故障分析

To make paper more systematic and practical, this paper has first introduced the development history of CT equipment, then, elaborate construction of system and theworking principle of CT equipment systematically, including the property of X-ray, the absorption law of X-ray for materials, the reconstruction principle of CT image, the structure of software and hardware for CT equipment. Finally, with 2 CT systems that we used, statistic and analysis of all the malfunctions which have carried out in passed 10 years was given, and according to the systematic parts of fault located, classify the malfunctions, then elaborate their working principle one by one, analyze the regularity and the characteristic of each malfunction, and put forward specific prevention method and measure for the malfunction.

为了使论文更具系统性和实用性，本论文首先介绍了CT设备的发展史，然后比较系统地阐述CT设备的工作原理及系统结构，包括X射线的特性和物质对x射线的吸收规律，CT图像的重建原理，CT设备的软、硬件结构等，最后以我们所使用的2台CT为例，对10余年来所出现的故障进行了全面的统计分析，并按故障所处的系统部件进行分类，然后逐个阐述其工作原理，分析其故障的特点和规律，并就这些故障提出具体的预防方法和措施。

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。

Base on the in-depth analysis into the phase-to-ground fault mechanism and its features, the new concept is presented, which is to change the reference signal for analyzing and processing from the steady signal to the transient signal in a fault case A new principle of the fault feeder line selection with the synthetic logical criterion is presented creatively, which is based on the waveform recognition of the selected time-frequency window.

在深入分析单相接地故障的机理及故障特征的基础上，提出了从基于稳态信号原理转到基于故障暂态信号去分析和处理的新概念；创造性的提出了基于选线时频窗波形识别的综合性逻辑判据的故障选线新原理。

The main study in the paper is as follows: Firstly, discussing the purpose of carrying on hydropower units fault diagnosis, then, introduce state of the art and classical method in the field of fault diagnosis in hydroelectric sets. The mechanism, major failure and failure symptom of hydropower units, three methods that can identify unit's vibration fault. With the key technology of monitoring on hydropower sets together with the viberation signal-disposed and fault feature-extracted are analysised.

本文主要进行了以下工作：从水电厂实际出发，阐述了开展水电机组故障诊断研究的重要意义与目的，简要介绍了国内外水电机组故障诊断技术发展现状以及目前应用于故障诊断领域的常用方法，系统地分析归纳了水电机组振动的机理、主要故障及其故障征兆、识别水电机组振动故障原因的三种方法，以及水电机组监测的关键技术和故障特征提取技术。

The feasibility,effectiveness and limitation of four improvement measures are studied:raise protection settings or prolong protection delay;apply inverse time limit ;use additional criterion to distinguish valve fault from AC system fault;and adjust 100 Hz protection configuration principle.

为减小交流系统故障期间直流100Hz保护动作的概率，利用PSCAD/EMTDC仿真分析软件，就阀故障和交流系统故障时直流线路50Hz/100Hz电流特性进行了分析，研究了提高保护定值或延长保护动作延时、采用反时限特性、利用附加判据区分交流故障和阀故障、调整直流100Hz保护配置原则4种措施的可行性、使用后的效果及局限性。

In this paper we begin with the electrical principle of the oxygen sensor, analyze the motive detecting method of the oxygen sensor in the LS400 car with the two-dimensional coordinator and explain the way to recognize the fault codes with oscillogram, finally illuminate the meaning of the different fault codes.

在修理发动机电控系统故障时，最想看到的就是发动机故障指示灯有规律地闪烁但有些故障需要在一定条件下，采用一定的方法才能检测到其故障代码，氧传感器的故障代码就属于这种代码通过对氧传感器的电路原理的分析，利用二维坐标图形论述了凌志LS400型轿车氧传感器的动态检测方法，并用波形图说明了该种车型的故障码识别方法，最后指出了不同故障码的意义。

The uniform approximation of normal wavelet neural network and the robust analysis of wavelet neural networks of the combination of Sigmoid function are detailedly introduction; Multiple model failure detection based on wavelet neural network is demonstrated detailedly; At last, the failure diagnosis results of aerocraft is present seperately by employing wavelet neural network and BP neural network, and the fault diagnosis of areocraft system by wavelet neural network is achieved.

论文以小波神经网络为研究对象，提出了一类新的加权小波基，分析证明了加权小波基的诸多良好特性；对于常见小波神经网络的一致逼近特性、S型函数组合小波神经网络的鲁棒性分析、多模型小波神经网络的故障检测等问题给出了详细的论证；最后，针对歼击机的常见故障问题，分别给出了应用小波神经网络和BP神经网络的故障诊断结果，实现了小波神经网络对飞机系统的故障诊断。

The damage analysis of cracked turbine disk in the rocket engine is described. From a series of analyses, the causes of failure were reasoned through calculation and experiments, fatigue analyses which include stimulating vibration test and fatigue strength calculation were emphasized.

针对某火箭发动机涡轮盘在热试车中出现的裂纹故障，进行全面的分析，准确定位故障类型，以试验和计算分析给出合理的故障原因，重点是在疲劳分析方面所做的工作，包括振动模拟试验、疲劳强度计算，并根据疲劳强度分析结果提出改进方案。

This article analyzes systematically the work process of fuel injection system in detail. It analyzes the fault fundamentals and its influence of three coupling parts in the high pressure oil road and the injection process, three coupling parts include plunger coupling parts, delivery valve coupling parts and needle valve coupling parts. It discusses the pulse situation of fuel pressure under the every kind of typical fault model, and regarding this as according to pick up the pulse signal of pressure from the high pressure pipeline, and process wavelet decomposition, picks up the of parameter fault, make use of the model identification technique, realizes to the intelligent diagnosis of fuel injection system fault.

文中系统地分析了燃油系统的工作过程，对高压油路中三偶件(柱塞偶件、出油阀偶件、针阀偶件)、喷油过程等的故障机理及其影响进行了分析，讨论了各种典型故障状态下的燃油压力波动情况，并以此为根据，从高压油管处提取压力波动信号，提取故障参数，利用模式识别技术，实现了对燃油系统故障的智能化诊断。

On the basis of the characteristics of line boundary, this paper analyzes the different features of internal and external faults. The difference is that the ratio of high frequency to low frequency components in case of one external fault is less than that in case of the same internal fault, in which high frequency is in the band of line trap and low frequency is within 1~10kHz.

在线路边界频率特性的分析基础上，深入地分析了区内外故障时的特征差异：就某一类故障而言，区外故障时反行波中高频分量与(1~10kHz内的)低频分量的比值显著小于区内故障时的比值。

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。