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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.
21

Bases conceituais da implantação de redes elétricas inteligentes de distribuição de energia elétrica. / Conceptual basis for implementation of distribution smart grids.

Antonio Paulo da Cunha 18 May 2011 (has links)
As redes elétricas inteligentes significam um novo paradigma de fornecimento de energia, cuja concepção integra várias áreas de concentração, novas funcionalidades e funções até então não realizáveis, bem como uma pluralidade de tecnologias e a necessidade de infraestrutura de apoio para a sua realização. A transição das redes elétricas atuais para o modelo de rede inteligente constitui-se num processo complexo, que envolve aspectos técnicos, econômicos, regulatórios e sociológicos. Esta pesquisa visa contribuir significativamente para a solução dessa questão pela proposição das bases conceituais para realizar efetivamente um plano de implementação, respeitando condições vigentes e impostas por cenários de outros setores. O modelo proposto, centrado na expansão da automação, lança as bases para a análise dos impactos da rede elétrica inteligente, para a formulação, análise e seleção de alternativas de implementação. É introduzido o conceito e forma de avaliação de uma rede por meio da definição de um índice de inteligência de uma rede elétrica, composto de vários indicadores, de forma a expressar padrões de eficiência energética e operativa, aspectos de gestão de ativos e da qualidade do serviço. A proposta de alternativas para evolução da automação se baseia em um conjunto de funções pré-estabelecidas, que melhoram os indicadores de desempenho e apresentam custos e benefícios quantificáveis. / The smart grids mean a new paragon for energy supply, whose concept integrates several areas of concentration, functionalities and functions non achievable up to now, as well as a plurality of technologies and the need of supporting infrastructure for its accomplishment. The transition of the present electrical networks to the smart grid model constitutes a complex process, which involves technical, economical, regulatory and sociological aspects. This research aims to contribute significantly to the solution of this issue by proposing the conceptual basis for effectively perform an implementation plan taking into account the constraints imposed by scenarios from other sectors. The proposed model, focused in automation expansion, launches the basis for the impact analysis of Smart Grid in order to formulate, analyze and selection alternatives of implementation. The concept and evaluation method of grid through the definition of a grid intelligence index, composed by several indicators is introduced in order to express standards of energy and operational efficiency, asset management and quality of supply. The proposal of alternatives for automation evolution is based on a set of pre established functions, which improve the performance indicators and present valuable costs and benefits.
22

Novo modelo institucional do setor elétrico brasileiro: análise dos mecanismos de mitigação de riscos de mercado das distribuidoras. / New institucional model of the Brazilian electric sector: analysis of mitigation mechanisms of the market risks of distribution.

Fábio Luiz Cuberos 01 September 2008 (has links)
Com a reestruturação do modelo do setor elétrico brasileiro, a partir do Projeto RE-SEB, as empresas de distribuição de energia elétrica no Brasil tiveram que se adequar às novas regras de mercado, bem como alterar a sua maneira de administrar a empresa. Com o conceito de regulação por incentivos e competição por mercado, e não competição no mercado, novos mecanismos de mitigação de riscos de mercado foram introduzidos no modelo do setor elétrico, de tal forma que as empresas de distribuição de energia elétrica sejam ressarcidas de maneira justa pelo serviço prestado à sociedade. Diante desse contexto, a gestão eficiente da empresa e, conseqüentemente, o fato de atingir as metas de desempenho pré-estabelecidas pela alta administração de cada distribuidora depende cada vez mais do conhecimento das regras de mercado por seus colaboradores, bem como da utilização dos mecanismos de mitigação de riscos de mercado das distribuidoras. Assim, esse trabalho pretende analisar os principais mecanismos de mitigação de riscos de mercado das distribuidoras envolvidos no processo de repasse dos custos de aquisição de energia elétrica às tarifas dos consumidores finais, bem como avaliar os dispositivos previstos na regulamentação legal, inserindo um estudo de caso que analisa o portfólio de contratação de uma empresa de distribuição de energia elétrica fictícia, simulando variações nos níveis de contratação da mesma bem como no portfólio, avaliando a utilização dos mecanismos de mitigação de riscos de mercado e as alternativas simuladas, como também identificando os pontos de sucesso e os pontos a serem melhorados na gestão e contratação da distribuidora. / As the restructuring of the model of the Brazilian electric sector, with the Project RE-SEB, the electric energy distribution companies in Brazil had to adjust themselves to the new rules of the market, as well as modify their way of manage the company. As the concept of regulation for incentives (price cap model) and competition by market, and not competition in the market, new mechanisms to reduce the risks of the market had been introduced in the model of the electric sector, in such a way that the electric energy distribution companies receive a fair revenue for the service delivered to the society. In this perspective, the efficient management of the company and, consequently, the fact of reaching the goals in the performance targets established by the high administration, depends on the deep knowledge of the rules of market by its technical team , as well as the use of the mechanisms to reduce the risks of the market of the distribution utilities. In this way, this work intends to analyze (i) the main mechanisms available to the distribution companies in order to mitigate the market risks in the process of contract energy supply and to pass-though such costs to the final consumers, as well as (ii) evaluate the rules implemented in the legal regulation framework. Furthermore, to illustrate the analysis, a case study was developed focusing the contract portfolio of a fictitious distribution company, simulating variations in the contracted energy volume as well as in the portfolio composition, evaluating the uses of the mitigation mechanisms of the market risks and solution alternatives to minimize such risks, searching for improvements that could be made in the management strategy of energy supply contracting.
23

