摘要:

AbstractAs part of the worldwide effort involved in modelling the spread of AIDS, nothing has been heard from the operational research community. Yet OR, with its client-oriented modelling philosophy, patently has a role to play in assisting clinicians, epidemiologists and health planners to obtain greater understanding of this staggering threat to public health. Using the methods of system dynamics, a model of the spread of AIDS in the UK homosexual population has been developed. It is implemented on a personal computer, and possesses the capability to capture complex virological and behavioural features of the epidemic whilst portraying the consequences in an easily digested graphical form. Some examples of these results are presented. The model's structure and parameters are also fully described, together with sensitivity tests on the crucial incubation time distribution.

ISSN:0160-5682    

DOI:10.1057/jors.1990.49

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe Hitchcock transportation problem is perhaps one of the‘most solved’linear programming problems in existence. We shall propose yet another computation for the problem....1The current computational status of the transportation problem is reviewed, and the claims of three papers that recently appeared in this journal are put into perspective.

ISSN:0160-5682    

DOI:10.1057/jors.1990.50

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA simulation study of an automated guided-vehicle system connected with an automated vertical transportation system in a large hospital is described. The aim of the study was to determine the allocation and size of storage space for vehicles, the minimum number of vehicles required, the accomplishment of a transportation-network timetable and the queueing situation in the system. This study is part of a simulation study of internal transportation in the new, 1100-bed University Hospital in Zagreb, Yugoslavia, which is under construction.

ISSN:0160-5682    

DOI:10.1057/jors.1990.51

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper describes the results of a study of the feasbility and cost- effectiveness of using mixed Prolog/Fortran programming to develop flexible, reconfigurable battle simulations, replacing large Fortran programmes which are difficult to modify. A mixed-system architecture is developed, in which Fortran and Prolog are each used to best advantage, and which allows discrete events to be combined with pseudo-continuous processes. The architecture is analysed in terms of a number of performance metrics. The paper concludes that the mixed architecture is feasible, practicable and brings a variety of benefits.

ISSN:0160-5682    

DOI:10.1057/jors.1990.52

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper describes an empirical study of the variability of simulation estimates, which produced some interesting new results. Simulation estimates are determined by the input samples. Any input sample can be divided into two basic features: the set of input values and their sequence. Based on this idea, the individual contribution of each feature to the estimates' variance can be empirically studied. This is done following a two-way factorial experiment. Using the standard random sampling approach, the set of values was found to affect most simulation estimates in a common way, and to play a relevant role in their variability. The sequence effect, however, was found to be problem-dependent. Apart from providing a better understanding of the estimates' variability, this study contributes to the proposal of a new sampling approach in simulation: descriptive sampling.

ISSN:0160-5682    

DOI:10.1057/jors.1990.53

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe process allocation problem (PAP) concerned with the assignment of a number of communicating processes to a certain number (not known apriori) of identical processors in a telecommunications environment is examined. The objective is to minimize the total message-passing between processes residing on different processors subject to constraints on the processing power and storage c apacity (code-, data-storage and occupancy) of the processors. Constraints imposed on the co-location of certain processes on the same processor are also included. The problem is formulated as a 0-1 linear maximization problem, taking into account only the number of processes involved, while the number of processors required is produced automatically with the optimum solution. An implicit enumeration algorithm is developed which produces an optimum message-passing allocation. Computational results of a set of random problems which have similar characteristics to a real-world application in telecommunications are also presented.

ISSN:0160-5682    

DOI:10.1057/jors.1990.54

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA three-dimensional, time-minimizing (bottleneck) assignment problem consists of assigningnjobs tonworkers to be performed onnmachines under different forms of feasibility conditions so that the different functions of the individual times taken by a worker to finish a job on a given machine are minimized. The usual assumption made in such a problem is that all the jobs can be commenced simultaneously. In this paper, two specially structured precedence constraints on jobs are considered, which necessitate modifications in this assumption. Further, the main purpose here is to develop branch-and-bound-type algorithms for solving the corresponding problems and to illustrate them by a numerical example.

ISSN:0160-5682    

DOI:10.1057/jors.1990.55

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThis paper develops optimal inventory-management rules for ann-item system supplied by a common vendor and with constant demand rates for the various items. The model allows planned stockouts, whose optimal values are determined on the basis of the total cost minimization.

ISSN:0160-5682    

DOI:10.1057/jors.1990.56

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractA decision-maker, using mathematical programming optimization models, is often faced with a choice of many alternative solutions optimizing the objective function. The decision may be based on secondary, tertiary or higher-order objectives. Such problems are usually handled using goal programming (GP) with pre-emptive priorities. Pre-emptive prioritization is discussed in the literature in the context of GP. This paper suggests that the two are separable, and presents algorithms to accomplish this. It argues that in a truly pre-emptive situation, direct lexicographical optimization of the objectives, without introduction of goals, has a number of advantages. In addition, when applied to special structure models such as transportation or assignment, this approach enables one to maintain the structure and hence the efficiency of those algorithms.

ISSN:0160-5682    

DOI:10.1057/jors.1990.57

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1990.58

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor