amita Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 22:31:17 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/regarding-use-of-kwavetransducer-class-as-source-for-kspacefirestorder3d#post-8663 Fri, 11 Nov 2022 12:06:40 +0000 Bradley Treeby 8663@http://www.k-wave.org/forum/ <p>If you open the code <code>kspaceFirstOrder3D</code> you can see where the transducer source is applied on line 889 (v1.4.0). The scaled source term is added to the x-component of the particle velocity. </p> http://www.k-wave.org/forum/topic/regarding-use-of-kwavetransducer-class-as-source-for-kspacefirestorder3d#post-8660 Wed, 09 Nov 2022 12:49:10 +0000 Amita 8660@http://www.k-wave.org/forum/ <p>Dear Dr. Treeby,<br /> Thank you for your reply.<br /> could you please help me with the following follow-up question?<br /> How do we get the velocity profile for a particular configuration and input of the transducer?<br /> I wanted to understand the relationship between the transducer's configuration, input signal, and particle velocity.<br /> I want to calculate the pressure or velocity field by the transducer so that I could use it as the initial condition for the function kspaceFirstOrder3D.<br /> could you please suggest any article for the same? </p> http://www.k-wave.org/forum/topic/regarding-use-of-kwavetransducer-class-as-source-for-kspacefirestorder3d#post-8646 Tue, 08 Nov 2022 10:23:02 +0000 Bradley Treeby 8646@http://www.k-wave.org/forum/ <p>The <code>kWaveTransducer</code> class sets the normal particle velocity in the direction that the transducer is facing. </p> http://www.k-wave.org/forum/topic/regarding-use-of-kwavetransducer-class-as-source-for-kspacefirestorder3d#post-8637 Tue, 01 Nov 2022 14:08:53 +0000 Amita 8637@http://www.k-wave.org/forum/ <p>How a source may be added to the kspaceFirstOrder3D function using the kWaveTransducer class?<br /> As the source input for the kspaceFirstOrder3D function can be given in terms of pressure or velocity, I am unable to understand how the output of the kWaveTransducer class is providing the source.p_mask and source.p values (or source.v_mask and source.v values)?</p> <p>Please help. </p> http://www.k-wave.org/forum/topic/elastic-simulation-with-two-transducer-transmitting-at-different-times#post-8588 Wed, 27 Jul 2022 23:53:16 +0000 bencox 8588@http://www.k-wave.org/forum/ <p>HI derrelldv,</p> <p>Yes, it could be used to generate offset signals. But you could also construct any two time varying signal you like and use them to drive the elements of the two sources. Just bear in mind that only frequencies supported by the grid will propagate, so the time series should be bandlimited using, for example, <code>filterTimeSeries</code>.</p> <p>Best wishes<br /> Ben </p> http://www.k-wave.org/forum/topic/elastic-simulation-with-two-transducer-transmitting-at-different-times#post-8583 Fri, 15 Jul 2022 17:14:23 +0000 derrelldv 8583@http://www.k-wave.org/forum/ <p>I have two transducers transmitting planewave. I want the simulation to be such that the first transducer transmits first and the second transducer transmits after a certain amount of time. Is this where the SignalOffset argument of toneBurst might be helpful? </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-8419 Sun, 09 Jan 2022 17:37:32 +0000 Amita 8419@http://www.k-wave.org/forum/ <p>ok<br /> Thank you </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-8418 Sun, 09 Jan 2022 15:23:52 +0000 Bradley Treeby 8418@http://www.k-wave.org/forum/ <p>See <a href="https://discovery.ucl.ac.uk/id/eprint/10113895/1/2014_Treeby_IEEE_kWaveElastic.pdf">here</a>. </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-8417 Sun, 09 Jan 2022 15:16:37 +0000 Amita 8417@http://www.k-wave.org/forum/ <p>Hi</p> <p>It is written there in user manual that the tool is solving governing equations for fluid medium, then how k-wave is applicable for solid or viscoelastic medium when the wave equation itself is not for these medium?</p> <p>or</p> <p>which governing equations are being solved behind the command pstdElastic2D and pstdElastic3D?</p> <p>please help. </p> http://www.k-wave.org/forum/topic/what-is-the-default-colormap-during-the-forward-simulation-plot#post-8415 Fri, 07 Jan 2022 13:48:49 +0000 Bradley Treeby 8415@http://www.k-wave.org/forum/ <p>The colormap is defined by the function <code>getColorMap</code>. Zero values are displayed as white, positive values are displayed as yellow through red to black (using the <code>hot</code> colormap in MATLAB) and negative values are displayed as light to dark blue-greys (using part of the <code>bone</code> colormap in MATLAB). </p> http://www.k-wave.org/forum/topic/what-is-the-default-colormap-during-the-forward-simulation-plot#post-8414 Fri, 07 Jan 2022 13:26:30 +0000 samantp 8414@http://www.k-wave.org/forum/ <p>Apologies if this is answered somewhere but I had trouble finding the answer. What is the default colourmap that simulations are plotted on *during* the simulation? I was unable to find this and a reviewer has requested it.