Page 225 - ExtendSim User Guide
P. 225

Simulate Multitasking Activity model
In this example model, there are three kinds of jobs that are being processed on a computer. The computer must share its time between all the jobs it is simultaneously working on.
Simulate Multitasking Activity model
The Simulating Multitasking Activity creates a random number of each type of job (small medium and large), as determined by probabilities entered in the Random Number block (Value library). Each job has a Job Size attribute with the string value small, medium, or large. The job’s processing time is defined by a distribution and entries in a table in the dialog of the Activity block, which is set to Delay is: from a lookup table. (For a description of this set- ting, see “Processing time for an Activity” on page 181.)
Running the model shows that the moving average processing time increases as the number of items in the Activity increases.
☞ Changing the capacity of the Activity changes the number of items allowed in the block, but it does not change the calculation for the delay time. Thus, if “Simulate multitasking activity” is enabled, increasing the capacity will not necessarily increase the throughput rate of the Activ- ity block.
Kanban system
A kanban just-in-time (JIT) inventory system limits the amount of inventory between process- ing stations with a controlling “kanban” card. In this type of system, a station is only autho- rized for processing if a kanban for that part is available. When processing is complete, the kanban moves with the part to the next station. As the next station consumes parts, it returns the kanbans to the previous station to authorize additional processing.
Processing 199
Kanban system
Discrete Event

   223   224   225   226   227