Geometric Integration of Aerial and High-Resolution Satellite Imagery and Application in Shoreline Mapping

This paper investigates the geopositioning accuracy achievable from integrating IKONOS and QuickBird satellite stereo image pairs with aerial images acquired over a region at Tampa Bay, Florida. The results showed that the accuracy is related to a few factors of imaging geometry. For example, the geopositioning accuracy of a stereo pair of IKONOS or QuickBird images can be improved by integrating a set of aerial images, even just a single aerial image or a stereo pair of aerial images. Shorelines derived from the IKONOS and QuickBird stereo images, particularly the vertical positions, are compared with the corresponding observations of water-penetrating LiDAR and water gauge stations and proved that differences are within the limit of the geopositioning uncertainty of the satellite images.     

Web-Based GIS as a Tool for Supporting Marine Research

Collecting marine data during hydroacoustic research surveys is a complex task, which not only consists of measurements but also analysis, validation, and interpretation of information acquired by various sensors. Automatic integration, visualization, and processing of collected data allow for a more precise investigation of the researched phenomena. The paper presents a dedicated Web-based system for fusion and dissemination of data from satellite imagery, hydrological measurements using CTD probes, acoustic surveys by multibeam systems, side-scan sonars and singlebeam echosounders, as well as live radar feed and oil spill spread models. The system has been designed as a tool for supporting research using the aforementioned techniques.     

地理视频数据模型及其应用开发研究

讨论地理视频的基本概念和数据模型,尝试提出地理视频数据的实体-关系图,并在网络环境中进行地理视频应用开发.地理视频数据模型的核心要素是:对视频帧进行位置和语义描述,建立视频片段的轨迹图层和元数据,并在轨迹图层中扩充视频帧线性参照.通过空间参照、线性参照和语义参照将视频数据与地理数据集成,实现地理视频的查询、检索、播放和地图跟踪.以河南大学校园和开封市公路网络为例,采集地理视频数据,建立地理视频数据库,发布网络地图和视频服务,并分别采用最新的Adobe Flex框架、ArcGIS Server ADF和JavaScript Mashup方式,开发网络视频GIS应用系统.原型系统开发表明,地理视频数据模型适用于网络视频GIS开发,且在技术实现上较为简单.     

Extensions of nonlinear error propagation analysis for explicit pseudodynamic testing

Two important extensions of a technique to perform a nonlinear error propagation analysis for an explicit pseudodynamic algorithm (Chang, 2003) are presented. One extends the stability study from a given time step to a complete step-by-step integration procedure. It is analytically proven that ensuring stability conditions in each time step leads to a stable computation of the entire step-by-step integration procedure. The other extension shows that the nonlinear error propagation results, which are derived for a nonlinear single degree of freedom (SDOF) system, can be applied to a nonlinear multiple degree of freedom (MDOF) system. This application is dependent upon the determination of the natural frequencies of the system in each time step, since all the numerical properties and error propagation properties in the time step are closely related to these frequencies. The results are derived from the step degree of nonlinearity. An instantaneous degree of nonlinearity is introduced to replace the step degree of nonlinearity and is shown to be easier to use in practice. The extensions can be also applied to the results derived from a SDOF system based on the instantaneous degree of nonlinearity, and hence a time step might be appropriately chosen to perform a pseudodynamic test prior to testing.     

区域流动空间整合与全球城市网络构建

流动空间作为新时期的新空间形式已经开始影响区域空间的结构与城市体系的形成与发展。文章通过区域流动空间的整合研究,发现在流动空间中,连接性弱化物理邻近性,关系论更新区位论,区域空间关系被重新整合。在新的区域空间关系中,流动空间的网络动力与结构表现出集聚与扩散、等级结构与地域差异等特征。这种关系进一步作用于传统的中心地体系,形成流动空间的网络城市体系,进而构筑全球城市网络体系。     

基于DEM的任意方向坡度计算方法

坡度是数字地形分析中重要的地形因子,在水文分析、土壤侵蚀模拟、地貌类型划分等地学分析及工程上均有广泛的应用。由于地形的各向异性,坡度在各个方向上并不相同。目前,基于DEM所提取的坡度,均是位于最陡方向上的坡度,而任意给定方向坡度计算是地学分析和工程应用中较为常见的问题。在对目前DEM坡度提取算法研究的基础上,通过数学分析,给出了格网DEM上任意方向格网点的坡度计算模型和计算流程,并给出了相应的计算实例,从而将坡度计算模型从特定方向推向任意方向,使DEM坡度计算更具普适性。     

不透水地基上堤坝上游坡的附加渗径

根据努美罗夫的理论解,附加渗径 与上游水深H成正比,与单宽流量与渗透系数的比值q/k成反比。按该理论解的浸润线方程,应用数值积分法求出比例系数 和 ,并提出了有足够精度的拟合式。边坡有压流的附加渗径 仅与透水层厚度T成正比,而和H、q/k无关, 。根据计算结果, 。对于 反比于q/k,文中作了分析和解释。该计算方法还可推广应用于上游坡下有一定厚度覆盖层的附加渗径计算,并且对附加渗径的各计算式作了比较和分析,并以实例说明了如何应用附加渗径计算堤坝的渗流。     

多点输入下大跨结构地震反应的频域精细传递矩阵法

地震输入问题一直是工程结构抗震研究所关注的焦点.在对大跨度结构进行抗震设计时,需要考虑多点地震输入的影响已成为国内外学术界和工程界的共识.本文根据傅氏变换,运用精细传递矩阵法推导出了大跨结构在多点地震输入下的频域精细传递矩阵,并在频域内对大跨度结构进行了动力分析.这种方法公式简单,能够快速、高精度地进行结构的地震反应分析.算例显示了本文方法的有效性.     

ShakeMap二次开发与软件集成研究

通过分析ShakeMap的软件组成、数据结构,探讨了ShakeMap的二次开发及该软件与国内现有强震动软件的集成方法,并针对ShakeMap二次开发后运行时的数据锁定问题(多用户模式下的数据锁定)给出解决方案。     

新疆防震减灾中心系统集成设计与实施

结合新疆防震减灾中心的实际,论述了系统集成项目的建设概况、集成设计与实施内容,以及集成实施后集成成果和其发挥的效益.系统集成建设满足了各台网部的工程设计要求,同时达到了在技术、资金等方面的优化,大大提高了整个防震减灾中心系统运行的安全性和稳定性.