Sistema de apoio à fiscalização das concessionárias de distribuição de energia elétrica. / Power distribution utilities fiscalization suport system.

Gustavo Gonçalves Borges 18 November 2005 (has links)
O desafio atual para a regulação e fiscalização dos serviços públicos de distribuição de energia elétrica é incentivar a melhoria da qualidade nos serviços, promovendo uma melhor satisfação dos usuários, e garantir que sejam criados incentivos à expansão do setor. Devido à sua extensão e à diversidade de suas instalações, aliadas à regulação ainda em consolidação, a função das agências reguladoras e fiscalizadoras ainda depende da discricionariedade para a resolução de alguns problemas isolados, compreendidos ou não pelo arcabouço legal constituído para o setor. Devido a estes fatores, além da própria limitação física das agências, torna-se fundamental e imprescindível uma ferramenta de apoio à fiscalização. O sistema proposto neste trabalho está baseado nas regras atuais de fiscalização exercidas pelas agências de fiscalização de energia elétrica. Compreende as áreas de atendimento comercial, fiscalização econômico-financeira, informações da engenharia de distribuição, mercado energético, operação e manutenção das redes de distribuição, informações de planejamento, qualidade do fornecimento, segurança e monitoração dos níveis de tensão, parte dos requisitos para a avaliação global da qualidade dos serviços prestados, exercício fundamental para garantir que a fiscalização exerça a sua função primordial: controlar e fazer cumprir as regras definidas pela regulação. / The current challenge for the electric energy distribution utilities regulation and fiscalization is to stimulate the improvement of the quality in the services, promoting better satisfaction of the customers, and to guarantee that incentives to the expansion of the sector are created. Due to its extension and diversity of its installations, allied to the regulation still in consolidation, the function of the Brazilian regulation and fiscalization agencies still depends on the discretionary power for the resolution of some isolated problems, understood or not for the sector law outline constituted. These factors, beyond the proper physical limitation of the agencies, a support tool becomes essential and indispensable to the fiscalization. The developed system in this project is based on the current rules of fiscalization exerted by the electric energy fiscalization agencies. It includes the areas of commercial attendance, economic-financier fiscalization, distribution engineering information, energy market, operation and maintenance of the power distribution systems, corporate plan information, power supply quality, security and supervision of the tension levels, requirement parts for the global evaluation of the public services quality, basic exercise to guarantee the fiscalization primordial function: to control and to make implement the regulation defined rules.
24

[en] ESTIMATING THE WEIGHTED AVERAGE COST OF CAPITAL FOR ELECTRICITY DISTRIBUTION COMPANIES IN BRAZIL / [pt] DETERMINAÇÃO DO CUSTO DE CAPITAL PARA EMPRESAS DE DISTRIBUIÇÃO DE ENERGIA NO BRASIL

SUSANA FURQUIM XAVIER COUTO 06 April 2005 (has links)
[pt] Em uma indústria sujeita à regulamentação, o Custo Médio Ponderado de Capital - CMPC é parâmetro fundamental para a determinação da remuneração justa dos fornecedores de capital das empresas reguladas (investidores e credores), bem como para determinar a tarifa módica para o consumidor dos produtos ou serviços. Sabendo que as indústrias reguladas prestam, em geral, serviços básicos e de infra- estrutura, toda a sociedade é atingida pelas decisões a respeito desse custo, e sua determinação é parte importante das atividades do regulador. A teoria que suporta o conceito do CMPC remonta ao final da década de 50 e se encontra consagrada nos meios acadêmicos, empresariais e normativos. Entretanto, a metodologia para a determinação dos seus componentes prospectivos, ou seja, a determinação de qual será o CMPC no futuro, encontra divergências entre os principais autores e apresenta dificuldades operacionais. Essas dificuldades aumentam em um mercado de capitais pequeno quando comparado a outros países e em um ambiente político com uma curta história de estabilidade. O objetivo do presente trabalho é discutir a metodologia empregada pela Agência Nacional de Energia Elétrica - ANEEL para determinar o CMPC para empresas de distribuição de energia elétrica no Brasil à luz das melhores práticas e do conhecimento teórico sobre o tema. / [en] In regulated industries, estimating the weighted average cost of capital (CMPC) is important to the regulatory framework in order to establish both the fair return to the capital providers (investors and creditors) of the regulated companies, as well the reasonable price of goods or services for the customers. The regulated industries provide, in general, basic or infrastructure services and, as the whole society is affected by decisions about this cost, the determination of such is an important part of the regulators activities. The theoretical foundations supporting the concept of the weighted average cost of capital (CMPC) date back to the 1950 s and are solidly established in the academic and business circles, as well as in the regulating entities. The methodologies applied to estimate the expected weighted average cost of capital (CMPC) in future years generate, however, some controversy among the authors. In addition, difficulties exist in gathering the necessary data, especially in emerging markets with small capital markets and a short history of political stability. The objective of this dissertation is to analyze the methodology employed by Agência Nacional de Energia Elétrica - ANEEL (Brazilian National Agency for Electricity - the country s regulator of electricity generation, transmission and distribution) in the calculation of the weighted average cost of capital (CMPC) used in the tariff review process for the electricity distribution companies.
25

Ion Energy Measurements in Plasma Immersion Ion Implantation

Allan, Scott Young January 2009 (has links)
Doctor of Philosophy (PhD) / This thesis investigates ion energy distributions (IEDs) during plasma immersion ion implantation (PIII). PIII is a surface modification technique where an object is placed in a plasma and pulse biased with large negative voltages. The energy distribution of implanted ions is important in determining the extent of surface modifications. IED measurements were made during PIII using a pulse biased retarding field energy analyser (RFEA) in a capacitive RF plasma. Experimental results were compared with those obtained from a two dimensional numerical simulation to help explain the origins of features in the IEDs. Time resolved IED measurements were made during PIII of metal and insulator materials and investigated the effects of the use of a metal mesh over the surface and the effects of insulator surface charging. When the pulse was applied to the RFEA, the ion flux rapidly increased above the pulse-off value and then slowly decreased during the pulse. The ion density during the pulse decreased below values measured when no pulse was applied to the RFEA. This indicates that the depletion of ions by the pulsed RFEA is greater than the generation of ions in the plasma. IEDs measured during pulse biasing showed a peak close to the maximum sheath potential energy and a spread of ions with energies between zero and the maximum ion energy. Simulations showed that the peak is produced by ions from the sheath edge directly above the RFEA inlet and that the spread of ions is produced by ions which collide in the sheath and/or arrive at the RFEA with trajectories not perpendicular to the RFEA front surface. The RFEA discriminates ions based only on the component of their velocity perpendicular to the RFEA front surface. To minimise the effects of surface charging during PIII of an insulator, a metal mesh can be placed over the insulator and pulse biased together with the object. Measurements were made with metal mesh cylinders fixed to the metal RFEA front surface. The use of a mesh gave a larger ion flux compared to the use of no mesh. The larger ion flux is attributed to the larger plasma-sheath surface area around the mesh. The measured IEDs showed a low, medium and high energy peak. Simulation results show that the high energy peak is produced by ions from the sheath above the mesh top. The low energy peak is produced by ions trapped by the space charge potential hump which forms inside the mesh. The medium energy peak is produced by ions from the sheath above the mesh corners. Simulations showed that the IED is dependent on measurement position under the mesh. To investigate the effects of insulator surface charging during PIII, IED measurements were made through an orifice cut into a Mylar insulator on the RFEA front surface. With no mesh, during the pulse, an increasing number of lower energy ions were measured. Simulation results show that this is due to the increase in the curvature of the sheath over the orifice region as the insulator potential increases due to surface charging. The surface charging observed at the insulator would reduce the average energy of ions implanted into the insulator during the pulse. Compared to the case with no mesh, the use of a mesh increases the total ion flux and the ion flux during the early stages of the pulse but does not eliminate surface charging. During the pulse, compared to the no mesh case, a larger number of lower energy ions are measured. Simulation results show that this is caused by the potential in the mesh region which affects the trajectories of ions from the sheaths above the mesh top and corners and results in more ions being measured with trajectories less than ninety degrees to the RFEA front surface.
26

