摘要:

AbstractThrough the impacts of higher required rates of return, debt, taxation changes and a new competitive structure for the industry, investment in electricity generating capacity has taken a shift to less capital-intensive technologies in the UK. This paper reports on the use of large-scale, long-term capacity planning models, of both an optimization and system dynamics nature, to reflect these separate factors, investigate their sensitivities and to generate future scenarios for the investment in the industry. Some new policy implications for the regulation of the industry become apparent, but the main focus of the paper is to develop some of the methodological changes required by the planning models to suit the privatized context.

ISSN:0160-5682    

DOI:10.1057/jors.1993.165

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractA production shop in Royal Ordnance contains machines which in many cases can be converted to manufacture any of the main products passing through the shop. The task of periodically reconfiguring the lines to match more nearly a given set of demands is a classic mathematical programming problem. A solution and some of its uses are presented as a case study.

ISSN:0160-5682    

DOI:10.1057/jors.1993.166

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractA major copier machine company in Hong Kong presently faces the problem of providing effective servicing and repairing support to its four service regions. Due to the shortage of skilled technicians and the variety of jobs to be handled by technicians of differing skill levels, its Service Department appears to be understaffed, experiencing substantial daily backlogs. This study concentrates on a new perspective of operation: the assignment of technicians at each skill level to specialize in a single type of job in one of the four regions. The objective is to maximize the overall daily number of completed service calls. A mathematical model is developed to handle this specialized allocation problem, where the average travel time (forming part of the coefficient of one of the model's variables) of a technician servicing a type of job in a region is dependent on the decision variables–the composition of the whole team. This results in what we call a mixed integer non-linear programme with variable coefficients. An exact solution is obtained by an iterative algorithm with an overall dynamic programming approach. Sample numerical results are also reported.

ISSN:0160-5682    

DOI:10.1057/jors.1993.167

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractA number of important contributions have been made toward the problem of minimizing the difference in‘customer’treatment on a single machine. However, so far, all the research has been to solve the problem of minimizing the‘job’difference. That is, it is assumed implicitly that each customer places only one job, and hence minimizing the difference in customer treatment is equivalent to minimizing the difference in job treatment. In many practical situations, a customer may place an order which consists of several jobs. The jobs usually can be grouped into different classes. Thus, the range, i.e. the difference between the maximum and the minimum, of order completion times becomes an appropriate performance measure for treating customers equally. In this paper, a dynamic programming (DP) algorithm is developed to provide the optimal solution. Due to the exponential time complexity of the DP algorithm, two heuristic methods are also proposed to solve large-sized problems. Computational results for the heuristics are provided.

ISSN:0160-5682    

DOI:10.1057/jors.1993.168

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn this paper, an optimal operational strategy is developed to optimize the system utilization while controlling the bottleneck problem in a finite capacity integrated assembly line system (consisting of a set of tandem workstations, a set of inspection stations, a loading station and an unloading station, linked by a set of transporter stations). To develop the proposed operational strategy, a stochastic optimization model is developed for selecting the optimal processing rates of the workstations and the transporter stations, such that the total throughput rate from the system is maximized while the resulting probability of finding either a workstation or a transporter station blocked is sufficiently close to zero.

ISSN:0160-5682    

DOI:10.1057/jors.1993.169

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper describes a method by which a neural network learns to fit a distribution to sample data. The neural network may be used to replace the input distributions required in a simulation or mathematical model and it allows random variates to be generated for subsequent use in the model. Results are given for several data sets which indicate the method is robust and can represent different families of continuous distributions. The neural network is a three-layer feed-forward network of size (1-3-3-1). This paper suggests that the method is an alternative approach to the problem of selection of suitable continuous distributions and random variate generation techniques for use in simulation and mathematical models.

ISSN:0160-5682    

DOI:10.1057/jors.1993.170

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper deals with general structure functions, where arbitrary degrees of performance between perfect functioning and complete failure are allowed for each component and then-component system itself. We make the assumption that then-component system can be modelled as a structure function given by a mappingφ:Ln→Lk0,LandL0being two linearly ordered sets, so that the performance of the system is evaluated according toksingle criteria. Global concepts of minimal path and minimal cut are discussed for these multicriteria systems; general reliability bounds based on them are deduced and compared with those given in previous papers.

ISSN:0160-5682    

DOI:10.1057/jors.1993.171

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper gives closed-form expressions, in terms of the roots of certain equations, for the distribution of the waiting time in queue,Wq, in the steady-state for the discrete-time queueGI/G/1. Essentially, this is done by finding roots of the denominator of the probability generating function ofWqand then resolving the generating function into partial fractions. Numerical examples are given showing the use of the required roots, even when there is a large number of them. The method discussed in this paper avoids spectrum factorization and uses both closed- and non-closed forms of interarrival- and service-time distributions. Approximations for the tail probabilities in terms of one or three roots taken in ascending order of magnitude are also discussed. The exact computational results that can be obtained from the methods of this study should prove useful to both practitioners and queueing theorists dealing with bounds, inequalities, approximations, and simulation results.

ISSN:0160-5682    

DOI:10.1057/jors.1993.172

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn this technical note it is shown how a problem of location of two facilities may be formulated as a non-convex optimization problem, and an algorithm is provided to determine anɛ-optimal solution.

ISSN:0160-5682    

DOI:10.1057/jors.1993.173

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1993.174

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor