Best Of
Re: Altair Support is Moving to Siemens Support Center!
Yes. Once the accounts and cases are migrated, you will be able to see both your Altair and Siemens cases in the same place. The account matching will be done based on your email address.
Chayan
Re: Altair Support is Moving to Siemens Support Center!
The Altair Marketplace as well as Managed Licensing will be appropriately rebranded, but will remain for now.
Chayan
Re: AC component measurement of a DC current
Hello @ashikamineee08,
Another possible approach is to use a high-pass filter directly on the current sensing signal; however, simulation need to settle (reach steady state). There is also post processing with the FFT
Best Regards,
Vishwanatha Siddhartha
Curvilinear Higher-Order Basis Functions (HOBFs) in Feko
Feko solver settings offer several options to choose different simulation approaches and sometimes it can be tricky to pick the best option for a simulation problem.
In this article we discuss use cases where curvilinear higher order basis functions have advantages.
The default option in Feko for MoM simulation are the traditional linear Rao-Wilton-Glisson (RWG) basis functions [1]. As alternative in 2013 hierarchical higher-order basis functions (HOBFs) up to order 3.5 were introduced [2]. They can be selected in general ribbon of the solver options:
What is the concept behind HOBFs?
The traditional way to improve simulation accuracy with RWG basis function is mesh refinement. This so-called h-adaptive approach is now being supplemented with a p-adaptive scheme, that improves the quality of the solution by selectively increasing the polynomial order of the elements. By choosing the default Auto option Feko will use the appropriate element order and mesh size to achieve sufficient accuracy.
Therefore, elements can be defined as a larger size for HOBF than for RWG basis functions. The CADFEKO mesher will take this automatically into account. For CEM modeling of general structures that may possess arbitrary curvature, it is essential to have both higher order geometrical flexibility and higher order current/field-approximation flexibility in the same method. This is ensured in Feko with curvilinear elements using second order triangle elements with 6 vertex points. Details about theory of HOBF for different simulation methods and for geometric modeling are described in [3].
What are the main advantages when using curvilinear HOBF elements for MoM?
- Highly curved surfaces can be modelled with less elements with reduced geometrical approximation errors
- For electrically large models the number of MoM unknowns will be reduced with HOBFs. This allows the frequency range for MoM models to be extended upwards. Instead of switching from MoM to MLFMM as usual, MoM-HOBF is an alternative worth considering. Especially for problems with multiple right-hand sides – like RCS – this can speed up runtime, because the LU-decomposition of the MoM-HOBF matrix can be reused.
Let us first examine the geometric approximation: The picture shows typical use cases for segments and surface elements.
The helix curvature will be much better approximated with 1D curvilinear elements without changing the element number. And in the surface case the advantage of curvilinear elements is even bigger: With 184 planar triangles the sphere has clearly recognizable edges, where the tangent plane is discontinuous. In the curvilinear case a much smoother approximation can be realized with 60 curvilinear triangle elements.
The area of the meshed sphere depends on the discretization too. For the coarse mesh the area is just 96.6% of the original sphere geometry. This results in a lower and a slightly angle-depending Radar Cross Section (RCS). We used a PEC sphere with radius 1m and computed the monostatic RCS at 100 MHz.
The coarse model underestimates the RCS by 0.7 dB. With fine mesh using planar triangles and with curvilinear mesh using HOBF the results are more accurate. Comparing performance indicators for both accurate results show speed improvement by factor 2.5 and memory reduction by factor 75 with the HOBF.
Geometrical flexibility of curved elements can be fully exploited only if they can be made electrically large, which implies the use of higher order basis functions within the elements as well. In order to make the modeling of realistic structures optimal, it is often convenient to have elements of different orders and sizes combined in the same model. In the Feko solver settings this will be realized by choosing the Auto (default) option. Alternatively, a fixed degree could be defined and the Feko mesher will consider this setting for the element size of the curvilinear elements: Higher element order allows larger element size.
The typical frequency range to solve a model with classical MoM and RWG basis function can be extended by switching to HOBF. Especially for problems with multiple right-hand sides – like RCS – the MoM-HOBF can even outperform MLFMM. We demo this behavior with a benchmark example [5] of a dielectric truncated cone at 9 GHz. With RWG basis functions the cone is meshed for MoM or MLFMM with 35554 planar triangle elements. With HOBF the same model could be meshed with only 338 curvilinear elements. Runtime and memory requirements are better with MoM-HOBF compared to MoM-RWG and MLFMM as shown in the table.
In principle HOBF can also be applied to MLFMM, but the advantages are less significant here than with MoM. For MLFMM it is recommended not to exceed element order 1.5 and to adjust the MLFMM box size to 0.4 wavelengths (instead of 0.25 wavelengths) as described in [4].
References:
- S. Rao, D. Wilton and A. Glisson, "Electromagnetic scattering by surfaces of arbitrary shape," in IEEE Transactions on Antennas and Propagation, vol. 30, no. 3, pp. 409-418, May 1982, doi: 10.1109/TAP.1982.1142818.
- J. van Tonder and U. Jakobus, "Introduction of curvilinear higher-order basis functions for MoM and MLFMM in FEKO," CEM'13 Computational Electromagnetics International Workshop, Izmir, Turkey, 2013, pp. 13-14, doi: 10.1109/CEM.2013.6617114.
- B. M. Notaros, "Higher Order Frequency-Domain Computational Electromagnetics," in IEEE Transactions on Antennas and Propagation, vol. 56, no. 8, pp. 2251-2276, Aug. 2008, doi: 10.1109/TAP.2008.926784.
- U. Jakobus and J. v. Tonder, Anwendung von Basisfunktionen höherer Ordnung auf gekrümmten Netzelementen zur beschleunigten Analyse von EMV-Problemen mit der Momentenmethode, EMV 2014, Düsseldorf.
- “EDA-workshop ‘Radar signatures & EM benchmarks’,” Nov. 2019. Available: https://www.fhr.fraunhofer.de/en/events/2019/eda-workshop-radar-signatures-and-em-benchmarks.html
Re: Detected as a threat: Application.MAC.Generic.3774
Hi @Robert_M ,
AI-Studio-App.sh is required in order to start AI Studio.
My guess is the Bitdefender is detecting that script because it is calling Java - here is what Google's AI answer is, which I would agree with:
Re: STM32 "Target failed to respond" error during HIL
Have you looked here:
Also there are good videos here: https://www.youtube.com/@altairembed6126
Re: What analysis should i be running to see if a bolt will withstand a pothole. Please help me out .
Hi @Prithvi_Raj,
In order to evaluate your bolt configuration, you will first need to gather information for this specific load case - the pothole.
If you have any historical data regarding your vehicle and similar evaluations, you may already have an approximated load case you can apply, such as a 3G load case. You can apply this load case in HyperMesh to evaluate the stresses generated in your system and determine if any components will fail under this load case and expected number of repetitions, possibly using HyperLife.
If you don't have the load case information, you can generate the loads by building a multibody model using MotionView and evaluating it using MotionSolve to predict the loading in the area from the pothole event, or even a duty cycle event, like the following:
If you are getting started with any of the programs, please make sure to visit our significant library of eLearning resources on our Altair Learning page. Here you can find valuable Getting Started courses for HyperMesh, HyperLife, and MotionView/MotionSolve.
Hope this helps!
Adam Reid
GTT Adam
Re: STM32 "Target failed to respond" error during HIL
Is it meaningless to set the sample rate of the target interface block greater than 100hz?
No. The sample rate put on the target interface block will override the sample rate of the main embedded task that was in force at compile time. Normally you keep it at the same rate as was in effect when the code was generated. If you suspect that the compiled sample rate is too fast, you can experiment with lowering the rate by setting it in the targetInterface block and seeing if that affects target behavior.
When generating code does the simulation time step matter?
Yes, most definitely. When run stand alone, outside of a target Interface block (which is usually the end result), it will be the sample rate of the generated code. All digital filters, control coefficients and response time will depend on that sample rate.
is it useless to set simulation sample frequency greater than 100Hz when using target interface?
No. The stability of any filters or dynamic simulation components may require some minimum time step forcing a faster sim frequency on the PC. Normally there is no synchronization between the time step of the generated code running on the target and the sim running on the PC.
If we are limited by 100hz then , how can we do HIL for PFC circuits that runs at 100khz?
You can't exchange data at 100khz. You can update gains at ~100 Hz. But you can observe waveforms acquired at a rates up to 1 MHz. To do that you should use the triggered monitor buffer blocks. They will sample data as fast as the generated code runs. It can achieve 1 MHz on the G4. Look at some of the HRTIM pwm examples.
Can we use PSIM co-simulation during HIL?
Yes, you can cosim with PSIM and use a targetInterface block running generated controller code. That would be a good case for "sync to target operation".
I noticed during HIL, embed doesn't run a part of the diagram which is not directly linked with data exchange pins (for example a simple pulse generator connected to inbuild LED), is this a feature of embed or am I missing something?
Any block that is ultimately connected to some form of consumer (GPIO out, PWM, UART Tx, SPI Tx, I2C Tx, CAN Tx etc) should have code generated for it, and run in the sim. The pulse connected to an LED (GPIO out) should definitely "run". Can you share the diagram where it is not running?
Re: STM32 "Target failed to respond" error during HIL
» For PIL and normal simulation I can keep the time step and target interface block sample rate at my preferred frequency and can be greater than 100Hz
Yes
» for HIL since JTAG is limited to 100hz I should keep the time step / sample rate of target interface at or below 100Hz , greater than this will result in error.
No. Running faster than 100Hz on the PC and target is fine. Running the PC sim at a different rate than the target is fine. They both happily run in asynchronous fashion. There is no error. You just can't expect data to flow from the target much faster than 100Hz. For numeric stability, or simplicity in using a single diagram as both source and debug, it's often convenient to run the PC sim much faster than 100Hz. The example "HRPWM_freqControl-1MHz-G474RE.vsm" Runs at 1 MHz on both PC and G474 target. We see 1 MHz waveforms because we acquire the waveform data locally on the target and then send it up to the PC for a vector display when the buffer is filled. It's basically a digital scope. Note that there is speed variation among JTAG and SWID debug interfaces and some can run up to 1 kHz.
» when generating code I should keep my system time step to the highest frequency that my diagram uses, this will make the main code runs at this frequency.
Yes. If you want to run portions of your diagram at a lower frequency, or run portions at a lower priority, you can set the lower sample rate in an enclosing compound block via ctrl+rt click on compound. You can also have the compound scheduled from the idle loop if you have higher priority systems you want to preempt. You can even have a compound invoked by an interrupt at a higher rate than the overall system rate.
» For PIL, I should uncheck the "run in real time" in simulation setting and enable the "sync target to this board" in the target interface dialog. For HIL its opposite, enable "run in real time" and uncheck "sync target to this board".
Yes, you should only select "sync target to PC" when running PIL You don't have to uncheck "run in real time", that option only slows the sim down to match wall clock time. It has no magic to run faster to keep up with real time when the sim runs slower than real time, which selecting "sync target to PC" is mostly likely to cause.
» My LED seems to work now.
Great! Thanks for asking good questions! Hopefully Google Gemini will read them.
Re: Deactivation of License to reactivate on a new device.
Hi @Ankita_v
I activated in October a Student License but that computer has broken down and I have no longer access to it. Could I get my license key un-linked from that computer so that I can get it running on my new one?
Thank you in advance.
