We propose a method for mOdeling azimuthal AVO responses from a fractured i reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the con...We propose a method for mOdeling azimuthal AVO responses from a fractured i reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the contrast in impedance and anelasticity i across interfaces, the intemal anisotropic propagation, the dispersion and attenuation along i the wave path, and tuning and interference. The results suggest that for large angles of incidence, the velocity dispersion and attenuation increase the amplitudes of PP waves from the top and decrease those from the bottom. For azimuthal responses at specific angles of incidence, the reflected wavetrains of PP waves tend to have longer duration with increasing azimuth. In contrast, model-converted PSV and PSH reflections show stable azimuthal features and are less affected by the reflector thickness. The amplitudes of PSV reflections increase with increasing azimuth; moreover, the waves have no reflection energy at 0° and 90° azimuth and maximum amplitude at 45° azimuth.展开更多
Numerous experimental studies reveal that the mechanical and deformational behaviors of sands are dependent on the combined effect of void ratio and stress. To predict this complex behavior of sands, a hypo-elastic mo...Numerous experimental studies reveal that the mechanical and deformational behaviors of sands are dependent on the combined effect of void ratio and stress. To predict this complex behavior of sands, a hypo-elastic model is developed based on the cross-anisotropic elasticity model, which involves four parameters: bulk module, tangent Young's module, volume deformation coefficient and Poisson ratio. A parameter defined as virtual peak deviatoric stress dependent on state parameter is introduced into hyperbolic stress strain relationship to determine tangent Young's module. In addition, an existing fitting equation for isotropic compression curves and an existing dilatancy equation, which can consider the effect of state of sands, are employed to determine bulk module and volume deformation coefficient. Thirteen model constants are involved in the proposed model, the values of which are fixed for a sand over a wide range of initial void ratios and initial confining pressures. Well known experimental data for drained and undrained triaxial compression tests of Toyoura sand are successfully modeled.展开更多
Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the fea...Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the feature that its strength strongly depends on the medium stiffness surrounding the adhesion.In this paper,we demonstrate in a stochastic-elasticity framework that a type of materials with linearly graded elastic modulus can be designed to achieve "equal load sharing" and enhanced cooperative rebinding among interfacial molecular bonds.Upon modulus gradation,multiple molecular bonds can be elastically decoupled but statistically cooperative.In general,uniform molecular adhesion can be accomplished by two strategies:homogeneous materials with sufficient stiffness higher than a threshold or heterogeneous materials satisfying the criterion on modulus gradation.These results not only provide a theoretical principle for possible applications of functionally graded materials in quantitatively controlling cell-matrix adhesion,but also have general implications on adhesion between soft materials mediated by specific molecular binding.展开更多
基金sponsored by the National Natural Science Foundation of China(under Grant Nos.41404090 and U1262208
文摘We propose a method for mOdeling azimuthal AVO responses from a fractured i reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the contrast in impedance and anelasticity i across interfaces, the intemal anisotropic propagation, the dispersion and attenuation along i the wave path, and tuning and interference. The results suggest that for large angles of incidence, the velocity dispersion and attenuation increase the amplitudes of PP waves from the top and decrease those from the bottom. For azimuthal responses at specific angles of incidence, the reflected wavetrains of PP waves tend to have longer duration with increasing azimuth. In contrast, model-converted PSV and PSH reflections show stable azimuthal features and are less affected by the reflector thickness. The amplitudes of PSV reflections increase with increasing azimuth; moreover, the waves have no reflection energy at 0° and 90° azimuth and maximum amplitude at 45° azimuth.
基金Project(2010BC732101)supported by the National Basic Research Program of China
文摘Numerous experimental studies reveal that the mechanical and deformational behaviors of sands are dependent on the combined effect of void ratio and stress. To predict this complex behavior of sands, a hypo-elastic model is developed based on the cross-anisotropic elasticity model, which involves four parameters: bulk module, tangent Young's module, volume deformation coefficient and Poisson ratio. A parameter defined as virtual peak deviatoric stress dependent on state parameter is introduced into hyperbolic stress strain relationship to determine tangent Young's module. In addition, an existing fitting equation for isotropic compression curves and an existing dilatancy equation, which can consider the effect of state of sands, are employed to determine bulk module and volume deformation coefficient. Thirteen model constants are involved in the proposed model, the values of which are fixed for a sand over a wide range of initial void ratios and initial confining pressures. Well known experimental data for drained and undrained triaxial compression tests of Toyoura sand are successfully modeled.
基金supported by the Start-up Funding from Young Thousand-Talent Program of Chinathe Fundamental Research Funds for Central Universities (Grant No. 2011XZZX002)the National Natural Science Foundation of China (Grant No. 11072273)
文摘Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the feature that its strength strongly depends on the medium stiffness surrounding the adhesion.In this paper,we demonstrate in a stochastic-elasticity framework that a type of materials with linearly graded elastic modulus can be designed to achieve "equal load sharing" and enhanced cooperative rebinding among interfacial molecular bonds.Upon modulus gradation,multiple molecular bonds can be elastically decoupled but statistically cooperative.In general,uniform molecular adhesion can be accomplished by two strategies:homogeneous materials with sufficient stiffness higher than a threshold or heterogeneous materials satisfying the criterion on modulus gradation.These results not only provide a theoretical principle for possible applications of functionally graded materials in quantitatively controlling cell-matrix adhesion,but also have general implications on adhesion between soft materials mediated by specific molecular binding.
