ZMT zurich med tech

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.

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

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

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.

If you click on Network Analysis in your Analysis tree, what is your Reference Impedance?

It is set to 50 ohms by default, but you have change it based on the Input Impedance for the coil before plotting the S11 curve.

Plot the complex Input Impedance. At resonance, the imaginary part will be zero (the circuit is purely resistive). So at the desired resonant mode / frequency, you should find the corresponding real value, and set this value as the reference impedance to plot |S11|.
image.png
6f536c46-f9f2-4d5a-b787-cfdb97521404-image.png
5730b440-37ea-4190-824e-1fac4e45155a-image.png

Yes，I have seen that tutorial. So I set the source like the coaxial in tutorial.
The antenna is to be implanted into body, so the size is small. (Coaxial outer radius 0.35mm)
5bdc3fe9-6e37-48b5-ba7a-e407160bcf0a-image.png
57d3cb14-bb80-4dc3-937a-ae23a32179d2-image.png
042cbc9f-6090-4aea-9a14-9805f08ee014-image.png

For others having this issue, when using the MQS solver, the E-field is calculated only in the lossy domain, whereas the H-field is calculated everywhere. So the E-field and its derived values will be NaN in regions with no conductivity.

When you used the Mask Filter, did you check the option 'Invalidate Masked Values'? This will set the Background to NaN, which should hide it. Otherwise, the Background value will be changed to a user-defined replacement value, which would still show up during visualization.

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.

One thing you could try and changing the priority settings on different grid folders. However, I'm not exactly sure what you want your grid to look like. Do you want the grid to be graded with successive voxel sizes of 0.5, 1, 1.5, and 2mm? Could you perhaps provide a simple sketch of what you are envisioning?

To perform such a study, define your region or quantity of interest, then parametrize it. After a quantity has been parametrized, you can run multiple simulations using the built in Sweeper feature or using the Sim4Life Python API.

There is an example in the Sim4Life manual titled 'Parametrized Patch Antenna' that shows how to use the Sweeper feature.

If using the Python API, the easiest way would be to create a baseline simulation by hand, then right-click on the simulation name and select To Python. Then you would find the quantity of interest in the auto-generated script and assign it to a variable instead of the hardcoded value. Using a simple loop in Python, you can create multiple simulation that have identical setup except for parameters of interest.

In your example, multiple simulations would be run with identical setup except for the grid resolution within a region of interest (e.g., a wire block surrounding a region of interest is placed in a manual grid settings folder, then Maximum Step is changed from 0.3 to 1.0 mm).

Then in Analysis you extract a quantity of interest and compare how this value changes as a function of grid resolution.

If the change in the value is small as you increase resolution, you can proceed in future simulations with a coarser resolution to save on run time. The exact convergence of the value needed depends on your application.

The second error message can be ignored.

For the first, have you experienced issues with Sim4Life crashing? Does the message show up when opening a new instance of Sim4Life, or only when opening specific smash files?

Thank you very much. This fixed the issue. This was related to Ares also.

Hello,

Sorry I am facing an issue with moving antennas to different locations based on the steps above. I used three points on the skin and calculated the transformation between static and posed states. I used this transformation to transform the antenna position to the new position (using RigidTransform and ApplyTransform functions).

However I get errors that the antenna source edge is within a solid. I have changed priorities during voxelling providing antennas higher priority but the errors still exist. What can I do? I would like to move antennas in a similar fashion to how soft tissues deform.

Thanks
Vignesh

That sounds like a neat setup you've got there with dual GPUs! Running multiple simulations simultaneously can definitely boost productivity. To tackle your issue, you might want to explore parallel computing techniques. This involves distributing computational tasks across multiple processors, in your case, GPUs. Look into frameworks like CUDA or OpenMP, which support parallel processing.Good luck, and if you're into cutting-edge tech, check out Quantum AI. They delve into the fascinating realm of quantum computing, which could revolutionize simulation and problem-solving in the future.

Hi,

Thank you. I tried it but would like to plot the fields on a grid between antennas (as shown in red in the image). It is easy when the model is static but when posed, I am not able to get a grid at an angle.

Thanks

image.png

That's great to hear! Thank you so much for sharing your experience. I'll explore the option of implementing something similar for EM simulation.

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