uncertainty estimation?


Subject: uncertainty estimation?
From: Makropoulos, Christos (c.makropoulos@ic.ac.uk)
Date: Fri Sep 29 2000 - 21:52:50 MET DST


> dear all,
>
> I am currently using fuzzy sets as a standardization method in
> multicriteria spatial analysis. It is the classic GIS problem of
> suitability maps for application of specific techniques in "the best
> location". The technique's application (in this case water demand
> management strategies) are dependent on a number of different criteria and
> each criterion is standardized with an "appropriate" fuzzy set membership
> function. As you very well now there are several techniques of building a
> fmf but not much if you cant have field data: I can claim that a
> particular part of a network has a 0.8 vulnerability to leakage, but the
> fact remains that it either leaks or not. If it doesn't (where the concept
> of the fmf is applicable) there is no real way of measuring in-situ the
> actual vulnerability!.
>
> I have two questions on the subject:
> 1. How do you built a fmf for say vulnerability to leakage for a water
> supply network, due to diameter of the pipe when there is no clear
> theoretical function linking them. There is some statistical data simply
> saying the small diameters (<300mm) are more vulnerable than large ones
> and intermediate diameters are ... intermediate.
> 2. Say you can built a fmf with a simple shape translating broadly the
> statistical evidence I described. It is clear that the shape you choose is
> not the only possible one. This would yield a slightly different outcome
> if someone else chose another shape: the vulnerability map output would be
> different, how is this uncertainty quantifiable??? I know that giving a
> 0.6 membership is an indirect indication of uncertainty, but I am saying
> that this 0.6 is also uncertain to a large extend.
>
> This uncertainty quantification is a major issue in the applicability of
> operational maps (suitability, vulnerability, preferable location
> identification etc).
>
> Any ideas, references and contacts of this topic of uncertainty
> quantification in the use of fuzzy sets will be greatly appreciated!!!
>
> Thanks in advance
> Best Regards
>
> Christos
>
> _____________________________________
> christos k. makropoulos
>
> environmental & water resources engineering
> research group
>
> civil engineering department
> imperial college of science, technology & medicine
> london SW7 2AZ
> united kingdom
>

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