测站位移固体潮效应的潮波公式

固体潮对测站位移的影响是空间大地测量和天文地球动力学研究的重要组成部分。对目前常用的3种引潮力位展开形式进行了总结，并列出了它们各自的实用公式。不同于IERSl996和IERS2000推荐的固体潮对测站位移影响的理论模型，独立于天体历书而基于精密引潮力位展开，直接给出了在亚毫米精度下的潮波公式，利用新的精密引潮位展开在亚毫米精度上重新计算了永久性潮汐的影响。可为高精度的空间大地测量和天文地球动力学的研究提供理论依据和参考。     

单目视觉下基于对偶四元数的运动目标位姿确定

利用对偶四元数研究运动载体和目标之间相对运动的单目算法大多是仿真验证,缺乏实验验证。针对这些不足,在James方法的基础上,扩展了状态量,推导了相应的系统模型和观测模型,组成新的滤波方程。匀速旋转的转台实验验证了改进算法的优越性。     

一种基于对偶四元数的摄影测量位姿估计直接解法

位姿估计是摄影测量学中的经典问题和核心问题之一,现将对偶四元数引入到摄影测量位姿估计问题中,充分利用了对偶四元数描述刚体运动的简洁性和非奇异性,统一表示刚体运动的旋转与平移。现将其方法与广泛使用的基于单位四元数的直接解法进行了仿真实验对比分析。实验结果说明本文采用的方法正确有效,相较基于单位四元数的直接解法,精度较高,计算时间较短,效率优势明显,具有较高的实际应用价值。     

依初值与无初值单位四元数空间后方交会的比较

针对传统空间后方交会方法的解算结果受外方位元素初值影响较大的问题,该文分别就航空摄影测量及近景摄影测量不同条件下,采用依初值单位四元数空间后方交会解算与无需初值单位四元数空间后方交会解算进行对比分析。实验表明,航空摄影测量条件时,在小倾角情况下,两种方法所得检查像点的点位精度相当;当倾角较大时,依初值解算所得检查像点的总体点位精度高于无需初值解算所得精度;特大倾角时,依初值解算得不到正确结果,而无需初值解算仍有很好适应性。在近景摄影测量条件下,无初值解算有广泛的适应性,且所得的检查像点的总体点位精度高于依初值解算所得精度。     

单位四元数、罗德里格转换模型与欧拉角的映射关系

在大角度姿态运动场景中,运动状态通常采用单位四元数或罗德里格转换模型,但转换参数并不具有直观性和几何意义,因此研究单位四元数、罗德里格转换模型与欧拉角的映射关系十分必要。然而,单位四元数、罗德里格参数与欧拉角相互之间并不存在一一对应的关系。结合三种转换模型的特点及欧拉角、罗德里格参数存在奇异问题,本文对可能出现的情况进行推导分析,建立各模型间转换参数的映射关系,实现单位四元数、罗德里格转换模型与欧拉角大角度范围的转换。     

A new modelling method for evaluating external disturbing potential based on theory of unified representation of gravitational field

For a special use a new modelling method of evaluating external disturbing potential is presented in this paper. Being different from classical methods in physical geodesy this method is grounded upon the theory of unified representation of gravitational field. The models created in this way are particularly satisfactory for a high-speed computation of gravitational field in low altitude because they take account of topographic effects and have their kernel functions with simple structure and weak singularity.     

A new modelling method for evaluating external disturbing potential based on theory of unified representation of gravitational field

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Comparative study on two methods for calculating the gravitational potential of a prism

The determination of the gravitational potential of a prism plays an important role in physical geodesy and geophysics. However, there are few literatures that provide accurate approaches for determining the gravitational potential of a prism. Discrete element method can be used to determine the gravitational potential of a prism, and can approximate the true gravitational potential values with sufficient accuracy (the smaller each element is, the more accurate the result is). Although Nagy’s approach provided a closed expression, one does not know whether it is valid, due to the fact that this approach has not been confirmed in literatures. In this paper, a study on the comparison of Nagy’s approach with discrete element method is presented. The results show that Nagy’s formulas for determining the gravitational potential of a prism are valid in the domain both inside and outside the prism.     

Comparative study on two methods for calculating the gravitational potential of a prism

The determination of the gravitational potential of a prism plays an important role in physical geodesy and geophysics. However, there are few literatures that provide accurate approaches for determining the gravitational potential of a prism. Discrete element method can be used to determine the gravitational potential of a prism, and can approximate the true gravitational potential values with sufficient accuracy (the smaller each element is, the more accurate the result is). Although Nagy’s approach provi...     

多因素灰色G(1,N)模型及其在基坑位移预测中的应用

G(1,1)模型只利用单点已测数据预测该点的位移,而不管别的因素影响。而事实上该点位移和围护桩上其他点的位移及锚索拉力是耦合的。针对传统的单因素灰色模型在基坑预测中的不足之处,本文提出采用多因素的G(1,N)灰色模型对基坑位移进行预测研究。计算实例表明,该模型预测精度高,所需数据少,简单实用,值得在基坑预测中推广。     

Integral formulas for computing the disturbing potential, gravity anomaly and the deflection of the vertical from the second-order radial gradient of the disturbing potential

Integral formulas are derived which can be used to convert the second-order radial gradient of the disturbing potential, as boundary values, into the disturbing potential, gravity anomaly and the deflection of the vertical. The derivations are based on the fundamental differential equation as the boundary condition in Stokes’s boundary-value problem and the modified Poisson integral formula in which the zero and first-degree spherical harmonics are excluded. The rigorous kernel functions, corresponding to the integral operators, are developed by the methods of integration.     

基于能量守恒的星间距离变率与地球重力场频谱关系的建立与分析

The spectral relationship between range-rate measurements and the gravity potential for low-low satellite-to-satellite tracking mission was established based on the energy conservation theory. Then the performances of satellite separation, the orbital altitude, and the accuracy of range-rate measurements in recovering the earth’s gravity field were simulated and analyzed by this method. Finally, the cumulative geoid errors of the reference mode were obtained by using the configuration parameters of the GRAC...     

基于RS和GIS的城市雾霾与汽车保有量关系研究

近年来我国许多城市雾霾天数增多,雾霾强度增强。本研究利用遥感数据反演获得沈阳市雾霾强度空间分布图。通过分析预测,未来的5年,汽车保有量依然呈现逐年增多的趋势,雾霾强度也将呈现逐年增强的趋势。     

结合SBAS-InSAR技术及信息熵的苍山地质滑坡隐患识别

针对西南地区滑坡隐患高位隐蔽,传统技术难以全面识别的问题,本文以大理苍山为研究对象,首先利用SBAS-InSAR技术对苍山2019年1月—2021年4月间的滑坡隐患进行识别;然后结合随机概率信息熵模型,对不同坡度等级与边坡稳定性之间的关联性进行定量分析;最后根据典型隐患区的遥感影像以及采样点的形变时序图,探讨了边坡形变时空演化特征及沉降诱因。试验结果表明：(1)2019年1月—2021年4月,研究区的形变速率为-155.6～92.4 mm/a, 13个超过-30 mm/a的不稳定滑坡隐患被识别;(2)坡度等级为Ⅳ、Ⅴ级时,信息熵大于0.8,边坡稳定性较弱,不均匀形变严重,与已有研究保持高度一致,证实了该模型的可靠性;(3)典型隐患区形变趋势呈明显的季节性变化,降雨和冰雪消融是导致边坡失稳的主要因素。     

A comparative study on groundwater spring potential analysis based on statistical index,index of entropy and certainty factors models

The main aim of this study is to generate groundwater spring potential maps for the Ningtiaota area (China) using three statistical models namely statistical index (SI), index of entropy (IOE) and certainty factors (CF) models. Firstly, 66 spring locations were identified by field surveys, out of which, 46 (70%) spring locations were randomly selected for training the models and the rest 20 (30%) spring locations were used for validation. Secondly, 12 spring influencing factors, namely slope angle, slope aspect, altitude, profile curvature, plan curvature, sediment transport index, stream power index, topographic wetness index, distance to roads, distance to streams, lithology and normalized difference vegetation index (NDVI) were derived from the spatial database. Subsequently, using the mentioned factors and the three models, groundwater spring potential values were calculated and the results were plotted in ArcGIS 10.0. Finally, the area under the curve was used to validate groundwater spring potential maps. The results showed that the IOE model, with the highest success rate of 0.9126 and the highest prediction rate of 0.9051, showed the preferable performance in this study. The results of this study may be helpful for planners and engineers in groundwater resource management and other similar watersheds.