摘要:

AbstractMost of the published job-shop research has focused primarily on the identification of dispatching rules which perform well under a variety of shop conditions. Most of the research has assumed that the job shop was an open shop in the sense that a virtually unlimited number of job routeings was possible, as compared to a closed shop, which has much more standardized routeings. Also, most research has further assumed that the capacities at all machines are relatively even, and thus no permanent bottleneck exists. In this research, some of the best-known dispatching rules are studied to determine whether the rules are robust with respect to capacity balance and work-flow structure. In order to be useful in all types of job shop, a rule should perform well regardless of the balance of capacity and work-flow structure in the shop. Results indicate that most of the rules studied are not affected by either of the above factors.

ISSN:0160-5682    

DOI:10.1057/jors.1990.142

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper is concerned with a university timetabling problem in which some clashes are unavoidable if the weekly lecture requirements are to be scheduled in the available time-slots. The solution needs to satisfy a number of different objectives. Most of these are achieved by imposing a series of constraints, and the problem is reduced to that of minimizing the single objective of student disappointment. Three models—graph colouring, set partitioning and simulated annealing—are suggested, and the advantages and disadvantages of using each of these to find a satisfactory solution are discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1990.143

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA multi-attribute value model has been developed to study UK energy-policy options. The model consists of four main stages: attribute selection, in which users identify up to 15 key attributes of an energy policy; attribute rating, in which a quantitative assessment is made of the relative importance of each of the attributes selected; option evaluation, in which users are asked to score five energy-policy options for the UK (drawn from a range of published sources) on each of the attributes; and experimentation, in which users are encouraged to explore and modify a tabular and graphical representation of the results. The model has been used in a series of workshops at which representatives from different organizations have been invited to use the model to explore each other's viewpoints. User reactions to the model are discussed, and the potential of such models for addressing controversial social issues is considered.

ISSN:0160-5682    

DOI:10.1057/jors.1990.144

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractWe analyse an (s, Q) production policy for an inventory system consisting of a single finished product and the raw materials used for manufacturing it, and where the demand rate of the product increases linearly with time. We formulate a mathematical programming model with the objective of minimizing total inventory cost per unit time. The problem of grouping raw materials optimally so that common replenishment periods may be used is considered. Solution procedures are developed, and numerical examples are presented.

ISSN:0160-5682    

DOI:10.1057/jors.1990.145

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper presents a queueing model with the service station subject to breakdown while it is busy, in order to determine analytically the optimal batch size in a machining economics problem. It is shown that departures from the optimal batch size result in moderate waiting-time increases when the batch size is scaled up and in significant waiting-time increases when the batch size is scaled down. It is also shown, through the use of a simulation model with normally distributed tool lives, that the analytical results obtained with exponentially distributed tool lives are quite robust. In the multiple-item case, simulation results show that the time in the system for each item and the average time in the system across all items behave exactly like the time in the system in the single-item case.

ISSN:0160-5682    

DOI:10.1057/jors.1990.146

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractIn this paper, alternative methods for estimating the beta distribution are proposed that utilize more information than the standard method based on the best, worst and most likely estimates. In particular, it is shown how information on skewness or the decision-maker's level of confidence can be incorporated into the estimation process. This provides an alternative to the restrictive assumptions that have to be made in the standard method. This is particularly useful when the skewness is expected to be high, or in situations where the degree of uncertainty is high.

ISSN:0160-5682    

DOI:10.1057/jors.1990.147

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractFor the multidimensional 0-1 knapsack problem a heuristic exists, based on Lagrange multipliers, that also enables the determination of an upper bound to the optimal criterion value. This heuristic is extended in two ways: (1) in each step, not one, but more multiplier values are computed simultaneously, and (2) at the end the upper bound is sharpened by changing some multiplier values. From a comparison using a large series of different test problems, the extensions appear to yield an improvement, on average, at the cost of only a modest amount of extra computing time.

ISSN:0160-5682    

DOI:10.1057/jors.1990.148

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis model discusses an infinite time-horizon deterministic inventory model without shortages, where the demand rate at any instant depends on the on-hand inventory (stock level) at that instant down to a certain stock level and then it becomes constant for the remaining period of the cycle. The decision rule for finding the optimal order quantity is also given, and three numerical examples are presented to illustrate the model developed.

ISSN:0160-5682    

DOI:10.1057/jors.1990.149

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper deals with the transient fluctuations of the mean production rate of a two-stage production system subject to interstage and end inspections and end buffer. The interstage and end inspections are instantaneous, and the end buffer is with finite capacity of sizeN. A stochastic model is developed to describe the system, and analytical expressions to evaluate the mean production rate (MPR) of machinej(=I, II) in [0,t] with arbitrary distributions of processing times at the stages of production and exponential supply and demand pattern have been obtained by using the state-space method and the regeneration-point technique. A particular case is investigated, and numerical results are presented.

ISSN:0160-5682    

DOI:10.1057/jors.1990.150

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe manpower planning models available in the literature have dealt with how changes take place in a manpower planning system, under various operating and policy constraints. However, none of these models has identified the manpower system costs. In this paper we have identified various manpower system costs. Further, we have developed a manpower planning model with the objective of minimizing the manpower system costs. The model has been found to be analogous to the Wagner-Whitin model in production/inventory management. A numerical example has been given to illustrate the model.

ISSN:0160-5682    

DOI:10.1057/jors.1990.151

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor