城区独立坐标系及基本控制网的建立

结合生产实际详细介绍城区独立坐标系建立的方法、GPS控制网的数据采集、基线向量的检核及GPS控制网利用GPSurvey软件,在城区独立坐标系中的平差方法,为建立城区独立GPS控制网积累了经验.     

沂源县城区独立坐标系建立的研究

本文结合生产实际详细的介绍了城区独立坐标系建立的方法、GPS控制网的数据采集、基线向量的检核及GPS控制网利用GPSurvey软件，在城区独立坐标系中的平差方法，为建立城区独立GPS控制网积累了经验。     

测距基线对精密交通GPS网的精度影响

讨论了长距离精密GPS控制网的特点,通过设置不同的精密测距基线,计算相应GPS控制网的精度,从而掌握连接方式、重复基线、精密测距仪基线对GPS网精度影响的规律,解决了长距离精密工程GPS网的建立方法。     

雁门关隧道控制网的建立及精度分析

论述了长大隧道洞外独立控制网建立方法,将WGS-84坐标系统无约束平差基线精度作为洞外独立GPS控制网的精度指标,并以WGS-84坐标系统无约束平差结果作为工程独立控制网的计算基准来获取二维工程平面坐标。     

城口县1∶500城镇地籍测绘工程独立坐标系统建立研究

本文简要分析了高程归化与高斯投影综合变形,介绍了建立地方独立坐标系中央子午线和抵偿投影面,并计算独立椭球参数的原理。运用重庆市国土资源和房屋管理局GNSS连续运行参考站系统技术建立了工程地区的独立坐标系统,建立了该县首级GPS控制网,包括数据采集、基线向量检核等,用常规测量方法进行了有关边长检验,为建立工程建设地区独立坐标系统GPS控制网积累了经验。     

模拟GPS控制网精度估算方法研究

精密GPS控制网的建立必须经过先模拟设计再实施两个阶段.讨论了以控制点文件和基线向量文件保存在电子地图上进行GPS网,顾及多时段重复基线和精密测距基线,用二维约束平差的方法实现对GPS模拟控制网的精度估算.     

起算点的分布和基线连接方式对GPS工程控制网的精度影响分析

GPS以其高精度、全天候、外业操作简单等优点,广泛应用于各种工程控制网的建立。本文通过几组相关实验,分析不同起算点分布以及不同独立基线连接方式对GPS控制网平差精度的影响,得出一些有益的结论,对生产实践工作具有一定的借鉴作用。     

一种基于GPS—RTK的超快速静态控制测量新方法

讨论利用GPS-RTK的作业模式,采用超快速静态建立GPS控制网的新方法。将常规的RTK方法中参考站固定不动改变为参考站和流动站交替流动,每时段至少获得一条独立的基线向量,所有的基线按设计的网形组成多边形GPS网,网的各项指标执行城市GPS规范,数据按静态网的数据处理方法进行。实践结果表明,该方法获得的结果可靠,具有速度快、效率高、操作简便等特点,能达到城市GPS规范各等级的精度要求。     

静态GPS控制测量基线精度统计分析

如何提高基线的精度,是GPS控制测量理论与方案设计实践中必须考虑的关键问题之一.运用在豫东地区1 800 km2区域航磁异常查证项目中所施测的E级GPS控制网中的大量基线,通过不同方案自由网平差后的基线相对精度数据的统计分析,揭示基线精度与框架网及端点重复设站数之间的关系,提出在大区域GPS控制测量中,不必设置框架网以及基线精度与端点重复设站数密切关联的实践证据,为大区域GPS控制网的建立提供了有益的借鉴.     

上杭县矿业权核查GPS控制网布网方案探讨及精度分析

本文介绍了上杭县矿业权实地核查GPS控制网的布设方案,包括GPS控制网技术设计、外业观测、基线向量解算、控制网平差及精度分析和可靠性检验等。同时对GPS平面控制网建立的有关问题提出一些建议。     

Pinpointing the sources and measuring the lengths of the principal rivers of the world

Abstract

Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable.     

世纪之交的沉思--论21世纪软科学的发展

软科学这一术语是70年代在国外提出的.然而30多年以来,它在国外不仅未得到普遍的承认,而且对软科学的定义也还未能达成大体上一致的共识.而在改革开放后的中国,出于决策科学化和民主化的需要,经过一些领导人的提倡和支持,特别是通过1986年召开的软科学座谈会及1994年召开的全国软科学工作会议,软科学事业得到了蓬勃的发展.据初步统计,截止1998年底全国共有软科学研究机构1224个,研究人员32655人,初步形成了一支较为强大的研究队伍,并取得了数百项覆盖多个领域的研究成果,为支持各级各类的决策发挥了一定的作用.     

Improving the modeling of the atmospheric delay in the data analysis of the Intensive VLBI sessions and the impact on the UT1 estimates

The very long baseline interferometry (VLBI) Intensive sessions are typically 1-h and single-baseline VLBI sessions, specifically designed to yield low-latency estimates of UT1-UTC. In this work, we investigate what accuracy is obtained from these sessions and how it can be improved. In particular, we study the modeling of the troposphere in the data analysis. The impact of including external information on the zenith wet delays (ZWD) and tropospheric gradients from GPS or numerical weather prediction models is studied. Additionally, we test estimating tropospheric gradients in the data analysis, which is normally not done. To evaluate the results, we compared the UT1-UTC values from the Intensives to those from simultaneous 24-h VLBI session. Furthermore, we calculated length of day (LOD) estimates using the UT1-UTC values from consecutive Intensives and compared these to the LOD estimated by GPS. We find that there is not much benefit in using external ZWD; however, including external information on the gradients improves the agreement with the reference data. If gradients are estimated in the data analysis, and appropriate constraints are applied, the WRMS difference w.r.t. UT1-UTC from 24-h sessions is reduced by 5% and the WRMS difference w.r.t. the LOD from GPS by up to 12%. The best agreement between Intensives and the reference time series is obtained when using both external gradients from GPS and additionally estimating gradients in the data analysis.     

Movements of the protoplanetary superconducting particles in the magnetic field of the Saturn lead to the origin of the rings

In this letter, we are trying to resolve the electromagnetic problem for the movements of the superconducting particles of the protoplanetary cloud in the magnetic field of Saturn. The force of levitation (Meissner-Ochsenfeld phenomenon) is introduced to the field of planetary science for the first time. It is shown from our theoretical analysis that rings of Saturn might have a superconducting origin, and rings might levitate within magnetic equator plane of the planet.     

省直管市（县）体制下建设用地监管技术研究

面向解决省直体制下市（县）建设用地管理业务监管难度大问题,研究建设用地全过程监管关键技术,设计该模式下的监管模式、技术架构、业务模型和数据模型,实现省直管市（县）模式下的建设用地批前、批中、批后＂批-供-用-补-查-登＂全过程监管。     

GPS整周模糊度确认中残差二次型次小与最小之差的分布问题

根据残差二次型次小与最小之差进行整周模糊度确认的关键是差值的分布,只有得到了合理的差值分布才可确定合理的界值.文中基于原有的两种方法及这两种方法的不足,从理论上导出了满足条件的差值分布,并作了一定的说明.