摘要:

Cellular manufacturing constitutes a key element of contemporary approaches to manufacturing such as just-in-time and flexible manufacturing systems. In some settings, it may not be possible to release all members of a family to a cell at the same time due to tooling, level of the in-process inventory and limited machine buffer capacity constraints. When such constraints exist, one approach is to partition each family into subfamilies.

ISSN:0020-7543    

DOI:10.1080/00207549508904820

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Many simulation studies have evaluated sequencing rules and due date assignment methods for scheduling job shops. More recently researchers have studied multistage, or assembly, shops. Typically, due dates have been set by using a fixed multiple of the critical path length. This paper evaluates the effects on shop performance due to using a regression-based approach for setting due dates. The findings show that marked improvement in the performance of dispatching rules can occur when the proposed due date setting procedure is used.

ISSN:0020-7543    

DOI:10.1080/00207549508904821

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents a new approach in the analysis of the natural resting behaviour of a component with a displaced centre of gravity. The methods proposed by Boothroyd et al. (1972), and Boothroyd and Ho (1977), can analyse parts with the centre of gravity located al their geometric centre. Hitherto, the only attempt at analysing pans with displaced centres of gravity entailed the use of empirical factors (Boothroyd et al. 1972). The hypothesis presented herein makes use of the centroid solid angle concept to analyse a component with a displaced centre of gravity. The proposed hypothesis postulates that the probability of a part coming to rest in its various natural resting aspects is directly proportional to the magnitude of the centroid solid angle and inversely proportional to the height of the centre of gravity from that aspect. The experimental results of drop tests conducted on a test specimen corroborate the hypothesis within a maximum deviation of 4%. This is the first successful attempt in the analysis of the natural behaviour of components with displaced centres of gravity that does not rely on empirical factors.

ISSN:0020-7543    

DOI:10.1080/00207549508904822

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper, we develop a new unsupervised learning clustering neural network method for clustering problems in general and for solving machine-part group formation problems in particular. We show that our new approach solves a very challenging problem in the area of machine-part group formation. A review of machine-part group formation methods and unsupervised learning artificial neural network methods is given. We modify the well-known competitive learning algorithm by using the generalized Euclidean distance, and a momentum term in the weight vector updating equations. The cluster structure can be adjusted by changing the coefficients in the generalized Euclidean distance. The algorithm is flexible and applicable to many practical problems. We also develop a neural network clustering system which can be used to cluster a 0-1 matrix into diagonal blocks. The developed neural network clustering system is independent of the initial matrix and gives clear final clustering results which specify the machines and parts in each group. We use the developed neural network clustering system to solve several machine-part group formation problems, in which the machine-part incidence matrix is to be clustered into a diagonal block structure. An algorithm is developed to consider lower and upper bounds on the number of machines for each cell. The computational results are compared with those from the well-known rank order clustering and directive clustering analysis methods.

ISSN:0020-7543    

DOI:10.1080/00207549508904823

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Many researchers have developed ‘standard’ computer-integrated manufacturing architectures in order to reduce the cost associated with software development and maintenance. Since a process plan provides the principal input to a Shop Floor Control System (SFCS), it is necessary to provide the process plan information in a manner suitable for use by the SFCS. However, research in interfacing process planning with different SFCSs has been extremely limited. The reason for this is that proper integration hooks and a generic vision for process plans do not exist. A deterministic description of what process plans are, and how they should be represented is yet to evolve. We describe an information interface between process planning and shop floor control. The functionality, scope, and information content of process plans are discussed in order to provide a clear functional distinction between process and planning and shop floor control. An information architecture for interfacing process plans and SFCSs built. The design of the architecture is focused on how process plans comply with the information requirements of a SFCS. and how to exchange information in real-time basis. Process plans are created on a formal process plan model platform. The SFCS architecture that is considered in this paper is a three-level hierarchical architecture. A detailed description of functional behaviour and information flow for each level of hierarchical SFCS is presented along with some illustrative examples.

ISSN:0020-7543    

DOI:10.1080/00207549508904824

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Although a significant amount of simulation research has been carried out for design and analysis of flexible manufacturing systems (FMS), it does not provide optimal solutions. In this research, we employ two optimum-seeking methods to design and optimize a manufacturing system. The first method is a Taguchi approach, which uses robust design concept to reduce the output variation. The second method is the response surface methodology (RSM), which combines mathematical and statistical techniques to study the geography of the response surface. The results show that throughput of a selected FMS system can be maximized when both methods are employed.

ISSN:0020-7543    

DOI:10.1080/00207549508904825

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A sensing method using an acoustic signal obtained in a relative low frequency range through a solid path for the monitoring of tool wear has been investigated. Such acoustic signals could be in the form of stress waves that are released during a machining process, which can be picked up by a regular ferroelectric microphone. Data analysis was conducted in both time and frequency domains. A clear pattern in such signals corresponding to the tool wear conditions has been identified. Several components in spectra were found in the pattern for indicating sudden changes of tool wear or breakage occurring at major cutting edges. It was also observed that the RMS and variance values of the signals could indicate the specific wear condition of the tool. Therefore, this kind of acoustic signal carries sensitive information about the progress of tool wear and can be implemented on line for monitoring tool wear.

ISSN:0020-7543    

DOI:10.1080/00207549508904826

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Simulation that approximates real-time system response has previously been used to train operators in the use of system controllers. These simulations typically use architectures that are highly specific and tightly coupled to the system hardware. A formalized generic real-time simulation architecture is presented to decouple the simulation and provide a mechanism for implementation and rapid reconfiguration. This architecture distributes the state variables in the system by coupling them with manufacturing process equipment, specifically for the continuous process industries such as chemical, food and pharmaceutical. This design provides a mechanism for rapidly interchanging manufacturing equipment and simulation model components for discrete and continuous simulation, that facilitates operator training.

ISSN:0020-7543    

DOI:10.1080/00207549508904827

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The variety of the currently available component grouping methodologies and algorithms provide a good theoretical basis for implementing GT principles in cellular manufacturing environments. However, the practical application of the grouping approaches can be further enhanced through extensions to the widely used grouping algorithms and the development of criteria for partitioning components into an ‘optimum’ number of groups. Extensions to the fuzzy clustering algorithm and a definition of a new validity measure are proposed in this paper. These are aimed at improving the practical applicability of the fuzzy clustering approach for family formation in cellular manufacturing environments. Component partitioning is based upon assessing the compactness of components within a group and overlapping between the component groups. The developed grouping methodology is experimentally demonstrated using an industrial case study and several well known component grouping examples from the published literature.

ISSN:0020-7543    

DOI:10.1080/00207549508904828

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We construct a multiqueue model of high fidelity for detailed performance evaluation of flexible machine centres. These models permit one to represent part type specific demand, processing, and setup time values, and to obtain part type specific performance figures. We show through numerical examples that variabilities in system parameters can induce paradoxical system behaviour. We also present an enhanced model which concerns a workpiece undergoing several operations at the work centre, and its application to evaluate alternative schedul ing strategies.

ISSN:0020-7543    

DOI:10.1080/00207549508904829

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor