活塞压缩机气阀故障检测的免疫神经网络方法研究

气阀故障是活塞压缩机最常见的故障类型之一。为了能够准确地检测出气阀的主要故障,从免疫系统反面选择机理出发,结合神经网络,提出了基于免疫神经网络的活塞压缩机气阀故障检测的方法。通过对2D12活塞压缩机气阀故障状态的检测,获得了较高的检测准确率,证明了所提方法的有效性。所提出的故障检测方法具有普遍的适用性,特别适合于故障样本缺乏或无故障样本设备的故障检测。     

吴消元法在转子动力学研究中的应用

以转子一轴承系统中短轴承的转子涡动，具有非线性支撑的柔性Jeffcott转子模型的周期响应为研究对象，对吴消元法在转子动力学研究中的应用作了初步探索。将吴消元法的特征列思想和Maple软件的符号计算机功能相结合，实现了对短轴承涡动参数的解析计算及对柔性Jeffcott转子模型周期响应的解析分析，在此基础上对Jeffcott转子的动态特性作了进一步的分析。     

温度对液氢绕水翼非定常空泡流影响的数值研究

该文基于均质多相流理论,采用RNG k-模型和修正系数Zwart空化模型对液氢绕NACA0015水翼非定常空化流动进行数值模拟。模拟了非定常空泡云的生长、断裂、涡状空化团脱落和破裂的周期性过程,模拟中考虑了热力学效应,并分析了温度对空泡流场特性的影响。研究结果表明:在相同空化数和来流速度下,空泡周期随温度增高而变长,升、阻力系数的波动周期随温度增高而增加,但其时均值的随温度增高而减小。     

辨识非线性动力系统分岔参数的相空间重构方法

由于关联维数对吸引子的不均匀性敏感，因此可用于定量描述振动信号复杂程度．采用相空间重构方法，对非线性转子轴承系统的动力学行为进行了分析研究，对Jeffcott单盘刚性转子模型的一维时间序列进行了分析．研究结果表明：关联维会在系统运动状态改变时发生明显的跳跃，例如系统在进入油膜涡动或油膜振荡时关联维数都有明显的跳跃，可利用跳跃现象对非线性系统分岔参数进行识别．     

传感器故障诊断中的数据关联方法与应用

基于信息融合技术中的数据关联技术 ,提出了将数据关联方法用于故障监测、报警的问题 ,改进了多传感器多模型相互作用的概率数据互联算法 ,结合某时变系统中传感器的故障诊断问题 ,进行了仿真分析 ,并讨论了这种方法在故障报警和预测预报中的应用。     

基于DCOM的故障诊断通用平台实现技术

提出了基于DCOM标准的故障诊断通用平台的框架体系,开发方法和实现机制。着重介绍了构成平台的软件组件的构造及组件与平台的集成技术,并给出了一个应用实例。     

旋转机械故障诊断系统数据库的机器自学习方法

本文讨论一种旋转机械故障诊断系统数据库的计算自学习方法.该法能使计算机在长期的运行实践中,自动识别和跟踪被监测机组工作参数的改变,从而大大增强了故障诊断系统的适应性.本文将最小?乘法应用于计算机自学习,并以"MMMD-1"的模糊诊断系统为例,介绍了这种方法的原理和应用.计算结果表明,该法对初值稳定.     

整星隔振器性能及阻尼可靠性实验分析

为保证卫星成功发射,应用整星隔振方法改善卫星在升空过程中其所处恶劣的动力学环境,降低卫星由于运载火箭激励而引起振动的幅值.通过隔振器传递率特性实验,可以证明添加隔振器后卫星顶端的响应幅值比未隔振前大幅降低.添加隔振器后的随机实验表明,在随机激励下,隔振器的隔振效果可以满足发射要求.此外,通过对隔振器阻尼可靠性问题的讨论,证明在隔振器少量阻尼元件失效条件下,隔振器性能变化不大,可以满足卫星发射对隔振器的冗余性能要求.     

Effect of attack angle change on hydrodynamic character of supercavitating bodies

A series of experiments has been done in a moderate-velocity cavitation tunnel to investigate the effects of attack angle change on hydrodynamic characters of supercavitation. Hydrodynamic characters of the aft section at various attack angles were compared. The investigation shows that hydrodynamic forces of the aft section are dependent of supercavity shapes at different attack angles,and the magnitude of hydrodynamic forces of the aft section varies with the change of attack angle. When the aft section is in the fully wetted case,the drag coefficient changes little. Lift and moment coefficients both increase with the increased attack angle,and the increase magnitude is not large. When the aft body planing is on the cavity boundary,the drag coefficient of nonzero attack angle is larger than that of zero attack angle,and the maximal lift and moment coefficients both vary obviously with the increased attack angle. In the case that the body is fully enveloped by cavity,the drag coefficient,lift coefficient and moment coefficient are nearly constant with the change of attack angles.     

Whole-spacecraft hybrid vibration isolation based on piezoelectric stacks and viscoelastic material

In order to improve the performance of whole-spacecraft vibration isolation systems,choosing piezoelectric stacks and viscoelastic material as the active and passive vibration isolation components,an innovative whole-spacecraft hybrid vibration isolation system (WSHVIS) is designed and studied.The finite element method is used to establish the dynamic model of WSHVIS and analyze its frequency response characteristic.According to the analysis results,eigensystem realization algorithm is applied to obtain the minimum-order state-space model of WSHVIS,which is used to design controller.On this basis,off-line simulation and on-line realization for the WSHVIS is performed.The simulation and experimental results showed that WSHVIS can effectively reduce the vibration loads transmitted from launch vehicle to spacecraft.Compared with passive vibration isolation system,the hybrid vibration isolation system has a significant inhibitory effect on the low-frequency vibration components,and can greatly increase the safety and reliability of spacecraft.