摘要:

A novel method of analysing serial production lines has been developed. This method lets one compute the throughput rate of lines composed of dissimilar stations, as well as for a large class of distributions of station service times. Several distribution-free models of 3-station lines are presented. These models are used to compute the throughput rate of unbalanced lines in which the sum of the mean service times is constant. Results are shown as contour plots of constant throughput rate. The bowl phenomenon is reviewed in the light of this capacity to model with a greater degree of freedom.

ISSN:0020-7543    

DOI:10.1080/00207548708919831

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

One of the resource utilization problems is the location of two-dimensional patterns onto stock sheets with finite dimensions. Stock sheets, in this respect, are depletable resources to be used and the remaining material which is known as the scrap (or trim loss) cannot usually be used later for allocating patterns. Thus, a decrease in the amount of scrap yields a decrease in the raw material cost. In the solution of the problem, usually templates of the patterns to be cut are placed on a stock sheet and then moved until an arrangement is obtained that appears to yield a minimum amount of scrap. Presently, this type of manual solution procedure is used and the algorithms are terminated intuitively when the solution obtained is usually far from the optimum.

ISSN:0020-7543    

DOI:10.1080/00207548708919832

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A multi-echeleon inventory system with one central warehouse andnregional warehouses is considered. Customer demand is satisfied from the regional warehouses. A push type control system is used, implying that the allocation of stock is coordinated by the central unit. Given an initial system stock, a fixed planning horizon and two shipping possibilities from the central warehouse until the next system replenishment, the problem of deciding how much to ship initially to each warehouse is addressed. The stock retained at the central warehouse will be allocated to the branches at the second shipping opportunity so as to, if possible, balance the inventory levels, thus maximizing the customer service until the time of the next replenishment. An approximation of the multi-variate probability distribution of the inventory levels at the regional warehouses, after the second shipping opportunity, is presented. Given a desired customer service level, the optimal initial system stock and the associated allocation are derived on the basis of this approximation. Characteristics of the optimal solution are discussed. The performance is compared with a simple ship-all policy, and with an extreme policy allowing a complete redistribution of the inventory among the regional warehouses at the second shipping opportunity. The results show that significant benefits can be achieved by the retention of some stock at the central warehouse.

ISSN:0020-7543    

DOI:10.1080/00207548708919833

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Cast irons find increasing applications in the production of several automotive components such as crankshafts, gears and the like. Ceramics are the ideal tools for machining cast iron. The present paper illustrates data on performance of ceramic tools in machining cast iron. It also illustrates certain scanning electron micrographs highlighting the wear mechanisms.

ISSN:0020-7543    

DOI:10.1080/00207548708919834

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We describe how the frequency of rescheduling permitted in Material Requirements Planning (MBP) systems influences the impact of safety stock on system costs, and its effectiveness in maintaining desired levels of customer service. The results are obtained from approximate analytical models and simulation studies of a single product with stochastic demand and a two-level product structure. The results indicate that in some cases it may be more economical to reschedule infrequently and use safety stock as protection against demand variations. They also indicate that the effect of changing safety stock levels is much more predictable when rescheduling is infrequent, and that increasing safety stock may actually result in degraded performance when rescheduling is frequent.

ISSN:0020-7543    

DOI:10.1080/00207548708919835

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Statistical method, and in particular, simulation is the most widely used operations research modelling approach now employed by industry and government. Validation of a simulation model is the procedure designed to determine whether the model is an accurate representation of the portion of reality under consideration. It is a process distinct from model building or debugging (although interrelated). In this work, strategies and practical numerical techniques for validating large-scale production simulation models (or any other large system) are detailed. An evolution of the central concepts of large-scale model validation is represented first. The distinction between model user's risk and model builder's risk is highlighted as an important development which alters the problem into a consideration of the basis a decision-maker should use in determining whether to rely on the outputs of such models. Two quantitative techniques which are applications of the Turing test and of mathematical programming are developed as recent advances within the traditional framework of this research area.

ISSN:0020-7543    

DOI:10.1080/00207548708919836

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper studies the effect of uncertainty on capacity planning in MRP. Two sources of uncertainty are inherent in any capacity planning: (1) fluctuation in product demand and (2) variation in operation work contents. Through the use of computer simulation, experiments are performed on actual operating data supplied by an electronics company. It is found that the accuracy of a capacity plan is approximately a quadratic function of the level of variation in operation work contents and is significantly affected by product demand fluctuation. Theoretical treatment of the data yields the same conclusion, thus suggesting the validity of the simulation results. In view of these findings, the management is advised to exercise close control on the sources of variation so that acceptable accuracy can be achieved in determining a feasible production schedule.

ISSN:0020-7543    

DOI:10.1080/00207548708919837

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper comprehensively evaluates the influence of ultrasonic irradiation of spark gap on EDM characteristics for both planing and drilling operations. A set of comparative experiments were carried out and the analysis of the results was based on standard statistical techniques. The response surfaces and the corresponding response functions were determined for major performance indices, such as machining rate, tool wear rate, corresponding wear ratio and surface roughness. With the application of ultrasonics the machining rate and surface finish improved significantly and, although the tool wear rate also increased, the wear ratio was not influenced significantly. The improvement in machining rate was highly significant in the drilling operation.

ISSN:0020-7543    

DOI:10.1080/00207548708919838

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper deals with a problem to develop ‘factory automation systems’ which harmonize companies’ needs with workers’ desires. Two kinds of indices and methods of survey are proposed on the basis of the ‘fusion system concept’. One is that of the state of workers’ desires which are based on the ‘stimulus-response model’, the other is that of situations where ‘factory automation’ is implemented in a workshop. The effects of ‘factory automation’ on workers’ desires are clarified in a study of Japanese manufacturing industries in 1983. As a result of this investigation, some problems can be pointed out which should be solved in the future to develop ‘factory automation systems’.

ISSN:0020-7543    

DOI:10.1080/00207548708919839

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In this paper, we formulate the quadratic assignment problem through multiple objective programming in which we can have several objectives. In the facility layout problem, the objectives can be materials handling cost, production rate, and flexibility. We define efficiency and describe how efficient alternatives can be generated. A heuristic procedure based on pairwise exchange of subfacilities is developed to generate the efficient solution associated with a given set of objective weights. Our approach could just as easily implement the graph theoretic or other approaches to solve the quadratic assignment problem and generate efficient points associated with given weights. A paired comparison method based on the strength of preference among alternatives is developed. The paired comparison method generates the decision maker's weights of an assumed unknown utility function. The method asks simple questions and uses linear programming to solve the problem. An experiment with the developed computer package is discussed. Some examples are provided for solving the facility layout problem.

ISSN:0020-7543    

DOI:10.1080/00207548708919840

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor