1,720,953 research outputs found
Development of a star recognition algorithm in astronomical images
No full textUno de los subsistemas más importantes en un satélite es el sistema de control de actitud. Este módulo se encarga de determinar y corregir la ubicación y posición delsatélite o cualquier objeto que se encuentre en el espacio. En este trabajo la importancia radica en la verificación experimental de uno de los sensores más importantes que realizan el control de actitud, el sensor de estrellas. El algoritmo de identificación de estrellas que se trabaja utiliza técnicas invariantes a la semejanza con polígonos de estrellas, mediante las cuales se pueden procesar imágenes de estrellas rotadas, escaladas y desplazadas sin que se afecte la información que guarda cada conjunto de estrellas. Se han adquirido y procesado fotografías de telescopios del Observatorio Astronómico Nacional de San Pedro Mártir con el objetivo de obtener imágenes lo más cercano posible a las que se encontrarían en un satélite de órbita baja. A estas, se les han aplicado algoritmos de eliminación de ruido, identificación de regiones de interés, cálculo de centroides, rotación de coordenadas mediante ángulos de Euler y cambios de época a coordenadas de estrellas con el fin de adaptar los datos para el correcto funcionamiento del algoritmo de la invariante. Además, para poder empatar los datos de los sensores de imagen de los telescopios ha sido necesario filtrar información de las coordenadas, velocidades propias y radiales y paralaje de estrellas descargadas de la base de datos de la misión espacial Gaia. Como resultado, para el presente caso de estudio se han obtenido los valores de la invariante a la semejanza con una precisión del 99.678121 %, mostrando así la viabilidad en la implementación real del algoritmo de identificación de estrellas. Además, se muestra un segundo caso de estudio utilizando imágenes de la colaboración de NovaAstrometry, en donde se obtiene un resultado de 99.482754 % de precisión. Por lo cual, se abre un nuevo panorama en donde se pueda implementar este algoritmo en un sistema embebido y con la adquisición de imágenes utilizando telescopios comerciales.One of the essential subsystems in a satellite is the attitude control system. This module is responsible for sensing and correcting the location and position of the satellite or any object in space. In this work, the importance lies in the experimental verification of one of the sensors that performs the attitude control, the star sensor. The star identification algorithm that is proposed uses similarity transformation invariant techniques to identify polygons formed by stars. The proposed algorithm can process star images that have been be rotated, scaled, and translated without affecting the information contained in each set of stars. The images used in this work were obtained using the telescopes of the Mexican National Astronomical Observatory of San Pedro Mártir in Baja California. We consider that these images are the closest that we can get to the type of images acquired by low Earth orbit satellites. Algorithms for noise elimination, identification of regions of interest, calculation of centroids, rotation of coordinates by Euler angles, and changes of time to star coordinates have been applied to adapt the data for the correct operation of the invariant algorithm. Besides, to be able to match the data of the image sensors of the telescopes, it has been necessary to filter information of the coordinates, proper motion, radial velocity and parallax of stars downloaded from the database of the Gaia space mission. As a result, for the present case study the values of the similarity invariant have been obtained with an accuracy of 99.678121 %, consequently showing the viability in the current implementation of the star identification algorithm. Also, a second case study is shown using images from the NovaAstrometry collaboration, where a 99.482754 % accuracy result is obtained. Therefore, a new panorama is opened where this algorithm can be implemented in an embedded system and using images obtained with commercial off-the-shelf telescopes
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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