Provides a stock or resource of items for the model. This block is most often used when a pool of resources is required for the model or to represent situations where processes already have a backlog when the model starts (such as a pile of work already on a worker's desk). Repository items typically represent tasks, orders, equipment (such as computer time), and so on.
The initial number is set in the dialog. The block holds items in FIFO order until they are required by the model and keeps count of the remaining number of items available. Items can be returned to the block to replenish the stock. If more items are required by the model than are available, projects and processes will be required to wait until an item is returned to the Repository and becomes available.
Dialog Choices:
Initial number: Enter the number of items initially available. The default is 0. If there are no initial items, the repository works just like a FIFO queue.
Items currently available: Displays the number of items available in the repository at the current time. If some items are currently in use, this number will be less than the initial number of items.
Set attribute, priority (optional): To assign one attribute and a priority to all items as they leave the block, specify a priority and an attribute name and value in the dialog. You can have different Repositories with different attributes or priorities of items, for example orders and computers.
Strip attributes from incoming items: When checked, will remove all attributes associated with incoming items. This option should be used with caution, since attributes that have been removed cannot be recovered.
Utilization rate: Displays the utilization rate. This shows the ratio of time that items are busy, based on the total number of items in the repository. For example, if 2 items out of 5 are used 100% of the time, and the other 3 items are never used in the model, the utilization is .40 (40%). The idle time rate is 1 minus the utilization rate. Note that utilization only makes sense if the block is used as a closed system (limited resource) where you set an initial number of items and the items return to the block when they are no longer used. However, if there is no initial number of items and you just show items flowing in and out of the block (for example, from some other source), the block cannot calculate utilization correctly since there is no base for the calculation.
Connectors:
The item input connector returns items to the repository.
The item output connector provides items to the model.
#: The number of items currently available in the repository.
u: Outputs the utilization of the repository.
Animation:
A green circle appears when an item enters or exits the block. A numeric display and a blue level display the contents of the block. The level graphically shows how the contents compare to a minimum and a maximum level amount. The minimum level amount is 0 and the maximum level amount is usually the "Initial number" of items. However, if additional items are added to the block (increasing the number above the initial number), the maximum level amount will be the higher number.
