摘要:

AbstractGiven a daily repeating timetable and locomotives of various types, each timetabled train must be assigned a locomotive. This paper presents an exact algorithm for the solution of this problem, based on an approach used to solve multiple-depot bus scheduling problems. The algorithm is used to solve moderately large scheduling problems drawn from real world data.

ISSN:0160-5682    

DOI:10.1057/jors.1991.163

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper describes work carried out with hospital consultants in Lancaster District Health Authority to develop and use computerized waiting list management models. The‘what if?’models produced have been found to be a very useful tool in the constructive debate about problems faced by consultants and managers, and of the options available to them.

ISSN:0160-5682    

DOI:10.1057/jors.1991.164

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractAn arbitrary policy of fixing the number of outpatient appointments specifying the dates (and not the exact times) of appointments created long queues and large waiting times in some departments of the Ibn-Rochd health centre, but considerable idle time for the consulting doctors in others. After narrating in detail these circumstances and examining a number of possible options, this paper describes the scientific approaches made to determine the number of appointments, the corresponding parameters of the queue and the system and the service per cent occupation.Finite source size, a random number of initial patients, group arrivals, non-exponential service time distribution, late start-up of the servicing unit and many other factors combined to render available theoretical results difficult to apply and results obtained by applying approximately equivalent theoretical models unreliable as compared with those observed in real life. It is shown that simulation could be more profitably applied in such situations.

ISSN:0160-5682    

DOI:10.1057/jors.1991.165

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThe recent developments in stochastic linear programming are reviewed here broadly in their applied aspects. They include non-parametric methods which are applicable in situations of incomplete knowledge and partial uncertainty. This framework is shown to be most suitable for developing robust optimal solutions. For instance, a class of non-parametric methods based on the minimax principle and the criteria of stochastic dominance is developed here to illustrate its wide scope of application. It is shown that this class of methods provides a measure of robustness through the adoption of a cautious policy. Some examples are discussed using the recent field of data envelopment analysis.

ISSN:0160-5682    

DOI:10.1057/jors.1991.166

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractA methodology to manage manufacturing lead times is currently being developed by the authors. The system is specifically designed to address the needs of small- to medium-sized make-to-order companies. It involves a hierarchical production planning system in which integration between the production and marketing functions is facilitated. Considerations of capacity are included at both of the decision levels addressed—the customer enquiry stage and the job release stage. This paper describes the job release stage, showing how it is linked with the higher-level stage by controlling a hierarchy of backlog lengths. At the job release stage the released backlog length for each work centre is maintained between predetermined minimum and maximum levels. It is shown that shop floor throughput times—an important part of manufacturing lead times—can be controlled by controlling released backlog lengths. The releasing mechanism is described and it is argued that there can be many benefits of job release—including reduced shop congestion, lower work-in-progress and lower costs.

ISSN:0160-5682    

DOI:10.1057/jors.1991.167

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractTechniques of development planning involve physical and financial aspects. Financial planning refers to the allocation of monetary resources; in Nigeria the previous development plans and budgets, which had been based on the incremental approach, contained various shortcomings, resulting in the deliberate inflation of estimated expenditure, and consequently it has been associated with retarded growth and conflicts between ministries. In addition, the approach does not adequately relate national objectives to their priorities. Conventional mathematical programming models are unable to allocate resources effectively in a conflicting environment. This paper proposes a goal programming model for allocating a country's scarce resources among competing sectors during a planned period. The goal programming model is shown to be adequate for allocating resources under the conflicting conditions of national planning. The model can help to determine all the priorities for the goals.

ISSN:0160-5682    

DOI:10.1057/jors.1991.168

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractMany heuristics exist for the single-item dynamic lot-size problem, for example, the Silver-Meal, the part period balancing and a simple variant of the part period balancing. The worst case performances of these heuristics have been shown to be zero, 1/3 and 1/2 respectively. These heuristics can be generalized to the dynamic version of the joint replenishment problem, that is, the multi-product dynamic lot-size problem. Such a generalization of the Silver-Meal heuristic has been shown to perform well on a set of test problems. This paper generalizes the part period balancing heuristic, and a simple variant of it to the multiproduct dynamic lot-size problem, and shows that the worst case performances of the generalized heuristics remain 1/3 and 1/2 respectively. An improved version of the generalized Silver-Meal heuristic is also given.

ISSN:0160-5682    

DOI:10.1057/jors.1991.169

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThis paper analyses a worst-case performance of the shortest-processing-time (SPT) heuristic in minimizing a quadratic function of job lateness for single machine scheduling. A sufficient condition on processing-plus-wait due dates is found for the SPT sequence to be optimal. A worst-case lower bound to the optimal solution is derived from the SPT sequence. It is then shown that the SPT sequence is asymptotically optimal. Extensive computational experiments suggest that the SPT heuristic may be a good choice for just-in-time production.

ISSN:0160-5682    

DOI:10.1057/jors.1991.170

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1991.171

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1991.173

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor