1,721,704 research outputs found
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
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
A new fuzzy Lyapunov function approach for a Takagi-Sugeno fuzzy control system design
No full textIn this paper, a new fuzzy Lyapunov function approach is presented for a class of continuous-time Takagi-Sugeno fuzzy control system. The proposed fuzzy Lyapunov function is formulated as a line-integral of a fuzzy vector which is a function of the state, and it can be regarded as the work done from the origin to the current state in the fuzzy vector field. Unlike the approaches using a fuzzy blending of multiple quadratic Lyapunov functions, the time-derivatives of membership functions do not appear in the proposed approach. The effectiveness of the proposed approach is shown through numerical examples. (c) 2006 Elsevier B.V. All rights reserved.X11283sciescopu
A Particle Filter Approach to Robust State Estimation for a Class of Nonlinear Systems with Stochastic Parameter Uncertainty
No full textIn this paper, we propose a robust state estimation method using a particle filter (PF) for a class of nonlinear systems which have stochastic parameter uncertainties. A robust PF was designed using prediction and correction structure. The proposed PF draws particles from a simple proposal density function and corrects the particles with particle-wise correction gains. We present a method to obtain an error variance of each particle and its upper bound, which is minimized to determine the correction gain. The proposed method is less restrictive on system nonlinearities and noise statistics; moreover, it can be applied regardless of system stability. The effectiveness of the proposed robust PF is illustrated via an example based on Chua's circuit.open1111sciescopu
Non-coherent and Differentially Coherent code acquisition in MIMO assisted DS-CDMA multi-path downlink scenarios
No full textIn this contribution we investigate both Differentially Coherent (DC) and Non-Coherent (NC) code acquisition schemes in the Multiple Input Multiple Output (MIMO)-aided Direct Sequence-Code Division Multiple Access (DS-CDMA) downlink, when communicating over uncorrelated Rayleigh channels. It is demonstrated that the employment of multiple transmit antennas has a detrimental impact on the achievable diversity gain at typical operational Signal-to-Interference plus Noise Ratios (SINR), as the number of transmit antennas is increased, regardless whether single-path or multi-path scenarios are considered. Our findings suggest that increasing the number of transmit antennas in a MIMO-aided CDMA system results in increasing the Mean Acquisition Time (MAT) by as much as an order of magnitude, when the SINR per chip value is relatively low. The main reasons for the performance trends are plausible, since we have to reduce each individual MIMO element's signal power for maintaining the same total power as in a single-antenna system and this will be further justified by information theoretic considerations in the NC MIMO-aided scenarios considered
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