Th. 3e cycle--Optique et trait, du signal--Besançon, 1982. N°: 384.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "May, 2008." Includes bibliographical references (leaves 63-64). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). "February 2008." Includes bibliographical references (p. 191-199). Also available via the World Wide Web.

Made available in DSpace on 2014-06-11T19:27:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31Bitstream added on 2014-06-13T19:47:38Z : No. of bitstreams: 1 menezes_cl_me_prud.pdf: 537017 bytes, checksum: 903487eb7b8ea31bd975c66d5fc494ef (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho é estudada a estabilidade para a equação de Stokes com diferentes condições de contorno em um esquema implícito. São consideradas análise pelo modonormal (método de Fourier) e pela computação numérica do fator de amplificação / In this work we studied the stability for the Stokes equation with different boundary conditions in an implicit scheme. The normal-mode analysis (Fourier method) and numerical computation of the amplification factor are considered

Organosilanes are widely used to bond organic materials such as polymers to inorganic materials in polymer composites. However, the mechanism of adhesion is poorly understood. One postulated mechanism is the interdiffusion of the silane and polymer, along with condensation of the silane to form an interpenetrating polymer network (IPN). The techniques of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and Raman confocal microscopy have been used to study the diffusion, hydrolysis and condensation of three organosilanes in silicon / PVC / silane laminates. These processes are thought to contribute to the formation of the IPN, and hence to be vital for adhesion. The organosilanes studied were [3-(amino)propyl]trimethoxysilane, also known as A1110, [3-(phenylamino)propyl]trimethoxysilane, known as Y9669, and [3-(mercapto)propyl]triethoxysilane, known as A1891.ATR-FTIR was shown to be an excellent technique for studying the kinetics of silane diffusion through PVC films. It was shown that at room temperature, no diffusion through unplasticised PVC films occurred. At 70 °C, however, diffusion occurred readily for Y9669 and A1891. In plasticised PVC films, diffusion was observed for all three silanes at room temperature. It was shown that the diffusion occurred more quickly with higher plasticiser concentrations, and hence lower glass transition temperatures. The kinetics of diffusion was found to fit a dual mode sorption model. Hydrolysis of the silanes was also followed by infrared spectroscopy, and the kinetics of hydrolysis and condensation were shown to be highly dependent upon silane type, the concentration of water, and the presence of an acid catalyst. The hydrolysis of the silanes was found to slow their diffusion through both plasticised and unplasticised PVC films. It was shown that the presence of water in the films caused the hydrolysis of the silanes in situ. Raman depth profiles were measured of the films before, during and after diffusion. The spatial resolution was shown to be adversely affected by refraction at the air / PVC interface. It was shown that it is possible to deconvolve the confocal response of the microscope from the depth profiles, resulting in greater spatial resolution. Hydrolysis of the silanes was followed in solution by Raman spectroscopy, and it was found that each of the three silanes showed different rates of hydrolysis and condensation. It was shown that it was also possible to follow the kinetics of diffusion by Raman microscopy, and the results agreed well with those shown by ATR-FTIR spectroscopy.

Neste trabalho foram estudados catalisadores heterogêneos para a reação de transesterificação e esterificação avaliando sua atividade catalítica. Sólidos impregnados em sílica e óxidos de hidrotalcita contendo cargas de Ba, Ca e Nb foram obtidos pelas técnicas de impregnação úmida e coprecipitação, respectivamente. NaOH e ureia foram utilizados como agente precipitantes na coprecipitação. A caracterização dos mesmos foi realizada através das técnicas tradicionais para o estado sólido, como Espectroscopia no Ultravioleta-visível (UV-vis), Espectroscopia por Infravermelho com Transformada de Fourier (IV), Difração de Raios-X (DRX) e Microscopia Eletrônica de Varredura (MEV). O requerimento de um cuidado especial na remoção de sódio em sólidos coprecipitados com NaOH foi observado. Os materiais contendo 25 e 35 % de BaO sobre a SiO2 apresentaram atividade para a reação de transesterificação, atingindo 93,5 e 87,0 % de conversão, respectivamente. No entanto, a presença de nitratos na análise de IV pode indicar uma tendência à lixiviação de espécies de Bário. O material obtido como Ca4MgAl apresentou conversão de 97,9 % em biodiesel, porém, há uma significativa contribuição da catálise homogênea, cerca de 22 %. / In this work we were studied heterogeneous catalysts for the reaction of transesterification and esterification evaluating its catalytic activity. Solid impregnated silica and hydrotalcite oxides containing loads of Ba, Ca and Nb were obtained by wet impregnation and coprecipitation techniques, respectively. NaOH and urea was used as precipitating agent in the coprecipitation. The characterization of these was carried out using traditional techniques to solid, such as Spectroscopy Ultraviolet-visible (UV-vis) Spectroscopy Infrared Fourier Transform (IV), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). An application for a special care in sodium removal on solid co-precipitated with NaOH was observed. Materials containing 25 and 35 % BaO on SiO2 showed activity for the transesterification reaction, reaching 93,5 and 87,0 % conversion, respectively. However, the presence of nitrates in the IV analysis may indicate a tendency to leaching of barium species. The material obtained as Ca4MgAl showed 97,9 % conversion into biodiesel, however, there is a significant contribution of homogeneous catalysis, about 22 %.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-graduação em Matemática / Made available in DSpace on 2012-10-24T03:27:12Z (GMT). No. of bitstreams: 1 251847.pdf: 3150525 bytes, checksum: 40f70c8122594bd8e8863233ef7c6b1f (MD5) / Esta dissertação apresenta um estudo sobre duas famílias de métodos para análise e ressíntese de sinais musicais: métodos no domínio do tempo (Iteração Ortogonal Adaptativa, Strobach, NP3 e OPAST) e métodos no domínio das freqüências (Phase Vocoder, PARSHL e SMS). Inicia apresentando algumas características dos sinais sonoros e introduzindo alguns modelos para sua representação matemática. Depois, apresentam-se métodos no domínio do tempo, que utilizam matrizes de Hankel com os dados do sinal, a partir das quais buscam-se os parâmetros que o descrevem. Além dos métodos de Iteração Ortogonal e de Strobach, utilizam-se implementações próprias dos algoritmos NP3 e OPAST em MATLAB. Em seguida, exibem-se resultados de testes realizados com sinais musicais monofônicos. Finalmente, após uma introdução à análise de Fourier, que fundamenta os métodos no domínio das freqüências apresentados a seguir, apresentam-se resultados de testes com esses métodos. Para os métodos Phase Vocoder e SMS, são utilizadas implementações públicas e, para o método PARSHL, uma implementação própria, todas programadas em MATLAB. Esses testes são realizados também com uma música polifônica. O trabalho encerra com a aplicação de transformações de mudança de velocidade e tom a essa música. This dissertation presents a study on two families of methods for analysis and resynthesis of music signals: time domain methods (Adaptive Orthogonal Iterations, Strobach, NP3 and OPAST) and frequency domain methods (Phase Vocoder, PARSHL and SMS). First, we present some features about sound signals and some models for their mathematical representation. After, we present time domain methods that utilize Hankel matrices, from which we search parameters that describe the signal. Besides Adaptive Orthogonal Iterations and Strobach methods, we utilize personal implementations of NP3 and OPAST algorithms in MATLAB. After, we present some results from experiments with monophonic music signals. Finally, after an introduction to Fourier analysis, which is the background for the explanation of those frequency domain methods, we present results of experiments with those methods. For Phase Vocoder and SMS we use public implementations, and for PARSHL we use a personal implementation, all of them in MATLAB.

