1,720,965 research outputs found
Desenvolvimento do planejador de trajetória e do sistema de controle em malha aberta de um manipulador robótico de geometria esférica, embarcados em uma plataforma FPGA
Full text linkDissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia,
Departamento de Engenharia mecânica, 2012.Esse trabalho descreve o desenvolvimento e a implementação de um controlador de trajetória retilínea em um robô esférico de 5 graus de liberdade. Para tanto, foi desenvolvida uma arquitetura de controle em malha aberta embarcada em uma FPGA para os três primeiros graus de liberdade do manipulador. Nesse intuito, apresenta-se, nesse trabalho, a modelagem cinemática direta e inversa do manipulador, bem como seu Jacobiano. Essa modelagem permite o controle da trajetória do robô em um caminho retilíneo descrito em coordenadas cartesianas. Na implementação do controle embarcado na FPGA, foi utilizado o microprocessador NIOS II, da Altera. Esse é o responsável pelos cálculos de posicionamento e velocidade do manipulador durante sua movimentação. Também são explicitadas as interfaces de acionamento e controle de cada um dos eixos do manipulador e seus respectivos motores. São ainda apresentadas as experiências de validação dos algoritmos implementados, através de simulações computacionais, bem como a validação das equações utilizadas. Além disso, são apresentados os resultados de movimentação do manipulador, seguindo uma trajetória pré-estabelecida, buscando validar na prática o controle implementado. _______________________________________________________________________________________ ABSTRACTThis paper describes the development and implementation of a controller for straight path trajectory in a spherical robot of five degrees of freedom. To do that, an open loop control architecture (embedded in an FPGA) was developed, for the first three degrees of freedom of the manipulator. Therefore, the direct and inverse kinematic models of the manipulator as well as its Jacobian are presented in this work. This modeling allows us to control the trajectory of the robot in a straight path described in Cartesian coordinates. In the implementation of the embedded controller in the FPGA, we have used the NIOS II microprocessor, from Altera. This is responsible for calculating the position and speed of the manipulator during its motion. Also the interfaces with the controllers of each axis of the handler and their respective engines are specified. We also present experiments to validate the implemented algorithms through computer simulations, as well as the validation of the equations used. Finally, the results are presented of the manipulator motion, following a predetermined path, in order to validate the control implemented in practice
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
A Dynamic Mode Decomposition approach with Hankel blocks to forecast multi-channel temporal series
No full textForecasting is a task with many concerns, such as the size, quality, and behavior of the data, the computing power to do it, etc. This letter proposes the dynamic mode decomposition (DMD) as a tool to predict the annual air temperature and the sales of a stores’ chain. The DMD decomposes the data into its principal modes, which are estimated from a training data set. It is assumed that the data is generated by a linear time-invariant high order autonomous system. These modes are useful to find the way the system behaves and to predict its future states, without using all the available data, even in a noisy environment. The Hankel block allows the estimation of hidden oscillatory modes, by increasing the order of the underlying dynamical system. The proposed method was tested in a case study consisting of the long term prediction of the weekly sales of a chain of stores. The performance assessment was based on the best fit percentage index. The proposed method is compared with three neural network-based predictors.info:eu-repo/semantics/publishedVersio
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
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