nvvyjayanthi Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 03:10:38 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/superposition-of-multiple-waveforms#post-6856 Tue, 21 May 2019 19:37:40 +0000 nv.vyjayanthi 6856@http://www.k-wave.org/forum/ <p>Hi Brad,</p> <p>Thanks a lot! This definitely cleared things when I tried it. </p> <p>Thanks!<br /> NV </p> http://www.k-wave.org/forum/topic/superposition-of-multiple-waveforms#post-6836 Wed, 10 Apr 2019 13:01:19 +0000 Bradley Treeby 6836@http://www.k-wave.org/forum/ <p>Hi NV,</p> <p>This is due to the source smoothing applied to initial value sources in k-Wave. You can check this by setting the optional input <code>&#39;Smooth&#39;, false</code>.</p> <p>To allow a fair comparison with smoothing on, turn off the automatic smoothing, and smooth yourself using the <code>smooth</code> function in k-Wave (see the <a href="http://www.k-wave.org/documentation/example_pr_2D_fft_line_sensor.php">2D FFT Reconstruction For A Line Sensor Example</a> if needed).</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/superposition-of-multiple-waveforms#post-6803 Wed, 27 Mar 2019 16:31:56 +0000 nv.vyjayanthi 6803@http://www.k-wave.org/forum/ <p>Hey Ben, </p> <p>Yes, they should be the sum but they do not end up being the sum when I simulate them separately and add. </p> <p>Best,<br /> NV </p> http://www.k-wave.org/forum/topic/superposition-of-multiple-waveforms#post-6797 Thu, 21 Mar 2019 00:48:56 +0000 bencox 6797@http://www.k-wave.org/forum/ <p>Hi nv.vyjayanthi, </p> <p>Is it just that where your dots share a grid point, the amplitude there should be the sum of the contributions from both dots?</p> <p>Best wishes,<br /> Ben </p> http://www.k-wave.org/forum/topic/superposition-of-multiple-waveforms#post-6773 Fri, 15 Mar 2019 17:27:51 +0000 nv.vyjayanthi 6773@http://www.k-wave.org/forum/ <p>Hello, </p> <p>I have a question regarding how k-wave computes the photoacoustic response for individual dots compared to when the object is a sum of such individual dots.</p> <p>My simulation setup includes a single element in my sensor.mask placed in the middle of the space defined. I then define 2 objects p01 and p02 both of which are single dots separated in x,y but in the same z-plane. I then generate the PA response of each of these dots and save them. The next object defined is p03 = p01+p02 and once again I generate a PA response for this combined object. </p> <p>Now my issue is this. When the dots do not share a common edge or corner, the sensor_data_p03 = sensor_data_p01 + sensor_data_p02. But when the two point objects do share a common edge or corner, the waveforms are in the same place in time and have the same shape but the principle of superposition doesn't hold anymore. </p> <p>When they share a corner, sensor_data_p03 = (sensor_data_p01 + sensor_data_p02)/1.4<br /> When they share an edge, sensor_data_p03 = (sensor_data_p01 + sensor_data_p02)/1.65</p> <p>I came by these scaling factors purely by trial and error. </p> <p>Would anyone happen to know why this is the case? Or is the way I'm looking at the PA generation wrong perhaps?</p> <p>My code is as follows:</p> <p>%% create computational grid<br /> clear;<br /> Nx = 32;<br /> dx = 1e-3;<br /> Ny = Nx; dy = dx;<br /> Nz = 64; dz = dx;</p> <p>kgrid = kWaveGrid(Nx,dx,Ny,dy,Nz,dz);</p> <p>% define the properties of the propagation medium<br /> medium.sound_speed = 1500; % [m/s]</p> <p>% create the time array<br /> kgrid.makeTime(medium.sound_speed);</p> <p>% define grid sensor<br /> sensor.mask = zeros([Nx,Ny,Nz]);<br /> sensor.mask(Nx/2+1,Ny/2+1,10) = 1;</p> <p>% input arguments<br /> input_args = {'DataCast', 'single', 'CartInterp', 'nearest', 'DisplayMask', 'off', ...<br /> 'PlotSim', boolean(0)};</p> <p>% create pressure distributions and get data</p> <p>p01 = zeros([Nx Ny Nz]);<br /> p01(17,17,50) = 1; % changing this in r,c<br /> source.p0 = p01;<br /> sensor_data_1 = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:});</p> <p>p02 = zeros([Nx Ny Nz]);<br /> p02(17,18,50) = 1; % changing this in r,c<br /> source.p0 = p02;<br /> sensor_data_2 = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:});</p> <p>p03 = p01+p02;<br /> source.p0 = p03;<br /> sensor_data_3 = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:});</p> <p>figure;<br /> plot(sensor_data_3)<br /> hold on<br /> plot(sensor_data_1 + sensor_data_2)<br /> legend('Total obj','Superposition')</p> <p>Any help would greatly be appreciated!</p> <p>Thanks </p>