No Brasil e no mundo a tecnologia nuclear vem ocupando posição de destaque com diversas aplicações na indústria, geração de energia, meio ambiente e na medicina, melhorando a qualidade de exames e tratamentos, consequentemente, a vida das pessoas. O urânio é o principal elemento utilizado em instalações nucleares, servindo como material base desde a geração de eletricidade à fabricação de radiofármacos. Nos anos 50, em meio à guerra fria, a então recém-criada Agência Internacional de Energia Atômica se propôs a supervisionar instalações nucleares e incentivar a fabricação de combustíveis nucleares com baixo teor de urânio, conhecidos como combustíveis do tipo Material Test Reactor (MTR), fabricados inicialmente na forma de U3O8 e mais tarde o U3Si2, ambos dispersos em alumínio. A utilização desta tecnologia requer uma constante melhoria de todos os processos que envolvem a fabricação do MTR sujeita a diversos protocolos internacionais, os quais procuram garantir a confiabilidade desse combustível do ponto de vista prático e ambiental. Dentro desse contexto, o controle de impurezas, do ponto de vista da economia de nêutrons, afeta diretamente a qualidade de qualquer combustível nuclear, fazendo-se necessário um controle rigoroso. A literatura reporta procedimentos que, além de gerar resíduos, são demorados e dispendiosos, pois necessitam de curva de calibração univariada e materiais de referência. Assim, o objetivo deste trabalho é estabelecer e validar uma metodologia de análise química quantitativa não destrutiva, de baixo custo e tempo de análise, tal como, minimizar a geração de resíduo para a determinação multielementar dos maiores constituintes (Utotal e Si) e as impurezas (B, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd e outros) presentes em U3O8 e U3Si2, atendendo as necessidades de reatores nucleares na qualificação de combustíveis nucleares do tipo MTR. Para tanto, foi aplicada a técnica de fluorescência de raios X que permite análises químicas rápidas e não destrutivas, além de não necessitar de tratamentos químicos prévios (dissolução, digestão e outros) na fase de preparação de amostras. Para as correções de efeitos espectrais e de matriz foram aplicados e avaliados os métodos de parâmetros fundamentais, de curva de calibração univariada e de calibração multivariada. Os resultados foram comparados por meios de testes estatísticos em conformidade com a norma ISO 17025 com os MRCs (123(1-7) e 124(1-7)) de U3O8 da New Brunswick Laboratory (NBL) e 16 amostras de U3Si2 cedidas pelo CCN do IPEN-CNEN-SP. A quimiometria demonstrou-se um método promissor para a determinação de maiores e menores constituintes em combustíveis nuclear a base de U3O8 e U3Si2, uma vez que a precisão e exatidão são estatisticamente iguais aos métodos de análises volumétrica, gravimétrica e ICP-OES. / In Brazil and worldwide the nuclear power has occupied a prominent position with many applications in industry, power generation, environment and medicine, improving the quality of tests and treatments, therefore people\'s lives. Uranium is the main element used in nuclear facilities and its employed as base material to generation of electricity in the manufacture of radiopharmaceuticals. In the \'50s, during the Cold War, the then newly created International Atomic Energy Agency proposed to oversee nuclear facilities and encourage the manufacture of nuclear fuels with low-enriched uranium (LEU) fuel came then type Material Test Reactor (MTR), manufactured initially in U3O8 and U3Si2 later, both dispersed in aluminum. The use of this technology requires a constant improvement of all processes involving the manufacture of MTR subject to several international protocols, which seek to ensure the reliability of the fuel from the standpoint of practical and environmental. In this context, the control of impurities, from the point of view of neutron economy, directly affects the quality of any nuclear fuel, so strict control is necessary. The literature has reported procedures which, beyond generating residues, are lengthy and costly, they need calibration curve and consequently reference materials. The aim of this work is to establish and validate a methodology for nondestructive quantitative chemical analysis, low cost and analysis time, as well as minimize the generation of waste, for multielement determination of major constituents (Utotal and Si) and impurities (B, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd and others) present in U3O8 and U3Si2, meeting the needs of nuclear reactors in the nuclear fuel qualification type MTR. For that purposes, will be applied the X-ray fluorescence technique which allows fast chemical and nondestructive analysis, aside from sample preparation procedures that do not require previous chemical treatments (dissolving, digesting, and others). To corrections like effects of spectral and matrix were applied and evaluated the fundamental parameter method, univariate calibration curve and multivariate calibration. The results were compared by means of statistical tests in accordance with ISO 17025 in MRCs (123 (1-7) and 124 (1-7)) MCRs of U3O8 from New Brunswick Laboratory (NBL) and 16 U3Si2 samples provided by CC of IPEN/CNEN-SP. The chemometrics is a promising method to determination of minor and major constituents on the U3Si2 and U3O8 basis nuclear fuel, because the precision and accuracy are statistically equal volumetric analysis, gravimetric and ICP-OES methods.

Kwan Wing Tak. / On t.p., "3" is subscript following the word: Pb (Zr, Ti) O" in the title. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves [96-100]). / Acknowledgement / Abstract / Chapter Chapter 1 --- Introduction --- p.1-1 / Chapter Chapter 2 --- Experimental Set-Up and Procedure / Chapter Section 2.1 --- General Description of Experiments --- p.2-1 / Chapter Section 2.2 --- High Temperature X-ray Diffraction Technique --- p.2-1 / Chapter Section 2.3 --- Sawyer-Tower Bridge --- p.2-3 / Chapter Section 2.4 --- Thermomechnical Analysis System(TMS) & Differential Scanning Calorimeter(DSC) --- p.2-4 / Chapter Section 2.5 --- Laser Experiment --- p.2-4 / Chapter Chapter 3 --- X-ray Experimental Results / Chapter Section 3.1 --- Investigation of PZT film on (100) MgO Single Crystal Substrate --- p.3-1 / Chapter Section 3.2 --- Investigaiton of PZT Bulk Materials by X-ray Diffractometer and Vacuum Chamber --- p.3-3 / Chapter Chapter 4 --- Experimental Data from TMS / Chapter Section 4.1 --- Experimental Details --- p.4-1 / Chapter Section 4. 2 --- Results --- p.4-2 / Chapter Chapter 5 --- "Measurement of Curie temperature using Ferroelectric Properties, Heat Capacity and Piezoelectric Properties of PZT" / Chapter Section 5.1 --- Investigation of the Ferroelectric Properties of PZT Bulk Material by Sawyer´ؤTower Bridge --- p.5-1 / Chapter Section 5.2 --- Investigation of the Heat Capacity of PZT Bulk Material by Differential Scanning Calorimeter (DSC) --- p.5-2 / Chapter Section 5.3 --- Investigation of Piezoelectric Properties of PZT Bulk Material by Laser Method --- p.5-3 / Chapter Section 5.4 --- Discussion of Results --- p.5-4 / Chapter Section 5.5 --- Data Summary --- p.5-5 / Chapter Chapter 6 --- Data Analysis and Discussion / Chapter Section 6.1 --- Analysis of Structural X-ray Data --- p.6-1 / Chapter Section 6.2 --- Analysis of TMS Data --- p.6-2 / Chapter Section 6.3 --- Discussion --- p.6-4 / Chapter Chapter 7 --- Conclusion --- p.7-1 / Reference

by Lee, Chun-Sing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 98-105). / Abstracts in English and Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / Table of Contents --- p.7 / List of Figures --- p.10 / List of Tables --- p.13 / Chapter Chapter 1 --- Introduction --- p.14 / Chapter 1.1. --- Ion implantation --- p.14 / Chapter 1.2. --- Scope of the thesis --- p.15 / Chapter Chapter 2 --- Background Theory --- p.17 / Chapter 2.1. --- Ion stopping --- p.17 / Chapter 2.2. --- The energy-loss process --- p.17 / Chapter 2.3. --- Kinematics of binary elastic collision --- p.20 / Chapter 2.4. --- Nuclear and electronic stopping --- p.21 / Chapter 2.5. --- Radiation Damage --- p.22 / Chapter 2.6. --- Spikes --- p.24 / Chapter 2.7. --- Topography of ion bombarded surface --- p.26 / Chapter Chapter 3 --- Equipment Reviews --- p.31 / Chapter 3.1. --- Metal Vapour Vacuum Arc Ion Source Implanter --- p.31 / Chapter 3.2. --- Atomic Force Microscopy --- p.34 / Chapter 3.3. --- Rutherford Backscattering Spectrometry --- p.37 / Chapter 3.4. --- X-ray Diffraction --- p.40 / Chapter Chapter 4 --- Study of Ion Beam Implanted Germanium by Atomic Force Microscopy and Rutherford Backscattering Spectrometry --- p.43 / Chapter 4.1. --- Introduction --- p.43 / Chapter 4.2. --- Experiments --- p.45 / Chapter 4.3. --- Results and discussion --- p.47 / Chapter 4.3.1. --- AFM --- p.47 / Chapter 4.3.2. --- RBS and ion channeling --- p.64 / Chapter 4.4. --- Conclusions --- p.71 / Chapter Chapter 5 --- Ion Beam Synthesised Cobalt Germanide Alloy by Metal Vapour Vacuum Arc Implantation --- p.73 / Chapter 5.1. --- Introduction --- p.73 / Chapter 5.2. --- Experiments --- p.74 / Chapter 5.3. --- Results and discussion --- p.74 / Chapter 5.3.1. --- XRD --- p.74 / Chapter 5.3.2. --- AFM --- p.78 / Chapter 5.3.3. --- RBS and ion channeling --- p.82 / Chapter 5.4. --- Conclusions --- p.87 / Chapter Chapter 6 --- Tip Artifacts in Atomic Force Microscope Imaging of Ion Bombarded Nanostructures on Germanium Surfaces --- p.89 / Chapter 6.1. --- Introduction --- p.89 / Chapter 6.2. --- Experiments --- p.90 / Chapter 6.3. --- Results and discussion --- p.90 / Chapter 6.4. --- Conclusions --- p.95 / Chapter Chapter 7 --- Conclusions --- p.96 / Bibliography --- p.98 / Publications --- p.105

Orientadores: Cris Adriano, Eduardo Granado Monteiro da Silva / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-09-02T06:12:12Z (GMT). No. of bitstreams: 1 Tasca_KelinRegina_D.pdf: 6364872 bytes, checksum: 7c505073990103d19ade00e5fcace964 (MD5) Previous issue date: 2017 / Resumo: Neste trabalho a dinâmica da transição de fase em sistemas de nanopartículas de óxido de titânio e de supercondutores de altas temperaturas críticas à base de Fe e a dinâmica da magnetização do NiO foram investigadas através de experimentos de difração de raios-X resolvida no tempo... O resumo poderá ser visualizado no texto completo da tese digital / Abstract: In this work the dynamics of the phase transition in systems of titanium oxides nanoparticles and hight Tc iron based superconductors and the magnetization dynamics of NiO were investigated by experiments of time resolved x-ray diffraction... The abstract is available with the full electronic document / Doutorado / Física / Doutora em Ciências / 1094215/2012 / CAPES

The ability of a ferromagnet to maintain its magnetic state in the absence of an external magnetic field has made ferromagnetic materials an important subject of study in physics since the end of the 19th century. Moreover, ferromagnetic materials are the cornerstone for data storage systems such as magnetic tapes, magnetic disk drives and magnetic random access memory. The discovery of the Giant Magneto Resistance (GMR) in 1988 suggested that, since the magnetic state of the electrical conductor has an important effect upon the current flow, there may also be an inverse influence of the current upon the magnetization. In this effect, predicted in 1989 [1] by Slonczewski and called Spin Transfer Torque, angular momentum transferred by a spin polarized current can exert a torque on the magnetization of a ferromagnetic material, changing the local magnetization and stimulating the precession of the magnetic moments, generating microwave signals. This provides a new method of manipulating magnetization without applying an external field. Large polarized currents lead to spin transfer effects which are the driving force for the magnetic dynamics of devices known as Spin Transfer Oscillators (STO). In this new kind of nano-device the emission of microwaves is stimulated by a DC electrical current and measured as a change in the output voltage due the GMR effect. The specific characteristics of these devices such as working frequency and DC current ranges, microwave emission linewidth, and maximum emission power among others, are given by the design and size of the device,and the nature of the magnetic oscillations producing the emission. Among the multiple types of STO that now exist , I have focused my research upon three of them: Spin Transfer Vortex Oscillators (STVO), Single Layer Spin Transfer Oscillators (SL-STO) and Orthogonal Pseudo Spin Valves. Within STVOs and SL-STOs we can nucleate what is called a magnetic vortex. A magnetic vortex is a curling of the in-plane of a magnetic layer with its centre pointing out of the magnetization plane. The gyration of this vortex due to STT produces a microwave emission < 1GHz with a greater emission power than that produced by the precession of magnetic moments in STOs. The phase-locked synchronisation of multiple vortices is expected to exhibit enhanced microwaved power and phase stability compared to a single vortex device, providing a solution to the drawbacks of the STO in the low frequency regime. On the other hand, Orthogonal Pseudo Spin Valves promote the nucleation of magnetic dissipative solitons, also called magnetic droplets. This type of magnetic structure has an opposite out of plane magnetization to the layer that contains it. Compared to the microwave emission of magnetic vortices , magnetic droplets have a higher frequency range and emission power. However, their nucleation is subject to large external fields being applied to the sample. In this thesis, I electrically characterized these devices and applied magnetic imaging techniques in order to go further in the understanding of the spatial features and dynamic behaviour of these magnetic structures. It is not possible to acquire this knowledge by only using electrical characterization. Understanding the magnetization dynamics in these devices is crucial for the design of STO based devices while imaging studies are required to prove the existence of these magnetic structures, as in case of the magnetic droplet. In chapter 2 I will introduce the background concepts of magnetism that are relevant to this thesis. I will go from the basics principles of ferromagnetism, its quantum mechanical treatment, and the theory that explain the dynamics of the magnetisation. I will also present the state of the art in experimental research in the field of spin transfer oscillators. My aim is to give the basic background needed to understand the results presented in this thesis. In chapter 3 I will introduce the two main experimental techniques used for imaging the magnetisation of the devices presented: Holography with Extended Reference by Autocorrelation Linear Differential Operator (HERALDO) and Time Resolved Scanning Kerr Microscopy (TRSKM). I will revise the theoretical background concepts and the development of the techniques in order to demostrate the uniqueness of each technique and how they were used in this thesis. It is interesting to note that while MOKE is a well-known and widely-used technique, far fewer laboratories in the world area able to perform time resolved measurements using MOKE, with the University of Exeter being one of them. Furthermore, HERALDO is a novel technique that is used for the first time to image magnetic structures within multilayer systems in this thesis, which is a milestone in the development of the techinque. In chapter 4 I present an investigation of the magnetization dynamics of a SL-STO. Electrical transport measurements provided an initial characterization of the device. We then used HERALDO for the first time to investigate the magnetization dynamics in an intermediate layer of a multilayer stack. We present time averaged measurements of the magnetisation of a magnetic vortex formed underneath a nano contact (NC) positioned on top of the multilayer, using a combination of x-ray holography and x-ray magnetic circular dichroism. In chapter 5 I present the first direct measurement at the time of a magnetic dissipative droplet, using holography with extended reference autocorrelation by linear differential operator (HERALDO). I studied the out of plane magnetisation of the free layer under a NC within an orthogonal pseudo spin salve. In chapter 6 I present and study STVO devices with pairs of NCs of 100 nm diameter and centre-to-centre separation D = 200 to 1100 nm, by a combination of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM). It will be shown that the dynamic behaviour of vortices and anti vortices changes when the distances between the NCs within the devices is changed.

O padrão ouro para a avaliação e o acompanhamento de desvios posturais é o exame radiológico. No entanto, a exposição à radiação ionizante aumenta o risco do desenvolvimento de câncer. Nessa perspectiva, se faz necessário o uso de métodos não invasivos com validade, repetibilidade e reprodutibilidade para mensurar os desvios posturais e acompanhar a sua progressão. Dessa maneira, o intuito do presente estudo foi verificar se o sistema Vert 3D fornece informações válidas referentes aos desvios posturais nos planos frontal e sagital de indivíduos de diferentes faixas etárias. Além disso, verificar a repetibilidade e a reprodutibilidade interavaliador do sistema Vert 3D nos planos sagital e frontal. Foi avaliada a postura sagital e frontal de 89 crianças de ambos os sexos e diferentes faixas etárias. A avaliação consistiu de duas etapas: exame radiológico e sistema Vert 3D. A primeira etapa foi realizada por um operador de raios X experiente e, a partir das imagens geradas, foram calculados os ângulos de Cobb nos planos sagital e frontal. A segunda etapa foi executada no mesmo dia por três avaliadores treinados no método e foram calculados os ângulos de deformidade do Vert 3D nos planos sagital e frontal e as flechas de escoliose do Vert 3D. O primeiro avaliador efetuou duas análises sucessivas, o segundo avaliador efetuou em seguida outras duas análises sucessivas e o terceiro avaliador efetuou a seguir uma única análise. Foram comparados e correlacionados os dados sucessivos de um mesmo avaliador para verificar a repetibilidade, os dados de diferentes avaliadores para verificar a reprodutibilidade interavaliador e entre os dados dos dois sistemas para verificar a validade do sistema Vert 3D. Para a repetibilidade no plano sagital, não houve diferença (p>0,05) e as correlações foram excelentes (ICC≥0,750, p<0,05). Para a reprodutibilidade interavaliador no plano sagital, não houve diferença (p>0,05) e as correlações foram satisfatórias (0,400<ICC<0,750, p<0,05) para a cifose de indivíduos de 6 a 10 anos e 16 a 18 anos e para a lordose de indivíduos de 11 a 15 anos e excelentes (ICC≥0,750, p<0,05) para a cifose de indivíduos de 11 a 15 anos e para a lordose de indivíduos de 6 a 10 e de 16 a 18 anos. E para a validade no plano sagital, houve diferença (p<0,05) e as correlações entre os ângulos de deformidade do Vert 3D (cifose e lordose) e os ângulos de Cobb (cifose e lordose) foram moderadas (0,400<r<0,699, p<0,05) para a cifose de indivíduos de 11 a 18 anos e para a lordose de indivíduos de 6 a 18 anos. Para a repetibilidade no plano frontal, não houve diferença (p>0,05) e as correlações foram satisfatórias (0,400<ICC<0,750, p<0,05) a excelentes (ICC≥0,750, p<0,05) para as flechas de escoliose do Vert 3D de indivíduos de 6 a 18 anos e para os ângulos de deformidade do Vert 3D (escoliose) de indivíduos de 11 a 18 anos. Para a reprodutibilidade interavaliador, não houve diferença (p>0,05) e as correlações foram satisfatórias (0,400<ICC<0,750, p<0,05) para as flechas de escoliose do Vert 3D de indivíduos de 6 a 18 anos e para os ângulos de indivíduos de 11 a 18 anos. E para a validade no plano frontal, houve diferença (p<0,05) entre os ângulos dos dois sistemas e as correlações foram moderadas (0,400<rho< 0,699, p<0,05) em relação à média das flechas de escoliose do Vert 3D à esquerda e à média dos ângulos de deformidade do Vert 3D à esquerda. Tendo em vista os resultados para repetibilidade e reprodutibilidade do Vert 3D nos planos sagital e frontal, o sistema pode ser utilizado para o acompanhamento das posturas sagital e frontal de indivíduos de 6 a 18 anos, a partir dos ângulos de deformidade do Vert 3D (cifose e lordose) e das flechas de escoliose do Vert 3D. Além disso, pode ser utilizado para o acompanhamento da postura frontal de indivíduos de 11 a 18 anos, a partir dos ângulos de deformidade do Vert 3D (escoliose). No entanto, na ausência de validade em relação ao padrão ouro, esse instrumento não pode ser utilizado para fins de avaliação dos ângulos de Cobb (cifose, lordose e escoliose). / The gold standard for the assessment and monitoring of postural deviations is the radiological examination. However, exposure to X-rays increases the risk to develop cancer. At this view, it is necessary the use of valid, repeatable and reproducible non-invasive methods to measure and monitor the progression of the postural deviations. Thus, the aim of this study was to verify if the Vert 3D system provides valid information regarding the postural deviations in frontal and sagittal planes of individuals of different age groups. Also, check the repeatability and inter-rater reliability of the Vert 3D system in sagittal and frontal planes. We evaluated the sagittal and frontal posture of 89 children of both sexes and different age groups. The evaluation consisted of two steps: radiological examination and Vert 3D system. The first step was performed by an experienced X-rays operator and from X-ray images were calculated Cobb angles in the sagittal and frontal planes. The second step was performed on the same day by three trained in the method evaluators. Was calculated the Vert 3D deformity angles in the sagittal and frontal planes and the Vert 3D scoliosis arrows. The first evaluator carried out two successive analyzes, the second evaluator then made two other successive analyzes and after the third evaluator made a single analysis. Were compared and correlated successive data of the each evaluator to verify repeatability, data from different evaluators to verify inter-rater reliability reproducibility and data from each system to verify the validity of Vert 3D system. For repeatability the in sagittal plane, was no difference (p>0.05) and the correlations were excellent (ICC≥0.750, p<0.05). For inter-rater reliability in the sagittal plane, was no difference (p>0.05) and the correlations were satisfactory (0.400 <ICC<0.750, p<0.05) for kyphosis in 6-10 years old and 16-18 years old individuals and for lordosis of 11-15 years old individuals and fine (ICC≥0.750, p<0.05) for kyphosis in 11-15 years old individuals 11 to 15 years and for lordosis in 6-10 years old and 16-18 years old individuals. And for validity in the sagittal plane, was significant differences (p<0.05) and the correlations between Vert 3D deformity angles (kyphosis and lordosis) and Cobb angles (kyphosis and lordosis) were moderate (0.400<r<0.699, p<0.05) for kyphosis in 11-18 years old individuals and for lordosis in 6-18 years old individuals. For the repeatability in the frontal plane, was no difference (p>0.05) and the correlations were satisfactory (0.400<ICC<0.750, p <0.05) to excellent (ICC≥0.750, p <0.05) for Vert 3D scoliosis arrows in 6-18 years old individuals and for Vert 3D deformity angles (scoliosis) in 11-18 years old individuals 11-18 years. For inter-rater reliability, was no difference (p>0.05) and the correlations were satisfactory (0.400<ICC<0.750, p<0.05) for Vert 3D scoliosis arrows in 6- 18 years old individuals and Vert 3D deformity angles (scoliosis) in 11-18 years old individuals. And for validity in the frontal plane, was significant differences (p<0.05) between the angles of the two systems and the correlations were moderate (0.400<rho<0.699, p<0.05) to the mean of Vert 3D scoliosis left arrows and the mean of Vert 3D deformity left angles (scoliosis). Considering the results for repeatability and inter-rater reliability of Vert 3D in both planes, the system can be used for monitoring the sagittal and frontal postures of 6-18 years old individuals 6-18 years from Vert 3D deformity angles (kyphosis and lordosis) and from Vert 3D scoliosis arrows. Moreover, it can be used for monitoring the frontal posture of 11-18 years old individuals from Vert 3D deformity angles (scoliosis). However, in the absence of validity related to the gold standard, the Vert 3D system cannot be used for diagnosis of Cobb angles (kyphosis, scoliosis, lordosis).

Thesis (Ph.D.)--M.I.T, Dept. of Physics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Cyrus Reza Safinya. / Ph.D.

In this thesis we present new ideas and mathematical insights in the field of Compton Scattering Tomography (CST), an X-ray and gamma ray imaging technique which uses Compton scattered data to reconstruct an electron density of the target. This is an area not considered extensively in the literature, with only two dimensional gamma ray (monochromatic source) CST problems being analysed thus far. The analytic treatment of the polychromatic source case is left untouched and while there are three dimensional acquisition geometries in CST which consider the reconstruction of gamma ray source intensities, an explicit three dimensional electron density reconstruction from Compton scatter data is yet to be obtained. Noting this gap in the literature, we aim to make new and significant advancements in CST, in particular in answering the questions of the three dimensional density reconstruction and polychromatic source problem. Specifically we provide novel and conclusive results on the stability and uniqueness properties of two and three dimensional inverse problems in CST through an analysis of a disc transform and a generalized spindle torus transform. In the final chapter of the thesis we give a novel analysis of the stability of a spindle torus transform from a microlocal perspective. The practical application of our inversion methods to fields in X-ray and gamma ray imaging are also assessed through simulation work.

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Agradecemos a compreensão. on 2017-03-09T14:01:43Z (GMT) / Submitted by Dominique Yukie Toyama null (dominique.toyama@gmail.com) on 2017-03-10T18:49:30Z No. of bitstreams: 1 Repositório.pdf: 9462693 bytes, checksum: b3c5b554b9ad7e33181206e7a901f8e6 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-16T19:50:08Z (GMT) No. of bitstreams: 1 toyama_dy_me_sjc.pdf: 9462693 bytes, checksum: b3c5b554b9ad7e33181206e7a901f8e6 (MD5) / Made available in DSpace on 2017-03-16T19:50:08Z (GMT). No. of bitstreams: 1 toyama_dy_me_sjc.pdf: 9462693 bytes, checksum: b3c5b554b9ad7e33181206e7a901f8e6 (MD5) Previous issue date: 2017-01-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho avaliou-se o comportamento mecânico e a homogeneidade estrutural de bilaminados cerâmicos com configuração convencional (compressão da zircônia) e bioinspirada (tração da zircônia) com e sem infiltração de sílica. Além disso, determinou-se a distribuição de tensões utilizando a análise de elementos finitos, e avaliou-se o modo de falha e o mecanismo de adesão da interface porcelana/zircônia. Amostras bilaminadas foram confeccionadas com Y-TZP e cerâmica injetável e divididos em 4 grupos (n=30): zircônia sob compressão (T), zircônia infiltrada sob compressão (I), zircônia sob tração (B) e zircônia infiltrada sob tração (BI); para teste da resistência à flexão biaxial. A infiltração por sílica ocorreu pelo método sol-gel. Os dados (MPa) do ensaio mecânico foram avaliados com análise de Weibull (IC 95 %). Análise de elementos finitos utilizou o critério de tensão máxima principal para avaliar a distribuição de tensões nos modelos e seus resultados foram apresentados em forma de figuras e gráficos da tensão máxima principal (TMP). A camada de infiltração foi caracterizada usando DRX e microscopia (MEV, MEV-FEG e EDS). O comportamento da interface foi analisado usando resistência ao risco e dureza. O grupo mais homogêneo estruturalmente foi o BI (m= 9,59). A concentração de tensão na cerâmica feldspática foi menor nos grupos bioinspirados. Houve formação de silicato de zircônia na superfície dos discos de zircônia infiltrados e preenchimento de defeitos superficiais e internos. A zircônia tradicional teve desempenho melhor do que a zircônia infiltrada no teste de resistência ao risco. A endentação interfacial mostrou que o elo mais fraco do conjunto é a cerâmica feldspática. Conclui-se que para melhorar o desempenho de bilaminados é preciso melhorar o material de recobrimento e não a adesão entre os materiais. / This study analyzed the mechanical behavior of bilayers using conventional arrangement (leucite ceramic under traction) and a bioinspired arrangement (zirconia under traction) with or without sol-gel silica infiltration, analyze stress distribution using FEA, characterize infiltration layer and observe interfacial behavior. 120 bilayered specimens were produced for biaxial flexural strength testing using Y-TZP and pressed ceramic and divided into 4 groups (n=30): zirconia under compression (T), infiltrated zirconia under compression (I), zirconia under traction (B) and infiltrated zirconia under traction (BI). The zirconia was infiltrated using sol-gel method. The results for the biaxial flexural strength (MPa) were analyzed using Weibull analysis (CI 95 %). Stress distribution within the models were examined using maximum principal stress and the results were presented as graphs and figures. The infiltration layer was characterized using XRD and microscopy (SEM, FEG-SEM and EDS). The interfacial behavior was analyzed using scratch test and micro-hardness indentation. The BI group was the most reliable (m=9.59). The stress distribution in the feldspar ceramic was better for the bioinspired groups. The infiltrated zirconia discs presented zirconia silicate formation on the surface and plugged internal flaws. The traditional zirconia had a better scratch performance compared to the infiltrated zirconia. The interfacial indentation showed that the weakest link of the set is the feldspar ceramic. To improve the performance of bilayers, a better coverage material is needed rather than an improvement in adhesion.

