Em muitos problemas de simulação de fenômenos físicos ou fenômenos de engenharia, o uso das malhas é um componente muito importante. Uma malha é uma aproximação de uma dada geometria por um conjunto de elementos mais simples, tais como triângulos e quadriláteros (caso bidimensional) ou tetraedros, prismas, pirâmides e hexaedros (caso tridimensional). Nesse texto, as malhas de interesse são as não-estruturadas e compostas por triângulos. A escolha de uma malha é fortemente influenciada pelo desempenho e precisão dos resultados da simulação. O desempenho depende do número de elementos a serem processados, ou seja, quanto maior for a área coberta por cada elemento da malha, menos elementos são necessários, por conseguinte, mais rápida será a simulaçao. A precisão nos resultados da simulação está relacionada tanto com o formato quanto com o tamanho dos elementos. Diferente do desempenho, quanto menor forem os elementos, mais precisos serão os resultados. O formato dos elementos também influencia a precisão, em geral, elementos mais próximos dos equiláteros são preferidos. Como é possível observar, desempenho e precisão são requisitos conflitantes e geralmente é necessário fazer uma ponderação entre eles. Para um determinado grupo de aplicações, o melhor compromisso entre desempenho e precisão é conseguido com elementos finos, longos e corretamente alinhados sobre o domí?nio onde a malha está definida. São as chamadas malhas anisotrópicas. Além disso, um método de refinamento anisotrópico pode melhorar ainda mais a precisão dos resultados. O principal objetivo desse trabalho é desenvolver métodos de refinamento de malhas anisotrópicas, usando como base, e tendo como ponto de partida, os métodos de refinamento Delaunay isotrópicos, a saber, os métodos de refinamento Delaunay de Jim Ruppert [13] e de Paul Chew [6], e também realizar a simplificação Delaunay proposto por Olivier Devillers [8] / The use of polygonal meshes for numerical simulation of physical problems is a well known component. Mesh is an piecewise approximation from a given geometry defined by a set of simpler elements, such as triangles and quadrilaterals (two-dimensional case) or tetrahedra, prisms, pyramid and hexahedra (three-dimensional case). In this work, the interest is unstructured meshes of triangles. The choice of a mesh is aimed at the performance and the precision of the simulation results. The performance depends of the number of elements that will be processed, i.e., the larger is the covered area for each mesh element, the less element is needed, therefore the simulation is faster performed. The simulation precision is related with the shape and the size of the elements. On the other hand, the smaller the elements are, the more precise are the results. The shape of the elements also influences on precision, generally, equilateral elements are preferred. It is worth to mention that performance and precision are opposite requirements and it is important to ponder between them. For a group of applications, the best commitment between performance and precision is obtained with thin and long elements correctly aligned on the domain where the mesh is defined. These meshes are named anisotropic meshes. Furthermore, a method of anisotropic refinement can even improve the precision. We aim at developing anisotropic mesh methods based on isotropic properties from well known Delaunay refinement methods, viz., the Delaynay refinement methods by Jim Ruppert [13] and Paul Chew [6], and performing a Delaunay simplification proposed by Olivier Devillers [8]

