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The MATLAB source code for the Sparse Signal Recovery in the Presence of Noise collection.


The following is the MATLAB source code for each of the components of our project.


function out = addNoise(sig,mean,sd,Plot) %addNoise%adds noise with given mean and sd to the signal rand=randn(1,1000)*sd+mean;out=sig+rand; if(Plot==1)plot(1:1000,out,1:1000,sig); endend


function out = sample(sd,plot,sig) %sample%samples a manually constructed signal, and adds gaussian noise to it %with a standard deviation that is providedout=fft(addNoise(sig,0,sd,plot)); end


function [out,samp]=init(sig,sd)%averages the signal and the noise over a number of samples to make the %noise level manageableout=sig+randn(1,1000).*sd; %optimize number of samplesif sd<76 val=6.25;else val=9;end samp=floor((ceil(sd))^2/(val));for n=2:samp out=(out.*(n-1)+sig+randn(1,1000).*sd)/n;end out=fft(out);end


function [mask, NSig,runT] = simpleIterate(sigMask,threshold,run,n,sd,sig)%simpleIterate(sigMask,threshold,run,n) %computes an iteration of the thresholding, with a running average of run,%on iteration n, with the current signal mask of sigMask %returns the new signal mask, the current signal(non-masked) NSig and the%running average of the signal runT siz=size(sigMask);temp=zeros(1,siz(2)); for i=1:4NSig=sample(sd,0,sig).*sigMask; if(n==1)runT=NSig; elserunT=(run.*(n-1)+NSig)/n; end%temp=temp+(max(abs(real(NSig)),abs(imag(NSig)))>threshold); temp=temp+(max(abs(real(runT)),abs(imag(runT)))>threshold); %temp=temp+(abs(NSig)>threshold); endmask=zeros(1,siz(2)); for l=1:siz(2)if(temp(l)<2) mask(l)=0;else mask(l)=sigMask(l);end endend


function [flag,samples,time]=testArbitrary(sig,sd)%Simulates the transmission of a signal in the library, and tests whether %or not it can be recovered.siglib=cat(1,sin(0:pi/500:(1000*pi-1)/500),sin(0:pi/250:(2000*pi-1)/500),sin(0:pi/125:(4000*pi-1)/500),sin(0:pi/50:(10000*pi-1)/500),sin(0:pi/25:(20000*pi-1)/500)); siglib=cat(1,siglib,sin(0:pi/500:(1000*pi-1)/500)+sin(0:pi/50:(10000*pi-1)/500),cos(0:pi/500:(1000*pi-1)/500),cos(0:pi/250:(2000*pi-1)/500),cos(0:pi/125:(4000*pi-1)/500),cos(0:pi/50:(10000*pi-1)/500));siglib=cat(1,siglib,cos(0:pi/25:(20000*pi-1)/500),cos(0:pi/25:(20000*pi-1)/500)+sin(0:pi/500:(1000*pi-1)/500),sin(0:pi/500:(1000*pi-1)/500)+sin(0:pi/125:(4000*pi-1)/500)+cos(0:pi/25:(20000*pi-1)/500)); sigmax=max(abs(fft(siglib(sig,:))));threshhold=sigmax-3*max(abs(real(fft(randn(1,1000))))); tolerance=.5;A=ones(1,1000); flag=0;tic [C,samples]=init(siglib(sig,:),sd); for i=1:10000[A,B,C]=simpleIterate(A,threshhold,C,i+samples,sd,siglib(sig,:));for j=1:size(siglib) if(abs(ifft(A.*C)-siglib(j,:))<tolerance) flag=j;break; endend if(flag>0) break;end endsamples=samples+i; time=toc;end


function accepted = Controller(enteredpassword,sd) %Tests whether or not a transmission of a password will activate the system%This simulates the noise and processing as well as the values actualpassword=cat(1,13,5,10,4,2,8);accepted=1; redundancy=3;for i=1:size(actualpassword); flag=0;%while flag==0 for j=1:redundancy [flag,runs]=testArbitrary(enteredpassword(i),sd); endif(flag~=actualpassword(i)) accepted=-i;break; endend end


function Controller2() %Helper function used to graph trendssig=1; for sd=0:30passed=0; for reps=1:50if(testArbitrary(sig,3+sd/10)==sig) passed=passed+1;end endtemp(sd*10-29)=passed endsubplot(1,1,1); plot(temp);end

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
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Damian Reply
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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for screen printed electrodes ?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Source:  OpenStax, Sparse signal recovery in the presence of noise. OpenStax CNX. Dec 14, 2009 Download for free at http://cnx.org/content/col11144/1.1
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