CAE软件在高职机械类专业教学中的应用研究与实践

研究了高职机械类专业学生的学习特征,将计算机辅助工程的基本功能和应用与机械设计相结合,降低了理论难度,提高了学习效果。     

一种低功耗无线传感节点设计

针对现有远程无线传感节点存在的功耗较高、测量准确度易受供电电压影响等不足,提出了一种基于时间同步的低功耗通信机制,采用比率测量技术、传感电路节能测量技术、无线SOC技术等技术设计了基于nRF24E1为核心的无线传感节点软硬件.实验表明,无线传感节点休眠功耗仅有2.45μA,10s采样周期的平均电流为93μA;既实现低功耗,也保证了测量准确度.     

本体在E learning系统中的应用研究*

探讨了Elearning及本体,提出了基于本体的Elearning系统层次结构模型,并重点研究了本体在其中的应用：用于描述学习材料语义的内容本体,用于定义学习材料上下文的上下文本体以及用于在学习课程中组织学习材料的结构本体。     

消雷器静态电场分布及其并行计算

以分析新型防雷装置消雷器静态电场为例 ,提出一种非常适合于多个 CPU并行计算机上实现的并行算法——奇偶并行法。通过算例证实该算法容易实现、效率比较高 ,同时也容易推广至其它数值计算领域。最后给出伞形导体消雷器的静态电场分布 ,并首次提出了判别消雷器设计期间的优劣标准 ,为进一步设计消雷器奠定理论基础。     

UML活动图的时序逻辑语义

UML活动图可以表示不同抽象级的控制流,很适合用于对系统的行为建模．但是缺乏精确的语义使得难以对它所表示的系统行为进行分析．XYZ／E是一可执行线性时序逻辑语言,既可描述系统的动态行为又可表示程序性质,用它对活动图形式化后,就可在统一的逻辑框架下分析活动图的性质．定义了一个有向图结构用以表示UML活动图,再给出其XYZ／E语义,并用一个例子说明活动图到XYZ／E的语义转换,为进一步的分析提供形式化基础．     

Robust Multigrid Methods for Nearly Incompressible Elasticity

We consider multigrid methods for problems in linear elasticity which are robust with respect to the Poisson ratio. Therefore, we consider mixed approximations involving the displacement vector and the pressure, where the pressure is approximated by discontinuous functions. Then, the pressure can be eliminated by static condensation. The method is based on a saddle point smoother which was introduced for the Stokes problem and which is transferred to the elasticity system. The performance and the robustness of the multigrid method are demonstrated on several examples with different discretizations in 2D and 3D. Furthermore, we compare the multigrid method for the saddle point formulation and for the condensed positive definite system. Received February 5, 1999; revised October 5, 1999     

电子商务在中国

中国的互联网发展到今天，已经拥有近千万的网民和１２多万个中文网站。然而中国的电子商务仍然面临着不少问题，如习惯问题、终端产品拥有率低、服务意识淡漠和商业流通中的安全问题。只有通过政府支持和法律保障等，中国的电子商务才能迎来爆炸性增长的未来。北电网络Ｓｈａｓｔａ ５０００构筑的功能强大的平台将推动中国电子商务的发展。     

彩色反转片E-6冲洗工艺中的首显和彩显

本文根据实际工作经验 ,系统地总结了彩色反转片 E- 6冲洗工艺中的首次显影 ,即黑白显影和彩色显影的主要技术环节和控制方法及注意事项。     

Weighted Error Estimates for Finite Element Solutions of Variational Inequalities

In this note the studies begun in Blum and Suttmeier (1999) on adaptive finite element discretisations for nonlinear problems described by variational inequalities are continued. Similar to the concept proposed, e.g., in Becker and Rannacher (1996) for variational equalities, weighted a posteriori estimates for controlling arbitrary functionals of the discretisation error are constructed by using a duality argument. Numerical results for the obstacle problem demonstrate the derived error bounds to be reliable and, used for an adaptive grid refinement strategy, to produce economical meshes. Received September 6, 1999; revised February 8, 2000     

Uniform Pointwise Convergence of Finite Difference Schemes Using Grid Equidistribution

A singularly perturbed quasilinear two-point boundary value problem is considered. The problem is discretized using a simple upwind finite difference scheme on adapted meshes using grid equidistribution of monitor functions. We derive sufficient conditions on the monitor function that guarantee uniform convergence in the discrete maximum norm no matter how small the perturbation parameter is. These results can be used to deduce uniform convergence of the scheme for a number of layer-adapted meshes. We also propose an adaptive procedure for the numerical treatment of the boundary value problem. Numerical experiments for the schemes are presented. Received November 12, 1999; revised April 20, 2000