摘要:

AbstractGiven the importance of understanding decision making processes within organizations, studies of the attitudes of Operational Research practitioners towards specific aspects of their work is a neglected area of research. This paper furnishes an account of a questionnaire-based survey of industrially based OR practitioners selected from the membership of the Operational Research Society. The objective of the study is to assess the views of OR practitioners regarding the modelling and problem solving tools that are available to them. In particular, the issues of technique selection, the treatment of uncertainty, and the perceived contribution of Operational Research to decision issues are investigated. Results from the survey contribute towards both a greater understanding of OR practitioners' perspectives on the decision support process and the development of a profile of the membership of the OR Society.

ISSN:0160-5682    

DOI:10.1057/jors.1995.113

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper describes a study of a large design and manufacture engineering project, undertaken as part of a Delay and Disruption litigation. Design changes and delays in design approval would have caused delay to the project; in order to fulfil a tight time-constraint, management had to increase parallel development in the network logic, reducing delay but setting up feedback loops that markedly increased total project spend. Cognitive mapping was used to elicit the relationships, which suggested the use of System Dynamics to quantify the effects. Results are described that show the effect of levels of design changes and approval delays, and their compounding effect. The wider implications on modelling projects are also discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1995.114

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis study presents an approximation of a Markovian decision process to calculate resource planning policies for environments with probabilistic resource demand. These policies provide a means of periodic determination of the quantity of resources required to be available. Managers may also use these approximation models to perform the sensitivity analysis of resource demand and the cost/reward parameters. The decision policy can be applied to many resource planning situations including manufacturing or construction equipment purchasing or leasing, airline capacity, professional services staffing, and computer/management information systems capacity.

ISSN:0160-5682    

DOI:10.1057/jors.1995.115

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper is concerned with the evaluation and enhancement of the maintenance routines of large and complex technical systems. An‘intelligent decision support system’approach is suggested as a method for overcoming the difficulties associated with the scale, variability and changeability of such systems. The main features of the proposed intelligent maintenance optimization system (IMOS) are identified. A prototype system is then presented and its main mathematical models of maintenance are introduced. Some sample test data and the results produced from them are presented. Other aspects discussed include dealing with censored data, optimization criteria, the development of a maintenance model selection rule base, the recognition of data patterns and models' robustness. Results of IMOS system validation against expert advice have shown a high measure of consistency.

ISSN:0160-5682    

DOI:10.1057/jors.1995.116

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractIn this paper, we consider the problem of detecting the collision of moving objects in three-dimensional space. We develop two algorithms that use linear programming techniques to detect exact possible collisions between the objects in both time and space when the objects are represented as polyhedral sets inℛ2orℛ3. The algorithms can handle the case of a rigid body moving on a general path with simultaneous translation and rotation. Computational experience on the developed algorithms is also presented.

ISSN:0160-5682    

DOI:10.1057/jors.1995.117

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractOne aspect of project planning risk assessment is to do with the uncertainty of the project duration. This uncertainty can be quantified by determining the project completion time distribution. A brief review of the existing literature on project duration risk assessment methodologies is given and their advantages and disadvantages evaluated. A development of the moments method based on Erlang distribution of activity times provides an accurate estimate of a project completion time distribution for a large range of practical situations and also is the basis upon which multi-modal input distributions of activity times can be handled. The method is assessed by a number of illustrative examples.

ISSN:0160-5682    

DOI:10.1057/jors.1995.118

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractA new heuristic method for the permutation flow shop scheduling problem is presented and compared with two other heuristics named NEH and SPIRIT. The new heuristic method is based on a property of the scheduling problem that provides an upper bound on the idle time of the last machine between any two adjacent jobs regardless of their position in the sequence of jobs. The results from computational experience have shown that the new heuristic outperforms, in solution quality, all others for problems having up to 50 jobs and 30 machines.

ISSN:0160-5682    

DOI:10.1057/jors.1995.119

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractIn this paper, we present an economic order quantity (EOQ) model when two products are required, and one can be substituted for the other, if necessary, at a given unit cost. We consider three cases: (i) when there is no substitution between the products, (ii) when there is full substitution between the products, and (iii) when there is partial substitution between the products. In a deterministic setting with proportional substitution costs, we would expect to find full substitution or no substitution being optimal, depending on the cost parameters. However, we observe that full substitution is never optimal; only partial substitution or no substitution may be optimal. This result can best be explained due to the non-linearity of the decision variables in the total cost expression. Finally, we present an algorithm to compute the optimal order quantities.

ISSN:0160-5682    

DOI:10.1057/jors.1995.120

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper investigates how the mean and variance of lead time change with the number of suppliers. Using known analytical results for the means and variances of the‘first’and‘spacing’lead times, we give simple decision rules to find the optimal numbers of suppliers when lead times are uniformly or exponentially distributed.

ISSN:0160-5682    

DOI:10.1057/jors.1995.121

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThe problem of scheduling a two-machine flowshop, where set-up times are considered as separate from processing times and machines suffer random breakdowns, is addressed with respect to the makespan objective. A dominance relation for minimizing makespan with probability 1 is established. Furthermore, it is shown that Yoshida and Hitomi's algorithm for the deterministic problem stochastically minimizes makespan when random breakdowns are present.

ISSN:0160-5682    

DOI:10.1057/jors.1995.122

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor