在中心仓库有损失销售的二级分布库存管理模型的研究

通过对一个中心仓库和N个零售商的二级分布库存系统进行分析,采用基本(S-1,S)库存策略,综合运用了排队法和M ETR IC近似法,提出了一种在中心仓库有损失销售的二级库存管理模型,该模型描述在中心仓库缺货情况下,多数零售商不等待延期付货,而直接与供应商订货,导致中心仓库就会因损失销售而产生机会成本.该模型可达到二级分布库存系统的总成本最小.     

电子商务背景下的城市物流共享仓库动态选址研究

针对电商顾客需求波动较大、分布较广、时效性较强等特点,首次将顾客需求的波动性及仓库资源的共享性等因素引入动态选址问题,并综合考虑运输成本、租赁共享仓库成本、关闭成本及风险成本等因素,以总成本最小为目标,构建了电子商务背景下的物流共享仓库动态选址模型.针对模型的NP难特性,提出了一种改进的遗传算法来求解该模型.最后,通过算例验证了模型的可行性及算法的有效性.     

面向远海岛礁群的双向物流网络规划

针对若干远海岛礁群系统封闭性的分布特点,将中心岛礁选址、各岛礁建设泊位数量和规模、仓库储存量、运输船型和数量以及航线设置、班期组织等作为规划内容,以整个运输网络系统总成本最低为原则,综合考虑了仓库存储理论,建立了兼顾“选址-库存-路径”的规划模型。结合所建模型特点,提出了双层并行搜索遗传算法,构建了以海上运输为基本交通方式的双向物流系统。最后,以我国南海为例进行建模并求解,采用不同算法并通过多组不同规模的算例进行演算比较,验证了所建模型和算法的有效性与合理性。     

井位不确定环境下的油田仓库选址问题

油田工作中,合理的仓库选址决策不仅能节约物流成本,而且能提高油田作业效率。现有研究通常基于当前的油井位置(简称井位),没有考虑未来井位变化对仓库选址的影响。同时井位受到地下储层条件及油气公司远景规划等因素影响,未来的井位具有很强的不确定性。此外,仓库选址决策属中长期决策,将长期影响油田的物流费用、管理工作甚至开发工作,而且油田生产要求仓库能持续供应物资,所以油田仓库选址应考虑井位的不确定性和仓库服务中断等因素。本文首先根据油田井位分布和钻井规划采用随机模拟方法模拟未来井位,建立并求解考虑设施中断的离散选址模型。然后以鄂南油区物资仓库选址问题为例,模拟井位并求解仓库选址问题,从8个候选点中选出3个建库/租库。最后,分析井位和需求量变化对仓库选址结果的影响。井位不确定环境下油田物资仓库选址问题的研究,不仅对油田物流系统管理的研究具有一定的理论意义,也对油田的物流决策有重要的现实意义。     

油库选址决策的二层优化模型研究

油库物流设施的选址决策属于战略管理层的决策,它是整个物流系统运作的基础.油库的选址决策是库存和运输决策的基础,库存决策和运输决策则是在整个油品配送系统规划框架内对油库选址决策的完善和延伸.如何进行科学的油库选址是企业所关心的问题.本文将在考虑影响选址的定性成本因素以及运营过程中的非成本因素、定性和定量相结合的基础上利用多层决策理论,将油库选址问题归结为一个二层优化模型,并提出了确定理想选址区域和可行点的相关方法的计算方法.数值实验表明该算法是可行的.本文的结论对实际决策问题具有一定的借鉴作用.     

需求依赖于展示区库存水平的易腐品订购和转运策略

本文主要研究易腐品零售商的订货和转运策略。零售商的库存分为两部分,即展示区/货架库存和仓库库存。零售商定期向供应商订货,零售商收到订购的商品首先将其中一部分商品存放在展示区中,余下的部分储存在仓库。展示区的空间是有限的,并且需求依赖于展示区商品的库存量。本文首先建立了以平均利润最大化为目标的库存优化模型并对模型最优解的存在性进行了分析,然后得到了求解最优订购量、转运量、转运时间间隔以及再订购点的算法,最后给出了不同参数条件下的算例。     

基于绩效保障模式的可修备件保障系统运营管理策略

基于绩效保障模式,设计了一个由备件仓库和维修车间组成的装备可修部件闭环保障系统,推导了备件库存水平状态的稳态概率分布,计算了可用度等几个保障绩效度量指标,建立了基于可用度约束的保障系统运作优化模型,并通过仿真分析探讨了保障系统运营管理策略问题。     

