87,068 research outputs found
Nova família de conversores CC-CC PWM não isolados utilizando células de comutação de três estados
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Tecnológico. Programa de Pós-Graduação em Engenharia ElétricaEste trabalho apresenta uma nova família de conversores CC-CC PWM não isolados. Estes novos conversores são gerados utilizando a célula de comutação de três estados, que são compostas por dois interruptores controlados, dois diodos e dois indutores acoplados. As principais vantagens destes conversores, em comparação aos conversores clássicos, são: baixas perdas de condução; reduzida ondulação de corrente tanto na entrada como na saída; freqüência nos elementos reativos o dobro da freqüência de comutação de um interruptor e reduzidos peso e volume. Devido a estas características, a nova família de conversores torna-se de fundamental importância para aplicações em baixas tensões e elevadas correntes. Principalmente para potências acima de 1kW. Os conversores são analisados para dois modos de operação: o primeiro modo quando os interruptores trabalham em não-sobreposição (non-overlapping mode) (0<D<0,5) e o segundo modo quando os interruptores trabalham em sobreposição (overlapping mode) (0,5<D<1). Portanto, para conseguir estes modos de operação, os sinais de comando PWM dos interruptores estão defasados em 180o, sendo uma importante característica destes conversores. Neste trabalho, para validar o princípio de funcionamento dos novos conversores, são escolhidos entre todas as famílias geradas, os conversores boost CC-CC PWM não isolados gerados com a célula de comutação de três estados. Portanto, apresenta-se a análise teórica, a metodologia de projeto, o exemplo de projeto e os resultados experimentais. Como exemplo de aplicação, são apresentados a análise teórica, o projeto e os resultados experimentais de um protótipo, do conversor boost gerado a partir da célula B de comutação de três estados, operando como pré-regulador de tensão com elevado fator de potência e baixo valor da taxa de distorção harmônica da corrente da rede
Propuesta de mejora de los problemas evolutivos de Coordinación Motriz en 1º de la ESO a través de la asignatura de E F
No full textPiqueras Torrico, Alejandro; director de proyecto: Palacios Ferrer, José Luis2021-2022Máster Universitario en Profesorado de Educación Secundaria Obligatoria y Bachillerato, Formación Profesional y Enseñanza de IdiomasFacultad de Estudios Sociales y Lenguas Aplicada
Variations on the Author
No full text“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
Contribuições ao controle preditivo robusto de sistemas com atraso
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Este trabalho apresenta um estudo direcionado à análise e projeto de controladores preditivos baseados em modelo para sistemas lineares e não lineares com atraso, visando a melhoria da robustez e levando em conta aspectos práticos de aplicação. O estudo considera sistemas lineares estáveis, integradores, instáveis, não lineares e um estudo de caso na área da medicina. No primeiro caso, estudam-se as condições que deve satisfazer um sistema de controle preditivo linear para garantir a estabilidade robusta de malha fechada quando se controlam processos estáveis com incertezas no atraso. No segundo e terceiro apresenta-se o estudo do controle preditivo de sistemas lineares com dinâmica integradora ou instável e atraso e propõe-se um novo algoritmo que utiliza idéias de controladores de compensação de tempo morto robustos. No caso de sistemas não lineares propõe-se a extensão das propriedades de robustez de um algoritmo utilizado em sistemas de controle lineares com atraso para processos não lineares com atraso. Finalmente apresenta-se um estudo de caso aplicado à dosagem de anestesia a pacientes durante cirurgia, com garantia de estabilidade sob condições de operação. Resultados de simulação ou ensaios numa planta piloto são apresentados para cada tipo de controlador proposto, mostrando as vantagens dos métodos de ajuste, que principalmente estão orientados a melhorar a robustez e permitir a sua aplicação simples em processos industriais. This work presents the analysis and design of model-based predictive controllers MPC for linear and nonlinear dead-time systems. The proposed control strategies take into account both practical aspects and robustness specifications. The study considers: (i) stable, integrative and unstable linear systems, (ii) nonlinear systems and (iii) a medicine area case study. In the first case, the necessary conditions to guarantee the robust stability when MPC are applied to stable processes with dead time are studied. In addition, it is proposed a robust predictive controller for integrative or unstable linear processes with dead time. This controller uses some of the robustness ideas of dead-time compensators. In the second case, the robustness properties of linear predictive controllers are extended for stable nonlinear processes with dead time. Finally, it is presented a case study where the robust MPC is applied to drug dosing during anesthesia in patients undergoing surgery. Also, a tuning rule is obtained to guarantee the stability of the system under operation conditions. Experimental or simulation results are presented for each proposed controller, to illustrate the advantages of the tuning methods
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Maine author Franklin F. Gould recalls his first glimpse of the outside world
No full textMaine author Franklin F. Gould recalls his first glimpse of the outside world as he relates how, as a young farm boy in the late 1800\u27s, he drove his father\u27s horses on an errand to an icebound river
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
No full textThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
- …
