共查询到20条相似文献，搜索用时 31 毫秒
1.
地球的时变主惯性矩和变化的自转(英文) 总被引：1，自引：0，他引：1
SHEN Wenbin CHEN Wei SUN RongSHEN Wenbin School of Geodesy Geomatics Wuhan University Luoyu Road Wuhan China The Key Laboratory of Geospace Environment Geodesy Wuhan University Luoyu Road Wuhan China. 《地球空间信息科学学报》2008,(2)
Based on the gravity field models EGM96 and EIGEN-GL04C, the Earth's time-dependent principal moments of inertia A, B, C are obtained, and the variable rotation of the Earth is determined. Numerical results show that A, B, and C have increasing tendencies; the tilt of the rotation axis increases 2.1×10-8 mas/yr; the third component of the rotational angular velocity, ω 3, has a decrease of 1.0×10-22 rad/s2, which is around 23% of the present observed value. Studies show in detail that both θ and ω 3 experience complex fluctua-tions at various time scales due to the variations of A, B and C. 相似文献
2.
Rotation of the Earth as a Triaxial Rigid Body 总被引：2，自引：6，他引：2
SHEN Wenbin CHEN Wei WANG Wenjun LIANG Yiqiang 《地球空间信息科学学报》2007,10(2):85-90
The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated. 相似文献
3.
Due to the super rotation of the Earth＇s inner core, the tilted figure axis of the inner core would progress with respect to the mantle and thus cause the variation of the Earth＇s external gravity field. This paper improves the present model of the gravity field variation caused by the inner core super rotation. Under the assumption that the inner core is a stratifying ellipsoid whose density function is fitted out from PREM and the super rotation rate is 0.27-0.53°/yr, calculations show that the global temporal variations on the Earth＇s surface have a maximum value of about 0.79-1.54×10^3 pGal and a global average intensity of about 0.45-0.89×10^ 3 μGal in the whole year of 2007, which is beyond the accuracy of the present gravimetry and even the super conducting gravimeter data. However, both the gravity variations at Beijing and Wuhan vary like sine variables with maximal variations around 0.33 pGal and 0.29 pGal, respectively, in one cycle. Thus, continuous gravity measurements for one or two decades might be able to detect the differential motion of the inner core. 相似文献
4.
The present study aims to extend the traditional rotation theory of the rotational-symmetric Earth to the triaxial Earth.We re-formulate the Liouville equations and their general solutions for the triaxial nonrigid Earth and find that the traditional theory intro-duces some theoretical errors in modeling the excitation functions.Furthermore,we apply that theory to the atmospheric excitation and find that theoretical errors should not be neglected given the present measurement accuracy.Thus we conclude that the traditional the-ory of the rotation of the rotational-symmetric Earth should be revised and upgraded to include the effects of the Earth’s triaxiality. 相似文献
5.
In this paper, the theory of the free wobble of the triaxial Earth is developed and new conclusions are drawn: the Euler period should be actually expressed by the first kind of complete elliptic integral; the trace of the free polar motion is elliptic and the orientations of its semi-minor and major axes are approximately parallel to the Earth’s principal axes A and B, respectively. In addition, the present theory shows that there is a mechanism of frequency-amplitude modulation in the Chandler wobble, whi... 相似文献
6.
The crustal structure of Xiachayu-Gonghe geophysical profile in eastern Tibetan plateau is simulated with Bouguer anomaly corrected for sediments and lithosphere.The forward simulation shows that the thickness of upper crust in eastern Tibetan plateau is about 20 km,and the density is 2.78 3 3 × 10 kg/m.The bottom interface of middle crust changes from 30 km to 40 km,the density of middle crust is 2.89 3 3 × 10 kg/m.The materials with low density of 2.78 3 3 × 10 kg/mexist in middle crust,and those with hig... 相似文献
7.
The characteristics of three GPS kinematic data processing models, Least Squares （LS）, Kalman filtering and filtering are discussed and their advantages and disadvantages are compared. With observational data and pertinent data processing software, the applicable condition, context and effect of the three models are experimented. Results show that when the mobile platform is in uniform motion, the accuracy of the three models are almost equal; when the mobile platform is in stochastic acceleration, the accuracy of H∞ filtering model is superior to that of LS, while that of Kalman filtering is the worst. 相似文献
8.
The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar＇s fictitious gravity anomaly, the solution of the ＂downward con- tinuation＂ problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth＇s potential field, and the gravity field determination in three cases： gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications. 相似文献
9.
