The design scheme and technical details for Distance Examination and Computer Aided Grading System for Computer Aided Drawing are presented in this paper. The distance examination is managed by a central server and examination site servers, being connected by internet and local networks. The questions and answers are stored in data banks of SQL Server, and the program in the client is encoded by C# Based on analysis of AutoCAD object model and establishment of specific algorithm, the ActiveX automation is used to realize the grading for drawing file. The grading results are accurate and efficient. The software is shown to reach design requirements after testing.

Several measures are put forward to solve the problems of magnetorheological (MR) damper such as sedimentation of magnetorheological fluid (MRF), easy abrasion leakage of oil-seal and lower exciting efficiency of piston magnetic circuit. The magnetic field distribution in MR damper is reconfigured by finite element method for Passat B5 damper as a design object. The test results show that the design calculations are satisfactory.

用面向对象的设计方法,在分析AutoCAD图元对象的基础上,设计了计算机辅助绘图阅卷系统的算法,进而完成了整个系统的研制工作.

本文从液体与固体界面之间的关系,以及它们之间存在的表面张力入手,从另一个角度探讨了磁流体密封的机理.通过分析和试验,得出了磁流体密封能力与表面张力间的定性关系.在把磁性力作为附加的范德瓦引力的新思路基础上,提出了磁表面张力新概念,为研究磁流体密封能力作了一些基础性的工作.

对磁流体在转轴密封中的应用作了探讨.阐明了磁流体密封的原理,根据磁学理论进行了磁回路的计算.在此基础上设计了磁流体密封的试验装置.实验中采用不同的密封间隙,以确定磁流体密封能力与密封间隙之间的关系.同时,进行了轴旋转和静止时磁流体密封能力变化的试验.试验结果表明,磁流体的密封能力随密封级数的增加而提高,随密封间隙的增大而减小,密封间隙在0.05～0.20mm时,效果较好,同时密封级数有一个最佳值.

多极齿形结构的磁流体装置中齿形几何参数的选择是这类装置设计的核心问题.它决定该装置中磁场分布形态,从而影响了密封的质量.采用任意三角形网格划分的有限元法求解描述永磁-软铁系统性质的非线性Poisson方程,以矢量磁位A为计算量得到磁流体密封装置中工作气隙的磁场分布数据.经多个齿形几何参数的比较,提出了磁流体密封装置的多极齿形结构设计中齿极宽度、槽宽度和槽深度的最佳参数.计算中考虑了磁铁的边缘效应、非线性效应及漏磁效应,计算结果较其他方法更可靠.