Page 313 - ExtendSim User Guide
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Activity-Based Costing 287
Modeling with activity-based costing
When a resource pool unit is released using the Resource Pool Release block, the information stored with the cost accumulator is modified to indicate that the resource has been released.
Unlike what happens where resource items are batched with other items, there is no limit to the number of different types of resources a cost accumulator can use when using the resource pool blocks. Furthermore, the two methods of modeling resources (batching resource items and resource pools) may be used in conjunction with each other.
Combining cost accumulators
The Batch block can be used to combine cost accumulators arriving from one or more paths. This may be used in conjunction with an Unbatch block, for instance to combine cost accumu- lators for processing and separate them after processing has been completed. In the Properties tab of both the Batch and Unbatch blocks you can specify what the block should do with the cost values. This is accomplished by selecting an Action for the _cost and _rate attributes.
Costing attributes when items are unbatched
For example, assume a Batch block combines three cost accumulators together and that while batched, these items accumulate an additional $9.00 due to processing. When these cost accu- mulators are unbatched, you can select one of the following actions for the _cost and _rate attributes in the Properties tab of the Unbatch block:
• Preservedvalue.Thisoptioncausesthecostaccumulatorstoretrievetheirpreservedvalue, if “preserve uniqueness” is turned on. In this case, the $9.00 is discarded.
• Batchedvalue.Withthischoice,the$9.00willbecop- ied to each of the resulting cost accumulators.
• Distribute.Thevaluewillbedividedamongeachitem equally. In this case, $3.00 to each.
☞ For more information, see “Preserving the items used to create a batch” on page 219 and “Properties when items are batched” on page 213.
Working with cost data
To provide access to cost information, ExtendSim creates two attributes (_cost and _rate) for every item in models that have costing. Since these are automatically created, they are consid- ered system attributes. If a cost is defined somewhere in the model, these attributes will appear in attribute popup menus, shown below:
Attribute popup menu
Discrete Event

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