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Monday, August 5, 2013

PPT On Laplace Circuit Analysis


 Laplace Circuit Analysis Presentation Transcript:
 1. In this course we have modeled circuit elements (resistors, inductors, and capacitors) as linear and time invariant.   We have used linear differential equations to determine the transients.  We have modified this analysis for AC steady state by using jw with inductors and capacitors to form impedance.  We coupled this with phasors to solve AC steady state circuits. 
In the case of Laplace transforms we take the Laplace transform of the voltages and currents that describe the circuit elements (resistors, capacitors, inductors).  This converts the circuit models to functions of s as illustrated here.  We then use all the methods of analysis that we learned for DC circuits such as nodal, mesh, Thevenin, Norton, to solve the Laplace circuits which we say are in the complex frequency domain.  Everything is algebraic and it makes the problem(s) easier to handle than if we carried out everything in the time domain with integral, differential equations.  Once we have found the particular variable we seek, such a voltage or current, we then take the inverse Laplace to go to the time domain.

Z-Transform And It's MATLAB Implementation PPT


Z-Transform And It's MATLAB Implementation Presentation Transcript:
1.Signals and Systems (Lab)

2.Z-Transform and its MATLAB implementation .

3.In This Lab…
Introduction to Z-Transform
How to implement Z-transform and Inverse Z-transform in MATLAB?
What is meant by Region of Convergence (ROC)
Pole Zero Plot
Stable and Unstable Systems
Impulse Response and Step Response
MATLAB Implementation of inverse Z-transform using Partial Fraction Expansion
How to use Z-Transform to solve Difference Equations using MATLAB?

4.Introduction to Z-Transform

5.MATLAB Implementation of Z-Transform

6.Solution of Example 1

7.The command ztrans and iztrans

8.Solution of Example 2

9.Discrete Time System Properties

10.Pole-Zero Plot and Stability
num=[.1 .1];
den=[1 -1.5 0.7];
Is this system is STABLE??

11.Step Response
num=[.1 .1];
den=[1 -1.5 0.7];

12.Impulse Response

13.Partial Fraction Expansion of a Rational Function

14.The Command residue

15.Solution of Difference Equation using Z-Transform

PPT On L.T Circuit Breakers


L.T Circuit Breakers Presentation Transcript:
1.L.T Circuit Breakers

2.L.T Circuit Breaker
A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.

3.Basic Principle:
    When a current supplies enough energy to operate a trigger device in a breaker, a pair of contacts conducting the current are separated by preloaded springs or some similar mechanism.

4.    Because it is usual for an electric arc to form between the contacts when a breaker opens, some means must be provided for preventing rapid erosion of the contacts.

5.    Electrical systems in residential, commercial and industrial applications usually include a panelboard for receiving electrical power from a utility source. The electrical power is then delivered from the panelboard to designated branch circuits supplying one or more loads.

6.        Thermal Circuit Breakers:
    In this device, the current flows from the battery terminal, through the bi-metal strip and then to the other terminal. The bi-metal strip is made of two different types of metal which have different coefficients of expansion. This means that one will expand more than the other when the rise in temperature is the same for both pieces. The two metals are bonded to each other. When the strip heats up from the current flow through it, one type of metal expands more than the other.

7.    When the temperature reaches a given point, the piece will snap into the open position and the current flow will stop.

8.        Magnetic Circuit Breakers:
    Some circuit breakers use a magnetic actuator to trip the circuit. In this type of breaker, the current flow through the electrical device passes through an electromagnetic actuator. When the current flow reaches a preset level (determined by the current rating of the breaker), the magnetic field in the electromagnet is strong enough to trip the breaker and allow the contacts to open. This type of breaker generally has to be manually reset. A well designed 'magnetically' actuated circuit breaker can operate very quickly (possibly as fast as or faster than a fuse of equal current rating).

9.    Circuit Breaker can be divided into two categories:
    The circuit beaker that trips or breaks the     circuit when there is a short circuit or     when there is too large current through the     circuit.
     The circuit beaker that trips or breaks the     circuit when there is small leakage currents     from the live wire to the earth wire.

10.    Types of first Category:
    Low voltage (less than 1000 V AC) types are common in domestic, commercial and industrial application, include:

    MCB (Miniature Circuit Breaker)—rated current not     more than 100 A. Trip characteristics normally not     adjustable. Thermal or thermal-magnetic operation.     MCCB (Moulded Case Circuit Breaker)—rated     current up to 1000 A. Thermal or thermal-magnetic     operation. Trip current may be adjustable in larger     ratings.

11.     Miniature circuit breakers (MCBs) :   
    Circuit breakers used in residential and light commercial applications are commonly referred to as miniature circuit breakers because of their limited size.

12.     Miniature circuit breakers (MCBs) :
    Miniature circuit breakers are similar to moulded case circuit breaker but as their name implies, these are smaller in size and are mostly used for current ratings below 100A. These are normally available in single pole (SP), single pole neutral (SPN), double pole (DP), triple pole (TP), triple pole neutral (TPN), and four pole versions (FP).     

13.    Miniature circuit breakers (MCBs) are fitted in consumer units in place of fuses. They have the advantage that they can be manually reset without having to replace wire as in the case of the traditional fuse. The MCBs have either a button or lever that can be flicked to reset it.

14.    Moulded Case circuit Breakers:
    Moulded case circuit breakers are power switches and they all consist of five main parts.
    Moulded case (frame)
     Operating mechanism
     Contacts and extinguishers
     Tripping elements
     Terminal connections
15.    Moulded Case: This is external cover of MCCB which houses all the components and is moulded from resin/glass-fiber material. It provides insulation between the live and components and the operators.
    Operating switch/mechanism: This is a handle which connects the internal mechanism for ON/OFF/RESET operations.

PPT On Introduction to Software Engineering


Introduction to Software Engineering Presentation Transcript:
1.Introduction to Software Engineering

2.What is Software?
Some of the constituted items of software are described below:
Program: The program or code itself is definitely included in the software.
Data: The data on which the program operates is also considered as part of the software.
Documentation: All the documents related to the software are also considered as part of the software. So the software is not just the code written in Cobol, Java, Fortran or C++. It also includes the data and all the documentation related to the program.

3.Why is it important?
Some of the major areas in which software has played an important role are identified as under.
Business decision-making
Modern scientific investigation and engineering problem solving
Bioinformatics and the process of DNA decoding is only possible by the use of software systems
Embedded systems
Small microcontrollers used in our cars, televisions, microwave ovens etc. All these systems are controlled through the software.

4.What is Engineering?
The process of productive use of scientific knowledge is called engineering.”

5.Difference bet. Computer Science & Software Engineering
The Science concerned with putting scientific knowledge to practical use.

“This is the process of utilizing our knowledge of computer science in effective production of software systems.”

6.Difference bet. Software & Other Systems
The major thing that distinguishes a software system from other systems is that:
“Software does not wear out”

7.What does that mean?
Software systems does not affect by the phenomenon of wear and tear.
If a software has any defect then that defect will be there from very first day.

8.Software Crisis
In early 60s software had suffered from different kind of problem to which we call Software Crisis. Techniques that were used to develop small software were not applicable for large software systems.
In most of the cases that software which was tried to be build using old tools and techniques were not complete.
Most of the times it was delivered too late.
Most of the projects were over-budgeted.
And in most of the case systems were not be able to do what they were expected to do.

As a result of these problems a conference were held in 1960 in which the term software crisis was introduced.
The major issue discussed was that the development of software is in crisis and we have not been able to handle its complexities. 
In this conference people have said that, we should use engineering principles in developing software in the same way as we use these principles in developing cars, buildings, electronic devices etc.
Software engineering is the result of software crisis when people realized that it is not possible to construct complex software using the techniques applicable in 1960s. An important result of this thing was that people had realized that just coding is not enough.

10.Software Engineering as defined by IEEE
“The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software.”

Another definition of Software Engineering given by Ian Somerville.
 “All aspects of software production’ Software engineering is not just concerned with the technical processes of software development but also with activities such as software project management and with the development of tools, methods and theories to support software production”.

12.Make it clear
These definitions make it clear that the software engineering is not just about writing code.

13.Software Engineering cover
  Software Engineering cover all things that are used in software production like:
 Programming Language 
 Programming Language Design
 Software Design Techniques
 Development etc.
  So all those thing that are related to software are also related to software engineering.

14.Well-Engineered Software
Well-engineered software is one that has the following characteristics:
Provides the required functionality

15.Major Challenge for Software Engineer
The major challenges for a software engineer is that he has to build software within limited time and budget in a cost-effective way and with good quality.

PPT On Introduction to Microprocessor and Computer


Introduction to Microprocessor and Computer Presentation Transcript: 
1.Introduction to Microprocessor and Computer

2.Mechanical Computing
The abacus circa 500 B.C. – the first calculator
Blaise Pascal – the first modern mechanical adder
Charles Babbage – the first true computer
50,000 machine parts
Herman Hollerith – the punched card system and founder of IBM

3.Early electronic computersKonrad Zuse – Z3 (relay logic at 5.33 Hz)
Alan Turing – Colossus
Fixed program computer
University of Pennsylvania – ENIAC
Could be reprogrammed by rewiring the circuit and could several man hours
17,000 vacuum tubes, 500 miles of wires
100K operations per second

4.Early milestones
1948 – the transistor at Bell Labs
1958 – the integrated circuit
1961 – RTL digital logic (resistor-to-Transistor Logic)
1971 – the microprocessor (4004)

5.Early programming
Countess of Lovelace (1823) wrote programs for the Analytical Engine
Machine Language then Assembly Language
Grace Hopper (1957) develops FLOW-MATIC
COBOL –first wide spread language
BASIC and PASCAL as teaching languages

6.Modern programming
Visual BASIC (most common business)
Visual C/C++ (most common technical)
JAVA (most common web)
ADA  (used by DoD
PASCAL -control programs
C# (gaining on web)

7.Early Microprocessors
4004 the first microprocessor (4-bit) 16K RAM
4040 improved speed
8008 (8-bit)
Fairchild, MOS tech., Motorola, National semiconductor, Rockwell, Zilog
8080 (8-bit) 64K RAM, 2Mhz clock
8086 (16-bit) 1M RAM, 5MHz clock
80286 (16-bit) 16M RAM, 16MHz clock

8.32-bit Microprocessors
80386, 4G RAM, 33 MHz clock
80486, 4G RAM, 66 MHz clock
Pentium, 4G RAM, 66 MHz clock
Pentium Pro, 64G RAM, 133 MHz clock
Pentium II, 64G RAM, 233 MHz clock
Pentium III, 64G RAM, 500 MHz clock
Pentium 4, 64G RAM, 1.5 GHz clock

9.The P nomenclature
P1 – 8086/8088 class
P2 – 80286 class
P3 – 80386 class
P4 – 80486 class
P5 – Pentium class
P6 – Pentium Pro/Pentium II, Pentium III, and Pentium 4 class

10.Cache Memory
A temporary high speed memory that buffers the slower DRAM from the higher speed microprocessor.
Usages in bursts of 4 memory-sized chunks of data (today 4, 64-bit numbers)
Level 1 (small cache for local high-speed storage)
Level 2 (larger cache for local high-speed storage.
Level 3 (large cache on Pentium 4 chip)

11.High End Computers
Processor: Intel Pentium 4
Frequency: 3.2GHz
Power consumption: 103 W max.*
Process: 90nm

12.Lower Scale of Computers
Processor can consume no more
 than 250-300mW

13.Speed of Evolution
2X in speed every 1.5 years; 100X performance in last decade
DRAM capacity: 2X / 2 years; 64X size in last decade
Cost per bit:  improves about 25% per year
capacity: > 2X in size every 1.0 years
Cost per bit:  improves about 100% per year
250X size in last decade

14.Memory Organization   
Memory is organized in byte-sized (wide) chunks of data
Memory is numbered in bytes
Memory is number in hexadecimal addresses or locations
Modern memory is 64-bits wide containing 8 bytes per memory physical location.
Modern DRAM is SLOW! (40 ns per a random access)
Buffering and double clock edge transfers can speed memory access times to about 25 MHz

15.Microprocessor Internals

PPT On Interrupt Mechanism


Interrupt Mechanism Presentation Transcript:
1.Interrupt Mechanism
Interrupt Compared With Procedures
Call MyProc
A= Addition(4,5);
 Printf(“hello world”);

2.Int 21h
Int 10h

3.Interrupt Vector Table

4.ISR’s are Routines Resident in Memory

5.Interrupt Invocation
Push Flags, CS, IP Registers, Clear Interrupt Flag
Use (INT#)*4 as Offset and  Zero as Segment
This is the address of interrupt Vector and not the ISR
Use lower two bytes of interrupt Vector as offset and move into IP
Use the higher two bytes of Vector as Segment Address and move it into CS=0:[offset+2]
Branch to ISR and Perform I/O Operation
Return to Point of Interruption by Popping the 6 bytes i.e. Flags CS, IP.

6.Parameter Passing to S/W interrupts

7.S/W Interrupts Invocation
Psuedo Variables
           AX, BX, CX, DX
           _AX = 0x1234H
           a = _BX

8.geninterrupt ( 0 x int# )

9.Interrupt 21/09 Description


char st[80] ={"Hello World$"};
void main()
    REGS regs;
    regs.x.dx = (unsigned int) st;
    regs.h.ah = 0x09;

11.Interrupt 21/42H Description
Int # 21            Service # 42H                             
    AL = Move Technique
    BX = File Handle
 CX-DX = No of Bytes File to be moved
    AH = Service # = 42H
  DX-AX = No of Bytes File pointer               actually moved

PPT On Illumination Engineering


Illumination Engineering Presentation Transcript:
1.Power Distribution & Utilization

2.Contents To Be Covered:
Terms Used in Illumination
Laws of Illumination
Measurement of Illumination
Sources of Light
Arc Lamps
Incandescent Lamps
Basic Principles of Light Control
Types of Lighting Scheme
Design of Lighting Scheme
Factory Lighting
Street Lighting
Flood Lighting

Light is the prime factor in human life.
All activities ultimately depend upon the light.
Artificial light is used in absence of natural light.
Artificial light due to its cleanliness, ease of control, reliability, steady output, low cost is playing a great role in our lives.
Science of illumination engineering is, therefore,  becoming of major importance.

4.Nature of Light:
Light is a form of radiant energy.
Depends on the temperature of bodies emitting them.
Heat of the body can be classified as red hot or white hot.
When the temperature increases, the body changes from red hot to white hot.
Higher the temperature of the body, lower the wavelength of radiant energy, and higher the radiant efficiency.

The sensation of color is due to the difference in wavelengths of the light radiations.
Visible light can have a wavelength between 4,000Aº  and 7,500Aº.

6.Relative Sensitivity:
Sensitivity of the eye to the lights of different wavelengths varies from person to person and according to the age.
Eye has greatest sensitivity for wavelengths of about 5,500Aº
The relative sensitivity at any particular wavelength ? is written as k? and known as relative luminosity factor.

It differs from light very much.

Light is the cause and illumination is the result of that light on surfaces on which it falls.

8.Terms Used in Illumination
Light: defined as radiant energy.
Luminous Flux: defined as total quantity of light energy emitted per second from a luminous body.
Luminous Intensity: it is the luminous flux emitted by the source per unit angle.
Lumen: it is the unit of luminous flux.
Candle Power: it is the light radiating capacity of the source in a given direction. Denoted by CP.
Illumination: when light falls upon any surface, it is called illumination.
Lux or Metre Candle: it is the unit of illumination.
Candela: it is the unit of luminous intensity.

