Perishable Queuing Inventory Systems with Delayed Feedback

The three-dimensional Perishable Queuing-Inventory System (PQIS) models with positive service time and delayed feedback are studied in this paper. We assume that the customers either leave the system with/without purchasing an item or join the orbit for the decision making. We apply the (s, S) replenishment policy with the positive order lead time. The approximate formulas are developed to calculate the joint distributions and performance measures of the system. The high accuracy of the approximate formulas is confirmed by the numerical experiments.