基于时变需求的集成多级供应链生产订货策略研究

考虑一个时变需求环境下集成多级供应链问题,在有限的规划时间内销售商以固定周期订货,而生产商以不同的周期生产,目的是寻找销售商最优的订货周期和生产商最佳的生产策略,从而使供应链系统的总运营成本最少.建立了该问题的混合整数非线性规划模型,求解该模型分为两步：先求对应一个订货周期的最佳生产策略,再求最优的订货周期,第一步用到了图论里求最短路方法.给出了两个步骤的算法和程序,实验证明它们是有效的.通过算例对模型进行了分析,研究了各参数对最优解及最小费用的影响.     

单件、小批量生产的工序质量控制

如何运用数理统计方法对单件、小批量生产进行工序质量控制,已经是重型、矿山、工程机械行业这一类具有单件、小批、多品种生产特点企业,提高产品质量,推行全面质量管理急待解决的问题。本文将从理论和方法上进行某些探讨,力图为具有这种生产特点的企业,找到一条能够运用数理统计方法进行工序质量控制的有效途径。 (一) 对于单件、小批、多品种生产特点的企业来说,如果同时做到如下五条: 第一、选定一台机床(车、刨、镗、铣、磨、钻床)为一个工程,对它进行控制; 第二、对该机床所加工的同一材质(钢号)的产品进行特性值测量记录; 第三、进行…     

集中式供应链的生产与库存分配联合决策

考虑一个由单一制造商和多销售点构成的二级集中式供应链,制造商采用积欠订货策略生产和销售产品,因而面临生产、运输和积欠订货型库存分配与补货的联合决策问题.综合考虑了延迟交货成本、库存持有成本、运输成本和生产成本,建立了最大化总利润的非线性混合整数规划模型,以联合优化供应链的生产、运输及库存分配方案.证明了最优的产品生产分配方案应该具有的结构性质:各个销售网点在任意销售间隔期末同时出现缺货或者库存剩余.同时,提出了基于逐级求解策略的分层求解算法,保证了解的全局最优性.最后,敏感性分析表明:单位产品的库存持有成本与延迟交货成本对最优分配次数及生产量的影响作用相反,固定运输成本也会影响制造商的分配方案及生产计划,但三者均不会影响每个间隔期末的产品分配方案(分配量).     

集团分布式制造模式下生产调配优化模型研究及算法设计

基于分布式概念的集团分布式制造生产管理模式在市场中占据着越来越重要的地位,此种运营模式由制造型企业向服务型企业蔓延的趋势也越来越明显,然而针对这一具有自身特点的集团分布式概念下的生产管理模型的调度研究却很少。研究针对此生产管理模式下集团级的生产调配问题建立数学模型,综合考虑客户订单的分散情况、各分厂日生产能力限制和产品品种多样性的特点,采用改进的遗传算法求解该模型,提出一种基于订单和工厂的两段式非负整数染色体编码方法,保证了生产能力约束和订单约束,采用PMX交叉算法避免不合法染色体的出现。选取W集团一定计划期内的客户订单数据进行实例分析,验证了该生产调配模型和算法的有效性。     

库存理论(六)

§5一些进展 本节简单介绍库存论中如下几个方面的进展:多品种多级库存系统的控制、易腐物品库存理论、具有概率约束的库存模型以及现金管理中的库存问题.这几个方向在库存文献中很活跃,而且有重要的实用价值与理论意义. 5.1多品种多级库存系统的控制 多品种多级库存系统可以形象地表为在这种系统中,最高的第一级是货源点(中心 仓库),它供应第二级的库存点.依此下去,最低 一级的库存点(如零售店)直接满足顾客的需要. 货源点直接从外界订货(或组织生产). 多品种多级库存系统的一个特点是可能有多种 不同的订货策略:单个物品分别订货;联合订货…     

一类易逝品非线性成本库存模型

本文采用指数函数模型来描述易逝品的成本随时间变化的特征,首先求出模型在基本假设条件下的最优订货量和订货成本,然后推导出了在订货商允许缺货、市场需求可变和订货周期可变三个扩展情景下的成本函数;最后通过计算机仿真实验,从经济性和时间效率两方面评价了本文的指数模型相对于经典EOQ模型的优势。     

钢铁企业订货系统模型的VENSIM建模与仿真实现

订货模型存在于大多数的公司中,用以根据销售情况组织公司生产.在简单生产-分配系统模型基础上,构建了钢铁企业零售商订货模型;运用系统动力学方法分析了该订货模型,并采用了阶跃函数描述了复杂变化的零售商销售状况,通过VENSIM建模与仿真分析,找出了零售商销售-订单-库存的相互关系;结果表明,钢铁企业生产-分配系统的特征与采用阶跃函数得出的结果非常相似,对钢铁企业零售商的订货策略具有指导意义.     

基于遗传算法的浸染生产排缸策略

针对目前印染企业在浸染生产过程中产品种类和加工设备多、调度复杂的特性，建立了一种用于浸染生产调度的数学模型，并应用遗传算法进行排缸调度求解。以生产任务的分配优先级顺序作为染色体的编码来求解多个生产任务在多个染缸上的调度分配命题，从而得出了最优排缸策略，适用于快速、高效地解决实际生产中大量生产任务调度问题。仿真结果表明了该策略的有效性和实用性。     

动态随机生产函数模型中库存量的确定

生产制造系统在某种程度上具有不确定性,库存量是影响生产系统的诸多随机变量之一,它随着市场需求、库存成本、企业生产能力等的改变而改变.本文以原有的动态随机生产函数模型为基础,通过在模型中引入库存变化这一随机因素,对该理论模型进行了改进与扩充,使其更加符合生产系统的实际.     

客户耐烦期相同的生产——库存系统最优模型

在常数需求率以及有限生产率条件下研究了订货客户耐烦期相同的一类新的生产——库存模型 ,在每一个周期内考虑了延期交货时间超过耐烦期的短缺费用和销售机会损失等因素 ,给出了相应的最优生产时间和周期的确定方法 ,利用数学软件 Matlab及计算机为工具给出了数字例子进行说明 ,其方法和结果为库存系统的管理决策提供了理论依据     

Production variability in manufacturing systems: Bernoulli reliability case

The problem of production variability in serial manufacturing lines with unreliable machines is addressed. Bernoulli statistics of machine reliability are assumed. Three problems are considered: the problem of production variance, the problem of constant demand satisfaction, and the problem of random demand satisfaction generated by another (unreliable) production line. For all three problems, bounds on the respective variability measures are derived. These bounds show that long lines smooth out the production and reduce the variability. More precisely, these bounds state that the production variability of a line with many machines is smaller than that of a single machine system with production volume and reliability characteristics similar to those of the longer line. Since all the variability measures for a single machine line can be calculated relatively easily, these bounds provide analytical tools for analysis and design of serial production lines from the point of view of the customer demand satisfaction.     

Aggregate production planning for process industries under oligopolistic competition

We consider a competitive version of the traditional aggregate production planning model with capacity constraints. In the general case, multiple products are produced by a few competing producers (oligopoly) with limited capacities. Production quantities, prices and consequently profits depend on production and allocation decisions of each producer. In addition, there is competition for the raw material whose supplies are limited, and where prices reflect these limitations. Such situations have recently occurred in several process industry settings including petro-refining, petrochemicals, basic chemicals, cement, fertilizers, pharmaceuticals, rubber, paper, food processing and metals. We use a successive “Bertrand–Cournot” framework to address this problem and to determine optimal production quantities, prices and profits at the producers and at the raw material supplier. Our analysis allows a new way to understand and evaluate the marginal value of additional capacity when there is competition for the market and raw materials.     

DEA的交形式生产可能集及其应用

DEA理论、模型及方法可用以评价给定决策单元之间的相对有效性,其在经济学中的应用体现在经验生产可能集的构造上.DEA的生产可能集有两种等价形式—和形式及交形式.相比较而言,交形式更具几何直观性及计算便利性.     

A polyhedral approach to a production planning problem

Production planning in manufacturing industries is concerned with the determination of the production quantities (lot sizes) of some items over a time horizon, in order to satisfy the demand with minimum cost, subject to some production constraints. In general, production planning problems become harder when different types of constraints are present, such as capacity constraints, minimum lot sizes, changeover times, among others. Models incorporating some of these constraints yield, in general, NP-hard problems. We consider a single-machine, multi-item lot-sizing problem, with those difficult characteristics. There is a natural mixed integer programming formulation for this problem. However, the bounds given by linear relaxation are in general weak, so solving this problem by LP based branch and bound is inefficient. In order to improve the LP bounds, we strengthen the formulation by adding cutting planes. Several families of valid inequalities for the set of feasible solutions are derived, and the corresponding separation problems are addressed. The result is a branch and cut algorithm, which is able to solve some real life instances with 5 items and up to 36 periods. This revised version was published online in June 2006 with corrections to the Cover Date.     

