Page 460 - ExtendSim User Guide
P. 460

434 Miscellaneous
Biasing flow
maximum effective rate which could circulate at its location, without taking into consideration the preferences expressed by blocks with a lower bias order. When its maximum effective rate has been determined, that rate will be fixed for the succeeding calculations involving blocks with lower rankings.
• The bias order of Bias blocks can change dynamically during the simulation
• IfmultipleBiasblockshaveidenticalbiasorders,thewaytheflowisdistributedbetweenthe effective rates cannot be predicted. The model will use one of the possible solutions.
• If a Bias block has a bias order that is Blank or is less than or equal to 0, the block does not express any preference.
Prioritize With Bias Blocks model
This model illustrates how Bias blocks can be used to indicate preferences for flow. It is similar to the Com- peting Requests for Flow model discussed on page 396. How- ever, this model uses Bias blocks to indicate the preferred route for flow, rather than bias order settings in Merge and Diverge blocks set to Priority
mode. Prioritize With Bias Blocks model
In the Prioritize With
Bias Blocks model, the Merge and Diverge blocks at set to Neutral mode and the Bias blocks indicate flow preferences. The results are identical to the Competing Requests for Flow model.
☞ This model is located in the folder \Examples\Discrete Rate\Merge and Diverge.
Merge and Diverge blocks
As shown in the “Mode table” on page 387, some Merge/Diverge modes use a fixed rule to obtain or distribute the flow. For other Merge/Diverge modes, flow rules are only invoked in specific situations depending on model conditions.
Because it influences the way flow is distributed, the bias concept only applies to Merge or Diverge blocks set to non-fixed rule modes: Distributional, Priority, or Sensing. To avoid con- fusion when Merge or Diverge blocks have competing requests for flow, blocks with these modes must specify a bias order.
Fixed rule modes
The Batch/Unbatch, Proportional, and Select modes all use a fixed flow rule to obtain or dis- tribute flow. For example, the way flow is distributed between the branches for a Merge/ Diverge in Proportional mode will follow the proportions set in the block’s dialog. No matter what happens in the rest of the model, the proportions will be respected.
The bias setting options in these block’s Model Settings tabs will be disabled.
Discrete Rate

   458   459   460   461   462