1,721,305 research outputs found
Lineamenti vulcanologici dell’Isola Deception (Arcipelago delle Shetland Australi, Antartide)
No full textNel corso di un viaggio per mare attraverso il Canale di Drake, da Ushuaia nella Terra del Fuoco argentina alla Penisola Antartica, è stato effettuato un approdo all’isola vulcanica di Deception dove sono state svolte osservazioni geologiche e raccolti diversi campioni di rocce che, insieme ad altri prelevati in precedenti spedizioni italiane, sono stati in seguito sottoposti ad analisi petrografiche e geochimiche. Il presente lavoro illustra i risultati delle osservazioni vulcanologiche che hanno consentito di definire gli aspetti principali del magmatismo che caratterizza l’isola e di riconoscere le più importanti fasi eruttive che hanno portato alla costruzione degli apparati vulcanici dell'Isola Deception
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
Polynomial filtering of discrete-time stochastic linear systems with multiplicative state noise
No full textIn this paper, the problem of finding an optimal polynomial state estimate for the class of stochastic Linear models with a multiplicative state noise term is studied. For such models, a technique of state augmentation is used, leading to the definition of a general polynomial filter, The theory is developed for time-varying systems with nonstationary and non-Gaussian noises. Moreover, the steady-state polynomial filter for stationary systems is also studied, Numerical simulations show the high performances of the proposed method with respect to the classical Linear filtering techniques
Polynomial filtering for linear discrete time non-Gaussian systems
No full textIn this work we propose a new filtering approach for linear discrete time non-Gaussian systems that generalizes a previous result concerning quadratic filtering [A. De Santis, A. Germani, and M. Raimondi, IEEE Trans. Automat. Control, 40 (1995) pp. 1274-1278]. A recursive nu th-order polynomial estimate of finite memory Delta is achieved by defining a suitable extended state which allows one to solve the filtering problem via the classical Kalman linear scheme. The resulting estimate will be the mean square optimal one among those estimators that take into account nu-polynomials of the last Delta observations. Numerical simulations show the effectiveness of the proposed method
OPTIMAL QUADRATIC FILTERING OF LINEAR DISCRETE-TIME NON-GAUSSIAN SYSTEMS
No full textIn this work, the state estimation problem for linear discrete-time systems with non-Gaussian state and output noises is dealt with. By following a geometric approach, an optimal recursive second-order polynomial estimate is proposed, which actually improves the widely used optimal linear one
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