1,721,016 research outputs found
An ANN approach in predicting solar radio enhancements at 11 cm wavelength
No full textOral presentation at conferenc
The mathematical modelling of MHD flows
No full textThe goal of this paper is to investigate the foundations of the mathematical modelling for turbolent MHD , with particular reference to incompressible fluids. A closely related issue involves the construction of phase-space approaches for ideal fluids (i.e., fluids descrbed as continuum media). Indeed, phase-space techniques are
well known both in classical and quantum fluid dynamics. In fact, generally the fluid equations represent a mixture of hyperbolic and elliptic PDE's, which are extremely hard to study both analytically and
numerically. This has motivated in the past efforts to replace them with other equations, possibly simpler to solve or mathematically more elegant. In this connection a particular viewpoint is represented by the class of so-called inverse problems, involving the search of
a so-called inverse kinetic theory (IKT) able to yeald the complete set of fluid equations for the fluid fields, via a suitable correspondence principle. A basic consequence of the theory is the possibility of explicitly identifying the phase-space dynamical system which advances in time the complete set of fluid fields. An interesting open
question, lying at the very heart of turbulence theory, is whether such a dynamical system is variational or not and in particular if it is Hamiltonian or not. The possible solution of the problem has potential important theoretical implications. Indeed, a fundamental issue is
whether the usual concepts of chaotic dynamics can be applied to the interpretation of turbulence. The purpose of this note is to present an answer to this question
A tentative estimate of Space Paleoclimate relevant to the Geospace in an astrobiological framework
No full textOral presentation at conferenc
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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