1、PDF外文：http:/ J.Production Economics 114 (2008) 119133Inventory/distribution control system in a one-warehouse/ multi-retailer supply chain Chumpol Monthatipkula,1, Pisal Yenradeeb,* Abstract This paper proposes a new inventory control system called the inventory/distribution plan(IDP)control system
2、for a one-warehouse/multi-retailer supply chain.In the system,a proposed mixed-integer linear programming model is solved to determine an optimal IDP control system,a proposed mixed-integer linear programming model is solved to determine an optimal IDP that controls the inventories of the supp
3、ly chain.The efficiency of the IDP control system is compared to that of the echelon-stock R,s,S control policy,where R is a periodic review interval,s is a reorder point,and S is an order-up-to level,at various fillrates.The experimental results show that when the system faces non-stationary demand
4、s,the IDP control system significantly outperforms the echelon-stock R,s,S control system because it can give lower total costs for all ranges of fill rates. Keywords:Inventory/distribution plan； One-warehouse/multiple retailers； Supply chain； Mixed-integer linear programming 1.Introduction I
5、n Supply Chain Management(SCM),the inventory control problem is very complicated and challenging because the planner needs to consider several factors,for example,supply chain structures,coordination levels,and information sharing processes.The inventory control policy used by each entity is also an
6、 important factor because it affects the inventory replenishment process of the upstream entity.The upstream demand may be distorted and far from the actual demand faced by the downstream entity.This phenomenon is known as the Bullwhip Effect,which is presented in Forrester(1961).Many classical inve
7、ntory control systems(s,Q,s,S,R,S,R,Q,and R,s,S,etc.where s,Q,S,and R denote reorder points,reorder quantities,order-up-to levels,and periodic review periods,respectively)are still used in the supply chain environment.However,determination of their control parameters is very difficult.For SCM,all en
8、tities in the supply chain should be planned and controlled simultaneously to obtain goodcontrol parameters and low inventory costs.The aim of this paper is to develop a new inventory control system called the inventory/distribution plan(IDP)control system that determines optimal product flow throug
9、h a one-warehouse/multi-retailer supply chain under both stationary and non-stationary uncertain demand situations.The IDP control system controls each supply chain member using the optimal IDP operating under a one-period rolling horizon planning strategy.The optimal IDP is obtained by solving a pr
10、oposed mixed-integer linear programming model.The performance of the proposed IDP control system is compared with that of the echelon-stock R,s,S control policy since both systems are similar in manyaspects.The main contribution of this paper is the development of IDP control system thathas good per
11、formances under both stationary and nonstationary uncertain demand situations.This paper also proposes a practical way to determine appropriate safety stock factors at the warehouse and retailers that yield relatively low total costs while maintaining relativelyhigh fill rates. 1.1.Literature review
12、 This paper involves two main streams of research:(a)proposing new inventory control systems and(b)determining suitable control parameters of classicalinventory control systems.Therefore,the literature review is presented in two main subsections.(a)Literature review proposing inventory control syste
13、ms:So far,many researches including this paper have focused on proposing new inventory control systems or improving classical inventory control systems,and also comparing their proposed/improved systems to a classical inventory control system.Yoo et al.(1997) proposed an improved Distribution Resour
14、ce Planning(DRP)method using concepts of installation-stock s,Q and R,S systems.The order quantities and order points are dynamically determined to meet the demand in a just-in-time concept and minimize the out-of-stock probability.In the improved system,regional distribution centers can make a deci
15、sion to reduce the related costs order only the amount available or postpone the ordering. Based on experiments,the proposed system out performs he classical DRP.Another relevant research work belongs to De Kok andFransoo(2003).The authors proposed the so-called Synchronized Based Stock(SBS)policy a
16、nd compared its performance to the LP-based system under the backlogging model.The SBS, which uses the base-stock-policy concept,raises the inventory position to meet the adjustable target level in every inventory review.It is concluded that the SBS outperforms the LP-based system considerably becau
17、se it uses more sophisticated ordering method and rationing rule.Ganeshan et al.(2001)studied two inventory control systems,namely,DRP and Reorder Point systems in a four-echelon network.TheDRP system refers to a calculation of upstream reorder quantities and reorder intervals by aggregating all dow
18、nstream demands and offsetting them by related lead times.The Reorder Point system refers to a situation that manufacturers forecast needs at the distribution centers.The authors concluded that the DRP system gives higher service levels and lower cycle times.A s,S system where s and S vary with stat
19、es(SMART s,S system)was proposed by Giannoccaro and Pontrandolfo(2002).A three-stage serial supply chain is formulated as a semi-Markov decision process model and then solved by SMART(semi-Markov average reward technique)algorithm.The authors compared the SMART s,S system to the echelon-stock R,Ssys
20、tem and then summarized that the SMART s,S system gives lower total costs and is more robust if demand undergoes only slight changes.Wang et al.(2004)proposed just-in-timedistribution requirements planning(JIT-DRP)which aims to pull material through a multi-warehouse/multi-retailer supply chain effe
21、ctively.The JIT-DRP gives optimal solutions under deterministic conditions.Literature review determining suitable control parameters of classical systems:The classical inventory control system in supply chains can be broadly divided intotwo types,namely, installation-stock and echelon-stock inventor
22、y control systems.The difference between them is mainly based on information used to make an inventory replenishment decision.The echelonstock inventory control system allows the planner to utilize the network information, while the installation-stock control system allows the planner to use only lo
23、cal information.Details of the two categories can be seen in Axsa ter and Rosling(1994). Many research works try to determine control parameters of classical inventory control systems in supply chains.They aim to minimize the total costs including inventory costs(ordering,holding,and shortage costs)
24、and transportation costs(transportation and in-transit holding costs).Schneider and Rinks(1991) and Schneider et al.(1995)provided a good approximation for parameter setting for the echelon-stock R,s,S control policy.The model is developed based on the backlogging model of a one-warehouse multiple-s
25、tores supply chain.Ganeshan(1999)studied a non-linear programming model which accounts for inventory and transportation costs.Solving the model by the Newton or the conjugate gradient method,the planner obtains near-optimal control parameters of the installation-stock s,Q system.Abdul-Jabar et al.(2
26、003)studied inventorycontrol systems of a one-warehouse/N-retailer network under centralized and decentralized policies.The authors obtained inventory control parameters(replenishment times and reorder quantities)by solving various types of mathematical models concerning holding and ordering costs.A
27、nother determination of control parameters on a one-warehouse/N-retailer network belongs to Axsa ter(2003).The author proposed a technique to approximate optimal reorder points.The model considers holding costs at all locations and backorder costs at retailers.Yokoyama(2002)studied a multi-DC/
28、multi-Retailer model controlled by the installation-stock R,S system.The target inventory and the transportation amountare determined so as to minimize the sum of transportation,holding,and shortage costs.Tagaras(1999)considered the installation-stock R,S system in a one-warehouse/N-retailer network
29、.Order-up-to quantities are calculated by solving a mathematical model concerning holding,shortage,and transshipment costs,if the transshipment between retailers is allowed.Optimal stock levels in general divergent networks under the echelon-stock R,S system was studied by Heijden(2000).The objectiv
30、e is to achieve target fill rates and to minimize total holdingcosts of the entire networks.Recently,control parameters of the traditional R,S system for serial supply chains were improved by Xie et al.(2006).The authors propose a two-level supply chain coordination algorithm to adjust the values of
31、 R and S,which are regularly determined by the local optimization.Some numerical experiments have been conducted and it is found that the supply chain performance is increased due to the new values of R and S.Al-Rifai and Rossetti (2007)proposed an efficient heuristic optimization algorithm to deter
32、mine the control parameters of the s,Q system.Their model is a one-warehouse/multi-retailer supply chain.The goal is to minimize the inventory investment that is affected by average annual ordering frequency and expected number of backorders.The continuous review s,Q policy were also studied by Seif
33、barghy and Akbari Jokar(2006).The authors study a one central-warehouse/multi-identical-retailer supply chain,which faces independent Poisson demands.When the batch size is given,the related reorder point at each facility is determined bya proposed approximate cost function. The remaind
34、er of this paper is organized as follows.Section 2 describes a supply chainmodel.The IDP control system and safety stock policies are presented in Sections 3 and 4,respectively.Section 5 contains the echelon-stock R,s,S control system and an approach to determine its control parameters.The experimen
35、tal design is shown in Section 6.Section 7 discusses the experimental results.Finally,the results are concluded in Section 8. 2.A supply chain model A supply chain under consideration comprises of one-warehouse and multiple identical retailers as depicted in Fig.1.It faces
36、uncertain demand of a single product.When the demand is not satisfied,it is considered as a lost sale.The retailers replenish their inventories from the central warehouse,which in turn replenishes its inventory from an incapacitated vendor outside the concerned supply chain.It is assumed that all storage and transportation capacities are unlimited.Transportation occurs after orders have been placed from the destination.Lateral transshipments between retailers are not allowed.The related costs are ordering,holding,intransit holding,transportation,and lost-sale costs.
