基于MRO采购策略的供应商选择模型构建

在制造业和采矿业中,设备的寿命周期长,因此,MRO视角下的可持续性采购尤其重要.提出了产品寿命周期满意度分析法(PLSA),改进了供应商的选择标准,引入了供应商智能(SI)的概念,充分体现了专家和客户两个群组在确认产品时的意见;指出了MRO视角下采购策略与传统采购策略的不同.最后以实例表明该方法是采购寿命周期长的产品时的一种有效可行的方法.     

一类存贮模型及其最优存贮策略

当工厂仓库容量有限时,常常需要租借仓库来进行存贮.但是,由于租借仓库的存贮单价通常比自己仓库的存贮单价高,所以不能用经典的经济批量公式来计算,有必要重新进行研究.本文研究了原料仓库和产品仓库容量均有限条件下的定料生产销售存贮问题,建立了相应的存贮模型,给出了最优定料生产存贮策略.     

一个具有可变需求率的工业存贮模型及其最优存贮策略

本文研究在一个水平周期τ上具有可变需求率的连续盘点的工业库存系统。文中建立了此库存系统的费用模型,讨论了该系统的最优存贮策略;同时,文中还给出了此模型的一个特例。     

仓库容量有限条件下的一类存贮管理模型

建立了一类仓库容量有限条件下存贮管理决策模型 ,给出最优存贮策略 .     

两种随机存贮管理模型的建立和求解

建立了仓库容量有限条件下单品种、多品种允许缺货的随机存贮模型.采用连续的时间变量更合理地描述了问题,简化了模型的建立.模型的求解是一个以分段的平均损失费用函数作为目标的带约束最优化问题.针对题目中的具体数据对随机量送货滞后时间的密度函数进行了估计,解出了单品种、多品种条件下最优订货点的值和存贮方案.通过分情况讨论把单品种存贮模型推广为多品种(m种)存贮模型,论证了目标函数的独立变量为2m-1个,使模型更加清晰、求解方便.类比控制论中的相关理论提出了一定条件下多品种存贮的最优性原理,给出了证明,指出该原理简化模型和验证模型求解结果的作用.讨论了销售速率具有随机性时的存贮模型,实际当中调整修正订货点的方法,以及仓库最大存贮量的一种预测办法.最后指出了模型的优缺点.     

仓库容量有限条件下的随机存贮管理模型

以商场的商品销售与存贮为研究对象,建立了一类在仓库容量有限条件下的存贮管理决策模型,并给出了最优存贮策略.针对某个大型超市的三种商品的真实销售数据,我们运用该模型分析求解得出了三种商品的最优订货点L*分别为35、39和40.结合销售存贮管理中的实际情况,我们针对商场同时订购多种商品时的情况对模型进行了初步推广,并依据此推广模型得出了在同时订购三种商品时的最优订货点L*为7.2.最后我们进一步讨论了在商品销售率随存贮时间发生变化及存贮变质性商品时的存贮管理决策模型,以便满足不同商家的订货和存贮策略.     

仓库容量有限条件下的随机存贮管理问题的评注

给出2005年全国部分高校研究生数学建模竞赛D题的研究背景,对参赛论文作了简要评注,并提供了一种参考解答.     

多供应商条件下选址模型的一个研究结果

通过实例和对模型的分析,得出[1]中已有多供应商条件上所建模型的不合理性,并提出了模型合理性的原则。     

考虑仓库容量扩张的多周期随机存贮模型——折扣准则

研究了仓库容量可以控制的、基于折扣准则的多周期随机存贮模型.利用马氏决策过程(MDP)的方法,建立了最小折现成本所满足的最优方程,在此基础上,得到了一个(Ut*,yt*(b))结构的最优策略:当仓库容量小于Ut*时将容量扩充到Ut*,并订货至Ut*;否则保持仓库容量不变,且当存贮量小于yt*(b)时订货到yt*(b),反之不订货.     

连锁中心店存贮决策模拟系统研究

针对连锁店中心在约束条件下，如何确定各种商品合理存货水平的问题，本文在建立动态规划模型并求解的基础上，利用计算机对市场需求量的仿真，计算选择连锁中心店存贮量最佳决策方案。     

存货质押融资质押物价格变化MRS-GRACH模型研究

针对质押物价格收益序列存在的结构转换特征,对常系数ARCH模型进行改进,引入一个变化服从马尔科夫过程的状态随机变量反映价格收益不同的波动状况,从而构建了质押物价格收益MRS-GARCH模型.实例研究表明MRS-GARCH模型能够刻画现实中质押物价格收益波动结构动态变化过程,同时能够识别外界不可见因素对收益波动的影响力度,MRS-GARCH模型较GARCH模型在拟合及预测价格收益波动方面具有更准确的效果.     

Inventory control with the gamma probability distribution

Application of inventory theory often rely on the normal and negative exponential distributions to represent the lead time demand of fast and slow moving items respectively. Yet it is now accepted that both distributions, when taken together, are incapable of adequately describing the demand characteristics of all items found in the typical inventory. Instead there has been a growing interest in the use of the gamma probability distribution because it not only encompasses both former distributions as special cases but also covers the gaps left by them. In the process a number of methods for calculating control parameters have appeared in the literature for items with gamma distributed lead time demand. As knowledge about the problem has increased there has been a general tendency towards greater simplification. This paper continues the trend by introducing an approach that depends only on concepts from basic statistics. The aim is to eliminate unnecessary complexity and make the associated theory easier to understand.     

