published_or_final_version / abstract / toc / Physics / Doctoral / Doctor of Philosophy

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The climb of dissociated dislocations in FCC materials is known to be complex: Observations of climb under HVEM irradiation in CuAl suggest that it, proceeds via the nucleation of interstitial loops directly onto individual partials. In silver, however, dissociated dislocations appear to constrict at an early stage in the irradiation, and dense vacancy cluster damage is seen to form in their vicinity. This thesis presents results and analysis of a study aimed at the determination of the interaction of HVEM generated interstitials and vacancies with pre-existing dislocations in a range of Fe-17Cr-Ni ternary alloys (with the nickel content varying between 15 and 40%). Two quaternary alloys (Fe-15%Ni-17%Cr-l%Si and Fe-15%Ni-17%Cr-2%Mo) arc also studied. As with earlier studies in CuAl and Ag, pre-existing dislocations in a (111) orientated foil were first characterized at subthreshold voltages employing the weak-becim technique, then irradiated with IMeV electrons at temperatures in the range 400-430°C and finally returned to the low voltage microscope for postirradiation characterization of the observed damage. Analysis of the post-irradiation microstructures indicates that interstitial climb only occurs at particularly favourable sites, such as pre-existing jogs: For the ternary alloys, constrictions are removed along edge and mixed dislocations, whilst zig-zagging of screw and near-screw dislocations may also be attributable to jog climb. After the annihilation of constrictions evidence of climb is not seen and pipe diffusion is thought to be occurring. The precipitation of small clusters, many of which are identifiable as vacancy SFT, is reminiscent of observations in silver. The addition of silicon to the matrix apparently leads to the creation of favourable sites for interstitial climb, as evidenced by the formation of high densities of new jogs after irradiation. Loops are seen to precipitate close to dislocations in the Mo-doped material. The origin of these loops is unclear at this stage. The relevance of the results to the phenomenon of void swelling is discussed.

The objective of this thesis is to present the fabrication of a multiphoton microscope and the underlying theory responsible for its proper functioning. A basic introduction to nonlinear optics will give the necessary knowledge to the reader to understand the optical effects involved. Femtosecond laser pulses will be presented and characterized. Each part of the microscope, their integration and the design of the microscope will be discussed. The basic concepts of laser scanning microscopy are also required to explain the design of the scanning optics. Fast scanning problems and their solutions are also briefly viewed. As a working proof, the first images taken with the microscope will be presented. Fluorescent beads, rat tail tendon, gold nanoparticles and pollen grain images using various nonlinear effects will be shown and discussed.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 57-63). Also available in electronic format on the Internet.

Thesis (M.S.)--University of Michigan, 1973.

Thesis (Ph. D.)--University of Hong Kong, 2004. / Title proper from title frame. Also available in printed format.

Made available in DSpace on 2015-08-20T17:09:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-23. Added 1 bitstream(s) on 2015-08-20T17:26:29Z : No. of bitstreams: 1 000837544.pdf: 4548876 bytes, checksum: d50c957c71c1497ccdc64d03f717ca8f (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Microscopias têm sido utilizadas para avaliação da morfologia de diferentes estruturas de materiais. Entretanto, seus resultados podem ser afetados por vários fatores externos. Técnicas de processamento de imagens podem ser empregadas para atenuar esses fatores, aprimorando os resultados. Neste estudo é proposto um método de segmentação de fotomicrografias em vários níveis, denominado Segmentação Starlet Multinível (MLSS), fundamentado na transformada walvelet starlet, uma walvelet não-decimada. A escolha de um nível ótimo de segmentação se dá pela técnica de nome Segmentação Starlet Ótima Multinível (MLSOS), que se baseia nos resultados da MLSS e no coeficiente de correlação de Matthews (MCC) faz a comparação entre as segmentações obtidas e imagens ground truth, elegendo a melhor segmentação para a imagem de entrada. Os métodos são avaliados pelos valores de precisão, sensibilidade e exatidão. MLSS e MLSOS deram origem ao software livre Jansen-MIDAS, voltando ao uso dessas técnicas pelo usuário final. O programa foi utilizado na separação de elementos em imagens de diferentes materiais, a saber: nanoportículas de ouro em amostras de borracha natural traços de fissão em cristais de epídoto. Nessas aplicações, o método proposto apresentou exatidão maior que 87% para as imagens de teste / Microscopies have been used for morphology evaluation of different materials structures. However, their results can be affected by several external factors. Image processing techniques can be used to attenuate these factors, improving the results. In this study we propose a method for segmentation of photomicrographs, denominated Multi-Level Startelet Segmentation (MLSS), based on the starlet wavelet transform. The choise of an optimal segmentation level is given by Multi-Level Optimal Segmentation (MLSOS), that uses MLSS results and the Matthews correlation coefficient (MCC). MCC compares the obtained segmentations and ground truth images, choosing the best segmentation for the input image. MLSS and MLSOS are evaluated using precision, recall and accuracy. Jansen-MIDAS, an open-source software from these methods, allows using MLSS and MLSOS by the end user. This software was employed in the separation of elements in images of different materials, namely gold nanoparticles in natural rubber samples and fission tracks in epidote crystals. In these applications, the proposed method presented accuracy higher than 87% for all test images / FAPESP: 11/09438-3

Made available in DSpace on 2014-06-11T19:23:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-13Bitstream added on 2014-06-13T19:30:04Z : No. of bitstreams: 1 sartori_em_me_araca.pdf: 1981097 bytes, checksum: 108176df6308fa34d3c4ef0f7ea4c265 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Objetivo: Avaliar comparativamente, em costela bovina, a deformação, a rugosidade e a perda de massa, de três diferentes tipos de tratamento de superfície de fresas, utilizadas em osteotomias, para instalação de implantes osseointegráveis. Materiais e método: Foram utilizadas 25 costelas bovinas e 3 tipos de fresas helicoidais de 2.0 mm e 3.0 mm para osteotomias para instalação de implantes (Fresa de aço (G1), Fresa com revestimento de filme de Carboneto de Tungstênio em Matriz de Carbono (G2) e Fresa de Zircônia (G3)), que foram subdivididas em 5 subgrupos: 1 – fresas sem uso e 2, 3, 4 e 5 correspondente ao número de perfurações 10, 20, 30 e 40, respectivamente. Todas as fresas foram submetidas a medidas de rugosidade (Ra, Rz e Rmáx), massa (gramas) e análise em microscópio eletrônico de varredura (MEV) antes e após uso. Os dados foram tabulados e submetidos a análise estatística através do Teste de Kruskal-Wallis e, quando encontrada diferença estatisticamente significante, ao Teste de Dunn. Resultados: Houve perda de massa em todos os grupos (G1, G2 e G3), sendo essa redução de forma gradual, conforme o número de perfurações realizadas (1, 2, 3, 4 e 5). Mas esta diferença não foi estatisticamente significante (P<0,05). Ao analisarmos os testes de rugosidade o G3 apresentou aumento de Ra, Rz e Rmáx (P<0,05) em relação ao G2. E um aumento de Ra em relação ao G1. Não houve diferença estatisticamente significante (P<0,05) entre G1 e G2. Na análise por microscopia eletrônica de varredura (MEV) foram observadas áreas de deformação em todas as amostras de 2.0 mm, com perda de substratos, sendo o G3 o que mais apresentou essas características. Conclusão: As fresas de Zircônia de 2.0 mm apresentaram maior perda de substratos e desgaste por abrasão, na região de corte. Apresentaram... / Purpose: Evaluate comparativily, in bovine ribs, the deformation, rugosity and loss of mass, in three different types of bur covering, used in dental implants osteotomy. Materials and methods: Twenty five (25) bovine ribs and three (3) types of helical burs of 2.0 mm and 3.0 mm for dental implant bed preparation had been used (Stell Bur (G1), Tungsten Carbid inCarbon Matriz Bur (G2) and Zirconia Bur (G3)), that they had been subdivided in five sub-groups: 1 – bur without use and 2, 3, 4 and 5 correspondent to the number of perfurations: 10, 20, 30 and 40, respectively. All burs had been measure in rugosity tests (Ra, Rz and Rmax), mass (gram) and scanning electron microscope (SEM) analisys before and after use. The data had been tabulated and submitted to statistical analysis through Kruskal-Wallis Test and, when significant statistical differnces were found, to Dunn Methods Test. Results: Loss of mass where found in all groups (G1, G2 and G3), being this reduction in gradual form as the number of carried through perfurations (1, 2, 3, 4 and 5). But this difference was not statistical significant (P<0,05). When analyzing the rugosity tests the G3 presented increase of Ra, Rz and Rmax (P<0,05) in relation to G2. And a increase of Ra in relation to G1. It did not have significany statistical difference (P<0,05) between G1 and G2. In the scanning electron microscope (SEM) analysis it was observed in all the 2.0 mm samples plastic deformation and drill wear, having been G3 what more it presented these characteristics. Conclusion: The 2.0 mm Zirconia burs had presented major consuming and drill wear in the cutting area. They had presented, also, an increase of rugosity related to G1 and G2. There was no significant statistical differences... (Complete abstract click electronic access below)

Orientador: Aldo Eloizo Job / Co-orientador: Aylton Pagamisse / Banca: Eniuce Manezes de Souza / Banca: Deuber Lincon da Silva Agostini / Banca: Eduardo Augusto Campos Curvo / Banca: Messias Meneguette Junior / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Microscopias têm sido utilizadas para avaliação da morfologia de diferentes estruturas de materiais. Entretanto, seus resultados podem ser afetados por vários fatores externos. Técnicas de processamento de imagens podem ser empregadas para atenuar esses fatores, aprimorando os resultados. Neste estudo é proposto um método de segmentação de fotomicrografias em vários níveis, denominado Segmentação Starlet Multinível (MLSS), fundamentado na transformada walvelet starlet, uma walvelet não-decimada. A escolha de um nível ótimo de segmentação se dá pela técnica de nome Segmentação Starlet Ótima Multinível (MLSOS), que se baseia nos resultados da MLSS e no coeficiente de correlação de Matthews (MCC) faz a comparação entre as segmentações obtidas e imagens ground truth, elegendo a melhor segmentação para a imagem de entrada. Os métodos são avaliados pelos valores de precisão, sensibilidade e exatidão. MLSS e MLSOS deram origem ao software livre Jansen-MIDAS, voltando ao uso dessas técnicas pelo usuário final. O programa foi utilizado na separação de elementos em imagens de diferentes materiais, a saber: nanoportículas de ouro em amostras de borracha natural traços de fissão em cristais de epídoto. Nessas aplicações, o método proposto apresentou exatidão maior que 87% para as imagens de teste / Abstract: Microscopies have been used for morphology evaluation of different materials structures. However, their results can be affected by several external factors. Image processing techniques can be used to attenuate these factors, improving the results. In this study we propose a method for segmentation of photomicrographs, denominated Multi-Level Startelet Segmentation (MLSS), based on the starlet wavelet transform. The choise of an optimal segmentation level is given by Multi-Level Optimal Segmentation (MLSOS), that uses MLSS results and the Matthews correlation coefficient (MCC). MCC compares the obtained segmentations and ground truth images, choosing the best segmentation for the input image. MLSS and MLSOS are evaluated using precision, recall and accuracy. Jansen-MIDAS, an open-source software from these methods, allows using MLSS and MLSOS by the end user. This software was employed in the separation of elements in images of different materials, namely gold nanoparticles in natural rubber samples and fission tracks in epidote crystals. In these applications, the proposed method presented accuracy higher than 87% for all test images / Doutor