Production lot sizing with process deterioration and machine breakdown

The paper presents a generalized economic manufacturing quantity model for an unreliable production system in which the production facility may shift from an ‘in-control’ state to an ‘out-of-control’ state at any random time (when it starts producing defective items) and may ultimately break down afterwards. If a machine breakdown occurs during a production run, then corrective repair is done; otherwise, preventive repair is performed at the end of the production run to enhance the system reliability. The proposed model is formulated assuming that the time to machine breakdown, corrective and preventive repair times follow arbitrary probability distributions. However, the criteria for the existence and uniqueness of the optimal production time are derived under general breakdown and uniform repair time (corrective and preventive) distributions. The optimal production run time is determined numerically and the joint effect of process deterioration, machine breakdowns and repairs (corrective and preventive) on the optimal decisions is investigated for a numerical example.     

基于供应方生产能力的应急物资生产模型

利用期权契约所建立的政企合作储备应急物资模式能够有效解决政府单独储备模式所造成的物资储备量过少或过多而引起的困境。然而由于应急物资的需求特性,若应急物资供应企业采用按单生产方式安排生产储备计划,势必会造成库存水平升高,引发资金周转困难等问题,对政企之间的长期合作造成不利影响。基于此,本文设计了基于供应方生产能力的应急物资生产模型。该模型在政府利用批发价格契约与期权契约采购应急物资的基础上,研究了供应方根据自身生产能力进行柔性生产时的生产与储备问题。通过推导政企双方最优决策后,重点分析了期权权利金,执行价格,加急生产成本等参数对供应方生产决策的影响,并证明与按单生产模式相比,柔性生产模式可有效降低供应方的库存量与生产成本,提高其利润,继而提高整体供应链的利润水平,有助于促进政企之间长期稳定的合作。     

Economic Production Lot Size Model with Variable Production Rate and Imperfect Quality

The classical economic production lot size (EPL) model assumes a constant production rate that is predetermined and inflexible, and perfect quality. Recent models have removed the assumption of perfect quality while maintaining the inflexible production rate assumption. Production rates in many cases, such as orders filled by a machine, can be changed. Moreover, unit production cost and process quality depend on the production rate. In this paper, we extend the EPL model to cases where the production rate is a decision variable. Unit production cost becomes a function of the production rate. Also, the quality of the production process deteriorates with increased production rate. We solve the proposed model for special cost and quality functions and illustrate the results with a numerical example. The results show that, for cases where increases in the production rate lead to a significant deterioration in quality, the optimal production rate may be smaller than the rate that minimizes unit production cost. For cases where quality is largely independent of the production rate, the optimal production rate may be larger than the rate that minimizes unit production cost.     

Controlling Rota Scheduled Production by Adjusting Stock Requirements

The paper considers a firm manufacturing several thousand different products, each requiring manufacturing time on several of its available production facilities. Production is scheduled according to a week-by-week rota, arranged so as to generate even average work loads on each production facility. Fluctuations in sales demands, however, lead to a discrepancy between the stock requirements in any section of the rota and the production capacities available. Consequently, to avoid the rota becoming disorganized, some form of production control must be applied. Since the production capacities are largely fixed, this must consist of adjusting the stock requirements. A method of computing adjusted requirements which minimizes a weighted sum of squares of the adjustments made is described. The method is based on Wolfe's technique for quadratic programming, modified to make it computationally feasible in the situation considered which involves several thousand non-negative and usually non-zero variables.     

基于Translog生产函数的中国汽车工业规模经济与替代弹性及价格弹性研究

使用迭代似无关回归(ISUR)方法估计了以生产工人、非生产工人和资本为投入要素的中国汽车工业Translog生产函数及中国汽车工业规模报酬的阶数,利用获得的估计计算了投入要素之间的替代弹性并通过替代弹性计算了要素需求的价格弹性。在此基础上,对中国汽车工业规模经济的状况、投入要素之间的替代或互补关系和要素价格变化对要素需求的影响进行了分析.结果显示:在所研究的期间内,中国汽车工业处于规模报酬不变阶段;生产工人和资本之间以及非生产工人和资本之间是替代关系,而生产工人和非生产工人之间是互补关系;对中国汽车工业而言,三个要素需求缺乏弹性。     

On the Mean Production-rate Analysis of a Two-stage Production System with End Buffer and Random Demand

This paper deals with the transient fluctuations of the mean production rate of a two-stage production system subject to interstage and end inspections and end buffer. The interstage and end inspections are instantaneous, and the end buffer is with finite capacity of size N. A stochastic model is developed to describe the system, and analytical expressions to evaluate the mean production rate (MPR) of machine j (=I, II) in [0, t] with arbitrary distributions of processing times at the stages of production and exponential supply and demand pattern have been obtained by using the state-space method and the regeneration-point technique. A particular case is investigated, and numerical results are presented.