Three functional models, polynomial, spectral analysis, and modified AR model, are studied and compared in fitting and predicting clock deviation based on the data sequence derived from two-way satellite time and frequency transfer. A robust equivalent weight is applied, which controls the significant influence of outlying observations. Some conclusions show that the prediction precision of robust estimation is better than that of LS. The prediction precision calculated from smoothed observations is higher than that calculated from sampling observations. As a count of the obvious period variations in the clock deviation sequence, the predicted values of polynomial model are implausible. The prediction precision of spectral analysis model is very low, but the principal periods can be determined. The prediction RMS of 6-hour extrapolation interval is Ins or so, when modified AR model is used. 相似文献
10.
LI Zhicai XU Caijun 《地球空间信息科学学报》2005,8(3):225-229
On the basis of the dislocation theory and gravity observation, a joint inversion model is presented with a fitting factor A scaling amplitudes between the gravity and GPS observation data. The test results show that the new joint model is better than that taking the scale factor ）, as a constant from the inversion result of MSE （mean square error）. In addition, the random cost method used in the inversion algorithm is revised and improved, which shows that the improved random cost method can easily get the local minimum value and greatly decrease the iteration steps. 相似文献
11.
地球质心(CM)是整个地球的质量中心,地心运动是由地球系统的质量重新分布激励的,特别是流体圈层.利用SLR对LAGEOS 1/2卫星的距离观测,解算1993-2006年期间的地心运动时间序列,然后分别利用小波变换和最小二乘法分析该序列,发现地心运动存在长期和周期性变化.地心的长期运动表明地壳形状在变化.季节性变化是地心运动的主项,主要是由地球流体圈层的质量分布造成的,如海洋、大气和陆地水等.地心运动还存在其他周期性和准周期性变化.地心运动存在2～5年的长周期变化.许多周期都存在渐变,这表明整个地球系统质量和环境存在不规则的变化.Abstract： The center of mass of Earth (CM) is the center of total Earth's mass. The geocenter motion may be excit-ed by the mass redistribution of Earth system, especially the fluid layer. A time series of geocenter motion meas-ured with SLR on LAGEOS 1/2 is estimated and then analyzed with the wavelet transformation and the least squaresmethod, respectively. The secular and periodic variations of geocenter motion are detected. The long-term move-ment indicates that the crustal figure is changing, the north hemisphere and 180-degree hemisphere are shrinking, and the south hemisphere and O-degree hemisphere are swelling. The seasonal variations are the main componentswhich may be caused from the mass distribution of Earth fluid layer, e.g. ocean, atmosphere and continental wa-ter, There are many other periodic or quasi-periodic variations. There are long periodic variations through 2 to 5 years, Many periods gradually change, which indicates that there exist nonregular fluxes for the environment and mass of the whole Earth system. 相似文献
12.
The OGC standard for 3D city modeling is widely used in an increasing number of applications.It defines five consecutive Levels of Detail(LoD0 to LoD4 with increasing accuracy and structural complexity),in which LoD3 includes all exterior appearances and geometrical details and subsequently requires much storage space.A new LoD is introduced as shell model with the exterior shell of the LoD3 model and the opening objects like windows,doors as well as smaller faade objects are projected onto walls.In this paper,a user survey is presented.The results of this survey show that the shell model can give users almost the same visual impression as the LoD3 model.Furthermroe,algorithms are developed to extract the shell model from LoD3 model.Experiments show that this shell model can reduce up to 90% storage of the original LoD3 model.Therefore,on one hand it can be used as a substitute for a LoD3 model for the visualization on small displays.On the other hand,it can be treated as a sub-level of detail(SLoD3) in CityGML,since it retains almost the same amount of information but requires much less storage space. 相似文献
13.
YAO Yibin 《地球空间信息科学学报》2006,9(4):260-264
The methods of Earth rotation parameter （ERP） estimation based on IGS SINEX file of GPS so- lution are discussed in detail. There are two different ways to estimate ERP： one is the parameter transformation method, and the other is direct adjustment method with restrictive conditions. By comparing the estimated results with independent copyright program to IERS results, the residual systemic error can be found in estimated ERP with GPS observations. 相似文献
14.
XU Jun BAO Jingyang LIU Yanchun YU Caixia 《地球空间信息科学学报》2007,10(2):100-104
A tide model (named DN1.0), which contains 12 principal constituents over China seas and the Northwest Pacific is estimated by along-track harmonic analysis with TOPEX/Poseidon altimetry data taken from 1993 to 2002. CSR3.0, FES95.2 and DN1.0 are used respectively to detide the data for the time series of sea level anomaly (SLA) in the Yellow Sea, East China Sea, South China Sea and Northwest Pacific. The SLA curves and the power spectral density show that the major components that exist in SLA in China seas arise from the error of the tide models. 相似文献
15.
