摘要:

Forecast accuracy is a major challenge for manufacturing organizations. Forecast error can be a direct cause of stockouts, inventory growth and/or costly changes in the mast schedule. Despite the considerable time and effort expended on forecasting, forecasts are still very inaccurate. In summation, forecast inaccuracy is expensive and the confusion and frustration resulting from it is extensive. This confusion has led some advisers to recommend the elimination of forecasting altogether (Goddard 1989). Others, however, emphasize the need for forecast accuracy in order to permit an appropriate and effective response by the manufacturing organization. The importance of a relatively accurate forecast to manufacturing performance calls for understanding of the factors which affect forecast accuracy. Many researchers have analysed how the use of various techniques affects forecast accuracy. These studies focus on understanding of the technical accuracy of various methods: they do not suggest how manufacturers might work to improve forecast accuracy. Most of this research as focused on the forecast developers rather than the users of the forecasts. This study examines the effects of institutional factors on forecast accuracy from the perspective of the manufacturing executive. This study investigates the effects of institutional factors on forecast error. The questions it addressed include: Who should be involved in forecast preparation? How important is forecast error measurement for future accuracy? What should the primary purpose of the forecast be? The data was obtained from a sample of manufacturing professionals in the UK, reporting information about practice within their manufacturing organizations. Statistical results from this study suggest that firms with a culture supportive of new technology have lower forecast errors. Multiple functional involvement in forecast development does not improve forecast accuracy. Top management (president/managing director) involvement in forecast development reduces forecast accuracy. Forecasts are best developed for sales planning and then distributed to other functions for their use. The statistical results suggest quantitative techniques have no effect on forecast accuracy. Single values of the forecast and forecast error measurements lead to improved forecasts. And finally, organizations respond to forecast inaccuracy by frequent modification.

ISSN:0020-7543    

DOI:10.1080/00207549508904855

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An economic approach to the control of continuously monitored production processes is detailed. A simple tabular procedure for designing a control chart for the mean of such processes is introduced and discussed. A new approach towards dealing with high false alarm rates is developed.

ISSN:0020-7543    

DOI:10.1080/00207549508904856

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Conventional line balancing deals with the processing of large batches with fixed operation times, such that the throughputrateis maximized. Solution procedures are predicted upon equal allocation of work to stations along the line. When batches are small, operation times exhibit learning effects, and not all stations are employed at the beginning and end of the batch process. Thus a totally different approach must be taken. The objective is to minimize the throughputtimeof a finite batch. In this article we show that optimal solutions are based upon allocation of work to stations in decreasing proportions, so that more work is allocated to the first station than to the last. A number of theorems are presented to support and illustrate the decreasing proportions principle; and two heuristics, one based upon simplified linear programming model, and the other on the geometric mean ratio of successive task times, are developed to find task-to-station allocations that yield minimum throughput times for the small-batch problem. A comparison with equal allocation of work (under learning conditions) is made, and the properties of the task allocations and resultant schedules are discussed.

ISSN:0020-7543    

DOI:10.1080/00207549508904857

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Designing mechanical systems for efficient disassembly improves their maintainability. Issues related to design disassembly for maintainability analysis of an evolving mechanical system design are discussed. Procedures and methodologies for the identification of disassembly sequence, animation of human technicians in performing the disassembly sequence, tool selection, time and cost analysis, and human factors analysis of the disassembly sequence are presented. Their software implementation in a maintainability analysis workspace is described and illustrated using a maintenance task example.

ISSN:0020-7543    

DOI:10.1080/00207549508904858

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper investigates a commonly omitted aspect of Automated Guided Vehicle (AGV) simulation—battery modelling. Battery usage is frequently overlooked in simulation for a variety of reasons. First, it is incorrectly believed to have minimal impact on system operation. Second, many analysts do not have an understanding of how batteries power AGVs. Third, battery analysis requires additional input information and varies for different AGV vendors. This paper contains several methods that can be used to account for the impact of various battery usage schemes on AGV simulations. These methods range from general philosophies to detailed model-specific coding examples.

