基于公理设计和相容决策支持问题法的稳健优化设计方法

 针对多目标稳健优化问题,建立了多目标稳健优化的损失函数,利用灵敏度分析方法确定各设计变量对各设计目标的影响程度,确定主要的设计参数,便于调整和控制设计参数的公差.根据信息公理与损失函数的一致性关系,建立以最小化各目标的总损失函数为目标函数.并在相容决策支持问题法框架基础上,提出一种基于公理设计和相容决策支持问题法的多目标稳健优化设计模型.实例分析表明,提出的方法是可行的.     

基于公理设计的产品设计解耦方法

针对利用公理设计理论进行产品设计时存在的很多耦合问题,综合应用公理设计理论与创新问题解决理论,提出利用创新问题解决理论中的矛盾矩阵来解决公理设计中耦合问题的一般方法,并通过打桩机的解耦设计对这一方法进行说明。     

基于公理设计的工业机械手设计方案评价研究

基于公理设计理论,结合工业机械手常见的设计方案组成元素,建立了工业机械手概念设计方案评价模型,实现了对工业机械手概念设计方案组进行评价并得到最优方案的推理过程.基于以上方法开发了原型系统,并以典型的工业机械手设计方案为例进行评价,验证了该理论和方法的可行性.研究表明,本文提出的基于公理设计的方案评价方法有利于设计过程的优化,其推理过程的形式化描述,便于计算机的表达和操作.该方法为工业机械手设计过程的优化做了一些有益的探索.     

基于公理的机械产品设计

公理设计是机械设计理论中的一种,本文介绍了在公理设计理论指导下的机械产品设计。     

可重构制造系统设施布置公理化设计研究

首先阐述了可重构制造系统和公理化设计的基本知识,然后通过公理化设计的两个公理(独立性公理和信息公理)对可重构制造系统进行设计.在独立性公理的应用中,将总目标进行了四级分解,每一级分解通过四个步骤来完成,并列出了各自的设计方程.然后汇总列举出了相应的功能结构表;在信息公理的应用中,针对非耦合设计和准耦合设计的情况分别计算...     

面向可适应性的产品平台设计参数规划方法

 在分析已有产品平台特点的基础上,将模块化和参数化产品平台统一表示为基于“设计参数”的产品平台,提出了面向可适应性的产品平台设计参数规划方法．引入可适应设计理念,分析了产品平台结构及变型方式;以公理设计理论为指导,进行产品功能要求 设计参数的映射,建立公理设计矩阵;分析各设计参数之间及其与功能要求之间的敏感性,构建设计关联矩阵并对其进行关联度分析;然后通过变型产品关于设计参数的差异度计算,合理识别平台参数和变型参数,确定设计参数在产品平台中的共享策略．通过桥式起重机产品族的柔性配置实例,证明了该方法的可行性和实用性．     

基于公理设计的产品结构设计模型研究

目的为了满足客户的实际需求,缩短产品设计周期,避免传统设计方法生成产品结构的过程中易产生设计耦合的潜在问题。方法以结构设计作为主要目的,提出一种基于公理设计的产品结构设计模型(AxiomaticDesignBasedStructuralDesign,ADBSD)。该模型在质量功能展开(QualityFunction Deployment, QFD)的基础上,采用KANO模型的赋值计算规则,获得总体客户功能需求权重值,作为结构设计的总功能需求,输入公理设计框架流程中的"Z"字型映射中;并运用TRIZ技术冲突、发明原理等工具进行设计优化,在设计初期解决设计参数之间的冲突问题,得到完整的产品设计结构。结果通过对小空间自走式消防装备进行设计研究,阐述了运用ADBSD进行产品结构设计的优势,验证了该方法的可行性。结论该模型为产品创新设计过程提供了新思路和理论参考。     

从设计入手搞好空调系统的节能

从负荷计算、冷源主机配置、风机风压的确定和水系统优化四个方面提出了中央空调节能设计的一些方法,同时指出了目前中央空调设计中存在的一些问题。     

公理化设计理论与TRIZ集成的设计方法研究

公理化设计理论与TRIZ在产品设计开发中都有其优势及局限性。公理设计在系统性地生成概念初始方案方面有优势,TRIZ在解决设计中出现的冲突方面有优势。提出了集成公理化设计理论与TRIZ解决设计问题的一种方法。首先应用公理设计理论形成设计的概念初始方案;其次分析所得设计方案中可能存在的冲突,并分清冲突的类型是物理冲突还是技术冲突;然后对不同的冲突采用相应的冲突解决原理来解决;最后重新设计新的设计参数来消除冲突。通过液压修井机设计实例说明了这种方法的有效性。     

基于TRIZ和公理设计的公共文化设施冲突管理模型

为了识别和研究公共文化设施管理中存在的矛盾冲突,把TRIZ创新工具和公理设计理论相结合,利用独立公理分解公众需求和现实约束之间的矛盾,再使用基于公共文化设施技术参数的TRIZ工具寻找解集,依据信息公理对可选方案进行评价筛选,有效解决了天津文化中心美术馆空置率高、图书馆空间利用率低等实际问题。该方法有效弥补了TRIZ理论在寻找最优解时低效的缺陷,为公共文化设施冲突管理提供了新的思路。     

Optimal concurrent product design and process planning based on the requirements of individual customers in one-of-a-kind production

One-of-a-kind production is a new manufacturing paradigm for producing customised products based on the requirements of individual customers while maintaining the quality and efficiency of mass production. This research addresses the issues in optimal concurrent product design and process planning based on the requirements of individual customers. In this work, a hybrid AND-OR graph is developed to model the variations of design configurations/parameters and manufacturing processes/parameters in a generic product family. Since different design configurations and parameters can be created from the same customer requirements, and each design can be further achieved through alternative manufacturing processes and parameters, co-evolutionary genetic programming and numerical optimisation are employed to identify the optimal product design configuration/parameters and manufacturing process/parameters. A case study is introduced to identify the optimal design configuration/parameters and manufacturing process/parameters of custom window products of an industrial company to demonstrate the effectiveness of the developed method.     

Analysis of automated guided vehicle configurations in flexible manufacturing systems

Automated guided vehicle (AGV) systems complement the operation of flexible manufacturing systems (FMS) by providing integrated automated material handling that capitalizes on the system's flexibility. Previous research considering AGV systems for use in FMS installations has focused on complex control strategies to reduce the congestion problem often encountered in these systems. Recently, attention has been given to tandem system configurations that reduce congestion and simplify system control. The present study uses the simulation methodology to compare the performance of three AGV configurations under a variety of experimental conditions. The results indicate that system size, load/unload time, and machine failure rate factors have significant impacts on the operation of the systems considered. In general, with respect to due date performance, it is recommended to use the traditional configuration in small systems while using the tandem/loop configuration in larger systems. Furthermore, it is shown that the addition of the loop to the tandem configuration mitigates the sensitivity of the tandem configuration to the load/unload time factor as well as significantly improving its performance under high load/unload times. Thus, if tandem configuration is desired to reduce congestion and simplify system control, investments must be made to directly reduce the load/unload times or to construct a loop to avoid the load/unload time penalty.     

PRODUCTION PLANNING DECISIONS IN FLEXIBLE MANUFACTURING SYSTEMS WITH RANDOM MATERIAL FLOWS

In this paper, we consider the FMS planning problem of determining optimal machine workload assignments in order to rninimize mean part flow time. We decompose this problem into the subproblems of first forming machine groups and next assigning operations to these groups. Three types of grouping configurations—no grouping, partial grouping and total grouping—are considered. In both no grouping and partial grouping, each machine is tooled differently. While each operation is assigned to only one machine in no grouping, partial grouping permits multiple operation assignments. On the other hand, total grouping partitions the machines into groups of identically-tooled machines; each machine within a group is capable of performing the same set of operations. Within this grouping framework, we consider three machine loading objectives—minimizing the total deviation from the optimal group utilization levels, minimizing part travel and maximizing routing flexibility, for generating a variety of system configurations.

A queueing network model of an FMS is used to determine the optimal configurations and machine workload assignments for the no grouping and total grouping cases. It is shown that under total grouping, the configuration of M machines into G groups that minimizes flow time is one in which the sizes of the machine groups are maximally unbalanced and the workload per machine in the larger groups is higher. This extends previous results on the optimality of unbalancing both machine group sizes and machine workload to the mean flow time criterion.

A simulation experiment is next conducted to evaluate the alternative machine configurations to understand how their relative performance depends upon the underlying system characteristics, such as system utilization level and variation among operation processing times. We also investigate the robustness of these configurations against disruptions, such as machine unreliability and variation in processing batch sizes. While different configurations minimize mean flow time under different parameter values, partial grouping with state-dependent part routing performs well across a wide range of these values. Experimental results also show that the impact of disruptions can be reduced by several means, such as aggregating operations of a part to be performed at the same machine, in addition to providing routing flexibility.     

A simulated annealing algorithm based on a closed loop layout for facility layout design in flexible manufacturing systems

Facility layout design problems in flexible manufacturing systems (FMS) differ from traditional facility design problems and are more difficult to solve because there are more constraints that must be considered (i.e., cell shape, cell orientation, pick-up and drop-off point positions). The focus of this paper is on the closed loop type layout, which is based on a predetermined layout pattern. This layout pattern is commonly found in manufacturing settings since it requires a simplified material handling system configuration and since it facilitates a modular and expandable layout structure. The open-field type layout problem, where there is no predetermined layout pattern, may potentially have a more efficient configuration, since there are fewer restrictions. However, this problem is more difficult to solve and may result in configurations that are not desirable due to the lack of structure or modularity. The procedure developed in this paper improves the efficiency of the closed loop configuration by changing the rectangular shape of the loop to different sizes. In many cases, the resulting closed loop layout proves to be as efficient as the open field layout. A simulated annealing procedure (SA-CL) is used to search for the configuration that minimizes the total material handling costs. A comparison of the results with existing methods indicates that, based on solution quality and computational time, the SA-CL offers a favourable alternative for efficient layout design.     

