Holographic Memory

Holographic data storage is a potential technology in the area of high-capacity data storage currently dominated by magnetic and conventional optical data storage. Magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium. Holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage.

Holographic data storage contains information using an optical interference pattern within a thick, photosensitive optical material. Light from a single laser beam is divided into two separate optical patterns of dark and light pixels. By adjusting the reference beam angle, wavelength, or media position, a multitude of holograms (theoretically, several thousand) can be stored on a single volume.

The stored data is read through the reproduction of the same reference beam used to create the hologram. The reference beam’s light is focused on the photosensitive material, illuminating the appropriate interference pattern, the light diffracts on the interference pattern, and projects the pattern onto a detector. The detector is capable of reading the data in parallel, over one million bits at once, resulting in the fast data transfer rate. Files on the holographic drive can be accessed in less than 200 milliseconds.

Holographic Memory





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Matlab for beginners continue...

Here are some example to understand the discrete function in signal system engineering.....

% Plot unit step sequence , sinusoidal sequence exponential sequence
% to generate a unit step sequence
N= 31;
x1 =  ones(1,N);   % the one give 1 by N matrix of ones
n = 0:1:N-1;
subplot(2,2,1),stem(n,x1);  % stem is use to plot descret point
xlabel('n'),ylabel('x_1(n)');
title('Unit Step Sequence');   % title command give the title of graph
axis([0 30 0 2]);

%sinusoidal sequence
x2= 2*cos(.1*pi*n);
subplot(2,2,2),stem(n,x2);
xlabel('n'),ylabel('x_2(n)');
title('Sinusoidal Sequence');

%Exponetial Sequence
x3= 0.6.^(n);
subplot(2,2,3),stem(n,x3);
xlabel('n'),ylabel('x_3(n)');
title('Exponential Sequence');

% Addition of two sinusoidal sequence
x4 = sin(.5*pi*n)+ sin(.25*pi*n)
subplot(2,2,4),stem(n,x4);
xlabel('n'),ylabel('x_4(n)');
title('Addition of two Sequence');

% plot a typical exponental sequence a^n when 1. 0<a<1 ,2. -1<a<0...
...3. a>1, 4. a<-1
 
clear all;
a= .8
n= -10:1:10;
x1 = a.^n;
subplot(2,2,1),stem(n,x1);
xlabel('n'),ylabel('x_1(n)');

a=-0.8;
x2 = a.^n;
subplot(2,2,2),stem(n,x2);
xlabel('n'),ylabel('x_2(n)');

a=1.15;
x3 = a.^n;
subplot(2,2,3),stem(n,x3);
xlabel('n'),ylabel('x_3(n)');

a= -1.15;
x4 = a.^n;
subplot(2,2,4),stem(n,x4);
xlabel('n'),ylabel('x_4(n)');

THYRISTOR

The thyristor is a four-layer, three terminal semiconducting device, with each layer consisting of alternately N-type  or P-type material, for example P-N-P-N. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications. They stay on once they are triggered, and will go off only if current is too low or when triggered off. The SCR is the most widely used and important member of the thyristor family. The SCR is almost universally referred to as thyristor. Common areas of application for SCRs are  Time-delay circuits, regulated power suppliers, static switches, motor controls choppers, battery charger and heater controls. Etch..

Thyristors can take many forms, but they have certain things in common. All of them are solid state switches which

act as open circuits capable of withstanding the rated voltage until triggered. When they are triggered, thyristors

 become low−impedance current paths and remain in that condition until the current either stops or drops below a minimum value called the holding level. Once a thyristor has been triggered, the trigger current can be removed without turning off the device. Silicon controlled rectifiers (SCRs) and triacs are both members of the thyristor family. SCRs are unidirectional devices where triacs are bidirectional. An SCR is designed to switch load current in one direction, while a triac is designed to conduct load current in either direction. Structurally, all thyristors consist of several alternating layers of opposite P and N silicon, with the exact structure varying with the particular kind of device. The load is applied across the multiple junctions and the trigger current is injected at one of them. The trigger current allows the load current to flow through the device, setting up a regenerative action which keeps the current flowing even after the trigger is removed. These characteristics make thyristors extremely useful in control applications. Compared to a mechanical switch, a thyristor has a very long service life and very fast turn on and turn off times. Because of their fast reaction times, regenerative action and low resistance once triggered, thyristors are useful as power controllers and transient overvoltage protectors, as well as simply turning devices on and off. Thyristors are used in motor controls, incandescent lights, home appliances, cameras, office equipment, programmable logic controls, ground fault interrupters, dimmer switches, power tools, telecommunication equipment, power supplies, timers, capacitor discharge ignitors, engine ignition systems, and many other kinds of equipment.

THYRISTOR


Here i give a proper format of seminar on topic Thyristor. The report file of this ppt also enclosure with the ppt at ELECTRODATA

Download PPt and report

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MATLAB for beginners

MATLAB ( MATrix LABoraory ) is a high - performance language for high efficiency  Engineering and scientific numerical calculations. It was original developed to provide easy acces to matrix software developed by the LINPACK and ESIPACK matrix computation software . The MATLAB environment allows us to integrate user freindly tools with superior computational  capabilities . As a result , MATLAB is one of the most useful tools for Scientific and Engineering calculation and Computing.

You can use MATLAB in a wide range of applications, including signal and image processing, communications, control design, test and measurement, financial modeling and analysis, and computational biology.

To the beginner it's my suggestion that the download  the Matlab and keep practice with the problem . The Matlab Help is fully compatible to the new user and  it explains every funtion with example. Here i give some Practice to generate a continuous signal . To understand the MATLAB window see the Getting Start MATLAB tutorial in HELP. I have also linked the Introduction to Matlab ppt on my post .

% To plot a continoius time signal                          /% is use before comment

%1 sinusoidal signal
clear all;                   % it removes all variables from the workspace, releasing them from system memory.
T = 0.2;        % time period in sec
t= -1:0.01:1;    % generate a time index with interval of 0.01
x1 =  sin(2*pi*t/T);        % sine function
subplot(2,2,1),plot(t,x1);      % it create a matrix form of the plot (row column position )     
xlabel('\itt'),ylabel('x_1(\itt)');    % xlabel and ylable is use for label the axis

%2 exp signal
x2 = exp(-2*t);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');

% 3 sawtooth signal
t1 = -20:0.01:20;
x3 =  sawtooth(t1);
subplot(2,2,3), plot(t1,x3)
xlabel('\itt'),ylabel('x_3(\itt)');

% 4 suare signal
x4 = square (t1);
subplot(2,2,4),plot(t1,x4);
xlabel('\itt'),ylabel('x_4(\itt)');
axis([-20 20 -1.5 1.5]);     % this command provide range of axis [xmin xmax ymin ymax] in matrix form


% plot countinious signals
% 1 sinc function
clear all;
t = -20:0.01:20;
x1 =  sinc(t/2);
subplot(2,2,1),plot(t,x1);
xlabel('\itt'),ylabel('x_1(\itt)');
axis([-20 20 -1.5 1.5]);

%2 rectanfular signal
x2 = rectpuls(t/10);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');
axis([-20 20 -1.5 1.5]);

% 3 triangular signal
x3 =  tripuls(t/10);
subplot(2,2,3), plot(t,x3)
xlabel('\itt'),ylabel('x_3(\itt)');
axis([-20 20 -1.5 1.5]);

% 4 signum signal
x4 = sign(t/3)
subplot(2,2,4),plot(t,x4);
xlabel('\itt'),ylabel('x_4(\itt)');
axis([-20 20 -1.5 1.5]);


% plot prdouct of two function
% 1
clear all;
t = -2:0.01:2; T = .2; T1=4;
x1 = sin(2*pi*t/T).*exp(-2*t);                           % for the product of two function we use
                                                                              Multiplication: Element-wise(.*) operator
subplot(2,2,1),plot(t,x1);
xlabel('\itt'),ylabel('x_1(\itt)');

%2 rectanfular signal
T2= .3; T3=2;
x2 = 2*cos(2*pi*t/T2).*sin(2*pi*t/T3);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');

% 3 triangular signal
x3 =  sin(2*pi*t/T).*exp(-2*t) + sin(2*pi*t/T1).*exp(-4*t);
subplot(2,2,3), plot(t,x3)
xlabel('\itt'),ylabel('x_3(\itt)');

% 4 signum signal
x4 = sinc(t).*sin(2*pi*t/T);
subplot(2,2,4),plot(t,x4);
xlabel('\itt'),ylabel('x_4(\itt)');

to create a function x= y(t) such that 

y(t) = t+5 when -5<t<=-2

      = 11 +4t when -2 <t<= 1

     =  24-9t  when 1<t<=3

     =  t-6  when 3<t<=6

Program

function x =y(t)

x1 = t+5; x2 = 11 + 4*t; x3 = 24 - 9*t; x4= t-6;

x = x1.*(-5<t&t<=-2) + x2.*(-2<t& t<=1) + x3.*(1<t&t<=3) + x4.*(3<t&t<=6);

%this  file is save with .m extension which is a function file now the y(t) work as function you can use it in  your own program.  To use it first it must be included in your working directory 

How to use this created function is explain by the following program

clear all;

tmin= -15 ; tmax= 20;

t= tmin:0.1:tmax;

y0 = y(t);

y1 = y(t+4);

y2 = 2*y(t-3);

y3 = y(2*t);

y4 = y(2*t-3);

y5 = y(t/2);

ymax = max([max(y0),max(y1),max(y2),max(y3),max(y4),max(y5)]);

ymin = min([min(y0),min(y1),min(y2),min(y3),min(y4),min(y5)]);

subplot(3,2,1), plot(t,y0);

xlabel('\itt'),ylabel('y_0(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,2), plot(t,y1);

xlabel('\itt'),ylabel('y_1(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,3), plot(t,y2);

xlabel('\itt'),ylabel('y_2(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,4), plot(t,y3);

xlabel('\itt'),ylabel('y_3(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,5), plot(t,y4);

xlabel('\itt'),ylabel('y_4(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,6), plot(t,y5);

xlabel('\itt'),ylabel('y_5(\itt))');

axis([tmin tmax ymin ymax]);

Nano Sensor

Nanosensors are any biological, chemical, or surgical sensory points used to convey information about nanoparticles to the macroscopic world. Their use mainly include various medicinal purposes and as gateways to building other nanoproducts, such as computer chips that work at the nanoscale and nanorobots

Nano Sensors


PPT of this seminar topic is avaliable at ELECTRODATA

A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analyzing the barcode's image data provided by the sensor and sending the barcode's content to the scanner's output port.

Laser Bar Code Scanner, Opti696D Fall 2008



Types of barcode readers  technology

The reader types can be divided as follows: There are various type of Bar Code Reader Technology

Pen-type readers
Pen-type readers consist of a light source and photodiode that are placed next to each other in the tip of a pen or wand. To read a bar code, the person holding the pen must move the tip of it across the bars at a relatively uniform speed. The photodiode measures the intensity of the light reflected back from the light source as the tip crosses each bar and space in the printed code. The photodiode generates a waveform that is used to measure the widths of the bars and spaces in the bar code. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is a representation of the bar and space pattern in the bar code. This waveform is decoded by the scanner in a manner similar to the way Morse code dots and dashes are decoded.

Laser scanners
Laser scanners work the same way as pen type readers except that they use a laser beam as the light source and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. As with the pen type reader, a photodiode is used to measure the intensity of the light reflected back from the bar code. In both pen readers and laser scanners, the light emitted by the reader is rapidly varied in brightness with a data pattern and the photodiode receive circuitry is designed to detect only signals with the same modulated pattern.

CCD readers
CCD readers use an array of hundreds of tiny light sensors lined up in a row in the head of the reader. Each sensor measures the intensity of the light immediately in front of it. Each individual light sensor in the CCD reader is extremely small and because there are hundreds of sensors lined up in a row, a voltage pattern identical to the pattern in a bar code is generated in the reader by sequentially measuring the voltages across each sensor in the row. The important difference between a CCD reader and a pen or laser scanner is that the CCD reader is measuring emitted ambient light from the bar code whereas pen or laser scanners are measuring reflected light of a specific frequency originating from the scanner itself.

Camera-based readers
Two-dimensional imaging scanners are the fourth and newest type of bar code reader. They use a camera and image processing techniques to decode the bar code.
Video camera readers use small video cameras with the same CCD technology as in a CCD bar code reader except that instead of having a single row of sensors, a video camera has hundreds of rows of sensors arranged in a two dimensional array so that they can generate an image.
Large field-of-view readers use high resolution industrial cameras to capture multiple bar codes simultaneously. All the bar codes appearing in the photo are decoded instantly (ImageID patents and code creation tools) or by use of plugins (e.g. the Barcodepedia uses a flash application and some web cam for querying a database), have been realized options for resolving the given tasks.

Omni-directional barcode scanners
Omni-directional scanning uses "series of straight or curved scanning lines of varying directions in the form of a starburst, a lissajous pattern, or other multiangle arrangement are projected at the symbol and one or more of them will be able to cross all of the symbol's bars and spaces, no matter what the orientation."[1]
Omni-directional scanners almost all use a laser. Unlike the simpler single-line laser scanners, they produce a pattern of beams in varying orientations allowing them to read barcodes presented to it at different angles. Most of them use a single rotating polygonal mirror and an arrangement of several fixed mirrors to generate their complex scan patterns.
Omni-directional scanners are most familiar through the horizontal scanners in supermarkets, where packages are slid across a glass or sapphire window. There are a range of different omni-directional units available which can be used for differing scanning applications, ranging from retail type applications with the barcodes read only a few centimetres away from the scanner to industrial conveyor scanning where the unit can be a couple of metres away or more from the code. Omni-directional scanners are also better at reading poorly printed, wrinkled, or even torn barcodes.


To download the PPT visit the ELECTRODATA

A digital signature or digital signature scheme is a mathematical scheme for demonstrating the authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, and that it was not altered in transit. Digital signatures are commonly used for software distribution, financial transactions, and in other cases where it is important to detect forgery or tampering.

Digital Signature

Digital signatures are often used to implement electronic signatures, a broader term that refers to any electronic data that carries the intent of a signature,[1] but not all electronic signatures use digital signatures.[2][3] In some countries, including the United States, India,[4] and members of the European Union, electronic signatures have legal significance.

Digital signatures employ a type of asymmetric cryptography. For messages sent through a nonsecure channel, a properly implemented digital signature gives the receiver reason to believe the message was sent by the claimed sender. Digital signatures are equivalent to traditional handwritten signatures in many respects, but properly implemented digital signatures are more difficult to forge than the handwritten type. Digital signature schemes in the sense used here are cryptographically based, and must be implemented properly to be effective. Digital signatures can also provide non-repudiation, meaning that the signer cannot successfully claim they did not sign a message, while also claiming their private key remains secret; further, some non-repudiation schemes offer a time stamp for the digital signature, so that even if the private key is exposed, the signature is valid. Digitally signed messages may be anything representable as a bitstring: examples include electronic mail, contracts, or a message sent via some other cryptographic protocol.

This PPT is created by the Controller of Certifying Authorities .To download the ppt please visit ELECTRODATA

Introduction to Matlab

Intoduction to Matlab

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Recent Advances in Display Technlogy

Recent Advances in Display Technlogy

Download Link of above Seminar Topic is given in ELECTRODATA

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Speed Controller For DC Motor

Speed control for dc motor (electric motor) can be implemented using open loop or closed loop. Closed loop controller, also known as servo controller, or a feedback control, gives the best performance since the loop will maintain the actual speed to follow the reference. In simple application, an open loop controller can be enough if the load is constant, such as in fan control (PC fan speed control). This dc motor control circuit uses PWM (pulse width modulation), gives a better efficiency than using linear driver. Here is the schematic diagram of this PWM motor controller. The LM/NE 555 timer is use to generate the PWM pulse which duty cycle is control by the potentiometer use in the circuit.

The report and transient response is download by electrodata.

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DESIGINING OF OVERHEATING ALARM USING 555 TIMER IC

The overheating alarm is use for detecting a high temperature in any system where it is use. It contains a buzzer which is on when a system attain a temperature level. It is simple circuit which have easily installation. Overheat alarm circuit consists a thermistor i.e. a heat sensor which detects the raise on heat and within some mechanism buzzer produces sound. We know thermistor is a kind of resistor,used as heat sensor which offers low resistance at high temperature and high resistance at low temperature and the same concept is used here for detecting overheat. The difference in values of op amp 324 inverting and non inverting terminal voltages  decides the switching on and off for the circuit to drive IC 555 for generating pulse train which produce beep alarm by buzzer.. At normal temperature, the resistance of the Thermistor is approximately 10 kilo-ohms, which reduces to a few ohms as the temperature increases beyond 100 C. The circuit uses readily available components and can be easily constructed on any general-purpose PCB.

                                    

Here i give the link of the report file regarding of this minor project     

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