摘要:

AbstractAt a company's request we were asked to determine the placement and the number of protection devices for their electrical tree networks. Three location heuristics were selected for this purpose and tested on artificial data. The chosen heuristic was then applied to two real tree networks with successful results.

ISSN:0160-5682    

DOI:10.1057/jors.1995.202

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThe problem of determining a project selection schedule and a production-distribution-inventory schedule for each of a number of plants so as to meet the demands of multiregional markets at minimum discounted total cost during a discrete finite planning horizon is considered. We include the possibility of using inventory and/or imports to delay the expansion decision at each producing region in a transportation network. Through a problem reduction algorithm, the Lagrangean relaxation problem strengthened by the addition of a surrogate constraint becomes a 0–1 mixed integer knapsack problem. Its optimal solution, given a set of Lagrangean multipliers, can be obtained by solving at most two generally smaller 0–1 pure integer knapsack problems. The bound is usually very tight. At each iteration of the subgradient method, we generate a primal feasible solution from the Lagrangean solution. The computational results indicate that the procedure is effective in solving large problems to within acceptable error tolerances.

ISSN:0160-5682    

DOI:10.1057/jors.1995.203

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractIn this paper, we compare different exchange heuristics for vehicle routeing problems with time windows. We also introduce a new 2-opt* exchange heuristic, and show that a hybrid approach, based on Or-opt and 2-opt* exchanges, is particularly powerful for problems with time windows. Computational results are reported for randomly generated problems and for a standard test set.

ISSN:0160-5682    

DOI:10.1057/jors.1995.204

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractA flexible manufacturing cell consisting of two machining centres, several automated storage/retrieval stations, and a mobile transporting robot is considered. The problem is to schedule jobs on machines so as to minimize the makespan, with the effects of transportation and set-ups to be taken into account. The problem is studied with the aid of a graph model, and an exact algorithm of cubic complexity is derived based on the Gilmore–Gomory algorithm for the travelling salesman problem.

ISSN:0160-5682    

DOI:10.1057/jors.1995.205

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper deals with a situation in which the buyer is in a monopolistic position with respect to the seller, and examines the issues and advantages of co-operation in a seller–buyer inventory control system. Game theory concepts form the foundation for the analysis of these issues. Initially, the relationship between the seller and the buyer is modelled as a non-cooperative two-stage game, and it is noted that the traditional EOQ formula is one of the results. Then, interactive game theory is utilized to address the problem of system co-operation as well as to determine optimal system order quantity-pricing strategies. Mutual incentives and motivations for system co-operation are also discussed. Among several alternative methods, the combination of an equal profit sharing role implemented via quantity discounting is demonstrated as the best mechanism for achieving system co-operation. Finally, the similarities and differences between the proposed model and those in the literature are discussed.

ISSN:0160-5682    

DOI:10.1057/jors.1995.206

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractA new heuristic search procedure is proposed for retrospectively detecting shifts (defined as sudden changes in the process mean) within a stationary time series subject to substantial white noise. After identifying the first, most significant shift, the search procedure is applied progressively to detect further shifts and also to define the timing, size and statistical significance of such shifts. Prior to the application of the procedure, the time series under review is evaluated to determine whether it is consistent with the shifting-mean model that underlies the heuristic. A feature of the search procedure is that it can be operated automatically, with searches terminated either when the segment of the data series within which the next identified shift occurs is shown not to be suitable for the application of the heuristic, or when the latest identified shift proves not to be statistically significant.

ISSN:0160-5682    

DOI:10.1057/jors.1995.207

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractWe consider a scheduling problem where a set ofnjobs has to be processed on a set ofmmachines and arbitrary precedence constraints between operations are given. Moreover, for any two operationsiandjvaluesaij>0 andaji>0 may be given whereaijis the minimal difference between the starting times of operationsiandjwhen operationiis processed first. Often, the objective is to minimize the makespan but we consider also arbitrary regular criteria. Even the special cases of the classical job shop problemJ//Cmaxbelong to the set of NP-hard problems. Therefore, approximation or heuristic algorithms are necessary to handle large-dimension problems. Based on the mixed graph model we give a heuristic decomposition algorithm for such a problem, i.e. the initial problem is partitioned into subproblems that can be solved exactly or approximately with a small error bound. These subproblems are obtained by a relaxation of a subset of the set of undirected edges of the mixed graph. The subproblems are successively solved and a proportion of the results obtained for one subproblem is kept for further subproblem definitions. Numerical results of the algorithm presented here are given.

ISSN:0160-5682    

DOI:10.1057/jors.1995.208

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper questions what network parameter-estimates really are. This follows recent papers on Parkinson's law, on the relationship with Management by Objectives, and on the historical basis on which these estimates are made. An underlying distribution is proposed that follows from these points—both a general shape and a pragmatic approximation—which can be shown to reflect behaviour found in practice, and has indeed been used in practical risk analysis.

ISSN:0160-5682    

DOI:10.1057/jors.1995.209

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1995.210

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1995.211

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor