TRANSIENT ANALYSIS OF MANUFACTURING SYSTEMS PERFORMANCE

Studies in performance evaluation of automated manufacturing systems, using simulation or analytical models, have always emphasized steady-s tate or equilibrium performance in preference to transient performance . In this study, we present several situations in manufacturing system s where transient analysis is very important. Manufacturing systems an d models in which such situations arise include: systems with failure states and deadlocks, unstable queueing systems, and systems with fluc tuating or non-stationary workloads. Even in systems where equilibrium exists, transient analysis is important in studying issues such as ac cumulated performance rewards over finite intervals, first passage tim es, sensitivity analysis, settling time computation, and deriving the behavior of queueing models as they approach equilibrium. In certain s ystems, convergence to steady-state is so slow that only transient ana lysis can throw light on the system performance. In this paper, we foc us on transient analysis of Markovian models of manufacturing systems. After presenting several illustrative manufacturing situations where transient analysis has significance, we discuss two problems for demon strating the importance of transient analysis. The first problem is co ncerned with the computation of distribution of time to absorption in Markov models of manufacturing systems with deadlocks or failures, and the second problem shows the relevance of transient analysis to a mul ticlass manufacturing system with significant setup times. We also bri efly discuss computational aspects of transient analysis.