摘要:

A singularly perturbed discrete control system with two small parameters is formulated as an initial value problem. The process of degeneration affects the corresponding two groups of initial conditions. A singular perturbation method is developed based on double asymptotic power series expansions where the approximate solution is sought in terms of an outer solution and two boundary layer correction solutions. Owing to the interplay between the various steps involved in the actual working of the method, an algorithm is presented. An example is provided to illustrate the proposed method.

ISSN:0020-7721    

DOI:10.1080/00207728708967181

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A reduced bilinear model of a binary distillation column is presented. This model has as control inputs the reflux rate and the heat flow of the reboiler, as perturbations the feed stream and its concentration, and as outputs the distillate and residual concentrations. A bilinear model is simpler than a non-linear one, and more exact than a linear model. Furthermore, its structure allows the design of a control structure via optimal control theory. In this paper, two optimal control schemes designed by the reduced bilinear model have been applied to a column simulated by an analytical model, obtaining a robust control of the process even in the presence of disturbances.

ISSN:0020-7721    

DOI:10.1080/00207728708967182

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Almost all of the issues that decision makers face in actuality involve multiple objectives that conflict in some measure with each other. In such issues, decisions that serve some objectives well will generally satisfy other objectives less well than alternative decisions. This paper is concerned with the personal decision-making problem of deciding where to go for a Ph.D. program in industrial engineering and operations research. The problem is modelled as a multiobjective decision-making problem. Then selected techniques are used to find the best course of action among the various alternatives. The methodology used here is based upon identifying simple underlying preference structures that enable the analyst to break down the assessment of a multidimensional utility function into that of several one-dimensional utility functions.

ISSN:0020-7721    

DOI:10.1080/00207728708967183

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Exact model-following (matching) techniques using output (or state) feedback are proposed for the design of an excitation controller for a two input-output linear time-invariant multivariable model of a turbogenerator with constant excitation voltageEFD, supplying power to an infinite grid. The transfer function matrix of the selected model is such that the design by the exact model-matching method closed-loop system attains enhanced dynamic (stability) characteristics. This constitutes a good indication that the designed excitation controller will be suitable for real implementation.

ISSN:0020-7721    

DOI:10.1080/00207728708967184

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The paper addresses model reduction of large-scale interconnected systems in the component connection model framework. It is shown that model reduction at the component level is equivalent to model reduction at the system level. A general procedure is presented to obtain a reduced-order model when (a) at least one of the components is exactly aggregable, and (b) none of the components are reducible. In the latter case, a reduced-order model is obtained by keeping the key state variables and compensating for the deleted ones using a numerical QL algorithm. An interconnected electric power system example is given to illustrate the proposed procedure.

ISSN:0020-7721    

DOI:10.1080/00207728708967185

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A two-level control strategy consisting of a fast first-level analogue controller for ensuring rapid reduction of tracking error under process disturbance without unacceptable overshoot and a slow second-level digital-analogue robust servo-mechanism controller to ensure asymptotic tracking with disturbance rejection is proposed. Thanks to the inclusion of samplers with an adequately chosen sampling period, the second-level controller comes into action essentially after the first-level controller has ceased its action. An interactive design procedure for the determination of the parameters of the controller is given. Simulation results comparing the proposed controller with conventional one-level controllers, such as the analogue, the digital and the digital-analogue controller, are presented.

ISSN:0020-7721    

DOI:10.1080/00207728708967186

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The new technique of data envelopment analysis is generalized for stochastic and dynamic cases with some empirical applications emphasizing issues of robustness and sensitivity.

ISSN:0020-7721    

DOI:10.1080/00207728708967187

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A comparative evaluation is performed empirically for two portfolio efficiency frontiers based on mutual funds over 1945-64 and 1965-83. One is the linear capital market line and the other is a non-linear mean variance frontier. Evidence points to the superiority of the estimated non-linear efficiency frontier over the linear frontier in terms of econometric and other criteria.

ISSN:0020-7721    

DOI:10.1080/00207728708967188

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A class of minimax investment portfolio which minimizes the maximum of suitably-defined risk is analysed theoretically and its relation to Markowitz efficient portfolios is evaluated. It is shown that minimax portfolios possess some robustness properties not shared by Markowitz efficient portfolios. An empirical application of the minimax risk frontier over Jensen's data set shows its superiority in explanatory power and robustness.

ISSN:0020-7721    

DOI:10.1080/00207728708967189

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A set of criteria for comparing efficient portfolios is critically reviewed here to show the inadequacy of the standard mean variance criterion used in traditional portfolio theory. These criteria emphasize, among other things, the following: (a) robustness, (b) multivariate distance as a measure of dissimilarity, and (c) diversity as an entropy measure related to information theory.

ISSN:0020-7721    

DOI:10.1080/00207728708967190

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor