Investigation on the stiffness and linear error of an air slide table of ultra precision machine in nano‐machining

Ultra precision machines are new generation of machine tools. They produce more accurate pieces in size and tolerance. Various rotational or linear movement mechanisms of these machines have been consisted of two main components; stationery or rail, and moving or slider. They are separated by a pressurized air film to reduce the friction resistance between mating parts. Thus, the relative movement happens through an air film. Two main problems for such systems are stiffness and linear motion errors. These issues will affect product quality. Due to such reason, most steel and iron manufacturers are very much interested to search about their product behavior under conditions of loading them as a thrust or journal bearing. In order to study stiffness and error characteristics of the movement mechanisms in this research, there have been experimental investigations about their variation behavior, and their relationship with input parameters such as inlet air pressure, applied load. Consequently, the best performance condition was identified. Additionally, the general behavior of errors in linear motion was recognized. Also, optimum conditions were identified in order to have the least errors.     

小湾水电站高陡边坡开挖爆破试验

小湾水电站开挖区地形、地质构造复杂,边坡高而陡。深孔大区爆破规模大,可能会影响边坡的安全,需要通过试验确定合理的开挖爆破方案和爆破参数。试验结果表明,采用垂直于边坡方向上的分区爆破方案,可以彻底消除爆碴压死现象。在全面分析试验结果的基础上,推荐了能确保高陡边坡安全的爆破参数以及爆破震动控制标准。     

气动精测滑阀付节流口叠合量的分析和研究

本文对滑阀付节流口叠合量的气动测量原理进行了实验研究和理论分析。根据喷嘴盖板变换机构的模拟实验,建立了相应的数学模型。提出了提高节流口叠合量气动测量精度和效率的方向。     

CODEBREAKING WITH IBM MACHINES IN WORLD WAR II

Standard IBM punchcard machines, supplemented by a number of ingenious add-on units developed by U. S. Army and Navy cryptanalysts, played a crucial role in the breaking of Japanese naval and military codes and German and Soviet diplomatic codes during World War II     

一种基于变尺度滑动窗口的数据流频繁集挖掘算法

基干传统滑动窗口机制的数据流频繁集挖掘算法较多地考虑快速且精确的效果,而较少考虑数据流的时变特性,对传统的滑动窗口机制进行改进.同时考虑数据流的海量特性和时变特性,提出一种基于变尺度滑动窗口机制的数据流频繁集挖掘算法V-Stream.该算法采用事务链表组的概要数据结构.能够根据数据流的数据分布变化自适应调整窗口大小.Eclipse上的仿真实验结果表明,V-Stream相比Manku算法提高了挖掘数据流频繁集的时间与空间效率.     

基于复杂度分析的电机转子-轴承系统早期故障检测方法

将复杂度分析方法用于转子-轴承系统的早期故障诊断中。同传统的频谱分析方法相比，复杂度分析更适用于非线性、非平稳信号的分析，详细介绍了复杂度的定义及其算法。着重用复杂度分析方法对轴承内圈裂纹早期故障及转子早期碰摩故障的试验数据进行了分析，结果表明系统发生故障时，信号的相对复杂度与正常状态相比均有明显的增加，该方法能够准确地检测出早期故障，并且可以对转子-轴承系统状态进行定量刻画。     

带式输送机落煤斗耐磨衬板的改进

分析了输煤系统带式输煤机存在的问题,并提出解决方案,确保输煤系统安全稳定运行。     

ALTERABLE INTERVAL OPTICALELECTRONIC AUTOCOLLIMATION METHOD FOR STRAIGHTNESS MEASUREMENT OF PRECISION GUIDE

0 INTRODUCTIONThe guide straightness strongly influences the performanceof kinetic parts, so straightness measurement[1-5] is widely ap-plied in engineering. An optical-electronic autocollimationmethod is widely used for high precision straightness measur…     

三通直管注射模的设计

分析了三通直管塑件的工艺特点,主要分析了浇口注射模成型并且带侧向抽芯机构制品的工艺特点;介绍了注射模结构,浇口设计方案和模具工作过程。为保证外观质量,综合地处理好产品外观要求与浇口位置及脱模方式之间的问题,简化模具结构、减低制造成本、提高了生产效率。注射模具有整体结构紧凑的特点。     

任意分布参数的车辆半轴的可靠性稳健设计

组合随机摄动法、四阶矩技术、可靠性优化设计、可靠性灵敏度与稳健设计等理论方法,提出了车辆半轴的可靠性稳健设计方法,将可靠性灵敏度作为目标函数之一体现在可靠性优化设计模型之中,将可靠性稳健设计归结为满足可靠性要求、重量最轻和敏感性最低的多目标优化设计问题。在基本随机参数的前四阶矩已知的情况下,可以实现基本随机参数为任意分布参数的车辆半轴的可靠性稳健设计。数值算例表明该方法是一种有效实用的设计方法。