北京城区绿地防灾避险功能评估   总被引：2，自引：0，他引：2  

张灿强  张彪  李文华  谢高地  肖玉 《地理研究》2012,31(12):2301-2309

城市绿地具有重要的防灾避险功能。以北京城区具有防灾避险功能的绿地为研究对象, 划定了不同类型绿地的防灾避险服务半径, 利用ArcGIS的缓冲区分析工具, 对研究区内绿地 的防灾避险服务范围进行了分析。结果表明:绿地防灾避险有效服务面积占研究区的 71.22%,3.94万hm²的区域处于服务盲区, 主要分布在五环路以外的海淀、丰台和朝阳区; 从防灾避险绿地和服务范围的覆盖率来看, 西城区>东城区>朝阳区>石景山区>海淀区> 丰台区, 有111个街道、地区办事处和乡镇覆盖率在90% 以上, 但仍有占研究区面积 24.08%的办事处和乡镇覆盖率在80%以下;此外, 防灾避险绿地及服务区覆盖率由市中心向 外围呈现递减趋势。  相似文献   

Distribution of cacti in Larrea spp. shrublands in Mendoza, Argentina     

E. Mndez  J. C. Guevara  O. R. Estevez 《Journal of Arid Environments》2004,58(4):414

In three Larrea shrublands, cacti grow under Larrea canopy at northern and southern exposures and in open spaces were counted. Cacti distribution was related to environmental variables. Seven out of the 15 cacti present were found to be associated with shrubs, whereas the other species were found in the open spaces. The lower temperature and radiation occurring under shrubs at south exposures would explain the absence of cacti in these places. The higher organic matter, nutrients, and moisture in the soils under shrubs appeared to be correlated with higher cacti density. The presence of cacti seedlings only under shrubs could be attributed to the favourable environmental conditions for cacti seed germination and seedling survival that occurred in these places.  相似文献   

The Working World of the Paladar: The Production of Contradictory Space during Cuba's Period of Fragmentation*     

Edward &#x;&#x;&#x;&#x;&#x;&#x;L. Jackiewicz  Todd Bolster 《The Professional geographer》2003,55(3):372-382

This article examines the social spaces of self‐employment in Havana, Cuba, to uncover the deeply conflicting and contradictory values that comprise the dialectics of state–society relations. These spaces and the many actors who traverse them provide important insight into the complexity surrounding contemporary Cuba. Through detailed research into one form of self‐employment, paladares (small in‐home restaurants), this article examines how paladares have come to reflect the struggle for society and state to mediate the multitude of external and internal pressures amongst the current geopolitical climate. Using interviews conducted during several visits in 1999 and 2000, we demonstrate that paladares do not necessarily represent a capitalist transition. Rather, they embody the struggle to mediate contradictory spaces through the assertion of the self in the discourse of change.  相似文献   

城市滨水区旅游·游憩功能开发研究——以武汉市为例   总被引：1，自引：0，他引：1  

吴必虎  贾佳 《地理与地理信息科学》2002,18(2):99-102

该文指出城市滨水区开发是滨水城市规划研究中的热点问题 ,从城市游憩功能开发的角度 ,提出城市滨水区开发的基本原则。以武汉市为例 ,在重点论述汉口外滩、汉阳南岸嘴和武昌东湖三个滨水区游憩功能开发的基础上 ,提出以滨水区建设为中心的武汉市旅游发展战略  相似文献   

南昌市土地利用的空间冲突风险评估及分区优化研究     

陈竹安  冯祥瑞  洪志强  马彬彬  李亦佳 《世界地理研究》2021,30(3):533-545

以土地利用的导向功能为基础,将南昌市1995、2005和2015三期20种土地利用类型划分为生态生产空间、生产生态空间、生态空间和生活生产空间。利用空间复杂性指数、空间脆弱性指数和空间稳定性指数3个因子构建冲突模型,借鉴倒“U”型模型,将空间冲突分为4类：稳定可控、基本可控、基本失控和严重失控,在冲突级别的基础上利用优化产业结构、生态系统修复等措施,建立10个亚功能区,优化土地资源,缓解空间冲突,实现可持续发展。研究结果表明：①1995—2015年中南昌市三生空间格局以生产生态空间为主,其次是生态空间、生态生产空间以及生活生产空间,生活生产空间所占比例在上升,其余均在减少,呈现“一升三降”特点;②1995—2015年南昌市三生空间空间冲突愈演愈烈,严重失控单元持续增长,但2005—2015年的增长速度较1995—2005年稍慢,南昌市三生空间冲突失控态势严峻;③不同空间类型冲突存在较大差异,均以可控级别为主,其中失控级别占比由大到小：生活生产空间?生产生态空间?生态生产空间?生态空间;④利用10个亚功能区优化南昌市70%以上的区域,其中以城镇用地等为主的两个亚功能区,70%以上属于允许建设区,以滩地、湖泊、林地等为主亚功能区65%以上属于禁止建设区,符合土地利用总体规划。  相似文献   

Evaluating changes in ecological land and effect of protecting important ecological spaces in China     

GAO Jixi  LIU Xiaoman  WANG Chao  WANG Yong  FU Zhuo  HOU Peng  LYU Na 《地理学报(英文版)》2021,31(9):1245-1260

It is important to quantitatively analyze the effects of protection of important eco-logical spaces in China to ensure national ecological security.By considering changes in the ecological land,this study examines the effects of protecting three types of important natural ecological spaces in China from 1980 to 2018.Moreover,considering important ecological spaces and their surroundings yields differences in the effects of protection between internal and external spaces,where this can provide a scientific basis for the categorization and zoning of China's land.The results show the following:(1)In 2018,the ratio of ecological land to important natural ecological spaces accounted for 92.64％.This land had a good ecological background that reflects the developmental orientation of important ecological spaces.(2)From 1980 to 2018,the area of ecological land in important ecological spaces shrank but the rate of reduction was lower than the national average,which shows the positive effect of regulating construction in natural ecological spaces.The restorative effects of ecological projects to convert farmland into forests and grasslands have been prominent.The expanded ecological land is mainly distributed in areas where such projects have been implemented,and the reduced area is concentrated in grain-producing areas of the Northeast China Plain and agricultural oases of Xinjiang.In the future,the government should focus on strength-ening the management and control of these areas.(3)The area ratio of ecological land was the highest in national nature reserves.The rate of reduction in its area was the lowest and the trend of reduction was the smallest in national nature reserves,which reflects differences in the status of ecological protection among different spaces.(4)The ratio of ecological land to important ecological spaces was higher than that in the surrounding external space,and the rate of reduction in it was lower.Thus,the effects of internal and external protection had clear differences in terms of gradient.  相似文献   

'Situating' Simulation to Model Human Spatio-Temporal Interactions: An Example Using Crime Events   总被引：3，自引：0，他引：3  

Elizabeth R Groff 《Transactions in GIS》2007,11(4):507-530

Many social phenomena have a spatio‐temporal dimension and involve dynamic decisions made by individuals. In the past, researchers have often turned to geographic information systems (GIS) to model these interactions. Although GIS provide a powerful tool for examining the spatial aspects of these interactions, they are unable to model the dynamic, individual‐level interactions across time and space. In an attempt to address these issues, some researchers have begun to use simulation models. But these models rely on artificial landscapes that do not take into account the environment in which humans move and interact. This research presents the methodology for ‘situating’ simulation through the use of a new modeling tool, Agent Analyst, which integrates agent‐based modeling (ABM) and GIS. Three versions of a model of street robbery are presented to illustrate the importance of using ‘real’ data to inform agent activity spaces and movement. The successful implementation of this model demonstrates that: (1) agents can move along existing street networks; (2) land use patterns can be used to realistically distribute agent's homes and activities across a city; and (3) the incidence and pattern of street robberies is significantly different when ‘real’ data are used.  相似文献   

Seismic demands on secondary systems in base‐isolated nuclear power plants     

Yin‐Nan Huang  Andrew S. Whittaker  Michael C. Constantinou  Sanjeev Malushte 《地震工程与结构动力学》2007,36(12):1741-1761

Numerical models of a sample nuclear power plant (NPP) reactor building, both conventionally constructed and equipped with seismic protective systems, are analysed for both safe shutdown and beyond‐design‐basis earthquake shaking at two coastal sites in the United States. Seismic demands on secondary systems are established for the conventional and seismically isolated NPPs. The reductions in secondary‐system acceleration and deformation demands afforded by the isolation systems are identified. Performance spaces are introduced as an alternate method for evaluating demands on secondary systems. The results show that isolation systems greatly reduce both the median and dispersion of seismic demands on secondary systems in NPPs. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Frictional contact of laminated elastic half‐spaces allowing interface cavities. Part 2: Numerical results     

A. A. Kryshtafovych  S. J. Matysiak 《国际地质力学数值与分析法杂志》2001,25(11):1089-1099

The paper presents some numerical results of the problem on contact of stratified elastic half‐spaces possessing unevenness of their surface layers. The approach of the Jacobi polynomials is used to reduce the singular integral equation of the problem to a system of linear algebraic equations. On the basis of the system's solution the dependence of gaps' geometric characteristics on external load and friction is investigated for two types of initial boundary disturbances, namely a local symmetric recess and a periodic set of recesses at a flat boundary. Numerical results are presented in figures for a few elastic and geometric parameters of joint components. The analysis shows that elastic properties and geometric structure of a laminated half‐space have a significant influence on the shape of interface gaps and their location. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

基于GIS与遥感影像的银行ATM机网点选址方法研究   总被引：1，自引：0，他引：1  

张伟  刘纯波  周廷刚  黎雯 《测绘科学》2007,32(1):142-144

本文针对当前影响ATM机布点的因素,提出了基于矢量图和遥感影像的可视化平台。首先应用门槛分析模型将区域划分为潜力区域(含有ATM机但还有布放潜力的区域)和空白区域(不含ATM机的区域),从宏观上分析区域布放的可行性,并通过计算潜力区域和空白区域内的网点消费潜力,得出适合布放ATM机的区域,然后通过点位评估模型来分析这些区域内的网点,最后评估出可以布放ATM机的网点,并以北京某公司ATM机布点选址规划应用本文的选址方法进行了实践,取得了很好的效果。  相似文献