1,720,973 research outputs found
"Liquid silicates at Cassis ; a conference report"
No full textBottinga Yan, Calas Georges, Coutures Jean-Pierre, Mathieu Jean-Claude. "Liquid silicates at Cassis ; a conference report". In: Bulletin de Minéralogie, volume 106, 1-2, 1983. Silicates liquides
Verres, liquides et transition vitreuse
No full textSilicate glasses are usually produced through the cooling of a liquid. The vitrification process is not gradual or continuous : it is characterized by discontinuities in second order thermodynamic properties (Cp , a, k...). This is the glass transition. In this paper, we give a qualitative description of the glass transition, and we discuss its thermodynamical aspects and its relevance to the theories of transport phenomena. We examine also the composition dependence of the glass transition and certain differences between silicate glasses and liquids.Les verres silicatés sont habituellement formés par refroidissement d'un liquide. Loin d'être graduel ou continu, le passage du liquide au verre est marqué par des discontinuités des propriétés thermodynamiques du deuxième ordre (Cp , a, k...). C'est la transition vitreuse. Nous en donnons une description qualitative, avant de présenter ses aspects thermodynamiques et son lien avec les phénomènes de transport. Cette note se termine par un bref examen de la variation de la transition vitreuse avec la composition, et par quelques exemples illustrant les différences entre les propriétés des verres et des liquides silicatés.Richet Pascal, Bottinga Yan. Verres, liquides et transition vitreuse. In: Bulletin de Minéralogie, volume 106, 1-2, 1983. Silicates liquides
Application of a percolation model to supercooled liquids with a tetrahedral structure
No full textThe unusual properties of liquid water are explained by a percolation model which emphasizes the geometrical aspects of the tetrahedral structure of this liquid. Statistics over the molecular distribution give predictions about the thermodynamic properties and their dependence on temperature, pressure and concentration of impurities. The model can be generalized to other liquids with analogous structures, such as liquid silica and silicates.Les propriétés inusuelles de l'eau sont expliquées par un modèle de percolation qui souligne le rôle des aspects géométriques de la structure de ce liquide. Un traitement statistique de la distribution moléculaire permet de prédire les propriétés thermodynamiques de l'eau, et leur dépendance vis-à-vis de la température, de la pression et des teneurs en impuretés. Ce modèle peut être généralisé à d'autres liquides de structure analogue, tels que la silice et les silicates fondus.Teixeira José, Stanley Harry Eugene, Bottinga Yan, Richet Pascal. Application of a percolation model to supercooled liquids with a tetrahedral structure. In: Bulletin de Minéralogie, volume 106, 1-2, 1983. Silicates liquides
Équations d'état pour le CO2 ; application aux inclusions carboniques
No full textCarbonic inclusions are abundant in rocks from the lower crust and upper mantle. Estimations of the P and T of formation of these inclusions is presently only possible when they are filled with pure CO2. For this purpose detailed knowledge of the PVT relations for CO2 are needed up to at least 1,200° C and 20 kbar. After a critical examination, the available PVT data are used to derive a modified Redlich-Kwong equation of state for CO2. Molar volumes, down to 27 cm3/mole are calculated for P and T conditions of interest to earth scientists. The densities of the saturated liquid and gas phase along the two phase curve are given.L'estimation des conditions de formation des inclusions carboniques, abondantes dans les roches de la croûte profonde et du manteau supérieur, n'est pour l'instant possible que pour les inclusions contenant du CO2 pur. Elle nécessite la connaissance des propriétés PVT du CO2 jusqu'au moins 1 200°C et 20 kbar. Les données expérimentales actuellement disponibles sont examinées de façon critique et utilisées pour établir une équation d'état du type Redlich-Kwong, à partir de laquelle les volumes molaires du CO2 sont calculés jusqu'à V = 27 cm3/mole, c'est-à-dire dans tout le domaine d'intérêt géologique et géochimique. On donne également les valeurs des densités en phase liquide et en phase vapeur le long de la courbe à deux phases en fonction de la température, à partir du point triple jusqu'au point critique.Touret Jacques, Bottinga Yan. Équations d'état pour le CO2 ; application aux inclusions carboniques. In: Bulletin de Minéralogie, volume 102, 5-6, 1979. Minéraux et minerais
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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