城市空间结构的复杂性研究进展   总被引：7，自引：3，他引：4  

房艳刚  刘鸽  刘继生 《地理科学》2005,25(6):754-761

城市空间结构一直是城市地理学和城市规划研究的核心之一,而复杂性是正在被逐步认识的现象。目前城市空间结构的复杂性研究是城市研究的前沿领域,对城市规划也具有重要的指导价值。本文首先论述了城市系统、城市空间结构与复杂性研究的关系,然后从城市子系统空间结构复杂性、城市系统空间结构复杂性和城市空间结构演化复杂性三方面综述了国内外的研究进展。最后讨论了目前城市空间结构的复杂性研究存在的问题,并就今后的研究重点做了展望。  相似文献   

地表蒸发条件下的膨胀土初始开裂分析   总被引：7，自引：1，他引：6  

郑少河  金剑亮  姚海林  葛修润 《岩土力学》2006,27(12):2229-2233

针对地表蒸发条件下的膨胀土开裂问题,从定性和定量两个方面进行了分析,提出了膨胀土初始开裂的基质吸力临界判据,经比较与现场实测结果基本一致。采用线弹性力学方法,研究了地表蒸发条件下的膨胀土初始开裂深度,对其与土体抗拉强度、泊松比及密度等特性参数的关系进行了详细的论述。  相似文献   

北京某地地热井施工工艺研究     

马新  刘戈  周立民 《吉林地质》2005,24(1):72-75

本文介绍了北京地区蓟县系雾迷山碳酸盐岩热储层的地热地质条件及地热井施工工艺。并对该地区热水开发前景做出了评价。  相似文献   

分布式时变增益流域水循环模拟   总被引：55，自引：0，他引：55  

夏军  王纲胜  吕爱锋  谈戈 《地理学报》2003,58(5):789-796

针对分布式水文模拟的问题,结合河西走廊黑河流域实际资料条件,提出将水文循环空间数字化信息与水文系统理论相结合的分布式时变增益水循环模型 (DTVGM)。DTVGM将单元时变增益水文非线性模型(TVGM)拓广到由DEM划分的流域单元网格上建立非线性地表水产流模型,基于水量平衡方程和蓄泄方程建立土壤水产流模型,并应用运动波方法建立分级网格汇流模型。最后,以黑河干流山区流域为例应用DTVGM开展了实例研究,设计开发了模型系统。研究区域被划分为38 277个网格单元 (网格大小为500 m×500 m),在此基础上将流域划分为456级带状汇流区域。考虑到黑河干流山区的寒区特点,模型耦合了融雪径流模型。模拟结果表明,DTVGM既有分布式水文概念性模拟的特征,同时具有水文系统分析适应能力强的优点,能够在水文资料信息不完全或者有不确定性干扰条件获得比较好的分布式水文模拟效率,在黑河干流山区的应用能够较好地满足水资源管理的要求。  相似文献   