Optimizing the configuration of a keyboard assembly cell

This paper describes how the configuration of a three station serial keyboard assembly cell can be optimized using a combination of discrete event simulation modelling and experimental design techniques. The investigation is based on a discrete event simulation model written in ARENATM. Optimum buffer sizes and number of pallets are initially determined by factorial design to identify the most significant factors affecting the throughput of the cell. Response surface methodology is then used to determine the optimal settings. The paper illustrates the methodology of using a combination of discrete event simulation modelling and experimental design techniques to design the optimal configuration of serial assembly cells and similar configurations in the manufacturing environment.     

Computer-based FMS facilities design tool

FMS layout design is a complex process, involving a large number of alternatives, which contributes generously to the usual two-year FMS planning lead time. The need for a comprehensive, yet easy-to-use methodology or tool which can reduce this large number of alternatives to a more reasonable figure has motivated this research. A survey of existing FMSs was undertaken with the intention of identifying some of the more common (dominant) types of layouts, and to develop, if possible, a methodology for the selection of such layouts. However, almost every FMS was found to have a unique layout. For a given FMS under consideration, the capabilities with respect to the parts which can be manufactured is essentially given. The determining features of the resultant design of the FMS, therefore, are primarily based upon the design of the material handling system which integrates the FMS. However, as the number of machines in a FMS increase, the number of part sequences and alternate configurations increase at a dramatic rate. To assist in the preliminary design process, an interactive computer-based program has been developed to aid the search for non-inferior layouts to suit the exact part sequence needs of each FMS. Six criteria-three related to the distances parts travel during manufacturing and three related to the capital costs of the FMS-are provided to assist the user in selecting an appropriate arrangement. The program is described and its use is demonstrated in developing improved arrangements over an example FMS which was published in the literature. Although the reader is cautioned that the results were developed using only static measures, the results do indicate that significantly improved designs are possible using the proposed methodology     

A hybrid methodology for enhancing reliability of large systems in conceptual design and its application to the design of a multiphase flow station

This paper presents a hybrid methodology for conceptual design of large systems with the goal of enhancing system reliability. It integrates the features of several design methodologies and maintenance planning concepts with the traditional reliability analysis. The methodology considers the temporal quality characteristic “reliability” as the main objective and determines the optimal system design. Key ideas from several design methodologies, namely axiomatic design, robust design, and the theory of inventive problem solving, have been integrated with the functional prioritization framework provided by reliability-centered maintenance. A case study of the conceptual design of a multiphase pumping station for crude oil production is presented. The methodology provides a new design tool for determining system configurations with enhanced reliability taking into account maintenance resources and variability.     

Performance evaluation of flexible manufacturing systems with blocking

Analytical approximations for the performance of flexible manufacturing systems (FMS) with blocking of machines due to limited local buffers are presented. The approximations are based on a detailed analysis of FMS configurations used in industry. The method proposed uses informations generated by applying the classical closed queueing network (CQN) model to the FMS. The approximations developed are tested against simulation models for a wide variety of FMS configurations. The results presented show that the approximations are very good.     

Design of an FMS decision support system

Flexible manufacturing system (FMS) is an integrated system consisting of computer numerical control machine tools and automated material handling system controlled by an overall control computer system. The FMS design is broken down into strategic, tactical and operational level designs. This research is concerned with the development of a decision support system for the design of FMS (FMSDDS. Simulation is used as a primary analysis tool, making the DSS capable of solving problems at all three levels. The decision making ability is provided by a multi-attribute utility model which accounts for both quantitative and qualitative factors that affect a decision. The FMSDSS is implemented using three routines: input, analysis, and output. The input routine helps the user to select feasible FMS configurations interactively. The analysis routine consists of a generalized FMS simulation model. This routine analyses the FMS alternatives selected and provides the information required for the output analysis. The qualitative and quantitative measures of performance that have to be considered for decision making are handled by the output routine. It also combines performance measures of different units such as time and cost. The DSS is modular and hence future enhancements can be readily added.     

Flexibility trade-offs in a random flexible manufacturing system: A simulation study

Flexible manufacturing systems (FMSs) are allowing firms to take advantage of diversified, low volume production of products with short life-cycles. The flexibility provided by an FMS improves the ability of a system to respond to change. Several types of manufacturing flexibility (M F) have been identified in the literature. Ideally, it is desirable to provide an FMS with all types of flexibility. However, there is a general consensus on the discordant nature of some of the flexibilities. This makes it imperative for management to recognize which flexibilities it deems critical to the manufacturing strategy of the firm. This allows the management to trade-off some of the less important flexibilities for the more important ones, as the need arises.

This study is an attempt toward an empirical examination of the flexibility trade-offs in an FMS. By using computer simulation, we study the flexibility tradeoffs in the stochastic environment of a random FMS. Various configurations of the FMS are simulated under the influence of a variety of loading and dispatching strategies. The results show that there is a trade-off among the various flexibility types under most circumstances. However, some scenarios illustrate that an appropriate combination of the variables like scheduling environment, product variety, and system configuration, can be effective in containing these trade-offs. In other cases, it is seen that the FMS can accommodate more than one flexibility type simultaneously.