1,720,953 research outputs found
Efecto de las propiedades de materiales y parámetros de diseño de los electrodos de baterías de ion litio de alta densidad de energía
Get PDFLas Baterías de Ion Litio (BIL’s) son sistemas de almacenamiento de energía, que convierten la energía química en energía eléctrica por medio de reacciones electroquímicas. Las BIL’s han sido utilizadas para dispositivos electrónicos, vehículos eléctricos, solución de almacenamiento de energía para energías renovables, etc. A pesar de que las BIL’s tienen propiedades que sobresalen de otro tipo de baterías como las de plomo ácido, sus propiedades no son adecuadas para otras aplicaciones, como los dispositivos miniaturizados, particularmente los Vehículos Aéreos No Tripulados (VANT’s). Las BIL’s de VANT’s se ven limitadas por su densidad de energía (densidadΓ =196 Wh/kg ) y densidad de potencia (densidadP =429 W/kg ). Para mejorar su diseño no existe una metodología que considere un efecto en conjunto de la evaluación de materiales, propiedades físicas de los electrodos, y su relación con los fenómenos de transporte. Considerando que una BIL exhibe propiedades en múltiples escalas de longitud, en el presente proyecto se propuso una evaluación integral de las propiedades de los materiales desde el nivel de escala de celda (10-4 m) hasta el nivel de la BIL (10-2 m). La evaluación integral consiste en dos etapas teóricas y una etapa experimental. En la primera etapa teórica se seleccionaron los materiales de la BIL mediante una ponderación cualitativa de las características intrínsecas de todos los componentes. La BIL con configuración C6/1 M LiPF6 en EC: DMC (1:1) / LiNiMnCoO2: PVDF-CSP, fue la que presentó mejores características en términos de densidad de energía y densidad de potencia a altas (5C) y bajas velocidades (C/10). Dentro de esta etapa se realizó una ponderación cuantitativa, donde fue posible identificar los parámetros de impacto en las salidas de densidad de potencia y densidad de energía de la BIL. Un aumento de la carga de Material Activo (MA) de 5 a 15 mgMA/cm2 impactó de manera positiva en un 31%; por el contrario, un aumento en los espesores de los colectores de corriente, para el cobre de 9 a 45μm y para el aluminio de 15 a 28μm , impactó de manera negativa hasta un 36%. Tomando en cuenta los factores de impacto antes mencionados, se especificaron las propiedades de la BIL para alcanzar los requerimientos energéticos del VANT comercial, como fue el caso de la carga de material activo (30MA 2cm mg ). Los espesores de los colectores de corriente que permitieron alcanzar estos requerimientos fueron: para el ánodo, cobre 6 de μm y para el cátodo aluminio de 13 μm. El separador por otra parte fue el Celgard 2500 de 20 μm de espesor. En la segunda etapa (experimental) se identificaron los límites de fabricación y operación al nivel del electrodo (10-8-10-6 m). El proceso de calandrado ayudó a tener un control del espesor y la porosidad, así como una mejora en la distribución de las partículas en el electrodo. Por medio de la caracterización electroquímica de electrodos de bajo (100 μm) y alto espesor (200 y 300 μm) se obtuvieron las salidas de densidad de energía y densidad de potencia a velocidades de descarga de C/10, C/5, 1C y 2C donde el electrodo de 200 μm presentó mejor desempeño en términos energéticos a altas velocidades. La tercera etapa teórica fue una herramienta para la interpretación de resultados experimentales; mediante simulaciones se determinó que para el electrodo de 100 μm las pérdidas de capacidad se deben sólo a limitaciones de difusión en la fase sólida. Para los electrodos de 200 y 300 μm las pérdidas de capacidad son influenciadas por caída óhmica en la solución y de transporte de masa en la fase sólida. Este trabajo es el primero en considerar un efecto en conjunto de las propiedades de una BIL en sus múltiples escalas de manera teórica como experimental, además sienta las bases para posteriores diseños de BIL’s para cualquier otra aplicación
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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