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基于Hilbert-Huang变换的结构损伤诊断

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武汉理工大学学报 2004年第8期26卷 44-47页

作者：李书进虞晖瞿伟廉武汉理工大学土木工程与建筑学院武汉430070 武汉大学测绘学院武汉430079

对 Hilbert- Huang变换 (HHT)在结构损伤诊断中的应用进行了分析。 Hilbert- Huang变换是一种适用于非线性、非平稳信号 ,且具有自适应性的新的数据处理方法 ,将该方法应用于结构的反应分析 ,能有效地提取结构的损伤特征 ,从而对结构的... 详细信息

对 Hilbert- Huang变换 (HHT)在结构损伤诊断中的应用进行了分析。 Hilbert- Huang变换是一种适用于非线性、非平稳信号 ,且具有自适应性的新的数据处理方法 ,将该方法应用于结构的反应分析 ,能有效地提取结构的损伤特征 ,从而对结构的健康状况进行诊断。

关键词：损伤诊断 Hilbert-Huang变换 EMD方法结构健康诊断

ADJUSTMENT FACTORS AND ADJUSTMENT STRUCTURE

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大地测量与地球动力学 2003年第B12期23卷 19-22页

作者： Tao Benzao (school of geodesy and {2., wuhan university, wuhan 430079,china) school of geodesy and {2. Wuhan University Wuhan 430079China

In this paper, adjustment factors J and R put forward by professor Zhou Jiangwen are introduced and the nature of the adjustment factors and their role in evaluating adjustment structure is discussed and proved.

关键词：调节因子J 调节因子R 结构调整调节因子作用调节因子加权

A numerical study on nonlinear propagation and short-term variability of the migrating diurnal and semidiurnal tides

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Chinese Science Bulletin 2005年第17期50卷 1940-1948页

作者： HUANG Chunming1,2. ZHANG Shaodong1,2.& YI Fan1,2.1. school of Electronic Information, wuhan Universiy,{2., china 2. Key Laboratory of Geospace Environment and geodesy, Ministry of Education, wuhan university,{2., china school of Electronic Information Wuhan University Wuhan 430079 China Key Laboratory of Geospace Environment and geodesy Ministry of Education Wuhan University Wuhan 430079 China

By using a three-dimensional fully nonlinear numerical model in spherical coordinates and taking the linear steady solutions of the migrating diurnal and semidi-urnal tides in January from the Global-Scale Wave Model (GSWM) as the initial values, we simulate the linear and nonlinear propagations of the migrating diurnal and semidi-urnal tides in the atmosphere from the ground to the lower thermosphere. A comparison of our simulations with the results of GSWM is also presented. The simulation results show that affected by the nonlinearity, the migrating diurnal and semidiurnal tides propagating in the middle and upper atmosphere exhibit evident short-term variability. The nonlinear interactions between the migrating tides and the background atmosphere can obviously alter the background wind and temperature fields, which suggests that the nonlin-ear propagations of the migrating diurnal and semidiurnal tides impact significantly on the transient dynamical and thermal structures of the background middle and upper at-mosphere and the nonlinear effect is an important cause of the difference between the results of GSWM and observa-tions.

关键词：大气非线性传播数学模型可变性温度场

A novel method of systematic error compensation for a position and orientation system

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Progress in Natural Science:Materials International 2008年第8期18卷 953-963页

作者： Xiuxiao Yuan* school of Remote Sensing and Information Engineering, wuhan university,{2., china school of Remote Sensing and Information Engineering Wuhan University Wuhan 430079 China

A novel method is introduced for self-calibration and elimination of systematic errors for a position and orientation system (POS). The method uses a combined bundle block adjustment with POS data (named the POS-supported bundle block adjustment) without a calibration field. On the basis of delivering strict observation equations for POS data, the specific scheme of compensating the translation and drift systematic errors in a POS is given, and a prototype system WuCAPS is developed. The effects of eliminating POS systematic errors using the POS-supported bundle block adjustment for different ground control conditions are tested using two sets of actual aerial photos. The first set was taken over a flat region in the suburbs of the city of Yingkou in china and tested at a scale of 1:2.00. The second set was taken over a high mountainous region in the desert region of Xinjiang in china and tested at a scale of 1:32.000. The empirical results verified that the POS systematic errors can be completely eliminated and the photo elements of exterior orientation obtained by the POS-supported bundle block adjustment can satisfy the requirements of aerial photogrammetric topographic mapping when four full ground control points (GCPs) are emplaced in the corners of the adjustment block for large-scale images of flat regions, but only one full GCP emplaced in the center of the adjustment block is needed for medium-small scale images of mountainous regions. This not only demonstrates the validity of the established mathematical model and the feasibility of the method proposed in this paper, but also avoids the use of a special calibration field. Therefore, it can simplify the existing POS operation rules and dramatically save on practical application costs, laying the theoretical foundation for widespread use of POS.

