Energy–Saving Oriented Maintenance and Inventory Policy for a Two–Unit Buffered Serial System

This paper investigates the joint optimization of maintenance and inventory policy for a two–unit buffered serial system. The system comprises a production unit, an assembly unit, and an intermediate buffer. When the production unit deteriorates to the preventive maintenance (PM) threshold, the unit is restored to a state as good as new by PM. When the production unit degrades to the corrective maintenance (CM) threshold, the unit is replaced by CM. As for the assembly unit, when it fails, it is replaced by CM. Unlike previous studies, where intermediate buffer inventory strategies and upstream and downstream components were studied separately, in this paper the size of the buffer inventory interacts with the operating speeds of both components. Moreover, we use a semi–Markov decision process to obtain the transition probability, expected sojourn time and expected cost of the system. The optimal PM, CM, and intermediate buffer thresholds are derived by minimizing the long–run average cost of the system. Finally, the effectiveness of the proposed policy is verified by comparing the models.