A model for line capacity design for PWB assembly systems

In a multi-product, flexible manufacturing environment, line capacity of printed wiring board (PWB) assembly systems may need to be designed at the beginning of each aggregate planning period because of demand fluctuation over multiple periods. A model of line capacity design problem and production planning at the aggregate level is developed, in which production and subcontracting are assumed to be two options for a firm to meet market demand. The model presented is a large-scale integer programming problem, it cannot be solved by using standard- or mixed-integer programming codes. Under the assumption that each machine line is dedicated to produce one product family, the model can be decomposed as a relatively small subproblem, and each subproblem has good properties by which the subproblems can be further simplified and decomposed over multiple planning periods. As the result, the original large-scale two-stage integer programming problem can be approximately solved by solving a series of small-scale mixed-integer programming, which can be implemented on a workstation or a PC. Computational studies show that the solution method is developed which gives near-optimal solutions with much less computational effort.     

Allocation of maintenance resources in mixed model assembly systems

Mixed-model assembly systems (MMASs) have been well recognized for their ability to handle product variety for mass customization. With multiple products to produce, the prioritization of maintenance work-order becomes more crucial and challenging. This paper develops a quantitative method to systematically determine maintenance work-order priorities in an MMAS using on-line production information. The effect of product mix ratio on maintenance decisions is studied in detail. Based on the proposed approach, one can search for an optimal maintenance plan that will lead to improved productivity within the optimization horizon.     

A SysML-based methodology for mechatronic systems architectural design

Mechatronic systems are characterized by the synergic interaction between their components from different technological domains. These interactions enable the system to achieve more functionalities than the sum of the functionalities of its components considered independently. Traditional design approaches are no longer adequate and there is a need for new synergic and multidisciplinary design approaches with close cooperation between specialists from different disciplines.SysML is a general purpose multi-view language for systems modeling and is identified as a support to this work.In this paper, a SysML-based methodology is proposed. This methodology consists of two phases: a black box analysis with an external point of view that provides a comprehensive and consistent set requirements, and a white box analysis that progressively leads to the internal architecture and behavior of the system.     

Resource monitors: A design methodology for operating systems

Resource manager objects are the operating system entities that manage computer system resources. In this paper we extend Hoare's and Brinch Hansen's monitor concept, and introduce a resource monitor language construct that represents a resource manager object. Resource monitors provide requesting processes with implicit synchronization, and do not require separate processes to perform the resource access operations. The resource monitor construct is compared to current language constructs used to structure operating system software. For this purpose we use an evaluation methodology that combines software complexity measurements with program performance measurements. The evaluation itself is carried out in a Concurrent Pascal-like programming environment. The current language constructs have a software complexity that is larger by 37 to 219 per cent over the resource monitor's complexity. The run-time synchronization overhead of programs that use current language constructs is 1.43 to 2.75 times higher than the overhead of programs that use a resource monitor.     

A methodology to design virtual cellular manufacturing systems

Virtual Cellular Manufacturing System is a new type of cellular system that emerged as a promising alternative for designing cells in real time. The problem is complex and time consuming NP-hard problem in its nature. This study was conducted to design virtual cells that maximizes similarity index and minimizes lead time. A mathematical model and an effective solution procedure were proposed. Several randomly generated data sets were used along a case study to test the performance of the proposed approach. The effects of inherent parameters of virtual systems were investigated and compared by using particular performance measures.     

RMS design methodology for automotive framing systems BIW

Today, markets increasingly require more customized products, with shorter life cycles. In response, manufacturing systems have evolved from mass production techniques, through flexible automation and mass customization, to produce at mass production costs. Manufacturing facilities must incorporate more flexibility and intelligence, evolving toward reconfigurable manufacturing systems (RMS). RMS are amid to posses such flexibility and responsiveness and said to be the next generation of world class systems. RMS are designed for rapid change in structure and for a quickly adjustable production capacity. This paper proposes a new methodology (high level process) of framework using flexible and reconfigurable manufacturing systems principles for automotive framing systems as well as to provide a guideline to support the structure of different stages of the design methodology. The proposed methodology is presented through a case study using data based on actual production systems of three different styles; (process and design data) which supports the hypothesis of the research.     

Category theory-based collaborative design methodology for mechatronic systems

Recent advances in companies are characterized by highly dynamic, knowledge-intensive and collaborative process. This has become primary concern for mechatronic systems since they involve multiple disciplines and knowledge. This requires a close exchange in order to share knowledge between the different design teams. The first step in knowledge sharing is to identify the most important knowledge that need to be capitalized, which we call “crucial knowledge”. During this exchange, heterogeneous knowledge and modelling languages are involved in the design process, which can lead to conflicts. Hence, the challenge is to continuously capture and handle such conflicts between expert models. Thus, the focus of this paper is to propose a new collaborative design model suitable for mechatronic concurrent design. Our contribution lies in identifying crucial knowledge and resolving conflicts in a formal way in order to ensure efficient collaboration. Our methodology called Category Theory-based Collaborative Design (CaTCoD) is described with its associated meta-model. A demonstrator is also used to validate the proposed methodology using an example from the aeronautic field.     

