cgenes Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 07:35:46 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/time-varying-source-in-thermal-simulation-possible#post-7800 Fri, 11 Sep 2020 09:46:29 +0000 Bradley Treeby 7800@http://www.k-wave.org/forum/ <p>Hi Charlie,</p> <p>A few points. First, the inputs to <code>takeTimeStep</code> are the number of time steps, and the size of the time step. So your code will take 1 time step of 60 seconds (your comments suggest you want to turn on and off for 1 second with 60 steps). </p> <p>Second, if your grid size is 201 x 201 x 201 as the comments suggest, the FFT calculations will be slow because of the large prime factors. Try switching to a grid size with small prime factors.</p> <p>Finally, with the current code, there is a reasonable overhead to calling the code for just one time step. So an alternative would be to hack <code>kWaveDiffusion</code> to put your checks inside the internal time loop.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/time-varying-source-in-thermal-simulation-possible#post-7773 Wed, 26 Aug 2020 09:18:28 +0000 cgenes 7773@http://www.k-wave.org/forum/ <p>HI I have a related question to this </p> <p>I'm using the below code to cycle the beam on and off - monitoring the heat in the middle of the 'tumour' - and then stopping the cycle when a cem&gt;240 is reached at the back of the tumour - but it takes ages! have you got any advice on a better way to achieve this </p> <p>thanks!</p> <p>Charlie </p> <p> back_of_tumour = 100; % in pixels on a 201x201x201 matrix<br /> middle_of_tumour = 120; % in pixels on a 201x201x201 matrix</p> <p> % set source on time and off time steps<br /> on_time = 1; % [s]<br /> off_time = 1; % [s]</p> <p> % calculate over this many steps<br /> dt = 60;</p> <p> kdiff.takeTimeStep(on_time, dt);<br /> disp('cem43 after 1 step'); kdiff.cem43(back_of_tumour, 100, 100)</p> <p> cem43_cycle_count = 0; % except the first round which has had an extra round to initiate k.diff heating cycle<br /> on_count = 0;<br /> off_count = 0;</p> <p> while kdiff.cem43(back_of_tumour, 100, 100) &lt; 241</p> <p> disp('cem43'); kdiff.cem43(back_of_tumour, 100, 100)</p> <p> while kdiff.T(middle_of_tumour, 100, 100) &lt; 65<br /> if kdiff.cem43(back_of_tumour, 100, 100) &gt; 241<br /> break<br /> end<br /> kdiff.Q = datacube; % this is my input source in W/m^3<br /> kdiff.takeTimeStep(on_time, dt);<br /> kdiff.T(middle_of_tumour, 100, 100)<br /> on_count = on_count + 1<br /> disp('cem43'); kdiff.cem43(back_of_tumour, 100, 100)<br /> end</p> <p> while kdiff.T(middle_of_tumour, 100, 100) &gt; 45<br /> if kdiff.cem43(back_of_tumour, 100, 100) &gt; 241<br /> break<br /> end<br /> kdiff.Q = 0;<br /> kdiff.takeTimeStep(off_time, dt);<br /> kdiff.T(middle_of_tumour, 100, 100)<br /> off_count = off_count + 1<br /> end</p> <p> cem43_cycle_count = cem43_cycle_count + 1 </p> <p> end </p> http://www.k-wave.org/forum/topic/time-varying-source-in-thermal-simulation-possible#post-7410 Fri, 17 Apr 2020 16:40:17 +0000 Bradley Treeby 7410@http://www.k-wave.org/forum/ <p>Hi XCHENG,</p> <p>There is currently no way to directly specify a time varying source. The approach you mention is the best one for now. However, if you're switching your source on and off much faster than the thermal diffusion time, you can likely just multiply your heat source amplitude by the duty cycle, and you will get the same result.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/time-varying-source-in-thermal-simulation-possible#post-7383 Fri, 10 Apr 2020 18:07:11 +0000 XCHENG 7383@http://www.k-wave.org/forum/ <p>Hi Bradley,</p> <p>I noticed that function 'kWaveDiffusion' only accepts 'source.Q' or 'source.T0' as source input (matrix same size as [Nx, Ny, Nz]).</p> <p>Is there a nice way to implement a time varying heat source?</p> <p>Since there's not something like source.Q_mask (an equivalence for source.p_mask) I'm not sure how to achieve it. (I can't just do a 2D matrix with each row containing the time signal for each source point and then positions specified by source.p_mask anymore)</p> <p>My current idea is as horrible as keep turning on and off the source as that shown in examples (but way faster and way more times) to achieve this.</p> <p>Please enlight me and save me from my horrible idea! </p>