MIME 4100 Exam 1: Prospectus Spring 2007

MIME 4100 Final Exam 5/2/2010 Due Thursday, May 6, 2010 by 5 PM. Please put your solution in a large envelop with your name on it and bring it to my office (NI 4035) in person between 3:00 PM to 5:00 PM on Thursday, 5/6/2010 or email it to me by that time. No solutions will be accepted after 5:00 PM.

This is a take-home exam. Open book, no time limit. Please sign the honor pledge: I have not given or received any help in this exam. Name ______, Signature ______

For the two problems below submit hardcopies of the following: a) A write-up explaining the logic for developing your model and the steps that you followed to develop this model. b) A printout showing your Arena model. c) The report from Arena. Export the report in a PDF or word file and print it. d) An explanation of what you did to check if the model is correct. How did you check that the results of the simulation are correct? e) A write-up explaining your observations are conclusions. This should include the steps that you did to verify the model.

1. (50 pts) Unprocessed parts arrive at a manufacturing machine for processing. The interarrival time is exponentially distributed with mean value 0.5 minutes. The parts wait for processing on a fist-in-first-out basis. The processing time per part is exponentially distributed with mean processing time of 0.25 minutes. After a part has been processed it is accepted or rejected. The acceptance probability is 0.8. If a part is rejected it is placed but in the queue of unprocessed parts, after a delay of 10 seconds.

It costs $2.5 to process a part once; if a part is rejected then it costs an additional $2.5 to process it again. The revenue per part that is disposed of the system is $5.

Construct an ARENA model to this process.

Run your model for the following termination conditions. Stop accepting parts after 10 hours. Terminate the simulation after all of the parts have been processed. Study the Arena report, and determine the following: a) The number of parts that entered and exited the system, b) the total cost, c) the total revenue and the total profit. Summarize the observations and conclusions of the study.

2. (50 pts) Study the example of the electronic assembly and test system in chapter 4, section 4.1 of the textbook.

A manager proposes eliminating the rework area and scraping all of the parts that fail inspection. She asks you to evaluate this proposal. In order to decide if this proposal will increase profit you find the cost of processing each part and the revenue from selling it to a client, which are shown in the table below: Process Cost per part (either A or B) Unprocessed part $10.00 Preparation $0.50 Sealing $0.60 Rework $2.00* Revenue per part (either A or B) Revenue $25

*Not applicable to modified configuration

The revenue and cost of each step does not depend on the part type. Also the revenue is the same for both salvaged and shipped parts.

Modify the model to evaluate the manager’s proposal. Run the original model in section 4.1 and the modified model according to the manager’s proposal by using the following termination condition: stop accepting parts after 1920 minutes and stop the simulation after all parts have been flushed out of the system. Calculate and compare the profits of the original configuration and the modified one per minute of operation in order to decide if the manager’s idea will increase the company’s profit.