[pt] Este trabalho aborda o projeto de antenas omnidirecionais de duplorefletores, onde o refletor principal é obtido a partir de uma geratriz circular. A antena é composta de refletores circularmente simétricos e concêntricos que são alimentados por uma corneta cônica coaxial excitada pelo modo TEM para a produção de polarização vertical. Para realizar este estudo são utilizadas técnicas de síntese e de análise eletromagnética rigorosa. A técnica de análise eletromagnética rigorosa é baseada na associação do Método de Casamento de Modos para representar os campos no interior do alimentador e do Método dos Momentos para solucionar as equações integrais para o campo elétrico e para o campo magnético e determinar a corrente elétrica induzidas sobre as paredes metálicas externas e a amplitude dos modos sobre a abertura da corneta. A técnica de síntese destas antenas é baseada na aplicação dos princípios da Ótica Geométrica para modelar o subrefletor que irá produzir uma distribuição de fase uniforme em uma abertura cônica colocada em frente ao refletor principal com geratriz circular. O estudo exploratório sobre o desempenho destas antenas é dividido em três partes. Na primeira, as soluções fornecidas pela síntese ótica e aproximações para os campos na abertura são utilizadas para identificar configurações de antenas compactas ou que maximizem o ganho ao longo do plano horizontal. Entretanto, pode-se obter uma melhor iluminação da área de cobertura através da inclinação do lobo principal (down tilt). Para reduzir o custo de fabricação de um conjunto de antenas que atendam diferentes áreas de cobertura, pode-se utilizar o mesmo refletor principal e modelar os subrefletores para deslocar a direção de máximo do diagrama. Assim, em uma segunda etapa do estudo paramétrico, são considerados alguns refletores principais, e, para cada um deles, é obtida uma família de subrefletores modelados para deslocar o máximo do diagrama no plano vertical. Esta estratégia se torna efetiva na medida em que o custo de fabricação do subrefletor é menor do que o do refletor principal. Na terceira parte, utilizando o método híbrido composto pelo Método do Casamento de Modos e pelo Método dos Momentos, é feito o modelamento da corneta coaxial TEM com o objetivo de reduzir sua perda de retorno e estender sua banda de operação. Por fim, ainda utilizando este método híbrido, é feita uma análise rigorosa das antenas duplo-refletoras propostas neste trabalho, procurando otimizar o desempenho destas antenas em termos do diagrama de radiação e da perda de retorno. / [en] This work presents a design study of omnidirectional dual-reflector antennas, where the main reflector is obtained from a circular generatrix. The antenna is composed of two concentric circularly symmetric reflectors and it is fed by a coaxial conical horn excited by TEM mode to produce vertical polarization. To obtain the subreflector surface, the study employs a GO synthesis technique to shape the subreflector in order to produce a uniform phase distribution in a conical aperture placed in front of the main reflector. To validate the results, it is employed a rigorous electromagnetic analysis technique based on the association of Mode Matching Technique to represent the fields inside the horn and Method of Moments to solve the integral equations of electric and magnetic fields. The solution of Method of Moments yields the induced electric current on the outer surface of the horn and the amplitude of the modes on the aperture of the horn. The exploratory study is divided in three parts. First, by using the GO approximations for the aperture fields, the geometry parameters are explored to identify compact antenna configurations that maximize the gain along the horizontal plane. However, a more uniform coverage of the ground can be obtained by tilting the main lobe. Thus, in a second step of the parametric study, it is considered a family of designs with the same main reflector and a set of subreflectors that are designed for different tilt angle of main lobe. This strategy is effective to reduce the manufacturing costs of a family of antennas designed to provide different coverage. Third, by using the hybrid method, the TEM coaxial horn is shaped to reduce the return loss and extend its operating band, and, finally, the overall antennas performance is optimized by controlling radiation pattern and return loss.

Este trabalho apresenta a realização de experimentos no reator nuclear IPEN/MB-01 submetido à presença de um refletor com água pesada instalado na sua face oeste. Após a instalação do refletor no reator foram conduzidos três tipos de experimentos: A calibração das barras de controle, a verificação da influência do aumento da temperatura do moderador na reatividade e a medição das taxas de reações por meio da irradiação de fios e folhas de ativação. Devido às propriedades nucleares de interação de nêutrons com água pesada, notadamente sua elevada capacidade de espalhamento e sua baixa capacidade de absorção, é possível notar alterações no funcionamento do reator observadas pelas mudanças dos padrões de retiradas e inserções de barras de controle no núcleo. Essas alterações são apresentadas no decorrer do trabalho. / This work presents the accomplishiment of experiments in the IPEN/MB-01 research nuclear under presence of a heavy water reflector installed in its western wall. After reflectors assembly in the reactor, three types of experiments were conducted: The control rod calibration, the check of temperature\'s influence increasing under reactivity and the measurement of reaction rates by means wires and foil\'s activation. Due to the properties of neutron interaction with heavy water, especially their high scattering and low absorption cross sections, pattern changes operation could be observed by the control rods moving inside the core. These observations will be the focus of this work

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-11-30T14:46:17Z No. of bitstreams: 1 Sérgio Luiz Bohrer Filho_.pdf: 1393460 bytes, checksum: 335661e44d51f93aa77abb3a780e6e5a (MD5) / Made available in DSpace on 2015-11-30T14:46:17Z (GMT). No. of bitstreams: 1 Sérgio Luiz Bohrer Filho_.pdf: 1393460 bytes, checksum: 335661e44d51f93aa77abb3a780e6e5a (MD5) Previous issue date: 2015-10-14 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / Este trabalho apresenta um estudo de viabilidade de inserção de energia solar térmica na matriz elétrica brasileira, através de integração de um campo de energia termosolar concentrada com uma usina termelétrica de ciclo combinado localizada na Região Centro-Oeste. A atual conjuntura do setor elétrico, que apresenta crescimento do despacho termelétrico e consequente elevação dos custos de geração de energia elétrica, provocados principalmente por períodos de Energia Natural Afluente (ENA) abaixo da média, justifica o desenvolvimento de fontes alternativas. O objetivo principal deste estudo é apresentar um modelo de empreendimento de produção de eletricidade por meio de fonte solar térmica, compatível à realidade tecnológica e econômica do mercado de energia. O estudo baseia-se na simulação de integração de um campo solar com tecnologia de concentração Fresnel linear e geração direta de vapor superaquecido, junto à Usina Termelétrica Luís Carlos Prestes (UTE-LCP), no município de Três Lagoas, no estado de Mato Grosso do Sul. O desempenho do campo solar é verificado através do software System Advisor Model (SAM) da National Renewable Energy Laboratory (NREL) e a produção adicional de termeletricidade é determinada com base na análise de eficiência do ciclo de Rankine da UTE-LCP. Por fim, é realizada a análise financeira do projeto através de ferramentas de engenharia econômica, onde identifica-se um custo nivelado da energia elétrica (LCOE) de pelo menos 139,24 USD MW-1h-1, uma redução de 42,7% em relação às estimativas de custo internacionais para usinas heliotérmicas. Análises de sensibilidade indicam que o custo do capital tem impacto crítico sobre o LCOE, fato atribuído ao caráter de alta dependência dos recursos de capital da tecnologia solar térmica. / This work presents a study of concentrated solar power insertion in the Brazilian energy matrix, through integration of the solar energy with Luís Carlos Prestes Thermoelectric Power Plant (UTE-LCP) in Três Lagoas city. The current situation of the Brazilian electricity sector, which has presented strong growth of thermoelectric dispatch in recent years and the consequent increase in the cost of electricity generation, justifies the development of alternative energy sources. The purpose of this study is to present a model of electricity generation through thermal solar source compatible to technological and economic realities of the energy market. The study is based on evaluation of the linear Fresnel reflector with direct steam generation, because this configuration has investment, operation and maintenance attractive costs. The performance of the solar field is simulated in the System Advisor Model software (SAM) of the National Renewable Energy Laboratory (NREL). The predict performance is used with UTE-LCP operational database to estimate the additional electricity generation. Finally, the financial analysis is carried out through economic engineering tools, which identifies a Levelized Cost of Electricity (LCOE) of the 139.24 USD MW-1h-1 at least. This LCOE is 42.7% less than cost estimates for Concentrating Solar Power plants. Sensitivity analysis indicates that the cost of capital has critical impact on the LCOE, which was attributed to the character of high dependence on Concentrating Solar Power (CSP) capital resources.

Ces dernières années, un intérêt croissant est porté aux réflecteurs rétro-directifs aplatis dans le but de remplacer le réflecteur diédrique conventionnel, trop encombrant pour de nombreuses applications. Dans un premier temps, cette thèse étudie deux techniques différentes permettant de réduire l’épaisseur d’un réflecteur diédrique. L’Optique de transformation modifie la constitution matérielle de son volume intérieur alors que la modulation d’impédance de surface introduit une distribution d’impédance à sa surface. On examine également la possibilité de combiner ces deux techniques pour tirer le meilleur parti de chacune d’elle. La deuxième partie de cette thèse étudie l’origine des réflexions parasites pour les panneaux utilisant la modulation d’impédance de surface et propose de nouvelles règles de conception pour atténuer leurs niveaux. Finalement, une mise en oeuvre pratique est proposée pour une modulation d'impédance de surface généralisée qui utilise des impédances complexes et surpasse les performances de la modulation d’impédance classique. / In recent years, increasing interest incompact reflectors with retrodirective response is perceived since the conventional dihedral reflector is too bulky to be integrated within most applications. First, this thesis investigates two different techniques that might lead to lower profiles of the dihedral reflector. It explores the use of Transformation Optics that modifies the filling volume of such a device and Surface Impedance Modulation that introduces an impedance distribution over its surface. It also inspects the possibility of combining those two techniques to take benefit of their complementary advantages. The second part of this thesis investigates the source of parasitic lobes for surface impedance modulated panels and proposes new design rules to mitigate their levels. Finally, it also proposes a practical implementation for a specific setting of the generalized surface impedance modulation that makes use of complex impedances and outperforms a panel implementing the classical modulation.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-04-19T16:40:27Z No. of bitstreams: 1 Patricia Scalco_.pdf: 2617305 bytes, checksum: 329172a91dc38579cc85445e7b13abf1 (MD5) / Made available in DSpace on 2017-04-19T16:40:27Z (GMT). No. of bitstreams: 1 Patricia Scalco_.pdf: 2617305 bytes, checksum: 329172a91dc38579cc85445e7b13abf1 (MD5) Previous issue date: 2016-01-22 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / O estudo de diferentes fontes de energia é de extrema importância, tanto em termos econômicos e sociais, como no âmbito ambiental. Assim, o uso da energia solar para a geração de calor para alimentar processos que necessitam de temperaturas em torno de 300 ºC aparece como uma alternativa para suprir o uso de combustíveis fósseis em ambientes industriais, seja de forma parcial ou total. Para atingir essa faixa de temperatura, devem ser utilizados equipamentos de alto desempenho e que possam concentrar ao máximo a radiação solar. Assim, é utilizada a tecnologia de refletores Fresnel lineares, que se baseia no princípio de concentração solar, onde os raios solares incidem em espelhos que refletem essa radiação para um receptor. O receptor é composto por um tubo absorvedor e por uma segunda superfície refletora, conhecida como concentrador secundário, que tem como função maximizar a quantidade de raios absorvidos pelo receptor. Esse tipo de instalação tem se mostrado competitiva diante de outros tipos de concentração solar devido à sua estrutura simples, custo reduzido e fácil manutenção. Assim, neste trabalho serão analisados aspectos ópticos e térmicos do conjunto do receptor, tanto para o concentrador secundário do formato trapezoidal como para o CPC. Para isso, o estudo foi dividido em duas etapas. Na primeira etapa foi feito o traçado de raios para as duas geometrias do concentrador secundário estudadas afim de determinar o fator de interceptação e as perdas ópticas envolvidas neste processo. Além disso, foi analisada a influência da inserção de uma superfície de vidro na base do receptor. A segunda etapa consistiu na análise térmica, onde foi feito o estudo da transferência de calor no receptor com a finalidade de determinar a eficiência do sistema, bem como os fatores que influenciam no desempenho do mesmo. Na análise