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Using the frequency of max value from frequency domain study as objective function

Posted 14 ott 2022, 03:48 GMT-4 Structural & Acoustics, Acoustics & Vibrations, Optimization Version 5.3a 4 Replies

宇宣 林
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Hi,

I'm simulating a speaker and adjusting Cms to adjust f0 to desired frequency by optimization.

I know that coil velocity will reach it's maximum value when resonance, so I trying to use (maxop1(shell.u_tZ)-500[Hz])^2 as optimization function.

But the result seemed that every frequency is independent so maxop1() cannot get overall maximum value.

Is there any function or method to define the optimization?

Thank you in advanced.

4 Replies Last Post 7 nov 2022, 05:11 GMT-5
Edgar J. Kaiser Certified Consultant
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Posted: 2 years ago 14 ott 2022, 08:47 GMT-4

You may want to check this blog contribution: https://www.comsol.de/blogs/using-the-previous-solution-operator-in-transient-modeling/

I am not sure if the previous solution works in frequency domain studies. I used it successfully in time-dependent studies.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
You may want to check this blog contribution: https://www.comsol.de/blogs/using-the-previous-solution-operator-in-transient-modeling/ I am not sure if the previous solution works in frequency domain studies. I used it successfully in time-dependent studies. Cheers Edgar
宇宣 林
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Posted: 2 years ago 16 ott 2022, 21:39 GMT-4

Hi Kaiser,

Thank you very much. I'll give it a try.

Hi Kaiser, Thank you very much. I'll give it a try.
Kristian Ejlebjærg Jensen COMSOL Employee

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Posted: 2 years ago 31 ott 2022, 08:31 GMT-4

Which optimization solver are you using? Is it gradient based or not? The max/min operators are not supported for gradient based optimization.

Which optimization solver are you using? Is it gradient based or not? The max/min operators are not supported for gradient based optimization.
宇宣 林
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Posted: 2 years ago 7 nov 2022, 05:11 GMT-5
Updated: 2 years ago 7 nov 2022, 05:11 GMT-5

Which optimization solver are you using? Is it gradient based or not? The max/min operators are not supported for gradient based optimization.

Hi Kristian,

Thank you for your reply, I didn't notice that, I used BOBYQA as my optimization solver, I remember this solver isn't based on gradient based optimization.

Also, I found a method that can achieve my goal perfectly, in the objective function I simply typed in "abs(Ztot)" which means absolute value of impedance, then in frequency domain step I only typed my goal frequency, for instance, 550 Hz, by this method, I can simply adjust the control varaibles to maximize my objective function.

>Which optimization solver are you using? Is it gradient based or not? The max/min operators are not supported for gradient based optimization. Hi Kristian, Thank you for your reply, I didn't notice that, I used BOBYQA as my optimization solver, I remember this solver isn't based on gradient based optimization. Also, I found a method that can achieve my goal perfectly, in the objective function I simply typed in "abs(Ztot)" which means absolute value of impedance, then in frequency domain step I only typed my goal frequency, for instance, 550 Hz, by this method, I can simply adjust the control varaibles to maximize my objective function.

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