k-Wave

1. HustYjq
   

   Member
   Joined: Jul '20
   Posts: 20

   Hi，
   Can anyone tell me how to define source.p as a matrix? I load the image and get the source.p0 as a matrix.But i don't know how to define source.p as a martix with the same size as source.p0.

   p0_magnitude = 1;
   p0 = p0_magnitude * loadImage('150mev.png');

   % create the computational grid
   Nx = 128; % number of grid points in the x (row) direction
   Ny = 128; % number of grid points in the y (column) direction
   dx = 0.1e-3; % grid point spacing in the x direction [m]
   dy = 0.1e-3; % grid point spacing in the y direction [m]
   kgrid = kWaveGrid(Nx, dx, Ny, dy);

   % resize the image to match the size of the computational grid and assign
   % to the source input structure
   source.p0 = resize(p0, [Nx, Ny]);

   % define the properties of the propagation medium
   medium.sound_speed = 1500; % [m/s]
   medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
   medium.alpha_power = 1.5;

   % define a time varying sinusoidal source
   source_freq = 0.25e6; % [Hz]
   for i = 1:128 %
   for k = 1:128
   source.mag = source.p0(i,k) %
   source.p = source.mag * sin(2 * pi * source_freq * kgrid.t_array);
   end
   end % [Pa]
   % filter the source to remove high frequencies not supported by the grid
   source.p = filterTimeSeries(kgrid, medium, source.p);

   Posted 4 years ago #

2. HustYjq
   

   Member
   Joined: Jul '20
   Posts: 20

   well,i modified my code ,but it still has problem:Input signal must be a vector.
   p0_magnitude = 1;
   p0 = p0_magnitude * loadImage('150mev.png');

   % create the computational grid
   Nx = 128; % number of grid points in the x (row) direction
   Ny = 128; % number of grid points in the y (column) direction
   dx = 0.1e-3; % grid point spacing in the x direction [m]
   dy = 0.1e-3; % grid point spacing in the y direction [m]
   kgrid = kWaveGrid(Nx, dx, Ny, dy);
   % create the time array

   % resize the image to match the size of the computational grid and assign
   % to the source input structure
   p1 = resize(p0, [Nx, Ny]);

   % define the properties of the propagation medium
   medium.sound_speed = 1500; % [m/s]
   medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
   medium.alpha_power = 1.5;

   source.p_mask = ones(Nx, Ny);
   kgrid.makeTime(medium.sound_speed);
   % define a time varying sinusoidal source
   source_freq = 0.25e6; % [Hz]
   j=1;
   for i = 1:128 %
   for k = 1:128

   source.p(j,:)= p1(i,k) * sin(2 * pi * source_freq * kgrid.t_array);
   j=j+1;

   end
   end % [Pa]
   % filter the source to remove high frequencies not supported by the grid
   source.p = filterTimeSeries(kgrid, medium, source.p);

   Posted 4 years ago #

3. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi HustYjq,

   I'd suggest working through the time varying source examples in the toolbox (you can access these using the MATLAB help browser), and the k-Wave user manual. These should tell you everything you need. Let me know if you get stuck on something specific after taking a look at these.

   Brad.

   Posted 4 years ago #

4. HustYjq
   

   Member
   Joined: Jul '20
   Posts: 20

   Hi,
   I have an matrix 40 *100 of initial pressure .In some locations the pressure is not 0.And I define the source.mask as source.p_mask(12:27,1:45)=1;But I have wrong Waveform.Can anyone tell me how to solve these problem?

   Nx = 40; % number of grid points in the x (row) direction
   Ny = 100; % number of grid points in the y (column) direction
   dx = 0.1e-3; % grid point spacing in the x direction [m]
   dy = 0.1e-3; % grid point spacing in the y direction [m]
   kgrid = kWaveGrid(Nx, dx, Ny, dy);
   p1 = resize(p0, [Nx, Ny]);
   medium.sound_speed = 1500; % [m/s]
   medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
   medium.alpha_power = 1.5;
   kgrid.makeTime(medium.sound_speed);

   source.p_mask = zeros(Nx, Ny);
   source.p_mask(12:27,1:45)=1;
   j=1;
   for k = 1:45;
   for i = 12:27;

   source.p(j,:)= p1(i,k) *(heaviside(kgrid.t_array);
   j=j+1;

   end
   end

   Posted 4 years ago #

5. HustYjq
   

   Member
   Joined: Jul '20
   Posts: 20

   Hi,
   I have an matrix 40 *100 of initial pressure .In some locations the pressure is not 0.And I define the source.mask as source.p_mask(12:27,1:45)=1;But I have wrong Waveform.Can anyone tell me how to solve these problem?

   Nx = 40; % number of grid points in the x (row) direction
   Ny = 100; % number of grid points in the y (column) direction
   dx = 0.1e-3; % grid point spacing in the x direction [m]
   dy = 0.1e-3; % grid point spacing in the y direction [m]
   kgrid = kWaveGrid(Nx, dx, Ny, dy);
   p1 = resize(p0, [Nx, Ny]);
   medium.sound_speed = 1500; % [m/s]
   medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
   medium.alpha_power = 1.5;
   kgrid.makeTime(medium.sound_speed);

   source.p_mask = zeros(Nx, Ny);
   source.p_mask(12:27,1:45)=1;
   j=1;
   for k = 1:45;
   for i = 12:27;

   source.p(j,:)= p1(i,k) *(heaviside(kgrid.t_array);
   j=j+1;

   end
   end

   Posted 4 years ago #

6. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi HustYjq,

   What do you mean by wrong waveform? If you can post a small working example and let me know exactly what the problem is, I'll take a look.

   Brad.

   Posted 4 years ago #

7. HustYjq
   

   Member
   Joined: Jul '20
   Posts: 20

   Hi Bradley Treeby，
   I want to perform a axisymmetric simulations in 3D.I have a two-dimensional matrices, and i want to rotate around an axis like the example "Simulations In An Axisymmetric Coordinate System Example" .But I want to get a three-dimensional body instead of a two-dimensional plane.Every gp in the body has value.Can i do this in K-wave?
   Thank you!

   Posted 4 years ago #

8. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Do you mean how can you remap results from an axisymmetric simulation to 3D? You could use something like revolve2D.

   Brad

   Posted 4 years ago #

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