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SIMULATION AND E-LEARNING TECHNOLOGIES.

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“Nicolae Bălcescu” Land Forces Academy

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Knowledge Based Organization 2008 International Conference

TECHNICAL SCIENCES

TABLE OF CONTENTS

Subsection 3: Computer Science, Modelling & Simulation and E-learning Technologies

Authentisierung in der Asynchronen Kommunikation bei Verteilten

Anwendungen, Reinhard Fössmeier, PhD, Cirquent GmbH, München, Akademio Internacia de la Sciencoj (AIS) San-Marino, München ...................... 9

Testing within e-Plasticity e-Learning Asynchron Solution in the Field of Elastic-Plastic Application of the Thick-Walled Tubes, Prof.Eng. Bârsan Ghiţă, PhD; Assoc.Prof. Giurgiu Luminiţa, PhD, Prof. Benoni Sfarlog, PhD, Asst.Prof. Gheorghe Motoc, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania................................................................................... 15

Generating, Testing and Assessing Learning Items within the e-Plasticity Educational Module, Assoc.Prof. Giurgiu Luminiţa, PhD, Prof.Eng. Bârsan Ghiţă, PhD, Asst.Prof. Bumbuc Ştefania, Asst.Prof. Moşteanu Danuţ, PhD, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania............................................................................................................... 26

The Impact of iPhone in Education, Assoc.Prof., Luminita Giurgiu, PhD, Prof. Ghita Barsan, PhD, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania .................................................................................................... 38

Important Concepts in the Economic Software Reliability Engineering, Assoc.Prof. Marian-Pompiliu Cristescu, PhD, Stud. Corina-Ioana Cristescu, ”Lucian Blaga” University of Sibiu, C.S.I.E. Faculty – A.S.E. Bucuresti.............................................................................................................. 43

Software Security for Enterprise. Security Risk, Assoc.Prof. Carmen Radut, PhD, Asst.Prof. Aurelian Has, University Constantin Brancoveanu, Pitesti, Romania................................................................................................... 51

A Guide on an IT Support for Historical Documents Collection in a Knowledge Based Organization, Cyb.ec.math. Florescu Gabriela, PhD, Eng. Florescu Valentin, National Institute for Research and Development in Informatics, Bucuresti ..................................................................................... 58

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E-Learning a New Method for Environments for 21st Century, Asst.Prof.Eng. Cornelia Victoria Anghel, PhD, Eftimie Murgu University of Reşiţa............................................................................................................... 66

Examples of Interdisciplinary Connections with the use of Computer Assisted Graphics Applicable to the Specialty of Military Technique, Asst.Prof.Eng. Horia Tarziu, PhD, Anamaria Comes, The Air Force Academy „Henri Coanda”, Brasov, The Main Foreign Language Learning Center in Brasov.................................................................................................. 73

Time & Attendance System with RFID Cards Containing User’s Fingerprint Templates, Eng. Nicolae Paraschiv*, PhD, 1st S.R. Eng. Toader Melinte**, Stud. Emil Pricop***, *Petroleum-Gas University of Ploieşti, ** S.C. SEEKTRON S.R.L., *** S.C. SEEKTRON S.R.L. ................ 79

Architecture of a Fuzzy Expert System used for Dyslalic Children Therapy, Asst.Prof. Eng. Ovidiu-Andrei Schipor, Prof. Stefan-Gheorghe Pentiuc, PhD, Asst.Prof. Doina-Maria Schipor, PhD, “Ştefan cel Mare” University, Suceava, Romania ............................................................................ 87

Serious Fun in Education: using Microbloging, Holotescu Carmen, Grosseck Gabriela, PhD, Technical University of Timişoara, West University of Timişoara ...................................................................................... 95

Modelling and Simulation in the Military Organisations, Vasile Căruţaşu, Daniela Căruţaşu, “Nicolae Bălcescu” Land Forces Academy.... 103

Decision Optimization in the Military Field, Vasile Căruţaşu, Daniela Căruţaşu, “Nicolae Bălcescu” Land Forces Academy .................................... 111

The Simulation of an Educational Platform, Asst.Prof. Mădălina Cărbureanu, Tutor Elia Petre, Petroleum-Gas University, Ploieşti............... 118

Forest Harvest Planning GIS Model, Asst.Prof. Aurelian Has, Assoc.Prof., Carmen Radut, University Constantin Brancoveanu, Pitesti, Romania............................................................................................................. 126

Candidate Face Detection from Color Images, Asst.Prof. Oancea Romana, Prof. Ştefan Demeter, PhD, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania................................................................................. 134

On the Application of the Artificial Neural Network Method To a Neural Simulator of Steam Turbine Power Plant, Asst.Prof.Eng, Liviu-Constantin Stan, Maritime University of Constanta, Romania ...................... 141

Reducing of Maritime Accidents Caused By Human Factors Using Simulators in Training Process, Asst.Prof.Eng, Liviu-Constantin Stan, Maritime University of Constanta, Romania .................................................... 149

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User Interfaces with Web Dynpro ABAP and Web Dynpro Java, Eng Cristea Ana Daniela, TA.Eng. Adela Diana Berdie, Asst.Prof. Osaci Mihaela, PhD, University Politehnica Timisoara, Timisoara .......................... 157

Using the MVDB Model’s Methodology and Arhitecture in Object-Oriented Databases Projects, Stud. Corina-Ioana Cristescu, Assoc.Prof. Marian-Pompiliu Cristescu, PhD, ”Lucian Blaga” University of Sibiu, C.S.I.E. Faculty – A.S.E. Bucuresti .................................................................. 165

Implications of Parallel Computing in the Optimization of Digital Image Processing Algorithms, Bogdan Vasilescu, Eng. Gabriel Rădulescu, PhD, Petroleum-Gas University of Ploiesti ...................................................... 173

Risk Management for Communication and Information Systems, Mioara Braboveanu, Bogdan Ciortoloman, National Registry Office for Classified Information....................................................................................... 181

Online vs. Offline in Modern Teaching, Eng. Gligorea Ilie, Prof.Eng. Ghiţă Bârsan, PhD “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania............................................................................................................. 190

Necessity of Using Modeling and Simulation in the Army, Coman Marian, “Nicolae Balcescu” Land Forces Academy, Sibiu............................. 196

Subsection 4: Physics, Mathematics and Chemistry

The Effects of the Far and Near Electromagnetic Field on the Human Body, CDR.Prof. Eng.Gheorghe Samoilescu, PhD, Prof.Eng. Alexandru Sotir, PhD, Assoc.Prof.Eng. Mircea Constantinescu, PhD, Asst.Prof. Alina Barbu, PhD, Eng. Florenţiu Deliu, “Mircea cel Bătrân” Naval Academy .................................................................................................................. 205

The Calculus of the Induced Current Density in a Reference Spire for the Protection of Onboard Personnel Exposed to an Electromagnetic Field, Cdr.Prof. Eng.Gheorghe Samoilescu, PhD, Prof.Eng. Alexandru Sotir, PhD, Assoc.Prof.Eng. Mircea Constantinescu, PhD, Asst.Prof. Alina Barbu, PhD, Eng. Florenţiu Deliu, “Mircea cel Bătrân” Naval Academy....... 211

Intentional Electromagnetic Interference and Electromagnetic Terrorism: a Review, Assoc.Prof. Miclaus Simona, PhD, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania .......................................... 217

A New Approach To Multi-Criteria Decision Making With Hierarchical Alternatives, Assoc.Prof. Ion Coltescu, PhD, Asst.Prof. Paul Vasiliu, PhD, Naval Academy “Mircea cel Batran”, Constanta ...................... 225

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Energetic Certificate for Buildings of the Ministry of Defense – a Necessity, Eng. Popescu Horia, Eng. Soare Mariana, Properties and Infrastructure Direction, Bucharest ................................................................... 232

Numerical Spectral Study for Viscous Temporal Stability of a Trailing Vortex, Dipl. Math. Diana-Alina Bistrian, Dipl. Math., Stefan Maksay, PhD, University ”Politehnica” of Timisoara, Faculty of Engineering Hunedoara ......................................................................................................... 241

Approximate Modeling of Degree 4 of Sliding Second Order Phenomena, Dipl. Math. Diana-Alina Bistrian, Dipl. Math. Stefan Maksay, PhD, University ”Politehnica” of Timisoara, Faculty of Engineering Hunedoara..................................................................................... 249

Optimization of Three-Dimensional Truncated Von Mises Modeling, Dipl. Math. Stefan Maksay, PhD, Dipl. Math. Diana-Alina Bistrian, University ”Politehnica” of Timisoara, Faculty of Engineering Hunedoara .... 255

Central Limit Theorem Analysis of Reliability of a Technical System with N-Components and the Mallows Distance Convergence, Assoc.Prof. Doru Luculescu, PhD, TA. Bogdan Gheorghe Munteanu, Air Forces Academy “Henri Coanda”, Brasov ................................................................... 263

The Optimizing of the Microwaves Hydrodistillation of Folium Menthae, Asst.Prof. Danut Mosteanu, PhD, “ Nicolae Balcescu” Land Forces Academy ................................................................................................ 267

Theoretical Studies on the Feasibility of Naval M.H.D Induction Propulsor, Asst.Prof. Grozeanu Silvestru, PhD, TA. Pazara Tiberiu, "Mircea cel Bătrân” Naval Academy, Constanţa.............................................. 275

About the Study of Ekman Currents on the Romanian Black Sea Shore, Angela Muntean, PhD, Mihai Bejan, PhD, Naval Academy „Mircea cel Bătrân” Constanta.............................................................................................. 283

An Error Analysis for a Quadrature Formula, Asst.Prof. Ana Maria Acu*, PhD, JrTA. Alina Baboş**, *“Lucian Blaga” University, Faculty of Sciences, Departament of Mathematics, Sibiu, Romania, **“Nicolae Balcescu” Land Forces Academy, Sibiu, Romania .......................................... 290

Particularities of the Electron Beams with a Rectagular Section, Prof. Raceanu Serban, PhD, Prof. Raceanu Felicia, Nationall College ,,Anastasescu”, Rosiorii de Vede ...................................................................... 298

Particularities of the Electron Beams with an Annular Section, Prof. Raceanu Serban, PhD, Prof. Raceanu Felicia, Nationall College ,,Anastasescu”, Rosiorii de Vede ...................................................................... 308

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Fractals Dimension, Design Methods and Measuring of Complexity, Asst.Prof. Daniela Cosma, “Nicolae Balcescu” Land Forces Academy, Sibiu, Romania .................................................................................................. 315

Solving Differential Equation with Mathematica, Asst.Prof. Andrea Minda*, Asst.Prof. Mihaela Tomescu**, TA. Diana Stoica***; *“Eftimie Murgu” University, Resita, Romania, **University of Petrosani, Romania, *** University “Politehnica” of Timişoara, The Faculty of Engineering of Hunedoara ......................................................................................................... 323

Use of Similarity Theory on Two Scales in the Study of Cavitation Phenomenon Generated At the Propellers, Ali Beazit, Sporis Adriana, “Mircea cel Bătrân” Naval Academy, Constanţa, Romania ............................. 330

High Performance Controllable Pitch Propellers for Low Acoustic Signatures, Ali Beazit, Sporis Adriana, Ali Levent, “Mircea cel Bătrân” Naval Academy, Constanţa, Romania .............................................................. 334

About Numerical Solutions and Conditioning of Lyapunov And Sylvester Type Equations, Asst.Prof. Ligia-Adriana Sporiş, PhD, Assoc.Prof.Eng. Beazit Ali, PhD, “Mircea cel Bătrân” Naval Academy, Constanţa, Romania .......................................................................................... 342

Activation of Metals, Chivu Florica, “Mircea cel Bătrân” Naval Academy, Constanţa, Romania ......................................................................... 348

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AUTHENTISIERUNG IN DER ASYNCHRONEN KOMMUNIKATION

BEI VERTEILTEN ANWENDUNGEN

Dr. Reinhard FÖSSMEIER

Cirquent GmbH, München, Akademio Internacia de la Sciencoj (AIS) San-Marino, München, DE, reinhard foessmeier.de

Abstract Asynchronous communication is an important technique for distributed

applications, as it eliminates unnecessary dependency between systems. In many cases it is to be considered an external service rather than part of an application. In these cases it constitutes a risk if it also performs security functions.

Nesinkrona komunik-ado estas grava tekniko en dis-tribuitaj aplikaĵoj, ĉar ĝi forigas nenecesan dependecon inter sis-temoj. Ofte ĝi estas konsideren-da pli kiel ekstera servo ol kiel parto de aplikaĵo. En tiaj okazoj estas risko, se ĝi plenumas ankaŭ sekurecajn funkciojn.

Comunicarea asincronă este o tehnică importantă pentru sistemele distribuite, pentru că elimină dependenţele de prisos între componentele. Deseori este considerată ca un serviciu extern, nu ca o parte a programului de aplicaţie. În acest caz este un risc, dacă umple şi funcţii de siguranţă.

Asynchrone Kommunikation ist eine wichtige Technik für verteilte Anwendun-gen, da sie unnötige Abhängigkei-ten zwischen Systemen vermeidet. Oft wird sie eher als externer Dienst denn als Teil der Anwen-dung betrachtet. In solchen Fällen ist es ein Risiko, wenn sie auch Si-cherheitsfunktionen übernimmt.

Keywords: asynchron, Warteschlange, Authentisierung

1. Einleitung Systeme zur asynchronen Kommunikation sind längst unverzicht-

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Knowledge Based Organization 2008 International Conference barer Bestandteil verteilter Systeme geworden. Als „Middleware“ entkoppeln sie Anwendungsteile dadurch voneinander, dass der Kommunikationsvorgang aus Sicht der sendenden Partei unabhängig von einer Reaktion der empfangenden rasch abgeschlossen ist. Das Warten auf die Annahme der Nachricht durch den Empfänger und die dadurch notwendige Zwischenspeicherung übernimmt die Middleware.

Solche asynchronen Verbindungen werden, wegen ihrer sequentiellen Arbeitsweise, als Warteschlangen (englisch: queues) bezeichnet. Bekannte Beispiele für Warteschlangensysteme sind Websphere MQ von IBM [2] und die quelloffene Plattform JBoss [3].

Aufgrund der Gefahren, denen jede Datenübertragung, selbst in gesicherten Intranetzen, ausgesetzt ist, bieten Warteschlangensysteme häufig eingebaute Sicherungstechniken zur Verschlüsselung und Authentisierung an, um sicherzustellen, dass übertragene Nachrichten nicht abgehört und Verfälschungen von Nachrichten sofort erkannt werden können. Diese Techniken sind analog denen in der Netzpost eingesetzten, bei der ja ebenfalls asynchrone Kommunikation vorliegt. Eine gute Beschreibung geben Tanenbaum und van Steen [4].

2. Bedeutung für die Zuverlässigkeit Im Vergleich zu synchroner Kommunikation weisen asynchron

gekoppelte Systeme vor allem eine erhöhte Zuverlässigkeit auf. Während eines von mehreren synchron gekoppelten Systemen durch seinen Ausfall andere Systeme auch dann lahm legen kann, wenn sie gar nicht auf die Dienste des ausgefallenen Systems angewiesen sind, beschränken sich die Abhängigkeiten bei der asynchronen Kopplung auf das funktional Notwendige.

Daher kann man bei asynchron gekoppelten System vielfach eine hohe Anforderung an die Verfügbarkeit feststellen.

Eine häufig vernachlässigte Eigenschaft asynchron gekoppelter Systeme ist, dass die Kopplung zwischen den Subsystemen und der Middleware notwendigerweise synchron ist: Erst wenn eine sendende.

Komponente eine Quittung von der Middleware bekommen hat, kann sie den Kommunikationsvorgang als (für sie) abgeschlossen betrachten. Wie Angerer und Erlacher [1] ausführen, wird damit die Verfügbarkeit des Gesamtsystems in hohem Grad durch die

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Knowledge Based Organization 2008 International Conference Zuverlässigkeit der Middleware bestimmt. Es ist daher nicht verwunderlich, dass diese Zuverlässigkeit das Hauptkriterium für die Qualität asynchroner Kommunikationssysteme darstellt.

In verteilten Systemen muss stets auch das verbindende Netz als Teil des Systems betrachtet werden. Auch seine Verfügbarkeit ist kritisch für das Gesamtsystem. Wegen der synchronen Kommunikation zwischen Teilsystemen und Middleware kann ein Ausfall der Verbindung zu Middleware ein Subsystem lahm legen. Es ist daher wichtig, solche Verbindungen zuverlässig auszulegen; dem wird häufig durch räumliche Nähe (Intranet) von Subsystem und Middleware („Queue-Manager“) Rechnung getragen.

Abbildung 1: Entkopplung durch mehrfache Queue-Manager Da bei zwei weit entfernten Subsystemen sich nur eines in der

Nähe des Queue-Managers befinden kann, werden manchmal zwei Queue-Manager eingesetzt, sodass jedes Subsystem einen in unmittelbarer Nähe haben kann. Abbildung 1 zeigt diese Situation. Damit werden die Auswirkungen von Ausfällen der langen Netzverbindung zwischen den Queue-Managern abgefangen.

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Abbildung 2: Senderseitiger Queue-Manager In solchen Situationen ist die Bedeutung der beiden Queue-

Manager jedoch sehr unterschiedlich: Während der beim Absender A platzierte Queue-Manager QA essentiell ist, um diesen von Ausfällen des Netzes zu entkoppeln, beschränkt sich der Nutzen des empfängerseitigen Queue-Managers QE auf den Fall, dass es sowohl im Netz als auch beim Empfänger E zu Ausfällen kommt: in diesem Fall kann er während eines Ausfalls des Empfängers Nachrichten von seinem Partner QA übernehmen und diese dann später an den Empfänger E leiten, selbst wenn zu diesem Zeitpunkt das Netz ausfallen sollte. Daher ist ein senderseitiger Queue-Manager, wie in Abbildung 2 gezeigt, meistens ausreichend.

Abbildung 3: Bidirektionale Kommunikation Diese Vorsorge ist nur bei recht häufigen Ausfällen sinnvoll.

Ansonsten genügt der senderseitige Queue-Manager QA, bei dem der Empfänger seine Nachrichten direkt abholt. Wenn die Kommunikation in beiden Richtungen stattfindet, sind zwar zwei

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Knowledge Based Organization 2008 International Conference Queue-Manager sinnvoll, es ist jedoch nicht notwendig, die Nachrichten über beide zu leiten. Diese Situation ist in Abbildung 3 dargestellt, wo die beiden Kommunikationsteilnehmer, wegen der symmetrischen Rollen, mit X und Y bezeichnet sind.

3. Die Vertrauenssituation Nach dem bisher Gesagten ist die Abhängigkeit verteilter Systeme

von der Zuverlässigkeit der Middleware offenkundig. Diese Abhängigkeit verführt häufig dazu, der Middleware auch Aufgaben aus dem Gebiet der Sicherheit zu übertragen, insbesondere die Verschlüsselung (Geheimhaltung) und Signierung (Authentisierung) der übertragenen Daten. Das bedeutet zwar Komfort für die beteiligten Subsysteme, setzt jedoch absolute Vertrauenswürdigkeit der Middleware voraus. Diese Vertrauenswürdigkeit mag bei Anwendungen, die in allen Teilen von einer einzigen Organisation betrieben werden, gegeben sein; das gilt jedoch nicht, wenn die Middleware von einem externen Dienstleister betrieben wird. Wohlstadter et al. [5] weisen daher darauf hin, dass nicht alle Funktionen einer Middleware zur Auslagerung an einen externen Anbieter geeignet sind.

Die Bereiche Vertraulichkeit und Authentizität gehören zu diesen Funktionen und sollten analog zum Bereich der Netzpost gehandhabt werden, wo sie ganz selbstverständlich nicht durch den Diensteanbieter wahrgenommen werden. Bei verteilten Anwendungen innerhalb eines mehrortigen Unternehmens oder Instituts ist die Verwaltung der benötigten Schlüssel unter Umständen intern möglich. Auch wenn der Dienst externer Zertifizierer (engl. Certifying Authority, CA) in Anspruch genommen wird, kann durch die Einbindung mehrerer CAs die Möglichkeit, dass eine einzige Stelle die Sicherheit des Systems gefährdet, ausgeschlossen werden.

4. Zusammenfassung Asynchrone Kommunikation erlaubt es, unnötige Abhängigkeiten

in verteilten Systemen zu beseitigen und damit deren Zuverlässigkeit zu erhöhen. Dabei muss auch das Netz als fehleranfällige Komponente berücksichtigt werden. Das kann den Einsatz mehrerer Middleware-Server an verschiedenen Orten erfordern.

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Middleware als (externer) Dienst erleichtert diese Verteilung, darf aber nicht dazu verführen, Sicherheitsaspekte ebenfalls an einen externen Anbieter auszulagern, der dadurch zu einer kritischen Schwachstelle im System würde.

Literatur

[1] Bernhard Angerer, Andreas Erlacher (2005): Loosely Coupled Communication and Coordination in Next-Generation Java Middleware, java.net, 06/03/2005. http://today.java.net/pub/a/today/2005/06/03/loose.html

[2] WebSphere MQ V6 Fundamentals (2005). International Business Machines Corporation 2005. www.redbooks.ibm.com/redbooks/pdfs/sg247128.pdf

[3] JBoss Enterprise Application Platform. Configuration Guide. Red Hat, Rayleigh, 2007. http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.3/doc/ Server_Configuration_Guide/html-single/

[4] Andrew S. Tanenbaum, Maarten van Steen (2007): Distributed Systems: Principles and Paradigms. Prentice Hall, Upper Saddle River, 2007.

[5] Eric Wohlstadter, T. Mikalsen, J. Diament, I. Rouvellou, S. Tai (2006): A Service-oriented Middleware for Runtime Web Services Interoperability. In: Proc. International Conference on Web Services, 2006.

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http://today.java.net/pub/a/today/2005/06/03/loose.html

http://today.java.net/pub/a/today/2005/06/03/loose.html

http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.3/doc/Server_Configuration_Guide/html-single/

http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.3/doc/Server_Configuration_Guide/html-single/


TESTING WITHIN E-PLASTICITY E-LEARNING ASYNCHRON

SOLUTION IN THE FIELD OF ELASTIC-PLASTIC APPLICATION OF THE THICK-WALLED TUBES

Prof.Eng. Bârsan Ghiţă, PhD, Assoc.Prof.Eng. Giurgiu Luminiţa,PhD Prof. Benoni Sfarlog, PhD, Asst.Prof. Gheorghe Motoc

Land Forces Academy, Sibiu, Romania, [email protected]

Abstract Advanced Distributed Learning (e-learning) is the most recent initiative

from a long campaign designated for developing the information technology advantages and the simulations during education and training performance. For different military and civil organizations, ADL has various meanings and it is applied in different ways. Defining it, a common fundamental request is compulsory, that is, ADL has to instruct and sustain the performance and decision, anytime and anywhere it is necessary: in the class rooms, in the garrison, or even on the training and battle field.

This paper presents testing designing aspects within the e-plasticity educational module, which represent a CNCSIS grant outcome, code 970/2007. This project aimed the Land Forces Academy educational side by elaborating an educational module for students, in the field of plasticity, actually, designing an e-content capability in the mechanical engineering field, which should lead to the constitution of the educational virtual library.

Keywords: e-learning, e-content, e-plasticity, asynchronous module 1. Introduction The implementation of the asynchronous e-plasticity e-learning

solution has been achieved in three stages. The first two stages aimed at generating learning items of the e-plasticity module, as wella testing and assessing the latter. In the last stage the training and

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administration specifications for e-plasticity module users have been elaborated.

The specialists team from the data processing field have chosen for designing the e-learning solution, the ToolBook Instructor base, which is a system creating complete courses allowing online learning applications’ design and distribution. The reason for choosing the ToolBook Instructor is the possibility to focus on the learning presentation material, fact that is most important. The ToolBook Instructor also helps creating and administrating the context, navigation, feedback and tests, which are a vital part of the interactive learning applications. Sound, animation, video, graphics, and other special effects can be easily added to the applications, making them interesting and in the same time entertaining. Hyperlink and navigation items allow students to control learning experience direction and tempo.

ToolBook Instructor is projected for a large variety of instructional designers. The ToolBook Instructor defining features, easy to use, quickly lead to the development of interactive quality courses. The most experienced ones will appreciate the ToolBook Instructor context-creation habitat, the Action Editor visual programming tool, the strong OpenScript programming language, and other various projection options ”as is”.

2. The TEST Module One of the elements sustaining the e-plasticity educational

module is the TEST module. An important part in designing a course is the assessing ability of the user’s learning means regarding the presented material. For assistance in this request, the ToolBook Instructor offers question items used for students’ knowledge tests.

Question items allow the design of different types of questions, including multiple choice, true/false, fill in the blanks, choose correspondent, and other answers. The question items determine the answers given by users, calculates the scores and offers feedback. The dialog window features of a question, vary a little bit according to the question item type, but the majority of the question items allow the following:

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- Each possible answer should be recognized; - Which answer is correct; - How many times the student can answer a question; - The assessment options of a score for a certain question; - Feedback options for the student; The ToolBook Instructor Catalog contains a rich variety of

question items which help the interactive learning assessment offered by the application. Some of these are in the following described:

A designed question using an item arrangement. An item that arranges items, allows the specification of item adequate position in a page and student knowledge about positions testing. When the book is running, the objects are mixed on the page, and the student will try to arrange them in the order specified by the designer using drag-and-drop. A student’s score is based on the number of correct positioned items.

A designed question using a “drag item”-type question. A “drag” item question allows the items’ definition as potential answers and the students’ capacity to identify correct answers testing. The student picks out an answer by dragging items over a pre-established potential answer (Fig.1).

Fig.1 – “Drag item” question

A designed question using a drop-target item. A drop-target item

allows the definition of items as potential answers and the students’ ability testing to identify correct answers. The student chooses the

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answer by dragging an item over the drop-target item. The drop-target item is typically an image of a container or a target. This question item is used when the correct answer allows the student to put more items in a single target.

A designed question using a fill-in-the-blanks item. Such an item allows defining a word or a phrase as a correct answer to a question. The student tries to answer the question in the item answer area (Fig. 2).

A designed question using a match-things item. This item allows defining thing couples as correct answers and testing students’ capabilities to identify the correct couples. The student tries to match the correct things by tracing an arrow from one item to the matching one (Fig. 3).

Fig.2 – “Fill in the blanks” question Fig.3 – “Match item” question A designed question using a multiple choice item. A multiple

choice item allows defining a button, field or another item as a correct answer. The student tries to answer the question by clicking the button, filed or item. Using this object, many correct answers can be selected (Fig. 4), also specified not to take the position into account (the correct answer appears in another place at each try).

A designed question using an order-text item. Such an item allows defining a word or phrase ordered list as a correct answer for a question and testing the student’s ability to reconstruct the list in correct order. The student tries to answer the question by dragging the phrases in the correct order.

Score questions. Besides indicating the correct answer, the

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question can be set to calculate the student’s score. After each question, the student’s score can be presented, at the end of the book or it can be registered in a log file. This text type file will include information, such as the student’s score, the answer to each question, time spent on a page. The instructor can also report the score in a learning management system, which can keep the student’s score in a data base so that the administrator can examine it later. The importance/weight attribution of an answer is an aspect with novelty elements. With the most item questions a weight can be attributed to each answer (Fig. 5).

The weight is a percentage from the possible points for each question. For instance, with the help of a fill-in-the-blanks question, different weights can be attributed to the different answer possibilities. This attribution can be also designated to the implicit features of the question dialog window, according to the type of question and the number of answers.

From its design, the difficulty of a correct answer is 100% if the question has only one answer and a fraction of 100% if there are more possible answers. The difficulty is automatically actualized as the correct or incorrect answers are cataloged.

Fig. 4 – “Multiple choice” question Fig. 5 – Answer weight attribution

For question items which can recognize only one answer at a

certain time, such as the fill-in-the-blanks or classify acc. to the multiple choice type, a greater difficulty can be attributed to the most wanted answers and a smaller one, for other answers.

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A feedback also can be associated to question items, which determines the item answer means when the student interacts with it. For example, when a student chooses the correct answer to a multiple choice question, the question item can present the message “correct” (Fig. 6).

Offering feedback to a student allows an interaction with an increased quality, which leads to a better retention. Feedback, in a traditional way, is used in computerized training for offering students answers and solutions regarding how good they answer a question. But, feedback is also useful for other purposes, like the guidance of a student through a request or application.

If a score test is created, the immediate feedback doesn’t have to be used for informing the user if the answer try is or is not correct. The Instructor does not take in account an answer try with an immediate feedback as a true try. An immediate feedback question will be assessed as if the student would have chosen the correct answer from his first try, although he needed three tries in finding the correct answer.

Fig.6 – Attaching feedback to the answers of a question

In the educational module immediate feedback has been used

then, when the evidence track of a question wasn’t planed or “correct” or “try again” type feedback was required with each student’s answer

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or try. Delayed feedback has been used, when: a) a test question was

taken in account, through score calculus; b) feedback was required then, when the student had finished answering the questions; c) “All correct”, “all incorrect”, “partially correct” feedback was required.

The e-plasticity educational module combines exercise with demonstration and evaluation. The exercise is interactive and allows the students to experiment with buttons, menus, text introduction fields or other items in a simulated interface (Fig. 7). The demonstration shows the student how to fill in an online request and it doesn’t need input data or interaction (Fig. 8). Eventually, the assessment, designed in a test shape, offers the student a single chance to fill in each step in a simulated request (Fig. 9).

In the selection of a distribution option on the internet there was taken in account the fact that this should reflect the developer’s and the user’s requests. Hence, the following have to be considered:

• The Instructor includes the option of an automatic exportation of the book designed in DHTML format, format that allows the authors to set actions for buttons and answers to questions, to release events, to use conditions and iteration loops, and other interactive elements (Fig. 10).

Fig. 7 Buttons interactive exercise Fig. 8 No interactive elements demo

• Browser technology, older versions of the Web browsers (older

than 4.0) don not support DHTML. A distribution method will be selected, which is advantaged by the used technology;

• Necessary components, if the DHTML export isn’t selected, a

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ToolBook application can be sent in a web browser using Neuron browser plug-in. The students have to have Neuron installed on each machine so that the native file .tbk can be visualized in the browser.

Fig. 9–Single chance assessment- Fig.10–Export option

“cannot change responses” setting • The application’s exportation as a series of DHTML web pages

allows students with internet access to visualize the e-plasticity educational module in a web browser with no Neuron browser plug-in. Using the DHTML format allows the maximizing of the interactivity – including Actions Editor programmed behavior, but older versions of browsers do not support DHTML. The dynamic HTML or the DHTML, adds to the HTML the ability to create interactive features, such as buttons that respond to click, running text, animations and many others. The items programmed from the catalog have these features incorporated. ToolBook Web Specialist automatically converts the application in web pages using DHTML. Exporting from the Instructor into the DHTML creates web pages that are personalized for Microsoft Internet Explorer and Netscape Navigator. When exporting in DHTML the majority of features and items will appear and act the same as in the Instructor.

When designing a native ToolBook application that users can see in a web browser with Neuron browser plug-in, the entire set of features, that the Instructor possesses, can be used. The native ToolBook applications can include pre-established interactive features, such as those created with OpenScript. The users download

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and install Neuron browser, and the ToolBool applications are run in a web browser on a computer. Neuron is compatible with Microsoft Internet Explorer, Firefox and Netscape browsers that run on a Windows base. Neuron can also help maintain security while running an internet application. Because the ToolBook applications are executable, they can interact with the computer, safety measures should be taken, then, when files from an unknown source are accessed. Hence, Neuron has two access ways: secured and unsecured. The unsecured option is used, when ToolBook applications created by redoubtable developers, are accessed, and the secured option when unfamiliar applications are accessed. In the secured mode, Neuron won’t allow links towards system files and will not execute commands, such as Save, Delete, or other actions that might affect the system.

The project team selected the e-plasticity application designing for DHTML export.

The factors affecting a DHTML application exported in a web browser are: internet connectivity speed, media files size in applications and page design complexity, all of these contributing to the application’s downloading necessary time. The application’s running necessary time in a web browser can be reduced by creating a book designed to use media items and files in an efficient way.

For reducing the necessary time to visualize applications in a web browser, the following have been used: a book base, the smallest possible number of frames, the number of items on a page has been limited, graphical elements small in size, placeholder type items from the catalog in order to visualize media files.

During the development of the e-plasticity module, the book was periodically exported in DHTML and the result was assessed in a web browser.

In order to run an application in a web browser using Neuron plug-in, a HTML page has to be created, one that contains a link to the native file .tbk (for running an optimized application using Impulse, a HTML page is created with a link to the file segment with the tbk extension).

In this perspective, the ToolBook e-plasticity educational module

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can be transmitted through the internet and can use any learning management system (LMS – Learning Management System) in compliance with SCORM and AICC standards, for registering the students’ scores for the questions’ answers. By adding evaluation buttons the results can be sent to a data base which is controlled by the LMS.

3. Conclusions The asynchronous e-plasticity e-learning solution, designed and

implemented, places the Land Forces Academy on high-standard positions in promoting e-content. The suggested project is in the following inscribed:

- The tendency outlined in the research by the European Union Roadmap of the European Technology Platform for Advanced Engineering Materials and Technologies, 27th June 2006, Grand Challenges and the Vision: Materials for the Life-Cycle and Vision for 2020;

- The e-learning initiative: Designing Tomorrow’s Education, integrate part of the Europe Action Plan, adopted on the 24th of May 2004 in Lisbon, figuring the knowledge triangle out: research, education and innovation, the main factor in the European Union strategic objective’s achievement.

What’s next? New transformation means for our lives have appeared, through digital technologies and, in the last years, we have witnessed the appearance of new tools and services. Some of these were presented as Web 2.0, others as social soft. Meaningful attributes that these tools and services present, are about the knowledge creation, the knowledge management, the knowledge match and the knowledge spread. Keywords were: creation, collaboration and communication. These technologies change the way we deal with knowledge. The ones implied in education raise two issues: first of all, these provide the learning process with new tools and means useful in sustaining education, and second of all, they suggest that, due to the changing nature of human knowledge management, it is necessary to change our priorities regarding things we need to learn.

It is important to notice the fact that the social soft provides a

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mechanism for the educational transformation, attaching these technologies to the educational advantage accomplishment.

Acknowledgements This study is a part of the 970/2007 CNSIS scientific project

funded by the Ministry of Education, Research and Young.

References [1] Ioan, Cerghit, Sisteme de instruire alternative şi complementare. Structuri,

stiluri, strategii. Bucharest, Aramis Publishing House, 2002. [2] Ioan Cerghit; Metode de învăţământ, Bucharest, Polirom Publishing House,

2006 [3] D., French; Internet Based Learning. An Introduction and Framework on

Higher Education and Business. London, Kogan Page, 1999 [4] Borje, Holmberg; A Theory of Distance Education Based on Empathy, in

Distance Education in Essence. Oldenburg University. 2001. [5] M.G., Moore; G., Anderson; Hanbook for Distance Education, New Jersey,

Laurence Erlbaum Associates, 2003. [6] S., Naidu; Designing Instruction for e-Learning Environment, Handbook for

Distance Education, Lawrence Erlbaum Associates, New Jersey, p. 349-367; 2003.

[7] Otto, Peters; Learning with New Media in DIstance Education, New Jersey, Lawrence Erlbaum Associated, 2003

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GENERATING, TESTING AND ASSESSING LEARNING ITEMS WITHIN THE

E-PLASTICITY EDUCATIONAL MODULE

Assoc.Prof. Giurgiu Luminiţa,PhD, Prof.Eng. Bârsan Ghiţă, PhD, Asst.Prof. Bumbuc Ştefania, Asst.Prof. Moşteanu Danuţ, PhD


Abstract The paper presents relevant aspects in the process of projecting,

generating, testing and assessing the learning items belonging to the asynchronous solution within the e-plasticity educational module.

For the e-learning solution projection, the ToolBook Instructor platform, which is a system that creates complete courses permitting the creation and distribution of online study applications, has been chosen.

The projected educational module represents the outcome of the CNCSIS grant code 970/2007, project that aimed at developing e-learning field related capabilities gathered until the present and at developing an e-content capability in the mechanical engineering field, which will lead to the constitution of an educational items system within the virtual library.

Keywords: e-learning, e-content, e-plasticity, asynchronous module

1. Introduction The reason for choosing the ToolBook Instructor is the possibility

to focus upon the study material presentation, which is the most important thing. ToolBook Instructor also helps creating and administrating the context, the navigation, the feedback and tests, which are a great vital part of the interactive learning applications. Sound, animation, video, graphics and other special effects can be easily added to the applications, making them interesting and in the

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same time entertaining. Hyperlink and navigation items allow students to control the learning experience direction and tempo.

ToolBook Instructor is projected for a large variety of instructional designers. The ToolBook Instructor defining features, easy to use, quickly lead to the development of interactive quality courses. The most experienced ones will appreciate the ToolBook Instructor context-creation habitat, the Action Editor visual programming tool, the strong OpenScript programming language, and other various projection options.

After creating a course using Instructor, this can be distributed to any student with internet access, or through the university’s intranet, using the flexible send options. The students can visualize the course either through a HTML-format (Hypertext Markup Language) web browser, or through the Neuron plug-in, in order to make the course look like a ToolBook (native file .tbk) book in a web browser. The course distribution like a run-time application accessible from the hard disk or CD-ROM is possible.

The ToolBook package contains: • ToolBook Assistant – designed for easy use. The Assistant

includes a rich variety of drawing and graphic basic items, and pre-programmed items with enlarged capabilities. Its intuitive interface is ideal for those who want to quickly create interactive learning applications – without the need of programming.

• ToolBook Instructor – designed for flexible creation of the learning applications with a rich content. The Instructor includes the possibility to totally personalize the application using the Actions Editor visual programming tool and the OpenScript programming language. Items can be personalized using these tools and, than, these are saved in the Catalog in order to be used in the Instructor and Assistant.

• ToolBook Neuron is free of charge if accessed as plug-in for browser or ActiveX control. It allows the access and running of native ToolBook Instructor and Assistant applications in Netscape Navigator and Microsoft Internet Explorer browsers. The ToolBook native application performance optimization using Impulse for Neuron is a post-process utility which divides the book for quick data internet

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transfer. Therefore, ToolBook Instructor is a program that creates courses and allows course developers and instructional designers to create, personalize and send learning applications online. The Instructor creates dynamic and interactive courses and implies the student to use sound, animation, video, graphics, and other special effects.

ToolBook Instructor has special designed features that allow the creation of online courses for educational training. A variety of courses can be created, such as simulations, interactive demonstrations and guide tours.

2. The implementation plan The solution implementation plan contained: - Generating, testing and assessing the learning items by the

instructional designers team; - The solution package and its visualization by the mechanical

engineering and pedagogy teams; - Impact testing of the e-learning solution on student teams within

the data processing students’ group. Each student expressed his point of view in written, outlining impressive elements or ones that need improvement;

- Suggestions’ implementation in the educational module and its testing on the three study groups;

- The educational module covering by the 1st group, with the teacher’s assistance, gathered knowledge assessment and impact form application;

- The educational module covering by the 2nd group, asynchrony, gathered knowledge assessment and impact form application;

- Analysis of the obtained results and form answers; - Solution re-design and the educational module covering by the

3rd group, asynchrony, gathered knowledge assessment and impact form application;

- Educational module package for its distribution to potential users.

From the received answers analysis interventions on e-plasticity educational module have been executed, these aiming at:

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- The interactivity increase of the online study solution: an interactive online learning application offers computerized training that reacts to the students’ actions. The ToolBook Instructor application presents information, and tests students storing their answers, reveals clues, recognizes correct answers and assesses the lesson to lesson progress.

- Project planning: a good project planning helps using the sophisticated program features and the strong distribution capabilities that the ToolBook Instructor offers. This section aimed at specific problems regarding file organizing and their distribution.

- Send course means decision: perhaps the most important decision to make before starting an application is the means to send the course to the students: using the internet or intranet, a local network, or a CD-ROM.

- Application build up means: within the Instructor, an application is constructed by beginning a book and filling in its contents: text, interactive items, graphics, navigation, a.o. The visualization module and the item behavior can be controlled through the owner’s setting. The Action Editor visual programming tool can also control the items’ behavior, or the OpenScript language can be used in books that won’t be exported in DHTML. The application creation will be made at the author’s level, the students interacting with these at a reader’s level.

- The difference between author level and reader level: The ToolBook Instructor has two operating levels: author and reader. At the author level, applications are created and changed using development tools, such as templates, the ToolBook catalog, dialogue frames, etc. At this level, characteristics of the created and changed items can be established in order to define aspect and behavior (Fig. 1).

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Fig.1 – ToolBook Instructor window application – author level

The reader level is the level at which the applications are

measured in regard to their development, being altogether the level at which the students use these applications by navigating the pages, completing the text in fields, answering interactive questions and releasing events (Fig.2).

Fig.2 – ToolBook Instructor window application – reader level

Generating learning items: the online e-plasticity learning

application, created with the ToolBook Instructor, consists of many files called books. These were arranged so to create a sequence course. In the online book, each screen is considered a separate page. The pages contain elements that determine the application’s visualization and behavior – buttons, graphics, text, media players, etc. The pages were arranged in a specific order given by the delivered draft material correlation and than, a navigation means was implemented between pages, and has at its base study elements regarding psycho-pedagogical methods in e-learning. Other

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intervention elements contained: - Redesigning more pages with the same background and placing

the items on the background so that the maintaining of a consistent arrangement is permitted along the book.

- The main Instructor window reveals a single page. Pages can be created in order for the window to appear once with the main window. These windows, called visions, can be small, like a pop-up window, or bigger as the main one.

- All visual application elements – buttons, text, graphics, pages and backgrounds – are items.

- Using the Actions Editor tool. Actions Editor is a visual programming tool used for creating sophisticated interactive courses without the need of proper programming in OpenScript, the programming language for the ToolBook. The Actions Editor is designed to offer non-designers the control level of a programmer upon item behavior and also to offer the programmers the creating behaviors tool for Web export (Fig. 3).

Fig.3 – Action Editor while constructing the “Procedure types” page

- Using OpenScript, the programming language for the ToolBook.

Designing in the OpenScript language, the visualization mode and item behavior are defined. For example, what exactly is going on can be controlled when a student executes click on a button, access a page, or chooses a selection in a list. A lot of these features can be controlled using Actions Editor, or the catalog items with

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preprogrammed behaviors, hence more means to end a request. - Resource using within applications. The application interface

visualization mode personalization has been designed by resource importation such as icons, graphics, fonts and colors (Fig.4).

Fig.4 – Resource importing – characteristic diagram graphic

- Visual interface: designed for easy use, the visual interface

allows focusing on important requests for contents presentation and students’ results assessing. The instructor has two working levels: author and reader. At the author level, applications are build up using development tools, such as catalog, Book Explorer, colors, toolbar. With these tools, books are build up, items in the page are created and changed, interactive behaviors are added to applications. At the reader level, the application is tested in order to see the users’ perception. The users will use the application at the reader level, where they can navigate pages, answer questions and release events.

- Navigating the application: in the module there are more navigating means incorporated. The catalog Instructor navigation items have been used, the navigation behaviors have been implemented to buttons using Actions Editor, or navigation tools from the two author and reader levels have been incorporated. Specifications are made, that certain pages should be skipped, conditions to directly jump to a certain page or a Uniform Resource Locator (URL), or a transitional effect between pages has been imposed.

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The elements that the study groups have identified as efficient, are:

- The jump/moving from page to page using the menus and buttons from the status bar or keyboard;

- The intuitive environment and drag-and-drop capabilities in the design of the book pages;

- The hyperlinks that allow users to move from page to page. This way, a user can visualize a page within another application or one that stands outside the normal page sequence (Fig. 5).

- Items on a page have hyperlink predefined capabilities, allowing idea, information and topic connection. Hyperlinks allowing the navigation to another common page or to another pop-up page, are used. Interesting is the fact that all students have shown that a hyperlink is useful in the technical contents presentation to the beginner and expert users. For example, by using hot-words for technical terms in the module contents, which, once activated, opens a window containing either the term’s definition or the associated image (Fig. 6).

- The item visual aspect changing through the style change of the line, color and filling pattern. This allows the implementation in the application of a color pattern that will appear as a interface integrated part;

Fig.5 – Hyperlink linked with the TEST button – jumps in the test file

- The text-information correlation. Text fields or registration

fields used for transmitting information and instructions are added to the e-plasticity module. Also, graphic elements are added inside the

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items, and fields for capture visual interest upon the text. Navigation is intuitive, a click can be executed on a text field, on an image, in a menu, on a button or icon, the keyboard can be used;

Fig. 5 – Hot-words hyperlink

- Adding buttons and hot-words to the application for users to

interact with it. A button of the ToolBook Instructor, like any other Windows button, is an item that the user can click with the mouse in order to release an event. A hot-word is a text selection that the user can mouse click like a button. Buttons and hot-words can be used for page navigation, as control for option setting, for starting or ending an animation, for running a video sequence, etc.

- Visual effects creation. Visual effects – such as hiding, appearing, item animation – make the ToolBook Instructor application look dynamic, interesting and entertaining. For creating these effects, the following were used: ToolBook Animation Editor for designing animations for trajectory or shape based items, Action Editor for projecting sequence actions of hiding, revealing or item animations as an answer to certain conditions, and OpenScript for changing item position, size, or shape, or for posting a changing set of pictures which gives the illusion of movement.

- Instructor item animation. Animation can add visual impact to the learning application and illustrates the mode in which the things change or move once with time passing;

- Digital media inserting: audio, video, animation and graphics are

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all kinds of media that can be incorporated in an online learning application. The media attach interest to any page, making the learning experience dynamic and efficient. Within the application, a video file has been used in a compatible format exportable in DHTML format (Fig. 7);

Fig.7 – Digital media inserting

- Using Actions Editor, a visual programming tool within the

ToolBook Instructor. This option presents familiar interface elements – such as menu and tool bar – which were used to add sophisticated interactive behaviors to application items (Fig. 8).

- The sequence actions designed in Actions Editor can be automatically exported in DHTML using ToolBook Web Specialist. Each sequence action contains one or more behaviors that the Instructor fulfills in the order specified by the designer. Sequence actions are created to require the user input data, to change the characteristics of an item, to run media, and many others. Sequence actions can be projected for programming the behavior of any object added in the Instructor application. A sequence action for an object answers to a specific event. The sequence actions are constituted from various actions that are grouped in three functional types: actions, conditions and iteration loops. The actions add behavior to the application, the conditions specify the circumstances in which the actions have an effect, and the iteration loops repeat the action. Each designed sequence action has to include at least one action that isn’t a condition or iteration loop. Designed sequence actions can be added to the iteration loop for running an action or a series of actions in a repetitive mode. A pas iteration loop runs the same action or actions a

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certain number of times. A conditioned iteration loop runs the same action or actions until a condition is achieved. For instance, if the user is required to enter input data until he succeeds at giving the right answer, such a conditional iteration loop can be used.

Fig.8 – Adding interactive behaviors to items

- Resource using. The resource is a file that can be used several

times in the ToolBook Instructor application. When a resource is added to a book, the Instructor places its copy in the Resource Manager, which is a common resource bookstore from a book. The resources are than accessible to all book items that can use that kind of a resource; the resource does not appear in the book until it is attributed to an item as a property. Resources were used for: applying a button graphic, replacing the normal cursor with one belonging to the ToolBook system, changing the drag image of the cursor, adding an icon appearing when the application is minimized, adding a menu bar that appears in different application windows, identifying a common script that is used by several application items.

3. CONCLUSIONS Obviously, e-learning solutions in the mechanical engineering

field can be spectacular as design but very hard to implement. The field concerns of the Interdisciplinary Engineering Department within the Missouri University can be considered as model in the field. The Mechanics of Materials can be visualized under the

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http://web.umr.edu/~mecmovie/index.html address. The year 2004 implied e-learning products in the field of mechanical engineering of the Interdisciplinary Engineering Department, through the prize awarded to Timothy A. Philpot and its team, formed by Richard Hall, David B. Oglesby, Nancy Hubing, Ralph E. Flori, Vikas Yellamraju.

The asynchronous designed and implemented e-learning solution, places the Land Forces Academy on advanced positions in promoting e-content.

References

[1] I., Cerghit; Sisteme de instruire alternative si complementare. Structuri, stiluri, strategii; Bucharest; Aramis Publishing House; 2002.

[2] D., French; internet Based Learning: An Introduction and Framework on Higher Education and Business; London; Kogan Page; 1999.

[3] Borje, Holmberg; A Theory of Distance Education Based on Empathy; in Distance Education in Essence; Oldenburg University, 2001.

[4] M.G., Moore; G., Anderson; Handbook for Distance Education, New Jersey, Lawrence Erlbaum Associates; 2003.

[5] S., Naidu; Designing Instruction for e-Learning Environment, in Handbook of Distance Education; Lawrence Erlbaum Associates; New Jersey; 2003.

[6] Otto, Peters; Learning with New Media in Distance Education; New Jersey, Lawrence Erlbaum Associates, 2003.

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THE IMPACT OF iPHONE IN EDUCATION

Assoc.Prof. Luminita Giurgiu, PhD, Prof. Ghita Barsan, PhD


Abstract Into the Cyber-market a new gadget has arrived - the iPhone; it is a typical

smart phone with e-mail, calendar, SMS, photo, music, and Internet support. That in itself isn't so extraordinary because most smart phones come with that nowadays, but what people are really raging about is the interface, it combines three products in one — a revolutionary phone, a widescreen iPod, and a breakthrough Internet device with rich HTML email and a desktop-class web browser. How will this new device impact education? This article is trying to notice what new features does it introduce and how will those be important to students and teachers.

Keywords: iPhone, education, smart phones, web applications

1. Introduction Clearly the immediate impact of iPhone is small. After all, it's

hard to imagine a significant portion of students or faculty will have an iPhone in the next year.

However, iPhone does give us a glimpse into a new era of networked media. iPhone does give us a sense of how it might be possible to have a workable desktop on a phone. If it is possible to have fully functional web access, then it is not hard to imagine fully-functional web-based applications. Looking back 6-7 years to 2001, we see iPod's didn't exist, blogging was around but few people did it, Wikipedia had just begun.

What if we imagine that the kind of technology we're talking about takes six years to become as widely adopted as iPods, blogs,

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and wikipedia? That would seem to suggest that over the next six years

successful colleges will be ones that have moved to a fully mobile, networked curriculum and pedagogy…

2. Impact features Here are three features [1] that I believe will impact education. a. Multi-Touch Display The most promising technology is the multi-touch display. In this

case, it is the technology that will make the difference, especially in the long run. Multi-touch displays are not a new technology, people have been working on this since the 80’s and recently Microsoft announced their similar “Surface1” computer. What is unique here is the mass production of a multi-touch device. The iPhone will be the first multi-touch device in the hands of millions of people.

A very interesting presentation of this technology was made by Jeff Han2 some years ago. He said that he thinks this is going to change the way we interact with machines from now on, and he was right.

Interaction with the computer in a much easier and more human-like manner through this new interface is going to be the jumping off point for a whole new generation of computing. As more and more data becomes available on computers this will be the first technology that will help us to better manage that information.

From a mobile perspective, it has always been a hassle to use a mobile device. Perhaps the multi-touch display will be the missing link for actually using a mobile device in the classroom.

The iPhone interface is very good explained in Apple iPhone Ad: This is How 3.

b. Widgets Computer users are already familiar with the wonderful world of

widgets. Widgets are most easily categorized as mini-applications: they can be anything and everything from simply displaying the weather and RSS feeds, to fully functional translation devices. There

1 http://www.microsoft.com/surface/index.html 2 http://www.edutechie.com/2006/12/computer-interaction-of-the-future/ 3 http://www.youtube.com/watch?v=tH0-GKBmOE8

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are thousands, tens of thousands of widgets out there: in the Information1 and Reference2 categories for Macs alone there are over 300 widgets.

Educators and students can use the widgets and build others that can easily be added to the iPhone thus capitalizing on the mobility factor.

c. iPhone Applications and a Fully Functional/Easily Browsable Internet

One of the iPhone's drawing points is that it runs a full browser. This is going to be important and this is going to open the flood

gates of creativity: the power of a multi-touch display could be used in a test by allowing students to more naturally interact and manipulate the test and then send it back to professor over the air, anywhere.

A fully-functional browser, and most importantly, easily-browsable internet will finally allow rich multimedia, and navigation that has been impossible before. Browsing the internet on a mobile device, up till now, was terrible. If the page wasn’t formatted in mobile format, forget it. Now students and teachers can really interact with the internet, and best of all manipulate it.

As it stands right now, there is no high speed internet over the cell signal (G3), but there is built in WiFi and things are going to be added on and prices are going to drop.

Most relevant to education is the price. Right now it costs approximate $450 for a 8GB model and $590 for an 16GB model. That is awfully pricey for an educational tool, and it certainly going to be a long time before most of us educators gets our hands on one, let alone enough students to design lesson plans around having one. But what to say about the new Microsoft “Surface” devices that are going to cost around $10,000? If it would be possible to afford one per school or organization, a multi-touch display could be shared among a lot of people…

d. On the other hand, Apple is presenting new flash cards with teaching, learning and selling purposes, tridimensional images of

1 http://www.apple.com/downloads/dashboard/information/ 2 http://www.apple.com/downloads/dashboard/reference/

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Knowledge Based Organization 2008 International Conference atoms, stars, constellations, together with reading books, are available on a range that goes from 40 dollars to no cost (totally free) through the App Store. Most of these are flash-card programs that iPhone users can download by accessing the App Store through Apple's iTunes software and clicking on the "education" category.

Other companies as Modality Inc. and Accela Study are also making there own programs for the iPhone in their respective field of knowledge.

So, it seems that flash cards in iPhones are the future of education.

3. Other‘s experience Kevin Roberts is chief information officer and director of re-

engineering at Abilene Christian University, in Texas. He has worked on the university's complete transition to Google Apps for Education and overseen experiments in group learning using various Google applications. He also has pushed for mobile computing, providing free iPhones to faculty members and students to create and complete course work from anywhere on the campus.

A very interesting discussion about his experiences that could serve as models for other institutions can be found in the Chronicle of Higher Education [1]. The reaction to those changes on his campus and how students and faculty members have different views are topics to think about.

Even if they have been looking at the idea of mobile learning for many years, it was certainly not anything new to their campus, fig. 1.

The combination of a mobile device and a fully functioning web browser made them felt like that combination is powerful and compelling as long as these are used as educational tools.

The Google Apps students have found to be most useful were the email app (the most widely used), the chat feature and calendar, and faculty members have commented on the value in the collaborative features built into docs and spreadsheets.

Kevin Roberts do not envision students doing all their coursework on their iPhone. However, it can be used as a handy field research device. It can be used to make notes, take photos, record podcasts, etc.

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It is often easy to assume that these devices will replace a computer, but isn’t the case at all. Considering them as augmenting the existing technology landscape, the next step is trying to demonstrate best practice uses.

Figure 1 iPhone in education

4. Summary The iPhone can be an incredible tool to support learning. The

tablet PC in the palm of our hand, complete with OS X and wifi access, it has all of the features wanted in a cell phone, iPod and handheld Internet device.

This device could be put into the service of learning: online simulations, games, learning objects, widgets, blogs, a built-in digital camera to collect images, his capabilities could far exceed the way Palms are currently being used in education today.

The mayor advantage of the I-Phone is its portability, we can take it anywhere at anytime, and do the learning experience whenever we want and wherever we need it, and this is freedom.

References

[1] http://chronicle.com/live/2008/04/roberts/[2] http://electronicportfolios.org/blog/2007/01/apples-iphone-in-education.html[3] http://olliebray.typepad.com/olliebraycom/2008/10/iphone-in-education-5-

of-5-earthscape.html[4] http://www.iphoneappreview.com/category/general-applications/education[5] http://www.quazen.com/Shopping/Consumer-Electronics/iPhone-

Education.227427

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http://chronicle.com/live/2008/04/roberts/

http://electronicportfolios.org/blog/2007/01/apples-iphone-in-education.html

http://olliebray.typepad.com/olliebraycom/2008/10/iphone-in-education-5-of-5-earthscape.html

http://olliebray.typepad.com/olliebraycom/2008/10/iphone-in-education-5-of-5-earthscape.html

http://www.iphoneappreview.com/category/general-applications/education

http://www.quazen.com/Shopping/Consumer-Electronics/iPhone-Education.227427

http://www.quazen.com/Shopping/Consumer-Electronics/iPhone-Education.227427


IMPORTANT CONCEPTS IN THE ECONOMIC SOFTWARE RELIABILITY ENGINEERING

Assoc. Prof. Marian-Pompiliu CRISTESCU, PhD Student Corina-Ioana CRISTESCU

”Lucian Blaga” University of Sibiu mp_ @yahoo.comcristescu C.S.I.E. Faculty – A.S.E. Bucuresti ci_ @yahoo.comcristescu

Abstract:

In the study of software, reliability is important to know the difference between error, defect and defection. This three terms are often confounds and, are often used with the same sense but they have different meanings. Usually, a defect occurs when system behaviour moves off from the demands. The defect can be studied also by prism of failure operations, so is defined as an incomplete operation. The defect is the cause of lot of defections because the variety of inputs makes that the programs system behave in a different way. Defect cause the defection. Because software depreciates in other way than hardware, the software reliability stay constant in time if we don’t operate changes in the source code or at the environment conditions level, inclusive at the user behaviour. However, if every time when a defection was rectified, and the defect that was the main cause is eliminate, then reliability will increase in ratio with time. This is a usual situation for the probation phase.

Keywords: software reliability, reliability modeling, software cost, error, failure

1. Introduction The software quality contains a set of different properties. One of

the most important is represent by the reliability. A straight approach of the reliability supposes its orientation rather to the user than to the software development process. This approach derives from the users' point of view, which determinates an easier understanding of the reliability by the clients. Also, refers more at the execution than to

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Knowledge Based Organization 2008 International Conference the design, which makes it more dynamic than statical.One advantage is the fact that reliability is being calculate for the both components: hardware and software. We can also calculate the reliability to the entire system.

The software reliability engineering is a part of the software engineering that concentrates on the quality property named reliability. It implies all the steps from the development process in order to identify the demand regarding to the reliability and in order to control if we find them in the final product.

The software reliability management is definite as the software reliability improvement process that accentuate on warning, detecting and elimination of the software errors and on using the metrics in order to maximize the reliability by its project compulsions- resources, the cost and the performances. For reliability maximization we must do:

- we need to prevent errors; - to detect and eliminate errors; - measurements for increasing reliability, for define and for

using specific metrics to sustain first two activities. Reliability is the quality product and quality can be measured.In

order to be effective, the measure must be a part of the management activity. The measures help in order to achieve the fundamental objectives of the management, concerning prevision, progress, and processes improvement.

