Cho, Yooney
M.S |
Mathematical model and solution approaches for multi-stage hybrid flow shop scheduling with reworks under general queue time limits This study addresses multi-stage hybrid flow shop scheduling in which a rework of a job is incurred if the queue time of the job between two arbitary stages exceeds a pre-specified upper limit. The problem is to determine the allocation of jobs to machines at stage, the start times of the jobs assigned to each machine and the start times of rework setups if incurred, A mixed integer programming model is developed for each of the two objectives of minimizing makespan and total tardiness and the NP-hardness of each problem is briefly shown. Then, to obtain fast solutions for practical applications, a scheduling mechanism is proposed for each two steps: filtering the jobs to be delayed; and dispatching non-delayed and delayed jobs sequentially using a priority rule, Also, for the tardiness measure, the mechanism is a modified one in which the filtering step is done by selecting rework jobs after estimating the tardiness, To test the performance of the mechanisms proposed in this study, simulation experiments were done on various test instances and the results are reported by comparing priority rules without and with the mechanims and identifying the best priority rules. |
