摘要:

In this paper, we propose a methodology to optimally allocate the repair rates in transfer lines, which requires estimating the gradient vector of the output rate with respect to repair rates. Partial derivatives can be obtained exactly in the case of two-machine lines. The gradient estimation method for longer lines uses this result together with an algorithm developed to approximate the performance measures of the line. The method developed is used in an optimization context to find the optimal repair rate vector to maximize the throughput given a constraint on the sum of the individual repair rates. The results obtained by this method is compared to those obtained using the finite difference method in gradient estimation.

ISSN:0740-817X    

DOI:10.1080/07408179808966541

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this study, we are concerned with finding the minimum-total-buffer allocation for a desired throughput in production lines with phase-type processing times. We have implemented a dynamic programming algorithm that uses a decomposition method to approximate the system throughput at every stage. We provide numerical examples to show the buffer allocation and compare the corresponding simulated throughput and its bounds with the desired throughput.

ISSN:0740-817X    

DOI:10.1080/07408179808966542

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Current manufacturing planning software systems, such as computer aided process planning (CAPP) systems, are general and in a closed form. It is very difficult to modify these systems to respond to a user's dynamically changing needs. These systems are no longer suitable for agile manufacturing. This paper presents research aimed at developing a novel architecture for the rapid development of CAPP systems. The architecture supports the construction of CAPP systems from prepackaged, plug-compatible software components. Specifications of the architecture and its building blocks are defined. Several important issues in architecture implementation are discussed, and an experimental system is illustrated. Finally, an Internet-based distributed CAPP system architecture is presented as a preview of next generation CAPP system development.

ISSN:0740-817X    

DOI:10.1080/07408179808966543

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A wide range of electromechanical devices are made up of a variety of miniature high precision mechanical components machined to very tight dimensional tolerances, geometric accuracy and surface finish. The predominant feature in producing these components is that the dimensional tolerances, geometric accuracy and surface finish must be achieved simultaneously as it is difficult to improve any of these features discretely in subsequent machining/finishing operations without affecting the others. While no firm or universal rules can be laid down to produce these components to exacting tolerances, the process design and engineering play the most important role in interlinking the tolerance levels which can make the difference between success or failure. This paper deals with some of the critical aspects of the process design and engineering of particular examples of high precision miniature mechanical components used in inertial devices.

ISSN:0740-817X    

DOI:10.1080/07408179808966544

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A numerical scheme for improving the drawability in the deep drawing of square shells by blank design optimization is presented. The numerical scheme is formulated as an optimization problem whose objective is to maximize the drawability, subject to the constraint that fracture failure and draw-in failure do not occur. Appropriate blank design parameters are used as the design variables of the formulation. To enable the numerical scheme to work models predicting the onset of fracture failure and draw-in failure are required. Numerical models simulating the onset of these failures under the given process conditions are thus discussed. Optimal designs for three cases are then presented. Finally, by considering both the drawability and the non-uniformity of the final flange profile it is shown that the circular profile can be considered to be the optimal blank shape for square cup drawing.

ISSN:0740-817X    

DOI:10.1080/07408179808966545

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new class of parametric and modular flexible tools is proposed to improve the setup times of assembly lines. The methodology is especially effective in dealing with problems of mass customization. In addition to improvements in the setup time, the methodology, MPATS (modular, parametric assembly tool sets) has other potential advantages such as lower tooling costs as well as faster tooling lead times compared to conventional assembly systems utilizing custom made tools. To demonstrate the feasibility of the methodology, a prototype tool set is designed and presented in this paper. The prototype tool set focuses on the most common of feeding and orienting tools: vibratory bowl feeders.

ISSN:0740-817X    

DOI:10.1080/07408179808966546

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Efforts taken by manufacturing companies to meet the increasing demand for product variety often lead to a proliferation of subassemblies. In this paper, we show that careful design of the product assembly sequence helps to create generic subassemblies that reduce subassembly proliferation and the cost of offering product variety. This approach of designing the assembly sequence to maximize the benefit from commonality of components and assembly operations, referred to as product family-based assembly sequence design, is the focus of this paper. After introducing the approach with a simple example, we formalize the notion of generic subassemblies, and present an algorithmic approach to identify generic subassemblies. We illustrate the algorithm with an example from the literature of an assembly from industry, and provide computational test results of the complexity and benefits of product family-based assembly sequence design.

ISSN:0740-817X    

DOI:10.1080/07408179808966547

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper focuses on facility layout problems with shape constraints. A heuristic algorithm is developed for the problems with the objective of minimizing the sum of rectilinear distances weighted by flow amounts between the facilities. The suggested algorithm is a simulated annealing algorithm in which a solution is encoded as a matrix that has information about relative locations of the facilities on the floor. A block layout is constructed by partitioning the floor into a set of rectangular blocks according to the information while satisfying the areas of the facilities. In this paper, three methods are suggested for the partitioning procedure and they are employed in the simulated annealing algorithm. The results of computational experiments show that the proposed algorithm performs better than two existing algorithms.

ISSN:0740-817X    

DOI:10.1080/07408179808966548

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The design paradigm called virtual prototyping (VP) is important because of the need to manufacture products in a short period of time and in a cost effective manner. By replacing the building of physical prototypes for testing various design issues such as usability, life-cycle analysis, functionality and so on with so called “virtual models” on a computer and analyzing them, virtual prototyping is achieved. One of the design issues that has become increasingly important is the “design-for-disassembly (DFD)” paradigm. A well designed product that is easy to disassemble has the obvious advantages when it needs to be taken apart for service or end-of-life recycling. Therefore a design tool that can tie the DFD issues into a virtual prototyping system is of considerable interest. This paper attempts to address this particular issue in the virtual prototyping area: DFD as applied to VP. This paper presents an overview of a detailed DFD method. An algorithm that can be readily tied into a computer aided design system, therefore also useful for virtual prototyping, is discussed. Some implementation issues and an evaluation of the effectiveness of the DFD method currently employed are explained. Even though this research is still in its early stages, the paper presents a general framework of DFD methodology and its potential to be used as a virtual prototyping tool.

ISSN:0740-817X    

DOI:10.1080/07408179808966549

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We obtain an approximate expression for the mean waiting time of an open tandem queueing network with population constraint, constant service times and an arbitrary arrival process.

ISSN:0740-817X    

DOI:10.1080/07408179808966550

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor