1,720,965 research outputs found
Optimization of a pulverized coal injection lance
No full textLa production d’acier est majoritairement basée sur la réduction du carbone contenu dans le charbon et est effectuée par des hauts fourneaux. Le principe global est le suivant : un débit important d’air chaud (1200K) est injecté en même temps que du charbon pulvérisé dans le haut fourneau via une tuyère d’injection. Ceci permet la combustion des matières premières (charbon préchauffé et minerai) et la fonte du minerai de fer. La fonte produite est récupérée à la base du haut fourneau pour être ensuite transformée en acier. Cependant, les réactions de réduction engagées dans le processus de production d’acier sont à l’origine d’émissions de gaz polluants (NOx, …) et de gaz à effet de serre (CO2). Pour contrôler et réduire ces émissions, l’industrie sidérurgique développe de nouvelles technologies. Parmi ces dernières, la capture du CO2 par oxy-combustion semble prometteuse. Elle consiste à décarboner les gaz produits par les réactions de réduction, et à les brûler dans la tuyère. Alors, le vent chaud n’est plus de l’air chaud, et l’oxy-combustion des gaz recyclés permet une capture du CO2 plus efficace. Dans le cadre du projet TGR-BF, ArcelorMittal souhaite étudier le comportement d’une tuyère d’injection fonctionnant en oxy-combustion grâce à la simulation numérique (Computational Fluid Dynamics – CFD) qui est aujourd’hui assez mature pour être intégrée aux processus industriels de conception, en complément de campagnes d’essais. Afin de simuler au mieux le fonctionnement d’une tuyère d’injection, la méthode aux grandes échelles a été utilisée et les différents processus physiques engagés dans la combustion du charbon ont été implémentés. Notamment, un nouveau modèle pour la dévolatilisation (pyrolyse) du charbon dans de conditions de hautes températures et pour des taux de chauffe élevés a été utilisé. Ce modèle, développé par T. Maffei, permet de capturer la bonne quantité et la bonne composition des matières volatiles éjectées de la particule de charbon pendant la pyrolyse. La combustion des espèces volatiles est traitée grâce à une méthode de chimie complexe avec l’utilisation d’un schéma réduit développé spécifiquement pour cette étude. L’effet de la turbulence sur la flamme est pris en compte grâce au modèle d’épaississement de flamme (TF-LES) dynamique. La validation du modèle de dévolatilisation a été faite en confrontant les données expérimentales trouvées dans la bibliographie tandis que la vérification du schéma cinétique réduit a été effectuée en le comparant au schéma détaillé GRI-3.0 sur des flammes 1D. Puis, l’ensemble des modèles est utilisé pour la simulation LES du brûleur swirlé de Cambridge. Enfin, la tuyère d’injection dans son fonctionnement en oxy-combustion est étudiée.Steel making is mostly based on coal combustion and is performed in blast furnaces. The principle is the following : a large amount of hot air (« the blast »,1200K) and pulverized coal particles are injected in the blast furnace through an injection tuyere. This results in the combustion of raw materials (pre-heated coal) and makes the iron ore melt in the tank of the blast furnace. The cast iron produced is retrieved at the bottom of the blast furnace and is thereafter transformed in steel. But, the reactions which occur during this process produce large amount of toxic gases (NOx, …) and greenhous gases such as CO2. In order to regulate and lower the production of such gases, the metal industry develops new technologies. Among them, the oxyfuel method for carbon capture seems to be promising. With such a method, the product gases are de-carbonated and re-used as a fuel. They are injected in the injection tuyeres and are burnt in oxy-combustion. Hence, the blast is not anymore hot air and the carbon is easily captured. In the context of reducing greenhouse gas emissions. ArcelorMittal wants to study, numerically, the behavior of an injection tuyere when it operates under oxy-combustion conditions. In order to simulate the behavior of such a tuyere, the large eddy simulation (LES) method is used. During coal combustion, several processes occur and need to be modeled. In particular, the pyrolysis of coal particles is performed using a new model developed by Maffei. This model is able to capture the right amount and the proper composition of the volatile gases released during the process, under specific conditions : the final temperature of the coal particles and the heating rates have to be high enough. The volatile combustion is performed with a complex chemistry approach, using a reduced scheme developed for the study. To take into account the effect of the turbulence on the flame, a dynamic thickened flame model (TF-LES) is used. The validation of the devolatilization model was made by comparing simulation results against experimental data found in the literature. On a 1D flame, the trajectories given by the reduced scheme were compared against the results obtained with the GRI-3.0, a detailed scheme, in order to verify the behavior of the reduced scheme. Then, the full coal combustion modeling was used on an experimental burner, studied at Cambridge university. Finally, the simulaion of the injection tuyere, under oxy-combustion operation, is performed, and its behavior is studied
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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