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Made available in DSpace on 2015-03-26T13:35:20Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4132930 bytes, checksum: 1169203ed33a5e53252821abccd6cf81 (MD5) Previous issue date: 2013-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work, ultra-thin layers of oxides grown using the technique of atomic layer deposition were characterized by measurements of x-ray reflectivity. TiO2:Al2O3 samples were grown using titanium isopropoxide (Ti(Hi-Pr)4), trimethylaluminum (Al(CH3)3) and water. The proportion of alumina was changed from 8 to 44% by varying the number of cycles of each precursor. TiO2:NiO samples were also grown using nickelocene (NiCp2) and water as precursors for NiO. The x-ray reflectivity measurements were performed at the Brazilian Synchrotron Light Laboratory and showed a reduction in deposition rate during growth of the TiO2:NiO series of samples, which prevented its use in the remainder of the study. The experimental data of TiO2:Al2O3 samples were analyzed using 03 simulation software: MOTOFIT, a free package designed to run on the IGOR Pro platform, and two MATHEMATICA codes; a first one based on kinematic approximation and another based in the Parrat recursion s method. The fitting procedure was based on two models: single layer, considering alumina as dopant, and multilayer, with sample composed of alternate layers of TiO2 and Al2O3. We conducted a detailed comparison of the results obtained from the softwares and models used and analyzed the influence of various parameters on the fits obtained. The fittings allowed the determination of various sample parameters, such as electron density and thickness of each layer and the roughness of the various interfaces. Comparing the software, we found that the best fits to the experimental data were obtained using the Parrat recursion s method. The multilayer model resulted in a better fit, reflecting the repetitive nature of the growth process, although the interface roughness values obtained were too large compared to layer thickness. Irrespective of software and the model used, the results show that atomic layer deposition can be used to obtain layers with controlled thickness and roughness less than 1 nm, independent of the number of cycles used in the deposition process. / Neste trabalho, camadas ultra-finas de óxidos, crescidas pela técnica de deposição por camada atômica, foram caracterizadas através de medidas de refletividade de raios-x. As amostras de TiO2:Al2O3 foram crescidas utilizando a técnica de deposição por camada atômica (ALD) usando como precursores isopropóxido de titânio (Ti(O-i-Pr)4), trimetilalumínio (Al(CH3)3) e água. A proporção de alumina foi modificada de 8 á 44%, variando a quantidade de ciclos de cada um dos precursores. Foram crescidas, também, amostras de TiO2:NiO, utilizando Niqueloceno (NiCp2) e água como precursores para NiO. As medidas de refletividade de raios-x foram realizadas nas instalações do Laboratório Nacional de Luz Síncrotron e mostraram uma redução na taxa de deposição durante o crescimento da série de amostras de TiO2:NiO, que impediu a sua utilização no restante do estudo. Os resultados experimentais das amostras de TiO2:Al2O3 foram analisados utilizando 03 softwares de simulação: MOTOFIT, um pacote livre desenvolvido para rodar na plataforma IGOR Pro, e dois códigos desenvolvidos para rodar na plataforma MATHEMATICA, o primeiro baseado na aproximação cinemática e o segundo no método de recursão de Parrat. Os ajustes das curvas experimentais foram feitos utilizando dois modelos: o de camada simples, considerando a alumina e o óxido de níquel como dopantes, e o de multicamada. Foi feita uma comparação detalhada entre os softwares e os modelos utilizados, analisando a influência dos vários parâmetros nos ajustes obtidos. Estes ajustes permitiram a determinação de diversos parâmetros característicos das amostras, tais como a espessura e a densidade eletrônica de cada camada e a rugosidade das várias interfaces. Na comparação entre os softwares, observou-se que o melhor ajuste aos dados experimentais foi obtido utilizando o método de recursão de Parrat. Em relação aos dois modelos utilizados, o de multicamada foi o que permitiu um melhor ajuste, refletindo a natureza repetitiva do processo de crescimento, apesar de fornecer valores de rugosidade das interfaces muito grande, comparados à espessura das camadas. Independente do software e do modelo utilizado, os ajustes permitem afirmar que a técnica de deposição por camada atômica permite a obtenção de camadas com espessura controlada e rugosidade menor que 1 nm, independente do número de ciclos utilizados na deposição.

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Orientadora: Ana Maria Falcão de Aragão Sadalla / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação / Made available in DSpace on 2018-08-13T20:26:18Z (GMT). No. of bitstreams: 1 Guimaraes_MonicaNarciso_D.pdf: 6221947 bytes, checksum: 1abaf0122a1a283022c38a6a42bbd8cc (MD5) Previous issue date: 2009 / Resumo: Este trabalho de pesquisa se propõe a revelar a constituição dos saberes de uma professora no processo de ensino e de aprendizagem de Ciências, construídos no contexto da atividade pedagógica, pelos registros docentes e pelas narrativas dos alunos. Os saberes docentes, como foco central deste estudo, são tomados como integrados e mobilizados em minha prática docente, constituindo assim a minha profissionalidade. Para tanto, utilizei como quadro de referência, as contribuições teóricas de dois pesquisadores, Lee Shulman e Maurice Tardif. O recorte de pesquisa retrata a execução de um projeto pedagógico em Ciências, intitulado Um Corpo em Construção, que prevê a construção de um corpo humano feito pelos alunos do 8º ano do Colégio Pedro II, Unidade Humaitá II, no Rio de Janeiro, focalizando o ano de 2006. A narrativa como opção metodológica trouxe a possibilidade de provocar um diálogo entre a prática vivida e as construções teóricas formuladas nesta e sobre estas vivências. Para este estudo, três momentos foram selecionados como significativos: O dia de montagem, O dia da Exposição Final - Edição 2006, e Uma reflexão sobre as narrativas ficcionais dos alunos e seu processo de elaboração. Como método de análise, a estratégia de triangulação dos dados permitiu uma inserção mais aprofundada no contexto de onde emergiram os fatos e dados recuperados pela memória. Por meio da análise de duas histórias produzidas no projeto pedagógico, as de Larissa e Carlos Eduardo, esta pesquisa revela os saberes construídos na vivência deste projeto, mediatizados pelas interações - emergentes ou intencionais - entre professora e alunos. Em especial, revela que a constituição de tais saberes se dá por um processo intencional de reflexividade. / Abstract: This research work intends to reveal the construction of the acquirements about a teacher in the teaching and learning process of Sciences, built in the context of the pedagogic activity by educational registrations and students' narratives. Teacher's knowledge, as a central focus of this study, are taken as integrated and mobilized in my educational practice, thus composing my professionalism. To do so, I used as a reference picture two researchers' theoretical contributions, Lee Shulman and Maurice Tardif. The outline of this research portrays the execution of a pedagogic project in Sciences, entitled "A Body in Construction", which foresees the construction of a human body done by students of the 8th year of the School Pedro II, Unit Humaitá II, in Rio de Janeiro, related to 2006. The narrative as methodological option brought the possibility to evoke a dialogue between the experimented practice and the theoretical constructions formulated in this and other experiences. For this study, three moments were selected as significant: The day of assembly, The day of the Final Exhibition-Edition 2006, and A contemplation on the students' fictional narratives and their elaboration process. As a method for analysis, the strategy of triangulation of the data allowed a deeper insight in the context from where the facts and data recovered by memory have emerged. By analysis of two stories produced in the pedagogic project, the Larissa's and Carlos Eduardo's ones, this research reveals the acquirements built in the experience of this project, mediated by emerging or intentional interactions between teacher and students. Especially, it reveals that the construction of such acquirements occurs by an intentional process of reflexivity. / Doutorado / Educação, Conhecimento, Linguagem e Arte / Doutor em Educação

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Em aplicaÃÃes prÃticas de energia solar ativa e passiva, ou para outros fins construtivos, o revestimento superficial do material que absorve a radiaÃÃo solar tem um papel importante no que concerne à absorÃÃo e à emissÃo de radiaÃÃo solar e tÃrmica, influenciando diretamente na relaÃÃo custo-benefÃcio do equipamento. Revestimentos superficiais para as placas absorvedoras de radiaÃÃo solar, ou superfÃcies seletivas, alteram as relaÃÃes de ganho e perda de energia do equipamento e, por isso, o desempenho dos diferentes revestimentos disponÃveis, seus tipos e custos, alÃm de Ãreas potenciais de aplicaÃÃo devem ser conhecidos. Em geral, coletores de placa plana sem superfÃcies seletivas operam em temperaturas inferiores a 100ÂC, sendo utilizados no aquecimento de Ãgua, em processos de secagem, etc. Existem aplicaÃÃes prÃticas como fogÃes solares, sistemas de refrigeraÃÃo, dessalinizadores tÃrmicos onde sÃo necessÃrias temperaturas muito elevadas que sà sÃo alcanÃadas pelo uso de superfÃcies seletivas. Para alta eficiÃncia, os coletores solares devem possuir um mÃximo de absorbÃncia no espectro solar enquanto mantÃm um mÃnimo de emitÃncia no infravermelho. Este trabalho apresenta um estudo comparativo de superfÃcies seletivas para coletores solares utilizadas nos maiores centros que utilizam energias renovÃveis. SÃo apresentadas as mediÃÃes experimentais da temperatura em placas absorvedoras e da radiaÃÃo solar global e direta incidente sobre as placas em funÃÃo do tempo. As amostras foram testadas nas condiÃÃes ambientais de Fortaleza. Os valores experimentais foram usados na determinaÃÃo dos valores para a emissividade, apÃs a realizaÃÃo de um balanÃo de energia em regime permanente nessas amostras. As temperaturas de estagnaÃÃo nas amostras foram tambÃm calculadas mostrando o desempenho desses materiais. SÃo tambÃm apresentadas as anÃlises microscÃpicas (microscÃpico eletrÃnico de varredura) das diferentes superfÃcies. Os resultados mostram claramente o desempenho das amostras quando expostas à radiaÃÃo solar e que o procedimento desenvolvido para esse trabalho pode ser utilizado na determinaÃÃo de um valor mÃdio para a emissividade tÃrmica a partir de mediÃÃes mais simples. / Em aplicaÃÃes prÃticas de energia solar ativa e passiva, ou para outros fins construtivos, o revestimento superficial do material que absorve a radiaÃÃo solar tem um papel importante no que concerne à absorÃÃo e à emissÃo de radiaÃÃo solar e tÃrmica, influenciando diretamente na relaÃÃo custo-benefÃcio do equipamento. Revestimentos superficiais para as placas absorvedoras de radiaÃÃo solar, ou superfÃcies seletivas, alteram as relaÃÃes de ganho e perda de energia do equipamento e, por isso, o desempenho dos diferentes revestimentos disponÃveis, seus tipos e custos, alÃm de Ãreas potenciais de aplicaÃÃo devem ser conhecidos. Em geral, coletores de placa plana sem superfÃcies seletivas operam em temperaturas inferiores a 100ÂC, sendo utilizados no aquecimento de Ãgua, em processos de secagem, etc. Existem aplicaÃÃes prÃticas como fogÃes solares, sistemas de refrigeraÃÃo, dessalinizadores tÃrmicos onde sÃo necessÃrias temperaturas muito elevadas que sà sÃo alcanÃadas pelo uso de superfÃcies seletivas. Para alta eficiÃncia, os coletores solares devem possuir um mÃximo de absorbÃncia no espectro solar enquanto mantÃm um mÃnimo de emitÃncia no infravermelho. Este trabalho apresenta um estudo comparativo de superfÃcies seletivas para coletores solares utilizadas nos maiores centros que utilizam energias renovÃveis. SÃo apresentadas as mediÃÃes experimentais da temperatura em placas absorvedoras e da radiaÃÃo solar global e direta incidente sobre as placas em funÃÃo do tempo. As amostras foram testadas nas condiÃÃes ambientais de Fortaleza. Os valores experimentais foram usados na determinaÃÃo dos valores para a emissividade, apÃs a realizaÃÃo de um balanÃo de energia em regime permanente nessas amostras. As temperaturas de estagnaÃÃo nas amostras foram tambÃm calculadas mostrando o desempenho desses materiais. SÃo tambÃm apresentadas as anÃlises microscÃpicas (microscÃpico eletrÃnico de varredura) das diferentes superfÃcies. Os resultados mostram claramente o desempenho das amostras quando expostas à radiaÃÃo solar e que o procedimento desenvolvido para