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Simulação com o código GEANT4 de medida de espessura de revestimento metálico em metal por XRF / GEANT4 simulation of measure thickness of metallic coating on metal by XRFIevgeniia Ievsieieva 17 September 2012 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Nesta dissertação são apresentados resultados de simulações Monte Carlo de
fluorescência de raios X (XRF), utilizando o programa GEANT4, para medidas de
espessura de revestimento metálico (Ni e Zn) em base metálica (Fe). As simulações
foram feitas para dois tamanhos de espessura para cada metal de revestimento, (5μm e
10μm), com passos de 0,1 μm e 0,001 μm e com 106 histórias. No cálculo da espessura
do revestimento foram feitas as aproximações de feixe de raios X monoenegético, com a
análise da transmissão apenas da energia do K-alfa e para uma geometria compatível com
um sistema real de medição (ARTAX-200). Os resultados mostraram a eficiência da
metodologia de simulação e do cálculo da espessura do revestimento, o que permitirá
futuros cálculos, inclusive para multirevestimentos metálicos em base metálica. / This dissertation is presented results of x-ray fluorescence (XRF) Monte Carlo
simulations) using GEANT4 for metallic coating (Ni and Zn) thickness determination on
metallic base (Fe). The simulations were made for two values of coating thickness for
each covering (5 μm and 10 μm), with steps of 0.1 μm and 0.001 μm, and with 106
stories. The monoenergetic x-ray approach was used assuming the transmission of only
K-alpha line. The experiment and geometry was similar to the real system of
measurement (ARTAX-200 ). The results showed the efficiency of the simulation
methodology, as well as the ability to measure the thickness of coating by XRF. Thus, a
continuation of this study for multilayer metal coating could be promising.
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Simulação com o código GEANT4 de medida de espessura de revestimento metálico em metal por XRF / GEANT4 simulation of measure thickness of metallic coating on metal by XRFIevgeniia Ievsieieva 17 September 2012 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Nesta dissertação são apresentados resultados de simulações Monte Carlo de
fluorescência de raios X (XRF), utilizando o programa GEANT4, para medidas de
espessura de revestimento metálico (Ni e Zn) em base metálica (Fe). As simulações
foram feitas para dois tamanhos de espessura para cada metal de revestimento, (5μm e
10μm), com passos de 0,1 μm e 0,001 μm e com 106 histórias. No cálculo da espessura
do revestimento foram feitas as aproximações de feixe de raios X monoenegético, com a
análise da transmissão apenas da energia do K-alfa e para uma geometria compatível com
um sistema real de medição (ARTAX-200). Os resultados mostraram a eficiência da
metodologia de simulação e do cálculo da espessura do revestimento, o que permitirá
futuros cálculos, inclusive para multirevestimentos metálicos em base metálica. / This dissertation is presented results of x-ray fluorescence (XRF) Monte Carlo
simulations) using GEANT4 for metallic coating (Ni and Zn) thickness determination on
metallic base (Fe). The simulations were made for two values of coating thickness for
each covering (5 μm and 10 μm), with steps of 0.1 μm and 0.001 μm, and with 106
stories. The monoenergetic x-ray approach was used assuming the transmission of only
K-alpha line. The experiment and geometry was similar to the real system of
measurement (ARTAX-200 ). The results showed the efficiency of the simulation
methodology, as well as the ability to measure the thickness of coating by XRF. Thus, a
continuation of this study for multilayer metal coating could be promising.
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The Development of Image Processing Algorithms in Cryo-EMRui Yan (6591728) 15 May 2019 (has links)
Cryo-electron microscopy (cryo-EM) has been established as the leading imaging technique for structural studies from small proteins to whole cells at a molecular level. The great advances in cryo-EM have led to the ability to provide unique insights into a wide variety of biological processes in a close to native, hydrated state at near-atomic resolutions. The developments of computational approaches have significantly contributed to the exciting achievements of cryo-EM. This dissertation emphasizes new approaches to address image processing problems in cryo-EM, including tilt series alignment evaluation, simultaneous determination of sample thickness, tilt, and electron mean free path based on Beer-Lambert law, Model-Based Iterative Reconstruction (MBIR) on tomographic data, minimization of objective lens astigmatism in instrument alignment and defocus and magnification dependent astigmatism of TEM images. The final goal of these methodological developments is to improve the 3D reconstruction of cryo-EM and visualize more detailed characterization.
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