DEFECT CORRECTION FOR FINITE ELEMENT GRADIENT

A defect correction scheme of fourth order accuracy for linear finite element gradient is proposed in this note.This extends the Rannacher's scheme for finite element solution to gradient and can compete with superconvergence from quadratic elements.     

具非负Ricci曲率流形上的线性增长的调和函数

设M是Ricci曲率非负的完备黎曼流形,U表示M上的线性增长的调和函数所构成的线性空间,得到U的维数的最佳话计是 dim U≤l 1≤2n 2其中l是M的端的个数,n=dim M.这个结果部分地解决了丘成桐的猜测。     

电脉冲除冰系统线圈的设计及优化

对电脉冲除冰系统线圈和铝板之间产生冲击力进行研究。从能量传递的角度对系统放电过程进行数值计算,在计算峰值电流和峰值时间时考虑线圈感抗、电容容抗和导线电阻等因素。峰值电流计算结果导入二维有限元模型,通过改变线圈与铝板的参数对冲击力进行分析。搭建电脉冲除冰系统力学实验台,进行冲击力实验,分析影响冲击力峰值的因素。对所得冲击力进行分析并与仿真结果进行对比。得出一种有效的平板线圈设计优化方法。     

代数类实验课程任务驱动式教学研究与实践

研究如何利用任务驱动式教学法对高等学校代数类的实验课程进行教学,提高学生学习兴趣以及分析和解决问题的能力.通过教学实践,清晰、生动的说明,将任务驱动式教学法引入代数类实验课程的教学是有效的.     

“两墙合一”中地下连续墙与桩基处于不同土层时地基沉降有限元分析

通过一个位于上海软土地基上典型的"两墙合一"工程实例,运用有限元软件分析了当地下连续墙和桩基处于不同压缩模量土层时,地基基础在上部荷载作用下的变形差异;以及此变形差异会对结构的应力、变形产生的影响,最后提出改进措施。     

子对,交换亏群与特殊p-块

本文首先研究了有限群的子对的一些性质,由此给出亏群交换的等价条件.基于子对成链的条件,文中最后定义了几种特殊的p-块,并给出相关的一些结论.     

全膜润滑金属成形工艺的有限元仿真分析

全膜润滑的金属成形的数值分析非常少,这主要是由于求解润滑模型的方法只适用于轴对称和平面应变情况.因此,本文中提出了全润滑膜润滑和金属成形有限元法相结合的统一方法,适用于稳态和非稳态的三维成形工艺,也适用于轴对称和平面应变情况.而一个轴对称拉深成形被用来做一个样板实验.该法大幅度增加了仿真的精度.而理论计算的润滑膜厚与实测值相一致,这也证明本文的方法优于其它方法.     

地下工程土体三维非线性流变有限元分析

简述了地下工程中土体三维非线性流变问题的有限元法,建立了基于三维非线性流变的时步-粘弹-粘塑性初应变方法,在此基础上研编了适应性较强的三维非线性流变有限元法分析软件──TDNRAS,并用工程实例分析了地下工程土体的三维非线性流变性态．     

撞击损伤过程的有限元分析

运用连续介质损伤力学理论．在接触-冲击问题中引入由Lemaitre提出的一个各向同性韧性损伤模型,通过有限元法来计算、反映接触-冲击过程中材料性能的劣化程度和进程,并以有限单元间的分离来模拟诸如“穿甲”等一类包含材料破碎的接触-冲击过程．为在接触-冲击问题中考虑损伤的影响,提供了一般的方法．     

Finite element models and molecular dynamic simulations for studying the response of mast cell under mechanical activation

In micropipette aspiration experiment, increasing mechanical stress applied to cell membrane induced degranulation of mast cell as well as a current that could be inhibited by an inhibitor, which is specific for the transient receptor potential vanilloid （TRPVs） channels. To determine the sensitivity of TRPVs to membrane strain and tension, and to gain new insights into the activation mechanism of TRPVs, finite element models of mast cell and molecular dynamic simulations of human aquaporin-1 are presented. During the finite element simulations, the cell membrane sustained to micropipette aspiration was simulated, and the strain distribution along membrane thickness direction was obtained. Besides, combining the finite element models of osteoblast aspirated into micro- pipette and other compared models, we examined the relationship between cell mechanical stimulations and mechanical attributes and presented a new perspective to determine the cell equivalent elastic modulus. Consid- ering the indetermination of TRPV crystal structure, human aquaporin-1, one kind of the channel membrane proteins, substituting for TRPV, has been studied with molecular dynamic （MD） simulations, under different external lateral tensions which have been obtained in mast cell finite ele- ment simulations, to investigate the mechanical stimulation effects on the membrane channels. The simulations show that human aquaporin-1 undergoes significant conforma- tional change and expands in accordance with lateraltension, which not only confirms the tendency of the pre- vious electrophysiological experiments but also leads us to a better understanding of TRPVs. The multi-scale study combining finite element simulation and MD simulation is a significant breakthrough in the field of mechanical mechanism in cell system.