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1.
We address the concept of an integrated inventory allocation and shipping model for a manufacturer with limited production capacity and multiple types of retailers with different backorder/waiting and delivery costs. The problem is to decide how to allocate and deliver produced items when the total retailer demand exceeds the production capacity, so that total retailer backorder and delivery costs are minimized. Our analytical model provides optimal allocation and shipping policies from the manufacturer’s viewpoint. We also investigate the allocation strategy of a manufacturer competing with other retailers to directly sell to end consumers. 相似文献
2.
在电子商务终端物流配送方面,存在能力与需求的矛盾。一方面,电动车存在货物容量约束和电池电量约束,配送能力有限;另一方面,一个物流配送点需要为众多的消费者进行门到门的配送,配送任务繁重。针对电子商务环境下终端物流配送规模大、电动车货物容量和行驶里程有限的问题,建立电商终端物流配送的电动车配置与路径规划集成优化模型,并提出一种基于临近城市列表的双策略蚁群算法,实现物流配送电动车辆配置与配送路径集成优化。该模型以电动车辆数最少和总路径最短为目标,以电动车货物容量和电池续航里程为约束,是带容量的车辆路径问题的进一步扩展,属于双容量约束路径规划问题。双策略蚁群算法在货物容量和续航里程的约束下,将蚁群搜索策略分为两类,即基于临近城市列表的局部搜索策略和全局搜索策略,在提高搜索效率的同时防止陷入局部优化。最后,通过阿里巴巴旗下菜鸟网络科技有限公司在上海的30组真实配送数据进行了测试,验证双策略蚁群算法显著优于一般蚁群算法。 相似文献
3.
In shipping services, the goal is to propose cyclical routes which ensure transport of required goods among the main centers of the regions. It is classified as a pickup and delivery problem with split demand and reloading. The objective is to minimize total shipping costs, or the total length of all cyclical routes. The optimum solution gives a number of vehicles going on arcs of the communication network and the amount of goods being transported on the arcs. Consequently, cyclical routes and depots are proposed for all vehicles. First, the multi-graph, in which each directed arc corresponds to exactly one vehicle, is generated. The multi-graph satisfies the condition that the number of arcs entering each node equals the number of arcs exiting the node. The heuristic method of loading goods onto a vehicle in the pickup node and to transport it to the delivery node without reloading onto another vehicle is proposed. The method is verified in the case study carried out on the DHL company. 相似文献
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5.
We consider a supply chain in which one manufacturer sells a seasonal product to the end market through a retailer. Faced with uncertain market demand and limited capacity, the manufacturer can maximize its profits by adopting one of two strategies, namely, wholesale price rebate or capacity expansion. In the former, the manufacturer provides the retailer with a discount for accepting early delivery in an earlier period. In the latter, the production capacity of the manufacturer in the second period can be raised so that production is delayed until in the period close to the selling season to avoid holding costs. Our research shows that the best strategy for the manufacturer is determined by three driving forces: the unit cost of holding inventory for the manufacturer, the unit cost of holding inventory for the retailer, and the unit cost of capacity expansion. When the single period capacity is low, adopting the capacity expansion strategy dominates as both parties can improve their profits compared to the wholesale price rebate strategy. When the single period capacity is high, on the other hand, the equilibrium outcome is the wholesale price rebate strategy. 相似文献
6.
《European Journal of Operational Research》1997,101(3):509-518
In this paper we study a single-depot/multi-retailer system with independent stochastic stationary demands, linear inventory costs, and backlogging at the retailers over an infinite horizon. In addition, we also consider the transportation cost between the depot and the retailers. Orders are placed each period by the depot. The orders arrive at the depot and are allocated and delivered to the retailers. No inventory is held at the depot. We consider a specific policy of direct shipments. That is, a lower bound on the long run average cost per period for the system over all order/delivery strategies is developed. The simulated long term average cost per period of the delivery strategy of direct shipping with fully loaded trucks is examined via comparison to the derived lower bound. Simulation studies demonstrate that very good results can be achieved by a direct shipping policy. 相似文献
7.
