大地网三类设计的应变分析法

本文针对大地网三类设计的质量标准问题,提出了一种新方法:应变分析法。它可以根据区域性的尺度、旋转、变形三个应变参数的变化,来发现网的局部区域性系统差或粗差;并能较明晰地反映出新增观测值对原网的局部改进或细节改进。     

Short Note: A global model of pressure and temperature for geodetic applications

The empirical model GPT (Global Pressure and Temperature), which is based on spherical harmonics up to degree and order nine, provides pressure and temperature at any site in the vicinity of the Earth’s surface. It can be used for geodetic applications such as the determination of a priori hydrostatic zenith delays, reference pressure values for atmospheric loading, or thermal deformation of Very Long Baseline Interferometry (VLBI) radio telescopes. Input parameters of GPT are the station coordinates and the day of the year, thus also allowing one to model the annual variations of the parameters. As an improvement compared with previous models, it reproduces the large pressure anomaly over Antarctica, which can cause station height errors in the analysis of space-geodetic data of up to 1 cm if not considered properly in troposphere modelling. First tests at selected geodetic observing stations show that the pressure biases considerably decrease when using GPT instead of the very simple approaches applied to various Global Navigation Satellite Systems (GNSS) software packages so far. GPT also provides an appropriate model for the annual variability of global temperature. Electronic supplementary material The online version of this article (doi: contains supplementary material, which is available to authorized users.     

Short Note: On the Relativistic Doppler Effect for Precise Velocity Determination using GPS

The Doppler effect is the apparent shift in frequency of an electromagnetic signal that is received by an observer moving relative to the source of the signal. The Doppler frequency shift relates directly to the relative speed between the receiver and the transmitter, and has thus been widely used in velocity determination. A GPS receiver-satellite pair is in the Earth’s gravity field and GPS signals travel at the speed of light, hence both Einstein’s special and general relativity theories apply. This paper establishes the relationship between a Doppler shift and a user’s ground velocity by taking both the special and general relativistic effects into consideration. A unified Doppler shift model is developed, which accommodates both the classical Doppler effect and the relativistic Doppler effect under special and general relativities. By identifying the relativistic correction terms in the model, a highly accurate GPS Doppler shift observation equation is presented. It is demonstrated that in the GPS “frequency” or “velocity” domain, the relativistic effect from satellite motion changes the receiver-satellite line-of-sight direction, and the measured Doppler shift has correction terms due to the relativistic effects of the receiver potential difference from the geoid, the orbit eccentricity, and the rotation of the Earth.     

Short Note: Asymptotic theory for calculating deformations caused by dislocations buried in a spherical earth — gravity change

An asymptotic theory is presented for calculating co-seismic gravity changes, as a complement to a previous article by Sun [J Geod (2003) 77:381–387)], which presents the asymptotic theory for co-seismic geoid changes. Only the important formulas and results are summarized here; all the concepts and conventions are the same as for the companion paper. The theory is given by closed mathematical expressions so that it can be applied as easily as the flat-Earth theory. Moreover, since the asymptotic theory includes a sphericity effect, it is physically more reasonable than the flat-Earth theory.     

神经网络计算机及其在遥感应用中的展望

本文概述了神经网络计算机的基本特点、神经网络的形式化描述、目前国际上神经网络计算机的现况以及在遥感图像处理中应用的潜力和展望。     

Network Density Estimation: A GIS Approach for Analysing Point Patterns in a Network Space

Human activities and more generally the phenomena related to human behaviour take place in a network‐constrained subset of the geographical space. These phenomena can be expressed as locations having their positions configured by a road network, as address points with street numbers. Although these events are considered as points on a network, point pattern analysis and the techniques implemented in a GIS environment generally consider events as taking place in a uniform space, with distance expressed as Euclidean and over a homogeneous and isotropic space. Network‐spatial analysis has developed as a research agenda where the attention is drawn towards point pattern analytical techniques applied to a space constrained by a road network. Little attention has been put on first order properties of a point pattern (i.e. density) in a network space, while mainly second order analysis such as nearest neighbour and K‐functions have been implemented for network configurations of the geographical space. In this article, a method for examining clusters of human‐related events on a network, called Network Density Estimation (NDE), is implemented using spatial statistical tools and GIS packages. The method is presented and compared to conventional first order spatial analytical techniques such as Kernel Density Estimation (KDE). Network Density Estimation is tested using the locations of a sample of central, urban activities associated with bank and insurance company branches in the central areas of two midsize European cities, Trieste (Italy) and Swindon (UK).     

GIS模糊可靠性分析的基本理论

文中首先分析了GIS模糊可靠性对于GIS的意义，接着论述了GIS可靠性分析引入可靠性工程理论和模糊集的理由，具体阐述了GIS模糊可靠性的几个主要的基本概念，详细论证了GIS可靠性存在着模糊性，并指出了其产生的原因；然后阐述了GIS模糊可靠性分析的几种计算方法和GIS模糊可靠性分析常用的几种模型；最后指出了存在的问题和对GIS模糊可靠性分析仍需大力研究的结论。     

沈阳市地铁二号线GPS控制网的建立与数据处理

介绍了沈阳市地铁二号线北延工程平面控制网的建立与数据处理过程,通过对精度指标的分析,总结了本次控制网工程的特点,对日后施工作业提供参考作用。     

沈阳市桃仙机场改扩建GPS控制网的建立与数据处理

介绍了沈阳市桃仙机场改扩建GPS控制网的建立与数据处理过程,通过对精度指标的分析,总结了本次控制网工程的特点。     

Decomposition of deformation primitives of horizontal geodetic networks: application to Taiwan’s GPS network

