机械轴承工作状态的ANSYS仿真研究

钢丝滚道球轴承是机械结构中常见的轴承方式之一,为了更好的了解其工作性能,应用弹性接触理论,对机械轴承的工作状态进行ANSYS仿真分析。通过对钢丝滚道球轴承点接触问题进行建模与仿真分析,得到接触压力和各向应力分布的状态。     

齿轮传动中磨损问题研究方法综述

齿轮传动是机器传递运动和动力的一种主要形式，如何减少齿轮工作中的磨损；延长其使用寿命，是工业生产中至关重要的问题。总结了目前齿轮接触问题的数值研究方法、齿轮磨损问题的研究历程等，并对齿轮磨损问题研究的发展方向提出建议。     

疏水性聚酯薄膜的制备及表面形貌分析

利用NaOH溶液化学刻蚀聚酯薄膜成功制得疏水性薄膜.研究了聚酯在碱性溶液中发生水解反应时外界条件对刻蚀结果的影响规律,分析了外界化学条件引起表面微观物理形貌的变化及其所对应的表面特性.结果表明,薄膜经pH为12的碱液在40℃下超声刻蚀5 min左右,并用无水乙醇浸泡,可达到与水接触角120°以上的疏水效果.     

基于PC总线的热继电器自动测试系统设计

文章介绍了利用计算机和VB语言进行的温度继电器自动测试系统的硬件结构和软件程序的实现方法．     

一般载荷作用下滚动直线导轨副的刚度计算

推导了在一般载荷作用下滚动直线导轨受力变形的基本方程，进行了数值计算，并与实验结果进行了比较．基于最大接触应力的判据，提出滚动直线导轨额定静力矩的基本定义，并计算了几种产品的额定静力矩．     

并行程序与状态序列--交叉语义约定的研究

许多程序模型是以数学或逻辑为基础设计并分析的,但程序模型的实现首先是个物理系统,它依物理规律,而非数学或逻辑规则活动.但人们习惯于用状态序列对并列程序模型的语义作数学处理.一旦偏序的状态空间用交叉的方法全序化,并用于论证程序性质,误导就在所难免.所谓误导,指的是与实际运行的偏差,借助于Petri网,可以将它们暴露出来.其实偏差的出现与Petri网的基本现象冲突(conflicct)、冲撞(contact)、并发(concurrency)和混惑(confusion)相关.本文用Petri网分析误导的情况.     

微格教学的一种新尝试--接力试教

在完成单项教学技能训练的基础上进行接力试教的作用在于，系统把握各项教学技能在实际教学中的运用，把技能与完整的教学内容与教学对象结合起来，通过小组学习的互相评价以达到有效的修正、提高。本文论述的是接力试教的必要性、实际操作与效果。     

PI tuning for large dead-time processes with a new robustness specification

A simple PI controller tuning method for large dead-time processes is presented. First, a first-order plus dead-time model is identified on the basis of relay feedback experiments, which Nyquist curve is very close to that of large dead-time processes over a wide frequency range. With the model available, PI controller is designed with a new robust specification. Simulation examples show the effectiveness and feasibility of the presented PI tuning method for large dead-time processes.     

Study on contact algorithm of dynamic explicit FEM for sheet forming simulation

Based on existing algorithms, a newly developed contact search algorithm is proposed. The new algorithm consists of global search, local searching, local tracking and penetration calculation processes. It requires no iteration steps. It can deal with not only general tool surfaces with vertical walls, but also tool surfaces meshed with elements having very poor aspect ratios. It is demonstrated that the FE code employing this new contact search algorithm becomes more reliable, efficient and accurate for sheet metal forming simulation than conventional ones. Foundation item: Supported by the National Natural Science Foundation of China (59875025) and Excellent Young Teacher Foundation of the Educational Department of China Biography: Zhang Hai-ming (1974-), male, Ph. D. candidate, research direction: sheet metal forming simulation.     

A niche-based evolutionary Tabu search algorithm for optimal coordination of protection relays in power networks

In this paper, refusal of operation and the degree of constraint violation are considered as one part of the objective function for optimizing the protection relay setting coordination of over current relays in power systems; a new expression of objective function in this optimization problem is proposed. To combine the advantages of both Tabu search (TS) and evolutionary algorithms (EAs), a new niche-based evolutionary Tabu search algorithm (named NETS) is presented to solve this optimization problem. Moreover, in two cases of power networks, comparisons between NETS and two published algorithms are given. Experimental results show the expression of the objective function for protection relay setting is feasible and reasonable, and the proposed algorithm NETS exhibits a good performance. Biography: YUAN Rongxiang (1965–), male, Professor, Ph. D., research direction: safety and stability in distributed power networks, relay protection, information and intelligent of power system.