第3届全国复合材料学术会议

<正> 会议于1984年11月2—7日在杭州举行,由中国宇航学会、中国航空学会和中国力学学会共同主办,全国科研、设计、生产部门和大专院校13个学院87个单位的221名代表参加了会议,大会收到学术报告312篇,接受了182篇,会前即预印了论文集,120篇论文分别在材料工艺、性能测试与应用、静动态力学性能、结构设计分析以及金属基复合材料五个组

星系磁场和星系激波演化的一种模式

本文求解了二维不定常磁流体力学方程组,从而讨论星系磁场和星系激波的起源和演化过程。初始均匀的磁场将缠卷而在星系盘中形成螺旋形的结构,其中磁场和星际气体是冻结在一起的。分析了星际磁场对形成星系激波的影响。由于磁场不是很强,它对星系激波的影响不是非常强。

高功率脉冲染料激光振荡-放大器

报道一种用倍频Nd:YAG激光纵向泵浦、双棱镜一维扩束的染料激光系统,经过二级放大,输出总效率达31%.当泵浦光为40 mJ时,得到12.2mJ、 2MW,线宽为0.18(?)的可调谐染料激光输出,重复率可达10次/秒.

使用任意非正交曲线坐标解变截面圆轴扭转问题的数值计算

<正> 1.基本方程及其数值求解由于讨论的是轴对称问题,因此取柱坐标系中的θ坐标为任意曲线坐标系(q~1,q~2,q~3)中的q~2坐标,在轴纵剖面Z—R平面上取任意非正交曲线坐标q~3和q~1,则变截面圆轴扭转问题以无量纲应力函数ψ表达的求解方程为:

An experimental-study of the bending behavior of call hybrid composites

The bending behavior and damage characteristics of CALL (Carbon fiber/epoxy/AL Laminate) hybrid composites have been studied by moire interferometry. The shear strain distribution along the cross-section and the forms of damage of bending beams are obtained. The results show that the magnitude of the shear strain in a carbon/epoxy layer is obviously larger than that in a corresponding aluminum layer and the shear strain distribution of a CFRP layer along the cross-section conforms basically to a parabolic distribution curve, as for the shear strain distribution in aluminum layers along the cross-section. Shear damage, either in the interfaces or in carbon-fiber/epoxy laminae, and tensile failure of CFRP laminae in the tension surface represent, respectively, the damage forms of the longitudinal and transverse bending specimen.

Phase relaxation model for 2-phase flows

A phase relaxation model (PRM) for 2-phase flows is presented in this paper on the basis of three principal assumptions. The basic equations for PRM arc derived from the Boltzmann equations for gas-partlcle mixture, The general characteristics and solving process of the PRM's basic equations are also presented and discussed. Many terms in the PRM's basic equations contain a factor ε= ρgρp/ρg+ρp2 which is an intrinsic small parameter for 2-phase mixture, with ρg and ρp being respectively the densities of gas and particle phases.This makes it possible to simplify the computation of the PRM's basic equations. The model is applied to for example, studying file steady propagation of shock waves in gas-particle mixture. The analysis shows that with an increase of shock wave strength the relaxation process behind a gasdynamics shock front becomes a kind of dynamics relaxation instead of the standard exponential relaxation process. A method of determining experimentally the velocity and tem...更多perature relaxation rates (or times) of gas-particle flows is suggested and analyzed.

客运架空索道系统动力特性分析方法

客运架空索道系统的固有频率与模态是衡量索道系统固有动力特性的重要指标，固有频率的大小直接关系到结构在各种不同的激励条件下是否会发生动力放大效应与共振。文中首先解决索道系统分析中的有限元建模问题，包括典型柔性索道的模型状态，然后利用ANSYS程序的子空间迭代法求出结构最低各阶的特征值与特征向量，并计算出三种工况下的前40阶固有频率与振动模态，为客运架空索道系统的动力特性分析提供有效的计算方法。

Numerical Simulation of R-M Instability

In order to capture shock waves and contact discontinuities in the field and easy to program with parallel computation a new algorithm is developed to solve the N-S equations for simulation of R-M instability problems. The method with group velocity control is used to suppress numerical oscillations, and an adaptive non-uniform mesh is used to get fine resolution. Numerical results for cylindrical shock-cylindrical interface interaction with a shock Mach number Ms=1.2 and Atwood number A=0.818, 0.961, 0.980 (the interior density of the interface/outer density p(1)/p(2) = 10, 50, 100, respectively), and for the planar shock-spherical interface interaction with Ms=1.2 and p(1)/p(2) = 14.28are presented. The effect of Atwood number and multi-mode initial perturbation on the R-M instability are studied. Multi-collisions of the reflected shock with the interface is a main reason of nonlinear development of the interface instability and formation of the spike-bubble structures In simulation with double mode perturbation vortex merging and second instability are found. After second instability the small vortex structures near the interface produced. It is important factor for turbulent mixing.

Rarefied gas dynamics: fundamentals, simulations and micro flows

Adiabatic shear localization: occurrence, theories, and applications

燃烧物理学基础

溶菌酶晶体生长过程中的扩散传质问题

采用Mach-Zehnder干涉测量系统与图象处理系统相结合实时观测溶菌酶蛋白质晶体生长过程中的流体动力学现象,对汽相扩散法溶菌酶蛋白质晶体生长过程进行了研究,观测到溶菌酶晶体生长时晶体周围存在的干涉条纹.分析了晶体生长时的重力沉降效应和溶质扩散过程.实验结果表明,该生长过程中的流体物理特征直接影响了生长晶体的晶面.根据实验结果,给出对蛋白质晶体生长过程流体物理现象的讨论。 

Alignment of nanoparticles formed on the surface of 6H-SiC crystals irradiated by two collinear femtosecond laser beams

Nanoripples with periods of 150 and 80 nm are formed on the surface of 6H-SiC crystals irradiated by the p-polarized 800 nm and the s-polarized 400 nm femtosecond lasers, respectively. When both of the two collinear laser beams focus simultaneously on the sample surface, nanoparticles are formed on the whole ablation area, and they array in parallel lines. We propose and confirm that the second harmonics in the sample surface excited by the incident lasers plays an important role in the formation of nanostructures.

Nonlinear X-wave formation and conical emission at different powers of a femtosecond laser pulse in water

Nonlinear X-wave formation at different pulse powers in water is simulated using the standard model of nonlinear Schrodinger equation (NLSE). It is shown that in near field X-shape originally emerges from the interplay between radial diffraction and optical Kerr effect. At relatively low power group-velocity dispersion (GVD) arrests the collapse and leads to pulse splitting on axis. With high enough power, multi-photon ionization (NIPI) and multi-photon absorption (MPA) play great importance in arresting the collapse. The tailing part of pulse is first defocused by MPI and then refocuses. Pulse splitting on axis is a manifestation of this process. Double X-wave forms when the split sub-pulses are self-focusing. In the far field, the character of the central X structure of conical emission (CE) is directly related to the single or double X-shape in the near field. (c) 2007 Elsevier B.V. All rights reserved.