Two-dimensional shape and size characterization of polygonally symmetric particles (original) (raw)
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The probability density function of projected area and the joint probability density function of projected perimeter and area have been evaluated for convex solid particles whose shapes are ellipsoidal, cylindrical and conical. This provides a starting point for a study of how calculated two-dimensional projections on a plane of threedimensional solids may be used to infer the three-dimensional particle shape and size. This information, for comparison with experimental measurements and supplemented by 'snapshot' views, could aid particle identification by eye or instrument.
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Journal of Quantitative Spectroscopy and Radiative Transfer, 2002
We investigate to what extent the full Stokes scattering matrix of an ensemble of wavelength-sized particles with complex shapes can be modeled by employing an ensemble of simple model shapes, such as spheres, spheroids, and circular cylinders. We also examine to what extent such a simple-shape particle model can be used to retrieve meaningful shape information about the complex-shaped particle ensemble. More speciÿcally, we compute the Stokes scattering matrix for ensembles of randomly oriented particles having several polyhedral prism geometries of di erent sizes and shape parameters. These ensembles serve as proxies for size-shape mixtures of particles containing several di erent shapes of higher geometrical complexity than the simple-shaped model particles we employ. We ÿnd that the phase function of the complex-shaped particle ensemble can be accurately modeled with a size distribution of volume-equivalent spheres. The diagonal elements of the scattering matrix are accurately reproduced with a size-shape mixture of spheroids. A model based on circular cylinders accurately ÿts the full scattering matrix including the o-diagonal elements. However, the modeling results provide us with only a rough estimate of the e ective shape parameter of the complex-shaped particle ensemble to be modeled. They do not allow us to infer detailed information about the shape distribution of the complex-shaped particle ensemble.
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