摘要:

AbstractThe purpose of this paper is to demonstrate how the relation between the mean arrival rate of break-downs conditional upon the inspection frequency of equipment can be estimated in practice. The work was carried out for a large, urban transit authority operating a fleet of approximately 2000 buses undertaking about 80 million kilometres per year. A model relating total downtime of buses incurred due to inspections and repairs per unit time to inspection frequency is developed, and the optimal inspection frequency which maximizes bus availability is determined.

ISSN:0160-5682    

DOI:10.1057/jors.1990.116

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe paper reports on a linear programming application in the meat industry. The problem is formulated as a variant of the cutting-stock or trim problem, where the objective is to maximize the return from selling products yielded from cutting patterns applied to animal carcasses. One feature of the formulation is the partitioning of cutting patterns among carcass sections. Since the sections are relatively independent, this partitioning vastly reduces the number of cutting patterns in the formulation. Implementation is on a personal computer, and the system is used by a meat company for market planning. The system uses a commercial database to handle data entry and solution reporting, and has been found to be extremely user-friendly.

ISSN:0160-5682    

DOI:10.1057/jors.1990.117

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper develops, demonstrates and tests a heuristic procedure for controlling finished goods in a multi-echelon environment where there are significant transportation costs and capacity limitations on storage and transportation resources. This overall problem can be formulated as a large, mixed-integer linear programme (MILP), but solving such a model for practical-sized problems is costly and time-consuming, or even impossible, given computer systems typically used by businesses. Instead, the MILP formulation is used to both motivate and provide a benchmark for testing the performance of the heuristic procedure developed in this paper. When compared to the optimal results from the MILP, the cost performance of the heuristic procedure is found to be excellent.

ISSN:0160-5682    

DOI:10.1057/jors.1990.118

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper deals with a simple but efficient heuristic solution method for the basic one-depot vehicle-routeing problem. It is called the chain-exchange principle, which represents a generalization of the improvement procedures removing just one or two customers. The chain-exchange process is shown for problems with up to 100 customers, which can be solved on microcomputers with justifiable use of computing time.

ISSN:0160-5682    

DOI:10.1057/jors.1990.119

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractIn this paper we present a method, based on the use of proportions, for restricting weight flexibility in data envelopment analysis. This method is applicable when the decision-making units being evaluated have multiple inputs and outputs.

ISSN:0160-5682    

DOI:10.1057/jors.1990.120

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractWe present an application of parallel computing techniques to the solution of a quadratic programme that arises in the resource-directive decomposition method for multicommodity problems. A sequential algorithm for the quadratic programme is discussed, and its extension to a parallel implementation is given. Computational testing of the sequential and parallel algorithms was done on the Sequent Symmetry S81 parallel computer located in the Parallel Processing Laboratory at Southern Methodist University. On several large test problems the parallel version achieved a speed-up of 10 with 12 processors.

ISSN:0160-5682    

DOI:10.1057/jors.1990.121

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractAn expression is derived for the increase in stochastic performance of a continuum structure of the Barlow-Wu type when each component of a subset is replicated once. If a single component is to be replicated, criteria are given for selecting the component so as to maximize the system performance for series and parallel structures. A series of upper bounds is derived for the increase in terms of the critical importance of the replicated component.

ISSN:0160-5682    

DOI:10.1057/jors.1990.122

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper addresses the issue of optimal project selection for capital expenditures assuming uncertain budgetary allocations. A critical review of the historical development of capital budgeting models indicates two major deficiencies: (i) deterministic models ignore the uncertain nature of capital budgeting problems; and (ii) those models which do incorporate the concept of uncertainty have serious computational problems when applied to larger problems. A stochastic capital rationing model (SCRM) is proposed which makes use of recent developments in stochastic programmes with recourse. This model remains computationally tractable despite the explicit incorporation of uncertainty and the application of theoretically sound penalties for constraint violations. Two problems are introduced which illustrate the model's superiority over comparable deterministic formulations. By varying both the probability distributions of the stochastic constraints and the borrowing rates, it was possible to identify the impact these factors have on project selections.

ISSN:0160-5682    

DOI:10.1057/jors.1990.123

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA heuristic for obtaining an initial solution for the transportation problem is presented. Comparison of findings obtained by the new heuristic and Vogel's approximation method (VAM) are tabulated for 480 examples. Superior performance of the new heuristic over VAM is discussed in terms of total costs obtained, number of iterations required to reach the final solution, and CPU time required to solve the problems. Experimental design aspects are also presented.

ISSN:0160-5682    

DOI:10.1057/jors.1990.124

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper analyses the use of multiple suppliers to replenish one stock item. The replenishment order is split into several portions, one for each supplier, and orders for these portions are placed simultaneously with the respective suppliers. Approximate expressions are derived for the mean and variance of the effective lead time, which is the minimum of the individual lead times of each supplier. These results give effective lead-time-demand mean and variance that are smaller than those of the individual suppliers. The results can be used to lower the operating cost of the stocking policy.

ISSN:0160-5682    

DOI:10.1057/jors.1990.125

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor