局部地形校正的精密算法

对局部地形校正中的中央区奇异积分部分进行非奇变换,使用Simpson公式和Cotes公式推导出两种中央区的数值计算方法。试算结果表明,新方法可有效地提高地形校正的精度。     

原子Na的电子碰撞电离

使用Ｒ矩阵方法, 在扭曲波和库仑玻恩近似下计算了入射电子能量为２０ ｅＶ、５０ｅＶ 及１００ ｅＶ 原子Ｎａ 的电子碰撞电离截面, 并详细给出了入射电子能量为５０ ｅＶ 时的能量微分截面及分波能量微分截面。计算结果揭示了明显的Ｒｙｄｅｒｇ 系列共振, 并使用量子亏损理论对结果进行分析和讨论, 展示了Ｒｙｄｅｒｇ 系列共振的丰富内容。     

用于数字测图的摄影测量数据库系统

本文介绍了一种面向数字测图系统的摄影测量数据库，着重讨论了该数据库的基本框架及数据结构。尤其是对数据块动态串作了深入的探讨。实践表明，这种数据库的设计方案是可行的。     

面向对象的空间数据采集

本文主要介绍在Turbo C++支撑下,用面向对象的方法,对地图的空间数据进行采集、分类、编辑、净化。该系统利用C++中面向对象的概念及类的继承与地图数据的层次关系相吻合的特点,使得数据的输出能满足更多的要求,并且针对地图数据量大的特点,引入了多态和动态覆盖相结合的方法,以满足内存和速度两方面的要求。     

摄影测量数据库的设计与建立

摄影测量数据库主要存储和管理数字地图成果数据，包括数字高程模型数据（DEM）、数字矢量地图数据（DLG）、数字影像地图数据（DOM）和数字栅格地图数据（DRG）。本文主要介绍了摄影测量数据库的设计、建立以及应用分析等内容。     

亚洲沙尘暴的遥感监测方法研究 --以中国-日本合作研究区为例

介绍了亚洲沙尘暴遥感监测的一些新方法,并对监测结果与数据进行了综合分析,这些结果能够为GCM全球尺度沙尘模型提供参数和验证数据。本次研究结果为亚洲沙尘暴的中长期预测/预警系统提供了新的遥感技术方法。     

工程测量数据共享机制研究

北京市测绘设计研究院(简称北京院)是全国最大的城市测绘院,每年约完成5000余件工程测量任务,其对工程测量数据共享的需求具有代表性.在调研北京市测绘设计研究院各部门工程测量数据情况的基础上,首先对院内工程测量数据的现状和共享现状进行了分析,然后分析了共享中存在的问题,并提出了工程测量数据共享机制的建议,供领导在决策过程...     

FY-3D and FY-3C onboard observations for differential code biases estimation

GPS Solutions - As parameter estimation and statistical testing are often intimately linked in the processing of observational data, the uncertainties involved in both estimation and testing need...     

The ellipsoidal corrections to the topographic geoid effects

The topographic effects by Stokes formula are typically considered for a spherical approximation of sea level. For more precise determination of the geoid, sea level is better approximated by an ellipsoid, which justifies the consideration of the ellipsoidal corrections of topographic effects for improved geoid solutions. The aim of this study is to estimate the ellipsoidal effects of the combined topographic correction (direct plus indirect topographic effects) and the downward continuation effect. It is concluded that the ellipsoidal correction to the combined topographic effect on the geoid height is far less than 1 mm. On the contrary, the ellipsoidal correction to the effect of downward continuation of gravity anomaly to sea level may be significant at the 1-cm level in mountainous regions. Nevertheless, if Stokes formula is modified and the integration of gravity anomalies is limited to a cap of a few degrees radius around the computation point, nor this effect is likely to be significant.AcknowledgementsThe author is grateful for constructive remarks by J Ågren and the three reviewers.     

Verification and mitigation of the power-induced measurement errors for airport pseudolites in LAAS

Certain GPS receivers exhibit a power-induced measurement error when the input signal power exceeds a certain threshold that is a function of the receiver architecture. The characterization of this error is important in the case of airport pseudolites (APLs) due to receiver saturation at ranges close to the transmission antenna. This paper details an effort using laboratory test to characterize the power-induced measurement error in NovAtel Millennium and Beeline receivers that are widely used for APL development. The results from the laboratory tests show that this effect can lead to errors as large as 3 m on pseudorange measurement for the dynamic range typical for APLs. The carrier-phase error however is seen to be limited to 5 cm. On the verification and characterization of the error, a cost-effective mitigation technique for LAAS is proposed. A solution for the ground subsystem is sought by employing power-control measures to limit the amount of APL power that LGF GPS/APL receivers are exposed to. In order to keep the integration cost low, the solution for the airborne subsystem does not involve hardware modifications or additions, but rather relies on the transition to a differential carrier-phase positioning algorithm prior to the onset of the power-induced error along the approach path. The proposed architecture was flight-tested to verify successful mitigation of the power-induced error on both the ground and air, and the results from these tests are presented in the paper.