2. The software reliability concepts If the objective is to calculate global reliability, we try to prevent

and to investigate errors since the first step of software development. The error represent an omission of the programmer wherefrom

results the defection. Errors are classified as: • Impermanent errors - are errors that manifest by a

temporary bad function of a component- directive, module, or program- but not by a permanent defection; most of the errors from the programs system are impermanent;

• Permanent errors - occur at a certain moment and maintains until the damages are repaired.

Because software depreciates in other way than hardware, the

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Knowledge Based Organization 2008 International Conference software reliability stay constant in time if we don’t operate changes in the source code or at the environment conditions level, inclusive at the user behavior. However, if every time when a defection was rectified, and the defect that was the main cause is eliminate, then reliability will increase in ratio with time. This is a usual situation for the probation phase.

The hazard rate of a component is noted with λ(t). Recent researches in reliability domain talk about the risk rate as failure rate r(t) or failure intensity λ(t). The fact that the risk rate of the program z(∆t/ti-1) is equal with the failure intensity at the [ ti-1+∆t) for the reliability increasing models of Poisson type, contributes at this confusion.

To increase software reliability by preventing errors, we must analyze the demands and the probation plans, in order to assure the demands probation. Also, we must pay attention to the software maintenance during the utilization time. This activity implies assistance from the programmer’s side.

The fundamental factors that influence the software reliability are the redundancy, the time, the input space and the operational profile:

Redundancy - is used to build reliable programs system; there are two types: spatial and temporal;

- the special redundancy - use more components than is necessary , to implement a programs system; when redundancy is big, there are detected and tolerated more errors;

- temporal redundancy - consists in the same instructions set, in order to make the same thing in repetitive way; after that the results are compared between them.

Time - from the point of view of the quantitative expression, the reliability is described often with some time intervals. There are different types of the time units:

- calendar time : is useful in order to express reliability congenial with the calendar time, because it offers to the managers and to persons that develop software the chance to see the date when the system attains the objectives of reliability;

- execution time: is used by models to evaluate reliability; the reason consists in the fact that these models are higher than the models that use the calendar time. To be able to express reliability by

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Knowledge Based Organization 2008 International Conference calendar time, the models convert the execution time in calendar time in an afterwards stage.

The models used to calculate the reliability are based on the defects which appears in a chance way. Because a defect appears only during the execution process, is important to use the calendar time in the reliability calculations.

The software reliability as a quality attribute: the measures and the concepts used to study hardware reliability apply fractionally at software, because of the differences that exist between these two components.

The nature and the errors comportment in programs systems – when a defection appears at a component, these stop constrained its execution. Also now an exit message that contains the reason of stop execution is transmited to all the interlinked components.

If the system is fault tolerance, exist the possibility that its execution to continue when the fundamental functions are not affected. In this case, the system must inform the user about the error occurred and about the way the execution spreaded.

Table 1 The errors of the software systems

Appearance conditions In normal conditions/in abnormal conditions

Origin From design, execution, exploitation The possibility to eliminate the defection cause

Eliminable, not eliminable

The possibility to use afterwards Total, partial Mode to eliminate the defections The conversion of the defect

component, the corrective maintenanceFrequency of defection appearance Unique, systematic The intercession complexity in order to eliminate defections

Simple, complex

Consequences Dangerous, major, not dangerous, minor

Mode of fault localization Visible, secretly The defection level dependence Dependent, independent Properties modification Sudden, lent

Is very semnificative an analyse on the comportment of the

hardware defects and of the software errors.

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The software errors depend by the input errors. The fact that the errors occurs at a certain moment,in an unique input sequence elaborated in that moment, confirm their dependence on input dates. Hardware defects depends by time because all devices have a medium endurance, thereupon the defection intensity increases very fast.

Causes of the errors appearance – the cause of the errors that appears in a programs system are the mistakes made in different translations which takes place in its achievement process; the mistakes are human actions, which generate undesirable results presented in every stage from the achievement process, since the define of demands and until the functional probation of the programs system.

3. Determination the software reliability methods In order to determinate the reliability increasing ways is

necessarily to know the factors which influences it, to analyse the errors causes and to evaluate quantitative the reliability. The reliability parameter it’s a measure which expresses quantitative the reliability or one of its properties. Considering the static character of the reliability result that the reliability parameters are static measurements.

The reliability parameters for program systems estimate its properties. This submit:

- to effectuate reliability computation; - to fundament the reliability demands; - to compare reliability for different programs; - to analyse the influence of different factors on the software

systems reliability; - to choose and to fundament the reliability increasing ways.

The preliminate reliability of the systems it determinates in the design stage when it obtains their architecture- components, interfaces and interactions. To estimate the preliminate reliability we apply the analyses techniques of the systems.

4. The software reliability modeling A model is a simple representation of the system or real process

comportment or structure. The goal of the modeling process is to reproduce the fundamental relationships in order to realize their clear

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Knowledge Based Organization 2008 International Conference understanding

A good model presents next properties: • it offers good prediction about the errors future comportment; • it calculates the necessary measures; • is simple; • has a high applicability level; • has as fundaments solid hypothesizes. The software reliability modelling is a functional representation

of the debated system and the better model offers a viable mechanism for reliability estimation.

4.2. Classification of the software reliability models Most of the specialists which designed and realized models had

validate them theories on the base of actuality dates. The studied mentioned previously are not convincings because:

• they are based on a small number of experiments; • the validity of a model and its evaluation criterions are not

defined in an unitary way. These reasons determines an absence of conviction, and this thing

represents an important limitation to the users. Therefore, is necessarily to develop some procedures that admit:

• time between the errors; • the count of the errors; • the solwing of the errors; • inputs on the main domain. In the next pages, are presented the most used models for the

evaluation of the programs systems in accountancy: 4.1.1. Prediction models This models are applied in the first stages of the systems

designing cycle. This models uses collect dates in the development process and product metrics in order to obtain a prelimitate level for the defection density. The representative models are:

- RADC model - the model based on phases.

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4.1.2. Assessment models The estimative models included in the dates domain use the

probation dates for the chosen programs systems according to the probability distributions of the anticipated operational uses. The models included in the time domain use as the fundamental element time, in these variants: the occur time of the errors, the execution time between successive errors, the probation time between successive errors.

The most representative models are: - the logarithmic model Musa- Okumoto - the Littlewood- Verrall model. 4.1.3. Reliability increasing models For this type of models, new versions programs system reliability

is predicted by the previous models. The increasing models realize predictions based on the observed

number of errors during the test, and the parameters are expressed by the maxim likelihood method or the smaller squares method. They product different results for the same input dates.

The models used frequently in estimation of software increasing reliability are:

- the Goel- Okumoto model; - the generalized Goel- Okumoto model; - the model with S profile ; - the Yamada- Ohba-Osaki model; - the lately S model; - the log-logistic model. 5. Summary Models are classified by the method the model is generated. The

first type is the part of the theoretical models that are based on the existence of some relationships between variables. The second type is based on extracting dates and its fundamental is statistic analyse. The third type is a models combination where the intuitive factor is used to determine the models constantly.In practice, is adopted the combined model.

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The metrics models are classified in: process model metrics and product model metrics. The first group improve the software development process and the second group concentrates on measurement of the software products intern attributes and to establish a conexion between them and the extern products quality.

References

[1] P.K. Kapur, R.B. Garg & S. Kumar Contribution to hardware and software reliability, Singapore, World Scientific, 1999;

[2] P.K. Kapur, D.N. Goswani, & A. Gupta, A software reliability growth model with testing effort dependent learning function for distributed systems, International Journal of Reliability, Quality and Software Engineering, 11(4), 2004, 365-378;

[3] M.P. Cristescu, Modele de evaluare a fiabiltăţii sistemelor de programe, Teză de doctorat, A.S.E. Bucureşti, 2002;

[4] D.R. Jeske, X. Zhang, Some successful approaches to software reliability modeling in industry, Journal of Systems and Software, v.74 n.1, p.85-99, January 2005;

[5] A. Gandy, U. Jensen, A non-parametric approach to software reliability: Research Articles, Applied Stochastic Models in Business and Industry, v.20 n.1, p.3-15, January 2004;

[6] C.Y. Huang, S.Y. Kuo, J.H. Lo, M.R. Lyu, Quantitative Software Reliability Modeling from Testing to Operation, Proceedings of the 11th International Symposium on Software Reliability Engineering (ISSRE'00), p.72, October 2000 .

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http://portal.acm.org/citation.cfm?id=1044431&dl=GUIDE&coll=GUIDE&CFID=7525943&CFTOKEN=94393740











SOFTWARE SECURITY FOR ENTERPRISE.SECURITY RISK

Conf. univ. dr. Răduţ Carmen, Lect. univ. drd. Has Aurelian

University “Constantin Brâncoveanu” -Pitesti, Romania, [email protected]

AbstractThe (most) organizations view critical security risks as having the utmost

importance, project managers constantly struggle to apply risk-managementtechniques. The enterprises often believe that an authentication, sessionmanagement, data encryption, or similar product protects their softwarecompletely.

The enterprise software security framework is a way of thinking aboutsoftware security more completely, at the enterprise level, targeting theproblem directly without demands for massive headcount, role changes, orturning an IT shop upside down to prioritize security ahead of supporting abusiness that funds it.

An Enterprise Software Security Framework aligns the necessary people,know-how, technologies, and software development activities, to achieve moresecure software. Every organization possesses strengths and weaknesses, and,most important, faces different risks as a result of using software, TheEnterprise Software Security Framework will differ across organizations.

Keywords: Enterprise Software Security Framework. SecurityRisk

1. The Enterprise Software Security FrameworkThe Enterprise Software Security Framework is a way of thinking

about software security more completely at the enterprise level,targeting the problem directly, without demands for massiveheadcount, role changes, or turning an IT shop upside down toprioritize security ahead of supporting the business that funds it.

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An organization’s the Enterprise Software Security Frameworkshould possess a “who, what, when” structure—that is, the frameworkshould describe: what activities each role is responsible for and atwhat point the activity should be conducted. Building security intoapplications requires the collaboration of a wide variety of disciplines,the framework should include roles beyond the security analysts andapplication development teams. In figure 1 we submit an EnterpriseSoftware Security Framework might list each role’s responsibility.

Figure 1. The Role responsibilities: who

Any organization’s infrastructure group is another’s sharedservices or architecture office, or something else entirely, and that’sokay. Another shrewdness involves reporting relationships— althoughthey’re important, don’t get wound up in them when defining theEnterprise Software Security Framework.

Focus on who needs to do what. In figure 2 we submit a partialenumeration of activities for which a particular role is responsible.The business owner of development might decide to build a handbookto walk developers stepwise through the process of programmingsecurely. The Enterprise Software Security Framework could mandatetraining for developers before they’re unleashed into the developmentorganization.

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Figure 2. The Role activities: what.

In this relative ordering, teams know which activities depend onothers. Providing any more of a detailed “when” diagram we remarkoffensive and overly constraining to each suborganization. Let peopleconduct detailed project planning around these activities themselves.

The philosophy of resisting attack must pervade each and everyEnterprise Software Security Framework activity. Avoid the featuretrap by establishing a goal of improving attack resistance in eachactivity from its inception. Some guides:

construct misuse/abuse cases, model the threats each application faces, assess applications against a threat model, misuse/abuse

cases, train using vulnerability case studies, define standards based on risk, vulnerabilities, avoid relying on security feature checklists, and avoid relying solely on API-guide security standards and

training.The Enterprise Software Security Framework defines an

organization’s approach to software security and describes roles,responsibilities, activities, deliverables, and measurement criteria. Italso includes a communication plan for enterprise- wide roll out.

Enterprise software and data architectures are essential anchors ofthe goal-state an Enterprise Software Security Framework defines.

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Definition of and migration toward a secure enterprise architecture isthus part of the framework competency. An organized collection ofsecurity knowledge is likely to include policy, standards, design andattack patterns, threat models, code samples, and eventually referencearchitecture and secure development framework. The definition oftasks and activities that augment existing development processes helpdevelopers build security into any custom software developmentprocess, as well as in-place outsource assurance and commercial off-the-shelf validation processes.

A secure development process is an iterative developmentmethodology whose constituents bear some resemblance to activitiesand artefacts found in Rational Unified Process. The phases for thesecure development process are:

Analysis phase – this phase is geared towards problem definition,requirements gathering and analysis

Design phase – this phase is consists of iterating through design,proof of concept work, and refining requirements

Development phase – this phase is characterized by programmingand unit testing code

Deployment phase – the deployment phases promotes the codeinto production operation

These phases are iterative in nature as opposed to a waterfallapproach. Analysis does precede other phases, but analysis artefactsand activities will be revisited throughout the development life cycle,i.e. after design prototyping. Design phase activities and artefacts arelikewise updated and refined throughout the development process, inconjunction with the development phase. In this case the focus will beon securing the building phases so that the application is in a moredefensible position when it is promoted to the operational status.

2. The security attributesTo determine the target system’s security attributes, the

assessment team must analyze the critical information stored,processed, and transmitted in and by the system. This informationshould be a reflection of the system’s security requirements. Thesecurity attributes include confidentiality, integrity, and availability.

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Only authorized people can access the data, but authorized people caninclude a wide range of roles such as person, insurers, billing staff .These descriptions of security attributes aren’t sufficient withoutclarifying how authorized individuals will be identified andauthenticated, how authorization and person information will beshared across the target system’s components, and how authorizationand data will be handled in each component. Gaps and discrepanciescan become potential vulnerabilities.

In identifying threats, the assessment team must consider who orwhat could compromise a target system’s components such that thesystem’s security attributes would be jeopardized. Although this mightappear similar to a general operational threat analysis, identification inthis step should focus on ways in which the target operational system,information assets, and components within it differ from what alreadyexists in the current operational environment.

However, if the system’s information assets differ greatly fromthose the operational environment currently protects, existing practicesmight be insufficient; this gap must be identified as a threat. If thetarget system requires wireless external access that differs from theexisting operational system, for example, then current operationalsecurity practices might not be sufficient and the system could bevulnerable to threats.

The assessment team must consider the critical interfacerelationships the target system has, the information that’s beingshared, and the ways it’s protected in transit, as well as the establishedtrust relations between systems, processes, and components and theways in which trust is communicated. Another area of potential threatis the implementation process.

Identifying security risks means considering each threat’spotential impact on the organization. This impact can be magnified ifthe new system’s operation becomes unstable. Impacts can include:

inability of the system to complete business functions; revenue loss; increased operational costs due to overtime payments or

other additional expenses; reputation damage;

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fines and penalties; and safety and health problems for system

An assessment team can evaluate the likelihood of external threatsif it knows the target organization’s technology infrastructure historieswith cyberthreats, similar organizations’ histories with cyberthreats, orsimilar systems’ histories with cyberthreats. Histories should includeinformation about how often such attacks have occurred in the past aswell as the severity of the resulting impacts on the organizations. Inmany organizations, operational support people collect thisinformation but most haven’t thought about making it available tosystem developers.

The execution of security touch point activities providesassurance—conducting a software architectural risk assessment, forexample, validates that security requirements were translated intoaspects of the software’s design and that the design resists attack..

3. ConclusionsGovernance should be applied to the roll out and maturation of an

organization’s Enterprise Software Security Framework. Theframework’s owners can measure project coverage and depth ofassurance activities, reported risks, and the progress of softwaresecurity knowledge and skill creation, among other things. Eachcompetency depends somewhat on the others, and growing eacheffectively demands thoughtful collaboration. Instead, good theEnterprise Software Security Framework leverage key initial successesin support of iterative adoption and eventual maturation: patience,customers.

Patience - It will take at least three to five years to create aworking, evolving software security machine. Initial organization-wide successes can be shown within a year. Use that time to obtainmore buy-in and a bigger budget, and target getting each pursuit intothe toddler stage within the three-year timeframe.

Customers - The customers are the software groups that supportthe organization’s lines of business. Each milestone in the roadmapshould represent a value provided to the development organization,not another hurdle.

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References[1] C. Alberts and A. Dorofee, Managing Information Security Risks: The

OCTAVE Approach, Addison-Wesley, 2003.[2] C. Alberts, A. Dorofee, and C. Woody, “Considering Operational Security

Risks during Systems Development” Software Engineering Process GroupConf. (SEPG2004), 2004; www.cert.org/archive/pdf/alberts-2.pdf/.

[3] C. Alberts, A. Dorofee, and C. Woody, “OCTAVE Overview: OperationallyCritical Threat, Asset, and Vulnerability Evaluation” white paper, CarnegieMellon Univ./Software Eng. Inst., 2003; www.cert.org/octave/pubs.html.

[4] P. Clements, R. Kazman, and M. Klein, Evaluating Software Architectures:Methods and Case Studies, Addison- Wesley, 2002.

[5] N. Mead, D. Firesmith, and C. Woody, “Eliciting and Analyzing QualityRequirements: A Feasibility Study” tech. report, CMU/SEI-2004-TR-018,Carnegie Mellon Univ./Software Eng. Inst., pp. 21-32, 2004;www.sei.cmu.edu/pub/documents/04.reports/pdf/04tr018.pdf.

[6] C. Woody, Eliciting and Analyzing Quality Requirements: ManagementInfluences on Software Quality Requirements, tech. note CMU/SEI-2005-TN-010, Carnegie Mellon/ Software Eng. Inst.,2005;www.sei.cmu.edu/publications/documents/05.reports/05tn010.html/.

[7] J. Allen, “Informational Security as an Institutional Priority” 2005;www.cert.org/archive/pdf/info-sec-ip.pdf/.

[8] C. Alberts, A. Dorofee, and J. Allen, OCTAVE Catalog of Practices, Version2.0, tech. report CMU/SEI-2001-TR- 020, Carnegie Mellon Univ., 2001;www.cert.org/archive/pdf/01tr020.pdf/.

[9] C. Woody and J. Minter, “Embedding Security into a Software DevelopmentMethodology” ID: SPC0562, Abstract and Presentation for the SecurityProfessionals Conf., Educause Resource Center, 2005;www.educause.edu/LibraryDetailPage/666?ID=SPC0562/.

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A GUIDE ON AN IT SUPPORT FOR HISTORICAL DOCUMENTS COLLECTION IN A KNOWLEDGE

BASED ORGANIZATION

Dr.Cyb.ec.math. Florescu Gabriela, Eng. Florescu Valentin

National Institute for Research and Development in Informatics, Bucharest, Romania, e-mail: [email protected], [email protected]

Abstract The paper aims at explaining a good practice in knowledge on digital

resources management for knowledge based organization owning valuable historical document collections. Some general considerations of the applicative context, considerations followed by a guide for deploying an IT support method for carrying out valuable collections and further concluded with a synthetically presentation of an IT tool for digital content management, are the main contributions of our paper.

Keywords: KBO, digital documents collection, guide, IT tools

1. Introduction As a general overview, the digital content made available by e-

libraries is not a new approach but new is our attempt to offer a solution for MM documents owner to be able to arrange and to valorise better their great collections for informational and research purposes within a knowledge based organization. We are interested on how to access these treasures or how to share them till a national initiative level on MM documents will be available.

Thousands of valuable MM documents could be prepared to be integrated according the laws and rules. The start consists in several “Standardized Digital Resources” populated with digital documents organized in a standardized framework.

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2. IT support for Historical Documents Collection In a knowledge based organisation it is supposed to have a special

structure and a special access to main collection of information of a given interest for the organization. Among this important information we consider the historical documents collections gathering old texts, diplomas, manuscripts, old maps, pictures. In order to have an easy access to this historical documents collection we propose a guide for an IT application for documents preservation and consultation within digital collection in a knowledge based organisation. That means that several steps in approaching the entire process from old documents discovery to their direct digital access as multimedia (MM) documents have to be fulfilled. All proposed steps are as follow and they are partially inspired by the technical guide for digital content creation programmes published by the MINERVA project [10]:

Application Planning Application Definition and Attributes Application Life Cycle Application Planning Formal Methods of Project Planning and Software Tools Staff Training and Development Disaster Planning 2. Preparation for Digitisation Background Hardware Software Environment 3. Digitisation Selection of Materials for Digitisation Appropriate Movement & Manipulation of Original Material The Digitization Process 4. Storage and Management of the Digital Master Material File Formats Text Capture and Storage Still Image Capture and Storage Video Capture and Storage Audio Capture and Storage Multimedia, GIS, 3D

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Media Choices Preservation Strategies 5. Metadata Creation/Capture The Scope of the Metadata Appropriate Standards Descriptive Metadata Administrative Metadata Preservation Metadata Structural Metadata Collection-Level Description Terminology Standards Web Ontology 6. Publication Processing for delivery Delivery of Text Delivery of Still Images Delivery of Video Delivery of Audio Identification 3D and Virtual Reality Issues Geographic Information Systems Web Sites Accessibility Security Authenticity User Authentication 7. Use of Resources Metadata Harvesting Distributed Searching Syndication / Alerting Web Services 8. Reuse and Re-purposing Learning Resource Creation Reuse by Third Party Services 9. Intellectual Property Rights and Copyright Identifying, Recording and Managing Intellectual Property Rights Safeguarding Intellectual Property Rights

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Creative Commons E-Commerce Watermarking and Fingerprinting These guidelines allow the documents owner within a KBO to

plan his application based on an information infrastructure that is not influenced by content changes. Based on this guide we deployed a research and developed an IT instrument for Romanian collection of valuable multimedia/digital documents ROCOLDO.

3. Experiment 3.1 General specification The ROCOLDO (ROmanian COLlection of valuable

DOcuments) approach, made of our proposed general IT tool and accordingly the general IT service, is presented by mentioning some of the main functionalities when it is deployed, used and further tested with an excerpt of documents from ICI historical multimedia (MM) document collection.

The ROCOLDO experimental system for digital content creation and distribution of MM documents is made of two modules:

- Digital content creation module, - Digital content distribution module. The ROCOLDO’s two generic target users of this system are: -The MM documents owner - the digital content providers

interested in preserving and disseminating their existing documents accompanied or not by explicative text information.

-The MM documents consultant - The interested public in documenting and researching in the field of the organisation.

Structurally, the experimental ROCOLDO system is made of three components: Documents data base, Owner interface, Consultant interface.

3.2. Working technologies and data base The main technologies proposed to be used by the system

developer are: HTML 4.1, JavaScript 5.0, ASP 3.0, ADO (ActiviX Data Object) 2.5, AJAX.

The ROCOLDO‘s IT tool is based on a Data Base server type, MySQL 5.0, ODBC 3.5 with interface developed in ScriptWeb ASP.

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Knowledge Based Organization 2008 International Conference The text information is made available in a free style. The MM document owner introduces as much as possible text information expressing better the content of the collection globally as well as for each page, in Romanian and in a foreign language. The MM documents are made of all pages of the MM documents for a topic in a standard JPEG format and with a given resolution.

3.3. Interfaces and digital content protection The system has one interface for digital content owner or

provider and one interface for the digital content consultant. Both interfaces are secure at external intrusion at copy attempts.

The ROCOLDO system interface protects automatically the text and the image by including special security elements. The interface is made in such a way that the following options are blocked: Copy, View Source, PrintScrn key, Shortcuts for the above options, Right hand side button of the mouse.

4. Results and discussion 4.1. Aspects for the digital content provider The ROCOLDO implemented system is experimented with a web

interface for the digital content owner. The content provider from his console can feed the Data Base

from distance. By means of the SQL language it is possible to access each page of each set of records attached to a MM documents.

The content provider has the following user’s rights: - To access the Data Base by personal password established by

the server Administrator. This password could be later modified, - To feed the Data Base and to erase records, - To modify records and to establish the sequence of pages for

digital content visualization. In ROCOLDO, after the password input, verified by the server,

the access right is received by the digital content provider or digital document owner and consequently, a web page is generated by the server. In this page, the text field and image field for a record are user-friendly displayed. The image field is a rectangle 200x200pixels under which there is a browse button. The content provider will select this button and will choose from his computer the jpg file for the

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Knowledge Based Organization 2008 International Conference record by means of an “open” type window. The images could be of any dimension with the standard resolution 72ppi, and the size 100kb for a minimal loss of graphical information. After the file selection, this image will appear minimized in the rectangle.

The text field will be a “text area” type which will allow the text with diacritics. Under this input there is also a search button. By means of this button the window 300x300pixels appears with two headings: Font selection, type and size and Selection of colour for the font from the 16 basic colours. There is also a button for saving the record on the server and one button to close the ROCOLDO work session.

4.2. Aspects for the digital content consultant The digital content consultant, after choosing of a digital

document for studying it, he has the possibility to browse each MM document as well as to zoom in or zoom out for studying details. The document image is increased three times against the original dimension. Page browsing is possible in both directions - descending or ascending. The consultant will be able also to search Data Base for texts and images by using selected keywords.

The digital content consultant by means of the home page will have a tree menu including the entire structure of information of Data Base organised by the following fields: author, year and MM document type, geographic coordinates. The tree menu on each page contains the access to consult: Document type, Place, Time interval of original elaboration, Authors, Document editors.

The digital content consultant, based on this menu, accesses the zone of interest by browsing. Each document is characterized by

- Place for direct consultation, - Place of acquiring the MM document, - Original or copy availability in either digital or material format

considering the intellectual property right. Considering the facilities developed by this experimental system

it is obvious that the IT tool is a support of an IT service in MM heritage preservation – unique MM documents - either an individual or an institution would like to make accessible and available.

The ROCOLDO system could be improved and extended with

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Knowledge Based Organization 2008 International Conference more facilities but in our opinion it is more convenient to have a simple system easy and directly accessible and usable by research or interested stakeholders and a system with no sophisticated development, much depending on the technology infrastructures. The evolution of ITC technology would little affect a simple system as that ROCOLDO proposed by us as our system contains low dependable elements of the rapid transformation of ITC.

5. Conclusion Knowledge society is first of all a society of long life learning

and education. In this context, scientifically, as a research projects result, ROCOLDO, contributes to the development of research in the field of personalised digital archives of MM documents considering the official standards for MM information.

Information gathered from MM documents is a precious testimony of the Romanian culture but it is threaten to disappear if no ITC tools or ITC services for public consultation are made available for all MM documents’ owners.

The proposed ITC tool, ROCOLDO, is a simple and an accessible way by which, individuals, researchers, could better preserve, filter, distribute or share their precious MM documents heritage within an organization. The general system proposed by this paper is the solution of a new approach concluded in a tool which is experimented and under tests on a part of ICI MM documents collection.

6. Summary This work has presented some contextual aspects of KBO and

some feature of the management of valuable collection of documents in an organization. A guide on how to develop a computer based application for a safe digital content management has been also presented. In the last part of the work it was presented an IT tool for digital collection developed considering the above guide.

Acknowledgements This work is supported by the Romanian Ministry of Education

and Research, under the Contract no. 19/2006 “System for interactive

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Knowledge Based Organization 2008 International Conference digital content provision and dissemination for historical documents”, Grant PN 06190303/2007-2008.

References

[1] Beagries, N., National Digital Preservation Initiatives (2003) http://www.clir.org/pubs/reports/pub116/contents.html.

[2] CIDOC - Conceptual Reference Model; http://cidoc.ics.forth.gr/index.html. [3] CIMEC - Romanian Old Books Catalogue http://www.cimec.ro/Carte/

cartev/default.htm [4] Eycken, L. Van DeKnuydt, B.and Gooll L. Van, A Common Infrastructure

for Cultural Heritage Applications, EPOCH Conference on Open Digital Cultural Heritage Systems (2008)

[5] Arnold, D. Niccolucci, F., Pletinck, D. Van Gool, L. (Editors) European Network of Excellence in Open Cultural Heritage, http://epoch-net.org

[6] OBLC - Online British Library Collection, http://www.bl.uk/collections/ manuscripts.htm

[7] RALMC - Romanian Academy Library, Manuscripts collection, http://www.biblacad.ro/www_rom/manuscrise.html (accessed 15 July 2008)

[8] RALC - Romanian Academy Library Collection. http://www.biblacad.ro/ www_rom/docist.html

[9] Europe’s digital library, museum and archive http://www.europeana.eu/ index.php

[10] Minerva Technical Guidelines for Digital Cultural Content Creation Programmes, UKOLN, University of Bath, version 1.2, 2008, pp48

[11] CASPAR Report on Framework Architecture, 2008, pp40 [12] Guidelines for the preservation of digital heritage, National Library of

Australia, 2003, pp170 [13] CASPAR –Cultural, Artistic, Scientific knowledge for Preservation, Access

and Retrieval http://www.casparpreserves.eu/ [14] MINERVA Ministerial Network for Valorization Activities in digitization

http://www.minervaeurope.org/ [15] EPOCH European Network of excellence in Open Culture Heritage

http://www.epoch-net.org/index.php

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http://www.cimec.ro/

http://www.bl.uk/collections/

http://www.biblacad.ro/ www_rom/

http://www.biblacad.ro/ www_rom/

http://www.europeana.eu/


E-LEARNING A NEW METHOD FOR ENVIRONMENTS OF 21ST CENTURY

Lecturer PhD Eng. Cornelia Victoria ANGHEL

EFTIMIE MURGU University of Reşiţa, Romania, [email protected]

Abstract The article presents some aspects about the new e-Learning method for

study. Education and researches in different domains using modern technologies for learning within computer aided instruction in knowledge based society.

We can consider that e-Learning represents an opportunity for those who want to be continually trained.

Keywords: e-Learning, knowledge, organization, computer

1. Introduction The evolution of technology, information, the development of the

communication system induces new approaches and new learning techniques. The technologies of information and communication (TIC) constitute not only a media device but also a path to all the resources of the world.

TICs contain three technologies: informatics, telecommunication and audio-visual materialized in the computer connected to the Internet. This new communication method, through its quantity and quality of available information, influences the educational activity.

E-learning is different from other methods of training. There are particularities, advantages and limits of this training method. Terms of distance training, on-line training, e-learning, tele-education have an apparently similar significance and represent specific aspects of the new educational technology.

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The term of e-learning represents the interaction between the educational process and the Information Communications Technology.

E-learning can be defined as a learning process based on multimedia resources and which allows one or more persons to get training starting from its own computer. The multimedia support system can combine a text, a plane or spatial graphic, a sound an image, animation and even video resources.

These support systems revolutionize the pedagogical approach

and the methods through the educational product. 2. Advantages and disadvantages of distance learning Training is “open” to any person, regardless of age, training,

socio-professional category, etc. The access to information and its manipulation is performed

without any restrictions imposed by the distance. It favors the creativity and the discovery of new interpretations,

nuances and entities. It allows the access to new competences required by modern life.

Anyone can get familiar to the new technologies: computer, multimedia systems, Internet.

It facilitates the local training, without departures; thus the person applying for this kind of education gains time, financial economy and optimal training conditions (for example at home). This represents great advantages for handicapped persons.

A trainer can address to a large number of students, ensuring an individualized relation with each of them.

It allows a sensitive reduction of costs compared to training that requires the presence of the student.

- transport and accommodation expenses are suppressed - the individual learning time is reduced by directing the study

towards the aspects which must be explored - the trainer has now the role of guidance, of giving assistance at

the learning programme. The persons implied in the study benefit of the knowledge and the

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experience of the internationally recognised trainers, whom they cannot meet directly.

It ensures the anatomy of training: the trainee chooses the conditions of time and space.

It allows the choice of subjects, the planning of courses in concordance with the actual training level, ensuring a better assimilation of knowledge and a proper evolution of the student’s capacity.

It is based on interactive multimedia solutions that require the student’s attention; it stimulates his capacity of understanding and interpreting. The simulations, the self-evaluating tests (soft products associated to the knowledge display), the exchange of messages place the person in the center of his training, and they constantly keep him active. The efficiency of training depends on his will to assimilate.

It supports the feeling of freedom and self trust, through the lack of intimidation and embarrassment condition towards the colleagues and the teacher.

The interesting information from the Internet can represent news in the field and can be accessed everywhere in the world.

However, this does not constitute a miraculous solution. It can be used on short term even if the solution is pedagogically qualitative.

Disadvantages: 1. It prevents/restraints the student’s socialising, its integration in

a group, its adaptation to real life, the creation of inter-human, affective relations.

2. The technical problems afferent to the functioning of the training systems (perturbation of the communication network, the breakdown of the computing equipments, soft piracy or document viruses)

Particularities of E-learning E-learning contains different development modalities and

technologies (correspondence/publishing, audio, video, computer) of training, which supposes the physical distance of the educational

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actors (teacher-student) who feel this distance and try to replace it through different strategies of encouraging the interaction between teacher-student, student, student, student-study content, and which leads to a much more personalised relation than in the traditional education (face to face), through the exchange of study messages and documents or answers to the required tasks.

The defining elements of e-learning could be: The separation between the trainer and the trainee during most of the training period The use of mass-media (for educational purposes) in order to relate the student with the teacher and as support to transmit the course content. The insurance of communication between the teacher/tutor or the education agent and the ones who learns.

3. Factors implied in the distance training a) Human resources:

- the students (with their motivation, skills and competences); - the faculty (the trainer who must develop an understanding of the students’ characteristics and needs, must adapt his teaching method, must be aware of technology, must facilitate learning and also be an information provider); - the technical personnel acting like a bridge between the teacher and the student, understanding each category, installing programmes, collecting evaluations, tests ; - the auxiliary personnel registering the students, multiplying and distributing the material, ordering the manuals, making level-development reports, organising technical resources, ; - administrators b) Technological support: the technologies selected according to a convenient balance between needs and costs c) The Programme management answering to the needs of the students and ensuring the necessary resources, the adequate equipment and the assistance services for the students d) Managerial services dealing with the integration of distance education in the curriculum (analytical programmes), the

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faculty development, ensuring the conditions for solving the tasks given by the trainer, the creation of new facilities and the improvement of the quality of the educational act. 4. Studies and Results

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Thus Computer Base Learning appears in America in the

years 1970-1980 and uses the educational software memorised on CD or hard-disk.

The Web Based Learning means training through web courses. The soft is dedicated to training on a web address. In this context there are electronic manuals, links towards other educational resources.

Web Based Teaching represents teaching on the Internet and is constituted from a list of emails and discussion forums. 5. Conclusions E-learning, founded as a consequence of the development of information and communication technology, is another opportunity offered to those who want to be trained.

It does not exclude the classic education, where real objects are used as a source of information, but attaches virtual resources (documents in electronic format on the internet and other information supports used on the PC).

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In this stage, using the TICs, the teacher is not the most important piece of knowledge; information can be found on the internet as well, independent from the teacher, thus he becomes the third actor in the learning process (actors: teachers, students/students/, knowledge/science). At the moment, the contribution of the teacher is strictly methodological, he must guide, and he must know how to ask the designer of the educational soft to adapt to new.

References

[1] Carmen Holotescu, Ghid de eLearning, Ed. Timsoft, Timişoara, 2004. [2] Jalobeanu M., WWW în învăţământ. Instruirea prin Internet, Ed. Casa

Corpului Didactic, Cluj, 2001. [3] Mihaela Brut, Instrumente pentru e-learning. Ghidul informatic al

profesorului modern, Ed. POLIROM, Bucuresti, 2007.

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EXAMPLES OF INTERDISCIPLINARY CONNECTIONS WITH THE USE OF COMPUTER

ASSISTED GRAPHICS APPLICABLE TO THE SPECIALTY OF MILITARY TECHNIQUE

Asst.Eng. Horia Tarziu, PhD, Anamaria Comes

The Air Force Academy „Henri Coanda”, Brasov, Romania, [email protected],

The Main Foreign Language Learning Center in Brasov,

Abstract The opportunities provided by the software packs specialized in graphic

modeling can be successfully used also in the military technique-related theoretical education, thus turning into a captivating and user-friendly tool for the students. Due to their capability of providing complex and evocative visual models, and in combination with imagination and interest, these graphic modeling software packs can significantly contribute to a better understanding of the theoretical issues specific to the study of the specialty disciplines. This article brings forward a model that pleads in favor of this method of approaching the theoretical issues, by means of computer-assisted graphics: the graphic modeling of the kinematic schemes of the landing gear, techniques for animated representation, solid modeling, etc.

Keywords: Solid Edge, AutoLISP, modelare, Macromedia Flash

1. Introduction The graphical methods of determining the kinematic sizes of the

elements of the mechanisms with articulated bars represent one category of such computer assisted –based didactic applications. With the advent of the graphics software packs – characterized by the

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Knowledge Based Organization 2008 International Conference capability to associate to any point on the screen its corresponding coordinates - the graphical methods can be re-evaluated with a double didactical advantage: the better understanding of the studied phenomenon, as well as the acquiring of the necessary skills to create applications by means of basic programming. Software packs are inexpensive: they can be educational versions at a lower price or simply open source versions of the AutoCAD, Solid Edge or any other relevant programs.

2. Geometric modeling of a landing gear mechanism The landing gear mechanisms that are studied as part of the

specialty discipline are built in a large variety of types, motions, kinematic couples, etc. that will not be covered in the present article. We will only refer to their way of representation, and the analysis and animation of the representation.

Figure 1: Kinematic scheme of the landing gear mechanism Figure 1 illustrates an example specific to the aviation technique,

i.e. a mechanism with elements in plane - parallel motion (the scheme of the mechanism used to activate a landing gear. As we can see, according to the Grubler - Cebîşev relation).

M = 3n -2C5 – C4 (1.1)

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Knowledge Based Organization 2008 International Conference the mechanism functions based on the desmodromic principle, its mobility being given by the relation:

M = 3x4 – 2x5 -1 = 1. (1.2) The leading element 1 sets in motion the bar of the landing gear

2, the motion being controlled through the rod systems 3 and 4. Figure 1 represents two positions of the mechanism’s elements.

2.1. Animated representation techniques One way to create the animated representation of the

mechanism’s functioning is to obtain individually one position at a time by choosing a motion parameter, for example the distance of the hydraulic cylinder piston of the leading element, followed by the introduction of the successive positions in a suitable graphic environment, such as Macromedia Flash. In order to correctly obtain the successive positions (and to accurately keep the distances and angles), the AutoLISP application was built, here called “aatren” and presented bellow.

(DEFUN C:aatren ( ) (SETQ d (GETREAL "Valoarea cursei d:") o1 (list 300 500) o2 (list 1000 500) o3 (list 1000 250) r 200 r1 300 r2 300 d1 (distance o1 o2) a (/ (- (+ (expt d1 2) (expt d 2)) (expt r 2)) (* 2 d1 d )) b (sqrt (- 1 (expt a 2))) c (/ b a) u (atan c) p1 (polar o2 (+ pi u) d) u1 (angle o1 p1) p2 (polar o1 u1 400) p3 (polar o1 u1 600) p4 (polar p1 u 1000) c1 (polar p4 (+ (*(/ pi 180) 30) u) 40);pistonulc1c2c3c4 c2 (polar p4 (+ (*(/ pi 180) 150) u) 40) c3 (polar p4 (+ (*(/ pi 180) 210) u) 40) c4 (polar p4 (+ (*(/ pi 180) 330) u) 40)

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i1 (polar o2 (+ (/ pi 2) u) 40);cilindruli1i2i3i4 i2 (polar o2 (- u (/ pi 2)) 40) i3 (polar i1 u 500) i4 (polar i2 u 500) d11 (distance p2 o3) a11 (/ (- (+ (expt d11 2) (expt r2 2)) (expt r1 2)) (* 2 d11 r2 ));elem3si4 b11 (sqrt (- 1 (expt a11 2))) c11 (/ b11 a11) u11 (atan c11) u12 (angle p2 o3) u13 (+ u11 u12) p11 (polar o3 (+ pi u13) r2) ) (Command "Point" p1) (Command "Point" o1) (Command "Point" o2) (Command "Point" o3) (Command "Point" p2) (Command "Point" p3) (Command "Point" p4) (Command "Point" p11) (Command "circle" p3 40) (Command "pline" o1 p3 "c") (Command "pline" p1 p4 "c") (Command "pline" p11 p2 "c") (Command "pline" p11 o3 "c") (Command "pline" c1 c2 c3 c4 "c") (Command "pline" i1 i2 "c") (Command "pline" i1 i3 "c") (Command "pline" i2 i4 "c") (Command "pline" i3 i4 "c") )

In this example, for the constructive elements of the kinematic chain, the following values were selected: a 200-unit ray r (from O1 to the first articulation of the chain), the rays r1 and r2 of the rod systems each of 300 units, a 1000-unit long hydraulic engine piston’s rod (p4 (polar p1 u 1000)), and a 600-unit distance from O1 to the second articulation (p3 (polar o1 u1 600)). All these can be easily modified, depending on a particular situation.

The value of the piston’s movement is repeatedly requested by the application, by means of the function:

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(SETQ d (GETREAL "The value of the distance d:") which displays on the dialogue bar of the AutoCAD the question

“The value of the distance d" and which will be introduced by using the keyboard.

Figure 2: The succession of the mechanism elements’ positions, with a 10-unit distance of the piston’s movement, from d = 500 to d = 550, as obtained with

the use of the “aatren” application Figure 2 illustrates the image of the succession of the elements’

positions, for a 10-unit distance of the advance of the piston rod. This application is used to obtain an animated representation of the functioning process, for example with the use of the Macromedia Flash software (the successive export of the key frame models). But it can also be used as a starting point for the kinematic study of this mechanism, as shown in the beginning of this article in relation to the rod - crank mechanism.

In other words, the whole construction process of the speeds’ and accelerations’ planes can be automated, for each introduction of the value of the piston’s distance the program generating the instantaneous values of the lead element’s speeds and accelerations.

It is well-known that one of the principles of the graphical animation that has remained unchanged since the advent of the cinema, refers to the fact that a supplementary coordinate - the time - is attached to the coordinates of the plane’s characteristic points (geometric).

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The programming environments specialized in 2D animation don’t always come with the appropriate tools for a precise geometric modeling of the angles and distances that describe a geometric model. Therefore, in order to obtain an accurate animation, it is necessary to combine them with another specialized and interactive program, such as AutoCAD, that offers such capabilities.

The positions in figure 2 can all be obtained simultaneously, by introducing an iterative sequence in the application, or successively, one by one, in the same way as in the above presented application, whose rays’ and distances between articulations’ values are pre-defined and only require the introduction of the values of the lead element’s distance by means of keyboard.

In conclusion, this type of approach can be applied to the practical or laboratory classes for the kinematic study of the mechanisms with elements in plane-parallel movement in order to: identify the instantaneous values of the instantaneous distances, speeds and accelerations; build their corresponding diagrams and obtain the animated representations of the functioning process of the respective mechanisms.

References

[1] Tarziu Horia, Examples of Using the CAD concept and CAE concept in the Study of Basic Technical Subjects, Review of the Air Force Academy Henri Coanda Brasov, no. 2/2007, ISSN 1842-9238.

[2] Manolea Dan, Programarea în AutoLISP sub AutoCAD, Ed. Albastră 1996, Cluj-Napoca..

[3] Autodesk, Inc. Fundamentals of AutoLISP, 1994. [4] Târziu Horia, Medode grafice cu mijloace CAD, Buletinul Ştiinţific al

Sesiunii Naţionale de Comunicări Ştiinţifice al Academiei “H. Coandă”, Braşov, mai 2007.

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TIME & ATTENDANCE SYSTEM WITH RFID CARDS CONTAINING USER’S FINGERPRINT TEMPLATES

Eng. Nicolae Paraschiv*, PhD, 1st S.R. Eng. Toader Melinte**, Stud. Emil Pricop***

*Petroleum-Gas University of Ploieşti, România, n @upg-ploieşti.roparaschiv ,

** S.C. SEEKTRON S.R.L., Ploieşti, România, [email protected] *** S.C. SEEKTRON S.R.L. Ploieşti, România, [email protected]

Abstract The management of the employees’ time is a very important task in every

company. In this paper we will present a time & attendance system based on RFID cards and biometric identification of persons, especially fingerprint analysis. The fingerprint template is stored on a RFID card together with permitted operation codes, identifiers for zones where the access is granted, the expiration date of the card and other information. We will describe how the RFID card and a fingerprint reader could be integrated and how the data is stored in the card’s memory. The proposed solution has some innovative characteristics: improved security – the system is based on fingerprint analysis, an unlimited number of users - the user data is stored on RFID card, real-time statistics accessible over the Internet – the devices could be connected to a network or Internet and the statistics could be viewed as any Web page. The system described in this paper is implemented at a company in Ploiesti and has proved good performance.

Keywords: RFID card, biometrics, identification, time & attendance, security

1. Introduction The management of the employees’ time is very important in the

actual business environment. It is very important to know how much

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Knowledge Based Organization 2008 International Conference time every person spends in the company, what hour he entered or left the building. There have been designed many systems to accomplish this task, saving time resources and money. Many of them use a personal identification number or a card for user identification. We consider that it is very important to identify quickly and exactly each user, that is the reason why in this paper we describe the characteristics of a time & attendance system based on fingerprint analysis. We propose to use a new concept: the biometric RFID card. That card has 1 KB memory that can store up to 3 fingerprint templates and additional user data such as: authorized operation codes, authorized zones codes, personal information, etc.

2. A general algorithm for generating fingerprint templates Biometrics represents automated methods for person

identification based on a physiological or behavioral characteristic. Among the features measured are: facial features, fingerprints, iris and retina features, hand veins, hand geometry, handwritten signature, keystroke dynamics and voiceprint.

Fingerprints are represented by the pattern of ridges and furrows on the surface of a fingertip. The fingerprints are unique and the patterns remain unchanged throughout life. Fingerprints are so distinct that even the ones of identical twins are different. The prints of each finger of the same person are also different.

Generally speaking a fingerprint analysis algorithm has the following steps:

- loading the fingerprint image for an sensor or from a file; - enhancing the quality of the image by modifying the contrast

and some filtering; - image binarization; - final image processing and selection of characteristic points; - generation of fingerprint template. Each step of this algorithm contains complex math problems. The

execution of this algorithm needs a large number arithmetic and logic operations, so it can be done in a minimum time, frequently less than 1 second, only using specialized and powerful processors. This paper is focused in the operations with the fingerprint template that is generated by any equipments using an algorithm similar to the one

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Knowledge Based Organization 2008 International Conference described below. For that reason we will do only some considerations regarding the fingerprint template seen as a data file.

The images have 8 bit grayscale color depth, so there is needed the binarization operation, that has the role to convert the image from 8 bpp (grayscale) to 1 bpp (black/white). The simplest binarization algorithm is to choose a threshold value and classify all pixels with values above this threshold as white and all other pixels as black. In many situations, finding one threshold compatible to the entire image is very difficult or even impossible. For that reason is used adaptive image binarization, when an optimal threshold is chosen for each image area. This process is very important in fingerprint analysis because it differentiate between ridges and furrows.

Final image processing has the role to filter the noises and to reveal the ridges and the furrows. The false distinct points are eliminated in this point. The algorithms used to detect the false distinct points are described in literature, well-known being [3], [4] and do not make the subject of our paper. Selection of characteristic points could be done using many distinct algorithms. These algorithms are described very well in specialty books and scientific papers [1, 3, 5].

The last step of the algorithm is generation of fingerprint template. The template’s size depends on the number of distinct points that have been selected and memorized and is between 100 and 480 bytes. For the time & attendance system described in this paper we used a simple algorithm that implements the steps described before. The size of generated template is 256 bytes, containing a sufficient quantity of information for usage in access control systems and operator identification tasks.

3. RFID biometric card memory structure The fingerprint template calculated using the algorithm described

before will be stored in the memory of an RFID card. RFID stands for Radio Frequency Identification and is the ultimate tracking technology for goods, animals or any object that could be marked using an active or passive radio transponder called RFID tag. The tag has two sections: one for radio communication and a memory used for storing data and custom fields. There are mainly two categories of

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Knowledge Based Organization 2008 International Conference RFID tags: active and passive. The active tags are writeable and readable and have an internal power source (a battery), so the lifetime of an active tag is limited. The passive tags obtain the energy from the magnetic field of the reader. These types of tags are smaller, cheaper and could be used an unlimited time. The functionality of RFID passive tags is very simple: when a tag is in the nearby of a reader, it detects the radio signals generated by the reader and starts to transmit the data stored in the memory. The radio signal generated by the reader offers the power needed to function and the synchronization data for communication between the two entities [2].

In the time & attendance system described herein we used passive tags working on 13.56 MHz (High Frequency), having the reading distance between 1 and 3 meters. The tag has a write-once read-many memory of about 1 KB, which could be programmed only when the card is issued to the user and could be read by any compatible reader.

The system is based on the fingerprint analysis and template storage in the memory of the RFID card in an encrypted form. When a person wants to enter or left the building he must place the RFID card in the nearby of the reader, which is mounted in the nearby of the access ways, then the system reads the data on the card and asks the user to put the finger on the fingerprint sensor. The fingerprint reader scan the finger of the user and then a template is created in real time. After that the generated template is compared with the one stored in the card’s memory. If the templates match and the comparison score is better than a threshold value, then the person is identified, he has access granted and a new event record is added to an event log in the device access controller memory. The user is identified in no more than 5 seconds.

The RFID card could store not only the fingerprint templates, but other information such as zone codes where the user has access, the expiration date of the card, personal user data, permitted or restricted operation codes. Using the model proposed in this paper for the RFID card could be established a unique, efficient and easy to manage system for access control, time & attendance, privilege management and operation tracking in any company.

The standard memory of a RFID card is composed by 128 blocks of 8 octets each, totalizing 1 KB of storage space. Each byte is

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Knowledge Based Organization 2008 International Conference addressable; the address interval is 0000h – 03FFh. For usage in process control systems we defined the following fields in the memory of the RFID card, as seen in Table 1.

Table 1. Field description for the RFID card memory

Start address

Stop address

Offset Name Description

0000h 000Fh 16 bytes CID Card Identifier 0010h 0017h 8 bytes EXPDATE Card Expiration Date 0018h 0117h 256 bytes FT1 Fingerprint Template 1 0118h 0217h 256 bytes FT2 Fingerprint Template 2 0218h 0317h 256 bytes FT3 Fingerprint Template 3 0318h 031Fh 8 bytes CS_FT1 Fingerprint Template 1

Checksum 0320h 0327h 8 bytes CS_FT2 Fingerprint Template 2

Checksum 0328h 032Fh 8 bytes CS_FT3 Fingerprint Template 3

Checksum 0330h 034Fh 32 bytes POPCODE Permitted operations

codes 0350h 036Fh 32 bytes ROPCODE Restricted operations

codes 0370h 03AFh 64 bytes U_DATA Userd data (Name, Social

ID) 03B0h 03FFh 80 bytes AZCODES Access granted zones

codes

CID – Card Identifier – is a 16 bytes field that must be unique at least in each system. The content of this field is automatically generated using a pattern of random numbers. EXPDATE - Expiration Date – represent the date when the card become invalid and cannot be used in the system. In the memory of the RFID card could be stored up to three fingerprint templates, having each a size of 256 bytes. For that reason there are defined three zones: FT1, FT2 and FT3. Each fingerprint

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Knowledge Based Organization 2008 International Conference template has a checksum of 8 bytes that is memorized in CS_FT1, CS_FT2 and CS_FT3 fields. Each fingerprint template is encrypted and even if a card is copied it is not useful because the system require that data on card to match the data read from the fingerprint scanner. POPCODE & ROPCODE– Permitted & restricted operations codes – are two fields of 32 bytes each. Each byte signifies a permitted operation code, corresponding to the records in a global privilege database. These fields’ contents could be used in privileges management systems. U_DATA – User data field – is a zone of 64 bytes of memory where is stored the SSN (Social Security Number), Name, Function of card’s user. AZCODES – Access granted zones codes – is a field of 80 bytes. Each byte is addressable and defines a physical zone where the user has access granted. This field is used in access control applications.

4. Time & attendance software Each fingerprint access controller has an integrated RFID reader

and an internal memory where the event log is stored. The log contains every system event such as: successful user identification, failed user authentication, modifications of system’s configuration, user enrolment, user account removal. The event log could be downloaded via RS232/485 or Ethernet (RJ45) interface. The RS485 serial interface could connect up to 127 devices to create a local network. The Ethernet interface uses TCP/IP protocol, so there could be created a distributed time & attendance system with devices connected via VPN or Internet. The system architecture is presented in the figures below.

Using the event log, generated by the Fingerprint Access Controller with integrated RFID reader, and appropriate software we created a powerful time & attendance system. The solution described in this paper is an efficient and discrete way of monitoring the work time for each employee in a company, providing the statistics needed for evaluation of each person performances.

The statistics software is a web application written in PHP. The database is a relational one managed by the powerful MySQL RDBMS. All the entries in the event log are imported in the database

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Knowledge Based Organization 2008 International Conference tables. The software has three modules: one for employee data management, another for system user data administration and one for statistics.

Employee’s data management module is used for creating, removing and modifying employee profiles. This module is used for issuing RFID cards for each employee. All the data is introduced using forms generated dynamically by PHP scripts.

Figure 1 – System architecture for a distributed system

System’s user data management module is used for creating,

removing and modifying user accounts. Each user account has some privileges corresponding to the hierarchy of the company, so a department manager can view the statistics only for his subordinates. Using this module the system administrator could define the operating rights for each user and even can delegate administrative privileges.

The statistics module is user-friendly. It generates the presence reports in table or graphic format. The reports can be exported in PDF or XLS format, and the graphs can be saved as JPEG files. The statistics are generated in real-time and includes the following reports: presence for current day, the number of hours worked by each employee, the list with absent/ present employees.

5. Conclusion Modern hardware and software technologies were used to build

this complex distributed biometric time & attendance system. The fingerprint access controller with integrated RFID reader is a smart

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Knowledge Based Organization 2008 International Conference device and could send all the log data using the TCP/IP network interface, making possible the usage of the systems in LAN, WAN environments and either in Internet. The reports are available anywhere in the world, using a simple web browser

There cannot be found any substitute to biometrics for effective person identification, reason why biometrics represents a must for any system based on identity management. Having the biometric data on a RFID card represent a step forward, because the number of users for this kind of system is unlimited, and the user is not linked with a device.

The system described in this paper was developed as a result of two research projects with acronyms: AMPRENTA and AVPROT. The time & attendance system was implemented and tested at S.C. SEEKTRON S.R.L from Ploieşti with good results.

References

[1] Donahue, M.J, Rokhlin, S.I., On the use of level curves in image analysis, Image Understanding, Vol. 67, p. 652-655, 1992

[2] Finkenzeller K., Waddington R., RFID Handbook: Fundamentals and applications in contactless Smart Card identification, 2nd Edition, Wiley, 2003

[3] Jain, L.C., Halici, U., Hazashi, I., Tsutsui, S., Intelligent biometric techniques in fingerprint and face recognition, The CRC Press, 1999

[4] Lin, H., Automatic personal identification using fingerprints, Ph.D. Thesis, 1998

[5] Maio, D., Maltoni, D., Direct gray-scale minutiae detection in fingerprints, IEEE Transactions on Pattern Analysis and Machine Intelligence, p. 27-40, 1997

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ARCHITECTURE OF A FUZZY EXPERT SYSTEM USED FOR DYSLALIC CHILDREN THERAPY

Asst.Prof.Eng. SCHIPOR Ovidiu-Andrei, Prof. PENTIUC Ştefan-Gheorghe, PhD,

Assoc.Prof. SCHIPOR Maria-Doina, PhD

“Ştefan cel Mare” University, Suceava, Romania, [email protected], [email protected], [email protected]

Abstract In this paper we present architecture of a fuzzy expert system used for

therapy of dyslalic children. With fuzzy approach we can create a better model for speech therapist decisions. A software interface was developed for validation of the system.

The main objectives of this task are: personalized therapy (the therapy must be in according with child’s problems level, context and possibilities), speech therapist assistant (the expert system offer some suggestion regarding what exercises are better for a specific moment and from a specific child), (self) teaching (when system’s conclusion is different that speech therapist’s conclusion the last one must have the knowledge base change possibility).

Keywords: fuzzy expert systems, speech therapy

1. Introduction In this article we refer to LOGOMON system developed in

TERAPERS project by the authors. The full system is used for personalized therapy of dyslalia affecting pre scholars (children with age between 4 and 7). Dyslalia is a speech disorder that affect pronunciation of one ore many sounds. According to the statistics, about 10% of pre scholars are affected by this type of speech impairment [1].

The objectives of LOGOMON system are:

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- initial and during therapy evaluation of volunteer children and identification of a modality of standardizing their progresses and regresses (physiological and behavioral parameters);

- rigorous formalization of an evaluation methodology and development of a pertinent database for the speech productions;

- the development of an expert system for the personalized therapy of speech impairments that will allow for designing a training path for pronunciation, individualized according to the defect category, previous experience and the child’s therapy previous evolution;

- the development of a therapeutically guide that will allow mixing classical methods with the adjuvant procedures of the audio visual system and the design of a database that will contain the set of exercises and the results obtained by the child.

All these activities are currently completed and the therapy system is tested by Interschool Regional Speech Therapy Center of Suceava, Romania.

Figure 1 - LOGOMON speech therapy system

The figure 1 presents the menus of LOGOMON (Administrative

Tasks, Complex Examination, Therapy Organizer, Therapy Steps, Reports, Special Operations, About, Exit).

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2. Literature review There is a powerful preoccupation at the European level in

helping the people with such disorders because of highly social and affective implications.

Forward we enumerate most important projects related with speech therapy area:

- OLP (Ortho-Logo-Paedia) - develop in „EU Quality of Life and Management of Living Resources” interest area with coordination of Institute for Language and Speech Processing, Athena, Greek, with participation of France (Arches), Greek (Logos Centre for Speech-Voice Pathology), Spain (Universidad Politecnica de Madrid), Sweden (KTH- Royal Institute of Technology) and Great Britain (Sheffield University, Barnsley District General Hospital) [2], [3];

- ARTUR (ARticulation TUtoR) – one of the most recently speech therapy system [4], [5], still develop in 2006 year, with coordination of KTH-Royal Institute of Technology, Sweden;

- STAR (Speech Training, Assessment and Remediation) – a system develop by Alfred I. duPont Hospital for Children and University of Delaware for help speech therapist and children with speech problems [6];

- MMTTS-CSD (Multimedia, Multilingual Teaching and Training System for Children with Speech Disorders) – a complex project develop by University of Reading – Anglia, Budapest University of Technology and Economics – Ungaria, University of Maribor – Slovenia and Kungl. Tekniska Hogskolan, Sweden [7].

At the national level, little research has been conducted on the therapy of speech impairments, out of which mostly is focused on traditional areas such as voice recognition, voice synthesis and voice authentication. Although there are a lot of children with speech disorder, the methods used today in logopaedia are mostly based on individual work with each child. The few existent computer assisted programs in Romania don’t provide any feedback. At international level, there are software applications but quite expensive and improper for the phonetic specific of Romanian language.

