A COMPUTER SIMULATION MODEL

FOR ANALYSING A PRODUCTION SYSTEM

Prof. Moataz H.Khorshid, Prof Said Ali HasSan),

Dr. Mohammed A. Ewees3), and Amr Abo-Sereai Mahfouz4)

Abstract A simulation model is a simplified representation of reality. The function of

such a model is to study the behavior of the alternative operating rules and policies to

select the most appropriate among them.

Simulation technique is one of the well-known methods to solve problems in the

real life world. It is the process of developing a model of a problem and estimating

measures of performance, then performing simulation experiments on the model with

different values for the decision variables in order to determine their best values. This

paper is intended to use the power of the simulation technique in designing the best

operating parameters for a real manufacturing system (Giza Telephone Cable

Company). The model represents a full analysis for the company, the machines, the

company products, the manufacturing system, and the scheduling rules.

The computer simulation model is directed to measure the effect of changing the

set of scheduling rules on the company throughput performance. The company

represents a job shop that contains a number of groups of similar machines that

receive a number of different order batches where each batch may have different

processing routes. The paper represents in details the objective, the assumptions, the

logic of the model, the inputs / outputs, the list of discrete events used for the model,

and the event flow charts. The simulation model for the system is built using the

SIMPROCESS 3.1 simulation package. Three used scheduling policies are selected:

first come first service (FCFS), shortest processing time (SPT), and the earliest due-

date (EDD).

0-7803-8482-21041$20.00 02004 IEEE. 133

Three factors were taken into consideration: machine efficiency, machine

operation type, and preventive maintenance interval. Factorial experiments are used

to design the simulation and the statistical results of each scheduling policy are

analyzed using the analysis of variance (ANOVA) method and the SPSS 9.5 package.

The main performance measure for evaluating the system is the average flow time.'

The paper represents the significant effects for various input factor levels at each

scheduling rule. The conclusion show the most significant input factors, which have

magnified effect on the response average flow time.

I ) Vice President of Cairo University for Postgraduate and Research Affairs.

2, Head of Operations Research and Decision Support Department, Faculty of

Computers and Information, Cairo university.

3, Military Technical College,

4, Assistant Lecturer, Institute of statistical Studies and Researches, Cairo University.

0-7803-8482-21041$20.00 02004 IEEE. 134