基于顾客低碳行为偏好的选址-路径-库存集成优化模型与算法

针对自愿减排驱动下的顾客低碳行为偏好对选址-路径-库存决策的影响进行研究。首先推导了顾客低碳行为偏好下的市场需求函数和价格函数,并构建了考虑单位产品碳排放量和经济成本的多目标选址-路径-库存优化模型,通过对多目标优化模型的求解可得碳排放量和经济成本间的Pareto解集。在此基础上,定义了碳配额税的概念,可得顾客低碳行为偏好和碳配额税下的总收益函数。最后通过数值分析给出了自愿减排和监管减排两种机制共同作用下的企业减排方案和灵敏度分析。     

一个基于运输规模经济的库存选址模型

介绍了一种新的配送中心(DC)选址模型,在该模型中考虑了一般库存和安全库存成本,同时把从供应商到DC的运输成本也结合进去综合考虑,运输成本是由固定成本加可变成本两部分组成,反映了运输规模经济.     

一个三级物流系统的运送策略优化问题

主要考虑一个三级物流系统的运送策略优化问题,系统由多个供货商、多个客户和一个中央仓库组成.假定两级库存均采用周期补货策略,每个客户处的产品需求为确定性需求.假设给定一套可行频率的情况下,选择使整个系统总的长期平均成本最小化的仓库的补货策略和仓库到各客户的配送策略.根据两个支配性质构造了一个列举优化算法,计算试验讨论了该算法的有效性.     

An inventory sharing and allocation method for a multi-location service parts logistics network with time-based service levels

We consider a model to allocate stock levels at warehouses in a service parts logistics network. The network is a two-echelon distribution system with one central warehouse with infinite capacity and a number of local warehouses, each facing Poisson demands from geographically dispersed customers. Each local warehouse uses a potentially different base stock policy. The warehouses are collectively required to satisfy time-based service targets: Certain percentages of overall demand need to be satisfied from facilities within specified time windows. These service levels not only depend on the distance between customers and the warehouses, but also depend on the part availabilities at the warehouses. Moreover, the warehouses share their inventory as a way to increase achieved service levels, i.e., when a local warehouse is out of stock, demand is satisfied with an emergency shipment from another close-by warehouse. Observing that the problem of finding minimum-cost stock levels is an integer non-linear program, we develop an implicit enumeration-based method which adapts an existing inventory sharing model from the literature, prioritizes the warehouses for emergency shipments, and makes use of a lower bound. The results show that the proposed inventory sharing strategy results in considerable cost reduction when compared to the no-sharing case and the method is quite efficient for the considered test problems.     

A new partial pooling structure for spare parts networks

Motivated by real-life spare parts networks, we introduce a new spare parts inventory model with lateral transshipment. We consider a multi-item, multi-location, single-echelon system with base stock control and aggregate mean waiting time constraints. The local warehouses are divided into two types: main and regular local warehouses. Lateral transshipment is allowed from main local warehouses only. A practical advantage of this structure is that only a limited number of local warehouses has to be equipped to provide lateral transshipment. This structure represents a new form of partial pooling, with no pooling (zero main locals) and full pooling (zero regular locals) as special cases. We develop an accurate and fast approximate evaluation method, and exploit this method in a heuristic procedure for the base stock level determination. We show that only a small number of main locals is sufficient to obtain most of the full pooling benefits. We also apply our methods to case data of ASML, an original equipment manufacturer in the semiconductor supplier industry. As a result of our work ASML was able to improve spare parts planning.     

应急物流中库存与运输集成决策模型研究

已有的研究表明,在物流管理中权衡库存与运输成本之间的关系,实现两者的集成决策,可改进系统的运作绩效。在给定的仓库布局条件下,针对应急物流的配送特点,构建了单周期物资的运输与库存集成决策的随机规划模型。考虑到模型求解的复杂性,首先通过对模型的分析,获得了最优解的性质和上界,然后设计了基于BP神经网络和遗传算法的混合智能算法。在算例分析部分,揭示了服务水平、运输、和库存成本在应急物流中之间的复杂关系,说明合理权衡三者之间的关系,可以提升应急物流的管理水平。     

A Lagrangian relaxation approach to simultaneous strategic and tactical planning in supply chain design

We study a multi-echelon joint inventory-location model that simultaneously determines the location of warehouses and inventory policies at the warehouses and retailers. The model is formulated as a nonlinear mixed-integer program, and is solved using a Lagrangian relaxation-based approach. The efficiency of the algorithm and benefits of integration are evaluated through a computational study.     

