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@Sylvain Hi, thank you for your reply. I changed modulated field to El. Loss Density and everything works.

@halder When I performed TI simulation using the spherical model, I found that if I changed the current direction of one pair of electrodes, the maximum value of the TI Max (x, y, z) slice remained unchanged. Changing the current of one pair of electrodes should have shifted from the original same-direction superposition to a reverse weakening, so why does it remain unchanged? Is it because Max Modulation only uses EM for calculations?

Thank you. Uploaded.

Hi, you can try something like the following to extract the reflection coefficient. You can always try to build extraction manually once and select "To python" by right-clicking on the end of the tree (i.e. the component you extract from your pipeline) import numpy import s4l_v1.analysis as analysis import s4l_v1.document as document import s4l_v1.model as model import s4l_v1.units as units from s4l_v1 import ReleaseVersion from s4l_v1 import Unit sim_name = "MRI Volume Coil Cleg = 29.5 pF" ###### define the sim name in this case this is a multiport FDTD simulation Adding a new EmMultiPortSimulationExtractor simulation = document.AllSimulations[sim_name] em_multi_port_simulation_extractor = simulation.Results() this is extracting a port inputs = [em_multi_port_simulation_extractor.Outputs["MRI Volume Coil Cleg = 29.5 pF - Endring source 1 (Birdcage 1)"]] em_port_simulation_extractor = analysis.extractors.EmPortSimulationExtractor(inputs=inputs) em_port_simulation_extractor.Name = "MRI Volume Coil Cleg = 29.5 pF - Endring source 1 (Birdcage 1)" em_port_simulation_extractor.UpdateAttributes() document.AllAlgorithms.Add(em_port_simulation_extractor) em_sensor_extractor = em_port_simulation_extractor["Endring source 1 (Birdcage 1)"] document.AllAlgorithms.Add(em_sensor_extractor) ref_coef_data = em_sensor_extractor.Outputs["Reflection Coefficient(f)"] ref_coef_data.Update() freqlist = ref_coef_data.Data.Axis ref_coef = refCoeff.Data.GetComponent(0) ref_coef_magnitude = np.sqrt(np.real(ref_coef)**2 + np.imag(ref_coef)**2) import matplotlib.pyplot as plt plt.plot(freqlist,ref_coef_magnitude)

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[image: 1736961843959-327c9ace-0099-4e59-b102-4a34c31e609c-sim4life_fxfwepw8sg.gif] to extract the inner normal vector to the cortical surface mask the field (set NaN outside GM) using the Mask Filter available under "Field Data Tools" in the top ribbion. add the Grey Matter Surface in the post-pro interpolate the (masked) field to the grey matter surface using the "Interpolator" which is active when the masked field and surface is selected. get the normal component via the NormalFieldEvaluator under the "Field Data Tools"

Okay, I will take those considerations into account. Thanks for the fast reply!

@Sylvain Hi Sylvain! Thanks for sharing the method. I tried it in this very simple structure but get unexpected result for current density. Also available at my post here https://forum.zmt.swiss/post/2071. I use the following very simple structure to test whether I am using the LF Ohmic Quasi-Static Solver correctly. The voltage comes out as expected but the current (density) is incorrect. I have these three electrodes of the same radius (1mm) stacking together (touching each other) in an electrode-cylinder-electrode configuration. I want to apply to a 2V (+1V top, -1V bottom) to the two silver electrodes and achieve a 1 kA current through. So I chose the cylinder material (copper) and length such that the resistance is 2 mOhm. After running the simulation, where I place a line as voltage sensor (it runs from 2mm offset from the top electrode to 2mm offset from the bottom electrode, in the centre), it gives a value of -1.9786V as expected. When I combine the J(x,y,z,f0) from the overall field and a plane I created and use flux evaluator to measure total current density as described here, unexpected resutls occur. I tried two different planes and they gave different results:: A block with 0mm thickness and 1m x 1m in area in the middle of the cylinder parallel to the electrodes, result: 1 A/m^2, multiply by the area gives 1A A cylinder with 0mm thickness and 1mm in radius in the middle of the cylinder parallel to the elctrodes, resutls: 49.7369 A/m^2, multiply by the area gives 0.156mA (P.S. why the current density has a unit of [A/m^2 m^2]?) Model, Simulation and Analysis details are summaried in the screenshots attached. [image: 1736740622839-img_5162.jpg] [image: 1736740622913-img_5163.jpg] [image: 1736740622953-img_5164.jpg] [image: 1736740634276-screenshot-2025-01-12-at-21.26.50-resized.jpg] [image: 1736740634609-screenshot-2025-01-12-at-21.27.16-resized.jpg] [image: 1736740634957-screenshot-2025-01-12-at-21.27.32-resized.jpg] [image: 1736740635384-screenshot-2025-01-12-at-21.31.17-resized.jpg] [image: 1736740635771-screenshot-2025-01-12-at-21.34.49-resized.jpg] [image: 1736740636120-screenshot-2025-01-12-at-21.35.28-resized.jpg]

As far as I'm aware it is not possible to suppress those messages. Maybe try writing your customized messages into a log file instead?

Hi! In all the tutorial python scripts this is shown. Within the python scripter you can click on the folder icon and choose "Open Example Script". There you will find lots of python scripts, that show how this is done. Here a small excerpt from the script "tutorial_emlf_parallel_plate.py": sim = CreateSimulation() s4l_v1.document.AllSimulations.Add(sim) sim.UpdateGrid() sim.CreateVoxels(path) sim.RunSimulation(wait=True) I suggest always creating a simulation, and an analysis function, that is then called in the RunTutorial function. It's best to then also create a main: def RunTutorial( path ): import s4l_v1.document s4l_v1.document.New() CreateModel() sim = CreateSimulation() s4l_v1.document.AllSimulations.Add(sim) sim.UpdateGrid() sim.CreateVoxels(path) sim.RunSimulation(wait=True) AnalyzeSimulation(sim) def main(data_path=None, project_dir=None): """ data_path = path to a folder that contains data for this simulation (e.g. model files) project_dir = path to a folder where this project and its results will be saved """ import sys import os print("Python ", sys.version) print("Running in ", os.getcwd(), "@", os.environ['COMPUTERNAME']) if project_dir is None: project_dir = os.path.expanduser(os.path.join('~', 'Documents', 's4l_python_tutorials') ) if not os.path.exists(project_dir): os.makedirs(project_dir) fname = os.path.splitext(os.path.basename(_CFILE))[0] + '.smash' project_path = os.path.join(project_dir, fname) RunTutorial( project_path ) if __name__ == '__main__': main()

Thank you, I could obtain the same also using this: analysis.exporters.MatlabExporter.ExportTo(matlab_exporter,matlab_exporter.FileName) Do you think it is a good solution as well?

@bryn Is the 6.8 displayed on the color bar the actual maximum field strength value? I exported the values and found that the maximum is around 5.9 instead. [image: 1735124755536-42fb974e-d830-42c2-8373-84c85ee63339-image.png]

@bryn @gc00 @halder Thank you so much, You've been very helpful !

You can open a smash file using import s4l_v1 as s4l s4l.document.Open(smash_file_path) You can save it using s4l.document.Save(smash_file_path) You can find a simulation using (assuming you have unique simulation names sim = [sim for sim in s4l.document.AllSimulations if sim.Name == "the name of your simulation"][0] If you want to load different models (from .sab file or .smash), but don't need to load e.g. simulations (in .smash file), you can import the file entities = s4l.model.Import(file_path) if you need to reset the document or model because you are accumulating too many entities and memory use is getting too high, you can use e.g. # reset the model sl4.model.Clear() # or keep entities, but discard model history import XCoreModeling as xcm xcm.GetActiveModel().ClearHistory() # or reset entire document (reset model, simulations, analysis) s4l.document.New()