For defining uncertain variable costs for some process flows or activities, I would say that the easiest way is to use S_FLO_FUNC.
For example, to define uncertain activity costs in a stochastic scenario, you could define:
Code:
FLO_EMIS(r,y,p,'ACT','ACTCOST','ANNUAL') = 1; <br>FLO_COST(r,y,p,'ACTCOST','ANNUAL','CUR') = 1;<br>S_FLO_FUNC(r,y,p,'ACTCOST','ACTCOST',stage,sow) = X;
where ACTCOST is a new commodity of type ENV and LIM type 'N'). Here X represents the uncertain activity costs X per unit of activity, by stage and sow. The cost X can be positive, negative, or zero, and so you can model uncertain variations in either direction.
No changes are needed in the process topology (i.e. there is no need to add ACTCOST into the topology). Compared to using a dedicated attribute (e.g. S_ACT_COST), basically the only difference is the additional FLO_EMIS parameter that is needed here.
Note also that using the S_FLO_FUNC approach doesn't create any new variables or equations into the model. So, it is also in that sense equivalent to using a dedicated new attribute. The additional advantage is that you can use the same approach for defining uncertain variable costs on
any process flows, not just activities. And the approach can be used for trade processes as well.
For trade processes, you can define FLO_EMIS(r,y,p,'ACT','ACTCOST','ANNUAL') as mentioned above, but for specific process flows you must use IRE_FLOSUM instead.
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