宏观速度对电弧螺旋不稳定性影响的数值分析

采用抛物型电导率和与时间有关的线性微扰理论,给出了有宏观速度存在的热势分布(温度分布)、稳定性条件以及不稳定性增长率等定量结果。     

THE REMAINDER－EFFECT ANALYSIS OF FINITE DIFFERENCE SCHEMES AND THE APPLICATIONS

ＴＨＥＲＥＭＡＩＮＤＥＲ－ＥＦＦＥＣＴＡＮＡＬＹＳＩＳＯＦＦＩＮＩＴＥＤＩＦＦＥＲＥＮＣＥＳＣＨＥＭＥＳＡＮＤＴＨＥＡＰＰＬＩＣＡＴＩＯＮＳＬｉｕＲｕ－ｘｕｎ（刘儒勋）ＺｈｏｕＺｈａｏ－ｈｕｉ（周朝晖）（Ｄｅｐｔ．ｏｆＭａｔｈ．Ｕｎｉｖｅｒｓｉｔｙｏ...     

数值模拟二维高速碰撞问题的拉格朗日任意三角形网格有限体积法

描述了一个数值模拟二维高速碰撞问题的拉格朗日任意三角形网格有限体积法,方法考虑了材料的弹性和塑性性质。文中给出两个计算例题。     

新型高活性催化剂乙烯气相聚合的研究(Ⅱ)──改性剂、预聚合和聚合条件对乙烯气相聚合的影响

研究了新型高活性乙烯气相聚合催化剂TiCl₄/MgCl₂/ZnCl₂/SiCl₄/醇/Al(i-Bu)₃体系中不同醇、不同C₂H₅OH/Ti摩尔比和正丁醚对聚合反应及产物颗粒形态的影响。研究了预聚合反应及乙烯气相聚合反应规律。用扫描电镜和图象分析对催化剂、预聚物及聚合产物的形态和颗粒分布的研究结果表明:新型高活性催化剂和经预聚合制得的乙烯气相聚合物的颗粒形态类似球形,颗粒长短轴比值和大小粒径比值相近。     

骨断裂力学概述

本文涉及近年来骨断裂力学的发展成果.对建立在张开型和剪切型断裂能基础上的方法作了回顾,并讨论了密度、试件厚度和裂纹速度对骨断裂的影响.最后简述了人股骨的试验研究.      

Formulae of force at a point in the interior of a half space with shear modulus linearly varied with depth

According to a lemma and an assumption, this paper prexenis formulae of force at a point in the interior of a half space with Poisson’s ratio v = constant and shear modulus G linearly varied with depth. These formulae can be used as an approximate basic solution when the integral equation method is employed for the analysis of piles and other geotechnical engineering problems.     

超声光栅测液体声速原理和实验

本文对用超声驻波自身像法和超声光栅衍射法测定液体声速的原理进行了分析,并介绍了其实验方法     

Kinematic segregation of granular mixtures in sandpiles

We study the segregation of granular mixtures in two-dimensional silos using a recently proposed set of coupled equations for surface flows of grains. We study the thick flow regime, where the grains are segregated in the rolling phase. We incorporate this dynamical segregation process, called kinematic sieving, free-surface segregation or percolation, into the theoretical formalism and calculate the profiles of the rolling species and the concentration of grains in the bulk in the steady state. Our solution shows the segregation of the mixture with the large grains being found at the bottom of the pile in qualitative agreement with experiments. Received: 6 July 1998 / Revised and Accepted: 13 August 1998     

Spatially Dependent Kinetics of Electrons and Excited Atoms in the Column Plasma of a He–Xe dc Discharge

The radially varying kinetics of electrons and excited atoms in the cylindrical axially homogeneous positive column of a dc glow discharge in a gas mixture of helium and 2% xenon was studied. The experimental investigations comprise the radially resolved measurements of the isotropic part of the electron velocity distribution function (EVDF) using a single-probe technique and of the densities of atoms in the lower excited states by using a laser diode absorption method. The theoretical investigations are based on the solution of the space-dependent kinetic equation for the EVDF and the balance equations of excited gas atoms. Besides a strict solution, various simplified treatments of the electron kinetics as the conventional homogeneous approach and the nonlocal approach have been applied. The electron kinetic behavior in the helium–xenon column plasma changes remarkably with increasing helium gas pressure from a distinctly nonlocal behavior at a low pressure of 100 Pa to a nearly local behavior at a medium pressure of 600 Pa.     

固—液耦合Timoshenko管道的稳定性分析

根据Ｈａｍｉｌｔｏｎ原理的固－液耦合振同分方程用幂级数法计算了Ｔｉｍｏｓｈｅｎｋｏ管道的固有频率和临界流速。给出了管道前三阶固有频率－流速的关系曲线,分析了转动惯量对该输流管道的稳定特性的影响。计算结果表明,转动一对两端简支的固－液合Ｔｉｍｏｓｈｅｎｋｏ管道的静力失稳没有影响,但对其频率特性和动力失稳有影响。