Barrières de transport (TB) sont un élément clé dans le contrôle de transport turbulent et atteindre la haute performance des ‘plasmas brûlants’. Les études théoriques abordent l’autorégulation de la turbulence comme une explication possible pour la formation de TB, mais une compréhension complète de ces dynamiques complexes est toujours manquante. Dans ce contexte, nous abordons l’auto-organisation dans le transport turbulent dans les plasmas de fusion dans le but de présenter une nouvelle compréhension de la dynamique des TB. Les outils numériques que nous utilisons des simulations de portée de la turbulence gyrocinétique plus complexe à simple turbulence des fluides 2D et prédateur-proie comme modèles.Deux principales caractéristiques de l'auto-organisation, les avalanches et les flux zonal (ZF), semblent contrôler transport à grande échelle. Dans la région de SOL (Scrape Off layer), événements avalancheux intermittents ne permettent pas séparation d'échelle dans le temps ou l'espace entre champs moyens et les modalités de fluctuation. Dans le bord (edge), la génération des doubles couches de cisaillement dans les profils de vitesse réduit le transport turbulent. Un modèle turbulent 2D pour la génération de ‘piedestal’, qui est non spécifique des plasmas de tokamak, a été mis au point, le piedestal étant localisée à l'interface entre les régions a différent amortissement d'écoulement zonal: edge et SOL. Les événements de relaxation quasi-périodiques sont étudiés réduisent le modèle à trois couplage des modes pour identifier l'interaction entre les streamers et les ZF et le rôle du Reynolds stress dans la génération et la saturation du TBs / Transport barriers (TB) are a key element in controlling turbulent transport and achieving high performance burning plasmas. Theoretical studies are addressing the turbulence self-regulation as a possible explanation for transport barrier formation but a complete understanding of such complex dynamics is still missing. In this context, we address self-organized turbulent transport in fusion plasmas with the aim of presenting a novel understanding of transport barriers dynamics. The numerical tools we use span simulations from the most complex gyrokinetic turbulence to simpler 2D fluid turbulence and predator-prey like models.Two features of self-organizations, avalanches and zonal flows (ZFs), appear to control large scale transport. In the SOL (Scrape Off Layer) , intermittent avalanche events do not allow for time or space scale separation between mean fields and fluctuation terms. In the edge, the generation of long living double shear layers in the profiles of the velocity reduces radial turbulent transport. Such radially distributed barriers govern profile corrugations. A 2D turbulent model for pedestal generation, which is not specific of Tokamak plasmas, has been developed, the pedestal being localized at the interface between regions with different zonal flow damping: the edge region, where zonal flows are weakly damped by collisions, and the SOL region characterized by zonal flow damping due to boundary conditions. Quasi-periodic relaxation events are studied reducing the model to three modes coupling to identify the interplay between streamers and ZFs and the role of Reynolds stress in the generation and saturation of TBs.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / With the advent of high-speed parallel-to-serial conversion interface standards reaching the 1.6 gigabit per second region, it is now possible to remote entire telemetry tracking systems over long distances without the need to maintain receivers, combiners, computers and antenna control units at the pedestal. In addition, it will soon be possible to digitize the RF signal(s) with high-speed flash-video analog-to-digital converters and transfer the data over these same links. This coupled with the improvements in fiber-optic L.E.D. and laser transmitters/ receivers and the constantly decreasing cost of fiber-optic cable, will allow for the eventual elimination of copper cabling for these interfaces. This will net a cost savings for the end user, provide for easier installations and increase the reliability of the overall system. This paper gives a brief history of the development of high-speed fiber-optic interface links, then expands into current interface standards and their utilization (such as MIL-STD-1553B, fiber data distributed interface (FDDI), HIPPI, etc.). Finally, a glimpse into the future of telemetry systems and the possibilities to soon be realized as major manufacturers of fiber-optic interfaces push well into the gigabit region. Topics include: • Replacement of existing copper cables between controller and pedestal using fiber-optic cable with interfaces that are not software-based intensive (black boxes); • Multiplexing pedestal control and status lines, RF feed commands, scan reference signals, and boresite video camera control; • Connecting and controlling multiple controllers and/or pedestals through one common interface cable; • Operating multiple tracking stations through one remote antenna controller; • Digitized RF telemetry signals sent along with pedestal, feed, video commands and status.

