k-Wave

1. serieslover
   

   Member
   Joined: Oct '22
   Posts: 2

   I have simulated a small object in water grids. But i get repeated peak-valleys of simulated data along with sensor dimension.Also i have tried difference objects like sphere, horizontal rectangles resulting same problems.
   Here is the object image
   
   And here is the resulting sensor-timestep image
   
   Besides that i have tried to move the sensors order in sensor.mask circulatively, and i get the peak-valleys of simulated data also moved circulatively.
   I have no idea about this, and doubt is it concerned to the calculation procedures? below is the code

   radius = 11; % mm
   dx = 0.05; % mm
   dy = 0.05; % mm
   Nx = 2 * radius / dx + 1;
   Ny = 2 * radius / dy + 1;
   zlength = 10; % mm
   dz = 0.1; % mm
   Nz = zlength / dz;

   % % generate k-wave grids
   kgrid = kWaveGrid(Nx, dx*1e-3, Ny, dy*1e-3);
   kgrid.Nt = 1000;
   kgrid.dt = 2.5e-8;

   % % % acoustic pressure
   gruneisen_parameter = 0.02;
   source.p0 = gruneisen_parameter * squeeze(absorption_coefficient(:,:,Nz/2)) .* squeeze(grid_fluence(:,:,Nz/2)) * 1e3;

   % % sound speed and medium density
   medium.sound_speed = 1501 * ones(Nx, Ny);
   medium.density = 1000 * ones(Nx, Ny);

   % % sensor settings
   num_sensor = 1024;
   sensormask_xy = makeCartCircle((radius-0.2)*1e-3, num_sensor);
   sensormask_xy = [sensormask_xy(1,129:end),sensormask_xy(1,1:128);sensormask_xy(2,129:end),sensormask_xy(2,1:128)];

   % % generate source data arrays
   zstopmargin = 0.5; % mm
   zstop = zlength / zstopmargin;
   % for i=1:zstop
   for i=fix(zstop/2):fix(zstop/2)
   sensor.mask = [sensormask_xy(1,:);sensormask_xy(2,:)];
   % sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor,'PMLAlpha',0);
   sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor);
   end
   figure,imshow(source.p0(:,:),[]),title('source.p0 2D')
   sdata_single = sensor_data;
   figure,imshow(sdata_single,[]),title('sensor_data 2D')

   Posted 2 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   I can't run your code as absorption_coefficient isn't defined. If you're after details of how k-Wave works under the hood, you can take a look in the user manual.

   Posted 2 years ago #

3. serieslover
   

   Member
   Joined: Oct '22
   Posts: 2

   sorry for missing some of the codes, i post updated version with similar problem below.
   the intensity variation along sensor dimension.

   radius = 11; % mm
   dx = 0.05; % mm
   dy = 0.05; % mm
   Nx = 2 * radius / dx + 1;
   Ny = 2 * radius / dy + 1;
   zlength = 10; % mm
   dz = 0.1; % mm
   Nz = zlength / dz;

   % % generate k-wave grids
   kgrid = kWaveGrid(Nx, dx*1e-3, Ny, dy*1e-3);
   kgrid.Nt = 1000;
   kgrid.dt = 2.5e-8;

   % % % acoustic pressure
   gruneisen_parameter = 0.02;
   absorption_coefficient = 0.01*ones(Nx, Ny);
   absorption_coefficient(((Nx+1)/2-10):((Nx+1)/2+10), ((Ny+1)/2-10):((Ny+1)/2+10)) = 0.2;
   source.p0 = gruneisen_parameter * absorption_coefficient;
   source.p_mask = zeros(size(source.p0));
   source.p_mask(((Nx+1)/2-10):((Nx+1)/2+10), ((Ny+1)/2-10):((Ny+1)/2+10)) = 1;

   % % sound speed and medium density
   medium.sound_speed = 1501 * ones(Nx, Ny);
   medium.density = 1000 * ones(Nx, Ny);
   medium.sound_speed(((Nx+1)/2-10):((Nx+1)/2+10), ((Ny+1)/2-10):((Ny+1)/2+10)) = 1488;

   % % sensor settings
   num_sensor = 1024;
   sensormask_xy = makeCartCircle((radius-0.2)*1e-3, num_sensor);
   sensormask_xy = [sensormask_xy(1,129:end),sensormask_xy(1,1:128);sensormask_xy(2,129:end),sensormask_xy(2,1:128)];

   % % generate source data arrays
   zstopmargin = 0.5; % mm
   zstop = zlength / zstopmargin;
   % for i=1:zstop
   for i=fix(zstop/2):fix(zstop/2)
   sensor.mask = [sensormask_xy(1,:);sensormask_xy(2,:)];
   % sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor,'PMLAlpha',0);
   sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor);
   end
   figure,imshow(source.p0(:,:),[]),title('source.p0 2D')
   sdata_single = sensor_data;
   figure,imshow(sdata_single,[]),title('sensor_data 2D')

   Posted 2 years ago #

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