摘要:

Simple deterministic mathematical models for the spread of common childhood diseases are considered. The population is divided into compartments containing susceptible, infectious and immune individuals. The spread of the disease is modelled by a set of differential equations which describe the transfer of individuals between these classes. Some equilibrium and stability results are described and numerical investigations presented which support the analytical results. In these numerical investigations we pay particular attention to whether the level of disease will damp down to a steady equilibrium value and to various methods of predicting the periods of disease cycles.

ISSN:0020-7721    

DOI:10.1080/00207729008910344

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Some results on modelling the statics of the distillation process and its applications are presented. A theoretical tray-to-lray binary distillation model is developed for describing the steady-state behaviour of composition in response to changes in bottom and reflux flows. Based on this model, a simplified one is elaborated and identified by means of the multivariable linear regression method. This approach makes it possible to find a simple and accurate model for the on-line computer control of distillation plant.

ISSN:0020-7721    

DOI:10.1080/00207729008910345

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A frequency-domain approach to derive stable reduced-order models for a stable linear discrete-invariant system is presented. The method is based on combining the Schwarz approximation with the bilinear transformation. An efficient algorithm that avoids the bilinear transformation is derived by which the bilinear Schwarz discrete models are derived directly in the z-domain. The state-space bilinear Schwarz approximation is also presented by which the lower-order time-domain model matrices are derived by suitable truncation of the original system matrices in the bilinear Schwarz canonical form. The aggregation matrix relating the original system and reduced model state vectors is also derived. A numerical example is included to illustrate the method.

ISSN:0020-7721    

DOI:10.1080/00207729008910346

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An adaptive controller for multi-input multi-output (MIMO) systems is presented, which is able to modify repeatedly the control variables between successive output measurements. This feature makes the proposed approach particularly appealing for the control of composition products of distillation columns when expensive and slow chromatographs are used. The control algorithm is derived by minimizing the predicted error signal, as well as the control increments, over a future control horizon which is suitably selected. Applications to a simulated non-linear model of a binary distillation column demonstrate the effectiveness of the proposed method.

ISSN:0020-7721    

DOI:10.1080/00207729008910347

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

On assuming that a continuous-time time-invariant linear system (CFLS) is reachable or stabilizable, a necessary and sufficient condition is presented that the discrete-time time-invariant linear system resulting from the hold equivalence approximation to the CILS is also reachable or stabilizable. The studies are based on the eigenvalues and eigenspaces of the adjointA*of the system matrixAand the kernel of the adjointB*of the input matrixBappearing in the CILS. A necessary and sufficient condition for the observability or detectability of a CILS to be preserved after discretization is also sought.

ISSN:0020-7721    

DOI:10.1080/00207729008910348

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A combined cost function is posed which includes both H∞sensitivity and disturbance minimization terms, as well as minimum variance tracking error and control signal terms. In some problems the criterion represents the engineering requirements of the designer more realistically than H∞or linear quadratic gaussian (LQG) cost lerms alone. The solution to the combined cost function problem is obtained by using a H∞‘embedding procedure’. This subsumes the H∞part of the problem within a fictitious LQG cost function minimization problem. The selection of the cost function weights to achieve certain design requirements is discussed and a method is proposed which leads to very simple computational procedures. In fact, the computation of the two controllers does not involve an iterative method and only requires the solution of a standard spectral factorization and diophantine and eigenvector equations.

ISSN:0020-7721    

DOI:10.1080/00207729008910349

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In order to develop a new analysis technique for distributed parameter systems (DPS), the array that is a generalization of the vector-matrix is introduced, and the array algebra is constructed, which generalizes the various concepts in the conventional vector-matrix theory. A wide class of DPS is approximately transformed into array dynamical systems by use of the finite element method or the finite difference method. In the array system formulation, the spatial structure of the DPS is preserved, and the formulation is accordingly suitable for the utilization of the spatial-state-distribution pattern (SSDP), which is in a sense the essence of the DPS, to the control. An array optimization problem for an array dynamical system is formulated, and the necessary optimality condiiion is derived by use of the array algebra. The linear quadratic (LQ) problem for a linear array dynamical system is investigated, and the resultant optimal control is the array version of the well-known LQ optimal control and realizes a sort of feedback of the SSDP of the DPS. The array theory developed generalizes the vector-matrix theory and prepares a technique for the system analysis for a wide class of DPS in a unified method and for developing the SSDP feedback control for DPS.

ISSN:0020-7721    

DOI:10.1080/00207729008910350

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper presents a novel approach for solving the problems associated with inputting Chinese characters for processing by digital computers. The idea adopted in solving this problem is that of construction pattern recognition (CPR), and it is developed based on some concepts from the artifical intelligence (AI) field. The method presented here is markedly different from the currently existing inputting methodologies used when dealing with Chinese characters. In our approach, a Chinese character (word) is treated as a graph, rather than as a character of a language. It is then analysed, through pattern recognition, using some computing points associated with the Chinese character in the construction process used. The CPR approach has two basic advantages: (a) it is flexible, in as much as it allows the computer to accept both western and oriental languages; and (b) it offers the most user friendly inputting environment to the end user.

ISSN:0020-7721    

DOI:10.1080/00207729008910351

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Recursive algorithms for on-line combined identification and control of linear discrete-time multivariable systems is presented. A variant of the observable canonical model with one-way coupling form of the state model is used to develop a solution of the problem. Exploiting the canonical structure of the model, the proposed solution turns out to be simpler than that obtained by El-Sherief (1983) and moreover, a combined decentralized state and parameter estimation based control scheme can be developed in three stages. In Stage I, the parameters of the system matrices are estimated by a recursive least-square algorithm or by a normalized stochastic approximation algorithm in decoupled manner. These parameters are then employed for state estimation in Stage 2 using a centralized conventional Kalman filter or by a decentralized adaptive Kalman filter which in turn reduces instrumentation and telemetry costs. Estimated parameters and states are then utilized in Stage 3 to implement the square-root based control law along with the good numerical behaviour of the control problem. The proposed algorithms are tested by considering an example of a third-order state-space model.

ISSN:0020-7721    

DOI:10.1080/00207729008910352

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The concept of linear u-controllability of input-output linear systems is introduced: the relation between the concepts of linear ∧-controllability and u-controllability of input-output systems, and the general stability and general uniform stability of linear systems are studied; a few equivalent descriptions for the stability of a linear system and the uniform stability of a linear system are given; many open questions are posed.

ISSN:0020-7721    

DOI:10.1080/00207729008910353

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor