低温切削技术及其应用研究

低温切削是指在低温环境下进行的切削过程,它利用低温下材料的物理化学性质,实现特定的加工目的。分析了低温切削技术的特点及其制冷技术,阐述了机械制造领域中低温切削技术的研究成果及应用状况。     

Numerical simulation for rheological characteristics of alternating distribution of soft and hard rock layers

The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of rock mass. The Burgers and generalized Kelvin models were applied to the soft and hard rock respectively and the rheological parameters were obtained based on the method of optimum separation. By using the simulated code FLAC^3D, the stability of surrounding rocks of a certain underground plant was analyzed. The effect of surface load and weakening the parameters intensity of argillaceous and bioclastic interlayers between soft and hard rock on rheological behavior of layer composite rock mass was investigated. The results indicate that the rheological characteristics of soft and hard rock layer in composite rock mass can be described well with above two rheological models.     

590P 4Q直流调速器在带钢纵剪机组电气控制中的应用

简单介绍了带钢纵剪机组的用途及其工艺流程,描述了全数字式590P 4Q直流调速器直流系统功能,设计了590P 4Q直流调速器的供电系统和直流调速系统,利用PLC和590P 4Q调速器之间强大的通讯能力,实现了PLC和直流调速器的数字通讯,提高了纵剪机组的生产能力和效率,降低了生产成本。     

矿山电机控制系统原理

矿山风机中使用的交流电机驱动,其消耗与浪费非常严重。针对DTC和VC控制系统的现状及实用化技术提出了一些看法。     

基于随机森林回归的清防垢加药量预测方法

复合驱由于强碱化学剂的注入易造成严重的结垢现象,而预测清防垢加药量是制定科学的清防垢方案的关键.为了获得一种具有较强实用价值和较高预测精度的复合驱清防垢加药量的预测方法,该文将随机森林回归算法应用到复合驱清防垢加药量预测.首先,分析并处理影响清防垢加药量的20维特征,利用随机森林回归的特征重要性评估功能对影响加药量的众...     

开关稳压电源中的电磁兼容技术

从滤波和屏蔽两个方面分别论述了开关稳压电源中的电磁兼容问题。为了满足对开关稳压电源电磁兼容的要求,并从这两个方面分别提出了一些行之有效的技术和方法,并加以实验验证。     

测量学多媒体教材在传播优质课程资源中的地位与作用

文章介绍了编著附随书光盘的系列测量学多媒体教材的做法与经验,教材发行5年来的实践证明,多媒体教材是传播测量学优质课程资源的有效途径。     

电驱变速箱用润滑油性能要求

文章综述了电驱变速箱用润滑油的性能要求。电动车是未来汽车产业发展的方向,而电机与变速器耦合的形式是电动汽车传动系统发展的主流。电驱变速箱中有电机、齿轮、湿式离合器等传动部件,润滑油不仅要润滑冷却机械传动部件和电机,同时还要作为能量传递的工作介质和热传递介质,所以电驱变速箱用润滑油必须具备优异的绝缘性能、抗磨损性能、摩擦特性、氧化安定性、剪切稳定性、抗泡沫性能、温升特性以及与漆包线良好的相容性等。     

一种基于软阈值方法的改进A1/A2极化干涉分类算法

在分析了极化干涉技术的发展现状和发展趋势的基础上,从极化干涉的特殊性入手,分析了干涉相干系数在极化干涉分类中的作用,并且系统分析了基于相干最优优化后的相干系数进行极化干涉分类过程的原理,总结了现有极化干涉分类算法在阈值选择方面存在的不足,阐述了硬阈值方法和软阈值方法的基本原理和它们之间的区别,最后提出基于软阈值方法的改进A1/A2非监督极化干涉分类算法,解决了极化干涉分类现有的分类空间中的阈值问题。实验表明这种方法能够得到更好的分类结果,做出了改进。     

Modelling of V–Hz and vector controlled ASDs in PSCAD/EMTDC for voltage sag studies

This paper deals with modelling and performance of adjustable speed drives (ASDs) subjected to voltage disturbances in electric supply. The aim of this study was to develop appropriate models of typical ASD and investigate their sensitivity to voltage disturbances under various practical modes of operation and control. Accordingly, scalar controlled open and closed loop volts–hertz (V–Hz) and vector controlled closed loop ASDs are modelled in PSCAD/EMTDC environment, and their performance in the presence of voltage disturbances is investigated under typical operating and loading conditions.