Multiscale nondestructive characterization of coal microscopic physical structure can provide important information for coal\nconversion and coal-bed methane extraction. In this study, the physical structure of a coal sample was investigated by synchrotronbasedmultiple-\nenergy X-ray CT at three beamenergies and two different spatial resolutions. A data-constrained modeling (DCM)\napproach was used to quantitatively characterize the multiscale compositional distributions at the two resolutions. The volume\nfractions of each voxel for four different composition groups were obtained at the two resolutions. Between the two resolutions,\nthe difference for DCM computed volume fractions of coal matrix and pores is less than 0.3%, and the difference for mineral\ncomposition groups is less than 0.17%. This demonstrates that the DCM approach can account for compositions beyond the Xray\nCT imaging resolution with adequate accuracy. By using DCM, it is possible to characterize a relatively large coal sample at a\nrelatively low spatial resolution with minimal loss of the effect due to subpixel fine length scale structures.
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