压电功能梯度板自由振动的三维解

基于三维弹性理论和压电理论,导出了有限长矩形压电功能梯度板的动力学方程及相应的边界条件,并用幂级数展开法进行了求解.得到了压电功能梯度板自由振动的三维精确解公式,求解了自由振动的固有频率,并分析了压电系数的梯度变化对不同电学边界条件下压电板的自由振动频率的影响.结果可用于校核不同的近似理论及理解压电结构的动态行为.     

DYNAMIC BEHAVIOR OF SEVERAL CRACKS IN FUNCTIONALLY GRADED STRIP SUBJECTED TO ANTI-PLANE TIME-HARMONIC CONCENTRATED LOADS

This paper contains a theoretical formulations and solutions of multiple cracks sub- jected to an anti-plane time-harmonic point load in a functionally graded strip. The distributed dislocation technique is used to construct integral equations for a functionally graded material strip weakened by several cracks under anti-plane time-harmonic load. These equations are of Cauchy singular type at the location of dislocation, which are solved numerically to obtain the dislocation density on the faces of the cracks. The dislocation densities are employed to evaluate the stress intensity factor and strain energy density factors （SEDFs） for multiple cracks with differ- ent configurations. Numerical calculations are presented to show the effects of material properties and the crack configuration on the dynamic stress intensity factors and SEDFs of the functionally graded strip with multiple curved cracks.     

激光等离子体中横场坍塌形成的密度空穴

强激光与等离子体相互作用时在临界面附近发生强烈的波-波、波-粒相互作用,原来均匀分布的横等离子体波在调制不稳定作用下,发生坍塌破碎,局域化的高强度横等离激元通过有质动力排斥粒子形成密度空穴,同时诱发出高强度的低频磁场.采用从伏拉索夫方程和麦克斯韦方程组导出的非线性控制方程,数值模拟了非静态极限情况下无碰撞等离子体中密度空穴和低频磁场的演化过程.     

Reflective Fourier CGH with 16 phase levels

This paper reports design and fabrication of reflective Fourier computer generat-ed hologram(CGH) with 16 phase levels.This CGH converts a single beam to a 5×5 beamarray.The measured diffraction efficiency is 76.16％. The size of the CGH is 10mm×10mm.     

非线性二阶中立型微分方程的振动性

考虑中立型微分方程我们建立了方程(1)的若干振动准则。这些结果适用于强超线性和强次线性中立型微分方程,且当p(t)≡0时仍然成立。     

Laser Accelerated, High Quality Ion Beams

Intense beams of protons and heavy ions have been observed in ultra-intense laser-solid interaction experiments. Thereby, a considerable fraction of the laser energy is transferred to collimated beams of energetic ions (e.g. up to 50 MeV protons; 100 MeV fluorine), which makes these beams highly interesting for various applications. Experimental results indicate very short pulse duration and an excellent beam quality, leading to beam intensities in the TW range. To characterize the beam quality and its dependence on laser parameters and target conditions, we performed experiments at several high-power laser systems. We found a strong dependence on the target rear surface conditions allowing to tailor the ion beam by an appropriate target design. We also succeeded in the generation of heavy ion beams by suppressing the proton amount at the target surface. We will present recent experimental results demonstrating a transverse beam emittance far superior to accelerator-based ion beams. Finally, we will discuss the prospect of laser-accelerated ion beams as new diagnostics in laser-solid interaction experiements. Special fields of interest are proton radiography, electric field imaging, and relativistic electron transport inside the target.     

有常秩的投射模

本文定义更具一般性的模(未必是有限生成投射模)的常秩的概念,并证明了如果M有常秩n,∧~n M是有限生成的,则M是有限生成的,还证明了若M是有常秩n的投射模,则M一定是有限生成的。     

Conjugacy Separability of Descending HNN-Extensions of Finitely Generated Abelian Groups

It is proved that an arbitrary descending HNN-extension of a finitely generated Abelian group is conjugacy separable.     

A Levinson-like algorithm for symmetric strongly nonsingular higher order semiseparable plus band matrices

In this paper, we will derive a solver for a symmetric strongly nonsingular higher order generator representable semiseparable plus band matrix. The solver we will derive is based on the Levinson algorithm, which is used for solving strongly nonsingular Toeplitz systems.     

关于m-增生算子的扰动方程

在实Banach空间X中考察非线性方程T0x Tx CxЗp，其中T为多值m-增生算子。T0为强增生算子，C为凝聚算子，p∈X。