1,720,953 research outputs found
Estudio de factibilidad de la instalación de una planta de acetaldehído a partir de bioetanol
No full textLa descarbonización de la industria, y en particular de la industria química, es una idea que ha ganado notable popularidad y fuerza en las últimas décadas. La búsqueda de formas de reemplazar las tradicionales vías de producción de energía, combustibles y productos químicos basadas en hidrocarburos y derivados del petróleo ha dado lugar a la aparición de alternativas más ambientalmente sustentables.
En Argentina, en un intento de lograr una matriz de combustible de mayor sostenibilidad, la legislación nacional ha impuesto desde 2010 un corte obligatorio con bioetanol a las naftas empleadas para transporte vehicular. Esta medida fomentó la instalación de plantas productoras de bioetanol, producido principalmente a partir de maíz y caña de azúcar. Sin embargo, el estancamiento del porcentaje de corte en un valor del 12%, sumado a la regulación estatal ejercida sobre el precio de venta del bioetanol, ha provocado una merma en la producción y un menor incentivo en apostar al crecimiento del mercado de este biocombustible.
A partir del proyecto de diseño de una planta de bioetanol a partir de remolacha, efectuado en el marco del Trabajo Final de Ingeniería Química en el año 2018, se propone en este proyecto la concepción de una nueva planta para la síntesis de acetaldehído, empleando ese mismo bioetanol como materia prima. De esta forma, se busca orientar recursos hacia la diversificación de la matriz productiva, valiéndose de materia prima disponible a partir de la cual es posible continuar con la cadena de agregado de valor.
El acetaldehído es un compuesto de gran interés en la industria química y sus ramificaciones (farmacéutica, alimenticia, de pinturas, entre otras). Se concibe entonces la posibilidad de instalar una planta con una capacidad de 20.000 toneladas anuales de acetaldehído de alta pureza.
El presente proyecto representa un diseño preliminar de las instalaciones y los principales equipos necesarios para su funcionamiento. Se alcanza una profundidad de ingeniería básica, sin adentrarse en las especificaciones propias de una etapa de ingeniería de detalle, previstas para una instancia más avanzada de un proyecto.
Se decide sintetizar el acetaldehído mediante la ruta de deshidrogenación catalítica del etanol. Se obtiene de la misma reacción hidrógeno como subproducto, y como resultado de una reacción secundaria, acetato de etilo. Ambos compuestos cuentan con valor comercial, por lo que es de interés separarlos en especificación para su posterior comercialización.
Se diseña un sistema de reactores que consta de dos lechos fijos rellenos de catalizador de cromita de cobre, y se seleccionan las condiciones operativas que resultan favorables para maximizar la selectividad hacia la formación de acetaldehído.
Posteriormente, se profundiza en el esquema de separación y purificación. Se proyecta la instalación de una subplanta de separación de hidrógeno que incluye un separador flash, un compresor y un absorbedor, junto a los compresores específicos para su almacenamiento como gas comprimido. Luego, en un tren de cinco destiladores se separa tanto el acetaldehído y el acetato en especificación, como el etanol no convertido para su recirculación al sistema de reactores.
Se implementa el método Pinch para integrar energéticamente las corrientes de proceso que requieren intercambio de calor. De esta forma, se aprovecha la carga térmica de corrientes que deben enfriarse para calefaccionar corrientes ávidas de calefaccionarse. Para aquellas corrientes que no puedan integrarse energéticamente, se suministra o extrae energía empleando fluidos auxiliares: agua de enfriamiento, agua helada, refrigerante, vapor de agua y fluido calefactor. Se definen los intercambiadores de calor necesarios, así como los demás equipos auxiliares de la planta (bombas, compresores, eyectores).
En función del diseño completo de la planta, se estima la inversión requerida para su puesta en funcionamiento, los costos operativos y los potenciales ingresos por venta. A partir de estos resultados, se calculan los flujos de caja anuales y se estima la rentabilidad del proyecto. Se realiza un análisis comparativo entre los resultados económicos de la planta original de bioetanol con y sin el agregado de las nuevas instalaciones de acetaldehído. Por otro lado, se efectúa un estudio de sensibilidad frente a cambios en la capacidad de la planta, el costo de la materia prima y el precio de venta del acetaldehído.
Por último, se lleva a cabo un estudio de impacto ambiental de la planta. Se identifican las fuentes de impacto presentes, y se proponen diversas medidas preventivas y correctivas en función de la clasificación del riesgo asociado a cada fuente.
Mail de los autores Agustín Pomponio ; Matias Sharif Jozami ; Lucila Malarczuk ; Carmen Novoa Fil: Jozami, Matías Sharif. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Malarczuk, Lucila. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Novoa, Carmen. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Pomponio, Agustín. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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