采样系统的H∞混合灵敏度设计

由于流行的提升法实际上并不适用于采样控制系统的H∞最优设计,本文提出一种基于频率响应概念的新的离散化H∞设计方法.文中结合S/T混合灵敏度问题,分析说明了这种离散化方法,并从鲁棒稳定性和性能两方面对设计结果进行了定量的验证.文中还与提升法的H∞设计进行了对比,指出由于提升变换需要进行回路转移,改变了标准H∞问题中的结构关系,因而设计结果并不理想.     

A design methodology for structural and control systems of a prosthetic leg

A design methodology is proposed to optimize a prosthetic leg considering the structural and control aspects. Previous studies mainly focused on each of a structural design problem or a control problem. The structural design variables of a prosthetic leg are determined in a structural design problem while the trajectory tracking based on the human gait cycle is found to be a control problem. The two problems have been separately solved. However, they should be simultaneously considered to obtain a better design. Then the problem would be nonlinear dynamic response optimization of structural and control systems. An optimization method was recently developed for a linear system of structural and control design problems using the equivalent static loads (ESLs). In this study, a design methodology for the prosthetic leg is presented by expanding the equivalent static loads method (ESLM) to nonlinear dynamic systems. A simple example is solved to validate the proposed methodology, and then a prosthetic leg is optimized to reduce the weight and energy consumption.     

A methodology for design, test, and evaluation of real-time systems

This article presents a methodology that is suitable for use as part of either a prototyping approach or a component-reuse approach. This methodology integrates modeling and simulation as well as developmental and operational testing over the life cycle. The type of systems or components we address operate in real time. Designing and testing real-time systems involves the use of multiple processors and communication links. The real-time system itself can run on a single processor or multiple processors. Even when the system runs on a single processor, the test and evaluation environment uses multiple processors. If the evaluation environment were hosted on the system processor, system performance would be affected. For ease of exposition, we focus on sensor systems; the methodology described is widely applicable to other kinds of systems. We use two examples (a space-borne navigation system and an interferometer system) to describe the methodology and show how it can be used. This methodology can reduce project costs and shorten schedules because it requires performance evaluation and integration testing early, when problems are generally easier and less costly to correct     

The methodology for design of effective computer-integrated manufacturing systems

This paper the combines group technology and the simulation approach to the design of an effective material flow system in production processes of a discrete nature. The GT method shows how to find operational groups using a classification system, and how to design GT cells to achieve their maximal effectiveness. Dynamic modelling and simulation of the designed system are emphasized as the tools for checking the behavior of the designed structure and measuring its effectiveness. An example of an application of the suggested approach in the case of a textile machine factory is discussed.     

A structured modeling based methodology to design decision support systems

Many Decision Support Systems (DSS) support the decision making process through the use of mathematical models and data. DSS design involves modeling data as well as mathematical relationships in a domain. The process of model formulation and subsequent integration of model with data in a DSS is a complex and ill-structured process. This paper proposes a methodology based on Structured Modeling (SM), originally introduced by Geoffrion together with the modeling language SML, to model and design the DSS. The methodology includes rigorous and step by step procedures to design and integrate data and modelbases. The main contribution of our approach lies in the integration of research in database design, and mathematical model formulation within the structured modeling framework. The resultant procedures can be easily automated and taught to students in DSS courses. The motivation for our research stemmed from our constant frustrations in teaching DSS courses over the last five years. In the last two years, when we used our methodology, the performance of the students improved significantly. The average score in the DSS project went up to 85 from 60. Our positive experience in using our methodology in classes over the past two years suggests that the methodology imposes structure into the analysis of decision problems, and as a result students produce better DSS designs for classroom cases.     

加工与装配车间集成调度的多目标优化模型

为解决一类具有多品种混流加工作业车间和流水装配车间的两阶段集成调度优化问题,以加工线最大完工时间和产品总生产完工时间最小为目标,并考虑通过对零部件加工提前完工和装配线等待施加惩罚系数,以保证缓冲区在制品库存和装配过程均匀连续生产,建立加工与装配车间集成调度的多目标优化模型,充分利用加工和装配工序之间存在的并行性,合理确定零部件加工顺序和装配排序,以缩短产品生产周期,降低生产成本,提高生产设备利用率;同时针对所建立的模型,设计遗传算法进行求解,采用零件加工和产品装配的两段实数编码,以稳态复制对群体进行选择,对交叉和变异算子进行设计,以保证新个体满足工序先后约束的可行性,避免了非可行解的混入影响优化结果;最后通过实例验证所建调度模型的可行性和算法的有效性。     

