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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Solutions of the toroidal wave equation and their applications

Weston, Vaughan H., January 1900 (has links)
Thesis--University of Toronto, 1956. / Photocopy (positive) of microfilm from University of Toronto Library. Microfilm made by Standard Microfilming Co., Toronto. Vita. Bibliography: leaf 88.
2

Solutions of the toroidal wave equation and their applications

Weston, Vaughan H., January 1900 (has links)
Thesis--University of Toronto, 1956. / Photocopy (positive) of microfilm from University of Toronto Library. Microfilm made by Standard Microfilming Co., Toronto. Vita. Bibliography: leaf 88.
3

Onderzoekingen omtrent drijvende homogene parallelopipeda ...

Brandsen, Petrus. January 1900 (has links)
Proefschrift-Amsterdam. / "Literatuur": p. [13]-14.
4

De seriebus secundum functiones, quae vocantur sphaericae, progredientibus

Thomé, Ludwig Wilhelm, January 1900 (has links)
Thesis--Friedrich-Wilhelms-Universität Berlin, 1865. / Vita.
5

Analytiske studier over harmoniske funktioner med tre variable,

Schou, Erik, January 1912 (has links)
Thesis--Copenhagen.
6

Sistemas híbridos para mitigação de harmônicos : modelagem e estudos experimentais /

Ravagnani, Lídia Luciana. January 2008 (has links)
Orientador: Luis Carlos Origa de Oliveira / Banca: Dalgerti Lelis Milanese / Banca: Júlio Borges de Souza / Banca: Antônio Carlos Delaiba / Banca: Kleiber David Rodrigues / Resumo: Diante do aumento expressivo de cargas não-lineares nos sistemas de energia elétrica cresce também, em proporções alarmantes, os problemas relacionados com as distorções harmônicas nas tensões e correntes. Com vistas à mitigação das distorções harmônicas, o uso de filtros e dispositivos de compensação harmônica são as técnicas comumente utilizadas para atenuar o fluxo das principais componentes harmônicas que compõem a citada distorção. Este trabalho está particularmente direcionado para investigações relacionadas ao uso de dispositivos de filtragem de natureza passiva, compreendendo arranjos híbridos, compostos por filtros ressonantes e filtros eletromagnéticos. Neste contexto, esta tese apresenta contribuições inéditas relacionadas com o desenvolvimento de modelos matemáticos no domínio da freqüência para filtros eletromagnéticos e a generalização de metodologias para análise de desempenho baseado no comportamento das componentes harmônicas seqüenciais. O desempenho e a aderência dos modelos propostos são avaliados numa base comparativa de natureza experimental, utilizando-se um protótipo de um filtro eletromagnético de potência reduzida, construído a partir das diretrizes metodológicas oriundas das análises teóricas. Os modelos desenvolvidos são utilizados na composição de um aplicativo computacional para análise de desempenho e otimização de projetos de sistemas de filtragem harmônica. A descrição analítica proporcionada por esta ferramenta de cálculo possibilita a investigação individualizada e sistemática do comportamento do sistema elétrico para as diferentes componentes harmônicas seqüenciais. Pela investigação detalhada das contribuições individuais de cada fonte harmônica, é possível identificar ações para a escolha adequada das topologias e de outros ajustes, visando à maximização do desempenho... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due to the expressive increase of non linear loads in the electric power systems it also grows, in alarming proportions, the problems related with harmonic distortions present in voltages and currents. Aiming the mitigation of harmonic distortions, the use of filters and devices of harmonic compensation are the techniques commonly used to reduce the flow of the main harmonic components that composes the mentioned distortion. This work is particularly addressed to investigations related to the use of filtering devices of passive nature, composed by hybrid arrangements of tuned filters and electromagnetic filters. In this context, this thesis presents unpublished contributions related with the development of mathematical models in the frequency domain for electromagnetic filters and the generalization of methodologies for performance analysis based on the behavior of the sequential harmonic components. The performance and adherence of the proposed models are evaluated in a comparative base of experimental nature, using a prototype of an electromagnetic filter of reduced power built considering the methodological guidelines originating from the theoretical analyses. The obtained models are used in the development of a computational application for performance analysis and optimization of projects of harmonic filtering systems. The analytical description proportioned for this calculation tool makes possible the individualized and systematic investigation of the electric system behavior for different sequential harmonic components. The detailed investigation of the individual contributions of each harmonic source, makes it is possible to identify actions for the appropriate choice of the topologies and other adjustments seeking the maximization performance of the filtering system, such as the definition of the number of resonant branches and respective syntonization frequencies... (Complete abstract click electronic access below) / Doutor
7

Performance evaluation of an active filter non-regenerative AC drive

Skorcz, Alex Joseph 10 October 2008 (has links)
The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE-519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed "half-controlled" boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.
8

Performance evaluation of an active filter non-regenerative AC drive

Skorcz, Alex Joseph 15 May 2009 (has links)
The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE–519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed “half-controlled” boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.
9

Performance evaluation of an active filter non-regenerative AC drive

Skorcz, Alex Joseph 15 May 2009 (has links)
The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE–519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed “half-controlled” boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.
10

Performance evaluation of an active filter non-regenerative AC drive

Skorcz, Alex Joseph 10 October 2008 (has links)
The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE-519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed "half-controlled" boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

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