k-Wave

1. Gabrielle
   

   Member
   Joined: Mar '15
   Posts: 8

   Hi,

   Thank you for such a wonderful toolbox!

   Recently I found the unreleased function fitPowerLawParamsMulti from the forum to solve the smallness approximation problem.

   I tried this function for a skull case with attenuation coefficient varies from 0 to 20 dB/cm and I assumed a constant power law exponent 2.0. It seems that this fitting function does not adjust the attenuation coefficient when ref_y is chosen as 2.0.

   Then I changed the ref_y to 1.5, the adjusted values from this function were smaller than original data. But when I check the paper "Modeling power law absorption and dispersion in viscoelastic solids using a split-field and the fractional Laplacian", the figure 2(a) shows that the fitting function will give higher values as the original absorption will underestimate the absorption.

   Another concern is that does this function only correct the values for moderate \omega\tau values? what about the case when \omega\tau>>1 ?

   many thanks,
   Gabrielle

   Posted 5 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Gabrielle,

   This function gives absorption values that are correct at the reference frequency. In this case, the actual value of y_ref doesn't matter (I usually choose 2), provided that the absorption at f_ref match that expected by a0 and y. The function automatically takes into account the actual absorption behaviour, including for highly absorbing media.

   Hope that helps,

   Brad

   Posted 5 years ago #

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