Wavelike spiral asymmetries are an intriguing aspect of Tropical Cyclone dynamics. Previous work hypothesized that some of them are Vortex Rossby Waves propagating on the radial gradient of mean–flow relative vorticity. In the Intermittently Forced Vortex Rossby Wave theory, intermittent convection near the eyewall wind maximum excites them so that they propagate wave energy outward and converge angular momentum inward. The waves’ energy is absorbed as the perturbation vorticity becomes filamented near the outer critical radii where their Doppler–shifted frequencies and radial group velocities approaches zero. This process may initiate outer wind maxima by weakening the mean–flow just inward from the critical radius. The waves are confined to a relatively narrow annular waveguide because of their slow tangential phase velocity and the narrow interval between the Rossby wave cut–off frequency, where the radial wavenumber is locally zero, and the zero frequency, where it is locally infinite.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-05-30T17:42:50Z No. of bitstreams: 1 DissBL.pdf: 8282671 bytes, checksum: 5dfca89e85bbea10d97a0617e91d1408 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-01T17:47:56Z (GMT) No. of bitstreams: 1 DissBL.pdf: 8282671 bytes, checksum: 5dfca89e85bbea10d97a0617e91d1408 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-01T17:48:03Z (GMT) No. of bitstreams: 1 DissBL.pdf: 8282671 bytes, checksum: 5dfca89e85bbea10d97a0617e91d1408 (MD5) / Made available in DSpace on 2017-06-01T18:20:58Z (GMT). No. of bitstreams: 1 DissBL.pdf: 8282671 bytes, checksum: 5dfca89e85bbea10d97a0617e91d1408 (MD5) Previous issue date: 2017-02-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The study of ceramic composites assisted by computer simulation is well spread nowadays. It is an interest of the ceramic industry the development of materials models trustfully enough to reduce cost with prototypes and virtually explore an infinitude of materials compositions and thermomechanical loads. The mismatch of thermal and mechanical properties among the composite’s phases may induce decohesions or cracks after temperature variation. The computer modeling of this behavior could auxiliate the planning of the systems’ composition, as it becomes possible to evaluate the influence of the concentration of an specific constituent on the global behavior. The present dissertation aims to analyze the role of the geometrical feature, such as inclusion radius and volume fraction, in the composite behavior submitted to temperature variation. It was also analyzed the application of coesive elements to simulate the cracking phenomena in ceramic systems. The main results of this dissertation were not only the thermomechanical properties influence on the global behavior of ceramic systems, but also the construction of finite element models that might be usefull to others reseachers on the investigation of the thermomechancial behavior of distincts ceramic systems. / O estudo de compósitos cerâmicos assistido por simulação computacional encontra-se em plena expansão. É de grande interesse da indústria cerâmica o desenvolvimento de modelos confiáveis de materiais o suficiente para reduzir os custos com protótipos e explorar virtualmente uma infinidade de possibilidades de composições e solicitações termomecânicas. A diferença entre as propriedades termomecânicas dos constituintes de compósitos pode induzir o surgimento de defeitos quando estes são submetidos a variações de temperatura. A modelagem computacional adequada destes sistemas nestas condições pode auxiliar no planejamento da composição do sistema, uma vez que é possível avaliar a influência da concentração de determinado constituinte no comportamento global do compósito. O presente trabalho objetiva analisar desde a influência do raio e fração volumétrica de inclusões até o efeito das diferenças de propriedades termomecânicas entre as fases no comportamento de compósitos cerâmicos submetidos a variações de temperatura. Analisar também, a aplicação de elementos coesivos na simulação da fissuração de sistemas cerâmicos. Como resultados principais, apresenta-se não só a compreensão dos efeitos de determinadas propriedades termomecânicas, mas também a construção de modelos em elementos finitos que podem ser utilizados por terceiros na investigação do comportamento termomecânico de sistemas cerâmicos.

In thisproject, solubility of butyl paraben in 7 puresolvents and 5 ethanol aqueous solvents has been determined at from 1 ℃to 50 ℃. Thermodynamic properties of butyl paraben have been measured by DifferentialScanning Calorimetey. Relationship between molar solubility of butyl paraben in6 pure solvents and thermodynamic properties has been analyzed. Thisrelationship suggests a method of estimating activity of solute at equilibrium fromcombining solubility data with DSC measurements. Then, activity coefficient accordingto the solubility at different temperatures can be estimated. Duringthe solubility measurements in ethanol aqueous solvents, it is found that whenbutyl paraben is added into aqueous solutions with certain proportion ethanol,solutions separates into two immiscible liquid layers in equilibrium. Water andethanol are primary in top layer, while the butyl paraben is primary in bottomlayer, but the solution turns to cloudy when two layers of solution are mixed. Theaim of this work was to present the phase behaviour of liquid-liquid-phaseseparation for (butyl paraben + water + ethanol) ternary system from 1 ℃ to 50 ℃at atmospheric pressure. Thearea of liquid-liquid-phase separation region in the ternary phase diagram increaseswith the increasing temperature from 10 ℃to 50 ℃. In thisstudy, more than several hundreds of nucleation experiments of butyl paraben havebeen investigated in ethyl acetate, propanol, acetone and 90% ethanol aqueoussolution. Induction time of butyl paraben has been determined at 3 differentsupersaturation levels in these solvents, respectively. Free energy ofnucleation, solid-liquid interfacial energy, and nuclei critical radius havebeen determined according to the classical nucleation theory. Statistical analysis ofinduction time reveals that the nucleation is a stochastic process with widevariation even at the same experiment condition. Butyl paraben nucleates most difficultlyin 90 % ethanol than in other 3 solvents, and most easily in acetone. The interfacialenergy of butyl paraben in these solvents tends to increasing with decreasemole fraction solubility in these solvents. Coolingcrystallizations with different proportions of butyl paraben, water and ethanolhave been observed by Focused Beam Reflectance Method, Parallel VirtualMachine, and On-line Infrared. The FBRM, IR curves and the PVM photos show someof the solutions appeared liquid-liquid phase separation during coolingcrystallization process. The results suggest that if solutions went throughliquid-liquid phase separation region during the cooling crystallizationprocess the distribution of crystals crystal was poor. Droplets from solutions withsame proportion butyl paraben but different proportions of water and ethanolhave been observed under microscope. Induction time of the droplets has been determinedunder the room temperature. Droplets from top layer or bottom layer of solutionwith liquid-liquid phase separation on small glass or plastic plates were alsoobserved under microscope. The microscope photos show that the opposite flows ofcloudy solution on the glass and the plastic plate before nucleation. The resultsof the cooling and evaporation crystallization experiments both revealed thatnucleation would be prevented by the liquid-liquid phase separation. / QC 20110630