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

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

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    AntoninoMCA
    @KK The titration procedure provides a scaling factor that must be applied to the stimulation source (incident E-field, input current, or voltage applied at electrode pairs) in order to initiate an action potential in a fiber or neuron. Here are some examples depending on the stimulation source: Source: Incident E-field (e.g., induced by TMS) Assume the incident electric field is 1 V/m, and the titration procedure yields a titration factor, tf. The threshold E-field is therefore tf [V/m]. If this 1 V/m field results from a coil current rate of change dI/dt = A [A/s], then the threshold dI/dt required is A × tf [A/s]. Source: Applied voltage Let the applied voltage across an electrode pair be V = V₀. This value is also used as the Dirichlet boundary condition in low-frequency (LF) simulations. If the titration factor is tf, the threshold voltage becomes V₀ × tf [V]. Source: Applied current Let the applied current to an electrode pair be I = I₀, typically derived from LF simulations via a current flux integrator. With a titration factor tf, the threshold current is I₀ × tf [A]. The titration factor tf is a dimensionless number that gains physical meaning when applied to the relevant stimulation quantity (electric field, voltage, or current). @LJ was suggesting the correct course of action. I hope this clarification is helpful!
  • FDTD Simulation Fail

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    ofliO
    Dear Aiping, please send the simulation file to the support team. Thanks.
  • This topic is deleted!

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  • Different frequencies in electrodes

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    H
    @pastis Hello, Have you solved this question? can we compare the amount of electric field that reach the targeted region to evaluate the TI simulation ?
  • Neuron solver failed

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    H
    Hello, It seems that you now have the Neuron installer and it is working, but something is missing in your setup. Could you please check for error messages in the Console? One possible reason could be that you have installed NEURON before Sim4Life completely finished its installation. Please uninstall Sim4Life, install it again, and only after finishing install NEURON.
  • RAM Usage Limit

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    H
    Hello, Unfortunately there is no direct way from Sim4Life to limit the amount of RAM to allocate for the program. You may be able to do so using external tools that tap into the operating system's settings and manage the resources. But we are not aware of any and we did not test any that we would recommend. The reason your PC is slowing down is because the OS switches to paging on disk instead of using fast RAM. Paging is slow and uses CPU resources. My guess is that even if you limit the RAM for Sim4Life, the solver will still need a lot more memory and it will either fail or use the disk for paging resulting in the similar slowing effect.
  • Magneto Quasi-static simulations stop

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  • conformal mesh

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    brynB
    If the cable bounding box is smaller than the body, maybe you could use sub-gridding.
  • MPI only starts 1 process

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    H
    Hi @Pedro The FDTD solver does not make use of any CPU parallelization and is actually not very suitable for CPU computation except for very small simulations. It is strongly recommended to run FDTD on GPU to benefit from much higher simulation speeds.
  • EM LF solver: Symmetric vs Asymmetric Dirichlet boundary condition

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    SylvainS
    Hi, most likely you have some other boundary conditions that are affecting the solution. Please share a screenshot of your boundary condition settings, maybe there is a clue there.
  • Error in loading neuron model

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    H
    How can I get the download code of neuro solver?
  • EM LF electro simulation

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  • EM LF solving problem

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    H
    Hello, Could you please explain a bit more what you mean by two operations and different results. Please provide any data or screenshots that you think would help us understand the problem.
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    H
    @christos1996 when I reach into the "Sensors" setting at Simulation Settings (Neuron)], the option "Point "Sensor Tool" is not available to click into. I am sure I have load the model. So have you solved this problem? how to solve ? hope you can reply me .
  • Correct time delay between transducers

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    M
    What do you mean with 'it is a real struggle' to calculate the phase? I used a python script for this. Would this be an acceptable solution? The idea is this (all in Python): Have a list of points indicating the coordinates of the base of the tranducer (can also be automated via Python) Interpolate the field values (complex values) of the reverse simulation at these points Calculate the phase of the complex value and conjugate it Create new simulation and add these phase values to the different sources of the transducer
  • Error misunderstanding

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    L
    I didn't do Python scripts yet so it is only when using the GUI. But I don't know which action because I realized after quite a time that the error was there, I could run the script anyways :)
  • simulation with 10k spheres

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    M
    Additionally, check the Boundary Settings on the Outside (your first Boundary Settings). Seems you set the potential of the spheres to the same value as the outside boundary of your domain and that's why it's constant outside the spheres and at the domain walls as well (hard to make sense of the problem with the dimensions you mentioned and what's displayed in the plots). Also, when setting Voltage (Dirichlet) boundary conditions, make sure to set a 'reference' (Ground: 0V) voltage somewhere
  • how to make current source for EM LF solvers?

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    SylvainS
    @hitina please see my answer here
  • homogeneous and heterogeneous of skull

    acoustic slover homogeneous
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    M
    Ok, we could set up a call for this ... The Mida model won't really work since it's based on MRI images which doesn't have good contrast for Bone. The typical approach utilizes CT images (known acoustic property maps use CT data as well)
  • stimulation

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    H
    @gbgbha you are right.thanks you very much.
  • How to use unstructured LF solvers with parameter sweeper?

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