Scheduling identical parallel machine with unequal job release time to minimise total flow time

Abstract

This paper addresses the identical parallel machine scheduling problem with unequal jobs release date to minimise the total flow time. An efficient heuristic algorithm was proposed, known as modified forward heuristic algorithm. The algorithm starts with developing a priority list of all jobs. This list is used to develop sub-schedules for each machine based on some propositions related to the jobs processing and release times with allowing delay schedule. A mathematical model of the problem was also developed. The performance of the algorithm was evaluated by comparing its solutions with the optimal solutions of small test cases obtained from the developed mathematical model. Then, the results of large problems were compared with the results of the best reported heuristics in the literature. In addition to the simplicity of the proposed algorithm, these comparisons showed that the proposed algorithm can obtain solutions that are very close to the optimum solutions and better than the other heuristics.