基于声发射监测的静载荷滑动轴承接触摩擦故障诊断的实验研究

在利用振动信号诊断静载荷滑动轴承接触摩擦故障的基础上，利用声发射监测方法对静载荷滑动轴承接触摩擦故障进行诊断．研究表明，与振动信号相比，声发射信号的频率响应范围更宽，所包含的信息量更大，能较好地反映轴承的摩擦规律，故障特征明显，易于识别，参数稳定性较好，因而可以更有效地诊断静载荷滑动轴承接触摩擦故障．     

Investigation of the Dynamic Response of Swirling Flows Based on LES and Experiments

The dynamic response of a swirling flow undergoing vortex breakdown is investigated via Large Eddy Simulation (LES) and experiments in a water flow facility. The investigation is carried out following previous work on the link between thermoacoustic combustion instabilities and coherent structures in lean premixed gas turbine combustors. The velocity field transfer function is obtained in LES from the Unit Impulse Response determined via application of a low intensity broadband noise perturbation of the inflow mass flow rate and the Wiener-Hopf filtering method. In the experiments, harmonic fluctuations in the water flow rate through the swirler are generated via a piston mounted on the side wall of the test facility and activated with a low frequency linear motor. The velocity field transfer function is then obtained via phase averaging applied to Particle Image Velocimetry snapshots which are collected at prescribed values of the harmonic phase. The analysis, which is carried out in terms of coherent structures identified via Proper Orthogonal Decomposition, gives numerical transfer functions with amplitude and phase consistent with the experimental ones.     

基于蚁群算法的复杂系统多故障状态的决策

故障树在设备的故障诊断中被广泛应用。当系统复杂度较大时,故障模式和故障树的分支会剧烈增加,故障现象和故障原因因此出现复杂关系,这必然给故障检测和诊断推理带来极大的困难。在故障诊断中引入一种新的人工智能方法,即蚁群算法,可以确定故障树的最优检测次序,并指导系统多故障状态的决策。由于该方法具有平行性、鲁棒性等特点,可以很好地解决前面所提问题。仿真结果显示,在故障树中采用该新方法可行、有效。     

A new approach to on-line vibration monitoring and fault diagnosis

This paper presents a finite element method by deriving the stiffness matrix of cracked element from the stress intensity factor. The method can be used to evaluate the strain response of the cantilever beam with a single edge crack. By using the method of identification in time domain, the modal parameters are identified and at the same time the effect of crack closure is taken into consideration. Analysis has also been made of the sensitivity of the strain to the faults. Test results show that the strain response is more sensitive to faults than the displacement response. Then, a distinguishing function is introduced, which is more effective than any other existing ones in failure detection. Finally a new approach to on-line vibration monitoring and fault diagnosis is given.     

基于RBF网络的信息融合在SAMS故障诊断中的应用

针对卫星姿态测量系统(SAMS)，将径向基函数RBF(Radial Basis Function)网络和多传感器信息融合技术相结合，并将其应用在系统的故障检测与诊断中。研究结果表明，此方法是可行有效的，可以提高系统的测量精度和性能。     

一种基于小波变换的信号突变征兆提取方法及其应用

获取故障征兆是诊断系统必须解决的首要问题。应用小波变换理论提出了一种信号突变征兆提取方法，并将它应用于转台故障诊断中。实验结果表明，这种方法在信号突变征兆提取上具有明显效果。     

野值存在情况下组合导航系统的容错技术研究

提出了“故障诊断周期”的概念，并基于一个诊断周期内占多数的数据均超过门限时才认为故障，否则认为是野值的故障原则对故障蜮野值情况分别处理。该容错方法不仅可以避免因野值造成的组成模式的频繁，而且还通过剔除野值对滤波的影响，提高了系统滤波精度和数据的连续性，并提高了系统故障检测的灵敏度。这在仿真中都得到了证明，说明该方法行之有效，在工程实际中也可以应用。     

Rolling bearing fault detection using correlation technique

It's known that auto-correlation technique is effective in extracting periodical signals from random noises. In the case of fault monitoring of rolling element bearing, we can't acquire the.fault information directly from the original signal because of the difference of signal phases. And the signal is shown as the wide band random signal in auto-correlation function. In this paper, the signal is pre-processed and the results are proved effctive. Moreow, by taking the auto-correlation fumction we can obtain the determined and comparable samples. This is very important for establishing the data base of running condition and for detecting the faults.     

灰色理论在旋转机械故障诊断与预报中的应用

利用灰色理论的关联度分析实现了旋转机械故障的精密诊断 ,利用灰色模型( GM)实现了旋转机械的状态预测及故障预报 ,并用 C语言编制了一套完整的旋转机械灰色故障诊断、状态预测与故障预报软件。同时本文对某厂透平机进行了全面的计算机诊断与预报 ,通过现场对该透平机检查发现故障与本软件诊断结果一致 ,进而揭示了利用灰色理论开发旋转机械故障诊断和预报系统的可行性。本软件为旋转机械故障诊断专家系统的开发提供了新的借鉴     

基于C-SVM的组合导航系统故障诊断算法

为了提高捷联惯性组合导航系统的可靠性,将聚类支持向量机(C-SVM)应用于故障诊断技术,基于SINS/DVL/MCP/TAN组合导航系统建立了C-SVM故障诊断模型,将SINS/MCP、SINS/TAN和SINS/DVL三个子滤波器的相关特征量(残差值和状态检测函数)作为样本对C-SVM进行训练,并应用交叉验证法选择参数组.根据训练好的C-SVM模型分别对三个传感器进行故障诊断,若发生故障则屏蔽相应传感器的输出信息,利用其余的传感器进行重构.仿真结果表明,C-SVM的故障诊断正确率较高,特别是当训练样本数有限的情况下也能够达到较好的性能,克服了传统的神经网络在训练样本数较少时推广性能不足的问题,因此是一种理想的故障诊断技术.     

