Solving Fuzzy Job Shop Scheduling Problems with Availability Constraints Using a Scatter Search Method
Orhan Engin, M. Kerim Yılmaz, M. Emin Baysal and Ahmet Sarucan
In the last decade job shop scheduling problems have been subject to intensive research due to their multiple applications. Job shop scheduling is known as a strongly NP-complete problem. In the job shop scheduling problems, processing times and due dates are very dynamic due to both human and machine resource factors. Fuzzy sets have been used to model the uncertain processing times and due dates in recent years. In this study, a fuzzy job shop scheduling problem with availability constraints is considered. Availability constraints mean that machines can be unavailable for preventive maintenance, periodic repair or random breakdown. These constraints have been considered in this study for fuzzy job shop scheduling problems. A Scatter Search (SS) method is proposed to solve these problems. The feasibility and effectiveness of the proposed scatter search method is demonstrated by comparing it with the hybrid genetic algorithm (HGA). The aim of the study is to minimize the tardiness and earliness.
Keywords: Fuzzy job shop scheduling problems, availability constraints, scatter search method, hybrid genetic algorithm