9.Mean Horizontal Candle Power (MHCP): it is the mean of candle powers in all directions in horizontal plane containing source of light.
Mean Spherical Candle Power (MSCP): it is the mean of candle powers in all directions and in all planes from source of light.
11. Mean Hemi-Spherical Candle Power (MHSCP): it is the mean of candle powers in all directions above or below the horizontal plane.
12. Reduction Factor:
13. Lamp Efficiency: ratio of luminous flux to the power input.

10.Laws of Illumination:
Law of Inverse Squares: if a source of light which emits light equally in all directions be placed at the centre of a hollow sphere, the light will fall uniformly on the inner surface of the sphere, that is to say, each square mm of the surface will receive the same amount of light.

11.Lambert’s Cosine Law:
   The illumination at any point on a surface is proportional to the cosine of the angle between the normal at that point and the direction of luminous flux.

The candle power of a source in any given direction is measured by comparison with a standard or substandard source employing photometer bench and some form of photometer.
Photometer bench essentially consists of two steel rods which carry the stands or saddles for holding the two sources.
The principle of most of the methods of measurement is based upon inverse square law.

13.Types of Photometers:
Most common type of photometers are:
Bunsen Grease Spot Photometer: consists of a piece of tissue paper with grease spot in the centre.
Flicker Photometer: used when two sources giving light of different colors are to be compared.

14.Measurement of Illumination
The best method of measuring illumination is by a portable type illumination photometer calibrated to read directly in lux.
No shadow should be allowed to fall on the meter during measurements.
Meter should be held perfectly horizontal and stationary for accurate results.
Meter should be color corrected type so that it can be used for all kinds of light sources.

15.Sources of Light:
Light sources may be grouped as:
Arc Lamps
High Temperature Lamps
Gaseous Discharge Lamps
Fluorescent Type Lamps 

PPT On Introduction To SENTENCES


Introduction To SENTENCES Presentation Transcript:

Two complete thoughts run together with not enough sign of a break b/w them.

Two complete thoughts run together with not enough sign of a break b/w them.

Fused Sentences
Comma splice

5.Fused sentences
Completely joined together .
I looked outside it was sunny.
Ali loves to draw sceneries he is a talented artist.

6.Comma splice
Expect comma to do the work of a period.
She yawned, she was very tired.
I got up late this morning, I  did not have time for breakfast.

7.Identification of run-on sentences
Read it aloud!!
Look at the sentence…
I drive she walks.
I drive. She walks.

8.Ways to fix run-on sentence:
 Periods and Capital letter
Comma and Co-ordinating conjunction
Sub-ordinate clauses
Conjunctive Adverbs.

9.period and capital letter:
Use period and capital letter to break a sentence in two independent clauses.
Incorrect form:
 Ali is a nice boy he really loves animals.
Correct form:-
Ali is a nice boy. He really love animals.

10.Comma and Co-ordinating Conjunction:
Make a compound sentence using comma and co-ordinating conjunction.
Co-ordinating conjunctions:
Incorrect form:-
The night was cold we forget to bring our coats .
Correct form:-
 The night was cold, and we forget to bring our coats.

11.Sub-ordinate clauses:
Determine if one or more clauses  of the independent clauses can be sub ordinated. Add a dependent word.
Sub-ordianate words:

Incorrect form:-
Ali and Ahmed like football but Hamza does not.
Correct form:-
 Although Ali and Ahmed like football, Hamza does not.

13.Semi colon :
 Use a semi colon which works like a period if one explains the other.
 Incorrect form :
It was a beautiful day  there was not a cloud in a sky.
Correct form:
 It was a beautiful day ; there was not a cloud in the sky.

14.Conjunctive adverb:
 Determine the independent clauses by using transitional word/conjunctive adverb.
Conjunctive adverbs:

 Incorrect :
 I expected him to return it I was wrong.
I expected him to return it , however ,
I was wrong.

PPT On Implementation of Analog and Digital Filters


Implementation of Analog and Digital Filters Presentation Transcript:
1. implementation of Analog and Digital Filters

2.MATLAB implementation of Analog and Digital Filters

3.What are Filters and their Types?
What is meant by Analog Filters?
How to implement RC Low Pass Filter using MATLAB
How to implement RC High Pass Filter using MATLAB
What are Digital Filters and their types?
How to design FIR Low Pass Filter?
How to design FIR High Pass Filter?
How to design FIR Band Pass Filter?
MATLAB implementation of Butterworth IIR Low Pass Filter?

4.Filters and their Types

5.Analog Filters

6.RC Low Pass Filter with Cutoff 200Hz

7.RC High Pass Filter with Cutoff 200Hz

8.Comparison of Low Pass & High Pass

9.Digital Filters and its types
10.FIR Low Pass Filter with Cutoff 1200Hz
fs=8000; % sampling frequency
n=50; % order of the filter
w=1200/ (fs/2);
b=fir1(n,w,'low'); % Zeros of the filter

11.FIR High Pass Filter with Cutoff 1200Hz
w=1200/ (fs/2);

12.FIR Band Pass Filter with Pass Band 1200--1800Hz
b=fir1(n,[1200/4000 1800/4000],'bandpass');

13.Butterworth IIR Low Pass Filter
 % finding the order of the filter
 % finding zeros and poles for filter
[h,q] = freqz(b,a,512,8000);

Filters and their basic Types
Analog Filters
MATLAB implementation of RC Low Pass and High Pass Filters
Digital Filters and their types
MATLAB implementation of FIR Low Pass, High Pass and Band Pass Filter
MATLAB implementation of Butterworth IIR Low Pass Filter

PPT On Electric Welding


Electric Welding Presentation Transcript:
1.Power Distribution & Utilization

2.Contents To Be Covered:
Gas Welding
Resistance Welding
Electric Arc Welding
Ultrasonic Welding
Electron Beam Welding
Laser Beam Welding
Power Supply For Resistance Welding
Power Supply For Arc Welding
Comparison Between Resistance And Arc Welding

Welding is a materials-joining process.
Produces coalescence of materials by heating them to the welding temperature.
Almost, all metals can be joined by welding.

It is the most efficient way to join metals.
Widely employed for manufacturing or repairing.
The expense of using bolts and rivets can be reduced.
Used extensively in automobile industry, aircraft machine frames, structural work, tanks, machine repair work, ship building etc.

5.Advantages & Disadvantages:
It is the lowest-cost joining method.
Affords lighter weight.
Joins all commercial materials.
Can be used anywhere.
Provides design flexibility.
Often needs internal inspection.
Some welding depends on human factor.

6.Personnel Protection & Safety Rules:
Combustible materials must not be allowed to collect in or near the welding work place.
Good house keeping practices should always be employed.
Adequate safety devices should be provide.
Only approved equipment should be used.
Proper maintenance of equipment should be done.

7.Classification Of Welding Processes:
It can be classified into:
Gas Welding
Resistance Welding
Arc Welding
Thermit Welding
Solid State Welding
Newer Welding

8.Gas Welding:
Oxygen-Acetylene Welding:
Oxygen tank (green)
Acetylene tank (red, or black with a red top)
Oxygen pressure valves have a right-hand internal thread
Acetylene pressure valve has an external left-hand thread.
An oxygen-acetylene flame is very hot, approaching 3500°F.

9.Fusion weld is to place the two pieces against each other and melt their surfaces together.
Reducing flame is used to melt low-melting-point metals and alloys because it does not oxidize or corrode the metals.
Neutral flame is the hottest one possible and is the proper adjustment for welding.
Oxidizing flame that can cause corrosion in the metal. It is only used for cutting flames or burning pieces of metal from a piece of stock.

10.Types Of Gas Welding:
Oxygen-Hydrogen Welding
The oxygen-hydrogen torch can reach temperatures much higher than the oxy-acetylene torch.
More expensive than oxy-acetylene welding and involves the flammability risk with hydrogen.
Plasma Welding
Hydrogen plasma burns even hotter than hydrogen gas, permitting the welding of extremely high-melting-point metals.
Very clean procedure that results in very little slag or foreign matter in the weld.

11.Resistance Welding:
It is the process in which a sufficiently strong electric current is sent through the two metal pieces in contact to be welded which melts the metals by the resistance they offer to the flow of electric current.
It includes:
Butt Welding
Spot Welding
Projection Welding
Seam Welding
Percussion Welding

12.Butt Welding:
The butt weld consists of two pieces of metal together either on face or on edge.
It is of two types.
Upset Butt Welding
Flash Butt Welding

13.Upset Butt Welding
It is resistance welding process that produces coalescence over the entire area of surfaces.
It can be used only if the parts to be welded are equal in cross-sectional area.
The faces of the metal pieces to be joined are prepared for even contact.
When sufficient heat is developed, a pressure is applied to complete the weld and the pressure is removed after cooling.
Voltage required for welding is 2-8 volts and current required varies from 50A to several thousand Amperes. 

14.Flash Butt Welding:
It may be defined as a resistance welding process that produces coalescence at the surfaces of a butt joint by flashing action.
No special preparation of the faces to be welded is necessary.
Voltage to the metal parts to be joined is applied before putting them together which gives rise to a small arc hence the name Flash Butt welding.
It causes whole of the surfaces to be heated to welding or forging temperature.
When the forging temperature is reached pressure is applied and power supply is cut off.

15.Spot Welding:
Spot welding is usually employed for joining or fabricating sheet metal structure.
This type of joint only provides mechanical strength and is not air or water tight.
The plates to be welded are placed overlapping each other between two electrodes.
Sufficient mechanical pressure is applied through the electrodes.
The welding current flows through electrodes tips producing a spot weld.
The welding current and period of current flow depend on the thickness of the plates.

PPT On Electric Heating


Electric Heating Presentation Transcript:
1.Power Distribution & Utilization

2.Contents to be Covered
Modes of Transfer of Heat
Classification of Electric Heating Methods
Resistance Heating
Arc Furnaces
Induction Heating
Dielectric Heating

Heating is required for domestic purposes as well as industrial purposes.
Industrial applications include
Melting of Metals
Case Hardening

4.Main Advantages of Electric Heating
Absence of Flue Gases
Ease of Control
Automatic Protection
Upper Limit of Protection
Special Heating Requirement
High Efficiency of Utilization
Better Working Conditions

5.Modes of Transfer of Heat

In this mode of transfer of heat, one molecule of the substance gets heated and transfer the heat to the adjacent and so on.
Rate of conduction of heat along a substance depends upon temperature gradient.

7.Convection is the movement of molecules within fluids (i.e. liquids, gases).
It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids.

Radiation is a process in which energetic particles or energy or waves travel through a medium or space.

In this mode of transfer of heat, one molecule of the substance gets heated and transfer the heat to the adjacent and so on.
Rate of conduction of heat along a substance depends upon temperature gradient.

10.Convection is the movement of molecules within fluids (i.e. liquids, gases).
It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids.

11. Radiation is a process in which energetic particles or energy or waves travel through a medium or space.

12.Classification of Electric Heating:
It can be classified as:
Direct Resistance Heating
Indirect Resistance Heating
Infra-red or Radiant Heating
Arc Heating
Direct Induction Heating
Indirect Induction Heating
Dielectric Heating

13.Resistance Heating:
It is based upon the I2R effect.
Has wide applications in heat treatment of metals, drying, baking of potteries, stoving of enamelled ware and domestic cooking.
Temperature upto 1000 celsuis can be obtained in ovens.
Two common methods of resistance heating are
Direct Resistance Heating
Indirect Resistance Heating

14.Direct Resistance Heating:
It is accomplished by the dissipation of an electric current in a material.
Material to be melted is placed inside a furnace with electrodes in the walls.
Alternating or direct electric current is then passed between the electrodes through the material.
Resistance losses are dissipated as heat, causing the material to melt.

High efficiency.
It gives uniform heat and high temperature.
It is mainly used in salt bath furnace and water heaters.

PPT On Dijkstra’s Algorithm

PPT On Corruption In Pakistan


Corruption In Pakistan Presentation Transcript:
1.Corruption In Pakistan

 First of all we must define the corruption. Apparently, it would look like suspicious financial transaction alone. But that is too narrow view. Corruption today has become a way of life and it encompasses the ideological, moral and ethical values of society.

3. Pakistan has one of the highest rates of corruption in the entire world. Bribe Payers Survey 2010 carried out by Transparency Intl. showed that the actions
of the government  in Pakistan’s fight against corruption were seen as ineffective by 72%  people whereas same the value for India stood at 42%. The survey also revealed the institutions considered to be the most corrupt shown

4.Eradicate Corruption

5.Eliminating Corruption:
 Decentralized Independent Judiciary:
The  judiciary  system  should  be  at  the  federal, province and city state level. The provincial and city  appointments should  be  under  the control of  local  government.
Federal government must abdicate healthcare & education  ministries  completely  to  the provincial, city and district governments.
 Provincial Election Commission:
Every province should have its  own independent Election commission.  A  central election commission is a disaster and an instrument which has always been used  for rigging purposes by the establishment.

6.No Provincial or Central control on Police:
Police should be completely under the control of city Government. Police used for rigging the elections and targeting the Opposition. By decentralization this police will only work on criminal cases.
 Education system:
Children should  be morally  taught  in  school to treat  corruption  as  a  sin. Lying  should  be punished  and  lying  under  oath  should  be treated as a high crime. Lying is an epidemic in Pakistan.
 Role of the CM and provincial assembly:
Their Job is to make state laws and implement them e.g. in state of Texas, USA which is roughly the size of Pakistan, Governor’s office is in Austin but he has no control over  Austin police. The department is under the Mayor of Austin.

7. Salaries:
Pays should be determined completely by city Government.
 Strongest District attorneys:
Justice System needs to be implemented at Union council, city, district Government and state level. District attorneys should have the right to prosecute anyone in their jurisdiction without any pressure.
Universal pay scale for all  the federal employees:
Government of USA does not pay for any of their President’s personal expenses. Clinton paid  all the costs of the Monica Lewinsky trial. The system should be
similar in Pakistan.

8. Abolishing the position of President & Governors from constitution:
This is an extra burden on the Tax payers and instrument for Martial law . If decentralization is properly implemented there is no need for a
President to oversee the units of federation. Time has proven repeatedly that the presidential structure
ironically has always been the cause of the
federation’s weakening, former President Musharraf  &  Ghulam Ishaq  Khan are evident proofs.
 Reporting Corruption:
An easy and practical system must be implemented in the country to ensure that ordinary citizens can report incidents of corruption. Several mediums like toll free
numbers, television, mail, etc should be widely advertised as a means for getting to
 the appropriate authorities. To date we do not have a proper system to report corruption.

A  systemic disease if not treated properly causes a multi organ failure. This is exactly what has happened in Pakistan. Corruption is widespread &  hopelessness is slowly taking Over.
All evil in this  world starts with injustice, in  our case  since  1947  Pakistan’s  centralized government has been a source of this injustice.
It is  about  time  People  of  Pakistan  get  their equal rights regardless of  race, culture, religion and language.
future government  should  base  its policies  and  the  future  government  on  just principles.

PPT On Network Security


Network Security Presentation Transcript:
1.Network Security

Introduction to Cryptography
Substitution Ciphers
Transposition Ciphers
One-Time Pads
Two Fundamental Cryptographic Principles

3.Need for Security

4.An Introduction to Cryptography

5.One-Time Pads
The use of a one-time pad for encryption and the possibility of getting any possible plaintext from the ciphertext by the use of some other pad.