We consider the infinite horizon inventory routing problem in a three-level distribution system with a vendor, a warehouse and multiple geographically dispersed retailers. In this problem, each retailer faces a demand at a deterministic, retailer-specific rate for a single product. The demand of each retailer is replenished either from the vendor through the warehouse or directly from the vendor. Inventories are kept at both the retailers and the warehouse. The objective is to determine a combined transportation (routing) and inventory strategy minimizing a long-run average system-wide cost while meeting the demand of each retailer without shortage. We present a decomposition solution approach based on a fixed partition policy where the retailers are partitioned into disjoint and collectively exhaustive sets and each set of retailers is served on a separate route. Given a fixed partition, the original problem is decomposed into three sub-problems. Efficient algorithms are developed for the sub-problems by exploring important properties of their optimal solutions. A genetic algorithm is proposed to find a near-optimal fixed partition for the problem. Computational results show the performance of the solution approach. 相似文献
8.
In this paper we consider a complex production-distribution system, where a facility produces (or orders from an external
supplier) several items which are distributed to a set of retailers by a fleet of vehicles. We consider Vendor-Managed Inventory
(VMI) policies, in which the facility knows the inventory levels of the retailers and takes care of their replenishment policies.
The production (or ordering) policy, the retailers replenishment policies and the transportation policy have to be determined
so as to minimize the total system cost. The cost includes the fixed and variable production costs at the facility, the inventory
costs at the facility and at the retailers and the transportation costs, that is the fixed costs of the vehicles and the traveling
costs. We study two different types of VMI policies: The order-up-to level policy, in which the order-up-to level quantity
is shipped to each retailer whenever served (i.e. the quantity delivered to each retailer is such that the maximum level of
the inventory at the retailer is reached) and the fill-fill-dump policy, in which the order-up-to level quantity is shipped
to all but the last retailer on each delivery route, while the quantity delivered to the last retailer is the minimum between
the order-up-to level quantity and the residual transportation capacity of the vehicle. We propose two different decompositions
of the problem and optimal or heuristic procedures for the solution of the subproblems. We show that, for reasonable initial
values of the variables, the order in which the subproblems are solved does not influence the final solution. We will first
solve the distribution subproblem and then the production subproblem. The computational results show that the fill-fill-dump
policy reduces the average cost with respect to the order-up-to level policy and that one of the decompositions is more effective.
Moreover, we compare the VMI policies with the more traditional Retailer-Managed Inventory (RMI) policy and show that the
VMI policies significantly reduce the average cost with respect to the RMI policy. 相似文献
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In this paper we consider a 1-warehouse, N-retailer inventory system where demand occurs at all locations. We introduce an inventory model which allows us to set different service levels for retailers and direct customer demand at the warehouse. For each retailer a critical level is defined, such that a retailer replenishment order is delivered from warehouse stock if and only if the stock level exceeds this critical level. It is assumed that retailer replenishment orders, which are not satisfied from warehouse stock, are delivered directly from the outside supplier, instead of being backlogged. We present an analytical upper bound on the total cost of the system, and develop a heuristic method to optimize the policy parameters. Numerical experiments indicate that our technique provides a very close approximation of the exact cost. Also, we show that differentiating among the retailers and direct customer demand can yield significant cost reductions. 相似文献
11.
An approximation algorithm for the pickup and delivery vehicle routing problem on trees 总被引:1,自引:0,他引:1
Naoki Katoh 《Discrete Applied Mathematics》2006,154(16):2335-2349
This paper presents an approximation algorithm for a vehicle routing problem on a tree-shaped network with a single depot where there are two types of demands, pickup demand and delivery demand. Customers are located on nodes of the tree, and each customer has a positive demand of pickup and/or delivery.Demands of customers are served by a fleet of identical vehicles with unit capacity. Each vehicle can serve pickup and delivery demands. It is assumed that the demand of a customer is splittable, i.e., it can be served by more than one vehicle. The problem we are concerned with in this paper asks to find a set of tours of the vehicles with minimum total lengths. In each tour, a vehicle begins at the depot with certain amount of goods for delivery, visits a subset of the customers in order to deliver and pick up goods and returns to the depot. At any time during the tour, a vehicle must always satisfy the capacity constraint, i.e., at any time the sum of goods to be delivered and that of goods that have been picked up is not allowed to exceed the vehicle capacity. We propose a 2-approximation algorithm for the problem. 相似文献
12.
《Operations Research Letters》2019,47(4):305-310
Consider a bilateral monopoly selling to a market with uncertain demand. The retailer has access to a demand signal. The supplier can add a direct channel, which grants it market access as well. The supplier and the retailer can acquire signals from each other with payments. We show that direct selling by the supplier improves information flow to realize system-wide information transparency, which has mixed effects on the profits for the retailer and the system. 相似文献
13.
This article considers a single product coordination system using a periodic review policy, participants of the system including a supplier and one or more heterogeneous buyers over a discrete time planning horizon in a manufacturing supply chain. In the coordination system, the demand of buyer in each period is deterministic, the supplier replenishes all the buyers, and all participants agree to plan replenishment to minimize total system costs. To achieve the objective of the coordination system, we make use of small lot sizing and frequent delivery policies (JIT philosophy) to transport inventory between supplier and buyers. Moreover, demand variations of buyers are allowed in the coordination system to suit real-world situations, especially for hi-tech industries. Furthermore, according to the mechanisms of minimizing the total relevant costs, the proposed method can obtain the optimal number of deliveries, shipping points and shipping quantities in each order for all participants in the coordination system. 相似文献
14.
Marie-Claude Bolduc Jacques Renaud Benoit Montreuil 《Central European Journal of Operations Research》2006,14(2):209-228
This paper presents a multi-period vehicle routing problem for a large-scale production and distribution network. The vehicles
must be routed in such a way as to minimize travel and inventory costs over a multi-period horizon, while also taking retailer
demands and the availability of products at a central production facility into account. The network is composed of one distribution
center and hundreds of retailers. Each retailer has its demand schedule representing the total number of units of a given
product that should have been received on a given day. Many high value products are distributed. Product availability is determined
by the production facility, whose production schedule determines how many units of each product must be available on a given
day. To distribute these products, the routes of a heterogeneous fleet must be determined for a multiple period horizon. The
objective of our research is to minimize the cost of distributing products to the retailers and the cost of maintaining inventory
at the facility. In addition to considering product availability, the routing schedule must respect many constraints, such
as capacity restrictions on the routes and the possibility of multiple vehicle trips over the time horizon. In the situation
studied, no more than 20 product units could be carried by a single vehicle, which generally limited the number of retailers
that could be supplied to one or two per route. This article proposes a mathematical formulation, as well as some heuristics,
for solving this single-retailer-route vehicle routing problem. Extensions are then proposed to deal with the multiple-retailer-route
situation. 相似文献
15.
为解决重大疫情引发的供应中断导致生鲜品库存水平振荡,在市场需求随机变化的情形下,建立一个由供应商、配送中心和零售商组成的三级生鲜供应链库存系统,考虑由疫情引起的三种风险情景,引入系统动力学模型对零售商动态库存系统运营进行仿真分析。研究发现:受疫情风险传导系数和变质率两个序参量影响,供应链库存呈现振荡趋势;通过确定不同供应中断时长下的疫情风险情景提出优化保鲜投入策略、安全库存策略、以及共享库存联合提前转运策略有效降低零售端库存水平振荡并使其呈现渐稳趋势,实现产品在交付过程中的双重时效性,达到供需匹配,缓解疫情风险带来的影响,为相关零售企业提供决策支持。 相似文献
16.
Robert N. Boute Stephen M. Disney Marc R. Lambrecht Benny Van Houdt 《European Journal of Operational Research》2014
We consider a supply chain in which orders and lead times are linked endogenously, as opposed to assuming lead times are exogenous. This assumption is relevant when a retailer’s orders are produced by a supplier with finite capacity and replenished when the order is completed. The retailer faces demands that are correlated over time – either positively or negatively – which may, for example, be induced by a pricing or promotion policy. The auto-correlation in demand affects the order stream placed by the retailer onto the supplier, and this in turn influences the resulting lead times seen by the retailer. Since these lead times also determine the retailer’s orders and its safety stocks (which the retailer must set to cover lead time demand), there is a mutual dependency between orders and lead times. The inclusion of endogenous lead times and autocorrelated demand represents a better fit with real-life situations. However, it poses some additional methodological issues, compared to assuming exogenous lead times or stationary demand processes that are independent over time. By means of a Markov chain analysis and matrix analytic methods, we develop a procedure to determine the distribution of lead times and inventories, that takes into account the correlation between orders and lead times. Our analysis shows that negative autocorrelation in demand, although more erratic, improves both lead time and inventory performance relative to IID demand. Positive correlation makes matters worse than IID demand. Due to the endogeneity of lead times, these effects are much more pronounced and substantial error may be incurred if this endogeneity is ignored. 相似文献
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18.
The paper considers a three-echelon supply chain which consists of one supplier, one manufacturer and one retailer for trading a single product. The market demand at the retailer is influenced by the retail price and the quality of the product. The quality of the finished product at the manufacturer depends on the supplier’s raw material quality. We analyze the model for both deterministic and stochastic demand patterns. We first study the centralized and decentralized systems, and then the decentralized system with a sub-supply chain coordination strategy (where the manufacturer chooses to merge with either the supplier or the retailer and then acts as a single entity) and the two-level retail fixed mark-up (RFM) strategy. In the case of the two-level RFM strategy, the manufacturer and the retailer use fixed mark ups over the supplier’s wholesale price. The proposed models are demonstrated through numerical examples. It is observed from the numerical study that the two-level RFM strategy is superior to the sub-supply chain coordination strategy. Further, the two-level RFM strategy in the stochastic demand scenario is not as effective as in the deterministic demand scenario. 相似文献
19.
Postponement strategies are becoming increasingly important in light of a global trend in which products’ life-cycles are decreasing, such that even products that are not traditionally considered seasonal become “obsolete” within a short period of time (e.g., electronic devices, new cars). Our work addresses postponed-pricing and ordering decisions for a retailer who sells a newsvendor-type inventoried product, in a selling season that is divided into two sub-periods. The division of the selling season enables the retailer to on-line adjust her decisions when faced with a scenario (one that is highly prevalent in reality) in which potential demand changes (increases or decreases) following consumers’ experiences of the product in early stages of the selling season. We assume that the retailer has two opportunities for receiving shipments: prior to the first sub-period and prior to the second one. The retailer determines each order quantity (base-stock level) on the basis of the demand distribution for the corresponding sub-period. In each sub-period, after observing additional market signals, the retailer determines the price of the product for that sub-period. With the aid of a stochastic programming approach, we develop optimization problems and solution methods in order to obtain pricing and ordering decisions that maximize the expected profit of the retailer. We present an extensive numerical example that compares the suggested strategy to three alternative strategies, and conclude that price postponement and responsiveness to demand changes can each reduce leftovers and lost sales as well as substantially increase expected profit. 相似文献
20.
《European Journal of Operational Research》1997,99(2):401-411
In this paper we consider a two-level inventory system with a central warehouse and a number of retailers. All facilities apply continuous review (R,Q)-policies. We first extend Forsberg's exact Poisson model to the case with unit demand and customer inter-arrival times that are Erlang distributed. In the case with generally distributed customer inter-arrival times we approximate by Erlang distributions. We use two different methods to choose the approximate Erlang distribution. The first method means that we, for each retailer, choose the Erlang distribution that has the exact mean and minimum difference in standard deviation. Our second method means that we, for each retailer, choose the Erlang distribution of customer inter-arrival times that gives the exact mean and minimum difference in the standard deviation of the demand per unit of time instead of the inter-arrival time. Both methods are tested on 38 simulated cases. In all cases both methods give the same approximation. 相似文献