Subcategories

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• Installation & Licensing

  Installing Sim4Life and configuring licenses

  28 Topics

  101 Posts

  H

  You must be referring to this: This is windows configuartion related issue. You might not have access to log counter data, try logging in as an administrator. Later you can add user to the Performance Logs User Group. Look at this page for more details: https://learn.microsoft.com/en-us/windows/win32/perfctrs/limited-user-access-support

• CAD Modeling

  Working with CAD models

  53 Topics

  182 Posts

  B

  The first method might not be working if your spline doesn't have a parametrization. If you click on the spline in the Model tree and don't see a list of points in the Controller window, then the information is no longer available and you'll have to stick to the second method.

• Anatomical Models

  Working with models from the Virtual Population

  45 Topics

  206 Posts

  V

  Hi Bryn,

  I would like to ask a question regarding posing. My aim is to detect the variation in bone position from the skin in different poses (hypothesis being: as the soft tissues deform, the bone wont always be at the same position wrt the skin). I currently have 8 antennas placed around the skin which are supposed to mimic wearable antennas and I would like to move these antennas along with the pose.

  But if I link these antennas to the bone using "link-parent tool", the bone is always at the same location wrt to the bone irrespective of the pose. But I cannot link the antennas wrt to the skin as the antennas dont move with the pose.

  How can I do this? I would like the antennas which are placed around the skin to similar to the skin rather than the bone? Based on the first video in this chain, triangular meshes can be posed similar to the body. If I convert the antennas to meshes and then pose it, will I be getting the same issue i.e the bone is always at the same location wrt to the antennas?

  Thanks

• Simulations & Solvers

  FDTD, Low-Frequency, Neuron, Mode-Matching, Flow, Acoustics, etc...

  T-Neuro
  216 Topics

  639 Posts

  H

  When using a long line as "normal" edge source, the discretization will result in one edge being the actual source and rest of the line being discretized as PEC filament. This can lead (depending on the excitation frequency, the length of the source line and the setup) to inaccuracies due to the additional capacitance introduced be the PEC filaments. An alternative that is, in most cases, a more accurate source representation is using the "Distribute Along Line" option, the source is equally distributed over all the discretized edges of a line element (see image, right). That prevents any PEC filaments and therefore makes the injection of the signal more realistic.

  Time delay = distance between the transmitter and receiver*sin(theta)/c where theta is the angle of antenna. I would suggest looking into antenna array literature for theoretical background on calculating this quantity.

• Analysis & Postprocessing

  Postprocessing results

  91 Topics

  254 Posts

  B

  Note that the above is only true in the case of a harmonic signal, which is why Sim4Life does not provide the RMS by default. It is up to the user to calculate the RMS based on their knowledge of the signal.

  If you are interested in B1+/B1-, the rotational components of B1 are by definition constant in time and so their RMS magnitudes are equal to their absolute magnitudes.

• Python API

  Scripting interface for Sim4Life

  113 Topics

  314 Posts

  B

  short answer: you can run most of the Python API without opening the Sim4Life user interface.

  you have different options

  you can call Sim4Life.exe --run your_script.py you can write scripts and run them using the python.exe in the Sim4Life installation you can create a virtual environment with the Sim4Life packages, e.g. "C:\Program Files\Sim4Life_6.2.2.6592\Python\python.exe" -m venv .venv --system-site-packages and then use the python from this venv to run your script

  The first option opens Sim4Life, runs the script, and closes Sim4Life again. It probably is the easiest option to work robustly.

  The latter two options run without the UI and by default without an application. In most cases, you will need an application though (e.g. the Application initializes the active model, which is needed for modeling). For Python scripting without the UI you can create a console application. We do this e.g., to run Python tests without opening the UI (which is slower). To create a console application you can usually call:

  import XCore XCore.GetOrCreateConsoleApp() # now you can do some stuff import s4l_v1 as s4l sphere = s4l.model.CreateSolidSphere(s4l.model.Vec3(0.0), 1.0)
• Networking & Administration

  Running Sim4Life over a network

  3 Topics

  5 Posts

  R

  I eventually configured Sim4Life on a Cloup GPU workstation (paperspace.com). The workstation has an Intel Xeon E5-2630 v3 processor, 16 virtual cores, 90 GB of RAM, and two NVIDIA Ampere A6000 GPUs, each with 48 GB of GPU memory. For Exablate Neuro transducers (220 and 670 kHz) simulations, the workstation improved simulation speed from about 200 Mcell/s with an 8-core OpenMP configuration, to about 12000 Mcells/s with two GPUs.

  The workstation allows simulations (1449x1149x816 grid, 200 periods, 670 kHz, 0.22 mm max step for 10 points per wavelength) in about 40 minutes with Fourier-domain sensor recordings and about 4 hours with Time-domain sensor recordings. Time-domain simulations seem only compatible with a single GPU, while Fourier-domain sensor simulations can use both GPUs. Also, the Fourier domain field sensor recordings create simulations that look unstable (or less accurate) compared to the time-domain field sensor recordings, with all other factors equal. Only the time-domain simulations have readily matched previous studies, but the simulation time is still too long.

  Can the time-domain sensor acoustic simulation be run on multiple GPUs? Also, most of the time for Fourier-domain simulations is spent "allocating memory for the voxel array." Is there a way to configure the GPU to preallocate memory or another way to reduce the amount of time to distribute the array memory?