The application of a theoretical framework for calculating the radial electric field in the DIII-D tokamak edge plasma is discussed. Changes in the radial electric field are correlated with changes in many important edge plasma phenomena, including rotation, the L-H transition, and ELM suppression. A self-consistent model for the radial electric field may therefore suggest a means of controlling other important parameters in the edge plasma. Implementing a methodology for calculating the radial electric field can be difficult due to its complex interrelationships with ion losses, rotation, radial ion fluxes, and momentum transport. The radial electric field enters the calculations for ion orbit loss. This ion orbit loss, in turn, affects the radial ion flux both directly and indirectly through return currents, which have been shown theoretically to torque the edge plasma causing rotation. The edge rotation generates a motional radial electric field, which can influence both the edge pedestal structure and additional ion orbit losses. In conjunction with validating the analytical modified Ohm’s Law model for calculating the radial electric field, modeling efforts presented in this dissertation focus on improving calculations of ion orbit losses and x-loss into the divertor region, as well as the formulation of models for fast beam ion orbit losses and the fraction of lost particles that return to the confined plasma. After rigorous implementation of the ion orbit loss model and related mechanisms into fluid equations, efforts are shifted to calculate effects from rotation on the radial electric field calculation and compared to DIII-D experimental measurements and computationally simulated plasmas. This calculation of the radial electric field will provide a basis for future modeling of a fast, predictive calculation to characterize future tokamaks like ITER.

O presente trabalho tem como objetivo principal a produção e estudo de filmes de nitreto de alumínio (AlN) depositados por pulverização catódica (sputtering) reativa e a fabricação e caracterização de guias de onda tipo pedestal utilizando o AlN como núcleo. Inicialmente, filmes de AlN foram fabricados por pulverização catódica reativa (sputtering) de rádio frequência (RF) utilizando um alvo de alumínio (Al) com 99,999% de pureza, e nitrogênio (N2) como gás reativo. Subsequentemente, os filmes foram caracterizados mediante as técnicas de elipsometria, difração de raios X (DRX), espectroscopia de absorção por transformada de fourier na região do infravermelho (FTIR) e espectroscopia de absorção na região do ultravioleta e do visível (UV-VIS). Tendo as melhores condições ópticas e físicas para a deposição de filmes de AlN, foram fabricados neste trabalho guias de onda tipo pedestal utilizando estes filmes como núcleo. O guia de onda pedestal traz um processo de fabricação alternativo, em que a geometria do guia de onda determina-se na camada anterior ao do núcleo, assim já não é necessário delinear as paredes laterais da camada de núcleo facilitando desta forma, o processo de fabricação do dispositivo. Os guias de tipo pedestal fabricados neste trabalho foram definidos através da corrosão parcial do óxido de silício (SiO2) mediante a técnica de RIE (Reactive Ion Etching) usando gases trifluorometano (CHF3) e oxigênio (O2) como gases reativos. Uma vez definido o pedestal, um filme de nitreto de alumínio é depositado sobre o SiO2 com a finalidade de constituir o núcleo do guia de onda. O ar foi utilizado como revestimento superior, cujo índice de refração (n = 1) aumenta o confinamento da luz no núcleo e também para poder possibilitar a caracterização das perdas ópticas do dispositivo. Para esta caracterização usamos a técnica de vista superior que permitiu a análises das perdas ópticas de propagação para diferentes alturas de pedestal e diferentes espessuras de núcleo tanto para filmes de AlN orientado no plano cristalino (002) quanto para filmes de AlN amorfos. / The main objective of this work is the production and study of Aluminum Nitride (AlN) films deposited by reactive sputtering and the fabrication and characterization of pedestal optical waveguides using AlN as core. Initially, aluminum nitride films were produced by reactive sputtering using a 99.999% aluminum (Al) purity target, and nitrogen (N2) as the reactive gas. Subsequently, the films were