Browsing by Subject "Inventory Theory"

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    Joint replenishment problem in two echelon inventory systems with transportation capacity
    (2006) Büyükkaramıklı, Nasuh Çağdaş
    In this study, we examine the stochastic joint replenishment problem in the presence of a transportation capacity. We first study the multi-retailer and singleechelon setting under a quantity based joint replenishment policy. A limited fleet of capacitated trucks is used for the transportation of the orders from the ample supplier in our setting. We model the shipment operations of the trucks as a queueing system, where the customers are the orders and trucks are the servers. Consequently, different transportation limitation scenarios and methods of approach for these scenarios are discussed. We then extend our model to a two-echelon inventory system, where the warehouse also holds inventory. We characterize the departure process of the warehouse inventory system, which becomes the arrival process of the queueing system that models the shipment operations between the warehouse and the retailers. This arrival process is then approximated to an Erlang Process. Several numerical studies are conducted in order to assess the sensitivity of the total cost rate to system and cost parameters as well as the performance of the approximation.
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    Replenishment decisions under quantity discounts and expiry dates
    (2006) Ergene, Erim
    In this study, we model a single buyer-single seller system under a quantity discount schedule with expiry dates. The buyer faces constant demand and shortages are not allowed. The seller o§ers a quantity discount which is e§ective on the buyerís next purchase to be exercised by a certain expiry date given that the current purchase exceeds a minimum quantity. We derive the optimal replenishment policy structure for the buyer which minimizes his/her total cost rate. We obtain the expressions for the operating characteristics of the buyer and investigate the structural properties of the objective function. Under a speciÖc inventory holding cost structure, we also investigate the impact of the buyerís decisions on the entire buyer-seller inventory system. We conduct an extensive numerical study. Our Öndings show that quantity discount schedules with expiry dates may be beneÖcial for both the buyer and the seller in a variety of operating cost settings.