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[ai-geostats] "Constrained" estimation / simulation

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  • Steinar Løve Ellefmo
    Hi All, I m estimating and simulating an iron ore deposit. The decisive ore parameters are total iron, FeTot and iron in magnetite, FeMagn. Clearly FeMagn can
    Message 1 of 3 , Jul 20, 2004
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      Hi All,

      I'm estimating and simulating an iron ore deposit. The decisive ore
      parameters are total iron, FeTot and iron in magnetite, FeMagn. Clearly
      FeMagn can not be larger than FeTot.

      FeMagn and FeTot is not correlated (coefficient of variation (CV) of
      FeMagn is much larger than the CV of FeTot). Domaining based on ore
      type is not practically possible.

      Is it possible to somehow "constrain" FeMagn realisations or estimations
      so that FeTot are the largest of the two?

      Any publications on the subject?

      I'm using Isatis.


      Best regards,

      Steinar Ellefmo
      Norwegian University of Science and Technology
      Norway
    • Julián Ortiz
      Hi Steinar, The exact same problem you have is addressed in: Stepwise Conditional Transformation for Simulation of Multiple Variables by Oy Leuangthong and
      Message 2 of 3 , Jul 20, 2004
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        Hi Steinar,

        The exact same problem you have is addressed in:

        "Stepwise Conditional Transformation for Simulation of Multiple Variables"
        by
        Oy Leuangthong and Clayton V. Deutsch, Math Geology 35(2):155-173, Feb.
        2003.

        What they propose is to normally transform the secondary variable
        conditionally to
        classes of the normally transformed primary variable. This transformation
        removes
        the cross-correlation at distance 0 (collocated) and often minimizes
        cross-correlation
        at lags different than 0, between the variables. Gaussian simulation can
        then be performed
        independently for each conditionally transformed variable. The simulated
        values must be
        back-transformed using the same "rule" created in the forward
        transformation, which will
        reinject any order relation they may have (such as FeTot>=FeMagn).

        Hope this helps.

        Julián Ortiz C., Ph. D.
        Assistant Professor
        Department of Mining Engineering
        University of Chile

        Phone: +56 2 678 4585
        Fax : +56 2 672 3504
        Web : www.ualberta.ca/~jmo1


        -----Mensaje original-----
        De: Steinar Løve Ellefmo [mailto:steinar.ellefmo@...]
        Enviado el: martes, 20 de julio de 2004 5:49
        Para: ai-geostats@...
        Asunto: [ai-geostats] "Constrained" estimation / simulation


        Hi All,

        I'm estimating and simulating an iron ore deposit. The decisive ore
        parameters are total iron, FeTot and iron in magnetite, FeMagn. Clearly
        FeMagn can not be larger than FeTot.

        FeMagn and FeTot is not correlated (coefficient of variation (CV) of
        FeMagn is much larger than the CV of FeTot). Domaining based on ore
        type is not practically possible.

        Is it possible to somehow "constrain" FeMagn realisations or estimations
        so that FeTot are the largest of the two?

        Any publications on the subject?

        I'm using Isatis.


        Best regards,

        Steinar Ellefmo
        Norwegian University of Science and Technology
        Norway
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