摘要:

Zoning constraints impose co-location of the storage addresses assigned to individual items within the same storage area of a warehouse. The cube-per-order index (COI) rule for assigning items to locations cannot guarantee orderpicking cost minimization when zoning constraints are active. A heuristic procedure is presented for using the COI to generate an initial item assignment followed by an improvement step. The improvement step includes a random search phase followed by a simulated annealing step designed to avoid trapping at local minima. The procedure is illustrated in the context of a sample problem with 100 items stored in a facility with 1600 storage addresses distributed among 25 zones. Computational experimentation aimed at developing approximate guidelines for controlling the improvement step are reported.

ISSN:0020-7543    

DOI:10.1080/00207549508930160

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The aim here is to establish a classification framework to evaluate the currently available uncertainty dampening methods used in reducing scheduling instability in materials requirements planning (MRP) systems. Dampening methods can first be categorized as the local and global dampening methods in terms of the locality of uncertain events to be resolved. In terms of the nature of dampening methods, they can be considered as inventory- or information-orientated dampening methods. Local dampening methods can be farther classified by the ‘type’ of uncertainty (i.e. timing versus quantity) and the level in the bills of materials to which this method can be suitably applied. The major advantages and disadvantages of each method will be identified. Also, the operating conditions within which each method can be applied are discussed before future research directions are suggested.

ISSN:0020-7543    

DOI:10.1080/00207549508930161

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In order to enhance the probability of correct quality diagnosis, it is useful to be able to identify the statistical manner in which the quality signal has changed, i.e. identify change structure. Specifically we wish to distinguish between changes in mean, variance and lag one autocorrelation. Because these change structures yield significant similarities in their corresponding output, a multistage decision tree is necessary. A multistage classification system with a neural network and quadratic discriminant functions is used, where neural network output is ana prioridistribution for the Bayesian quadratic discriminant function. Experimental results show that this multistage decision strategy performs significantly better than its single stage counterpart, with an overall success rate of 84%.

ISSN:0020-7543    

DOI:10.1080/00207549508930162

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This study develops a framework for analysing time-based competition and examines four supply-chain management strategies in make-to-order markets which can lead to cycle-time reduction: cross-functional product design participation, ‘just-in-time’ purchasing systems with suppliers, improved supplier delivery and quality performance, and work-in-process lot size reduction. A structural model and relevant measures were developed to assess the impact of these strategies on time-based competition, and the model was tested using interview data with managers in 40 plants from nine industries. Both just-in-time purchasing and supplier performance were found to have a significant effect on leadtime competitiveness, while cross-functional design and lotsize reduction did not. Several explanations for the lack of significance of the latter two variables were suggested based on qualitative observations and post-hoc analysis. Although the analysis suggests that the greatest progress towards time-based competitiveness can be made in the area of procurement of materials, the study points to the importance of managing the entire supply chain to attain this strategic advantage.

ISSN:0020-7543    

DOI:10.1080/00207549508930163

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents a simulation-based analysis of a service robot operating in a robot-centred FMC, in which the robot is located at the approximate centre of the cell and the machines are arranged in a partial circle around it. The robot's function is to locate and service the parts, which require a series of unloading, moving, and loading operations. The main purpose of the study is to determine the best movement decision for the robot when it becomes free, where multiple products with different but similar operation sequences are processed. The results from the study, based on both statistical and non-statistical analyses, suggest the best policy for the robot movement that holds promise for application to the robot-centred FMC.

ISSN:0020-7543    

DOI:10.1080/00207549508930164

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Design features created by a feature based design system could theoretically be directly sent to machining preparation system. This, however, has not been found and feature modification is still necessary. A feature modification framework is proposed in this paper for bridging the gap between the design features and machining features. Feature modification algorithms were also developed for the foundation of the framework. A prototype system is presented and illustrated by an explanation of how the feature modification concept could function in a real situation.

ISSN:0020-7543    

DOI:10.1080/00207549508930165

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Using simulation, experimental design, and regression analysis, mathematical models are developed here to describe the effect that maintenance policy, machine unreliability, processing time variability, ratio of preventive maintenance time to processing time, ratio of minimal repair time to preventive maintenance time, and production line size have on various measures of performance, namely total production line output and production line variability of the just-in-time production system. The analysis of the data shows that under different situations, different maintenance policies do not have the same effect on the production line performance. The following conclusions were obtained; when the number of production machines is low (five machines or less), and/or when the ratio of minimal repair time to preventive maintenance time is high, maintenance policy III leads to a higher performance than maintenance policy II. Otherwise maintenance policy II, which is more sensitive to the change of the ratio of minimal repair time to preventive maintenance time, leads to a higher performance. The results of the study can be utilized in choosing a maintenance policy as a function of the production process parameters. Once a policy is chosen, the practitioner can select the most important factors to control under that policy in order to minimize the machine idle time, maximize the production process reliability, improve productivity, and therefore increase the production line performance.

ISSN:0020-7543    

DOI:10.1080/00207549508930166

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor