共查询到20条相似文献，搜索用时 31 毫秒
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重力场的局部虚拟向下延拓以及利用EGM96模型的模拟实验检验 总被引：4，自引：0，他引：4
阐述了基于虚拟压缩恢复法导出的虚拟向下延拓法，该法从理论上解决了重力场的向下延拓问题。为了检验理论的正确性，选取EGM96模型进行了模拟实验检验，实验结果支持局部虚拟向下延拓法。同时，对观测值加进随机误差的情形也进行了模拟实验检验，结果表明，局部虚拟向下延拓几乎不损失精度。 相似文献
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虚拟压缩恢复基本原理及应用实例解析 总被引：4，自引：1，他引：4
概述了虚拟压缩恢复基本原理及其在地球科学特别是边值问题中的应用。作为新的应用实例，论证了Runge定理、Runge-Krarup定理和Keldysh-Lavrentiev定理均是虚拟压缩恢复原理的推论。 相似文献
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利用卫星重力数据确定地球外部重力场的一种方法及模拟实验检验 总被引：5，自引：1，他引：5
假定给定了海量的卫星重力观测数据，基于球谐展开法并应用最小二乘原理可以确定地球重力场模型EGM，由此确定的重力场模型在地球表面附近的空间区域未必有效。设想有一个包含了地球的大球Ks，假定EGM在大球的外部成立，则可根据虚拟压缩恢复法求出一种新的重力场模型NEGM，它是对原有重力场模型的进一步精化，适合于整个地球外部空间，从理论上可以解决重力场的“向下延拓”问题。初步的模拟实验检验支持虚拟压缩恢复法以及由此而引中出的“向下延拓”法。 相似文献
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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
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确定地球外部重力场的虚拟压缩恢复法 总被引：6，自引：1，他引：5
自申文斌提出引力位虚拟压缩恢复法[1,2 ] 并证明了级数解的一致收敛性[3 ] 之后 ,宁津生和申文斌等又提出了引力场虚拟压缩恢复法[4] 本文在指出了Stokes理论、Molodenskii理论以及Bjerhammar理论所存在的缺陷或不足之后 ,概述了引力位虚拟压缩恢复法 ,用新的观点考察了引力场虚拟压缩恢复法并证明了由此得到的级数解是一致收敛的 ,提出了引力梯度场虚拟压缩恢复法 ,最后给出了确定高程的模型 相似文献
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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
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High accuracy surface modeling (HASM) constructed based on the fundamental theorem of surface is more accurate than the classical methods. However, because of boundary error, location error, etc, HASM has a big accuracy loss in real-world examples. In former researches we solved the location error with Taylor expansion. In order to reduce the HASM boundary error and improve its accuracy further, this paper presents a new method of Laplace interpolation to compute the region boundary value. Gaussian synthetic surface and the real world test region are employed to validate the efficiency of this method. Results show that the boundary value computed with Laplace interpolation is more accurate than the classical methods, which can be regarded as an alternative for boundary value computation. 相似文献
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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
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分析了地球外部空间磁场性质,阐述了基于虚拟压缩恢复原理建立地磁场模型的一种方法-地磁压缩恢复法,利用国际地磁参考场模型IGRF模拟卫星观测数据对其进行了数值试验检验,初步证实了其有效性和可靠性. 相似文献
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改进的能量守恒方法及其在CHAMP重力场恢复中的应用(英文) 总被引：1，自引：0，他引：1
XU Tianhe HE Kaifei Xi’an Research Institute of Surveying Mapping Middle Yanta Road Xi’an China. 《地球空间信息科学学报》2008,11(3):168-173
An efficient method for gravity field determination from CHAMP orbits and accelerometer data is referred to as the energy balance approach. A new CHAMP gravity field recovery strategy based on the improved energy balance approach IS developed in this paper. The method simultaneously solves the spherical harmonic coefficients, daily Integration constant, scale and bias parameters. Two 60 degree and order gravitational potential models, XISM-CHAMPO1S from the classical energy balance approach, and XISM-CHAMPO2S from the improved energy balance, are determined using about one year＇s worth of CHAMP kinematic orbits from TUM and accelerometer data from GFZ. Comparisons among XISM-CHAMPO1S, XISM-CHAMPO2S, EIGEN-CGO3C, EIGEN-CHAMPO3S, EIGEN2, ENIGNIS and EGM96 are made. The results show that the XISM-CHAMPO2S model is more accurate than EGM96, EIGENIS, EIGEN2 and XISM-CHAMPO1S at the same degree and order, and has almost the same accuracy as EIGEN-CHAMPO3S. 相似文献
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ITG-CHAMP01: a CHAMP gravity field model from short kinematic arcs over a one-year observation period 总被引：8，自引：0，他引：8
Global gravity field models have been determined based on kinematic orbits covering an observation period of one year beginning from March 2002. Three different models have been derived up to a maximum degree of n=90 of a spherical harmonic expansion of the gravitational potential. One version, ITG-CHAMP01E, has been regularized beginning from degree n=40 upwards, based on the potential coefficients of the gravity field model EGM96. A second model, ITG-CHAMP01K, has been determined based on Kaulas rule of thumb, also beginning from degree n=40. A third version, ITG-CHAMP01S, has been determined without any regularization. The physical model of the gravity field recovery technique is based on Newtons equation of motion, formulated as a boundary value problem in the form of a Fredholm-type integral equation. The observation equations are formulated in the space domain by dividing the one-year orbit into short sections of approximately 30-minute arcs. For every short arc, a variance factor has been determined by an iterative computation procedure. The three gravity field models have been validated based on various criteria, and demonstrate the quality of not only the gravity field recovery technique but also the kinematically determined orbits. 相似文献
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经典物理大地测量学利用斯托克斯方法和莫洛金斯基方法解算大地测量边值问题并给出地球外部重力场表达,若忽略1~2 m量级的动力学海面地形,静止的平均海面可认为是大地水准面,后者是与平均海平面最为接近的重力等位面。经典理论无法求解海洋内部,即地球内部重力场问题,为解决这一局限,基于地表浅层法引入“浅层海水”的概念,“浅层海水”上下界面由平均海面高模型DTU21确定,利用牛顿积分和球谐展开算法确定了最优球谐分析迭代次数,分析了“浅层海水”厚度与积分区域半径大小的关系,确定了“浅层海水”厚度为100 m、500 m和1 000 m时的最优积分区域半径为1°,厚度4 000 m时为1.5°;评估了“浅层海水”质量法移去-恢复海洋表面重力值的精度,“浅层海水”厚度100 m、500 m、1 000 m和4 000 m的均方根误差分别为0.13 mGal、0.61 mGal、1.21 mGal和3.93 mGal,验证了该方法的可靠性。基于此理论,计算了不同厚度“浅层海水”下表面的层面重力值,得到了100 m、500 m、1 000 m和4 000 m深度处层面重力值与“浅层海水”上表面重力值差的均方根,分别为22.11 mGal、110.50 mGal、220.87 mGal和877.31 mGal。 相似文献
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基于Coons曲面的规则格网DEM表面模型 总被引：7，自引：0，他引：7
内插是数字高程模型的核心问题。目前的内插模型主要是由离散的格网数据构建的连续曲面,直接以点推面,可能存在较大的地形误差。本文建立的Coons曲面DEM表面模型,首先利用离散的格网数据构造与格网边界相对应的地形剖面曲线的拟合曲线,再基于拟合曲线构建DEM表面模型。实验表明：Coons曲面DEM表面模型是一种高精度的DEM表面模型,其地形模拟误差比直接基于格网数据建立的双线性内插、样条函数内插和移动曲面拟合法的误差都小,实际地形模拟误差与双线性模型相比减少15％-28％,且精度随着构建边界拟合曲线所用格网点的增多而逐渐提高。 相似文献
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ACCURACY PREDICTION FOR ORTHO-IMAGE GENERATION 总被引：1，自引：0，他引：1
Amnon Krupnik 《The Photogrammetric Record》2003,18(101):41-58
This paper revisits the basic mathematical formulation of ortho-image (digital orthophoto) generation. The main objective is to provide an approach for predicting the accuracy of an ortho-image, according to the accuracy of the digital elevation model (DEM), control points and image measurements, the configuration of fiducial, tie and control points, and the ground slope. The approach is based on applying the well-known law of error propagation to the mathematical model of ortho-image generation. Although it may seem intuitive for professionals in the field of photogrammetry, such an approach is essential in the era when specialists in other fields use off-the-shelf software packages for ortho-image generation. Simulations with the derived approach show that the accuracy of the ortho-image is more sensitive to errors in image measurement of fiducial, tie and control points and ground coordinates of control points, than to DEM errors. Non-standard configurations of fiducial, tie and control points further impair the accuracy. In addition, certain combinations of point location and ground slope might lead to unacceptably large error on the ortho-image. 相似文献
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Ai Tinghua 《地球空间信息科学学报》2013,16(2):55-62
