Page 136 - ExtendSim User Guide
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A basic discrete event model
Category:Name (Label)
Activities:Activity (Wash Bay)
Routing:Exit (Exit)
Plotter, Discrete Event
Block Function
Processes one or more items simulta- neously. Processing time is a con- stant or is based on a distribution or an item’s attribute.
Removes items from the simulation and counts them as they leave.
Purpose in Car Wash Model
Washes the cars for a simulated 6 minutes.
Removes the cars from the model.
Reports the length of the waiting line and how many cars have been washed.
☞ Place blocks on the model worksheet using one of the methods discussed in “Adding blocks to the model” on page 26. Or, place the Executive and Create blocks on the model worksheet and use the “Smart Blocks” technique to add the remaining blocks. To do this, right click the item output of the Create block and select the Queue. Then right-click the item output of the Queue and choose an Activity, and so forth. You can also use this technique to add and connect a Plot- ter Discrete Event to the L (length) output of the Queue.
Smart Blocks is only available in discrete event and discrete rate models and the Executive must be on the model worksheet for it to be enabled.
Starting at the right of the Executive block, place the blocks on the model worksheet in a line from left to right, based on their order in the table. The model should look like the one shown on page 109.
Label the blocks as indicated in the table. Entering dialog parameters and settings
There are only a few values to enter to reflect the basic car wash assumptions.
In the Create block’s dialog, the default setting is that items are created randomly using an exponential distribution. Since this is exactly what you want, just enter Mean: 4. With this setting, one car will arrive approximately every 4 minutes.
By default, the Queue block is specified as a sorted queue, with items stored and released in first-in, first-out order. Since this is what the model specifies, do not make any changes to the Queue.
The assumptions indicate that cars are washed one at a time and that it takes the same amount of time to wash each car. In the Activity block’s dialog, the default settings are that the capacity is 1 and the delay is a constant amount of time. Since those settings are what you want, just enter Delay (D): 6, indicating that it takes 6 minutes to wash each car.
The Exit block automatically counts and passes items out of the simulation and the Plotter will graph results as the simulation runs. There are no settings to enter for those two blocks.
Discrete Event

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