ISSN:0020-7543    

DOI:10.1080/00207549508904859

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this article, exploratory factor analysis was applied to a set of 50 quality management practices, synthesized from Deming's philosophy, to determine whether they can be summarized or explained by a smaller number of meaningful factors. Eight meaningful factors were extracted that accounted for 53.6% of the total variation among Deming's 50 quality management practices. Industry practitioners can use these factors in concert with other critical quality management practices to help them in their TQM initiatives. Researchers can also use these factors to build structural models linking such factors to various organizational performance measures.

ISSN:0020-7543    

DOI:10.1080/00207549508904860

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This empirical study utilized concrete financial/accounting data concerning measures of organizational performance, as reported in Standard & Poors Compustat, to examine the impact of Just-in-Time production on organizational performance. Matching groups of JIT implementing and non-implementing firms were formed from a cross sectional survey, and a comparative analysis was made for the two groups. The result of the study shows that JIT firms have not achieved better organizational performance in terms of sales in $/employee, operating profit margin, and return on investment than non-JIT firms; but achieved better performances in terms of finished goods inventory turnover, raw materials inventory turnover, and work in process inventory turnover. In addition, this study ascertained that JIT firms have achieved much better performance in terms of quality and flexibility than non-JIT firms.

ISSN:0020-7543    

DOI:10.1080/00207549508904861

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

CAD-directed assembly sequence planning is an essential component of automated robotic assembly task planning. Many research attempts have been made in the past to integrate computer-aided design (CAD) and robot task planning to increase the efficiency and effectiveness of robotic assembly automation. This paper presents a graph-based heuristic approach for automatic generation of assembly sequences from a feature-based data base. A feature-based representation is used to model product assembly. The automatic assembly sequence planning system utilizes four major stages to generate assembly sequences without any user intervention:(1) creates connective graphs based on the product feature representation; (2) decomposes an assembly into sub-groups using the connective graphs; (3) generates the disassembly sequence for each sub-group formed at stage 2; and (4) merges the disassembly sequences of the sub-groups into a complete disassembly sequence, and converts the disassembly sequence into the final assembly sequence. The assembly planning system associated with the feature-based product model has been implemented in Smalltalk-an object-oriented programming language. Several examples are included to illustrate the approach and the heuristic algorithms. The results show that the approach can be used to automatically generate assembly sequences for robot assembly task planning directly from the feature-based database.

ISSN:0020-7543    

DOI:10.1080/00207549508904862

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Cyclic data occur relatively frequently in manufacturing processes. Traditional approaches to detecting cyclic behaviour are mostly statistics-based, such as spectral analysis and time series analysis. In this paper, a special-purpose cyclic pattern recognition system applying neural networks is proposed. The system consists of multiple multilayer perceptrons with each perceptron dealing with cycles of a certain period. Thus, it incapable of identifying cycles of various periods. Multiple perceptrons may work concurrently, but a final decision is made through a unified decision rule. This type of special-purpose system is recommended when certain behaviour is known to exhibit more frequently in a given manufacturing process. Under the circumstances, an automatic assignable-cause interpretation system, which contains a special-purpose pattern recognition system as a core component, may be tuned to be more sensitive to this particular type of behaviour. Simulation indicates that a Special-purpose cyclic pattern recognizer performs comparably to a general-purpose pattern recognizer in detecting less noise-contaminated cycles, but performs superiorly in detecting cycles of higher noise and cycles of higher amplitudes.

ISSN:0020-7543    

DOI:10.1080/00207549508904863

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper addresses an increasingly important aspect of product design and its relationship to life-cycle costing: disassembly for material recovery opportunities (MRO). MRO is defined as an opportunity to reclaim post-consumer products for recycling, remanufacturing and re-use. The authors have developed a methodology which can be used to identify and assess cost-effective characteristics of disassembly for the recovery of products. The central focus of this paper is aimed at improving the efficiency of the disassembly planning process and generating an optimal disassembly sequence. Four criteria are established to optimize the generation of the disassembly sequence: (1) material compatibility, (2) clustering for disposal, (3) concurrent disassembly operations, and (4( maximizing yield. In this paper we define the ‘disassemblability’ of a product as the ability to optimize the design and disassembly process for removal of specific pans or materials in a manner which will minimize costs. Steps have been taken to incorporate this methodology within a life-cycle analysis software tool (EDIT) to be used at the early concept stage of product design.

ISSN:0020-7543    

DOI:10.1080/00207549508904864

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor