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INVESTIGATION OF TURBULENCE STRUCTURES AND TURBULENT COUNTER-GRADIENT TRANSPORT PROPERTIES IN STRATIFIED FLOWS

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Journal of Hydrodynamics 2006年第5期18卷 627-627页

作者： QIU Xiang Shanghai University Shanghai Institute of Applied Mathematics and Mechanics Shanghai 200072 China

Turbulence structures and turbulent Counter-Gradient Transport（CGT） properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and b... 详细信息

关键词： stratified turbulence counter-gradient transport coherent structure hilbert-huang transform

CRACK DETECTION OF BEAM-STRUCTURES BASED ON TRANSIENT WAVES

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CRACK DETECTION OF BEAM-STRUCTURES BASED ON TRANSIENT WAVES

2012全国压电和声波理论及器件技术研讨会

作者： Ji-qing JIANG Wei-qiu CHEN Gui-ru YE Department of Civil Engineering Zhejiang University City College Department of Engineering Mechanics Zhejiang University Department of Civil Engineering Zhejiang University

A method for crack detection in beam-structures is developed based on the transient waves under arbitrary external *** rotational springs are introduced for modeling cracked sections in a Timoshenko beam,and the wave responses of the perfect and cracked beams are calculated accurately by the reverberation-ray matrix *** it is hard to identify cracks from the wave responses directly,the hilbert-huang transform is employed to analyze the dynamic *** examples show that extra wavecrests can be observed from the hilbert spectrum of the cracked beam when compared with the perfect *** extra wavecrests are found to be generated by waves scattered from the cracked *** location of the crack can then be determined according to the wave speed and possible propagation path.

关键词： Cracked beam Transient wave Damage detection Reverberation-ray matrix method hilbert-huang transform

Application of HHT for Aerodynamic Instability Signal Analysis in Compressor

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Application of HHT for Aerodynamic Instability Signal Analys...

2011 3rd International Conference on Signal Processing Systems(ICSPS 2011)

作者： Li Changzheng Xiong Bing School of Power and Energy Northwestern Polytechnical University

ISBN: (纸本)9781457701726

The phenomenon of aerodynamic instability in compressor including stalls and surges is very complicated, and the mechanism is still not clearly understand by researchers. For disclosing characteristics of the phenomenon better, the hilbert-huang transform (HHT) was introduced in this paper. The outlet total pressure of a compressor was adopted as the indicate signal of aerodynamic instability. In the HHT, firstly, the pressure signal was decomposed into several intrinsic mode functions (IMFs) with the empirical mode decomposition (EMD) method. Then, the hilbert transform was carried out on each IMF. Finally, the time- frequency chart of the outlet total pressure was constructed. The analysis disclosed that: 1) the EMD method can decompose the outlet total pressure signal into the noise component, the stall component, the surge component and the others IMFs;2) when the compressor operates in a steady state, the energy of the signal distributes evenly on the frequency band, while in aerodynamic instability state, the energy concentrates on the surge frequency and the stall frequency, the signal pulse intensity increasing significantly;3) the type of aerodynamic instability of this compressor is surge companied with rotating stall.

关键词： hilbert-huang transform compressor stall surge aerodynamic instability

Research of Harmonics Measurement Aalgorithim Based on HHT

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Research of Harmonics Measurement Aalgorithim Based on HHT

2012 International Conference on Future Energy,Environment,and Materials

作者： ZHANG Shaoyong Hohai University

The measurement of power parameters is one of the most basic calculation in power systems, it plays a key role on running power systems in security, economy and reliability. This thesis studys the application of the hilbert-huang transform in the field of nonstationary electric power signal in the aspects of amplitude nonstationary, on which the traditional methods work not very well. Much MATLAB simulation shows that HHT is more suitable than DFT to analyze the nonstationary electric power signal. HHT is excellent in the amplitude nonstationary signal analysis. In this thesis, the structure, the function, the communication mode, the application and the trend of development of Power Analyzer are analyzed. Finally, a self-developed chip named Power Analyzer used for measuring of power parameter based on TMS320F2812 processor is designed. The instrument can attain 0.2 grade of RMS, 0.2 grade of power and high-precision measurement of 2 to 31 harmonics. Its real-time performance is very good.

关键词： hilbert-huang transform Stationary electric power signal Nonstationary electric power signal EMD

Research on Properties of hilbert Spectrum

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Research on Properties of Hilbert Spectrum

2007 8th International Conference on Electronic Measurement & Instruments（ICEMI’2007）

作者： Ren Zhong Zhang Haiyong (Department of Information & Communication Engineering Dalian Naval Academy Dalian 116018 China)

＜正＞hilbert-huang transform（HHT） is a new method of processing non-stationary *** method consists of two parts:the empirical mode decomposition（EMD）,and the hilbert spectral *** method is *** properties of it are ***,hilbert spectrum is linear,and it satisfies the principle of superposition without the cross-term interferences which exist in Wigner-Ville ***, hilbert spectrum has local property,and compared to wavelet analysis,it has excellent time-frequency *** addition,hilbert spectrum has real number ***,it has the adaptive frequency multi-resolution *** from simulation experiment are given to demonstrate the power of the *** properties are of great importance to its application in measurement data processing.

关键词： Non-stationary signal Time-frequency analysis hilbert-huang transform hilbert spectrum Adaptive frequency multi-resolution propertiy

基于边缘计算的配电网雷电过电压在线监测系统的研究

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基于边缘计算的配电网雷电过电压在线监测系统的研究

作者：高辉山东大学

学位级别：硕士

配电网作为电力系统与电力客户之间的桥梁与纽带,其安全稳定运行直接影响电力系统的供电可靠性;综合统计分析配电网运行数据,雷击故障为影响配电网安全稳定运行的重要因素。随着经济社会的不断进步,配电网覆盖范围、规模日益扩大,新能... 详细信息

配电网作为电力系统与电力客户之间的桥梁与纽带,其安全稳定运行直接影响电力系统的供电可靠性;综合统计分析配电网运行数据,雷击故障为影响配电网安全稳定运行的重要因素。随着经济社会的不断进步,配电网覆盖范围、规模日益扩大,新能源、新负荷等不断接入,传统配电网防雷手段及运行管理模式已无法满足电网飞速发展及电力客户对供电可靠性的要求。因此,为保障配电网安全稳定运行,确保不间断的电力供应,加强配电网雷电过电压在线监测系统的研究,具有重要的理论意义和重要的工程实用价值。首先,在详细论述雷电产生机理、雷电参数、线路防雷性能指标及跳闸条件、雷电过电压类型、对比各类防雷原理和防雷措施优缺点的基础上,针对雷电过电压类型识别问题,对希尔伯特-黄变换(hilbert-huang transform,HHT)和小波变换两种算法分别进行了深入分析;小波变换方法能够进行多分辨率分析,但其本质为一种恒定多分辨分析方法,且存在对不同种类过电压有最优小波基选择的问题,HHT能够分析线性信号、非线性及非平稳型号,采用HHT算法进行雷电过电压类型识别具有优越性。其次,统计分析了枣庄地区配电网防雷现状及存在问题,通过仿真深入研究配电网雷电过电压问题。详细论述了不同条件下直击雷过电压、感应雷过电压计算方法;结合枣庄配网特征,选取双指数的雷电流、***架空线路、柱式复合绝缘子闪络等元件模型,搭建10kV配电线路的仿真模型,进行不同条件下的雷击过电压仿真研究;通过对短路故障识别仿真分析,未发生故障的雷击、反击故障、绕击故障、感应雷故障过电压仿真分析,获得各类过电压特征,为雷电过电压识别分类提供判据。最后,详细叙述了系统的开发思路,构建了基于边缘计算的雷电过电压在线监测系统框架结构;详细分析了系统各单元部分的原理,基于HHT的数据分析模块提取过电压特征量;基于HTML和Javascript搭建了系统的前端用户界面,实现对边缘设备的在线监测;采用MySQL的数据服务器,实现数据统计分析、故障点判定。该系统能够提升配电网线路防雷能力、加快雷击事故应急处理效率,为提高配电网供电可靠性,提供强有力的支撑。

关键词：配电网雷击过电压边缘计算 hilbert-huang transform 在线监测

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基于GARCH和HHT的散户投资研究

基于GARCH和HHT的散户投资研究

作者：林达湖南大学

学位级别：硕士

股票市场的收益和波动一直是各界关注的焦点,在各方面机制尚不完善的A股市场,被发达国家投资者普遍认可的长期投资、集合化投资、指数化投资等理念受到了质疑,目前投资界虽已有大量相关讨论,但分歧较大,且停留于经验之谈、案例分析层面... 详细信息

股票市场的收益和波动一直是各界关注的焦点,在各方面机制尚不完善的A股市场,被发达国家投资者普遍认可的长期投资、集合化投资、指数化投资等理念受到了质疑,目前投资界虽已有大量相关讨论,但分歧较大,且停留于经验之谈、案例分析层面,有待更严谨的论证。本文在介绍现有时间序列分析工具——GARCH模型族和hilbert-huang transform的基础上,选取上证指数、深证综指、混合型基金指数作为A股市场的代表性指数,对我国股票市场的收益、波动展开了深入的研究,利用实际业绩资料和热门网络论坛后台数据评估了专业投资机构和中小投资者的投资能力。最后,总结收益和波动规律,分析散户的弱点,得出以下面向中小投资者的结论和投资建议：(1)我国混合型基金配置股票资产能力较强,能灵活应对大小盘股分化和风格切换迅速的行情。(2)对于普通投资者而言,购买混合型基金明显优于直接购买股票,一是因为期望收益率更高,波动率更低;二是因为散户自行操作的业绩较差,甚至远低于市场基准。(3)混合型基金的平均业绩高于沪深两个市场基准证明了主动管理在A股市场的有效性,美国市场由于对冲基金管理费昂贵和市场有效程度更高,结论与此相反。(4)长期投资在A股市场同样适用,且最具长期投资价值的标的是采用主动管理策略的基金,其次是中小盘股,而大盘蓝筹股长期投资回报较低。严格奉行长期投资策略却收益不佳的主要原因是牛市末期入场或投资组合中蓝筹股占比过高。本文不仅运用了较为先进的计量方法,并且根据A股二级市场特征慎重选取了最具代表性和真实性的原始数据,对实证结果进行了贴近投资实践的解读,密切联系理论与实际,为投资者尤其是散户提供参考。

关键词：股票基金 GARCH hilbert-huang transform 散户

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基于希尔伯特黄变换的滤波器设计

基于希尔伯特黄变换的滤波器设计

第十二届全国信号处理学术年会（CCSP-2005）

作者：刘卓夫廖振鹏桑恩方中国地震局工程力学研究所哈尔滨工程大学水声工程学院

对希尔伯特黄变换理论进行了简要地介绍,研究了希尔伯特黄变换的经验模态分解过程和有噪信号的固有模态函数特征。通过研究,设计了一种基于希尔伯特黄变换的滤波器。将该滤波器应用于信号去噪,收到了满意地效果。

关键词： hilbert-huang transform speech enhancement empirical mode decomposition intrinsic mode function