characterized by ellipsometry, X-ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-visible spectroscopy (UV-VIS). Once the best optical and physical conditions for the deposition of AlN films were obtained, pedestal waveguides using these films as a nucleus were fabricated in this work. The pedestal waveguide provides an alternative manufacturing process where the geometry of the waveguide is determined in the pre-core layer, so it is no longer necessary to delineate the side walls of the core layer thereby facilitating the device fabrication process. The pedestal waveguides fabricated in this work were defined by the partial corrosion of SiO2 by the RIE (Reactive Ion Etching) technique using CHF3 and O2 gases as reactive gases. Once the pedestal is completed, an aluminum nitride film is deposited onto the SiO2 layer as the waveguide core. The air was used as an upper cladding, whose refractive index (n ? 1) increases the confinement of the light in the core and also allows the optical loss characterization. For this characterization, we used the superior view technique that allowed the analysis of optical propagation losses for different pedestal heights and different core thicknesses for both highly (002) oriented and amorphous AlN films.

No atual cenário da construção civil brasileira, onde há vigorosa competição, as empresas construtoras que conseguirem aplicar tecnologias que aumentem a eficiência econômica ou o desempenho de seus imóveis estarão em melhores condições de perpetuar os seus negócios. A tecnologia construtiva de piso elevado para áreas externas de edifícios apresenta-se como uma das alternativas que tem elevado potencial de contribuir com incremento do desempenho e da eficiência econômica dos edifícios, já que permite a racionalização da manutenção de parte das vedações horizontais exteriores e da manutenção de eventuais instalações dispostas em seu espaço de entrepiso. Estas possibilidades permitem uma redução do custo global da edificação, ao viabilizar intervenções de menor custo. Porém, para que sejam atingidos os benefícios propostos com a utilização desta tecnologia, é necessário dispor de informações técnicas capazes de orientar satisfatoriamente a concepção e a seleção entre alternativas disponíveis no mercado, para que as exigências dos usuários sejam respeitadas. Diante desta situação, justifica-se o presente projeto de pesquisa, cujo objetivo é a sistematização e análise crítica das informações pertinentes à tecnologia construtiva de piso elevado para áreas externas de edifícios, apresentando os principais aspectos que condicionam sua especificação, projeto e execução. Por meio do estabelecimento do estado da arte, são abordados os principais conceitos associados à tecnologia, à luz das principais funções e requisitos de desempenho de uma vedação horizontal exterior. Após a avaliação destas informações, e através da análise crítica das práticas de comercialização e de produção identificadas em estudo de campo, são apresentadas diretrizes para especificação, projeto e execução do sistema de piso elevado para áreas externas. / In the Brazilian building market, where there is a vigorous competition, the companies that have efficient technological process of production, based on product performance, will be able to turn themselves more competitive. The technology of raised access floor used in exterior areas appears as an alternative that can both increase the performance and increase the economical efficiency of the building. This technology may turn easier and cheaper the process of planned maintenance. In order to reach those benefits, it is essential to have technical information about raised access floor used in exterior areas to support the stage of design and the stage of technological selection, making the alternative selected, suitable to the user requirements. With this background justifies a project aiming the systematization and critical analysis of the main characteristics and requirements of the technology that regulate the selection, design and production stages. This dissertation will present the state of the art on raised access floor in external areas and will use the functions and requirements related to exterior floors, in order to discuss the main parameters which influence its conception and its production system. This discussion will use field information research.

O apelo estético da odontologia moderna tem impulsionado a busca por materiais cerâmicos de alto desempenho estético e mecânico. Este trabalho objetivou o desenvolvimento de fibras cerâmicas de alumina/aluminato de gadolínio (Al2O3/GdAlO3) obtidas por meio de fusão a laser (laser heated pedestal growth LHPG) e a sua aplicação como reforço de materiais odontológicos. Os pedestais foram obtidos a partir da mistura dos pós precursores (óxido de gadolínio (Gd2O3) e óxido de alumínio (Al2O3) pré-sinterizados para a obtenção de fibras de Al2O3/GdAlO3 de 0,8 mm de diâmetro médio. Variou-se: a velocidade de puxamento das fibras de 48mm/h a 240mm/h, em pedestais de composição eutética; e em outro grupo a composição dos pedestais (da composição eutética (23 mol% de Gd2O3 e 77 mol% de Al2O3) a 5 % (em peso) de excesso de Al2O3), puxadas com velocidade fixa de 96 mm/h. A melhor condição de obtenção da fibra foi com a velocidade de puxamento de 240mm/h que forneceu fibras com 0,6m de espaçamento médio entre as fases e 1790 MPa de resistência à flexão. Quando as fibras foram aplicadas como reforço de porcelana odontológica houve um aumento da resistência à flexão de 91MPa para 218MPa. Por meio desta metodologia, observou-se que as fibras cerâmica de Al2O3/GdAlO3 apresentaram elevado desempenho mecânico e compatibilidade com porcelanas odontológicas que indicam uma grande potencialidade de uso como reforço estrutural de cerâmicas odontológicas. / The esthetic appeal of modern Dentistry has prompted the search for ceramic materials with high esthetic and mechanical performance. This research aimed at the development of Al2O3/GdAlO3 ceramic fibers, obtained by laser heated pedestal growth (LHPG) and its application as reinforcement of dental materials. Pedestals were obtained from the mixture of precursor powders (Gd2O3 e Al2O3), pre-sintered to form Al2O3/ GdAlO3 fibers with average diameter of 0,8 mm. Variables were: fiber pulling rates (in pedestals of eutectic composition): from 48 mm/h to 240 mm/h; and pedestal composition: from eutectic composition (23 mol% of Gd2O3 and 77 mol% of Al2O3) to 5 wt% of excess Al2O3, pulled at 96 mm/h. The best results were obtained with a pulling rate of 240 mm/h, which originated fibers with average distance between phases of 0.6 m and three-point bending flexural strength of 1790 MPa. When fibers were used as re-enforcement of dental porcelain (Cerabien- Noritake), an increase in flexural strength from 91 MPa to 218 MPa was obtained. The methods employed in this study allowed the observation that Al2O3/GdAlO3 ceramic fibers presented high mechanical performance and compatibility with dental porcelain, indicating a significant potential as re-enforcement of dental ceramics for infrastructure.

La presente investigación tiene como propósito estudiar el poemario Pedestal para nadie del poeta César Calvo, un poeta de la generación del 60, cuya obra no ha sido analizada a profundidad, y ofrecer una aproximación crítica hacia su producción poética. Así, se plantea que, en este libro, el yo poético vive constantemente en el pasado, el mundo idílico e infantil, puesto que el presente supone muerte e infertilidad (la imposibilidad de la memoria) y ello implica fatalidad futura. Se ha dividido el análisis en dos partes. En la primera, la voz poética se lamenta de la imposibilidad de futuro que se refleja, en algunos poemas, en la maternidad frustrada. En la segunda, se examinará cómo el sujeto poético retorna constantemente a los recuerdos infantiles, tiempo en el que sí se evidencia la posibilidad de descendencia, es decir, el futuro, de distintas maneras. Los poemas estudiados en estos apartados han sido seleccionados teniendo en consideración un criterio temático; es decir, se ha escogido aquellos que se relacionan con la temática de la imposibilidad de futuro. El libro contiene poemas de distinta índole; sin embargo, debido al tópico escogido, interesa particularmente una visión más íntima. Por ello, se ha optado por analizar varios de los poemas en relación con otros, además de realizar un estudio intertextual desde perspectivas psicoanalíticas, filosóficas y mitológicas. / Tesis

In this work, a multi dimensional RF MEMS variable capacitor that utilizes electrostatic actuation is designed and fabricated on a 425um thick silicon substrate. Electrostatic actuation is preferred over other actuation mechanisms due to low power consumption. The RF MEMS variable capacitor is designed in a CPW topology, with multiple beams supported (1 - 7 beams) on a single pedestal. The varactors are fabricated using surface micromachining techniques. A 1um thick silicon monoxide (Er - 6) is used as a dielectric layer for the varactor. The movable membrane is suspended on a 2.5um thick electroplated gold pedestal. The capacitance between the membrane and the bottom electrode increases as the bias voltage between the membrane and the bottom electrode is increased, eventually causing the membrane to snap down at the actuation voltage. For the varactors designed herein, the actuation voltage is approximately 30 - 90V. Full-wave electromagnetic simulations are performed from 1 - 25GHz to accurately predict the frequency response of the varactors. The EM simulations and the measurement results compare favorably. A series RLC equivalent circuit is used to model the varactor and used to extract the parasitics associated with the capacitor by optimizing the model with the measurement results. The measured capacitance ratio is approximately 12:1 with a tuning range from 0.5 - 6pF. Furthermore, the measured S-parameter data is used to extract the unloaded Q of the varactor (at 1GHz) and is found to be 234 in the up state and 27 in the down state. An improved anodic bonding technique to bond high resistivity Si substrate and low alkali borax glass substrate that finds potential application towards packaging of MEMS varactors is investigated. To facilitate the packaging of the varactors the temperature is maintained at 400°C. The bonding time is approximately 7min at an applied voltage of 1KV.

Rapid development of fiber-optic communications network requirements increasing in recent years, The WDM technology and invention of anhydrous optical fiber open the possibility for optical fiber transmission bands broaden form 1.3 £gm to 1.6 £gm. Chromium doped yttrium aluminum garnet crystal fiber has characteristic of 300 nm broadband. Therefore, it¡¦s strongly desirable to develop a broadband fiber amplifier, laser or other active components for extending the flexibility of system architecture design in optical fiber communication. A few-mode chromium doped yttrium aluminum garnet double-clad crystalline fibers has been demonstrated by employing a modified version of LHPG technique, means using silica-YAG crystal co-drawing and multiple core-tuning process by precisely controlled inter-diffusion between YAG core and silica tube. In this thesis, electron probe x-ray micro-analysis, energy dispersive spectroscopy and transmission electron microscopy were utilized to confirm this fiber structure and composition. This fiber has gross gain about 2.3 dB with dual pumped by few hundred mini Watt. Significantly reduce the pump power threshold. Compared with the last large core size, few-mode (small core size) chromium doped yttrium aluminum garnet double-clad crystalline fibers has lower heat effect and higher power efficiency. To enhance the optical properties towards few modes or even single mode, not only reduce the transmission loss, but improve the device efficiency. Key words: Laser heated pedestal growth, Cr4+:YAG, Double-clad Crystal Fiber, gain

The presence of a large pinch velocity in the edge pedestal of high confinement (H-mode) tokamak plasmas implies that particle transport in the plasma edge must be treated by a pinch-diffusion theory, rather than a pure diffusion theory. Momentum balance also requires the inclusion of a pinch term in descriptions of edge particle transport. A numerical investigation of solving generalized pinch-diffusion theory using methods extended from the numerical solution methodology of pure diffusion theory has been carried out. The generalized diffusion equation has been numerically integrated using the central finite-difference approximation for the diffusion term and three finite difference approximations of the pinch term, and then solved using Gauss reduction. The pinch-diffusion relation for the radial particle flux was solved directly and used as a benchmark for the finite-difference algorithm solutions to the generalized diffusion equation. Both equations are solved using several mesh spacings, and it is found that a finer mesh spacing will be required in the edge pedestal, where the inward pinch velocity is large in H-mode plasmas, than is necessary for similar accuracy further inward where the pinch velocity diminishes. An expression for the numerical error of various finite-differencing algorithms is presented.