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Batching and Unbatching
Blocks of interest
In a discrete event model, items pass through the system and something is done to or with them. The process often involves temporarily or permanently joining, or batching, resources or other items with the original item. For instance, in a manufacturing plant, precursors of the final products come into the process as raw materials, subassemblies, and packaging that are joined in various combinations. During the manufacturing process they are often batched with other precursors and require additional resources such as pallets and workers for processing. These batched items move through the process together.
These same concepts apply to other discrete processes. For example, in an emergency room model, doctors are temporarily batched with their patients during medical diagnosis. In the same model, a technician, a diagnostic machine, and a patient would be batched for the dura- tion of x-ray treatment. In a communication system, multiple packets might be batched together to create a single message. For a retail store model, customers could be shown arriv- ing and selecting merchandise, then be temporarily batched with a sales person to make the purchase.
This chapter discusses:
• Blocks for batching and unbatching
• How to batch and unbatch items
• Dealing with item properties when items are batched or unbatched
• Delaying the batching of items until all requirements are present
• Preserving unique item properties as items are batched and unbatched
☞ The models discussed in this chapter can be found in the folder \Examples\Discrete Event\Batching.
Blocks of interest
The following blocks will be the main focus of this chapter. The block’s library and category appear in parentheses after the block name.
Batch (Item > Batching)
Joins multiple items into a single item for use in the model. This causes the original
input items to be destroyed and replaced by one output item. A batched item may be unbatched at a later point in the model, but that is not required.
Unbatch (Item > Batching)
Outputs multiple items for each input item. Depending on selections in the dialog, this block can separate items that were previously batched or make duplicates of items that were never batched.
Batching allows multiple items from different sources to be joined as one new item for simula- tion purposes (processing, routing, and so on). The Batch block accumulates items from each source up to a specified count, then releases a single item that represents the batch. In this pro- cess, the original input items are destroyed and replaced by one new output item.
☞ Items may have properties, such as attributes, before they are batched. To specify what will happen to the properties of items that have been replaced by a new batch item, see “Properties when items are unbatched” on page 218.
Discrete Event

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