1,721,015 research outputs found
Implementación computacional de la interacción sólido-fluido para el modelo CAFFA3D.MBRI
Get PDFEl modelo numérico CAFFA3D.MBRI se enmarca en el área de mecánica de los fluidos computacional y su aplicabilidad abarca el estudio de flujos tridimensionales viscosos, turbulentos, incompresibles, con transporte de escalares o con superficie libre, entre muchos otros. Es una implementación del Método de Volúmenes Finitos que utiliza mallas curvilíneas y estructuradas por bloques, que permite dividir la tarea realizando el cálculo en paralelo bajo el estándar MPI. En el presente trabajo se desarrollan nuevas extensiones del código, que permiten su aplicación a situaciones que involucren la interacción entre un cuerpo rígido, de forma arbitraria, y un flujo en el que se encuentra inmerso. La presencia del cuerpo se realiza adaptando implementaciones del Método de Condiciones de Borde Inmersas (IBM) y su movimiento de traslación y rotación se calcula con las ecuaciones de la mecánica clásica, discretizadas bajo un esquema leapfrog con sobre-relajación. El cálculo preciso de la fuerza y momento de fuerza de interacción sólido-fluido requiere la utilización de mallas muy finas, que conlleva un elevado costo computacional. Para obtener un cálculo preciso y con un costo computacional moderado, en este trabajo se adapta una implementación previa de la técnica de mallas anidadas para que se muevan de manera solidaria al cuerpo. Esto permite tener en todo momento un refinamiento local de malla en la cercanía del rígido. Además, la técnica completa se implementó para el caso en que intervienen varios rígidos de forma arbitraria. Se aplicó el código generado a diferentes problemas físicos para su validación y para el análisis de su capacidad. Los resultados para el análisis en dos (tres) dimensiones de la caída, bajo la acción de la gravedad, de un círculo (esfera) inmerso en un fluido newtoniano confinado en un recipiente están en excelente concordancia con referencias previas. Además, se modeló la fuerza de choque entre dos cuerpos para analizar el caso de la caída en dos (tres) dimensiones de dos círculos (esferas). Se obtuvieron excelentes resultados y se logró reproducir el fenómeno de drafting, kissing and tumbling (DKT). Para mostrar la capacidad del código frente a problemas de interés tecnológico, se aplicó el modelo al problema de resuspensión de sedimentos para el caso en dos dimensiones de un sedimento circular que es removido de la pared inferior del dominio por un flujo de Poiseuille entre dos paredes horizontales paralelas. El método desarrollado permitirá estudiar situaciones en un amplio rango de escalas. Desde escalas biológicas, como la propagación de glóbulos rojos en el torrente sanguíneo, hasta grandes escalas, por ejemplo en la resuspensión de sedimentos en el fondo de un río o el movimiento de un aerogenerador cuando interactúa con un viento durante la generación de energía eólica.The so called caffa3d.mbri is a flow solver which scope includes the study of viscous, turbulent, incompressible, or transporting a contamin ant flows, to mention some. It is an implementation of the finite volume method and uses curvilinear, block-structured grids, allowing the code parallelization using the MPI library. In this work we continue with the development of the code, in order to expand its applicability to cases involving the interaction between a rigid body of given shape and the flow in which it is immersed. The body is represented by means of the immersed boundary method and its motion and rotation are obtained by solving the equations from classical mechanics, using an over-relaxed leapfrog time scheme. A very accurate force and moment calculation, as a result of rigid-flow interaction, resulting from the body-flow interaction,
requires the use of fine meshes, leading to a great numerical effort. In order to obtain an accurate solution and save numerical effort, in this work we adapted a previous implementation of the nesting technique, which gives the solver the capability of overlapping fine meshes on the volume occupied by the rigid, at every time step of the simulation. These meshes can also move and rotate following the body state, so that we get mesh refinement only in its vicinity, that is, where it is needed. Moreover, the described technique is also extended for cases involving many bodies. The solver is applied to different physical problems for its validation and to test its real capabilities. Among them, we studied the falling, due to the gravity, of a circle (sphere) immersed in a newtonian fluid in a container, in two (three) dimensions, obtaing results which are excellent agreement with previous works. In the second study, we considered the two (three) dimensional problem concerning two circles (spheres) falling immersed in a newtonian fluid contained in a closed container. For that purpose, we added the calculation for the collision force between the bodies. The problem was solved properly and the typical drafting, kissing and tumbling phenomenon (DKT) was observed.
Finally, we apply the solver for simulating a problem concerning the resuspension of sediments, which has great technological interest. It consists on a two dimensional Poiseuille flow between two horizontal walls, that causes the remotion of a circular body initially at rest over the bottom wall and then advected by the flow. The new features incorporated to the code made it capable of studying real world applications where the interaction between fluid an rigid bodies is present, in a wide range of scales. From the transport of red blood cells by the bloodstream, or the resuspension of sediments at the bottom of the riverflow, to the motion of wind turbines during the generation of wind power
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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