http://www.k-wave.org/forum/topic/sensor-setting-problems Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:20:44 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/sensor-setting-problems#post-6700 Sat, 29 Dec 2018 10:01:32 +0000 wenxiu 6700@http://www.k-wave.org/forum/ <p>Hi khoslaygr26,</p> <p>I recommend you to read the reference in the k-wave's user manual:<br /> J. C. Bamber, \Attenuation and Absorption," in Physical Principles of Medical Ultrasound<br /> (C. R. Hill, J. C. Bamber, and G. R. ter Haar, eds.), pp. 93{166, Chichester: John Wiley,<br /> 2004</p> <p>I met the similar question with yours several days before.And I choose water as the medium.<br /> The attenuation coefficient is determined by frequency, and the relationship is very complex. But the attenuation coefficient could be thought as linear to the square of frequency with a certain range. So the medium.alpha_power can be set as 2.<br /> As for your question. I suggest you to find the references about the material you chosen. Choosing the approximated values of medium.alpha_power and medium.alpha_coeff.</p> <p>Wenxiu </p> http://www.k-wave.org/forum/topic/sensor-setting-problems#post-6699 Fri, 28 Dec 2018 10:48:36 +0000 khoslaygr26 6699@http://www.k-wave.org/forum/ <p>Hi</p> <p>I have a doubt regarding the parameter medium.alpha_coeff. The unit mentioned is dBcm-1Mhz-y, can anybody tell me if i have a 40Khz source sensor, will the attenuation coefficient still be the same, because most materials refer to the attenuation coefficient around 1 for 1MHZ, will it be the same even for a lower frequency?</p> <p>Thank you. </p> http://www.k-wave.org/forum/topic/sensor-setting-problems#post-6698 Thu, 27 Dec 2018 07:57:58 +0000 wenxiu 6698@http://www.k-wave.org/forum/ <p>Hi Bradley,</p> <p>Thanks for your reply. Your guidance helps a lot. </p> http://www.k-wave.org/forum/topic/sensor-setting-problems#post-6622 Tue, 30 Oct 2018 16:27:30 +0000 Bradley Treeby 6622@http://www.k-wave.org/forum/ <p>Hi wenxiu,</p> <p>(1) In practice, I would suggest using a least 3 points per wavelength at the highest frequency of transducer. Any less, and the effectiveness of the PML starts to decrease (see <a href="http://bug.medphys.ucl.ac.uk/papers/2017-Robertson-JASA.pdf">here</a> for an example).</p> <p>(2) Details of how to set the sensor mask are given in the k-Wave manual and the examples. In short, in this example you are using a binary sensor mask. Wherever you have set a 1 in your matrix, the pressure will be recorded. You can take a look at the sensor mask using <code>imagesc(sensor.mask);</code></p> <p>(3) This seems sensible, yes.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/sensor-setting-problems#post-6586 Wed, 26 Sep 2018 03:42:38 +0000 wenxiu 6586@http://www.k-wave.org/forum/ <p>Hello,</p> <p>I'm trying to simulate a simple example of acoustic propagation in water in 2D, which is received by a focused transducer. And I have several problems need your help.</p> <p>1) The central frequency of transducer is about 50 MHz, so what the resolution to divide the mesh? I set the resolution to 1 micrometer, and the result told the maximum supported frequency is 750 MHz. But the radius of 'source.p0' is 2 micrometer. Is it OK? If the resolution be finer, it will cost too much time.</p> <p>2) In the experiment, I use an acoustic lens in front of transducer. So that the sensor is focused, but I'm not familiar with how to set it.<br /> I use a flat transducer to replace it in the simulation, and there is also a small question.The parameter I set:<br /> sensor_radius = 3e-3;<br /> num_sensor_points = 2*sensor_radius/n;<br /> sensor.mask = 0*ones(Nx,Ny);<br /> sensor.mask(200,Ny/2-3000:Ny/2+3000)=1;<br /> I'm confused about the sensor_radius and sensor.mask, are they the same? I think the diameter of sensor is set in the sensor.mask. It seems that sensor_radius and num_sensor_points won't appear again later. And when the sensor_radius and sensor.mask mismatch, there is nothing happened.</p> <p>3)After simulation, I use the average value of every sensor point of the same time, I use it as the simulation output data of the transducer, is it OK?</p> <p>Thanks you! </p>