Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 134-140). Also available for download via the World Wide Web; free to University of Oregon users.

Techn. Universiẗat, Diss., 2003--Berlin.

Thesis (MScIng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 103-111).

The structure and conformation of lithium phenyl stearate (and to a lesser extent, for comparative purposes, cadmium stearate) was investigated using Fourier transform infrared spectroscopy, and various modelling techniques. The infrared results for LiPS show that the aliphatic portion of the soap molecule is much more ordered at room temperature than had been expected, having only 0.62 and 0.60 gtg and gg defects per molecule respectively, where an isotropic chain would have 1.35 and 1.21 gtg and gg defects per chain respectively. As the temperature is increased the number of conformational defects increases continuously, until at < 130°C the chain reaches an isotropic degree of disorder. At this point the phase transition begins, so the chain reaches liquid like disorder before the phase transition begins. Modelling of the phenyl stearic acid showed that the phenyl group was restricted to certain angle of rotation values, and that the bonds close to the phenyl group were prevented from attaining true rotational isomeric state conformations, gtg defects near the phenyl group were distorted only slightly from their usual angular position, and an additional band in the infrared spectrum of LiPS at 1363 cm-1 has been assigned to this distorted gtg/gtg' defect. The gg defects near the phenyl group have a much greater distortion (and energy) resulting in a much reduced probability of occurrence. The number of gg defects present at the phase transition (< 130°C) was only 75% of that expected for an isotropic n-alkane of equivalent chain length, indicating that the four bonds nearest to the phenyl group have a reduced probability of forming a gg defect. The modelling of the ionic core of LiPS gives a reasonable estimate of between 5.6 to 7.1 A for the core radius. When this is used to calculate the hexagonal cylinder diameter, at room temperature, along with the average chain extension, it gives a value for the cylinder diameter of between 33.9 to 36.8A. The hexagonal lattice parameter determined by X-ray diffraction has a value 35.9A. Also after the LiPS sample has gone through the phase transition beginning at >130&deg;C, the hexagonal lattice parameter is 31.4A while the cylinder diameter lies between 30.2 and 33.2A.Crystalline cadmium stearate was found to contain two crystal forms, orthorhombic which has lattice dimensions of a0=5.05A, b0=7.35A and c0=48.6A and the other eithermonoclinic or triclinic. In the reverse hexagonal phase, the cadmium stearate molecule behaves like an isotropic n-alkane of equivalent chain length. The model used to predict the core radius of divalent metal soaps gives rise to some inconsistencies: the cylinder diameter thus determined gives a result between 28.8A to 31.7A, while the lattice parameter determined by X-ray diffraction gives a value of 36.9A. The assumption that the n-carboxylate ions in a divalent metal soap behave like two independent monovalent metal ion soaps appears to be incorrect.

This thesis is concerned with the development of a practical digital image processing system for recording and subsequent reconstruction of the magnitude and phase of an optical wave-front arriving from a coherently illuminated object disturbance. Since the wave-fronts of concern are coherent, the magnitude and phase of such waves are generally independent functions in the sense that the knowledge of one is not sufficient to uniquely deduce the other. To uniquely reconstruct and characterize optical disturbances both the magnitude and phase are required. In general, all recording media respond only to light intensity and no difficulty is encountered in recording the intensity and therefore the magnitude, because it is the square root of the intensity.

No description available.

Orientador: Eugênio Spanó Rosa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T06:14:18Z (GMT). No. of bitstreams: 1 GomezBueno_LuisGerardo_M.pdf: 4585840 bytes, checksum: b8ed6708894a46ed052d422f40624935 (MD5) Previous issue date: 2010 / Resumo: Medidas experimentais foram realizadas em uma tubulação de 26 mm de diâmetro interno, com inclinação variável de horizontal a vertical, operando com escoamento de água e ar no padrão intermitente ou "slug". Foram utilizados dois sensores de impedância posicionados 77D e 257D a jusante do misturador de água e ar. As faixas de velocidades superficiais de gás e líquido foram 0,1 m/s a 2,1 m/s e 0,3 m/s a 1,2 m/s, respectivamente. Os ângulos de inclinação da tubulação variaram de 15 em 15 graus desde a horizontal até a vertical. Por meio dos sensores de impedância e de pressão foram determinados os parâmetros: a velocidade do nariz da bolha de ar, o comprimento da bolha e do pistão líquido, a freqüência, o fator de intermitência, a taxa de coalescência e a queda de pressão. Uma análise do comportamento destes parâmetros em função das vazões de água e ar assim como dos ângulos de inclinação é realizada / Abstract: This work analyses experimentally the flow properties of a gas-liquid mixture flowing in the slug regime in inclined lines. The experimental data are collected through a pair of impedance probes placed at 77D and 257D downstream of the air-water mixer in a 26mm ID pipe. During the tests air and water superficial velocities spanned, respectively, from 0,1 m/s to 2,1 m/s and from 0,3 m/s to 1,2 m/s. The tests started with the line positioned at the horizontal, 0 degrees and changed, in steps of 15 degrees each, up to the vertical position or 90 degrees. Along each line position the pressure drop, the bubble velocity, the lengths of the liquid slug and of the elongated bubble, the coalescence rate as well as the frequency of the air-water structures were measured. This work analyses the effect of the line inclination on the slug flow properties / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

The use of plasma sprayed ceramic coats as thermal barrier coatings (TBCs) for the protection of metallic structures and equipment from severe thermal, abrasive and corrosive conditions has been documented extensively in the last two decades. The state-of-the-art TBCs consist of a double layer coat. a top ceramic layer and an intermediate bond coat (MCrAIY, M=Ni, Co, Fe) deposited on the alloy substrate. Zirconia, both stabilized and partially stabilized with different oxides has been used as the ceramic top coat due to its low thermal conductivity and low thermal expansion coefficient. Studies of the microstructure of the TBCs have shown aspects that can help the understanding of the properties of the coating. The ternary system ZrOz-Y203-TiCz is believed to offer improved properties when it is compared to Zr02-Y203. However, the use of &02-Y203-Ti02 as TBCs, a major part of this work, is not widely reported in the literature. The purpose of this thesis was to study the microstructure of a plasma sprayed ZrOrY203-TiO2 TBC using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). The evolution of the Zr41_phase distribution in the ceramic coat was followed by XRD after different heat treatments, with the finding that the cooling rate plays a decisive role in the final Zr42 phase composition. SEM studies allowed a description of the lamellae structure of the Zr02-Y203-TiOz coating. The evolution of the morphology, porosity and crack distribution in the coat after different thermal treatments were followed by SEM. Evidence of incipient sintering is observed in Zr02-Y203-Ti02 coats heated at temperatures higher than 1200 °C. This should lead to poor coating performance. EDS analysis revealed an heterogeneous distribution of titanium through the oating. A detailed microstructural characterization of the as-sprayed coating was done using TEM. Microstructural features such as micro-twins, antiphase-boundaries and mottled morphology associated with "non-transformable" tetragonal ZrO2 phase were identified. It is believed that these microstructural elements promote toughening and thermal stress relief mechanisms that provide the coating with the erosion and thermal shock resistance required for a TBC. The presence of TiO2 is linked to a higher proportion of tetragonal ZrO2 in the Zr02-Y203-Ti02 coating, therefore improved properties of the coating are expected. The addition of TiO2 promotes grain growth and decreases the final density in pressed and sintered Zr02-Y203-TiO2 powders. The results obtained are a contribution to the understanding of the microstructure of TBCs and to the sparse knowledge base of the ZrOrY2O3-TiO2 coatings. Further work should be done in the characterization of the ZrO2-Y2O3-Ti42 coatings and the study of its stability under different conditions in order to determine the real potential of this material offers as an alternative to the better known ZrOrY203 TBC.

D. Phil. (Physics) / Please refer to full text to view abstract