Preliminary investigation of seismic damage to two steel space structures during the 2013 Lushan earthquake

Severe damage to steel space structures is rarely reported when compared to other structural systems damaged during past major earthquakes around the world.Two gymnasiums of steel space structures in downtown Lushan County that were damaged during the 2013 M7.0 Lushan earthquake in China were investigated and the observations are summarized in this paper.Typical damage to these two steel space structures ranges from moderate to severe.Moderate damage includes global buckling and dislocation of bolted connections of truss members,and inelastic elongation of anchor bolts and sliding of pedestal plates of supports.Severe damage includes member fracture caused by local buckling,and fracture failure of anchor bolts and welds.The distribution of structural damage to these two structures is described in detail and future research opportunities are suggested.     

“数字重庆”地理空间信息定位基准体系的建设

介绍了"数字重庆"地理空间信息定位基准建设的基本情况,着重阐述了CQGNSS、高精度GPS控制网、精密水准网和区域似大地水准面精化等方面的数据处理情况,展示了山城地区的基准体系建设特点。     

数字增城地理信息公共服务平台的建设与研究

增城市地理信息公共服务平台的建设是利用Webservice、历史回溯等技术以满足各个部门对于基础地理信息的需求,实现地理信息跨部门共享、历史回溯和多元空间无缝集成,并最终达到建立在线服务系统,完成水利局等客户端试点、绿色通道3维景观演示,进一步提高服务端数据管理水平的目标,使得基础地理信息真正能为增城市各部门的建设提供良好的发展平台。     

基于双重逆极限空间的地貌信息数据挖掘方法

为了挖掘不完备的地貌数据信息,将地貌信息描述为拓扑空间的形式,从逆极限定义出发,利用映射诱导法建立与原地貌信息空间拓扑同构的双重逆极限空间作为目标信息空间,然后利用拓扑传递性分析原地貌信息空间与目标信息空间的拓扑相似度,实现不完备的地貌信息空间数据挖掘.本文利用GIS软件,结合地貌的坡度、坡向等地貌特征因子分别模拟了地貌信息数据挖掘前后的模型并进行了对比,结果表明此方法是可行的.     

Legal Geographies—Skating Around the Edges of the Law: Urban Skateboarding and the Role of Law in Determining Young Peoples' Place in the City

This article argues that urban skateboarding and the laws by which the city is governed must be understood as intertwined. The transformation of skateboarding's most popular practices from the 1970s onward are a product of an ongoing dialectical engagement between young people and the law. When faced with shifting landscapes of property and liability, young skaters have adapted their practices, seeking out new types of terrain. This search has led skateboarding into the public spaces of the city and regimes of urban governance. Contemporary efforts to build public skateparks in cities such as Seattle, Washington are properly contextualized as part of a continuing evolution of skaters' agency in responding to and capitalizing on openings in the legal landscape. By working both within the political system and constructing skateparks outside conventional political avenues, skatepark advocates seek spaces that are free from increasingly restrictive conventional logics of private and public property.     

基于MSAVI-WI特征空间的新疆渭干河-库车河流域绿洲土壤盐渍化研究

土壤盐渍化是造成干旱区土地荒漠化及生态恶化的重要原因,及时获取大尺度高精度土壤盐渍信息是防治工作的基础。选取新疆塔里木盆地北缘渭干河—库车河流域三角洲绿洲为研究区,利用Lansat-TM数据与野外实测数据分析盐渍化土壤与修改型土壤调整植被指数(MSAVI)、湿度指数(WI)之间的关系,在此基础上提出了MSAVI-WI特征空间概念,构建了土壤盐渍化遥感监测指数模型(MWI)。结果表明:MWI与土壤表层含盐量相关性较高,其相关性为0.844,精度高于土壤盐渍监测常用的盐分指数与实测数据的相关性。MWI能较好的反映盐渍化土壤地表植被及土壤水分的组合变化,具有明确的生物物理意义,并且特征参量简单,理论上易于理解,实践上易于实现,MWI模型的构建有利于干旱区大尺度土壤盐渍化定量监测与评价工作的开展。     

A GEOMETRIC ALGORITHM FOR TILTED-CAMERA PERSPECTIVE PROJECTION AND THE COMPARISON WITH EXTERNAL PERSPECTIVE PROJECTION

ABSTRACT

A geometric algorithm for Tilted-Camera Perspective (TCP) projection is proposed in this paper based on the principle of perspective projection. According to that, the difference between TCP projection and External Perspective (EXP) projecton is analyzed. It is put forward prerequisites making these two projections were compatible, and some examples are given.     

Shadow detection and compensation for color aerial images

A method for shadow detection and compensation for color aerial images is presented. It is considered that the intensity value of each image pixel is the product of illumination function and ground object reflection, and the shadowed regions on the image are mainly caused by the short of illumination, so the information compensation for the shadowed regions should concentrate on the illumination adjustment of concerned area on the basis of the analysis of whole image. The shadow detection and compensation procedure proposed by this paper consists of four steps.     

Wide-band multi-spectral space for color representation

This paper develops a wide-band multi-spectral space for color representation with Aitken PCA algorithm. This novel mathematical space using the broad-band spectra matching method aims at improving the accuracy of color representation as well as reducing costs for processing and storing multi-spectral images. The results show that the space can present our experimental original spectral spaces (i. e. Munsell color matt and DIN-6164 color chips) with high efficiency, and that the spanning space with three eigenvectors can present the original space at more than 98% CSCR, and when 5 eigenvectors are used it can cover almost the whole original spaces.