考虑库容与订货批量约束的(R, Q) 策略优化

受订货批量和库容限制的购买商向单供应商采购单种产品,以其相邻两次订货间单位时间期望总成本最小为目标建立(R,Q)策略优化模型.针对均匀分布需求给出求解方法,结合算例从资源约束、成本参数及需求特征3个方面进行敏感性分析.将随机需求与资源约束下的安全库存与订货批量进行联合优化,克服已有(R,Q)策略研究将一定时期随机需求期望值默认为最优采购总量,并由此计算订货费、货物成本及缺货成本的不足,可为供应商的选择提供依据。     

考虑配送中心弹性库存的果品采购优化模型

为保证果品质量与降低运输成本,基于小批量多频次采购方式,提出考虑配送中心弹性库存的果品采购优化问题。以水果超市配送中心向多个供应商采购不同品种果品为对象,将库存变化因子引入周期性路径优化模型,建立果品采购优化模型,并设计一种两阶段求解的混合启发式算法。结合算例测试模型与算法的可行性,与已知最优解比较,目标解偏差约为2%,最大为3.3%,经验证,供应商和采购期数量在一定取值范围内,算法具有竞争优势,有利于改善超市物流中心的小批量多频次采购决策能力。     

整合供应商选择的多层级选址-库存模型

针对多级供应链网络设计中选址和库存一体化决策问题,基于梯级库存策略,建立了整合供应商选择的多层级选址-库存模型。模型以网络中供应商的选择成本、工厂和配送中心的打开成本、层级之间的运输成本、库存成本、采购成本和生产成本之和最小为目标,同时对供应商的选择、工厂和配送中心的选址、配送中心对顾客的分配、层级之间的运输量、工厂和配送中心的订货批量进行决策。为了求解所建立的模型,设计了基于部分编码的粒子群优化算法。20个不同规模的算例测试表明：所建立的模型是有效的,能用于多层级供应链网络的设计;所设计的算法无论是在求解精度,还是在运算速度上都明显优于数学优化软件Lingo 9.0,尤其是当供应链网络中总节点数较大时。     

考虑多类零售商的库存与运输VMI 集成策略

研究由单批发商多零售商构成的供应商管理库存(VMI)供应链,批发商向外部供应商订货,并为价格和缺货成本不同的零售商补货.首先构造解析模型以分析如何为多类零售商确定不同的库存分配策略;然后将这一最优的库存分配策略与最优的先到先服务(FCFS)策略进行比较,同时比较相应简化的库存分配策略和简化的FCFS策略.解析和算例结果表明,简化的库存分配策略总是优于简化的FCFS策略,而最优的库存分配策略大部分情况下优于最优的FCFS策略.     

基于双层规划的多供应商物料配送期量优化

为有效解决多供应商单制造商构成的二级供应链中供应商配送批量不经济、配送时间无序导致物流成本高和卸货拥堵等问题,建立多供应商配送期量的双层规划模型.上层模型从库存与配送联合优化视角,考虑供应商配送批量经济性,以供应链物流总成本最低为目标,确定最优配送批量;下层模型基于上层优化结果,考虑制造商生产时序性,以供应商时间惩罚成本最小化为目标,确定供应商配送时间序列.采用遗传算法和动态规划相结合的方法求解上下层模型,得到供应商最优配送期量标准.通过实例运用,验证了模型与算法的有效性及可行性.     

基于双层规划的多供应商物料配送期量优化

为有效解决多供应商单制造商构成的二级供应链中供应商配送批量不经济、配送时间无序导致物流成本高和卸货拥堵等问题,建立多供应商配送期量的双层规划模型.上层模型从库存与配送联合优化视角,考虑供应商配送批量经济性,以供应链物流总成本最低为目标,确定最优配送批量;下层模型基于上层优化结果,考虑制造商生产时序性,以供应商时间惩罚成本最小化为目标,确定供应商配送时间序列.采用遗传算法和动态规划相结合的方法求解上下层模型,得到供应商最优配送期量标准.通过实例运用,验证了模型与算法的有效性及可行性.     

基于第三方的易变质产品库存决策

针对需求受价格影响和需求受价格、库存量共同影响的两种情况,考虑销售商允许缺货且缺货期间出现短缺量部分拖后,研究多个供应商、多个销售商情况下,供应商库存外包于第三方的易变质产品库存联合决策模型.对比分析两模型的结论表明,需求依赖当前销售价格和库存量情况下,考虑易变质产品库存问题更贴近实际,存在最优订货周期、最优销售价格使得供应链整体利益最大化,此时,供应链整体利润并不随着缺货率的增加而单调减小.     

