OPTIMAL ORDERING POLICIES WITH 2 TYPES OF RANDOMIZED LEAD TIMES

In this paper, we discuss the generalized ordering policy, in which when an ordered spare is delivered after a randomized lead time it is put into the inventory if an original unit is still operating and the original one is replaced/exchanged by the stocked spare when the original one fails/passes a prespecified time, whichever occurs first. We apply the expected total discounted cost as a criterion of optimality and obtain the optimal ordering policies minimizing this expected cost, taking into account several costs, an exponential-type discount rate and two types of randomized lead times. Finally, we present the relationships between the results of this paper and earlier contributions. © 1990.