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## [ai-geostats] "Constrained" estimation / simulation

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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
Message 1 of 3 , Jul 20, 2004
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
• 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
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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