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The isothermal movement of liquid water in saturated soil has been intensively studied, and a sound theoretical basis has been developed. Considerably less is known about the flow of water in unsaturated soils, but a general theory based on Darcy's law of flow is beginning to develop. A good theoretical basis exists for the vapor diffusion under isothermal conditions. Inconsistent data and theories are found in the literature concerning the movement of water in both the vapor and liquid phases, under the influence of thermal fields.

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Made available in DSpace on 2014-10-09T12:27:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:09Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:09Z (GMT). No. of bitstreams: 0 / Este trabalho descreve um estudo experimental dos efeitos da temperatura em um elemento de pavimento de concreto, construído em laboratório interno e instrumentado com sensores de deformação, deslocamento, força e temperatura. A estrutura foi construída em duas camadas (placa e base) assentadas sobrepostas, sem aderência, sobre um subleito artificial. Os efeitos térmicos foram gerados artificialmente seguindo padrões sazonais da natureza. Os carregamentos estáticos foram realizados por meio de uma máquina hidráulica referenciados a um eixo simples de roda simples. A estrutura foi dimensionada e construída em uma escala de tamanho reduzido, distorcida e montada sobre uma laje de reação. Sob a placa do pavimento foi construído um sistema térmico auto controlado para causar diferencial de temperatura entre o fundo e o topo da placa pela passagem de um fluido. No topo um sistema térmico com controle manual foi construído para gerar gradientes térmicos através da estrutura. Todas as ações foram registradas automaticamente por meio de um sistema de aquisição de dados. Os resultados combinam com os dados da literatura, com experimentos realizados em pistas experimentais e se correlacionam com simulações realizadas por meio de software específico. Isso implica que a metodologia usada é apropriada para ser utilizada em outras situações e experimentos. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Decades of research have fostered a greater understanding of the environmental controls that drive tropical cyclone (TC) intensity change, yet the community has achieved only small improvements in intensity forecasting. Numerous environmental factors impact TC intensity, such as vertical wind shear and sea surface temperatures (SSTs), but little research has focused on establishing if SST change under the TC, or SST gradients, influence these intensity changes. This study investigated three methods to compute SST gradients. The first method calculated the SST change within fixed distances along the track. In the second and third methods, the SST was calculated over the distance traversed by the TC in two separate six-hour periods. By examining 455 24-hour weakening episodes in the eastern North Pacific, this study revealed that the first SST gradient method explained the highest 24-hour weakening variance for TCs located within SSTs at or lower than 26.5 degrees C.

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The ability to resolve reactions within a monolith spatially and temporally is key in developing reliable kinetic models, as well as in validating proposed reaction mechanisms. In this work, two techniques, IR-thermography and spatially-resolved capillary inlet mass spectrometry (SpaciMS), were used to measure temperature and gas-phase concentrations. Specifically, they were applied to monitor the axial distribution of temperature and concentration profiles during propylene oxidation over a Pt/Al2O3 monolith-supported catalyst. Also, the effect of thermally aging the catalyst on the temperature and concentration patterns observed was investigated. During temperature programmed oxidation experiments, the data show that conversion of propylene began at the outlet, and a reaction front generated at the rear of the monolith traveled upstream, as a moving reaction zone, thereby creating a temperature wave pattern since the reaction is exothermic. The conversion was always complete downstream of this reaction zone at any point along the catalyst. When the reactor was cooled, the conversion of propylene started to drop, accompanied by a similar temperature wave pattern that traveled in the opposite direction (from upstream to downstream) and was attributed to a phenomenon known as wrong-way behavior. Finally, thermally aging the catalyst led to a slower and more localized moving hot zone.

The ability to resolve reactions within a monolith spatially and temporally is key in developing reliable kinetic models, as well as in validating proposed reaction mechanisms. In this work, two techniques, IR-thermography and spatially-resolved capillary inlet mass spectrometry (SpaciMS), were used to measure temperature and gas-phase concentrations. Specifically, they were applied to monitor the axial distribution of temperature and concentration profiles during propylene oxidation over a Pt/Al2O3 monolith-supported catalyst. Also, the effect of thermally aging the catalyst on the temperature and concentration patterns observed was investigated. During temperature programmed oxidation experiments, the data show that conversion of propylene began at the outlet, and a reaction front generated at the rear of the monolith traveled upstream, as a moving reaction zone, thereby creating a temperature wave pattern since the reaction is exothermic. The conversion was always complete downstream of this reaction zone at any point along the catalyst. When the reactor was cooled, the conversion of propylene started to drop, accompanied by a similar temperature wave pattern that traveled in the opposite direction (from upstream to downstream) and was attributed to a phenomenon known as wrong-way behavior. Finally, thermally aging the catalyst led to a slower and more localized moving hot zone.