基于排队的库存服务系统最优控制策略

研究一个连续盘点的(s,Q)补货的库存服务系统。基于排队理论建立库存水平状态平衡方程,并推导出库存水平稳态概率分布以及作为库存控制的系统稳态性能指标。以库存成本最小化为目标,构建服务水平约束的库存控制模型。针对模型的非线性约束与整数型变量的特征,采用一种改进的遗传算法(IGA)用于决策变量的寻优。数值实验表明,当目标服务水平大于库存系统内生的服务水平时,实施服务水平约束能够降低库存控制成本。     

区域二级应急救援系统多救援点协同策略研究

主要研究在需求不确定的救援环境下,由一个区域救援总站和多个地方救援点组成的二级应急救援系统多种救援物资协同共享问题.各地方救援点对救援物资的需求为随机模糊变量,当某一地方救援点救援物资不足时,可以通过不同的协同方式进行应急补库,所有应急补库方式均考虑了地方救援点的优先级.据此建立了在一定服务满足率条件下以救援时间最短为目标函数的模型,结合随机模糊变量模拟和PSO、PSO-SA算法对模型进行了求解.最后对各种协同方式进行了对比并分析了相关变量的敏感性.结果表明:允许完全转运的协同共享方式能有效地缩短救援时间.     

Optimization of component reliability in the design phase of capital goods

We introduce a quantitative model to support the decision on the reliability level of a critical component during its design. We consider an OEM who is responsible for the availability of its systems in the field through service contracts. Upon a failure of a critical part in a system during the exploitation phase, the failed part is replaced by a ready-for-use part from a spare parts inventory. In an out-of-stock situation, a costly emergency procedure is applied. The reliability levels and spare parts inventory levels of the critical components are the two main factors that determine the downtime and corresponding costs of the systems. These two levels are decision variables in our model. We formulate the portions of Life Cycle Costs (LCC) which are affected by a component’s reliability and its spare parts inventory level. These costs consist of design costs, production costs, and maintenance and downtime costs in the exploitation phase. We conduct exact analysis and provide an efficient optimization algorithm. We provide managerial insights through a numerical experiment which is based on real-life data.     

Cost-effective inventory control in a value-added manufacturing system

This paper considers the cost-effective inventory control of work-in-process (WIP) and finished products in a two-stage distributed manufacturing system. The first stage produces a common WIP, and the second stage consists of several production sites that produce differentiated products with different capacity and service level requirements. The unit inventory holding cost is higher at the second stage. This paper first uses a network of inventory-queue model to evaluate the inventory cost and service level achievable for given inventory control policy, and then derives a very simple algorithm to find the optimal inventory control policy that minimizes the overall inventory holding cost and satisfies the given service level requirements. Some managerial insights are obtained through numerical examples.     

Multi-source facility location–allocation and inventory problem

We consider a joint facility location–allocation and inventory problem that incorporates multiple sources of warehouses. The problem is motivated by a real situation faced by a multinational applied chemistry company. In this problem, multiple products are produced in several plants. Warehouse can be replenished by several plants together because of capabilities and capacities of plants. Each customer in this problem has stochastic demand and certain amount of safety stock must be maintained in warehouses so as to achieve certain customer service level. The problem is to determine number and locations of warehouses, allocation of customers demand and inventory levels of warehouses. The objective is to minimize the expected total cost with the satisfaction of desired demand weighted average customer lead time and desired cycle service level. The problem is formulated as a mixed integer nonlinear programming model. Utilizing approximation and transformation techniques, we develop an iterative heuristic method for the problem. An experiment study shows that the proposed procedure performs well in comparison with a lower bound.     

An exact solution procedure for multi-item two-echelon spare parts inventory control problem with batch ordering in the central warehouse

We consider a multi-item two-echelon inventory system in which the central warehouse operates under a (Q,R) policy, and the local warehouses implement basestock policy. An exact solution procedure is proposed to find the inventory control policy parameters that minimize the system-wide inventory holding and fixed ordering cost subject to an aggregate mean response time constraint at each facility.