geométrica, o fator de interceptação para a concentrador secundário do tipo trapezoidal foi de 36% para o receptor aberto e 45% para o receptor com o fechamento de vidro. Para o concentrador secundário do tipo CPC, os resultados foram de 44% para o receptor aberto e 56% para o receptor isolado com vidro. Através da análise térmica, foi possível estabelecer a eficiência do sistema que, para a melhor condição de trabalho, DNI de 1000 W/m², foi de 80%. / The study of different energy sources is extremely important, both in economic and social scope, as well as in the environmental field. Thus, the use of solar energy for the generation of heat to feed processes that require temperatures around 300 ºC appears as an alternative to supply the use of fossil fuels in industrial environments, either partially or totally. To reach this temperature range, high-performance equipment must be used that can concentrate solar radiation to the maximum. Thus, Fresnel linear reflector technology is used, which uses the principle of solar concentration, where the solar rays focus on mirrors that reflect this radiation to the receiver. The receiver is composed of an absorber tube and a second reflecting surface whose function is to maximize the number of rays absorbed by the receiver. This type of installation has been competitive in comparison to other types of solar concentration because of its simple structure, low cost and easy maintenance. Thus, in this work will be analyzed optical and thermal aspects of the receiver set for the trapezoidal and the CPC secondary concentrator. For this, the study was divided into two stages. In the first stage the ray tracing was done for the two geometries of the secondary concentrator studied in order to determine the interception factor and the optical losses involved in this process. In addition, the influence of insertion of a glass surface on the base of the receptor was isolated by isolating it from the environment. The second stage consisted of the thermal analysis, where the heat transfer study was carried out in the receiver in order to determine the efficiency of the system as well as the factors that influence the performance of the system. In the geometric analysis, the interception factor for the trapezoidal secondary concentrator was 36% for the open receptor and 45% for the receptor with the glass enclosure. For the CPC secondary concentrator, the results were 44% for the open receptor and 56% for the receptor with the glass enclosure. Through the thermal analysis, it was possible to establish the efficiency of the system, which, for the best working condition, DNI of 1000 W/m², was 80%.

女性雜誌之出現，標舉將女性視為一特定閱聽眾。長期以來，女性受到父權意識型態的限制，權利義務被忽略，依附男性而生活，然而這種不平等的現象，隨著社會環境的變遷，而有緩和趨勢。而女性雜誌既為一「女性空間」，是否強化傳統的性別秩序，或呈現無刻板印象的性別角色，值得探討。 　　歷來探討大眾媒介和社會變遷關係的研究者，把其關係區分為三大類，包括反映者、強化者和促動者。但由於大眾媒介內容和社會環境變遷的時間，很難做清楚的劃分，對二者間的關係，至今仍莫衷一是。 　　本研究以創刊達二十五年的「婦女雜誌」為對象，企圖找出女性雜誌和女性價值變遷間的相關性。在相關研究中，可以發現，女性雜誌中所呈現的女性，基本仍偏向傳統形象，強調外貌、家庭比工作重要，研究焦點多半著重在人物描繪上。本研究則關切女性雜誌中的報導主題，及傳達的兩性價值和形象，是否因時間推移而有所改變。 　　研究結果發現，「婦女雜誌」中，以生活資訊報導量最多，但其所占比例逐年減少，同時安排位置也多半在整本雜誌的後半部，而偏向硬性的法律政治和社會議題，則呈逐年增加的情形，顯示「婦女雜誌」逐漸脫出傳統的窠臼，不再只把女性的關心焦點限囿在流行上，原屬男性領域的議題也日受重視。 　　「婦女雜誌」對兩性形象的呈現方式，仍以傳統角色占居主流，而代表較自由開放的形象，在女性方面，呈逐年增加的情形，而男性方面則呈逐年減少趨勢，顯示「婦女雜誌」在描繪女性時，鼓勵朝自由開放方向發展，而描繪男性時，則著重傳統性別秩序，但也鼓勵自由發展。 　　在兩性價值方面，「婦女雜誌」中所傳達的女性價值，朝向自由多元的方向發展，鼓勵女性做個有主見的人，但在男性價值方面，仍偏向傳統的價值，和根深柢固的男性形象相符合。 　　從社會背景變遷和「婦女雜誌」的報導內容來看，在民國59年以前，「婦女雜誌」偏向扮演社會變遷的促動者，到了民國60年開始，和社會變遷的時間差距拉近，反映者和強化者的角色開始突顯出來，但因時間不易明確劃分，促動者的角色也不能率爾去除。 　　從「婦女雜誌」的報導內容來看，在民國59年以前，父權意識型態色彩濃厚，但自民國60年開始，女性角色日益多元化，兩性關係也朝平等方向發展，顯示父權意識型態的威力已逐年減低。

<p>Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed.</p><p>Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWh_electrical and 800 kWh_thermal per m² cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing.</p><p>Low-concentrating photovoltaic systems for façade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules.</p><p>Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.</p>

Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed. Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWhelectrical and 800 kWhthermal per m2 cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing. Low-concentrating photovoltaic systems for façade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules. Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.

