1,721,084 research outputs found
Varietà di Segre e di Veronese
Full text linkL'obbiettivo della tesi è presentare due esempi classici di varietà proiettive: le varietà di Segre e di Veronese. Inizialmente si presentano alcuni risultati generali sugli insiemi algebrici affini e proiettivi, sugli anelli graduati e gli ideali omogenei, sulla corrispondenza tra insiemi algebrici proiettivi e ideali omogenei radicali e si costruisce la topologia di Zariski di Pn. Si costruiscono poi le varietà di Segre e le varietà di Veronese e si conclude con alcune considerazioni sulla cubica gobba
Fluctuations in two-dimensional reversibly dampedturbulence
No full textG. Gallavotti has recently proposed an equivalence principle, in hydrodynamics, which states that the properties of forced-damped fluids can be equally well represented by means of the Navier-Stokes equations and by means of special time reversible dynamical systems called GNS. In the GNS systems, the ordinary, irreversible, dissipation is replaced by a state-dependent dissipation which fixes one global quantity. The principle then states that the mean values of properly chosen observables should be the same for both representations of the fluid. In the same paper, the chaotic hypothesis of Gallavotti and Cohen is extended to hydrodynamics, leading to the conjecture that entropy fluctuations in the GNS system should verify a relation first observed in nonequilibrium molecular dynamics. We tested these ideas in the case of twodimensional incompressible fluids. We examined the fluctuations of global quantities, such as the energy and the enstrophy, in the statistically stationary state o..
MODELLAZIONE NUMERICA DELLE COLATE DETRITICHE CON IL METODO DEGLI AUTOMI CELLULARI
No full textLa simulazione del meccanismo evolutivo di colate deteitiche è svolta con un modello numerico tridimensionale basato sul Metodo degli Automi Cellulari. Le equazioni alla base del modello sono la conservazione della massa e una legge costitutiva per il flusso multifase. Il modello è validato con back-analysis di un caso real
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
Analysis of Laboratory Surface Wave Data using the Scattering Transform for the Periodic Korteweg-de Vries
No full textVariations 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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