Os supercondutores de alta temperatura crítica apresentam propriedades diferentes dos supercondutores convencionais, uma destas propriedades importantes é a simetria não isotrópica do parâmetro de ordem. Neste trabalho se apresenta um modelo que mostra a presença de simetria d-wave em uma classe de supercondutores de alta Tc, assim como a condição para a existência de ondas de densidade nos estados de equilíbrio. Se analisa primeiro um sistema de três corpos, um bipolaron e dois elétrons, com o objetivo de estudar o efeito da repulsão coulombiana local e não local sobre a simetria do parâmetro de ordem para o caso exato e também o limite de acoplamento forte. Se mostra também a construção de um Hamiltoniano efetivo que desacopla a interação el etron-bipolaron com o fim de abordar o problema coletivo de infinitos corpos e vemos como o modelo proposto prediz a formação de ondas de densidade para uma região especifica dos parâmetros físicos do Hamiltoniano estudado. / High-temperature superconductors have different properties than conventional superconductors, one of these important properties is non-isotropic symmetry of the order parameter. In this work we present a model that shows the presence of symmetry d-wave in a class of superconductors of high Tc , as well as the condition for the existence of density waves in the states of equilibrium. We first analyze a three-body system, a bipolaron and two electrons, in order to study the effect of local and non-local Coulomb repulsion on the symmetry of the order parameter for the exact case and also the strong coupling limit. It is also shown the construction of an effective Hamiltonian that decouples the electron-bipolaron interaction in order to approach the collective problem of infinite bodies and we see how the proposed model predicts the formation of density waves for a specific region of the physical parameters of the studied Hamiltonian.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The challenge for professional physicists, doctors and technicians and to identify the limits of acceptable image quality of the procedures to minimize the radiation dose to patients subjected. The definition of image quality should extend to matters of view of lesions to optimize the dose of radiation. (Kalra et al, 2004, p. 620). In this paper, the proposed optimization of the protocols provided by manufacturers of equipment for computed tomography (CT), give yourself to the reduction of transportable cargo (MAS) suggested by the manufacturers. The proposed new MAS, or optimized to be found by the intersection of two curves, which correlate dose levels and noise, plotted on the y axis, with the MAS, the x-axis Two devices were studied with computed tomography protocols optimized. Equipment has a single section (single slice) and the other multiple sections (multi-slice). The optimization was carried out in the protocols correspond to the skull by larger percentages of examinations. The quality of images of original and optimized protocols was analyzed quantitatively and qualitatively. Quantitatively, we analyzed the relation to noise (ASD), the High Spatial Resolution Contrast (HSRC), the spatial resolution of low contrast (SRLC) and Signal to Noise Ratio (SNR). From a qualitative (images) analyzed the noise (phantom water), the HSRC (phantom) and SRLC (phantom). Concurrently, we estimated the amount of heat generated in the X-ray tube. For the protocol 1∆ original, but 250 mAs, the CTDIVol, Exp was 33.19. For the protocol 1∆ optimized for 235 mAs, the CTDIVol, Exp was 31.37. 2∆ for the original protocol, but in 250, the CTDIVol, Exp was 33.96. For the protocol optimized for 235 mAs, the CTDIVol, Exp was 32.96. For the protocol 3∆ original, but 150, the CTDIVol, Exp was 18.28. For the protocol 3∆ optimized for 143 MAS, the CTDIVol, Exp was 16.63. For the protocol 4∆ original, but 150, the CTDIVol, Teo was 39.90. For the protocol optimized 4∆, 135 mAs, the CTDIVol, Exp was 28.29. For protocol 5∆ original, but 380, the CTDIVol, Exp was 40.97. For protocol 5∆ optimized for 367 mAs, the CTDIVol, Teo was 44.66. For protocol 6∆ original of 190 mAs, the CTDIVol, Exp was 20.04. For protocol 6∆ optimized for 178 mAs, the CTDIVol, Exp was 18.66. The protocols were already with low mAs, the technique used to find the optimal mAs provided noise levels that have not harmed the image quality, there was a natural increase in noise with decreasing mAs, however, that amount was found acceptable, as can be seen in the images obtained. / O desafio para os profissionais físicos, físicos médicos, médicos é técnicos em radiologia é identificar os limites aceitáveis de qualidade de imagem dos procedimentos de modo a minimizar a dose de radiação submetida aos pacientes. A definição da qualidade de imagem deve estender-se às questões de visualização das lesões para otimizar a dose da radiação (KALRA et al, 2004, p. 620). Neste trabalho, a proposta de otimização dos protocolos fornecidos pelos fabricantes de equipamentos de Tomografia Computadorizada (TC), dar-se-à pela redução das cargas transportáveis (mAs) sugeridas pelos fabricantes. Os novos mAs propostos, ou seja, otimizados, serão encontrados pela intersecção de duas curvas, que correlacionam níveis de dose (IDTCVol,Exp) e de ruído (MDP), plotados no eixo y, com o mAs, eixo x. Dois equipamentos de tomografia computadorizada foram estudados com os protocolos otimizados. Um dos equipamentos possui secção única (single slice) e o outro múltiplas secções (multi slice). A otimização foi realizada nos protocolos crânio por corresponderem aos maiores porcentuais de exames. A qualidade das imagens dos protocolos originais e otimizados foi analisada de forma quantitativa e qualitativa. De forma quantitativa analisou-se, a relação ao ruído (MDP), a Resolução Espacial de Alto Contraste (REAC), a Resolução Espacial de Baixo Contraste (REBC) e a Relação Sinal Ruído (RSR). De forma qualitativa (imagens) analisou-se o ruído (phantom com água), a REAC (phantom) e a REBC (phantom). Concomitantemente, foi estimada a quantidade de calor gerado no tubo de raios X. Para o protocolo 1∆ original, mAs de 250, o IDTCvol,Exp foi de 33,19. Para o protocolo 1∆ otimizado, mAs de 235, o IDTCvol,Exp foi de 31,37. Para o protocolo 2∆ original, mAs de 250, o IDTCvol,Exp foi de 33,96. Para o protocolo otimizado, mAs de 235, o IDTCvol,Exp foi de 32,96. Para o protocolo 3∆ original, mAs de 150, o IDTCvol,Exp foi de 18,28, Para o protocolo 3∆ otimizado, mAs de 143, o IDTCvol,Exp foi de 16,63. Para o protocolo 4∆ original, mAs de 150, o IDTCvol,Exp foi de 39,48. Para o protocolo 4∆ otimizado, mAs de 135, o IDTCvol,Exp foi de 28,29. Para o protocolo 5∆ original, mAs de 380, o IDTCvol,Exp foi de 40,97. Para o protocolo 5∆ otimizado, mAs de 367, o IDTCvol,Exp foi de 38,57. Para o protocolo 6∆ original, mAs de 190, o IDTCvol,Exp foi de 20,04. Para o protocolo 6∆ otimizado, mAs de 178, o IDTCvol,Exp foi de 18,66. Os protocolos já encontravam-se com valores baixos de mAs, a técnica utilizada para encontrar o mAs otimizado forneceu valores de ruído que não prejudicaram a qualidade da imagem, houve um aumento natural do ruído com a diminuição do mAs, porém, essa quantidade encontrada foi aceitável, como pode ser visualizado pelas imagens obtidas.

Os supercondutores de alta temperatura crítica apresentam propriedades diferentes dos supercondutores convencionais, uma destas propriedades importantes é a simetria não isotrópica do parâmetro de ordem. Neste trabalho se apresenta um modelo que mostra a presença de simetria d-wave em uma classe de supercondutores de alta Tc, assim como a condição para a existência de ondas de densidade nos estados de equilíbrio. Se analisa primeiro um sistema de três corpos, um bipolaron e dois elétrons, com o objetivo de estudar o efeito da repulsão coulombiana local e não local sobre a simetria do parâmetro de ordem para o caso exato e também o limite de acoplamento forte. Se mostra também a construção de um Hamiltoniano efetivo que desacopla a interação el etron-bipolaron com o fim de abordar o problema coletivo de infinitos corpos e vemos como o modelo proposto prediz a formação de ondas de densidade para uma região especifica dos parâmetros físicos do Hamiltoniano estudado. / High-temperature superconductors have different properties than conventional superconductors, one of these important properties is non-isotropic symmetry of the order parameter. In this work we present a model that shows the presence of symmetry d-wave in a class of superconductors of high Tc , as well as the condition for the existence of density waves in the states of equilibrium. We first analyze a three-body system, a bipolaron and two electrons, in order to study the effect of local and non-local Coulomb repulsion on the symmetry of the order parameter for the exact case and also the strong coupling limit. It is also shown the construction of an effective Hamiltonian that decouples the electron-bipolaron interaction in order to approach the collective problem of infinite bodies and we see how the proposed model predicts the formation of density waves for a specific region of the physical parameters of the studied Hamiltonian.

The thesis deals with dynamic bandwidth allocation in passive optical networks of NG- PON2 standard. The paper also describes the so-called. triple play services and the practical part is a simulation of these services in passive optical networks NG-PON2 in the simulation environment OMNeT ++. As part of this work modules for passive optical network NG-PON2 were created as an expansion of project INET. Namely ONU, OLT and splitter modules were created. The first four chapters are theoretical and descibe older standards PON networks, further NG-PON2 networks and DBA algorithm then describes triple play services and explains their current status respectively. In another part a description of the programm OMNeT++ a description of the structure of simulation models. The practical part contains a description of modules, implementation of DBA algorithm and its modification, design simulated topology and detailed description of the configuration simulation. At the end of the practical part presents the results of simulations with the corresponding explanations.

National efforts to reduce energy dependency on fossil fuels have prompted examination of macrotidal nearshore zones around the UK for potential tidal stream resource development. Although a number of prospective tidal energy sites have been identified, the local hydrodynamics of these sites are often poorly understood. Tidal-energy developers rely on detailed characterisation of tidal energy sites prior to device field trials and installation. Although first-order appraisals may make macrotidal tidal straits appear attractive for development, detailed, site-specific hydrodynamic and bathymetric surveys are important for determining site suitability for tidal stream turbine (TST) installation. Understanding the ways in which coastal features affect tidal velocities at potential TST development sites will improve identification and analysis of physical constraints on tidal-energy development. Ramsey Sound (Pembrokeshire, Wales, UK) will soon host Wales’ first TST demonstration project. However, the local hydrodynamics of the sound have been underexamined. Ramsey Sound experiences a marked tidal asymmetry, with local bathymetric features that affect flow fields which are spatially heterogeneous in three dimensions. Using Ramsey Sound as a case study, this thesis has three objectives: (1) to examine the wake created by submerged objects through field- and laboratory-based measurements, (2) to experimentally investigate the effect of submergence on wake development and decay downstream of a conical island, and (3) to develop a TST suitability tool, which examines the effects of velocity, water depth and bed slope on power availability within a macrotidal coastal area. Laboratory experiments have shown that submergence level is an important parameter controlling wake structure and extent, and that changes in submergence level affect both the 3-D flow structure in the near wake and the 2-D far wake of islands. Analysis of physical and hydrodynamic characteristics in Ramsey Sound, including tidal velocities across the swept area of the pilot TST, vertical shear in the stream flow, estimated power output, water depth and bed slope, suggests that the spatial and temporal variability in the flow field may render much of Ramsey Sound unsuitable for tidal power extraction. Although the resource potential depends on velocity and bathymetric conditions that are fundamentally local, many prospective tidal energy sites are subject to similar physical and hydrodynamic constraints. Results of this study can help inform site selection in these complicated, highly dynamic macrotidal environments.

Cette recherche se propose d'examiner l'évolution des symptômes d'un trouble déficitaire de l'attention/hyperactivité (TDAH), d'un trouble des conduites (TC) et d'un trouble de l'opposition avec provocation (TOP) de l'élève selon l'accord ou le désaccord entre les parents et les enseignants. Elle a aussi comme objectif de déterminer les répercussions d'un consensus inter-informateurs sur la fréquence et la satisfaction des services scolaires. L'échantillon est constitué de 341 élèves québécois âgés de 5 ans 7 mois à 13 ans 5 mois recevant des services d'aide spécialisés. Les parents et le personnel enseignant ont complété le DISC-2.25 . Les résultats posent que l'entente entre informateurs est spécifiquement associée aux deux variables retard scolaire et dépression des parents. L'accord entre informateurs est bénéfique à la trajectoire des enfants 24 mois plus tard surtout dans le cas des symptômes d'un TC et dans une moindre mesure de ceux d'un TOP. La fréquence des services augmente sensiblement pour les enfants avec des symptômes d'un TC lorsqu'il y a une reconnaissance mutuelle de ce trouble par les parents et les enseignants. Pour aucun des trois troubles, le niveau de satisfaction des parents de l'aide reçue n'est influencé par la présence d'une entente entre informateurs. La fréquence des services spécialisés reçus par l'enfant ne spécifie rien des mécanismes par lesquels le consensus entre informateurs influe positivement l'évolution des élèves 24 mois plus tard. Ce travail se termine par un questionnement sur les différences dans l'évaluation des troubles de comportement des élèves entre la France et le Québec et apporte plusieurs contributions pour la pratique, spécifiquement l'évaluation et l'intervention.

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Meshless Local Petrov-Galerkin method based on Rankine source solution (MLPG_R) has been developed by Dr. Qingwei Ma (Ma, 2005b) and has been used to simulate the nonlinear water wave problems in 2D cases without the occurrence of the breaking waves. In this thesis, MLPG_R method has been further developed to numerically simulate breaking waves and the interactions between breaking waves and structures in 2D and 3D cases. The main difference between this meshless method and conventional mesh-based methods is that the governing equations are solved in terms of particle interaction models, without the need of computational meshes. Therefore, this method avoids the time-consuming mesh generating and updating procedures which may be necessary and may need to be frequently performed in the mesh-based methods. Furthermore, in order to simulate the breaking waves well, several novel numerical techniques are developed and adopted. The numerical technique for implementing the solid boundary condition for meshless methods is proposed, which is more robust than others in terms of accuracy and efficiency. A technique for meshless interpolation (SFDI scheme) is adopted, which is as accurate as the more costly moving least square (MLS) method generally but requires much less computational time than the latter. A newly developed technique for identifying the free surface particles is presented, which is much more robust than those existing in literature. A semi-analytical method for numerical evaluation of integrals in a local domain and on its surface is presented to form the matrix for the algebraic equations, which makes it possible to modelling the 3D problems on personal computers. The newly extended MLPG_R method is applied to simulate the waves generated by a wave maker and their propagations, overturning and breaking over flat and sloped seabed. And it is also applied to 2D and 3D dam breaking cases and violent sloshing cases. The convergence properties of this method in different cases are investigated. Some of the results have been validated by experimental data and numerical results obtained by other methods. Satisfactory agreements are achieved. Based on these numerical investigations, a number of conclusions have been made, including that the breaking waves can cause large pressure with several peaks when they impact on structures; the behaviour of pressure strongly depends on the relative locations of structures to the breaking point of breaking waves. Breaking waves in a sloshing container can also cause more than one peaks, which is correlated with the direction change of water motion within the container. These investigations can give us better understanding of the impact pressure, breaking wave and interactions between breaking wave and structures.