向列液晶表面弹性能K13项的物理效应及检验方法

通过解析推导和数值计算的方法，得到了平衡态指向矢满足的微分方程和边界条件.研究了表面弹性能K13项对磁场作用下的弱锚定向列液晶盒Fréedericksz转变性质的影响.结果表明，表面弹性能K13项的存在对液晶系统的自由能有很大的影响，从而改变转变的性质，诱导液晶盒在阈值点发生一级Fréedericksz转变.给出了发生一级转变的物理条件，它除了与液晶的结构和材料有关外，还依赖于液晶表面弹性能K13项，同时给出了由此判断K13项是否存在的检验方法. 关键词： 表面弹性能K13项 弱锚定 Fréedericksz转变     

Lattice mechanical properties of some fcc f-shell metals

A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion-ion interaction, phonon dispersion curves (q-space and r-space analysis), mode Grüneisen parameters and dynamical elastic constants of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation theory for the potential while d and f-like electron is taken into account by introducing repulsive short-range Born-Mayer term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations and experimental findings is achieved which confirms the present formalism     

Stancu-Sikkema算子的点态估计

本文构造了Stancu—Sikkema算子,并利用点态光滑模研究了此算子的点态逼近正逆定理.     

Nonlinear Energy Transfer over the Wave Spectrum in Water Covered by Solid Ice

On the basis of the hydrodynamic equations for nonlinear elastic-gravity waves beneath a solid ice cover and their Hamiltonian representation, a three-wave kinetic equation for the time evolution of the wave spectrum is formulated. The properties of the kernel of the kinetic integral describing the nonlinear interactions between wave triplets are investigated. An algorithm for numerically calculating the kinetic integral is developed. The rate of nonlinear energy transfer over the wave spectrum is estimated quantitatively and its most important characteristics are found.     

New isothermal equation of state of solids applied to high pressures

In the present paper, a new two-parameter inverted equation of state (EOS) is developed which is found to be working very well in the high-pressure region. To check its success and validity, this EOS has been applied in a number of solids. The computed volume compression is found to be in very good agreement with the experimental data in the whole range of pressure in all the solids. The minimum and the maximum pressure range used in the present study is 0–320 kbar and 0–3000 kbar, respectively.     

Ab-initio simulation of elastic constants for some ceramic materials

Athermal elasticity for some ceramic materials (α-Al₂O₃, SiC (α and β phases), TiO₂ (rutile and anatase), hexagonal AlN and TiB₂, cubic BN and CaF₂, and monoclinic ZrO₂) have been investigated via density functional theory. Energy-volume equation-of-state computations to obtain the zero pressure equilibrium volume and bulk modulus as well as computations of the full elastic constant tensor of these ceramics at the experimental zero pressure volume have been performed. The present results for the single crystal elasticity are in good agreement with experiments both for the aggregate properties (bulk and shear modulus) and the elastic anisotropy. In contrast, a considerable discrepancy for the zero pressure bulk modulus of some ceramics evaluated from the energy-volume fit to the computational zero pressure volume has been observed.     

Co-Orthogonal Codes

We define, construct and sketch possible applications of a new class of non-linear codes: co-orthogonal codes, with possible applications in cryptography and parallel processing. We also describe a fast and general method for generating (non-linear) codes with prescribed dot-products with the help of multi-linear polynomials.     

小球与均质自由杆的碰撞

讨论了小球与自由杆碰撞过程中所遵从的物理规律,明确了完全非弹性碰撞过程的能量特征,指出完全非弹性碰撞后两物体不一定粘在一起共同运动的事实.     

牛顿碰撞球的解释与分析

对牛顿碰撞球的常规碰撞形式和混合联珠单球碰撞形式做了理论分析和解释.在常规碰撞时,将悬线(钓鱼线)先悬挂小球一段时间后组装仪器,可克服悬线的拉力.在混合联珠单球碰撞时,根据理论分析,选取大球和小球的质量比为27∶8时,演示效果较好.     

钢丝的切变模量与扭转角度关系

研究了钢丝的切变模量随其扭转角度变化而变化的情况,观察到扭转角大于某一角度时,切变模量趋于定值的规律,得出扭摆实验准确测量的方法.