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3. Logo-therapeutic aspects related personalized therapy In figure 2 are presented the main aspects related preschools

dyslalia therapy. In complex examination, speech therapist collects the base set of data used for child diagnostic.

Figure 2 - Personalized therapy steps and role of expert system

Speech examination has two distinct levels [8]: - examination of hear, voice, grammatical and linguistic skills; - speech production (articulator system and vocal production). Therapeutically program has two steps [9]: - generally therapy (mobility development exercises, air flow

control, hear development); - specific therapy (sound pronunciation, consolidation and

differentiation). In according with [1], speech therapy software can help speech

problems diagnostic, can offer a real-time, audio-visual feedback, can

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Knowledge Based Organization 2008 International Conference improve analyze of child progress and can extend speech therapy at child home.

4. Expert system – fuzzy approach With fuzzy approach we can create a better model for speech

therapist decisions. A software interface was developed for validation of the system.The main objectives of this task are:

- personalized therapy (the therapy must be in according with child’s problems level, context and possibilities);

- speech therapist assistant (the expert system offer some suggestion regarding what exercises are better for a specific moment and from a specific child);

- (self)teaching (when system’s conclusion is different that speech therapist’s conclusion the last one must have the knowledge base change possibility).

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Figure 3 - Example of speech therapy fuzzy inference

Fuzzy logic has ability to create accurate models of reality. It’s

not an “imprecise logic”. It’s a logic that can manipulate imprecise aspects of reality. In the latest years, many fuzzy expert systems were developed [10], [11]. In figure 3 we present an example of fuzzy inference, using three input linguistic variables (speech problems level, family implication and children age) and one output linguistic variable (weekly session number).

First three variables have following textual representation: speech_problems_level (1.62) = “low”/0.37,”normal”/0.62,”high”/0.0 family_implication (2.00) = “reduce”/0.0,”moderate”/1.0,”high”/0.0 children_age (4.50) = “small”/0.25,”medium”/0.5,”big”/0.0 We consider five rules for illustrate the inference steps: - IF (speech_problems_level is high) and (child_age is medium) and

(family_implication is reduce) THEN weekly_session_number is high; min (0.00, 0.50, 0.00) = 0.00 for linguistic term high

- IF (speech_problems_level is low) and (child_age is small) and (family_implication is moderate) THEN weekly_session_number is low; min (0.37, 0.25, 1.00) = 0.25 for linguistic term low

- IF (speech_problems_level is low) and (child_age is medium) and (family_implication is moderate) THEN weekly_session_number is low; min (0.37, 0.50, 1.00) = 0.37 for linguistic term low

- IF (speech_problems_level is normal) and (child_age is small) and (family_implication is moderate) THEN weekly_session_number is normal min (0.62, 0.25, 1.00) = 0.25 for linguistic term normal

- IF (speech_problems_level is normal) and (child_age is medium) and (family_implication is moderate

THEN weekly_session_number is normal min (0.62, 0.5, 1.00) = 0.50 for linguistic term normal Final coefficients levels are obtained using max function:

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high = max (0.00) = 0.00; low = max (0.25, 0.37) = 0.37; normal = max (0.25, 0.50) = 0.50 Each linguistic term of output variable has another representation

and in this manner is obtained final graphical representation of weekly_session_number variable. If system user wants to get a single output value, then area center of gravity is calculated. In our case (value 1.62), child must participate at one to two session (but two is preferred).

We implement over 150 fuzzy rules for control various aspects of personalized therapy. These rules are currently validated by speech therapists and can be modified in a distributed manner. We also develop a Java expert engine interface in order to test our knowledge base [9], [12].

Acknowledgements We must specify that these researches are part of TERAPERS

project financed by the National Agency for Scientific Research, Romania, INFOSOC program (contract number: 56-CEEX-II-03/27.07.2006).

References

[1] Tobolcea Iolanda, Logo-therapeutic intervention in order to help children with speech problems, Iasi, Romania, Spanda press 2002.

[2] Oster Anne-Marie, House David, Protopapas Athanassios, Presentation of a new EU project for speech therapy: OLP (Ortho-Logo-Paedia), Proceedings of Fonetik, pp. 45-48, Greek, 2002.

[3] Hatzis A., Kalikow DN, Stevens KN, OPTICAL LOGO-THERAPY (OLT) - A computer based speech training system for the visualization of articulation using connectionist techniques, Proceedings of Fonetik, pp. 125-131, Greek, 2002.

[4] Bälter, O., Engwall, O., Öster, A-M., & Kjellström, H., Wizard-of-Oz Test of ARTUR - a Computer-Based Speech Training System with Articulation Correction, Proceedings of the 7-th International ACM SIGACCES Conference on Computers and Accessibility, pp. 36-43, Baltimore, USA, 2005.

[5] Eriksson Elina, Balter Olle, Engwall Olov, Oster Anne-Marie, Kjellstrom Hedvig, Design Recommendations for a Computer-Based Speech Training

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System Based on End-User Interviews, Proceedings of International Conference On Speech And Computer, pp. 483–486, Patras, Greece, 2005.

[6] Bunnel H. Timothz, Yarrington M. Debra, Polikoff B. James, STAR: Articulation Training for Young Children, Proceedings of the Sixth International Conference on Spoken Language Processing, vol. 4, pp. 85-88, Beijing, China, October 16-20, 2000.

[7] Viksi K., Roach P., Oster A., Kacic Z., A Multimedia, Multilingual Teaching and Training System for Children with Speech Disorders, International Journal of Speech Technology, Vol. 3, No. 3, pp. 289-300, 2000.

[8] Stefan-Gheorghe PENTIUC, Ovidiu SCHIPOR, Mirela DANUBIANU, Doina SCHIPOR, Therapy of Dyslalia Affecting Pre-Scholars, Proceedings of Third European Conference on the Use of Modern Communication Technologies – ECUMICT 2008, pp. 317-326, Gent, Belgium, 2008.

[9] Ovidiu SCHIPOR, Doina SCHIPOR (2007), Computer Assisted Therapy of Dyslalia, Proceedings of the Knowledge Based Organization, pp. 151-156, Sibiu, Romania, November, 2007.

[10] Vadim Mukhin, Elena Pavlenko, Adaptative Networks Safety Control, Advances in Electrical and Computer Engineering, Volume 7 (14), No 1, pp. 54-58, 2007.

[11] Fuller R, Carlsson, Fuzzy Reasoning in Decision Making and Optimization. Physica-Verlag, Heidelberg, Germany, 2002.

[12] Mirela Danubianu, St.Gh. Pentiuc, Ovidiu Schipor, Cristian Belciug, Ioan Ungureanu, Marian Nestor, Distributed system for therapy of dyslalia, Proceedings of Distributed Systems Symposium, pp. 45-51, Suceava, Romania, September, 2007.

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SERIOUS FUN IN EDUCATION: USING MICROBLOGGING

Carmen Holotescu1, Gabriela Grosseck2, PhD

1Technical University,Timisoara, Romania, [email protected] of the West, Timisoara, [email protected]

Abstract Microblogging is the Web2.0 technology with one of the most important

impact in education in the last couple of years. On a microblogging platform, the users can send and receive messages via the web, SMS, instant messaging clients, and by third party applications. The most known platform is Twitter.

The authors introduce a Romanian microblogging platform especially designed for education, called Cirip, trying to provide arguments for using this microblogging platforms in education, underlining both the advantages and (possible) bad points. Some concrete examples are presented, in which the platform is used for delivering entire online courses, for courses enhancement, for communities of practice, and as an eportfolio.

Keywords: microblogging, cirip, online course, education, e-learning

1. Introduction Cirip.ro is a microblogging platform launched this year on March,

implemented by Timsoft, a company specialized in e-learning and mobile applications, under the first author's coordination. The platform already has many educational uses, for information and knowledge management, for courses enhancement, for collaborative projects in universities, for communities of practice, or as an eportfolio [7] [8].

Between June 4-18, 2008, the authors developed and moderated

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http://www.cirip.ro/

http://www.timsoft.ro/

Knowledge Based Organization 2008 International Conference an online course, in a private group. It is a world premiere, the first online course developed and run entirely on a microblogging platform.

2. The purpose of the course The aim of this course was to find out if microblogging can be

integrate in the lifelong learning / teaching / collaboration / business / blogging. The topics addressed were: microblogging platforms, Twitter facilities, Cirip facilities, uses in education, uses in business, uses in blogs promotion etc.

We wanted to investigate: if a microblogging platform, in particular cirip.ro, can be used

as a Learning Management System (LMS), and if it has the needed facilities to run an online course;

how to integrate microblogging with other Web2.0 technologies;

what are the differences between facilitating an online course on such a platform and one in a classic LMS.

3. Platform facilities and group The course was hosted and run in the private group cursmb1 of

the microblogging platform cirip.ro. A group has a special section for announcements (Group News) -

another original element of the platform, where the moderators can post notes and useful materials for the group activities (figure 1).

The authors have published in the announcements both notes on the proposed activities and course resources (mainly tutorials on course topics, with a variety of multimedia elements).

The discussions on the proposed themes were realized through messages sent by the participants in the group space. Messages can be sent / monitored online (web site or CiripFox – a Firefox extension) or as: SMS ( it’s simply to track the group messages via mobile phone); instant messages; e-mail (daily notices with followed messages, answers, new followers or news are received by those who activate this option); it is also possible to send e-mail messages on cirip.ro, including in groups.

1 http://www.cirip.ro/grup/cursmb

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http://www.cirip.ro/grup/cursmb



Figure 1. Group news, http://www.cirip.ro/grup/cursmb

Other valuable options are the facilities to send live video / audio

messages and to integrate multimedia objects in the notes, these becoming part of the information / communication flow (eg. audio clips saved on a server or vocaroo, audio clips from e-ok.ro, trilulilu or deezer; flickr or tinypic images, youTube, seesmic or dotsub videos; slideshare, voicethread or flowgram presentations; pdf, docs or spreadsheet files etc. [1]).

Besides discussions and debates conducted by the wide range of messages we carried out a series of collaborative exercises, which will be presented in the next section.

4. Participation in discussions Although initially 50 people have registered, 40 of them have

actively participated. The participants were mainly educational actors (students, teachers, developers, librarians etc.). They appear in the members section of the group. For each member, the total number of contributions in the group is listed. The Network option shows a graphical representation for the group.

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Figure 2. Group Members section(42 members)

There were almost 1100 messages written in the group,

approximately 100 after the end of the course. On average, each member had written 25 messages, which demonstrates an interested participation, and involvement.

The Tagcloud group section (present for any microblog too) allows interesting observations regarding the terms that appear most often in messages, the most active users, resources specified most frequently in messages.

Figure 3.Group Tagcloud

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In the figure 3 one can see the 50 words that have appeared most often in the last 500 messages.

Topics Tagcloud and Network are interesting features of the groups created on the cirip.ro platform, useful in analysing the interactions in learning or practice communities.

5. Collaborative activities and their results In this section we offer an overview of the collaborative activities

carried out during the course, which involved the use of other Web2.0 technologies. For most of the participants this was the first contact with them, so in advance helpful information were offered: 1. Puzzle images - we proposed a combination word - picture

(Creative Common from flickr) to be associated with microblogs and / or microblogging. Towards the end of the course this exercise was redone, to see if the opinion about microblogging was changed during the course [2].

2. A collaborative collection on del.icio.us created during the course, which was enlarged and used after the course end [3].

3. Translation of “Twitter in Plain English” video, which is part of the Common Craft Show collection. Video is posted on dotsub.com, where the transcript was translated through collaborative editing a document on writeboard.com [4].

4. A voicethread object with text and audio comments submitted by members[5].

5. Notes on a Flickr image. Starting from wordle.net, a resource suggested by a participant - TBD, a tagcloud with the words that appeared most frequently in the aprox. first 600 messages of the course was generated.

One can be observe: - the most active members - nouns, verbs, and notions that appeared most often in

discussions - participation - warm and open atmosphere.

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http://www.youtube.com/watch?v=ddO9idmax0o

http://www.youtube.com/user/leelefever

http://dotsub.com/view/665bd0d5-a9f4-4a07-9d9e-b31ba926ca78


Figure 4. Tagcloud made with Wordle,

http://www.flickr.com/photos/cami13/2573662470/

6. A code of good practice on microblogs with items written by the

participants using the collaborative platform writeboard. 6. Conclusions The course promoted values and attitudes among participants:

respect and confidence in themselves and others “you have the floor” discipline recognition of each person’s uniqueness / facilitate mutual

awareness responsiveness to the emotions of others valuing interpersonal relations adaptation and openness to new types of learning motivations and flexibility in developing their own

educational and vocational route interest in life-long learning developing skills to meet the demands of social life in general passionate discussions analysis of real needs and problems (examples: How do I ...?

Does anyone know if ..? etc.) polls (which are Ciriposphere verbs - the metaphors of

microblogging) perimeter changes and a direct dialogue with @ the virtually course turned into an interface to their own

experiences

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http://www.flickr.com/photos/cami13/2573662470/


Each student participated in exercises to explore personal motivation for professional use of microblogging (some have raised the problem of limited knowledge).

During the course the participants could develop the public part of their microblogs, writing public messages, following and discussing with other users, validating the topics of the course, monitoring feeds, and being part in other groups. After the course end, they continue to activate on the platform, communicating and collaborating with facilitators and other participants. This is important advantage of this platform, the learning community continue to be active after the course end.

The course has also allowed: a wide variety of expression forms (voice, video, images etc.)

using mashup tools already tested in education, training in communication of personal experience, not only didactical

a series of views on a topic of study (eg. Spore creatures) or a concept / technology (eg. CiripFox, mobile use)

the application of effective and flexible techniques, to use microblogging in education

reversibility of messages an expression of concern to provide all a set of best practices practice of behavior in favor of change graphic expression of relations between users the discovery of new ideas use imaginative capacity of network members humor, good mood development of "vocabulary" consulting statistics of using over time (dipity) promoting his own blog and microblog (export notes on the

blog) profile management weekend exercises can be considered as meme, turning into a

communication-type rotary "ambassadors" of ideas / concept / event (eg. Eurovision

live). There were also:

moments of inertia (see dipity to route messages over time)

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certain technical constraints (do not forget that it is an engineering platform growing), messages without dissipation

relationships reduced to some users unrealistic messages / considered foreign to the immediate

reality of course endless conversations, confusing interactions snob, megalomania, narcissistic style a certain degree of pollution or noise information.

In conclusion, respecting the learning time budget, each teacher can choose to use microblogging to enhance her/his courses. This is the option recommended by the authors of this material due to the following considerations: the need for personal development and planning issues related to the future course school and it can be build a curriculum microblogging based on the principle of learning spiral.

Acknowledgements The expression “serious fun” belongs to Conor Galvin, university lecturer

and researchers at UCD Dublin College of Human Sciences, Ireland [6].

References [1] http://www.cirip.ro/blog/?p=31[2] http://www.flickr.com/photos/cami13/sets/72157606890150518/[3] http://del.icio.us/tag/cursmb_cirip[4] http://dotsub.com/view/665bd0d5-a9f4-4a07-9d9e-b31ba926ca78[5] http://voicethread.com/#q.b153122.i0.k0[6] Galvin,C., Serious Fun: etwinning within teacher education programmes,

presentation at etwinning seminar, Leuven, Belgium, 3-5 october 2008 [7] Ebner, M; Schiefner, M.; (2008): Microblogging - more than fun? in

Proceedings of IADIS Mobile Learning Conference 2008, Inmaculada Arnedillo Sánchez and Pedro Isaías ed., Portugal, 2008, p. 155-159

[8] Grosseck, G., Holotescu, C., Can we use Twitter for educational activities, The 4th International Scientific Conference eLSE "eLearning and Software for Education", Bucharest, April 17-18, 2008.

[9] Carmen Holotescu, Notes on microblogging, http://www.timsoft.ro/weblog [10] Gabriela Grosseck, Notes on microblogging, http://grosseck.blogspot.com

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http://www.cirip.ro/blog/?p=31

http://www.flickr.com/photos/cami13/sets/72157606890150518/

http://del.icio.us/tag/cursmb_cirip

http://dotsub.com/view/665bd0d5-a9f4-4a07-9d9e-b31ba926ca78

http://www.timsoft.ro/weblog

http://grosseck.blogspot.com/


MODELLING AND SIMULATION IN THE MILITARY ORGANISATIONS

Vasile CĂRUŢAŞU, Daniela CĂRUŢAŞU

“Nicolae Bălcescu” Land Forces Academy Abstract

The present security environment imposed a certain acceleration of the initial reforms at the level of the military organization, which was highly generated by the diversity of the insecurity and dynamics of the sources and means to process the information having a special impact on the tasks attributed to the defence field structures and to the national safety, along with the military action development. The multinational structure’s getting involved in the peacekeeping missions, against terrorism and against drug traffic led to a reviewing of the developing concepts, in terms of the military actions. These types of actions, totally different from the classical ones, have imposed a remodeling of the means to analyze the possibilities and to make the right decision in the military field. The military confrontations and the future actions will more and more bear the outstanding technological marks. In the present, the moving from energetic towards information is highly reflected in concepts’ using, such as the informational conflicts and actions, the cybernetic ones, the psychological ones, mass media ones, etc.

Key words: Interoperability, Modeling, Simulation, Decision, Compatibility

1. INTRODUCTION The North Atlantic Alliance coherently shaped the conceptual

issues. In the present, there is a deep concern for the simulating models and concepts’ standardizing, including the protocols, the techniques and the processes. The interoperability standards’ reaching,

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Knowledge Based Organization 2008 International Conference in terms of the NATO military structures, represents the end-state of the modeling and simulating. This goal implies the efficiency of the training techniques and methods, where the training, by means of simulation, takes a leading place. On the other hand, the complexity theory, the chaos theory and the fractals theory are highly studied in the present, while the first applications did not cease to show up; in this context, we have the issuing of the first regulation in the command and control field of the military actions, by means of subjecting them to the concepts within chaos theory, by marines infantry Corp MCDP 6 - Command and Control. The problem in this context is that, although having a quantitative nature, the theories cannot stand any quantification in interrogating the social existence. Nevertheless, these theoretical frames act in the metaphoric plan, too (the butterfly effect), in order to provide the decisional support that the commanders need so much. Thus, we have reached the level of intensifying the qualitative methods within military actions studying, without neglecting the top technology. Therefore, we are facing a double qualitative quantitative duality, in interrogating the field in question, such an opportunity being the QFD method using itself, (Quality Function Deployment), which main goal is to provide the product in question, such as studying the interaction between the client and the provider.

Reaching these goals imposes the thorough analysis of the security environment and also the identification of the tendencies, an epistemological approach of the used theories and models in the field, a presentation and explanation of the new concepts that are used and also the implications on the developing concept of the military actions, in order to accomplish an assessing instrument of the Romanian Army capabilities in order to reach the assumed missions.

A deep understanding of the means the modern Armies conceive and develop the military actions, and impose some theoretical efforts out of the most diverse ones. The study is part of the efforts undertaken within NATO and European Union, in order to create a compatible platform and an interoperable one compared to the ones developed within the above mentioned ones, but which offer new analyses and optimum solutions based on the modern Mathematical

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Knowledge Based Organization 2008 International Conference models (the complexity theory, the Chaos theory and the Fractals theory and the QFD method, etc).

2. The Modelling and Simulation Problem in the Romanian

Army It is highly important to understand the unity of the social

phenomenon and of the joint military actions. The modeling and the simulating of the processes are to be differentiated by means of the specific functions of the structure elements.

The Ministry of Defence has issued the Developing Strategy of the Modelling and Simulating within Romanian Army, divided into three stages, starting with 2004 and to be finalized in 2014, which aims at integrating the capabilities in the M&S within all the leading levels and personnel, in order to increase the Armed forces‘competences and the training process efficiency.

We do appreciate that, in the present, on a national level, the applications in the field of modulating and simulating are disparate; there are no functional mixed teams that deal with their unity effort creating, starting from the legal frame.

Although within the National Defence University there is informatics applications meant to support the decision issuing, in terms of uncertainty, their content provides information only for the movement monitoring, for the force’s report quantitative assessment and for the monitoring of the artillery support possibilities. The applications allow the creating of new structures, quantitative assessed, for their friendly forces and for the adversary ones, while the programmes are not integrated and are independently used, for training purposes.

The Simulating Centre within GH uses JCATS system, implemented by CUBIC. Combining the multi-service interoperability with the land, air, water forces and the real command connections, the control, communication, computers and information ones (C4), the JCATS capacities and patterns provide the possibility to lead the tactic level activities up to joint group forces, including the entire spectrum of the conflicts, including the operations other than war, not only lethal, but also non lethal, in the open, village, and underground field. JCATS covers an entire set of operations, from the strategic level up

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Knowledge Based Organization 2008 International Conference to the tactical one, and it is used as an efficient instrument for training, analysis, activity support, for planning and experimenting the missions and rehearsals.

3. The Modelling and Simulation Problem within other

Armies The decision problems presented during the military conflicts are

quite complex and the classic mathematic method set or the military science ones prove to be limited their stating and their information processing.

The concerns in the modeling and simulating field are present not only at a national level, but especially in USA and in the European space.

The Joint Visions 2020 (IV 2020) of USA highlights the necessity to obtain the informational superiority (with impact on the supremacy within the entire activity spectrum of activities) and of the armed forces’ capability integrating within joint forces. Therefore, IV 2020 highlights the fact that the future operations will be performed by independent forces, of small dimensions, with great mobility and a great striking force, which can operate in a decentralized manner, but which greatly depend on information. In this context, USA will develop an endowment programme of one billion dollars, known as FCS Future Combat System, and which will become “the largest war machine in the history. Such changes are welcomed and will undoubtedly have long-lasting effects on the War fighter.

Within NATO structures among other modeling and simulating programmes, there is the JSAF programme, which represents the high fidelity operation theatre. It has implemented the AARS system -After Action Review System, which provides information about the maintenance capability involved by means of the MOE/MOP - Measure of Effectiveness / Measure of Performance. This programme has also implemented specific elements of C4ISR type. Lately, there is a constant concern to elaborate some strategies of dimensioning the forces and the means meant to obtain the capability within the entire armed spectrum; a good example is provided by FCS endowment programme, developed by USA Army and supervised by NATO.

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The German Armed Forces (Bundeswehr) faced the need to be transformed from a static army for a domestic defense to one flexible enough to fulfill international peacekeeping deployments. After a study of the current architecture, the German Armed Forces established that it was necessary to implement a new solution able to support mobile deployments. Through a strategic development partnership with the German Armed Forces, SAP developed mobile functionality to enable forces to efficiently and flexibly prepare, execute and complete deployed operations and exercises. The functionality leverages the SAP Mobile Infrastructure technology component of the SAP NetWeaver integration and application platform to execute field operations independent of a direct connection to a central SAP system.

The Israeli Navy is leveraging SAP Enterprise Portal and SAP Business Intelligence, key technology components of SAP NetWeaver, to integrate and analyze disparate data from existing non-SAP personnel, medical, and transportation and finance systems. The SAP rollout will equip the Israeli Navy with quick, role-based portal access to comprehensive, real-time information on all material assets and personnel in each theatre of operations to support efficient decision making.

Austria has been selected the Northrop Grumman to provide the enterprise portal technology and underlying process-based services to support the U.S. Army's task order to develop Defense Knowledge Online (DKO). The task order with a $267 million total was awarded under the U.S. Air Force Network-Centric Solutions contract vehicle and it is the largest portal task order ever awarded in the federal government.

We can notice that the importance and the huge amount invested in the modelling and simulating projects, within National safety and Defence are quite increased.

4. Directions in Modeling and Simulation In the present, we are facing a real revolution in the field of

military business, revolution imposed by the complex character of the social existence. The theories and concepts used so far have lost their viability, taking into account the new types of challenges and missions

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Knowledge Based Organization 2008 International Conference which the defence and national safety are to develop.

In this respect, the command and control system, known as C2, is insufficient to cover all the command needs, in a similar or complementary action. (Support and stability operations). These types of systems have evolved, according to the new needs in the tactical field, the C4ISR system, (Command, Control, Communications, Computer, Intelligence, Surveillance and Reconnaissance), and it represents a thorough system in leading the fight. This system had not got its maximum efficiency within coalition modern actions, due to its incompatibility to the communication systems and nation information within alliances. Therefore, we got to the conclusion that it is necessary to build a new system, known as C2 Approach, meant to answer to all the action types in the field of national safety. This new system involved the mixing of three dimensions: decision’s right distributing; information’s dissemination; the type of interaction among participants.

In this context, starting from the present theories, we have to explore the types of missions possible to be assumed by the Defence and National Safety Structures in the future. Out of the already assumed missions, the most important one is that connected to the terrorist actions. At a global level, this represents a major challenge which the democratic states will be facing. We will try to create a proper model to analyze this phenomenon and to use the proper method to predict the terrorist activity and the areas which these might develop. Lately, we have been facing a huge increasing of the terrorist incidents and of the victim’s resulted.

From this point of view, we have to analyze the assessing instrument of the Romanian Army’s capacity to fulfill the missions as a result of the Defence and National Safety Structures and of the Collective NATO and European Union security strategies at the outset of 2025, when we are totally integrated into NATO and European Union structures.

Another direction is represented by the correlation analyses between the missions and capabilities, as the factors that may influence the means to develop.

The next step is to set the relevant parameters for the main types of military actions developed by Land Forces, Air Forces, and by the

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Knowledge Based Organization 2008 International Conference Joint Naval Forces. For every type of mission it is highly important to establish the minimum parameters, which may provide their finest copy, but which may also provide the possibility of a qualitative and quantitative analysis.

One of the qualitative methods that can be used, is the QFD method, (Quality Function Deployment), which main goal is to provide the product’s quality regarded as client and provider, by means of the interaction studying. Adapted to the proposed research the provider is represented by the research team, while the client is the decision maker from the military hierarchy levels. We also appreciate that this method is quite useful in studying the correlation between the situation, in an operation theatre and the possibilities of the units acting in this area. Far from being a random option, QFD using was suggested by the most frequent using, within the products’ projecting by great multinational concerns, Lockheed Martin Aeronautics, the builder of F35 Lightening plane, being just one of them.

As previously mentioned, besides the classical models, used in the decision making process (linear programming, nonlinear and dynamic, the graphs theory and the transport issue, the games’ theory, the decision theory, in certain or uncertain conditions, the stocks’ theory, the waiting theory, the prediction by means of interpolating with different types of functions etc.), this new context is needed to be used in modern theories (the chaos theory, the fractal one, the complexity one), in order to get new optimum actions means for all the mission types identified (by means of introducing the settled parameters).

5. Summary The military organization reform, its transformation into a

professionalized army, well tailored and prepared, equipped according to NATO standards, interoperable, capable of accomplishing its missions, are the objectives our country has been focusing on. All these can only be accomplished by means of appropriate financial allocations, multi-annual well-grounded programmes (cost – efficiency analyses). At the same time, we need also emphasize the fact that all the military organizations from the North Atlantic Alliance are going through a reform process, in terms of searching

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Knowledge Based Organization 2008 International Conference new theoretical approaches, harmonizing and implementing the operating procedures for mission accomplishment. The modeling and simulation problem is one of the main directions of this general reform.

There are data confirming the interest of NATO and EU member states in the field of modeling and simulating the national defense and security actions. If Romania stays out of such projects, this would make it depend on the products developed by the countries interested in this field and would entail higher costs for human resource acquisition, implementation and training.

References [1] Coordinator Mircea Cosma, Vasile Căruţaşu, Formarea ofiţerului modern de

la realitate la necesitate, Land Troops Academy Publishing House, Sibiu, 2006, 271 pages, ISBN 973-7809-59-9, 978-973-7809-59-9

[2] Coordinator Mircea Cosma, Vasile Căruţaşu, Ofiterul modern. fundamente ale procesului de formare şi specializare, Land Troops Academy Publishing House, Sibiu, 2005, 260 pages, ISBN 973-7809-32-7

[3] Vasile Căruţaşu, Ghiţă Bârsan, Aplicatii ale modelarii si simularii actiunilor militare, Land Forces Academy Publishing House, Sibiu 2006, 110 pages, ISBN 973-7809-65-3, 978-973-7809-65-0

[4] Vasile Căruţaşu, Stoina Neculai, Consideraţii privind amploarea fenomenului terorist în perioada 1991-2003, U.N.Ap. International Conference, Bucharest, 14-15 Of April, 2005, ISBN 973-663-182-6

[5] The Developing Strategy of the Modelling and Simulating within Romanian Army

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DECISION OPTIMIZATION IN THE MILITARY FIELD

Vasile CĂRUŢAŞU, Daniela CĂRUŢAŞU

“Nicolae Balcescu” Land Forces Academy Abstract

Appointing optimal solutions in decision related problems is a difficult issue for which methods have been asserted, in certainty as well as in uncertainty conditions. These methods are useful in analysis, which imply finding “the best solution”, but, from a mathematical point of view, they don’t offer a rigorous sustain. The usage of such instruments is necessary and useful for the commanders and major states in finding solutions for every training, military operations and combat stage. The continuous increase of the collected, processed and transmitted information’ volume implies the increase of the efficiency and troop leadership’ quality by implementing the decisional methods, by means of calculus techniques. The knowledge of such methods gives the command officer the chance to better direct and provide the proper scientific solution.

Keywords: model, decision, certainty, uncertainty, optimal

solution 1. Introduction Every day life is marked by decisions, irrespective of the activity

that we perform and of the role that we play in society or family. But, when we find ourselves in a theatre of operations, and our decision can lead to the loss of subordinates’ lives, than, decision-making receives a special meaning. An arbitrary decision, without a proper study of the analyzed situation, can have disastrous consequences. Even more, in the military field, the decision made by leading factors has to depend on a solid scientific base.

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This theory’s evolution has targeted the elaboration of general methods that allow the generalization of the decision-making procedures.

The utility theory aims at introducing a proper consequence comparison system for the different ways that a decident can act in association with a numeric value, known as “utility”. In the 60’s, a new decisional analysis approach appears once with the passing over to the multi-decisional problem solving. The French researchers, disregarding the utility term, provided for the optimal variant establishing, a method based on concordance and discordance indexes that can be determined by matrix methods. Another decisional process approach is the group decision theory that analyses the crossing over of the individual to the group options.

All these researches aimed at finding objective methods of analyzing the variants placed in front of the decident and selecting objectively the optimal action variant.

2. Scenario We will focus on the analysis mode and decision-making in the

case of the described tactical situation in Fig.1.

1ST BASE 1ST ZONE 2ND ZONE 3RD BASE 2ND BASE C

Fig. 1

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The enemy forces are situated in the 1st Zone; they are equipped with 3 bulletproof transporters, anti armor, individual combat weapons, one self-propelled radar station for short distance and low altitude detection, and they intend to occupy a strategic position in the 2nd Zone.

The own forces dispose of 3(three) bases, situated as in Fig.1 and have the following:

• 1st Base: a carrier in the G Golf; • 2nd Base: at approximately 2000 km from the 1st Zone; • 3rd Base: at approximately 350 km from the 2nd Zone and at

approximately 250 km from the 1st Zone. The three military bases placed in the structure of own forces are

subordinate to a commandment situated in the 2nd Base. The created tactical situation analysis and the performed analysis

within the commandment have led to the following action variants: a) V1 – air attack from the 1st Base platform; b) V2 – rocket attack from the 2nd Base; c) V3 – land attack from the 3rd Base; d) V4 – rocket attack combined with land attack; e) V5 – air attack combined with land attack; f) V6 – rocket attack combined with air attack. The weather forecast predicts instable weather for the period the

military action is due to take place. The weather becomes a problematic aspect for the commander than when visibility decreases.

The mission will be considered accomplished, if the enemy and its means are destroyed in proportion of at least 70%.

The commandment analysis has to take in account the following criteria when making the decision according to the action variant:

a) C1 – time (hours); b) C2 – number of people; c) C3 – mission accomplishing costs (thousands of dollars); d) C4 – mobility ( operating systems’ time / number of hours); e) C5 – destruction capacity (number of strikes / surface). The information regarding the used criteria and the identified

attack variants are synthetically arranged in the table below:

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Table 1 C1 C2 C3 C4 C5

V1 2,5 23 180 2 0,7 V2 1,2 16 145 1,1 0,94 V3 4 30 210 0,5 0,5 V4 3,5 26 183 1,3 0,83 V5 4,7 25 205 3 0,72 V6 2,9 19 172 1,6 0,9

We will search for the optimal action variant using the moment

method and the linear attribution method. 3. Mathematical Model 3.1. Moment Method (Deutch – Martin) Applying the moment method, which consists of the alternative

moment calculation, in columns and rows, and their increasing arrangement, the results in the table below are obtained:


V3 1 1 0,8 0 0 V5 0,64 0,92 1 1 0,5 V4 0,71 0,58 0,65 0,32 0,75 V1 0,35 0,53 0,37 0,6 0,45 V6 0,21 0,41 0,48 0,44 0,9 V2 0 0 0 0,24 1

From the obtained information in this table, the conclusion is that

the problem’s optimal solution is V2. The most efficient way of attack is, according to this mathematical method, the one presented by the second action variant (V2): rocket attack from the 2nd Base.

3.2. Linear attribution method (Hungarian method) We take in account the same problem and attribute the following

importance to the criteria. The factors of our interest are: the destroying capacity generated by each variant, mission achievement costs and the time in which the target is destroyed.

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V1 2,5 23 180 2 0,7 V2 1,2 16 145 1,1 0,94 V3 4 30 210 0,5 0,5 V4 3,5 26 183 1,3 0,83 V5 4,7 25 205 3 0,72 V6 2,9 19 172 1,6 0,9 P 0,2 0,1 0,2 0,1 0,4

We build up the B matrix:


V1 V5 V3 V3 V5 V2 V2 V3 V4 V5 V1 V6 V3 V4 V5 V4 V6 V4 V4 V6 V1 V1 V4 V5 V5 V1 V6 V6 V2 V1 V6 V2 V2 V2 V3 V3 P 0,2 0,1 0,2 0,1 0,4

We’ll calculate the B matrix elements, which are inscribed in

Table 5: Table 5

1 2 3 4 5 6 V1 0 0,1 0 0,3 0,6 0 V2 0,4 0 0 0 0,1 0,5 V3 0,3 0,2 0 0 0 0,5 V4 0 0,1 0,8 0,1 0 0 V5 0,3 0,2 0,1 0,4 0 0 V6 0 0,4 0,1 0,2 0,3 0

This matrix generates the following matrix:

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Table 6 1 2 3 4 5 6

V1 0 0 0 0 1 0 V2 1 0 0 0 0 0 V3 0 0 0 0 0 1 V4 0 0 1 0 0 0 V5 0 0 0 1 0 0 V6 0 1 0 0 0 0

From this last matrix we can obtain the information regarding the

optimal solution. We have b21=1, b62=1, b43=1, b54=1, b15=1 and b36=1. Hence, we conclude that the alternatives’ order will be: V2, V6, V4, V5, V1, V3.

In this case also, the most efficient attack is presented in the second action variant (V2): rocket attack from the 2nd Base.

4. Scenario Solution From the analysis presented above, in good visibility conditions,

the optimal action variant is the one suggested by the second action variant (V2): rocket attack from the 2nd Base.

A very important analysis case is the establishing of the optimal solution in low visibility weather conditions.

Low visibility weather conditions have as consequences for the mission achievement, the following:

• Mission accomplishment time increasing; • Mission achievement costs increasing; • System operating time increasing; • Destroying capacity increasing. The criteria weight remains unchanged, but the problem

information, according to the mentioned criteria, are changed, this meaning that the values increase.

Therefore, resolving this problem with the two methods, the optimal solution in low visibility conditions is V6.

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5. Summary In good visibility conditions the V2 variant is the optimal

solution. A rocket attack is efficient, and has a great capacity to destroy, compared to the other variants that the own forces dispose of. Hence, V2 is the optimal solution in the context with a short time to accomplish the mission, a reduced number of people that prepare and serve it, and a low mission achievement cost.

In low visibility conditions the efficiency of any other attack is visibly decreased. The optimal variant is a rocket attack combined with air attack. V6 contains a great capacity to destroy, a relative low mission achievement cost and a good time to accomplish the mission.

The changing of the importance coefficients according to the criteria, leads to solution modification, a study of changing the optimal solution regarding these changes being extremely useful.

References

[1] Căruţaşu, Vasile; Bârsan, Ghiţă; Aplicaţii ale modelării şi simulării acţiunilor militare, Land Forces Academy Publishing House, Sibiu, 2006.

[2] Hampu, Alexandru; Cercetări operaţionale şi modelarea sistemelor militare, Land Troops Academy Publishing House, Sibiu, 1999.

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THE SIMULATION OF AN EDUCATIONAL PLATFORM

Asst.Prof. Mădălina Cărbureanu, Tutor, Elia Petre

Petroleum-Gas University, Ploieşti, Romania, [email protected]

Abstract The academically environment it can be considered to be a Knowledge

Based Organization (KBO), because uses different ways of managing the information and there is a batch of actors involved in this process. Also, there is a final goal, which consists in deliver to students, in an accessible format, the necessary information. The education platforms are a very useful way of deliver to students the solicited courses, laboratory materials, etceteras. Such a platform is Moodle, which supplies to the teacher and students a wide variety of tools for managing the existing information. In this paper is presented a simulation of some activities which take place on the Moodle platform, using some elements from the numerical programming structures domain. The software we chose to use for this application is Circuit Maker.

Keywords: KBO, Moodle platform, simulation, demultiplexer

1. Few words about Knowledge Based Organization Concept Knowledge Based Organization (KBO) concept refers to those

organizations which uses different means, as processes, systems or platforms, to generate, manage, transform, use and deliver inside the organization departments, the users necessary information, with the final goal of achieving the organization proposed goals. Clyde W. Holsapple and Andrew B. Whinston, defined in their work, the knowledge based organization concept, as follows: “O society of knowledge workers who are interconnected by a computerized infrastructure.

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Their work with various distinct kinds of knowledge is supported in a coordinated, cooperative manner by the computerized infrastructure” [1]. Such an organization, uses for achieving its goals, an infrastructure composed by: a certain number of local workstations, communications paths and distributed knowledge storehouses.

From the managerial point of view, James A. Alexander and Michael C. Lyons state that the knowledge based organization “offers a blueprint for integrating sales and service capabilities to create Professional Services organization” [2].

So as to any type of organization to have success in its activities, it must supply to its employees, the requested information and the necessary tools for accessing the information, any time they want and need.

2. Some features of Moodle platform For having any time he needs the necessary information, the user,

in our case, the student, can access a certain platform for downloading the courses and laboratory materials.

Such a platform is Moodle, created by Martin Dougiamas, a computer scientist and educator from Australia. This platform is free, is an open source software package, designed using the pedagogical principles, to help teachers create effective online learning communities. Moodle (Modular Object-Oriented Dynamic Learning Environment) platform is a software package for producing internet-based courses and web sites. It is a world-wide, ongoing development project designed to support a social constructionist framework of education. Moodle can be installed on any computer that can run PHP, and can support a SQL type database [4]. The actors which can use this platform are: the student, the teacher, the administrator of the platform and certainly, the product developer. Moodle is an open source Course Management System, so called CMS. CMSs are web applications, which offer to the teachers, the necessary tools to create a course web site and provide access control so only enrolled students can view it. CMSs also offer a wide variety of tools that can make a teacher course more effective, such as: the uploading and sharing of

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course materials, forums and chats (for the teacher – student communication and also for the communication between students), quizzes (a great tool for giving students rapid feedback), gathering and reviewing assignments, recording grades (an online grade book can give to students up-to-date information about their performances in a certain course) [4]. Moodle platform offer the possibility to deliver to students online courses, that is way this platform represents a great alternative to face to face courses, or to the traditional courses.

Moodle uses a number of interface conventions throughout the system. Important information is usually presented in the middle of the screen. On the left-hand side of the screen are presented several blocks that list available courses and site news. In the upper-right corner, is presented a drop-down menu with language options.

Figure 1: Moodle interface

3. A simulation of the Moodle platform using Circuit Maker In 1998, MicroCode Engineering has released a new Student

Version of their popular Circuit Maker electronic design and simulation software. “The software provides a comprehensive library of devices to choose from, and has various virtual instruments like oscilloscopes and multimeters that allow users to measure, test and troubleshoot the circuits they create” [3].

Using Circuit Maker we simulate some activities on the Moodle platform.

In our application the inputs are, the following: MP- checks if the platform is working properly;

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TL - refers to the list of uploaded projects; C - is connected to the courses uploaded on the platform by the teacher.

These inputs can have only a binary value: MP is 0 when the platform is not working properly and 1 otherwise;

TL is 0 if the list of projects is not uploaded and 1 if it is; C is 0 if the teacher did not have the opportunity to upload the courses and 1 if there are the courses on the platform.

For the internal representation of the inputs there are necessary 2 bits. There are described in Table 1.

Table 1 The binary codification of the inputs

xi i1 i0

MP 0 0 TL 0 1 C 1 0

The output of this application can be one of the following:

download – if there are no problems with the platform and there is uploaded the list of projects, as well as the courses one student can begin the download;

mail_prof – if the platform is working without problems but one of the list of projects or the courses are not uploaded the student can mail the teacher to notify him;

mail_adm – if there are some problems with the platform the user can inform the administrator.

In the output combination can be used a 3 bits codification like the one in the Table 2.

Table 2 The internal representation of the output

OUT download 1 0 0 mail_prof 0 1 0 mail_adm 0 0 1

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Our system is represented in Figure 2. When a student enters the platform first is tested if MP is 0 or 1: if it is 0, then the platform is not working properly and the output is mail_adm, otherwise if TL is 0 the result is mail_prof. If TL is 1 the user can try to access the courses and there are two possibilities: the first one, if C is 0 then again a mail to the teacher is sent or the second one, when C is 1, the download is started.

MP

mail_adm TL

C mail_prof

Figure 2: The system’s logical scheme

download

Furthermore, we notice that we can use only two types of

instructions: IF xi THEN ADR1 ELSE ADR0 and DO REG<-OUT GOTO ADR+; and that each one is written to a certain memory address (ADR) represented in Table 3.

Table 3 The instructions used and their memory address

ADR Instruction 0 If MP then 1 else 3 1 If TL then 2 else 4 2 If C then 5 else 4 3 Do REG<- mail_adm GOTO 0 4 Do REG<- mail_prof GOTO 0 5 Do REG<- download GOTO 0

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The first row in table 3 can be read: if MP is equal to 1 then execute the instruction stored in address 1 else the one in address 3. The instruction DO…GOTO in row four means that the output register is loaded with the value of mail_adm and then it is reloaded the instruction in address 0.

For the two types of instruction there are necessary 8 bits, but to distinct them we will use a supplementary bit called T which is 1 for the instruction IF xi THEN ADR1 ELSE ADR0 and 0 for DO REG <- OUT GOTO ADR+. We mark the fact that in the second instruction there are not values for xi with a ‘-‘.

The binary program is described in Table 4.

Table 4 The binary program ADR T i1 i0 ADR+

ADR1 ADR0 OUT

0 0 0 1 0 0 0 0 1 0 1 1 0 0 1 1 0 1 0 1 0 1 0 0 0 1 0 1 1 0 1 0 1 1 0 0 0 1 1 0 - - 0 0 0 1 0 0 1 0 0 0 - - 0 0 0 0 1 0 1 0 1 0 - - 0 0 0 0 0 1

To create the Circuit Maker program we use the majority rule: if,

for example, the input is 0 -0 -1 the fact that we have two 0 from three makes the result to be 0; on the other hand if we had 0 – 1 – 1 the result would be 1.

The simulation process is represented in Figure 3. In this scheme we observe that there are used three

demultiplexers and a logical gate OR.

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Figure 3: The simulation using Circuit Maker A demultiplexer, as we can see in figure 4, takes one data input

and a number of selection inputs, and it has several outputs. It forwards the data input to one of the outputs depending on the value of the selection inputs.

Figure 4: A demultiplexer in Circuit Maker

In figure 4 is captured the case when the value of MP is

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1(represented by the first demultiplexer) as well as C (which is the third demultiplexer), but the second input, the TL is 0. In the output the second light (the lower one) is on (in our scheme it is black). It means that the result of the simulation is a mail_prof.

4. Summary This part of numerical programming structures discipline,

electronic design and simulation software is useful in modeling different processes which take place on different types of platforms, used in academic environment. Using this type of simulation, we have a clear image about different decisions that have to be taken in certain situations, in educational process.

References

[1] Clyde W. Holsapple, Andrew B. Whinston, Knowledge-Based Organizations, Information Society 5(2), 1987.

[2] James A. Alexander, Michael C. Lyons, The Knowledge Based Organization, Four steps to increasing sales, profits and market share, SUA, Richard D. Irwin, Inc., 1995, Page 93-95.

[3] Jason Cole, Helen Foster, Using Moodle-Teaching with the Popular Open Source Course Management System, 2end Edition, SUA, O’Reilly Community Press, 2007, Page 1-3.

[4] http://www.aboutspice.com/details-219 [5] http://moodle.org/

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FOREST HARVEST PLANNING GIS MODEL

Lecturer, Aurelian Has, Senior Lecturer, Carmen Radut

University Constantin Brancoveanu, Pitesti, Romania, [email protected]

AbstractThe complex planning environment encountered by today’s harvest

planners requires that sites specific terrain data be considered in decisionsconcerning harvesting system selection.

The inclusion of terrain information in the timber harvest planningprocess should enable harvest planners to produce more economically andenvironmentally acceptable timber harvest plans.

The presented model utilizes a geographic information system to store,display, and manipulate the large amount of resource and terrain date requiredfor terrain classification.

Keywords: GIS, harvesting, planning, forestry

1.Introduction.Today harvest planners operate in a planning environment in

witch concerns over the adverse environmental impacts of timberharvesting activities must be balanced against economic advantages ofusing highly mechanized harvesting systems. In order to reduce theseverity of these environmental impacts without scientificallyincreasing harvesting costs requires that the harvest planner considersite-specific terrain factors and equipment characteristics duringharvest planning. For small planning areas, harvest planners havetraditionally relied upon personal experience and “rules of thumb” todeterminate the most appropriate harvesting system to employ on any

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given site. While this method may be satisfactory if the planner iswell-acquainted with the harvest site, it can result in excessive sitedamage and uneconomical harvesting operations if the planner isunfamiliar with the area. However, these traditional planning methodsmay not be applicable for detailed planning on large harvesting areaswith diverse terrain characteristics, especially when several equipmentcombinations are considered.

Consequently, a more structured method of considering terrainfactors is needed for harvest planning.

Terrain evaluation and classification systems have been used inEurope [3]. and [5]. and Canada [4]. to classify sites in terms ofequipment suitability ratings. Two types of terrain evaluation systemshave been used: descriptive classifications and functionalclassifications. In a descriptive classification system, the site isclassified solely in terms of the terrain factors that directly affectharvesting system productivity: (ground strength or bearing capacity,surface roughness, and slope). In functional classification, the terrainis directly classified in terms of the operability or inoperability of aparticular type of equipment. The main advantage of the descriptiveclassification system is that the site is classified in terms of permanentterrain factors rather than on the basis of the performance of aparticular harvesting machine. By concentrating on the site, ratherthan on the machinery, the effect of technical change resulting fromthe equipment development is eliminated. Thus, the terrain has to beclassified only once, not every time a new harvesting machine isintroduced.

While the descriptive classification approach to terrain evaluationhas many advantages, the time required to evaluate the terrain of largeforested areas may be excessive if manual mapping techniques areused. A solution to this problem is to use the speed and efficiency of acomputerized geographic information system (GIS) to evaluate terraincondition. GIS systems combine a database with computer graphics toefficiently maintain and display spatial information. The use of thesesystems to manipulate spatial date can provide a faster and moreefficient means of identifying potential terrain problems [1].

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The study describes a terrain evaluation model that utilizes GIS.The model was developed as a part of a cooperative research projectwith a major forest products firm to investigate the feasibility of usinga GIS to assist planning timber harvesting activities. The terrainevaluation model is used to determine equipment suitability for aforested area.

2. Terrain Evaluation SystemThe development of a terrain classification system for use in

planning harvesting activities requires three distinct steps. First,terrain factors important to harvesting decisions must be identified.Second, these terrain factors must be quantified and assigned a value.Finally, the range of the measured terrain factors must be subdividedinto classes to form the terrain classification.

While many terrain factors affect harvesting, in either a direct orindirect manner, forest terrain classification systems have concentratedon three terrain components: slope, ground strength. And surfaceroughness. Slope is included since it is a primary determinant of travelspeed and machine stability. Often, it can be the limiting terrain factorthat determines whether a parcel of land can be harvested with aparticular type of equipment. Ground strength, a measure of thebearing capacity of the soil, is usually included in these terrainclassifications because it affects the productivity of harvestingmachines and indicates the potential level of environmental damagecaused by those machines. Surface roughness, a measure of the sizeand distribution of obstacles, is important because it directly affectsmachine stability and travel speed.

The database component of a GIS contains forest types, terrainfactors (including elevation, slope, and aspect), site classes, inventorydata, and information on past harvesting, silvicultural and protectionactivities. In addition, roads, major rivers and streams, lakes, wetlands,regulatory zones, and corporate and political boundaries are stored ingeographical form. Each type of information is stored on separatethematic levels or layers within graphic design file.

The classification system developed for evaluating terrain is a

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modification of the terrain classification system developed for Canadaby Mellgreen [4]. Each of the three terrain component (slope, groundstrength, and surface roughness) is measured and classified separatelyaccording to procedures detailed by Davis [2]. Slopes values aredetermined from elevation date contained in U.S.G.S. 7.5 minuteDigital Elevation Models. The resultant slope values are divided intosix classes (Table 1) to form the slope classification. Normally, soilsurveys are used to determine the ground strength rating for an area.However, since this information is rarely available, ground strengthratings are determined from cover type and land use data stored in theGIS.

Using the rating criteria in Table 2, the species information fromthe GIS is classified (Figure 1) in terms of ground strength.

Surface roughness values are based on field surveys that assessthe number and size of obstacles in the survey area.

Table 1. Criteria for evaluating slope.Slope class Slope description Slope range (%)

1 Level 0-22 Slight 2-83 Gentle 8-154 Moderate 15-255 Steep 25-456 Very steep >45

The final step in the classification of the terrain involves thecreation of a composite terrain classification. The compositeclassification for an area is created by overlaying and intersecting theindividual terrain classifications polygons (slope, ground strength, andsurface roughness) to form a descriptive terrain classification for thatarea.

Table 2. Criteria for evaluating ground strengthGround

strength classGroundstrength

Soil moisture Soil texture Forest cover

1 Very good Very freelydrained

Coarse sands,gravel

Jack Pine, W.Spruce

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Groundstrength class

Groundstrength

Soil moisture Soil texture Forest cover

2 Good FreelyDrained

Sandy loams,Coarse sands

Balsam fir,aspen, birch,pine, spruce

3 Moderate Fresh Fine sandsClay Loams

Balsam Fir,Aspen, R.

Spruce4 Poor Moist Fine sands

Sandy siltPoplar, B

Spruce5 Very poor Very wet Organic B, Spruce

Tamarack6 Water - - Water bodies

3. Example terrain evaluationThe ground strength classification, illustrated in Figure 1,

indicates that the area is predominantly classified as having eithergood or moderate ground strength. The surface roughnessclassification, illustrated in Figure 2, indicates that the area ispredominantly classified as being slightly uneven or uneven. Theslope classification, illustrated in Figure 3, indicates that the area ispredominantly level.

Since the primary purpose of the terrain evaluation model is toassist the harvest planner in making decision concerning the use ofharvesting equipment, the descriptive terrain classification, describedabove, may not be directly useful in the planning process. However,this descriptive classification may be converted to a functionalclassification by considering the limiting operable terrain factors fordifferent harvesting systems. These limiting factors, shown in Table 3,were developed for each of the three harvesting systems commonlyused (manual fell/cable skidder, feller-buncher/grapple skidder, feller-forwarder) and then used to convert the descriptive terrainclassification into a functional classification by equipment types.

The functional terrain classification, illustrated in Figure 4,explicitly indicates to the harvest planner which areas may beharvested with each harvesting system. For the 506 hectares area usedin the example, 210 hectares is suitable for the operation of the feller-

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forwarder system and 205 hectares are suitable for the feller-buncher/grapple skidder system. The remaining 91 hectares are onlyoperable using the manual fell/cable skidder system.

Figure 1, 2: Ground strength classification, Surface roughness classification

Figure 3, 4: Slope classification, Functional terrain classification

Table. 3 Limiting terrain factor valuesHarvesting

SystemMinimum Ground

StrengthMaximum Surface

RoughnessMaximum Slope

Feller-forward moderate uneven 8-15%Feller-

Buncher/Grapplepoor rough 15-25%

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SkidderManual

Fell/CableSkidder

Very poor Very rough 25-45%

4. Integration with harvest planning decision support systemWhile the terrain evaluation system described above provides

harvest planners with useful information about equipment operability,it does not explicitly consider the economic aspects of harvestingequipment selection. To address this question, a modification of theterrain evaluation system has been developed for use with a harvestplanning decision support system (HPDSS). HPDSS consists of anoperational GIS, a set of operations research models, and aninteractive display system. HPDSS is designed to assist harvestplanners in determining optimal harvesting equipment assignmentsbased upon terrain/productivity relationships and operating costs.

Through the use of on-screen date prompts, the harvest plannerenters this productivity and cost information and delineates the area tobe considered in the equipment assignment analysis. HPDSS thendetermines the optimal assignment of harvesting equipment using amixed integer programming formulation and display the result, ingraphical and tabular forms, for the planner’s review.

A stand map of the northern third of the forested tract, withsystem assignment represented as shaded areas, illustrated in Figure 6.

In addition to the map display, HPDSS provides printed reports ofthe optimal system assignment.

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Fig. 6 Map, showing harvesting assignments, produced by HPDSS

5. ConclusionsThe terrain evaluation model, utilizing a geographic information

system, has been developed as a tool for planning large-scaleindustrial timber harvesting operations. The model combines terraindescriptions with machines operating criteria to produce mapsdelineating operable areas.

References:[1] Balser, R and K. Fila. Planning for terrain resource information

management in British Columbia. Proc. GIS’87- San Francisco Conference,San Francisco CA, 1987, p91-100.

[2] Davis, C.J. Planning timber harvest activities geographic information/decision support systems. Ph. D. Dissertation. Department of Forestry andnatural Resources, Purdue University, West Lafayette, In., 1987, 249p.

[3] Haarlaa, R. The effect of terrain on the output in forest transportation oftimber. Acta Forestalia Fennica, 1973, 43p.

[4] Mellgren, P.G. Terrain classification for Canadian forestry. WoodlandsSection, Canadian Pulp and Paper Association, 1980, 13p.

[5] Rowan, A.A. Terrain classification. Forest Record, British ForestryCommission, 1977, 22p.

[6] http://www.fao.org/docrep/004/AC142E/ac142e00.HTM

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CANDIDATE FACE DETECTION FROM COLOR IMAGES

Asst.Prof. Romana Oancea, Prof. Ştefan Demeter, PhD

“Nicolae Bălcescu” Land Forces Academy, Sibiu, România

Abstract

The face detection algorithm has various applications like recognition, expression analysis, and others. The first problem in the case of the recognition algorithm is the location of the face in the image or in the video sequence.

Keywords: skin likelihood, face detection, skin model 1. Introduction In the face recognition process, the first stage is the detection of

the faces from the image or video sequences, which has led to the development of different algorithms that attempt to classify the objects in the image into faces or non-faces.

Specialized literature presents a series of algorithms for face detection and, according to the methods that are used, they are included into several categories: [5]

- Algorithm for face detection by background examination; - Algorithms for face detection using the skin color; - Algorithms for face detection using the movement girls; - Algorithms for face detection using neural networks. Usually, the algorithm for automatic face detection in color

images is composed of several stages: detection of the regions that could be faces and extracting the regions and classifying the objects according to their properties into faces and non-faces. In the present paper we focus on face detection by using color.

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2. Building the model appropriate to the skin color In order for the color image to be segmented, first, it is necessary

to build a model of skin color. Thus, color images in RGB format, of small dimensions that contain the skin colors of more human races were taken into consideration. For these images the average of the Cb and Cr components and covariance. were calculated [4]

Each RGB color image is converted into the YCbCr format (Y = luminance, Cb and Cr = crominances) [1]:

⎪⎩

⎪⎨

⎧

−=−=++=

)(*713.0)(*564.0

*114.0*587.0*299.0

YRCrYBCb

BGRY (1)

For constructing the model corresponding to the color of the skin, the luminance Y component is eliminated and the averages (for Cr and Cb) and the covariance matrix are computed:

CB=[]; CR=[]; for i=1:no_file // read skin template im= imread(file(i).name); imycbcr = rgb2ycbcr(im); lpf = 1/9 * ones(3); cr = imycbcr(:,:,3); cb = imycbcr (:,:,2); cr = filter2(lpf, cr); cb = filter2(lpf, cb); cr = reshape(cr, 1, prod(size(cr))); cb = reshape(cb, 1, prod(size(cb))); CB=[CB,cb]; CR=[CR cr]; end medie_b=mean(CB); medie_r=mean(CR); covbr=cov(CR,CB); 3. Skin likelihood values 3.1. RGB skin color using the skin test image Before the test image segmentation, the skin likelihood value is

computed for each pixel in the test image by computing the mahalanobis distance from the mean (Fig. 2):

img_test=rgb2ycbcr(imread(img_test));

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[l c z]=size(img_test); skin1=zeros(l,c); cb=double(img_test(:,:,2)); cr=double(img_test(:,:,3)); for i=1:l for j=1:c b = double(img_test(i,j,2)); r = double(img_test(i,j,3)); x = [(r-medie_r);(b-medie_b) ];

skin1(i,j) = [power(2*pi*power(det(covbr),0.5),-1)]*exp(-0.5* x'*inv(covbr)* x);

end end

Fig 1 Original image Fig. 2 Likelihood image

The light areas correspond to possible faces. If the test image

contains several skin areas (Fig 3), they should be classified in order to detect only the areas corresponding to faces. One can see in Fig. 4 that, in addition to the face, a portion of the hand is also detected.

Fig 3 Original image Fig. 4 Likelihood image

A global threshold is applied to the image of probabilities and a

binary image is obtained which is then transformed, by means of morphology in order to detect the faces.

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[level EM]=graythresh(skin1); img_BW=zeros(l,c); img_BW(find(skin1>=level))=1;

Fig 5 Black&white image

(fig.1 original image) Fig. 6 Black&white image

(fig. 3 original image)

For color images there are several ways to determine the model of the skin. A method is described above. It utilizes averages and the covariance of the established skin images.

