TRANSIENT ANALYSIS OF MULTICLASS MANUFACTURING SYSTEMS WITH PRIORITY SCHEDULING

In this article we examine the transient performance of a flexible mac hine centre that processes several classes of jobs with significant se tup times and with priority scheduling. Our results show that the tran sient performance of the system over typical observation intervals can be significantly different from the performance predicted by steady-s tate analysis. The machine centre serves three classes of jobs-class 1 , class 2 and class 3; class 3 jobs have non-preemptive priority over jobs of class 1 and class 2. The results show that the throughput and cycle time of class 1 and class 2 jobs are affected quite dramatically by the arrival of class 3 jobs. However, over a typical observation p eriod in the initial evolution of the system, steady-state results ove restimate this effect of the high priority jobs whereas the more credi ble estimates are given by transient analysis. The transient analysis is carried out by solving explicitly the corresponding Markov chains, using a higher level stochastic Petri net model to generate the Markov chains. (C) 1997 Elsevier Science Ltd. All rights reserved.