利用多普勒观测值精确确定运动载体的速度

讨论了利用ＧＰＳ多普勒频移观测值确定运动载体速度的基本原理,估计了 方法可以达到的精度。为验证该方法的可靠性及稳定性,做了两个试验：静态试验和动态试验。,试验中实测动态数据处理采用ＶＡＥＳ软件。理论研究和数据处理结果均表明,在卫星分布较好的情况下,载体速度的确定精度可达ｍｍ／ｓ。     

基于GPS双差相位率确定运动载体的速度和加速度

本文讨论了利用ＧＰＳ双差相位率确定运动载体速度的基本原理,提出了对速度序列进行曲线拟合的加速度确定方法。模拟试验表明,加速度的确定精度可达３ｍＧａｌ。     

航空重力测量中确定载体速度的静态试验

航空重力测量需要一定精度的导航信息，其中也包括载体的运动速度，用于计算厄特弗斯改正，本文作者参考文献[1][2]中的利用GPS多普勒频移观测值确定运动载体速度基本原理，自行研制了VAES（Velocity and Acceleration Esti-mation System)软件，用静态试验数据验证了理论的可靠性、软件的稳定性和该方法可以达到的精度。数据处理结果表明，载体水平速度的确定精度可达1-2cm/s，满足航空重力测量的精度要求。     

一种GNSS双天线姿态确定及点位标定方法研究

针对难以通过全球卫星导航系统(GNSS)直接测量的目标点位动态标定问题,讨论了GNSS双天线姿态确定的方法,且对存在的由安装误差等因素引起的姿态不一致做了推导分析,提出了一种基于GNSS双天线的点位动态标定原理和试验验证方法,并对点位动态标定的精度进行了分析．通过飞行试验算例分析得出:该方法可实现优于3 cm的动态标定精度,为载体目标点位动态标定提供了一种新的解决方案．      

精密单点确定航空重力载体运动速度和加速度

载体运动速度和加速度的精确确定是航空重力中的关键问题之一。基于IGS发布的精密轨道和钟差产品,并对各种相关误差精确模型化,利用载波相位直接法计算速度和加速度。在静态条件下,水平方向的速度精度优于1.5 mm/s,加速度精度优于2.0 mm/s2;垂直方向的速度精度约为2.0 mm/s,加速度精度约为2.5 mm/s2。在动态条件下,与多参考站载波相位直接法精度相当,并且计算效率和解算成功率更高。结果表明了本文方法在航空重力中的有效性。     

GPS在航空重力测量中的应用

概述航空重力测量对载体位置，速度和加速度速度的精度要求，讨论GPS成动加速度的原理和方法；基于航空重力测量实测数据，分析GPS高程，速度和加速度的确定精度。     

重力仪动态精度检定方法浅析

重力仪动态精度检定是重力仪检定的重要项目。本文主要从相对重力仪的动态精度检定方法、检定性质和合格性判定标准入手,通过对不同约定真值引入,提出了使用动态内符合精度和外符合精度联合判定重力仪动态精度的检定方法,明确了粗差剔除方法,确定了合格性判定标准,并进行试验论证,仅供同行参考。     

航空重力测量中加速度的确定

垂直加速度的精确确定是航空重力测量中的关键问题之一。本文讨论了利用GPS相位加速度确定运动载体加速度的基本原理，估计了这一方法可以达到的精度，为检验该方法的可靠性和实用性，我们做了模拟实验，数据来源于一次车载GPS测量试验。数据处理中使用了自行研制的VAES软件。数据处理结果表明，该方法确定的载体加速度，其精度可以达到1－2mGal。     

北斗载波相位差分的高频测速

针对GNSS测速方法中,传统单站历元间伪距单点定位位置差分及原始多普勒观测实时估计载体速度精度较低的问题,该文通过GNSS模块输出的载波相位观测值,根据相位中心一阶差分导出多普勒观测值的方法、同时系统地分析参数估计中各项误差源的影响,最后通过多普勒测速原理实时估计载体的速度信息。实验结果表明,该文所采用的方法静态模式下精度可以达到1～2mm/s,动态情况下测速精度可以达到5cm/s,较好地满足了机械控制领域的测速需求。     

顾及载体航向约束的单站BDS-3相位测速模型

速度是载体运动状态的重要表征,高精度定速能力是BDS-3系统高性能服务的重要体现。针对传统单站历元间相位差分模型易受误差积累与观测环境影响等问题,本文提出了顾及载体航向约束的单站BDS-3相位测速模型。首先,在传统BDS-3历元间相位差分方程矢量分解的基础上,构建载体位移增量微分表达式,联合非差模型与微分方程综合估计载体速度;其次,利用载体水平面内位移矢量与航向角之间的相关性,建立顾及航向角约束的N与E方向位移参数约束条件;最后,综合3组独立的函数方程进行载体速度分量逐历元解算。通过静态与动态试验表明,静态条件下,BDS-3相位不同方向均可实现mm/s的测速精度,相较于传统历元间差分模型,E与N方向分别提升了62.9%和87.5%,且有效避免了水平方向测速误差的积累效应,但U方向由于缺少约束导致精度提升不显著。动态条件下,BDS-3相位测速在直线运动状态水平面内可获得mm/s级的测速精度,且E与N方向较传统历元间差分模型分别提升了35.2%和21.8%,而转向状态E、N、U方向测速精度分别为2.81、2.03和1.91 cm/s,较传统模型分别提升了41.2%、45.9%和56.2%。...     

阿克苏河-塔里木河水系水质污染遥感监测与评价

 采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的 污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体 污染变化曲线,得出污染物浓度随着远离上游而增加。     

Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data

The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw.     

Landslide risk analysis between Giri and Tons Rivers in Himachal Himalaya (India)

The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies.     

Gravity Changes Before Large Earthquakes in China: 1998-2005

Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200...     

GNSS系统及其技术的发展研究

阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议.     

“4D”技术及其应用

介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。     

Virtual Australia: its key elements – know,think, communicate

Abstract

Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised.     

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.     

地理数据库的关系模型及其实现

本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4～9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。     

GIS空间数据的采集误差及其分析

本文详细阐述了GIS数据采集过程中的误差来源，重点分析了通过地图、遥感和摄影测量等方式采集数据所产生的误差及其特性，分析了其对GIS数据的影响与消减方法。