3.2. RGB skin cluster An area of an image is classified as skin area if the following the

conditions are met:[2]

⎪⎪⎩

⎪⎪⎨

⎧

∈>>>−>−

>>>

]255,0[,, and and 15

15,,min,,max20 and 40 and 95

BGRwhereBRGRGR

BGRBGRBGR

(2)

The source code for the application of the threshold for the R, G, B color plans is:

[l c z]=size(img); img_R=img(:,:,1); img_G=img(:,:,2); img_B=img(:,:,3); img_BW1=zeros(l,c); for i=1:l for j=1:l if (img_R(i,j)>95 & img_G(i,j)>40 & img_B(i,j)>20)

if (max([img_R(i,j),img_G(i,j),img_B(i,j)])-min([img_R(i,j),img_G(i,j),img_B(i,j)])>15)

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if (abs(img_R(i,j)-img_G(i,j))>15 & img_R(i,j)>img_G(i,j) & img_R(i,j)>img_B(i,j))

img_BW1(i,j)=1; end end end end end

3.3. YCbCr skin cluster When the image is of a YCbCr form, an image area is classified

as skin if the following conditions are met:[2]

⎪⎪⎩

⎪⎪⎨

⎧

∈<<<<

>

[0,255]Cr Cb,Y, 18013513585

80

whereCrCb

Y

(3)

The source code for classifying a color image is: img_YCbCr=rgb2ycbcr(img); img_Y=img_YCbCr(:,:,1); img_Cb=img_YCbCr(:,:,2); img_Cr=img_YCbCr(:,:,3); img_BW2=zeros(l,c); for i=1:l for j=1:c

if (img_Y(i,j)>80 & img_Cb>85 & img_Cb<135 & img_Cr>135 &img_Cr<180)

img_BW2(i,j)=1; end end end 3.4. HSV skin cluster

In order to impose a threshold for the H, S, V components which would determine the skin areas from an RGB image, it is necessary that during the first stage one should transform the R, G, B color image into H (Hue), S (saturation) ,V (value) format. In order to segment the image into candidate skin classes it is necessary that the following restrictions regarding the H,S,V color schemes be observed:[2]

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⎪⎩

⎪⎨

⎧

∈∈<<<<

]1,0[, ],360,0[ 68.023.0

500

VSHwhereS

H (4)

After the processing the color image into various formats and

after the application of the described thresholds the following results are obtained:

Fig.7 Original image

Fig.8 BW image use skin image subset Fig.9 BW image. Threshold aplied on

R,G,B planes

Fig.10 BW image Threshold aplied on

Y,Cb,Cr planes Fig.11 BW image. Thereshold aplied

on H,S,V planes 4. Conclusion By analyzing the obtained color images, we can conclude that

the imposition of the R, G, B threshold components has led to the weakest results. Next, in order to remove non-skin areas, we must apply morphological transformations to the black and white image.

The best result was obtained in the case of using test images with skin nuances.

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References: [1] Douglas A. Kerr, P. E, The sYCC Color Space, Issue 1.1, 2005; [2] Udo Ahlvers, Ruben Rajagopalan, Udo Zolzer, Model-Free Face Detection

and Head Tracking With Morphological Hole Mapping, 13th European Signal Processing Conference, Antalya, 2005

[3] Chang H., Robles U., Face Detection, EE368 Final Project Report - Spring 2000;

[4] http://webeng.cs.ait.ac.th/cvwiki/matlab:tutorial:detectface [5] http://www.facedetection.com/facedetection/techniques.htm

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ON THE APPLICATION OF THE ARTIFICIAL NEURAL NETWORK METHOD TO A NEURAL

SIMULATOR OF STEAM TURBINE POWER PLANT

Lector PhD candidate Eng, Liviu-Constantin STAN

Maritime University of Constanta, Romania, [email protected]

Abstract In the paper a neural simulator of steam power unit is presented as an

example of application of artificial neural networks (ANN) for modelling complex technical objects. A set of one-directional back-propagation networks was applied to simulate distribution of main steam flow parameters in the cycle’s crucial points for a broad range of loading. A very good accuracy and short computation time was obtained. The advantages make the simulator useful for on-line diagnostic applications where short response time is very important. The most important features of the simulator, main phases of its elaboration and a certain amount of experience gained from solving the task was presented to make the practical application of the method in question more familiar.

Keywords: neural modeling and simulating, turbine power plants, on-line diagnostics

1. Introduction Steam power unit or ship power plant is a very complex object.

To know its technical state is crucial for carrying out its operation in an optimum way, in which diagnostics is of a great importance.

Today, apart from safety, the taking care of operational process quality to obtain long-term reduction of cost has become a priority. It consists in expanding times between overhauls at simultaneous maintaining the efficiency of devices on a constantly good level. This

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is on-line diagnostics which makes continuous controlling the technical state of objects under operation possible. As it brings large economical profits the diagnostics becomes more and more important and its dynamical development can be thus explained.

Therefore is needed a device which would be able to accurately determined operational parameters of a given object so fast as to make it possible to compare them with current ones. To achieve that determination time of a correct operational standard should be of the order of milliseconds (resulting from sampling frequency of measuring systems). Heat flow diagnostics of steam power units is based on advanced analytical models. However because of their long computation time they can be used in off-line mode only. It means that periodic control of technical state of an object can be performed on the basis of earlier collected data.

The neural simulator operates as a black box and artificial neurons acts here instead of sophisticated models. Its response process consists in simple mathematical operations. Due to this fact a neural simulator is more primitive than an analytical one but it provides standard operational parameters of a given object very fast and with good accuracy that justifies its application to on-line diagnostics.

2. Phases of elaboration of the neural simulator 2.1. Choice of a simulated object A standard steam power unit of 200 MW output fitted with a

modernized TK 200 turbine was selected as the object to be simulated (Fig.1). Such selection has been justified by the wide application of units of the kind in Polish electro-energy system. Figure 1. B – Boiler, C - Constant pressure condensers, D – Degasifier, DP - Drip pumps, G - Electric generator, HP - High Pressure unit of condensing turbine, HRH - HP regenerative heaters, LP - Low Pressure unit of condensing turbine, MP - Medium Pressure unit of condensing turbine, RH - LP regenerative heaters, SC - Steam cooler, SI - Steam injectors, VC - Cooler of vapours from stuffing boxes, WP - Water supply pump, WT - Water supply tank .

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Figure 1: Simplified schematic diagram of the steam power plant, where

2.2 Training data acquisition In the ANN method a fundamental thing is to have an appropriate

set of training data as the rules written in neural model structure are generated on their basis. During training the network finds only relations between a given “input” and “output”, contrary to an analytical model elaborated on the basis of universal laws of mathematics and physics where experimental data serve only to control if theoretical laws are in compliance with reality.

Hence to apply the ANN method it is necessary to collect in advance a huge amount of experimental data for training the network.

For lack of operational data of a real steam power unit this author made use of DIAGAR software [2] which served as a source of data for elaborating the neural simulator in question. Such situation where an analytical simulator provides training data is very advantageous as it makes it possible to generate an almost arbitrary set of images for training the network.

Figure 2 shows schematic diagram of computations of the object taken into account in DIAGAR software. The main steam jet is marked red and regenerative steam extractions are signed with Roman numerals.

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Figure 2: Schematic computational diagram for the steam cycle considered in DIACAR software, where: i Main steam jet (flow) —> Steam extractions (I - I’M) G - Electric generator, D Particular devices of the steam power unit

Preparation of the training data set The training data set consists of independent and dependent

operational parameters of the power unit [1], namely: Set of independent parameters: Turbine set’s power output Fresh steam pressure Fresh steam temperature Superheated steam temperature Pressure in condenser, which define loading state of the steam cycle, see Table1. Set of dependent parameters: Mass flow rate (m) Pressure (p) Temperature (t) Enthalpy (h). The heat flow parameters of working medium are determined in

176 points of the cycle. As a result the data set covered a wide range of the power unit’s work, and amounted to 6300 combinations defining various loading states.

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Table 1: Set of the parameters defining loading states of the power unit [5] (Parameters of rated working state are marked red)

Set of independent operational parameters of the unit

Power Fresh steam

pressure

Fresh steam temperature

Superheatedsteam

temperature

Pressure in condenser

Number of combinations

N [MW]

po[bar] T1[°C] T2[°C] pk[bar] 6300

120 110 510 510 0.04 140 120 520 520 0.05

160 130 530 530 0.06

180 140 540 540 0.07

200 150 550 550 0.08

560 560 0.09

0.10

The task consisted in training the network in order to determine a set of diagnostic (dependent) parameters in response to a given set of independent operational parameters of the power unit.

3. Features of the simulator The simulator was composed of 12 neural networks. Each of

them was separately optimized. Due to the hardware limitations it was necessary to split all the simulated points of the steam cycle into 3 groups (modules), see Fig.2 and 3.

The main steam jet contains the points 1 through 21 located between the boiler and condenser including the flow part of the turbines.

The first steam extension is in the point 22 where 3 steam jets are mixed together: the regenerative steam extension from the first stage of the turbine, the steam from the sealing of HP turbine casing and that from the sealing of control valves.

The remaining extensions (points 23 through 30) are located in the remaining steam extension pipelines leading to relevant regeneration heat exchangers.

Figure 3 illustrates the procedure of information flow during the

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simulation process. Each of the networks operates separately and provides only one parameter and only within a given group of the cycle’s points. In all the 30 points the distribution of 4 parameters, i.e. p, m, t, h, can be simulated, or an arbitrary module and a parameter can be selected to obtain the pressure parameters from p1 to p21. The user can also select one of the simulated cycle’s points to know a concrete parameter value.

Figure 3: Schematic diagram of the simulator’s modular structure [6], where : h - enthalpy in a given point of cycle [kJ/kg] (resultant); h1 - h21 - enthalpy put out by 1st module of simulator : main flow; h22 - enthalpy put out by 2nd module of simulator.

4. Control of operational accuracy of the simulator Great attention was paid to continuous control of operation of the

neural networks as they represent rather primitive algorithms (not including any interpretation of physical phenomena). Also, much work was done to reliably present the simulator’s accuracy, especially as it appeared to be very different, depending on a concrete cycle’s point, simulated parameter and assumed state of loading.

Figure 4 presents distribution of values of the relative error of mass flow simulation for the main steam jet and all combinations of training data.

During simulation of the parameters an error value is automatically displayed provided its precise determination is possible at all. If a set of load parameters does not belong to that of training data then an expected value of the error is given.

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A more precise verification of operational quality of the simulator was performed by using the DIAGAR analytical simulator since its responses could be taken as a standard for the neural simulator. This way at the expense of some additional efforts response uncertainty of the network could be reduced to a minimum. Such operation was performed for the first steam extraction and due to its specificity an additional set of testing data was taken from the DIAGAR and on its basis the network’s generalization accuracy was determined for this module. In Figure 5 is presented an example of the results of the above described operation for distribution of mass flow rate at the first steam extraction. A testing data set not contained in the training data but belonging to the same loading range, was put into the network.

Figure 4: Distribution of simulation error of enthalpy parameter for the main steam jet (21 points of the cycle) [5] .

Figure 5: Results of testing the network’s generalization capability for mass flow rate at the first steam extraction.

5. Conclusions The neural simulator of the steam power unit was elaborated to

investigate possibility of its application to an on-line diagnostic system for so complex objects as steam turbine power plants are.

The presented simulator is a tool of the following features: -simple in use; -fast in operation: determination time of one parameter in 30

points of the cycle amounts to 30 ms -sufficiently exact; -inexpensive: to its manufacturing only a set of operational

parameters of a considered object, MATLAB software and a typical personal computer is required.

On the basis of the performed task were also analyzed some

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practical aspects of the neural modeling method, constituting its merits and drawbacks related to the considered application. The most important merit is the possibility of omitting the long analytical modeling process, hence lowering the modeling cost; and, the most important drawback is that the neural model does not include any physical interpretation of phenomena.

Modelling by means of neural networks is realized on the basis of existing operational or statistical data. In the case when character of a phenomenon is complex and multidimensional, and first of all not quite recognized, as well as when availability of the data is high then such conditions can be taken as very favourable for neural modelling. In some cases the method is the most suitable, and sometimes the only possible. In other cases it can be useful as an aiding element for analytical models.

The tasks assigned to advanced diagnostic systems applicable to large technical systems make that so different approaches as analytical methods, hidden ones (neural networks) or fuzzy logic, are used for them. Their mutual interaction is often very favourable for accuracy and credibility of an obtained result, i.e. assessed technical state of an object.

References [1] Głuch J., Verification of selected experimental coefficients of turbine flow

design process, based on standard measurements of power units, Doctorate thesis. Faculty of Ocean Engineering and Ship Technology, Gdańsk University of Technology. Gdańsk, 1992.

[2] Gardzielewicz A., Głuch J., Uziębło W., Jankowski T., DIAGAR software for heat flow diagnostics as a tool to predict repair time for component devices of turbine power systems. Proceedings of 5th Domestic Scientific Technical Conference on Diagnostics of Industrial Processes. Łagów Lubuski. September 2001.

[3] Korbicz J., Obuchowicz A., Uciński D., Artificial neural networks, Academic Publishing House (PLJ). Warszawa, 1994

[4] Demuth H., Beale M., Neural Network Toolbox, 2001.[5] Ślęzak-Żołna J., Neural simulator of a steam power unit, M.Sc. thesis.

Faculty of Ocean Engineering and Ship Technology, Gdańsk University of Technology. Gdańsk, 2004.

[6] Ślęzak-Żołna J., Głuch J., Neural simulator of a steam power unit, 2004.

148


REDUCING OF MARITIME ACCIDENTS CAUSED BY HUMAN FACTORS USING SIMULATORS IN

TRAINING PROCESS

Lector PhD candidate Eng, Liviu-Constantin STAN

Maritime University of Constanta, Romania, [email protected]

Abstract Given the increasing prevalence of automated systems on board ships, it is

important that the human element is considered throughout their design, implementation and operational use. Automation can be beneficial to operators of complex systems in terms of a reduction in workload or the release of resources to perform other onboard duties. However, it can also potentially be detrimental to system control through increasing the risk of inadvertent human error leading to accidents and incidents at sea.

A team of researchers from our University had participated at a study together with students, study which wants to release the dangerous situation on sea based on human factors. In this scope has been used a web base simulator, bridge and liquid cargo handling simulators, developing applications in navigation and ship handling area, with different grades of difficulty and risk. These applications brings the future deck officers in usually situations on board, forced to use the present navigation technology and study their options and reactions in these cases, focus on situations with risk of errors, human errors, appearance.

Keywords: Engine and Bridge technology, human factors, simulation, Bridge and Engine Team Management

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1. Introduction Over the last 40 years or so, the shipping industry has focused on

improving ship structure and the reliability of ship systems in order to reduce casualties and increase efficiency and productivity. We’ve seen improvements in hull design, stability systems, propulsion systems and navigational equipment. Today’s ship systems are technologically advanced and highly reliable.

With all of these the maritime incidents rate is still high, we have not significantly reduced the risk of accidents. There is because ship structure and system reliability are a relatively small part of the safety equation. The maritime system is a people system, and human errors figure prominently in these situations. About 75-96% of marine accidents are caused, at least in part, by some form of human error.

Therefore, if we want to make greater strides toward reducing marine accidents, we must begin to focus on the types of human errors that cause these and their relationship with the new technology on board.

In recent years a problem in international maritime training became obvious: the lack of experiential learning of entry-level officers or “lost apprenticeship”. Like in many other technical work systems the work processes on board have been an object of extensive automation. Human beings on board modern ships are needed predominantly for planning, control and supervision. However, in critical and unusual situations they have to step in actively. Such situations require flexible problem solving, improvisation and intuition. Furthermore, decreasing number of (experienced) crewmembers on board and the pressure of fast promotion into responsible positions have increased the “experiential learning gap’ of junior-officers. This problem is most obvious in tanker shipping, due to the demands on junior officers which are higher in this branch of our industry as compared for example with the field of container shipping.

2. Human factors Most people would agree with the old adage “to err is human”.

Most too would agree that human beings are frequent violators of the

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“rules” whatever they might be. But violations are not all that bad, through constant pushing at accepted boundaries they got us out of the caves!

As it is inevitable that errors will be made, the focus of error management is placed on reducing the chance of these errors occurring and on minimizing the impact of any errors that do occur. In large scale disaster, the oft-cited cause of “human error” is usually taken to be synonymous with “operator error” but a measure of responsibility often lies with system designers.

To find a human error is necessary to identify active and latent failure in order to understand why mishaps occur and how it might be prevented from happening again in the future.

As described by Reason, active failures are the actions or inactions of operators that are believed to cause the accident.

In contrast, latent failures are errors committed by individuals elsewhere in the supervisory chain of command that effect the tragic sequence of events characteristic of an accident.

The difference is that team error considers how a group of people made human errors when they work in a team or a group. Then we can define team error as human error made in group processes. Reason categorized human errors into three types: mistakes, lapses and slips. Mistakes and lapses arise in the planning and thinking process, whereas action slips emerge primarily out of these execution processes. Mistakes and lapses are more likely to be associated with group processes. Slips are errors in the action process of a single individual and are likely to be divorced from the activities of the team as whole.

Figure 1: Team error process

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3. Organizational factors The training of operators can only ever be part of the solution to

reducing accidents. Organisational factors also play a significant part in accident causation.

The analysis of human factors in accident causation is still relatively immature in the maritime world. Although databases held by insurers and classification societies do include human error taxonomies, little analysis is undertaken to identify trends or patterns. Even less analysis has been attempted in assessing the significance or frequency of organisational factors such as the incidence of commercial pressure or the effects of organisational culture on accident causation.

The differences in organizational culture between shipping companies are a well known phenomenon, but there has been little work on understanding the effects of organizational culture on safe and efficient performance. In much the same way as we are striving to identify a set of behavioural markers to assess the competence of individuals, so there is a need to establish a set of organizational metrics to determine the competence of shipping companies to perform safely.

4. Human factors issues in maritime industry What are some of the most important human factors challenges

facing the maritime industry today? A study by U.S. Coast Guard found many areas where the industry can improve safety and performance through the application of human factors principles. The three largest problems were fatigue, inadequate communication and coordination on navigational bridge, and inadequate technical knowledge. Below are summaries of these and other human factors areas that need to be improved in order to prevent accidents.

Fatigue has identified to be an important cross-modal issue, being just as pertinent and in need of improvement in the maritime industry as it is in the aviation, rail and automotive industries. Fatigue has been cited as the “number one” concern of mariners in different studies. It

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was also the most frequently mentioned problem in a recent Insurance and Classification Society survey. A new study has objectively substantiated these anecdotal fears: in a study of critical vessel casualties and personnel injuries, it was found that fatigue contributed to 16% of the vessel casualties and 33% of the injuries.

Inadequate Communications. Another area for improvement is communications between shipmates, between masters and pilots, ship-to-ship, and ship-to-VTS. Is stated that 70% of major marine collisions and allisions occurred while a pilot was directing one or both vessels.

Inadequate General Technical Knowledge. This problem is responsible for 35% of accidents. The main contributor to this category is a lack of knowledge of the proper use of technology, such as radar and electronic charts. Mariners often do not understand how the automation works or under what set of operating conditions it was designed to work effectively.

Inadequate Knowledge of Own Ship System. A frequent contributing factor to marine casualties is inadequate knowledge of own ship operations and equipment. Several studies and accidents report have warned of the difficulties encountered by crews who are constantly working on ships of different sizes, with different equipment, and carrying different cargoes. The lack of ship-specific knowledge was cited as a problem by 78% of the mariners surveyed.

Poor Design of Automation. One challenge is to improve the design of shipboard automation. Poor design pervades almost all shipboard automation, leading to collision from misinterpretation of radar display, oil spills from poorly designed overfill devices, and allisions due to poor design of bow thrusters.

Decisions Based on Inadequate Information. Mariners are charged with making navigation decisions based on all available information. Too often, we have a tendency to rely on either a favored piece of equipment or our memory.

Faulty Standards, Policies or Practices. This is an oft-cited category and covers a variety of problems. Included in this category is the lack of available, precise, written and comprehensible operational procedures aboard ship.

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Poor Maintenance. Poor maintenance can result in a dangerous work environment, lack of working backup systems and crew fatigue from the need to make emergency repairs. Poor maintenance is also a leading cause of fires and explosions.

Hazardous Natural Environment. The marine environment is not a forgiving one. Currents, winds and fog make for treacherous working conditions. When we fail to incorporate these factors into the design of our ships and equipment and when we fail to adjust our operations based on hazardous environment conditions, we are at greater risk for accidents.

5. Simulators and the process of training The use of simulation in providing solutions to the problems of

risk and crisis management and the optimal use of crew resources has a long established pedigree in maritime training.

These courses were developed to focus on the non-technical skills of flight operations and include group dynamics, leadership, interpersonal communications and decision making.

Bridge Resource Management and Engine Team Management courses are a more recent initiative, adapted directly from the aviation model for training the non-technical skills of resource management, and are not always based on the use of simulators.

Many types of simulator: bridge, engine and cargo control room, have tended to emphasise a physically realistic environment in which these exercises occur, although the of PC-based simulators for training some tasks is increasingly widespread.

In some parts of the world, simulators have been developed which have very high levels of physical fidelity, for example, multi-storey engine room mock-up and bridge simulators including features such as 360 degrees day/night views, pitch and roll, and full vibration and noise effects.

The only mandatory requirements in the maritime domain for the development of the non-technical skills of crisis management are those of the International Maritime Organization’s (IMO) Seafarer’s Training, Certification and Watchkeeping Code (International Maritime Organization, 1995). Table A-V/2 of this code specifies the

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minimum standard of competence in crisis management and human behaviour skills for those senior officers who have responsibility in emergency situations.

6. Virtual simulator training process Inside the project develop by our university about web based

simulation training; four tankers related IMO Model Courses was implemented with the new instructional design strategy (Familiarization, Oil tanker, Chemical Tanker, Gas Tanker). All courses have combined three different but interdependent content levels:

Theory Modules (with online-assessment) Simulator Exercises (with online assessment) Practical Training Tasks (planned in form of a tanker

qualification record book) The instructional design considered the general aim of the

courses. In the Familiarization course the simulation-modules and/or practical tasks were implemented into the theory. Since in many cases the course was made prior to sailing on a tanker, a lot of tasks could be fulfilled either by simulation or on-board practice.

It should be clear that all courses covered more than the requirements of the IMO-model courses. Every course starts with a “pre-test” to ensure that all participants are starting with at least a comparable level of knowledge. The main menu will follow the IMO-model course

7. Conclusions Without addressing the chronic issue of human error, the

maritime transportation system all over the world, already feeling the effects of spiraling costs associated with accidents, will have difficulty in absorbing the sweeping changes currently underway. Without mitigating the impact of human error, innovation in the maritime sector may introduce more cost than benefit and not be sustainable in the long run.

In order to reduce the number of accidents caused by human error, effort will have to focus on reducing latent error, mitigating the

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impact of psychological precursors, and improving the crisis management capability within the maritime community. Such an effort will not only reduce the accident rate, but will help to stimulate the innovation process by making new initiatives more likely to succeed.

Simulation, modeling and web base simulation training represents an important capability to ensure that innovation delivers on its promise of improved activity. To achieve this goal a concentrated effort is required to incorporate maritime simulation, modeling and web base training process into the innovation cycle.

References

[1]Chiotoroiu L., Dinu D., Hanzu-Pazara R., Pana I., Simulation Models in Maritime Distant Learning: Tankers Topping-Off, Conference “TECHNONAV ‘2006”, Constanta, Romania, 2006.

[2]Barsan E., Bridge and engine room teams cooperation, in loss of remote control scenarios, International Navigation Simulator Lecturers Conference, Genova, Italy, 2006.

[3]McCallum M.C., Raby M., and Rothblum A.M., Procedures for Investigating and Reporting Human Factors and Fatigue Contributions to Marine Casualties. Washington, D.C.: U.S. Dept. of Transportation, U.S. Coast Guard Report No. CG-D-09-97. AD-A323392, 1996.

[4]U.K. P&I Club, The United Kingdom Mutual Steam Ship Assurance Association (Bermuda) Limited. Analysis of Major Claims, 1992.

[5]International Maritime Organization, MSC/Circ.565 Fatigue as a contributory factor in Marine Accidents, International Maritime Organization, 1999.

[6]Huey, Beverly Messick and Christopher D. Wickens, Workload transition – Implications for Individual and Team Performance. Washington D.C: National Academy Press, 1993.

[7]Barnett, M.L., Gatfield, D., Habberley, J, Shipboard crisis management: A Case Study, Procceding International Conference Human Factors in Ship design and Operation, October 2002, pp 131-145, 2002.

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USER INTERFACES WITH WEB DYNPRO ABAP AND WEB DYNPRO JAVA

Eng. Cristea Ana Daniela, Asst.Prof.Eng. Adela Diana Berdie, Asst.Prof. Osaci Mihaela, PhD

University Politehnica of Timisoara, Timisoara, Romania,

[email protected]

Abstract To build web business applications SAP offers us two development tools the

NetWeaver Development Studio and the ABAP Workbeanch. Respective two Frameworks Web Dynpro Java and Web Dynpro ABAP. Both Framewors use the same Model View Controller concept separating the business logic from the User Interface. In this paper we presented trough example the way and the tools we can use to build a User Interface and some of the UI Elements that these Frameworks offer us. We presented from invisible UI Elements such as TransparentContainer until to Interactive UI Elements such as drop-down lists, InteractiveForm or LinkToAction. The Interactive Form UI Element offer us the possibility to use Adobe Technology in more as just one scenario, as for example interactive scenario or offline scenario to have an alternative to the traditional paper forms.

Keywords: Web Dynpro ABAP, Web Dynpro Java, User Interface, UI Elements.

1. Introduction Both Web Dynpros ( ABAP and Java) use the same Model View

Controller (MVC) concept separating the business logic from the user interface.

The goal of using the MVC design pattern is to reduce development time, to enable software reuse and to minimize the time and effort required for maintenance [1].

The Web Dynpro ABAP and Web Dynpro Java Framework

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provides view editors where the developer simply drags and drops the UI Elements into the view [2]. We can build a Web Dynpro application (Java or ABAP) without need of HTML, CSS or Java Script, the UI Elements don’t need coding and we use the so called “Layout Manager” to arrange a visual part of the screen. The screen content are generally made of views that can be combined and nested, we don’t worry about coding the User Interface and we can us focus on the application business logic.

To build these examples we have use SAP NetWeaver platform release 7.0 level 14.

When we use these Frameworks, we don’t have a control pixel with pixel of the UI Elements alignment, the design of these applications are limited and we cannot adding our own HTML Java Script code. We don’t have support for integration of Flash files or to use Ajax but this comes in the next releases. For example according to SAP [3] the next releases for ABAP will introduce a new UI Element called “Flash Island”. With this UI Element you can integrate and interact with flash files build with Adobe Flex Builder, will introduce Ajax support, drag and drop for the UI Elements shown to the user in a screen, etc. A new Book comes next year, Reference [4].

2. User Interfaces with Web Dynpro ABAP and Web Dynpro

Java The User Interface in both Web Dynpros is build from small units

named Views. A View it is the only component where we can integrate UI (User Interface) Elements and cannot be shown in a screen without integration in a window. To navigate from a view to another view we have inbound plugs and outbound plugs. In fig. 1 - left we present a Web Dynpro Java example and in fig. 1 – right we present a Web Dynpro ABAP example.

The screen content of the View (Web Dynpro ABAP or Web Dynpro Java) is designed with help of UI Elements and the way they are show into the View depend of four Layout categories: FlowLayout, RowLayout, MatrixLayout and GridLayout. We can set these categories for every Web Dynpro UI Element container.

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Fig. 1 Nested Views and navigation Web Dynpro Java and Web Dynpro ABAP

To construct a screen we can use UI Elements with which the user have to interact, non-interactive UI Elements used just for design or UI Elements that are invisible and we can use for example in a GridLayout Layout for a bether arrangement. We can use UI Elements of type TimedTrigger to trigger an event with a specified delay, UI Elements of type BusinessGraphics that can be used for the graphical illustration of data, an UI Element - InteractiveForm for Adobe Technology, UI Elements of type Group used as container for other UI Elemets, UI Elements of type MessageArea for moving the message location, etc.

3. UI Elements with Web Dynpro ABAP and Web Dynpro

Java In both Web Dynpro Frameworks each UI Element has several

properties that help us to control some characteristics and to do a dynamic programming and a static programming. In SAP documentation [5] it is presented for every UI Element and every property the data type we have to use for a dynamic programming and if this property can be binding or cannot be binding.

To create the User Interface with Web Dynpro (ABAP or Java) we can drag and drop an UI element into the View or we can create this element dynamic with the help of the Hook Method wdDoModifyView.

In fig 2 we present a Web Dynpro ABAP example with dynamic programming of the property enabled for the Button UI Element in

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accordance with SAP Documentation we have to do a data binding to an attribute that have the data type WDY_BOOLEAN.

Fig 2 Dynamic programming of the enabled property –Button UI Web Dynpro

ABAP

The image shown in User Interface fig. 2 for the first step of the RoadMap UI Element was take from Reference [6].

The only difference in Web Dynpro Java when we programming dynamically the property enabled for the same Button UI Element is the data type (BOOLEAN) of the attribute where we make data binding and the coding language Java.

3.1 Web Dynpro UI Element Container In both Web Dynpro frameworks we have so called containers.

The main goal of these containers is to group a set of UI elements. We should specify that all the UI Elements that are included in a View are integrate in a root container: RootUIElementConainer.

In fig. 3 we present an example of a container UI Element named Group.

The example presented is made in Web Dynpro ABAP and as you can see Group UI Element integrate here. UI Elements as LinkToAction, Label, InputField, TextView, TextEdit, Button and MessageArea.

In Web Dynpro Java this Group UI Element has the same functionality and the same structure. In both Frameworks we have container UI Elements as Tray, TransparentConteiner, etc.

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Fig. 3 Group UI Element Web Dynpro ABAP

3.2 Web Dynpro UI Element DropDownByKey Another UI Element that have the same functionality and the

same form in both Framework is DropDownByKey, presented in fig. 4.

Fig. 4 DropDownByKey UI Element Web Dynpro ABAP

This example was build with Web Dynpro ABAP and the list that

we show in this UI Element could be make with a Domain with fixed values or dynamic at View initialization.

In Web Dynpro Java the list that we show in this UI Element can be make with an Enumeration or dynamic at View initialization.

3.3 Web Dynpro UI Element TabScript In Web Dynpro ABAP TabScript UI Element allows the display

of a tab. For every Tab we can use a container where we integrate all the UI Elements that we want to show in that Tab, fig. 5.

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Fig. 5 TabScript UI Element Web Dynpro ABAP

In Web Dynpro Java TabScript UI Element allows the display of

a tab and the navigation between Views, because in every Tab we have to integrate a View, fig. 6.

Fig. 6 The way we can create two tabs into a TabScript UI Element Web dynpro Java

3.4 Web Dynpro UI Element MessageArea In both Web Dynpro Frameworks we have MessageArea UI

Element that specifies where messages should appear in the View. Default, without this UI Element, all the messages are show at the begin of screen in Web Dynpro ABAP and at the end of screen in Web Dynpro Java.

In fig. 7 we present an example made in Web Dynpro ABAP. The Fields FirstName and Email are mandatory and when the user don’t enter a proper value we show an Error Message with help of a Message Class.

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Fig. 7 MessageArea Web Dynpro ABAP

3.5 Web Dynpro UI Element ViewContainerUIElement In both Web Dynpro Frameworks we have

ViewContainerUIElements that offer us the possibility to integrate a View in another View. In fig. 7 we present an example made in Web Dynpro ABAP. The images used to create this application was take from Reference [7].

Fig. 7 ViewContainerUIElement Web Dynpro ABAP

3.6 Web Dynpro UI Element InteractiveForm In both Web Dynpro frameworks we have InteractiveForm UI

Elements that offer us an alternative to the Paper Forms through Adobe Interactive Form. We can use this technology in many scenarios: interactive scenario, offline scenario, print scenario, scenario with digital signature [8]. Before use this technology we have to check if Adobe Document Services (ADS) is integrate it in the SAP Web Application Server.

ADS Infrastructure was developed by Adobe, written in Java and is installed into a SAP NetWeaver Applicatio Server Java [9].

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Fig. 8 Adobe LifeCycle Designer tool – Web Dynpro ABAP

6. Summary Through development tools NetWeaver Development Studio and

ABAP Workbeanch respective Web Dynpro Java and Web Dynpro ABAP, SAP offers us a large number of UI Elements and two separate What You See Is What You Get (WYSIWYG) editors where the developer simply drags and drops the UI Elements that he needs. Both Frameworks use the same Model View Controller design pattern to build Multilanguage, reusable web business applications.

References

[1] Ulli Hoffmann, Web Dynpro for ABAP, Galileo Press 2006 [2] Rich Heilman, Thomas Jung, Next Generation ABAP Development, Galileo

Press 2007 [3] https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/500491

d5- 8f52-2b10-2894-8b8f3601a1fd[4] Philippe Gackstatter, Dominik Ofenloch, Einstieg in Web Dynpro ABAP,

Galileo Press, com next April 2009 [5] https://www.sap.help.com[6] http://www.eclipse.org/downloads/ [7] http://www.amazon.com/[8]http://help.sap.com/saphelp_nw04s/helpdata/en/c8/4adf7ba13c4ac1b4600d4d

f15f8b84/frameset.htm [9] Karl Kessler – Peter Tillert, Panayot Dobrikov, Java Programing with the

SAP Web Application Server, Galileo Press 2005

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https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/ 500491d5-8f52-2b10-2894-8b8f3601a1fd

https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/ 500491d5-8f52-2b10-2894-8b8f3601a1fd

https://www.sap.help.com/

http://www.amazon.com/


USING THE MVDB MODEL’S METHODOLOGY AND ARHITECTURE IN OBJECT-ORIENTED DATABASES

PROJECTS

Stud. Corina-Ioana CRISTESCU, Asst.Prof. Marian-Pompiliu Cristesc,u PhD

C.S.I.E. Faculty – A.S.E. Bucuresti ci_ @yahoo.comcristescu

”Lucian Blaga” University of Sibiu mp_ @yahoo.comcristescu Abstract:

In databases, much work has been done towards extending models with advanced tools such as view technology, schema evolution support, multiple classification, role modelling and viewpoints. Over the past years, most of the research dealing with the object multiple representation and evolution has proposed to enriches the monolithic vision of the classical object approach in which an object belongs to one hierarchy class. In particular, the integration of the viewpoint mechanism to the conventional object-oriented data model gives it flexibility and allows one to improve the modelling power of objects. The viewpoint paradigm refers to the multiple descriptions, the distribution, and the evolution of object. Also, it can be an undeniable contribution for a distributed design of complex databases. The motivation of this paper is to define an object data model integrating viewpoints in databases and to present a federated database architecture integrating multiple viewpoint sources following a local-as-extended-view data integration approach.

Keywords: object-oriented data model, OQL language, LAEV data integration approach, MVDB model.

1. Introduction Object-oriented databases are becoming more and more popular

for applications to support the complexity and the irregularity of the real-world entities. Moreover, with the expansion of the distributed

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Knowledge Based Organization 2008 International Conference technology and the Internet, new needs related to data sharing and data exchange appear. Thus, the development of advanced database models is required. Object-oriented technology seems to be the keystone of this evolution. Hence, much work has been done recently towards extending object-oriented database models with advanced tools such as view technology, schema evolution support, multiple classification, role modelling and the viewpoint paradigm. All these extensions require more flexible and powerful constructs than are currently supported by existing object –oriented models [10].

In the conventional object-oriented database model, the conceptual structure, that is a schema, is embodied by a collection of abstract data types called classes. The unique and permanent bond between an object and its class forbids a dynamic evolution of its structure and behaviour, or the representation of several points of view, independent or otherwise. However, in the real world applications, it’s often useful to cope with a multiple and evolving modelling of objects. This perception mode of data is called the viewpoint approach.

2. The Viewpoint Approach In computer science, most of data modeling systems don’t deal

with the variety of perceptions related to the same UoD and develop tools to create a single model for a single vision of the observed world. The viewpoint approach is opposed to this monolithic approach and makes it possible to model the same reality according to different points of view.

The viewpoint approach is constructed on the conjunction actor/information. Therefore, it is necessary to include the actor in the action. We thus define a viewpoint as “a conceptual manner binding, on the one hand an actor who observes and, on the other hand, a phenomenon (or a world) which is observed”. Many actors can observe the same UoD and produce various viewpoints on it. These last can be considered in several manners illustrated in Figure 1.

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Figure 1. The different manners to consider viewpoints on an UoD

Uniform viewpoints: in this case, all the actors have the same

vision of the UoD and produce equivalent representations. For example, let us consider many research teams, each one uses a different data model and considers it as the best one to represent a project.

Complementary viewpoints: in this case, each actor sees a part of the UoD and provides a viewpoint on it. Each viewpoint is a partial and coherent representation. The various representations which rise from the various actors are complementary and their union is a complete and coherent representation of the UoD.

Comparable viewpoints: in this case, the actors produce comparable representations according to the generalisation/ specialization meaning. Within the framework of our study we are interested in the second interpretation of the relation "actor-world", which supposes that the various viewpoints on the same UoD are partial but complementary representations of it.

The viewpoint mecahnim has been integrated into various contexts and used to solve different problems. Most works in the literature dealing with the viewpoint notion in object-oriented and conceptual modelling are much more pragmatic. In the following, we identify the main objectives in integrating viewpoints into computer systems. Note that there is no single use of this concept that includes all of these objectives.

3. Related Works In the field of databases, the concept of viewpoints is mainly

investigated within the concept of views and roles in the object-oriented database community. Most of the research works propose enriching the monolithic vision of the traditional object-oriented

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Knowledge Based Organization 2008 International Conference approach in which an object belongs to one and only one hierarchy class. They deal with the objects evolution and with the existence of multiple views of the same data. In this section, we briefly examine some proposals which present roles and views, and then we present an overview of our viewpoint approach.

3.1. Views Various view models have been proposed such as the multi-view

model of [10] and the view model of [1] and of [7]. In these works, views are exploited to allow different applications to see the same database according to different viewpoints. The viewpoint concept here supports external schema, which is the third level of the ANSI architecture standard upon which the construction and the use of relational database systems and the later object-oriented ones are centred.

3.2. Roles Objects with roles have increasingly been studied by several

authors [8, 3, 10]. Roles are useful for supporting objects with multiple interfaces that can be dynamically extended to model entities which change their behaviour, and the class they belong to over time. This task presents many problems such as uniqueness of objects identifier, strong typing, persistence, late binding, etc. in response to the role handling problem, several approaches have been introduced. In particular, the intersection-class-based and the role-hierarchy-based approaches are the most popular.

3. The Methodology of the MVDB Model The MVDB is an object-oriented data model with an extension by

concepts and mechanisms which allow the multiple, evolutionary and distributed representation of a database schema. This representation confers to an UoD several partial and complementary representations. Each partial description is based on a first description of the entities and extends it according to a given viewpoint. The multiple and evolutionary representation overcomes the restriction of the single and fixed object instantiation link.

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The methodology of the MVDB model relies on the following ideas:

• the viewpoint concept is considered as an inherent concept of the data model and not as an augmented mechanism on it;

• a database schema is a multiple description of the same UoD according to various viewpoints. A database schema is thus viewed as a set of VP schemas, as shown in Figure 2. Each VP schema represents an aspect of the data description and is held by an independent database system;

• the VP schemas construction is based on a basic one called the referential schema. This last holds basic data on the real word entities shared by all the VP schemas;

• objects evolution is held by allowing entities to acquire or lose partial descriptions in the different viewpoint schemas while preserving their identities.

Figure 2. The viewpoint approach

We point out that object identity is a central notion in our

approach. It is the same object described in many ways according of its membership in the various VP schemas. However, in order to ensure the components autonomy, local objects can be created and managed locally by VP databases.

We illustrate the viewpoint approach through a simple modelling example. It concerns the representation of a laboratory’s scientific staff (see Figure 3). We are particularly interested in the teaching and research activities of each member of the laboratory. Each viewpoint is an object-oriented schema that contains only information that is relevant to it. The Research VP, for example, is a hierarchical description of the laboratory’s members according to their research activity. Each member can have, simultaneously, a basic description

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Knowledge Based Organization 2008 International Conference at the referential level and one or two viewpoint descriptions according to his/her teaching and research activities.

Figure 3. A multi-viewpoint modelling example

Figure 4. The multi-viewpoint object representation

4. The MVDB Architecture We have noticed above that the viewpoint approach to databases

requires a distributed environment. Distributed systems [9, 5] have become increasingly important because of requests for organization and the growth of advanced techniques in the network management. These systems are characterized by three orthogonal dimensions: distribution, heterogeneity and autonomy. In this paper, we do not deal with the heterogeneity dimension. According to the autonomy dimension, [9] propose a classification most commonly applied to the distributed systems.

In a federated system two strategies are used to integrate independent databases in a unified logical global schema: the Global-As-View (GAV) strategy that defines the global schema as a view over the local schemas and the Local-As-View (LAV) strategy that defines the local schemasas views over the global schema [9]. We are particularly interested in the LAV architecture that will be adapted to

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Knowledge Based Organization 2008 International Conference our architecture.

Figure 5. The LAV data integration approach

The Local-As-View (LAV) strategy, presented in Figure 5,

consists of defining the local sources as views over the global schema. This presents two principle advantages: a local change to a data sourceis easily handled and the heterogeneity of the different components is supported. We recall that a viewpoint schema is a partial description of data according to a viewpoint. A Local-As- Extended-View (LAEV) process is then used in our system (see Figure 6).

Figure 6. The LAEV data integration approach

5. Summary In this paper, we have proposed a structural object database

model that integrates the viewpoint paradigm. This approach refers to the evolution, multiple description and distribution of objects. Also, it can make an undeniable contribution for the distributed design of complex databases. However, the same UoD can be described in a distributed fashion by different database schemas. Each one of these presents the entities according to a single viewpoint. A federated environment instead of a centralized one has been chosen to achieve our approach. Future work would concern the development of a data definition and manipulation language for the MVDB model, which is

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Knowledge Based Organization 2008 International Conference an extension of the OQL language. In addition, it would be interesting to develop an expression language to specify integrity constraints at the federation level.

References

[1] P. J. Charrel, D. Galaretta, C. Hanachi, B.Rothenburger, Multiple Viewpoints for the Development of Complex Software,Proceedings of the IEEE Int’l Conference on Systems, Man and Cybernetics, (1993), pp. 556–561. Le Touquet, France;

[2] O. A. Bukhres, A. K. Elmagarmid, Object-Oriented Multidatabase Systems, Prentice-Hall, (1996), Englewood Cliffs, NJ;

[3] S. Coulondre, T. Libourel, An Integrated Object-Role Oriented Database Model, Data & Knowledge Engineering 42(1), (2002), pp. 113–141;

[4] H. Naja, CEDRE: un modèle pour une représentation multi-points de vue dans les bases d’objets, Doctoral thesis, University of Henri Poincaré, Nancy 1, (1997);

[5] M. Gergatsoulis, Y. Stavrakas, D. Karteris, A. Mouzaki, D. Sterpis, A Web-Based System for Handling Multidimentional Information through MXML, Lecture Notes In Computer Science (LNCS 2151), (2001), pp. 352–365, Springer-Verlag;

[6] S. Abiteboul, A. Bonner, Objects and views, Proceedings of the Int’l Conference on Management of Data, ACM SIGMOD, (1991), pp. 238–247. Denver, Colorado;

[7] E. Bertino, A View Mechanism for Object-Oriented Databases, Proceedings of the 3rd Int’l Conference on EDTB’92, (1992), pp. 136–151;

[8] A. Albano, R. Bergamini, R. Ghelli, R. Orsini, An Object Data Model with Roles, Proceedings of the Int’l Conference on Very Large Database, (1993), pp. 39–51. Dublin, Ireland;

[9] F. Benchikha, M. Boufaida, The Viewpoint Mechanism for Object-oriented Databases Modelling, Distribution and Evolution, Journal of Computing and Information Technology - CIT 15, 2007, 2, 95–110, doi:10.2498/cit.1000692;

[10] G. Gottlob, M. Schrefl, B. Rock, Extending Object-Oriented Systems with Roles, ACM Transactions on Information Systems 14(3), (1996), pp. 268–296.

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IMPLICATIONS OF PARALLEL COMPUTING IN THE OPTIMIZATION OF DIGITAL IMAGE PROCESSING

ALGORITHMS

Bogdan Vasilescu, Eng. Gabriel Rădulescu, PhD

Petroleum-Gas University of Ploiesti, Romania, [email protected]

Abstract Digital image processing is one of the fastest growing fields of research

nowadays, with applications ranging from satellite imagery, medical imaging and videophone to character recognition, motion detection and photo enhancement. Digital image processing allows the use of much more complex algorithms for image processing, and hence can offer both more sophisticated performance at simple tasks, and the implementation of methods which would be impossible by analog means.

The current paper offers a possible solution to the optimization problems that arise from working with digital image processing algorithms. It focuses on using parallel computing architectures to increase the performance of the algorithms, especially by using the OpenMP standard.

Keywords: digital image processing, optimization, parallel

architectures, OpenMP 1. Introduction The software dimension associated with digital image processing

has known a spectacular development along with computing technology. The algorithms are now solidly based on mathematical grounds, giving birth to new approaches which are faster, more precise and can solve formerly unsolvable problems. Most of the times the increase in performance due to using a more efficient algorithm is considerable, reaching up to several sizes in scale. Therefore, faster algorithms render many new digital image

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Knowledge Based Organization 2008 International Conference processing techniques applicable and significantly reduce the costs of the systems.

Processing digital images typically involves several filtering steps, some of which are time-consuming [1]. However, there is an interesting method to improve program performance through parallel computing. Lately, since there are many computers with multi processors or multi-core CPUs, parallel processing becomes widely available. Nevertheless, having multiple processing units on the hardware does not make existing programs necessarily run faster. Programmers must take the initiative to implement parallel processing capabilities in their programs to fully make the most of the hardware available. OpenMP is a set programming APIs which include several compiler directives and a library of support functions. It was first developed for use with FORTRAN and now it is available for C and C++ as well.

The current paper focuses on using OpenMP-based tools to show how can multithreading be implemented to improve filter performance on multiprocessor systems and/or processors that support Hyper- Threading Technology.

2. Types of Parallel Programming Before beginning with OpenMP, it is important to know why

parallel processing is needed. In a typical case, a sequential code will execute in a thread which runs on a single processing unit. Thus, if a computer has 2 processors or more (either two cores or one processor with HyperThreading technology), only a single processor will be used for execution, therefore wasting the other’s processing power. Rather than letting the other processor sit idle (or process other threads from other programs) it can be used to speed up the algorithm.

Parallel processing can be divided into two groups, task based and data based [2].

- Task based: Divide different tasks to different CPUs to be executed in parallel. For example, a Printing thread and a Spell Checking thread running simultaneously in a word processor. Each thread is a separate task.

- Data based: Execute the same task, but divide the workload on the data over several CPUs (for example, converting a color image to

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Knowledge Based Organization 2008 International Conference grayscale). We can convert the top half of the image on the first CPU, while the lower half is converted on the second CPU (or as many CPUs you have), thus processing in half the time.

There are several methods to do parallel processing - Using MPI: Message Passing Interface - MPI is most suited for

a system with multiple processors and multiple memory modules (for example, a cluster of computers with their own local memory). MPI can be used to divide the workload across this cluster and merge the results when it is finished.

- Using OpenMP: OpenMP is suited for shared memory systems like desktop computers. Shared memory systems are systems with multiple processors but each are sharing a single memory subsystem.

- Using OpenMP is like writing smaller threads and letting the compiler manage them.

- Using SIMD intrinsic: Single Instruction Multiple Data (SIMD) has been available on mainstream processors such as Intel's MMX, SSE, SSE2, SSE3, Motorola's (or IBM's) Altivec and AMD's 3DNow!. SIMD intrinsic are primitive functions to parallelize data processing on the CPU register level. For example, the addition of two unsigned chars will take the whole register size, although the size of this data type is just 8-bit, leaving 24-bit in the register to be filled with 0 and wasted. Using SIMD (such as MMX), 8 unsigned chars can be loaded (or 4 shorts or 2 integers) and executed in parallel on the register level.

Figure 1: Overview of MPI, OpenMP and SIMD architectures

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3. OpenMP The OpenMP standard [4] is a specification for a portable

implementation of shared memory parallelism in FORTRAN, C, and C++. The specification provides a set of compiler directives and runtime library routines that extend FORTRAN, C, and C++ to achieve shared memory parallelism. OpenMP language extensions include work-sharing constructs, data environment and synchronization. The standard also includes a callable runtime library with accompanying environment variables.

OpenMP defines a set of C pre-processor pragmas (or directives for FORTRAN), which describe parallelism to the compiler (OpenMP has a limited ability to express task parallelism as well). OpenMPcompliant compilers are available for most operating systems, which makes OpenMP quite portable. Most important, however, OpenMP is compact and often non-intrusive and threading existing serial code rarely requires significant code modifications.

OpenMP uses the fork-and-join parallelism model [6]. In forkand-join, parallel threads are created and branched out from a master thread to execute an operation and will only remain active until the operation has finished, then all the threads are destroyed, thus leaving only one master thread. The process of splitting and joining the threads including synchronization for the end result are handled by OpenMP.

Figure 2: The fork-and-join parallelism model

A typical question is how many threads are needed for a specific

problem [5]. The number of threads required to solve a problem is generally limited to the number of CPUs available. As seen in the

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Knowledge Based Organization 2008 International Conference Fork-and-Join figure above, whenever threads are created, a little time is taken to create a thread and later to join the end result and destroy the threads. When the problem is small, and the number of CPUs are less than the number of threads, the total execution time will be longer (slower) because more time has been spent to create threads, and later switch between the threads (due to preemptive behaviour) then to actually solve the problem. Whenever a thread context is switched, data must be saved/loaded from the memory. This takes time.

Therefore, since all the threads will be executing the same operation (hence the same priority), one thread is sufficient per CPU (or core). The more CPUs available, the more threads can be created.

Most compiler directives in OpenMP use the Environment Variable OMP_NUM_THREADS to determine the number of threads to create. The number of threads can be controlled with the following C++ functions:

// Get the number of processors in this system int iCPU = omp_get_num_procs(); // Now set the number of threads omp_set_num_threads(iCPU); 4. Analysis and results Digital image processing uses specific algorithms and techniques,

also known as filters. Most of the times, image processing filters require time-consuming iterations. The current study focuses on finding a solution to reduce the execution time of such iterations, namely the for-loops and the double for-loops, which are most commonly found in such filters. In order to optimize the crossing of the loops the workload can be distributed to multiple threads running on multiple cores.

4.1. Parallel for Loop The following is a C++ code to convert a 32-bit Colour (RGBA)

image to 8-bit Greyscale image, a common operation used in image processing algorithms [3]. The sequence demonstrates the use of a simple parallel for loop.

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// pDest is an unsigned char array of size width * height // pSrc is an unsigned char array of size width * height * 4 (32-bit) // Use pragma for to make a parallel for loop omp_set_num_threads(threads); #pragma omp parallel for for(int z = 0; z < height*width; z++) pDest[z] = (pSrc[z*4+0]*3735 + pSrc[z*4 + 1]*19234+ pSrc[z*4+ 2]*9797)>>15; The “#pragma omp parallel for” directive will parallelize the

forloop according to the number of threads set. The following plot illustrates the performance gained for a

3264x2488 image on a 1.66GHz Dual Core system (Fig.3-a). By executing the problem using 2 threads on a dual-core CPU, the time has been cut by half (the speedup has doubled). However, as the number of threads is increased, the performance does not improve further due to increased time to fork and join.

Figure 3: Speedup of parallel for-loop; b,c. Speedup of the two solutions for

parallel double for-loop

4.2. Parallel double for loop The same problem above (converting color to grayscale) can also

be written in a double for-loop way, like in the C++ sequence below. for(int y = 0; y < height; y++) for(int x = 0; x< width; x++)

pDest[x+y*width] = (pSrc[x*4 + y*4*width + 0]*3735 + pSrc[x*4 + y*4*width + 1]*19234+ pSrc[x*4 + y*4*width + 2]*9797)>>15;

In this case, there are two solutions. The first makes the inner

loop parallel using the parallel for directive. When 2 threads are being

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Knowledge Based Organization 2008 International Conference used, the execution time has actually increased (Fig.3-b). This is because for every iteration of y, a fork-join operation is performed, which eventually leads to the increased execution time.

for(int y = 0; y < height; y++) #pragma omp parallel for for(int x = 0; x< width; x++)


For the second solution, instead of making the inner loop parallel,

the outer loop is the better choice. Here, another directive is introduced - the private directive [7]. The private clause directs the compiler to make variables private so multiple copies of a variable do not execute. In this case, the execution time did indeed get reduced by half (Fig.3-c).

int x = 0; #pragma omp parallel for private(x) for(int y = 0; y < height; y++) for(x = 0; x< width; x++)


5. Conclusions This paper presented a possible optimization solution to digital

image processing filters. The method uses commonly available parallel computing architectures, like the ones in multiple core CPUs, in order to divide the workload over several processors by assigning it to several execution threads.

The most promising results have been obtained with a twothreaded approach on a dual-core processor where the execution time of the algorithms was reduced by half. Therefore, the optimum number of threads to be used is equal to the number of CPUs available.

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Since the method proved to be viable, further research will be done by the authors in order to study the behavior of the algorithms on other multiple core processors (quad-core processors and so on).

References

[1] Gonzales, Woods, Digital image processing, Prentice Hall, 2008 [2] Malik, D. S., C++ Programming: Program Design Including Data

Structures, Course Technology, 2008. [3] Miller, A., Ford, L. F., Microsoft Visual C++ 2005 Express Edition

Programming for the Absolute Beginner, Course Technology, 2005. [4] OpenMP Application Program Interface, May 2008 [5] Gabb, H.A., Magro, B., Faster Image Processing with OpenMP, Dr.Dobb’s

Portal, 2004 [6] Begin Parallel Programming with OpenMP, http://www.codeproject.com/ KB/cpp/BeginOpenMP.aspx [7] 32 OpenMP traps for C++ developers, http://www.codeproject.com/KB/cpp/32_OpenMP_traps.aspx

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http://www.codeproject.com/


RISK MANAGEMENT FOR COMMUNICATION AND INFORMATION SYSTEMS

Mioara Braboveanu, Bogdan Ciortoloman

National Registry Office for Classified Information

Abstract All communication and information system (either handling classified or

unclassified information) must be submitted to a Risk management process. The risk management process is an ongoing process during the life cycle of

a communication and information system (CIS). It comprises mainly two stages: risk assessment stage and risk mitigation stage.

The purpose of risk management process is to identify the threats and vulnerabilities which are specific to a particular CIS based upon the results of the risk analysis and the goals are to select and implement countermeasures that will reduce or eliminate the number of threats or vulnerabilities available for exploitation, design a countermeasure strategy that will deter or prevent attacks (Internal and External) and achieve an acceptable level of risk at an acceptable cost.

“In GOD we trust, all other we monitor ………”

Security risk assessment is the process of identifying security

risks, i.e. the threats and vulnerabilities, of a CIS, determining their magnitude, and identifying areas needing safeguards or countermeasures. Security risk assessment serves to identify the security risks that exist, identify the current security posture of the CIS in respect to storing, processing or transmitting information, and then assemble the information necessary for the selection of effective security countermeasures.

Security risk assessment contributes to the decision on which security measures shall be required, and how the apportionment

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Knowledge Based Organization 2008 International Conference between technical and alternative security measures can be achieved, and gives an unbiased assessment of the residual risk. A benefit arising out of security risk assessment is the increased security awareness which will be visible at all organisation levels, from top-level management to operations and ancillary staffs.

Security risk assessment is not a task which is accomplished once for all time. It needs to be performed periodically, in accordance with the requirements of the agreed security accreditation strategy, in order to keep up to date with changes to the threats and vulnerabilities; and to the mission, its information, facilities and equipment.

The major resources required for security risk assessment are time, skilled manpower, and, preferably, an automated security risk assessment tool using a sound methodology. For this reason, the first security risk assessment will be the most resource consuming. Subsequent updates to a security risk assessment can be based on previous baselines of information, with a resultant decrease in the time and resources required.

The time allowed to accomplish the security risk assessment should be commensurate with its objectives. A complex CIS with significant volumes of information, and large numbers of users, will require more resources than a smaller stand-alone information system with limited amounts of information and a small number of users.

The success of a security risk assessment depends, largely, on the role of top-level management in the process. There must be management agreement to the purpose and scope of the security risk assessment, with that support being expressed to all levels of the organisation and management review and endorsement of the results of the security risk assessment.

Security risk management addresses the options for managing the risk, including elimination, limitation and acceptance. Security risk management involves planning, organising, directing and controlling resources to ensure that the risk remains within acceptable bounds, at optimal cost. It is also a collaborative process where representatives of various interest groups develop a shared understanding of requirements and options. Increased awareness will strengthen security and make it more compatible with user needs.

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Risk management is the process that allows IT managers to balance the operational and economic costs of protective measures and achieve gains in mission capability by protecting the IT systems and data that support their organization’s missions. This process is not unique to the IT environment; indeed it pervades decision-making in all areas of our daily lives. Take the case of home security, for example. Many people decide to have home security systems installed and pay a monthly fee to a service provider to have these systems monitored for the better protection of their property. Presumably, the homeowners have weighed the cost of system installation and monitoring against the value of their household goods and their family’s safety, a fundamental mission need.

The head of an organizational unit must ensure that the organization has the capabilities needed to accomplish its mission. These mission owners must determine the security capabilities that their IT systems must have to provide the desired level of mission support in the face of real-world threats. Most organizations have tight budgets for IT security; therefore, IT security spending must be reviewed as thoroughly as other management decisions. A well-structured risk management methodology, when used effectively, can help management identify appropriate controls for providing the mission-essential security capabilities.

Security risk management for CIS presents some particular difficulties arising from the dynamic nature of risk factors and the rapid evolution of the technology. Failure to consider security risk factors in an adequate and timely manner may result in ineffective and unnecessarily costly security measures. Therefore, security risk management needs to be considered as an integral part of the overall system life cycle process.

1. The security risk assessment process is a data collection and assessment exercise that addresses two basic questions: (a) what is the value of the subject of the security risk

assessment; and (b) what is the probability of the impact or consequence if the

threats do in fact materialise (i.e., the level of risk).

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Risk assessment is the first process in the risk management methodology. Organizations use risk assessment to determine the extent of the potential threat and the risk associated with an IT system throughout its life cycle. The output of this process helps to identify appropriate controls for reducing or eliminating risk during the risk mitigation process.

