A Memetic Algorithm for Hybrid Flowshops with Flexible Machine Availability Constraints

This paper considers the problem of scheduling hybrid flowshops with machine availability constraints (MAC) to minimize makespan. Thepaper deals with a specific case of MAC caused by preventive maintenance (PM) operations. Contrary to previous papers considering fixedor/and conservative policies, we explore a case in which PM activities might be postponed or expedited while necessary. Regarding thisflexibility in PM activities, we expect to obtain more efficient schedule. A simple technique is employed to schedule production jobs alongwith the flexible MACs caused by PM. To solve the problem, we present a high performing metaheuristic based on memetic algorithmincorporating some advanced features. To evaluate the proposed algorithm, the paper compares the proposed algorithm with several wellknownalgorithms taken from the literature. Finally, we conclude that the proposed algorithm outperforms other algorithms.

Keywords:

Scheduling , Hybrid flowshops , sequence dependent setup times , machine availibility constraints , memetic algorithm