基于近海定常环流高程模式的平均海面地形联合解算方法

联合卫星测高和物理海洋监测数据计算海面地形和测高大地水准面（以下称联合问题）是卫星测高应用领域的前沿课题之一。本文从流体动力学基本方程出发,推导出近海定常环流的高程模式,由此高程模式出发利用有限差分法组成观测方程,从而按最小二乘间接平差法解算联合问题。最后联合 Ｔ／ Ｐ、 Ｅ Ｒ Ｓ－ ２卫星测高和物理海洋监测数据,计算了东中国海（ ２２°－ ４１°×１１６°－ １３１°）的平均海面地形。     

基于近海定常环流高程模式的平均海面地形联合解算方法

联合卫星测高和物理海洋监测数据计算海面地形和测高大地水准面是卫星 高应用匠前沿课题之一。本文从流体动力学基本方程出发,推导出近海定常环流的高程模式,由此高程模式出发利用有限差分法组成观测方程,从而按最小二乘间接平地解算联合问题。     

精密测距三角水准测量的研究

本文从理论上分析了T2000测距三角高程的各项误差,提出了按跳点法观测的垂线偏差影响公式和精度达0.2毫米的量高方法,讨论了减弱大气垂直折光影响的措施。通过150公里的比较试验,得出了S≤500米,α≤10°按跳点法观测或S≤1公里、α≤8°按对向测距三角高程均能达到二等水准精度要求的结论。     

芬兰GPS水准的试验

一、概况最近几年芬兰在南部地区,对ＧＰＳ水准进行了较全面的试验。试验选定了两个区,均在北纬６０°～６２°之间,Ⅰ区在东,Ⅱ区在西。Ⅰ区面积９０００ｋｍ２,区内高程约在０～１２０ｍ之间,Ⅱ区面积约１００００ｋｍ２,区内高程约在７～１２２ｍ之间。二、水准...     

IRNSS和QZSS在各自主服务区域的L5定位性能评估：独立系统与GPS联合

印度区域导航卫星系统（IRNSS）与日本准天顶系统（QZSS）是近年来宣布正式运行的两个区域卫星导航系统。本文首先评估了IRNSS和QZSS在各自主服务区域的L5信号单点定位性能。然后,为了探究导航星座结构差异对各区域系统联合GPS在城市峡谷环境下定位性能的影响程度,详细对比分析了卫星截止高度角为5°、15°、25°、35°、45°、55°时各区域系统在其主服务区内联合GPS定位的表现。结果表明：① IRNSS在其主服务区内可提供全天连续独立L5定位服务,水平方向定位精度小于2.50m,高程方向定位精度小于4.10m;② QZSS在其主服务区内只能提供全天部分时段的独立L5定位服务,水平方向定位精度小于4.80m,高程方向定位精度小于7.40m;③由于QZSS独特的星座结构,其在主服务区城市峡谷环境中联合GPS定位的性能要优于IRNSS在其相应主服务区联合GPS定位的表现,尤其是在天空视野有限的情况下。本文结果对决策者设计新的区域导航系统具有一定的参考价值。     

经验点滴

用查表法直接查取水平角观测中仪器垂直轴倾斜改正数按“一、二、三、四等三角测量细则”的规定,当进行水平角观测时,若照准点的垂直角在一等超过±2°（TT 2″/6″）和± 1°（T_3）、在二等超过±3°（TT 2″/6″）和±2°（T_3）时,则须在观测时读定水准器分划值,于观测值中加入垂直轴倾斜改正数。在实际作业中,若对各观测值逐一计算其相应的垂直轴倾斜改正数,颇为费时。若能预先编算出“水平角观测垂直轴倾斜改正用表”用查表的办法直接查取,则甚为便利。     

星载SAR水下地形和水深遥感的最佳雷达系统参数模拟

根据星载合成孔径雷达 (SAR)浅海水下地形和水深成像机理 ,建立了浅海水下地形和水深雷达后向散射截面仿真模型。该模型包括奈维 斯托克斯方程、谱作用量平衡方程和雷达后向散射模式。利用该模型仿真结果 ,探讨了不同波段 (P、L、C和X)、不同极化 (VV和HH)和不同入射角 (2 0°— 70°)的星载SAR测量浅海水下地形和水深的能力。研究结果表明 ,浅海水下地形和水深遥感的最佳波段为P波段 ,L波段次之 ,C波段比X波段要好一些。VV极化SAR的测量能力要强于HH极化。 2 0°— 40°是星载SAR测量浅海水下地形和水深的最佳入射角范围。     

检验测角仪器水平度盘直径误差的纲要和方法

根据一、二、三、四等三角测量细则的要求,所有用于一、二等三角点上作水平角观测或用于拉伯拉斯点上作方位角观测的仪器,都要每隔3°测定水平度盘的直径误差。测定在检验室内进行,其方法是观测由照准器所构成的36°, 45°和60°三个角。     

用ДHБ-2视距经纬仪在高山地区施测高程导线的经验

前 言我队对航测作业高程控制点的连测,过去两年大都采用普通经纬仪导线法。因此,对这一方法操作较熟悉,故今年计划高程控制点的连测时,大部分仍拟采用此法。但今年测区山势陡峻（因森林荫蔽不适用多角高程导线）,在开工时就发现了所测导线倾斜角有达30°者,15°—25°的情况则更多。根据实地的摸索与计算的证明,此法不适合山区使用。这是因为视距精度受倾斜角增大的影响很大,更何况倾斜角增大时即同样的距离误差也会产生更大的高程误差,现列表作如下说明：     

中国地区1°×1°点质量解算与精度分析

从重力异常相关性分析，地面重力异常场逼近效果以及数值计算稳定性出发，讨论分析了外部引力场扰动点质量赋数值，提出以窗口移动方式控制点质量对场元观测的作用范围，简化了模型结构。在此基础上，提出算经结构简化后具有稀疏矩阵特征的边值条件方程的超松驰迭代法，并实际解算了中国地区１°×１°点质量。     

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。