Risk is a function of the likelihood of a given threat-sources exercising a particular potential vulnerability, and the resulting impact of that adverse event on the organization.

To determine the likelihood of a future adverse event, threats to an IT system must be analyzed in conjunction with the potential vulnerabilities and the controls in place for the IT system. Impact refers to the magnitude of harm that could be caused by a threats exercise of a vulnerability. The level of impact is governed by the potential mission impacts and in turn produces a relative value for the IT assets and resources affected (e.g., the criticality and sensitivity of the IT system components and data). The risk assessment methodology encompasses nine primary steps, as follows:

Step 1. System Characterization In assessing risks for an IT system, the first step is to define the

scope of the effort. In this step, the boundaries of the IT system are identified, along with the resources and the information that constitute the system. Characterizing an IT system establishes the scope of the risk assessment effort, delineates the operational authorization (or accreditation) boundaries, and provides information (e.g., hardware, software, system connectivity, and responsible division or support personnel) essential to defining the risk.

Step 2. Threat Identification A threat is the potential for a particular threat-source to

successfully exercise a particular vulnerability. A vulnerability is a weakness that can be accidentally triggered or intentionally exploited. A threat-source does not present a risk when there is no vulnerability that can be exercised. In determining the likelihood of a threat, one must consider threat-sources, potential vulnerabilities, and existing controls.

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Step 3. Vulnerability Identification The analysis of the threat to an IT system must include an

analysis of the vulnerabilities associated with the system environment. The goal of this step is to develop a list of system vulnerabilities (flaws or weaknesses) that could be exploited by the potential threat-sources.

Step 4. Control Analysis The goal of this step is to analyze the controls that have been

implemented, or are going to be implemented, by the organization to minimize or eliminate the likelihood (or probability) of a threat exercising a system vulnerability.

Step 5. Likelihood Determination To derive an overall likelihood rating that indicates the

probability that a potential vulnerability may be exercised within the construct of the associated threat environment, the following governing factors must be considered: Threat-source motivation and capability, Nature of the vulnerability and Existence and effectiveness of current controls.

Step 6. Impact Analysis The next major step in measuring level of risk is to determine the

adverse impact resulting from a successful threat exercise of a vulnerability.

Step 7. Risk Determination The purpose of this step is to assess the level of risk to the IT

system. The determination of risk for a particular threat/vulnerability pair can be expressed as a function of:

- The likelihood of a given threat-source’s attempting to exercise a given vulnerability

- The magnitude of the impact should a threat-source successfully exercise the vulnerability

- The adequacy of planned or existing security controls for reducing or eliminating risk.

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Step 8. Control Recommendations During this step of the process, controls that could mitigate or

eliminate the identified risks, as appropriate to the organization’s operations, are provided. The goal of the recommended controls is to reduce the level of risk to the IT system and its data to an acceptable level.

Step 9. Results Documentation Once the risk assessment has been completed (threat-sources and

vulnerabilities identified, risks assessed, and recommended controls provided), the results should be documented in an official report or briefing.

A risk assessment report is a management report that helps senior

management, the mission owners, make decisions on policy, procedural, budget, and system operational and management changes. Unlike an audit or investigation report, which looks for wrongdoing, a risk assessment report should not be presented in an accusatory manner but as a systematic and analytical approach to assessing risk so that senior management will understand the risks and allocate resources to reduce and correct potential losses. For this reason, some people prefer to address the threat/vulnerability pairs as observations instead of findings in the risk assessment report.

2. Risk mitigation, the second process of risk management,

involves prioritizing, evaluating, and implementing the appropriate risk-reducing controls recommended from the risk assessment process.

Because the elimination of all risk is usually impractical or close to impossible, it is the responsibility of senior management and functional and business managers to use the lowest-cost approach and implement the most appropriate controls to decrease mission risk to an acceptable level, with minimal adverse impact on the organization’s resources and mission.

Risk mitigation is a systematic methodology used by senior management to reduce mission risk. Risk mitigation can be achieved through any of the following risk mitigation options:

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Risk Assumption. To accept the potential risk and continue operating the IT system or to implement controls to lower the risk to an acceptable level;

Risk Avoidance. To avoid the risk by eliminating the risk cause and/or consequence (e.g., forgo certain functions of the system or shut down the system when risks are identified);

Risk Limitation. To limit the risk by implementing controls that minimize the adverse impact of a threat’s exercising a vulnerability (e.g., use of supporting, preventive, detective controls);

Risk Planning. To manage risk by developing a risk mitigation plan that prioritizes, implements, and maintains controls;

Research and Acknowledgment. To lower the risk of loss by acknowledging the vulnerability or flaw and researching controls to correct the vulnerability;

Risk Transference. To transfer the risk by using other options to compensate for the loss, such as purchasing insurance.

The goals and mission of an organization should be considered in

selecting any of these risk mitigation options. It may not be practical to address all identified risks, so priority should be given to the threat and vulnerability pairs that have the potential to cause significant mission impact or harm. Also, in safeguarding an organization’s mission and its IT systems, because of each organization’s unique environment and objectives, the option used to mitigate the risk and the methods used to implement controls may vary. The “best of breed” approach is to use appropriate technologies from among the various vendor security products, along with the appropriate risk mitigation option and nontechnical, administrative measures.

Therefore the security risk assessment and risk management process should be undertaken jointly by the CIS planning and implementation authority(s), CIS operating authority(s) and the Security Accreditation Authority. The security risk assessment and risk management process should follow a structured approach (either carried out manually or using an automated tool), and should include the following stages:

(a) identification of the scope and objective of the security risk assessment;

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(b) determination of the physical and information assets which contribute to the fulfilment of the mission;

(c) determination of the value of the physical assets; (d) determination of the value of the information assets against

the following impacts: disclosure, modification, unavailability and destruction;

(e) identification of the threats and vulnerabilities to the risk environment, and the level of those threats and vulnerabilities;

(f) identification of existing countermeasures; (g) determination of the necessary countermeasures and a

comparison with existing measures; identifying those countermeasures which are already installed, and identifying those countermeasures which are recommended;

(h) review of the risks and the recommended countermeasures, taking into account the following options :

• risk elimination – the objective consisting in the total elimination of the real or potential vulnerabilities, by implementing the countermeasures in full;

• physical and information asset loss prevention – the objective consisting in the implementation of the countermeasures to prevent the loss as far as possible, knowing that some risks cannot be eliminated due to technological or operational reasons;

• physical and information asset loss limitation – the objective consisting in the implementation of the countermeasures to the extent that the loss is limited to an acceptable level; or

• acceptance of the risk of physical and information asset loss – where a decision may be taken to accept the risk and the consequences, for example, when the cost / impact of the loss is not significant, or the probability of loss is judged to be sufficiently small, or the cost of the countermeasures are much higher than, or not in balance with, the costs / impacts of the assessed losses; and

(i) development of a Security Risk Management Report, including a description of the countermeasures to be implemented, and a description of the residual risk.

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References

[1] Guidelines for security risk assessment and risk management of secure systems – ISP 205, version 0.3, June 2003, Council of the European Union;

[2] Guidelines for security risk assessment and risk management of communication and information systems, AC/35-D/1017 – Rev2;

[3] NIST Special Publication 800-30, Risk Management Guide for Information Technology Systems, US Department of Commerce, octombrie 2001;

[4] NIST Special Publication 800-30 Rev.A, Risk Management Guide for Information Technology Systems, US Department of Commerce, ianuarie 2004;

[5] Information Security Guideline for NSW Government – Part 1 Information Security Risk Management, NSW Department of Commerce, iunie 2003;

[6] Information Security Guideline for NSW Government - Part 2 Examples of Threats and Vulnerabilities, iunie 2003;

[7] Information Security Guideline for NSW Government – Part 3 Information Security Baseline Controls, iunie 2003.

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ONLINE VS OFFLINE IN MODERN TEACHING

Eng. Ilie Gligorea, Prof.Eng. Ghiţă Bârsan, PhD

“Nicolae Bălcescu” Land Forces Academy, Sibiu, Romania, [email protected]

Abstract With the tremendous development of the e-learning and its tools (online

courses and conferences, chats, video presentations), in-person activities such as face to face courses and conferences seem to lose ground. That’s why this paper addresses a comparative approach to the advantages and disadvantages of on-line courses and conferences versus those of in-person ones. We will see that face to face learning activities have some features that have on-line equivalents, while other characteristics are specific to one type or the other.

Keywords: e-learning, online, modern teaching

Before embarking on the research, we were aware of and influenced by a number of research-based notions of distance education. The first was that it requires a considerable amount of time to design and develop an online class. The instructor must shift from the role of content provider to content facilitator, gain comfort and proficiency in using the Web as the primary teacher-student link, and learn to teach effectively without the visual control provided by direct eye contact [1].

Moore [2] suggests that there are three types of interaction necessary for successful distance education:

1) learner-content interaction; 2) learner-instructor interaction; 3) learner-learner interaction.

Distance learning instructors need to ensure that all three forms of interaction are maximized in their course structure.

Peters [3] criticizes distance education, saying that it reduces

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Knowledge Based Organization 2008 International Conference education to a kind of industrial production process, lacking the human dimension of group interaction, and even alienating learners from teachers. He compares distance education to a mass-production assembly line process where a division of labor (educators and communications specialists) replaces the more craft-oriented approach of traditional face-to-face education. However, Peters' article predates the current Web-based boom in distance education. The personal computer and the Internet have probably been a greater force towards individualization than mass production.

With regard to the comparative approach mentioned above, first we can mention that in-person events have people attending sessions, traditionally gathered in a formal space during a specific scheduled time. This has its online equivalent in the form of chat-rooms, webinars etc. What makes some people praise the face to face meetings is that, beside the main topic debated during lectures and presentations, they really provide ground for discussions on sometimes random topics with random people. Most value of an in-person event comes from conversations on hallways, establishing contacts, finding vendors and sellers, socializing during coffee breaks and dinners. But these, too, have their own on-line equivalents in the shape of chat, like Twitter, Yahoo Messenger etc.

Nevertheless, it could be argued that often a more threaded discussion (like those in online conferences) is more effective.

Speaking of the social benefit of the conferences, they manage to bring together people with the same interests. Often these people are so stuck in their jobs and daily routines that the prospect of attending a course or a conference appears as a great opportunity for a change. This leads to a feeling of motivation and dedication (some call it inspiration) which is viewed as an emotional contagion that happens when you’re around people who share the same interest and enthusiasm.

Moreover, participants in the face to face events appear to be more motivated and paying more attention to the topic. They know what are there for, and that they had a lot of expenses, in terms of time and money, to be there.

Relatively, as regards the on-line conferences and courses they have the great advantage of much lower costs in terms of time and

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Knowledge Based Organization 2008 International Conference expenses. While the in person attending requires a lot of expenses (such as round-trip air fare, ground transportation, nights in a hotel, conference registration, food, as well as vacation time at job), the on-line events cut out a big part of them.

Besides, they offer the possibility of attending a lot more conferences and courses at lower expenses and also allow people to participate on their own schedule, without having to leave their work for a week or so in order to travel and to attend an event.

As online events allow the recording of sessions, people can participate even if they don’t do it on real time. The recordings provide also the opportunity of having a reference of the debated topics.

In terms of time management, on-line activities seem to be more effective, too, as the attendees have more time to think, to refine their questions and prepare their answers.

Another advantage is the possibility of quickly organizing ad-hoc online event when an issue arise the interest of a group of people. It’s easy to pull together some speakers, create a group, set up an online conference, advertise through the social media. Because of their specific topic and the urge of it, attendees will be more deeply focused (while in-person events tend to focus more broadly in order to appeal to a larger audience).

Besides, the atmosphere is more casual and everybody has a chance to chat.

Thus, given the advantages of lower costs and more time, online courses and conferences will probably increase. People will be more interested in online meetings offering the same topics as in-person events.

Taking into consideration also the economic downturns, everybody will likely seek to lowering costs (transportation, vacation from work post etc.). All it takes to raise the number of on-line attendees is getting a better handling of the online tools and environment.

Furthermore, while in-person courses and conferences seem to be preferred at a local level, on-line activities permit the broading of the audience spectrum.

An example of the transition from a traditionally in-person course

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Knowledge Based Organization 2008 International Conference to an online one is Academia Online [4] which has been providing, for all the Internet users, a number of online courses in Romanian. These courses run in the frame of a coherent system, integrated and easy to use. The authors of courses and the tutors has been offering support by one-on-one messages, by directing the learning process and by scheduling the activities according to the personal learning pace of each student.

Academia Online is a platform which presents the teaching institutions and training providers with the opportunity to publish and run their own online courses. These institutions can choose from a whole arsenal of functions and resources implemented within the system, which consist in course editing modules, continuing and final evaluation of the students’ results, and online managing of all the registered students. Thus, Academia Online is a tool of promoting the teaching and training institutions, by pulling together new students, regardless of their location and without any organizing and travelling expenses.

From the beginning, Academia Online set up the following goals: 1. providing high-quality resources for the permanent education,

for the training and personal development of students, young graduates, companies, educators and, generally, of any Internet user.

2. building an efficient platform, projected on academic standards, available to corporations, training and teaching institutions, and to individual authors for publishing their online courses.

3. setting up standards for design, infrastructure, security, didactic planning, support and interactivity within the virtual media, distance training methods, resources distribution, online testing.

Besides all of the traditional reasons for choosing an online programme rather than joining a classical training system, the main advantages of the Academia Online are: affiliation to a large community of interest in the fields of the chosen programmes, development of team working abilities and, last but not least, development of life-long learning abilities by the appropriate handling of the new information technologies. The future society, a society of knowledge and long-life training, will make a tough selection of human resources, based on these criteria.

From the viewpoint of the tutor, as a pedagogue in an e-learning

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Knowledge Based Organization 2008 International Conference medium, joining the team of Academia Online represents a boost of experience and training in using the educational platforms on the Internet, an increase of the specific abilities to communicate online and to manage virtual groups of students, a work place which doesn’t require neither his or her physical presence, nor a very strict schedule.

From the training institution perspective, the advantages involve the reduction in the resources needed for running the courses, the increasing number of attendees without any special additional efforts, the decrease of the expenses for teaching aids etc.

In online courses, the teacher usually makes class participation a higher percentage of the class grade, since teacher access to the permanent archive of threaded discussions allows more objective grading (by both quantity and quality). This differs from face-to-face classes where, because of time constraints, a relatively small percentage of the students can participate in the discussions during one class session. Because of the lack of physical presence and absence of many of the usual in-person cues to personality, there is an initial feeling of anonymity, which allows students who are usually shy in the face-to-face classroom to participate in the online classroom. Therefore it is possible and quite typical for all the students to participate in the threaded discussions common to online courses.

Contrary to intuition, current online courses are not an alienating, mass-produced product. They are a labour-intensive, highly text-based, intellectually challenging forum which elicits deeper thinking on the part of the students and which presents, for better or worse, more equality between instructor and student. Initial feelings of anonymity notwithstanding, over the course of the semester, one-to-one relationships may be emphasized more in online classes than in more traditional face-to-face settings.

It is obvious that nowadays the trend of using information and communication tools is increasing among the teaching and professional training institutions. Creating and developing services which provide both students and teachers tools such as access to virtual libraries, information resources, chat, assistance, online training is a necessity.

Combining a system based upon the up-to-date Internet

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Knowledge Based Organization 2008 International Conference technologies with the highest educational standards is the key to integrate the e-learning into the broader field of distance learning, as part of a coherent teaching program.

Trying to draw a conclusion, we may say that, paradoxically, in spite of their big benefits, on-line courses and conferences is complementary to their face-to-face counterparts, as both seem to respond to the human need of connecting. Online events are but the opportunity to make friends and colleagues, leading to people wanting to connect with each other, every so often after years of electronic-only contact.

References [1] Peters, O. 1993. "Understanding Distance Education." Distance Education: New Perspectives, eds. K. Harry , M. Hohn and D. Keegan. London: Routledge [2] Moore, M. 1993. "Three Types of Interaction." Distance Education: New Perspectives, eds. K. Harry , M. Hohn and D. Keegan. London: Routledge [3] Williams, V. & Peters, K. 1997. "Faculty Incentives for the Preparations of Web-Based Instruction." Web-based Instruction, ed. B. H. Khan. Englewood Cliffs, NJ: Educational Technology Publications. [4] Istrate, O. Academia Online. Apărut în: Elearning Romania, 2006-10-22. Bucureşti: TEHNE - Centrul pentru Dezvoltare şi Inovare în Educaţie. Disponibil online: http://www.elearning.ro

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NECESSITY OF USING MODELING AND SIMULATION IN THE ARMY

Coman Marian

“Nicolae Balcescu” Land Forces Academy, Sibiu Abstract

Since the early 1960's, Simulation has been one of many methods used to aid strategic decision making within industry. Its main strength lies in the ability to imitate complex real world problems and to analyze the behavior of the system as time progresses.

In an era of Force structure reductions, shrinking budgets and environmental restrictions, Modeling&Simulation (M&S) provides the opportunity to create relatively inexpensive, realistic simulation environments. M&S provides a method for training individuals and units in a safe environment, while optimizing the expenditure of your precious, limited resources.

We need to understand the past so that we can comprehend what

the future holds for us in the rapidly growing field of Modeling and Simulation. The objective of the present article is to provide you with an outline of the development of M&S and its relationship to such areas as Human Factors and Digital Media. M&S is a rapidly emerging field which is likely to bring about some significant changes in the way we learn, design complex systems, and entertain ourselves.

Computer simulations are built to satisfy our need to better understand an entity or a process, and to gain additional information and knowledge about the entity or process that would be too expensive, dangerous, or impossible to accomplish using other means.

For instance: - A commercial pilot repeating take-off maneuvers; - Reaction to emergencies at sea in a submarine; - Performance of a machine that does not exist;

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- Outcome of a non-existing conflict. The fact that these activities are expensive, dangerous or

impossible makes building computer simulations a logical choice with the following benefits:

- cost reduction - risk reduction - design support - scenario rehearsal possibility.

1. Modeling and simulation concept (M&S) First of all we have to do some explanations about elements used

by modeling and simulation. What is a Model? Model - "A representation of a system, entity, phenomenon, or

process. Software models of specific entities are comprised of algorithms and data." [1]

A model of something is the way we implement a representation of it. The model may be more complex, more profound or more exotic than the thing itself, but, in relation to that thing, it is just a representation.

What is "simulation" and what about "modeling"? Simulation - "The execution over time of models representing the

attributes of one or more entities or processes." [2] "The technique of imitating the behavior of some situation or

system (Economic, Mechanical etc.) by means of an analogous model, situation, or apparatus, either to gain information more conveniently or to train personnel." [3]

In its broadest sense, simulation is imitation. We've used it for thousands of years to train, explain and entertain. Thanks to the computer age, we're really getting good at using simulation for all three.

Simulations (and models, too) are abstractions of reality. Often they deliberately emphasize one part of reality at the expense of other parts. Sometimes this is necessary due to computer power limitations. Sometimes it's done to focus your attention on an important aspect of the simulation. Whereas models are mathematical, logical, or some

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other structured representation of reality, simulations are the specific application of models to arrive at some outcome.

Types of simulations Simulations generally come in three styles: live, virtual and

constructive. A simulation also may be a combination of two or more styles.

Live simulations typically involve humans and/or equipment and activity in a setting where they would operate for real. Think war games with soldiers out in the field or manning command posts. Time is continuous, as in the real world. Another example of live simulation is testing a car battery using an electrical tester.

Virtual simulations typically involve humans and/or equipment in a computer-controlled setting. Time is in discrete steps, allowing users to concentrate on the important stuff, so to speak. A flight simulator falls into this category.

Constructive simulations typically do not involve humans or equipment as participants. Rather than by time, they are driven more by the proper sequencing of events. The anticipated path of a hurricane might be "constructed" through application of temperatures, pressures, wind currents and other weather factors.

A simulator is a device that may use any combination of sound, sight, motion and smell to make you feel that you are experiencing an actual situation. Some video games are good examples of low-end simulators. For example, you have probably seen or played race car arcade games.

Simulators are employed widely by military forces and the transport industry, particularly to train pilots. They are also used to instruct aircraft engineers, and for entertainment. In flight simulators, powerful hydraulics actuators recreate the forces experienced when flying, while computer graphics simulate the view from the cockpit window.

Most people first think of "flight simulators" or "driving simulators" when they hear the term "simulation." But simulation is much more. Because they can recreate experiences, simulations hold great potential for training people for almost any situation. Education researchers have, in fact, determined that people, especially adults,

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learn better by experience than through reading or lectures. Simulated experiences can be just as valuable a training tool as the real thing.

Simulations are complex, computer-driven re-creations of the real thing. When used for training, they must recreate "reality" accurately, otherwise you may not learn the right way to do a task.

Modeling: a model definition A model represents a part of reality (target) which was specified

by a modeling view and described by modeling facilities in order to the purposes for recognition, understanding, and manipulation of the target.

A computer model, as used in modeling and simulation science, is a mathematical representation of something—a person, a building, a vehicle, a tree—any object. A model also can be a representation of a process—a weather pattern, traffic flow, air flowing over a wing.

Models are created from a mass of data, equations and computations that mimic the actions of things represented. Models usually include a graphical display that translates all this number crunching into an animation that you can see on a computer screen or by means of some other visual device.

Models can be simple images of things—the outer shell, so to speak—or they can be complex, carrying all the characteristics of the object or process they represent. A complex model will simulate the actions and reactions of the real thing. To make these models behave the way they would in real life, accurate, real-time simulations require fast computers with lots of number crunching power.

Why model? A computer model can generate new insights A computer model can make testable predictions A computer model can test conditions that may be difficult to

study in the laboratory A computer model can rule out particular explanations for an

experimental observation A computer model can help you identify what’s right and

wrong with your hypotheses The benefit of formal mathematical models is that they can show

whether proposed causal mechanisms are at least theoretically feasible

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and can help to suggest experiments that might further discriminate between alternatives.

2. Modeling and simulation in military domain Modeling and simulation allows leaders to solve the most difficult

problems, test courses of action, and learn the probable outcomes of strategies.

M&S enables leaders to make critical tactical and strategic decisions, supported by auditable quantitative and qualitative techniques, integrating science and technology with human perspectives.

The U.S. Department of Defense (DoD) has a large investment in modeling and simulation (M&S). There are several ways to categorize M&S including engineering models, analysis models and training models. Tremendous savings in manpower and financial resources are realized through the use of M&S. There are a tremendous number of challenges and opportunities that confront and confound those in positions to make decisions relative to where to invest the time and money to support current M&S, and future development.

Several Examples [4] 1960’s and 1970’s- NASA’s Astronaut Training: Simulators

played a major role in training astronauts. The Apollo Mission Simulator allowed astronauts to simulate the operation of what was then the most sophisticated vehicle ever built, the Apollo spacecraft. In the late 1970s, a Space Shuttle Mission Simulator was developed that simulated launch and landing of the Shuttle. In the early 1960’s, the slide rule and analog computer were the basic computational resources for engineers as they initially planned and designed to put man on the moon. Digital computers were available in those years, but they were generally too slow for simulation and required coding in machine or assembly languages. Computer technology improved during this period, spurring the development of continuous simulation on digital computers.

The Apollo Mission Simulators were developed to provide training for the flight crew in the operation of the spacecraft. These simulators were tied in with the Mission Control Center so that an integrated training could be accomplished with the flight controllers.

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They were also used for advanced training, particularly in emergency procedures. Numerous emergency procedures cannot be practiced in flight, either because they would be too dangerous or because there is no way to recreate the emergency. The importance of this facet of simulation was highlighted during the Apollo 13 mission, where the Command Module simulator was used to design procedures which allowed a crippled spacecraft to bring home the three astronauts. This is very well depicted in the movie, Apollo 13.

1980’s-1990’s – SIMNET Networked Simulation for Training. Simulators developed prior to the 1980s were stand-alone systems designed for single task training purposes, such as docking a space capsule or landing on the deck of an aircraft carrier. These systems were expensive, with costs in the ten’s of millions of dollars for an advanced pilot simulator system in the late 1970s, Some flight cost more than their aircraft counterparts. In 1988 the Defense Advanced Research Projects Agency (DARPA) initiated a lower cost program called Simulator Networking (SIMNET) that would join multiple tank simulators over a network such that each could detect, engage, and destroy the others. Graphics were computer generated and much less realistic than current PC-based games. However, the resolution was sufficient for effective training. SIMNET resulted in the institution of important simulation interaction principles and the creation of a network messaging protocol that allowed exchange data.

SIMNET was the predecessor of the Distributed Interactive Simulation (DIS) protocols. DIS was a logical next step which attempted to leverage the SIMNET technology so that it could be applied to a wider variety of combat vehicle simulators such as trucks, helicopters, fighters, ships, and soldiers. Using this distributed virtual battlefield simulation, virtual theaters of war are created that link multiple actors in real time.

The rapid development of this technology during the 1990s accelerated the drive for content realism, leading to an emphasis on storyline and the development of databases of historically and geographically accurate data. This drive for realism, compelling content, and storyline was applied to both imagined and actual warfare scenarios. In the summer of 1990, for example, a computer-based war game called Operation Internal Look was used by General Norman

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Schwarzkopf and his staff at the U.S. Central Military Command to run through scenarios of potential conflict in Iraq. Immediately after the invasion of Kuwait, the function of Internal Look changed from virtual to actual: it was now used to run variations of the real combat scenario.

2000-present – The Merging of simulations with Commercial Gaming. The shift in the culture of the military with regard to simulation design coupled with enlightened procurement policies led from SIMNET to Doom to America’s Army. The Marine Corps implemented a policy in 1996 aimed at implementing improvements in what was termed “Military Thinking and Decision Making Exercises.” It identified personal computer (PC)-based wargames as an important way to exercise these skills. A report was issued in 1997 observing that Department of Defense's simulations were lagging behind commercial games and advised joint research with the entertainment industry. This eventually led to the development of America’s Army, a massively multiplayer, online first person shooter game by the MOVES Institute at the U.S. Navy's Naval Postgraduate School. America’s Army simulates the training and deployment of Army Special Operation Forces. This freely downloadable game has not only become one of the most popular games, it is used as a recruiting tool, and has been modified for use as a training tool by the Army as well as other government agencies. As has happened with wargaming, the commercial side of simulation has driven improvement in the government side. The MOVES Institute used the commercial game Counter-Strike the model for America's Army.

M&S in Romanian Army In Romania, in June 17, 2002 was founded the Simulation

Training Center (STC), located in the National Defense University (NDU) Bucharest. [5]

STC is a fundamental element in transforming and modernizing the Romanian Armed Forces.

The priority of simulation training will be: training, education and decisional support for conducting military operations; analysis; research, development, procurement.

In our army has been established a training strategy using simulations as a fundamental element in transforming and

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modernizing the Romanian Armed Forces (RAF). This strategy includes application of simulations in execution of training, education, exercises and military operations.

The STC could be seen as the nucleus of the national military education and training simulation program. The center can also be an important adjunct to a future national military command center, a nerve center for national and NATO operations. It can provide a capability to participate in NATO exercises and NATO-PfP led exercises.

The operational goals for STC are: 1. Focus training on Company, Battalion and Brigade

commanders and their staff; 2. Train throughout the complete spectrum of military operations; 3. Identify likely areas of supporting operational units through

simulating possible courses of action during the military decision-making process;

4. Connect the STC with other simulation centers throughout NATO countries.

Another organization, in Romania, in the spectrum of modeling and simulation is Military Equipment and Technologies Research Agency (METRA).

The main activities of METRA are oriented in technological demonstrators, fundamental research, technological development of new equipment, concept studies, upgrading/modernization of the existing equipment.

In the virtual simulation activities, METRA is known for individual and crew simulators – to train and test personnel operating military equipment, virtual environment generation, use of real hardware devices, training program corresponding to army regulation, instructor facilities allowing simulation control, recording and displaying results and evaluation, support for action reviews (record and replay training exercises).

3. Conclusions about military modeling and simulation Modeling and simulation have made momentous strides in recent

years, and the military, medical science and other professions are on

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the verge of being able to use computing power to simulate reality for all kinds of applications.

Advanced M&S may integrate a mix of computer simulations, actual warfighting systems, and weapons system simulators. The entities may be distributed geographically and connected through a high-speed network. Warriors at all levels will use M&S to challenge their military skills at tactical, operational or strategic levels of war through the use of synthetic environments.

Modeling and Simulation (M&S) is increasingly widely used in today’s military forces worldwide. M&S can assist decision makers in choosing various strategic courses of action, whether or not to purchase particular weapons systems, implement programs and more. Growing costs of operational trials and limited budgets make extensive live tests of military systems impossible, hence simulation is one of the most important tools currently for military analyses, strategic planning, training and acquisition. It is imperative that models used are logically coherent and provide results that closely mirror real situations.

References

[1] NATO Modeling and Simulation Master Plan, 1998, page 4 [2] The Oxford English Dictionary [3] http://www.ist.ucf.edu/background.htm [4] Dr. J. Peter Kincaid, Origins and Overview of Modeling and Simulation [5] Ghiţă Bârsan, Modeling and Simulation – Introduction course, Editura

Academiei Forţelor Terestre, Sibiu, 2006 http://www.dami.army.pentagon.mil/offices/dami-isr/mands.asp http://www.msco.mil/ http://www.battle-command.army.mil/

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THE EFFECTS OF THE FAR AND NEAR ELECTROMAGNETIC FIELD ON THE HUMAN BODY

Prof.Eng.Gheorghe SAMOILESCU, PhD, Prof.Eng. Alexandru SOTIR, PhD, Assoc.Prof.Eng. Mircea CONSTANTINESCU, PhD,

Asst.Prof. Alina BARBU, PhD, Eng. Florenţiu DELIU

“Mircea cel Bătrân” Naval Academy, Constanta, Romania Abstract

The paper presents a simulation program regarding the effects of the electromagnetic field on the crew of a ship. The purpose of the paper is to put forward methods, measurements and procedures which can be used for the protection of personnel exposed to electromagnetic radiation.

1. Introduction Let there be a human body averagely built (h=1,75m,

rthorax=25cm), situated at a 10 m distance from the emission antenna, located inside some circular contours, made of copper, reference, testing spires, and of human material. We calculate the current densities induced in the spires by the magnetic field component Hϕ (radial component is neglected), of the far and near electromagnetic field, produced by monopol antennae (also called dipole non-symmetrical antennae) from the construction of a ship.

RE

The calculated values are compared to the admissible limit values provided by the European standard ICNIRP – GUIDE LINES FOR LIMITING EXPOSURE TO TIME-VARYING ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS (UP TO 300 GHz).

205


2. Mathematical Relations The components of electric and magnetic field produced by an

antenna of an emission-reception station onboard a ship, in a nearby area, or distant, respectively, are as follows (1)-(3), where we have introduced the void wave impedance, Z0, and the phase constant, 0β :

000

1cv;2vT2

vf2

v µελπππωβ =≅==== - where v – the phase speed of the

wave in free space; or:

0 v 0 0ωβ ω ε µ= = ⋅ , the phase constant.

0 0,ε µ - Permittivity, the permeability of void respectively, and of the free space;

Rj3

02

0

20

0R0ecos

)Rj(1

)Rj(1

4Il2ZE βθ

ββπβ −⋅⎥

⎦

⎤⎢⎣

⎡+

⋅⋅⋅= ; (1)

Rj3

02

00

20

00esin

)Rj(1

)Rj(1

Rj1

4IlZE β

θ θβββπ

β −⋅⎥⎦

⎤⎢⎣

⎡++

⋅⋅⋅= ; (2)

Rj2

00

20 0esin

)Rj(1

Rj1

4IlH β

ϕ θββπ

β −⋅⎥⎦

⎤⎢⎣

⎡+

⋅⋅= . (3)

An alternative way of writing down the equations is : R2j

320R eR2j1R4j

cosIlZE λπ

λπ

πθλ −

⋅⎥⎦⎤

⎢⎣⎡ +⋅= ; (4)

R2j2

320 eR2jR2j1R8j

sinIlZE λπ

θ λπ

λπ

πθλ −

⋅⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎠⎞

⎜⎝⎛++⋅= (5)

R2j

2 eR2j1R4

sinIlH λπ

ϕ λπ

πθ −

⋅⎥⎦⎤

⎢⎣⎡ += (6)

where R is the distance of point P from space in relation with the antenna which is used to calculate the intensity of the electric field, or the magnetic one, in relation with the field source.

The component Er is neglected in the calculus because it decreases significantly with the distance.

For the far field (radiation field) we take into consideration, for the above mentioned equations, only the components which decrease with the distance R; for the near field we take into consideration the components which decrease with the square of distance R.

The following values are known:

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A – the surface of the testing spire (m2); Imax – maximal intensity of the current through the antenna (A); R – the distance of the field source (m) in relation with the testing

spire; r – the beam of the testing spire (m); λ – the wave length of the emmitted radiation (λ=cT=c/f (m)) or: f – the frequency of the emmited radiation (Hz). By determining the intensity of the magnetic field H, and

similarly the magnetic induction B in point P, considered as being situated in the center of the testing spire, along the direction propagation of the antenna and assuming that the uniform field alloted on the spire surface (an acceptable supposition because the spire beam is shorter than the distance from the antenna to point P), we calculate the electromotor tension induced in the spire, and eventually, the density of the induced current.

3. The calculus of the minimal safety distance for the crew The calculus of the minimal safety distance for the personnel

exposed to a source of radiation ( in a far area), is made on the basis of the power desity of the radiation field emitted by an antenna, for frequencies 10MHz≤ , value which constitutes the standard.

The region of far field is that precise area in space which lays from the boundary of the Fresnel to the infinity.

Between the two areas, of far and near field, there cannnot be a strict discrimination. We should bear in mind the fact that the Fresnel area (near field) is that area in space, whose coordinates range between r=0 şi r ≤λ/2π, where λ is the wave length of the radiation.

The evaluation of power densities in the far field is relatively simple since both the benefit and the diagram of antenna radiation (or the width of the main radiation lobe, in degrees, at half the power) are independent from the distance from the antenna. Thus, the power density of the far field or radiation field, in the free space, on the axis of maximal power density is given by the formula (Friis):

Wd= 2)(4 dGP ot

π (7)

where: Wd – the power density admitted in a given observation point,

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[mW/cm2]; Go – the benefit of the far field of the antenna; Pt – the average power transmitted, [mW]; d – the distance from the antenna to the specific point, [cm]. The relation does not include the effects of soil/deck reflection

which, if case there be, may determine a value of the power density at least 4 times greater than the value in free space. For a vertical polarization, the elevation angle Ψ is limited as follows:

- la 100 MHz, Ψ 1 , ≤o

- la 5000 MHz, Ψ 5 , ≤o

As the frequency increases, the allowed elevation angle Ψ increases as well. By replacing W=10 mW/cm2 in the equation we determine d, the minimal safety distance for the personnel located in a far area:

d = 0

4tPGWdπ

(in cm) (8)

In the case of radars, if the value of the maximal power impulse is known, we can determine the average power, by multiplying the maximal power with the emission flow of the radar:

Pt (average)=Pt (maximal) x re (emission rate), where re= emission rate =

p

p

pl =lp x fr,

where lp= the impulse duration (in µs); pp= the impulse period (in µs); fr= the repetition frequency of the impulse.

In the Fresnel area, the antenna benefit and the radiation diagram are not constant, both parameters being functions of the effective distance form the antenna.

4.Conclusions The components of the near electromagnetic field are manifest at

distances r2λπ

≤ from the antenna.

We stress the fact that in the expressions which give the norm values in the tables below, 87

nE

fθ = , 0,73n

Hfϕ = and Jn=f/100, the

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Knowledge Based Organization 2008 International Conference frequencies is introduced in MHz for the electric and magnetic field and in Hz for the current density.

References

[1] Samoilescu,G., Electromagnetic Disturbances of the Naval Electroenergetic System, , MBAN Publishing House – Constanţa, 2000

[2] Sotir, A., Disturbing Electromagnetic Interferences. Theoretical Notions,Army Publishing House, Bucharest, 2005

[3] Sotir, A.,Moşoiu,T., Samoilescu,G., Theoretical Elements and Applications of electromagnetic compatibility onboard a maritime ship, MBAN Publishing House – Constanţa,1999

[4] Sotir, A.,Moşoiu,T., Samoilescu,G.,Constantinescu,M., Electromagnetic Compatibility.Theoretical Basis. Antidisturbing Screening, MBAN Publishing House – Constanţa,2001

[5] Ianoz, M., Compatibilité Electromagnetique, Coursebook, suport de curs, U.P. Lausanne, Switzerland, AGIR Conference, Bucharest, 1992

[6] Mocanu, C.I., The Theory of the Electromagnetic Field, Pedagogical and Didactic Publishing House, Bucharest, 1981

[7] Baran, I., Sources of Electromagnetic Disturbances, UPB Publishing House, Bucharest, 2001

[8] Costea, M., Methods and means of insuring elecromagnetic compatibility, AGIR Publishing House, Bucharest, 2006, pg.163-166.

[9] ***CEI 61000-2-5, Electromagnetic compatibility (EMC) Part2: Environment 6-Section 5: Clasification of electromagnetic environment. Basic EMC publication”

[10] Ignea, A., Measurements and tests in Electromagentic Compatibility Waldpress Publishing House, Timişoara, 1996

[11] Tamaş, R., Sotir, A., Constantinescu, M., Alexa, M., Electromagentic Compatibility of electric and electronic gear onboard ships, Muntenia Publishing House, Constanţa, 2004

[12] Gary, C., Les effects biologiques des champs magnétiques. Que peut dire l`électricien à ce sujet?, in Energetica Magazine, 41, nr.2-B, 1993

[13] Mataluno, G., Le radiazioni elettromagnetiche a bordo, in Rivista marittima, anno CXXI – Dicembre, Roma, 1988

[14] Nair, I., Biological Effects of Electric and Magnetic Fields: What do we know ?, manuscript, 15 Febr. 1993, Department of Engineering and Public Policy, Carnegie Mellon University (not presented at Stockholm Conference of EMC)

[15] Calotă, S.V., Deliu, N., Licurici, M., Ferastraeru, C., Contulescu, A., Study regarding professional exposure to non-ionized radiation of high frequency and their risk for health, Institute for Public Health, Bucharest, 1998

209

Knowledge Based Organization 2008 International Conference [16] King, W.P.R., Fields and Currents in the Organs of the Human Body when

exposed to Power Lines and VLF Transmitters, in IEEE Transactions on Biomedical Engineering, vol.45, nr.4, April 1998

[17] Ianoz, M.(Professor at Politehnics University of Lausanne, Switzerland), Biological and Health Effects of Electromagnetic Fields, conference, Politehnics University, Bucharest, Faculty of Energetics, TICEM Research Center, march 2003

[18]*** Human exposure to electric and magnetic fields of industrial, Project of Romanian Standard: SR EN 50166-1, IRS, Bucharest (in conformity with the standard EN 50166-1/1994)

[19]*** TheExposure of the Human Being to Electromagnetic Fields form the frequency range 10 kHz-300 GHz, Project of Romanian Standard: SR EN 50166-1, IRS, Bucharest (in conformity with the standard EN 50166-1/1994)

[20] Zamfirescu, M., Sajin, I., Rusu, I., Sajin, M., Kovacs, E., Biological Effects of electromagnetic radiations of radiofrequency and microwave, Medicală Press, Bucharest, 2000

[21] Miclăuş, S., Bechet, P., Demeter, Ş., Determining the Radiofrequency Power Distribution Absorbed into a Spherical Biological Model, Scientific Bulletin of the Land Forces, nr. 1/2004.

[22] Miclăuş, Simona., Bechet, P., Demeter, Ş., Determining the Radiofrequency Power Distribution Absorbed into a Spherical Biological Model, Scientific Bulletin no. 1/2004, “Nicolae Balcescu” Land Forces Academy, Sibiu

The paper was achieved within the Research Project, nr.6115 ” Electromagnetic

Ecology, characterization of sources, diagnosing effects, prevention and their repraisal”

210


THE CALCULUS OF THE INDUCED CURRENT DENSITY IN A REFERENCE SPIRE FOR THE

PROTECTION OF ONBOARD PERSONNEL EXPOSED TO AN ELECTROMAGNETIC FIELD

Prof.Eng.Gheorghe SAMOILESCU, PhD, Prof. Eng. Alexandru SOTIR, PhD,

Assoc.Prof.Eng. Mircea CONSTANTINESCU, PhD, Asst.Prof. Alina BARBU, PhD, Eng. Florenţiu DELIU

“Mircea cel Bătrân” Naval Academy, Constanta, Romania

Abstract

The paper presents, starting from the particular equations of the electromagnetic field theory, the modality of calculation for the density of induced current. The obtained results allow the suggestion of: analysis methods of the presence of electromagnetic energy in a given area; the protection measures which include screens, barriers; the orientation of antennae far form the areas in which the onboard personnel deploys their activity; protection measures for the personnel working in a high risk area.

1. Introduction In the program the calculation has been made for a near field, as

well as for a far field. The simulation was performed for various values of the peak current intensity in the antenna, of the testing spire, of the spire beams of the human material which simulate various parts of the body, and of the distance between the source and the objective also.

For the simulation we have conceived a calculation and simulation program PCS-3.1, rendered in parameteres, intitled Final Effects, achieved in Maple mathematical environment.

211


2. Mathematical relations We start form Maxwell’s second equation :

tH

tBErot

∂∂

−=∂∂

−= µr , (1)

Considering that the environment (free space) is homogenous and

liniar form an electromagnetic point of view, with the constituent parameters respectively µ,ε,σ – which are always constant.

In relation (1), tB∂∂ represents the induction variation, of the

magnetic field intensity which is part of the wave radiated by the antenna.

Applying Stokes theorem: ∫ ∫∫Γ Γ

=S

AdErotsdErrrr , (2)

We obtain the integral equation:

S

BEds dAt

ΓΓ

∂= −

∂∫ ∫∫ . (3)

In relation (3), dA represents the surface area element of the open

surface S, comprised in the testing spire. In a first phase, the human body shall be considered as being

framed by a circular contour of a beam r=25cm, as shown before, the contour being materialized by a copper spire; the latter being considered standard or reference measurement.

In the next phase, various organs/parts of the body shall be simulated, in their turn, by fictitious spires of different beams, having, this time, conductivities equal to the average conductivities of these organs ( taken form the specialty literature). The purpose of these calculations is to allow comparisons, with a common refernce basis – the Co spire, between the calculated values and the norms admitted by the standards.

Considering the curve Γ of a circular shape and neglecting the sign, the integral equation (3) becomes:

dtdBrrE 22 ππ = , (4)

212


where r is the testing spire, supported by the Γ curve. It results thereby:

dtdBrE

2= . (5)

The density of current induced in the spire, according to the local

form of the electric conduction law for passive circuits, shall be: r dBJ E

2 dtσσ= = , (6)

where σ is the conductivity of the Co spire material or the average conductivity of the human material ( cuσ =58.106 S/m,

0,6 /mc S mσ = ). In the case of a synusoidal radiation field ( max sin( )B B tω= ), we

obtain the expressions: max ( / )

2rE B V mω= , (7)

respectively 2

max ( / )2rJ B A mσ ω= . (8)

The value of B is obtained by the relations: 0

0 00 0 0

1/ ; ; / ;B H E c S E H Z E H cϕ ϕ θ θ ϕ θ ϕµµε ε µ

= ⋅ = = ⋅ = = =⋅

, (9)

max max 0 maxB B Hϕ ϕµ= = ⋅

70 09

1 / ; 4 10 /4 9 10

F m Hε µ ππ

−= = ⋅⋅ ⋅

m

where : c – the light velocity in void, m/s; S( or Wd) – the power density radiated by the antenna, W/mp;

0, 0ε µ - permitivity, respectively the permeability of the void/free space, which are known values.

Obviously, the values which are obtained for t.e.m. and the density of the current obtained in the spire are minimal in the case of a synusoidal signal, greater values being expected whether the field source emmits impulses (for example in the case of radar antennae), when the frequency range is much wider (due to the large slope of its front)

213


If the analysed point is at a d distance, perpendicular to the emmission direction of an antenna (directional), the relation (7) becomes:

( )RE Bcos V /

2= ω α m (10)

where:

2 2

RcosR d

α =+

(11)

3. Comparing calculated data to the norm values The values obtained by simulation or measurement for the current

density, J, are used as follows: - up to the frequency of 10 MHz we compare the values of current

densities admitted by the standards regarding the exposure of the human factor in the frequency range 10kHz-10MHz, that can be calculated with the formula: Jn=f/100mA/m2 , where f is the frequency in Hz ( in conformity with the european standard ICNIRP – GUIDE LINES FOR LIMITING EXPOSURE TO TIME-VARIING ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS (UP TO 300 GHz).

- for frequencies of 10 MHz we calculate The Specific Absorption Rate (SAR) with the formula :

2

/JSAR W kgρ σ

=⋅

, (12)

where: - J is the value of the current densityeste induced in the testing

spire, respectively in the tissue/organ/part of the body of interest, in A/m2;

- ρ is the density of the testing spire respectively in the tissue/organ/part of the body of interest, in kg/m3;

- σ is the conductivity of the testing spire respectively in the tissue/organ/part of the body of interest,, in S/m;

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4. Conclusions resulting from the theoretical simulation As a result of simulating the effects of the electromagnetic field

with the help of a theoretical model, implemented through the calculation and simulation program PCS-3.1, on a copper spire, respectively made of human material, in circumstances of far and near field, for two frequencies, onboard a maritime minesweeper ship, we have obtained the data in the tables below.

In the last two rows from the tables we present the admitted boundary values, in conformity with the European standard ICNIRP – GUIDE LINES FOR LIMITING EXPOSURE TO TIME-VARIING ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS (UP TO 300 GHz).

References

[1] Samoilescu, G., Electromagnetic Disturbances of the Naval Electroenergetic System, MBNA Publishing House, Constanta, 2000

[2] Sotir, A., Disturbing Electromagnetic Interferences. Theoretical Basis, Military Publishing House, Bucharest, 2005

[3] Sotir, A., Moşoiu,T., Samoilescu,G., Theoretical Elements and Applications of the Electromagnetic Compatibility Onboard a Maritime Ship, MBNA Publishing House, Constanta,1999

[4] Sotir, A., Moşoiu,T., Samoilescu, G., Constantinescu,M., Electromagnetic Compatibility. Theoretical Basis. Antidisturbing Screening, MBAN Publishing House – Constanţa, 2001

[6] Timotin, A., Hortopan, V., Ifrim, A., Preda, M., Lessons on Basics of Electrotechnics, Didactic and Pedagogic Publishing House, 1970

[7] ***CEI 61000-2-5, Electromagnetic compatibility (EMC) Part2: Environment 6-Section 5: Clasification of electromagnetic environment. Basic EMC publication”

[8]*** Research on the biologic Effects of the magnetic and electric field, in R.G.E., special issue, July 1976, Colloqium CEM, Limoges, France, 1987

[9] Tamaş, R., Sotir, A., Constantinescu, M., Alexa, M., Electromagentic Compatibility of electric and electronic gear onboard ships, Muntenia Publishing House, Constanţa, 2004

[10] Mataluno, G., Le radiazioni elettromagnetiche a bordo, in Rivista marittima, anno CXXI – Dicembre, Roma, 1988

[11] Calotă, S.V., Deliu, N., Licurici, M., Ferastraeru, C., Contulescu, A., Study regarding professional exposure to non-ionized radiation of high frequency and their risk for health, Institute for Public Health, Bucharest, 1998

215

Knowledge Based Organization 2008 International Conference [12] King, W.P.R., Fields and Currents in the Organs of the Human Body when

exposed to Power Lines and VLF Transmitters, in IEEE Transactions on Biomedical Engineering, vol.45, nr.4, April 1998

[13]*** TheExposure of the Human Being to Electromagnetic Fields form the frequency range 10 kHz-300 GHz, Project of Romanian Standard: SR EN 50166-1, IRS, Bucharest (in conformity with the standard EN 50166-1/1994)

[20] Zamfirescu, M., Sajin, I., Rusu, I., Sajin, M., Kovacs, E., Biological Effects of electromagnetic radiations of radiofrequency and microwave, Medicală Press, Bucharest, 2000

[21] Miclăuş, S., Bechet, P., Demeter, Ş., Determining the Radiofrequency Power Distribution Absorbed into a Spherical Biological Model, Scientific Bulletin of the Land Forces, nr. 1/2004. The paper was achieved within the Research Project, nr.6115 ”

Electromagnetic Ecology, characterization of sources, diagnosing effects, prevention and their repraisal”

216


INTENTIONAL ELECTROMAGNETIC INTERFERENCE AND ELECTROMAGNETIC

TERRORISM: A REVIEW

Assoc.Prof. Miclaus Simona, PhD

“Nicolae Balcescu” Land Forces Academy, Sibiu, Romania, [email protected]

Abstract Intentional electromagnetic interference, sometimes denominating an

electromagnetic terrorist act, represents one of the modern threats to electronic technologies in a direct manner and to military and civil society by indirect consequences. Present paper reviews in a synthetic approach some essential aspects regarding types of intentional electromagnetic environments, their physical characteristics and sources, some of the effects following an attack and possibilities to better define protective measures in the future.

Keywords: electromagnetic threat, vulnerability, high power electromagnetics, electromagnetic pulse

1. Introduction Intentional Electromagnetic Interference (IEMI) is one of the

most serious 21st century’s threats, since it concerns any system containing electronic components. Presently, terrorists and hackers are able to build electromagnetic interference (EMI) sources that can produce high level transient radiated and conducted disturbances [1]. Taking into account the society’s dependence on computers is enough to imagine the degree of susceptibility. Present paper reviews the overall threat and the possibilities to deal with the problem of IEMI.

Specific characteristics of IEMI threat are [1]-[4]: a) it can be undertaken covertly, anonymously and at some distance away from

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Knowledge Based Organization 2008 International Conference physical barriers; b) it can cover a great number of targets and leave minor traces or none at all; c) those involved can range from careless people to pranksters, vandals, criminals and terrorists, whether state-sponsored or otherwise.

2. Classification of intentional electromagnetic interference

environments One can classify potential IEMI threat environments into four

categories, based on frequency coverage [4]. Sufficiently intense electromagnetic (EM) signals in the frequency range 200 MHz-5 GHz can cause upset or damage in electronic systems. The disturbing EM environment could be described by attributes of the incident field applied to a system as: 1) a single pulse with many cycles of a single frequency (an intense narrowband signal that may have some frequency agility); 2) a burst containing many pulses, with each pulse containing many cycles of a single frequency; 3) an ultra-wideband pulse (UWB) (spectral content from hundreds of MHz to several GHz); 4) a burst of many ultra-wideband transient pulses. All of these may be radiated or conducted as well.

Yet another way of categorizing IEMI environments is based on the level of sophistication of the underlying technologies involved in producing the EM environment, i.e. by the nature of the source producing the environment [4]. Such sources could range from unsophisticated EM noise sources - like a spark gap or a Jacob’s ladder discharge, to highly sophisticated directed EM weapons [5].

A third way of classifying IEMI is by the effects that it can have on a targeted system [4]. Such effects can range from momentary loss of function of a system to catastrophic failure of the system due to component damage.

3. Time-frequency and amplitude characteristics of

electromagnetic environments The most common EM environment that affects electronic

systems is naturally occurring lightning. In regions of high lightning activity, surge protection devices and lightning rods are used. In addition, many military assets and a few civilian systems (e.g. nuclear power plants, communications facilities, etc.) in some nations are

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Knowledge Based Organization 2008 International Conference protected against the damaging effects of the High-Altitude Electromagnetic Pulse (HEMP). The emerging high power electromagnetic (HPEM) environments (when the peak electric field is 100 V/m or higher), which could be used intentionally to disrupt a system, have the characteristics described in figure 1. Here, the narrowband signals include high power microwave (HPM) and the wideband signals include ultra-wide-band signals (UWB).

In the category of HPEM are included: 1) lightning electromagnetic pulse; 2) radar fields; 3) fields produced near an electrostatic discharge arc; 4) electromagnetic pulse (EMP) produced by a nuclear detonation at any altitude; 5) electromagnetic fields that can produce IEMI, including narrowband threats such as high-power microwaves (HPM) and wideband threats such as ultrawideband (UWB) fields.

Figure 1: Comparison of the spectra of several types of EM environment [4]

For comparison, in figure 2, the normalized amplitude of three

different EMP source signals (including natural lightning) are represented, in function of time (rise-time).

Characterization based on spectral attributes of the EM signals separate four categories, based on the frequency content of their spectral densities as: narrowband, moderate band, ultra-moderate band and hyperband.

Another approach for characterizing the IEMI produced by a HPEM source is to examine the E-field strength at a specified distance from the source, the frequency agility of the source, the duration and

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Knowledge Based Organization 2008 International Conference repetition rates for pulsed sources, and the burst lengths. Therefore, one can estimate the electric field levels as a function of frequency and range for two chosen power levels, as in table 1 [4].

Figure 2: Typical electromagnetic pulses shapes

(amplitude temporal evolution) [5] Table 1 Range of radiated electric field at four different frequencies and for two

different power levels Frequency Range Antenna aperture of

10m2 and output power of 2kW

Antenna aperture of 10m2 and output power of 20MW

500MHz 300m-1km 15.23V/m-4.57V/m 1.52kV/m-457V/m 1GHz 300m-1km 30.43V/m-9.13V/m 3.04kV/m-913V/m 2GHz 300m-1km 60.90V/m-

18.27V/m 6.09kV/m-1.83kV/m

3GHz 300m-1km 91.33V/m-27.40V/m

9.13kV/m-2.74kV/m

Regarding IEMI sources, they can be built as: a. hyperband systems - TEM horns and reflectors fed by TEM

transmission lines have been established as efficient radiators or arrays of such sources and antennas, which enable a peak signal of 7.5 kV/m at a distance of 1 km [6], [7];

b. narrowband (hypoband) systems - referred to as a “Phaser” (a device that produces Pulsed High-Amplitude Sinusoidal

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Knowledge Based Organization 2008 International Conference Electromagnetic Radiation), which can produce up to 1.8GW peak power; possibilities to get an E-field of 2.3 kV/m at 3 km and ~ 700 V/m at 10 km exist; such narrow band generator systems could also be truck-mounted and arrive in close proximity to civilian electronics systems and facilities, producing much higher field levels; several narrowband generator systems in the frequency range of 0.7 GHz to 3 GHz exist [4], [6], [7];

c. moderate band systems - for example a "dispatcher" (Damped Intensive Sinusoidal Pulsed Antenna), a low–impedance quarter wave transmission line oscillator feeding a high-impedance antenna or a low-impedance quarter wave transmission line feeding a TEM fed reflector are in this category [6]-[8].

4. Electromagnetic interference and intentional interference

effects The existence of IEMI and associated phenomena are partially

commonly-known in the present [1]: commercial aircrafts regulate use of all radios, mobile phones, computers, CD players, etc., by turning them off before take-off and landing. Similarly, hospitals restrict the use of mobile phones, which can affect patient monitoring and other medical equipment.

Unintentional EMI implied a series of incidents, starting from 1967, and bellow is a short list [3]: a. Effect: Munitions on landing aircraft released due to irradiation by ship radar; 134 sailors killed. Cause: degraded termination of cable shield, U.S.S. Forrestal (aircraft carrier), 1967; b. Effect: Warning system against missile attacks was shut down since it interfered with communication systems on the ship, H.M.S. Sheffield, 1982; c. Effect: 5 crashes, due to radio transmitters, Blackhawk, 1981 – 1987; d. Effect: Crash, 3 km from VOA radio transmitter, Tornado, 1984; e. Effect: Crash, flew too close to VOA radio transmitter, F16; f. Effect: Crash, blast of radom due to lightning, AJ37 Viggen, 1978. g. Effect: Release of canopy due to lightning, AJ37 Viggen, 1978.

Historically, the first possible connection to IEMI involvement dates back in July 1996 - near Long Island, New York, when the crash of Boeing 747 - TWA Flight 800 took place.

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In 2004 a Swedish study has revealed that HPM radiation applied intentional, can stop cars at a distance of 900 meters and cause serious damage at a distance of 30 meters.

HPEM emitters could be installed in vans along highways in order to stop car traffic and to cause malfunctioning of traffic signals. Similarly, if the vans are parked outside the perimeter of a large airport, they can disrupt the proper functioning of systems for take-off and landing. If such vans are left outside computer buildings, they can cause malfunctioning of computer systems. If the computer centres control critical industrial systems, the results could be very serious, in terms of injury and loss of life [1].

Another example is high density Metal Oxide Semiconductor (MOS) computer chips, which rely on extremely narrow internal “wires” to connect densely packed components. They are permanently damaged when exposed to more than tens of volts or a few tenths of an ampere.

While it is extremely difficult to calculate the minimum

field strength required to induce signals of this magnitude for all cases and systems, testing has shown that pulses of 10 kV/m are sufficient to cause widespread damage.

Ten kV/m could induce electrical

charges a billion times more powerful than systems were designed for, not just burning them out, but in some cases melting critical components.

As a result, unhardened computers used in data

processing systems, communications systems, displays, industrial controls, military systems (including signal processors and electronic engine and flight control systems), telecommunications equipment, radar, satellites, UHF, VHF, HF, and television equipment are all vulnerable to the EMP at and above this level.

In 2005 a military report approved for public release, “Electromagnetic Pulse Threats to U.S. Expeditionary Operations in 2010” [9] was published, in order to underline the potential destructive effects of EMP weapons and the potential devastation such a weapon could wreak on civilian infrastructures. The report stresses that the military and civilian leaders seem to be ignoring the threat, perhaps to avoid the costs involved in addressing it, while pushing for further development of a network-centric force that will be increasingly vulnerable if not protected.

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5. Present recommendations The electromagnetic compatibility (EMC) community should be

aware about the following: a. the major potential impact of such major disruptions of these important technological functions; b. the need for additional research into IEMI in order to understand the large variation of susceptibility levels and system weaknesses and to establish appropriate levels for dealing with such treats; c. the need for the development and recognition of techniques for appropriate protection against IEMI and of methods that can be used to protect the public from the damage to the infrastructure that could occur as a result of such intentional EMI; d. the need to develop special EM monitors to determine when an attack is underway; e. the necessity for high-quality testing and assessment of system performance when exposed to these special electromagnetic environments; f. the need for the EMC community to provide usable data to support the formulation of standards of protection.

