14.2: Points Made in the Case Study

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Arrivals represent daily shipping demand. There is one arrival per day at the beginning of the day. The number of shipments per day is modeled as a random variable.

Trucks used in shipping are modeled with a single resource. Each unit of the resource represents a truck. The number of trucks (resource units) required can be determined dynamically in the model during execution. An additional truck (resource unit) is created whenever needed to make a shipment, subject to an upper limit. Thus, the number of trucks needed to meet a performance level can be determined.

A sequence of experiments can be used to determine the relationship between the maximum number of trucks (resource units) available and system performance. The values of the number of trucks depend on the results of previous simulation experiments. After the number of trucks is established, the number of workers is set in the same way.

Simulation experiments can be run to determine the affect of structural variability on system performance. Various staff schedules with regard to shifts worked per day and days worked per week can be tested to determine their relationship to system performance and to estimate the number of workers required. This is left as an exercise for the reader.