Applicable Version
V11, V12

Problem Statement
We have two process streams (X and Y) which mix and can only do so up to a fixed maximum ratio. Ratio can be variable depending on the absolute flow of Stream A. Stream A is a different LP column which is not itself part of the ratio control row but is present somewhere else in the same LP submodel.  When Stream A is at low rates, then this ratio increases and when Stream A is at higher rates then this ratio decreases; therefore, in summary the max ratio depends on the flow rate of Stream A.
Is it possible to create such structure in DR?

Solution
For AO this problem can be modeled easily using Non-linear Equations tool.
In DR we could try to resolve this issue involving PIMS-SI (in case you’re not planning to migrate to AO. Non-linear formulas are preferable still. Please note SI is not supported in AO).

For example, there is fixed ratio between two variables introduced – row Enewnew in ROWS (in your case it could be either G or L row) and want to vary that coefficient for DCN (now it is 5)



The following workflow could be used for control:
 

1. Define Excel Server

2. Define necessary independent variable as an Input (I defined SHCDBAS – random choice). Value will be populated from PIMS to Simulator

3. Necessary non-linear correlations can be defined in a separate spreadsheet. I used IF operator for testing

4. Result of calculation I would like to use as mentioned coefficient, so as an Output I specify the value should be used in PIMS for coefficient in the intersection of row Enewnew and SNHTDCN.

After run I can verify coefficient is changing dependent on SHCDBAS activity.

If you would like to see updated Excel, please activate “Save Excel Tables after PIMS-SI Calc…” in Tools|Program Options




Keywords
PIMS-SI
ratio
variable