Fundamental solutions for plane problem of piezoelectric materials

Based on the basic equations of two-dimensional, transversely isotropic, piezoelectric elasticity, a group of general solutions for body force problem is obtained. And by utilizing this group of general solutions and employing the body potential theory and the integral method, the closed-form solutions of displacements and electric potential for an infinite piezoelectric plane loaded by point forces and point charge are acquired. Therefore, the fundamental solutions, which are very important and useful in the boundary element method (BEM), are presented.     

双参数弹性地基厚板分析的边界元法

以弹性地基上Ｒｅｉｓｓｎｅｒ板为研究对象，地基采用双参数模型，把地基效应归并到厚板的弯曲微分方程中。利用「４」导出的双参数地基上弯曲问题的基本解，从虚功原理出发，依据在胡海昌的中厚板弯曲理论，推导出三个广义位移表示的边界积分方程。适用于任意边界条件，任意形状及任意荷载的薄板及中厚板的弯曲问题。     

A Unified Theory of Uncalibrated Stereo for Both Perspective and Affine Cameras

This paper addresses the recovery of structure and motion from uncalibrated images of a scene under full perspective or under affine projection. Particular emphasis is placed on the configuration of two views, while the extension to $N$ views is given in Appendix. A unified expression of the fundamental matrix is derived which is valid for any projection model without lens distortion (including full perspective and affine camera). Affine reconstruction is considered as a special projective reconstruction. The theory is elaborated in a way such that everyone having knowledge of linear algebra can understand the discussion without difficulty. A new technique for affine reconstruction is developed, which consists in first estimating the affine epipolar geometry and then performing a triangulation for each point match with respect to an implicit common affine basis.     

基础工业工程网络多媒体实验环境的设计与构建

针对目前基础工业工程实验教学环节的现状，兼备管理和工程双重属性的特点，基于螺旋型系统方法学，在不回避实际操作的前提下制定了具体可行方案，自行设计并建立了基础IE网络多媒体实验环境，开发了配套的适用于远程教育使用的电子教材，其中包括可视化案例库、模特法预定时间标准库、电子教案和电子作业。实际教学表明效果良好。     

浅谈超浓相输送技术在85kA预焙槽的节能应用

1999年该电解铝厂引进超浓相输送技术并进行了10台电解槽工业实验，经过工业实验，确认超浓相输送技术在85kA预焙槽上应用的可行性之后，2001年完成技术改造后将此技术大规模应用于260台三个系列85kA纵向排列中间点式下料电解槽，经一年多的吸收和改进，已成功实现了这一世界先进技术在85kA纵向排列电解槽的平稳运行，不仅比原来的罐车加料方式成本更低，而且填补了超浓相输送技术在中小型预焙铝电解槽上应用的空白。     

浅析参加健身健美操运动的动机与美感

本文对参加健身健美操俱乐部的锻炼者关于动机与美感的若干问题进行了调查，分析了身体形态的变化对运动美感产生的积极作用，并得出了参与健美运动离不开动机驱使和审美理念的影响。     

对高校病残学生体育运动的研究

高校病残学生参与体育活动的状况不容乐观,主要因素是个人、学校、社会诸方面不够重视,从而极大地影响了学生的身心健康发展.为提高整个中华民族的整体素质和健康水平,高校体育在开展体育运动中应重视病残人的体育健身活动,以真正实现我国<全民健身计划纲要>所确定的目标.     

Variations of stress intensity factor of a semi-elliptical surface crack subjected to mixed mode loading

Maximum stress intensity factors of a surface crack usually appear at the deepest point of the crack, or a certain point along crack front near the free surface depending on the aspect ratio of the crack. However, generally it has been difficult to obtain smooth distributions of stress intensity factors along the crack front accurately due to the effect of corner point singularity. It is known that the stress singularity at a corner point where the front of 3 D cracks intersect free surface is depend on Poisson's ratio and different from the one of ordinary crack. In this paper, a singular integral equation method is applied to calculate the stress intensity factor along crack front of a 3-D semi-elliptical surface crack in a semi-infinite body under mixed mode loading. The body force method is used to formulate the problem as a system of singular integral equations with singularities of the form r ⁻³ using the stress field induced by a force doublet in a semi-infinite body as fundamental solution. In the numerical calculation, unknown body force densities are approximated by using fundamental density functions and polynomials. The results show that the present method yields smooth variations of mixed modes stress intensity factors along the crack front accurately. Distributions of stress intensity factors are indicated in tables and figures with varying the elliptical shape and Poisson's ratio.     

Recent Advances in Disordered and Nanostructured Carbon Coatings for Superl Ubricity and Wearless Sliding

Increasingly more demanding and very stringent operating conditions envisioned for future mechanical and tribological systems will certainly require new materials and coatings that are superhard and at the same time self-lubricating.For example, dry machining is a much desired practice in manufacturing sector, but it is currently very difficult to realize mainly because of high friction and severe wear losses. However, recent advances in surface engineering and coating technologies may enable design and production of novel coatings architectures that can combine superhardness with self-lubricating properties in both the disordered or nanostructured forms. Recently developed nearly frictionless carbon films, ultrananocrystalline diamond and carbide derived carbon films can dramatically lower friction and at the same time reduce wear under very harsh sliding conditions. These coatings can be formulated in such a way that they can substantially increase the load-bearing capacity of sliding surfaces and hence improve their resistance to scuffing. It is also possible to design nano-composite coatings that can form self-replenishing and-lubricating tribofilms on their sliding surfaces and thus help increase the overall lubricity of these surfaces. In this paper, an overview of recent advances in disordered and nanostructured carbon films will be presented. Specific examples will be given to demonstrate the superior performance and durability of such novel coatings under a very wide range of tribological conditions. The major emphasis is placed on super low friction carbon films. The fundamental tribological mechanisms that control their exceptional friction and wear behaviors are also discussed.     

利用单位解矩阵估计判定含有非线性电阻的动态电路唯一稳态

利用微分方程单位解矩阵估计的相关方法,得到了确定含有非线性电阻的动态电路唯一稳态的条件.结果表明,含有非线性电阻的动态电路的唯一稳态,可以用一个矩阵测度决定.由于目前已有的经典结果只能处理含有线性电阻的动态电路的唯一稳态,因此本文的工作大大扩展了已有的经典结果.