考虑信用融资的期权和实物产品最优组合采购策略

分析由零售商和银行组成的供应链系统, 在零售商面临资金约束的条件下, 通过引入期权采购和信用融资的组合方式, 实现企业的资金风险降低和运作效率提升. 通过建立博弈模型分析得出零售商的最优实物产品采购量和最优期权采购量的显性表达式, 证明银行的最优信用借款利率的存在性和唯一性条件. 通过比较存在资金约束情形下的其他运作方式, 发现信用融资是最有效的决策方式, 可以提升零售商的绩效, 最大可能实现全局最优.

     

一类考虑机器可靠性的变质性物品供应商管理库存

在考虑机器可靠性和通货膨胀的情形下,建立一个供应商和一个订货商,在允许订货商缺货且缺货量部分拖后的易变质产品的供应商管理库存(VMI,Vendor Managed Inventory)模型,给出了数值算例、最优解及主要参数的图形分析,结果表明参数对供应链库存成本均有一定程度的影响,为VMI模式下的库存管理系统提供一些理论依据.     

需求分布不确定条件下的多周期库存鲁棒优化模型

在离散需求情景概率不确定的条件下, 建立基于最大最小方法的多周期库存鲁棒优化模型. 考虑需求分布分别隶属于区间和椭球不确定集两种情形, 运用对偶理论将多周期库存鲁棒优化模型转化为易于求解的凸规划问题. 数值结果表明, 与已知需求分布下的系统最优绩效相比, 采用鲁棒订货策略虽然会导致部分绩效损失, 但损失值很小, 表明基于鲁棒优化的多周期库存订货策略具有良好的鲁棒性, 能够有效抑制需求分布不确定性对库存运作绩效的影响.

     

一种利用切比雪夫逼近求解库存最优控制的方法

针对供应链中库存随着需求的变化可能导致的积压和对生产(或采购)产生的不利影响,为更好地协调生产(或采购)并减少产品库存,研究了一类基于库存约束和动态时变需求下的多品种、多周期、多循环的生产与库存的最优控制模型.结合最优控制理论,给出一种采用切比雪夫多项式逼近和高斯-切比雪夫数值积分对库存最优控制问题进行数值求解的方法.实例分析表明该方法是可行的.     

An integrated multi-stage supply chain inventory model under an infinite planning horizon and continuous price decrease

This paper studies an integrated inventory model in a supply chain that involves procurement, production and delivery activities. The model is studied in an environment where products experience continuous price decrease and planning is performed in an infinite time horizon. In this model, a manufacturing facility purchases a fixed-quantity of raw materials from an outside supplier, processes the materials, and delivers a fixed-quantity of finished products to a customer periodically. In order to take advantage of the decreasing price trend, customers demand frequent deliveries of small lots of finished products, and this inventory management strategy has been used by many successful companies in technology-related industries. Therefore, the ultimate intention of this research is to study and model the inventory system for high-tech companies whose products are experiencing continuous price decrease. This model is used to determine an optimal economic lot size model for raw material procurement, production setup and finished goods delivering under an infinite planning horizon. Two efficient algorithms are developed in this paper to solve this nonlinear model and the test results consistently indicate that ordering of raw materials and delivery of finished goods should be frequent in small lots for low ordering and shipment costs. Finally an operational schedule is provided to show the implementation procedure of the model.     

时变需求下生产与库存系统的最优控制决策方法

针对供应链中库存随着需求的变化可能导致的积压和对生产(或采购)产生的不利影响,为了更好地协调生产(或采购)并减少产品库存,本文研究了以生产为中心的一类基于库存约束和动态线性时变需求下的多品种、多周期、多循环的生产与库存的最优控制模型,结合应用最优控制理论,给出了一种采用切比雪夫多项式逼近和高斯.切比雪夫数值积分对最优控制问题进行数值求解的方法.最后,对某一时变需求情况下的模型应用MATLAB软件进行了求解,得到了生产(采购)与库存的最优控制策略,有效地保证了供应链系统的持续稳定的循环.     

Modeling and analysis of single item multi-period procurement lot-sizing problem considering rejections and late deliveries

Integer linear programming approach has been used to solve a multi-period procurement lot-sizing problem for a single product that is procured from a single supplier considering rejections and late deliveries under all-unit quantity discount environment. The intent of proposed model is two fold. First, we aim to establish tradeoffs among cost objectives and determine appropriate lot-size and its timing to minimize total cost over the decision horizon considering quantity discount, economies of scale in transactions and inventory management. Second, the optimization model has been used to analyze the effect of variations in problem parameters such as rejection rate, demand, storage capacity and inventory holding cost for a multi-period procurement lot-sizing problem. This analysis helps the decision maker to figure out opportunities to significantly reduce cost. An illustration is included to demonstrate the effectiveness of the proposed model. The proposed approach provides flexibility to decision maker in multi-period procurement lot-sizing decisions through tradeoff curves and sensitivity analysis.     

A mathematical model for order splitting in a multiple supplier single-item inventory system

In this paper we develop a mathematical model which considers multiple-supplier single-item inventory systems. The lead times of the suppliers and demand arrival rate are random variables. All shortages are backordered. Continuous review (s, Q) policy has been assumed. When the inventory level hits the reorder level, the total order is split among n suppliers. The problem is to determine the reorder level and order quantity for each supplier so that the expected total cost per time unit, including ordering cost, procurement cost, inventory holding cost and shortage cost is minimized. We also conduct extensive numerical experiments to show the advantages of our model compared to the relevant models in the literature. In addition, some managerial insights are observed.     

A single-period inventory model with fuzzy demand

The single-period inventory models have wide applications in the real world in assisting the decision maker to determine the optimal quantity to order. Due to lack of historical data, the demand has to be subjectively determined in many cases. In this paper, a single-period inventory model for cases of fuzzy demand is constructed. The costs considered include the procurement cost, shortage cost, and holding cost. For different fuzzy total cost resulted from different order quantity, a method for ranking fuzzy numbers is adopted to find the optimal order quantity in terms of the cost. When the profit gained from selling one item is less (greater) than the loss incurred due to one unsold item, the optimal order quantity lies in the range defined for the left-shape (right-shape) function of the fuzzy demand. If the unit profit is equal to the unit loss, then all quantities with a membership grade 1 are optimal to be ordered. The methodology of this paper can be applied to construct other inventory models with fuzzy demand.     

Grouping in decomposition method for multi-item capacitated lot-sizing problem with immediate lost sales and joint and item-dependent setup cost

This article examines a dynamic and discrete multi-item capacitated lot-sizing problem in a completely deterministic production or procurement environment with limited production/procurement capacity where lost sales (the loss of customer demand) are permitted. There is no inventory space capacity and the production activity incurs a fixed charge linear cost function. Similarly, the inventory holding cost and the cost of lost demand are both associated with a linear no-fixed charge function. For the sake of simplicity, a unit of each item is assumed to consume one unit of production/procurement capacity. We analyse a different version of setup costs incurred by a production or procurement activity in a given period of the planning horizon. In this version, called the joint and item-dependent setup cost, an additional item-dependent setup cost is incurred separately for each produced or ordered item on top of the joint setup cost.     

Multi-item partial backlogging inventory models over random planninghorizon in random fuzzy environment

In this paper, some multi-item inventory models for deteriorating items are developed in a random planning horizon under inflation and time value money with space and budget constraints. The proposed models allow stock dependent consumption rate and partially backlogged shortages. Here the time horizon is a random variable with exponential distribution. The inventory parameters other than planning horizon are deterministic in one model and in the other, the deterioration and net value of the money are fuzzy, available budget and space are fuzzy and random fuzzy respectively. Fuzzy and random fuzzy constraints have been defuzzified using possibility and possibility–probability chance constraint techniques. The fuzzy objective function also has been defuzzified using possibility chance constraint against a goal. Both deterministic optimization problems are formulated for maximization of profit and solved using genetic algorithm (GA) and fuzzy simulation based genetic algorithm (FAGA). The models are illustrated with some numerical data. Results for different achievement levels are obtained and sensitivity analysis on expected profit function is also presented.Scope and purposeThe traditional inventory model considers the ideal case in which depletion of inventory is caused by a constant demand rate. However for more sale, inventory should be maintained at a higher level. Of course, this would result in higher holding or procurement cost, etc. Also, in many real situations, during a shortage period, the longer the waiting time is, the smaller the backlogging rate would be. For instance, for fashionable commodities and high-tech products with short product life cycle, the willingness for a customer to wait for backlogging diminishes with the length of the waiting time. Most of the classical inventory models did not take into account the effects of inflation and time value of money. But at present, the economic situation of most of the countries has been much deteriorated due to large scale inflation and consequent sharp decline in the purchasing power of money. So, it has not been possible to ignore the effects of inflation and time value of money any further. The purpose of this article is to maximize the expected profit of two inventory control systems in the random planning horizon.     

基于B/S结构移动物流信息管理平台的设计与实现

本文设计基于B/S结构的移动物流信息管理平台,该平台具有物资产品采购、库存管理、出库、货物跟踪、物流信息查询等功能,实现物流信息管理自动化。基于B/S结构的移动物流信息管理平台采用面向对象设计,表示层、业务层和数据层三层设计结构,模块化平台功能,将平台划分为采购管理模块、库存管理模块和物流编码自动化管理模块,对模块进行设计和实现。     

供应商选择的双层规划模型及求解分析

为了促使供应商在降低产品成本的同时,提高服务质量,提出了利用双层规划建立供应商选择模型。上层规划以制造企业的采购费用最小为目标,下层以选择的供应商的服务质量最大为目标。其中,下层规划中供应商的服务质量用综合评价得分体现先计算出各影响因素的权重,乘以标准判断矩阵得出各供应商的综合得分。最后,结合模型特点设计了双层迭代的算法,并结合实例验证了模型和算法的有效性。