Optimal geometric process replacement model

In this paper, we study the geometric process replacement model as follows: the successive survival times of the system form a nonincreasing geometric process while the consecutive repair times of the system constitute a non-decreasing geometric process, and the system is replaced at the time of theNth failure after its installation or last replacement. Based on the long-run average cost per unit time, we determine the optimal replacement policyN* show the uniquess of the policyN* and discuss its monotonicity.