SUI Haigang HUA Li ZHAO Haitao ZHANG Yongli 《地球空间信息科学学报》2005,8(4):262-268
An effective strategy and framework that adequately integrate the automated and manual processes for fast cartographic sounding selection is presented. The important submarine topographic features are extracted for important soundings selection, and an improved “ influence circle” algorithm is introduced for sounding selection. For automatic configuration of soundings distribution pattern, a special algorithm considering multi-factors is employed. A semi-automatic method for solving the ambiguous conflicts is described. On the basis of the algorithms and strategies a system named HGIS for fast cartographic sounding selection is developed and applied in Chinese Marine Safety Administration Bureau （CMSAB）. The application experiments show that the system is effective and reliable. At last some conclusions and the future work are given. 相似文献
16.
YU Xuexiang associate professor Ph.D Department of Resource Environment Engineering Anhui University of Science Technology Huainan China. XU Shaoquan GAO Wei LU Weicai 《地球空间信息科学学报》2003,6(4):51-56
A new similar singledifference mathematical model ( SS-DM) and its corresponding algorithm are advanced to solve the deformation of monitoring point directly in single epoch. The method for building the SSDM is introduced in detail, and the main error sources affecting the accuracy of deformation measurement are analyzed briefly, and the basic algorithm and steps of solving the deformation are discussed. In order to validate the correctness and the accuracy of the similar single-difference model, the test with five dual frequency receivers is carried out on a slideway which moved in plane in Feb. 2001. In the test, five sessions are observed. The numerical results of test data show that the advanced model is correct. 相似文献
17.
申文斌 《地球空间信息科学学报》2009,12(1):1-6
Given a continuous boundary value on the boundary of a "simply closed surface"S that encloses the whole Earth, a regular harmonic fictitious field V*(P) in the domain outside an inner sphere K i that lies inside the Earth could be determined, and it is proved that V*(P) coincides with the Earth’s real field V(P) in the whole domain outside the Earth. Since in the domain outside the inner sphere Ki and the fictitious regular harmonic function V*(P) could be expressed as a uniformly convergent spherical harm... 相似文献
18.
According to the different characteristics that signal and noise exhibit during wavelet decomposition, a new denoising method based on the lifting scheme wavelet packet decomposition is presented. In this method, the SAR images are decomposed by using the best wavelet packet and the norm of each sub-band are calculated; signals and noise can be discriminated based on the norm and soft-threshold method, and the images can be denoised. Experiments show that the proposed algorithm has excellent performance in denoising SAR images, and can remove most noise of images with well-kept texture detail information. The calculating speed of the method is twice the speed of the general wavelet packet transform algorithm. 相似文献
19.
A novel filtering algorithm for Lidar point clouds is presented, which can work well for complex cityscapes. Its main features are filtering based on raw Lidar point clouds without previous triangulation or rasterization. 3D topological relations among points are used to search edge points at the top of discontinuities, which are key information to recognize the bare earth points and building points. Experiment results show that the proposed algorithm can preserve discontinuous features in the bare earth and has no impact of size and shape of buildings. 相似文献
20.
Wenbin Shen Jin Li Jiancheng Li Zhengtao Wang Jinsheng Ning Dingbo Chao 《地球空间信息科学学报》2008,11(4):273-278
Given the second radial derivative Vrr（P） ｜δs of the Earth＇s gravitational potential V（P） on the surface δS corresponding to the satellite altitude, by using the fictitious compress recovery method, a fictitious regular harmonic field rrVrr（P）^＊ and a fictitious second radial gradient field V：（P） in the domain outside an inner sphere Ki can be determined, which coincides with the real field V（P） in the domain outside the Earth. Vrr^＊（P）could be further expressed as a uniformly convergent expansion series in the domain outside the inner sphere, because rrV（P）^＊ could be expressed as a uniformly convergent spherical harmonic expansion series due to its regularity and harmony in that domain. In another aspect, the fictitious field V^＊（P） defined in the domain outside the inner sphere, which coincides with the real field V（P） in the domain outside the Earth, could be also expressed as a spherical harmonic expansion series. Then, the harmonic coefficients contained in the series expressing V^＊（P） can be determined, and consequently the real field V（P） is recovered. Preliminary simulation calculations show that the second radial gradient field Vrr（P） could be recovered based only on the second radial derivative V（P）｜δs given on the satellite boundary. Concerning the final recovery of the potential field V（P） based only on the boundary value Vrr （P）｜δs, the simulation tests are still in process. 相似文献