The growing use and demand for microwave communication systems has led to an increase in system density, particularly in urban areas. Consequently this rise has increased the risk of interference. Especially in urban areas the abundant presence of potential obstacles increase the risk of multipath propagation. Multipath propagation on radio links is associated with signal delays and signal level fades on which adversely influences the system performance. For efficient frequency planning the knowledge of the multipath geometries involved is required. This knowledge can be obtained by resolving the experienced multipath field into its constituent components yielding their amplitudes and angles of arrivals at a receiver terminal. Some previous investigations into the resolution of multipath generated height gain curves are documented in the literature. These generally however oncentrate on resolving the two predominant signal components. In an urban environment the number of expected constituent signal components exceed the number of two. Resolution of more than two components requires considerably more effort than this relatively simple case. This thesis provides a component resolution procedure which determines the individual amplitudes and angles of arrival of constituent multipath components. The procedure is applied to the spatial amplitude envelope observed when displacing a receiver incrementally over a distance of a few wavelength through a multipath field. The presented solution can be applied with inexpensive easurement and computational means. For the resolution process it is only required to record the envelope pattern amplitude values without any phase information being required. The use of a single standard antenna as receiver is also sufficient. The procedure does not require data of an array of antenna elements. The performance of the resolution procedure has been tested and validated in an extensive experimental programme which was part of this research. Preliminary results of this project are published in the report of the European COST 235 project.

We extend the theory of singular integral operators and multiplier theorems to the setting of anisotropic Hardy spaces. We first develop the theory of singular integral operators of convolution type in the anisotropic setting and provide a molecular decomposition on Hardy spaces that will help facilitate the study of these operators. We extend two multiplier theorems, the first by Taibleson and Weiss and the second by Baernstein and Sawyer, to the anisotropic setting. Lastly, we characterize the Fourier transforms of Hardy spaces and show that all multipliers are necessarily continuous.

The advent of highly-coherent x-ray light sources, such as those now available world-wide in modern third-generation synchrotrons and increasingly available in free-electron lasers, is driving the need for improved analytical and experimental techniques which exploit the coherency of the generated light. As the light illuminating a sample approaches full coherence, a simple Fourier transform describes the diffraction pattern generated by the scattered light in the far field; because the Fourier transform of an object is unique, coherent scattering can directly probe local structure in the scattering object instead of bulk properties. In this dissertation, we exploit the coherence of Advanced Light Source beamline 12.0.2 to build three types of novel coherent scattering microscopes. First, we extend the techniques of coherent diffractive imaging and Fourier transform holography, which uses iterative computational methods to invert oversampled coherent speckle patterns, into reflection geometry. This proof-of-principle experiment demonstrates a method by which reflection Bragg peaks, such as those from the orbitally-ordered phase of complex metal oxides, might eventually be imaged. Second, we apply a similar imaging method to the x-ray beam itself to directly image the mutual coherence function with only a single diffraction pattern. This technique supersedes the double-slit experiments commonly seen in the scattering literature to measure the mutual intensity function by using a set of apertures which effectively contains all possible double slit geometries. Third, we show how to evaluate the speckle patterns taken from a labyrinthine domain pattern for "hidden" rotational symmetries. For this measurement, we modify the iterative algorithms used to invert speckle patterns to generate a large number of domain configurations with the same incoherent scattering profile as the candidate pattern and then use these simulations as the basis for a statistical inference of the degree of ordering in the domain configuration. We propose extending this measurement to position-resolved speckle patterns, creating a symmetry-sensitive microscope. The three new techniques described herein may be employed at current and future light sources.