摘要:

AbstractA paper in a previous issue of this journal described the development of a decision-support system for planning services within hospitals, the Hospital Planning Model. A crucial test of such a system is the actual change in the planning process its use brings about. Does it change and improve the planning process or do planners prefer to continue with historical practice? To demonstrate the potential impact of a decision-support system on planning, this paper describes a major application of the system undertaken in an inner London DHA. In this study, use of the system helped overturn management's original intention and resulted in savings of around£2 million.

ISSN:0160-5682    

DOI:10.1057/jors.1990.176

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA case is described that has been used successfully many times as a vehicle for teaching mathematical modelling. The case has been closely derived from a consultancy assignment with Chartwell Books. The place of mathematical modelling within decision-support systems is examined, and this is followed by an outline of one such mathematical modelling methodology. The problem situation facing the managing director of Chartwell Books concerning the modelling of labour and material costs is described. A detailed application of the mathematical modelling methodology is worked through, finishing with a discussion of the value of the case for student teaching and of the problems that students have encountered when tackling the Chartwell case. Possible extensions to the basic methodology, such as validation and the human-computer interface, are also briefly considered.

ISSN:0160-5682    

DOI:10.1057/jors.1990.177

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe problem of ranking players in a tournament has been studied by a number of authors. The methods developed for ranking players fall under two general headings—direct methods and rating methods. The present paper extends the tournament ranking problem in two directions. First, the usual definition of a tournament is broadened to include ties or draws. Thus, our model determines the best weak ranking of the players. Second, the ranking method presented takes account of player strength in that wins over strong players are valued higher than wins over weak players. To account for player strength, we evaluate both direct or first-order wins of players over opponents (idefeatsj) and indirect or higher-order wins (idefeatsk, who defeatsj). A model which derives a composite score for each player, combining both direct and indirect wins, is used to obtain an overall ranking of the competitors.

ISSN:0160-5682    

DOI:10.1057/jors.1990.178

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractMany algorithms have been developed for multiple-criteria decision-making problems. Goal programming (GP) is one of these algorithms. This model is a special extension of linear programming. Usually, it is not easy for the decision-maker to choose his aspiration levelsa priori. Moreover, the incommensurability of the measurement units of the various objectives creates an aggregation problem. However, in the standard GP formulation, the decision-maker is not required to arbitrate among conflicting objectives. To deal with these difficulties, we explicitly introduce the structure of the decision-maker's preferences into the GP model in order to evaluate the impact of deviations from the decision-maker's aspirations levels. Easily and naturally, the idea of a generalized criterion, as introduced in the Promethee outranking method, will be used to build this structure of preferences.

ISSN:0160-5682    

DOI:10.1057/jors.1990.179

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractAlthough simple random sampling is the standard sampling procedure in Monte Carlo simulation, such practice is questioned in this paper. In any Monte Carlo application, sampled distributions are assumed to be known. Using simple random sampling, sample histograms or, equivalently, sample moments will vary at random, thus producing an imprecise description of the known input distribution, and consequently increasing the variance of simulation estimates. This problem can be avoided with descriptive sampling, here proposed as a more appropriate approach in Monte Carlo simulation than simple random sampling. Descriptive sampling is based on a deterministic and purposive selection of the sample values—in order to conform as closely as possible to the sampled distribution—and the random permutation of these values. As such, it represents a fundamental conceptual change in Monte Carlo sampling, departing from the‘principle’that sample values must be randomly generated in order to describe random behaviour. The basis of this new idea, examples of its use and empirical results are presented.

ISSN:0160-5682    

DOI:10.1057/jors.1990.180

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractNumerous multiobjective linear programming (MOLP) methods have been proposed in the last two decades, but almost all for contexts where the parameters of problems are deterministic. However, in many real situations, parameters of a stochastic nature arise. In this paper, we suppose that the decision-maker is confronted with a situation of partial uncertainty where he possesses incomplete information about the stochastic parameters of the problem, this information allowing him to specify only the limits of variation of these parameters and eventually their central values. For such situations, we propose a multiobjective stochastic linear programming methodology; it implies the transformation of the stochastic objective functions and constraints in order to obtain an equivalent deterministic MOLP problem and the solving of this last problem by an interactive approach derived from the STEM method. Our methodology is illustrated by a didactical example.

ISSN:0160-5682    

DOI:10.1057/jors.1990.181

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper studies the machine-repair problem with two different types of a single service station breakdown under steady-state conditions. In type 1, the service station can break down only when there is at least one failed machine in the system, while in type 2, the station can break down even if no failed machines are in the system. A profit model is developed in order to determine the optimal value of the number of machines to be assigned to the service station for both types. Numerical results are provided in which several system characteristics are evaluated under optimal operating conditions.

ISSN:0160-5682    

DOI:10.1057/jors.1990.182

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA challenging problem in process control is the selection of input levels which will produce desirable output quality. This problem is complicated by the unsure relationships of cause and effect and by the trade-offs between meeting conflicting output specifications. This paper proposes a new approach, which incorporates prediction-interval constraints into a goal-programming model. A process-control problem, originally solved by the desirability-function approach, is solved using this new model. Comparisons between the two approaches are discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1990.183

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractIn this paper we consider the problem of determining the optimal purchase quantity when the supplier offers a discount on large purchases. We propose a simple approach which requires fewer EOQ calculations for determining the lot size.

ISSN:0160-5682    

DOI:10.1057/jors.1990.184

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractEvery life faces a certain age-specific mortality risk. Changing this mortality risk for a life agedAby a small quantityR, say, would change the life expectancy byRxK, whereKis some constant. Kamerud has proposed a model forKwhich is independent ofR. This note offers an improvement to Kamerud's model which depends on bothAandR.

ISSN:0160-5682    

DOI:10.1057/jors.1990.185

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor