基于变分不等式的闭环供应链超网络模型研究

建立了一个由原材料供应商、生产商、零售商、需求市场和回收中心组成的闭环供应链超网络模型.利用均衡理论以及变分不等式的方法分析网络中各层决策者的独立行为及其相互作用进而得到了该系统达到均衡状态的条件.最后,设计了一个数值算例就旧产品的回收率和利用率及旧材料的利用率等参量对超网络系统的运作性能的影响进行了分析同时也验证了该超网络模型的有效性.     

低碳供应链协同运作的演化模型

针对低碳供应链协同运作的系统演化问题,运用协同论中的伺服原理分析了低碳供应链中的序参量和运作流程;运用布尔代数的逻辑加和逻辑乘运算规则,分析了序参量和运作流程之间的关系。在此基础上,根据系统动力学中的速率原理,构建了低碳供应链协同运作的演化模型,运用自组织原理分析了序参量影响低碳供应链协同运作的演化过程,运用协同效应原理分析了低碳供应链协同运作规律,并对模型进行了应用仿真分析,得出了低碳供应链协同运作的机理。     

货架和仓库商品共同影响需求的供应链延期支付协调

针对单一制造商和单一零售商组成的供应链,研究了需求受货架和仓库库存水平共同影响的企业间延期支付协调问题.首先根据制造商主导的Stackelberg对策结构,对供应链成员间的决策问题进行了分析;然后为制造商提出了一个改善整个供应链运作效率的延期支付策略,研究结果表明该延期支付模型不仅能提高制造商的利润,而且能提高零售商的利润.最后给出了数值例子,并对模型参数灵敏度进行了分析.     

基于λ-最大相容类的粗糙规划模型及其在企业战略联盟形成决策问题中的应用

企业战略联盟作为一种新型、双赢的商业竞争模式,近年来,其联盟的形成问题一直是学术界与应用领域广泛关注的研究内容。本文在分析影响企业战略联盟形成的各因素基础上,首先利用序关系G1法对各影响因素指标进行了权重确定,并用基于相似度的聚类分析法来对属性权重进行筛选和修正;其次以形成的联盟稳定性最高为目标,以λ-最大相容类模拟联盟中各企业之间的相似关系,利用粗糙规划模型的性质和特点,建立了基于λ-最大相容类的粗糙规划模型;最后结合企业战略联盟的具体实例,分析了该模型的特点和有效性。结果表明,该模型丰富了现有的理论成果,为战略联盟的有效形成提供了正确的决策参考。     

我国农村土地间接流转供应链的利益协调机制研究——基于委托代理模型

利益冲突是供应链中的一个共性问题,因而建立合理的利益协调机制对农村土地流转的成功运作无疑是重要的。本文应用博弈论建立了供应链中利益协调的博弈模型——一个两阶段的委托代理模型,以此来分析我国农村土地间接流转模式运作中存在的双重委托代理风险问题,以至于可采取各种措施和手段促进供应链中的信息沟通与协调行为。最后,通过数值模拟与数值算例说明了机制设计的有效性,并对分析结果进行验证。研究结果表明,通过选择合理的机制可以使供应链各成员的期望收益达到帕累托改进,从而实现农村土地间接流转供应链系统的协调。     

基于有向加权网络的价格传导时滞模型

传统的投入产出价格模型利用矩阵描述并分析价格传导过程.因矩阵表述方式属二维模型,故而无法反映价格随时间变化的动态关系.利用有向加权网络描述各产业部门及部门间的价格传导关系,并将时间维度引入构建了价格传导网络模型,考察价格传导时滞的影响.与现有投入产出价格模型相比,模型具有以下三个优势:一是可计算任意时刻的价格传导波动,而传统投入产出价格模型只是该模型在价格传导时间趋向无穷时的特例;二是模型考虑了各部门不同的价格传导时滞的影响,对价格传导过程描述更加精确;三是该模型不受二维矩阵算法的限制,计算复杂度低,易于仿真模拟.     

基于直觉模糊TOPSIS法的煤炭企业设备供应商选择研究

对于煤炭企业来说,设备供应商选择的合理性、适当性是保证其安全、高效生产运作的关键.在供应商选择时,综合考虑设备价格、设备质量、服务能力、技术能力、绿色体系、社会责任6个方面,构建了设备供应商评价指标体系并建立了基于直觉模糊TOPSIS法的设备供应商选择模型.通过对4个供应商方案的实证分析,验证了该模型的有效性.     