分数阶微分方程的Haar小波算法研究

在BPFs的Caputo分数阶微分算子矩阵的基础上,建立了Haar小波的分数阶微分算子矩阵,提出了一种有效的求解分数阶微分方程的Haar小波数值方法,并将该方法应用于线性和非线性分数阶常微分方程求解中.数值算例表明,该算法简单,数值精确度高,是一种高效的数值求解方法.     

惯导系统故障诊断技术的特点

对惯导系统故障诊断技术的特点作了简要而全面的论述。论述的内容包括基本功能、故障分类、故障现象及原因，指出各类故障诊断方法的问题，并提出了智能故障诊断构思。     

Permeability up-scaling using Haar Wavelets

In the context of flow in porous media, up-scaling is the coarsening of a geological model and it is at the core of water resources research and reservoir simulation. An ideal up-scaling procedure preserves heterogeneities at different length-scales but reduces the computational costs required by dynamic simulations. A number of up-scaling procedures have been proposed. We present a block renormalization algorithm using Haar wavelets which provide a representation of data based on averages and fluctuations. In this work, absolute permeability will be discussed for single-phase incompressible creeping flow in the Darcy regime, leading to a finite difference diffusion type equation for pressure. By transforming the terms in the flow equation, given by Darcy’s law, and assuming that the change in scale does not imply a change in governing physical principles, a new equation is obtained, identical in form to the original. Haar wavelets allow us to relate the pressures to their averages and apply the transformation to the entire equation, exploiting their orthonormal property, thus providing values for the coarse permeabilities. Focusing on the mean-field approximation leads to an up-scaling where the solution to the coarse scale problem well approximates the averaged fine scale pressure profile.     

基于Haar小波方法的功能梯度材料矩形板三维力学分析

利用Haar小波方法对任意材料梯度分布的四边简支功能梯度材料矩形板进行了三维力学分析.由于小波方法在求解局部奇异性问题上的优越性,对于任意材料梯度变化,甚至材料性质存在局部剧烈变化的情况,各分量的Haar小波级数解都有较好的收敛性.通过算例得到了矩形板在机械荷载作用下,平板上下表面材料性质差异以及材料不同梯度形式对其结构响应的影响.     

电动潜油离心泵流道堵塞振动模型研究

电动潜油泵以其独具的特点和优势在油田生产过程中得到了日益广泛的应用,但过高的故障率给油田开发带来效率和经济上的损失。其核心部件离心泵也是故障易发部件,经常出现流道堵塞,严重影响机组的正常运转。本文结合电潜泵机组的工作特性和力学性能,建立了一套潜油离心泵流道堵塞的振动识别模型,并推导了振动模型的运动方程。利用自建的大型实验装置,模拟了该类故障井的实际生产并测得了井口三维振动信号,绘制了信号的时域图和频域图。此外,本文引入小波分析方法对信号进行了细致化分析,研究了此类故障的振动特性并验证了所建模型的可靠性。     

基于邻域粗糙集的转台故障诊断

针对转台的故障类型和特点,设计了基于邻域粗糙集的故障诊断系统。邻域粗糙集以邻域关系代替经典粗糙集的等价关系,通过邻域信息粒子逼近论域空间,可以直接处理数值型属性。提出了一种基于邻域等价关系的混合约简算法,通过计算条件属性的依赖度,对原始决策表进行约简,有效地剔除了系统的冗余属性。在约简决策表的基础提取分类规则,并最终生成分类机。通过对转台故障诊断的实验,验证了该方案的有效性和可行性。     

THREE-DIMENSIONAL ANALYSIS OF FUNCTIONALLY GRADED PLATE BASED ON THE HAAR WAVELET METHOD

A three-dimensional analysis of a simply-supported functionally graded rectangular plate with an arbitrary distribution of material properties is made using a simple and effective method based on the Haar wavelet.With good features in treating singularities,Haar series solu- tion converges rapidly for arbitrary distributions,especially for the case where the material prop- erties change rapidly in some regions.Through numerical examples the influences of the ratio of material constants on the top and bottom surfaces and different material gradient distributions on the structural response of the plate to mechanical stimuli are studied.     

基于案例推理方法在惯性导航故障诊断专家系统的应用

以测量船惯性导航系统为例,为解决其故障诊断专家系统知识瓶颈问题,特别是突发、原因不详的故障,利用专家知识和以往的工作经验积累,在故障诊断专家系统中融入了基于案例的推理方法。这种推理方法把知识获取简化为领域内经验知识的收集,并以此为基础构造案例库;把基于规则的推理转化为基于案例推理,即在案例库中检索相似的经验知识。采用基于案例推理的方法,可以简化知识获取的过程,求解效率高、质量高,具有持续的学习能力,能有效提高故障诊断系统的智能化程度。文中重点介绍了构建该故障诊断专家系统的案例知识表示方法、案例的索引和检索算法等关键技术。     

小波分析技术在陀螺故障诊断中的应用研究

小波分析是一种全新的时一频两维分析技术，其对高频突变信号和低频缓变信号的分析有其独特的优点。本文分析了小波分析技术的原理，提出了将其引入机械设备故障诊断中的方法。通过对有故障陀螺振动信号的多尺度分析，研究故障信号小波变换轴心轨迹分量图，建立典型故障特征模型，从而对单故障及多故障问题进行分析与诊断。