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Simulation Modelling CB667
University of Kent
Computing Exercise #1 – Simple Queuing Models

1. Building a simple single-server queue in SIMUL8

Build a simple single-server queue like the one below.
Here, customers enter the system, wait to be process by a single work centre and then leave the system. Set the time between arrivals to be 5 minutes and set the service time to be 6 minutes. In both cases, use an “exponential” distribution. Run the simulation and look at the time chart of the number of items in the queue. What’s happening to the queue? Why?

Now set the service time to be 4 minutes and rerun your simulation. Determine: a) the average number of people waiting in line and b) the average % of time the work centre is busy. According to queuing theory, the average number of people waiting in line should be 3.2 and the work centre should be busy 80% of the time. Do your results agree? Why might they be different?

2. Building multi-server queues in SIMUL8

Now you will build several multi-server queues in SIMUL8 and compare their operating performances.

Indigo Montoya is the manager at a small, local bank. He has run his bank the same way for many years but recently has been thinking about trying to make some improvements in customer service. Based on extensive data, Mr. Montoya informs you that customers arrive exponentially at a rate of 50 per hour and take an average of 2.3 minutes to be serviced by each of his two full-time tellers

Under current policy, customers arrive at the bank and then enter one of two separate queues each serviced by a single teller. Assuming that each successive customer enters a different queue compared to the previous customer and there is no jockeying between lines, create a model of this system in SIMUL8. Determine the average waiting time of customers in the queues and the average number of customers in queue.

One change that Mr. Montoya is pondering is allowing customers to enter the...