Is it possible to replace a computational model that does not have open source code?

UQ with UQLab Community Q&A and How To
1

I’m conducting a metamodel study of the software called ‘LIFESIM’, but I don’t understand how to write the computational model in ‘UQLab’ because the code is not open source and the model is complex.

I’m trying to understand how to compare results from my computational model with the metamodel. If I input the same data and run it through the metamodel, wouldn’t I get the same results?

This reference is available here:
Water | Free Full-Text | Quantitative Assessment of Uncertainties and Sensitivities in the Estimation of Life Loss Due to the Instantaneous Break of a Hypothetical Dam in Switzerland (mdpi.com)

2

Is it enough to take the input and output data and put them into a table to be called by UQLab?

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For a PCE model, I think you can directly use the input-output dataset to build the metamodel. See section 2.5 of this manual.

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Good afternoon, thank you for the response. Would these input data be only input parameters that will be evaluated for uncertainties?

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Dear @Juliana_Maia ,

I think it will depend on the model you choose. For example, it is enough to use only the input-output dataset for a Kriging model. However, for a PCE model, I think you should also define the input object to create appropriate basis functions.

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6

Dear @Juliana_Maia

As discussed above, you can use your input/output data directly with certain surrogate models such as Kriging (a.k.a. Gaussian process models), support vector machines, etc. When using (sparse) polynomial chaos expansions, you need to define also an Input object that contain the distributions of the parameters which your input samples were drawn from, e.g. uniform, Gaussian, etc.
If you generated these samples by your self, you probably have this information at hand.

You will find a similar UQLab example here. Your data is simply passed to the metamodel options as:

MetaOpts.ExpDesign.X = X;
MetaOpts.ExpDesign.Y = Y;

Alternatively, if you plan to construct many metamodels of this code, you can wrap it using the UQLink module.

Don’t hesitate to ask further questions on this channel. This helps the whole UQ community!
Good luck
Bruno

1 Like
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Thanks, @YuanXi_Wu!!

8

Thank you very much for answering my questions, I was really worried and trying to better understand the metamodel - PCE.