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SAR tomography imaging via higher-order spectrum analysis 被引量:2
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作者 Wang Jinfeng Pi Yiming 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第4期748-754,共7页
To deal with the non-Caussian noise in standard 2-D SAR images, the deramped signal in imaging plane, and the possible symmetric distribution of complex noise, the fourth-order cumulant of complex process is introduce... To deal with the non-Caussian noise in standard 2-D SAR images, the deramped signal in imaging plane, and the possible symmetric distribution of complex noise, the fourth-order cumulant of complex process is introduced into SAR tomography. With the estimated AR parameters of ARMA model of noise through Yule-Walker equation, the signal series of height is pre-filtered. Then, through ESPRIT, the spectrum is obtained and the aperture in height direction is synthesized. Finally, the SAR tomography imaging of scene is achieved. The results of processing on signal with non-Gaussian noise demonstrate the robustness of the proposed method. The tomography imaging of the scenes shows that the higher-order spectrum analysis is feasible in the application. 展开更多
关键词 synthetic aperture radar 3-D imaging TOMOGRAPHY high-order spectrum analysis nongaussian
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The second order spectrum of two-dimensional random waves
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作者 Ding Pingxing Sun Fu and Yu Zhouwen 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1994年第1期23-29,共7页
On the basis of the second order solution of two-dimensional random gravity waves in finite uniform depth,which is rederived by a perturbation expansion method,the analytical expression of the second order spectrum is... On the basis of the second order solution of two-dimensional random gravity waves in finite uniform depth,which is rederived by a perturbation expansion method,the analytical expression of the second order spectrum is strictly deduced, and for infinite depth, the correct form of the kernel function is given for each octant do main.In fact,the present study improves and corrects the generally accepted results obtained by Tick 展开更多
关键词 The second order spectrum of two-dimensional random waves 五十
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Application of higher order spectrum in analysis of magneto-rheological damper control
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作者 刘晓梅 黄宜坚 陈俊杰 《Journal of Central South University》 SCIE EI CAS 2008年第S1期256-260,共5页
Higher order spectral analysis can be used to identify nonlinearities in the complex dynamical systems.This proposal shows that the contributions of the bispectrum,trispectrum,reconstructed bispectrum and reconstructe... Higher order spectral analysis can be used to identify nonlinearities in the complex dynamical systems.This proposal shows that the contributions of the bispectrum,trispectrum,reconstructed bispectrum and reconstructed power spectrum in terms of the system frequency response function and elementary physical properties of the MR damping system.Subsequent estimates of the HOS based on the output stochastic oscillating signals appear distinct variation.An experimental platform for MR vibrating semi-active control is built,proper simplifications are presented,an AR(10) model is established with colored noises from the output signals.Comparison between power spectrum from second order moment function and bispectrum,trispectrum are taken.The later gives an indication of the correlation between the phases of different frequency components.Since time series model is a parametric model,the reconstructed bispectrum and power spectrum are smooth.It is demonstrated that the higher order spectra are effectively for recognition and description of nonlinear systems. 展开更多
关键词 MRF vibrating CONTROL time SERIES HIGHER order spectrum BIspectrum trispectrum
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Role of Ordering Energy in Formation of Grain Structure and Special Boundaries Spectrum in Ordered Alloys with L12 Superstructure 被引量:1
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作者 O.B.Perevalova (Institute of Strength Physics and Material Science, Russian Academy of Sciences, Siberian Branch pr. Academicheskii, 2/1, 634048, Tomsk, Russia) E. V.Konovalova, N.A.Koneva and E. VKozlov (State University of Architecture and Building, Sol 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第6期585-590,共6页
It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special b... It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special boundaries in coincidence sites of ordered alloys. It was determined that the more energy of special boundaries in ordered alloys, the more energy of complex stacking fault. There is a correlation between the distribution of special boundaries as a function its relative energy and ordering energy: the more ordering energy, the more degree of washed away of distribution. The correlation between average relative energy of special boundaries and ordering energy was detected: the more ordering energy, the more average energy of special boundaries. The reverse dependence between ordering energy and average number of special boundaries in grains limited by boundaries of general type was discovered. 展开更多
关键词 Role of ordering Energy in Formation of Grain Structure and Special Boundaries spectrum in ordered Alloys with L12 Superstructure
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Influence of the initial electronic state on minima of high-order harmonic spectrum radiated from hydrogen molecular ion
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作者 崔会芳 苗向阳 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第10期194-199,共6页
We theoretically investigate the high-order harmonic generation of the one-dimensional hydrogen molecular ion at fixed intermediate internuclear distance, driven by a multicycle laser field. Our results show that the ... We theoretically investigate the high-order harmonic generation of the one-dimensional hydrogen molecular ion at fixed intermediate internuclear distance, driven by a multicycle laser field. Our results show that the initial electronic state of the hydrogen molecular ion affects the modulation of the high-order harmonic spectrum, especially the positions of the minima. Based on the two-state model, the underlying physical mechanism of the minimum is analyzed and discussed. Further analysis shows that the different positions of the minima in the different initial electronic states can be understood via the different interferences of the two phase-adiabatic states at the ionization times. 展开更多
关键词 the minima of the high-order harmonic spectrum INTERFERENCE phase-adiabatic states
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SPECTRUM DISTRIBUTION OF THE SEDOND ORDER GENERALIZED DISTRIBUTED PARAMETER SYSTEMS 被引量:2
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作者 葛照强 朱广田 马勇镐 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2003年第10期1224-1232,共9页
Spectrum distribution of the second order generalized distributed parameter system was discussed via the functional analysis and operator theory in Hilbert space. The solutions of the problem and the constructive expr... Spectrum distribution of the second order generalized distributed parameter system was discussed via the functional analysis and operator theory in Hilbert space. The solutions of the problem and the constructive expression of the solutions are given by the generalized inverse one of bounded linear operator. This is theoretically important for studying the stabilization and asymptotic stability of the second order generalized distributed parameter system. 展开更多
关键词 second order generalized distributed parameter system spectrum distribution Hilbert space generalized inverse one of bounded linear operatiors
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UV-Vis Spectrum and the Third-order Nonlinear Optical Properties of the Chiral Camphorderived β-diketonate Platinum Complexes 被引量:1
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作者 龚雪 卫航 +1 位作者 骆开均 李权 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2014年第3期422-428,共7页
UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G* level. The results showed that the introduction of electron-drawing g... UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G* level. The results showed that the introduction of electron-drawing group -CF3 and -C3F7 on β-diketonate made the strongest absorption peak red-shift and the lowest energy absorption blue-shied. Introduction of -OC2H5 on the benzene or pyridine ring made the lowest energy absorption blue-shift. When the -C2H3 was introduced on the benzene or pyridine ring, the lowest energy absorption was red-shifted. Introduction of electron-donating group on β-diketonate can enlarge their nonlinear optical properties. On the contrary, the introduction of electron-drawing group dropped it down. 展开更多
关键词 camphor-derived β-diketonate platinum complexes the third-order nonlinear optical properties UV-Vis absorption spectrum density functional theory
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基于Z-ordering的多重分形维数及多重分形谱算法 被引量:1
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作者 闫光辉 马志程 +2 位作者 刘利松 杜琳娜 杨霞霞 《计算机工程与应用》 CSCD 北大核心 2009年第9期146-150,共5页
分形维数的高效求解是分形理论应用与实践的关键问题,传统分形维数计算方法由于时空复杂性高已成为当前分形技术应用的一个主要瓶颈。借鉴Z-ordering索引技术的思想,设计并实现了一种改进的多重分形维数计算方法ZBMFD(Z-orderingBased M... 分形维数的高效求解是分形理论应用与实践的关键问题,传统分形维数计算方法由于时空复杂性高已成为当前分形技术应用的一个主要瓶颈。借鉴Z-ordering索引技术的思想,设计并实现了一种改进的多重分形维数计算方法ZBMFD(Z-orderingBased Multifractal dimension Algorithm),该方法扫描数据集一遍建立底层网格结构,通过动态修改网格坐标编码递推实现低层网格到高层网格之间的动态映射并计算数据集的分形维数。在实际数据集的实验表明算法在保持O(N×logN)时间复杂性的基础上,降低了分形维数算法的空间复杂性,且计算结果精度与已有算法相当,拓广了分形技术在当前高维、海量数据处理等领域的应用。 展开更多
关键词 分形 多重分形 分形维数 Z-ordering 多重分形谱
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基于阶梯波盲移频的LFM雷达干扰技术
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作者 张梦杰 赵忠凯 《电子信息对抗技术》 2026年第1期1-7,共7页
针对非整数阶盲移频干扰生成的欺骗干扰效果单一,假目标分布规律等问题,提出了一种基于阶梯波盲移频的线性调频(Linear Frequency Modulation,LFM)雷达干扰。设计了均匀阶梯波和非均匀阶梯波两种移频方法,推导了基于阶梯波盲移频的LFM... 针对非整数阶盲移频干扰生成的欺骗干扰效果单一,假目标分布规律等问题,提出了一种基于阶梯波盲移频的线性调频(Linear Frequency Modulation,LFM)雷达干扰。设计了均匀阶梯波和非均匀阶梯波两种移频方法,推导了基于阶梯波盲移频的LFM雷达干扰数学模型。该技术引入阶梯波函数对系统阶数进行调制,在系统延时不变的情况下,可以实现精确位置的欺骗假目标群或固定范围内的随机假目标。通过调整阶梯波函数的各项参数,可以完成对假目标位置、幅度和数量的控制。仿真验证表明,采用均匀阶梯波函数可以实现特定位置的密集假目标,采用非均匀阶梯波函数能够在特定范围内生成随机的假目标。对调频斜率捷变的雷达有着较强的干扰能力,具有较好的工程应用意义。 展开更多
关键词 非整数阶频谱扩展和压缩算法 阶梯波函数 欺骗干扰 压制干扰
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HIGHER ORDER SPECTRAL ANALYSIS IN FAULT DIAGNOSIS OF ROTORS 被引量:4
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作者 Yang Jiangtian Xu Jinwu School of Mechanical Engineering, Beijing University of Sicence and Technology 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2001年第1期40-44,共5页
The nonlinear properties of rotating machinery vibration signals are presented. The relationship between faults and quadratic phase coupling is discussed. The mechanism that gives rise to quadratic phase coupling is a... The nonlinear properties of rotating machinery vibration signals are presented. The relationship between faults and quadratic phase coupling is discussed. The mechanism that gives rise to quadratic phase coupling is analyzed, and the coupling models are summarized. As a result, higher order spectra analysis is introduced into fault diagnosis of rotors. A brief review of the properties of higher order spectra is presented. Furthermore, the bicoherence spectrum is employed to extract the features that signify the machinery condition. Experiments show that bicoherence spectrum patterns of different faults are quite different, so it is proposed to identify the faults in rotors. 展开更多
关键词 ROTOR Fault diagnosis Quadratic phase coupling Higher order spectra Bicoherence spectrum
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Solvothermal Synthesis, Structure and the Secondorder NLO Properties of a Novel Non-metal 3-D Borophosphate:(NH4)2[B2P2O8(OH)2] 被引量:2
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作者 FENG Yu-Quan ZHAO Qian BI Dong-Qin 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2019年第11期1909-1915,共7页
A new non-metal 3-D borophosphate compound formulated as(NH4)2[B2P2O8(OH)2](1)has been synthesized by a solvothermal method and characterized by elemental analysis,energy-dispersive X-ray spectroscopy(EDS),IR spectrum... A new non-metal 3-D borophosphate compound formulated as(NH4)2[B2P2O8(OH)2](1)has been synthesized by a solvothermal method and characterized by elemental analysis,energy-dispersive X-ray spectroscopy(EDS),IR spectrum and single-crystal X-ray diffraction.The borophosphate(NH4)2[B2P2O8(OH)2]crystallizes in the cubic system,space group P213 with Z=2,a=b=c=7.586(4)?,V=436.6(4)?3,Mr=281.64,Dc=2.127 g/cm^3,λ=0.71073?,μ=0.551 mm^-1,F(000)=284,R=0.0277 and wR=0.0758 for 262 observed reflections with I>2σ(I)and S=1.082.Its structure is constructed by the connection of PO4 and BO3(OH)tetrahedra to form a 3-D anionic framework containing 4-and 8-membered rings(MRs),with two NH4+cations located in the channels of the 8-membered rings.The N–H…O hydrogen bonds are observed in its packing structure and enhanced the stability of crystal structure.In addition,its thermal stability,UV spectrum and second-order NLO properties have been also investigated. 展开更多
关键词 SOLVOTHERMAL synthesis BOROPHOSPHATE UV spectrum SECOND-order NLO properties
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An 8-Connected Chiral Lanthanide Metal-organic Framework Constructed from Naturally Camphoric Acid:Crystal Structure,Vibrational Circular Dichroism Spectroscopy and Second-order Nonlinear Optical Effect 被引量:2
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作者 梁晓强 吴涛 樊增禄 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2016年第11期1736-1744,共9页
A chiral lanthanide metal-organic framework based on enantiopure camphoric acid (D-H2cam), [Nd3(D-cam)8(H2O)4Cl]n (1), has been synthesized and characterized by single-crystal X-ray structural analysis, elemen... A chiral lanthanide metal-organic framework based on enantiopure camphoric acid (D-H2cam), [Nd3(D-cam)8(H2O)4Cl]n (1), has been synthesized and characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Crystal data for the title compound are as follows: orthorhombic system, space group P212121 with a = 13.8287(7), b = 14.0715(7), c = 25.7403(12) A^°, V = 5008.8(4) A^°3, Mr = 1333.08, Z = 4, F(000) = 2644, Dc = 1.768 g/cm^3, μ(MoKα) = 3.189 mm^-1, the final R = 0.0351 and wR = 0.0814 (I 〉 2σ(I)). Compound 1 displays an 8-connected bcu topology 3D framework and hydrogen-bonding interactions stabilize the solid-state structure. The vibrational circular dichroism (VCD) spectrum and second-order nonlinear optical effect of compound 1 have been studied in the solid state. 展开更多
关键词 homochiral lanthanide metal-organic framework D-camphoric acid 8-connected VCD spectrum second-order nonlinear optical effect
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THE FOURTH-ORDER CUMULANTS BASED SPECTRALESTIMATION METHOD AND ITS APPLICATIONTO DIRECTION-FINDING
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作者 魏平 肖先赐 李乐民 《Journal of Electronics(China)》 1995年第4期330-335,共6页
Traditional approaches of spatial spectral estimation are usually based on the second-order statistics. The higher-order cumulants and the poly-spectrum contain more information and are capable of reducing the Gaussia... Traditional approaches of spatial spectral estimation are usually based on the second-order statistics. The higher-order cumulants and the poly-spectrum contain more information and are capable of reducing the Gaussian noise. In this paper, we present a new spectrum estimation method for direction-finding, the FOMUSIC algorithm, which is based on the eigen-structure analysis of the fourth-order cumulants. The derivation of the algorithm is given in detail and its performance is illustrated by both the computer simulations and the experiments of a direction-finding system. The obtained results demonstrate that the fourth-order cumulants based method outperforms the traditional methods, especially when the noise is an unknown colored one. 展开更多
关键词 Direction-finding SPATIAL spectrum HIGH-order CUMULANTS Poly-spectrum
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Asymptotic Value of the Probability That the First Order Statistic Is from Null Hypothesis
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作者 Iickho Song Seungwon Lee +1 位作者 So Ryoung Park Seokho Yoon 《Applied Mathematics》 2013年第12期1702-1705,共4页
When every element of a random vector X =(X1,X2,...,Xn)?assumes the cumulative distribution function F0?and F1?with probability p?and 1 - p, respectively, we have shown that the probability S0?that the first order sta... When every element of a random vector X =(X1,X2,...,Xn)?assumes the cumulative distribution function F0?and F1?with probability p?and 1 - p, respectively, we have shown that the probability S0?that the first order statistic of X?is originally under F0?can be expressed as . We have also shown that , where ?and ??with ?the support of F?i?(x)?. Applications and implications of the results are discussed in the performance of wideband spectrum sensing schemes. 展开更多
关键词 ENERGY order Statistic PROBABILITY spectrum SENSING
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Theory and Analysis for First-Order Interaction Between HF Radio Waves and Ocean Waves
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作者 周志鑫 陈振华 刘永坦 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1997年第2期81-85,共5页
TheoryandAnalysisforFirst┐OrderInteractionBetweenHFRadioWavesandOceanWavesZHOUZhixin(周志鑫)CHENZhenHua(陈振华)LI... TheoryandAnalysisforFirst┐OrderInteractionBetweenHFRadioWavesandOceanWavesZHOUZhixin(周志鑫)CHENZhenHua(陈振华)LIUYongtan(刘永坦)(Ele... 展开更多
关键词 High Frequency(HF) RADIO WAVE OCEAN WAVE first order INTERACTION Doppler spectrum Bragg Resonant
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3-D simulations of freak waves based on high-order spectral method
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作者 赵西增 孙昭晨 梁书秀 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2010年第2期286-291,共6页
Three-dimensional ( 3-D) directional wave focusing is one of the mechanisms that contribute to the generation of freak waves. To simulate and analyze this phenomenon,a 3-D wave focusing model is proposed based on the ... Three-dimensional ( 3-D) directional wave focusing is one of the mechanisms that contribute to the generation of freak waves. To simulate and analyze this phenomenon,a 3-D wave focusing model is proposed based on the enhanced high-order spectral method,which solves the fully nonlinear potential flow equations with a free surface within periodic unbounded 3-D domains. The numerical model is validated against a fifth-order Stokes solution for regular waves. Laboratory-scale freak waves are observed with wave components having equal amplitudes. Investigations of the appearance and propagation of freak-wave events in a 3-D open wavefield defined by a directional wave spectrum are then realized. 展开更多
关键词 freak wave high order spectral method directional spectrum wave focusing wave model
