Orientadores: Osvaldir Pereira Taranto, Virginia Aparecida Silva Moris / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T18:40:09Z (GMT). No. of bitstreams: 1 Lopes_NadiaElizaCorrea_M.pdf: 3103834 bytes, checksum: fb203b4d1396353b5e15847051d51028 (MD5) Previous issue date: 2007 / Resumo: O recobrimento de partículas em leito de jorro tem se mostrado bastante promissor, tendo em vista o seu potencial de aplicações em diversos produtos como comprimidos, cosméticos, sementes, fertilizantes. A maioria dos trabalhos reportados na literatura são baseados em observações visuais, em colunas construídas com material transparente, operados a pressão e temperatura ambiente. Porém, o reconhecimento visual dos regimes de escoamento não é possível em escala industrial ou com altas pressões. Logo, o objetivo desse trabalho foi identificar modificações ocorridas durante o processo de recobrimento de partículas em leito de jorro, pela comparação de observações visuais em conjunto com os espectros de potência obtidos a partir da aquisição de dados de queda de pressão em tempo real, utilizando a técnica FFT (Fast Fourier Transform). Para este estudo foram utilizadas partículas de diferentes formas, ABS e poliestireno, com diâmetro médio de 3,03 mm e 3,81 mm, respectivamente, e suspensão polimérica a base de Eudragitâ. O recobrimento foi realizado em um leito de jorro cone cilíndrico, confeccionado em acrílico com as seguintes dimensões: H = 70 cm, Dc = 14,3 cm, Di = 4 cm e ? = 60°, as condições operacionais foram pré-fixadas para cada partícula baseadas em ensaios preliminares. As flutuações da queda de pressão foram determinadas utilizando o software LabView 7.1, a uma taxa de amostragem de 400 Hz. Os resultados permitiram identificar durante o recobrimento a redução na taxa de circulação de partículas, zonas mortas e até ¿completo¿ colapso do leito, tanto por variações fluidodinâmicas visualmente observadas no leito, quanto por alteração espectral on line durante os experimentos de recobrimento. No futuro essa identificação pode ser útil como ferramenta no desenvolvimento de um sistema de controle ao processo de recobrimento / Abstract: The coating of particles in spouted has shown sufficiently promising, in view of its potential of applications in several products such as tablets, cosmetics, seeds, fertilizers. However, the works reported in literature had been predominantly based on visual observations, through columns constructed with transparent material, operated the pressure and ambient temperature. Furthermore, the visual recognition of flow regimes is not possible in industrial scale or with high pressures. Soon, the aim of this work was to identify modifications accured during the coating of particle in spouted bed, the comparison of the visual behavior with the power spectrum gotten from the acquisition of data of pressure drop in real time, using technique FFT (Fast Fourier Transform). For this study had been used particles of ABS and polystyrene, with average diameter of 3,03 mm and 3.81 mm, respectively, and aqueous polymeric suspension the base of Eudragitâ. The coating was carried through in a conical-cylindrical spouted bed, confectioned in acrylic with the following dimensions: H = 70 cm, Dc = 14,3 cm, Di = 4 cm and ? = 60°, the operational conditions had been fixed for each particle based in preliminary assays. The fluctuations of the drop pressure had been acquired using software LabView 7.1, to a rate of sampling of 400 Hz. The results had allowed to identify during the coating the reduction in the circulation rate of particle, zones deceased and until complete collapse of the spouted bed, as much for fluid-dynamics variations visually observed in the spouted bed, how much for spectral alteration during the coating experiments. In the future this identification can be useful development a control process tool / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Made available in DSpace on 2016-04-18T21:39:47Z (GMT). No. of bitstreams: 4 Daniela Mitie Kato1.pdf: 3074727 bytes, checksum: 838e46df28bd97be8c86b966efbdb36b (MD5) Daniela Mitie Kato2.pdf: 1644798 bytes, checksum: 9fab5a871347c336126e7f1eebb46dd2 (MD5) Daniela Mitie Kato3.pdf: 1390068 bytes, checksum: a71d113839f5bb7d740a9d8ddd7deda0 (MD5) Daniela Mitie Kato4.pdf: 3042893 bytes, checksum: 9c6b7834f6fd7ff78c42d7435ef034b7 (MD5) Previous issue date: 2008-06-26 / Fundo Mackenzie de Pesquisa / In this work, we investigate characteristics of the Power Spectral Density (PSD) of chaotic signals generated by one-dimensional maps. Usually, these signals are mentioned as having broadband and impulsive Autocorrelation Sequence (ACS). In this work, we verify that chaotic signals can be narrowband or broadband, with their power concentrated in the high or low frequencies. For a particular piecewise linear family of maps, we analytically evaluate the influence of the Lyapunov exponent on the ACS and on the PSD. We relate essential bandwidth to this exponent and to the parameter that defines a map in the family. We also consider the Manneville family of maps. In this case, the analysis is performed via computational simulations, interpreting the signals as sample-functions of a stochastic process. We relate the essential bandwidth to the Lyapunov exponent and to the family's parameter. We also relate this parameter to the return time of the intermittences. From the Telecommunication Engineering point of view, the results are relevant because they allow the emergence of new ideas for applications of chaotic signal in digital communication. / Neste trabalho investiga-se características da Densidade Espectral de Potência (DEP) de sinais caóticos gerados por mapas unidimensionais. Usualmente, refere-se aos sinais caóticos como sendo sinais banda larga e com Seqüência de Autocorrelação (SAC) na forma impulsiva. Verifica-se aqui que estes sinais podem ser banda estreita ou banda larga, com sua potência concentrada nas altas ou nas baixas freqüências. Para uma particular família de mapas lineares por partes, a influência do expoente de Lyapunov na SAC e na DEP é avaliada analiticamente. Relaciona-se a banda essencial dos sinais a este expoente e ao parâmetro que define um mapa da família. Considera-se também a família de mapas de Manneville, para a qual a análise é realizada por meio de simulações computacionais, interpretando os sinais gerados como funções-amostras de um processo estocástico. Relaciona-se a banda essencial ao expoente de Lyapunov e ao parâmetro da família e relaciona-se também este parâmetro ao tempo de retorno das intermitências. Do ponto de vista da Engenharia de Telecomunicações, os resultados obtidos são relevantes, pois possibilitam o surgimento de novas idéias de aplicações de sinais caóticos em sistemas de comunicação digital.

Esta dissertação apresenta o método de análise espectral de ondas superficiais (SASW) para a obtenção das variações do módulo cisalhante (Gmáx) com a profundidade, no domínio das deformações muito pequenas (abaixo de 0,001%). O SASW é um método sísmico in situ, não destrutivo, baseado na geração e detecção de ondas Rayleigh e na natureza dispersiva desta onda. Pela aplicação de um impacto na superfície do solo e detecção da onda em vários pontos, através de dois receptores, é construída uma curva de dispersão (velocidade de fase versus comprimento de onda). Esta curva de dispersão é, então, invertida. A inversão é um processo analítico para a reconstrução do perfil de velocidade de onda de cisalhamento (VS), partindo-se da curva de dispersão experimental de campo. O módulo de cisalhamento máximo de cada camada é facilmente obtido a partir do perfil de VS. No conteúdo teórico da dissertação discutem-se propriedades dinâmicas dos solos e descrevem-se as equações que dominam a propagação das ondas elásticas, tanto em meios homogêneos como em meios estratificados. A metodologia desenvolvida para a obtenção das curvas de dispersão, através da realização de ensaios SASW, apresenta os resultados obtidos em ensaios realizados na Cidade Universitária em São Paulo, sendo esses resultados comparados com estimativas feitas a partir de correlações baseadas em ensaios SPT existentes. Essas comparações permitem concluir que a metodologia SASW é uma boa alternativa para a determinação do perfil de rigidez (Gmáx) do solo, concordando com o nível de deformação envolvido nos ensaios. São desenvolvidos estudos de sensibilidade do método para verificar a influência na mudança dos parâmetros assumidos (peso específico, coeficiente de Poisson e espessuras das camadas) no processo de redução de dados (inversão) sobre o perfil final de VS, concluindo-se que o parâmetro que apresenta maior influência é o coeficiente de Poisson. / This dissertation presents the spectral-analysis-of-surface-waves (SASW) method as a tool for obtaining the variations in the modulus shear (Gmax) with depth in the field of very small strains (below 0,001%). The SASW method is a nondestructive in situ seismic method, based on the generation and measurement of Rayleigh wave and on its dispersive characteristic nature. Throughout the implementation of an impact on the soil surface and the detection of the wave at various points by two receptors a dispersion curve is constructed (phase velocity versus wave-length). This dispersion curve is then inverted. Inversion is an analytical process for reconstructing the shear wave velocity profile from the experimental field. The shear modulus of each layer is readily obtained from the shear wave velocity profile. The theoretical content of the dissertation presents dynamic properties of the soils and is described in the equations that dominate the propagation of elastic waves, both in homogeneous media and in stratified media. The methodology developed to obtain the dispersion curves through the implementation of SASW test is defined, and results from tests carried out at the University Campus in São Paulo are presented and compared with values obtained from correlations based on SPT tests. These comparisons indicate that the SASW method is a good alternative to determine the profile of stiffness (Gmax) of the soil, agreeing with the level of deformation involved in the tests. Studies on the methods sensitivity are developed to verify the influence on the changing of the parameters given (natural unit weight, Poisson coefficient and thickness of layers) in reduction of data (inversion) on the final profile of VS. The conclusion is that the Poisson coefficient is the parameter with greater influence.

Orientadores: Alexandre Campane Vidal, Emilson Pereira Leite / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-19T10:26:59Z (GMT). No. of bitstreams: 1 Honorio_BrunoCesarZanardo_M.pdf: 2919796 bytes, checksum: 69dad1cb91b548f053e48d33bcef6274 (MD5) Previous issue date: 2011 / Resumo: Perfis geofísicos de poços são importantes fontes de informação para o estudo de rochas em subsuperfície, sendo comumente utilizados na caracterização de reservatórios de petróleo. É sabido que os sinais obtidos como respostas do meio geológico contêm ruídos que podem afetar a interpretação do objeto estudado e que a transformada wavelet (WT) é melhor adaptada que a transformada de Fourier (FT) para a análise de sinais não-estacionários, como aqueles obtidos da perfilagem geofísica. Por outro lado, existem diversos parâmetros que devem ser considerados quando se trabalha com a WT, tais como a escolha da função wavelet base (wavelet mãe), o nível de decomposição, assim como a função e as regras que "controlam" como e quais coeficientes serão utilizados para reconstrução do sinal. Este estudo analisa o processo de atenuação de ruídos em perfis geofísicos de poços através da transformada wavelet ortogonal. Numa primeira abordagem, foi estudado o processo de atenuação em sinais sintéticos e então, foi estudado o processo em perfis geofísicos reais. Uma vez que os dados de perfis de poços são geralmente utilizados para a classificação de litologias, foi proposto um método associado com o algoritmo de classificação K-Vizinhos Mais Próximos (KNN) para investigar como as diferentes combinações dos parâmetros afetam os sinais de saída e o seu desempenho na classificação litológica, tornando assim um processo conduzido pelos dados. Foi investigada as funções de thresholding tradicionalmente empregadas (hard e soft threshold) bem como uma recente abordagem (customized threshold), sendo esta a que proporcionou melhores resultados. O potencial da transformada wavelet como ferramenta para auxiliar na interpretação geológica é evidenciado pela identificação de importantes características geológicas, como regiões de cimentação carbonática e a determinação de ciclos sedimentares, do Campo de Namorado, Bacia de Campos, Brasil / Abstract: Geophysical well logs are an important tool for the characterization of subsurface rocks, being commonly used in the study of reservoir geology. It is well known that signals obtained as responses from geological media contain noise that can affect their interpretation, and that wavelet transform (WT) is more suitable than the Fourier transform (FT) to denoise non-stationary signals, as the ones obtained from well logs. On the other hand, there are several parameters that must be considered when working with the WT, such as the wavelet basis function choice (mother wavelet), the decomposition level and also the function and rules that "control" which and how the coefficients will be used for signal reconstruction. This study analyzes the process of denoising geophysical well log data by orthogonal wavelet transform. In a first approach, it was studied the denoising process in synthetic signals and then, the process in real geophysical well logs. Since the well log data are usually used in lithology classification, we propose a method associated with the K-Nearest Neighbor (KNN) classification algorithm to investigate how different combinations of parameters affect the output signals and its performance in the lithological classification, thus making a data driven process. It was evaluated the thresholding function traditionally used (hard e soft threshold) as well a recent approach (customized threshold), this being the one that provided better results. The potential of the wavelet transform as a tool to aid geological interpretation is evidenced by the identification of important geological features, such as regions of carbonate cementation and determination of sedimentary cycles of the Namorado Field, Campos Basin, Brazil / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T03:26:02Z (GMT). No. of bitstreams: 1 Butzge_JoseJunior_M.pdf: 8667182 bytes, checksum: 5a5c900220efaa8c05f446d1c6942d84 (MD5) Previous issue date: 2012 / Resumo: A técnica do leito de jorro têm sido utilizada em diversos processos industriais e com maior ênfase nos setores químico, alimentício e farmacêutico, visto que apresenta como principais vantagens excelentes taxas de transferência de calor e massa. Contudo, tais características estão diretamente condicionadas à manutenção do regime de jorro estável, sendo, portanto, um ponto crítico de controle e objetivo operacional que deve ser satisfeito. Em geral, as condições operacionais executadas durante a secagem de pastas em leito de jorro produzem uma atmosfera interna com elevado conteúdo de umidade devido à aspersão de líquidos, promovendo notória dificuldade de operação e manutenção do regime fluidodinâmico desejado neste tipo de processo. Uma forma de superar os problemas efetivos associados à dificuldade de manutenção do regime de jorro estável é através da engenharia de controle e automação de processos. Dentro deste contexto e objetivando a manutenção do regime dinâmico estável durante o processo de umedecimento de inertes em leito de jorro, utilizou-se a metodologia de análise espectral dos sinais de flutuação de queda de pressão no leito para estudar o comportamento dos regimes fluidodinâmicos e implementar uma estratégia de monitoramento e controle do processo. Como partículas inertes foram utilizadas microesferas de vidro, enquanto o umedecimento do leito foi por meio de água destilada. Ensaios em leito seco em malha aberta permitiram identificar os regimes de jorro estável, jorro interno, leito fixo e o instante de transição entre os regimes a partir das variáveis monitoradas, frequência e amplitude espectral dominante e desvio padrão da flutuação de pressão. A frequência dominante demonstrou ser a variável mais adequada para monitorar e controlar o processo. Ensaios em leito úmido em malha aberta tiveram o intuito de avaliar o comportamento da frequência dominante durante condições de instabilidade e definir o setpoint range do controlador para o regime de jorro estável (7,8 a 8,4 Hz). A última etapa deste trabalho consistiu na implementação das malhas de controle. A utilização de controladores PI e PID permitiu desenvolver diferentes malhas de controle atuantes na vazão de ar de jorro e na vazão de atomização (variáveis manipuladas) a partir de uma única variável controlada (frequência espectral dominante). Os resultados demonstram que o regime dinâmico de jorro estável pode ser monitorado através da análise espectral dos sinais de flutuação de pressão, e controlado utilizando simplesmente controladores convencionais PID. A metodologia utilizada neste trabalho demonstra grande potencial de aplicação em processos de secagem de pastas reais, uma vez que a análise espectral das flutuações de pressão é baseada em medições simples, versáteis, robustas, em tempo real e de forma não intrusiva ao processo, enquanto que os controladores convencionais (PID) são de fácil aplicação e conseguiram neste trabalho, dentro das faixas estudadas, controlar o regime de jorro estável evitando instabilidades fluidodinâmicas / Abstract: The spouted bed dryers have been widely used in many industrial processes, especially in chemical, food and pharmaceutical industries, since its main advantages are high rates of heat and mass transfer. However, such characteristics are related on the maintenance of stable spout regime, therefore, beyond a critical control point and an operational objective that must be done. Usually, the moisture content during the drying of pastes in spouted bed is high due to the liquid atomization. Thus, the operational and maintenance of the desired fluid dynamic regime in this process is difficult. One way to overcome these problems is through the control engineering and process automation. In this context, and aiming to maintain the dynamic regime stable during the wetting in the spouted bed, we used the method of spectral analysis of pressure fluctuation signals for studying the behavior of fluid dynamic regimes and implement a strategy monitoring and control process. Glass beads were used as inert particles and distilled water was the atomize liquid. The open loop experiments in a dry bed allowed the identification of stable spout, internal spout and fixed bed and the moment of transition between the regimes from the monitored variables, dominant frequency, amplitude and standard deviation of pressure fluctuation. The dominant frequency was the most appropriate variable to monitor and control the process. The open loop experiments in a wet bed allowed to evaluate the behavior of the dominant frequency during unstable conditions and set the controller setpoint range for the system of stable spout (7.8 and 8.4 Hz). The last stage of this work consisted in the implementation of control loops, tuning controllers and closed loop tests. The use of PID controllers allowed the development of different control loops operating in the air flow rate and flow of pulp to be dried (manipulated variables) from a single controlled variable (spectral dominant frequency), demonstrating that stable dynamic regime can as well as monitored by spectral analysis of the pressure fluctuation signal to be maintained and controlled through the use of conventional controllers. The methodology used in this study demonstrates good potential for application for drying real slurries, because spectral fluctuations of the pressure measurement is based on simple, versatile, non-intrusive and with a real time, while conventional controllers (PID) are easy to apply and, in this work, controlled the stable spout regime in the range studied, avoiding fluid dynamics instabilities / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Many techniques have been developed to analyze time series. Spectral analysis and cycle regression analysis represent two such techniques. This study combines these two powerful tools to produce two new algorithms; the spectral algorithm and the one-pass algorithm. This research encompasses four objectives. The first objective is to link spectral analysis with cycle regression analysis to determine an initial estimate of the sinusoidal period. The second objective is to determine the best spectral window and truncation point combination to use with cycle regression for the initial estimate of the sinusoidal period. The third is to determine whether the new spectral algorithm performs better than the old T-value algorithm in estimating sinusoidal parameters. The fourth objective is to determine whether the one-pass algorithm can be used to estimate all significant harmonics simultaneously.

La fissure d'engrenages peut être considérée comme un défaut des plus compliqués à diagnostiquer car sa signature vibratoire n'est pas vraiment connue. En plus, l'intégration des fissures dans les modèles numériques n'est pas une tâche simple. D'autre part, le diagnostic des engrenages peut être fait dans le domaine temporel à travers des descripteurs statistiques ou dans le domaine fréquentiel grâce à l'analyse spectrale ou l'analyse cepstrale. Lors de l'apparition d'un défaut de fissure, des phénomènes non linéaires et non-stationnaires se manifestent ce qui rend les outils classiques de traitement du signal moins fiables. Dans ce manuscrit, nous répondons à toutes ces problématiques en développant un modèle d'engrenages à 6 DDL qui porte une fissure qui respire. Le modèle nous permet d'étudier la signature de la fissure et son effet sur les vibrations résultantes indépendamment de l'effet des autres composantes du système. Les résultats ont montré que la fissure conduit à une chute de la rigidité d'engrènement. En plus, la respiration de la fissure cause une fatigue dans le matériau ce qui engendre un terme aléatoire dans le signal vibratoire. La combinaison du terme aléatoire avec la composante périodique due à la rotation des arbres conduit à l'apparition de la cyclostationnarité d'ordre 2. Une étude comparative de sensibilité et de robustesse entre la transformée de Fourier rapide, la cyclostationnarité d'ordre 2 et les estimateurs de la phase instantanée (la transformée de Hilbert, estimation of signal parameters via rotational invariance techniques avec une fenêtre glissante, weighted least squares estimation et le scalogramme de phase) est effectuée pour la détection précoce des fissures. En plus, des essais expérimentaux ont été effectués sur un banc d'essais d'engrenages avec différentes dimensions de fissures. Les résultats théoriques et expérimentaux ont montré que l'analyse cyclostationnaire est la méthode la plus sensible et la plus robuste pour la détection précoce des fissures par rapport aux méthodes proposées. De plus, l'analyse de la phase instantanée donne également des résultats intéressants dans le cas des défauts de fissures. Nous avons montré que le scalogramme de phase est, a priori, plus performant que les autres approches / The gear crack is considered as the most complicated failure to diagnose because its vibration signature is not really known. In addition, the integration of crack defect in numerical models is not a simple task. On the other hand, gears diagnosis can be done in the time domain through statistical descriptors or in the frequency domain using spectral analysis or cepstral analysis. During the appearance of a crack defect, nonlinear and nonstationary phenomena occur which makes the classical tools of signal processing unreliable. In this manuscript, we respond to these challenges by developing a gear model of 6 DOF that has a crack that breathes. This allows us to study the signature of the defect in the resulting vibrations with a flexible way away from external vibrations. The results showed that the crack leads to a fall in the mesh stiffness. In addition, the opening and closing of the crack causes a fatigue in the material which generates a random term in the vibration signal. The combination of the random term with periodic component due to the rotation of the shafts leading to the appearance of second-order cyclostationary. A comparative study of sensitivity and robustness between the fast Fourier transform, second-order cyclostationary and estimators of instantaneous phase (the Hilbert transform, Estimation of Signal Parameters via Rotational Invariance Techniques with a sliding window, Weighted Least Squares Estimation and phase scalogramme) is performed for the early detection of cracks. In addition, experimental tests were carried out on a test-bench with different sizes of crack. The theoretical and experimental results showed that the cyclostationary analysis is the most sensitive and most robust method for the early detection of cracks in comparison with the other evaluated methods. Furthermore, the analysis of the instantaneous phase also gives good results in the case of crack defects. We have shown that the phase scalogramme is a priori more efficient than other approaches

On constate un regain d’intérêt pour l’étude des potentiels de champs extracellulaires (EFP). Trois principaux rôles fonctionnels des oscillations enregistrées dans le système nerveux ont été proposés : i) le codage d’informations spécifiques ii) la modulation des états attentionnels du cerveau, mais aussi iii) la création d’assemblées dynamiques. Je me suis intéressé aux EFP enregistrés dans les régions du néocortex, de l’hippocampe et de la VTA dans deux cadres expérimentaux dits “contrôlés” - afin de déceler des “motifs” oscillatoires spécifiques dans les mécanismes de mémorisations d’une situation stressante d’une part et dans les prises de décision sous incertitude d’autre part. Nous avons dans un premier temps enregistré et analysé l’activité dans les circuits dopaminergiques de la VTA, le PFC et l’OFC dans un paradigme permettant d’analyser le comportement de souris dans un cadre de prise de décision sous incertitude. Nous avons pu montrer dans un premier temps, que les circuits PFC, OFC et la VTA montrent des séquences d’activations et de synchronisations spécifiques selon le choix de l’individu, en condition incertaine. Dans un second temps, je me suis intéressé à mesurer, chez l’animal éveillé, les effets que pouvait engendrer une situation stressante sur le PFC et l’HPC en fonction de l’âge. Nos résultats mettent en évidence que les principaux effets mesurables aux niveaux des spectres de puissances s’expliquent par l’apparition d’activités électriques de fortes amplitudes dans la gamme (7-12 Hz), dont l’apparition varie en fonction de l’âge et du contexte (repos, stress). / Currently, there is a renewed interest in studying extracellular field potentials (EFP). This signal and the oscillations associated with it are the basis of many studies on the mechanisms underlying cognitive processes in cortical networks. Three key functional roles of oscillations recorded in the nervous system have been proposed: i) encoding specific information ii) modulation of attentional states of the brain, but also iii) creating dynamic assemblies. Although the interest for EFP continues to grow, the interpretation of these signals are sparse. During my prject I focused on the interpretation of EFP patterns under stress and uncertainty and specifically studied neocortex, hippocampus (HPC) and the ventral tegmental area (VTA) signals in these two experimental settings.Firstly, we recorded and analyzed the activity in the dopaminergic circuits including the VTA, PFC (prefrontal cortex) and OFC (orbitofrontal cortex) in a probabilistic decision-making paradigm for mice. We demonstrated that the PFC, OFC and VTA circuit shows specific time-dependent activation sequences depending on the anticipated choice per trial. Secondly, I was interested to measure, in awake animals, the effects caused by a stressful situation at different ages on the PFC and HPC signals. Our results demonstrate major effects at the level of the power spectral analysis. We identified that particularly high amplitudes in the range (7-12 Hz) vary according age and context (rest, stress).

