Endüstri Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/279
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Article Citation - WoS: 20Citation - Scopus: 22Shipment Consolidation With Two Demand Classes: Rationing the Dispatch Capacity(Elsevier Science Bv, 2018) Erenay, Fatih Safa; Bookbinder, James H.; Satir, BenhurWe analyze the problem faced by a logistics provider that dispatches shipment orders (parcels or larger packages) of two order classes, viz. expedited and regular. Shipment orders arrive according to a compound Poisson process for each class. Upon an arrival, the logistics provider may continue consolidating arriving orders by paying a holding cost. Alternatively, the provider may dispatch, at a fixed cost, a vehicle containing (a portion of) the load consolidated so far. In addition, the provider must specify the composition of each dispatch by allocating (rationing) the volume of the vehicle between expedited and regular shipment orders. We model this problem as a continuous-time Markov Decision Process and minimize the expected discounted total cost. We prove the existence of quantity-based optimal threshold policies under particular conditions. We also structurally analyze the thresholds of these optimal policies. Based on these structural properties, we develop an efficient solution approach for large problem instances which are difficult to solve using the conventional policy-iteration method. For two real-life applications, we show that the quantity-based threshold policies derived using the proposed approach outperform the time policies used in practice. (C) 2018 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 12Pooling Through Lateral Transshipments in Service Parts Systems(Elsevier Science Bv, 2012) Savasaneril, Secil; Serin, Yasemin; Satir, BenhurWe study the inventory management problem of a service center operating in a decentralized service parts network. The service centers collaborate through inventory and service pooling, and through sharing information on the inventory status. Upon demand arrival, a service center may request a part from the other center, in which case a payment is made. Under this competitive and collaborative environment, we first characterize the optimal operating policy of an individual service center. Through computational analysis we identify the conditions under which pooling is most beneficial to the service center, and make an assessment of different pooling strategies which are commonly adopted in practice and in the literature. Finally, we analyze the effect of interaction between the centers on the benefit of pooling. (C) 2012 Elsevier B.V. All rights reserved.