A Note on the Problem of Multivariable Adaptive Tracking

In this note we consider the problem of adaptive tracking formultivariable relative degree one, minimum phase systems. Ourapproach is in the spirit of Helmke et al. (1990) who consideredadaptive tracking of sinusoidal reference signals for single-input,single-output systems. The case of relative degree r, single-input,single-output, minimum-phase systems has been considered inMareels (1984). The main contribution we make is in establishingthat the sufficient conditions for universal adaptive tracking,namely minimum phase, relative degree one and the internal modelprinciple, hold for the suitably precompensated plant. Thisenables us to apply the techniques of Helmke et al. (1990).     

On the use of reduced-order models and simulation data in control-system design

This note extends some results on robust control and approximation,to provide a systematic framework for the use of reduced-ordermodels of single-input single-output systems in control systemsdesign where data from a finite number of simulations of theoriginal open-loop system can be used to assess the stabilityand performance of the implemented closed-loop scheme and substantiallyreduce conservatism during the design stage without the needfor a full closed-loop plant simulation.     

SIMULTANEOUS SATURATION OF VARIABLE FLUORESCENCE YIELD AND PHOTOACOUSTICALLY MONITORED THERMAL EMISSION IN THYLAKOID MEMBRANES

Thermal and fluorescence emission from thylakoid membranes were monitored simultaneously in a photoacoustic cell. A close relationship existing between variable fluorescence and variable thermal emissions is demonstrated. The modulated measuring beam of the photoacoustic spectrophotometer was used to study the effect of light intensity on the energy storage yield and on the variable fluorescence yield. The half-saturation light intensities obtained for both parameters were 8.5 and 9.1 W m^?2, respectively. The similar sensitivity of energy storage and variable fluorescence yield to light intensity indicates that electron transfer with plastoquinone as last acceptor is probably responsible for the photoacoustically monitored energy storage.     

Structure indices for multidimensional systems

The structure indices of a one-dimensional system are an importantset of invariants. In this paper we examine a generalizationof this concept to multidimensional linear systems, which correspondsto the algebraic concept of a Hilbert series. We use the standardtheory of the Hilbert series to explain some of the previousID system-theoretic results. We discuss the computation of nDstructure indices from an initial condition set, and the invariantswhich can be derived from these indices.     

Positive-Real Structure and High-Gain Adaptive Stabilization

This paper investigates the use of positive real conditionsin the analysis of high-gain adaptive control rules for linearsystems subjected to nonlinear perturbations of the state andinput.     

On Sensitivity, Compensation, and the Approach to the Asymptotes in Multivariable Root-Loci

Dynamic transformation techniques are used to characterize therate of approach of multivariable root-loci to the asymptotesby calculation of the third term in the Puiseux series usingthe system Markov parameter matrices. The design of compensatorsto eliminate the sensitivity of the pivots to control data issuggested by maximizing the rate of approach to the asymptotes. ^*This work is supported by SERC under grant No. GR/B/79455     

Stability Analysis for Discrete Linear Multipass Processes with Non-Unit Memory

A new set of stability conditions for discrete linear multipassprocesses with non-unit memory is derived and used to developcomputationally feasible stability tests. This results in asystematic procedure which tests these conditions in a particularorder, with termination if the one just tested does not hold.The use of this procedure within the area of control systemsdesign is discussed.