Rescheduling of unrelated parallel machines under machine breakdowns

In this paper, new repair and rescheduling algorithms are developed for the unrelated parallel machine environment. The introduced rules and algorithms are used to handle different rates of breakdowns and delays and are evaluated based on several performance measures to ensure the optimisation of both the schedule quality and stability. Schedule quality is assessed based on the schedule makespan (time to finish all jobs), and schedule stability is based on the number of shifted jobs from one machine to another and the time to match up with the original schedule after the occurrence of a breakdown. The extensive computational tests and analyses show the superiority of the proposed algorithms compared to existing methods in the literature. Moreover, the rules are ranked based on their accomplishment for different performance measure combinations, allowing the decision maker to easily determine the most appropriate repair/rescheduling rule depending on the performance measure(s) desired.