k-Wave

1. rmurthy
   

   Member
   Joined: Nov '11
   Posts: 4

   Hello,

   In the Homogenous Medium example, there's the following section of code:

   % create initial pressure distribution using makeDisc
   disc_magnitude = 5;

   The example states that this initial pressure distribution is arbitrary, but I'm interested in simulating a particular transducer's effects on tissue. What are the units of this magnitude value? And when the final graph is formed:

   imagesc(sensor_data, [-1, 1]);
   colormap(getColorMap);
   ylabel('Sensor Position');
   xlabel('Time Step');

   What is the sensor_data being normalized to? Is it to this initial pressure magnitude?

   Thanks!

   Posted 12 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   The current version of k-Wave (B.03) uses linearized acoustic equations. In this case, everything scales linearly (double the input and you'll double the output). However, the governing equations are derived in units of pressure if you would prefer to use more meaningful input values. (In other words, if you give your input in units of Pascals, your output will also be in units of Pascals).

   In the final graph, the sensor_data is not normalised in any way, but the magnitudes are relative to the initial pressure (5 in this case). The plot scale [-1, 1] is chosen to give suitable contrast in the displayed image.

   We are just putting the finishing touches on the B.04 release which includes nonlinearity. In this case, the actual value of the pressure (in units of Pa) will affect the characteristics of the simulation.

   Posted 12 years ago #

3. rmurthy
   

   Member
   Joined: Nov '11
   Posts: 4

   Thank you for the quick response! Any idea when that next release will be coming out?

   Posted 12 years ago #

4. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hopefully sometime in the next few weeks. We are just in the process of doing some final debugging of the new features and updating the documentation and examples.

   Posted 12 years ago #

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