Genetic algorithms for sequencing problems in mixed model assembly lines

Mixed model assembly lines are a type of production line where a variety of product models similar in product characteristics are assembled. The effective utilisation of these lines requires that a schedule for assembling the different products be determined. In this paper, the performance of genetic algorithms for sequencing problems in mixed model assembly lines is investigated. The problem first considered is a comparison between a existing heuristic and the proposed genetic algorithm to get the constant usage of every part used by the line considering variation at multi levels (Number of levels fixed as four. level 1—product, level 2—subassembly, level 3—component, level 4—raw-materials) for various test-bed problems. The algorithms proposed by Miltenburg and Sinnamon hereafter referred to as MS 1992 [IIE Trans. 24 (1992) 121] and the proposed genetic algorithm (GA) applied to mixed model assembly line are compared. Results of evaluation indicate that the GA performs better over MS1992 on 25 of the 40 problems investigated.

The other problem solved is a multiple objective sequencing problem in mixed model assembly lines. Three practically important objectives are minimizing total utility work keeping a constant rate of part-usage, minimizing the variability in parts usage and minimizing total setup cost. In this paper, the performance of the selection mechanisms, the Pareto stratum-niche cubicle and the selection based on scalar fitness function value are compared with respect to the objective of minimising variation in part-usage, minimising total utility work and minimising the setup cost. Results of evaluation indicate that the genetic algorithm that uses the Pareto stratum-niche cubicle performs better than the genetic algorithm with the other selection mechanisms.     

ACTEN: A conceptual model for security systems design

This paper describes ACTEN, a conceptual model for the design of security systems. Security information is represented by action-entity pairs and organized into a framework composed of graphs and tables. The rules permitting the building and management of this framework are introduced.The model describes both static and dynamic aspects of the security system; in fact, it shows the access modalities between objects in the system and the evolution of such modalities due to grant and revocation of rights within the security system.ACTEN also allows the identification of the authority and protection level of each component of the system. The tools for this analysis are introduced and an example is given.     

A design methodology for data-parallel applications

A methodology for the design and development of data-parallel applications and components is presented. Data-parallelism is a well understood form of parallel computation, yet developing simple applications can involve substantial efforts to express the problem in low level notations. We describe a process of software development for data-parallel applications starting from high level specifications, generating repeated refinements of designs to match different architectural models and performance constraints, enabling a development activity with cost benefit analysis. Primary issues are algorithm choice, correctness, and efficiency, followed by data decomposition, load balancing, and message passing coordination. Development of a data-parallel multitarget tracking application is used as a case study, showing the progression from high to low level refinements. We conclude by describing tool support for the process     

A methodology for evolutionary product design

this paper describes a function-based approach for conceptual design support in the context of evolutionary product development. The main objective is to improve a designers productivity by the effective reuse of existing design information in design alternative identification, evaluation, and modification. An integrated evolutionary design methodology, EPD, is presented. The proposed methodology divides the whole process into three inter-related phases: information recovery, information management, and information reuse. The detailed steps in each phase are elaborated, and various techniques are employed to improve information reuse efficiency. A case study on commercial electrostatic air cleaner was used to illustrate the whole process of product evolutionary design. The proposed methodology will have a positive impact on the future development of the conceptual design support system.     

Sequencing in mixed model assembly lines: A genetic algorithm approach

The mixed model assembly lines are becoming increasingly popular in a wide area of industries. We consider the sequencing problem in mixed model assembly lines, which is critical for efficient utilization of the lines. We extend standard formulation of the problem to allow a hybrid assembly line, in which closed and open workstations are intermixed, and sequence-dependent setup time. A new approach using an artificial intelligence search technique, called genetic algorithm, is proposed. A genetic representation suitable for the problem is investigated, and genetic control parameters that yield good results are empirically found. A new genetic operator, Immediate Successor Relation Crossover (ISRX), is introduced and several existing ones are modified. An extensive experiment is carried out to determine a proper choice of the genetic operators. The performance of the genetic algorithm is compared with those of heuristic algorithm and of branch-and-bound method. The results show that our algorithm greatly reduces the computation time and its solution is very close to the optimal solution. We have identified the ISRX operator to play a significant role in improving the performance.     

Analysis and design of networked control systems using the additive noise model methodology

Networked Control has emerged in recent years as a new and exciting area in systems science. The topic has many potential applications in diverse areas ranging from control of microrobots to biological and economic systems. The supporting theory is very rich and combines aspects of control, signal processing, telecommunications, and information theory. In this paper, we give a partial overview of recent developments in Networked Control with an emphasis on the additive noise model methodology. We also point to several open problems in this emerging area. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society