摘要:

AbstractSince the middle 1970s, urban communities in Sweden have been compelled to plan under increasing political, social and economic uncertainties. After a long spell of crisis management, urban planners have come to realize the need to plan with uncertainty. That implies an explicit understanding of the implications of quantitative as well as qualitative uncertainty. Various approaches for this type of planning have been experimented with, in different urban communities. This paper discusses the application of futures studies in the Municipality of Västerås and of the strategic choice approach in the Municipality of Köping. The aim of the comparative study is to relate the experience in applying the two methodologies and to evaluate the issues as well as contexts to which the two methodologies can be applied.

ISSN:0160-5682    

DOI:10.1057/jors.1993.46

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper outlines the development of an integrated mathematical model of an aluminium smelter incorporating the raw materials feed, carbon bake, rodding, potrooms and ingot mill areas, together with non-linear feedback loops. The model is structured to facilitate its use for planning and managing both technological and economic change.

ISSN:0160-5682    

DOI:10.1057/jors.1993.47

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThere are well-established legal procedures that have to be followed when a school is proposed for closure in the UK. A reasoned case has to be made for the closure of the school and consultation with interested parties has to take place. This is an ideal opportunity for Community Operational Research to get involved. However, school closures are the result of a political programme, and a response which is based on analysis rather than on political pressure may simply be ignored, no matter how convincing the argument. This paper discusses the role of the Community Operational Researcher as a source of expert advice in a complicated issue. It is argued that, in this particular case, OR analysis served only to expose the impotence of individuals when faced with arbitrary administrative decisions.

ISSN:0160-5682    

DOI:10.1057/jors.1993.48

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn multiple sourcing, replenishment orders for one stock item may be placed at the same time with several suppliers. In order to determine the re-order level and the size of the buffer stock, we then need to estimate the mean and variance of the effective lead time, i.e. the smallest of the lead times. Previous work on this topic has assumed that the mean and variance are either known or may be estimated from large samples, but the number of observations typically available is small. This paper presents a Bayesian approach to the problem when the lead times are independent and normally distributed, although it is shown that the method may be used in more general circumstances. The computational procedures are described and illustrated with an example.

ISSN:0160-5682    

DOI:10.1057/jors.1993.49

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn this paper, the notion of duality and a generalized methodology to identify the dual for an Erlang distribution-based truncated steady-state queueing process is suggested. This procedure provides insight into truncated queueing processes. At first glance, the relationship between the primal problem and the dual problem may not be intuitive. Several such relationships are identified. For example, the dual of theM/Es/C/Cqueueing process is shown to be theM/M/1 machine interference problem withCmachines and the solution to one of these provides the solution to the other. An example is presented.

ISSN:0160-5682    

DOI:10.1057/jors.1993.50

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractAn algorithm for solving a special capacitated multicommodityp-median transportation problem (CMPMTP), which arises in container terminal management, is presented. There are some algorithms to solve similar kinds of problems. The formulation here is different from the existing modelling of thep-median or some related location problems. We extend the existing work by applying a Lagrangean relaxation to the CMPMTP. In order to obtain a satisfactory solution, a heuristic branch-and-bound algorithm is designed to search for a better solution, if one is possible. A comparison is also made with different algorithms.

ISSN:0160-5682    

DOI:10.1057/jors.1993.51

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractWe present a class of bulk server queueing models encountered in material handling and public transportation systems. Customers arrive according to the Poisson process and server visits form a Markov renewal process. Results for the queue length at steady state are obtained and a numerical example using observed data is presented.

ISSN:0160-5682    

DOI:10.1057/jors.1993.52

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractWe describe three simple heuristics for the vehicle routeing problem with customer time windows that can be violated by paying appropriate penalties. The customer demands are known, and a homogeneous fleet of vehicles stationed at a single depot is considered. The penalty payable to a customer is assumed to be a linear function of the amount of time window violation. Upper limits are imposed on both the penalty payable and the waiting time allowed at any customer. At each customer in a route, the PC-based heuristics simultaneously determine the actual time to begin service, and the next customer to serve. To achieve this, each heuristic uses different measures to compare the cost of waiting and penalty payable, with the benefit obtained by leaving immediately for the next customer. Computational results on a set of benchmark problems show that the procedure is efficient and enables significant reduction in the number of vehicles required and/or the total route distances while controlling both customer penalties and waiting times.

ISSN:0160-5682    

DOI:10.1057/jors.1993.53

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThe petal method for vehicle routeing imposes special structure on the form of a feasible route. In this paper we show that by extending the definition of a petal route, more general forms of vehicle route can be generated without invalidating the important underlying property that optimal petal solutions can be produced very easily. It will also be shown that the optimal generalized petal solution can be produced efficiently by multiple applications of a shortest path algorithm.

ISSN:0160-5682    

DOI:10.1057/jors.1993.54

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper presents a planning/budgeting scheme for hierarchical systems. A multi-objective network optimization model for multilayer budget allocation is suggested. The network presents the hierarchical structure of the system. The budget allocations are the flows in the network. Each component in the system (arc in the network) has lower and upper bounds. The model maximizes the additive utility function of the system, expressed as a weighted summation over the preferences of the system's components in the various levels. The preferences are evaluated by using a multigoal approach, utilizing the Analytical Hierarchy Process (AHP). Finally, the model is conceptually compared with other known budgeting procedures and models, such as ZBB, PBBS and cost benefit analyses.

ISSN:0160-5682    

DOI:10.1057/jors.1993.55

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor