应急物流中驾驶员优选的灰色聚类决策

驾驶员的指派是完成应急物流中运输配送的重要环节,合理地选择驾驶员是实现应急物资及时准确安全运送到位的重要保障。运用灰色聚类决策,从影响驾驶员选择的五项决策指标入手,求解出各驾驶员关于各灰类的决策系数向量,根据决策系数的大小,判定驾驶员所属的灰类,并确定指派的优先顺序。最后,通过案例分析,说明应急物流中驾驶员的优选采用灰色聚类决策是可行的、有效的。     

船体分段模块装配工艺决策研究

针对船体装配工艺设计自动化程度低，影响船舶建造周期和建造质量等问题，设计了分段模块的装配单元决策系统，建立了分段模块装配信息模型，基于模糊数学理论，应用模糊聚类方法实现了分段模块装配工艺的自动编制．实例表明，该方法是合理的和可行的．应用该方法在较高的装配层次上实现了船体模块装配工艺的制定，为船舶模块化生产提供了有效的工具．     

基于八维结构模型的雇员工作绩效灰局势评价

在合并不同概念的基础上,从任务绩效、非任务绩效、创新能力、学历等工作绩效因素和组织承诺、工作满意度、离职倾向和绩效倾向等心理定向因素出发,使用一个八维蛛网模型评估雇员工作绩效.根据先前的工作绩效结构文献,运用灰色系统原理建立了雇员工作绩效识别的多目标灰色局势决策方法,得出每个雇员的工作绩效成份及综合测度效果.通过一个实际的案例应用,证明了该方法是一个切实可行的、科学的决策方法.     

精品课程评估的灰色聚类模型

为使评估更具科学性,本文将灰色系统理论应用于精品课程的评估.依照国家精品课程评审指标(本科,2010)体系,我们利用灰色聚类方法定义了指标的白化权函数,并给出精品课程评估的灰色聚类数学模型,然后利用这一数学模型讨论了精品课程灰色聚类实例.本文的结果对当今高校教学质量工程建设具有一定的意义.     

基于灰色聚类方法的关键链项目工期风险评估

工期不确定以及资源冲突等问题的存在使得项目进度管理更加复杂。为有效地识别工期风险,本文在灰色关键链法的基础上,首先运用一致指数对工序工期进行灰色估计,并综合考虑资源紧张度、工序复杂度、开工柔性、风险偏好、环境不确定性5个影响项目进度的不确定性因素。然后,基于三角白化权函数的灰色聚类评估模型确定综合聚类系数,从而进行工期风险评估。最后通过算例分析,快速识别工期风险大的工序,降低工期延误风险,验证所提方法的有效性和实用性。     

考虑资源成本的Petri网在FMS调度中的应用

本文针对目前基于petri网的调度方法中调度目标单一的缺点，通过在petri网的结构中引入资源成本元素的方法，使得在调度计划产生的过程中可以同时考虑时间和资源成本优化，为企业作出更为科学合理的生产决策提供依据．最后通过一个实例来验证了提出的算法。     

基于自动拆卸过程的装配序列生成方法研究

装配序列生成是装配工艺规划的基本任务,设计了一个基于自动拆卸过程的装配序列生成算法。首先,进行自动拆卸仿真,通过过程中的干涉检查生成可行的装配序列集。然后,定义了三类装配序列优先约束规则,对可行序列集进行过滤选择,得到可用于最终评价的少量装配序列。该算法在SolidWorks平台上得到了实现,给出了实例验证。     

可装卸式加油设备的管路系统装配设计研究

由于在不同装配空间的管路系统装配结构存在相似性和差异性,可装卸式加油设备的管路系统装配设计十分复杂．针对该问题,提出了基于谱系聚类法的管路系统装配空间聚类方法,使聚类后的每类装配空间能够通用多套已装配好的管路系统．通过定义类的典型装配空间及装配半径,使新设计的加油设备按其管路系统装配空间尺寸,迅速地找到符合要求的已装配好的管路系统．最后,以对一些典型的装配空间进行聚类及如何应用聚类结果为例,验证了该方法的有效性和合理性．     

基于灰色聚类评估的配送中心选址模糊多目标优化模型

将多属性决策方法与最优化方法相集成,研究了多配送中心选址优化问题。首先采用灰色聚类决策计算各候选地定性属性的综合评估值。再以选定配送中心的评估值均值最大化、系统成本最小化,以及配送中心容量利用率最大化作为3个优化目标,建立一个考虑需求点模糊需求、供应点与候选配送中心容量限制的三级供应链系统多配送中心选址模型。该模型被描述成了一个多目标的非线性混合整数规划模型。采用机会约束规划对模糊需求进行清晰化处理,并应用目标加权的方法将问题转化为单目标问题。通过算例验证了所提模型的可行性。在实际工作中,可根据决策者权重偏好得出令人满意的结果。     

基于聚类分析技术的装配流程平衡运行研究

通过测算不同装配流水线上各个工序作业时间,利用聚类分析技术将各流水线按不同作业时间进行聚类,并画出装配时间谱系聚类图.根据聚类分析得出的各流水线作业时间类别及相互类级关系,控制各条流水线上零部件的投放时间及物流速度,使不同流水线上的装配零部件在最短时间相遇,据此达到装配流程平衡运行,提高装配效率.     

基于区间数的多指标灰靶决策模型的研究

现实生活中遇到的许多问题都具有不确定性，使得在对系统进行决策评估时，指标值难以精确化。在此情形下，人们常常对指标值给出一个区间，到目前为止， 尚未有人研究区间数灰靶决策。首先定义了区间数、m维区间数的距离及其距离性质，并证明了当区间数为实数时，区间数距离就是实数距离的推广；提出了区间数规范化方法，在此基础上, 建立了基于区间数的灰靶决策模型，从而把灰靶决策模型由实数序列拓展到区间数序列，使灰靶决策理论得到发展，同时为扩大灰靶决策的应用领域提供了理论根据。最后以实例验证了该模型的有效性与实用性。     

Expert Enhanced Coloured Stochastic Petri Net and its application in assembly/disassembly

This article comprises of an Expert Enhanced Coloured Stochastic Petri Net (rule base system, or RBS) for modelling and analysing assembly/disassembly systems. RBSs are an Enhanced High-level Petri net extended with Close-World-Assumption (CWA). Traditional Petri nets can be used to model RBSs containing explicitly described knowledge. The main focus was is to facilitate and analyse the process planning activities of assembly/disassembly. The advantages of the new modelling approach were: (1) consideration of the non-desirable events, (2) occurrence of assembly/disassembly tasks with regard to colour of the tokens and utilization of probability concept to determine feasible steps, (3) establishing a relationship among components by means of arc labels, and (4) deeper insight into the assembly/disassembly process using high- and low-level petri nets.     

Assembly planning with an ordering genetic algorithm

The goal of assembly planning consists in generating feasible sequences to assemble a product and selecting an efficient assembly sequence from amongst these. This paper describes an original ordering genetic algorithm (OGA) developed to solve this problem. The developed approach permits the generation of assembly trees for a mechanical product. The algorithm is based on three main ideas. First, a mapping transforms any studied assembly plan into a valid one using 'precedence values' changing through the sequence, so that an invalid sequence will never be proposed. Secondly, to identify subsets, trace is kept all along the sequence of the components membership to a set of parts. Finally, the individuals of the OGA are compared with each other using a multi-criteria decision aided method called PROMETHEE II. The use of this method avoids aggregating several technical criteria into a unique fitness value. The proposed algorithm, illustrated through the simple example of a mouse device, has been applied on an industrial signalling relay made of 34 parts.     

3D geometric constraint analysis and its application on the spatial assembly sequence planning

Focusing on the spatial geometric feasible assembly sequence planning and optimising, a novel approach entitled 3D-GCA is proposed based on the method of Geometric Constraint Analysis (GCA) incorporated with the Oriental Bounding Box (OBB) and Separation Axis Theory. Accordingly, the corresponding computer-aided 3D assembly sequence planning system is developed and two cases are studied in detail. The analysis results demonstrate that, with 3D-GCA method, the spatial assembly precedence relations (APRs) can be calculated out correctly and completely. Thereby, all the 3D geometric feasible assembly sequences can be derived automatically. Moreover, an optimisation algorithm is designed based on 3D-GCA method, by which, the optimal assembly sequences can be calculated out according to two criteria, e.g., assembly angle and assembly direction. The 3D-GCA method and its algorithms can provide significant assistance in the spatial geometric feasible assembly sequences reasoning and the optimal sequences selection.     

Computer-aided process planning for assembly: generation of assembly operations sequence

Process planning for assembly requires a computerized representation and analysis of assembled products. In order to recommend a good sequence of assembly operations, the process planner needs to generate all such feasible sequences. This paper presents a methodology to consistently generate all feasible asssembly sequences with consideration for the various combinations of subassembly operations. The methodology is demonstrated on a real product. A practical method to reduce the number of feasible combinations generated is also demonstrated.     

基于工程语义约束的线束预装配自动规划方法

线束预装配是线束生产的重要环节,论文通过总结线束工艺设计中的工程语义约束信息,建立装配关联图模型,提出了一种线束预装配自动规划方法。该方法通过主件选择、最大子装配体提取、工程语义约束检测来实现对预装配序列自动规划,而无需与用户进行交互。最后的实例表明该方法是有效可行的,能较好的解决大线束图纸中装配序列规划问题。     

The effects of work-in-process inventory costs on the design and scheduling of assembly lines with low throughput and high component costs

This paper considers a class of assembly systems with long cycle times (low volume of output) and highly expensive components or subassemblies. Systems such as these are typical for companies in the aerospace industry assembling missiles and airplanes. As each unit of the product moves along the assembly line, its value increases owing to additional parts or components installed and the additional work performed. We show that sequencing activities according to ascending values of the ratios of the 'value added' to activity duration minimizes inventory holding cost within a given workstation. A branch-and-bound procedure is then used to allocate activities optimally to a given number of workstations. The objective function used in this paper is to maximize the net profit of a production line, which comprises net revenues minus inventory holding costs and fixed costs of workstations. The design of the assembly line is affected by two decision variables: number of workstations and cycle time. Finally, it is shown that a 'balanced' line is not necessarily an optimal one and 'pushing' activities to the right (the end of the assembly line) may reduce total holding costs and improve the profitability of the line.     

Optimisation of assembly sequences for compliant body assemblies

Multi-sequence modelling is proposed to optimise assembly sequences for compliant body assemblies such as automotive and aircraft bodies. Multi-sequence modelling is composed of assembly modelling, assembly sequences, tolerance analysis, and assembly operations. Assembly modelling describes the geometric modelling through the liaison graph, which is based on assembly sequence optimisation. Assembly sequences provide information for assembly sequence optimisation. Three-dimensional tolerance analysis is employed to evaluate assembly operations, which is different from previous conceptual tolerance analysis. A genetic algorithm is presented to optimise assembly operations among components. Results show that different sequences lead to a different tolerance of key product characteristics because assembly operations among components are not identical. This paper provides the flowchart of optimising assembly sequences according to the tolerance of key product characteristics.     

Evaluation of product assemblability in different assembly sequences using the tolerancing approach

This paper discusses an approach to evaluate the assemblability of a product according to its assembly sequence. A concept called Sensitive Tolerance in Assembly is proposed and its influence on the assembly is investigated. The approach using a transformation matrix is proposed to determine the geometric deviations of mating features caused by the tolerance and assembly clearance, and the resulting propagation and accumulations in the different assembly sequences. An example is given to illustrate the approach to derive the relative assemblability of a product for comparing different assembly sequences.     

Shades of grey: A critical review of grey-number optimization

A grey number is an uncertain number with fixed lower and upper bounds but unknown distribution. Grey numbers find use in optimization to systematically and proactively incorporate uncertainties expressed as intervals plus communicate resulting stable, feasible ranges for the objective function and decision variables. This article critically reviews their use in linear and stochastic programs with recourse. It summarizes grey model formulation and solution algorithms. It advances multiple counter-examples that yield risk-prone grey solutions that perform worse than a worst-case analysis and do not span the stable feasible range of the decision space. The article suggests reasons for the poor performance and identifies conditions for which it typically occurs. It also identifies a fundamental shortcoming of grey stochastic programming with recourse and suggests new solution algorithms that give more risk-adverse solutions. The review also helps clarify the important advantages, disadvantages, and distinctions between risk-prone and risk-adverse grey-programming and best/worst case analysis.