Setup times with a learning effect in flowshop scheduling problem

Abstract

Relevant to recent scheduling studies, setup times of jobs have generally been either neglected or considered in processing times. But, in some production systems the setup times may be so large that it can not be neglected but should be considered separately from processing times. In production systems, since jobs are generally processed on automated machines, job processing times are independent of the sequence of jobs. When the setup times are taken into account, there will be a gradual decline in their magnitudes due to the repetition of setup procedures by human operators. This phenomenon is known as the learning effect in scheduling analysis. In this study, a two-machine flow-shop scheduling problem with learning effect setup times is considered. A mathematical programming model is developed for the problem and according to different setup time ranges and learning effects, computational results are compared. Additionally, heuristic approaches are presented and experimental results are given for large size problems.