Chaaben Kouki

Analysis of a periodic review inventory control system with perishables having random lifetime

We consider an order up to level policy for perishable items with random lifetime. We investigate two cases: the first one is the case where excess demand is completely lost and the second one deals with full backorders. Demands arrive according to a Poisson process. The lifetime of each item is assumed to be exponentially distributed and the procurement lead time is constant. We also assume that there is at most one outstanding order at any time. We model this inventory system as a Markov process in which stationary regime can be characterised. This model allows us to get insights on the impact of the model parameters on the overall system performance in terms of costs.

Comparison between continuous review inventory control systems for perishables with deterministic lifetime and lead time

This paper aims at comparing and verifying the effectiveness of existing (r, Q) inventory systems for perishables with fixed lead time and lifetime. The total inventory operating costs are compared to measure the performance for each policy in order to choose the best one that leads to the lowest cost. We show that, under backordered demand, the (r, Q) policy obtained from [8] deviates on average by less than one percent from the optimal (r, Q) policy and performs better than a previous model developed by Chiu [2] when Q ≥ r. When excess demand are lost, Chius model [2] performs better than the model of [8]. But both models are unsuitable when the ordering cost K increases. Keywords: Perishable products, Inventory control, Continuous review policy.

Consideration of the Undershoot in an (r,Q) Inventory Model for Perishables

Abstract In this paper, we consider a perishable inventory control model under an ( r,Q ) review policy, i.e. at every unit time, the inventory position is monitored and a replenishment of size Q is made if the inventory position hits r. The lifetime of products and the lead time are an integral number of the unit time. We derive approximate expressions of the key operating characteristics of the inventory system (such as the expected quantity of perished products, the expected shortage and the expected inventory level) and obtain a closed form expression of the average total cost per unit time. The effectiveness of approximations is tested by a simulation experiment implemented in Arena software. A numerical analysis is developed to illustrate the advantages of using the proposed policy compared to the classical ( r,Q ) policy which ignores the perishability of products.