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Using standard deviation operator in optimization objective function

Posted 2024年11月22日 GMT+1 17:27Heat Transfer, Optimization, Results & VisualizationVersion 6.22 Replies

Sujeong Lee
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Hello.

I want to definestandard deviation of temperature distribution of the load after 60 seconds of heating **( time at 60s) ** as objective function in shape optimizationmodule.

My study is consists of two steps, frequency domain and time dependent.

I made integration operation of the domain of the load in non local coupling section,intop2Then i could get standard deviation at specific time (60s) by defining Derived values - global evaluation using stddev() built in operator,stddev('comp1.intop2',T).

However, I have no idea how to define objective function using stddev('comp1.intop2',T). stddev() does not work here. Also, I am struggling how to define standard deviation of temperature at specific time as objective function.

I appreciate any advice.

2 Replies Last Post 2024年12月11日 GMT+1 06:50
Kristian Ejlebjærg Jensen COMSOL Employee

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Posted: 1 year ago 2024年11月25日 GMT+1 15:47
Updated: 1 year ago 2024年11月25日 GMT+1 15:52

Hi Sujeong

The stddev operator is just an integration operator behind the scenes as described in thedocumentation, which contains an error, but it should say stddev('comp1.intop1',X) = sqrt(comp1.intop1((X-comp1.intop1(X)/comp1.intop1(1))^2)/comp1.intop1(1)), so you can just make your own variable equal to the standard deviation (you are allowed to have an integration operator inside another integration operator).

Optimization of time dependent problems only support evaluation of the objective function at the final time (except for parameter estimation), because there is no reason to continue the computation beyond the point where the objective is evaluated. If you want to integrate in time, you can use an ODE. The library model tesla_microvalve_transient_optimization demonstrates this.

Best regards,

Kristian E. Jensen

Technical Product Manager, Optimization

Hi Sujeong The stddev operator is just an integration operator behind the scenes as described in the [documentation](https://doc.comsol.com/6.2/docserver/#!/com.comsol.help.comsol/comsol_ref_definitions.19.029.html%232150205), which contains an error, but it should say stddev('comp1.intop1',X) = sqrt(comp1.intop1((X-comp1.intop1(X)/comp1.intop1(1))^2)/comp1.intop1(1)), so you can just make your own variable equal to the standard deviation (you are allowed to have an integration operator inside another integration operator). Optimization of time dependent problems only support evaluation of the objective function at the final time (except for parameter estimation), because there is no reason to continue the computation beyond the point where the objective is evaluated. If you want to integrate in time, you can use an ODE. The library model tesla_microvalve_transient_optimization demonstrates this. Best regards, Kristian E. Jensen Technical Product Manager, Optimization
Sujeong Lee
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Posted: 1 year ago 2024年12月11日 GMT+1 06:50

Hello. It worked! thank you so much.

Hello. It worked! thank you so much.

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