1,721,909 research outputs found
The four-element Chua`s circuit
No full textA new circuit configuration, linearly conjugate to the standard Chua`s circuit, is presented. Its distinctive feature is that the equations now admit an additional parameter, which controls the dissipation in the network connected to the Chua diode. In the limiting case we obtain the simplest chaotic circuit, consisting of a piecewise-linear resistor and three lossless elements
An inductor-free realization of the Chua`s circuit based on electronic analogy
No full textAlthough literature presents several alternatives, an approach based on the electronic analogy was still not considered for the implementation of an inductor-free realization of the double scroll Chua`s circuit. This paper presents a new inductor-free configuration of the Chua`s circuit based on the electronic analogy. This proposal results in a versatile and functional inductorless implementation of the Chua`s circuit that offers new and interesting features for several applications. The analogous circuit is implemented and used to perform an experimental mapping of a large variety of attractors.National Counsel of Technological and Scientific Development (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)State of Minas Gerais Research Foundation (FAPEMIG)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)State of Sao Paulo Research Foundation (FAPESP)Gorceix Foundation and Texas Instruments Inc.,Gorceix Foundation and Texas Instruments Inc.
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
Nonlinear control of the Chua´s oscillator
No full textEn el presente trabajo se aborda el diseño de controladores para estabilización de puntos de equilibrio y seguimiento de trayectorias para el oscilador de Chua con dinámica caótica. La metodología empleada para sintetizar los controladores es la linealización por retroalimentación del estado y cambio de coordenadas. Se prueba que el oscilador de Chua se puede linealizar entrada-estado y entrada-salida. También se resuelve el problema de acoplamiento a un modelo de referencia, tomando como planta al oscilador de Chua caótico y como modelo de referencia un segundo oscilador de Chua en diversos estados estacionarios. Los controladores diseñados se validan mediante simulaciones y experimentalmente. También se evalúan su robustez ante incertidumbre paramétricas. Se demuestra que los controladores linealizantes diseñados por el oscilador de Chua permiten estabilizarlo entorno a un punto de equilibrio y, también llevar a cabo tareas de seguimiento de trayectorias de dinámica lenta. Se prueba para el acoplamiento a modelos, que el conjunto controlador-planta es capaz de acoplar la dinámica del modelo de referencia.In this work we deal with the design of stabilization and tracking nonlinear controllers for chaotic Chua´s oscillator drive by a control input. We prove that the controlled Chau´s oscillator is input-state and input-output feedback linearizable. We also solve the model-matching problem tanking as the plant the controlled Chau´s oscillator in chaotic regime and as the reference model another Chau´s oscillator (autonomous) in several steady states. The controllers robustness is investigated when there exists some uncertainty in the plants. We show that the feedback linearizable controllers for Chau´s oscillator exhibit good performance in stabilization and slow-dynamics trajectory tracking tasks. Besides we prove that the controller-plant set is able to produce the dynamics of the reference model in the model-matching problem
Experimental characterization of nonlinear systems: a real-time evaluation of the analogous Chua`s circuit behavior
No full textThis paper presents an experimental characterization of the behavior of an analogous version of the Chua`s circuit. The electronic circuit signals are captured using a data acquisition board (DAQ) and processed using LabVIEW environment. The following aspects of the time series analysis are analyzed: time waveforms, phase portraits, frequency spectra, Poincar, sections, and bifurcation diagram. The circuit behavior is experimentally mapped with the parameter variations, where are identified equilibrium points, periodic and chaotic attractors, and bifurcations. These analysis techniques are performed in real-time and can be applied to characterize, with precision, several nonlinear systems
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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