Browsing by Subject "Inventory control Mathematical models."

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Open Access
An inventory model with two suppliers under yield uncertainity
(2001) Gürbüz, Mustafa Çağrı
In this study, an inventory model with one retailer and two suppliers is considered for a single item. Di erent from most of the models in inventory literature, we do not make the assumption that we receive all the quantity that we ordered. It is assumed that a random fraction of the lot size is actually delivered by the suppliers. Hence, the model is constructed under yield uncertainty for both binomial yield and stochastically proportional yield model. The demand rate is constant, and backordering is allowed. The ob jective is to minimize the long-run average cost and nd the near optimal values for the decision variables; order quantities and reorder point. Furthermore, the regions where diversi cation among suppliers is bene cial are investigated. The results are generalized to \M" suppliers (M>2) and solution method is proposed. Finally, experimental study is carried out for the two-suppliers problem.
Open Access
Multi-period inventory models with price protection
(2007) Ahat, Nurdan
In an environment with declining sales prices, retailers (or any reseller) often face the risk of buying high and selling low. In order to limit their channel partners’ exposure to such risks and increase the availability of their products in the marketplace, suppliers often offer price protection. With price protection, a retailer is reimbursed with a percentage of the procurement cost declines, for the inventory that the retailer ordered within a given price protection age limit. We study the optimal inventory policy of the retailer under such price protection terms in a multi–period finite horizon setting with stochastic demand. We propose three different models for the treatment of unsatisfied demand. For the case of full backlogging, we show that the order–up–to type policies are optimal. In a numerical study, we study the behavior of the retailer and investigate the impact of price protection terms on the operational performance of the retailer and the supplier under a variety of settings.
Open Access
On stock rationing policies for continuous review inventory systems
(2005) Bulut, Önder
Rationing is an inventory policy that allows prioritization of different demand classes. In this thesis, we analyze the stock rationing policies for continuous review systems. We clarify some of the ambiguities present in the current literature. Then, we propose a new method for the exact analysis of lot-for-lot inventory systems with backorders under rationing policy. We show that if such an inventory system is sampled at multiples of supply leadtime, the state of the system evolves according to a Markov chain. We provide a recursive procedure to generate the transition probabilities of the embedded Markov chain. It is possible to obtain the steady-state probabilities of interest with desired accuracy by considering a truncated version of the chain. Finally, we propose a dynamic rationing policy, which makes use of the information on the status of the outstanding replenishment orders. We conduct a simulation study to evaluate the performance of the proposed policy.