面向服务的数字泰州共享平台及其示范应用

服务共享是当前数字城市向智慧城市方向发展的关键技术之一。探讨了基于面向服务的数字城市共享框架,在此基础上以数字泰州建设为例设计并实现了一个面向服务架构的数字城市共享服务平台,为空间信息在城市信息化发展中的共享服务做出有益的探索和尝试。     

分形学:现代地图学的非线性数学分析方法

分析了地图学的传统数学分析方法，讨论了对象复杂性与方法简单化的矛盾，阐述了分形几何学，为现代地图学研究的定量化、系统化提供了新的数学分析方法。     

Impact of GLONASS pseudorange inter-channel biases on satellite clock corrections

GLONASS carrier phase and pseudorange observations suffer from inter-channel biases (ICBs) because of frequency division multiple access (FDMA). Therefore, we analyze the effect of GLONASS pseudorange inter-channel biases on the GLONASS clock corrections. Different Analysis Centers (AC) eliminate the impact of GLONASS pseudorange ICBs in different ways. This leads to significant differences in the satellite and AC-specific offsets in the GLONASS clock corrections. Satellite and AC-specific offset differences are strongly correlated with frequency. Furthermore, the GLONASS pseudorange ICBs also leads to day-boundary jumps in the GLONASS clock corrections for the same analysis center between adjacent days. This in turn will influence the accuracy of the combined GPS/GLONASS precise point positioning (PPP) at the day-boundary. To solve these problems, a GNSS clock correction combination method based on the Kalman filter is proposed. During the combination, the AC-specific offsets and the satellite and AC-specific offsets can be estimated. The test results show the feasibility and effectiveness of the proposed clock combination method. The combined clock corrections can effectively weaken the influence of clock day-boundary jumps on combined GPS/GLONASS kinematic PPP. Furthermore, these combined clock corrections can improve the accuracy of the combined GPS/GLONASS static PPP single-day solutions when compared to the accuracy of each analysis center alone.     

Corn Area Extraction by the Integration of MODIS-EVI Time Series Data and China’s Environment Satellite (HJ-1) Data

In this paper, we intent to use the remotely sensed MODerate resolution Imaging Spectroradiometer (MODIS) data and China’s Environment Satellite (HJ-1) data for extracting the corn cultivated area over a regional scale. The high resolution HJ-1 data was to extract corn distribution at a small scale class with Support Vector Machine (SVM). The mean Enhanced Vegetation Index (EVI) time series curve of corn from MODIS was derived for the reference area and validated in a larger area. The MODIS-EVI time series curve derived from the reference area instead of the MODIS-EVI time series curve derived from the study area after validation, which was taken as the standard MODIS-EVI time series curve in for generating a standard MODIS-EVI image of corn. The mean absolute distance (MAD) between the standard MODIS-EVI image of corn and the MODIS-EVI time series image was used to detect the maximum possible extent of corn distribution in the study area. The results showed that the overall accuracy of the method was 82.17 %, with commission and omission errors of 16.85 and 15.40 %, respectively; at the county level, the satellite-estimated corn area and statistical data were well correlated (R ²?=?0.85, N?=?50) for the whole Jilin Province. It indicated that the MODIS data integrated with higher spatial resolution of HJ-1 satellite data could be utilized to enhance the extraction accuracy of corn cultivated area at a larger scale.     

基于ArcGIS Server的医院网络地理信息服务系统

为解决目前医院地理信息服务系统在信息共享、空间分析等方面的不足,采用ArcGIS Server组件、C#编程语言、SQL Server数据库研发了医院网络地理信息服务系统。该系统以天地图作为基础地理数据,融合医院空间与医疗信息,并部署到互联网环境中。除具有医疗专题信息的网络浏览与查询外,系统还实现了诸多空间分析、地学统计等功能,既可为市民就医提供更全面的信息查询,又可为医疗事故的突发与应急提供技术支撑。     

基于虚拟化的“天地图?四川”网站集群设计与实现

本文通过对服务器集群和虚拟化技术的研究,设计了一种基于虚拟化的地理信息服务器集群架构,在此基础上,对地理信息服务软件系统进行了优化,并应用于天地图?四川的建设。通过相应的性能测试对比分析,采用虚拟化的“天地图?四川”服务器集群架构,能有效提高地理信息服务功能的可用性和性能。     

上海市不可移动文物管理信息系统的研究与实现

探讨了以上海市为例,在WebGIS技术、数据库技术等支持下,通过设计和实现不可移动文物管理信息系统,实现文物历史资料存档、综合档案信息数字化管理、文物点云数据存储及3维模型重建等,以改进文物管理工作的方法和手段,提高管理工作的效率和信息化水平。     

GPS基线解算的基本理论与质量控制

主要阐述了GPS基线解算的基本理论,分析了基线解算中的质量控制。并利用TBC软件以某市新城区控制网计算为例,在计算过程中对基线质量进行控制,最后对控制点成果进行评价。     

美国空间规划体系的构建及启示

本文在分析美国空间规划及体系形成的基础上,从规划的法规体系、行政体系和运行体系三个方面阐述各级规划的法规、机构及规划类型,总结美国空间规划体系的特点,得出对我国空间规划体系构建的启示.     

A two-step ionospheric modeling algorithm considering the impact of GLONASS pseudo-range inter-channel biases

The Global Navigation Satellite System presents a plausible and cost-effective way of computing the total electron content (TEC). But TEC estimated value could be seriously affected by the differential code biases (DCB) of frequency-dependent satellites and receivers. Unlike GPS and other satellite systems, GLONASS adopts a frequency-division multiplexing access mode to distinguish different satellites. This strategy leads to different wavelengths and inter-frequency biases (IFBs) for both pseudo-range and carrier phase observations, whose impacts are rarely considered in ionospheric modeling. We obtained observations from four groups of co-stations to analyze the characteristics of the GLONASS receiver P1P2 pseudo-range IFB with a double-difference method. The results showed that the GLONASS P1P2 pseudo-range IFB remained stable for a period of time and could catch up to several meters, which cannot be absorbed by the receiver DCB during ionospheric modeling. Given the characteristics of the GLONASS P1P2 pseudo-range IFB, we proposed a two-step ionosphere modeling method with the priori IFB information. The experimental analysis showed that the new algorithm can effectively eliminate the adverse effects on ionospheric model and hardware delay parameters estimation in different space environments. During high solar activity period, compared to the traditional GPS + GLONASS modeling algorithm, the absolute average deviation of TEC decreased from 2.17 to 2.07 TECu (TEC unit); simultaneously, the average RMS of GPS satellite DCB decreased from 0.225 to 0.219 ns, and the average deviation of GLONASS satellite DCB decreased from 0.253 to 0.113 ns with a great improvement in over 55%.