ISSN:0160-5682    

DOI:10.1057/jors.1990.79

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractMany decision support systems for feedstock companies include an option for the solution of large linear programming problems. A three-level decomposition algorithm is presented which substantially improves the solution times for such linear programming problems. When decisions must be made on the addition of new raw materials or extra quantities of existing raw materials to feed mixes, the usual approach is to use parametric linear programming. A new approach to this decision problem, based on the results of the three-level decomposition algorithm, is presented in the paper. Finally, implementation issues and the computational performance of the new approaches on real-world problems are discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1990.80

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper describes the application of a differential game model in which technological as well as economic strategies are present. Inventory is not considered, so the products of each firm may be thought of as services. The solution concept is the memoryless closed-loop Nash equilibrium, which is computed by numerical approximation. Effects of changes in technology purchase prices, salvage values at the end of the planning horizon and initial production capacities are studied on realistic data. Managerial policies of demand-capacity balance are examined, and the effects of tight controls are observed. Analyses to show the impact of cost-reduction differentials of new technologies are presented. The insights obtained by the use of such a model can be quite significant, and sizable advantages may be gained through their application.

ISSN:0160-5682    

DOI:10.1057/jors.1990.81

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA computer model has been developed to address the problem of attaining the most cost-effective balance when providing perimeter security at any given prison. The generalized analysis of security of perimeters (GASP) model evaluates the cost and performance of different prison perimeters in terms of several measures. The modelling process takes account not only of the site-specific problems such as perimeter shape, but also of the policy input of trade-offs between the various output measures of cost and effectiveness. Goal-programming and multi-criteria decision-making techniques have been used.

ISSN:0160-5682    

DOI:10.1057/jors.1990.82

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractData envelopment analysis (DEA) has become an accepted approach for identifying inefficient decision-making units in an organization. This paper presents a systematic application of DEA carried out at the Commercial Bank of Greece in assessing the relative efficiency of bank branches. After a description of the model and the data, the results of the analysis are discussed, and a note is made of certain aspects of the follow-up analysis.

ISSN:0160-5682    

DOI:10.1057/jors.1990.83

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractAn index fund is a portfolio of shares designed to replicate the investment performance of a market index. The index represents the behaviour of the market as a whole. This paper describes the selection of an index fund which minimizes expected tracking error. Using a multivariate model of returns on shares, a development of a univariate model by Taylor, the selection problem is formulated as a quadratic programme. The effects of various constraints on tracking error are demonstrated. Several policies for the readjustment of a fund are examined in the context of the differing objectives of fund managers. As a general rule, regular readjustment is shown to be a more expensive policy than irregular updating.

ISSN:0160-5682    

DOI:10.1057/jors.1990.84

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper extends earlier hierarchical production-planning approaches initiated by Hax and Meal. The proposed model incorporates both functional and hierarchical interfaces simultaneously as encountered in practice, and assures feasibility and consistency among the decisions made at the different hierarchical levels of the firm. The problem of infeasibility which arises in disaggregating the aggregate production plan into detailed schedules is solved using goal programming at the product-family disaggregation level, and using branch and bound at the item-disaggregation level. The proposed approach minimizes backlogging regardless of the underlying cost structure of the problem at hand.

ISSN:0160-5682    

DOI:10.1057/jors.1990.85

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper is concerned with a combined production-transportation scheduling problem. The problem comprises a simple, two-machine, automated manufacturing cell, which either stands alone or is a subunit of a complete flexible manufacturing system. The cell consists of two machines in series with a dedicated part-handling device such as a crane or robotic arm for transferring parts from the first machine to the second. The loading of a new piece on the first machine and the ejection of a finished piece from the second machine are performed by dedicated automated mechanisms. The introduction of parts into the system is donenat a time, whereby the parts are reshuffled into a sequence that minimizes completion time. All processing and transfer times are considered deterministic—a reasonable assumption for a cell comprising a robotic transfer device and two CNC machining units. What complicates the problem is the assumption of a non-negligible time for the transfer device to return (empty) from the second machine to the first. The operation is a generalization of a two-machine flowshop problem, and is formulated as a specially structured, asymmetric travelling salesman problem. An approximate polynomial time 0(nlogn) algorithm is proffered. The procedure incorporates a lower bound using the Gilmore–Gomory algorithm for the no-wait, two-machine flowshop problem.

ISSN:0160-5682    

DOI:10.1057/jors.1990.86

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractIn an EOQ system, an anticipated price increase may require determination of an exceptiom lot. A criterion of minimizing the maximum error in terms of cumulative costs is used to determine this lot. This avoids the pitfalls raised on earlier works that compare out-of-phase inventory policies. The exception lot determined happens to be equal to the one obtained by an average cost model.

ISSN:0160-5682    

DOI:10.1057/jors.1990.87

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractWe consider optimal replenishment policy in the case of deterministic demand, with demand a known function which is periodic in time. The general formulation is a special case of Donaldson's fixed-horizon model, and two common situations are discussed: (i) demand varies sinusoidally; and (ii) there is an abrupt increase or decrease in demand, represented mathematically by a discontinuity in the demand rate.

ISSN:0160-5682    

DOI:10.1057/jors.1990.88

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor