http://www.k-wave.org/forum/topic/embeddings-with-larger-sound-speed-and-density Support for the k-Wave MATLAB toolbox en-US Thu, 14 May 2026 00:41:48 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/embeddings-with-larger-sound-speed-and-density#post-9121 Thu, 01 Aug 2024 01:27:27 +0000 healsea 9121@http://www.k-wave.org/forum/ <p>Hello,</p> <p>I am using k-Wave to simulate some embeddings within tissue and have been referencing your example, example_us_bmode_phased_array.m. I encountered an issue when adjusting the wave speed and density of the embedding.</p> <p>When the embedding's wave speed and density are half that of the tissue, the simulation works perfectly. However, when I set the wave speed and density to twice that of the tissue, the sensor data becomes unstable, increasing exponentially and eventually resulting in NaN values. Consequently, the B-mode image is not visible.</p> <p>I have attached my code defining the properties for your reference. Thank you very much for your software and assistance!</p> <p>Best wishes<br /> Haohui Zhang</p> <p>'% define properties<br /> sound_speed_map = c0 * ones(Nx, Ny, Nz) ;<br /> density_map = rho0 * ones(Nx, Ny, Nz) ;<br /> sound_speed_iron = c0*2;<br /> density_iron = rho0*2;</p> <p>% define a cylinder for Iron oxide<br /> radius = 4e-3;<br /> x_pos = 28e-3;<br /> y_pos = dy * Ny/2;<br /> x_loc = round(x_pos / dx);<br /> height = 4e-3;<br /> x_height = round(height / dx);<br /> neighbor = 12e-3;</p> <p>scattering_plane1 = makeDisc(Ny, Nz, round(y_pos / dx), Nz/2, round(radius / dx)); % Center array<br /> scattering_plane2 = makeDisc(Ny, Nz, round((y_pos-neighbor)/ dx), Nz/2, round(radius / dx)); % Left array<br /> scattering_plane3 = makeDisc(Ny, Nz, round((y_pos+neighbor)/ dx), Nz/2, round(radius / dx)); % Right array<br /> scattering_plane = scattering_plane1 + scattering_plane2 + scattering_plane3;</p> <p>scattering_region = repmat(scattering_plane,[1,1,Nx]);<br /> scattering_region = permute(scattering_region,[3,1,2]);<br /> tmp = scattering_region;<br /> tmp([1:x_loc,x_loc+x_height:end],:,:) = 0;<br /> % assign region<br /> sound_speed_map(tmp == 1) = sound_speed_iron;<br /> density_map(tmp == 1) = density_iron;</p> <p>% assign to the medium inputs<br /> medium.sound_speed = sound_speed_map;<br /> medium.density = density_map;' </p>