摘要:

AbstractThis paper describes aspects of a project in which a computer model (I.C.D.M.) of the longer-term trends in demand for telecommunications media in the U.K. was developed and implemented. The work was undertaken by Cambridge University Engineering Department for the Long Range and Strategic Studies Division of British Telecom. The paper concentrates on the processes of developing and implementing the model as an aid in the formulation of robust investment and marketing strategies for British Telecom in the face of a rapidly changing technological environment and emergent competition. The value of the integrative and dynamic characteristics of the I.C.D.M. in this context is emphasized, and the role of a user-friendly colour graphics interface in encouraging managerial acceptance of the new tool is noted.

ISSN:0160-5682    

DOI:10.1057/jors.1985.198

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractIn two recent papers, the problems of the two-sided nature of shadow prices in degenerate L.P.s have been reviewed. Aukamp and Steinberg demonstrate that shadow prices and the optimal dual variables computed by L.P. packages do not necessarily correspond. Their analysis is completed by Mustafa Akgul, who shows that positive and negative prices can be easily computed by simple auxiliary programmes as well as by parametric programming methods. The original work on this subject by Strum discusses the pricing and accounting aspects of two-sided shadow prices. The purpose of this note is to extend the analysis of Akgul to multiple-objective linear programming (MOLP) models.

ISSN:0160-5682    

DOI:10.1057/jors.1985.199

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractGrowth curves such as the logistic and Gompertz are widely used for forecasting market development. The approach proposed is specifically designed for forecasting, rather than fitting available data—the usual approach with non-linear least squares regression. Two innovations form the foundation for this approach. The growth curves are reformulated from a time basis to an observation basis. This ensures that the available observations and the forecasts form a monotonic series; this is not necessarily true for least squares extrapolations of growth curves. An extension of the Kalman filter, an approach already used with linear forecasting models, is applied to the estimation of the growth curve coefficients. This allows the coefficients the flexibility to change over time if the market environment changes. The extended Kalman filter also proves the information for the generation of confidence intervals about the forecasts. Alternative forecasting approaches, least squares and an adaptive Bass model, suggested by Bretschneider and Mahajan, are used to produce comparative forecasts for a number of different data sets. The approach using the extended Kalman filter is shown to be more robust and almost always more accurate than the alternatives.

ISSN:0160-5682    

DOI:10.1057/jors.1985.200

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractIt has been demonstrated by Takacs that combinatorial methods can be successfully applied to derive certain probability distributions in queueing processes. Mohanty further illustrated the usefulness of combinatorial techniques and determined the stochastic law of the busy period in two queueing systems particularly involving batches. This paper describes an analysis of a simple queueing process based on the number of minimal lattice paths, which is counted in terms of the Catalan number as the special case. The proposed procedure is comparatively convenient and practical.

ISSN:0160-5682    

DOI:10.1057/jors.1985.201

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractThis paper deals with the problem of determining economic maintenance frequency for a group of machines. The operating cost for each machine is assumed to increase with time since the last maintenance work carried out on the machine. The cost of carrying out maintenance work is known and assumed constant. A fixed cost is incurred whenever maintenance work is carried out, and this fixed cost is assumed to be independent of the number of machines on which maintenance work is carried out. The total cost of the system is given by the sum of maintenance and operating costs for all the machines. A heuristic method is proposed for determining the economic maintenance frequency of each machine. An example is given to illustrate the method.

ISSN:0160-5682    

DOI:10.1057/jors.1985.202

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractOn the basis of the growth-rate matrix in co-operating enterprises, this study deals with growth stability as well as the possibility of interpolation and extrapolation of a dynamic growth system. This study also suggests an index of growth stability when a new enterprise is introduced: disequilibrium occurs initially, and stability is gradually reached with the passage of time.

ISSN:0160-5682    

DOI:10.1057/jors.1985.203

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1985.204

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1985.205

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1985.206

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1985.208

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor