1,720,953 research outputs found
Estudio de películas antirreflectoras para comunicaciones ópticas
No full textAntireflective (AR) coatings have been widely studied due to their technological importance in numerous applications, including microelectronics, optical telecommunications, solar cells, etc. This work presents a complete study of AR coatings, including their theory, design, simulation, synthesis, and characterization. An essential subject in the operation of AR coatings is the contrast between the refractive indices of the materials used to make the layers of the coatings. Regarding synthesis, this contrast can be obtained either by evaporating different source materials or by manipulating the stoichiometry of the evaporated material. This thesis explores both fabrication approaches. For the former, a four-layer broadband AR design for the range from 1200 to 1600nm was fabricated at Corning Reynosa facilities using Nb2O5 and SiO2 as source materials by Ion Beam Assisted Deposition (IBAD) technique. On the other hand, at the ThinFilms laboratory at CICESE, the application of SiOx (1 < x < 2) thin-films on double- and triple-layer antireflective coatings designs for optical communications wavelength of 850nm was used for the very first time. Manipulation of the atmosphere, deposition rate, or the vacuum level in the chamber while evaporation of silicon monoxide by thermal evaporation technique can produce a range of refractive indices from 1.47 to 1.92. SiOx thin films have been widely studied but not used for antireflective purposes. After optical characterization of the samples by ellipsometry and spectrophotometry, was conclude that SiOx thin-films offer a good optical (reflectivity), but no mechanical (adhesion, packing density, etc.) AR performance, most probably due to the nature of the thermal evaporation technique. For this reason, energetic methods like IBAD are preferred to get high-quality antireflective coatings. IBAD offered rapid, repeatable, and low- substrate temperature deposition, which are some of the current requirements for the market of antireflective coatings for optical communications.Los recubrimientos antirreflectores (AR) llevan décadas siendo ampliamente estudiados debido a su importancia tecnológica en numerosas aplicaciones, incluyendo microelectrónica, comunicaciones, celdas solares, etc. Este trabajo presenta un estudio completo de los recubrimientos AR: desde su teoría, diseño, simulación, fabricación y su caracterización. Un concepto fundamental en el funcionamiento de los recubrimientos AR es el contraste entre los índices de refracción de los materiales que componen a éstos. Con respecto a la fabricación, este contraste se puede obtener evaporando diferentes materiales o manipulando la estequiometría del material evaporado. Esta tesis explora ambos. Para el primero, se fabricó en las instalaciones de Corning Reynosa un diseño antirreflector de banda ancha de cuatro capas para el rango de 1200 a 1600 nm, utilizando Nb2O5 y SiO2 como materiales fuente mediante la técnica de Depósito Asistido por Haz de Iones (IBAD, por sus siglas en inglés). Por otro lado, en el laboratorio de películas delgadas del CICESE, se utilizaron por primera vez películas delgadas de SiOx (1 < x < 2) en recubrimientos antirreflectores de doble y triple capa para la línea de comunicaciones ópticas de 850nm. Al modificar la atmósfera, la velocidad de deposición o el vacío en la cámara al evaporar el monóxido de silicio mediante la técnica de evaporación térmica, se obtiene un rango de índices de refracción desde 1.47 hasta 1.92. Las películas delgadas de SiOx se han estudiado ampliamente pero no se habían utilizado con fines antirreflectivos. Después de la caracterización óptica de las muestras mediante elipsometría y espectrofotometría, se concluyó que las películas delgadas de SiOx ofrecen un buen rendimiento óptico (reflectividad), mas no mecánico (adhesión, densidad de empaquetamiento, etc.), ocasionado muy probablemente por la naturaleza misma de la técnica de evaporación térmica. Por esta razón, se prefieren los métodos energéticos como IBAD para obtener recubrimientos antirreflectores de alta calidad. IBAD ofreció una deposición rápida, repetible y con una baja temperatura del sustrato, que son algunos de los requerimientos actuales para el mercado de recubrimientos antirreflectores para comunicaciones ópticas
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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