In the late spring of 2008, the Chevron-led Gulf of Mexico Gas Hydrate Joint Industry Project (JIP) expects to conduct an exploratory drilling and logging campaign to better understand gas hydrate-bearing sands in the deepwater Gulf of Mexico. The JIP Site Selection team selected three areas to test alternative geological models and geophysical interpretations supporting the existence of potential high gas hydrate saturations in reservoir-quality sands. The three sites are near existing drill holes which provide geological and geophysical constraints in Alaminos Canyon (AC) lease block 818, Green Canyon (GC) 955, and Walker Ridge (WR) 313. At the AC818 site, gas hydrate is interpreted to occur within the Oligocene Frio volcaniclastic sand at the crest of a fold that is shallow enough to be in the hydrate stability zone. Drilling at GC955 will sample a faulted, buried Pleistocene channel-levee system in an area characterized by seafloor fluid expulsion features, structural closure associated with uplifted salt, and abundant seismic evidence for upward migration of fluids and gas into the sand-rich parts of the sedimentary section. Drilling at WR313 targets ponded sheet sands and associated channel/levee deposits within a minibasin, making this a non-structural play. The potential for gas hydrate occurrence at WR313 is supported by shingled phase reversals consistent with the transition from gas-charged sand to overlying gas-hydrate saturated sand. Drilling locations have been selected at each site to 1) test geological methods and models used to infer the occurrence of gas hydrate in sand reservoirs in different settings in the northern Gulf of Mexico; 2) calibrate geophysical models used to detect gas hydrate sands, map reservoir thicknesses, and estimate the degree of gas hydrate saturation; and 3) delineate potential locations for subsequent JIP drilling and coring operations that will collect samples for comprehensive physical property, geochemical and other analyses

Este trabalho apresenta a realização de experimentos no reator nuclear IPEN/MB-01 submetido à presença de um refletor com água pesada instalado na sua face oeste. Após a instalação do refletor no reator foram conduzidos três tipos de experimentos: A calibração das barras de controle, a verificação da influência do aumento da temperatura do moderador na reatividade e a medição das taxas de reações por meio da irradiação de fios e folhas de ativação. Devido às propriedades nucleares de interação de nêutrons com água pesada, notadamente sua elevada capacidade de espalhamento e sua baixa capacidade de absorção, é possível notar alterações no funcionamento do reator observadas pelas mudanças dos padrões de retiradas e inserções de barras de controle no núcleo. Essas alterações são apresentadas no decorrer do trabalho. / This work presents the accomplishiment of experiments in the IPEN/MB-01 research nuclear under presence of a heavy water reflector installed in its western wall. After reflectors assembly in the reactor, three types of experiments were conducted: The control rod calibration, the check of temperature\'s influence increasing under reactivity and the measurement of reaction rates by means wires and foil\'s activation. Due to the properties of neutron interaction with heavy water, especially their high scattering and low absorption cross sections, pattern changes operation could be observed by the control rods moving inside the core. These observations will be the focus of this work