摘要:

In this paper, the irregular operations problem is approached for the first time in a way that allows an airline to provide for schedule recovery with minimal deviations from the original aircraft routings.Anetwork model with side constraints is presented in which delays and cancellations are used to deal with aircraft shortages in a way that ensures a significant portion of the original aircraft routings remain intact. The model is flexible, allowing user preferences in the objective, and thereby reflecting the immediate concerns of the decision-maker in the recovery schedule.Themodel can be tailored by airline operations personnel to emphasize differing solution characteristics. Fleet data provided by Continental Airlines are used to demonstrate the approach. Extensive testing indicates that optimal or near-optimal solutions are routinely obtained from the LP relaxation of the network formulation. When integrality is not achieved, a rounding heuristic is provided that finds feasible solutions within a small fraction of the optimum.

ISSN:0740-817X    

DOI:10.1080/07408170008963891

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Integrating multiple sensors into manufacturing systems enables adaptive and flexible automation and increases process adaptivity and quality control. The design of an optimum configuration must be based on a systematic analysis relative to operational and economic considerations. This design should include an evaluation of sensor performance, a decision on how many sensors, of which type they should be, and where to locate them, modes of sensor interaction, and the influence on overall performance based on a cost/benefit analysis. In most real-world applications it is impossibletodevelop an accurate model to predict sensor performance and therefore, performance must be derived empirically but in a systematic manner. This paper presents research and development of integrated sensor economy principles and selection procedures in addition to a performance assessment model.Asystems engineering approach is applied for empirical investigations for assessment of alternative guidance systems. The outcome of this research is a set of general design guidelines for integrating multiple sensors into robotic manufacturing systems.

ISSN:0740-817X    

DOI:10.1080/07408170008963892

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper we solve the problem of determining the optimal inspection/disposition policy for a finite batch of items produced by a machine that is subject to random breakdowns. In particular, we identify which units should be inspected and in which order so as to minimize costs. The operational implications of the optimal policy are analyzed with a selected set of numerical results. We place special emphasis on three different policies: the cost minimizing policy; the policy of perfect information, i.e., we insist on determining the quality of each unit; and the policy of zero-defects,i.e.,weinsist that all accepted units are known to conform to specifications, allowing the rejection of units of unknown quality. We alsoshowhow the optimal inspection/disposition policy is incorporated into the optimization of the batch size.

ISSN:0740-817X    

DOI:10.1080/07408170008963893

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

An operation sequence-based method which integrates intra-cell layout cost with cell formation tominimizethe total cost of the materials flow and machine investment is developed here for designingacellular manufacturing system. The method comprises three distinct approaches: part-family formation, cell-formation, and layout configuration.Inthe first phase, an operation sequence-based similarity coefficient is applied in ap-median model to group the parts to form part families with similar operation sequences. In the second phase, machine assignment to part families is determined where a trade-off between potential inter-cell movement cost due to the. bottleneck machine and the potential benefit of assigning bottleneck machines to certain part-family is considered. In the third phase, intra-cell layout is determined for each cell so as to refine the initial layout of the cell further. Numerical examples are employed to demonstrate the mechanism of the procedure throughout all phases.Acomparative study is also performed to support the present method

ISSN:0740-817X    

DOI:10.1080/07408170008963894

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Non-stop flights are the first choice for passengers traveling from one city to another. In the absence of such flights, passengers must take connecting services (or connections) withtwoor more flights.Athrough flight is a type of connection that uses the same aircraft for the flights involved, which enables connecting passengers to remain onboard rather than deplaning to locate their departure gates at busy airports. The convenience of through flights gives them a marketing advantage over regular connections. For this reason, airline schedulers invest significant effort in building profitable through flights into the flight schedule. We have developed an optimization model for United Airlines for constructing the set of through flights that maximizes the through revenue for a schedule. The model eliminates the manual effort involved in assigning through flights and enhances the network contribution by at least ten million dollars annually.

ISSN:0740-817X    

DOI:10.1080/07408170008963895

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The problem is to determineareview period and stocking policy that are mutually beneficial to a producer and a retailer. In our model, the retailer uses a periodic review, base stock policy for ordering the item from the producer's Distribution Center (DC). Excess customer demand is assumed to be lost.Amake-to-order production system supplies to the DC. We show that given a review period, unless the manufacturer agrees to share the cost of carrying a fractionofthe safety stocks at the retailer, the two will not agree upon the level of stocks to be carried in the store. We prove that there is an equilibrium valueforthis fraction, such that the retailer and the manufacturer are always in agreement withregardto the stocking level. We then show that complete coordination on the stocking level as well as the review period can be achieved solely through carrying out negotiations on credit terms. These theoretical results are used to construct an algorithm for calculating the optimal policy parameters for a supply chain. As part of the analysis we suggest a modification of the base stock policy for the positive lag lost sales caseofperiodic review inventory models that consistently outperforms the base stock policy in our numerical studies.

ISSN:0740-817X    

DOI:10.1080/07408170008963896

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper we describe a class of resource allocation problems with a min-sum-max objective function. We first discuss practical applications of the problem. We then present a result on the computational complexity of the problem. We propose an implicit enumeration procedure for solving the general case of the problem, and report on our computational experience with the solution procedure.

ISSN:0740-817X    

DOI:10.1080/07408170008963897

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408170008963898

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408170008963899

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408170008963900

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor