MATLAB SIMEVENTS RELEASE NOTES Betriebsanweisung PDF herunterladen (Seite 89)

Model Basic Queueing Systems

4-11

• You want the service time to arise from dynamics of the simulation. In this case, set

the Single Server block's Service time from parameter to Signal port t and

create a signal whose value at the time an entity arrives at the server is equal to the

desired service time for that entity.

If the signal representing the service time is an event-based signal such as the output

of a Get Attribute block, ensure that the signal's updates occur before the entity

arrives at the server. For common problems and troubleshooting tips, see “Unexpected

Use of Old Value of Signal” online.

Random Service Times in a Queuing System

Open the model that you created in “Build a Discrete-Event Model” on page 2-2, or enter

simeventsdocex('doc_dd1') in the MATLAB Command Window to open a prebuilt version

of the same model. By examining the Single Server block's Service time from and

Service time parameters, you can see that the block is configured to use a constant

service time of 1 second. To use a random service time instead, follow these steps:

Set Service time from to Signal port t. This causes the block to have a signal

input port labeled t.

From the Signal Generators sublibrary of the Generators library, drag the Event-

Based Random Number block into the model window and connect it to the Single

Server block's signal input port labeled t.

Run the simulation and note how the plot differs from the one corresponding to

constant service times (shown in “Results of the Simulation” on page 2-14).

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MATLAB SIMEVENTS RELEASE NOTES Betriebsanweisung Seite 89