摘要:

AbstractPerceived importance attribute rankings, obtained from samples of various types of public transport users, are used to determine the relative weights of their level of service vectors. A generalization of a recent linear programming methodology is proposed which requires transforming the ranking data into equivalent pairwise choices. The weights were compared with those obtained from discrete choice models estimated with stated preference data.

ISSN:0160-5682    

DOI:10.1057/jors.1994.180

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractMilitary communications networks are large complex systems; their physical dynamics, composition, workload characteristics and operational goals make them very hard to model and analyse. It is particularly difficult to build a generalized model that can adequately fit each instance, generate a workload that exercises the network in a realistic way, and measure network effectiveness in terms of the operational goals. In this work, we describe our approach to building such a model for the US Marine Corps, and demonstrate the model's use by solving a particular equipment allocation problem. We combine object-oriented simulation with new concepts for workload modelling and measuring effectiveness that are based on the operational tasks the Marines perform.

ISSN:0160-5682    

DOI:10.1057/jors.1994.181

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThe‘Bob Graham Round’is an arduous route in the English Lake District which fell-runners attempt to complete in under 24 hours. Runners who complete the round and wish to have their achievement recognized must submit a detailed timetable of their progress. From an analysis of these submissions we have:(a) tested an elaboration to the well-known Naismith Rule for predicting progress in mountainous country;(b) tested the conjecture that successful athletes in stamina events apply a constant work rate;(c) estimated the effect of such additional factors as darkness or fatigue.The objective of our work is threefold. First, to help runners planning an attempt on the round. Secondly, (as the Lake District mountains are so well known and accessible) to provide any readers who are mountain walkers with an opportunity to check our estimates against their own experience and judgement. This can of course be done for any section of the route, and does not require the whole round to be tackled. Thirdly, to make our findings applicable for mountainous areas other than the Lake District.

ISSN:0160-5682    

DOI:10.1057/jors.1994.182

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThe quality requirements set by edge exchange heuristics on their initial solutions are evaluated in connection with the travelling salesman problem. The performance of the heuristics is measured using the expected value of the best solution achievable in a certain computing time. The computational results show that the use of initial solutions generated by applying a construction heuristic, instead of random initial solutions, typically improves the performance of edge exchange heuristics. The improvement, however, is dependent on the edge exchange heuristic to be used, the properties of the problem, and the computing time available.

ISSN:0160-5682    

DOI:10.1057/jors.1994.183

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThis research investigates two maintenance float models in a flexible manufacturing system (FMS). We use classical queueing theory to study the characteristics of the fractional utilization of the system. A mathematical program is constructed to determine the optimal number of floats of an important module used in the FMS and the optimal capacity of the repair station.

ISSN:0160-5682    

DOI:10.1057/jors.1994.184

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractA new heuristic for the vehicle routeing problem which makes use of repeated matching is described. The numerical results are comparable to or better than the best published for most of the 14 benchmark problems commonly used to evaluate VRP heuristics.

ISSN:0160-5682    

DOI:10.1057/jors.1994.185

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThis paper provides a modelling framework for the use of non-homogeneous Markovian techniques for components and systems, where the sojourn time at a state, or a class of states, may be limited by a given value. This approach is useful, for example, to build component models with constant repair times, and to model systems or components with tolerable down times. Tolerable down time models have appeared in the field of Boolean techniques for 10 years. A systematic Markovian approach applied to systems composed of several components, allows the interdependencies among the components to be precisely treated, which may cause large conservativeness, if the Boolean modelling technique is applied.

ISSN:0160-5682    

DOI:10.1057/jors.1994.186

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThis paper presents a table of values of an adjustment factor to be used in predicting future values of a Gaussian process in the presence of asymmetric quadratic loss and which are helpful in the control of such a process. It is shown that in this case the optimal prediction is merely an additive adjustment to the conditional mean, the adjustment being the product of the standard deviation and the appropriate tabulated value.

ISSN:0160-5682    

DOI:10.1057/jors.1994.187

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractFlexible Manufacturing Systems (FMSs) are usually composed of general purpose machines with automatic tool changing capability and integrated material handling. The complexity of FMSs requires sophisticated control. In this paper we present a four-level control hierarchy and outline computationally feasible control algorithms for each level. The top level is concerned with the choice of part types and volumes to be assigned to the FMS over the next several months. The second level plans daily or shift production. Production levels are set and tools are allocated to machines so as to minimize holding and shortage costs. Various FMS environments are presented. The third level determines process routes for each part type in order to minimize material handling. Additional tools are loaded on machines when possible to maximize alternate routeing. Routes are then assigned to parts to minimize workload assignment, and these are used by level four for actual routeing, sequencing and material handling path control. The level three model is formulated as a linear program, and heuristics are used for level four. An example is provided to illustrate the completeness of the decision hierarchy and the relationships between levels.

ISSN:0160-5682    

DOI:10.1057/jors.1994.188

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThis paper presents a heuristic algorithm for determining order quantities for multiple items given incremental quantity discounts and a single resourse constraint. The heuristic is based on Lagrangian relaxation. The performance of the heuristic is compared, for small problems, with a procedure that generates optimal solutions. Results from computational experiments are given that demonstrate the quality and computational efficiency of the heuristic algorithm.

ISSN:0160-5682    

DOI:10.1057/jors.1994.189

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor