architectural acoustics, new engineering materials ,ultrasoni
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PHYSICS PRESENTATIONPRESENTED BY:-
1. 140410116054 PATEL HARSH
2. 140410116055 PATEL HETUL
3. 140410116056 PATEL JAINA
4. 140410116057 PATEL KINJAL
5. 140410116058 PATEL KUNJ
CONTENT :
INTRODUCTION CLASSIFICATION OF SOUND CHARACTERISTICS OF SOUND INTENSITY SOUND ABSORBING MATERIAL REVERBERATION TIME FACTORS AFFECTING ACOUSTICS OF BUILDING REMEDIES OF AFECTING FACTORS
INTRODUCTION :
DEFINITION OF ACOUSTIC :- ACOUSTICS is the SCIENCE of SOUND which deals
with the properties of SOUND WAVE , their origin, propagation & their action on obstacles.
ARCHITECTURAL ACOUSTICS deals with the design & construction of music halls & sound recording rooms to provide best audible sound to the audience.
CASSIFICATION OF SOUND :
On the basis of frequency sound waves are classified into 3 types.
- INFRA SOUND [f<20Hz] - AUDIBLE SOUND [ 20Hz < f < 20kHz] - ULTRA SOUND [ f > 20kHz] CLASSIFICATION OF AUDIBLE SOUND: 1) MUSICAL SOUND 2) NOISE
CHARACTERSTICS OF SOUND :
PITCH : Related to Frequency of SOUND. : The PITCH of SOUND changes due to DOPPLER’s principle. LOUDNESS : Related to Intensity of SOUND. : Relation between LOUDNESS(L) & INTENSITY(I), where K is constant. TIMBER : Related to Quality of SOUND.
L = K log I
L
INTENSITY (I) :
Definition:-Intensity is defined as the amount of sound energy Q flowing per unit area in unit time.
Mathematically Intensity is define as
Unit:- Weber/m².
I = Q/At
LOUDNESS INTENSITY
It is degree of SENSATION Produced on the ear.
It is the quantity of SOUND ENERGY flowing across unit AREA in unit TIME.
It various from listener to listener.
It is independent to listener.
It is a PHYSIOLOGICAL quantity.
It is a PHYSICAL quantity.
Its unit is SONE. Its unit is Weber/m².
SOUND ABSORBING MATERIALS :
SR.NO
SOUND ABSORBING MATERIALS
EXAMPLE
1 PORPUS ABSORBERS
FIBER BOARDS, ROCK WOOD, WOOD WOOL, SOFT PLASTERS, MINERAL WOOLS, GLASS SILK, ASBESTOS FIBER SPRAY.
2 CAVITY RESONATORS
CAVITY RESONATOR CHAMBER.
3 RESONANT ABSORBENTS
WINDOWS,DOORS, RIGID PLASTIC BOARDS, SUSPANDED PLASTER CEILINGS, GYPSUM BOARDS.
4 COMPOSITE ABSORBERS
BOTTLE, EMPTY JAR, GLASS WOOD, QUILT, SLAB, PERFORMED FIBER BOARD.
REVERBERATION TIME : Definition:- The prolongation of sound wave in a
hall even though the source of sound is cut off is called as REVERBERATION
Sabine’s Formula:- REVEBERATION TIME,
Where, v- volume of hall a- absorption coefficient s- surface area
T
FACTOR AFFECTING ACOUSTICS OF BUILDING :
REVERBERATION TIME LOUDNESS FOCUSSING & INTERFERENCE EFFECT ECHO ECHELON EFFECT RESONANCE NOISE : 1) AIR BORNE NOISE 2) BORNE NOISE 3) INSIDE NOISE
REMEDIES TO CONTROL ACOUSTICS
By providing windows & openings. By covering the floor with carpets. By using public address system like Loud
Speaker. Avoid Curvature surface. To cover surfaces with Sound Absorbing
materials. By decorating the walls with pictures &
maps.
INTRODUCTION In the field of electrical , optical ,medical &
communication engineering new engineering materials play a vital role.
Today, In industries these materials are required for good & high quality production.
There are so many advance engineering materials use today.
EXAMPLES: Metallic glass, Bio-materials, Different Energy materials.
METALLIC GLASS Metallic glasses share the properties of METAL
& ALLOYS. Metallic glass is non-crystalline , brittle and
transparent solid. Metallic glasses are to be made by various
rapid cooling techniques such as, :-Spraying :-Spinning :-Laser Deposition
TYPES OF METALLIC GLASSES
1.Metal-Metal GlassesExamples:- : Ni-Nb : Mg-Zn : Cu-Zr
2.Metal-Metalloid GlassesExamples:-:commercial metallic glasses are usually of this kind
PROPERTIES OF METALLIC GLASS:-
They are Ductile,Malleable,Brittle & Opaque. Lighter in Weight Toughness & Hardness is very High High Elasticity High Corrosion Resistant Soft Magnetic Materials Strength is very High.
APPLICATION OF METALLIC GLASSESMetallic glasses are used as Transformer Core material in High power transformers. It used in making Cryothermometers , Magneto
resistance sensors & Computer memories. As magnetic properties of Metallic glasses, they
are used in making containers for Nuclear waste disposal.
It used in preparation of magnets for fusion reactors & levitated trains.
It used for making watch cases to replace Ni & other metals, which can cause allergic reaction.
It used in tap reorders as heads , in manufacturing of springs & standard resistance.
BIO-MATERIALS Bio-Material:- A synthetic materials used to
make devices to replace part of living system Or to function in intimate contact with living tissue.
A variety of devices & materials are used in the treatment of disease or injury.
Bio-materials are classified into three groups:- 1. Bioinert2. Bioactive3. Biodegradable
Bio-material
Defination Application Examples
1. Bio-inert Minimal interaction with surrounding tissues
Implant Applications
Stainless Steel,Titanium,Alumina.
2. Bioactive Interact with surrounding hard (bone) and soft tissues
Bone Filling,Dental Filling,Application.
Hydroxyapatite,Bioactive Glass,Glass Ceramics.
3. Biodegradable
Material slowly dissolved into body and replace the damaged tissues
Scaffold application Drug dilivery
Polylactic-Polyglaycolic, acid Copolymers
ENERGY MATERIAL Some energy Materials classified below:-1. Solar Cell2. Fuel Cell3. Lithium Cell4. Ultra Capacitor
SOLAR CELL Solar cell is a device that convert Solar energy
directly into Electric energy. Principle: Solar cell operate on the principle of
Photovoltaic action. A solar cell is basically a P-N junction which
generates EMF when solar radiation false on P-N junction.
APPLICATIONS OF SOLAR CELL
Telecommunication PV systems & difficult to areas like mountain tops , islands & deserts.
To prevent corrosion of pipe , Bridges , etc. PV systems are also used to power railway
signals , alarm systems , traffic lights & highway telephones.
Remote radio & light beacons are powered by PV systems.
Interval of Time , Meteorological stations are powered by PV systems.
CONTENT
Introduction to Ultrasonic
Production of Ultrasonic waves
Ultrasonic in Non-Destructive Testing
Applications of Ultrasonic's
INTRODUCTION
Classification of sound wave:-1. Depends upon Frequency
2. Divided into 3 groups
Description Frequency range
Infra sound 0-20
Audible sound 20-20,000
Ultra sound >20,000-5M
PROPERTIES OF ULTRASONICS They have a high energy content (high freq)
Speed of ultrasonic waves depends on frequency .
Their wavelengths are small as a result , their penetrating power is high.
They can travel over long distances as a highly directional beam.
Polarization: can not be polarized
CREATING ULTRASONIC WAVE
Ultrasonic waves are produced by the following methods
1. Magneto-striction generator or oscillator
2. Piezo-electric generator or oscillator
MAGNETOSTRICTION METHOD
This method is used to generate low frequency ultrasonic waves
Principle: Magnetostriction effect When a magnetic field is applied parallel to
the length of a ferromagnetic rod made of ferromagnetic materials such as iron or nickel, a small elongation or contraction occurs in its length
MAGNETOSTRICTION METHOD
The change in length (increase or decrease) produced in the rod depends upon i) the strength of the magnetic field, ii) the nature of the ferromagnetic materials iii) does not depend of the direction of the field.
MAGNETOSTRICTION METHOD XY is a rod of ferromagnetic materials like iron or
nickel. The rod is clamped in the middle.
The alternating magnetic field is generated by electronic oscillator.
The coil L1 wound on the right hand portion of the rod along with a variable capacitor C.
This forms the resonant circuit of the collector tuned oscillator. The frequency of oscillator is controlled by the variable capacitor.
The coil L2 wound on the left hand portion of the rod is connected to the base circuit. The coil L2 acts as feed –back loop.
Working• When High Tension (H.T) battery is switched on,
the collector circuit oscillates with a frequency,
f =
• This alternating current flowing through the coil L1 produces an alternating magnetic field along the length of the rod. The result is that the rod starts vibrating due to magnetostrictive effect.
1
1
2 L C
MAGNETOSTRICTION METHOD
The frequency of vibration of the rod is given by f =
where l = length of the rod E = Young’s modulus of the rod material and
=density of rod material• The capacitor C is adjusted so that the frequency
of the oscillatory circuit is equal to natural frequency of the rod and thus resonance takes place.
• Now the rod vibrates longitudinally with maximum amplitude and generates ultrasonic waves of high frequency from its ends.
E
l
P
2
MAGNETOSTRICTION METHOD
Advantages1.The design of this oscillator is very simple and its production cost is low2.At low ultrasonic frequencies, the large power output can be produced without the risk of damage of the oscillatory circuit.
1.It has low upper frequency limit and cannot generate ultrasonic frequency above 3000 kHz (ie. 3MHz).
2.The frequency of oscillations depends on temperature.
3.There will be losses of energy due to hysteresis and eddy current.
Disadvantages
MAGNETOSTRICTION METHOD
PIEZO ELECTRIC METHOD
If mechanical pressure is applied to one pair of opposite faces of certain crystals like quartz, equal and opposite electrical charges appear across its other faces. This is called as piezo-electric effect.
The converse of piezo electric effect is also true.
If an electric field is applied to one pair of faces, the corresponding changes in the dimensions of the other pair of faces of the crystal are produced. This is known as inverse piezo electric effect or electrostriction.
Principle : Inverse piezo electric effect
The quartz crystal is placed between two metal plates A and B.
The plates are connected to the primary (L3) of a transformer which is inductively coupled to the electronics oscillator.
The electronic oscillator circuit is a base tuned oscillator circuit.
The coils L1 and L2 of oscillator circuit are taken from the secondary of a transformer T.
The collector coil L2 is inductively coupled to base coil L1.
The coil L1 and variable capacitor C1 form the tank circuit of the oscillator.
PIEZO ELECTRIC METHOD
When H.T. battery is switched on, the oscillator produces high frequency alternating voltages with a frequency.
Due to the transformer action, an oscillatory e.m.f. is induced in the coil L3. This high frequency alternating voltages are fed on the plates A and B.
Inverse piezo-electric effect takes place and the crystal contracts and expands alternatively. The crystal is set into mechanical vibrations.
The frequency of the vibration is given by
f =
112
1
CLf
E
l
P
2
where P = 1,2,3,4 … etc. for fundamental, first over tone, second over tone etc.,E = Young’s modulus of the crystal and ρ = density of the crystal.
Working
PIEZO ELECTRIC METHOD
Advantages Ultrasonic frequencies as high as 5 x 108Hz or 500
MHz can be obtained with this arrangement. The output of this oscillator is very high. It is not affected by temperature and humidity.
Disadvantages The cost of piezo electric quartz is very high The cutting and shaping of quartz crystal are
very complex.
PIEZO ELECTRIC METHOD
APPLICATION OF ULTRASONIC WAVESSONAR
SONAR is a device which stands for Sound Navigation and Ranging.
It is based on the principle of echo sounding.In this technique high-frequency ultrasonic waves are used.
When ultrasonic waves are transmitted through water,they get reflected by the objects under water.the change in frequency of the echo signal due to the Doppler effect helps us to determine the velocity,distance and direction of objects.
Using sonar the distance and direction of submarines,depth of sea ,depth of rocks in the sea,the shoal of fish in the sea.,can be determined.
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ULTRASONICS IN NON-DESTRUCTIVE TESTING
Ultrasonics used in Non-Destructive Testing. It is defined as the process of testing the material
without causing any damage or reducing the service life of the component.
NDT may be classified as:(1)To incress serviceability(2)To improve productivity and to increse the profits(3)To increse safety
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OTHER APPLICATION OF ULTRASONICS
Ultrasonic waves used in industry for drilling,cutting,welding,soldering.
It is uesd in medical for diagostic purpose and therapetic.
It is also used in science and engineering. It used in medicine.
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