基于GMCR-NPAWLAK混合模型的冲突分析研究

冲突分析图模型中,决策者的态度只有肯定和否定两种,实际问题中往往不止两种;新PAWLAK冲突模型(NPAWLAK模型)将冲突系统中决策者的三种态度扩展到决策争端的三种程度,符合实际情况,因而研究冲突系统中决策者的偏好排序和全局可行方案对决策者的策略选择具有重要意义。本文在NPAWLAK模型的基础上,引入冲突分析图模型理论(GMCR),提出GMCR-NPAWLAK冲突分析混合模型。该混合模型首先拓展和改进的策略优先排序法,实现了冲突系统中各决策者的客观偏好排序;同时,模型给出了全局可行方案的算法,该算法依据决策者的偏好排序分析结果找出系统的全局可行方案。最后,本文以某企业劳资关系的NPAWLAK冲突为例,对冲突系统进行建模和偏好分析,得到了冲突各方的偏好序列和全局可行方案,同时验证了混合模型的有效性。     

不同需求条件下供应链系统动态仿真比较研究

本文首先建立供应链节点企业的系统动力学模型,并由此推及到供应链的系统动力学模型。通过使用Vensim对模型进行仿真,引入外生摄动的需求变化,包括阶跃需求、斜坡需求、脉冲波动需求和正弦波动需求,对比分析四种不同需求对供应链系统动态性的影响。研究表明,斜坡需求和正弦波动需求具有渐变的性质,使得供应链各节点企业的牛鞭效应较小;阶跃需求和脉冲波动需求具有突变的性质,供应链各节点企业的牛鞭效应较大。通过销售策略的调整可以改变其外生摄动的需求变化,降低供应链的动态性,提高其运作绩效。     

随机化交通灯的二维元胞自动机交通模型

元胞自动机交通模型以简单的规则反映交通系统中的多种因素，可以分析各种交通现象，且可在计算机上方便、高效地运作·Ｂｉｈａｍ－Ｍｉｄｄｌｅｔｏｎ－Ｌｅｖｉｎｅ模型（ＢＭＬ模型）实现了二维交通问题的元胞自动机模型的模拟研究·本文对ＢＭＬ模型作了改进，解除了该模型中关于交通灯同步变化的限制·在新模型中，每个路口的交通灯可以自由选定起始工作时间和变化节奏，于是可以更全面、准确地反映交通灯对交通系统性能的影响·本文还对新模型中出现的若干新效应作了解释·     

Multi-item lot-sizing with joint set-up costs

We consider a multi-item lot-sizing problem with joint set-up costs and constant capacities. Apart from the usual per unit production and storage costs for each item, a set-up cost is incurred for each batch of production, where a batch consists of up to C units of any mix of the items. In addition, an upper bound on the number of batches may be imposed. Under widely applicable conditions on the storage costs, namely that the production and storage costs are nonspeculative, and for any two items the one that has a higher storage cost in one period has a higher storage cost in every period, we show that there is a tight linear program with O(mT ²) constraints and variables that solves the joint set-up multi-item lot-sizing problem, where m is the number of items and T is the number of time periods. This establishes that under the above storage cost conditions this problem is polynomially solvable. For the problem with backlogging, a similar linear programming result is described for the uncapacitated case under very restrictive conditions on the storage and backlogging costs. Computational results are presented to test the effectiveness of using these tight linear programs in strengthening the basic mixed integer programming formulations of the joint set-up problem both when the storage cost conditions are satisfied, and also when they are violated.     

An Improved,Multiplier Adjustment Procedure for the Segregated Storage Problem

The segregated storage problem consists of determining an optimal distribution of products among existing storage compartments such that at most one product may be stored in a given compartment. The problem is solved using linear programming, Lagrangean relaxation and multiplier adjustment techniques. The procedures are easily adapted to obtain good heuristic solutions quickly. Computational results are given.     

基于多候选储位的存取路径优化问题研究

针对单储位储存方式可能导致仓库存取通道拥挤和作业效率低的情形,提出了一种基于多候选储位的存取路径优化方法。首先分配了货物的存取储位,然后建立了多候选储位的车辆路径问题(MLVRP)模型,并基于储位优先解码原则设计了遗传算法,最后通过算例证明该方法的有效性和算法的高效性。多候选储位的方法可以为取货任务至少节约18.4%(两个候选储位)和21.8%(三个候选储位)的路程,算法迭代10000次只需要434s。     

仓库容量有限条件下的随机存贮管理2

讨论了仓库容量有限条件下的随机存贮管理优化问题,认为时间是连续分布的.对于存贮一种商品的问题,根据订货点和自己仓库容量的关系分两种情况讨论,得到平均损失费与订货点、到货时间之间的关系式,利用实测数据拟合出到货时间的概率密度,建立了以平均损失费用的数学期望为目标函数的最优化模型,并使用MATLAB数学软件进行求解,得到三种商品的最优订货点分别为41,37和36.经过分析得知仓库容量与销售速率的比例、单位商品的损失费均对确定订货点都有重要影响.对于存贮多种商品的问题,根据到货时间的取值范围与两个时间临界点(销售完租借仓库中某种商品的时间和销售完所有该种商品的时间)之间的位置关系,将每种商品分为六种情况,m种商品组合起来,就有6()种不同情况,在此基础上,以m种商品的总体平均损失费用的数学期望作为目标函数,建立问题的最优化模型.针对题目中给出的三种商品的情形进行求解,得到最优订货点L*=4.807.最后,对销售速率随机的情形建立模型并进行了讨论.     

Security and efficiency data sharing scheme for cloud storage

With the adoption and diffusion of data sharing paradigm in cloud storage, there have been increasing demands and concerns for shared data security. Ciphertext Policy Attribute-Based Encryption (CP-ABE) is becoming a promising cryptographic solution to the security problem of shared data in cloud storage. However due to key escrow, backward security and inefficiency problems, existing CP-ABE schemes cannot be directly applied to cloud storage system. In this paper, an effective and secure access control scheme for shared data is proposed to solve those problems. The proposed scheme refines the security of existing CP-ABE based schemes. Specifically, key escrow and conclusion problem are addressed by dividing key generation center into several distributed semi-trusted parts. Moreover, secrecy revocation algorithm is proposed to address not only back secrecy but efficient problem in existing CP-ABE based scheme. Furthermore, security and performance analyses indicate that the proposed scheme is both secure and efficient for cloud storage.     

On the Flow-Shop Sequencing Problem with No Wait in Process<Superscript>†</Superscript>

The optimization problem of minimizing the completion time in flow-shop sequencing with an environment of no intermediate storage is considered. Application of this problem in computer systems is pointed out and techniques are developed to solve the problem.     

Dynamic storage allocation with limited compaction - complexity and some practical implications

In this paper, the problem of dynamic memory allocation with limited compaction of contigious segments, is considered. To be more precise, we are concerned with the problem of finding, given the storage state, a free storage space of a given size by reallocating segments whose total size is minimal. The general case of this problem will be proved to be NP-hard. It is, however, possible to give a linear time algorithm for solving a restricted case, involving only a few types of segment sizes. Moreover, for the general case we present several bounds on the storage size ensuring the possibility of finding in linear time a free space of the desired size by reallocating not more than L memory cells.     

A column generation approach for determining optimal fleet mix,schedules, and transshipment facility locations for a vessel transportation problem

This paper presents a column generation approach for a storage replenishment transportation-scheduling problem. The problem is concerned with determining an optimal combination of multiple-vessel schedules to transport a product from multiple sources to different destinations based on demand and storage information at the destinations, along with cost-effective optimal strategic locations for temporary transshipment storage facilities. Such problems are faced by oil/trucking companies that own a fleet of vessels (oil tankers or trucks) and have the option of chartering additional vessels to transport a product (crude oil or gasoline) to customers (storage facilities or gas stations) based on agreed upon contracts. An integer-programing model that determines a minimum-cost operation of vessels based on implicitly representing feasible shipping schedules is developed in this paper. Due to the moderate number of constraints but an overwhelming number of columns in the model, a column generation approach is devised to solve the continuous relaxation of the model, which is then coordinated with a sequential fixing heuristic in order to solve the discrete problem. Computational results are presented for a range of test problems to demonstrate the efficacy of the proposed approach.     

Defining order picking policy: A storage assignment model and a simulated annealing solution in AS/RS systems

Improving technology, variable customer demands, variety of products and increasing improvement of production systems has brought storage facilities, which has an important role on business operations, to a critical point. This circumstance has revealed the necessity on activating of storage systems and operations. In this study, mathematical model, which minimizes simultaneously storage allocation, storage retrieval and storage keeping costs, is generated for an AS/RS system of an enterprise. The mathematical model has run for small solution space and optimal solution is obtained. The problem in this study is an NP hard problem that is why optimal solution cannot be obtained for large solution spaces. So the problem in existing system is solved by using simulated annealing and an optimal order policy is proposed.     

Offsetting inventory replenishment cycles to minimize storage space

In a recent paper, [Murthy, N.N., Benton, W.C., Rubin, P.A., 2003. Offsetting inventory cycles of items sharing storage. European Journal of Operational Research 150, 304–319] discussed the problem of offsetting inventory replenishment cycles of several items in order to minimize the maximum required storage space. They analyzed the case where replenishment cycles are given integer multiples of a basic period and proposed a heuristic to solve the problem. While they provided a good analysis of the considered problem, the proposed heuristic produces less interesting results. In the following, a simpler, more efficient and easier to implement heuristic is proposed. Numerical results are provided to prove its superiority.