Periodic-Review Inventory Model with Three Consecutive Delivery Modes and Forecast Updates

This paper is concerned with a periodic-review inventory system with three consecutive delivery modes (fast, medium, and slow) and demand forecast updates. At the beginning of each period, the inventory level and demand information are updated and decisions on how much to order using each of the three delivery modes are made. It is shown that there is a base-stock policy for fast and medium modes which is optimal. Furthermore, the optimal policy for the slow mode may not be a base-stock policy in general.This research was supported in part by a Faculty Research Grant from the University of Texas at Dallas, a RGC (Hong Kong) Competitive Earmarked Research Grant, a Distinguished Young Investigator Grant from the National Natural Sciences Foundation of China, and a Grant from the Hundred Talents Program of the Chinese Academy of Sciences.     

模糊需求下的库存风险及最优库存决策

分析了在模糊需求下,按经典库存模型中的经济订货批量和订货周期所导致的库存风险损失。推导了模糊需求下的经济风险函数。给出了风险函数在模糊需求分布下的重心决策方法,在此基础上得到了模糊需求下经济批量的修正公式,为模糊库存风险分析的研究提供了一种方法。     

考虑通货膨胀与最长顾客等待时间的变质性物品的库存模型

本文建立了一种考虑通货膨胀与时间价值的变质性物品的库存模型,在模型中允许短缺发生且拖后的需求速率与在缺货期间已经发生的缺货量有关.和已有相关模型的主要区别在于本模型把一个可重复的订货周期内的最大平均利润的净现值作为目标函数,且增加了在缺货期间最长顾客等待时间的限制,以确保库存系统拥有较高的服务水平.然后讨论了模型最优解的存在性与唯一性,并提供了寻求模型整体最优解的算法.最后用实例说明了此模型在实际中的应用.     

Inventory models for perishable items with inventory level dependent demand rate

This paper presents inventory models for perishable items with inventory level dependent demand rate. The models with and without backlogging are studied. In the backlogging model, it is assumed that the backlogging rate is dependent on the waiting time and the amount of products already backlogged simultaneously. Two cases that holding inventory is profitable or not are studied, respectively. The smallest shelf space to ensure shortage not occur when holding inventory is not profitable is obtained. In the model without backlogging, it is assumed that the remaining stock at the end of the inventory cycle is disposed of with salvage value. The necessary and sufficient conditions for the existence and uniqueness of the optimal solution of these models are investigated. At last, some numerical examples are presented to illustrate the effectiveness of the proposed model. The model in this paper is generalization of present ones. In particularly, the model is reduced to Padmanabhan and Vrat’s when δ₁ = 0, and Dye and Ouyang’s when δ₂ = 0. If S = s and δ₂ = 0, it is Chang, Goyal and Teng’s model.     

Optimal order lot sizing and pricing with free shipping

Companies, especially those in e-business, are increasingly offering free shipping to buyers whose order sizes exceed the free shipping quantity. In this paper, given that the supplier offers free shipping, we determine the retailer’s optimal order lot size and the optimal retail price. We explicitly incorporate the supplier’s quantity discount, and transportation cost into the model. We analytically and numerically examine the impacts of free shipping, quantity discount and transportation cost on the retailer’s optimal lot sizing and pricing decisions. We find that free shipping can benefit the supplier, the retailer, and the end customers, and can effectively encourage the retailer to order more of the good, to the extent of ordering a few times of the optimal order lot size without free shipping. The order lot size will increase and the retail price will decrease if the supplier offers proper free shipping.     

Control Policies for Inventory with Service Time

Abstract

This article introduces an additional control policy—the N-policy–into (s, S) inventory system with positive service time. Under specified interarrival and service time distributions, which are independent of each other, we obtain the necessary and sufficient condition for the system to be stable. We also obtain the optimal values of the control variables s, S, and N; it is seen that the cost function attains the minimum value at s = 0. It is also shown that the cost function is separately convex in the variables S and N. Numerical illustrations are provided. Several measures of performance of the system are evaluated.     

通货膨胀对带有时变需求的变质性物品库存补充策略的影响

本文在考虑通货膨胀的情形下，建立了带有时变需求的变质性物品在有限计划期内的库存补充模型，提供了最优补充次数、最优补充周期长度以及各次补充的最优补充量的一种简单而有效的逼近方法，并用数学例子说明了该方法的实现过程．     

Inventory control with product returns: The impact of imperfect information

Product returns are characterized by considerable uncertainty on time and quantity. In the literature on inventory management for product return environments best forecasts of future returns are associated with methods that use the most information regarding product return history. In practice, however, data is often scarce and unreliable, while forecasts based on historical data, reliable or not, are never perfect. In this paper we therefore investigate the impact of imperfect information with respect to the return process on inventory management performance. We show that in the case of imperfect information the most informed method does not necessarily lead to best performance. The results have relevant implications regarding investments in product return information systems.