1,720,953 research outputs found
Etude cinétique et mécanistique en liquéfaction directe du charbon : Impact des conditions opéartoires et dusolvant donneur d'hydrogène
No full textThis work deals with the understanding and the modeling of coal hydroliquefaction mechanisms, more precisely the impact of operating conditions and H-donor solvent -hydrogen gas phase-catalyst interactions. Experimental tests are performed in a batch reactor by using Illinois #6 coal, tetralin and NiMo/Al2O3 catalyst. An original separation procedure is developped, combinig micor-distillation and solvent extraction. Complete mass balances allow the dtermination of conversion, product yields and product quality. Operating conditions studied are temperature (380° C-420°C), hdrogen pressure (16-22 MPa) and NiMo/Al2O3 presence. Temperatures mainly impacts the firs stage of liquefaction (also called dissolution), hydrogne pressure and catalyst the products quality. Then, tests performed with other solvents (n-undecan or diethylbenzene) and/or under N2 pressure have shown the crucial impact of solvent on the first stage of liquefaction, and and the high impact of gas phase o products quality. These experimental results allow the establishment of kinetic model. In a first step, maceral are transformed into coke, preasphaltenes and hydrotreatment products. Coke formation only depends on temperature. However, preasphaltenes and hydrotreatment products formation highly depends on solvent. Other products (asphaltenes, vacuum distillate, middle distillate, light distillate and gas) are producted from preasphaltenesL’objectif de la thèse est de comprendre et de modéliser les principaux phénomènes chimiques qui gouvernent les performances du premier réacteur, et en particulier le rôle du solvant donneur d’hydrogène, ainsi que les interactions entre charbon, solvant, hydrogène gazeux et catalyseur. L’impact des conditions opératoires telles que la température, la pression d’hydrogène, le temps de séjour ainsi que l’impact de la qualité de la charge (type de charbon et teneur en cendres) et du type de solvant ont également été évalués. Ce travail s’articule autour d’une partie expérimentale réalisée en autoclave et d’une partie modélisation basée sur un schéma réactionnel simplifié et sur un regroupement par familles chimiques. Dans un premier temps, la partie expérimentale a consisté à mettre au point une stratégie adaptée à l’étude. L’outil utilisé est un réacteur batch de type autoclave fonctionnant jusqu’à 25 MPa et 450°C qui sont des conditions opératoires classiques en hydroliquéfaction du charbon. La charge de référence utilisée est un charbon Illinois n°6, bien connu dans la littérature. Le solvant utilisé est le 1,2,3,4-tétrahydronaphtalène (tétraline) qui est une molécule naphténo-aromatique potentiellement donneuse d’hydrogène et qui a été couramment utilisée au laboratoire pour ce type d’étude. Enfin, un seul catalyseur sulfuré NiMo/Al2O3 a été testé, l’objectif de cette étude ne portant pas sur ce paramètre. Un protocole spécifique de post-traitement a été optimisé pour séparer les différentes fractions de liquéfiats produits, avant leur caractérisation. La démarche originale mise en place dans ce travail a consisté à fractionner les liquéfiats par microdistillation à bande tournante (50 plateaux théoriques) puis à fractionner la coupe résidu sous vide via des extractions par solvants. La microdistillation a ainsi permis de séparer les liquides en quatre coupes : Pi-230°C, 230-350°C,350-450°C et 450°C+, avec une bonne performance de séparation, isolant notamment la quasi totalité du solvant dans la fraction légère, performance difficile à atteindre sur des outils plus classiques. Chacune de ces coupes a été analysée en distillation simulée par chromatographie gazeuse et par analyses élémentaires CHONS. Le résidu sous vide (450°C+) a ensuite été fractionné en huiles lourdes, asphaltènes et préasphaltènes, par solubilité dans l’heptane et le toluène respectivement. Ce protocole a été appliqué à chacun des 66 essais de liquéfaction réalisés dans l’autoclave, ce qui a permis d’effectuer des bilans matières complets et d’évaluer l’impact des conditions opératoires, des interactions solvant-phase gaz-catalyseur et des différentes charges. Pour chaque bilan, le taux deconversion, les structures de rendements et les performances en hydrotraitement ont été déterminés ainsi que la répartition entre la phase gaz et le solvant dans l’hydrogénation du charbon
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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