1,721,129 research outputs found
Kotenkaisekigaku ni okeru hokanmondai to Most Powerful Unfalsified Model (MPUM)
No full textThis review article (in Japanese) presents the essentials of exact identification. Particular attention is given to the formalization of interpolation problems involving stability- and metric constraints (e.g. the Nevanlinna and the Takagi interpolation problems) in the framework of exact identification, and the representational issues for the Most powerful Unfalsified Model arising in these applications
On the Takagi interpolation problem
No full textIn this paper we approach the interpolation problem of Takagi from the perspective of time-series modeling. The framework of exact identification and the notion of MPUM are used in order to generalize some results on the Nevanlinna interpolation problem. These results are of independent interest and concern the relation between the roots of the determinant of the denominator of an unfalsified model, and the signature of the Pick matrix of the data
An algorithm for the spectral factorization of unimodular para-hermitian polynomial matrices in continuous time
No full textIn this paper, we address an algorithm for the spectral factorization of para-Hermitian unimodular polynomial matrices in the continuous time case. Most of the algorithms for the spectral factorizations of matrix polynomials depend on the existence of the roots of given polynomial matrices, so it is almost impossible to execute the spectral factorization of unimodular polynomial matrices. In this paper, we provide a new algorithm for the spectral factorization of unimodular polynomial matrices without the existence of the roots of polynomial matrices or the stability. The task one has to do is only to solve a linear matrix inequality consisting of the coefficients of a given unimodular matrix, which can be achieved easily by the use of numerical computation packages. The algorithmwe present here is based on the property of the storage functions for the dissipative systems in which there always exists positive dissipated energy for the environment. This implies that the fundamental property in our algorithm is also a self-standing interesting result with respect to theoretical points of view. Finally, in order to show the validity of our results, we give an illustrative example with respect to numerical aspects
Recursive exact H-infinity identification from impulse-response measurements
No full textWe study the H∞-partial realization problem from a behavioral point of view; we give necessary and sufficient conditions for solvability, and a characterization of all solutions. Instrumental in such analysis is the notion of time- and space-symmetrization of the data, which allows to transform the realization problem with metric- and stability constraints into an unconstrained behavioral modeling one
Totally dissipative systems
No full textIn a totally dissipative behavior, all non-trivial trajectories dissipate energy. A characterization of such behaviors is given in terms of properties of the one- and two-polynomial matrices associated with the supply rate and with their kernel- and image representation
Characterization of solutions of the discrete-time algebraic Riccati equation based on quadratic difference forms
No full textThis paper is concerned with a characterization of all symmetric solutions to the discrete-time algebraic Riccati equation (DARE). Dissipation theory and quadratic difference forms from the behavioral approach play a central role in this paper. Along the line of the continuous-time results due to Trentelman and Rapisarda [H.L. Trentelman, P. Rapisarda, Pick matrix conditions for sign-definite solutions of the algebraic Riccati equation, SIAM J. Contr. Optim. 40 (3) (2001) 969–991], we show that the solvability of the DARE is equivalent to a certain dissipativity of the associated discrete-time state space system. As a main result, we characterize all unmixed solutions of the DARE using the Pick matrix obtained from the quadratic difference forms. This characterization leads to a necessary and sufficient condition for the existence of a non-negative definite solution. It should be noted that, when we study the DARE and the dissipativity of the discrete-time system, there exist two difficulties which are not seen in the continuous-time case. One is the existence of a storage function which is not a quadratic function of state. Another is the cancellation between the zero and infinite singularities of the dipolynomial spectral matrix associated with the DARE, due to the infinite generalized eigenvalues of the associated Hamiltonian pencil. One of the main contributions of this paper is to demonstrate how to resolve these difficulties
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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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