故障

Based on varying process of generator terminal parameters after excitation fault, shortages of excitation protective principle of static stability boundary and asynchronous impedance boundary are analyzed. It proposed that excitation fault research relates to large-disturbance stability. Because dynamic power-angle character of generator after excitation fault is non-sinusoidal, there are differences between dynamic power-angle character and static state power-angle character. So it isn't ideal to protective operation result based on small-disturbance stability and static stability boundary criterion. At the same time, it proposed that asynchronous boundary impedance criterion is a constant reactive power circle moving adown j Xd′. It can ensure complete loss-of-excitation generator measuring impedance enter into the circle, but can't ensure the other condition measuring impedance including impossible losing synchronism enter. So loss-of-excitation protection would be maloperation when system voltage drops short and recovers or generator rejects load.③Based on stability principle, it puts forward setting conditions and calculation method of generator loss-of-excitation protection by direct measuring power-angle.

以励磁故障后发电机端的相关参数的变化为基础，通过对以静稳定边界和异步阻抗边界作判据的两类三种现行励磁保护在原理上存在的缺陷分析，发现：励磁故障是一个大干扰稳定性问题，励磁故障后的发电机的动态功角特性与静态功角特性有很大的差异，已远非正弦曲线，因此基于小干扰稳定性原理、以静稳定边界作判据的保护必然动作不理想；异步边界阻抗判据是一个下移j Xd′的等无功阻抗圆，它可以保证完全失磁后的发电机测量阻抗能进入该阻抗圆，但不能保证完全失磁之外的其它状态不会进入该阻抗圆，因此在系统电压短时下降或发电机突然甩负荷等情况下可能启动该保护使之误动。

Airworthiness compliance is an important way to ensure the safety of civil aircraft operation.

研究了功能危险分析、故障树分析、故障模式影响分析以及共因故障分析等安全性分析方法在民用飞机适航符合性验证中的应用，明确了各种方法的应用时机与输入输出信息。

I had experienced oxygen andor engine trouble.

我曾碰到过，不是氧气设备出故障，就是引擎出故障，或二者都出故障。

So there need not only no failure but working in a stably good condition in the ignition system, the using condition and adjust of the use factors are the most important thing for the system performance. The paper analyses the characteristics of electronic ignition system, points out that determinant use factors are mainly the voltage of battery, the occupy-emptiness rate of the ignition signal, the clearance of spark plug, the resistance of high-voltage part, and the cam angle of spark advance.

本论文重点分析了电子点火系统故障特征，论证了决定电子点火系统性能的使用因素主要有电瓶电压、点火信号发生器发出电压信号的占空比、火花塞间隙、高压阻抗、点火提前角，这些因素在点火系使用过程中故障率占点火故障比例最大，故障出现的频率最高，而且有时常因维修调整不当导致点火系统性能变差。

Aiming at the signal processing problems that exist in online fault diagnosis for train running gear, based on discussing the principle of characteristic spectrum analysis, a method of full period and uniform angle sampling is applied, which transfers the vibration signal from time domain into angular domain. The angular domain signal is transferred into corresponding characteristic spectrum using FFT. Through spectrum estimation and analysis, fault characteristic spectrum values of running gear components are acquired to distinguish their faults.

在讨论特征分析方法原理的基础上，针对机车走行部故障在线监测过程中存在的信号分析与处理问题，运用整周期等角度采样方法将时域振动信号转换为角域信号，采用FFT变换将角域信号变换为对应的特征频谱，通过谱估计、谱图分析得到机车走行部各零部件的故障特征谱值，再根据该特征谱值识别机车走行部各零部件的故障。

The approximation theorem of the rough neural network is proved. Then the method is applied to the fault verification of fighter plane, the simulation results show that the rough neural network is efficient.

最后将此方法应用于歼击机的故障认定系统，仿真结果表示，此粗糙神经网络可以很好地对具有区间数的歼击机故障认定系统进行故障认定。

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。

This thesis is mainly focus on the fault forecast problem of compressor, that is, on the basis of the relationship of the gathering correlative parameters of compressor (such as compressive stress of exit or entrance、temperature、oscillation of axletree、the quantity of leaking gas and so on), concluding the possible reason of the fault, taking effective measures to avoid economic lost from shutting down of the fault of equipments.

本论文研究的主要内容是压缩机的故障预测问题，即根据采集到的压缩机的相关参数（如：出/入口压力、温度、轴承振动、泄漏气量等）之间的关联关系推断出可能的故障原因，采取有效措施，避免因设备故障停车造成的经济损失。

These algorithms can resolve efficiently the two difficult problems in aero\|engine fault diagnosis, e.i., reduce the number of fault factors in the fault equation, and improve its abnomal condition.

这两种算法可以有效地解决发动机故障诊断中的两个技术难点，即减少故障方程中故障因子的个数以及克服故障方程的多重共线性的不良影响。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