modelica

问题 I am referring to this post: alternative to sample function with varying sampling range I want to measure an RMS value (or a mean value) with a variable sampling frequency, which i can feed in as an input signal. The suggested way which nearly suits my need is the following: model RMS constant Real f_max = 2*2*asin(1.0); constant Real f = 1+abs(2*asin(time)); Real signal = sin(time); Real rms = if time < f then (if time < 1e-10 then signal else sqrt(i_sq / time)) else sqrt(i_sq_f / f); Real i

问题 I am building a control system with the Modelica Standard Library. But I got trouble in tuning the parameters in the PID system，so I wanna use a library that could do auto-tuning for the PID system. After some searching on Google, it seems there is no such a library in Modelica. My question: Could anyone recommend an auto-tuning library for the PID system? 回答1: You should take a look at Modelica IndustrialControlSystems (https://github.com/mbonvini/IndustrialControlSystems). It has some

问题 In Dymola, I often meet a nonlinear system initialization failure or maybe a stiff system that is hard to solve in the large thermo-fluid system, but for a simple system, there wouldn't be this kind of problem. My questions are: So I am wondering how much is the largest capability of solving a nonlinear system model? For example, how many nonlinear equations I could include in my model at most? Is there any setting in Dymola which allows increasing the capability of solving nonlinear system?

问题 In Dymola, I often meet a nonlinear system initialization failure or maybe a stiff system that is hard to solve in the large thermo-fluid system, but for a simple system, there wouldn't be this kind of problem. My questions are: So I am wondering how much is the largest capability of solving a nonlinear system model? For example, how many nonlinear equations I could include in my model at most? Is there any setting in Dymola which allows increasing the capability of solving nonlinear system?

问题 I would like to measure the total simulation and initialization time of a system of DAEs. I am interested in the wall-clock time (like the one given in Matlab by the function tic-toc). I noticed in Modelica there are different flags for the simulation time but actually the time I get is very small compared to the time that elapses since I press the simulation button to the end of the simulation (approximately measured with the clock of my phone). I guess this short time is just the time

问题 I would like to measure the total simulation and initialization time of a system of DAEs. I am interested in the wall-clock time (like the one given in Matlab by the function tic-toc). I noticed in Modelica there are different flags for the simulation time but actually the time I get is very small compared to the time that elapses since I press the simulation button to the end of the simulation (approximately measured with the clock of my phone). I guess this short time is just the time

问题 I build a large model in Dymola, there are nonlinear equations in this model, I wanna know which nonlinear equations decrease the performance and cause an initialization failure, but with the following settings of debugging, I can't see the nonlinear equations in the dslog.txt file, only the iteration variables, how could I find the nonlinear equations? 来源： https://stackoverflow.com/questions/61797757/how-to-see-the-nonlinear-equations-of-a-modelica-model-in-dymola

问题 I am writing this question related to this. In his reply, Marco gave me an excellent answer but, unfortunately, I am new with OpenModelica so I would need some further help. I am actually using OpenModelica and not Dymola so unfortunately I have to build the function that does it for me and I am very new with OpenModelica language. So far, I have a model that simulates the physical behavior based on a DAEs. Now, I am trying to build what you suggest here: With get time() you can build a

问题 In the documentation it is indicated, that cardinality() function is deprecated and should no longer be used. However, it is still used in the libraries such as ThermoSysPro. e.g. if (cardinality(C) == 0) then some code end if; where C is FluidInlet or FluidOutlet Could anyone give a simple example of how it could be replaced? 回答1: The usual solution is to make the connector conditional, and if enabled you require that it is connected. For physical connectors you can see how heatports and

问题 I have a FMU of a model and the use case is to change parameter values of the FMU to see the impact on the results. Is there a way to list top level parameters of the FMU using either FMPy or pyFMI if I dont' have access to the Modelica model? One of the process I have been following is to open the FMU using FMPy.gui and go through the list of parameters and then use them in the script but I would like to know if there an easier way of doing it so that I can list then in the Jupyter notebook