Em muitos problemas de simulação de fenômenos físicos ou fenômenos de engenharia, o uso das malhas é um componente muito importante. Uma malha é uma aproximação de uma dada geometria por um conjunto de elementos mais simples, tais como triângulos e quadriláteros (caso bidimensional) ou tetraedros, prismas, pirâmides e hexaedros (caso tridimensional). Nesse texto, as malhas de interesse são as não-estruturadas e compostas por triângulos. A escolha de uma malha é fortemente influenciada pelo desempenho e precisão dos resultados da simulação. O desempenho depende do número de elementos a serem processados, ou seja, quanto maior for a área coberta por cada elemento da malha, menos elementos são necessários, por conseguinte, mais rápida será a simulaçao. A precisão nos resultados da simulação está relacionada tanto com o formato quanto com o tamanho dos elementos. Diferente do desempenho, quanto menor forem os elementos, mais precisos serão os resultados. O formato dos elementos também influencia a precisão, em geral, elementos mais próximos dos equiláteros são preferidos. Como é possível observar, desempenho e precisão são requisitos conflitantes e geralmente é necessário fazer uma ponderação entre eles. Para um determinado grupo de aplicações, o melhor compromisso entre desempenho e precisão é conseguido com elementos finos, longos e corretamente alinhados sobre o domí?nio onde a malha está definida. São as chamadas malhas anisotrópicas. Além disso, um método de refinamento anisotrópico pode melhorar ainda mais a precisão dos resultados. O principal objetivo desse trabalho é desenvolver métodos de refinamento de malhas anisotrópicas, usando como base, e tendo como ponto de partida, os métodos de refinamento Delaunay isotrópicos, a saber, os métodos de refinamento Delaunay de Jim Ruppert [13] e de Paul Chew [6], e também realizar a simplificação Delaunay proposto por Olivier Devillers [8] / The use of polygonal meshes for numerical simulation of physical problems is a well known component. Mesh is an piecewise approximation from a given geometry defined by a set of simpler elements, such as triangles and quadrilaterals (two-dimensional case) or tetrahedra, prisms, pyramid and hexahedra (three-dimensional case). In this work, the interest is unstructured meshes of triangles. The choice of a mesh is aimed at the performance and the precision of the simulation results. The performance depends of the number of elements that will be processed, i.e., the larger is the covered area for each mesh element, the less element is needed, therefore the simulation is faster performed. The simulation precision is related with the shape and the size of the elements. On the other hand, the smaller the elements are, the more precise are the results. The shape of the elements also influences on precision, generally, equilateral elements are preferred. It is worth to mention that performance and precision are opposite requirements and it is important to ponder between them. For a group of applications, the best commitment between performance and precision is obtained with thin and long elements correctly aligned on the domain where the mesh is defined. These meshes are named anisotropic meshes. Furthermore, a method of anisotropic refinement can even improve the precision. We aim at developing anisotropic mesh methods based on isotropic properties from well known Delaunay refinement methods, viz., the Delaynay refinement methods by Jim Ruppert [13] and Paul Chew [6], and performing a Delaunay simplification proposed by Olivier Devillers [8]

Parallel manipulators have been the subject of study of much robotic research during the past three decades. A parallel manipulator typically consists of a moving platform that is connected to a fixed base by at least two kinematic chains in parallel. Parallel manipulators can provide several attractive advantages over their serial counterpart in terms of high stiffness, high accuracy, and low inertia, which enable them to become viable alternatives for wide applications. But parallel manipulators also have some disadvantages, such as complex forward kinematics, small workspace, complicated structures, and a high cost. To overcome the above shortcomings, progress on the development of parallel manipulators with less than 6-DOF has been accelerated. However, most of presented parallel manipulators have coupled motion between the position and orientation of the end-effector. Therefore, the kinematic model is complex and the manipulator is difficult to control. Only recently, research on parallel manipulators with less than six degrees of freedom has been leaning toward the decoupling of the position and orientation of the end-effector, and this has really interested scientists in the area of parallel robotics. Kinematic decoupling for a parallel manipulator is that one motion of the up-platform only corresponds to input of one leg or one group of legs. And the input cannot produce other motions. Nevertheless, to date, the number of real applications of decoupled motion actuated parallel manipulators is still quite limited. This is partially because effective development strategies of such types of closed-loop structures are not so obvious. In addition, it is very difficult to design mechanisms with complete decoupling, but it is possible for fewer DOF parallel manipulators. To realize kinematic decoupling, the parallel manipulators are needed to possess special structures; therefore, investigating a parallel manipulator with decoupling motion remains a challenging task. This thesis deals with lower mobility parallel manipulator with decoupled motions. A novel parallel manipulator is proposed in this thesis. The manipulator consists of a moving platform that is connecting to a fixed base by three legs. Each leg is made of one C (cylinder), one R (revolute) and one U (universal) joints. The mobility of the manipulator and structure of the inactive joint are analyzed. Kinematics of the manipulator including inverse and forward kinematics, velocity equation, kinematic singularities, and stiffness are studied. The workspace of the parallel manipulator is examined. A design optimization is conducted with the prescribed workspace. It has been found that due to the special arrangement of the legs and joints, this parallel manipulator performs three translational degrees of freedom with decoupled motions, and is fully isotropic. This advantage has great potential for machine tools and Coordinate Measuring Machine (CMM). / UOIT

In this preprint, we look onto the theory of linear thermoelasticity. At the beginning, this theory is shortly repeated and afterwards applied to transversely isotropic materials. Then, the corresponding weak formulation is derived, which is the starting point for a FE-discretisation. In the last part, we explain how we added this material behaviour to an adaptive Finite-Element-code and show some numerical results.

Geodesy deals with the accurate analysis of spatial and temporal variations in the geometry and physics of the Earth at local and global scales. In geodesy, least-squares collocation (LSC) is a bridge between the physical and statistical understanding of different functionals of the gravitational field of the Earth. This thesis specifically focuses on the [incorrect] implicit LSC assumptions of isotropy and homogeneity that create limitations on the application of LSC in non-stationary gravity field modeling. In particular, the work seeks to derive expressions for local and global analytical covariance functions that account for the anisotropy and heterogeneity of the Earth's gravity field. / Standard LSC assumes 2D stationarity and 3D isotropy, and relies on a covariance function to account for spatial dependence in the observed data. However, the assumption that the spatial dependence is constant throughout the region of interest may sometimes be violated. Assuming a stationary covariance structure can result in over-smoothing, e.g., of the gravity field in mountains and under-smoothing in great plains. The kernel convolution method from spatial statistics is introduced for non-stationary covariance structures, and its advantage in dealing with non-stationarity in geodetic data is demonstrated. / Tests of the new non-stationary solutions were performed over the Darling Fault, Western Australia, where the anomalous gravity field is anisotropic and non-stationary. Stationary and non-stationary covariance functions are compared in 2D LSC to the empirical example of gravity anomaly interpolation. The results with non-stationary covariance functions are better than standard LSC in terms of formal errors and cross-validation. Both non-stationarity of mean and covariance are considered in planar geoid determination by LSC to test how differently non-stationarity of mean and covariance affects the LSC result compared with GPS-levelling points in this area. Non-stationarity of the mean was not very considerable in this case, but non-stationary covariances were very effective when optimising the gravimetric quasigeoid to agree with the geometric quasigeoid. / In addition, the importance of the choice of the parameters of the non-stationary covariance functions within a Bayesian framework and the improvement of the new method for different functionals on the globe are pointed out.

Mild traumatic brain injury (mTBI) is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion) and anisotropic fashion (i.e., quantitative anisotropy, QA) for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition) impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo) on the amount of water diffusion (QA) for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

No description available.

O solo é base de praticamente todas as obras de Engenharia Civil e em algumas situações este não apresenta condições de suportar o carregamento imposto. Tal problema pode ser solucionado com técnicas de estabilização. A estabilização com cal é uma técnica clássica, porém não apresenta um método racional de dosagem e uma superfície de falha tridimensional conhecida. Entretanto este quadro vem alterando-se por meio de pesquisas que buscam utilizar o coeficiente porosidade/teor volumétrico de cal para dosar solo-cal. Assim, esta pesquisa tem como objetivo avaliar a influencia do coeficiente n/(Liv) na variação de resistência à tração na compressão diametral de misturas solo- cinza volante-cal para diferentes temperaturas e diferentes tempos de cura. Busca-se obter, também, a envoltória de ruptura tridimensional deste material. Para isso foram realizados ensaios de tração por compressão diametral em corpos de prova da mistura areia de Osório e cinza volante com 3, 5 e 7 % de cal (em peso), com peso especifico aparente seco de 14, 15 e 16 kN/m², curados a 20, 27, 35, 50, 65,80 e 90ºC por 1, 3 e 7 dias. Ensaios em Triaxial Verdadeiro e de ondas ultrassônicas foram executadas em amostras com 3 dias de cura a 35º, 3% de cal, peso específico seco de 14kN/m³ e nvariando de 0 até 180º. A relação porosidade/teor volumétrico de cal ajustado por um coeficiente [n/(Liv)0,3] mostrou-se adequada na previsão da resistência à tração para todas as temperaturas e tempos de cura estudados. O uso deste coeficiente permitiu a obtenção de curvas que permitem o cálculo da temperatura máxima que influência na resistência da mistura estudada para cada tempo de tempo. Este coeficiente também permitiu a obtenção de uma equação capaz de determinar a resistência máxima que pode ser obtida em cada tempo de cura independente da temperatura de cura. A envoltória de ruptura encontrada tem formato não circular, logo a resistência do material é dependente do caminho de tensões. A isotropia do material foi confirmada através da comparação entre caminhos de tensão iguais, porém executados em diferentes direções e através da comparação entre o Módulo Oedométrico há pequenas deformações (M0)e o Módulo de Cisalhamento há pequenas deformações (G0) das direções x, y e z da amostra. / Soil is the base of most civil engineering constructions, and when it cannot support the construction loads, such problem can be solved through the use of soil stabilization technique. Lime stabilization is a classical technique, but does not present a rational dosage method and a known three-dimensional failure envelope. This situation has been changed with researches using the porosity/lime ratio to dose soil-lime. Thereby this research aims to evaluate the influence of the quotient n/(Liv) in the assessment of splitting tensile at different temperatures and time of curing and find. It was also looked for the three dimensional rupture envelope of this material. For this research splitting tensile tests were carried out with lime contents varying from 3% to 7%, dry unit weight ranging from 14kN/m³ to 16kN/m³, time curing varying from 1 to 7 days and curing time varying from 20º to 90º. True Triaxial tests and ultrasonic waves tests were carried out with samples with 3% of lime content, 14kN/m³ of dry weight, 3 days of curing at 35º and nangle between nz and the consider stress path) in ranging from 0º to 180º. The porosity/lime ratio, defined as the ratio of the compacted mixture porosity and the lime volumetric content, adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-fly ash-lime studied in all time and temperature studied. The use of this coefficient allowed obtaining curves that allow the calculation of the maximum temperature that influences the resistance of the studied mixture for each time period. This coefficient also allowed obtaining an equation capable of determining the maximum resistance that can be reached in each curing time independent of curing temperature. The failure envelope found has a non-circular shape, so the strength of the material is dependent on the stress path. The isotropy of the material was confirmed by comparing equal stress paths, but executed in different directions and by comparing the Oedometric Modulus in small strains (M0 ) and Shear Modulus in small strains (G0 ) of the x, y, and z directions the sample.

För att kunna förbättra processer och användning av det duplexa rostfria stålet SAF 2507 måste dess deformationsegenskaper undersökas och förklaras. Genom EBSD-analyser har deformationsstrukturer och polfgurer tagits fram för att kunna beskriva materialets beteende vid deformation. Även Taylorfaktorer, E-moduler och Poissons tal har tagits fram för att kunna undersöka materialets anisotropi. Experimenten har utförts på prov av SAF 2507 som har deformerats plastiskt till olika töjningar. Det som undersökts är odeformerat prov, prov som dragits enaxligt till 7,7 % och 24,3 % töjning, samt ett prov som är cykliskt belastat till 3 % töjning. Det undersökta stålet tillverkas genom två olika metoder, men i denna rapport har enbart det extruderade stålet undersökts. Genom att jämföra hur stålets olika mekaniska egenskaper beter sig under plastisk deformation har resultatet blivit att stålets ferritfas beter sig anisotropt med en antydan till ökande isotropi vid ökande deformation. Austenitfasen beter sig däremot isotropt och blir varken mer eller mindre isotropt vid ökande deformation. Substrukturerna i ferritfasen ökar tydligt vid ökande deformation, och ses framför allt i austenitfasen efter 24 % deformation. / In order to improve the processes and the use of the duplex stainless steel SAF 2507, its deformation properties has to be investigated and explained. Through EBSD-analysis deformation structures and pole figures have been developed to describe the behavior of the material during deformation. Also Taylor factors, Young’s modules and Poisson's ratio have been developed in order to investigate the material's anisotropy. The experiments have been performed on samples of SAF 2507 which has been plastically deformed at different strains. The strains studied are undeformed sample, samples drawn uniaxial drawn to 7.7 % and 24.3 % elongation, and one sample which is cyclically loaded to 3% elongation. The steel we have investigated is produced by two different methods, but in this report, only the extruded steel is investigated. By comparing how different mechanical properties of the steel behave during plastic deformation, the result shows that the steel’s ferrite phase behaves anisotropically with a hint of increasing isotropy when the deformation is increasing. The austenite phase behaves isotropic and does not become more or less isotropic with increasing deformation. The substructures in the ferrite phase are clearly increasing with increasing deformation, and are seen mainly in the austenite phase after 24 % deformation.

O solo é base de praticamente todas as obras de Engenharia Civil e em algumas situações este não apresenta condições de suportar o carregamento imposto. Tal problema pode ser solucionado com técnicas de estabilização. A estabilização com cal é uma técnica clássica, porém não apresenta um método racional de dosagem e uma superfície de falha tridimensional conhecida. Entretanto este quadro vem alterando-se por meio de pesquisas que buscam utilizar o coeficiente porosidade/teor volumétrico de cal para dosar solo-cal. Assim, esta pesquisa tem como objetivo avaliar a influencia do coeficiente n/(Liv) na variação de resistência à tração na compressão diametral de misturas solo- cinza volante-cal para diferentes temperaturas e diferentes tempos de cura. Busca-se obter, também, a envoltória de ruptura tridimensional deste material. Para isso foram realizados ensaios de tração por compressão diametral em corpos de prova da mistura areia de Osório e cinza volante com 3, 5 e 7 % de cal (em peso), com peso especifico aparente seco de 14, 15 e 16 kN/m², curados a 20, 27, 35, 50, 65,80 e 90ºC por 1, 3 e 7 dias. Ensaios em Triaxial Verdadeiro e de ondas ultrassônicas foram executadas em amostras com 3 dias de cura a 35º, 3% de cal, peso específico seco de 14kN/m³ e nvariando de 0 até 180º. A relação porosidade/teor volumétrico de cal ajustado por um coeficiente [n/(Liv)0,3] mostrou-se adequada na previsão da resistência à tração para todas as temperaturas e tempos de cura estudados. O uso deste coeficiente permitiu a obtenção de curvas que permitem o cálculo da temperatura máxima que influência na resistência da mistura estudada para cada tempo de tempo. Este coeficiente também permitiu a obtenção de uma equação capaz de determinar a resistência máxima que pode ser obtida em cada tempo de cura independente da temperatura de cura. A envoltória de ruptura encontrada tem formato não circular, logo a resistência do material é dependente do caminho de tensões. A isotropia do material foi confirmada através da comparação entre caminhos de tensão iguais, porém executados em diferentes direções e através da comparação entre o Módulo Oedométrico há pequenas deformações (M0)e o Módulo de Cisalhamento há pequenas deformações (G0) das direções x, y e z da amostra. / Soil is the base of most civil engineering constructions, and when it cannot support the construction loads, such problem can be solved through the use of soil stabilization technique. Lime stabilization is a classical technique, but does not present a rational dosage method and a known three-dimensional failure envelope. This situation has been changed with researches using the porosity/lime ratio to dose soil-lime. Thereby this research aims to evaluate the influence of the quotient n/(Liv) in the assessment of splitting tensile at different temperatures and time of curing and find. It was also looked for the three dimensional rupture envelope of this material. For this research splitting tensile tests were carried out with lime contents varying from 3% to 7%, dry unit weight ranging from 14kN/m³ to 16kN/m³, time curing varying from 1 to 7 days and curing time varying from 20º to 90º. True Triaxial tests and ultrasonic waves tests were carried out with samples with 3% of lime content, 14kN/m³ of dry weight, 3 days of curing at 35º and nangle between nz and the consider stress path) in ranging from 0º to 180º. The porosity/lime ratio, defined as the ratio of the compacted mixture porosity and the lime volumetric content, adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-fly ash-lime studied in all time and temperature studied. The use of this coefficient allowed obtaining curves that allow the calculation of the maximum temperature that influences the resistance of the studied mixture for each time period. This coefficient also allowed obtaining an equation capable of determining the maximum resistance that can be reached in each curing time independent of curing temperature. The failure envelope found has a non-circular shape, so the strength of the material is dependent on the stress path. The isotropy of the material was confirmed by comparing equal stress paths, but executed in different directions and by comparing the Oedometric Modulus in small strains (M0 ) and Shear Modulus in small strains (G0 ) of the x, y, and z directions the sample.