6.Symmetric-Key Algorithms
DES – The Data Encryption Standard
AES – The Advanced Encryption Standard
Cipher Modes
Other Ciphers

7.AES – The Advanced Encryption Standard
Rules for AES proposals
The algorithm must be a symmetric block cipher.
The full design must be public.
Key lengths of 128, 192, and 256 bits supported.
Both software and hardware implementations required
The algorithm must be public or licensed on nondiscriminatory terms.

8.Electronic Code Book Mode

9.Cipher Feedback Mode

10.Public-Key Algorithms
Other Public-Key Algorithms

11.Digital Signatures
Symmetric-Key Signatures
Public-Key Signatures
Message Digests
The Birthday Attack

12.Symmetric-Key Signatures

13.Management of Public Keys
Public Key Infrastructures

14.Problems with Public-Key Encryption

15.Communication Security
Virtual Private Networks
Wireless Security

PPT On Magnetic Forces Materials And Inductance


Magnetic Forces Materials And Inductance Presentation Transcript: 
1.Magnetic Forces, Materials, & Inductance

2.Magnetic Field
A bar magnet has a magnetic field around it. This field is 3D in nature and often represented by lines LEAVING north and ENTERING south
To define a magnetic field you need to understand the MAGNITUDE and DIRECTION
We sometimes call the magnetic field a B-Field as the letter “B” is the SYMBOL for a magnetic field with the TESLA (T) as the unit.

3.Magnetic Force on a moving charge
If a MOVING CHARGE moves into a magnetic field it will experience a MAGNETIC FORCE. This deflection is 3D in nature.

4.Lorentz Force Equation
The force on a moving particle arising from both Electric and Magnetic fields.
C is the speed of light.

5.Lorentz Force Equation
Electron Orbits in Magnetron.
Proton Paths in cyclotron.
Plasma Characteristics in MHD generator.
Charge particle motion in both combined Electric and Magnetic Fields.

6.Force on a Differential Current Element
Assume two current loops

7.Force on a Differential Current Element

8.Force and Torque on a closed circuit


10.Force and Torque on a closed circuit
If B is uniform on the loop current , then the net force is zero (no displacement)
If B is not uniform, the net force is not always zero
The magnetic field causes a Torque on the loop
This torque will try to make the magnetic field due to the loop current in the same direction of the external magnetic field B

11.Force and Torque on a closed circuit

12.The Nature of Magnetic Materials
Materials have a different behavior in magnetic fields
Accurate description requires quantum theory
However, simple atomic model (central nucleus surrounded by electrons) is enough for us
There are 3 magnetic dipole moments:
1. Moment due to rotation of the electrons
2. Moment due to the spin of the electrons
3. Moment due to the spin of the nucleus

13.We will study 6 types:
Super paramagnetic

14.Diamagnetic Materials
Without an external magnetic field, diamagnetic materials have no net magnetic field
With an external magnetic field, they generate a small magnetic field in the opposite direction
The value of this opposite field depends on the external field and the diamagnetic material

15.Atoms have a small net magnetic dipole moment
The random orientation of atoms make the average dipole moment in the material zero
Without an external field, there is no magnetic property 

PPT On Introduction To Network Layer


Introduction To Network Layer Presentation Transcript: 
1.The Network Layer

2.Network Layer Design Isues
Store-and-Forward Packet Switching
Services Provided to the Transport Layer
Implementation of Connectionless Service
Implementation of Connection-Oriented Service
Comparison of Virtual-Circuit and Datagram Subnets

3.Store-and-Forward Packet Switching

4.Implementation of Connectionless Service

5.Implementation of Connection-Oriented Service

6.Comparison of Virtual-Circuit and Datagram Subnets

7.Routing Algorithms
The Optimality Principle
Shortest Path Routing
Distance Vector Routing
Link State Routing
Hierarchical Routing
Broadcast Routing
Multicast Routing
Routing for Mobile Hosts
Routing in Ad Hoc Networks

8.The Optimality Principle

9.Shortest Path Routing

10.Link State Routing
Each router must do the following:
Discover its neighbors, learn their network address.
Measure the delay or cost to each of its neighbors.
Construct a packet telling all it has just learned.
Send this packet to all other routers.
Compute the shortest path to every other router.

11.Learning about the Neighbors

12.Measuring Line Cost

13.Building Link State Packets

14.Distributing the Link State Packets

15.Routing in Ad Hoc Networks
Possibilities when the routers are mobile:
Military vehicles on battlefield.
No infrastructure.
A fleet of ships at sea.
All moving all the time
Emergency works at earthquake .
The infrastructure destroyed.
A gathering of people with notebook computers.
In an area lacking 802.11.

PPT On The Medium Access Control Sublayer


The Medium Access Control Sublayer Presentation Transcript:
1.The Medium Access Control Sublayer

2.The Channel Allocation Problem
Static Channel Allocation in LANs and MANs
Dynamic Channel Allocation in LANs and MANs

3.Dynamic Channel Allocation in LANs and MANs
Station Model.
Single Channel Assumption.
Collision Assumption.
(a) Continuous Time. (b) Slotted Time.
(a) Carrier Sense. (b) No Carrier Sense.

4.Multiple Access Protocols
Carrier Sense Multiple Access Protocols
Collision-Free Protocols
Limited-Contention Protocols
Wavelength Division Multiple Access Protocols
Wireless LAN Protocols

5.Pure ALOHA

6.Persistent and Nonpersistent CSMA

7.CSMA with Collision Detection

8.Collision-Free Protocols

9.Limited-Contention Protocols

10.Adaptive Tree Walk Protocol

11.Wavelength Division Multiple Access Protocols

12.Wireless LAN Protocols

Ethernet Cabling
Manchester Encoding
The Ethernet MAC Sublayer Protocol
The Binary Exponential Backoff Algorithm
Ethernet Performance
Switched Ethernet
Fast Ethernet
Gigabit Ethernet
IEEE 802.2: Logical Link Control
Retrospective on Ethernet

14.Ethernet Cabling

15.Ethernet MAC Sublayer Protocol

PPT On The Physical Layer


The Physical Layer Presentation Transcript: 
1.The Physical Layer

2.The Theoretical Basis for Data Communication
Fourier Analysis
Bandwidth-Limited Signals
Maximum Data Rate of a Channel

3.Bandwidth-Limited Signals

4.Guided Transmission Data
Magnetic Media
Twisted Pair
Coaxial Cable
Fiber Optics

5.Twisted Pair

6.Fiber Optics
Three examples of a light ray from inside a silica fiber impinging on the air/silica boundary at different angles.
(b) Light trapped by total internal reflection.

7.Transmission of Light through Fiber

8.Fiber Cables
(a) Side view of a single fiber.
(b) End view of a sheath with three fibers.

9.Wireless Transmission
The Electromagnetic Spectrum
Radio Transmission
Microwave Transmission
Infrared and Millimeter Waves
Lightwave Transmission

10.The Electromagnetic Spectrum

11.Radio Transmission
(a) In the VLF, LF, and MF bands, radio waves follow the curvature of the earth.
(b) In the HF band, they bounce off the ionosphere.

12.Politics of the Electromagnetic Spectrum

13.Lightwave Transmission
Convection currents can interfere with laser communication systems. 
A bidirectional system with two lasers is pictured here.

14.Communication Satellites
Geostationary Satellites
Medium-Earth Orbit Satellites
Low-Earth Orbit Satellites
Satellites versus Fiber

15.Communication Satellites
Communication satellites and some of their properties, including altitude above the earth, round-trip delay time and number of satellites needed for global coverage. 