6. Conclusion Intentional electromagnetic interference (IEMI), or as it is

sometimes known, "EM Terrorism", is a new area of concern for military, public and commercial interests. At the Union of Radio Science (URSI) XXVIth General Assembly in Toronto, August 1999, a resolution was adopted on “Criminal Activities using Electromagnetic Tools”. According to this, intentional EMI is defined as the "Intentional malicious generation of electromagnetic energy introducing noise or signals into electric and electronic systems, thus disrupting, confusing or damaging these systems for terrorist or criminal purposes." This threat has been recognized by several international organizations, the International Electrotechnical Commission (IEC) and the URSI, and continuous work is underway to deal with the threat. For example, inside IEC, the Technical Committee 77 has a subcommittee - SC 77C (where Romania is also represented), which develops standards and reports - including seventeen active projects and/or publications, covering HEMP and IEMI issues [2].

The effects of intentional EMI on the infrastructure and important functions in society, are mainly affecting: transportation,

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Knowledge Based Organization 2008 International Conference communication, security and medicine. Military forces depend on electronic systems and information dominance to produce overwhelming combat power. Defense leaders are calling for development of a network-centric force to rapidly deploy and conduct decisive operations in the future security environment. Unfortunately, the information revolution embraced by the military has a dark side - it introduces a potentially catastrophic vulnerability. Electronics, the foundation of the network-centric force, are extremely vulnerable to a rapidly proliferating class of arms - electromagnetic pulse (EMP) weapons.

References

[1] Radaski A.W., Progress in the Field of Intentional Electromagnetic Interference, since New Delhi General Assembly in 2005, Proceedings of URSI General Assembly in 2008, pp.31-40, 2008.

[2] Wik M.W., Radaski A.W., Intentional Electromagnetic Interference- Background and Status of Standardization Work in the IEC, Proceedings of URSI General Assembly in 2002, pp.56-63, 2002.

[3] Backstrom M., Is Intentional EMI a Threat Against the Civilian Society, presentation at EL-QA Meeting, Desitek A/S, Sonderso, Denmark, 20 Nov. 2006.

[4] Giri D.V., Tesche F.M., Clasiffication of Intentional Electromagnetic Environments, IEEE EMC Trans., Spec. issue, pp. 43-50, 2004.

[5] Kopp C., The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction, http://www.globalsecurity.org/military/library/report/1996/ apjemp.htm

[6] Sabath, F. et. al., Survey of Worldwide High-Power Microwave Narrow Band Test Facilities, IEEE EMC Trans., Spec. issue, pp. 83-91, 2004.

[7] Prather, W. D., et. al., Worldwide Survey of High-Power Wideband Capabilities, IEEE EMC Trans., Spec. issue, pp. 101-109, 2004.

[8] Carter R.J., Grothaus M.G., Lucas J.H., Intentional Electromagnetic Interference Test of a Facility Security Entry System, Proceedings of URSI General Assembly in 2002, pp. 106-112, 2002.

[9] Miller C.R., Electromagnetic Pulse Threats to U.S. Expeditionary Operations in 2010, Res. Report AU/SCHOOL/40-2712/2004-05, Air Command and Staff College, Air University, Maxwell Air Force Base, Alabama, USA, 2005.

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http://www.globalsecurity.org/military/


A NEW APPROACH TO MULTI-CRITERIA DECISION MAKING WITH HIERARCHICAL ALTERNATIVES

Assoc.Prof. Ion Coltescu, PhD, Asst.Prof. Paul Vasiliu, PhD

Naval Academy “Mircea cel Batran”, Constanta, i @ yahoo.comcoltescu

Abstract

This paper focuses on the structure of alternatives and proposes a new problem structuring approach based on hierarchical alternatives, an appropriate solution methodology based on fuzzy outranking, and a framework for the design of the decision support system suitable for multi-criteria decision making problems (MCDM).

Keywords: multi-criteria, decision making, fuzzy.

1. Introduction This paper presents a new approach to group multi-criteria

decision making problems that increases the effectiveness and facilitates the implementation of group decision support systems by means of a hierarchical structure for alternatives. The mathematical model of decision problems with such structures and the solution procedure are presented in section 2.

2. Mathematical Model of Hierarchical Alternatives In this section, the mathematical modeling of MCDM with

hierarchical alternatives is illustrated. Consider a multi-criteria decision making problem [1], [2], with criteria ,

levels of alternatives and alternatives in each level. q , , ,1 2C C CqK L

ml

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mailto:icoltescu @ yahoo.com


If lAi , and 1, ,l L= K 1, ,i lm= K is an alternative on level , we

denote then the set of all alternatives on level

l

1l + derived from lAi is:

(1) 1 1 1, , ,1 2 1l l lA A Aimi i l

⎧ ⎫⎪ ⎪⎨ ⎬⎪ ⎪⎩ ⎭

+ + ++

K

In the general form, alternatives of adjacent levels can have a fuzzy relationship. That is, alternatives of each level can belong to alternatives of the upper level by a degree of membership from the range of . The crisp relation is a special case of the fuzzy relation in which the degrees of membership are either 0 or 1. Thus:

0,1⎡⎣ ⎤⎦

1 2 2 2, , , , , ,1 1 2 1 2 2 1 2 121 1 2 1 12A A A K AmA A A A Am

µ µ µ⎧ ⎫⎛ ⎞⎛ ⎞ ⎛ ⎞⎪ ⎪⎜ ⎟⎪ ⎪⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎨ ⎬⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎪ ⎪⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠⎪ ⎪⎝ ⎠⎩ ⎭

=A

M (2)

1 2 2 2, , , , , ,1 2 1 2 2 1 2 11 21 21 1 2A A A K Am mA A A A A Am m m

µ µ µ⎧ ⎫⎛ ⎞ ⎛ ⎞ ⎛⎪ ⎪⎜ ⎟ ⎜ ⎟ ⎜⎪ ⎪⎜ ⎟ ⎜ ⎟ ⎜⎨ ⎬⎜ ⎟ ⎜ ⎟ ⎜⎪ ⎪⎜ ⎟ ⎜ ⎟ ⎜⎪ ⎪⎝ ⎠ ⎝ ⎠ ⎝⎩ ⎭

=

1m

⎞⎟⎟⎟⎟⎠

l

In general, if 1lA Ai j

µ + is the membership degree of alternative

1lAi+ to the upper level alternative lAj then for all and 1, , 1l L= K −

1, ,j ml= K 1, 1, ,1 1l lA A i mj i l l lA Ai j

µ⎧ ⎫⎛ ⎞⎪ ⎪⎜ ⎟⎪ ⎪⎨ ⎬⎜ ⎟⎪ ⎪⎜ ⎟⎪ ⎪⎝ ⎠⎩ ⎭

+= =+ +K (3)

In dealing with multi-criteria, although the proposed method may work well with both aggregation and outranking approaches, in this paper, we adopt an outranking approach. For this purpose, an outranking relation matrix is constructed for each criterion. Here, we consider two distinct groups of criteria. In the first group all alternatives can be compared with respect to these criteria. In the second group of criteria the decision maker needs to refer to

226

Knowledge Based Organization 2008 International Conference alternatives of the next level(s). For any criterion that belongs to the first group, the following preference relation could be obtained through comparison of alternatives in level

Cp

1l = : 1 11 1

A K Am

1 1 1 11 1 1 11 11 0

11 1 1 1 1

11 1

C Cp pr K rA A A AA m

R M M MCpC Cp pAm r K rA A A Am m

⎛ ⎞⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎝ ⎠

=

1m

⎤⎦

(4)

where for the case of fuzzy, and for the

case of crisp relations. In the above matrix

0,11 1CprA Ai j

⎡⎣∈ 0,11 1CprA Ai j

∈

1 1CprA Ai j

is the partial

evaluation of alternatives 1Ai and 1Aj with respect to criterion . The

magnitude of this partial evaluation indicates the degree of truth of the statement “

Cp

1Ai is at least as good as 1Aj ”. Similarly, for any criterion

from second group criteria, the preference relation of alternatives in the first level is: Cq

1 11 1

A K Am

1 1 1 11 1 1 11 11 0

11 1 1 1 1

11 1

C Cq qr K rA A A AA m

R M M MCqC Cq qAm r K rA A A Am m

⎛ ⎞⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎝ ⎠

=

1m

(5)

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However, since the criterion belongs to second group criteria, some of the values in the above matrix may not be directly obtained from the first level. Therefore, the decision maker needs to refer to the next level :

Cqr

2l =

2 21 2

A K Am

2 2 2 22 1 1 11 22 0

22 2 2 2 2

12 2

C Cq qr K rA A A AA m

R M M MCqC Cq qAm r K rA A A Am m

⎛ ⎞⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜⎜⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟⎝ ⎠

=

2m

⎟⎟ (6)

For simplicity, assume that level 2l = is a suitable level for judgment about criterion . That is, all elements of are

available. Therefore, can be used in finding a ranking for

alternatives of the second level. In this ranking, let

Cq 2RCq2RCq

2CqSAi

, ,

denote the score of alternative

1, , 2i m= K

Ai of level 2 with respect to criterion

such that , and Cq 0,12CqSAi

⎡⎣∈ ⎤⎦ 1CqAj

ρ , 1, , 1j m= K denote the average

rating of alternative Aj of level 1. Thus, the following equation can be

written:

22 1 21

1 2

m CqSA A AC i i j iqmAj

µ

ρ∑=

= , 1, , 1j m= K (7)

The above rating indicates the aggregated contributions of the second level alternatives in improving the preference of alternative Aj

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in the first level with respect to criterion . Once Cq 1CqAj

ρ values are

calculated, then 1 1CqrA Ai j

, 1, , 1i m= K 1, , 1j m= K that shows the

preference of alternative Ai of the first level over alternative Aj of the

same level with respect to criterion C could obtained as follows: q

,01 1 1 1C C Cqq qr Not MaxA A A Ai j j i

ρ ρ⎡ ⎤⎧ ⎫⎛ ⎞⎢ ⎥⎪ ⎪⎜ ⎟⎢ ⎥⎨ ⎬⎜ ⎟⎢ ⎥⎪ ⎪⎜ ⎟⎢ ⎝ ⎠⎩ ⎭⎥⎣ ⎦

= − 1, , 1, i m= K m

1q

(8) 1, , 1j = K

where is the logical complement of the argument . Based on the above equation result:

Not a⎡ ⎤⎣ ⎦ a

if 1C CqA Ai j

ρ ρ= , then 11 1CqrA Ai j

= and 11 1CqrA Aj i

=

if 1C Cq

1q

A Ai jρ ρ> , then 111 =qC

jAiAr and (9)

⎥⎥⎥

⎦

⎤

⎢⎢⎢

⎣

⎡

−= qC

jAqC

iANotqC

iAjAr 1111 ρρ

if qC

jAqC

iA 11 ρρ < , then 1 1 1 1C Cq qr Not

CqA A Ai j j i

ρ ρA

⎡ ⎤⎢ ⎥⎢ ⎥⎢ ⎥⎣ ⎦

= − and 11 1CqrA Aj i

= .

Thus, all elements of which corresponds to the level can

be obtained from the elements of that corresponds to the level

.

1RCq1l =

2RCq2l =In a case where the decision maker needs to refer to the third level

of alternatives in order to judge criterion first is obtained

from , and then is obtained from using the above

equations. Therefore, the preference relations for all second group

Cq 2RCq3RCq

1RCq2RCq

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Qcriteria , will become available. Finally, to choose the best alternative or to rank alternatives an outranking approach may be taken. The following is a step-by-step algorithm that shows the solution approach to a multi-criteria decision making problem with hierarchical alternatives.

Cq 1, ,q = K

Step 1. Determine all criteria C , q 1, ,q Q= K .

Step 2. Identify alternatives and organize them in a hierarchy. Step 3. Determine 1l lA Ai j

µ + , the degree of membership of

alternative 1lAi+ to the upper level alternative lAj .

Step 4. Determine the outranking preference relations for all

first group criteria.

2RCp

Step 5. For all second group criteria, repeat the following steps: Step 5.1. Move to the first level for which the outranking

preference relations can be constructed. Set k

2RCq1l k= − .

Step 5.2. Find 1CqS lAi+ , 1, , 1i ml= +K , the score of alternative Ai of

level with respect to criterion . 1l + Cq

Step 5.3. Using the following equation, calculate Cq

lAjρ ,

, the average rating of alternative 1, ,j l= K m Aj of level l ,

11 11

1

m Cl qSl l lA A AiC i j iql mA lj

µ

ρ

+∑ + +=

=+

, 1, ,j ml= K (10)

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Sep 5.4. Using the following equation, calculate Cqr l lA Ai j

,

, , the prference of alternative 1, ,i ml= K 1, ,j l= K m Ai of level over

alternative

l

Aj of the same level with respect to criterion C . q

,0C C Cq ⎪⎪

⎬q qr Not Maxl l l lA A A Ai j j i

ρ ρ⎡ ⎤⎧ ⎫⎛ ⎞⎢ ⎥⎪⎜ ⎟⎪⎢ ⎥⎨⎜ ⎟⎢ ⎥⎪ ⎪⎜ ⎟⎢ ⎥⎪ ⎪⎝ ⎠⎩ ⎭⎣ ⎦

= − 1, , l, i m and 1, ,j ml= K (11) = K

Step 5.5. If 1l ≠ , then set 1l l= − and go to Step 5.2; otherwise, continue. Step 5.6. If all second group criteria have been tested, continue to

the next step; otherwise, go to Step 5.1. Step 6. Perform the final ranking of alternatives in the first level

using an outranking approach.

References [1] Corner, J., Buchanan, J. and Henig, M., Dynamic Decision Problem

Structuring, Journal of Multi-Criteria Decision Analysis, 129-141, 2001. [2] Keefer, D. L., Kirkwood, C. W. and Corner, J. L., Decision Analysis

Applications in the Operations Research Literature, Department of Supply Chain Management, Arizona State University, Tempe, Arizona, 2002.

[3] Nutt, P. C., Surprising but true: Half of the decisions in organizations fail, Academy of Management Executive, 75-90, 1999.

[4] Perry, W. and Moffat, J., Developing models of decision making, Journal of Operational Research Society, 457–470, 1977.

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ENERGETIC CERTIFICATE FOR BUILDINGS OF THE MINISTRY OF DEFENSE – A NECESSITY

Eng. Horia Popescu, Eng. Mariana Soare

Properties and Infrastructure Direction, Bucharest, [email protected]

Abstract The Ministry of Defense administers aproximatly 10.000 buildings, divided

in 6 categories, based on the thermic (energetic) regime, starting with the military hospitals, military nurseries, infirmaries and finishing with the harbours for sheltering the machines, heated garages or fire brigades. By using a double conversion (photon in the infrared field – electron-photn in the visible field), it can be noticed the thermal contract of the building, that is to say the diference of intensity of the thermal radiations sent out by the building face to the surrounding environment. In the civil field, for the thermo vision systems, there were found more and more uses, for example the dwellings loss of heating determination.

This paper shows how infrared thermography can identify the moisture soures from a building defining the causes and the origins or how it can be usefull for saving energy. The thermal cameras tests establish that various thermal resitances of bulding materials of the walls responsible for the conductiv losses of heat from arround the windows and doors combined with the conductive losses associated to plaster fissures, bricks, concrete – combined – reveal thermal anomalies, studied in the paper.

1. Introduction The component parts of a building send out in infrared – this heat

in not visible to human eye (fig. 1). The thermal camera determines these radiations in infrared and assigns to each temperature a specific color in an image, called thermograme. The energetic audit specialists can determine, based on the analysis of these images, what parts of the building are conductive or convective for the heat lost/gained. When

232

Knowledge Based Organization 2008 International Conference the difference of temperature between inside and outside is minimum 18 degrees Fahrenheit, the associated colors from the thermograme depend on the age and the type of the building.

All the buildings have leaks of airmaking like this impossible to mentain an interior constant differential presure, When we measure along the casing of the building a positive presure will be measured on the exposed to wind facade. The unexposed to wind facade of the building will present a negative presure. This condition must be searched at all the levels of the building and retain the little transverse variations. In the inspection proces time we will measure the static interior pressure along the casing of the building, in normal HVAC (heating, ventilating and air conditioning) operation conditions. While all the buildings opperate with positive pressure outside, the negative one from the unexposed to wind side must not surprise, being able to draw some conclusions regarding the age and the type of the construction.

The lost heat along the intrados of the building’s section; Where it is accessible, in the inspection time, the test on the wall presents minimum levels of moisture. While in the visible sectors the presence of water can be obvious determined, in the soffits, intradoses and seepage, we can not know the moisture level.

A considerable loss of heat, both through conduction and convection through windows and doors; in this case, these must be replaced. After the replace it will be able to see if the termal pathern is improved.

A great part of the interior corners are heated by the neighboring walls. Future moisture tests in these corners will not produce significant hydrogene increase. Real barriers in the walls can be done by using special mortar. Redaubing must have as a scope also the elimination, as much as possible, of the infiltrated water.

Figure 1. Thermal image of the building Figure 2. Thermo vision camera

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2. Infrared quality assurance of masonry during construction The inspector must have an energetic audit certificate, level 1 –

thermograph and he must be familiarized with the demands of the execution technical project of the building. While the inspection, the specialist will record data concerning the location, environment conditions, presence of obstacles, distance to the building and the height of the walls that are visible through the objective of the camera.

The data can be taken inside the wall on the daubed face of the bricks after it was walled and the exterior raw.

The thin daub on the wall is characterized by a spaced pattern of vertical light, uniform along the wall. Like this, the holes can be clearly seen. An interesting thing can represent the changes in the vertical pattern mostly seen at the middle of the wall’s height. These appear because the changes of the walling type. At the end, the data recorded on magnetic support are processed at the office, with Acad.

3. Thermography for new buildings Here there are some discrete disadvantages. The environment

conditions, the optimum evaluation moment of the construction, differences between regions and projects. So it is necessary to resent a list of factors that can substantially influence the thermo vision measurements:

• The temperature gradation – in some climatic areas, in a certain period of the year, the temperature does not very much vary from day to night;

• The moisture – the moisture is often present in the new constructions. The moisture on the masonry substantially alternates the results by the cold vaporization effect on the porous surfaces;

• The wind – in many situations, the masonry is exposed to different speeds of wind. The convection losses can substantially alternate the thermographic images cu particularities at the corners and at the entries;

• The solar exposure – often some parts of the buildings can be exposed to a solar radiation significant different from other parts. In the responsability of the thermography specialist to take into consideration the differences of solar exposure;

234


• Obstructions – the mobile constructions can obturate parts of the facade that will be measured by thero vision. It is important that the thermography specialist to have a deployment scheme of the activities;

• The architectural feature – the metalic elements, the bulwarks and the windows can mirror a most part of the energy and can affect the thermographic images;

• The age of the construction. 4. Thermographic applications in constructions Thermographie is used for diagnosing the ptoblems of the

buildings, since the middle 60ies. During the 70ies and 80ies, when the energy price grew up dramatically, thermographie becomes in a greater measure an instrument that helps incresing the performance of a building. I will present you the major applications of this technology in the construction field:

• Isolation control: it is essential to know what type of isolation has the building and other details, including how the isolation was installed. The isolation can be at its place but non performant, often a distructive evaluation establishing the conditions and allowing the understanding of the construction details. Every isolation type has its thermal characteristic that implies a certain pattern in the thermal image. A lot of factors have an impact over the thermal image. When the test is done during the day time or in the morning, the solar radiation impact must be taken into consideration. The action of the Sun from the last 6-8 hours manifests alike on both sides of the exposed wall. The air flow must be taken into consideration because this can debase the final diagnose. The cost of a weak performance of a building is huge. Regarding the large energy consume, we can have problems concerning the freezing of the sewarage or of the fire prevent systems, problems concerning the presece of mouldiness inside cold spaces, distructions of the roof and interior caused by ice, condensed and water infiltrations.

• Locating the air losses. An excessive leak of air means a growth of the energy consumed in the building. Of course, an adequate air exchange is essential for the healthy of the inhabitants and for the

235

Knowledge Based Organization 2008 International Conference safety but many buildings have a higher rate of air exchange than it is necessary.

The essence of the problem consists in the weak design and/or in the air plugs construction along the thermal perimeter. The inspection of the air losses will lead to controlling and improving this flow. The problem is solved when, in every day of the year, the difference of temperature between inside and outside is higher than a few degrees.

• Humidity or condense [4]: in the design and the shaping of the thermal covering, the humidity (produced by leaks and condense) can create many problems.

A good construction of a building presumes both airflow and slow humidity emergence process. Locating the humidity by thermography is often simple because the water has both heat conductivity and high capacity of heat. The determinations of the humidity source can e difficult. Condense and the leaks are often hidden so it is important to identify the source of air that transports the humidity in walls sections and the cold airflow that determines condenses.

EIFS construction: the growth of the popularity of buildings that use Exterior Isolation and Finish System – EIFS – has been followed by numerous cases of humidity linked to structural destructions. Also assigned to windows losses, the regular water infiltrated where the system was not properly installed.

An example of thermo graphic study of the energetic plumbing was recently presented. It is about a thermal study nondestructive, using the infrared thermography for building ventilation air conditioning applications (HVAC – heating, ventilating and air conditioning). In these applications, it was done the evaluation of the thermal form of the thick walls, of the barriers with their constructive elements, of the air conditioning plumbing but also of the thermal systems, cables, conductors, switchers from the wiring. It was studied the influence of the humidity over the thermal behavior of the construction materials. The results have shown the relation between the water vaporization and the porosity due to material structure and the study has shown the utility of this technique in detecting various invisible defects from the energetic and thermal installations.

Substratums – heat source: the anchored heat starts more and more to be kept out of some thermal routes and the heat reaches into

236

Knowledge Based Organization 2008 International Conference the rooms through hot water or electric conductors. Thermography is a quick way of checking the location and the performance of these underface instalations.

Specialists in thermography are often asked if they can locate the steel structures in buildings. This is very difficult. The heat of steel is not a simple distribution, is often filled with an inductive current, or DC-powered heating. Second heat of steel is often insufficient to define a single area, the thermal image. Other methods based on broadcasting and receiving radio signals, is probably more efficient in these cases.

Checking the details of construction: is not the area of the application that is very important but checking the details and the performance. Thermography can be used successfully to verify the relationships between the beams and insert in the walls of masonry prefabricated elements. How? Solid portion of the wall changes temperature more slowly than the rest.

The fatigue syndrome of the building: When the buildings are too wet or too sealed occurring health problems. Grouped together as 'sick building syndrome' these arise in the event of an inadequate HVAC system, a humidity installed in the walls, a mold, wet surface and a rate of exchange of air inadequate. Many cases can be viewed and diagnosed and part with thermography can be resolved.

Demarcation thin layers in facades: A great deal has been concluded in SE Asia with inspections at large facades of buildings for the delimitation layers / facades of thin materials. Failure of these materials has resulted in opinions revision of the staff. Masonry exposed used to change the temperature quickly when the top layer begins to change temperature compared with subadiacent layer is a new idea. Diurnal cycle is typical to adjust sources heat and inspection ends successfully in the first hours after a series of warm and sunny day.

Inspection of the roof humidity: Straight roofs inspection in especially of brindging is made a nomber of years. With thermography the infiltrated moisture can be detected before it produces degradations of bridging. Moisture from the roof appears on the surface at night after a sunny day due to higher capacitance.

237


5. Standards and references Some standards are important to support the work of specialists in

thermography: ASTM C 1060-97 practice in thermograph inspection of isolation

facilities and buildings covering; ASTM C-1153-97 practice in the location of wetlands in the

coverage using infrared images; ISO 6781 thermal isolation, qualitative detection of bridging

thermal jacket buildings, IR method; American Concrete Institute Design Standard 530 / American

Society of Civil Engineers Standard 5, Masonry Building Code and Specification;

Canadian General Standards Board Manual for thermo graphic analysis of the constructions (149-GP-2MP).

6. Qualification of the experts in thermography Energy auditors are independent experts authorized by the

Ministry of the resort, to make surveys, certificates and energy audits. This specialization is very new in Romania (appeared in 2003),

not yet being passed in the nomenclature of trades. UNESCO Chair of Engineering Sciences of the University Politehnica Bucharest in 2001 began the first program (Master) for training energy auditors in this profession. Meanwhile, other courses with this profile appeared, organized by the Technical University of Construction Bucharest and the Technical University of Iasi. These courses are post-graduate and addressed to graduates of colleges or technical architects. Courses are subsidized by the budget or tax and are held during the variables (3 months - 3 semesters).

7. Conclusions Inspection systems is done in a very economically without

stopping the technological process; Thermal vision system provides an image that allows a rapid and

precise identification of points that are defective overheat potential. It is also possible an assessment of the primary losses of heat.

Registered images can be analyzed with a dedicated program on any personal computer is possible the discovery of defects early

238

Knowledge Based Organization 2008 International Conference assessment of the degree their risk planning repairs - thereby obtaining a decrease in the rate of failure as well as a secure operating higher.

There are 3 great categories of loss of heat that need to be tracked: 1. Heat loss through all windows. 2. The loss of heat through certain facade. 3. The loss of heat through bridges, attics, mezzanines. Thermography (thermo vision) means measuring ther thermal

field by recording the infrared radiations and viewing the distribution of temperature on the surface observed. Thermo vision is a non-contact and non-distructive method for detecting flaws while operating industrial systems, without shutting down the process technology.

Activities for the conservation of energy, including optimal use of energy resources in primary and secondary, is the most urgent and effective measures in the development of a healthy economy. These activities require obtaining accurate information on the energy performance of equipment, facilities and equipment. Information are obtained by carrying out analysis of balance sheets or energy to support scientific and technical, based on data collected from the inspection objectives. Such systems optimized can obtain a certificate certifying energy effieciency.

Industrial ecquipments in which the technological processes require higher thermal levels in relation to the environment present energy losses that depend on the topology facilities and the quality and status of their isolation.

The evaluation of the losses of energy, which reduces the yield systems, means the knowing of the distribution of all its components. This is accomplished with the help of thermography system that views the temperature distribution on the equipment surface, by measuring the IR radiation (infrared).

References

[1] Rosina, Elisabetta, and Jonathan Spodek, Using Infrared Thermography to Detect Moisture in Historic Masonry, Association of Preservation Technology, 2002, pp. 11-16.

[2] Gale, Frances R., “Laboratory Testing for Historic Preservation Projects.”

239

Knowledge Based Organization 2008 International Conference [3] Maldague, Xavier P. V., ed., and Patrick O. Moore, ed., Infrared and

Thermal Testing, Vol. 3 of Non-Destructive Handbook, Columbus, Ohio: American Society of Non-Destructive Testing, 2001.

[4] Krogstad, Norbert V., Tricky Bricky. Building Renovation, Spring 1995, pp.43-46.

240


NUMERICAL SPECTRAL STUDY FOR VISCOUS

TEMPORAL STABILITY OF A TRAILING VORTEX

Dipl. Math. PhD Stud., Diana-Alina Bistrian,

Dipl. Math. PhD, Ştefan Maksay

University ”Politehnica” of Timisoara, Faculty of Engineering Hunedoara,

Hunedoara, Romania, [email protected]



Abstract

This paper presents a numerical investigation upon the temporal stability

of a Q type vortex subject to infinitesimal perturbations. The study is based on

spectral collocation technique using Chebyshev Gauss-Lobatto points and the

nonlinear eigenvalue problem is obtained in a matrix form and is solved by an

Arnoldi type algorithm. Our procedure directly provides relevant information

about the state of the fluid system for given parameters, in axisymmetrical and

non-axisymmetrical mode and also permits a graphical visualization of the

differences between perturbed velocity fields developed for the first unstable

temporal frequency and the least stable one.

Keywords: temporal stability, trailing vortex, perturbation

1. Introduction

We present in this paper a numerical investigation upon temporal

stability of a trailing Q type vortex, subject to infinitesimal

perturbations. Such problems may be of interest in the field of

aerodynamics, where vortices trail on the tip of each wing of the

airplane and a stability analysis is needed. Using a spectral Chebyshev

Gauss-Lobatto collocation technique, we developed a numerical

procedure which directly provides relevant graphic information about

241


perturbation velocities amplitude for stable or unstable induced

modes. Our paper is organized in the following manner. We set the

problem and the perturbations form in Section 2. Section 3 describes

in detail the numerical procedure based on collocation technique and

relates the results and Section 4 concludes the paper.

2. Viscous analysis model for temporal stability

In literature, the properties of swirl flows are presented in a

beautiful synthesis in [1]. The stability of three-dimensional Burgers

vortices class were first studied in [4] and, later, a study against

instability for a trailing vortices class was made in [2].

We consider for our purpose the one-parametric model of the Q-

vortex, in form related in [1]

( ) ( ) ( ) ( )22

,1,0 rrerWe

r

QrVrU

−− =−== (1)

where U, V, W are the radial, tangential and axial velocity

components, respectively, and Q is the swirl parameter.

Distribution of tangential velocity in (1) corresponds to the

Burgers vortex [3], the velocity fields of which satisfies the Navier-

Stokes equations.

The flow is assumed to be incompressible and the lengths in

cylindrical coordinates are nondimensionalized with respect to the

length scale s/ν , where ν is the viscosity of the fluid and s is the

strain rate of the base flow field.

In preparing our tools to perform the numerical computation, we

first obtain the linearized Navier-Stokes equations, in cylindrical polar

coordinates, subject to the base flow of form (1).

We perform a linear stability investigation of the proposed base

flow, in which the velocity and pressure p fields are decomposed into

their mean parts ( )PWVU ,,, and small perturbations ( )',',',' pwvu .

We use in this note the standard form of the perturbations, in detail

described in [1]

( ) ( ) ( )tnziTTerprwrvrupwvu

ωθα −+= )(),(),(),(',',',' (2)

242


where u , v , w and p are the disturbances eigenfunctions, α is the

axial wavenumber, n is the integer azimuthal wavenumber, θ is the

azimuthal angle and ω is the complex temporal frequency.

We obtained the hydrodynamic temporal stability model of the

following form

( ) ( )rsrs ΗΜω −≡ , ( ) ( )Trprwrvrurs )(),(),(),(= (3a)

Relation (3a) consists in a set of partial differential equations for

the perturbation velocities and pressure, expressed in a matriceal form.

The non-zero elements of the 4 × 4 matrix operators M and H are

given by

immm −=== 332211

and

+−+=

2111

Re

1

rWi

r

Vinh ∆α ,

Re

22212

r

in

r

Vh +−= ,

rh

∂

∂=14 ,

Re

2'

221r

in

r

VVh −+= ,

−−+=

2221

Re

1

rWi

r

Vinh ∆α ,

r

inh =24 ,

'31 Wh = , ∆αRe

133 −+= Wi

r

Vinh , αih =34 ,

rr

h1

41 +∂

∂= ,

r

inh =42 , αih =43 ,

where 2

2

2

2

2 1α∆ −−

∂

∂+

∂

∂≡

r

n

rrr and primes denote drdVV /'≡ and

drdWW /'≡ . The Reynolds number Re is defined according to the

maximum difference of axial velocity and the vortex core radius, as

described in [2].

The system (3a) has to be solved with the following boundary

conditions [8]:

0=r

0=nCase 0== vu , 0/ =drwd , (3b)

1±=nCase 0=± viu , 0/ =drud , 0=w , (3c)

1>nCase 0=== wvu ; (3d)

∞→r 0=== wvu . (3e)

243


In the temporal stability analysis that we will study here, for a

given real wavenumber α and given the parameters Re, Q and n, the

system (3a-3e) constitutes a nonlinear eigenvalue problem for the

complex eigenvalue ω. The flow is considered unstable when the

disturbance grows in time, i.e. the imaginary part of the

eigenfrequency ω is positive.

3. Spectral collocation based investigation

3.1. Chebyshev spectral differentiation matrices

Spectral methods are one of the most used technique for the

numerical investigations in hydrodynamic stability problems. Started

with Orszag [9], many researchers have demonstrated the applicability

of this technique with high degree of accuracy, as in [5], [6], [7].

We choose for our study a Chebyshev Gauss-Lobatto collocation

approach, for the reasons that Chebyshev polynomials distribute the

error evenly, exhibit rapid convergence rates with increasing numbers

of terms and cluster the collocation points near the boundaries,

diminishing the negative effects of the Runge phenomena [11].

The Chebyshev Gauss-Lobatto points are given explicitly by

( ) NjNjj ..0,/cos == πξ (4)

In order to compute the derivatives ( ) rrs ∂∂ / and ( ) 22 / rrs ∂∂ we

constructed the Chebyshev spectral differentiation matrices of first

and second order as we describe hereinafter.

Let Njj ..0, =ξ be the interpolation points and Nuuu K,, 10

be the components of the eigenvector u . Let as consider, for a simpler

explanation, that 2=N . Then 1,0,1 −∈ξ and the eigenvector can

be expressed is the quadratic form

( ) ( ) ( )( ) ( ) 210 15.01115.0 uuuu −⋅+−+++⋅= ξξξξξξξ (5)

Differentiating (7) yields

( ) ( ) ( ) 210 5.025.0' uuuu −+−+= ξξξξ (6)

The spectral differentiation matrix D2 is the 3×3 matrix whose jth

column is obtained by sampling the jth term of this expression at

ξ = 1, 0, and -1, yielding

244


( )5.125.0;5.005.0;5.025.12 −−−−=D (7)

For arbitrary N, the entries of Chebyshev spectral differentiation

matrix DN are

6

12 2

00+

=N

d , 6

12 2 +−=

NdNN , ( )212 j

jjjd

ξ

ξ

−

−= , 1,,1 −= Nj K ,

( )( )ji

ji

j

iij

c

cd

ξξ −

−=

+1

, ji ≠ , 1,,1, −= Nji K , =

=otherwise

Niifci

1

,02.

For N collocation points, the derivatives are expressed as

( ) ( )TNN uuuDu ,,,' 10 K⋅=ξ , ( ) ( )TNN uuuDu ,,,'' 102

K⋅=ξ (8)

where DN2 denotes the squared Chebyshev spectral differentiation

matrix of first order.

Because Chebyshev polynomials are defined on the interval

[ ]11−∈ξ and the physical range of our problem is [ ]max0 rr ∈ ,

we made use of the transformation (Figure 1)

( )max

21,

1

r

ab

bar +=

+

−=

ξ

ξξ (9)

The differentiation matrices N∆ in the physical coordinate r are

obtained by a multiplication of the corresponding matrices in the

standard interval [ ]11− by the diagonal matrix S with the entries

( ) jkjjk ddrS δξ1

/−

= , NN DS ⋅=∆ (10)

where jkδ is the Kronecker delta symbol and ND is the spectral

Chebyshev differentiation matrix in the standard interval.

Because large matrices are involved, we numerically solved (3a-

3e) using the Arnoldi type algorithm [10, 11], which provides entire

eigenvalue and eigenvector spectrum.

For non-axisymmetrical modes (case 1>n ), our boundary value

problem have been solved subject to Dirichlet boundary conditions.

This was numerically implemented as part of spectral collocation

method by discarding the no effect first and last columns of the

Chebyshev differentiation matrices of first and second order and also

ignoring the first and last rows.

245


Figure 1: The graphic representation of the Chebyshev collocation points

(left, N = 100) and their corresponding points (right), maped into the physical

range, for different values of parameter a (rmax=3)

For implementing the boundary conditions in the axisymmetrical

mode 0=n , first we retained the location of rows in matrix M and

their corresponding columns which were replaced with zero. Then we

operate the H matrix by replacing some lines with their corresponding

lines of identity block matrix, for Dirichlet boundary conditions

imposed to u , v , p (at 0 and rmax) and w (at rmax), and also, a specific

line has been replaced with its corresponding of the block Chebyshev

differentiation matrix of first order, for Newman condition fulfilled by

w at limit 0.

3.2. Numerical results

In case n = 2, for given parameters Re = 8000, α = 3.5, Q = 1, the

fluid system is stable, as can be seen in Figure 2a.

For axysimmetrical mode n = 0, having the same initial

parameters, Re = 8000, α = 3.5, Q = 1, an eigenvalue with positive

imaginary part occurred in spectra, thus the conclusion that the fluid

system became unstable (Figure 2b).

We denote by the least stable eigenfrequency, the stable

eigenvalue with maximum imaginary part, and by the first unstable

eigenfrequency, the unstable eigenvalue having minimum imaginary

part. The least stable eigenfrequency is ωLST = 1.7591 − 0.051863i,

and the first unstable one ωFUS = 3.2934 + 0.02789i. Figure 3 presents

246


the variations in time of the differences between perturbed velocity

fields developed for temporal frequencies ωFUS and ωLST.

a. b. Figure 2: Zoom in the eigenvalue spectra, for N=100 collocation points

a. Case n=2, Re=8000, α=3.5, Q=1; b. Case n=0, Re=8000, α=3.5, Q=1

Figure 3: Variations in time of the differences between perturbed velocity fields

developed for the first unstable eigenfrequency and the least stable one

247


4. Summary and conclusions

We have made a numerical investigation upon the temporal

stability of a trailing swirl flow, namely the Q vortex, subject to

infinitesimal perturbations. We have implemented a temporal stability

analysis method based on Chebyshev Gauss-Lobatto spectral

collocation technique and we numerically obtained information on the

state of the fluid system. For fixed parameters Re, α, and Q, the stable

system in non-axisymmetrical mode became unstable if the tangential

wavenumber n is set to zero. We obtained a graphical visualization of

the differences between perturbed velocities developed for the first

unstable temporal frequency and the least stable one, in the

axisymmetrical mode.

References

[1] Alekseenko S.V., Kuibin P.A., Okulov V.L., Theory of concentrated

vortices, Springer-Verlag Berlin Heidelberg, 2007.

[2] G.K. Batchelor, Axial flow in trailing line vortices, J. Fluid Mech 20:645-

658, 1964.

[3] Bistrian D.A., Maksay Şt., Approximate method for numerical investigation

of temporal stability of swirling flows, in print, Proceedings of International

multidisciplinary symposium “Universitaria SIMPRO 2008”, Petroşani,

2008.

[4] Burgers J.M., A mathematical model illustrating the theory of turbulence,

Adv. Appl. Mech. 1:171-199, 1948.

[5] Canuto C., Hussaini M.Y., Quarteroni A., Zang T.A., Spectral methods-

Evolution to complex geometries and applications to fluid dynamics,

Springer Berlin Heidelberg New-York.

[6] Crowdy D.G., A note on the linear stability of Burgers vortex, Studies in

Applied Mathematics, 100:107-126, 1998.

[7] Hesthaven J., Gottlieb S., Gottlieb D., Spectral methods for time dependent

problems, Cambridge University Press.

[8] Korrami M.R., Malik M.R., Ash R., Application of spectral collocation

technique to the stability of swirling flows, Journal of Computational

Physics 81, 206-229, 1989.

[9] Orszag S. A., J. Fluid Mech. 50, 689, 1971.

[10] Saad Y., Iterative methods for sparse linear systems, PWS Publishing

Company, Boston, 1996.

[11] Trefethen L.N., Spectral methods in Matlab, SIAM, Philadelphia.

248


APPROXIMATE MODELING OF DEGREE 4 OF

SLIDING SECOND ORDER PHENOMENA

Dipl. Math. PhD Stud., Diana-Alina Bistrian

Dipl. Math. PhD, Ştefan Maksay,





Abstract

This note presents the 4th

degree polynomial modeling of the horizontal

fluid velocity in the boundary layer in the neighborhood of a plane plaque,

subject to second order sliding phenomena. Considering a second order sliding

boundary layer in the neighborhood of an unlimited plane plaque, a new

approach for the numerical solution of the involved viscous fluid flow is given.

The profile of the boundary layer and its characteristic values together with the

velocity field are explicitly determined.

Keywords: sliding boundary layer, velocity profile

1 Introduction

Let us envisage a fluid stream past a semi-infinite plane plaque

with the "attack" angle zero. Suppose that the fluid is viscous

incompressible while the flow is plane (in Oxy ). The plane plaque is

considered located on the real axis Ox , its “attack” edge being atO .

According to the well known boundary layer approximation

(Prandtl), the Navier -Stokes equations

249


,. ux

puv ∆µρ +

∂

∂−=∇

r,. v

y

pvv ∆µρ +

∂

∂−=∇

r,0=

∂

∂+

∂

∂

y

v

x

u (1)

lead to

,2

2

y

u

y

uv

x

uu

∂

∂=

∂

∂+

∂

∂µρ (2)

,0y

v

x

u=

∂

∂+

∂

∂ (3)

where ρ , p , and )v,u(vr

, are the mass density, the pressure and the

plane velocity respectively while µ is the viscosity coefficient.

To these equations one attaches the boundary conditions

,2

2

11 ),(,0)0,(,)0,()0,( ∞=∞=∂

∂+

∂

∂= uxuxv

y

uMx

y

uLxu (4)

the first one signifying the fact that the fluid slides on the plaque

surface (in stead of the adherence on the plaque, i.e. of the classical

non-slip condition 0)0,( =xu ).

Such sliding boundary conditions have been considered before in

[1]. In a previous attempt we have given a new numerical method for

approaching this problem which is based on a particular polynomial

development of the velocity profile inside the boundary layer [2].

The goal of the present work is to improve the previous attempts

by considering a more accurate polynomial representation for the

velocity profile.

2 Results

By using the expression of v which comes from (3), the above

relation (2) leads to

2

2

0 y

u

y

udy

x

u

x

uu

y

∂

∂=

∂

∂

∂

∂−

∂

∂∫ µρ .

Integrating this integro-differential equation across the boundary

layer, namely from 0y = to )x(y δ= - the upper border of the

boundary layer, i.e.

250


,0

00 0

∫∫ ∫ −=∂

∂+

∂

∂−

∂

∂ δδ

δ

τρρρ w

y

dyx

uudy

x

uudy

x

uu

we get the integral relation

,10

2

wdy

u

u

u

u

dx

du τρ

δ

−=

−

∞∞

∞ ∫ (5)

where

w

wy

u

∂

∂= µτ .

In a previous paper we have suggested the approach of this

equation by using a velocity profile (within the boundary layer) of a

polynomial form [3].

In this paper we solve this equation by considering a velocity

profile of a polynomial type of 4th degree. Precisely we suppose that

,4

4

3

3

2

210 ηηηη aaaaauu

u++++=≡

∞

,10 ≤≤η (6)

and

,1=≡∞

uu

u 1≥η where

( ).

x

y

δη ≡

The coefficients ia can be determined by using the appropriate

conditions

,2

_2

ηη ∂

∂+

∂

∂=

uM

uLu ,0

3

3

=∂

∂

η

u for 0=η (7)

,1=u ,0=∂

∂

η

u ,0

2

2

=∂

∂

η

u for 1=η (8)

where

2

11

)(,

)( x

MM

x

LL

δδ== , )0(,0)( ≠≠ xxδ

Following the calculations, by using the 4th degree polynomial

approximation, it results for the non dimensional profile of the

horizontal component of the velocity the expression

251


( ).681281283

1 42 ηηη +−+−−+

= MLML

u (9)

The influence of the M parameter on the nondimensional

velocity’s profile is presented in Figure 1.

Figure 1: The influence of the M parameter

on the nondimensional u velocity

The thickness of the impulse losses

,11

0

ηδθ du

u

u

u∫

−=

∞∞

(10)

has in this case the following form

2)1283(315

)75650479(4

ML

ML

−+

−+=

δθ .

The local tension between two neighboring layers

,

∂

∂=

y

uµτ (12)

has the expression

( )( ).2()1

1283

4 2 +−−+

= ∞ ηηδ

µτ

ML

u (13)

The local stress on the plaque has the structure

252


( ).

1283

8

ML

uw

−+= ∞

δ

µτ (14)

In Figure 2 one could see the influence of the M parameter on the

local tension distribution in the boundary layer.

Figure 2: The influence of the M parameter

on the local tension distribution

In Figure 3 it is represented the profile of the local stress between

two neighboring layers, for several values of M.

Figure 3: Profile of the local stress between two neighboring

layers, for several values of M

Replacing then the velocity (9) and the local stress on the plaque

(14), in the integral relationship (5), it comes out that

253


( )

,1283

8

)1283(315

)75650479(42

2

ML

u

ML

ML

dx

du

−+=

−+

−+ ∞∞ δ

µδρ

and

( )

,16

)75650479(4

)1283(3152

∞−+

−+=

uML

ML

dx

d

ρ

µδ

from where, by integrating, we get

( ) ,75650479

)1283(3152

∞−+

−+=

u

x

ML

MLx

ρ

µδ (15)

The acquaintance of delta(x) permits to establish a

correspondence between the modeling variable eta and the variable y

of physical plane, in accordance with the x section in which the

correspondence is performed.

References

[1] C. Iacob, Introduction mathematique a la mecanique des fluides, Gauthier –

Vilars., Paris, 1959.

[2] T. Petrila, Mouvement general d’un profil dans une fluide ideal en presence

d’une paroi permeable illimitee. Cadre variationel et approximation par

une methode d’elements finis, Mathematica – Revue d’Analyse numerique

et de la théorie de l’approximation, 8, 1, pp. 67 – 77, 1979.

[3] L. Howarth, Modern Developments in Fluid Dynamics High Speed Flows,

vol. I, Oxford, 1953.

[4] L.M. Milne – Thomson, Theoretical hydrodynamics, St. Martin’s Press,

New – York, 1960.

[5] Şt. Maksay, Solving the dynamical problem of the fluids movement on a

plane plaque, considering the sliding phenomenon, Universitatea

“Politehnica” din Timisoara, Anal. Fac. Ing. Hunedoara, Tom I, Fasc. 4, pp.

39 – 46,1999.

[6] Şt. Maksay, Dynamic boundary layer with sliding on a plane plaque,

Universitatea “Politehnica” din Timisoara, Anal. Fac. Ing. Hunedoara, Tom

III, Fasc.5, pp. 39 – 44, 2001.

[7] H.W. Emmons, (editor), High Speed Aerodynamics and Jet Propulsion, vol.

III, Fundamentals of Gas Dynamics, Princeton Univ. Press, 1958.

[8] T. Petrila, Şt. Maksay, A New Numerical Approach of a Sliding Boundary

Layer, An International Journal computers & mathematics with

applications, Elsevier, 50, 113-121, 2005.

254


OPTIMIZATION OF THREE-DIMENSIONAL

TRUNCATED von MISES MODELING

Dipl. Math. PhD, Ştefan Maksay,

Dipl. Math. PhD Stud., Diana-Alina Bistrian





Abstract

This paper introduces a numerical method for a truncated modeling of the

three-dimensional von Mises distribution. We suggest a method of truncation in

which the limits are determined using the least squares optimization, under the

conditions in which the corresponding probability density approximates ever

better the numeric data. The results we obtained by simulating the three-

dimensional von Mises rule and that of the corresponding truncated one, are

presented comparatively. Calculations have been done in MATLAB.

Keywords: Mises distribution, least squares optimization

1. Introduction

Starting from the Three-sigma rule, according to which, in certain

problems in probability theory and mathematical statistics, an event is

considered to be practically impossible if it lies in the region of values

of the normal distribution of a random variable at a distance from its

mean value of more than three times the standard deviation, arose the

idea of truncating the normal distribution [5]. We are going to give in

Section 2 the rule of three-dimensional von Mises distribution, and the

way in which it can be truncated. In order to obtain an optimal

255


truncation corresponding to a set of numerical data, we elaborated a

program under MATLAB. The modeling we obtained can be

compared to the three-dimensional classic one, as it will be shown in

Section 3. The application that we are going to analyze will prove that

the rule of truncated von Mises distribution, as it is built in this paper,

can be used in data modeling more efficiently than the classic von

Mises rule. Section 4 presents an analysis of the results we obtained,

and includes the conclusions of the paper.

2. The truncated three-dimensional von Mises law against the

classic law

In probability theory and statistics, the von Mises distribution

(also known as the circular normal distribution) is a continuous

probability distribution, previously appeared in the literature in [2],

[3], [4]. It may be thought of as the circular version of the normal

distribution, since it describes the distribution of a random variate with

period 2π and it is used in applications of directional statistics.

We have started from a set of numeric data that are going to be

processed, which is given bellow, where the first three lines represent

the values of the independent variables x, y and z, and the last line

represents the independent variable u.

Table 1: Numeric Data

1 2 3 4 5 6 7 8 9 10 11 12 13

x 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

y 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

z 1.

5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

7.

5

u 9⋅10-4

3.5⋅10-3

4.2⋅10-3

3.8⋅10-3

8.6⋅10-3 0.0112 8.6⋅10

-3 8.4⋅10

-3 6.8⋅10

-3 5.1⋅10

-3 4.2⋅10

-3 2.9⋅10

-3 1.5⋅10

-3

These variables are characterized by the mean values

mx = 3, my = 4, mz = 4.5, mu = 0.005361538461538

and the standard deviations

sx = sy = sz = 1.870828693386971

su = 0.002986002849589.

256


Let

vx = vy = vz = 3.791666666666667

be the variance of the variables x, y and z, and let

µx = mx , µy = my, µz = mz

kx = 1/vx, ky = 1/vy, kz = 1/vz

kx = ky = kz = 0.263736263736264,

be the constants that appear in the von Mises density law.

With these values the classic two-dimensional law which have

been introduced in [6] becomes the three-dimensional law

[ ] [ ] [ ] Rzzyyxxfc →+−×+−×+− πµπµπµπµπµπµ ,,,:

( ))(0)(0)(08

,,3

)cos()cos()cos(

kzIkyIkxI

ezyxfc

zzkzyykyxxkx

⋅⋅⋅⋅=

−⋅+−⋅+−⋅

π

µµµ

(1)

where x, y and z are the independent variables and I0(t) is the

modified Bessel function of first kind [1], having the form

( )∑=

+

++⋅

=10

0

20

10!

2)(0

p

p

pp

t

tIΓ

(2)

We are going to approximate this rule (1) by a new function being

null without a finite parallelepiped, situated in the vicinity of the mean

values of variables x, y, respectively z.

Let

[ ] [ ] [ ] Rzzyyxxft →+−×+−×+− πµπµπµπµπµπµ ,,,: ,

be of form

−+<<+−

−+<<+−

−+<<+−

⋅⋅⋅⋅⋅

=

−⋅+−⋅+−⋅

otherwise

zzzzz

yyyyy

xxxxx

if

kzIkyIkxI

e

K

zyxft

zzkzyykyxxkx

,0

,)(0)(0)(08

1

),,(

3

)cos()cos()cos(

απµαπµ

απµαπµ

απµαπµ

π

µµµ

(3)

257


where K will be determined by imposing the condition that this

function be a probability density and xα , yα , zα are positive

constants that are going to be determined using the least squares

optimization.

Hence, for K results the expression

( ) dxdydzzyxEKxx

xx

yy

yy

zz

zz∫ ∫ ∫

−+

+−

−+

+−

−+

+−=

απµ

απµ

απµ

απµ

απµ

απµ,, (4a)

where

( ))(0)(0)(08

,,3

)cos()cos()cos(

kzIkyIkxI

ezyxE

zzkzyykyxxkx

⋅⋅⋅⋅=

−⋅+−⋅+−⋅

π

µµµ

(4b)

3. Description of the method of truncated modeling

In order to determine an optimal modeling of the data we have

presented before, we processed them both classically and in the

truncated way. Constants xα , yα and zα are going to be determined

by minimizing the error resulted from the use of the truncated function

instead of the classic law. In order to achieve this, the necessary

condition is that the sum of the squares of the differences between the

theoretical values of the function and the experimental values u, be

minimum

( )∑=

−=n

iiiii uzyxftzyxM

1

2),,(),,( ααα (5)

The parameters of the truncated function that optimally models

the cloud of points, have been determined with the help of the

MATLAB program we are giving in Appendix 1.

We shall find the minima of ),,( zyxM ααα considering that

[ ]6.0,0∈xα , [ ]35.0,15.0∈yα and [ ]65.0,05.0∈zα .

4. Results and interpretations

The running of the program, which has found a minimum value

258


of the deviations sum (5), has led to the following results, given in

Table 2.

Table 2: Numeric Results

Constants Values

fmin 1.642124241580566e-005

alfa_xf 0

alfa_yf 0.300000000000000

alfa_zf

0.500000000000000

the value of constant K from the formulae (3), respectively (4) being

K = 0.814934315559693.

The domain in which the truncated function we thus determined

has non-null values is

( ) ,,|,, zzzyyyxxxzyxV µαπµαπµαπ <+−<+−<+−=

case in which the truncated function is expressed by

[ ]

+<<−

+<<−

+<<−

⋅⋅⋅

=

−+−+−

otherwise

z

y

x

if

I

e

zyxft

zyx

,0

45

7.33.4

33

,)2637.0(088149.0

1

),,(

33

)5.4cos()4cos()3cos(2637.0

ππ

ππ

ππ

π

(6)

As both the classic function and the truncated one we obtained are

threevariate functions, for a more suggestive graphical representation,

we successively substituted each variable by its mean value, which

resulted in three partial functions.

Figure 1 presents in part a, the representation of the classic von

Mises distribution and in part b, the partial truncated von Mises

distribution, considering variables x and y, variable z being substituted

by its mean value mz. The representations of the two partial rules,

259


considering variables y and z, x being substituted by mx, and the

representations of the two partial distribution rules for variables x and

z, y being substituted by my are similar with those depicted in Figure

1.

a. b.

Figure 1: The graphic representation of the partial von Mises distribution

a. The partial classic von Mises distribution law ),,( mzyxfc

b. The partial truncated von Mises distribution law ),,( mzyxft

Figure 2 presents the contour lines of the surfaces.

a. b.

Figure 2: The contour lines of the partial von Mises surface

a. Contours of the partial classic von Mises surface ),,( mzyxfc

b. Contours of the partial truncated von Mises surface ),,( mzyxft

We obtained the graph of the partial cumulative distribution

function given in Figure 3, in which variable z was substituted by mz.

Substituting x by mx and y by my, we obtained similar surfaces.

260


Figure 3: The graph of partial cumulative distribution function of the truncated

von Mises distribution law ),,( mzyxft

5. Summary

The considerations presented in the paper may lead to the

conclusion that the rule of parallelepipedically truncated von Mises

distribution obtained under the given conditions, preserving the

properties of a probability density, leads to a higher correlation

coefficient and to a smaller deviation than in the case of the classic

distribution, as it can be noticed from the results given hereinafter.

Correlation coefficients

r_fclas = 0.858684566837700, r_ftrunc = 0.926460245974576

Standard deviations

sigma_fclas=0.0015303397580, sigma_ftrunc= 0.0011239094685

Therefore, the optimal modeling of the existent data can be

obtained by means of the truncated distribution. In practical cases the

use of truncated modeling can be more expedient instead of using the

classic law.

Appendix 1

clc,clear;format long,nv=13; for i=1:nv, x(i)=0+(i-1)*0.5; y(i)=1+(i-1)*0.5;z(i)=1.5+(i-1)*0.5;end; u=[0.0009 .0035 .0042 .0038 .0086 .0112 .0086 .0084 .0068 .0051 .0042 0029 .0015 ]; fmin=10^10; F=0; mx=mean(x); my=mean(y); mz=mean(z); mu=mean(u);sx=std(x,1);sy=std(y,1); sz=std(z,1);su=std(u,1);vx=var(x);vy=var(y);vz=var(z);miu_x=mx; miu_y=my; miu_z=mz; kx=1/vx; ky=1/vy; kz=1/vz;

%The classic three-dimensional von Mises law fc=@(x,y,z)exp(kx.*cos(x-miu_x)+ky.*cos(y-miu_y)+kz.*cos(z-miu_z))/... (8.*pi^3.*besseli(0,kx).*besseli(0,ky).*besseli(0,kz));

%Initial data alfa_xi=0.0;alfa_xs=0.6;alfa_yi=0.15;alfa_ys=0.35;alfa_zi=0.05;

261


alfa_zs=0.65; %Starting the optimization

nt=4; for i=1:nt+1 alfa_x(i)=alfa_xi+(i-1)*(alfa_xs-alfa_xi)/nt; for j=1:nt+1 alfa_y(j)=alfa_yi+(j-1)*(alfa_ys-alfa_yi)/nt; for k=1:nt+1 alfa_z(k)=alfa_zi+(k-1)*(alfa_zs-alfa_zi)/nt; uinf=miu_x-pi+alfa_x(i);usup=miu_x+pi-alfa_x(i); vinf=miu_y-pi+alfa_y(j);vsup=miu_y+pi-alfa_y(j); winf=miu_z-pi+alfa_z(k);wsup=miu_z+pi-alfa_z(k); inte=triplequad(fc,uinf,usup,vinf,vsup,winf,wsup); ftr=@(x,y,z)exp(kx.*cos(x-miu_x)+ky.*cos(y-miu_y)+...

kz.*cos(z-miu_z))/(8.*pi^3.*besseli(0,kx).*besseli(0,ky).*besseli(0,kz)).* logical((x-uinf).*(x-usup)<0).*logical((y-vinf).*(y-vsup)<0).* logical((z-winf).*(z-wsup)<0);

for ks=1:nv F=F+(ftr(x(ks),y(ks),z(ks))/inte-u(ks))^2; end; if F<=fmin

alfa_xf=alfa_x(i);alfa_yf=alfa_y(j);alfa_zf=alfa_z(k);fmin=F;intef=inte; uinff=miu_x-pi+alfa_x(i);usupf=miu_x+pi-alfa_x(i);vinff=miu_y-pi+alfa_y(j); vsupf=miu_y+pi-alfa_y(j);winff=miu_z-pi+alfa_z(k);wsupf=miu_z+pi-alfa_z(k);

end; F=0; end; end; end;

%Calculation of K xinf=miu_x-pi+alfa_xf;xsup=miu_x+pi-alfa_xf;yinf=miu_y-pi+alfa_yf ysup=miu_y+pi-alfa_yf;zinf=miu_z-pi+alfa_zf;zsup=miu_z+pi-alfa_zf K=triplequad(fc,xinf,xsup,yinf,ysup,zinf,zsup)

References

[1] Abramovitz M., Stegun I.A., Zelen M., Severo N.C., Handbook of

mathematical functions-Probability functions, U.S. National Bureau of

Standards, Applied Mathematics Series-55, 1965.

[2] Best D., Fisher N., Efficient simulation of the von Mises distribution,

Applied Statistics, 1979.

[3] Evans M., Hastings N., Peacock B., von Mises Distribution, 3rd ed. New

York, Wiley, 2000.

[4] Gumbel E., Greenwod J., Durand D., The circular normal distribution:

theory and tables, Journal of the American Statistical Association, 48,131-

152.

[5] Maksay Şt., A probabilistic distribution law with practical applications,

Mathematica – Revue D’Analyse numerique et de Theorie de

L’Approximation, Tome 22 (45), Nr. 1, pp. 75-76, 1980.

[6] Maksay Şt., Bistrian D.A., Considerations upon the von Mises 2-

dimensional distribution, Journal of Engineering, Annals of Faculty of

Engineering Hunedoara, Tome V, Fascicole 3, pp. 175-180, 2007.

[7] Maksay Şt., Stoica D.M., Considerations on modeling some distribution

laws, Applied Mathematics and Computation 175, 238-246, ELSEVIER,

2006.

