故障信号

The fault arc characteritie of EHV transmission lines is investigated, the fault arc EMTDC model is set up, and the result of simulation confirms to the result of experiment.

考虑到EHV电网故障带有电弧的特点，利用电力暂态信号小波分析方法的研究结果，首次提出基于小波分析的EHV输电线路单端量暂态保护机理和实现方案，该保护原理能够实时检测EHV电网线路故障，区分区内外故障。

By applying the difference arithmetic to solve the differential vibration model of the single-degree-of-freedom,the acceleration responses of the vibrated bevel wheel was calculated.The bevel wheel contact fault was simulated by taking it as the impulsion loading in local point.By using techniques of wavelet de-noising and demodulated resonance,gear contact character information was picked up successfully.

从齿轮的单自由度振动模型出发，运用差分算法对模型进行求解，得到斜齿轮的振动加速度响应，将齿面接触型故障等效为在局部点突加一个冲击载荷，对齿轮齿面接触型故障进行了仿真，利用小波降噪和共振解调技术分别对仿真的染噪振动加速度信号进行处理，成功地提取了轮齿接触故障的信息。

Aim at the defect of commonly technique,a new technique of alarm in advance of boiler water level is put forward.this technique adopt the idea of signal catenation and blur control.alarm in advance and seek out the coming fault.the fault can be repaired before water level beyond the limit.avoiding water level beyond the limit.

针对一般方法的弊端，提出一种新颖的汽包水位预警的方法。该预警系统采用信号间的连锁和模糊控制的思想，在故障发生以前提出预警，并且找出可能发生的故障。从而达到在水位越限以前进行故障检修，避免水位越限。

Then, in the direction of the characteristic of the signal device fault, it works on the course model for realizing fault diagnosis, the composition of the expert system of fault diagnosis, and the method to develop a real system.

然后，针对信号设备故障的特点，对故障诊断实现的过程模型、故障诊断专家系统的构成及其实现方法进行了研究。

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

The early fault feature signal can be obtained by means of de-noising, decomposition and reconstruction.

文中对早期故障特征量的选取、有用信号与噪声信号的分离方法、突变信号与奇异信号的特征提取等进行了分析和研究，并以转子早期碰摩和早期不平衡为例进行了实验研究。

The circuit board fault detection and diagnosis system, which was designed for neotype weapon equipments, not only could resolve the problem that external test resources were too limited ,while there were too many quantities and types of circuit board test signals, but also could find the fault slug.

基于某新型武器装备的电路板故障检测诊断系统，不仅可解决外部测试资源有限，而电路板测试信号数量和类型过多之间的矛盾，而且可实现电路板故障定位，将故障定位到相应的元器件。

Starting from the signal of pressure and temperature, this paper does a series of theoretical and experimental researches on the following topics: the fundamental theory of the thermal parameter method, its field of application, the choice of diagnostic signal, the choice of the technologies on analysis of the signal, the foundation of the database of the fault samples, the application of the artificial nerve net technique and the error analysis of the experimental systems.

本文以参数法中的热力参数为研究对象，以压力、温度信号为研究信号，就热力参数法的基本原理、适用范围、诊断信号的选择、诊断信号分析技术的选择、故障样本库的建立、人工神经网络技术的应用及实验测试系统的误差分析等一系列问题展开了较深入系统的理论和实验研究。

The saltation coefficient of wavelet analysis was regarded as a characteristic value to predict a sudden accident and the changing trend of the coefficient was figured out. The results s...

结果表明：小波变换能有效捕捉冲击信号的时域特征和故障发生的时间历程，用小波分层突变系数所做的趋势图能有效地预测故障发展趋势，避免突发故障。

The wavelet packet analysis applied in fault diagnosis system is studied in this thesis. Using simulation fault data, uncalm and time difference vibration signal of sodium pump are decomposed on different levels and frequencies.

对小波包分析应用于故障诊断进行了研究，利用仿真出来的故障数据，将快堆钠泵非平稳时变振动信号分解到不同层次和不同频带上，有效地提取出反映钠泵不同故障的特征向量，在识别中得到了满意的结果。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。