PPT On Uses of Computer Networks


Uses of Computer Networks Presentation Transcript: 

2.Uses of Computer Networks
Business Applications
Home Applications
Mobile Users
Social Issues

3.Business Applications of Networks

4.Home Network Applications
Access to remote information
Person-to-person communication
Interactive entertainment
Electronic commerce

5.Home Network Applications

6.Network Hardware
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Wireless Networks
Home Networks

7.Broadcast Networks
Types of transmission technology
Broadcast links
Point-to-point links

8.Local Area Networks

9.Metropolitan Area Networks

10.Wide Area Networks

11.Wireless Networks
Categories of wireless networks:
System interconnection
Wireless LANs
Wireless WANs

12.Home Network Categories
Computers (desktop PC, PDA, shared peripherals
Entertainment (TV, DVD, VCR, camera, stereo, MP3)
Telecomm (telephone, cell phone, intercom, fax)
Appliances (microwave, fridge, clock, furnace, airco)
Telemetry (utility meter, burglar alarm, babycam).

13.Network Software
Protocol Hierarchies
Design Issues for the Layers
Connection-Oriented and Connectionless Services
Service Primitives
The Relationship of Services to Protocols

14.Network Software Protocol Hierarchies

15.Design Issues for the Layers
Error Control
Flow Control

PPT On Power Distribution Equipments


Power Distribution Equipments Presentation Transcript: 
1.Power Distribution & Utilization

2.Contents To Be Covered
Circuit Breakers & their Types
Lightening protection
Protective Relay Introduction
Disconnect Switches
Metering Equipment

Circuit breakers are high voltage, high current devices that automatically disconnect faulted equipment to protect people, prevent damage to equipment and minimize the effects of damage.
Range in size from 125V,15A to over 800kV,thousands of Amperes.

4.Arc in Circuit Breakers:
Opening of the contacts of circuit breaker causes ionization of gas present between contacts, as a result, producing arc.
It is due to the presence of high electric field between the current carrying contacts.
Severe in case of inductive loads(Mostly Industrial & faulted lines).
Arc must be extinguished to interrupt the current in case of Fault.

5.Methods to Extinguish Arc:
Firstly, by lengthening the arc which causes  rise in resistance, drop in current & temperature rise, thus reducing the arc.
Using an arc quenching medium e.g Air, Oil or an Insulating gas.
DC arcs are harder to break than Ac, but can be extinguiushed using the same principles.

6.Methods used to break the arc in air are:
Arc Trip
Arc Horn
Interrupting Fins

It causes an arc, which is hot, to rise if the contacts are properly oriented.
Increased surface area is exposed to cooler air due to stretching in rising arc, causing its temperature to drop.
Longer an arc can be drawn, easier it is to extinguish.

8.Arc Tip:
Arc tips, also called arcing contacts, break after the main contacts break.
Prevents pitting of the main contacts.
Works on same principle as Convection.
Only difference is that, it spreads the arc further, thus making it extinguish earlier.

9.Interrupting Fins:
These are placed in the path of rising arc.
Stretch the arc further
Cool it more
Extinguish it faster.

10.Types of Circuit Breakers Air Circuit Breakers:
Use air as arc interrupting medium.
Used mostly as low voltage breakers.
These are driven open by strong springs compressed by rachet mechanism.

11.Air Blast Circuit Breakers:
Special purpose medium voltage breakers.
Used at voltages between 14.4kV and 34.5kV.
Blast of compressed air(800 psi) is blown across breaker contacts as they are open.
Opening mechanism is provided by powerful springs.
Contacts are closed either by a motor or compressed air.
Must have a resistor across the arc to dampen high voltage oscillations which may re-ignite the arc.

12.Vacuum Circuit Breakers:
Contacts are enclosed in a container with a high vacuum.
No significant arcing can occur because no air is present to be ionized.
Operated by spring force.
Available for voltages from 480V to 34.5V.

13.Oil Circuit Breakers:
Use oil as arc interrupting medium.
Oil has a dielectric strength far in excess of air.
Opening of contacts in oil causes the oil to disassociate which absorbs energy.
Hydrogen is used as a product of disassociation.
Can be used up to voltage levels of 230kV.
Use of arcing chamber increases capacity by a factor of 500, to 10,000 MVA.

14.Sulphur Hexaflouride(SF6) Circuit Breakers:
SF6 is used as an arc quenching medium.
Used for extremely high voltage(EHV, above 345kV) applications.
These are usually live tank designs supported on insulators.

15.Circuit Breaker Ratings:
User must consider a number of ratings to select a circuit breaker.
Continuous Voltage Rating(Decrease at altitudes above 3000 ft.).
Rated Impulse Voltage.
Continuous Current Rating.
Maximum Fault Current.
Interrupting Time.
Mechanical considerations such as size, foundation and space required.

PPT On Distribution Substations


Distribution Substations Presentation Transcript: 
1.Power Distribution & Utilization

2.Distribution Substations
To lower the voltage from the high voltage transmission and sub-transmission levels to a voltage that can be safely installed on the streets.

3.Substation Layout Selection Criteria
It depends on many factors.
Load Requirements
Expected Growth
Available Site Space
Location Of Site
Protection System Sophistication & Cost
Other Stations In The General Area
The design of a substation depends on both the sub-transmission and/or transmission voltages available.

4.Voltage And Spacing
Voltage determines the spacing between the conductors and conductor clearance to ground.
Minimum clearances are 22.3 inches for 34.5kV and 13.2 inches for 12.5kV for rigid buses with fixed supports.

The size of the load to be served determines the capacity of substation.
Industrial and commercial loads are served by large substations.(More reliable and contains more than one transformer)
Critical loads such as industrial districts are served by more complex substations designed for maximum reliability and speed of power restoration.

6.Space And Location:
More space allows more construction options.
Densely populated areas may contain few locations suitable for substation construction.
Cost of the land must also be high.
GIS may have to be used in such cases.

7.Distribution Substation Protection Needs:
The level of protection of a substation is determined by how critical the loss of power is to the load.
Loss of power to a hospital or to industrial and commercial areas can result in severe damages, both to human life and economy.
Fault removal must be fast
Automatic switching should be used to decrease the repair time.

8.Construction Methods
Four basic methods exist for substation construction.
Steel Lattice
Steel Low Profile

Wood pole substations are inexpensive.
Can easily use wire bus structures.
Wood is suitable only for small and simple substations.
Very few wood substations are built anymore.

10.Lattice Steel:
It provides structures of low weight and high strength.
Multilevel bus structures can be fabricated.
It is reasonably economical and preferable.

11.Lattice Steel Structure for Grid Station

12.Solid Steel Low Profile:
Superior to lattice or wood.
More expensive than either wood or steel.
Requires more land because multilevel bus structures can not be used.

It is a recent development.
It is factory built and tested.
Shipped in modules and bolted together at sites.
Completely enclosed in metal cladding to deny access to unqualified individuals.

14.Trends In Distribution Substations:
It is difficult to add small increments of capacity to large substations economically.
Maximum economy is realized when low voltage feeder mileage is kept as low as possible.
Smaller substations allow a lower mix of high and low voltage lines, more economical, simpler design, construction and relaying is easier. 

15.Insulation Coordination:
A typical method is to establish a definite common level for all insulation in the station.
Bring all equipment and devices to that insulation level.
Lightening protection is set at least 20% below this level, but above normal peak operating voltages.



CAPITAL BUDGETING Presentation Transcript:

2.Capital Investment Decisions
 Outcome is uncertain.
 Investment involves a long-term commitment.
Capital budgeting: Analyzing alternative long- term investments and deciding which assets to acquire or sell.
 Decision may be difficult or impossible to reverse.
 Large amounts of money are usually involved.

3.Capital Investment Decisions

4.Capital Investment Decisions: Typical Cash Outflows

5.Capital Investment Decisions: Typical Cash Inflows

6.Capital Investment Decisions: Nonfinancial Considerations

7.Evaluating Capital Investment Proposals:  An Illustration

8.Evaluating Capital Investment Proposals:  An Illustration
Stars’ Stadium is considering purchasing vending machines with a 5-year life.

9.Evaluating Capital Investment Proposals:  An Illustration
Most capital budgeting techniques use annual net cash flow.
 Depreciation is not a cash outflow.

10.Payback Period
The payback period of an investment is the time expected to recover the initial investment amount.

11.The payback period of an investment is the time expected to recover the initial investment amount.

12.Payback Period

13. Consider two projects, each with a five-year life and each costing $6,000.

14.Return on Average Investment (ROI)
  ROI focuses on annual income instead of cash flows.

15.  ROI focuses on annual income instead of cash flows.

PPT On Modifier


Modifier Presentation Transcript: 


3. A modifier is a word, phrase, or clause that describes or changes the meaning of another word, phrase or clause in some way.
  The tall man with the hat sat under the palm tree.

Misplaced modifiers
  Dangling modifiers

5. Misplaced modifier means that there is a separation of space between the word, phrase or clause and the modifier.
           When a modifier is misplaced, your meaning gets really fuzzy.

6. How do I Fix it?
          Revise the sentence, taking care to put
modifying words, phrases, and clauses in a
position that clearly identifies the headword
and that does not awkwardly interrupt a

7. What Was Stolen?
The stolen man’s wallet  was placed on the police department’s counter. (incorrect)
The man’s stolen wallet  was placed on the police department’s counter.  (correct)

8.Consider an other example
   I nearly made 1000 today.
   I made nearly 1000 today.

9.On her way to work, Hina saw the silver
   woman’s earring laying on the park bench.
 On her way to work, Hina saw the woman’s
   silver  earring laying on the park bench.

10. A DANGLING MODIFIER  is a word or
phrase that modifies a word NOT CLEARLY
STATED  in the sentence.
Leaving quickly, my car lights were left on.
In selecting her next car, cost was determined by Sarah’s pay cheque.

     Change the main part of the sentence so it
begins with the term actually modified.
                       This change will put the modifier next to the
   term it modifies.  Name the appropriate or logical doer of the action as the subject of the main clause:
Looking toward the west, a funnel shaped cloud stirred up dust. (Incorrect)
Looking toward the west, I saw a funnel shaped cloud stir up dust. (Correct)

12. Change the dangling modifier phrase to a subordinate clause, creating a subject and verb.
Leave the rest of the sentence as it is.
Having been fixed the night before, Farhan could use the car. (Incorrect)
Since the car had been fixed the night before, Farhan could use it. (Correct)

13. Combine the phrase and main clause into one:
With dangling modifier:
To improve his results, the experiment was done again.(Incorrect)
He improved his results by doing the experiment again.(Correct)

PPT On Introduction To Cyber Crime


Introduction To Cyber Crime Presentation Transcript: 
Types of cyber crime
How do we become a victim?
Prevention of being a victim.
Conclusion .

2.Modern age
Like there was a Stone Age and ice age, currently we are
 living in information age. We are surrounded by information,
 weather it is a school college university industry hospitals or
 government agencies very one is dealing with information.

3.Digitalized information
 Next import thing to understand is that this information is no more a paper based information. It has been digitalized. We have been storing information on computers hardisks, flash drives and many other storage mediums.

4.New era of internet
Until then it was not quite an issue
but then we step into the era of internet, where the
 information happens to be flying over offices cities
countries and continents. All the information transfer
started using transfer protocols like http ftp and their
were Ip and subnets involved. We grew our network to
 large extent and this leads us to vulnerability.

5.Security of digitalized information
With all this evolving around us by
time we understood the importance
of information security. It became a
great deal to secure all digitalized
information. Information security
raised many issues. Secure and
encrypted transfer of data or
communication over the wires and
wireless mediums, Individual or
personal data integrity and many
other such stuff was needed to be

6.What is a cyber crime?
With all this happening the world was introduced with a
 cyber crime. World first ever virus was developed by
Pakistanis world was known to another threat to
 information i.e. Cyber Crime. Cyber crime is termed as
 any crime that
involves a computer
 and a network,
 where the computers
 may or may not
 have played an
 instrumental part in the
commission of a crime. .

7.Types of cyber crime
• HACKING:An illegal intrusion into computer without 
permission of owner  is called hacking
• Email bombing :This kind of activity refers to sending
large numbers of mail to the victim, which may be an
 individual or a company or even mail servers there by
 ultimately resulting into crashing.

8.Types of cyber crime
Salami Attacks: In such crime criminal makes insignificant changes in such a manner that such changes would go unnoticed.
Denial of service attacks:The computer of the victim is flooded with more requests than it can handle which cause it to crash.

9.Virus: Viruses are programs that attach themselves to a computer or a file and then circulate themselves to other files and to other computers on a network. They usually affect the data on a computer, either by altering or deleting it.
Trojan attacks:     In software field this means an unauthorized programme, which passively gains control over another’s system by representing itself as an authorised programme.


11.How do we become a victim?
1.Beware of Phishing
Phishing is a new model cyberspace attack, in which the attacker masquerades a genuine entity and tricks you into providing important user information such as credit cards, account user names, passwords, etc.
Usually phishing starts with an email or an instant message, asking you to furnish important details or to ‘verify’ your account with the genuine entity Unsuspecting users, thus, may provide the original user name and password in this website and make themselves victims of the
 phishing attack (and may still remain
 unsuspecting). Once given, the phishing
 entity has a direct door opened to your
 personal information and your identity

12.How do we become a victim?
The term identity theft is used to refer to a fraud, wherein an individual pretends to be someone else, in order to gain some or the other benefits he is not rightfully entitled to. people using the Internet for financial transaction give out personal information, such as the date of birth or social security number, online. Sometimes they click on suspicious links or e-mails promising a hefty prize money which in turn provides way for identity

A person is first informed about a large amount of money languishing in some bank account in a remote country. This first contact is made via phone calls, fax and now, through e-mails. They are then told that the amount has to be transferred into the country, and asked whether they would let them use his or her bank account. Once a person agrees to such a transaction, they are then informed of delays due to government red tape. Finally, they are asked for a loan to pay off some bribes to government officials. After months of paying off small and large amounts, it finally transpires that there was never any money, gold or any other valuables that were first described in the original e-mail. mail. The person therefore stands to lose vast amounts of money. In some cases, people have also provided their bank passwords, only to have their entire accounts cleaned out

Sometimes  users get an e-mail account that seems to have come from a company they regularly do business with, and  asking for information that users. have already given them, in such cases users don’t try to contact with company ignoring that it can be fraudlent note and, the sender will
    then know that user’s  e-mail
    address is a valid one
    and he may be opening himself up
    to still moreunwanted e-mails from

A Trojan horse, or Trojan, is malware that appears to perform a desirable function for the user prior to run or install but instead facilitates unauthorized access of the user's computer system. "It is a harmful piece of software that looks legitimate. Users are typically tricked into loading
     and executing it on their systems"

PPT On Angle Modulation


Angle Modulation Presentation Transcript:
1.Angle Modulation

2.This scheme is called Frequency Shift Keying (FSK) where information digits are transmitted by keying different frequencies.

3.Bandwidth of Angle Modulated Waves

4.Generation of NBFM

A better bandwidth estimate is:
For a truly wideband case,
The “deviation ratio” plays a role similar to the “modulation index” in AM.   

PPT On VSB Modulation


VSB Modulation Presentation Transcript:
1.Carrier Acquisition

2.Phase Locked Loop (PLL)


4.Carrier Acquisition in DSB-SC

5.Angle Modulation 



DCCN Presentation Transcript: 
1.Introduction DCCN

What is a network?
Digital transmission
Components of a network
Network hardware
Network software
Network standards

3.What is a network?
“an interconnected collection of autonomous computers”
    interconnected = able to exchange information
“a set of nodes connected by media links”
    node = any device capable of sending / receiving data to/from other nodes in the network
“a connected collection of hardware and software that permits information exchange and resource sharing”
    information = data, text, audio, video, images, …
    resources = printers, memory, link bandwidth, ...

4.Networks vary in:
type: Ethernet, Cable TV, telephone network, Internet, cellular…
size: from a few computers close together, to a world-wide network of networks containing millions of computers
technology: copper wire, coaxial cable, wireless, fibre optics…
technical issues: services offered, rules for inter-computer communications, how users are charged for network use...

5.Why all these variations?
historical reasons
different operating environments
lack of (sensible) standards
difficult problems ?no optimal solutions
different target applications

6.Uses of Computer Networks
Companies and Organizations
Private Individuals

7.Companies and Organizations
resource sharing: programs, equipment, data…
high reliability: multiple processors/links/file copies/...
scalability: gradually improve system performance
rapid communications & remote cooperation saving money

8.Client Server Model

9. Private Individuals
Person-to-person communication

10.Digital transmission
all information represented by bits(only values are 0 and 1).
more resistant to noise, which unpredictably changes transmitted values.
basic idea: transmit two very different signals for 0 and 1.
even if these signals are corrupted during transmission, they should still be distinguishable–and as long as the destination can distinguish 0 and 1.
in addition, extra bits (not part of the information to be transmitted) can be added in order to reduce noise effects
    e.g. automatically correct bit errors.
may require analog-to-digital / digital-to-analog conversions (e.g. if input/output information is in analog form).

11.Components of a network
Components of a network
•message: information to be communicated
•sender: device that sends the message
•receiver: device that receives the message
•medium: physical path from sender to receiver
•protocol: set of rules that govern data communications

12.Network hardware
Transmission technology
•broadcast networks: single communication channel shared by all network nodes
can send to: one node, all nodes, (maybe) group of nodes
•point-to-point networks: many possible connection paths between any pair of nodes
message may have to pass through intermediate nodes on the way from sender to receiver
usually, need a routing algorithm to decide if a path exists from sender to receiver, and --if multiple such paths exist --which one(s)to use

13.Network Scale

14.Local Area Networks (LANs)
restricted size
low propagation delay(e.g. small fractions of a second)
high speed(e.g. 10 Mbps up to 1 Gbps and beyond)
low error rate

15.Metropolitan Area Networks (MANs)
bigger version of wired broadcast LANs
may be a means of connecting multiple LANs 

PPT On Network Basics


Network Basics Presentation Transcript:
1.Network Basis

Types of communication services   
Implementation of communication services
Network performance measures

3.Types of service
establish a connection
use the connection (for data transfer)
release the connection
modeled on the telephone system
essential feature: sender pushes objects (e.g. bits, packets) in one end of the connection, and receiver takes them out in the same order at the other end

each message is sent independently from the sender to the receiver
modeled on the postal service
essential features: each message must include the receiver’s address, and messages can be received in a different order to the order in which they were transmitted

5.Each type of service is characterized by its reliability.
whether or not the service guarantees to correctly deliver the data
Reliable service: receiver confirm to the sender that it correctly received each message (which introduces extra overhead and delays)
Reliable connection-oriented service has 2 variations:
message stream: preserves message boundaries
    (e.g. 2 1-kBmessages are received as 2 1-kBmessages, not1 2-kBmessage, 4 512-byte messages, or anything else)
byte stream: doesn’t preserve message boundaries
            (e.g. 2 1-kBmessages are received as a 2048-byte stream)
Unreliable connection-oriented service
e.g. real-time audio or video: tolerates some errors or losses in transmission (quality decreases as errors/losses increase)

6.Connectionless service can be unreliable(no 100% delivery guarantee), acknowledged(receipt confirmed), or request-reply(a single short message contains a request, another the reply)

7.a single network could offer more than one type of service
e.g. the Internet supports all of them, more or less
may have different implementations of the same service
e.g. connection-oriented delivery of a voice bit stream can be implemented by packet voice or a dedicated circuit

8. Implementation of Communication Services
It is economically infeasible to directly connect every pair of sender-receiver pairs (e.g. mesh or star) in a large network
Network resources must be shared between the users, while still allowing senders to transmit data to their receivers

9.Basic Techniques of Connectivity
Two basic techniques that permit connectivity while sharing resources are switching and multiplexing
switching: sharing network resources among multiple transmissions
multiplexing: sharing a single link among multiple transmissions

10.Types of switching
Circuit Switching
Packet Switching
Datagram packet switching
Virtual circuit packet switching

11.Circuit Switching
a path is set up in the network between the sender and the receiver (by making the appropriate connections in the switches)
the necessary network resources are reserved for the connection prior to any data transfer; if this is not possible, the connection request is blocked
these reserved resources are then held for the duration of the connection links are not shared at the same time
the links in a path are monopolized for the duration of the connection, then released so that they are available for other connections
circuit switching is ideal for “smooth” network traffic
e.g. telephone network

13.if the traffic from sender to receiver is “bursty” (varies widely around its average value)
computer-to-computer traffic can be very bursty
could set up a new circuit for each burst
could hold original circuit for duration of data transfer
both of these solutions are wasteful of network resources

14.packet = string of bits (up to a few thousand, typically)
uses store-and-forward operation

15.Types of Packet Switching
Two types of packet switching
Datagram packet switching
Virtual circuit packet switching

PPT On Three Phase Circuits


Three Phase Circuits Presentation Transcript:
1.Three-phase circuits

Almost all electric power generation and most of the power transmission in the world is in the form of three-phase AC circuits. A three-phase AC system consists of three-phase generators, transmission lines, and loads.
Major advantage of three-phase systems over a single-phase system:
Power delivered to a three-phase load is constant at all time, instead of pulsing as it does in a single-phase system.

3.Generation of three-phase voltages and currents

4.Each of three-phase generators can be connected to one of three identical loads.
This way the system would consist of three single-phase circuits differing in phase angle by 1200.
The current flowing to each load can be found as

5.Generation of three-phase voltages and currents

6.We can connect the negative (ground) ends of the three single-phase generators and loads together, so they share the common return line (neutral).

7.Such three-phase power systems (equal magnitude, phase differences of 1200, identical loads) are called balanced.
Phase Sequence is the order in which the voltages in the individual phases peak.

8.Such three-phase power systems (equal magnitude, phase differences of 1200, identical loads) are called balanced.
In a balanced system, the neutral is unnecessary!
Phase Sequence is the order in which the voltages in the individual phases peak.

9.Voltages and currents
Each generator and each load can be either Y- or ?-connected. Any number of Y- and ?-connected elements may be mixed in a power system.
Phase quantities - voltages and currents in a given phase.
Line quantities – voltages between the lines and currents in the lines connected to the generators.

10.Voltages and currents

11.Magnitudes of the line-to-line voltages and the line-to-neutral voltages are related as:
In addition, the line voltages are shifted by 300 with respect to the phase voltages.
In a  connection with abc sequence, the voltage of a line leads the phase voltage.

12.For the connections with the abc phase sequences, the current of a line lags the corresponding phase current by 300 (see Figure below).
For the connections with the acb phase sequences, the line current leads the corresponding phase current by 300.

13.Analysis of balanced systems
We can determine voltages, currents, and powers at various points in a balanced circuit.
Consider a Y-connected generator and load via three-phase transmission line.
For a balanced Y-connected system, insertion of a neutral does not change the system.
All three phases are identical except of 1200 shift. Therefore, we can analyze a single phase (per-phase circuit).
Limitation: not valid for ?-connections…

14.A ?-connected circuit can be analyzed via the transform of impedances by the Y-? transform. For a balanced load, it states that a ?-connected load consisting of three equal impedances Z is equivalent to a Y-connected load with the impedances Z/3. This equivalence implies that the voltages, currents, and powers supplied to both loads would be the same.

15.Example 3-1:
for a 208-V three-phase ideally balanced system, find:
the magnitude of the line current IL;
The magnitude of the load’s line and phase voltages VLL and V?L;
The real, reactive, and the apparent powers consumed by the load;
The power factor of the load.
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