262


CENTRAL LIMIT THEOREM ANALYSIS OF RELIABILITY OF A TECHNICAL SYSTEM WITH

n-COMPONENTS AND THE MALLOWS DISTANCE CONVERGENCE

Assoc.Prof.Eng. Doru Luculescu, PhD, TA. Bogdan Gheorghe Munteanu

Air Forces Academy “Henri Coanda”, Brasov, Romania, doru_ @yahoo.comluculescu [email protected]

Abstract The importance of the central limit theorem in studying the reliability of a

system with n-components is illustrated in the present paper. A new proof of the classical Central Limit Theorem, in the Mallows distance is given. Our proof is elementary in the sense that is does not require complex analysis, but make use of a simple subadditive inequality related to this metric.

Keywords: Mallows distance, central limit theorem, reliability

1. Introduction For a long time, the Central Limit Theorem benefited of

numerous proofs based on the weak convergence: in Pohorov (1952, [6]), ( L1 convergence of densities) in Gnedenko and Kolmogorov (1968, [2]), ( L∞ convergence of densities) and information theoretic (convergence in relative entropy [1] and Fisher information [3]).

In this paper we consider the Central Limit Theorem with respect to the Mallows r - distance. To this aim, let us first remind the following

Definition 1.1. [3]. For any r>0, we define the Mallows r – distance between probability distribution functions and asXF YF

( ) rr

YXYXr YXEFFd/1

),(|inf),( −=

263


Knowledge Based Organization 2008 International Conference where the infimum is taken over all distributions of pairs

whose marginal distribution functions are and respectively, and may be infinite. So that

),( YXF

XF YF∫= dyyxFxF YXX ),()( ),(

and . ∫= dxyxFxF YXY ),()( ),(

Where no confusion is possible, we write for . ),( YXdr ),( YXr FFdAlso, we define the set ∫ ∞<=ℑ )(/ xdFxF r

r . The following proposition shows that the Mallows distance is a

metric on . rr ℑ×ℑProposition 1.1. [4]. Let +→ℑ×ℑ Rd rrr : . Then is a

metric on . ),( YXr FFd

rr ℑ×ℑIn [4] we proved. Theorem 1.1. [4]. Let be independent identically

distributed random variables with zero and finite variance ,...., 21 XX

02 >σ and let ( ) nXXXS nn /...21 +++= . Then

0),(lim 22 =∞→ σ

ZSd nn

where ),0(~ 22 σ

σNZ .

Theorem 1.1, generalized by us in Section 2 up to Theorem 2.1, implies the standard Central Limit Theorem in the sense of weak convergence. Theorem 1.1 is proved by using the following subadditivity relation of ),( 2

22 σ

ZSd n

( ) ),(),(, 222211

222121

22 YXdYXdYYXXd +≤++ (1)

2. Convergence of for general rd r Note that the subadditive inequality (1) arises in part from the fact

that a moment inequality holds, namely if and are independent

with mean zero, then 1X

2X

rrr XEXEXXE 2121 +≤+ for 2=r . Similar results will imply that for 2≥r , we have

0),(lim 2 =∞→ σ

ZSd nrn

In order to prove this, we combine the convergence to zero of , established in Theorem 1.1, with the Rosenthal's ),( 22 σ

ZSd n

264

Knowledge Based Organization 2008 International Conference inequality ([5], Theorem 2.9), which states that if are

independent with mean zero and

,...,21 XX

∞<r

iXE , then there exists a constant )(rc such that

( ) ⎥⎦⎤

⎢⎣⎡ +≤+++ ∑ ∑

= =

m

i

rm

ii

r

i

r

m EXXErcXXXE1

2/

1

221 )(... (2)

First, we prove the following lemma Lemma 2.1. Consider the independent random variables

and , where for some ,..., 21 VV

,..., 21 WW 2≥r and for all i, ∞<r

iVE , ∞<r

iWE Then for any m we have

( ) ⎥⎦⎤

⎢⎣⎡ +≤++++ ∑ ∑

= =

m

i

rn

iiiii

rrmm

rr WVdWVdrcWWVVd

1

2/

1

2211 ),(),()()...,...(

Proof. We consider the independent random variables and set and

)1,0(~ UU i

)(1*iVi UFV −= )(1*

iWi UFW −= . Then, using equation (2), we obtain

rm

iiimm

rr WVEWWVVd ⎥⎦

⎤⎢⎣⎡ −≤++++ ∑

=1

**11 )()...,...(

( ) ( )( )( ) ⎥⎦

⎤⎢⎣⎡ +=

⎥⎦⎤

⎢⎣⎡ −+−≤

∑ ∑

∑∑

= =

==

m

i

rm

iiiii

rr

rm

iii

m

i

r

ii

WVdWVdrc

WVEWVErc

1

2/

1

22

2/

1

**

1

**

),(),()(

)(2

Using Lemma 2.1 we establish our main result. Theorem 2.1. Let be independent and identically

distributed random variables with mean zero, variance ,..., 21 XX

02 >σ and ∞<

rXE 1 for some 2≥r . If ( ) nXXS nn /...1 ++= , then 0),(lim 2 =

∞→ σZSd nrn

where ),0(~ 22 σ

σNZ .

Proof. Theorem 1.1 convers the case 2=r therefore we consider only the case 2>r . We use a scaled version of Lemma 2.1 twice. First, in this lemma take into account that, for , nm = ii XV =

).,0(~ 2σNWi and, by monotonicity of the r - norms, for any n ,

265


⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛ ⋅+⋅≤

2/

1221 ),(1),(

)(1)(),( 222

r

rrrn

rr ZVd

nnZVd

nnrcZSd

σσσ

( )

( )⎥⎥

⎦

⎤

⎢⎢

⎣

⎡+≤

⎥⎥

⎦

⎤

⎢⎢

⎣

⎡+=

−

≤

−

43421

44 344 21

r

rr

XE

rr

r

ZXd

rrr

r

ZXdnrc

ZXdZXdnrc

1

2

21

22

),(1)(

),(),()(

12/1

),(

2/

1221

2/1

σ

σσ

σ

Therefore, , for any . KZSd nrr <),( 2σ

nNow, we consider the case nm ≠ define [ ]nN = , and take

⎥⎦⎤

⎢⎣⎡=

Nnm

and NNmnu ≤−−= )1( . In Lemma 2.1, we take

,....................................................

,...,...

,...

)1(2)2(1)2(1

322123

2212

211

NmNmNmm

NNN

NNN

N

XXXV

XXXVXXXV

XXXV

−+−+−−

++

++

+++=

+++=+++=

+++=

and

4444 34444 21termsNmnu

nNmNmm XXXV−−−=

+−+− +++=)1(

2)1(1)1( ...

On the other hand, still by Lemma 2.1 and Theorem 2.1, it follows that ),0(~ 2σNWi Ν for 1,1 −= mi and ),0(~ 2σuWm Ν independently.

Then ( ) KNZSdNWVd rN

rr

rii

rr

2/2/2,),( ≤=

σ, where

NVVS NN /)...( 1 ++= and ( ) KuZSduWVd ru

rr

rmm

rr

2/2/2,),( ≤=

σ, where

uVVS uu /)...( 1 ++= . Further,

.),(),(),(1,1 ),,(),(

22

2

22

22

22

22

22

σσ

σ

ZSNdZSudWVdmiZSNdWVd

Numm

Nii

≤=

−==

266


Using Lemma 2.1 again, we obtain

)...,...(1),( 112/2 nnrrrn

rr WWVVd

nZSd ++++=

σ

( )⎭⎬⎫

⎩⎨⎧ +≤ ∑ ∑

= =

m

i

rm

iiiii

rrr

WVdWVdn

rc1

2/

1

222/

),(),()(

0),(1

1),()1(

)(

),(1

1),()1(

)1()(

),(),()1(

)(

2/

22

222/

2/

22

222/

1)1(

1)1(

2/

2/2/

2/

22

22

2/

2/

22

22

2/2/

2

2

∞→

<−

−<

→⎭⎬⎫

⎩⎨⎧

⎟⎠⎞

⎜⎝⎛

−++

−≤

⎪⎪⎭

⎪⎪⎬

⎫

⎪⎪⎩

⎪⎪⎨

⎧

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛

−++

−+

−≤

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎟⎟⎠

⎞⎜⎜⎝

⎛+

−+≤

nr

NNr

r

NNr

mm

r

rr

r

N

N

r

r

ZSdm

ZSdm

mKrc

ZSdm

ZSdm

mKnmNrc

ZSdnN

nZSNdm

nKmNrc

rr

σσ

σσ

σ

σ

4434421

because by Theorem 1.1. 0),( 22

∞→

→n

N ZSdσ

Corollary 2.1. Let be independent and identically distributed life time of a system with mean zero, variance

,..., 21 TT02 >σ and

∞<rTE 1 for some 2≥r . If ( ) mTTS mm /...1

* ++= , then 0),(lim * =

∞→YSd mrm

(3)

where ),0(~ 2σNY .

The condition (3) implies or . In this

context, reliability , where represents the normal distribution function.

YSn

m

∞→

→* ( ) )(2

* ttSPn

n σΦ→≤

∞→

( ) 0 ),(1 2

* >∀Φ−→>∞→

tttSPn

n σΦ

References

[1] Barron A., Entropy and the central limit theorem, Ann. Probab. Vol.14, No. 1, pp. 336-342, 1986.

[2] Gnedenko, B.V. and Kolmogorov, A.N., Limit distribution for sums of independent random variables, Addison-Wesley, Reading, M.A., 1968.

[3] Johnson O.T. and Barron A., Fisher information inequalities and the central limit theorem, Probability Theory and Related Fields, Vol.129, No. 3, pp. 391-409, 2004.

267

Knowledge Based Organization 2008 International Conference [4] Luculescu, D., Fiabilitatea mecanismelor echipamentelor tehnice militare,

Editura Academiei Forţelor Aeriene “Henri Coanda”, Braşov. [4] Munteanu, B., The role of the Mallows distance in the Central Limit

Theorem, Sesiunea de Comunicări Ştiinţifice cu Patricipare Internaţională "Terra Dacica-Romania Mileniului Trei", Academia Forţelor Aeriene "Henri Coandă" Braşov, 2006. (on CD, ISSN:1453-0139), (Romanian).

[5] Petrov, V.V., Limit theorems of probability theory: sequence of independent random variables, Oxford Science Publication, Oxford, 1995.

[6] Prohorov, Y., On a local limit theorem for densities, Doklady Akad. Nauk SSSR (N.S.) Vol. 83, pp. 797-800, 1952.

268


THE OPTIMIZING OF THE MICROWAVES HYDRODISTILLATION OF FOLIUM MENTHAE

Asst.Prof. Danuţ Moşteanu, PhD

“ Nicolae Balcescu” Land Forces Academy, Sibiu, Romania, [email protected]

Abstract

This paper focuses on the hydrodistillation process efficiency fluctuation in order to optimize this process, depending of these two important parameters from the system: the power and the pressure. Therefore, we accomplished nine hydrodistillations with my oven installation, using Folium Menthae vegetal material. Out of the above represented data we notice the efficiency, with is a function with two variables (pressure and power) is increased along with the power’s increasing and the system pressure’s decreasing In order to optimize the process we focused on a mathematic model that minds the Polynomial Function of two variables of the kind. In order to solve the linear system with nine equations, we used Profesional Matchad programme that generated a matrix of the kind:

Keywords: volatile oils, hydrodistillation, microwaves, gas-

chromatographic. 1. Introduction. Ten carrying overs have been accomplished for the microwaves

hydrodistillation process. The oils obtained were mixed and the efficiency of the operation was the arithmetic average of the above mentioned processes

In order to accomplish a fair interpretation of the process, we focused on void space microwaves hydrodistillation, with variable parameters, generating power and pressure from the system, the power being 700-800W and the pressure 0.05-0.1MPa.

269


2. Experimental The efficiency of the hydrodistillation for all nine experiments,

depending on the established working conditions is represented in table 1

Table 1. The hydrodistillation efficiency depending on the working conditions Nr. Volatile oil η Power(W) P(MPa)

1 Folium Menthae 1.30 800 0. 100 2 Folium Menthae 1.24 750 0. 100 3 Folium Menthae 1.20 700 0.100 4 Folium Menthae 1.38 800 0.075 5 Folium Menthae 1.34 750 0.075 6 Folium Menthae 1.28 700 0.075 7 Folium Menthae 1.50 800 0.050 8 Folium Menthae 1.45 750 0.050 9 Folium Menthae 1.40 700 0.050

The graphic representation of the efficiency depending on the

pressure and the power is represented in figure 1, using Statistics programme, version 4.0., and obtaining the graphic in the variant 3D xyz

1.182 1.204 1.226 1.248 1.270 1.292 1.315 1.337 1.359 1.381 1.403 1.425 1.447 1.469 1.491 1.513

3D Surface Plot (8.STA 10v*10c)z = 0.898+0.001*x-4.067*y

Fig.1. The extraction efficiency graphic depending on the generator’s power

and the working pressure for these nine experiences.

270


2. Result and discussions. From the above represented graphics notice that the

hydrodistillation efficiency, if a parameter is constantly maintained is increased along with the decreasing of the pressure from the working place. We also notice that is we constantly maintain the other parameter, the pressure, the efficiency are increased along with the power’s increasing.

Out of the above represented data we notice the efficiency, with is a function with two variables (pressure and power) is increased along with the power’s increasing and the system pressure’s decreasing.

In order to optimize the process we focused on a mathematic model that minds the Polynomial Function of two variables of the kind

F(x,y) = a1x2y2+a2x2y+a3xy2+a4x2+a5y2+a6xy+a7x+a8y+a9=0 (1)

where: - function F(x, y) is the microwaves hydrodistillation efficiency, - x is the working pressure and - y is the microwaves generator power. In order to solve the linear system with nine equations, we used

2002 Profesional Matchad programme that generated a matrix of the kind:

M

4.9 10 3×

5.625 10 3×

6.4 10 3×

2.756 10 3×

3.164 10 3×

3.6 10 3×

1.225 10 3×

1.406 10 3×

1.6 10 3×

7

7.5

8

3.938

4.219

4.5

1.75

1.875

2

4.9 10 4×

5.625 10 4×

6.4 10 4×

3.675 10 4×

4.219 10 4×

4.8 10 4×

2.45 10 4×

2.813 10 4×

3.2 10 4×

0.01

0.01

0.01

5.625 10 3−×

5.625 10 3−×

5.625 10 3−×

2.5 10 3−×

2.5 10 3−×

2.5 10 3−×

49 10 4×

5.625 10 5×

64 10 4⋅

49 10 4×

5.625 10 5×

64 10 4⋅

49 10 4×

5.625 10 5×

64 10 4⋅

70

75

80

52.5

56.25

60

35

37.5

40

0.1

0.1

0.1

0.075

0.075

0.075

0.05

0.05

0.05

700

750

800

700

750

800

700

750

800

1

1

1

1

1

1

1

1

1

⎛⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎝

⎞

⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟

⎠

:=

(2)

271


v

1.20

1.24

1.30

1.28

1.34

1.38

1.40

1.45

1.50

⎛⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎝

⎞

⎟⎟⎟⎟⎟⎟⎟⎟⎟

⎠

:=

soln lsolve M v,( ):=

Solution

soln

8.571 10 3−×

12.721−

1.143− 10 3−×

4.723 10 3×

3.257 10 5−×

1.694

632.473−

0.047−

18.756

⎛⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎝

⎞⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟

⎠

=

(3) Replacing in the relation the obtained results, we have a function

F(x, y) of the kind: F(x,y) = 8.571x10-3x2y2 – 12.721 x2y – 1.143 x10-3xy2 + 4.723 x103x2 +

3.257 x10-5y2 + 1.694xy – 632.473x – 0.047y + 18,756 (4) In order to find out the minimum, maximum punctual or

stationary punctual, we derive function F(x, y) according to x and to y: 04730.632694.1446.92001143.0442.252017142.0 =−++−−= yxyxyxy

xf

ϕϕ (5)

0047.0694.100006514.0002286.0721.12017142.0 22 =−++−−= xyxyxyxxf

ϕϕ (6)

After solving the system with 2002 Professional Mathcad programme, the solutions are of the kind:

( ) ( )( )258885

080,

.y,xFind = that represented a point that can be

maximum, minimum or stationary point

272


In order to find this out, we also derive function F(x, y) according to x and to y wich leads to solving a system with the flexion.

451.357446.9442.252017142.02

2

=+−= xyyx

fϕϕ (7)

043.0446.9442.252017142.02

=+−= xyyxy

fϕϕ (8)

62

2

10*031.800006514.0002286.02017142.0 −−=+−= xxy

fϕϕ (9)

In order find out the nature of the obtained point, we calculate the flexion’s Iacob:

2

2

xf

ϕϕ

xyf

ϕϕ 2

357.451 0.043

=

xyf

ϕϕ 2

2

2

yf

ϕϕ 0.043 -8.031*10-6

We establish the sign of this determined, >0, We establish the second determined: 357.451*(8.031*10-6)-(0.043)2 = -4.72*10-3 The sign of the second determined is <0 . 3. Conclusions • The results theoretically established is that the point obtained is

a maximal, which is according to the experimental results • The efficiency of the hydrodistillation is greater in the case of

low pressure and greater power, so the values of 0.05MPa and 886W are the maximal accepted values for the value efficiency to be a maximum one.

• This hydrodistillation was not experimented because of the impossibility of regulating the power parameter, at the theoretically established value

273


References [1] Cornillot P. ,Horay P., Encyclopedie des medicines Naturelles,

[2] ochimice privind valorificarea

[3] tion of the

Editura Technique, Franţa, 1991 A. Mărculescu, Cercetări bi

principiilor active din Ch. Balsamita, Sesiune de comunicări ştiinţifice, Cluj Napoca, 1995. Mosteanu D., Teza de doctorat, Sibiu, Romania, 2005.

[4] Moşteanu D, The optimizing whith spline interpolamicrowaves hydrodistillation, Acta Universitatis Cibiniensis Chemia, vol.9, nr.2, 2005, Ed. Universităţii “Lucian Blaga”, Sibiu

274


THEORETICAL STUDIES ON THE FEASIBILITY OF NAVAL M.H.D INDUCTION PROPULSOR

Asst.Prof. Grozeanu Silvestru, PhD, TA. Pazara Tiberiu

Naval Academy „Mircea cel Bătrân“, Constanţa, România

Abstract A naval magnetohydrodynamic propulsor is a modern system which

succeeds to cancel a lot of other propulsor’s disadvantages. It reduces the energy losses produced by the propeller and its parts; further more, the noise produced by the cavitation it’s very much decreased. One of the characteristics of the M.H.D. propulsor is Q, the quality factor. This paper expresses the fact that the energetic ratio R (the ratio between dissipated energy and accumulated energy) and the quality factor Q define the same physical reality. Also, an easier calculus is proposed because the velocity in the drain is not uniform.

Keywords: propulsor, magnetohydrodynamic, quality factor, energetic ratio, seawater

A naval magnetohydrodynamic (M.H.D.) induction propulsor is, in fact, a linear induction machine using as indus seawater. In the seawater take place an interaction between a progressive magnetic field and the currents induced by the field, resulting an electromagnetic force. This force produces the water motion, and the water is evacuated through a nozzle, thus making a reactive propulsor. This kind of propulsion eliminates the propeller and its parts, reducing the energy losses associated with water swirling, and the noise made by cavitation. A silent navigation is essential in the case of a submarine being in the cruising ground.

275


Because the naval MHD propulsor is a linear induction machine, its efficiency is described using the quality factor Q, defined by Laithwaite as the ratio between magnetization reactance and indus resistance:

2

2

RL

Qω

= (1)

From this definition results:

h

fQ p

∆ρ

π

µτ= 02

p 0

(2)

where:τ is the polar step, µ is the permeability of vacuum, f is the supply frequency, ρ is resistivity, ∆ is indus thickness and h is the size of air-gap.

In case of an induction machine with seawater as indus, it is difficult to use eq. 1 because of obvious reasons; that’s why we assume a redefinition of quality factor on energetic considerations.

The machine takes energy from the source and a part of it is dissipated in the liquid environment as active energy, and the other part is stocked as reactive energy accumulated in the magnetic field from air-gap. Author considers that the machine will be much efficient as the ratio between dissipated energy and accumulated energy will be greater, and he propose to characterize the efficiency of naval MHD propulsor using the quantity „energetic ratio“ R. If the dissipated Joule energy is W and the magnetic field energy in the air-gap is W , this ratio is:

j

m

m

j

WW

R =

m

Author will demonstrate that the energetic ratio R and the quality factor Q represent the same physical reality. To do this, one will calculate the energiesW andW . The polyphased coil of inductor will generate in the air-gap a magnetic field with the aspect of progressive wave with intensity given by:

(3)

j

276


)sin(),(p

m

xtHtxHτπ

−ω=

fv ps τ= 2

0vvv sr −=

τt

(4)

This field travel with a synchronous velocity towards a fixed point:

(5) If indus moves with the velocity v, the relative velocity of

magnetic field towards indus will be: (6)

The progressive field covers a distance equal with a polar step during :

vvt

s

p

−

τ=τ

∫τ

=t

jj dttxPW0

),(

)(),(2 xdgtxudPj =

The infinitesimal Joule power dissipated in an indus element of length dx will be:

where u(x,t) is the voltage induced by the progressive field in indus element situated at x towards a fixed point placed at the extremity of a pole, at moment t, and g(x) is indus conductivity:

During this time, in indus will be dissipated a Joule energy having this expression:

(7)

(8)

(9)

2

1R

g = (10)

A stripe of indus with an infinitesimal length dx, and with a width equal with the width „a“ of indus, will have the next conductance:

a

dx

dxa

∆ρ

=

∆ρ

1dg = (11)

The ratio sρρ =∆

The value of induced voltage will be given by the law of electromagnetic induction:

is surface resistance [1, 2].

277


rBavt

txtxu −∂

Φ∂−=

),(),(

p

(12)

In a first stage we disregard the first element due to pulsation, and in this case the energy dissipated through Joule effect in an indus segment with length τ will be:

dxdtavtxH

Wt

o s

roj

p

∫ ∫τ τ

ρµ

=0

222

2),(

Replacing in (13) the expression of field intensity and making the integrations, we get:

(13)

s

rpmo

j

vaHW

ρτµ

=2

222

The magnetic energy is obtained integrating on air-gap volume the energy density of the magnetic field:

(14)

dxdydztxH

WrefierV

m ∫∫∫µ

=int 2

),(20 (15)

or:

dxxtdzdyH

Wa h

p

mm

p

)(sin2 0 0 0

22

0 ∫ ∫ ∫τ

τπ

−ωµ

= (16)

After integration:

4

20 haH

W pm

m

τµ= (17)

The value of energetic ratio R becomes:

hv

Rs

rp

ρτµ

= 02

Introducing the armature slip,

(18)

s

r

vv

s

s

vvv

s =−

=

and replacing the synchronous velocity (5), we obtain:

(19)

h

f psh

fsR

s

p

∆ρ

π

τ

In the moment of start-up, s = 1, and we get the ratio:

µπ=

πρ

τµπ=

20 2

22

22

0 (20)

278


π= 2QR

j mW

(in fact, relation (2) was deducted in the moment of start-up too).

The fact that R/Q is a non-dimensional constant, allow us to assert that both R and Q express the same physical reality: the efficiency of linear induction machine.

(21)

The fact that R≠Q can be a coincidence of the fact that pulse induced voltage wasn’t taken into account. So, quantity R can be used instead of Q, with the advantage of a clearer physical mean and a easier calculus.

In the case of the naval MHD propulsor, phenomena are getting complicated because the velocity in the flow channel is not uniform, and it has a maximum value on the channel axis and it is zero at contact with walls. To apply eq. (3) in the case of a propulsor with seawater, the energies W and must be calculated using eq. Maxwell – Hertz with respect to hydrodynamic processes expressed with eq. Navier - Stokes. The resulting differential equations systems are very complex and can be solved only using simplifying hypothesis. Such calculus is described by the author in paper [3], but the results couldn’t be verified experimentally. Because of this, he proposes another simpler calculus method which leads to similar conclusions. The armature slip s can be defined only locally, so it will be a function like this:

ss

s

vzxv

vzxvv

zxs ),(1),(

),( −=−

=

maxo

(22)

In the proximity of free surface and on the axis of MHD channel, velocity has a maximum value v and the armature slip is:

ss

s

vv

vvv

s max0max00 1−=

−=

The energy ratio R can be expressed using the mean value of armature slip:

∫ ∫+

−

a

a

h

dxdzzxsah 0

),(1=s

2 (24)

(23)

279


max0vVelocity value in the channel, depending on maximum

velocity , is calculated in [4].

2

2

max0 11

1),(

hz

chHa

chHachHx

vzxv−

−= (25)

Ha is Hartman’s number:

ησ

= aBHa 0

0B

(26)

is here the actual value of magnetic field induction:

220

0mm HB

Bµ

== (27)

ρ=σ

1 115 −−Ω≅τ m is the environment conductivity (for seawater )

and η is the dynamic viscosity. The factor 2

2

hz in (25) appeared

because one assumed in [4] the simplifying hypothesis that the depth distribution of velocities is very little influenced by the magnetic field.

Replacing in (24) the value of armature slip from (25), one get:

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛ −+=

HathHass 12

31

0 (28)

Replacing (28) in the expression of energy ratio (20), one get:

1s22

32

0

20

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛ −+

ρπ∆

Of course, this equation is not entirely correct because it was deduced using simplifying hypothesis, but offers some information regarding the phenomena produced by the irregularity of flowing velocity in the channel.

A first resulting information is that when the flowing velocity on channel axis becomes zero, then the armature slip is zero; but R isn’t zero like in machine with solid indus. In this case, although the inductive processes disappear on channel axis, they remain present elsewhere. The generating forces will differ from zero, causing water

τµπ=

HathHa

h

fR p (29)

280


drive. The value of energy ratio R is mainly determined by the element in front of eq. (29) which increase quadratic with polar step and linear with frequency. The main drawback of the naval MHD propulsor comes from the high value of seawater resistivity. For example:

710≅ρρ

cupru

apademare (30)

To have the same magnitude degree for energy ratio R in MHD propulsor like in an engine with copper indus, it is necessary to satisfy the eq.:

7

2

2

10)(

)(≅

ττ

cuprup

apademarep

ff

fp2τ

210 −≅τ p

1

(31)

Eq. (31) explains the fact that the experiments made with inductors designed after classical principals in which the metallic indus was replaced with a pipe with seawater, didn’t lead to concluding results.

Conclusions 1. The quality factor of a linear induction machine can be

expressed with the energetic ratio R, defined as the ratio between the active energy dissipated in indus and the inside energy of magnetic field.

2. A naval M.H.D. propulsor can be efficient only if the product is 10 7 times bigger than the one of a classic linear engine. For a

classic engine m and f = 50 Hz. A naval M.H.D. induction propulsor must be designed so ≅τ p m and f = 50 Hz. A scaling like this one brings some technical difficulties which can be solved.

281


References [1] Laithwaite, E.R., Induction machines for general purposes, Editura John

Wiley & Sons, New York, 1966. [2] Botez, D.; Cantemir, L.; Cristea, I., Propulsia navală neconvenţională,

Editura Muntenia, 1999. [3] Grozeanu, S., Asupra unor rapoarte energetice la maşina liniară cu indus

lichid, SIELMEC `97, Chişinău, 1997. [4] Grozeanu, S., Aspecte fundamentale ale propulsării apei de mare cu ajutorul

câmpurilor electrice şi magnetice, Sesiunea naţională de electrotehnică teoretică, Bucureşti, 1996.

282


ABOUT THE STUDY OF EKMAN CURRENTS ON THE

ROMANIAN BLACK SEA SHORE

PhD. Angela Muntean PhD. Mihai Bejan

Naval Academy „Mircea cel Bătrân” Constanta, Romania,

e-mail: [email protected] Abstract

The paper reveals some calculus results obtained about the principal elements of Ekman currents: magnitude, flowing direction for the ocean basin with finit depth. The local vorticity for those special conditions is calculated. Some results for the Romanian Black Sea shelf are discussed. Keywords: ocean water circulation, Ekman currents, vorticity 1. Introduction

Physical oceanography is a relative new sience field. It was developed mainly recently stimulated by the problem importance. Physical oceanography is the ocean study using physics, chemistry, biology, geology. Mathematics, through fluid mechanics, remains the main instrument for research and unification of all abouve mentioned fields. Mathematics used in physical oceanography is a high level one, imposed by problems difficulty. Oceanography takes into consideration the sea water study, with its physical properties (salinity, temperature, density) and also about its flow (the motion equations of real, viscous fluid). The temperature and salinity variations lead to a complement of the Navier-Stokes system with another three differential equations: the volume continuity equation and salinity and temperature difusion equations.

283


Sea water flow takes the form of waves and currents. For the Black Sea basin type, the general results obtained can be fragmentary used. This result from basin characteristics, with its weak communication with the Planetary Ocean and a wide continental slope in its north – west region. The Romanian Black Sea currents study requires a systematic and profound approach of existing conditions in this geographic area. It also requires the water flow conditions. The lack of currents systematic measurements on Romanian Black Sea makes quite impossible validation of theoretical results from motion equations. 2. Motion equation of wind – driven circulation

Fluid mechanics, geophysics, oceanography, use the coordinate system Oxyz with Ox to east, Oy to north and Oz up. Navier – Stokes equation is used for ocean water motion study. The water model is a viscous and incompressible fluid.

The motion equations considering friction are:

2 2 2

2 2 2

2 2 2

2 2 2

1 ;

1 ;

1 .

⎛ ⎞∂ ∂ ∂ ∂= − + + +⎜ ⎟∂ ∂ ∂ ∂⎝ ⎠

⎛ ⎞∂ ∂ ∂ ∂= − − + + +⎜ ⎟∂ ∂ ∂ ∂⎝ ⎠

∂= −

∂

h v

h v

du p u u uf v A Adt x x y z

dv p v v vf u A Adt y x y z

pgz

ρ

ρ

ρ

(1)

Considered forces are: Coriolis force, pressure, turbulent frictional force, gravity. For turbulent frictional terms, different values of eddy viscosity are used, particularly for vertical and horizontal directions ( ),v z hA A A . Last system equation has a single form due to hydrostatic assumption. This equation is an excellent approximation for motion at typical ocean speeds [3].

When the wind blows, a transfer of torque and energy occurs from wind to water. The wind friction generates a tangential force to basin surface. The major wind – driven circulation is a relatively steady – state motion. The wind – driven circulation occurs mainly in the upper few hundred meters. It is an horizontal circulation. The wind frictional stress acts on the sea surface.

284


This water motion downward through sea by friction induces deeper layers movement. The Coriolis force acts and changes the direction of motion. The upper layer, with opposite to the surface water velocity, is the Ekman layer.

Considering the continuity equation, the Boussinesq approximation is used. This allows using of the continuity equation for the incompressible fluid:

0u v wx y z∂ ∂ ∂

+ + =∂ ∂ ∂ . (2)

The general case of salinity and temperature variation are signifficant. Another three differential equations are added: salt conservation equation, temperature conservation equation and sea water state equation.

( )

2

2 2

2

2 2

,

∂ ∂+ ⋅∇ = Δ +

∂ ∂∂ ∂

+ ⋅∇ = Δ +∂ ∂=

r

r

SH SV

TH TV

S Sv S k S kt zT Tv T k T kt z

S Tρ ρ

(3)

Simplified form of the sea water state equation, is T ST Sρ α α= + . (4)

The new sea water state equation, used for sea water density calculus depends on salinity, temperature and water pressure. This is the International Equation of Sea Water State (IES 80), [3] with a polynomial form having 41 coefficients.

A common water ocean motions classification is: – thermohaline motion, produced by a signifficant density gradient in a limited area; the motion is generated by gravity action. Different densities are produced by temperature and/or salinity changes; – wind – driven circulation such as the major ocean circulations of the upper layers (Ekman currents), surface waves, upwelling etc. – tidal currents, horizontal motions, internal waves of tidal period; – tsunami or seismic sea waves motions produced by ocean bottom movements during undersea earthquakes; – turbulent motions resulting from velocity shear usually at water boundaries;

285

Knowledge Based Organization 2008 International Conference – internal waves, gravitational – gyroscopic waves, Rossby or planetary waves, etc [2]. 3. Results for a finite depth basin

In the open ocean, the wind stress is the most important cause of the gyral circulation in the upper layers. The general sea water circulation is a result of combined effects of the thermohaline circulation and the wind – driven ones. The wind influences the upper ocean layer only. It is the Ekman layer. The thickness of this layer depends on the wind speed and eddy friction of water. Two forces (wind stress and Coriolis) generates the sea water circulation as Ekman currents. If horizontal area is small enough the coordinate system horizontal plan is a tangent plan to the sphere. This is so called f – plan and the Coriolis coefficient can be adopted as a constant, from the area center.

Another assumption used in wind – driven circulation study is that a steady wind blows with constant speed and direction for a long time. The water is assumed homogeneous and the water density depends on pressure only, i. e. the flow is barotropic [2].

For a finite depth H basin, a stress τ wind, blowing up in a constant direction α angle (with the north direction), the motions equations are:

2

2

2

2

0 ;

0 .

∂= +

∂∂

= − +∂

z

z

uf v Az

vf u Az

(5)

Boundary conditions are: – at surface

,w z x w z yu vA Az z

ρ τ ρ τ∂ ∂= =

∂ ∂ for 0z = , (6a)

where wρ is the water density; – at the basin bottom

0u v= = , (6b) for z H= − .

286


The Gougenheim and Saint – Guilly method [1] can be used. We obtain a differential equation with constant coefficients. The Ekman currents velocity components are:

( ) ( )

( ) ( )

cos sinh 2 sin sin 22 4 4

cos 2 cosh 2w z

a H a Hu

f A a H a H

π πα ατρ

⎡ ⎤⎛ ⎞ ⎛ ⎞− − −⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎢ ⎥=+⎢ ⎥

⎢ ⎥⎣ ⎦

; (7a)

( ) ( )

( ) ( )

sin sinh 2 cos sin 22 4 4

cos 2 cosh 2w z

a H a Hv

f A a H a H

π πα ατρ

⎡ ⎤⎛ ⎞ ⎛ ⎞− + −⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎢ ⎥=+⎢ ⎥

⎢ ⎥⎣ ⎦

; (7b)

where 2 z

faA

= .

The Ekman current velocity magnitude is

( ) ( )2 2cos cos2

2 2cos cos

z z

w z

z z

f fh z H z HA A

Vf A f fh H H

A A

τρ

⎛ ⎞ ⎛ ⎞+ − +⎜ ⎟ ⎜ ⎟

⎝ ⎠ ⎝ ⎠=⋅ ⎛ ⎞ ⎛ ⎞

+⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

, (8)

and its direction is given by θ angle with north direction

( ) ( )

( ) ( )

cos sinh 2 sin sin 24 4tan

sin sinh 2 cos sin 24 4

a H a H

a H a H

π πα αθ

π πα α

⎛ ⎞ ⎛ ⎞− − −⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠=⎛ ⎞ ⎛ ⎞− + −⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

. (9)

For north – west wind direction, most frequently encountered

situation on the Romanian Black Sea coast, 54πα = the current

direction becomes

( )( )

sinh 2tan

sin 2a Ha H

θ = . (10)

The angle magnitude between wind and the surface current direction is

287


( )aHaHaHaH

2sin2sinh2sin2sinhtan

+−

=− αθ , (11)

and for z level

( ) tan tanh tantan1 tan tanhaH aH a z

aH aHθ α ⋅ −− =

+ ⋅ . (12)

All above relations are written for a depth H. If H is not constant, ( )yxHH ,= eddies and rings is possible to appear due to vorticity. The

vorticity is very important for the ocean water general circulation. At flat considered surface, the only conserved component of local vorticity is the vertical one, given by:

( )( )

02

12 cos 2 cosh 2

1 cos 2 cosh 2

sin cos4 4

sin 2 sinh 2

sin cos4 4

⎛ ⎞∂ ∂= − = ×⎜ ⎟∂ ∂ +⎝ ⎠

+ ×

⎡ ⎤⎛ ⎞ ⎛ ⎞∂ ∂ ∂ ∂⎛ ⎞ ⎛ ⎞× − − − + − − +⎢ ⎥⎜ ⎟ ⎜ ⎟⎜ ⎟ ⎜ ⎟∂ ∂ ∂ ∂⎝ ⎠ ⎝ ⎠⎝ ⎠ ⎝ ⎠⎣ ⎦+ ×

⎡ ⎤⎛ ⎞ ⎛ ⎞∂ ∂ ∂ ∂⎛ ⎞ ⎛ ⎞− − + + −⎢ ⎥⎜ ⎟ ⎜ ⎟⎜ ⎟ ⎜ ⎟∂ ∂ ∂ ∂⎝ ⎠ ⎝ ⎠⎝ ⎠ ⎝ ⎠⎣ ⎦

zaVv u

x y aH aH

aH aH

H H H Hy x y x

aH aH

H H H Hy x y x

ω

π πα α

π πα α .⎫⎪⎬⎪⎭

(13)

If 0>zω , the eddies are cyclonic and if 0<zω they are

anticyclonic. For north – west wind, 45πα = , with xsH = the eddy

type is given by the expression sign ( ) ( ) ( ) ( ) ( )asxasxasxasxxE 2sinh2sin2cosh2cos1 ⋅−⋅+= . (14)

For a large spectrum of values, ( ) 0>xE , the motion is cyclonic.

4. Conclusions

General results regarding sea water circulation can not be used for Romanian Black Sea coast circulation. This is because of continental

288

Knowledge Based Organization 2008 International Conference slope small depths. Finite depth basin circulation results are used for the study.

The Ekman currents velocity components, the velocity magnitude of Ekman currents direction were calculated. The vertical component of local vorticity was also calculated and some discussions regarding its expression were presented. Those discussions consists a starting point for further studies of Romanian Black Sea shore local vorticity.

References [1] Lacombe H., Cours d‘ oceanographie physique, Gautier-Villars, 1965. [2] Pickard G., Emery W. Descriptive Physical Oceanography. An Introduction. Butterworth-Heinemann. Oxford. 2003. [3] Pond S., Pickard G. Introductory Dynamical Oceanography. Butterworth-Heinemann. Oxford. 2003.

289


AN ERROR ANALYSIS FOR A QUADRATURE FORMULA

Asst.Prof. Ana Maria Acu*, PhD, JrTA. Alina Babos**

*“Lucian Blaga” University, Faculty of Sciences, Departament of Mathematics, Sibiu, Romania, [email protected],

**“Nicolae Balcescu” Land Forces Academy, Sibiu, Romania, [email protected]

Abstract

In this paper we derive a 2-point quadrature formula of open type. We show that there are situations when this formula has a better estimations of error than the well-known 2-point Gaussian quadrature rule.

Keywords: Quadrature rule, Error inequalities, Numerical

integration

1. Introduction Definition 1. It is called a quadrature formula or formula of

numerical integration, the following formula

],[][)()(][0

fRfAxdxffIR

m

imii∫ ∑

=+== λλ (1)

where mifi ,0],[ =λ are the punctual(local)information relating to function f, which to integrate with respect to the measure λd , miAi ,0, = are called the coefficients of the quadrature formula, and is the remainder term. ][ fRm

1

290




2

Lemma 1. [1]If +∞<<<∞− βα and w is a weight on ),( βα and

),(],[)()()( 1

1βα

β

αwn

n

kkk Lffrzfcdttwtf ∈+=∫ ∑

= (2)

then

+∞<<<−∞∈⎟⎠⎞

⎜⎝⎛

−−

−+= babaxabaxwxW ),,(,)()( αβα (3)

is a weight on (a,b) and

][)()()(1

FRz

abaFcabdxxWxF nk

n

kk

b

a+⎟

⎠

⎞⎜⎝

⎛−−

−+−−

= ∑∫= αβ

ααβ

(4)

where and),(1 baLF w∈

.)()(],[][~~

⎟⎟⎠

⎞⎜⎜⎝

⎛−−

−+=−−

=αβα

αβtabaFtFFrabFR nn (5)

The class of quadrature formulae of the interpolator type is obtained by integration of interpolation formulae. For example, the quadrature formulae of the Newton-Cotes type are the formulae of the interpolator type and they are obtained by integration of Lagrange interpolation formula, corresponding to integrable function .],[: Rbaf →

We shall enumerate some quadrature formulae of the Newton-Cotes type:

-the mid-point quadrature formula

,),(24

)(2

)()( "3

bafabbafabdxxfb

a

<<−

+⎟⎠⎞

⎜⎝⎛ +

−=∫ ξξ (6)

-the trapezoid quadrature formula

,),(12

)()]()([2

)( "3

bafabbfafabdxxfb

a

<<−

−+−

=∫ ξξ (7)

-Simpson’s quadrature formula

,),(2880

)()(2

4)(6

)( )4(5

bafabbfbafafabxfb

a

<<−

−⎥⎦

⎤⎢⎣

⎡ +⎟⎠⎞

⎜⎝⎛ +

+−

=∫ ξξ (8)

291


3

-Newton-Simsons’s quadrature formula

⎥⎦

⎤⎢⎣

⎡ +⎟⎠⎞

⎜⎝⎛ +

+⎟⎠⎞

⎜⎝⎛ +

+−

=∫ )(323

323)(

8)( bfbafbafafabxf

b

a

.),(6480

)( )4(5

bafab<<

−− ξξ (9)

In a recent years a number of authors have considered an error analysis for quadrature rules of Newton-Cotes. For example, they investigated the mid-point, trapezoid and Simson rules.

Denote by

)10(,)]([.,.],,[],[ 2)()1(12,

⎭⎬⎫

⎩⎨⎧

∞<∈= ∫−−b

a

nnnn dttfcontabsfbaCfbaH

,)]([ 2)(2

2

)( dttffb

a

nn ∫=

(11) where ].,[2, baf H n∈ In [5], N.Ujevic obtained the following quadrature formula

]1,1[,][)()()( 2,21

1−∈++=∫

−

HffRyfxfdttf (12)

where

,)(),,(][ "1

1dttftyxKfR ∫

−

= (13)

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

∈−

∈++

−∈+

=

].1,[,)1(21

),(,21

21

],,1[,)1(21

),,(

2

2

2

xtt

yxtxt

xtt

tyxK (14) (14)

292


4

Using the relation 2

"2),,(][ fyxKfR ⋅≤ and putting the

condition that min,),,( 22 →⋅yxK to obtain ,36 −=x respectively

the following quadrature formula:

],[)36()36()(1

1fRffdttf ++−+−=∫

−

(15)

.685

98][2

"ffR −≤ (16)

N.Ujevic compare this result with the 2-point Gauss formula, namely

],[33

33)( 1

1

1

fRffdttf +⎟⎟⎠

⎞⎜⎜⎝

⎛−⎟⎟

⎠

⎞⎜⎜⎝

⎛−=∫

−

(17)

,3274

13534][

2

"1 ffR +−≤ (18)

and show that the estimate (16) is better than the estimate (18).

2. Main results Theorem 1. If then we have ],1,1[2,3 −∈Hf

],[33

33)( 2

1

1fRffdttf +⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛−=∫

−

(19)

.85051483

4054][

2

)3(2 ffR +−≤ (20)

Proof. We seek a quadrature formula of the type

∫ ∫− −

=++−1

1

1

1

)3( ,)()()()()( dttftKyfxfdttf (21)

where We define .],1,1[, yxyx <−∈

293


5

,

],1,[,)(21)(

61

),(,)(21)(

61

],,1[,)(21)(

61

)(

32

23

1

32

23

1

32

23

1

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

∈+−+−

∈+−+−

−∈+−+−

=

ytcctct

yxtbbtbt

xtaatat

tK (22)

where are parameters which have to be determined. Integrating by parts, we obtain

3,2,1,,, ∈∈ iRcba iii

dttfcctct

dttfbbtbt

dttfaatatdttftK

y

y

x

x

)()(21)(

61

)()(21)(

61

)()(21)(

61)()(

)3(1

32

23

1

)3(3

22

31

)3(1

1 13

22

31

)3(

∫

∫

∫ ∫

⎥⎦⎤

⎢⎣⎡ +−+−+

⎥⎦⎤

⎢⎣⎡ +−+−+

⎥⎦⎤

⎢⎣⎡ +−+−=

− −

)1()1(21)1(

61

)()(21)(

61)(

21)(

61

)()(21)(

61)(

21)(

61

"3

22

31

"3

22

313

22

31

"3

22

313

22

31

−⎥⎦⎤

⎢⎣⎡ +−−+−−−

⎥⎦⎤

⎢⎣⎡ −−−−−+−+−+

⎥⎦⎤

⎢⎣⎡ −−−−−+−+−=

faaa

yfccycybbyby

xfbbxbxaaxax

)()(21)(

21

)()(21)(

21

)1()1(21)1(

61

'2

212

21

'2

212

21

"3

22

31

yfccybby

xfbbxaax

fccc

⎥⎦⎤

⎢⎣⎡ −−++−−+

⎥⎦⎤

⎢⎣⎡ −−++−−+

⎥⎦⎤

⎢⎣⎡ +−+−+

294


6

∫−

−−+−+

+−++−+

⎥⎦⎤

⎢⎣⎡ −+−−

−⎥⎦⎤

⎢⎣⎡ −−−−+

1

111

1111

'2

21

'2

21

.)()1()2()1(

)()()()(

)1(1)1(21

)1(1)1(21

dttffcfa

yfcbxfba

fcc

faa

We require that

,0)(21)(

61)(

21)(

61

32

23

132

23

1 =−−−−−+−+− bbxbxaaxax (23)

,0)(21)(

61)(

21)(

61

32

23

132

23

1 =−−−−−+−+− ccycybbyby (24)

,0)1(21)1(

61

32

23

1 =+−−+−− aaa (25)

,0)1(21)1(

61

32

23

1 =+−+− ccc (26)

,0)(21)(

21

22

122

1 =−−++−− bbxaax (27)

,0)(21)(

21

22

122

1 =−−++−− ccybby (28)

,01)1(21

22

1 =−−−− aa (29)

,01)1(21

22

1 =−+− cc (30)

,111 =+− ba (31) ,111 =+− cb (32)

.02,0

1

1

=−=c

a (33)

From the above relation we find

295


7

.33,

33,0,

,241,

241,

23,

21,2,1,0

32

3322111

=−==−==

===−====

yxbxyb

cacacba

Therefore, we have

],[33

33)( 2

1

1fRffdttf +⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛−=∫

−

(34)

∫−

−=1

1

)3(2 ,)(][ dtftKfR (35)

⎪⎪⎪⎪

⎩

⎪⎪⎪⎪

⎨

⎧

⎥⎦

⎤⎢⎣

⎡∈−+−

⎟⎟⎠

⎞⎜⎜⎝

⎛−∈−+

⎥⎦

⎤⎢⎣

⎡−−∈+++

=

1,33),133(

61

,33,

33),323(

61

,33,1),133(

61

)(

23

3

23

tttt

tttt

tttt

tK (36)

Since

dttttdttttK 233/3

3/3

2233/3

1

2

2)323(

361)133(

361

−+++++= ∫∫−

−

−

⎥⎦⎤

⎢⎣⎡ +−=−+−+ ∫ 1701

8235103142)133(

3611

3/3

223 dtttt

,85051483

4054

1701823

5103142

3)323(486133

91

61

13523

102061 2

+−=⎥⎦⎤

⎢⎣⎡ +−+

⎥⎦⎤

⎢⎣⎡ −+⎟

⎠⎞

⎜⎝⎛ −++

(37)

we obtain

2

)3(

2

)3(2

1

1

)3(2 8505

14834054)()(][ ffKdttftKfR +−=≤= ∫

− (38)

If we use Lemma 1 we obtain the quadrature formula on the interval [a,b]:

296


8

Theorem 2. If ],[2,3 baf H∈ , then

],[)]()([2

)(~

221 fRxfxfabdttfb

a

++−

=∫ (39)

where

.8505373

4051

24)(][

,23

32

,23

32

2

)3(2/7~

2

21

fabfR

abbaxabbax

+−−

≤

−⋅+

+=

−⋅−

+=

(40)

Now, we show that there are the situations when the estimates

(20) is better then the estimates (16) and (18).

Example 1. If , xxf ex +=)( ]1,1[−∈x , then

1208,01

2268

598][ 2

4

≅−

⋅⋅−≤e

efR (41)

1303,01

223

274

13534][ 2

4

1 ≅−

⋅⋅+−≤e

efR (42)

0325,01

22

85051483

4054][ 2

4

2 ≅−

⋅⋅+−≤e

efR (43)

Example 2. If 4

1)( 2 +=

xxf , ]1,1[−∈x , then

0079,0214687539246

2000168

598][ ≅⎟

⎠⎞

⎜⎝⎛+⋅⋅−≤ arctgfR (44)

0085,0214687539246

200013

274

13534][1 ≅⎟

⎠⎞

⎜⎝⎛+⋅⋅+−≤ arctgfR (45)

0028,02117226562501329179460

2800001

85051483

4054][2 ≅⎟

⎠⎞

⎜⎝⎛+⋅⋅+−≤ arctgfR (46)

Example 3. If ex

xxf3

)( = , ]1,1[−∈x , then

297


9

9338,0470624168

598][ 22 ≅+−⋅⋅−≤ − eefR (47)

0071,147062413

274

13534][ 22

1 ≅+−⋅⋅+−≤ − eefR (48)

.7326,0399813441

85051483

4054][ 22

2 ≅+−⋅⋅+−≤ − eefR (49)

References

[1] A.Lupaş, C.Manole, Capitole de Analiză Numerică, Universitatea din Sibiu,

Colecţia facultăţii de Ştiinţe-Seria Matematică 3, Sibiu, 1994. [2] F. Sofonea, Analiză numerică şi teoria aproximarii, Editura Universităţii din

Bucuresti, 2006. [3] N.Ujevic, Inequalities of Ostrowski-Gauss type and applications, Appl.

Math., 4, pp. 465-479, 2002. [4] N.Ujevic, A generalization of Ostrowski’s inequality and applications in

numerical integration, Appl. Math. Lett., 17, No.2, pp. 133-137, 2004. [5] N.Ujevic, Error inequalities for a quadrature formula of open type, Revista

Colombiana de Matematicas, Vol.37, pp. 93-105, 2003.

298


PARTICULARITIES OF THE ELECTRON BEAMS WITH A RECTAGULAR SECTION

Prof. Raceanu Serban, PhD, Prof. Raceanu Felicia

Nationall College ,,Anastasescu”, Rosiorii de Vede, [email protected]

Abstract Because the electrons are particles charged with electricity of the same

sign, forces of rejection appear among them proportional to the density of the beams. The main effects which appear as a result of the interaction between the electrons are: the dilatation of the electronic bean, the decrease of the potential in the area of action of the beam and the limitation of the electronic beam passing through the anode.

Keywords: electron, beam, potential, trajectory

We consider an electron beam moving in an equipotential space

along the axis Oz, with a constant speed oZ and which has its thickness 2yp much smaller that its width xp.

The movement equation of the peripherical electron of such a beam is:

poo

y2

2

xz2IE

dtyd

εη=η−= (1)

but 2o2

2

2

2z

dzyd

dtyd

≈ then we shal have:

299


23

apop3

oo2

2

Ux24

Ixz2

Idz

yd

εη=

εη=

(2)

The equation does not contain in the right term the transversal co-

ordinate, so we have the possibility to integrate. In the analyzed space, where the potential is constant, either a

paralel beam, or a convergent one can penetrate. Taking into consideration the case two, because it is the most

frequent, we have: o0z yy == ; γ≈γ=== tg

fy

dzdy

o

o0z (3)

where fo is the focal distance of the entrance lense, and γ is the convergence angle.

After the integration we obtain:

21

23

apo

2

o zAKzUx28

Izzyy +γ−=εη

+γ−=− (4)

where we used the notations:

23

ap

1Ux

IK = şi o28

1Aεη

=

When the beam is paralel to the axis Oz, the expression of the

trajectory of the peripherical electron gets the form:

21

23

apo

2

o zAKUx28

Izyy =εη

=− for γ = 0. (5)

300


Thus the dilatation of the paralel beam is done in function of z after a parabolic law, figure 1. The compression of the convergent beam depends of K1, which can be seen if in the preceding expression we take y = 0 we obtain:

1

1o2

AK2AKy4

z−γ−γ

= (6)

And the convergence of the electrons will take place only if z is real. 1o

2 AKy4≥γ (7)

When 1o2 AKy4=γ , we can still obtain the linear focus, from we

have the result of the expression of the maximum current:

23

a2o

o623

ao

26

p

maxmax1 U

fy105,10U

y105,10

xII −− ⋅=γ⋅== (8)

Fig. 1. The convergence of the electron beam in function of the tension.

301


A practical interest has the passing of an electron beam in a metal pipe with a rectangular section like in the figure 2.

Fig. 2. Electron beam with rectangular section.

The potentialon the transversal direction, in the inside of the electron beam can be determine from Poisson’s equation by integration.

23

po

12

2

Uy22

Idy

Ud

εη

= Poisson’s equation. (9)

With limit conditions: o0y UU == ; pyy UU

p=±= and 0

dydU

0y == . (10)

( )dyUd

yAI

dydU

dyd 2

3

p1

12

⋅=

where o1 22A εη= (11)

As a result after the first integration we have the relation:

302


( )21

o21

p1

1 UUyA

IdydU −

= (12)

After a new integration we obtain the law of modification of the

potential in the transversal section of the electron beam.

( ) ( ) yyA

IU2UUU34 2

1

p1

1o2

1

o

±=+− (13)

The signs plus and minus correspond to the positive and negative

values of the coordinate y. Because in the space between the metal pipe and the beam there

are not electric charges, the gradient of the potential will be constant from y = yp to y = yT.

pT

pT

yyUU

dydU

−−

= where UT = Ua (14)

At the surface of the beam at y = yp the values of the field

determined by the preceding expressions, must be equal. That is why we have:

1

yy

1UU

UU1yU

yAI

p

T

p

T21

p

op4

3p

21

p1

1

−

−=

−

− (15)

For the same surface with the potential pyy UU

p== the preceding

equation will have the form:

303


21

p23

p21

p1

1

p

o21

p

o yUyA

IUU21

UU1

34 −

±=

+

− (16)

Comparing the last two expressions the result is:

+

−

−+=

p

o

p

o

p

T

p

TUU21

UU11

yy

341

UU (17)

Substituting pe Up we obtaine:

23

p

o

p

o

p

T

2

p

o

p

o

p

T

T

23

T

15

UU21

UU11

yy

341

UU21

UU1

yy

yU

I1007,1

+

−

−+

+

−

=⋅ (18)

Fig. 3. The ratio of the potential on the axis of the beam as compared to that from the margin.

304


Fig. 4. The ratio of the potential at the limit of the beam as compared to that on

the pipe.

Analyzing the graphics in the figures 3 and 4 where we noted F = 1,07·105 T

23

T

1 yU

I we deduce that as the current in the

beam increases the potential will be modified both in the inside and at the margin of the electron beam.

For each correlation of the transversal dimensions of the beam

and of the pipe T

p

yy

there will be a maximum value of the function F,

corresponding to the maximum current I1max, for which the movement of the electron beam is stable.

This maximum value of the function is obtained in the following way: 0

UU

F

p

o

=

∂

∂ results:

305


+

−

−

=−

p

o

p

o

p

o

p

T

UU21

UU1

1UU2

231

yy (19)

+

−

+

−

=⋅=23

p

o

2

p

o

p

o

T

23

T

max15max

1UU4

UU21

UU1

yU

I1007,1F

23

p

o

p

o

p

o

1UU4

UU211

UU2

23

−

+

−

+ (20)

and 1UU4

UU

p

o

maxp

T −=

we obtain:

maxT

23

T6

p

maxmax1 F

yU1035,9

xII −⋅== (21)

The dependences of the expressions Fmax, maxFT

oUU

and maxFT

p

UU

of

the parameter T

p

yy

are shown in the graphic 5.

306


Fig. 5. The dependence of the ratio of the optimum potentials face to the

gemetry of the electron flood.

It results that in order topass a current as big as possible through the metal pipe, it is necessary that the beam have almost the same thickness as the pipe.

References

[1] Floriganţă, Gh.; Răceanu, Ş. - ,,Fenomene fizice la producerea şi utilizarea fasciculelor de electroni în tehnică’’, Editura SITECH, Craiova, 2004.

[2] Moлokobckий, C. И.; Cущob, A. Д. - Элektpohho – oпtичeckиe cиctemы

пpибopob cbepxbыcokиx чactot. Издateльctbo « ЭHEPГИЯ », Mockba, 1965.

[3] Boarnă, C.; Dehelean, D.; Arjoca, I. – Procedee neconvenţionale de sudare,

Ed. Facla, Timişoara, 1980. [4] Dehelean, D. – Sudarea cu fascicul de electroni, Studiu actual şi

perspectiva de dezvoltare, OID-I.C.M, SID 79-1988.

307


PARTICULARITIES OF THE ELECTRON BEAMS

WITH AN ANNULAR SECTION

Prof. Raceanu Serban, PhD, Prof. Raceanu Felicia

Nationall College ,,Anastasescu”, Rosiorii de Vede, [email protected]

Abstract The problem to determin the geometrical dimensions of the electrono-

optical systems considering imposed parameters of the electronic beam will take into consideration several factors, including the action of spatial charge, it is very complex and generally it is not solved analytically. Nevertheless, there exists a certain category of electrono-optical systems for whide a partial analytical solution can be found and as a result, the necessary calculation expressions can be found. To this category belong those electronic cannons, based on the laws of movement of electric loads in the simplest systems: in paralel, cylindrical and spherical plane.

Keywords: electron, beam, potential, trajectory

We consider an electron beam with an annular or tubular section, moving between the electrodes of a cylindrical condenser.

The dilatation of the tubular electron beam is analyzed starting from the movement of the marginal electron on the side surface. It is supposed that all the electrons have the same radial speed, and the axis of simetry of the condenser.

Comparing the tubular beam with the cylindrical beam we see that their dilatation is almost identical.

308


Still, we have to keep in mind that the density of the current in the tubular beam is bigger than in the case of the cylindrical and continuous beam.

Fig. 1. Electron beam with a tubular section.

In the hypothesis that the potential Uo in the section of the electron flood is constant (for the beams with very thin walls), the value of the current passing between the electrodes of the condenser is given by the expression:

21

0Io

Io

0Io

Io

max )U()U(

)U()U(1

233

II

⋅

−=

== (1)

309


where I is the intensity of the electronic current, Imax is the maximum value of the current, (U0)I is the potential in the section of the flood for a given current, and (U0)I=0 is the potential for the nule value of the electronic current.

Fig. 2. The dependence of the tension on the intensity of the current.

