40,776 research outputs found
Retificador trifásico buck-boost de estágio único
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Este trabalho apresenta uma nova topologia de retificador trifásico de estágio único com característica Buck-Boost. Inicialmente é apresentada uma revisão bibliográfica envolvendo as publicações mais relevantes na área de estudo. Na sequencia são apresentadas a motivação para o trabalho e as contribuições da Tese. A topologia proposta é apresentada sendo descritas a sua origem e seus modos de operação de interesse. São analisados então os modos de condução descontínua (MCD) e contínua (MCC). No MCC são analisados os modos de operação Buck, Buck+Boost e Boost. As etapas do estudo de cada modo de operação compreendem a descrição das etapas de operação, análise teórica estudos por simulação numérica, definição das equações de projeto e resultados experimentais.This work presents a new topology of three-phase rectifier with singlestage and Buck-Boost characteristic. Initially a literature review is presented which brings the most important publications in the study area. Following it is presented the motivation for the work and the contributions of this thesis. The proposed topology is then presented, with descriptions of their origin and their operation modes of interest. Are then analyzed the discontinuous (DCM) and continuous (CCM) conduction modes. At MCC, we analyze the operation modes Buck, Boost and Buck + Boost. The study stages of each mode of operation include the description of the operation stages, theoretical analysis, numerical simulation studies, definition of design equations and experimental results
Passing the buck
No full textShifting the responsibility for a necessary but costly action to someone else is often called Passing the Buck. Examples of such behavior in politics are environmental and budget problems which are left to future generations. Small group examples are (not) washing the dishes or (not) dealing with a difficult customer. Under the assumption of altruistic preferences, rational behavior in this game is derived and confronted with experimental data. By comparison, the sequence of possible decision makers in the normal Passing the Buck game is substituted with an expert who alone is competent to fix the problem. It turned out that the marginal probabilities of shifting the responsibility are in good accordance with the theoretical model, although with completely different parameter distributions for experts and non-experts. The structure of the individual decisions, however, is best described by a random parameter model (Cox et al., 2007). --public goods,volunteer's dilemma,responsibility
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[News Clip: Pearl Buck]
No full textVideo footage from the WBAP-TV station in Fort Worth, Texas to accompany a news story about an author, who came to Dallas to claim her prizes. Novelist Pearl Buck arrived for the 6th annual Club Woman's Forum
Oral History Interview with Buck Gibson, October 19, 2002
No full textInterview with Buck Gibson of Waco, Texas, a veteran from the United States Navy during World War Two. The interview includes some of Strauss' background before and after the war as well as his personal experiences while in the Navy, including memories of his training, life in the Navy, the sinking of the USS Indianapolis, and what happened after he was rescued
Retificador buck trifásico unidirecional PWM isolado em alta-frequência por único estágio
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2009Descreve-se uma nova topologia de conversor CA-CC trifásico isolado em alta-frequência por único estágio de potência. O novo conversor é constituído de um retificador Buck unidirecional trifásico associado a um transformador forward/flyback com desmagnetização na carga. Para a exploração da nova topologia foram realizados estudos sobre retificadores Buck, algumas técnicas populares de modulação SPWM escalar, uma técnica clássica de filtragem das harmônicas das correntes de entrada e uma técnica de modelagem por espaço-de-estados e controle contínuo do retificador Buck em sistema de coordenadas dq obtidas por transformação de Clarke/Park. Para a obtenção da isolação em alta-frequência sem conversores adicionais foram estudados os princípios de operação do conversor forward/flyback em modo de condução descontínuo para posterior integração do transformador ao retificador trifásico. Os conhecimentos obtidos foram concentrados no retificador Buck trifásico isolado em altafrequência onde foram exploradas a modulação da ponte retificadora, os estados de operação associados ao transformador e a desmagnetização na carga. Ainda, foram obtidos os modelos em espaço-de-estados em coordenadas dq para o retificador Buck com transformador e projetados compensadores PI contínuos para o controle pela tensão na carga. Para a comprovação do conceito da topologia proposta foi projetado e implementado um protótipo de 2;5 kW para conexão em rede trifásica sem neutro de 220 V e tensão de 48 V para a carga regulada por circuito controlador digital baseado na arquitetura de baixo custo dsPIC.This work presents a new topology for an AC-DC three-phase converter with single-stage high-frequency isolation. The new converter is composed of an unidirectional three-phase Buck rectifier and a forward/flyback transformer with demagnetization through the load. The study of Buck rectifiers principles has been performed as a basis to develop the new topology. The scalar SPWM modulation techniques, the classic design of filters to input currents and a state-space modeling technique at dq components to design the feedback control for a Buck rectifier have been studied. The forward/flyback converter operating at discontinuous conduction mode has been studied to allow a high-frequency isolation to the Buck rectifier without the cascade of extra switched converters. The three-phase Buck rectifier with high-frequency isolation has been analyzed regarding pulse width modulation, operational states and requirements for demagnetization through the load. Moreover, the state-space models at dq components have been derived and standard PI regulators have been designed to control the proposed rectifier. The validation of the proposed topology has been performed on an experimental prototype with the following specification 220 V three-wires mains source and 2:5 kW at 48 V output regulated by a digital control based on dsPIC low cost architecture
Oral History Interview with Homer Buck & Dub Ramsel, June 21, 2003
No full textThe National Museum of the Pacific War presents an interview with Homer Buck and Dub Ramsel. Buck joined the Marine Corps in October of 1942, and served as a B-25 pilot. He was assigned as a replacement on Mindanao, Philippines. He completed patrol missions, searching for Japanese PT boats. Buck was discharged in early 1946. Ramsel was called to active duty in September of 1942. He received his wings and commission in August of 1943, and served as a Corsair pilot. In early 1944, Ramsel served with Marine Fighting Squadron 215 (VMF-215). He deployed to Hawaii as a replacement, completed around 900 hours of flight time, though never participated in any war campaigns. Ramsel was discharged in October of 1945
Brennan Buck
No full textArchitecture Spring 2014 Lecture - February 28, 2014 at Slocum Hall. Brennan Buck is a principal at Freeland Buck in NYC and a Critic at the Yale School of Architecture. His writing and editing focuses on technology within the discipline an its associated aesthetic culture. He has practiced architecture and landscape architecture at offices including New M. Denari Architects and Johnston Marklee & Associates in Lose Angeles. Freeland Buck is affiliated with Yale University and SCI-ARC. The office focuses on the spatial, atmospheric and structural potential of computational pattern
Cherie Buck-Hutchison
No full textBirth Story
Creative Push is a multimedia visual art and oral history project that focuses on the most formative of human experiences: birth. Creative Push is a means to collect, transform, display, and circulate birth stories and artworks.Storyteller: Cherie Buck-Hutchison
Age: 59, Delivery Date: 10/24/1976
Race: CaucasianArtist: Cherie Buck-Hutchison, Title: Musings on an Attempt at Natural Childbirth in an Artificial State of Affairs (Installation of Adit's Ode: A Modest Revolt), Medium: Video performance Dimensions: Duration 11:3
Dynamic characterisation of a linearised transfer function of non-ideal buck converters
No full textThe inherent nonlinear behaviour of DC-DC power supplies complicates the task of working out their linear models, which are essential for a model-oriented control. In a model-oriented control design approach, the accuracy of the plant model directly influences the performance of the control system as the plant parameters tend to be linked to the gains of the controllers. This paper presents a dynamic analytical model of a DC-DC buck converter based on small signal analysis with a closed loop control. The small signal model is used to analyse the small deviations around the steady-state operating point of a buck converter leading to an accurate modelling of the closed loop converter parameters. A complete state-space analysis is undertaken where the output voltage to duty ratio transfer function for a non-ideal buck converter including the parasitic elements is developed
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