Sensitivity tradeoffs for multivariable plants

This paper gives a characterization of the smallest upper bound on the norm of the sensitivity matrix over a frequency interval, with the constraint that the norm remain bounded at all frequencies. The matrix Nevanlinna-Pick interpolation theory is applied to give a necessary and sufficient condition for the existence of a sensitivity matrix meeting the upper bound conditions on thejomega-axis, and the matrix Nevnnlinna-Pick algorithm is used to compute the bounds. A scalar example is also presented to demonstrate the tradeoffs between the bounds inside and outside a given operating frequency band.     

A review of instrumentation and therapeutic techniques in the diagnosis and management of supraventricular tachycardia

Paroxysmal supraventricular tachycardia can usually be managed without any specific therapy or with an appropriate drug program. Some patients, however, are resistant to conventional therapy. In the past decade, the electrophysiologic pathogenic mechanisms of this rhythm disorder have been elucidated, and this, coupled with progress in intracardiac instrumentation, has enabled the physician to induce specific rhythm disorders and to map them to determine an ideal, specially tailored method of treatment. As a result, the use of radiofrequency pacing and surgery are becoming increasingly important in the treatment of patients with paroxysmal supraventricular tachycardia, especially those with arrhythmias related to Wolff-Parkinson-White syndrome.     

Some computational results on size reduction inH∞ design

The authors explore the properties of the algebraic Riccati equation. New results on the rank of the solution to the algebraic Riccati equation are obtained and lead to an efficient algorithm for reducing the size of the antistable transfer function matrix in the model-matching problem. In the 1-block problem, the method is taken further to obtain explicit formulas for a minimal realization of the matrix. The approach is direct and numerically reliable as it is based almost entirely on orthogonal transformations     

Discrete approximation and supervisory control of continuoussystems

Addresses the following hybrid control problem: a continuous plant (its state evolving in Euclidean space) is to be controlled via symbolic output feedback-both measurement and control signal “live” on finite sets of symbols. We adopt the following approach: the hybrid problem is first translated into a purely discrete problem by approximating the continuous plant model by a (nondeterministic) finite-state machine. By taking into account past measurement and control symbols, approximation accuracy can be improved and adjusted to the specification requirements. Supervisory control theory for discrete-event systems (DES) is then applied to find the optimal controller which enforces the specifications. As the behavior of the approximating automaton is guaranteed to contain the behavior of the underlying continuous plant model, the controller also forces the latter to obey the specifications     

A treatment of jw-axis model-matching transformation zerosin the optimal H2 and H∞control designs

A model-matching transformation (MMT) zero is defined as a rank-deficiency condition which prevents an H² or H^∞ optimal control problem from being transformed into an equivalent model-matching problem. By imposing saturation constraints and accounting for additive instrument noise in the sensor and actuator signals, all MMT zeros can be eliminated     

Survey of Techniques for Measuring RF Shielding Enclosures

An intensive literature survey has been conducted to review existing techniques for measuring the effectiveness of RF shielding enclosures. Prevalent methods of measuring E- and H-field components and for sensing the total field are discussed and evaluated. The procedures described in the literature are tabulated into groups determined by their similarities in method or theory and are compared by listing the advantages and disadvantages inherent in each. (A weighting system is devised to aid in evaluating each of the principal methods discussed.) Also discussed are the theoretical considerations underlying each of the methods listed, as applicable to the measurement of shielding effectiveness. Among these are the concepts of the resultant wave impedance of the E-M field at a point inside a shielded enclosure and the relationship of low-impedance and high-impedance fields in the near field regions of antenna systems. Techniques for extending the frequency and intensity of illuminating fields are also discussed, as well as the insertion loss method of determining leakage from a shield. Limitations and deficiencies of this latter procedure are noted.     

Discrete Supervisory Control of Hybrid Systems Based on l-Complete Approximations

The topic of this paper is the synthesis of discrete supervisory control for hybrid systems with discrete external signals. Such systems are in general neither l-complete nor can they be represented by finite state machines. Our solution to the control problem is as follows: we find the strongest l-complete approximation (abstraction) _l for , represent it by a finite state machine, and investigate the control problem for the approximation. If a solution exists on the approximation level, we synthesize the maximally permissive supervisor for _l . We show that it also solves the control problem for the underlying hybrid system . If no solution exists, approximation accuracy can be increased by computing the strongest k-complete abstraction _k , k > l. The basic ideas regarding the approximation step are explained within the framework of Willems' behavioral systems theory. Implementation issues are treated in a state space framework, and the main results are interpreted from a traditional control engineering point of view.