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Modelica

modelica.org

61–70 of 118 posts

Re: Modelica

#61

How does this compare to Spice/verilog-A/Simulink?

You can do a lot of the same kinds of things with Verilog-AMS and VHDL-AMS. Generally with simulators there's a kind of analog to the Turing tarpit - it's not "can I model this thing I know how to model with differential equations?" but what tooling, graphical tools, optimizers, synthesizers, libraries, etc are available.

Re: Modelica

#62

From the website: > Modelica is a high-level declarative language for describing mathematical behavior. It is typically applied to engineering systems... We use Modelica quite a bit in HVAC industry. In my case (controls engineer), I can request FMUs of various components from systems engineers for optimization work. (Functional Mockup Unit (FMU)[1]: stand-alone binary representing a dynamical system that can be driv…

Does MATLAB also compete in the same field?

MATLAB/Simulnk is imperative. They have signal flow/causal approach. So you should know ahead of time which variable causes another variable to change i.e. which is defined first.

Modelica is acausal. You define the variables and how they are related (equations). The compiler handles variable dependencies and resolution internally.

There are pros & cons of each. Both are used for simulating cyber-physical systems.

Re: Modelica

#63
post #58
post #53

Earlier quoted context omitted.

Modelica underneath uses DAE (differential algebraic equations) [1,2]. Think of it like a solver for many coupled differential equations. The coupling happens through "linear" equality constraints. Such as "the output pressure variable of component A needs to be equal the input pressure variable of component B". Something that Modelica doesn't do very well is stochastic systems. There you would need to go into SDE an…

Any chance you know of good DAE books/resources that go into combining symbolics and numerics or parametrized DAEs?

There is an MIT course by the developers of MTK: https://sciml.github.io/ModelingToolkitCourse

Re: Modelica

#64
post #37

I finished university 4 years ago but just now I am going down the rabbit hole of bond graph modeling and studying directly from the MIT class notes of Henry M. Paynter [1] while simultaneously using Simscape at work for modeling vehicle systems. I understand that bond graphs are the underlying mechanism upon which Modelica and Simscape are built upon(?). Can any expert in this field give me some pointers. My current…

I actually would disagree that Bond Graphs are the "underlying mechanism" in Modelica. The Modelica community and the Bond Graph community are a bit at odds in fact. My side of this story can be found at [1] and [2]. I disagree with the idea that Bond Graphs will give you an intuitive understanding of just about every system. What it will give you is an appreciation for the elegance of the Bond Graph formulation. But…

I studied bond graphs in modeling & simulation courses in college. I thought they were so cool! The utility knife of understanding mechanical phenomena.

Until I discovered Hamiltonian physics :)

Re: Modelica

#65

I am now using Modelica with OpenModelica at work to describe electromagnetic systems and it is an excellent language and, with OpenModelica, a excellent graphical user environment. Sometimes I think of it like SPICE but for multi-physics systems. The Modelica library is quite mature and complete and the numerical solvers included with OpenModelica robust and performing. It looks me a while to learn it but now it is…

I remember using OpenModellica to test an Functional Mockup Unit where I extracted Neural Net as ONNX and the ONNX runtime DLL and then connected it to Simcenter Amesim as my student work at Siemens. Pretty okay standard compared to how old and crusty the APIs of engineering software are.

Re: Modelica

#68

From the website: > Modelica is a high-level declarative language for describing mathematical behavior. It is typically applied to engineering systems... We use Modelica quite a bit in HVAC industry. In my case (controls engineer), I can request FMUs of various components from systems engineers for optimization work. (Functional Mockup Unit (FMU)[1]: stand-alone binary representing a dynamical system that can be driv…

Another up-and-coming solution is Julia's simulation ecosystem [1]. It is powered by the commercial organization behind the Julia programming language, which has received DARPA funding [2] to build out these tools. This ecosystem unifies researchers in numerical methods [3], scalable compute, and domain experts in modeling engineering systems (electrical, mechanical, etc.) I believe this is where simulation is headed…

JuliaSim looks interesting! From my understanding, it's 100% proprietary/commercial, but built on top of the open source https://github.com/SciML/ModelingToolkit.jl?

Re: Modelica

#69
post #68

Earlier quoted context omitted.

Another up-and-coming solution is Julia's simulation ecosystem [1]. It is powered by the commercial organization behind the Julia programming language, which has received DARPA funding [2] to build out these tools. This ecosystem unifies researchers in numerical methods [3], scalable compute, and domain experts in modeling engineering systems (electrical, mechanical, etc.) I believe this is where simulation is headed…

JuliaSim looks interesting! From my understanding, it's 100% proprietary/commercial, but built on top of the open source https://github.com/SciML/ModelingToolkit.jl ?

I believe it's open source but requires a commercial license; free for academics.

Re: Modelica

#70
post #68

Earlier quoted context omitted.

JuliaSim looks interesting! From my understanding, it's 100% proprietary/commercial, but built on top of the open source https://github.com/SciML/ModelingToolkit.jl ?

I believe it's open source but requires a commercial license; free for academics.

To be slightly more precise, it's not open source, but source available.
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