By analyzing the graphic, ( fig. 2 ) we see that when the current increses from zero to the maximum value, the potential in the beam decreases to 1/3 of the potential corresponding to the annulement of the current.

The maximum value of the current between the armaturs of the condenser is given by the formula:

max23

T

T

p

p

T

T

T

6max FU

rr

lgrr

lg

rr

lg104,6I

1

2

1

2

⋅⋅⋅= − (2)

where Fmax is a function that depends on the proportion of the

electrodes potentials 1

2

T

T

UU

and on the proportion of the capacities C1

şi C2.

310


1

2

1

T

T

T

p

21

2

rr

ln

rr

ln

CCC =+

(3)

- C1 is the capacitaty created between the electronic flood and the inner electrode; - C2 is the capacitaty created between the electronic flood and the outer electrode.

The way of avariation of the function Fmax in proportion with 1

2

T

T

UU

snd 21

2CC

C+

presents a great practical importance, as it makes the

correlation between the maximun intensity that passes through the condenser and the electric and geometric parameters of the system ( fig. 3 ).

Fig. 3. The dependance of the function Fmax on the tension and electric

capacity.

311


If the condenser misses the outer electrode

2Tr → ∞ the maximum current will have the value:

1

1

T

p

23

T6max

rr

lg

U1055,5I −⋅= (4)

And if it misses the inner electrode 0r

1T = , then the maximum current will be:

p

T

T6max

rr

lg

U1055,5I

2

2−⋅= (5)

The effect of thermic dispersion

The electrons emitted by thermic effect by the anode present an initial speed different from zero. The spedds of the electrons emitted by the cathode present a maxwellian distribution which is influenced by the temperature of the cathode.

Because of the initial spedds of the electrons occurs a limitation of the maximum current that can be transported by the electron beam.

The electrons emitted by the cathode are of two kinds: the non-thermal one, that have a neglectable initial spedd and the thermal ones that have an initial spedd non nule when they quit the metal. Around the trajectories of the non-thermal electrons are the trajectories of the thermal electrons. If the beam of non-thermal electrons have a focussing point, then it can transport a big density of current. In comparison with this beam, the one formed by the thermal electrons does not have a real focus, but they rather produce a focussing on a

312


difusion disc. In order to limit the transversal dimensions of the focus of the thermal electrons we must reduce the maximum density of the current in the beam.

Fig. 4. The effect of thermic dispersion.

In practice there are two situations: the first one when the beams

of thermal and non-thermal electrons have a certain angular dispersion, and the second when the beams are focussed, ( fig. 4 ). In the cas of the focussing of the beams, there must exist a certain relationship between the solid angle of emission of the thermal beam and the solid angle through which the same beam is focussed. Usually, the focussing conditions of the thermal beams are not compatible in whar concerns making a univoque image. The minimal dimension for an electron beam that presents the phenomenon of thermic dispersion is obtained when the temperature of the cathode is low and the acceleration tension between the cahode and the anode is high.

313


References

[1] Floriganţă, Gh.; Răceanu, Ş. - ,,Fenomene fizice la producerea şi utilizarea fasciculelor de electroni în tehnică’’, Editura SITECH, Craiova, 2004.

[2] Dehelean, D.; Răceanu, Ş. – ,,Tratat de tehnologii neconvenţionale-

Prelucrarea prin eroziune cu fascicul de electroni (vol.VI)”, Editura ARTPRESS, Timişoara, 2005.

[3] Moлokobckий, C. И.; Cущob, A. Д. - Элektpohho – oпtичeckиe cиctemы

пpибopob cbepxbыcokиx чactot. Издateльctbo « ЭHEPГИЯ », Mockba, 1965.

[4] Boarnă, C.; Dehelean, D.; Arjoca, I. – Procedee neconvenţionale de sudare,

Ed. Facla, Timişoara, 1980. [5] Dehelean, D. – Sudarea cu fascicul de electroni, Studiu actual şi

perspectiva de dezvoltare, OID-I.C.M, SID 79-1988.

314


FRACTALS DIMENSION, DESIGN METHODS AND MEASURING OF COMPLEXITY DEGREE

Daniela COSMA

Land Forces Academy “Nicolae Bălcescu”Sibiu România, [email protected]

Abstract The mathematics behind the images is often even prettier than the pictures

themselves! The branch of mathematics known as discrete dynamical systems1 theory include the study of iterative processes called fractals. The author’s goal in this article is to describe some easy-to-understand topics involving ideas from fractal geometry using the conclusions of the focus group organized with military students. We describe a method to generate discrete fractals by using numbers and demonstrate a simple experimental method to count the fractal dimension. The design space for fractal affords vast new opportunities in designs and applications many realized and proven beyond theory. Although a young extension in engineering, fractals have already made great strides in expanding design space for applications.

Keywords: fractals, dimension, method, complexity, design

1. What are Fractals? In the most generalized terms, a fractal demonstrates a limit. The

underlying principle of fractals is that a simple process that goes through infinitely much iteration becomes a very complex process. Fractals attempt to model the complex process by searching for the simple process underneath. [1]

Most fractals operate on the principle of a feedback loop. A

1 A dynamical system is a mapping of a metric space into itself. To lend some control to the ``generations,'' we require that our mapping be continuous

315



This leaved us with three triangles, each of which had dimensions

simple operation is carried out on a piece of data and then fed back in again. This process is repeated infinitely many times. The limit of the process produced is the fractal. Almost all fractals are at least partially self-similar2. An initial image is transformed by a set of affine transformations producing a new image. The new image is then transformed by the same affine transformations producing

another new image. Because the transformation is contractive3, the image will begin to converge to what is called an attractor. The outlining (Figure 1) indicates a few of the self-similarities of the object. The above method Expressed as an Iterated Function System will form a Sierpinski Gasket: Begin with an equilateral triangle Reduce the image by one-half. Make three copies of the reduced image. Align them in the shape of an equilateral triangle. Translate the top copy to the left above the lower-left copy. Go to step the second step.

Figure 1. Self-Similarity

Figure 2. Sierpinski Gasket

2. The chaos game experimented with military students The Sierpinski triangle S may also be constructed using a

deterministic rather than a random algorithm. To see this, we began with any triangle. Then we used the midpoints of each side as the vertices of a new triangle, which we then removed from the original.

2 An object is self-similar only if you can break the object down into an arbitrary number of small pieces, and each of those pieces is a replica of the entire structure. 3 Brings points closer together

316


Figure 3: JAVA Gallery of Interactive Geometry

Figure 3: A target for

exactly one-half the dimensions of the original triangle, and area exactly one-fourth of the original area. Now we iterated this process.

An interesting and valuable classroom

the chaos game

activity with the members of applied

colored one of the trian

find this winning strategy, and an eve

ogy project at Bost

dimension of a line, a square, and a cube.

mathematic scientific research group involved target-shooting. We had to draw one of the images in the deterministic construction of S on the board. Actually, we considered it is best to begin at a relatively low level, say the third stage (27 triangles remain). The students had to fix a seed, perhaps one of the 3 vertices. Then they gles that remained at the lowest stage of the

construction. This triangle was the target. Then the game was to move the seed into the interior of the target in the smallest number of moves. This was not a random game any longer: the students had to determine which rolls of the die put the seed in the target in the smallest number of rolls. (See Figure 3).There was no unique most efficient method to hit the target, as they found several alternatives. However, there are a least possible number of moves that cannot be

beaten. At first, students seemed to have a great deal of fun challenging one another with this game. Later they turned their attention to finding the algorithm that yields the most efficient solution. It was a wonderful exercise for students to try to n more beneficial exercise for

them to explain their strategy once they have found it. As part of the Dynamical Systems and Technolon University, there is a Java Applet available that we used to

play this interactively chaos game [5]. The intention was to make students be interested and connected with the study of fractals.

3. Fractal Dimension All students knew the

317


They

3.1 Degree of Complexity s us to measure the degree of

com

necessary to under

are one, two, and three respectively. And, we could measure the distance, area, and volume of those objects as well. However, what is the dimension of the inside of a kidney or the brain, and how do we measure their surface area? How about a piece of broccoli or cauliflower? This where problems we proposed to solve.

Fractal Dimension4 allowplexity by evaluating how fast our measurements increase or

decrease as our scale becomes larger or smaller. We discussed types of fractal dimension: self-similarity dimension and box-counting dimension and many different kinds of dimension not so easy to count. Some types included topological dimension5, Hausdorff6 dimension, and Euclidean dimension7 Students had to find the easy and fast way to solve the problem. It is important to note that not all types of dimension measurement give the same answer to a single problem and this fact surprised us. However, the dimension measurements we decided to use gived the same answer.

To explain the concept of fractal dimension, it was stand what we mean by dimension in the first place. Obviously,

a line has dimension 1, a plane dimension 2, and a cube dimension 3. But why is this? It is interesting to see students struggle to enunciate why these facts are true. They said that a line has dimension 1 because there is only 1 way to move on a line. Similarly, the plane has dimension 2 because there are 2 directions in which to move( backward and forward) and infinitely many in the plane. What the students really tired to say is there are 2 linearly independent

4 A measure of a geometric object that can take on fractional values. 5 Intuitively, the dimension of the space equals the number of real parameters necessary to describe different points in the space. 6 In topology and related branches of mathematics, a Hausdorff space, separated space or T2 space is a topological space in which distinct points have disjoint neighborhoods. Of the many separation axioms that can be imposed on a topological space, the "Hausdorff condition" (T2) is the most frequently used and discussed. It implies the uniqueness of limits of sequences, nets, and filters. Intuitively, the condition is illustrated by the pun that a space is Hausdorff if any two points can be "housed off" from each other by open sets.. 7 A dimension in Euclidian space. Euclidian dimensions are all orthogonal to each other (at right angles to each other) and refer to physical space with X, Y and Z components.

318

http://en.wikipedia.org/wiki/Topology

http://en.wikipedia.org/wiki/Mathematics

http://en.wikipedia.org/wiki/Topological_space

http://en.wikipedia.org/wiki/Neighbourhood_(mathematics)

http://en.wikipedia.org/wiki/Separation_axiom

http://en.wikipedia.org/wiki/Limit_(topology)

http://en.wikipedia.org/wiki/Limit_of_a_sequence

http://en.wikipedia.org/wiki/Net_(topology)

http://en.wikipedia.org/wiki/Filter_(topology)

http://en.wikipedia.org/wiki/Open_sets


Figure 4: The Hausdorff

directions in the plane. Another problem discussed: to determine the dimension of a curve in the plane or in three-dimensional space

without using integrals. An interesting debate occurred when we suggested that curves are actually one-dimensional. But they have 2 or 3 dimensions, the students objected.

So w

Dimension

hy are a line one-dimensional and the plane two-dimensional? Both of these

We can se a sq

objects are self-similar. We may break a line segment into 2 self-similar intervals, each with the same length, and each of which can be magnified by a factor of 2 to yield the original segment. In general, we can break a line segment into N self-similar pieces, each with magnification factor N. A square is different. uare into 4 self-similar sub-squares, and the

magnification factor here is 2. Clearly, the square may be broken into N2 self-similar copies of itself, each of which must be magnified by a factor of N to yield the original figure. See Figure 4. Finally, we can decompose a cube into N3 self-similar pieces, each of which has magnification factor N.For the square, we have N2 self-similar pieces, each with magnification factor N. So we can write

decompo

2log 2NDIMENTION = =log N

(1)

Similarly, the dimension of a cube is 3log 3NDIMENTION = =

log N(2)

Thus, the definitionobje

of the fractal dimension of a self-similar ct can be:

⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛

=

factorionmagnificat

piccssimilarofnumberDIMENTIONFRACTAL

log

log (3)

For the Sierpinski triangle consists of 3 self-similar pieces, each with magnification factor 2. So using(3) the fractal dimension is:

319


58,12log3log=

so the dimension of S is somewhere between 1 and 2, just as our ``eye'' is telling us. S also consists of 9 self-similar pieces with magnification factor 4.

58,14log9log==DIMENTIONFRACTAL

as before. Similarly, S breaks into 3N self-similar pieces with magnification factors 2N, so we again have

58,12log3log

== N

N

DIMENTIONFRACTAL

Fractal dimension is a measure of how "complicated" a self-similar figure is. In a rough sense, it measures "how many points" lie in a given set. A plane is "larger" than a line, while S sits somewhere in between these two sets.[2] DT-the dimention of element DE-the space dimention

Figure 5: Fractal dimension DF-object dimention

DEDFDT ≤< (4)

3.2 Dimension Measuring Algorithms, We can compare the proposed method with the well-known

techniques: (see Table 1) Self-Similarity Dimension

To Measure the Self-Similar Dimension, the picture must be self-similar. The power law holds and in this case is

1Da

s= (5)

Where a is the number of pieces, s is the reduction factor, and D is the self-similar dimension measure. For the Sierpinski Gasket, the original triangle is cut in half, and there are three pieces. Therefore a=3, s=0,5 and D=1.5850. We obtained the same result but the method seemed more difficult for students. Of particular interest for

320

http://pages.cs.wisc.edu/%7Eergreen/honors_thesis/gifs/sierpinski.gif


applications is the area of the holes and the circumference of the solid pieces. If the area of the original triangle is 1 then the total area removed after the N-th iteration is given by:

1

1 3 ... 13 4

kN

Nk

A ∞=

⎛ ⎞= ⎜ ⎟⎝ ⎠

∑ A = (6)

The circumference after the Nth iteration is given by:

1

1 31 ...3 4

kN

Nk

C ∞=

⎛ ⎞= + = ∞⎜ ⎟⎝ ⎠

∑ C (7)

Box-Counting Dimension To calculate the box-counting dimension, we placed the picture

on a grid. Then, count the number of blocks that the picture touches N(s). After we resized the grid we repeated the process. Ploted the values found on a graph where the x-axis is the log(s) and the y-axis is the log(N(s)) and drawing in the line of best fit finded the slope. The box-counting dimension measure is equal to the slope of that line. The Box-counting dimension is much more widely used than the self-similarity dimension since the box-counting dimension can measure pictures that are not self-similar.

Table 1 Fractal Dimension Calculation Methods

Fractal Dimension calculation methods for self-similar

patterns

Hurst Exponent calculation and Fractal Dimension calculation methods for self-affine

traces

Methods for estimation of Fractal Dimension of

size-frequency data

Box dimension Perimeter-area dimension Information dimension Mass dimension Ruler dimension

Rescaled range analysis Power-spectral analysis Roughness length Variogram Wavelets

Fragmentation dimension

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3.3 Fractal Analysis Software Thanks to computers, we can now generate and decode fractals

with graphical representations. One of the hot areas of research today seems to be Fractal Image Compression. Many web sites [3,4] devote themselves to discussions of it. The main disadvantage with Fractal Image Compression and Fractals in general is the computational power needed to encode and at times decode them. As personal computers become faster, we may begin to see mainstream programs that will fractally compress images.

BENOIT is fractal analysis software for Windows that enables the measurement of the fractal dimension and/or hurts exponent of

data sets using choice of method(s) for analysis of self-similar patterns and self-affine traces. A white noise filter (Fourier or Wavelet) and self-affine trace generator are two additional features in the computer program. It is a great resource for learning about fractal

methods and an analysis tool for researchers, and students. [5]

Figure 6: Fractal Analysis Software

4. Conclusion We now have ways of measuring things that were traditionally

meaningless or impossible to measure. The path is there as long as the limiting physics are understood and appreciated the design space for fractals affords vast new opportunities. [6] Finally, Fractal research is a fairly new field of interest.

References [1] Barnsley M., Fractals Everywhere, Academic Press Ltd., London (1988). [2] Mandelbrot B., A theory of factal sets, Macmilan Publisher 1975 [3] http://math.bu.edu/DYSYS/applets/ [4] www.complexity.ro – Introducere in geometria fractală, de Dr.Ing. Florin

Munteanu si Dr. Stefan Gheorghiu [5] http://www.geom.uiuc.edu/java/ [6] www.rfdesign.com – Fractal’s new era in military antenna design by Nathan

Cohen

322

http://math.bu.edu/DYSYS/applets/index.html

http://www.complexity.ro/

http://www.rfdesign.com/


SOLVING DIFFERENTIAL EQUATION WITH MATHEMATICA

Asst.Prof. Andrea Minda*, Asst.Prof. Mihaela Tomescu**, TA. Diana Stoica***

*“Eftimie Murgu” University, Resita, Romania, [email protected]**University of Petrosani, Romania, [email protected]

*** University “Politehnica” of Timişoara, The Faculty of Engineering of Hunedoara, [email protected]

Abstract The aim of this paper is to present some numerical methods for solving

differential equations: the Euler method, the second order Runge-Kutta formula and the fourth order Runge-Kutta formula. We give some examples in which we find the exact solutions and the numerical solutions to differential equations using Mathematica.

Keywords: differential equations, numerical methods,

mathematica. 1. Numerical Solution of Differential Equations We consider a general first order differential equation given in

the form ( ),x f x t=& (1)

with the initial condition ( )0 0x t x=

In the numerical method we want to obtain the solution in steps, at points where 0ix x i= + h 1,2,3,...i = .

323





Figure 1

How do we obtain the value of after the first step? Ideally, the

value should be obtained by integration of (1): x

( )1

0

1 0 ,t

t

x x f x t d= + ∫ t

]

(2)

But in this case the numerical value of the second term may not be exactly known, and we have to make some approximation to obtain

. The various methods of numerical solution of differential equations actually differ in the way this approximation is done.

1x

1.1 The Euler Method As a start, assume that the function remains constant through the

interval [ i.e. 0 1,t t ( ) ( )0 0, ,f x t f x t= for 0t t t1≤ ≤ . This gives ( )1 0 0 0,x x hf x t≈ +

Similarly, in for we have 1t t t≤ ≤ 2 ( )2 1 1 1,x x hf x t≈ + . Proceeding this way, we obtain, in general,

( )1 ,n n nx x hf x t+ ≈ + n This is known as the Euler method. One drawback of this method is that every step incurs some error

which tends to build up. Therefore in order to achieve a reasonable accuracy one has to take a very small value of h . This makes the computation very slow.

324


1.2. The Trapezoidal Rule In order to reduce the error, instead of approximating ( ),f x t by

( )0 0,f x t , one can approximate ( ),f x t by ( ) (0 0 1 11 , ,2

)f x t f x t+⎡ ⎤⎣ ⎦ .

This is called the trapezoidal rule, which obtains

( ) (1 0 0 0 1 1, ,2hx x )f x t f x t= + +⎡ ⎤⎣ ⎦

But then, we need to assume some approximate value of . A possible way of doing that is by assuming

1x( )1 0 0 0,x x hf x t= + .

Substituting this approximate value of and 1x 1 0t t h= + , we get

( )1 0 0 0 0 0,2hx x f f x hf t h= + + + +⎡ ⎤⎣ ⎦ (3)

where ( )0 0 , 0f f x t= If we now set

1 0k hf= ( )2 0 1 0,k hf x k t h= + +

then (3) becomes

( )1 0 1 212

x x k k= + +

This is also called the second order Runge-Kutta formula. It can be shown that the error per step in this method is of the order of

, which is considerably smaller than that in the Euler’s method. 3hFor further iterates, one has to obtain and for each step, and is calculated as

1k 2k

1nx +

( )1 112n nx x k k+ = + + 2

1.3. The Fourth Order Runge-Kutta Formula To obtain a greater degree of accuracy, one can approximate the

integral in (2) by more accurate expressions of ( ),f x t . This gives the Runge-Kutta formulae of higher orders. Of particular interest is the fourth-order Runge-Kutta formula

325


(1 0 1 2 3 41 2 26

x x k k k k= + + + + ) (4)

where ( )1 0 ,k hf x t= 0

2 0 1 01 1,2 2

k hf x k t h⎛ ⎞= + +⎜ ⎟⎝ ⎠

3 0 2 01 1,2 2

k hf x k t h⎛ ⎞= + +⎜ ⎟⎝ ⎠

( )4 0 3 0,k hf x k t h= + + It can be shown that in this formula the error is of the order of . 5h 2. Solving differential equations with Mathematica Mathematica has long been known for its powerful numerical,

graphical and symbolic computation capabilities. Now, more and more companies are discovering that the features that make it a standard for technical computing also help to make companies more efficient by increasing the speed of development and communications, cutting down on errors, and ensuring future compatibility.

Mathematica offers a complete, unified solution for symbolic math, numerical computation, equation solving, matrix manipulations, graphing, word processing, and presentation. There is only one system for students and faculty to learn, a system that can follow your students through their undergraduate and graduate engineering curricula, while still supporting even the most sophisticated faculty and industry research.

Mathematica is the world's most powerful global computation system. First released in 1988, it has had a profound effect on the way computers are used in technical and other fields. In 2007, after many years of development, a major reinvention of Mathematica once again transformed how computation is done.

Built into Mathematica is the world's largest collection of both numerical and symbolic equation solving capabilities—with many original algorithms, all automatically accessed through a small number of exceptionally powerful functions. Mathematica's symbolic

326

Knowledge Based Organization 2008 International Conference architecture allows both equations and their solutions to be conveniently given in symbolic form, and immediately integrated into computations and visualizations.

Solve— exact solutions to equations and systems NSolve — general numerical solutions to equations and systems FindRoot— numerically find local roots of equations DSolve — exact solutions to differential equations NDSolve — numerical solutions to differential equations RSolve — exact solutions to recurrence equations FindInstance— find particular solutions to equations and

inequalities Reduce— reduce equations and inequalities LinearSolve— solve linear systems in matrix form ContourPlot,ContourPlot3D— plot solution curves and

surfaces RegionPlot,RegionPlot3D— plot regions satisfied by

inequalities Mathematica's differential equation solvers DSolve and

NDSolve can handle a huge number of ordinary and partial differential equations analytically or numerically.

DSolve finds symbolic solutions for an ever increasing number of differential equations. These solutions are easier to verify, use, and recalculate than numeric solutions, and they provide a better understanding of the problems being studied.

The following are some implementation notes about the analytical differential equation solver DSolve.

DSolve can solve linear ordinary differential equations of any order with constant coefficients. It can also solve many linear equations up to second order with nonconstant coefficients.

DSolve includes general procedures that handle a large fraction of the nonlinear ordinary differential equations whose solutions are given in standard reference books.

NDSolve finds numerical solutions to differential equations. It automatically selects the optimal algorithm to use or lets you select it if you know it in advance. Mathematica alone uses interpolation

327

Knowledge Based Organization 2008 International Conference functions instead of simple lists of numbers to represent numerical solutions to differential equations, making it easy to reuse the results of Mathematica's NDSolve. All results can be used like any other function, namely, integrated, differentiated, or included in more-complex calculations.

Now lets go through a numerical example with to=0 for the

equation: ( ) ( ) ( )42 3 , 0ty t y t e y−′ + = 1=

which has an exact solution

( )2 45 3

2

t te ey t− −−

=

With the Runge-Kutta method the approximate solution is 1.04, the exact solution is 1.04. Note that this is much better than the approximation of 1.1 obtained with the Euler method.

The Mathematica sequence for finding the exact solution and the numerical solution of this equation is in figure 2.

Figure 2

In figure 3 we have the comparison of Euler, Runge-Kutta and

328

Knowledge Based Organization 2008 International Conference the exact solutions.

Figure 3

References [1] Braescu L., Balint S., Bonchis N., Kaslik E., Numerical Methods, West

University Publishing House, Timisoara,169 pg. (2007) [2] Maris S., Braescu L., Metode numerice-Probleme de Seminar si Lucrari de

Laborator, Editura Universitatii de Vest, Timisoara, 2008 [3] http://reference.wolfram.com/mathematica

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USE OF SIMILARITY THEORY ON TWO SCALES IN THE STUDY OF CAVITATION PHENOMENON GENERATED AT THE AXIAL PUMP ROTORS

Asst.Prof. Beazit Ali, PhD, Assoc.Prof. Adriana Sporis, PhD, student Levent Ali

“Mircea cel Batran” Naval Academy, [email protected]

Abstract By analysis the theoretic and experimental phenomenon it establish the

implicit function which describes this phenomenon. By application the Π teoreme for this implicit function it finds the criterion equation of phenomenon

Keywords: the similarity theory, the Π teoreme 1. Introduction As we know, the problems of cavitation were not solved yet

theoretically or practically on global plane, though many researches have made and are going to be made.

If we want to stady this phenomenon by using the similarity theory, first we must establish the physical magnitudes interfering in the evolution of cavitation phenomenon at the rotors of axial pumps.

2. The Criteron Equation for the Cavitation Phenomenon

Generated at the Axial Pump Rotors As a result of the theoretical and experimental researches

achieved till now, it is established that the cavitation phenomenon at the axial pump rotors has the following implicit function:

f( ρ , n, D, T, p∆ , h, d , g, max η , v, m, z ) = 0 (1)

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Knowledge Based Organization 2008 International Conference where: ρ - water density; n – rotor speed; D – rotor diameter; T – rotor thrust; p∆ = p – p blade pressure distribution, , p – water vaporizing pressure at respective temperature; h – immersion of rotor shaft to the water free surface; d – maximum thickness of rotor blade; g – gravitational acceleration, g = 9,81 m/s ;

v v

max2 η – water

kinematic viscosity; v – current velocity through the rotor disk (plate); m – mass of water-dissolued air; z – number of rotor blade.

The physical magnitudes of this implicit function represent the physical magnitudes on which this phenomenon depends. To apply Π theorem to this implicit function, first, we write the dimensional matrix of variables (the number of rotor blades = is the same both the model and the prototype).

011200220101010001100101111111103

max

−−−−−−

−−−∆

sKgm

mvgdhpTDn ηρ

(2)

from where we obtain the equation system:

02220

03

1098542

119541

1098765431

=−−−−−−=++++

=+−+++−++−

xxxxxxxxxxx

xxxxxxxxx (3)

We choose the main unknowns of the system:

11109876543

1098542

119541

3224222

xxxxxxxxxxxxxxx

xxxxx

−−−−−−−−=−−−−−=

−−−−= (4)

The system (3) being undetermined for solving, we apply Cramer’s rule and obtain the matrix of solutions under the following form:

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1000000030101000000110001000002110001000012000001000100000001001000000001022100000001421

8

7

6

5

4

3

2

1

max

−−Π−−Π−−−Π−−Π−Π−Π−−−Π−−−Π

∆ mvgdhpTDn ηρ

(5)

From the matrix of solutions we obtain the following similarity criteria:

3872625

max43222421

;;;

;;;;

Dm

nDv

nDDng

Dd

Dh

Dnpp

DnT v

ρρηρµ

=Π=Π=Π=Π

=Π=Π−

=Π=Π

(6)

z = constant The criterion equation in which we shall include the number of

blades z too will be of the following form: Φ ( 22Dn

Tρ

, 22Dnpp v

ρ− ,

Dh ,

Ddmax ,

dng2 , 2nDρ

η , nDv , 3D

mρ

, z ) = 0 (7)

If we observe the geometrical similarity on a single scale, it is possible that the thickness of the rotor blade and the immersion of its shaft to be very much reduced, so that it is possible that the model can’t be used for determinations the results of tests on that model having many errors.

For that reason, it is more advantageous and reliable to achieve the distorted rotor model (on two scales) allowing the obtaining of some results which are closer to the reality, when they are transposed to the rotor prototype.

We can determine the law of the model in the case of similarity on two scales, choosing arbitrarily the scale of the lengths parallel with the rotor diameter and the scale of the lengths parallel with the blade thickness.

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3. Conclusion We notice that not all the similarity criteria have the same

importance in evolution of the cavitation process at the propellers. The most important criterion, with a decisive role in the cavitation process, is that in which the vaporizing pressure interferes pv

References

[1] Anton, A., Cavitaţia, vol I şi II, Editura Academiei, Bucureşti, 1980. [2] Ali, B., Hidrodinamica aripii de mică anvergură, controlul cavitaţiei şi

stabilitatea navei cu aripi imerse, Referat II , Galaţi, 1996. [3] Vasilescu, Al., A., Analiză dimensională şi teoria similitudinii, Editura

Academiei, Bucureşti, 1969.

333


HIGH PERFORMANCE CONTROLLABLE PITCH PROPELLERS FOR LOW ACOUSTIC SIGNATURES

Asst.Prof. Beazit Ali, PhD, Assoc.Prof. Adriana Sporis, PhD, stud. Levent Ali

“Mircea cel Batran” Naval Academy, [email protected]

Abstract In order to maximize the design of the Controllable Pitch Propellers for

low acoustic signature is necessary to analyse more aspects the general features of propeller and the effect of air emission, the effect of cavitation by using different computer programme which can stimulate a lot of parameters developed on the model on scale and on the full scale model. The result made possible a new way for improvement of design techniques to obtain more and more less noisly Controllable Pitch Propellers

Keywords: Ship propulsion, propeller, cavitation 1. Introduction. General Features of the Controllable Pitch propellers system VA

TECH Escher Wyss has delivered or has on order complete propeller systems for five different MEKO® Class Frigates for four different end users. All of these systems are equipped with shaft line mounted actuating units. Four of these sets have an air emission system with the air inlet box being located at the forward end of the gearbox.

Figure 1: Escher Wyss Controllable Pitch Propellers with calculated

streamlines

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2. Blade Bearing System Escher Wyss Controllable Pitch Propellers are commonly known

for their unique type of blade fastening. The Escher Wyss hubs of the trunnion bearing type with blades and trunnions cast in one piece are especially applicable for naval vessels, see Figure 2 (below). This design delivers the following beneficial features:

- By eliminating blade bolts, the flow in the blade palm area is smooth which reduces the vortex formation and delays cavitation inception. With bolted-on blades, the bolt heads and the pockets in the blade root constitute flow obstacles which can contribute to early inception of cavitation.

- The number of propeller blades can be increased up to seven with an acceptable low hub ratio (approx. 32%).

3. Hub Shape The hub shape has been developed in order to achieve a minimum

hub resistance and a high inception speed of the hub vortex cavitation. Cavitation predictions in the model scale as well as full scale viewings confirmed that, for this type of hub shape, hub vortex cavitation is not present during a straight ahead course. During the full scale viewings, such vortex cavitation could only be observed at extreme propeller loadings in the manoeuvring mode.

4. Air Emission Emitting air (see Figure 2), can reduce or eliminate the increase of

the noise levels associated with cavitation inception at the higher frequency range. The emission of air is also effective at ship speeds with developed cavitation. The large number of delivered propellers with air emission systems for naval vessels is proof that the benefits of this system are highly appreciated. Up to date, any detrimental impact of the air emission on the propeller efficiency could not be verified during the sea trials (and is impossible to detect in model scale). No erosion damages around the blade air emission holes have ever been discovered.

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Figure 2: Air emission test with water

5. Development of the Blade Design By making immediate use of the rapid progress in computer

technology of the past 25 years, VA TECH Escher Wyss was able to optimize the blade designs on computer screens. At present VA TECH Escher Wyss is able to adapt a blade design completely to the given design conditions by calculation, prior to verifying the design by model tests. The major progress consists of the ability to control the blade design's cavitation behaviour and thus increase the cavitation free ship's speed without sacrificing propeller efficiency.

However, although the present design tools, as well as the analytical procedures enable the propeller designer to optimize the blade geometry, the hull and appendages ahead of the propeller regulate the limits for a successful blade design. Therefore, if a quiet propeller is required, the ship's hull and appendages must be appropriately designed and fabricated.

6. Wake Data Processing. 3D-Wake Survey For the adaptation of the blade design to the given wake field, an

experimental 3D-Wake Survey is necessary. The blade designer is able to optimize the blade geometry locally after access to all three velocity components in the propeller plane.

Usually, navy vessels are twin screw vessels whose wake field typically looks like the one illustrated in Figure 3. The wake survey report of the model basin comprises, as a standard, the plot of the transversal components (top plate) as well as the axial velocity

336

Knowledge Based Organization 2008 International Conference isolines (bottom plate). The wake peak due to the propeller shaft is clearly visible as well as the spikes created by the struts. An illustrative presentation of the "wake peak" shows the mountain in the middle of the plot where the region of reduced axial velocities are readily visible as a groove.

Figure 3: Typical 3D wake of a twin screw navy vessel

7. Wake Adaption of the Blade Design. Blade Tip and Blade

Surface The wake adaptation of a blade design consists of step by step

modifications to the blade geometry and to the subsequent cavitation calculations.Though VA TECH Escher Wyss has developed strategies for the wake adaptation of ship propellers, a sizable number of calculation loops remain necessary to reach a satisfactory status.

When considering blade geometry, the cavity volumes and cavitation extension are calculated with the program system PUF-3A, which was originally developed by the M.I.T.,Cambridge, Massachusetts and has been continuously updated by the University of Texas in Austin, USA. PUF-3A calculates - for a given wake field and blade geometry - the surface pressure on a large number of panels on the blade surface, and, based on sophisticated criteria (not only the vapour pressure), determines whether cavitation will take place at this panel. From the surface pressures on the suction side and pressure side, mean values as well as the fluctuations of the forces and moments for the cavitating and non-cavitating case are computed.

The present design-tool PUF-3A is based on a potential theory technique, which does not allow the prediction of the tip vortex structure and the complex processes in the vortex.

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8. Developed Cavitation The large differences between the calculated developed cavitation

and the calculated incipient cavitation in the chordwise extension, as well as in the cavity volumes, require different post-processing techniques. In order to visualize the developed cavitation, VA TECH Escher Wyss has implemented a rendering program which superimposes the calculated cavitation as well as the surface pressures on the three-dimensional blade surface, as illustrated in Figure 4.

With decreasing pressure the colour changes from blue to red. The suction side sheet cavitation is depicted in pink in order to distinguish between the regions of low pressure from those regions in which the program predicts cavitation. On the back, where a low pressure area has been calculated, the cavitation inception criterion of the program is not satisfied. Nevertheless, by experience, mid-chord bubble cavitation has to be expected.

Figure 4: Calculated developed cavitation (PUF-3A)

9. Incipient Cavitation Cavitation inception is crucial for the noise signature of a vessel's

propeller, and for this necessitates a precise determination of the first indication of cavitation. In order to depict the few cavitating panels which have only a small chord wise extension of cavitation, a specific kind of presentation is needed. Figure 5 shows a typical plot of incipient cavitation that is characterized by a small angular sector in the vicinity of the top position of the blade where the cavitation occurs, and by the restricted radial extension.

The colour scale facilitates the identification of the chord wise extension of the cavitation sheet. In comparing the cavitation

338

Knowledge Based Organization 2008 International Conference extension as calculated in this manner with full scale viewings, it has been found that calculated sheet lengths up to 1% chord length seem to vanish in an uncertainty range, and that cavitation sheet lengths only greater than 1% chord length are significant. PUF-3A is not able to calculate tip vortices.This appears to be an important disadvantage. However, previous studies showed, that the presence of a tip vortex agreed with the program's indication of a sheet cavitation which might be sufficient for a practical approach.

Figure 5: Calculated incipient cavitation (PUF-3A)

10. Blade Root In the past, interest has been focused on the flow around the blade

tip since the cavitation inception used to first occur here. Meanwhile, the analysis tools and countermeasures have been developed in such a way that the blade tip does not necessarily constitute the inception point of cavitation on the propeller.In some cases, cavitation inception has been observed earlier on the root (or even on the appendages).

Therefore, the knowledge of flow phenomena in the root region is of interest, in particular if the blades are fastened with blade bolts.

11. Simulation of Cavitating Tip Vortex The simulation of three dimensional tip vortex structures at

Controllable Pitch Propellers becomes significantly more stringent when dealing with noise target requirements. The induced vortex from the blade tip is strongly dependent on friction and turbulence structures. The RANSE-solver FENFLOSS (Finite Element based Numerical Flow Simulation System) has been developed by the University of Stuttgart's Institute of Fluid Mechanics and Hydraulic

339

Knowledge Based Organization 2008 International Conference Machinery. FENFLOSS is able to calculate the three dimensional, turbulent flow under consideration of the friction around the propeller. Both blades have been calculated with FENFLOSS for three different operation points each simulating the wake peak, the mean wake and the minimum wake. Furthermore, they are characterized by a small rake and a reduced pitch near to the blade tip. The skew is adapted to the wake.

One blade is meshed with roughly one million calculation elements for simulations. The wall shear stresses are calculated with a logarithmic wall function. The wake ahead of the propeller is simplified as a homogeneous boundary condition. The influence of different operation points is realized through various axial velocities at the inlet of the calculation model. A radial constant axial velocity is thus defined as an inflow boundary condition. Additionally a degree of turbulence of 5% is applied at the inlet. A natural boundary condition dp/dx=0 is defined at the outlet. A symmetrical boundary condition is applied for the surface of the calculation model.

Three different wake fractions are compared for the studied blade geometry. Figure 6 shows a comparison of streamlines around the tip of each propeller blade. It seems that the variant two can hamper the tip vortex rolling up.

Figure 6 . Comparison of two geometrical variations of blade tip with

calculated streamlines (FENFLOSS) However, the evaluation of the pressure distribution behind the

propellers illustrates that the low pressure peak for both geometries is quite similar, as to be seen in Figure 7.

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Figure 7: Comparison of the calculated pressure distribution behind the

propellers for both geometries (FENFLOSS) 12. Conclusions Due to the strong impact of the hull and appendages on the

propeller performance, the given wake field constitutes the limits for a successful blade design. Therefore, the ship's hull and appendages must be designed and fabricated appropriately if a quiet propeller is required. By means of a M.I.T. program system, the cavity volumes and the surface pressures of a given blade geometry can be calculated and optimized in several design loops.

However, the analysis shows clearly that the variation and calculation of a propeller with modern RANS-solver is possible and leads to a new way of propeller design.

References

[1] Cristian Bauer, High Performance CP Propellers for acoustic signatures , VA TECH Escher Wyss.

[2] M. Abdel- Maksoud, H-J. Heinke, Investigation of the Viscous Flow around Modern Propultion System, 95-th general meeting of the German Society for Maritime Technology, Hamburg, 2000.

[3] M. Abdel- Maksoud, Rieck K., Calculation of the pressure reduction in the tip vortex core of a skew propeller in model and full scale , 4-th Numerical Towning Tank Symposiym (Nu TTS 01) Hamburg, Germany, 2001

341


ABOUT NUMERICAL SOLUTIONS AND CONDITIONING OF LYAPUNOV AND SYLVESTER

TYPE EQUATIONS

Asst.Prof. Ligia-Adriana Sporiş, PhD, Assoc.Prof.Eng. Beazit Ali, PhD

Naval Academy “Mircea cel Bătrân”, Constanţa, România

Abstract

In this note, we discuss about a few aspects of perturbation theory and next, develop some computational methods for Lyapunov and Sylvester type Equations.

1. Introduction The Lyapunov Equations:

CXAXA T =+ (1) and its dual:

CXAAX T =+ (2) arise in stability and robust, stability analyses, in computing – nom, in the implementation of some iterative methods for solving algebraic Riccati equations.

2H

The equations (1) and (2) constitue special cases of another classical matrix equation know as the Sylvester equation:

CBXXA =+ (3) which arise in a wide variety of applications: the construction of the solutions in the eigenvalue assignment problems, the computing of numerical solutions of elliptic boundary values problems, the block diagonalization of a matrix by a similarity transformation.

342


2. Some remarks about: the existence and the uniqueness of the solutions and the perturbation analysis for these equations

For the matrix equations (1) and (3), assume that: .RC,RB,RA nmmmnn ××× ∈∈∈

Theorem 1: Let ( ) n1 ,,A λλ=Τ K and ( ) n1 ,,B µµ=Τ K , the sets of the eigenvalues of A and respective, B. The Sylvester equation (3) has a unique solution iff ( ) ( ) 0BTAT =−I (4)

Corollary 2: The Lyapunov equation (1) has a unique solution iff ( ) n,1j,i,0ji =∀≠λ+λ (5).

We know that: if A is a stable matrix and C be symmetric, positive definite or semipositive definite, the unique solution x of Lyapunov equation is given by:

( ) dteCeX At

0

tAT

−= ∫∞

(6)

Note that: (6) requires computations of the matrix exponential and

evaluation of a matrix integral; there are some obvious computational difficulties with these computations.

Ate

Others analytical methods include finite and infinite series methods. For example, consider X, solution of Lyapunov equation:

using series method (Jameson - 1968): CXAXA T =+

First, we consider: ( ) ( ) n1nn

nA c,cAIdetP ++λ+λ=−λ=λ − K (7) Then, we define the sequence of matrices: ( )kkQ :

AQAAQQAQ,CQ,0Q 2kT

1k1kT

k01 −−−− +−=== (8) So, ( ) ( ) ( )[ ] ( )( )0n

n1nn

1

nnn1nTnT Qc1Q,cQIc1A,cAX −++−−++−= −

−−KK (9)

But the numerical experiments show that for random matrices of size greater than 14, the errors are almost as large as the solution themselves.

In the above results, it has given informations only for the uniqueness of the solutions. However, there are certain situations (i.e. control problems: EVA problems, for example) that require nonsingular of full-rank solutions of (1).

Next, we present some results of perturbation analysis for the matrix equations (1) and (3), important in assessing the accuracy of the solutions obtained by numerical algorithms.

343


Theorem 3: Let the Sylvester equation (3) and we presume that it has a unique solution X, for C ≠ 0 and ( ) 2

1A,BsepBA

FF ≤−

+µ (10)

where ( )

F

F

0X XBXAX

minB,Asep−

=≠

∆

(11)Then, we have:

( )A,BsepBA

4XX

FF

F

F

−

+µ≤

∆ (12)

where: µ is such as: µ≤

∆µ≤

∆µ≤

∆

F

F

F

F

F

F

CC

,BB

,AA ( X,C,B,A ∆∆∆∆ are the perturbations

in the matrices A, B, C, X). Corollary 4: Let X be the unique solution of the Lyapunov

equation (1) for C ≠ 0 and , the unique solution of perturbed problem:

X~

( ) ( ) CX~AAAAX~ T =∆++∆+ (13) where

FFAA µ≤∆ (14)

Assuming that:

( ) 41

A,AsepA

TF <α=−

µ (15)

we have:

( )A,AsepA

8XX

TF

F

F

−µ≤

∆ (16)

3. Some numerical methods for the Lyapunov an the Sylvester

Equations We present some of the most interesting numerical methods for

the matrix equations (1) and (3). 3.1. The Schur method for the Lyapunov equation Proposed by Bartels and Stewart, this method, based on the

reduction of AT to RSF, is now widely used as an effective computational method.

Next, we shortly describe this method:

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Step 1: Reduction of problem: Let , the RSF of AT. UAUR TT=

(1) ⇔ DRYYR T =+ (17) where (18) XUUY,CUUD,UAUR TTTT ===

Step 2: Solution of the Reduced Problem: Let and ( ) ( n1n1 d,,dD,y,,yY KK == ) ( )ijrR = .

Assume that the columns: n1k yy ÷+ have been computed and consider the following two cases:

Case 1: 0r 1k,k =− : is determined by solving the system: ky

( ) ∑+=

−=+n

1kjjkjkkkk yrdyIrR (19)

Case 2: for some k: and are simultaneously compute by solving the linear system:

0r 1k,k ≠− 1ky − ky

n2n2 ×

( ) ( ) ( ) ( )∑+=

−−−

−−−−− −=⎟⎟

⎠

⎞⎜⎜⎝

⎛+

n

1kjjkjjj,1kk1k

k,kk,1k

1k,k1k,1kk1kk1k yr,yrd,d

rrrr

y,yy,yR (20)

Step 3: Recovery of the solution of original problem: TUYUX = (21)

3.2. Another numerical method for a Lyapunov Type Equation If we consider the equation:

CCXAXA TT −=+ (22) where nnRA ×∈ is stable (i.e. all the eigenvalues of A have negative

real parts) and , , symmetric positive semidefinite solution. nrRC ×∈ ( )X!∃

Thus, such a solution X has a Cholesky factorization, YYX T= (23)

where Y is upper-triangular. In several applications, it is needed only Y but not X, explicitly. We describe below a procedure, due to Hammarling, for finding

Y without explicitly computing X and without forming the matrix CTC.

Substituting in: , we obtain: YYX T= CCXAXA TT −=+

( ) ( ) CCYYAAYY TTTT −=+ (24) Let: (25), the upper RSF (U, orthogonal); , the

QR factorization of CU. AUUS T= QRCU =

Then, we have: ( ) ( )[ ] ( ) ( )[ ] RRSYUYUYUYUS TTTT −=+ (25) where:

( ) CUCURR TT = (26)

345


We partition:

⎟⎟⎠

⎞⎜⎜⎝

⎛=⎟⎟

⎠

⎞⎜⎜⎝

⎛=⎟⎟

⎠

⎞⎜⎜⎝

⎛==

1

T11

1

T11

1

T11

S0ss

S,R0rr

R,Y0y~y~

YUY~ (27)

where: s11 is a scalar (a real eigenvalue in RSF, S) or a matrix corresponding to a pair of complex conjugate eigenvalues in S.

22×

Then, we obtain:

( ) ( ) 11T

11T1111

T1111

T11

T11 rrsy~y~y~y~s −=+ (28)

( ) T11

1111111

T1 y~sry~sy~y~y~S −α−=+ − (29) ( ) ( ) 1

T1

T11

T11

T1

T1 R~R~SYYYYS −=+ (30)

where: 1

1111y~r −=α (31) T

1T11

T1 uuRRRR~ += (32)

Ty~ru α−= (33) Note that: - is easily computed from the QR factorization

(34) 1R~

11

T

R~Q~Ru

=⎟⎟⎠

⎞⎜⎜⎝

⎛

- (30) is of the same form as the original equation (24), but is of smaller order. This is the key observation.

111 R~,Y,S can now be portioned further as in(27), and the noble process can be repeated, until is completely determined. y~

Once is obtained, Y of the QR / factorization, y~ ~

TUY~yQ = (35) will be an upper triangular matrix that will satisfy (30). Now,

( ) ( )( )Yysign,,ysigndiagY nn11 K= (36) The Schur method described above for (1), can also be used to

solve (3).But some computational effort can be saved if the larger of the two matrices A and B, B (for example) is left in the Hessenberg form and the other one, A is transformed to RSF.

3.3 A Hessenberg-Schur method for the Sylvester Equation We describe this method: Step 1: Reduction to the Hessenberg-Schur Problem Let:

346


)

BVVH,UAUR TTT == (37) be the upper RSF of A and the Hessenberg from for B. Then: (3) (38) ⇔ CHYYR T =+where: (39) CUVC,XUVY TT ==

Step 2: Solution of the Reduced Problem Let . ( ) ( n1n1 c,,cC,y,,yY KK ==

Assume that have already computed, (or yk and yk+1) can be computed as in the case of Lyapunov equation:

k1k yy ÷+ ky

Case 1: 0r 1k,k =− : yk has come from:

( ) ∑+=

−=+n

1kjjkjkkkk yrcyIrH (40)

Case 2: for some k: yk and yk-1 are simultaneously computed by solving the

0r 1k,k ≠−

m2m2 × linear system: ( ) ( ) ( ) ( ) ( k1k

n

1kjjkjjj,1kk1k

kkk,1k

1k,k1k,1kk1kk1k d,dyr,yrc,c

rrrr

y,yy,yH −+=

−−−

−−−−− =−=⎟⎟

⎠

⎞⎜⎜⎝

⎛+ ∑ ) (41)

Step 3: Recovery of the original solution: (42). TVYUX =

4. Applications In this § we give some numerical examples to apply the above

methods.

References [1] Bartels, R.H. and Steward G.W., Algorithm 432: solution of the matrix

equation , Comm ACM Vol.15, 1972. CXBAX =+[2] Datta H., HongY.P. and Lee R.B., Applications of linear transformation to

matrix equations, Lin. Alg. Appl. Vol.267, 1997 [3] Hammarling S.J., Numerical solution of the stable nonegative definite

Lyapunov equation, IMA J. Numer. Anal Vol.2, 1982.

347


ACTIVATION OF METALS

Chivu Florica

Departament of chemistry, "Mircea cel Batran"

Naval Academy, Constanta, Romania Abstract

This article aim to bring to the attention of synthetic chemists the possibilities offered by sonochemistry for metal activation.

More importantly, the aim is to demonstrate that the interaction of acoustic waves with a chemical system is far from being merely a rather complicated way of achieving agitation or surface cleaning, but involves complex physical phenomena which are presently a matter of advanced research.

Keywords: electron transfer, acoustic waves, hot spot Introduction Ultrasound –Induced Activation of Metals Organic synthesis without metals cannot be imagined, since

reactions using them rank among the more important methods for the formation of carbon-carbon bonds.However chemists often find at the bench that mixing a metal and an organic partner does not necessary produce a reaction."Activation" is frequently required as a first step on the way to the desired reagent or reaction.Several methods have been introduced to give access to new organometallic reagents, either via direct processes, or indirectly via auxin aries, easily prepared reagents which cand then undergo metal exchange.Practical experience has let led to a deep insight into the advantages and limitations of such methods.Numerous article and specific reviews dealing with particular methods have been published and this book contains discussion on

348


these points.A recent review [1] and a book [2] by one of us give a general overview of this subject.

Sonochemistry is now a well-established branch of chemistry with relevant theoretical and experimental advances [3, 4]. The effecativenes of sonication in this field was perceived at the beginning of the fifties by Renaud [5] but significant applications in synthesis are much more recent. Ultrasound offers inherent advantages (and of course limitations) compared with other activation agents, and the methodology has proven to be a safe, quick, and easy way to produce active materials under wery mild conditions.Reviews and books contain pertinent discussions on this topic. [3, 4, 6-12].

An in-depth study of the principies of sonochemistry lies beyond the scope of this survey.However some theoretical aspects will first be considered, to allow a better under-standing of the results and to familiarize beginners with the technique and equipment .

The symbolism adopted here is ))) for sonochemical reactions, and ) for reactions effected in the absence of ultrasound, also called silent reactions, in accordance with internationally accepted usage.

Disscusion The Physical and Chemical Effects of Ultrasonud The propagations of an acoustic pressure wave in a liquid consists

of an alternation of compressions and rarefactions. When the amplitude of the wave reaches a critical value, the Blake threshold, the intermolecular van der Waals forces are not strong enough to maintain the cohesion of the liquid during the rarefaction phase. The structure is broken and a cavity filled with gases and/or vapors of the surrounding liquid is created, preferentially where small solid particles or gas bubbles are present. A description of these complex phenomena accessible to organic chemists is given in [14]. After this nucleation and growth, the subsequent evolution of the bubble forms the basis of sonochemistry.

349


Dynamics of the Cavitation Bubble. Transient and Stable Cavitation

After their creation the bubbles grow to 2-10 times the initial diameter of a few microns and undergo radial vibration. Some of them become highly unstable. After a few cycles of rarefaction and compression (transient cavitation), they collapse violently in 10-5s-

10-7s Under these adiabatic conditions the content in the residual bubble is subjected to high temperatures (ca. 5000 K), and pressures (several hundreds of bars) generating a "hot spot" [15, 16].Sonochemistry should therefore be closely related to flash thermolysis, but many experimental results cannot be explained solely by this approach.

Bubbles undergo not only radial vibrations but also surface deformations resulting from tangential forces on the boundary layer, leading to molecular redistribution and reorientation. After several tens or hundreds of cycles (stable cavitation), the deformed bubbles fragment into smaller gaseous inclusions. During these events, considerable electrical fields [17] are generated in the separation zones (indentations) of the "daughter" bubbles from the "mother" large bubble. High energy electrons are emitted in these zones [18] and the bubble bears an overall negative charge [19]. The electrons propagating across the bubble can be captured by the vapors, the solvent, or molecules in solution. This theory, which predates that of the "hot spot" [20], emphasizes the electrical consequences of cavitation, which, from the chemist’s viewpoint, should be ionization and formation of radicals or radical ions from the irradiated compounds, a kind of "mass spectrometry" chemistry.

The probable coexistence of "hot spot" and "electrical discharge" effects reflects the complexity of cavitation and explains the unique character of sonochemistry. The relative influence of these intricate phenomena should be frequency dependent [21], an aspect recently reexamined by Italian sonochemists [22].

Cavitation in Heterogeneous Solid-Liquid Systems In the recent development of synthetic sonochemistry,

heterogeneous reactions were muh more intensively studied than homogeneous ones, essentially because cavitation appear to be more

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easily predictable when produced in two-phase systems. In the strongly deformed cavitation bubble, a liquid jet propagates at a high velocity before violently hitting the interface [8, 23, 24]. On solids, erosion takes place [25], with removal of particles and/or permanent deformation of the surface. In terms of chemistry, what is produced can be described as an "activation" of the surface.

The Physical Nature of Activation Usually, a metal surface is not pure. A solid coating of oxides,

hydroxides, carbonates and sometimes nitrides, constitutes a "passivation" layer which prevents the reagent in the solution from reaching the metal [26]. Activation consists of reestablishing the contact between the partners. In a study of the formation of Grignard reagents, the rate of the subsequent reaction was shown to be proportional to the active surface area [27], a result which can be extrapolated to most reactions of metals. Two mechanisms, sketched be envisaged for surface depassivation, according to the mechanical properties (e.g. the hardness [28]) of the metal itself and its coaling.

When sonicated, soft materials such as alkali metals undergo permanent plastic deformation, regardless of the nature of the passivation layer. Electron microscopy of a lithium surface (hardness 0.6 Mohs) reveals very important changes in morphology [29], The surface area is increased and numerous irregularities appear. Sodium and potassium, softer then lithium, can even be dispersed to give highly reactive fine powders [30]. Sonication of magnesium, harder than lithium (2.3 Mohs), seems to affect only the superficial layers [31]. Fracturing of the oxide (5 Mohs), not necessarily accompanied by its removal, offers a better explanation for the experimental observations.

A second factor is the adhesion of the passivating layer to the underlying metal. The role of ultrasound should be to overcome this adhesion. Aluminum (hardness 2.7 Mohs) is thought to undergo plastic surface deformations which fracture its hard (9 Mohs) strongly adhering oxide layer, before the metal structure itself is broken. Zinc is probably activated via another mechanism, as its oxide is not firmly attached. Indeed, Auger spectroscopy [8] reveals that sonication reduced the oxygen content or the surface layer and the size of the

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particles, especially the larger ones, is slightly reduced. Copper [32] and nickel [33] show similar phenomena.

The catalytic activity of a sonicated nickel powder for hydrogenation is increased by a factor of 105, but is lost after prolonged sonication. Collision between particles are believed to produce local fusion at the contact point, and reagglomeration. This interpretation was later challenged [34] and an alternative explanation can be proposed based on tribochemistry [35]. Lastly, when hard metals with hard adhesive oxide are involved, such as molybdenum and tungsten, sonochemical activation no longer takes place [8].

The Chemical Component of the Sonochemical Activation Having undergone a first step establishing the physical contact

between the reaction partners, the metallic surface is assumed to react. Let us consider as an example a reaction starting from an organic halide. The initial step is an electron transfer from the metal to the carbon-halogen bond, taking place on the surface [36, 37], In a study of the Barbier reaction in the presence of lithium, it was noted that not all the results could be interpreted solely on the basis of mechanical effects [29]. Experiments revealed that the initial electron transfer itself is enhanced by sonication, which then has a true chemical role, a conclusion consistent with results obtained later.

The promotion of single-electron transfers (SET] is regarded as a general characteristic of sonochemistry. In reactions with metals, the origin of this effect is still unclear. Theoretical calculations showed that, for non-transition metals, the energy gap between the valence and conduction bands (in the language of organic chemists, the HOMO and LUMO) is reduced by sonication [38]. An interpretation of the sonochemically enhanced reaction based on this result should however be treated with caution, since the frequencies used in this study, up to 1011 Hz, are much higher than those employed in sonochemistry. On the other hand, the creation of structural defects by ultrasound is expected to have other consequences besides mechanical ones. Physicists know that in disordered metallic structures the electrons do not circulate freely, but are located at lattice defects where the wave-function reaches maximum values [39]. Correspondingly, it was shown that the more "reactive" metal atoms are those with a minimum

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number of neighbors [40]. It is intuitively understood that an atom placed on an edge or a defect has unsatisfied valences and is less tightly bound to the lattice. After the initial electron transfer, the question of whether the intermediate radical or radical anion remains at die metal surface or not [36, 37] does not affect the last step, during which an atom or ion must be extracted from the metal.

The Relationship between Sonochemical and Mechanochemical

Activation The surface area and reactivity of a metal increase when it is

subjected to mechanical stresses. Contraintuitively, the surface effect has only minor consequences, whereas the accumulation of energy in lattice defects is considered to be responsible for up to 90% of the increase in reactivity [35]. At the same time, high energy electrons are ejected by the collision and can induce chemical reactions [41]. For instance, styrene polymerizes when subjected to ball milling in a metallic reactor [42].

The catalytic properties of nickel powders can be enhanced in the same way. Prolonged mechanical treatment results in the loss of the catalytic property by a relaxation process [43], an effect similar to the observations mentioned above [33].

From the description of the effects of the cavitational collapse on metallic surfaces, an analogy with micro-hammering can be drawn. Shock waves and microstreaming produce lattice defects and surface vacaciest increasing the total energy of the system, which can then relax, among other pathways, by easier chemical reactions. The analogy between mechanochemical and sonochemical reactions thus seems plausible. In this context it is worth considering Rieke's active metal preparation method [44], which should also produce such energy-rich disorganized states. Since the reductions require prolonged heating, some deactivation can result from a thermal relaxation process (annealing), which is minimized in reactions performed under sonication in shorter times at lower temperatures [45].

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Conclusions In order to place sonochemistry in a general context, some

fundamental aspects are briefly discussed here. Many sonochemical processes cannot be understood on the basis of cleaning and erosion effects, and a true picture of how the non-quantified mechanical energy is transformed into chemical energy cannot be derived from the "hot spot" theory alone. In the absence of a general understanding, a classification leading to empirical rules was proposed with the purpose of predicting the behavior of a given system [46].

The first type of sonochemical reactions are those occurring in solution. Cavitation phenomena generate reactive intermediates such as radicals or radical-ions. Ionic processes remain unaffected. Sonochemical switching, a term coined by Ando [47] for describing the difference in nature of the reaction products in the presence and absence of ultrasound, can occur. Sonochemical switching is often an indication of the existence of a SET process in competition with an ionic one.

The second type includes heterogeneous ionic reactions. The influence of ultrasound is purely physical and sonochemical switching is not expected. Although the ionic pathway remains unchanged by sonication, rates and yields can be substantially improved by what may be called "ultrasonic agitation". This class of reactions can also be described as "false sonochemistry".

The third type of sonochemical reactions are heterogeneous radical reactions, or processes that can follow either an ionic or a SET mechanism. They are influenced by the physical and chemical effects of sonication, and the nature and ratio of the products represent the relative importance of the two different mechanisms. Many of these reactions involve metals and the results have led to important conclusions concerning the reaction mechanisms.

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