Fibromyalgia syndrome (FMS) is a disorder characterised by chronic widespread pain, non-restorative sleep, fatigue and daytime dysfunction. Occurring in 2-5% of the population, the aetiology is largely unknown. Sleep dysfunction occurs in over 90% of FMS patients. While research has shown that both the macrostructure and microstructure of sleep may be altered, there remain inconsistencies in the polysomnographic (PSG) findings, and wide variations in methodological approaches. Few studies have controlled for symptom duration or the time elapsed between diagnosis and PSG sleep assessments. In addition, while psychometric analyses have suggested a distinctive FMS psychological profile (which includes higher levels of depressive symptoms, anxiety and fatigue) few studies have simultaneously, and thoroughly examined sleep and psychological status in the same participants. A frequently reported alteration found in the sleep microstructure of FMS patients is the alpha-delta sleep anomaly, characterised by an increase in alpha wave activity during slow wave sleep. Originally considered a possible neurological contribution to FMS, whether the alpha-delta sleep anomaly is fundamental to the development of fibromyalgia syndrome, or results mainly from the pain experience of FMS patients remains unknown. No previous study has directly compared the sleep of FMS and other (non-FMS) patients experiencing similar levels of chronic pain and sleep dysfunction. The present study was designed to examine sleep macrostructure and microstructure in FMS patients, and evaluate the role of the alpha-delta sleep anomaly as either a possible contributor to fibromyalgia syndrome, or a likely consequence of pain experience. In order to explore these relationships, detailed sleep, activity and psychological profiles were compared in 3 groups: 1) FMS patients (n = 19); 2) osteoarthritis patients with sleep disturbance (n = 17); and non-clinical (normal healthy) adults (n = 10). In order to standardise diagnostic reliability and symptom chronicity, the FMS group was recruited from a single rheumatology facility immediately following diagnosis. Guided by a series of formal research questions, analyses compared sleep macrostructure (using American Academy of Sleep Medicine criteria), sleep microstructure (using spectral analysis), and a range of psychological variables (including pain experience, sleepiness, fatigue, depression, anxiety, perceived social support, health locus of control, pain catastrophizing and personality). The results indicated that the alpha-delta sleep anomaly is not unique to FMS, but appears to be a feature found in the sleep of normal healthy adults and (to a greater extent) those with FMS and osteoarthritis. The incidence of the anomaly was statistically similar in both clinical (FMS and osteoarthritis) groups, a pattern consistent of its being a secondary feature of pain, rather than a primary abnormality of FMS. Overall, the psychometric assessments of state and trait anxiety and depression better discriminated between the three groups than did the sleep variables. Nevertheless, on measures of sleep, perceived social support, health locus of control, and pain catastrophizing, FMS and osteoarthritis patients were not significantly different, though both clinical groups differed on these variables from healthy controls.

A multilayered system is a good model for many optical systems. An optical coherence tomography (OCT) system can provide fundamental information about the refractive index distribution of the sample and enables images to be corrected for geometric accuracy, but this requires the separation of refractive index and physical thickness for each layer from the measured optical paths. In this thesis a novel approach for simultaneous extraction of index and thickness of multi layer systems and the last medium index of refraction in a single experiment using only the object’s spectral response available by any Fourier Domain OCT system without using any additional outside measurements is introduced. The method is based on a novel matrix equation that uses the reflected spectrum from the object and the measured optical thickness. In the presence of slight error of measuring optical thickness, the parameters extraction has wavenumber dependency. A novel method is used to select the suitable set of spectral components that reduces the extracted parameters error. The parameters extraction method is followed by a fitting process for optimized results. The method works the best for low contrast index distribution even in the presence of relatively large optical thickness measurement error.