超音速自由分子流における非ボルツマン回転エネルギー分布の実験的解析

森, 英男, MORI, Hideo, 新美, 智秀, NIIMI, Tomohide, 秋山, 勇雄, AKIYAMA, Isao, 都築, 巧, TSUZUKI, Takumi 02 1900 (has links)
No description available.
27

Applications of noise theory to plasma fluctuations

Li, Bo, 1979- 28 August 2008 (has links)
Fluctuation phenomena are important to many physical systems, such as the fusion plasma. Noise theory is used to study the time and space correlations of stationary Markovian fluctuations that are statistically homogeneous and isotropic. The relaxation of the fluctuations is modeled by the diffusion equation. The spatial correlations are modeled by the exponential decay. Based on these models, the correlation function and the power spectral density of random fluctuations. We also find that the fluctuation-induced transport coefficients may be estimated by the correlation length and the correlation time. The theoretical results are compared with the observed plasma density fluctuations from tokamak and helimak experiments.
28

Žvaigždžių atmosferų modelių energijos kreivių tyrimas / A comparison of the stellar atmosphere model energy distributions

Dailidka, Edgar 24 September 2008 (has links)
Šiame darbe buvo palygintos tarpusavyje Kurucz, Castelli ir Kurucz (ATLAS9), PHOENIX (NextGen) ir MARCS žvaigždžių atmosferų modelių energijos kreives ir patikrintas modelių energijos kreivių atitikimą realių žvaigždžių energijos pasiskirstymui spektre. / Stellar atmosphere models energy distribution curves were investigated. Energy distributions of synthetic spectra for Kurucz, Kurucz & Castelli(ATLAS9), PHOENIX(NextGen), MARCS stellar atmosphere models are compared together. Also the stellar atmosphere models energy distribution curves are compared with the observed energy distributions (Straižys V., Sviderskienė Z., 1996). The synthetic color indices of the Kurucz, Kurucz & Castelli(ATLAS9) model for the UBV and Vilnius photometric systems were calculated. The synthetic color indices were compared with the observed mean intrinsic color indices.
29

Impact of flow energy distribution on the ecological status of rivers / Tėkmės energijos pasiskirstymo poveikis upelių ekologinei būklei

