1,721,265 research outputs found
About the Existence of Locally Lipschitz Output Feedback Stabilizers for Nonlinear Systems
No full textInternational audienceIn this paper we complement some results of [L. Marconi, L. Praly, and A. Isidori, SIAM J. Control Optim., 45 (2007), pp. 2277–2298] by presenting a sufficient condition under which the output feedback controller proposed in that paper can be designed to be locally Lipschitz. The condition in question consists in a regularity property of the observable part of an autonomous system with output that generates the control input in a steady state. The work has been deliberately written to be an addendum to [L. Marconi, L. Praly, and A. Isidori, SIAM J. Control Optim., 45 (2007), pp. 2277–2298], to which the reader is referred for notation and main results
Analisi della Popular Music (L. Marconi e R.Agostini, a cura di)
No full textIl numero della "Rivista di Analisi e Teoria Musicale" dedicato all'analisi della pop music, con un florilegio di contributi di vari autori curati da L. Marconi e R. Agostini, offre il destro per una serie di rilievi che vanno, in prospettiva metodologica, dalla liceità epistemologica dell'uso stesso del termine popular alla validità euristica di una distinzione tra analisi a livello sintattico e sub-sintattico, fino a rilievi nel merito dei singoli contributi e delle traduzioni italiane
A note on the design of the robust regulator for non-minimum phase linear systems2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601)
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stabilization for a class of minimum phase hybrid systems under an average dwell-time constraint
No full textWe consider the class of nonlinear systems in normal form with unitary
relative degree whose zero and output dynamics are affected by state
jumps fulfilling an average dwell-time constraint. Under a minimum-phase
assumption requiring the existence of a compact set which is globally
pre-asymptotically stable for the hybrid zero dynamics, we show how to
design continuous, global state- and semiglobal output-feedback control
laws. The proposed design methodology extends to the considered class of
hybrid systems well-known design techniques for robustly stabilizing the
class of continuous-time minimum-phase nonlinear systems having unitary
relative degree. Examples are given to show the usefulness of the technical
result
A zero-dynamics re-design approach to problems of nonlinear output regulation
No full textIn this paper we deal with the problem of output regulation for possibly non-minimum-phase nonlinear systems. The main goal is to provide a unifying framework for a number of recently proposed results. The underlying idea is to use a design paradigm based on zero-dynamics re-design which reduces the problem to a problem of set stabilization using high-gain feedback. In this unified setting, we are also able to show that uncertainties on the value of the so-called "high-frequency gain" coefficient of the system can be effectively handled by means of periodically varying controllers. This extends, to a nonlinear setting, robust zero-assignment techniques known for linear systems as "vibrational feedback". Copyright © 2010 Watam Press
A Note About Hybrid Linear Regulation
No full textWe present some results about the problem of output regulation for a class of hybrid linear systems. We focus on the class of linear systems and exosystems whose dynamics have jumps according to the value of a clock variable, and we address the problem of designing controllers embedding an internal model of the switching exosystem to achieve the regulation objective. This will lead us to generalize concepts and tools well known in the field of output regulation for continuous-time systems, such as the concept of steady-state response, of regulator equations and the internal model property. The actual results are preliminary steps toward the development of a theory of nonlinear hybrid regulation that is under study by the authors
A Note on Robust Output Feedback Stabilization of Nonlinear Nonminimum Phase Systems
No full textThis paper investigates a few issues related to the problem of robust output feedback stabilization of nonlinear non-minimimum phase systems. In order to cope with (unstructured) parametric uncertainties we insist on well-known high-gain design principles which, however, are integrated with robust zero-assignment procedures to handle possible unstable zero dynamics. In this respect we propose two possible zero-assignment arguments. The rst relies upon an output redesign obtained by means of a "feed-through" compensator. Interestingly enough, we show how existing results on this subject can be cast in terms of the resulting feed-through / high-gain design paradigm. In the second, by drawing inspiration from known results for linear systems which go under the name of vibrational-feedback, the output redesign is achieved by using time- varying periodic controllers. Remarkably, we show how the resulting design framework is able to deal also with severe uncertainties in the high-frequency gain of the controlled system by thus obtaining results which turn out to be interesting also in a linear setting. Copyright © 2007 International Federation of Automatic Control All Rights Reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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