Chemical Composition of Urban Street Sediments and Its Sources

INTRODUCTIONBeijingfacesseveredustpollutionduetosuchsourcesasdustimportedfromwesterndeserts,industryandpowerplants,domesticcombustionprocessesandtraffic .Inthelastdecades ,theurbanpopulationhasgrowntomorethan10million .TheeconomicgrowthofChinahasalsoleftitsfootprintsinBeijing .Newindustrialzonesanddomesticar easweredeveloped ,inducinganincreasingtrafficcirculation(Shi,2 0 0 1) .Thedroughtclimateinalmostthewholeyear ,thestrongmonsoonsinwinterbringingdustsfromtheGobidesert,theheavytraffic…     

Toponymy and the Communist city: Street names in Bucharest, 1948–;1965

Past studies of the Socialist/Communist city have paid only limited attention to the ways in which Communist regimes mobilised a wide variety of symbols in the urban landscape in order to legitimate and institutionalise the ideology of revolutionary socialism. This paper considers the role of street names in this process with particular reference to Bucharest, Romania during the 1948–1965 period. When the Communist regime came to power it embarked on widespread renaming of streets as one means of both `decommemorating' the pre-socialist regime and proclaiming the agenda and ideology of the Communist state. The new street names commemorated a variety of events and personalities from the history of Romanian and Soviet Communism. The impact of street names was amplified further through practices such as multiple namings and the spatial clustering of street names of high ideological resonances. The paper argues that Bucharest's street names can be `read' as a mirror of ideological change, changing constructions of national identity, and Romania's macro-political orientation (especially its changing relations with the Soviet Union).     

基于空间句法视角的民国以来北京老城街道网络演变

研究基于空间句法理论与方法,结合不同时期的数字化历史地图,从街道网络显型、“局部—整体”层级关系及运转效率等三方面探讨民国以来北京老城的街道网络演变进程。结果表明：① 政权更替是其演变的分水岭。民国时期,老城街道网络由封建隔离结构向现代通达结构转型,环环相扣、中轴对称式的整合、穿行核心格局同时被打破。1949年中华人民共和国成立后,街道网络的几何格网特征越发明显,“环形+大格网”式的核心运动骨架凸显,不同街道段的可达性与穿行频率则逐渐趋同。② 老城各子区域的可达性层级关系在百余年来持续变化,穿行频率层级关系则保持稳定,与其他区域相比,东城的可达性与穿行频率优势明显。③ 政权更替之际新结构的集中嵌入与随后规划建设的路径依赖使得老城全域的运转效率历经“下降→上升→下降→上升”的起伏演变过程。这一过程同样出现在东城、西城与外城,但更强的几何格网特征促使前者的两次上升幅度较大,运转效率也相对较高,而皇城的运转效率则随小规模封闭系统的日益开放呈阶梯式下降。概括来讲,研究不仅运用数字化手段系统梳理了北京老城的街道发展史,为如何更好地保护古都风貌,传承历史文脉提供了街道网络视角的逻辑支撑,对于空间句法的理论算法体系也进行了一定拓展。     

Measuring urban activities using Foursquare data and network analysis: a case study of Murcia (Spain)

Among social networks, Foursquare is a useful reference for identifying recommendations about local stores, restaurants, malls or other activities in the city. In this article, we consider the question of whether there is a relationship between the data provided by Foursquare regarding users’ tastes and preferences and fieldwork carried out in cities, especially those connected with business and leisure. Murcia was chosen for case study for two reasons: its particular characteristics and the prior knowledge resulting from the fieldwork. Since users of this network establish, what may be called, a ranking of places through their recommendations, we can plot these data with the objective of displaying the characteristics and peculiarities of the network in this city. Fieldwork from the city itself gives us a set of facilities and services observed in the city, which is a physical reality. An analysis of these data using a model based on a network centrality algorithm establishes a classification or ranking of the nodes that form the urban network. We compare the data extracted from the social network with the data collected from the fieldwork, in order to establish the appropriateness in terms of understanding the activity that takes place in this city. Moreover, this comparison allows us to draw conclusions about the degree of similarity between the preferences of Foursquare users and what was obtained through the fieldwork in the city.     

基于Android平台的街景采集系统的研究

随着国民经济的发展、人们生活水平的提高,城市各街道的商铺、建筑物等更替速度越来越快,更新缓慢的街景地图服务已经无法满足日常生活的需求。专业的街景采集存在成本高、见效周期长、盈利性差、更新速度慢等诸多弊端。随着智能手机的广泛使用和手机像素的不断提高,街景采集工作出现了新的方式。本文以基于Android平台的街景数据采集系统为研究对象,对目前国内街景采集的现状进行了详细研究,设计数据库构架并阐述了在Android手机上建立库的流程。并以Eclipse为开发平台,利用Android SDK、高德地图SDK、ADT等插件,采用嵌入式开发方法,在Android手机上实现街景数据的采集、本地街景数据的存储管理和GIS的相关功能。     

基于倾斜摄影的三维城市建模研究

基于街景工厂与徕卡RCD-30倾斜摄影测量系统,研究了快速处理高分辨率、大数据量倾斜影像的技术流程,并以实际项目为例进行了数据处理,对项目的模型接边、模型效果、模型精度进行了分析和总结,对倾斜摄影技术在我国大规模的应用具有一定的指导意义。     

An effective spherical panoramic LoD model for a mobile street view service

Street view (panoramic view) services have begun to shift from PC platforms to mobile smart devices. Considering the capabilities of smart terminal devices, a 360° spherical level of detail (LoD) model for mobile street view services that renders panoramic images on the inner surface of a sphere via LoD is proposed in this article. Panoramic images are segmented into tiles and organized in a pyramid tile structure for LoD rendering to improve the rendering efficiency of the proposed model. A projection model between panoramic images and the spherical surface is presented to map the panoramic tiles on the spherical graticule. A street view‐rendering algorithm of panoramic images is proposed with the rendering function of OpenGL for Embedded Systems (OpenGL ES). A street view service app running on Android, based on the proposed approach, is implemented to assess two aspects of the panoramic view model, namely visualization effect and efficiency. Experiment results reveal that the 360° spherical LoD model of the panoramic image can display 3D street view scenes better than the cubic panoramic view model. The proposed model also has an excellent 3D visualization effect and high‐efficiency rendering ability for mobile street view services. Therefore, it is applicable in large‐scale mobile street view services both online and offline and in augmented reality navigation.     

The “von Karman vortex street” to the west of Big Island

Satellite-tracked drifting buoy data and altimetry data are used to study the active vortex field to the west of Big Island. A pair of vortexes were observed at the trajectory of buoy in 1995. The westward propagation of the vortex pair is studied in detail by reproducing the loops of each vortex. The orbital period and radius of the pair of vortex are determined to be 10-11 d and 58-68 km. Two arrays of contra-rotating vortices are displayed in the average sea surface height anomaly (SSHA) field to the west of Big Island. Based on the calculation of the fluid dynamical parameter, the “von Karman vortex street” is proved to be generated to the west of Big Island as the North Equatorial Current impinges upon Big Island from the east. Finally, the analysis of the buoy trajectories in a decade contributes to the conclusion of the pattern of VKVS in a statistical view.     

城市街道级GIS设计与研究

阐述了城市街道级GIS的概念及意义,并对城市街道级GIS的设计与实现方法进行研究,特别是城市大比例尺数据的分类、组织。以泰安市街道级GIS应用系统为例,详细阐述了街道级GIS设计的数据组织与管理、总体功能框架、系统功能模块等,解决了公交换乘、多媒体信息组织与管理等问题。     

扫描地形图中居民地街区提取和矢量化方法

提出了特征点提取和总体最小二乘拟合相结合的新方法,对扫描地图上的居民地街区进行提取和矢量化。本文首先对居民地街区进行轮廓跟踪得到初始的矢量数据,通过特征点提取进行数据压缩,再利用总体最小二乘方法对每条边线进行拟合,得到最终的矢量数据。此外,还提出了三个精度指标,对实验图中矢量数据的精度进行定量分析。结果表明,该方法能够提高居民地街区矢量化的准确性,消除冗余数据。