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基于高阶谱特征的雷达全脉冲转发干扰识别
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作者 刘一兵 陈柳廷 韩国强 《现代防御技术》 北大核心 2025年第6期149-155,共7页
雷达全脉冲转发干扰通过数字射频存储器件采样并根据不同的时序转发,由于单个脉冲内不包含其他调制特征,与回波信号具有高度的相似性,相较于其他干扰样式识别,特征参数提取难,差异性不明显。针对此问题,提出一种基于高阶谱特征的雷达全... 雷达全脉冲转发干扰通过数字射频存储器件采样并根据不同的时序转发,由于单个脉冲内不包含其他调制特征,与回波信号具有高度的相似性,相较于其他干扰样式识别,特征参数提取难,差异性不明显。针对此问题,提出一种基于高阶谱特征的雷达全脉冲转发干扰识别方法,根据高阶谱分析抑制高斯白噪声、包含相位信息等适用于处理非平稳信号的特点,提取特征参数构建特征向量,利用机器学习算法进行识别,最后通过实装和数学仿真相结合进行验证。仿真结果表明,在信噪比大于5 dB和25 dB时,识别正确率分别接近80%和95%,验证了算法的有效性,具有一定的工程应用价值。 展开更多
关键词 全脉冲转发 干扰识别 高阶谱 特征向量 机器学习
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Special algorithm of enhancing underwater targetradiated dynamic line spectrum
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作者 Guo Yecai Zhao Junwei Chen Huawei 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第4期797-801,共5页
Performance of traditional adaptive line enhancer (ALE) in suppressing Gaussian noise is low and can get worse at low input signal-to-noise ratio(SNR). For greatly overcoming these disadvantages, feature of fourth... Performance of traditional adaptive line enhancer (ALE) in suppressing Gaussian noise is low and can get worse at low input signal-to-noise ratio(SNR). For greatly overcoming these disadvantages, feature of fourth-order cumulant (FOC) different slices for quasi-stationary random process is analyzed, fourth order cumulant(FOC) different slice-based adaptive dynamic line enhancer is presented, and output SNR of the proposed enhancer is derived and bigger than that of the ALE via theoretical analysis. Simulation tests with the underwater moving target-radiated data have shown that the proposed enhancer outperforms the ALE in suppressing Gaussian noise and enhancing dynamic line spectrum feature. 展开更多
关键词 higher-order cumulant different slice dynamic line spectrum underwater moving target Gaussian noise.
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The Application of Three Order Cumulants Coupling Features in Fault Diagnosis
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作者 Wenbing Wu Rihua Liu 《International Journal of Modern Nonlinear Theory and Application》 2020年第4期81-89,共9页
Although mechanical vibration is extremely complicated, each fault signal produced by it has its own inherent features, The distinction may be most prominent between the certain components hidden in those features and... Although mechanical vibration is extremely complicated, each fault signal produced by it has its own inherent features, The distinction may be most prominent between the certain components hidden in those features and the same components of normal signals. Three-order cumulant can reduce the Gaussian background noise automatically and its complex formal includes different coupling information of its signal. In the experiment, through these different coupling modes, the same coupling components are fetched from specific fault signal and normal signal, then these components are used to diagnose that certain fault. The results show that the method can fetch the most prominent distinction between normal signal and the specific fault signal, so the specific fault diagnosis by this method is satisfactory. 展开更多
关键词 Three order Cumulant 1 (1/2) Dimension spectrum COUPLING Fault Diagnosis
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The Application of Coupled Three Order Cumulants’ Differential Feature in Fault Diagnosis
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作者 Wenbing Wu Jinquan Xiong +1 位作者 Yupeng Wu Rihua Liu 《International Journal of Modern Nonlinear Theory and Application》 2018年第2期77-87,共11页
Complex three-order cumulant has different definition forms. Different forms conclude different information. For studying the effection of frequency in the coupled signals to fault diagnosis, the differential method t... Complex three-order cumulant has different definition forms. Different forms conclude different information. For studying the effection of frequency in the coupled signals to fault diagnosis, the differential method to the three order cumulants of coupled signals is adopted. By using the differential of complex three order cumulants before and after respectively, then their ?dimensional spectrum is calculated, and the results are used to fault diagnosis. The experimental results show that, the increase frequency item in three order cumulants after differentiated impacts on the results of fault diagnosis and the degree of effection is relative to the differential times. And the correct rate of fault diagnosis can be raised by changing the differential times of three order cumulants. 展开更多
关键词 THREE order CUMULANTS DIFFERENTIAL COUPLED DIMENSIONAL spectrum FAULT Diagnosis
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