</p> <p>Thanks </p> http://www.k-wave.org/forum/topic/simulation-on-viscoelastic-solid-medium#post-8398 Tue, 21 Dec 2021 06:12:55 +0000 Amita 8398@http://www.k-wave.org/forum/ <p>Hi brad<br /> Thank you so much. </p> http://www.k-wave.org/forum/topic/simulation-on-viscoelastic-solid-medium#post-8394 Mon, 20 Dec 2021 16:28:14 +0000 Bradley Treeby 8394@http://www.k-wave.org/forum/ <p>Hi Amita,</p> <p>There is a viscoelastic model in k-Wave (called pstdElastic3D and pstdElastic2D). There are some examples under Elastic Wave Propagation in the help files.</p> <p>Brad </p> http://www.k-wave.org/forum/topic/simulation-on-viscoelastic-solid-medium#post-8393 Mon, 20 Dec 2021 13:22:01 +0000 Amita 8393@http://www.k-wave.org/forum/ <p>Can I use k-wave toolbox for shear wave generation in Heterogenous viscoelastic material? (for example, viscoelastic Tissue phantom) </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-4988 Thu, 19 Feb 2015 19:39:20 +0000 Bradley Treeby 4988@http://www.k-wave.org/forum/ <p>Hi Amin,</p> <p>There are a few reasons why we solve the first-order equations rather than the second-order wave equation in the main simulation functions. First, it allows both mass and force sources to be easily included into the discrete equations. Second, it allows the PML to be easily defined. Third, calculation of the particle velocity allows quantities such as the acoustic intensity to be calculated. This is useful, for example, when modelling how ultrasound heats biological tissue due to acoustic absorption. Finally, there is some evidence that solving the first-order equations gives improved accuracy for heterogeneous media.</p> <p>If you're interested in homogeneous media, the function <code>kspaceSecondOrder</code> solves the second-order wave equation.</p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-4985 Wed, 11 Feb 2015 13:52:26 +0000 aminzadeh 4985@http://www.k-wave.org/forum/ <p>Dear Dr. Treeby</p> <p>Hello and Thanks for your Toolbox.</p> <p>As you said k-Wave solve a system of coupled 1st-order equations. why you don't solve the single 2nd-order equation?<br /> I asked this question, because before I know about your Toolbox, I solved the single 2nd order wave eq. and now I see that results are in a good agreement with the k-Wave. </p> <p>Best regards,<br /> Amin </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-321 Wed, 22 Feb 2012 02:39:18 +0000 xiong 321@http://www.k-wave.org/forum/ <p>Hi Brad,</p> <p>This is exactly what I want.</p> <p>Thank you!</p> <p>Xiong </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-314 Fri, 17 Feb 2012 05:34:24 +0000 Bradley Treeby 314@http://www.k-wave.org/forum/ <p>Hi Xiong,</p> <p>Thanks for your question. You are correct about the units. The alpha(r) in Chao's equation actually represents a relaxation time. This is normally denoted tau and is often called Stokes' relaxation time. In the limit of w*tau &lt;&lt; 1, the absorption will be proportional to frequency squared, in other words:</p> <p> absorption = alpha_0 w^2.</p> <p>In this case, the relationship between tau and alpha_0 is given by: </p> <p> alpha_0 = tau/(2*c) </p> <p>Here c is the sound speed in m/s and w is the frequency in rad/s. Note, this is not the wave equation solved in k-Wave.</p> <p>I hope that helps!</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-305 Fri, 10 Feb 2012 00:45:10 +0000 xiong 305@http://www.k-wave.org/forum/ <p>Dear Chao and Ben,</p> <p>I also saw the equation Chao posted. I have a question about it. The unit of alpha(r) in it should be the same as that of time (second) to ensure the unit consistency of the equation. But the acoustic attenuation coefficient (use beta(r) to denote it) usually has the unit of Np/cm or Np/cm/MHz. I don't know the relationship between alpha(r) (ultrasonic absorption distribution) and beta(r) (acoustic attenuation coefficient). If possible, please provide the corresponding equation with beta(r) represents the loss of acoustic wave.</p> <p>Thank you.</p> <p>Xiong </p> http://www.k-wave.org/forum/topic/about-the-wave-equation#post-101 Wed, 16 Feb 2011 11:48:20 +0000 bencox 101@http://www.k-wave.org/forum/ <p>Dear Chao,</p> <p>I think deconvolving your frequency response before you do the image reconstruction is probably the safest way, as you can then deal with the problems that the deconvolution presents (noise amplification essentially) before it gets tangled up in an image reconstruction. Deconvolution of a frequency response from a time series will be covered in many standard digital signal processing books.</p> <p>Kind regards,</p> <p>Ben </p>