Gegužis, Ramūnas 18 December 2013 (has links)
The aim of the study - to investigate interaction regularities of water flow energy distribution and stream beds during the naturalization process, to identify morphometric changes in the beds of streams and to assess the impact of these factors on the ecological status of rivers. To achieving this aim, 6 specific tasks were identified: 1 Designing geostatistical models of hydromorphological characteristics of regulated and natural river beds based on the field research results; 2 Identifying morphometric characteristics of river beds based on geostatistical models; 3 Determining regularities of the flow energy distribution and its interaction with the stream bed; 4 Determining the abundance and composition of grass and woody vegetation in the investigated sections of streams; 5 Determining the diversity, composition and abundance of macrozoobenthos and fish species; 6 Identifying the impact of flow energy distribution and stream bed interaction on the ecological status of rivers. / Darbo tikslas – ištirti vandens tėkmės energijos pasiskirstymo ir upelių vagų sąveikos dėsningumus, vykstant natūralizacijos procesams, nustatyti morfometrinius pokyčius upelių vagose lemiančius veiksnius ir įvertinti jų poveikį upių ekologinei būklei. Darbo tikslui pasiekti buvo sprendžiami 6 uždaviniai: 1) taikant natūrinių tyrimų rezultatus, sudaryti geostatistinius reguliuotų ir natūralių vagų hidromorfologinių charakteristikų modelius; 2) pasinaudojus gautais modeliais, nustatyti morfometrines vagų charakteristikas; 3) pasinaudojus gautais modeliais, išsiaiškinti tėkmės energijos pasiskirstymo ir jos sąveikos su upelių vaga dėsningumus; 4) ištirti žolinės ir sumedėjusios augalijos gausą ir jos sudėtį tiriamų upelių atkarpose; 5) nustatyti makrozoobentoso ir juo besimaitinančių žuvų rūšinę įvairovę, sudėtį ir gausą; 6) išsiaiškinti tėkmės energijos pasiskirstymo ir upelių vagų sąveikos įtaką upių ekologinei būklei.
30

Ion Energy Measurements in Plasma Immersion Ion Implantation

Allan, Scott Young January 2009 (has links)
Doctor of Philosophy (PhD) / This thesis investigates ion energy distributions (IEDs) during plasma immersion ion implantation (PIII). PIII is a surface modification technique where an object is placed in a plasma and pulse biased with large negative voltages. The energy distribution of implanted ions is important in determining the extent of surface modifications. IED measurements were made during PIII using a pulse biased retarding field energy analyser (RFEA) in a capacitive RF plasma. Experimental results were compared with those obtained from a two dimensional numerical simulation to help explain the origins of features in the IEDs. Time resolved IED measurements were made during PIII of metal and insulator materials and investigated the effects of the use of a metal mesh over the surface and the effects of insulator surface charging. When the pulse was applied to the RFEA, the ion flux rapidly increased above the pulse-off value and then slowly decreased during the pulse. The ion density during the pulse decreased below values measured when no pulse was applied to the RFEA. This indicates that the depletion of ions by the pulsed RFEA is greater than the generation of ions in the plasma. IEDs measured during pulse biasing showed a peak close to the maximum sheath potential energy and a spread of ions with energies between zero and the maximum ion energy. Simulations showed that the peak is produced by ions from the sheath edge directly above the RFEA inlet and that the spread of ions is produced by ions which collide in the sheath and/or arrive at the RFEA with trajectories not perpendicular to the RFEA front surface. The RFEA discriminates ions based only on the component of their velocity perpendicular to the RFEA front surface. To minimise the effects of surface charging during PIII of an insulator, a metal mesh can be placed over the insulator and pulse biased together with the object. Measurements were made with metal mesh cylinders fixed to the metal RFEA front surface. The use of a mesh gave a larger ion flux compared to the use of no mesh. The larger ion flux is attributed to the larger plasma-sheath surface area around the mesh. The measured IEDs showed a low, medium and high energy peak. Simulation results show that the high energy peak is produced by ions from the sheath above the mesh top. The low energy peak is produced by ions trapped by the space charge potential hump which forms inside the mesh. The medium energy peak is produced by ions from the sheath above the mesh corners. Simulations showed that the IED is dependent on measurement position under the mesh. To investigate the effects of insulator surface charging during PIII, IED measurements were made through an orifice cut into a Mylar insulator on the RFEA front surface. With no mesh, during the pulse, an increasing number of lower energy ions were measured. Simulation results show that this is due to the increase in the curvature of the sheath over the orifice region as the insulator potential increases due to surface charging. The surface charging observed at the insulator would reduce the average energy of ions implanted into the insulator during the pulse. Compared to the case with no mesh, the use of a mesh increases the total ion flux and the ion flux during the early stages of the pulse but does not eliminate surface charging. During the pulse, compared to the no mesh case, a larger number of lower energy ions are measured. Simulation results show that this is caused by the potential in the mesh region which affects the trajectories of ions from the sheaths above the mesh top and corners and results in more ions being measured with trajectories less than ninety degrees to the RFEA front surface.

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