Modified Periodic Replacement with Minimal Repair at Failure

This paper summarizes four models of modified periodic replacement with minimal repair at failures when the scheduled replacement time is specified. If a failure occurs just before the replacement time, then three models are: A) a unit remains as it is until the replacement time comes, B) a unit is replaced by one of spares, C) a unit is replaced by a new unit. If a failure occurs well before replacement time then model D is: a unit is replaced at failure or at time T1. The s-expected costs for each model are obtained and the optimum policies are discussed.