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Descripción
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| This study examines the influence of the binarization threshold used to interpret 3D grey images acquired by X-ray computed tomography of a soil at different bulk densities. One objective was to generate criteria for choosing the optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation. The study also attempts to identify relationships between soil physical properties, density, porosity and connectivity. The starting point was the outputs of the simulation of 40000 particles following a directed random walk algorithms in soils with densities from 1.2 to1.6 (Mg/m3) and up to 7 thresholds for each image. These data consisted of 31 files containing the simulated end points of the 40000 random walks. MATLAB software was used for computing the frequency matrix of the number of particles arriving at every end point of the random walks and their 3D representation. The relationships identified were: the higher the bulk density the lower the porosity and the fewer the final positions of the 40000 particles; each soil sample shows different sensibility to the threshold; a higher threshold always reflects a higher porosity, greater connectivity and greater number of final positions at greater depth, regardless of density (Fig.1). Soil structure and connectivity between pores determines the 3D distribution of final positions with at least one fluid particle; and the higher the threshold, the lower the influence of the structure. A criterion to select the threshold was identified: final positions were divided in two subgroups, cg1 (positions with frequency of the number of particles received greater than the median) and cg2 (frequency lower or equal to median). Images with maximum difference between the Z coordinate of the center of gravity of both subgroups were selected as those with optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation, allowing us for comparing the percolation of soils with different bulk density. | |
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Internacional
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Si |
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Nombre congreso
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The American Geophysical Union Fall Meeting |
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Tipo de participación
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960 |
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Lugar del congreso
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San Francisco (California) |
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Revisores
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Si |
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ISBN o ISSN
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00000000 |
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DOI
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Fecha inicio congreso
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03/12/2011 |
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Fecha fin congreso
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07/12/2011 |
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Desde la página
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624 |
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Hasta la página
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624 |
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Título de las actas
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ABSTRACT FINAL ID: EP41C-0624; AGU Fall Meeting Database http://www.agu.org/meetings/abstract_db.shtml |