Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.
The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shells of both Fe2＋ and Fe3＋ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2＋ and 1.96 for Fe3＋, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2＋ aqueous solution. The corresponding X-ray absorption near edge fine structure （XANES） calculation successfully reproduces all features in the XANES spectra in Fe2＋ and Fe3＋ aqueous solution. A feature that is located at energy 1 eV higher than the white line （WL） in an Fe3＋ aqueous solution may be assigned to the contribution of the charge transfer.
The study has analyzed the relationship between the water-drainage sluice process of reservoir, stress triggers and shadows of earthquake and porosity variability of fault slip zone. First, the pore pressure, pressure gradient, viscous stress and Reynolds stress to reservoir-earthquake fault slip problem are analyzed, and these are un-negligible factors of the extended coulomb failure stress under ultra-high temperature and pressure condition. Second, the porosity tensor and permeability tensor are studied, the relationship between Zipingpu reservoir and Longmenshan slip has been analyzed, and the extended viscous stress and Reynolds stress as function of time and infiltration process are obtained. Last, some primary conclusions about the flow-solid coupled facture mechanism to the Zipingpu reservoir and Longmenshan slip problem are presented, which can help understand the flow-solid coupled facture mechanism of reservoir-coseismic fault slip problem.
ZHU BoJingLIU ChangSHI YaoLinSUN DongShengZHANG Kai
We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.