esse trabalho pode ser utilizado na determinaÃÃo de um valor mÃdio para a emissividade tÃrmica a partir de mediÃÃes mais simples. / In practical applications of active and passive solar energy, or other construction purposes, the coating material which absorbs solar radiation has an important role as regards the absorption and emission of thermal radiation and, directly influencing the cost benefit the product. Surface coatings for solar radiation-absorbing plate or selective surfaces, changing the relationship of gain and loss of energy of the equipment and, therefore, the performance of the various coatings available types and their costs as well as potential areas of application should be known. In general, flat plate collectors operate without selective surfaces at temperatures below 100  C, and for the heating of water in drying processes, etc.. There are practical applications such as solar cookers, refrigeration systems, thermal desalination plants where they are needed at very high temperatures that are only achieved by the use of selective surfaces. For high efficiency, solar collectors should have a maximum absorbance in the solar spectrum while maintaining a minimum infrared emittance. This paper presents a comparative study of selective surfaces for solar collectors used in the larger centers that use renewable energy. Shows the experimental measurements of the temperature and the plates absorbing solar radiation and directly incident on the plates as a function of time. Samples were tested in environmental conditions in Fortaleza. The experimental values ​​were used in determining values ​​for the emissivity, after conducting an energy balance in steady state in these samples. The stagnation temperatures in the samples was also calculated showing the performance of these materials. Are also presented microscopic analysis (scanning electron microscopy) of different surfaces. The results clearly show the performance of samples when exposed to solar radiation and the procedure developed for this work may be used in determining an average value for the thermal emissivity measurements from simpler. / In practical applications of active and passive solar energy, or other construction purposes, the coating material which absorbs solar radiation has an important role as regards the absorption and emission of thermal radiation and, directly influencing the cost benefit the product. Surface coatings for solar radiation-absorbing plate or selective surfaces, changing the relationship of gain and loss of energy of the equipment and, therefore, the performance of the various coatings available types and their costs as well as potential areas of application should be known. In general, flat plate collectors operate without selective surfaces at temperatures below 100  C, and for the heating of water in drying processes, etc.. There are practical applications such as solar cookers, refrigeration systems, thermal desalination plants where they are needed at very high temperatures that are only achieved by the use of selective surfaces. For high efficiency, solar collectors should have a maximum absorbance in the solar spectrum while maintaining a minimum infrared emittance. This paper presents a comparative study of selective surfaces for solar collectors used in the larger centers that use renewable energy. Shows the experimental measurements of the temperature and the plates absorbing solar radiation and directly incident on the plates as a function of time. Samples were tested in environmental conditions in Fortaleza. The experimental values ​​were used in determining values ​​for the emissivity, after conducting an energy balance in steady state in these samples. The stagnation temperatures in the samples was also calculated showing the performance of these materials. Are also presented microscopic analysis (scanning electron microscopy) of different surfaces. The results clearly show the performance of samples when exposed to solar radiation and the procedure developed for this work may be used in determining an average value for the thermal emissivity measurements from simpler.

A common way to measure height in aerial vehicles is to use a radar height altimeter (RHM). Since the RHM transmits radar pulses that can be detected, a passive alternative would be desirable in military applications. The idea to use reflected signals from the Global Positioning System (GPS) as a bistatic radar, has been established over the last years. The GPS signals are already present and would not reveal aeroplanes in covert operations. In this thesis, the use of reflected GPS signals as a bistatic, passive altimeter is examined. A simulation model has been developed and implemented, and simulations using the model have been done. Different types of ground cover have been investigated, both water and land types, with varying reflectivity and scattering behaviour. For larger terrain variations, e.g. mountains and valleys, a ground elevation database has been used. Furthermore, several parameters, like the antenna coverage and the satellite elevation angle, have been varied and the result of this examined. The results of these simulations show that measuring height is possible for bothsea and land surfaces. The accuracy depends on several error factors, like a bias originating from surface roughness and measurement errors due to noise in the receiver. The simulations also show that the most important design parameter is the antenna, which must be designed to give a sufficiently large SNR, capture the specular reflection and avoid unwanted reflections.

Room temperature photomodulated reflectance (PR), Photoluminescence (PL) and double crystal x-ray diffraction (DCXRD) measurements have been performed on a series of tensilely strained InxGa1-xAs (0.316 ≤ x ≤ 0.533) multiple quantum well (QW) structures, with In0.80Ga0.20As0.43P0.57 barriers. The DCXRD measurements provided accurate information on composition, strain and layer thickness, while PR was used to determine the energies of the full manifold of allowed and forbidden critical point interband QW transitions. A three-band effective mass formalism was used to model the QW transitions to derive structural information on each sample. The energies of the ground-state QW transitions, H11 and L11, were found to increase with tensile strain, becoming degenerate near 0.36% tensile strain. Room temperature PR and conventional reflectance (R) measurement have been performed on two I.R. emitting InGaAs/GaAs/A1As vertical cavity surface emitting laser (VCSEL) structures. The R measurements were modelled using a transfer matrix formalism to determine errors in the growth fluxes. A new PR lineshape model has been developed based on energy dependent Seraphin coefficients, to describe the cavity mode interaction with a confined-state QW transition. The model is demonstrated on a set of PR spectra, and used in a novel way to derive the Deltaepsilon2 spectrum of the QW layers directly. The results are compared with those taken of the QW layers directly after removing the top Bragg stack reflector. Whilst the QW layers in one sample were found to be close to nominal, the in composition of QW in the other sample was found to depart significantly from the nominal 23%, and was found to be 28%. Room temperature and ~ 80K PR measurements were performed on three InAs/GaAs self-assembled quantum dot (QD) structures: a sample with a single layer of QDs, and two with two layers. The PR revealed five equally spaced confined-state QD transitions, at both 80K and room temperature, with ~ 54 meV separation. The behaviour of the QD1 transition as a function of temperature was investigated and an anomalous increase in linewidth was observed on cooling. Annealing of one of the samples produced a strong blue shift (~ 250 meV) and narrowing of the QD transitions.

The contribution to the global sea level change from the large ice sheet of Greenland and Antarctica if both ice sheet where to melt completely, is estimated to be approximately 70 meters. How much the actual contribution would be, is due to complex ice dynamics still unclear. It is crucial to gain knowledge about the spatial distribution of wet and frozen beds, in order to increase the understanding of ice-sheet flow. There are yet no complete models available that can fully explain and describe ice sheet motion and the feedback mechanisms that are involved, making this topic important for future predictions and modelling of the impact of a warming climate. Radar sounding can be used for distinguish the different reflectivity between wet and frozen beds, this is however limited by uncertainties caused by scattering and attenuation. To be able to map the spatial distribution of subglacial water, attenuation needs to be taken into account. Here, mapping of water under a smaller part of the Greenland ice sheet was performed, and three different methods for acquiring attenuation values was used to obtain a suitable value of the attenuation. A CMP analysis, an attenuation model based on temperature data and an attenuation estimation derived from common-offset radar data, the mean attenuation value from these methods was used for the determination of the reflectivity. Hydraulic potential calculations