摘要:

AbstractA complex manual rostering system for directory assistance, telephone operators has been rationalized and the technique of integer programming used to automatically generate staff rosters. These rosters can be generated by relatively unskilled clerical staff. They result in operator costs comparable to manually generated rosters and can be produced in a fraction of the time taken to produce their manual counterparts. Implementation is reported.

ISSN:0160-5682    

DOI:10.1057/jors.1991.143

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractSome recent research on queueing models is successfully applied to the problem of designing an appropriate appointment system for the out-patient department at the Royal Lancaster Infirmary. Although it is acknowledged that improving appointment systems is not simply a modelling problem, it is nevertheless argued that the model used here could be an effective tool in local studies.

ISSN:0160-5682    

DOI:10.1057/jors.1991.144

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis study describes a technique originated from the emerging field of machine learning and demonstrates its effectiveness in stock screening. We have derived screening rules by applying a rule induction method, constructed portfolios using the rules, and evaluated the portfolios' performance using the Sharpe, Treynor and Jensen indexes. Results indicate that regularities among stocks can be identified, and portfolios so constructed outperformed the NYSE Composite index and the S&P 500 over the same period.

ISSN:0160-5682    

DOI:10.1057/jors.1991.145

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractIn this paper an integral equation approach is given for evaluating the expected cost of repair replacement policies over finite time horizons. An asymptotic estimate of this expected cost is also obtained. The policy involving imperfect repair on failure with replacement afterNfailures is taken as an illustrative example and optimal policiesN* are found for both infinite and finite time horizons of use.

ISSN:0160-5682    

DOI:10.1057/jors.1991.146

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractDatabases require a management system which is capable of retrieving and storing information as efficiently as possible. The data placement problem is concerned with obtaining an optimal assignment of data tuples onto secondary storage devices. Such tuples have complicated interrelationships which make it difficult to find an exact solution to our problem in a realistic time.We therefore consider heuristic methods—three of which are discussed and compared—the‘greedy’graph-collapsing method, the probabilistic hill-climbing method of simulated annealing and a third‘greedy’heuristic, the random improvement method, which is a local search heuristic. Overall, the best performance is obtained from the graph-collapsing method for the less complicated situations, but for larger-scale problems with complex interrelationships between tuples the simulated annealing and random improvement algorithms give better results.

ISSN:0160-5682    

DOI:10.1057/jors.1991.147

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper considers production-maintenance policy for the deteriorating production system which can go‘out of control’while producing items. Once out of control, the production process produces some proportion of defective items. The defective items are reworked at some cost before being shipped, or, if passed to the customer, incur much larger warranty cost. Thus, to operate this system economically, periodic inspection and restoration of the process are needed. A mathematical model representing the expected annual cost is developed to determine the production cycle and process inspection intervals jointly. A case of equally spaced inspection intervals is solved by using an approximation to the cost function.

ISSN:0160-5682    

DOI:10.1057/jors.1991.148

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper considers a two-product, single-machine production scheduling problem where there is an added constraint on the amount of finished stock that can be held. The need for a ratio of the cycle times of the two products is a feature both of two-product production scheduling problems contained on one machine and two-product inventory problems with constraints on storage capacity. This means an easy solution algorithm is possible for the problem addressed in the paper which has both types of constraints.

ISSN:0160-5682    

DOI:10.1057/jors.1991.149

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractLine simplification is a process by which unnecessary detail in cartographic data is eliminated. In the past, a variety of heuristics have been implemented to simplify lines. This paper describes practical algorithms which have been developed to provide optimal solutions. The line simplification problem is shown to have the special structure of an acyclic shortest-path problem. Three formulations are presented, which differ in the form of their objectives and/or constraints, and a solution algorithm is outlined for each formulation. Issues associated with implementation are addressed by using each algorithm to perform various degrees of simplification on a large example line. Possibilities for future research related to optimal line simplification are also discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1991.150

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper shows that under date-terms supplier credit, making explicit the separate effects of carrying cost, the financing and other marginal holding costs, does not invalidate Kingsman's original result that the optimal order quantity is given by an integer multiple of monthly demands, provided the capital investment component of the inventory holding costs is equal to or greater than 30% of the component due to the physical holding of inventory. The analysis is extended to the case when orders of less than a month's demand are optimal. Here it is shown that the order quantity should be an integer fraction of a month's demand, provided that the capital investment component of the inventory holding charge is equal to or greater than one quarter of the component due to the physical holding of inventory. It is argued that these conditions are likely to be satisfied for most if not all practical inventory situations. Combining these results with those of Carlson and Rousseau leads to a simple formula for the general optimal policy. The EOQ can still be expressed as a simple formula, so for practical situations generally there is no need to use the numerical search procedure these authors propose.

ISSN:0160-5682    

DOI:10.1057/jors.1991.151

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper examines a single-machine, non-renewable-resource-constrained scheduling problem where jobs have arbitrary processing times and resource requirements. Unit supply of a resource is assumed at each time period. Performance criterion is makespan. It is proved that this problem is identical to the two-machine flowshop problem, enabling the use of Johnson's algorithm. Immediate extensions of this result are presented.

ISSN:0160-5682    

DOI:10.1057/jors.1991.152

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor