export the data into Matlab... single Tx coil and combined coils for B1

Hi all,

I am not sure if you have experienced below issue;

  1. I set up a model that consist of 8 parallel transceiver coils (resonating at 298mhz, ie, 7TMR freq.)
  2. ran the simulation with harmonic to evaluate the B1+ field and it took me 60hrs to get the result
  3. I first exported combined B1+ field and SAR without any issue. .MAT files have been saved in the directory as I expected
  4. then I wanted to do the B1 shim and evaluate the SAR per phase and amplitude changed with B1 shim, so I want to export the B1 and SAR as a .MAT file per channel
  5. I pulled simulation combiner from the one of the coil pulled sensor combiner for the overall field which should contain B1 and SAR matrix for the coil (one coil)
  6. When I tried to plot to see the field or export as a .MAT file, I am having all these weird error.

Does anyone know why this error is being generated and how to solve this?
If I have run the simulation every time after exporting the field, this is waste of time....
Please help....

Hi, I am not sure why you are seeing these errors but I can maybe help by providing some information:

  • the data you export, for example .MAT files for B1+ and SAR, are not used by Sim4Life (unless you explicitly import the data back into Sim4Life). So any error (or success) that you see is independent of the exports you may have made
  • the simulation combiner needs the raw simulation results (E and H fields) created by the solver. These files are located in the Results folder. Moving or copying those files in or out of that folder can lead to errors.
  • you are not showing all the errors in your screenshot: that makes it difficult to see what is actually going on

@sylvain said in export the data into Matlab... single Tx coil and combined coils for B1:

you are not showing all the errors in your screenshot: that makes i

Hi Sylvain,

so, what I did was export the individual Coil's SAR and B1 as .MAT file and after that, I tried to export the combined SAR and B1 and it won't let me... (vice versa).
I have not done anything with the E and H field - so, I am not sure why I am seeing this error.
it almost appears that some of the coil, i.e coil#3 didn't converge to calculate the E and H...
I ran exact same simulation 4 times and have had similar error.
it seems like it is repeatable - when you export the B or SAR and try to plot... it throws an error.

Hi I am not sure if these may help.

  • to decrease simulation time (60hrs), you may consider healing the smallest grid. In my simulations, I have time steps usually around 1-3 ps. Anything below 1ps (time step) makes me to revise the model. Modeling cylindrical objects in cartesian coordinates may cause some geometric discrepancies. For example, assume you have a capacitor in one element, which has an only 0.1 mm offset compared to its mirrored counterpart. This means, although you have a capacitor size of a few millimeters, the minimum mesh size would be in the order of 0.05mm! This is terrible for a simulation at 298MHz. To avoid this, I usually model my elements in python environment. Rotating/translating elements manually (without proper snap options) may cause this problem.
  • make sure that all channels have simulation results (I assume multiport simulation)
  • other than that, (These errors may be due to missing simulation result, though) avoid using single port simulations, since you cannot change phases and export results after running a simulation.