1,720,954 research outputs found
Fluid dynamic study of cyclonic separators inside oil wells through CFD techniques
Get PDFControlling of sand production in oil and gas wells has been a subject of great interest of the oil industry. This process has a direct implication in increasing the costs of production and has been widely described in the literature. Several authors have reported problems due to the sand production in wells that includes: premature waste of equipment, considerable increase in the number of workover operations and the availability of rigs to attend the demand of drilling operations. In this context, this paper focus on simulating efficient separation on 32 swirl tubes geometries as downhole desander device. Firstly, a desander with two vanes was simulated using CFD techniques and compared with experimental data existing in the technical literature. After that, different designs of swirl tubes with different parameters was performed by means of fractional factorial design with two levels in order to perform a sort of most relevant factors. However, the results of the validation test did not show satisfactory results for the particle injection parameters used. Therefore, the fluid dynamic analysis and the application of the method for tangential velocity and pressure drop were performed. According to the results, it was verified that for the five geometrical factors analyzed the external diameter, the number of vaynes and the vortex finder length are the most significant. The most impact on pressure drop are the external diameter, the flow rate and the number of vanes for the pressure drop. Finally, a linear model was proposed for the pressure drop as a function of the eight parameters analyzed and the main interactions between two factors. Among the results, a 110% increase in pressure drop was observed for an increase in the inlet flow from 60 m3 /day to 116 m3 /day.O controle da produção de areia em poços de petróleo e gás tem sido um assunto de grande interesse da indústria do petróleo. A produção de areia tem relação direta com o aumento dos custos de produção destacando-se problemas como o desgaste prematuro de equipamentos, aumento considerável no número de operações de intervenção e principalmente a falta de sondas para as operações de intervenção. Neste contexto, o presente trabalho buscou simular a eficiência de separação em 32 geometrias de separadores tubo-ciclônicos no processo de separação de areia produzida em poços de petróleo. Inicialmente, realizou-se a simulação para o separador tubo-ciclônico de duas hélices cujos dados experimentais estão disponíveis na literatura. Logo após, foram construídas diferentes geometrias deste tipo de separador variando os principais parâmetros geométricos por meio do planejamento fatorial fracionário de dois níveis com o intuito de realizar uma triagem dos fatores que mais relevantes. Contudo, os resultados dos testes de validação não mostram resultados satisfatórios para os parâmetros de injeção de partículas utilizados. Desta forma, foram conduzidas análises do escoamento do fluido para as diferentes geometrias de separadores e aplicação do método para a velocidade tangencial e queda de pressão. De acordo com os resultados, verificou-se que para os cinco fatores geométricos analisados o diâmetro do tubo externo do separador, o número de hélices e o comprimento do vortex finder são os mais significativos. Os fatores que mais influenciaram na queda de pressão foram o diâmetro externo, a vazão de entrada e o número de hélices, sendo mais pronunciada em escoamentos viscosos. Por fim, um modelo baseado no ajuste linear das simulações foi proposto para a queda de pressão em função dos oito parâmetros analisados e das principais interações entre dois fatores. Dentre os resultados, observou-se um aumento de 110% na queda de pressão para um aumento na vazão de entrada de 60 m3/dia para 116 m3/dia
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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