Multi-item EOQ inventory model with varying holding cost under two restrictions: A geometric programming approach

In this paper we provide a simple method to determine the inventory policy of multiple items having varying holding cost using a geometric programming approach. The varying holding cost is considered to be a continuous function of the order quantity. The EOQ inventory model with constant holding cost and the classical EOQ inventory model without constraints are derived.     

两种订货模式下订购和促销联合优化策略

本文基于CVaR决策准则,通过构建需求依赖于促销的一般需求模型,其中包括加法和乘法需求模型作为特例,考察了一次订货和允许紧急订货两种模式下风险厌恶零售商关于促销和库存的联合优化问题。讨论了紧急订购成本、风险厌恶以及市场需求变动对最优策略的影响,并对两种模式下零售商的最优策略和收益进行了比较分析,结果表明:在两种订货模式下,零售商的最优订购量和促销努力均随风险厌恶程度的增大而降低;紧急订货模式下的促销努力和实现的收益大于一次订货模式,且在加法需求模型下,紧急订货模式下的初次订购量小于一次订货模式的最优订购量。运用随机变量一阶和二阶交替随机占优的概念刻画了市场需求变动下零售商如何调整最优策略的充分条件。最后实施数值实验验证了理论分析结果。     

An inventory model with lot-size dependent ordering cost

The classical Harris - Wilson inventory model assumes that the ordering cost is constant and does not depend on the quantity ordered. There are, however, many practical situations where this is not true. This paper considers an inventory model where the ordering cost depends on the size of the lot and increases in steps as the lot size increases. An algorithm is developed to determine the economic order quantity and is illustrated by a numerical example.     

基于B2B电子交易市场的零售商最优订购策略

B2B电子交易市场能够为企业提供现货交易、远期合约交易以及产能期权合约交易等交易服务.B2B电子交易市场中交易的期权合约在签订后至到期日之前可再次交易.以此为背景研究了零售商最优采购策略.研究结果表明,期权合约可再次交易为供应链中的零售商提供新的投机渠道,显著地提高了零售商对期仅合约的采购数量,而对与固定供应商签订的长...     

Stochastic efficiency analysis with a reliability consideration

Stochastic Data Envelopment Analysis (DEA) models have been introduced in the literature to assess the performance of operating entities with random input and output data. A stochastic DEA model with a reliability constraint is proposed in this study that maximizes the lower bound of an entity׳s efficiency score with some pre-selected probability. We define the concept of stochastic efficiency and develop a solution procedure. The economic interpretations of the stochastic efficiency index are presented when the inputs and outputs of each entity follow a multivariate joint normal distribution.     

Multi-item production lot-size inventory model with varying order cost under a restriction: A geometric programming approach

In this paper we present a geometric programming approach for determining the inventory policy for multiple items having varying order cost, which is a continuous function of the order quantity, and a limit on the total average inventory of all items. Our model is a generalization of that of Gupta and Gupta for unrestricted single-item order quantity model with varying order cost and assumes the same order cost function. This cost function relates well to real-life situations since it increases as the order quantity increases and, at the same time, it is easy to handle when deducing previous work as special cases of our model since it is easily reducible to a constant. An example is solved to illustrate the method.     

The blocking job shop with rail-bound transportation

The blocking job shop with rail-bound transportation (BJS-RT) considered here is a version of the job shop scheduling problem characterized by the absence of buffers and the use of a rail-bound transportation system. The jobs are processed on machines and are transported from one machine to the next by mobile devices (called robots) that move on a single rail. The robots cannot pass each other, must maintain a minimum distance from each other, but can also “move out of the way”. The objective of the BJS-RT is to determine for each machining operation its starting time and for each transport operation its assigned robot and starting time, as well as the trajectory of each robot, in order to minimize the makespan. Building on previous work of the authors on the flexible blocking job shop and an analysis of the feasible trajectory problem, a formulation of the BJS-RT in a disjunctive graph is derived. Based on the framework of job insertion in this graph, a local search heuristic generating consistently feasible neighbor solutions is proposed. Computational results are presented, supporting the value of the approach.     

基于 B2B电子交易市场的零售商最优订购策略

B2B电子交易市场能够为企业提供现货交易、远期合约交易以及产能期权合约交易等交易服务.B2B电子交易市场中交易的期权合约在签订后至到期日之前可再次交易.以此为背景研究了零售商最优采购策略.研究结果表明, 期权合约可再次交易为供应链中的零售商提供新的投机渠道, 显著地提高了零售商对期仅合约的采购数量, 而对与固定供应商签订的长期合约采购数量的影响不明显, 因此零售商在线下与网上市场的总订货量将有所增加.最后, 对供应链中的采购者、供应商以及第三方 B2B电子交易市场提出建议.     

Revised GRASP with path-relinking for the linear ordering problem

The linear ordering problem (LOP) is an NP\mathcal{NP}-hard combinatorial optimization problem with a wide range of applications in economics, archaeology, the social sciences, scheduling, and biology. It has, however, drawn little attention compared to other closely related problems such as the quadratic assignment problem and the traveling salesman problem. Due to its computational complexity, it is essential in practice to develop solution approaches to rapidly search for solution of high-quality. In this paper we propose a new algorithm based on a greedy randomized adaptive search procedure (GRASP) to efficiently solve the LOP. The algorithm is integrated with a Path-Relinking (PR) procedure and a new local search scheme. We tested our implementation on the set of 49 real-world instances of input-output tables (LOLIB instances) proposed in Reinelt (Linear ordering library (LOLIB) 2002). In addition, we tested a set of 30 large randomly-generated instances proposed in Mitchell (Computational experience with an interior point cutting plane algorithm, Tech. rep., Mathematical Sciences, Rensellaer Polytechnic Institute, Troy, NY 12180-3590, USA 1997). Most of the LOLIB instances were solved to optimality within 0.87 seconds on average. The average gap for the randomly-generated instances was 0.0173% with an average running time of 21.98 seconds. The results indicate the efficiency and high-quality of the proposed heuristic procedure.     

基于净现值的模糊型多项目多期投资优化模型

探讨了基于净现值的多项目多期优化模型,并且分别讨论了目标函数和约束条件呈现模糊时与含有模糊系数时的模型以及它们的求解.根据模型的背景利用三角模糊数处理模糊系数,给出了相应的模糊机会约束规划模型,提出了一种模糊约束规划清晰化的新方法,然后在此基础上结合遗传算法对模型进行求解.最后,数值仿真说明了模型的应用与算法的可行性.     

Single machine lot scheduling with non-uniform lot capacities and processing times

Journal of Combinatorial Optimization - In this paper, we investigate the single machine lot scheduling problem in which each lot contains one or more jobs (or part of jobs). Jobs with different...     

已实现波动与日内价差条件下的CVaR估计

随着高频金融数据的获取,已有很多基于高频数据的研究,包括已实现波动率的估计及其分布特征分析等.尝试结合日内高频数据和日收益率数据,基于Copula方法分析了日收益率与"已实现"波动率以及日内价差之间的相依结构.通过分象限对数据进行了Copula拟合,给出了一类特殊数据的联合分布估计方法,进而给出了已实现波动率和日内价差条件下的CVaR的估计方法.最后基于中国股市上证综指和深证成指的高频收益率数据进行了实证分析,并对两种条件下的CVaR方法进行了预测效果的比较,实证结果表明已实现波动率条件下的CVaR预测效果更好.     

两次生产和订货模式下的供应链契约式协调

研究了考虑供应链成员的退货处理成本和相对出清优势情形下,两次生产和订货模式 的供应链契约式协调问题,分析了退货契约和滞销补贴契约的适用条件,设计了有效的退货契 约和滞销补贴契约,以协调供应链成员的决策,使销售商的两次订货量达到集中决策的水平, 并通过数值仿真的方法发现:提高退货价格或滞销补贴,能增加销售商的期望利润和总订货 量,并且使其更趋向于在第一次订货,减少第二次的订货量;制造商第一次生产量也因销售商 订货量的增加而增加,第二次生产量则变化不大,制造商的期望利润随着退货价格的提高而不 断下降;一定数量的滞销补贴可使制造商的绩效有所提高,制造商的期望利润随着滞销补贴的 增加而下降.     

An approximation algorithm for stochastic multi-level facility location problem with soft capacities

Journal of Combinatorial Optimization - Facility location problem is one of the most important problems in the combinatorial optimization. The multi-level facility location problem and the facility...     

供应链融资模式下零售商的订货与定价研究

已有零售商订货与定价问题的研究大都忽略了零售商的初始资金,本文在考虑零售商初始资金的情况下,研究零售商面对初始资金不足时,如何借助外部的融资政策做出最优的订货与定价决策.因此,本文分别讨论了零售商在无融资服务,供应链中核心制造商担保下的外部融资服务及核心制造商提供商业信用的内部融资服务下的订货与定价问题,并建立了相应的...     

Robotic assembly of printed circuit boards with component feeder location consideration

The use of industrial robots for the assembly of printed circuit boards (PCB) is fast gaining popularity. Minimization of the time required for board assembly while maintaining production quality is the process planner's main task. This task involves the specification of the insertion sequence of components in their respective locations and the assignment of component types to feeders or dispensing magazine slots. The time taken by a robot to fetch a component for insertion is dependent on the location of the feeder that holds the component type. Similarly, board assembly lime is dependent on the order of component insertion on the board and the fetch time of components between insertions. In this paper, models to minimize the total assembly time for a board are developed and studied. Factors considered in the analysis of the assembly time are the component assignment to magazine     

A multiperiod auto-carrier transportation problem with probabilistic future demands

In this paper we study the problem of delivering finished vehicles from a logistics yard to dealer locations at which they are sold. The requests for cars arrive dynamically and are not announced in advance to the logistics provider who is granted a certain time-span until which a delivery has to be fulfilled. In a real-world setting, the underlying network is relatively stable in time, since it is usually a rare event that a new dealership opens or an existing one terminates its service. Therefore, probabilities for incoming requests can be derived from historical data. The study explores the potential of using such probabilities to improve the day-to-day decision of sending out or postponing cars that are ready for delivery. Apart from the order selection, we elaborate a heuristic to optimize delivery routes for the selected vehicles, whereby special loading constraints are considered to meet the particular constraints of car transportation via road. In a case study, we illustrate the value of introducing probabilistic information to the planning process and compare the quality of different configurations of our approach.     

Multi-item inventory model with quantity-dependent inventory costs and demand-dependent unit cost under imprecise objective and restrictions: A geometric programming approach

A multi-item inventory model with constant demand and infinite replenishment is developed under the restrictions on storage area, total average shortage cost and total average inventory investment cost. These restrictions may be precise or imprecise. Here, it is assumed that inventory costs are directly proportional to the respective quantities, and unit purchase/production cost is inversely related to the demand. Restricted shortages are allowed but fully backlogged. First, the problem is formulated in crisp environment taking the deterministic and precise inventory parameters. It is solved by both geometric programming (GP) and gradient-based non-linear programming (NLP) methods. Later, the problem is formulated with fuzzy goals on constraints and objectives where impreciseness is introduced through linear membership functions. It is solved using the fuzzy geometric programming (FGP) method. The inventory models are illustrated with numerical values and compared with the crisp results. A sensitivity analysis on the optimum order quantity and average cost is also presented due to the variation in the tolerance of total average inventory investment cost and total average shortage cost following Dutta et al., 1993, Fuzzy Sets and Systems, 55, 133-142.     

短保质期变质产品的两次订货策略研究

一类短保质期变质产品,如生鲜蔬菜、水果等,增加其库存展示量能为顾客提供更多的拣选机会,从而刺激顾客增加购买量.对此,在综合分析已有变质库存基本模型的基础上,建立了一个更能准确反映当前存货水平和需求率、变质率的关系的库存模型.考虑到计划期可能不是最优订货周期的整数倍,从一般意义上研究了基于保质期约束和计划期可修正的变质产品最后两次订货策略.结论表明,最优订货周期须超过一个保质期.在计划期的一定变动范围内,订货周期越短越有利于增加利润和增强经营的社会外部性,并在计划期的上界达到最优;超过计划期的合理变动范围,则须将不完整订货周期控制在一个保质期内,且越接近保质期越好,否则随着计划期延长,变质量增加而利润却逐渐降低.