The contribution to each component of the deformation vector due to a marginally undetected blunder in an observation is split into two parts, and so are the deformation measures at a point. The first part, called the local component (or self component), signifies the contribution due to the redundancy-related multiplier belonging to the observation itself, while the second part, called the complementary component, shows the contribution due to the non-redundancy-related multipliers belonging to the observation. A larger redundancy results in a smaller local component for each component of the deformation vector. However, robustness due to an observation at a point is correlated with redundancy to a significant extent. The first-order global positioning system (GPS)-geodetic network of Taiwan was examined for its robustness. The experiments seem to indicate that: (1) large deformations tend to be found at points where the group redundancies are small; (2) the local components monopolize deformation measures at the perimeter stations of the network where very small redundancy numbers are found; (3) the largest deformation at a point may be due to an observation not directly tied to the point of interest; and (4) except for local twisting, deformation measures and mean positional precisions at individual points are highly correlated.Acknowledgement The authors thank Drs. A.A. Simkooei, M. Schmidt, and M.R. Craymer greatly for their constructive comments and suggestions, which improved the quality of the paper. This research was supported by National Science Council of Taiwan (contract number NSC-91-2211- E-002-085).     

扫描数字化图质量的应变张量评估法

引入了应变张量分析法表示数字化地图的质量,给出了应变张量的几何解释和计算方法,并以一幅实际数字化图为例,证明了地图数字化质量应变张量评估法的有效性。     

短期潮汐潮流数据的正交潮响应分析研究

论证并试验证明了正交潮响应分析对潮汐潮流数据的时间长度的要求,得出理论最短数据时间长度为2 d;但对于实测数据,要求在以全日潮为主的海区需7 d以上数据,在以半日潮为主的海区需10 d以上。对于一天到几天的数据,通过引入比例关系和改变模型中Δτ的取值,实现了对数据的建模分析。经对中国12个主要验潮站连续366 d数据的试验验证,短期与长期(1 a)数据分析结果相近,而与准调和分析相比较,正交潮响应分析具有较高的精度,且不存在良好天文观测日期的选择问题。     

动态定位的模型偏差检测与校正

动态定位的数据处理中广泛应用卡尔曼滤波,而卡尔曼滤波的应用要求动态模型(函数模型)和随机模型可靠和切合实际,但实际测量定位中难以保证观测对象的规则运动,因而容易出现模型误差.探讨在实际应用中存在模型误差时的卡尔曼滤波,研究动态定位时卡尔曼滤波的模型检测与校正,给出一种偏差分离估计方法.由于不存在状态增广,因而该方法计算效率高.最后以一数字仿真(模拟)实验论证方法的可行性.     

基于三角模糊数的GIS的可靠性分析(英文)

首先就三角模糊数运算的基本规则作了简单的介绍,阐述了三角模糊数用于GIS可靠性分析的方法与步骤,然后用实例进行了分析,最后就全文进行总结并指出了需要解决的问题。     

GPS短边网精度的研究

《ＧＰＳ测量规范》规定了ＧＰＳ测量的等级及各级ＧＰＳ网相邻点间距离,最低级Ｅ级网相邻点间距为１～１０ｋｍ,平均边长为２～５ｋｍ。根据工程的要求,有时控制网相邻点间距仅为几十至几百米,文中针对ＧＰＳ短边网的数据处理和精度进行分析,并对ＧＰＳ网的质量检核进探讨,采用全站仪对网进行检核发现ＧＰＳ边长误差在５ｍｍ以内。     

Measuring the robustness potential of the least-squares estimation: geodetic illustration

For a linear least-squares parametric model analysis is carried out of the structure of the projection operator transforming the vector of standardised observations into the vector of standardised residuals. On this basis the properties of the model responses to observational disturbances (i.e. gross errors or blunders) are derived. A final outcome of the research can be summarised as: (1) proposing the robustness characteristics of a model and linking them with the local measures of internal reliability, being the diagonal elements in the projection operator; (2) determining the internal reliability levels satisfying specified robustness requirements, i.e. the possibility of detecting at least one of the k observational disturbances (k=1,2,…) having most disadvantageous locations in the system. The theory and a numerical example show that for the systems which have been designed to a proper level of internal reliability, the least-squares estimation can demonstrate an accordingly high level of robustness. Received: 11 June 1996 / Accepted: 28 April 1997     

基于 SDCORS 的网络 RTK 在城市区域测量效率与精度测试分析

利用SDCORS提供的网络RT K服务,在山东建筑大学校园内利用一台RT K GPS接收机,从初始化时间、定位精度及可靠性等方面对SDCORS 网络RTK的性能进行了测试与分析。实验表明：待测点周围环境对网络 RT K 初始化所需时间影响较大,在开阔区域,RT K从浮点解到获得固定解的时间约需2 s ,在树木及建筑物等遮挡比较严重的环境下初始化时间约需几分钟甚至更长;在城市环境下,基于SDCORS的网络RT K动态定位的精度达到3 cm左右。     

沈阳市地铁九号线GPS控制网的建立与数据处理

介绍了沈阳市地铁九号线GPS控制网的建立与数据处理过程,通过对精度指标的分析,总结了本次控制网工程的特点。     

可靠性空间分析初探

从工程和生命科学的可靠性概念出发,结合地理信息科学的自身特点,强调空间数据及分析的全过程质量和分析结果的决策可用性。首次给出了可靠性空间分析的概念,分析了可靠性空间分析的特点、面临的主要问题和研究方法,探讨了可靠性空间分析的主要理论、研究方向和应用领域,促进了空间分析从不确定性研究向可靠性空间分析方向的发展。