Made available in DSpace on 2014-10-09T12:52:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:24Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:01/14033-0

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The use of new materials in the sanitation industry aims to improve water treatment conditions and optimize the performance of the structures of sewage systems. Studies show that investments in sanitation are four times more effective than health. Manhole (PV) is an integral structure of the collection networks of major importance sewage because it is the sewage flow of the meeting from various facilities that are guided and follow for further processing. Non-destructive tests are widely used in modern industry worldwide to evaluate the quality and detection of changes in structure, small surface flaws, presence of cracks and other physical disruptions, being capable of detecting flaws in structures prematurely allowing constant monitoring and real time frame. The technique of acoustic emission (AE) is effective both during subsequent tests the implementation of the structure, guaranteeing their structural integrity, and in the real-time monitoring of the frame subject to the usual charging service, while performing its function without need of interrupting. To properly investigate the structure is necessary to know how the defects are and their respective acoustic activity. In this study, the acoustic emission signals generated in polyethylene manholes by variable axial deformation during loading are characterized both in time domain and in the frequency domain creating the signature of the defect. / A utilizaÃÃo de novos materiais na indÃstria do saneamento, visa melhorar as condiÃÃes do tratamento de Ãgua e otimizar o desempenho das estruturas de redes coletoras de esgoto. Estudos comprovam que os investimentos realizados em saneamento bÃsico sÃo quatro vezes mais efetivos que na saÃde. PoÃo de visita (PV) à uma estrutura integrante das redes coletoras de esgotos de grande importÃncia, pois nele ocorre o encontro do fluxo de esgotos provenientes de diversas instalaÃÃes que sÃo orientados e seguem para o posterior tratamento. Os ensaios nÃo destrutivos sÃo largamente utilizados na indÃstria moderna em todo o mundo para avaliaÃÃo da qualidade e detecÃÃo de variaÃÃes na estrutura, pequenas falhas superficiais, presenÃa de trincas e outras interrupÃÃes fÃsicas, sendo capaz de detectar prematuramente falhas em estruturas permitindo a monitoraÃÃo constante da estrutura e em tempo real. A tÃcnica de emissÃo acÃstica (EA) à eficaz tanto na fase de testes subsequentes à implementaÃÃo da estrutura, garantindo sua integridade estrutural, quanto no monitoramento em tempo real d a estrutura sujeita a carregamento usual de serviÃo, enquanto desempenha sua funÃÃo, sem necessidade de interrupÃÃo. Para investigar corretamente a estrutura à necessÃrio conhecer como os defeitos se manifestam e sua respectiva atividade acÃstica. Neste trabalho, os sinais de emissÃo acÃstica gerados em poÃos de visita de polietileno por deformaÃÃo axial durante carregamento variÃvel sÃo caracterizados tanto no domÃnio do tempo quanto no domÃnio da frequÃncia criando a assinatura do defeito.

Made available in DSpace on 2014-10-09T12:42:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:11Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tomografia por Coerência Óptica, ou simplesmente OCT (acrônimo do inglês: Optical Coherence Tomography), é uma técnica para geração de imagens de seções transversais de meios espalhadores ao comprimento de onda utilizado. A OCT é baseada em interferometria óptica e gera imagens comumente correlacionadas às imagens geradas exames histológicos com a vantagem de ser indolor, não invasiva e não utilizar radiação ionizante. Este estudo dividiu-se em dois objetivos distintos, um refere-se à aplicação de sinais interferométricos de autocorrelação para a formação de imagens de amostras com estruturas complexas. O segundo objetivo foi o estudo das estruturas denominadas de harmônicos e sua aplicação no aumento da resolução axial de um sistema OCT. Com relação à primeira parte, constatou-se que o sinal interferométrico de autocorrelação é muitas vezes ignorado ou descartado pela OCT tradicional. Análises mais profundas da teoria de interferometria, juntamente com alguns estudos anteriores, apontaram para a possibilidade de gerar imagens de maior complexidade morfológica utilizando o sinal de autocorrelação, com a vantagem de se utilizar um arranjo óptico mais simples e também possibilitar imagens estáticas de amostras em movimento axial. Para testar os benefícios e as limitações da técnica de autocorrelação (Au-OCT) foi montado em laboratório e foram realizadas imagens de amostras no repouso e em movimento e confrontadas com imagens geradas no sistema OCT convencional. O sistema de Au-OCT foi capaz de gerar imagens de estruturas diversas (dentes, filmes plásticos entre outros), e apesar de possuir uma qualidade de imagem inferior à OCT, ela apresentou vantagens quando a amostra sofre deslocamentos axiais. Já em relação as características harmônicas, que se apresentam em amostras de alta refletividade óptica como falsas estruturas em imagens OCT, todo um estudo para o entendimento do fenômeno foi desenvolvido. Demonstrou-se também a possibilidade de utilização dessas estruturas para aprimorar a resolução axial diferencial (entre estruturas da própria amostra) através de um estudo numérico e experimental. Para isso padrões dimensionais do tipo degrau foram mensurados e os resultados tratados de acordo com procedimentos metrológicos, mostrando que os harmônicos podem ser utilizados para promover o aumento de resolução axial de um fator de aproximadamente dois. Por fim uma análise crítica sobre os resultados e uma discussão sobre perspectivas dos temas abordados, foram realizada. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:09/13764-3

