CSci 405-01: Computer Simulation
CSci 581-01: Special Topics on Computer Simulation
Fall Semester 2001

Assignment #1
Due Wednesday, 10 October (Revised)

For All Students

Prepare this assignment by the above deadline in accordance with the instructions given in the Professional Conduct and Assignments sections of the Syllabus.

In this assignment you are asked to develop a simulation model and program using Java and the Psim-J simulation package. The Psim-J package is available from the course Web pages and will be installed on some of the Department's systems soon.

Develop a simulation model for the Bursar's office, assuming it has the following characteristics:

• There is a single waiting line that holds at most numWaiting customers.
• There are numTellers tellers to serve customers from the waiting line.
• Tellers may serve at most one customer at a time. Assume all tellers are identical in how fast they carry out customer service requests.
• Customers are served by tellers in a first-come, first-served manner.
• During periods when there are no customers to serve, a teller becomes idle.
• Customers arrive separately with interarrival times that can be modeled using an exponential distribution with a mean of arrivalMean minutes.
• Serving customers take service times that can be modeled using an exponential distribution with a mean of serviceMean minutes.
• Customers that arrive when the waiting line is full are rejected and go away without being served.
• The system starts with the waiting line empty and all tellers idle at time zero and runs until its closing time, which is servicePeriod minutes later.
• After closing time, no new customers are accepted into the waiting line, but all customers waiting will be serviced.

The values numWaiting, numTellers, arrivalMean, serviceMean, and servicePeriod are parameters of the model. In your program, it shuld be easy to vary the parameter values. (I'd probably supply them as command line parameters and run the program from a Unix script-- or maybe read the parameters from a file.)

You need to collect information for several performance measures of the system and display them at the end of each run.

• The total number of customer arrivals.
• The total number of customer rejections.
• The total number of customers served.
• The average waiting time for customers.
• The average sojourn time for customers.
• The maximum and average lengths of the waiting lines.
• The teller utilization.

Suppose the arrMean = 1 minute, serviceMean = 2 minutes, numWaiting = 5, and servicePeriod = 60 minutes. Run the model for numTellers = 1, 2, 3, 4, and 5 (or to larger values if needed to answer the question below)

What is the minimum number of tellers needed to make sure all customers are serviced?

When this assignment is complete, submit:

• a description of your model in text and drawings,
• a paper listing of your program source code and outputs from your experiments,
• a diskette containing your program source code and instructions on how to run your model.

Be sure that all items submitted are clearly labeled with your name, class, and the assignment number.

Additional Work for Graduate Students

Assume that:

• Providing a teller costs tellerCost cents per minute.
• Each customer pays a fee ofserviceFee cents for each service if served within serviceWindow minutes.
• A customer that is not completely served within serviceWindow minutes of arrival gets a discount of serviceDiscount cents off the service fee.
• The Bursar must buy each rejected customer a Coke. (Suppose the Coke costs the Bursar cokeCost cents).

Instrument your model to determine revenue generated (positive or negative) for the period of operation. Use the following values for the new parameters: tellerCost = 20, serviceFee = 100, serviceWindow = 6, serviceDiscount = 50, and cokeCost = 50.

To generate the most revenue, how many tellers would you suggest be hired?

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