基于BP神经网络电液伺服阀多参数故障模式识别研究

分析了电液伺服阀静态特性与故障模式之问的映射关系，介绍了基于BP神经网络电液伺服阀故障模式识别的力法，并进行了实验研究，结果表明该方法故障模式识别准确率较高，可以进一步与伺服阀试验台测试功能进行结合，形成一种具有自学习、自动测试与智能诊断功能的检测系统。     

电液伺服阀故障模式识别的自适应神经-模糊推理系统

基于MATLAB模糊逻辑工具箱，利用维数缩减技术和模糊减法聚类法，对表征电液伺服阀工作状态的实测样本数据进行聚类分析，实现合理的特征空间划分和寻找适当的规则数目，从而实现了自适应神经--模糊推理系统(即：ANFIS）的结构辨识。在此基础上，利用BP算法与最小二乘法相结合的混合算法，实现ANFIS的参数辨识，建立了适用于电液伺服阀的故障模式识别的ANFIS，从而有效地解决了电液伺服阀故障的多样性和不确定性的难题，实现了电液伺服阀故障的智能诊断。     

伺服阀高频震荡故障机制分析

针对电液伺服阀使用过程中出现的高频振荡现象，通过理论分析结合实践，揭示了电液伺服阀高频震荡现象的故障机制，即该现象是因伺服阀在长期使用过程中，其弹簧管刚度值由于疲劳损坏而降低，导致劳斯稳定条件被破坏，系统失稳而产生的。并给出相应的解决措施。     

三级电液伺服阀的故障仿真研究

电液伺服阀性能的优劣对液压设备的控制精度、系统的稳定裕度以及可靠性有很大的影响.而对电液伺服阀故障模拟常采用硬件方式仿真模拟,笔者利用液压仿真软件对电液伺服阀进行仿真研究,通过仿真分析得到发生故障时阀的压力曲线,符合实际要求.     

基于AMESim的二级双喷嘴挡板电液伺服阀仿真及故障研究

为分析二级双喷嘴挡板电液伺服阀性能及进行故障研究,利用AMESim平台建立了伺服阀的整体仿真模型,通过进行伺服阀动态性能实验获得阶跃信号作用下伺服阀输出流量瞬态、稳态数据,通过数据对比验证了所建仿真模型的正确性。仿真分析了二级双喷嘴挡板电液伺服阀常见故障对频响特征曲线、流量特性、压力特性等性能的影响,仿真结果使得系统故障分析有据可依,可为伺服阀的故障诊断研究提供依据。     

三级电液伺服阀稳定性及其对系统的影响

指出三级电液伺服阀及其所在系统的不稳定现象并进行分析,通过对三级电液伺服阀的结构原理分析,从伺服放大器、先导级和主阀这3个部分讨论了影响三级电液伺服阀稳定性的主要因素,重点分析T--级电液伺服阀先导级小球磨损对稳定性的影响,对理解、维护三级电液伺服阀及电液控制系统有指导意义.     

三类伺服阀控制电液伺服加载系统的分析

以三类伺服阀控制马达的电液伺服加载系统为对象，分别建立了三类阀控制马达伺服加载系统的数学模型并进行了频率特性分析，通过对系统进行的动态仿真分析，得出了不同伺服阀对电液伺服加载系统的影响特性。     

电液伺服阀计算机辅助测试技术的研究

本文介绍了一种电液伺服阀静、动态特性计算机辅助测试方法，该测试方法可完成三、四通电液伺服阀静、动态特性的测试。提出了采用跟踪滤波技术测试电液伺服阀相频特性和幅频特性，其测试效果很好。     

基于AMESim的电液伺服阀试验和仿真研究

电液伺服阀是液压伺服系统的核心元件,直接影响系统的控制性能.利用AMESim软件对电液伺服阀进行建模仿真,模拟出电液伺服阀的特性.通过对比试验数据和仿真数据,验证了电液伺服阀仿真模型的有效性.     

喷嘴挡板式电液伺服阀的应用及仿真

介绍了典型电液伺服阀的工作原理,基于HyPneu电液仿真软件对喷嘴挡板式电液伺服阀模型进行仿真,为工程应用喷嘴挡板式电液伺服阀提供了理论及仿真依据.     

Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation

Sequential anodic and cathodic pulse voltages were applied on anodised Al micro-electrodes in alkaline silicate electrolyte to explore the role of cathodic pulse in AC or bipolar plasma electrolytic oxidation (PEO) process. SEM observation was carried out to observe the sites of anodic and cathodic breakdown and their morphologies. The prior anodic breakdown accelerated the cathodic breakdown at ?50 V, and the acceleration was associated with the preferential cathodic breakdown at the anodic breakdown sites. However, the succeeding anodic breakdown during applying anodic pulse of 420 V for 2 ms was highly suppressed at the cathodic breakdown sites. This would randomise the anodic breakdown sites. Such role may contribute to the formation of rather uniform coatings on aluminium in this electrolyte without large discharge channels when larger cathodic current is applied with respect to the anodic current in AC PEO.     

工业用视频内窥镜在故障诊断中运用实例

在故障诊断和维修中，经常出现因为设备的结构、安装和现场环境等原因，造成常规故障诊断方法无法看到设备故障点内部发生的具体情况。为解决上述问题，采用新型故障诊断设备——工业用视频内窥镜，将其采集的图像传输到电视监视器上显示，在不用对设备进行拆卸的条件下，就可以对故障点内部进行观察和判断。使用这种方法大大提高了对设备故障判断的可靠性，顺利完成设备故障的排除工作。     

Breakdown of the niobium oxide film under galvanostatic polarisation and in acid solutions

The breakdown process of niobium oxide process depends on the current density, the concentration and the composition of the electrolyte and the time that the film is maintained under galvanostatic polarisation. The electrical breakdown is associated with small oscillations in the breakdown potential, the presence of sparks, anion incorporated in the film and small holes in the film surface. The mechanical breakdown is associated with sudden variations in the potential; there are no anions in the niobium oxide to start the avalanche process and large fractures in the film. Electrical and mechanical breakdown processes can proceed in the same anodisation.     

Mechanism of pit nucleation by electrical breakdown of the passive film

Based on the similarity between the electrical breakdown of insulators and the pitting breakdown, the mechanism of the breakdown of passive film of transition metals in a chloride solution is described. It is proposed that nucleation of pits occurs by electrical breakdown, probably by the Zener mechanism. Creation of a very high current locally destroys the passive film and causes the dissolution of the metal forming metastable or stable pits.     

中国焊接资讯网(www.weldinfo.net)的建设

针对中国焊接资讯网的现状，提出了重新构筑的技术方案，强调了网站在焊接专业的市场定位，明确了需要实现的数据库、电子商务等各项服务功能，其要点正在逐步实施中。     

丙烯酸粉末涂料的特性及其应用体系

从粉末涂料的现状出发说明开发丙烯酸粉末涂料的重要性 ,介绍了丙烯酸粉末涂料的特性 ,重在阐述了通过对丙烯酸树脂不同的活性官能团与不同的树脂或固化剂交联得出工业化应用体系及其优缺点。     

卡车玻璃导轨槽模具设计

玻璃导轨槽是一种细长且有复杂外形的汽车零件,玻璃导轨是驾驶室车门上必备的冲压件,由于其长度长、刚性差,整体外形呈3D立体形状且断面为半封闭形状,给成形带来许多困难。依据其腹板面形状和翻边类型的不同,提出了两种工艺方案和联合安装模具结构,在实践中证明这种工艺方法最简捷,可以大幅度降低模具成本,是一种比较经济实用的方法。     

The localized corrosion of resistant alloys in chloride solutions

A potentiostatic scratching technique has been used to study the breakdown potentials of stainless steel 304, Incoloy, Inconel 600, Monel 400 and Hastelloy C in chloride solution at pH 8 as a function of chloride activity, temperature and metal cold work. For the first four alloys breakdown occurs through pitting. For Hastelloy C there is no pitting process, and breakdown occurs by a transpassive reaction, probably involving oxidation of Mo and Cr in the film to soluble anions.     

基于智能积分因子的三维模糊控制器及其应用

模糊控制器以其结构简单，适应性强，响应速度快，鲁棒性好等特点引起广泛注意。本文分析了模糊控制器的稳态控制特性，提出了在模糊控制输入端引入一种智能积分器，形成一类三维模糊控制器。并对其进行了结构分析，通过仿真及在电液位置同步控制系统中的应用，表明这种模糊控制器具有良好的稳态控制性能。     

Temperature Dependence of Pitting Corrosion in Cr-Ni stainless steels

In the temperature range from 6 to 40°C the temperature dependence of pitting corrosion may be expressed by the Arthenius-equation. The lowering of the breakdown potential in this range shows a linear dependence on the reziprokal value of the absolute temperatur. From the temperature dependence of the breakdown potential and of current density it is possible to calculate the activation energy of dissolution within the pits (4,5 –4.8 kcal). In the temperature range from 40 to 70°C the temperature dependence of the breakdown potential is relatively small. This fact apparently indicates a change in pitting kinetics above 40°C. It is concluded from other results obtained that in this temperature range the formation of oxide layers in the pits is accelarating so that passivation is accelerated and the breakdown potential increases.