探索如何利用低成本的低轨卫星(low Earth orbit,LEO)星群的精密轨道资料探测地球重力场,并以COSMIC(constellation observing system for meteorology ionosphere & climate)为研究实例初步分析了其覆盖性和方法的可行性。
Regional gravity field modeling with high-precision and high-resolution is one of the most important scientific objectives in geodesy, and can provide fundamental information for geophysics, geodynamics, seismology, a...Regional gravity field modeling with high-precision and high-resolution is one of the most important scientific objectives in geodesy, and can provide fundamental information for geophysics, geodynamics, seismology, and mineral exploration. Rectangular harmonic analysis （RHA） is proposed for regional gravity field modeling in this paper. By solving the Laplace＇s equation of gravitational potential in local Cartesian coordinate system, the rectangular harmonic expansions of disturbing potential, gravity anomaly, gravity disturbance, geoid undulation and deflection of the vertical are derived, and so are the formula for signal degree variance and error degree variance of the rectangular harmonic coefficients （RHC）. We also present the mathematical model and detailed algorithm for the solution of RHC using RHA from gravity observations. In order to reduce the edge effects caused by periodic continuation in RHA, we propose the strategy of extending the size of computation domain. The RHA-based modeling method is validated by conducting numerical experiments based on simulated ground and airborne gravity data that are generated from geopotential model EGM2008 and contaminated by Gauss white noise with standard deviation of 2 mGal. The accuracy of the 2.5＇×2.5＇ geoid undulations computed from ground and airborne gravity data is 1 and 1.4 cm, respectively. The standard error of the gravity disturbances that downward continued from the flight height of 4 km to the geoid is only 3.1 reGal. Numerical results confirm that RHA is able to provide a reliable and accurate regional gravity field model, which may be a new option for the representation of the fine structure of regional gravity field.展开更多
TH761.1 2000042969一个面向对象的星体标校软件的设计与实现=Design and implementation of an obiect oriented soft-ware for star calibration[刊,中]/张光明,王建军(北京跟踪与通信技术研究所,北京(100094))
In land-use data generalization, the removal of insignificant parcel withsmall size is the most frequently used operator. Traditionally for the generalization method, thesmall parcel is assigned completely to one of i...In land-use data generalization, the removal of insignificant parcel withsmall size is the most frequently used operator. Traditionally for the generalization method, thesmall parcel is assigned completely to one of its neighbors. This study tries to improve thegeneralization by separating the insignificant parcel into parts around the weighted skeleton andassigning these parts to different neighbors. The distribution of the weighted skeleton depends onthe compatibility between the removed object and its neighbor, which considers not only topologicalrelationship but also distance relationship and semantic similarity. This process is based on theDelaunay triangulat'on model. This paper gives the detailed geometric algorithms for this operation.展开更多
文摘探索如何利用低成本的低轨卫星(low Earth orbit,LEO)星群的精密轨道资料探测地球重力场,并以COSMIC(constellation observing system for meteorology ionosphere & climate)为研究实例初步分析了其覆盖性和方法的可行性。
基金jointly supported by the National Basic Research Program of China (Grant No. 2013CB733301)the National Science and Technology Support Program of China (Grant No. 2012BAB16B01)+1 种基金the National Natural Science Foundation of China (Grant No. 41204008)the Basic Research Program of National Administration of Surveying, Mapping and Geoinformation of China
文摘Regional gravity field modeling with high-precision and high-resolution is one of the most important scientific objectives in geodesy, and can provide fundamental information for geophysics, geodynamics, seismology, and mineral exploration. Rectangular harmonic analysis （RHA） is proposed for regional gravity field modeling in this paper. By solving the Laplace＇s equation of gravitational potential in local Cartesian coordinate system, the rectangular harmonic expansions of disturbing potential, gravity anomaly, gravity disturbance, geoid undulation and deflection of the vertical are derived, and so are the formula for signal degree variance and error degree variance of the rectangular harmonic coefficients （RHC）. We also present the mathematical model and detailed algorithm for the solution of RHC using RHA from gravity observations. In order to reduce the edge effects caused by periodic continuation in RHA, we propose the strategy of extending the size of computation domain. The RHA-based modeling method is validated by conducting numerical experiments based on simulated ground and airborne gravity data that are generated from geopotential model EGM2008 and contaminated by Gauss white noise with standard deviation of 2 mGal. The accuracy of the 2.5＇×2.5＇ geoid undulations computed from ground and airborne gravity data is 1 and 1.4 cm, respectively. The standard error of the gravity disturbances that downward continued from the flight height of 4 km to the geoid is only 3.1 reGal. Numerical results confirm that RHA is able to provide a reliable and accurate regional gravity field model, which may be a new option for the representation of the fine structure of regional gravity field.
文摘TH761.1 2000042969一个面向对象的星体标校软件的设计与实现=Design and implementation of an obiect oriented soft-ware for star calibration[刊,中]/张光明,王建军(北京跟踪与通信技术研究所,北京(100094))
文摘In land-use data generalization, the removal of insignificant parcel withsmall size is the most frequently used operator. Traditionally for the generalization method, thesmall parcel is assigned completely to one of its neighbors. This study tries to improve thegeneralization by separating the insignificant parcel into parts around the weighted skeleton andassigning these parts to different neighbors. The distribution of the weighted skeleton depends onthe compatibility between the removed object and its neighbor, which considers not only topologicalrelationship but also distance relationship and semantic similarity. This process is based on theDelaunay triangulat'on model. This paper gives the detailed geometric algorithms for this operation.