Made available in DSpace on 2014-10-09T12:52:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:24Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Cerâmicas elétricas de Ba2In2O5 foram preparadas pelo método convencional de mistura de óxidos, e pela mistura e cristalização dos nitratos metálicos, para verificar o efeito do tamanho inicial das partículas na transição de fase ordemdesordem e na condutividade elétrica. Foram feitas substituições utilizando os cátions Gd3+ e Er3+, para verificar o efeito destes cátions na condutividade elétrica do indato de bário. Foi também preparado o óxido de índio pela técnica de complexação de cátions, e as nanopartículas obtidas foram caracterizadas por diversas técnicas. As principais técnicas de caracterização utilizadas foram: análise térmica, espectroscopia de absorção na região do infravermelho com transformada de Fourier, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de raios X convencional e utilizando radiação síncrotron, espalhamento de raios X a baixos ângulos, espectroscopia de energia dispersiva, espectroscopia Raman e medida da condutividade elétrica por espectroscopia de impedância. Os principais resultados mostraram que os tratamentos térmicos de calcinação e sinterização exercem forte influência na obtenção da fase Ba2In2O5. Fases espúrias são facilmente formadas no Ba2In2O5 também decorrentes da interação deste com a umidade. Um menor tamanho inicial de partículas favorece a redução na temperatura de transição de fase de segunda ordem. A introdução do Er, em teores relativamente baixos, produziu aumento na condutividade elétrica e simultânea redução na temperatura de transição de fase. Altos teores de Er e Gd dão origem a múltiplas fases. Na decomposição térmica do citrato de índio é formado um composto intermediário. A calcinação do citrato de índio produziu um material particulado com tamanho nanométrico, mesmo para temperaturas de até 900 ºC. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:01/14033-0

Considere a variedade Tn x S1 com coordenadas (t;x) e considere uma 1-forma diferencial fechada e real a(t) em Tn. Neste trabalho consideramos o operador Lpa = dt +a(t) Λ ∂x de D\'p em D\'p+1, onde D\'p é o espaço das p-correntes da forma u = ∑ Ι I Ι = puI (t, x)dtI. O operador acima define um complexo de cocadeia formado pelos espaços vetoriais D\'p e pelos homomorfismos lineares Lpa : D\'p → D\'p+1. Definiremos o que significa resolubilidade global no complexo acima e caracterizaremos para quais 1-formas a o complexo é globalmente resolúvel. Faremos o mesmo com respeito a hipoeliticidade global no primeiro nível do complexo. / Consider the manifold Tn x S1 with coordinates (t;x) and let a(t) be a real and closed differential 1-form on Tn. In this work we consider the operator Lpsub>a = dt +a(t) Λ ∂x de D\'p from D\'p to D\'p+1, where D\'p is the space of all p-currents u = ∑ Ι I Ι = puI (t, x)dtI . The above operator defines a cochain complex consisting of the vector spaces D\'p and of the linear maps Lpa : D\'p → D\'p+1. We define what global solvability means for the above complex and characterize for which 1-forms a the complex is globally solvable. We will do the same with respect to global hypoellipticity on the first level of the complex.

This research presents a pulse-by-pulse analysis of Oscillometric blood pressure waveform at systolic, diastolic and mean arterial pressure points. Using a mathematical optimization technique, pulses are characterized into component harmonic by minimizing the least square error. The results at the important pressure points are analyzed and compared for different subject using different waveform extraction techniques. Blood pressure is estimated using the harmonic parameters. The approach studies changes in the parameters as oscillometric blood pressure recording is done. 8 harmonic parameters are obtained from the pulse characterization and are used to estimate Systolic arterial Blood Pressure, Mean arterial Blood Pressure, and Diastolic arterial Blood Pressure. The estimates are compared with our reference value to determine which has the best agreement. The proposed method is further compared with Maximum Amplitude Algorithm and Pulse Morphology Algorithm. The effect of oscillometric waveform extraction methods on the proposed method is observed. The experiment established the fact that the extraction technique can alter the shape of oscillometric pulses. The methods were compared and it was observed that the used extraction methods did not make any significant difference on the accuracy, using this technique.

L’échantillonnage est une étape clé dans le rendu graphique. Il permet d’intégrer la lumière arrivant en un point de la scène pour en calculer sa couleur. Généralement, la méthode utilisée est l’intégration Monte Carlo qui approxime cette intégrale en choisissant un nombre fini d’échantillons. La réduction du biais et de la variance de l’intégration Monte Carlo est devenue une des grandes problématiques en rendu réaliste. Les techniques trouvées consistent à placer les points d’échantillonnage avec intelligence de façon à rendre la distribution la plus uniforme possible tout en évitant les régularités. Les années 80 ont été de ce point de vue un tournant dans ce domaine, avec l’apparition de nouvelles méthodes stochastiques. Ces méthodes ont, grâce à une meilleure compréhension des liens entre intégration Monte Carlo et échantillonnage, permis de réduire le bruit et la variance des images générées, et donc d’améliorer leur qualité. En parallèle, la complexité des méthodes d’échantillonnage s’est considérablement améliorée, permettant d’obtenir des méthodes à la fois rapides et efficaces en termes de qualité. Cependant, ces avancées ont jusqu’à là été faites par tâtonnement et se sont axées sur deux points majeurs : l’amélioration de l’uniformité du motif d’échantillonnage et la suppression des régularités. Bien que des théories permettant de borner l’erreur d’intégration existent, elles sont souvent limitées, voire inapplicables dans le domaine de l’informatique graphique. Cette thèse propose de rassembler les outils d’analyse des motifs d’échantillonnages et de les mettre en relation. Ces outils peuvent caractériser des propriétés spatiales, comme la distribution des distances entre points, ou bien spectrales à l’aide de la transformée de Fourier. Nous avons ensuite utilisé ces outils afin de donner une expression simple de la variance et du biais dans l’intégration Monte Carlo, en utilisant des prérequis compatibles avec le rendu d’image. Finalement, nous présentons une boite à outils théorique permettant de déterminer la vitesse de convergence d’une méthode d’échantillonnage à partir de son profil spectral. Cette boite à outils est notamment utilisée afin de classifier les méthodes d’échantillonnage existantes, mais aussi pour donner des indications sur les principes fondamentaux nécessaires à la conception de nouveaux algorithmes d’échantillonnage / Sampling is a key step in rendering pipeline. It allows the integration of light arriving to a point of the scene in order to calculate its color. Monte Carlo integration is generally the most used method to approximate that integral by choosing a finite number of samples. Reducing the bias and the variance of Monte Carlo integration has become one of the most important issues in realistic rendering. The solutions found are based on smartly positioning the samples points in a way that maximizes the uniformity of the distribution while avoiding the regularities. From this point of view, the 80s were a turning point in this domain, as new stochastic methods appeared. With a better comprehension of links between Monte Carlo integration and sampling, these methods allow the reduction of noise and of variance in rendered images. In parallel, the complexity of sampling methods has considerably enhanced, enabling to have fast as well as good quality methods. However, these improvements have been done by trial and error focusing on two major points : the improvement of sampling pattern uniformity, and the suppression of regularities. Even though there exists some theories allowing to bound the error of the integration, they are usually limited, and even inapplicable in computer graphics. This thesis proposes to gather the analysis tools of sampling patterns and to connect them together. These tools can characterize spatial properties such as the distribution of distances between points, as well as spectral properties via Fourier transformation. Secondly, we have used these tools in order to give a simple expression of the bias and the variance for Monte Carlo integration ; this is done by using prerequisites compatible with image rendering. Finally, we present a theoretical toolbox allowing to determine the convergence speed of a sampling method from its spectral profile. This toolbox is used specifically to give indications about the design principles necessary for new sampling algorithms

Context. Theoretical studies predict that the length scale of convection in stellar atmospheres isproportional to the pressure scale height, which implies that giant and supergiant stars should have convection granules of sizes comparable to their radii. Numerical simulations and the observation of anisotropies on stellar discs agree well with this prediction. Aims. To measure the characteristic sizes of convection structures of models simulated with the CO5BOLD code, to look at how they vary between models and to study their limitations due to numerical resolution. Methods. Fourier analyses are performed to frames from the models to achieve spatial spectral power distributions which are averaged over time. The position of the main peak and the averagevalue of the wavevector are taken as indicators of these sizes. The general shape of the intensity map of the disc in the frame is fitted and subtracted so that it does not contaminate the Fourier analysis. Results. A general relationship of the convection granule size being more or less ten times larger than the pressure length scale is found. The expected wavevector value of the time-averaged spectral power distributions is higher than the position of the main peak. Loose increasing trends with the characteristic sizes by the pressure scale height increasing against stellar mass, radius, luminosity,temperature and gravity are found, while a decreasing trends are found with the radius and modelresolution. Bad resolution subtracts signals on the slope at the side of the main peak towards larger wavevector values and in extreme cases it creates spurious signal towards the end of the spectrum due to artifacts appearing on the frames. Conclusions. The wavevector position of the absolute maximum in the time-averaged spectral power distribution is the best measure of the most prominent sizes in the stellar surfaces. The proportionality constant between granule size and pressure length scale is of the same order ofmagnitude as the one in the literature, however, models present sizes larger than the ones expected, likely because the of prominent features do not correspond to convection granules but to larger features hovering above them. Further studies on models with higher resolution will help in drawing more conclusive results. Appendix. The SIA pipeline takes a set of time-dependent pictures of stellar disks and uses a Fourier Analysis to measure the characteristic sizes of their features and other useful quantities, such as standard deviations or the spatial power distributions of features. The main core of the pipeline consists in identifying the stellar disc in the frames and subtracting their signal from the spatial power distributions through a general fit of the disc intensity. To analyze a time sequence, the SIA pipeline requires at least two commands from the user. The first commandorders the SIA pipeline to read the .sav IDL data structure file where the frame sequence is stored and to produce another .sav file with information on the spectral power distributions, the second command orders the reading of such file to produce two more .sav files, one containing time-averaged size measurements and their deviations while the other breaking down time-dependant information and other arrays used for the calculations. The SIA pipeline has been entirely written in Interactive Data Language (IDL). Most of the procedures used here are original from the SIA pipeline, but a small handfull like ima3_distancetransform.pro, power2d1d.pro, extremum.pro and smooth2d.pro from Bernd Freytag and peaks.pro and compile opt.pro amongst others are actually external. / <p>The report consists in two parts:</p><p>1.- The main project, where we apply our pipeline and get scientific results.</p><p>2.- The appendix, where a technical description of the pipeline is given.</p>

Operating system kernels rely on fine-grained concurrency to achieve optimal performance on modern multi-core processors. However, heavy usage of fine-grained concurrency mechanisms make modern operating system kernels prone to data races, which can cause severe and often elusive bugs. In this thesis, I propose a new approach to identifying data races in OS Kernels based on learning a model to predict which memory accesses can be feasibly executed concurrently with one another. To develop an efficient learning method for memory access feasibility, I develop a novel approach based on encoding feasibility as a boolean indicator function of system calls and ordered memory accesses. A memory access feasibility function encoded this way will have a naturally sparse latent representation due to the sparsity of interthread communications and synchronization interactions, and can therefore be accurately approximated based on a small number of observed concurrent execution traces. This thesis introduces two key contributions. First, Probabilistic Lockset Analysis (PLA), is a new analysis that exploits sparsity in input dependencies in conjunction with a conservative lockset analysis to efficiently predict data races in the Linux OS Kernel. Second, approximate happens-before analysis in the fourier domain (HBFourier) generalizes the approach used by PLA to reason about interthread memory communications and synchronization events through sparse fourier learning. In addition to being theoretically grounded, these techniques are highly practical: they find hundreds of races in a recent Linux development kernel, an order of magnitude improvement over prior work, and find races with severe security impacts that have been overlooked by existing kernel testing systems for years.

No / The differentiation between genuine and fake lapis lazuli specimens using Raman spectroscopy is assessed using laboratory and portable instrumentation operating at two longer wavelengths of excitation in the near-infrared, namely 1064 and 785 nm. In spite of the differences between the spectra excited here in the near infrared and those reported in the literature using visible excitation, it is clear that Raman spectroscopy at longer wavelengths can provide a means of differentiating between the fakes studied here and genuine lapis lazuli. The Raman spectra obtained from portable instrumentation can also achieve this result, which will be relevant for the verification of specimens which cannot be removed from collections and for the identification of genuine lapis lazuli inlays in, for example, complex jewellery and furniture. The non-destructive and non-contact character of the technique offers a special role for portable Raman spectroscopy in forensic art analysis.