Generic simulation model for hybrid flow-shop

In this paper, we propose a generic simulation model for Hybrid Flow-Shop (HFS) where the job priorities at each machine stage are established dynamically. Based on an object-oriented conceptual model of the HFS system class, an initial dynamic simulation prototype was developed using the Simula language and the external class GPSSS (GPSS under Simula). In order to help the industrial managers an HFS dedicated simulator in Delphi 2 under Windows 95 operating system has been realized. The main goal of the simulator is to facilitate the performance evaluation of different priority rules for job dispatching concerning the mean flow time and makespan as well as other performance criteria like average resource utilization, average queue length . . . A simulation experiment was made to investigate the performance of four priority rules. The performed tests concern 13 systems. The results of 52 simulation runs demonstrate that the shortest processing time dispatching rule yielded superior performance for the makespan criteria for most of the tests. However, it has also been found that for some tests clear superiority of a particular priority rule has not been established. Thus the HFS simulator proposed can help managers to schedule hybrid flow shops efficiently to achieve various corporate objectives.