EngineeringCarlos A. Santos SilvaSeptember 23th, 2009

WHAT IS ENGINEERING?

The roots

•Ingenium [Latin]:

• innate quality, especially mental power, hence a clever invention

= Genious [English]

•Engine:

•Military machine / machine

•Engineer:

•Operator of an engine

•Engineering:

•Military engineering (roads, bridges, vehicles)

Definition

Accreditation Board for Engineering and Technology:• The creative application of scientific principles to design or develop structures,

machines, apparatus, or manufacturing processes, • or works utilizing them singly or in combination; • or to construct or operate the same with full cognizance of their design; • or to forecast their behavior under specific operating conditions; • all as respects an intended function, economics of operation and safety to life

and property;

“Scientists study the world as it is; engineers create the world that has never been” [T. von Kármán]

“Apply scientific knowledge and technology to solve real problems”

HISTORY

The Greeks

Archimedes Screw (Holand)

“Give me a leverand I will lift the world”

Heat-Ray Syracuse

The Romans

Criptoportic(Lisbon,Portugal)

Aqueducts(PontduGard,France)

ViaApia (Italy)

The Egyptians, The Chinese, The Arabs

Great Wall(Chinese 500BC-1700)

5 machines(Al-Jazari 1200)

Papyrus scroll(Imhotep)

16th to 19th Century

Electrical Motor(Hungary 1821)

One span bridge(Leonardo Da Vinci)

Steam Governour(James Watt 1788)

Siemens Telegraph(Germany1856)

Jaquard loom(France 1801)

20th Century

Transistor(US 1947)

Ford T(US 1908)

Jet Plane(Germany 1929)

ENIAC(US1946)

Space shuttle(US1981)

Panama Canal(US1914)

TYPES OF ENGINEERING

Traditional branches

•Civil Engineering•Mining Engineering•Mechanical Engineering•Chemical Engineering•Electrical Engineering•Aeronautics Engineering•Physics Engineering

New branches

•Computer and Software Engineering•Bio – Engineering•Molecular Engineering•Nanotechnology Engineering•Mechatronics Engineering•Aerospace Engineering

•Engineering Systems

Engineering Systems

“study dealing with diverse, complex, physical design problems that may include components from several engineering disciplines, as well as economics, public policy, and other sciences”•Examples of complex systems:• Internet• Supply Chains• Air-traffic control• Energy networks

ENGINEERING MINDSET

Solve problems by finding solutions

"Everything should be made as simple as possible, but not simpler.“ [A. Einstein]

Create model that represents the problem

Understand problems and test solutions

Design multiple solutions

Evaluate options

Choose solution

Trade off between requirements fulfillment, complexity of manufacturing, safety….

Characteristics

•Build models• Abstraction•Design solutions• Science knowledge • Deduction• Analogy•Make choices• Experience • Intuition

Simple problems:

Show what to do: theory, application, heuristics, examples to train theory

Compound problems:

Case-studies: get information and apply accordingly

Engineers….

•Know that there is more than one solution

•The best solution might not be the perfect solution

•The result might not be exactly as previewed, but it is within an interval

•Have to know science (physics)

•Deduct results (general premises to particular conclusions)

•Establish analogies (transferring information from a particular case to other)

•Class1- Defining Engineers

• Battle against uncertainty

• Result driven

•

Why Physics?

•Understanding of Nature• Discovering the laws governing the universe and predict how it will behave

Matter:

Anything that has weight

Light:

Anything that can travel trough empty space and has no weight

Tools• Scientific method: theory to explain and predict, experiments to demonstrate• Reductionism: isolate system to study•Measurement System• Scaling• Estimates• Vectors• Conservation Law• Simplifying assumptions

INTRODUCTION TO ENGINEERING

Program and Evaluation

1. Engineering and tools for Engineering

2. Kinematics and Dynamics

3. Waves, Atom and Optics

4. Electricity and Magnetism

5. Electrical Systems

6. Thermodynamics

7. Fluids

8. Heat Transfer

9. Thermodynamic cycles

10. Diesel and Otto cycles

11. Steam and Cooling cycles

12. Systems

Assignments for each topic (40%)

Final Assignment (60%)

Bibliography and References

•Classes Slides and Readings•http://groups.google.pt/group/mit-portugal_ses_0910 •Books•http://www.lightandmatter.com/• Newton physics• Conservation laws• Vibration and Waves• Electricity and Magnetism•Optics•Modern Revolution in Physics•Internet•http://www.wikipedia.org/

Tools for EngineeringCarlos A. Santos SilvaSeptember 25th, 2009

International Measurement System (SI)

•Basic Units•Meter (m) for distance• The length between two marks on a platinum-iridium bar,

which was designed to represent 1⁄10,000,000 of the distance from the equator to the north pole through Paris• The meter is the length of the path travelled by light in

vacuum during a time interval of 1/299 792 458 of a second

• Second (s) for time• Kilogram (kg) for mass• Ampere (A) for electric current• Kelvin (K) for temperature•Mole (mol) for amount of substance in a system• Candela (cd) for luminous intensity Prototype kg

Prototype meter (1960)

SI Prefixes

1000m 10n Prefix Symbol Since

10008 1024 yotta (iota) Y 1991

10007 1021 zetta (zeta) Z 1991

10006 1018 exa E 1975

10005 1015 peta P 1975

10004 1012 tera T 196010003 109 giga G 196010002 106 mega M 196010001 103 quilo k 1795

102 hecto h 1795101 deca da 1795

10000 100 none none10−1 deci d 179510−2 centi c 1795

1000-1 10−3 mili m 17951000-2 10−6 micro µ (mu)1 19601000-3 10−9 nano n 19601000-4 10−12 pico p 1960

1000-5 10−15 femto (fento) f 1964

1000-6 10−18 atto (ato) a 1964

1000-8 10−24 yocto (iocto) y 1991

Metric Measurement System (SI)

•Countries where the metric system is official

Other units

•Velocity – meter per second [m/s or ms-1]

• Velocity of an object traveling 1 m in 1 s

•Force – Newton [N]

• Force applied during 1 s to a 1kg object starting from rest to a velocity of 1ms-1

•Energy (Mechanical and thermal) – Joule [J]

• A force of 1 N moving an object for 1 m

• Heat 1g of air by 1 K

•Power – Watt [W]

• 1 J per 1 s / rate of work or energy

•Energy (Electrical) [J]

• Produce 1 W during 1 s

Scientific notation

•It is used to represent large numbers

•Representing a number with a product between:

• a number between 1 and 10

• a number that is a power of 10.

•Examples:

• 1000 kg = 1x103 = 1E+3

• 1g = 0,001kg = 1x10-3 =1E-3

Conversions

•Different measurement systems• 1 inch = 2,54 cm = 0,0254 = 2,54x10-2 m• 1 lb = 4,54 10-1 kg / 1kg = 2,2 lb• 1 cal = 4.184 J (thermochemical calorie)

•Conversion methodology• 10 pound in kg

• 1 year in s

g4540kg54,4kg2.2

10

pounds2.2

kg1pounds10pounds10

ss 7103,1531536000s

minute1

60

hour1

minutes60

day1

hours24

year1

days365year1year1

Significant Figure

Gives the accuracy of a number• 5m ≈ 4,99m ≈ 5.12m• 5.00m ≠ 4.99m ≠ 5.12m

The number of significant digits depends on the least accurate data• 5.00m + 0.1m = 5.1m

To count the number of digits, count the number of digits different from the 0s to the left and to the right (ambiguous)• 50cm=5.0x10-1m or 5x10-1m• 0,5m=5x10-1m •Using scientific notation helps to keep track of the significant figures• 5x10-1m (1 significant figure)• 5.0x10-1m (2 significant figure)

Scaling

•In order to study a system it is normal to make scaled models

Natural phenomena behave differently on different scales

Example

Clay 1: length x height x depth

Clay 2: 2length x 2height x 2depth

Why does Clay 2 break?

Cross Area α L2

Clay2 =4 Clay1

Volume (Weight) α L3

Clay2 =8 Clay1

Galileo experiment

Order of Magnitude

•Things that differ by a factor of 10 are said to differ one order of magnitude

1 and 9 are the same order of magnitude

1 and 19 are one order of magnitude different

Often it is necessary to make rough estimates (~)

Round up to the nearest power of ten (same order of magnitude)

Don’t forget scaling effects:

Imagine simpler objects

Estimate area and volume based on linear dimensions

Example:

How much does it cost to cover the classroom floor with a 1m long square panels that cost 10€?

Vector

Geometrical object described by•Magnitude (length)• Direction

Entity that “carries” A to B

Used to describe forces

Vector Operations

Addition

Scalar multiplication

Cross Product