Hi, this typically happens if some material that is voxeled is not found. If I had to guess, I'd say that you have a source and no corresponding material (the source element should be in the Sources and Materials)

If I read the message correctly, it seems that another program is interfering. Have you tried to uninstall the Yale Neuron Solver?

@rose, you write "it was a bit different from the theoretical result", but unfortunately I don't fully understand what you did, what you are trying to do, and what you are comparing your results to. Perhaps if you describe (with e.g. screenshots and equations) both what you did and what the "theoretical results" I can try and find why they do not match.

Hi Javier, What error messages are you getting with Endring 1 simulation? I assume that you have already checked the tutorial "3.1.9 MRI Lowpass Volume Coil" which might help you to make sure that your setup is correct.

@rose see my answer here

See the Sim4Life Manual (2.6.1 EM LF - Simulation Theory) ωσμd2≪1^ The quasi-static conditions are sufficient conditions for the quasi-static approximation to hold. In practice, there are cases where the quasi-static approximation still yields accurate results even when the quasi-static conditions are not satisfied. The guideline for this type of cases is to compare to results from full-wave simulations. A table of the quasi-static approximation criteria for every simulation is written in the log file: Solid settings: frequency = x Hz, characteristic length (worst case domain diagonal) x Epsilon Mu SigmaE QS Approx. Quality Static Magn. Field SigmaE/wEpsilon Solid name The column QS Approx. Quality and Static Magn. Field refers to quasi-static conditions. The column SigmaE/wEpsilon indicates whether the displacement current ( ≪1 ) or the ohmic current dominates ( ≫1 ). 2.6.1.4 Choosing the Appropriate Low Frequency Solver has further details

Thank you @LJ and @Habib!! Fantastic explanations, I understand :)

@rose your simulations are most likely done with a 1V voltage at the excitation source (that's the default setting). This is perfectly fine from a numerical point of view, but in practice (e.g., if you wanted to compare with measurements) you probably want to normalize your results. In the Far Field Sensor, for example, you can normalize to a Total Available power of 1W (say). This way, you will be comparing apples to apples. That will not change the value for the Gain, though (since it is a power ratio, independent of scaling). This must come from either a difference in some aspect ratio of your dipole, or simply that you did not change the dimensions in the same proportion (1/10th) as you changed the frequency.

I would double-check that the electrodes being used are added as voxels correctly if they're not then the boundary conditions do not get set up properly. It might be easier to help if you provide more information.

@Sylvain It really helped!! I've successfully done making animation!! Thank you for helping me. Since you also gave me some advice about TRP problems, I would like to carry on the solutions you suggested. I really appreciate your help.

@habib Hi, Thank you for your reply. I can understand that if you enable the titration, the software keeps on scaling the field till sees a stimulation. But it also gives us a number for the scaling field. In this case, I am seeing that number to be 0.13. Doesn't it mean that the field has been scaled down to a factor of 0.13 to create the minimum field for stimulation - I was hoping that number to be orders of magnitude higher. Please correct me if I am wrong. Thanks for looking into this.

Hi, There is a tutorial called "Parallel Plates" for the LF (low-frequency) solver. I think it does exactly what you need. You can access the step-by-step instructions from Sim4Life -> Help -> HTML Tutorials -> 3.2.1. Parallel Plates You can also open the Sim4Life project using Sim4Life -> File -> Open Tutorial -> EM LF Tutorials -> Parallel Plates.smash

Hi Ari, It depends on your purpose. If you use single port simulation, then, you cannot later change the phase difference between the coils. However, if you use multiport simulation, Sim4Life runs 2 simulations for each coil and stores the results separately. This is useful if you would like to postprocess results for different source parameters. For example, you may change the current amplitudes for each coil, or add phase differences. You do not have to run the simulations again. New results will be directly calculated by using the previously stored multiport results. So, if you have enough memory and would like to try different settings for the sources, you had better to use multiport simulation for the above setup. If you want to save time and memory and fixed the source settings, then you may chose single port simulation. I hope this helps. Sayim

The easiest way I found is to use the power (I=P/V) as it shows you the current lost in different parts of the model as well as overall. have a look at what was mentioned here https://forum.zmt.swiss/topic/24/compute-the-total-current-flowing-between-two-electrodes-in-an-electro-quasistatic-lf-simulation/3?_=1618565314728

@lj I have followed the yoon-sun arm stimulation tutorial, but I don’t understand the meaning of the results obtained. I don’t know the relationship between these results and tactile feedback, nor can I understand how to get information about tactile sensation and nerve fiber potential. Information link.