Conceptual Information Model ^?

The potentially relevant object types are:

1. parts,
2. workstations,
3. input buffers,
4. workers.

Potentially relevant types of events are:

1. part arrivals,
2. processing starts,
3. processing ends,
4. part departures.

Notice that a pair of start and end events, like "processing start" and "processing end", indicates that there is an activity that is temporally framed by these two events. It's an option to consider also activities, in addition to objects and events, in a conceptual model. We will do this in our 2nd model of single workstation systems.

Both object types and event types, together with their participation associations, can be visually described in a UML class diagram, as shown below.

Conceptual Process Model ^?

The involved types of events can be related with each other via their (possibly conditional) temporal succession, as visualized in the following process diagram:

Information Design Model ^?

The purpose of the simulation model is to compute two statistics: the workstation utilization and the average length and maximum length of the input buffer. We may therefore abstract away from several of the object types described in the conceptual information model. In particular, there is no need to consider individual parts and (the composition of) the input buffer. It's sufficient to represent the input buffer in terms of its length. Also, part departure events are merged with processing end events.

For controlling the competition between arrival and processing end events for allocating the workstation, a workstation status attribute, with the two possible values BUSY and AVAILABLE is introduced.

The resulting object types and event types, together with their participation associations, are visually described in the following UML class diagram:

Notice how functions representing random variables, like processingDuration() and recurrence(), are marked with the keyword (or UML stereotype) «rv» standing for "random variable".

Process Design Model ^?

Other OES Models for the Same System/Problem/Domain