Secondary plasmon resonance in graphene nanostructures

The plasmon characteristics of two graphene nanostructures are studied using time-dependent density functional theory (TDDFT). The absorption spectrum has two main bands, which result from π and σ + π plasmon resonances. At low energies, the Fourier transform of the induced charge density maps exhibits anomalous behavior, with a π phase change in the charge density maps in the plane of the graphene and those in the plane 0.3 ? from the graphene. The charge density fluctuations close to the plane of the graphene are much smaller than those above and beneath the graphene plane. However, this phenomenon disappears at higher energies. By analyzing the electronic properties, we may conclude that the restoring force for the plasmon in the plane of the graphene does not result from fixed positive ions, but rather the Coulomb interactions with the plasmonic oscillations away from the plane of the graphene, which extend in the surface-normal direction. The collective oscillation in the graphene plane results in a forced vibration. Accordingly, the low-energy plasmon in the graphene can be split into two components: a normal component, which corresponds to direct feedback of the external perturbation, and a secondary component, which corresponds to feedback of the Coulombic interaction with the normal component.     

瀑布沟水电站库首右岸深部裂缝成因分析

水电工程常常建在高山峡谷地带,其天然岸坡通常由坡面向内有一个强卸荷带和弱卸荷带以及相应的强风化和弱风化带,内侧则为完整新鲜的岩石。对涉及的工程岸坡在正常卸荷带以内发育的一系列张性破裂或破裂带,称之为“深拉裂缝”。瀑布沟水电站库首右岸存在两个拉裂变形体,通过对其岸坡深部拉裂缝空间发育分布、变形特征的考察,综合分析造成深部裂缝发育规律与变形特征的因素。在此基础上提出,库首右岸深部拉裂缝是岸坡快速卸荷条件下浅表生改造的产物,其形成时期相当于河谷由宽谷深切为峡谷这一转换时期。     

Two-dimensional problem of natural convection in a rectangular domain with local heating and heat-conducting boundaries of finite thickness

Time-dependent natural convective heat transfer in a closed rectangular domain with heat-conducting boundaries of finite thickness is investigated numerically in the case of local heating on the inner side of the vertical wall. Convection-radiation heat transfer takes place on one of the outer boundaries of the solution domain. The inhomogeneous temperature distribution in the gas cavity is clearly manifested when the Grashof number Gr > 10⁶. Circulation flows can be distinguished in various zones of the solution domain on the basis of the numerical investigations carried out. These flows are due to the effect of the heat-release source, the propagation of perturbations induced by elements of the rigid wall, and the dynamics of conductive heat transfer in the solid material. The scales of the effect of the Grashof number on the hydrodynamic and thermal characteristics are indicated.     

One-dimensional consolidation of layered soils with impeded boundaries under time-dependent loadings

On the basis of Terzaghi‘s one-dimensional consolidation theory, the variation of effective stress ratio in layered saturated soils with impeded boundaries under timedependent loading was studied. By the method of Laplace transform, the solution was presented. Influences of different kinds of cyclic loadings and impeded boundaries conditions were discussed. Through numerical inversion of Laplace transform, useful illustrations were given considering several common time-dependent loadings. Pervious or impervious boundary condition is just the special case of the problem considered here. Compared with average index method, the results from the method illustrated are more accurate.     

THE COMPACTION OF TIME-DEPENDENT VISCOUS GRANULAR MATERIALS CONSIDERING INERTIAL FORCES

In the present paper, compactions of time-dependent viscous granular materials are simulated step by step using the automatic adaptive mesh generation schemes. Inertial forces of the viscous incompressible aggregates are taken into account. The corresponding conservation equations, the weighted-integral formulations, and penalty finite element model are investigated. The fully discrete finite element equations for the simulation are derived. Polygonal particles of aggregates are simplified as mixed three-node and four-node elements. The automatic adaptive mesh generation schemes include contact detection algorithms, and mesh upgrade schemes. Solutions of the numerical simulation are in good agreement with some results from literatures. With minor modification, the proposed numerical model can be applied in several industries, including the pharmaceutical, ceramic, food, and household product manufacturing.     

岩石裂纹演化及其力学特性的研究进展

综述评介了岩石裂纹（缺陷）演化及其力学特性研究的近期进展．其内容包括：微细观裂纹演化及其力学特性,时间相关性,裂纹扩展与岩石破坏,并结合某些工程问题进行了讨论．     

Local energy decay for the wave equation with a nonlinear time-dependent damping

This article addresses a wave equation on a exterior domain in ? ^d (d odd) with nonlinear time-dependent dissipation. Under a microlocal geometric condition we prove that the decay rates of the local energy functional are obtained by solving a nonlinear non-autonomous differential equation     

Arrangement transformation approach to state-to-state quantum reactive scattering H + DH→DH + H, HH + D

Arrangement transformation approach (ATA) for doing state-to-state quantum reactive scattering calculations of atom-diatom systems is given. The state-to-state results of H + DH on ISTH potential energy surface are presented, and it can be deduced from the results that the ATA method can be used for the system with more than three atoms. Project supported by the National Natural Science Foundation of China (Grant No. 19774038) and Shandong Science Foundation (Grant No. Y96A08012).