This paper presents a field based method to deal with the displacement of building cluster, which is driven by the street widening. The compress of street boundary results in the force to push the building moving inside and the force propagation is a decay process. To describe the phenomenon above, the field theory is introduced with the representation model of isoline. On the basis of the skeleton of Delaunay triangulation, the displacement field is built in which the propagation force is related to the adjacency degree with respect to the street boundary. The study offers the computation of displacement direction and offset distance for the building displacement. The vector operation is performed on the basis of grade and other field concepts. 相似文献
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AlTinghua 《地球空间信息科学学报》2003,6(2):55-62
This paper presents a field based method to deal with the displacement of building cluster, which is driven by the street widening. The compress of street boundary results in the force to push the build-ing moving inside and the force propagation is a decay process.To describe the phenomenon above,the field theory is introduced with the representation model of isoline.On the basis of the skeleton of Delaunay triangulation.the displacement field is built in which the propagation force is related to the adjacency degree with respect to the street boundary.The study offers the computation of displacement direction and offset distance for the building displacement.The vector operation is performed on the basis of grade and other field concepts. 相似文献
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针对当前利用灰色预测模型进行地表沉降预测研究更多注重模型本身探讨而较少涉及预测值合理范围以及预测值时间响应函数的还原方法的情况,该文提出了一种改进的等维灰数递补模型预测边界的确定方法,采用了误差传播定律对预测值范围进行界定,并尝试利用中值近似处理代替累减生成建立预测值的时间响应函数;最后,结合工程实例给出了预测值上下边界,探讨了模型在误差允许范围内的预测步长,并对比分析了改进的等维灰数递补模型、原始的等维灰数递补模型和GM(1,1)模型。结果发现:改进的等维灰数递补模型具有较好的拟合效果与预测精度。 相似文献
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The paper presents a numerical solution of the oblique derivative boundary value problem on and above the Earth’s topography using the finite volume method (FVM). It introduces a novel method for constructing non-uniform hexahedron 3D grids above the Earth’s surface. It is based on an evolution of a surface, which approximates the Earth’s topography, by mean curvature. To obtain optimal shapes of non-uniform 3D grid, the proposed evolution is accompanied by a tangential redistribution of grid nodes. Afterwards, the Laplace equation is discretized using FVM developed for such a non-uniform grid. The oblique derivative boundary condition is treated as a stationary advection equation, and we derive a new upwind type discretization suitable for non-uniform 3D grids. The discretization of the Laplace equation together with the discretization of the oblique derivative boundary condition leads to a linear system of equations. The solution of this system gives the disturbing potential in the whole computational domain including the Earth’s surface. Numerical experiments aim to show properties and demonstrate efficiency of the developed FVM approach. The first experiments study an experimental order of convergence of the method. Then, a reconstruction of the harmonic function on the Earth’s topography, which is generated from the EGM2008 or EIGEN-6C4 global geopotential model, is presented. The obtained FVM solutions show that refining of the computational grid leads to more precise results. The last experiment deals with local gravity field modelling in Slovakia using terrestrial gravity data. The GNSS-levelling test shows accuracy of the obtained local quasigeoid model. 相似文献