Solved it - Model the electrode as PEC and use the voltage reader

Hi everyone, I'm using Sim4Life and currently working with the Optimizer tool. I would like to run the optimization algorithm on a network server using ARES instead of executing it on my local machine. However, I can't seem to find an option in the simulation settings that allows me to select the server as the execution target — the optimizer always defaults to running locally. Is it now possible to run parameter sweeps and optimization tasks on a remote machine in the network (without using a remote desktop session)? If so, how can I configure this in Sim4Life? Thanks in advance!

Dear, @AntoninoMC Thank you very much for your detailed clarification. I now understand the fundamental difference between the Ohmic solver and the QS solver, and I have also tried some test runs with the QS solver, which helped me to grasp the impact of frequency dependence more clearly. In my current application, I am applying a voltage to the human body and measuring the potential difference between two points on the head. I am particularly interested in how the measured potential difference changes with the frequency of the applied current. The frequency range I am considering is typically from about 10 kHz up to 100 kHz, but I am also exploring much lower frequencies, down to around 100 Hz. If you could kindly point me to relevant references or scientific literature that discuss similar applications or provide guidance on which dielectric properties are most suitable in this frequency range, it would be extremely helpful. Thank you again for your support.

If simulations are queued indefinitely, this could be an indication of a license issue. To run a simulation, the solver needs to 'check out' a license feature from the license server. When it completes, it marks that license feature as available again. Sometimes, if the application were to crash for some reason, the license feature is not correctly marked as available, preventing other simulations from proceeding because they think the feature isn't currently available to checkout. To resolve this, one thing to try would be to stop and restart license software, or to reinstall the license to ensure that all license features are reset.

After creating the voxels for a simulation, the input file can be created without submitting the simulation by right-clicking on 'Solver' in the simulation configuration and selecting 'Write Input File'.

The Thickness Factor defines the thickness of the Piezo element and the Reflector as a fraction of the acoustic wavelength (determined from frequency and Speed of Sound). By default, n=10, so the fraction is 1/10. This is a parameter which should help to nicely design the SEFT such that it gets correctly voxeled later on (so not too thin) but also doesn't cover too much space (not too thick). Theoretically, the reflector and the active element can be as thin as a single cell layer, but you don't know the computational cell size when drawing the model. Since the voxeler is set to have a max step size of lambda/10, due to stability considerations, the Piezo and reflector will always be nicely and continuously voxeled when using the default Thickness Factor of 1/10. You can find more information about the Acoustic Solver, including relevant equations, in a thesis titled "Multi-Physics Computational Modeling of Focused Ultrasound Therapies", upon which the Acoustic Solver in Sim4Life is based.

Hello, I have the same issue. Currently using Sim4Life 8.2.0.16876. I wonder if there is any new update on this. Many thanks, Ines

OK, I will share it. Thanks

it seems to happen (in Sim4Life 9.0.0) when you switch to the analysis tag after sending a solver job on the cloud. I guess it can be ignored and will be fixed in an upcoming update-fix release

Hi, Did you run your simulation using our SMALL server (16 CPU cores, 32 GB RAM) or the LARGE server (48 CPU cores, 96 GB RAM)? Also, could you let us know the total number of cells in your simulation? As a general suggestion for optimizing memory usage, you can start by running a simulation with a coarse grid to identify regions where the fields are negligible. Based on this, you can adjust the grid padding settings to exclude those body regions from the simulation domain, effectively "cropping" unnecessary areas and reducing the computational load.

I used it to get information for high level workflows. It can also come with suggestions for code, obviously, but it often invents functions that don't exist and implementations for me has not been very AI-powered. But the theoretical discussions are quite good.

Here is the Web Manual section containing this information: 2.11.3.9 Neuro-stimulation with Imperfect Electrode-Skin Contact. Additionally, Yoon-Sun Arm Stimulation tutorial also includes this new feature. For more information or examples you can contact us at s4l-support@zmt.swiss. Thanks!

Hi In Sim4Life the tissue properties are provided as a single values. However, the IT’IS website provides supplemental information on the tissue properties. In addition to the average value, you can find the standard deviation, minima and maxima. Low Frequency (Conductivity) » IT'IS Foundation](https://itis.swiss/virtual-population/tissue-properties/database/low-frequency-conductivity/)

After a call with S4L support, here is the solution for future reference: My machine had two GPUs connected, one of them old and deactivated. However, the script ExtractCudaInfo.py detected both of these in the line 'num_gpus = int(xml_root.find("attached_gpus").text)' and then got stuck trying to find information on the deactivated GPU. A quick fix for the issue is therefore to manually set the correct number, in my case 'num_gpus=1', in the script.

Hi @bryn, I think you’re right. The issue appears to be related to the boundary conditions on the outer bounding box. I changed the boundary to a flux(0) condition, and that resolved the problem with the localized high field values at the extremities. Thank you!