In the recent years , as the proportion of mechanic industry in nation economy increases , the requirement for safe operation of mechanic equipment is higher and higher . due to that all kinds of technology are progressively applied to mechanic equipment fault and diagnosis , such as signal processing , pattern recognition , etc . , mechanical equipment fault and diagnosis technology has been developed rapidly all over the world . the reciprocating pump as a part of mechanic equipment field takes up very important station in production department , such as the petrochemical industry . because its applications are very widely , making researchs about its fault and diagnosis has important meaning . though people have already made out some researchs and obtained some research results , but the total diagnosis level is not still very high . based on former research results , according to the strong non - stationary characteristic of the pump valve signal of the reciprocating pump , this text introduces hilbert - huang transform ( abbreviated as hht ) , and diagnosed the pump valve faults of the reciprocating pump well 虽然人们已对其开展了不少研究并取得了一些研究成果,但总的诊断水平还不是很高。本文在基于前人研究成果的基础上,根据往复泵泵阀信号的强非平稳特性,引入了希尔伯特-黄变换(简称hht ) ,对往复泵泵阀较好地进行了诊断。往复泵由于其结构复杂,激励源多,故其信号为强非平稳信号,对其进行故障特征提取和诊断比较困难,所以本文主要研究了往复泵泵阀振动信号的特征提取方法。
As we all known , with the founding of euclidean geometry in ancient greece , with the development of analytic geometry and other kinds of geometries , with f . kline " s erlanger program in 1872 and the new developments of geometry in 20th century such as topology and so on , man has developed their understand of geometry . on the other hand , euclid formed geometry as a deductive system by using axiomatic theory for the first time . the content and method of geometry have dramatically changed , but the geometry curriculum has not changed correspondingly until the first strike from kline and perry " s appealing 纵观几何学发展的历史，可以称得上波澜壮阔：一方面，从古希腊时代的欧氏综合几何，到近代解析几何等多种几何的发展，以及用变换的方法处理几何的埃尔朗根纲领，到20世纪拓扑学、高维空间理论等几何学的新发展，这一切都在不断丰富人们对几何学的认识；另一方面，从欧几里得第一次使用公理化方法把几何学组织成一个逻辑演绎体系，到罗巴切夫斯基非欧几何的发现，以及希尔伯特形式公理体系的建立，极大地发展了公理化思想方法，不管是几何学的内容还是方法都发生了质的飞跃。
To solve this problem , some researches on denoising for the nonstationary and noisy - strong signal are carried out in this paper . combining hilbert - huang transform ( hht ) which has been proved to be more valid in the aspect of time - frequency analysis , with mature wavelet transform ( wt ) threshold theory , an emd - based wavelet threshold denoising algorithm is presented 针对这个问题,本文也开展了对信噪比较低的含噪非平稳信号的去噪研究工作,并将具有比小波变换更强时频分析能力的希尔伯特?黄变换( hht )与成熟的小波阈值理论相结合,提出基于emd的小波阈值去噪算法。
We propose a chaos - based generation of the random ppm - ps signals , design and implement a generator of the ppm - ps signals . we introduce an if sampling technique and simulate the performances of digital demodulation techniques of using hilbert filters , sine filters , bessel filters and poly - phase filters . the poly - phase filtering method can achieve the higher mirror - frequency rejection ratio by using the low order filters 介绍了中频采样技术，并对希尔伯特滤波法、辛格内插函数修正、贝赛尔函数插值法及多相滤波法等数字解调算法进行了计算机仿真和性能比较，指出多相滤波法能以较低的阶数实现较高的镜频抑制比。
The ship radiated noise is analyzed and its 4 features are extracted from the envelop spectrum . the envelope of ship noise waveform can be demodulated utilizing hilbert transform , and the spectrum components with line rotation frequency of propeller shaft are extracted effectively by bispectrum , 1 ( 1 / 2 ) spectrum and 2 ( 1 / 2 ) spectrum analysis 对于通过希尔伯特变换解出的舰船辐射噪声包络信号进行高阶统计量分析，有效地提取出了舰船噪声的双谱、 11 / 2维谱、 21 / 2维谱等方面的特征。
There are two kinds of capacitites depending on the informatoion being transmitted , when we use quantum channel to transmit 0 , 1 seriels we talk about classical capacity , while an unknown quantum state is transmitted , we think of quantum capacity . in the first three chapters , we will concentrated on classical capacities of quantum channels . in chapter 1 an overview is given for the general results of classical capacities of quantum channels as well as a breif introduction to quantum information and basic notations 量子信道的容量有两类；一类是用量子信道传输经典信息，如在光纤上传输0 、 1串，量子态为已知，这时我们谈论经典信息容量，我们将在前三章中讨论，另一类是量子信道传输未知的量子态，这时我们要考虑的是量子信息，是整个希尔伯特空间的传输，其内部的态，纠缠等包含量子相位信息的部分不能被破坏，我们将在后三章中讨论。
First of all , the emd - based wavelet threshold denoising algorithm is apllied to denoise noisy structural response data to reduce the effect resulting from noise . during the process of the empirical mode decomposition ( emd ) , the two boundaries of the response signal are processed with semi - periodical ? semi - symmetrical method . subsequently , hilbert - huang transform ( hht ) is used in identifying structural intrinsic frequency 这套技术用以解决实际工程应用中遇到的在信噪比较低情况下通过结构的响应信号来进行结构损伤识别问题,即先用基于emd的小波阈值去噪算法对含噪结构响应进行去噪处理,以有效降低噪声影响(在去噪的emd处理过程中,对信号的边界采用“半周期半对称”延括算法来抑制边界误差) ,然后再用希尔伯特?黄变换( hht )进行结构的固有频率识别,最后计算出结构刚度。
Because reciprocating pump has complicated structure and more exciters , so its signal is a strong non - stationary signal , and carrying out fault feature extraction and diagnosis is very difficult to it , this text mainly researches on featute extraction of reciprocating pump ’ s valve vibration signal . this text introduces hht that huang put forward , it is a kind of signal processing method that suits for dealing with the stationary signal , and suits for non - stationary signal also . although the hilbert - huang transform ( hht ) is an effective tool processing the non - stationary signal , the hht based on emperical mode decomposition ( abbreviated as emd ) algorithm which adopts the cubic spline interpolation could n ' t acquire accurate characteristics for the strong non - stationary signals in that the spline produces an accurate result only under the condition that the data consists of values of a smooth function 本文引入了huang等人提出的hht , hht是一种既适合于处理平稳信号也是一种适合于处理非平稳信号的信号处理方法。尽管希尔伯特-黄变换( hht )是处理非平稳信号的有效工具,但基于经验模态分解(简称emd )的hht由于采用三次样条插值而不能准确提取强非平稳信号的特征,因为三次样条插值只有在数据由光滑函数值构成的情况下才能产生精确的结果。为了解决这个问题,本文提出了基于改进的emd算法,即采用分段三次hermite插值多项式( pchip )作为极值包络的方法。
Firstly , a method to estimate the rotor speed , which is based on bp neural network , is introduced in this paper . secondly , the park vector approach is used to monitor and diagnose the inter - turn fault of the stator winding . finally , this paper studies thoroughly a novel approach to detect rotor bar breaking fault , which is based on the perfect combination of the hilbert transform and digital filter 具体工作如下：采用bp神经网络对异步电动机转子转速进行无速度传感器估计；对定子绕组匝间短路故障，采用派克矢量方法进行监测与诊断；对于转子断条故障，详细介绍了一种新的基于希尔伯特变换与数字滤波的在线监测方法。
It can also determine the fault spot and reason . this technology has been used in some technological fields and proved efficient . it has promoted the revolution of maintance system and the historial protection is replaced by preventive maintenance . with this technology , we can improve the reliability of machine and decrease the maintance fee . recently , reserch has pick up a fervent pace in the area of fault diagnosis of electrical machines . the paper simply analyzes the fault reason of electrical machines , stressly describes and explores the methods of condition monitoring and fault diagnosis such as partial discharge , stator current , rotating speed , vibration etc . fault prognosis is now include diagnostic feature , reason , spot . prodigious improvement in signal processing hardware and software has made this possible . primarily , these techniques depend on locating specific harmonic components of the fault . these harmonic components are usually diffirent for diffirent types of faults . automated tools such as fuzzy logic based system is also simply presented in the paper 本文从绝缘结构的故障机理入手，以绝缘结构故障的典型特征? ?局部放电为研究对象，重点讨论局部放电的在线监测方法、适用场合并比较它们的优缺点；在分析笼型异步电机转子断条在线监测的定子电流监测方法后，根据其缺陷，本文探讨了温升不平衡法、希尔伯特变换数字滤波、小波包分析法的原理及优点；以电机轴承、气隙偏心等故障为研究对象，通过对电机振动和转速频率的检测，诊断电机的故障类型；本文的重点工作是将人工智能技术中的模糊技术应用于电机的状态监测和故障诊断中，力求使电机故障诊断更接近人工智能化；最后，本文对电机状态监测和故障诊断系统进行了硬件和软件初步设计，为实现预测维修提供了有效的技术手段。
