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Estudo da influência de diferentes granulometrias na densificação de compósitos de aço duplex uns s31803 produzido por metalurgia do pó
Get PDFDuplex stainless steels (DSS) are so named because they exhibit a biphasic microstructure, with roughly equal volumetric proportions of ferrite and austenite. They find extensive use in industries such as oil, pulp and paper, chemical, nuclear, and others, typically when a material with high mechanical strength and corrosion resistance is required. Powder metallurgy can provide a means of recycling scraps and leftovers from production processes like machining. This study focused on investigating the influence of different particle sizes and pressing methods (uniaxial and isostatic) on the densification of a DSS composite, specifically the UNS S31803 grade, produced through powder metallurgy. The powders were subjected to milling for 20, 40, and 80 hours, with the addition of 3% vanadium carbide and 1% methanol as a process control agent. Heat treatment at 1050 ºC for 30 minutes was applied to relieve the stresses resulting from the milling process. The powders obtained at different milling times were classified and characterized in terms of morphology and particle size distribution using scanning electron microscopy and laser granulometry techniques. Subsequently, the powders with different particle sizes were pressed using uniaxial and isostatic pressing methods. Pellets were produced using powders milled for 20, 40, and 80 hours, as well as mixtures of equal weight fractions of powders milled for 20 and 40 hours, 40 and 80 hours, and 20, 40, and 80 hours. Green density measurements were conducted on the obtained pellets, which were then sintered at 1250 ºC for 1 hour. The sintered pellets were characterized in terms of porosity, pore size, and densification using optical microscopy, X-ray diffraction, and density measurements using the Archimedes method. The results showed that particle dimensions decreased with longer milling times. The average particle size decreased from 60.57 μm at 20 hours of milling to 52.35 μm at 40 hours and 39.02 μm at 80 hours. The porosity values were similar for uniaxial and isostatic pressing. The highest densification value (determined using the Archimedes method) was achieved with the mixture of powders milled for 20, 40, and 80 hours using isostatic pressing, resulting in a density of 6.9528 g/cm³. The density value for UNS S31803 DSS produced via casting is 7.80 g/cm³.Os aços inoxidáveis duplex (AID) são assim denominados por apresentar uma microestrutura bifásica, com a proporção volumétrica aproximadamente iguais de ferrita e austenita, sendo muito empregado na indústria de petróleo, papel celulose, química, nuclear entre outras. De modo geral são empregados quando existe a necessidade de um material com alta resistência mecânica aliada a alta resistência a corrosão. A metalurgia do pó pode ser uma forma de reaproveitamento para sucatas e sobras de componentes produzidos a partir de processos de produção, como usinagem. Neste trabalho foi realizado um estudo sobre a influência de diferentes granulometrias e de diferentes formas de prensagem (uniaxial e isostática) na densificação de um compósito de AID UNS S31803 produzido por metalurgia do pó. As moagens foram realizadas, por 20, 40 e 80 horas, com adição de 3% de carbeto de vanádio e de 1% de metanol como agente controlador do processo. Os pós foram tratados termicamente a 1050 ºC por 30 minutos, para alívio das tensões oriundas do processo de moagem. Os pós obtidos nos diferentes tempos de moagem foram classificados e caracterizados quanto à sua morfologia e distribuição granulométrica, utilizando as técnicas de microscopia eletrônica de varredura e granulometria a laser. Após a caracterização os pós, com diferentes granulometrias, foram prensados utilizando prensagens uniaxial e isostática. Foram produzidas pastilhas utilizando os pós moídos por 20, 40 e 80 horas, também foram produzidas pastilhas utilizando a mistura em frações iguais de peso dos pós 20 e 40 horas, 40 e 80 horas e 20, 40 e 80 horas. Após a obtenção das pastilhas, foi realizado a medida da densidade a verde e posteriormente as pastilhas foram sinterizadas na temperatura 1250 ºC por 1 h. As pastilhas sinterizadas foram caracterizadas segundo à porosidade, dimensão dos poros e densificação utilizando as técnicas de microscopia óptica, difração de raios x e medidas de densidade pelo método de Arquimedes. Os resultados mostraram que as dimensões dos particulados reduzem com o aumento do tempo de moagem. No tempo de 20 horas a dimensão média das partículas ficaram em 60,57 μm, no tempo de 40 horas a dimensão média reduziu para 52,35 μm e no tempo de 80 horas a dimensão ficou em 39,02μm. Com os resultados da porosidade foi possível verificar que os valores ficaram próximos para a compactação uniaxial e isostática. O maior valor de densificação (utilizando a técnica de Arquimedes) foi obtido com a mistura na fração igual dos pós de 20, 40 e 80 horas utilizando a prensagem isostática e o valor alcançado foi de 6,9528 g/cm3. O valor da densificação do AID UNS S31803 produzido via fundição é de 7,80 g/cm³
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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