No Brasil e no mundo a tecnologia nuclear vem ocupando posição de destaque com diversas aplicações na indústria, geração de energia, meio ambiente e na medicina, melhorando a qualidade de exames e tratamentos, consequentemente, a vida das pessoas. O urânio é o principal elemento utilizado em instalações nucleares, servindo como material base desde a geração de eletricidade à fabricação de radiofármacos. Nos anos 50, em meio à guerra fria, a então recém-criada Agência Internacional de Energia Atômica se propôs a supervisionar instalações nucleares e incentivar a fabricação de combustíveis nucleares com baixo teor de urânio, conhecidos como combustíveis do tipo Material Test Reactor (MTR), fabricados inicialmente na forma de U3O8 e mais tarde o U3Si2, ambos dispersos em alumínio. A utilização desta tecnologia requer uma constante melhoria de todos os processos que envolvem a fabricação do MTR sujeita a diversos protocolos internacionais, os quais procuram garantir a confiabilidade desse combustível do ponto de vista prático e ambiental. Dentro desse contexto, o controle de impurezas, do ponto de vista da economia de nêutrons, afeta diretamente a qualidade de qualquer combustível nuclear, fazendo-se necessário um controle rigoroso. A literatura reporta procedimentos que, além de gerar resíduos, são demorados e dispendiosos, pois necessitam de curva de calibração univariada e materiais de referência. Assim, o objetivo deste trabalho é estabelecer e validar uma metodologia de análise química quantitativa não destrutiva, de baixo custo e tempo de análise, tal como, minimizar a geração de resíduo para a determinação multielementar dos maiores constituintes (Utotal e Si) e as impurezas (B, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd e outros) presentes em U3O8 e U3Si2, atendendo as necessidades de reatores nucleares na qualificação de combustíveis nucleares do tipo MTR. Para tanto, foi aplicada a técnica de fluorescência de raios X que permite análises químicas rápidas e não destrutivas, além de não necessitar de tratamentos químicos prévios (dissolução, digestão e outros) na fase de preparação de amostras. Para as correções de efeitos espectrais e de matriz foram aplicados e avaliados os métodos de parâmetros fundamentais, de curva de calibração univariada e de calibração multivariada. Os resultados foram comparados por meios de testes estatísticos em conformidade com a norma ISO 17025 com os MRCs (123(1-7) e 124(1-7)) de U3O8 da New Brunswick Laboratory (NBL) e 16 amostras de U3Si2 cedidas pelo CCN do IPEN-CNEN-SP. A quimiometria demonstrou-se um método promissor para a determinação de maiores e menores constituintes em combustíveis nuclear a base de U3O8 e U3Si2, uma vez que a precisão e exatidão são estatisticamente iguais aos métodos de análises volumétrica, gravimétrica e ICP-OES. / In Brazil and worldwide the nuclear power has occupied a prominent position with many applications in industry, power generation, environment and medicine, improving the quality of tests and treatments, therefore people\'s lives. Uranium is the main element used in nuclear facilities and its employed as base material to generation of electricity in the manufacture of radiopharmaceuticals. In the \'50s, during the Cold War, the then newly created International Atomic Energy Agency proposed to oversee nuclear facilities and encourage the manufacture of nuclear fuels with low-enriched uranium (LEU) fuel came then type Material Test Reactor (MTR), manufactured initially in U3O8 and U3Si2 later, both dispersed in aluminum. The use of this technology requires a constant improvement of all processes involving the manufacture of MTR subject to several international protocols, which seek to ensure the reliability of the fuel from the standpoint of practical and environmental. In this context, the control of impurities, from the point of view of neutron economy, directly affects the quality of any nuclear fuel, so strict control is necessary. The literature has reported procedures which, beyond generating residues, are lengthy and costly, they need calibration curve and consequently reference materials. The aim of this work is to establish and validate a methodology for nondestructive quantitative chemical analysis, low cost and analysis time, as well as minimize the generation of waste, for multielement determination of major constituents (Utotal and Si) and impurities (B, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd and others) present in U3O8 and U3Si2, meeting the needs of nuclear reactors in the nuclear fuel qualification type MTR. For that purposes, will be applied the X-ray fluorescence technique which allows fast chemical and nondestructive analysis, aside from sample preparation procedures that do not require previous chemical treatments (dissolving, digesting, and others). To corrections like effects of spectral and matrix were applied and evaluated the fundamental parameter method, univariate calibration curve and multivariate calibration. The results were compared by means of statistical tests in accordance with ISO 17025 in MRCs (123 (1-7) and 124 (1-7)) MCRs of U3O8 from New Brunswick Laboratory (NBL) and 16 U3Si2 samples provided by CC of IPEN/CNEN-SP. The chemometrics is a promising method to determination of minor and major constituents on the U3Si2 and U3O8 basis nuclear fuel, because the precision and accuracy are statistically equal volumetric analysis, gravimetric and ICP-OES methods.