was also performed, analyzed and compared with the result from the mapping of the reflectivity. Higher reflectivity was observed closer to the front of the glacier, indicating wetter basal condition in that area. This area did also have more moulins and sinks which could lead water from the surface down to the base of the ice. / De båda istäckena Grönland och Antarktis uppskattas kunna bidra till den globala havsytehöjningen med ungefär 70 meter om de bägge istäckena skulle smälta helt och hållet. Hur mycket det faktiska bidraget skulle bli, är på grund av komplex isdynamik fortfarande oklart. Det är av yttersta vikt att öka kunskapen om den rumsliga fördelningen av frusna och icke-frusna bottnar under ett istäcke, för att öka förståelsen om isrörelse. Det finns i nuläget inga modeller som helt och fullt kan beskriva och förklara istäckens rörelse och de återkopplingsmekanismer som är involverade, vilket gör detta ämne viktigt för framtida förutsägelser och modellering av inverkan av ett allt varmare klimat.Radar kan användas för att särskilja den olika reflektivitet som uppvisas mellan frusna och icke-frusna bottnar, detta är dock begränsat på grund av dämpning och spridning av radarvågor genom isen. För att kunna kartera den rumsliga fördelningen av subglacialt vatten, behövs bland annat dämpningen i isen tas med i beräkningarna.Kartering av vatten under en mindre del av istäcket på Grönland har utförts i detta arbete, och för att erhålla ett bättre värde på dämpningen i isen användes tre olika metoder. En CMP-analys, en dämpningsmodell baserad på temperatur data och en dämpningsbedömning baserad på common-offset radardata, och medelvärdet på dämpningen från dessa tre metoder användes för fastställandet av reflektivitet i det undersökta området. Beräkningar av hydraulisk potential utfördes också, vilket analyserades och jämfördes med resultatet från karteringen av reflektivitet.Högre reflektivitet observerades närmre fronten av glaciären, vilket är en indikation på att vatten finns vid botten i det området. I detta område fanns också fler brunnar som skulle kunna leda ner vatten från ytan till botten av glaciären.

Relying mainly on R. B. Pippin’s and D. Moggach’s interpretative works on Kant and Hegel, the thesis tackles the problem of the reception of Kant by Hegel. It does so by looking into the impact of Kant’s first critique on the Preface, the Introduction and the first part of the section Self-consciousness of the Phenomenology of Spirit. Three Kantian conditions for there to be freedom are identified and shown to be reinterpreted by Hegel in a continuist perspective. These three conditions are spontaneity, reflectivity and negativity which propels and retains the free Kantian subject in the Hegelian becoming of reality.

Maintenance of aging buried infrastructure and reinforced concrete are critical issues in the United States. Inexpensive non-destructive techniques for mapping and imaging infrastructure and defects are an integral component of maintenance. Ground penetrating radar (GPR) is a widely-used non-destructive tool for locating buried infrastructure and for imaging rebar and other features of interest to civil engineers. Conventional acquisition and interpretation of GPR profiles is based on the arrival times of strong reflected/diffracted returns, and qualitative interpretation of return amplitudes. Features are thereby generally well located, but their material properties are only qualitatively assessed. For example, in the typical imaging of buried pipes, the average radar wave velocity through the overlying soil is estimated, but the properties of the pipe itself are not quantitatively resolved. For pipes on the order of the radar wavelength (<5-35 cm), pipe dimensions and infilling material remain ambiguous. Full waveform inversion (FWI) methods exploit the entire radar return rather than the time and peak amplitude. FWI can generate better quantitative estimates of subsurface properties. In recent decades FWI methods, developed for seismic oil exploration, have been adapted and advanced for GPR with encouraging results. To date, however, FWI methods for GPR data have not been specifically tuned and applied on surface collected common offset GPR data, which are the most common type of GPR data for engineering applications. I present an effective FWI method specifically tailored for common-offset GPR data. This method is composed of three main components, the forward modeling, wavelet estimation and inversion tools. For the forward modeling and iterative data inversion I use two open-source software packages, gprMax and PEST. The source wavelet, which is the most challenging component that guarantees the success of the method, is estimated with a novel Sparse Blind Deconvolution (SBD) algorithm that I have developed. The present dissertation indicates that with FWI, GPR can yield better quantitative estimates, for example, of both the diameters of small pipes and rebar and their electromagnetic properties (permittivity, conductivity). Also better estimates of electrical properties of the surrounding media (i.e. soil or concrete) are achieved with FWI.