GPS网络RTK技术及应用

本文主要介绍了GPS网络RTK的基本组成和原理，以及该技术在国内外的应用。本文的论证围绕四川省地震局VRS系统实例展开，结论表明VRS是一套非常稳定可靠的系统，能满足城市测量等高精度需求。该系统为城市建设部门、规划部门、政府决策部门提供了简便、有效的数据采集手段。     

Stress transfer in earthquakes, hazard estimation and ensemble forecasting: Inferences from numerical simulations

Observations indicate that earthquake faults occur in topologically complex, multi-scale networks driven by plate tectonic forces. We present realistic numerical simulations, involving data-mining, pattern recognition, theoretical analyses and ensemble forecasting techniques, to understand how the observable space–time earthquake patterns are related to the fundamentally inaccessible and unobservable dynamics. Numerical simulations can also help us to understand how the different scales involved in earthquake physics interact and influence the resulting dynamics. Our simulations indicate that elastic interactions (stress transfer) combined with the nonlinearity in the frictional failure threshold law lead to the self-organization of the statistical dynamics, producing 1) statistical distributions for magnitudes and frequencies of earthquakes that have characteristics similar to those possessed by the Gutenberg–Richter magnitude–frequency distributions observed in nature; and 2) clear examples of stress transfer among fault activity described by stress shadows, in which an earthquake on one group of faults reduces the Coulomb failure stress on other faults, thereby delaying activity on those faults. In this paper, we describe the current state of modeling and simulation efforts for Virtual California, a model for all the major active strike slip faults in California. Noting that the Working Group on California Earthquake Probabilities (WGCEP) uses statistical distributions to produce earthquake forecast probabilities, we demonstrate that Virtual California provides a powerful tool for testing the applicability and reliability of the WGCEP statistical methods. Furthermore, we show how the simulations can be used to develop statistical earthquake forecasting techniques that are complementary to the methods used by the WGCEP, but improve upon those methods in a number of important ways. In doing so, we distinguish between the “official” forecasts of the WGCEP, and the “research-quality” forecasts that we discuss here. Finally, we provide a brief discussion of future problems and issues related to the development of ensemble earthquake hazard estimation and forecasting techniques.     

基于低空摄影数据的三维校园场景构建

为满足对外展示和发展规划的需要,开发了一套三维漫游展示系统。系统是以Quest3D为平台,利用低空无人机（UAV）航空摄影技术结合三维建模软件（3DsMAX）来构建校园的三维真实场景,最后在多通道环幕（立体）仿真投影系统上进行漫游展示。对其技术关键、基本流程及展示进行了较为详细的阐述,为相关三维虚拟场景构建和展示工作提供了较好的实践参考。     

基于Sketchup和Google Earth的3D虚拟校园建设

以重庆市第十八中学的虚拟校园建设为例,阐述了基于Sketch Up和Google Earth的具有良好的现实还原度和更短的开发周期的虚拟校园建设方案。同时,指出了一些较重要问题的解决方案。     

Monitoring the Ocean Surface Topography Virtual Constellation: Lessons Learned from the Contribution of SARAL/AltiKa

Altimetry missions are usually presented to the user communities with rather short lifetime durations of the order of five years. However in practice, most altimeters can remain in operations for twice as long, although often in a degraded state (coverage and/or accuracy) and with a higher risk of mission loss. Early in the design of the SARAL/AltiKa mission, this Ka-band technology demonstrator has been envisioned as a contributing mission to the so-called Ocean Surface Topography Virtual Constellation (OST-VC) of the Committee of Earth Observation Satellites (CEOS). This article uses the experience feedback from SARAL and its launch delay on the OST-VC. Using a simple yet quantified probability model, we illustrate the value of anticipating the periods where the constellation is fragile, and we identify the next periods where actions can be undertaken by CEOS Agencies to strengthen the OST-VC.     

地质特征三维分析及三维地质模拟现状研究

自然地质现象极其复杂，三维实体普遍存在，随着地学研究不断深入，三维地质模拟已引起了地球科学界的高度重视，目前已经研制出了多种三维地质模拟软件，并被广泛应用到地质、矿产、水文、物探、地震、环境等各个领域。从地质体结构、构造、类型、分布等方面，系统地分析了地质体三维特征，总结了国内外三维地质模拟软件在地质构造、地质工程、矿山测量、地球物理等方面的开发现状，指出三维地质模拟在软件开发方面存在的问题及在地质数据采集、处理、解释、利用方面所面临的困难，并从三维空间数据结构、技术方法、应用研究等方面阐述了三维地质模拟新进展，最后论述了开展三维地质模拟的意义。     

气象影视虚拟演播室的性价比分析

为使气象部门选择到功能合理、高性价比的虚拟演播室系统,概述了虚拟演播室的概念、基本工作原理,并对虚拟演播室的各种类型进行性价比分析。结果表明:根据气象部门的实际情况,建议选择采用机械传感跟踪方式的三维虚拟演播室系统,其他类型可供参考。     

数字天气雷达虚拟终端的硬件和软件设计

设计了一套基于PC机的数字天气雷达虚拟终端系统,用普通的PC机代替传统数字天气雷达信号处理分机[1,2]直接完成雷达信号处理和实时显示。该系统在硬件方面,设计了基于PCI总线的三通道高速数据接收卡,以满足大容量数据高速传输要求;在软件方面则利用高级语言(C )和虚拟设备驱动程序(WDM)技术开发了一套基于WINDOWS2000/9X操作系统的实时处理软件,以此控制数据接收卡和雷达工作,并完成信号处理和实时显示。实际应用表明,该系统结构简单、界面友好、操作方便、便于升级,完全能够实时、高效地处理常规天气雷达信号,而且处理后的雷达回波层次清楚,具有较高精度。本研究也为虚拟终端应用到多普勒天气雷达打下了一个良好的基础。     

基于断层虚位错模式讨论2008年汶川MS8.0地震前视电阻率变化

2008年汶川M_S8.0地震前,距震中450km范围内有7个视电阻率台站运行,震前记录到了不同形态和幅值的变化。本文采用断层虚位错模式,在模型中将汶川地震同震滑动位移按大小相等但方向相反的方式进行加载,计算震前产生这些同震位错所需积累的应力应变分布。计算结果表明：在100m深度,震前正应力和剪切应力主要积累区域位于龙门山断裂带两侧约100km范围内,最大应力变化量为0.5MPa;体应变积累区域与应力积累区域基本一致,最大应变值为10^-5,显示这些区域在震前存在较高的挤压应力应变积累,而在这些区域外,应力应变积累程度较低。成都台和江油台位于震前主要的应力应变挤压积累集中区域,视电阻率观测数据均为震前下降-准同震阶跃-震后回升,与震前应力应变积累-震后释放的变化形式一致,这2个台站震前的异常变化与汶川地震关系密切;而甘孜台、武都台、冕宁台、小庙台和天水台位于应力应变积累较弱的区域,其视电阻率变化与汶川地震的关联性较弱。     

新一代移动三维GIS平台研究

5G时代的到来,使人们对移动三维GIS平台的需求也越来越高,然而移动GIS技术面临诸多机遇和挑战.随着GIS行业的发展和用户更高的要求,出现了新一代移动三维GIS平台.本文分析了新一代移动三维GIS平台在三维数据、虚拟漫游、双方式数据加载、智能数据处理和丰富统计分析等方面技术上的要求,设计了系统平台框架和双方式数据加载...