关键词： Position and orientation system (POS) Systematic error POS-supported bundle block adjustment Self-calibration Accuracy

TEMPORAL SPATIAL VARIATION CHARACTERISTICS OF CRUST DEFORMATION OF ACTIVE TECTONIC BLOCKS IN NORTH china

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大地测量与地球动力学 2003年第B12期23卷 41-49页

作者： Xu Caijun, Li Zhicai and Wang Hua (school of geodesy and {2., wuhan university, wuhan 430079,china) school of geodesy and {2. Wuhan University Wuhan 430079China

Global Positioning System (GPS) observations during four measurement campaigns from 1992.to 1999 are used in a study of the temporal and spatial variation characteristics of crustal deformation of active tectonic blocks in North china. The Euler vectors for these active blocks are determined on the basis of GPS velocities of a group relative stable points in 1992.1995,1996 and in 1996,1999 respectively. We have studied the relative motion between blocks at the boundaries and the intra block deformation field. We have also inverted the strain rate fields for these active blocks by bi cubic spline model based on the GPS velocity field. The results show that the intra block deformation rates are different from those in block boundary zones, and are also different in different periods; the deformational field is generally characterized by intra-block extension in North china.

关键词：活动板块表层变形中国北方瞬时空间变化特性边缘区的运动应力等级场地质结构内部变形

Numerical study of the auroral particle transport in the polar upper atmosphere

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Science china(Technological Sciences) 2008年第10期51卷 1759-1771页

作者： CAI HongTao1,2. MA ShuYing1,2.& PU ZuYin3 1 school of Electronic Information, wuhan university,{2., china 2.Key Laboratory of Geospace Environment and geodesy, Ministry of Education of PRC,{2., china 3 school of Earth and Space Sciences, Peking university, Beijing 100871, china 1. school of Electronic Information Wuhan University Wuhan 430079 China 2. Key Laboratory of Geospace Environment and geodesy Ministry of Education of PRC Wuhan 430079 China 3. school of Earth and Space Sciences Peking University Beijing 100871 China

Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2., to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2.ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

关键词： aurora particle precipitation polar upper atmosphere electron transport equation numerical simulation

GRACE detection of the medium-to far-field coseismic gravity changes caused by the 2.04 Mw9.3 Sumatra-Andaman earthquake

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Earthquake Science 2012年第3期25卷 235-240页

作者： Jin Li1,2.3 and Wenbin Shen1,3,4, 1 Department of Geophysics, school of geodesy and {2., wuhan university, wuhan 430079, china 2.Key Laboratory of Geodynamic geodesy of Chinese Academy, wuhan 430077, china 3 Key Laboratory of Geospace Environment and geodesy (Ministry of Education), wuhan university, wuhan 430079, china 4 State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, wuhan 430079, china 1. Department of Geophysics School of Geodesy and Geomatics Wuhan University Wuhan 430079 China 2. Key Laboratory of Geodynamic geodesy of Chinese Academy Wuhan 430077 China 3. Key Laboratory of Geospace Environment and geodesy (Ministry of Education) Wuhan University Wuhan 430079 China 4. State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan 430079 China

Large earthquakes cause observable changes in the Earth’s gravity field, which have been detected by the Gravity Recovery and Climate Experiment (GRACE). Since most previous studies focus on the detection of near-field gravity effects, this study provides the results from the medium- to far-field gravity changes caused by the 2.04 Sumatra-Andaman earthquake that are recorded within GRACE monthly solutions. Utilizing a spherical-earth dislocation model we documented that large-scale signals predominate in the global field of the coseismic gravity changes caused by the earthquake. After removing the near-field effects, the coseismic gravity changes show a negative anomaly feature with an average magnitude of -0.18×10-8 m·s-2.in the region ranging ～40° from the epicenter, which is considered as the 'medium ffield' in this study. From the GRACE data released by Center for Space Research from August 2.02.to December 2.08, we retrieved the large-scale gravity changes smoothed with 3 000 km Gaussian ffilter. The results show that the coseismic gravity changes detected by GRACE in the medium field have an average of (-0.2.±0.06)×10-8 m·s-2. which agrees with the model prediction. The detection confirms that GRACE is sensitive to large-scale medium-field coseismic gravitational effects of mega earthquakes, and also validates the spherical-earth dislocation model in the medium field from the perspective of satellite gravimetry.

关键词： GRACE medium-to far-field coseismic gravity change 2.04 Sumatra-Andaman earthquake spherical-Earth dislocation model

Long Distance Transference of Height Datum Across Seas

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Geo-Spatial Information Science 2002年第3期5卷 1-5页

作者： LI Jiancheng JIANG Weiping professor,school of geodesy and {2.,wuhan university,12. Luoyu Road,wuhan 430079,china. school of geodesy and Geomaties Wuhan University

This paper focuses on studying long distance transference of height datum across seas by combining ellipsoidal height derived from GPS with gravimetric geoid *** Yellow Sea Height Datum is transferred to Yangshan Island which is 30 km away from Luchaogang in *** stations heights derived in this way are compared with those determined from two independent sets of the tidal observations taken in two years,and the difference values are 1.0 cm and 6.0 cm,***,the derived height differences between two sections on the island are also compared with the values derived from precise leveling with respect to the same *** result shows that the inconsistencies are only 0.2.cm and 0.7 cm,respectively.

关键词： GPS geoid height

Crustal Movement Patterns of china Continent Measured by GPS

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Geo-Spatial Information Science 2003年第4期6卷 57-60页

作者： YAO Yibin, Ph.D candidate, school of geodesy and {2., wuhan university, 12. Luoyu Road, wuhan 430079, china. school of geodesy and Geornatics Wuhan University Wuhan China

This paper uses multi-quadric equations interpolation to es-tablish a widely covered and valuablespeed field model of china, withwhich the horizontal crustal movementpatterns are obtained. The present-dayvertical crustal movement velocity im-age of china is also expressed by GPSobservations, from which we canknow the vertical crustal movementpatterns.

关键词： multi-quadric equations interpolation speed field model crustal movementpattern