Yukon River Basin long‐term (1977–2006) hydrologic and climatic analysis     

Shaoqing Ge  Daqing Yang  Douglas L. Kane 《水文研究》2013,27(17):2475-2484

In this study, long‐term discharge data and climate records, such as temperature and precipitation during 1977–2006, have been used to define basin climatic and hydrologic regimes and changes. Discharge analyses at four key gauging stations (Eagle, Stevens Village, Nenana, and Pilot Station) in the Yukon River Basin show that the runoff in the cold season (November to April) is low with small variations, whereas it is high (28 500–177 000 ft³/s; 810–5000 m³/s) with high fluctuations in the warm season (May to October). The Stevens Village Station is in the upper basin and has similar changes with the flow near basin outlet. Flow increases in May (61 074 ft³/s; 1729 m³/s) and September (23 325 ft³/s; 660 m³/s); and decreases in July (35 174 ft³/s; 996 m³/s) and August (6809 ft³/s; 193 m³/s). Discharge in May at the Pilot Station (near the basin outlet) shows a positive trend (177 000 ft³/s; 5010 m³/s). Daily flow analyses show high fluctuation during the warm season and very low flow during the cold season; the 10‐year average analyses of daily flow at Pilot Station show a small increase in the peak and its timing shifted to a little earlier date. The annual flow, average of 227 900 ft³/s (6450 m³/s) with high inter‐annual fluctuations, has increased by 18 200 ft³/s (or 8%; 520 m³/s) during 1977–2006. From 1977 to 2006, basin air temperature in June has increased by 3.9 °F (2.2 °C) and decreased by 10.5 °F (5.8 °C) in January. A strong and positive correlation exists between air temperature in April and discharge in May, whereas a strong and negative correlation relates August temperature and September discharge. Negative trend during 1977–2006 is observed for precipitation in June (0.6 in.; 15 mm) with a confidence over 93%. Precipitation in August and September has strong and positive correlations with discharge in September and October at basin outlet; the precipitation in other months has weak correlation with the discharge. The mean annual precipitation during 1977–2006 increased by 1.1 in. (or 8%; 28 mm), which contributes to the annual flow increase during the study period. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

我对白云鄂博铁铌稀土矿床的研究过程及往见新识   总被引：1，自引：1，他引：0  

白鸽 《地质学报》2012,86(5):679-682

80年前,丁道衡先生奉命去西北进行古生物考查研究工作,取道乌蒙草原,突然看到荒漠大地上有一座高耸美丽的神山,作了旅游参观之举.走到山脚下,就看到很多黑黑的滚石,到山上,更见有大块致密的磁铁矿石和红绿条带相间的赤铁矿石,就这样偶然发现了白云鄂博大型铁矿床.  相似文献   

基于等价分析法评估溢油事故的自然资源损害   总被引：2，自引：0，他引：2  

张蓬  冯俊乔  葛林科  王震  姚子伟  杜廷芹 《地球科学进展》2012,27(6):633-643

尽管国际公约和许多国家立法已将海上溢油事故导致的自然资源损失列入索赔范围,然而,在量化和货币化损害以及确定索赔和修复范围等方面尚未建立被广泛接受的计算方法。生境等价分析(Habitat Equivalency Analysis,HEA)和资源等价分析(Resource Equivalency Analysis,REA)是美国和欧盟应用于评估自然资源损害的理论方法,二者的关键假设是受损的生态服务损失和修复计划的服务收益应当相等。HEA结果依赖于生态服务价值标尺选择、服务价值水平、恢复曲线形状、修复计划时长以及贴现率等;REA结果受死亡生物数量和年龄组成的影响。HEA和REA的非货币形式结果补偿的并非生态环境,而是人类社会福祉。目前,一些货币化损失的方法已被提出,然而传统经济学家和生态经济学家之间存在争议。美国部分法庭承认HEA和REA方法,其结果为法庭索赔提供数据支持。如果将生态学和经济学原理结合考虑,将能够促进等价分析法的深入发展,推动索赔工作更加有理有据。  相似文献   

Quartz sandstone peak forest landforms of Zhangjiajie Geopark, northwest Hunan Province, China: pattern, constraints and comparison   总被引：1，自引：1，他引：0  

Guifang Yang  Mingzhong Tian  Xujiao Zhang  Zhenghong Chen  Robert A. L. Wray  Zhiliang Ge  Yamin Ping  Zhiyun Ni  Zhen Yang 《Environmental Earth Sciences》2012,65(6):1877-1894

The Zhangjiajie Sandstone Peak Forest Geopark in northwest Hunan Province, China, is a comprehensive geopark containing many spectacular quartz sandstone landforms, limestone karst landscapes and various other important geoheritage resources. It is listed as a UNESCO World Geopark and is also part of the World Heritage Wulingyuan Scenic and Historic Interest Area for its important landscape features. Many of the sandstone landforms, particularly the vast number of thin pillars or spires, are very unusual and serve as the core landscapes of the geopark. But Zhangjiajie displays a diverse range of landform types, exhibiting spectacular patterns and regular distributions. In this paper, the geomorphic traits, distribution pattern and constraints of the sandstone landforms of the Zhangjiajie Geopark are examined. Our study indicates that in the outcropping areas, the sandstones display four distinctive levels from 300 to 1,000 m above sea level, and these extend clearly from the highest sandstone plateau platform to the center of the valleys. The high sandstone platforms developed close to a flat high-level erosional surface, and subsequent erosion into this plateau has resulted in successively lower levels of landforms that transition gradually from peak walls, peak clusters, peak forests and peak pillars to remnant peaks in the lower valley bottoms. The form and distribution of the Zhangjiajie sandstone landforms are primarily dominated by the geological setting, particularly the presence of brittle structures (fractures and joint sets) trending NNW, ENE and NE. Triggered by the episodic tectonic movements, major streams and escarpments frequently occur along these structural directions, while some of the peak walls, peak clusters and peak forests have their longer elongated axes corresponding to NE or NNW directions, with an increased density of peak forms at the intersection of these fractures and joints. The geometry of the diverse sandstone landforms is also influenced to a certain degree by the climatic, water system distribution, lithologic properties, biological process, meteorological features and denudation processes. The suite of quartz sandstone landforms in Zhangjiajie can be compared with other sandstone landscapes regionally, and our interpretation of the sandstone peak forest formation processes offers a significant contribution to the study of topographic features and the geomorphic evolution of sandstone landscapes.  相似文献   

Susceptibility and risk assessment of earthquake-induced landslides based on Landslide Response Units in the Subao River basin,China     

Jianqiang Zhang  Peng Cui  Yonggang Ge  Lingzhi Xiang 《Environmental Earth Sciences》2012,65(4):1037-1047

Generally, pixels are the basic unit for assessment of landslide susceptibility. However, even if the results facilitate the comparison, a pixel-based analysis does not clearly illustrate the distribution relationships. To eliminate this deficiency, the concept of the Landslide Response Unit (LRU) is proposed in this study, for which adjacent pixels that have similar properties are combined as a basic unit for susceptibility assessment. The Subao River basin, seriously impacted by the Wenchuan Earthquake, was selected as the study area, and three factors including slope gradient, slope aspect, and slope shape, which have a significant impact on landslides, were chosen to divide the basin into 25,984 LRUs. Then topographic, geologic, and distance factors were applied for the landslide susceptibility evaluation. The logistic regression method was used to establish the susceptibility assessing model by analyzing 2,000 susceptible LRUs and 2,000 un-susceptible LRUs. The model accuracy was defined in terms of the ROC curve value and the κ value, 0.531 and 0.84, respectively. The susceptibility of landslides was divided into low, moderate, high, and very high in Subao River basin, and 73% of historical landslides and all four new landslides are in the highly susceptible zone and very highly susceptible zones. Finally, the LRUs with houses, farmlands, and roads prone to sliding and burial hazard were assessed separately. On the basis of considering the potential movement directions of the LRUs, the result found that 1,001 and 835 LRUs probably would be destroyed by slope sliding and landslide burial, respectively.  相似文献   

LAMOST CCD相机总控的设计与实现     

邓小超  王坚  董健  刘光曹  袁海龙  金革 《天文研究与技术》2011,(3)

大天区面积多目标光纤光谱望远镜(LAMOST)使用了16台低色散光谱仪、32台科学级CCD相机对目标进行光谱拍摄。CCD集总控制器MASTER是其32台CCD相机的中枢,它控制CCD按观测需要进行曝光、管理CCD状态和诊断相机故障。针对LAMOST相机系统的结构和UCAM控制器的特点,设计了MASTER系统;介绍了与OCS和UCAM接口的方式,并分析了对命令和状态的管理。  相似文献