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Magnatic field in surface coil for overlapping conductor

1 次查看（过去 30 天）
Dhafer
Dhafer 2013-3-6
Dear All
Please can you help urgently
I do not know where is the error.
clear all close all condition = 1;
while (condition)
L = input('Please enter the grid length and size [l s]: ');
N = L(2); l = L(1); dl = l/N;
miu0 = 4*pi*1e-7/1000;
I1 = 1; I2 = -1; width = 1/dl;
%%Grid Calculations.
offset = input('Please enter the position for wire 1 in cm: ');
offset = ceil(offset/dl);
overlap = input('Please enter the %age Overlap between two coils: ');
overlap = overlap*N/100;
n_slices = input('Please enter the number of slices: ');
loc = input('Please enter the location of the first slice in mm: ');
loc = ceil(loc/(10*dl));
x= -N/2:N/2;
y=-N/2:N/2;
% Setting Location of the wire points.
p11 = offset;
p12 = p11+width;
mid1 = p11+width/2;
mid2 = mid1 + ceil((1-overlap/100)*width);
p21 = mid2-width/2;
p22 = p21+width;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if ((p11<0) || (p12<0) || (p21<0) || (p22<0) || (p11>N+1) || (p12>N+1) || (p21>N+1) || (p22>N+1))
disp('%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%')
disp('Wires do not fit on the grid, Please enter new dimensions')
disp('%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%')
else
condition = 0;
for i = 1: length(x)
for j = 1: length(y)
% Calculating distance vectors
r1(i,j) = sqrt((x(p11) - x(i))^2 + (y(j))^2);
r2(i,j) = sqrt((x(p12) - x(i))^2 + (y(j))^2);
r3(i,j) = sqrt((x(p21) - x(i))^2 + (y(j))^2);
r4(i,j) = sqrt((x(p22) - x(i))^2 + (y(j))^2);
end
end
%Calculating magentic fields
B1 = (miu0*I1)./(2*pi*r1);
B2 = (miu0*I2)./(2*pi*r2);
B3 = (miu0*I2)./(2*pi*r3);
B4 = (miu0*I1)./(2*pi*r4);
B = B1+B2+B3+B4;
% Selecting reference axis
Ref_axis = B(N/2+1:N,p21+ceil((p12-p21)/2));
test_lines = B(128:256,128:256);
test_avg_H = sum(test_lines,2)/128;
test_avg_V = sum(test_lines,1)/128;
%%%%%Taking slices of the Signal Decay %%%
Brain = test_avg_V(loc:ceil(loc+5.5/(10*dl)));
l_Brain = length(Brain);
new_dim = ceil(l_Brain/n_slices);
new_Brain = padarray(Brain,[0 new_dim*n_slices-l_Brain],0,'post');
l_Brain = length(new_Brain);
pulses = zeros(l_Brain,n_slices);
sig = reshape(new_Brain, [new_dim n_slices]);
slices = (sig(ceil(length(sig)/2),:)); % Taking mid-point of each rectangular pulse.
slices = (slices);
for i = 1:n_slices
pulses((i-1)*l_Brain/(n_slices)+1:l_Brain/(n_slices)*i,i) = slices(i);
fft_pulses(:,i)=fftshift(fft(pulses(:,i))); % moving the zero-frequency component to the center of the array
Nf=length(fft_pulses(:,i)); %to take the frquecny axis of the hoarmonics.
n=-(Nf-1)/2:(Nf-1)/2; %divide the frequency compone
f(:,i)=sqrt(fft_pulses(:,i).*conj(fft_pulses(:,i))); % to take the amplitude of each hoarmony.
figure;
plot(f(:,i));
title('Fourier Transform of the pulses');
xlabel('frequency ');
ylabel('Amplitude');
end
pulses = padarray(pulses,loc,0,'pre');
pulses = padarray(pulses,100,0,'post');
%Plotting figures
figure;
bar(pulses,5,'hist');
hold on
plot(test_avg_V);
% figure % plot(pulses) % hold on % plot(flipud(test_avg_V)); figure; plot(f); figure; plot(test_lines') title('test lines') figure; plot(test_avg_V); title('Magnetic Field Decay Ratio'); xlabel('Distance on y-axis'); ylabel('B1');
figure
surf(x,y,B);
view(0,90);
colorbar;
xlabel('x');
ylabel('y');
title('B1 Profile');
end
end
Regards
Dhafer

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回答（1 个）

Youssef Khmou
Youssef Khmou 2013-3-6
hi,
delete this portion :
L = input('Please enter the grid length and size [l s]: ');
N = L(2); l = L(1);
And replace it with :
N = input('Please enter the grid length :');
l=input('Enter the grid size');
  3 个评论
显示 1更早的评论
Youssef Khmou
Youssef Khmou 2013-3-6
编辑：Youssef Khmou 2013-3-6
hi Dhafer , the new error is not technical , but its about the conception of the code or the entered values, i think the error is
1) Matrix dimensions must agree or
2) Index exceeds

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