“一带一路”沿线地区城市扩张和形态变化分析   总被引：1，自引：0，他引：1  

海凯  王思远  马元旭  杨瑞霞  涂平  梁娟珠  刘卫华  吴林霖 《地理学报》2020,75(10):2092-2108

尽管越来越多的人认识到“一带一路”沿线各国的城市化进程对其经济、政治和环境系统所起的重要作用,但对监测区域范围内城市扩张和形态变化的比较研究却极为有限。基于欧空局气候变化倡议项目最新发布的1992—2015年300 m分辨率的全球土地覆盖数据集、1992—2012年DMSP/OLS夜间灯光数据和2000—2015年LandScan人口数据,本文首先分析了1992—2015年“一带一路”陆域城市用地增长的空间格局和十大分区城市用地面积的动态。其次,通过分析3个时间点（1992年、2003年和2015年）上同心环内城市用地密度的时空变化,量化了“一带一路”沿线80个城市的扩张和形态变化。最后采用3种统计模型（线性、幂律和指数函数模型）来分析城市用地面积、加权灯光面积和城市人口之间的长期关系。结果显示,“一带一路”陆域城市用地面积占土地总面积的比例从1992年的0.24%上升至2015年的0.56%,并且非洲和亚洲的发展中国家是“一带一路”监测区域城市化的主要贡献者。同心环内城市用地密度从城市中心到城市边缘呈递减趋势,且城市间的空间分布完全不同。中国、欧洲、非洲、西亚、东南亚和印度6个分区人口数超过100万的城市间比较显示,除了中国城市形态变得分散,其他分区城市形态总体变得紧凑。分析结果也显示,夜间灯光信号所反映的城市经济活力和城市人口分布趋势在不同程度上影响城市空间扩张和形态变化。  相似文献   

Bearing capacity of strip footings on spatially random soils using sparse polynomial chaos expansion     

Tamara Al‐Bittar  Abdul‐Hamid Soubra 《国际地质力学数值与分析法杂志》2013,37(13):2039-2060

A probabilistic model is presented to compute the probability density function (PDF) of the ultimate bearing capacity of a strip footing resting on a spatially varying soil. The soil cohesion and friction angle were considered as two anisotropic cross‐correlated non‐Gaussian random fields. The deterministic model was based on numerical simulations. An efficient uncertainty propagation methodology that makes use of a non‐intrusive approach to build up a sparse polynomial chaos expansion for the system response was employed. The probabilistic numerical results were presented in the case of a weightless soil. Sobol indices have shown that the variability of the ultimate bearing capacity is mainly due to the soil cohesion. An increase in the coefficient of variation of a soil parameter (c or φ) increases its Sobol index, this increase being more significant for the friction angle. The negative correlation between the soil shear strength parameters decreases the response variability. The variability of the ultimate bearing capacity increases with the increase in the coefficients of variation of the random fields, the increase being more significant for the cohesion parameter. The decrease in the autocorrelation distances may lead to a smaller variability of the ultimate bearing capacity. Finally, the probabilistic mean value of the ultimate bearing capacity presents a minimum. This minimum is obtained in the isotropic case when the autocorrelation distance is nearly equal to the footing breadth. However, for the anisotropic case, this minimum is obtained at a given value of the ratio between the horizontal and vertical autocorrelation distances. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Spatial characteristics and driving forces of the morphological evolution of East Lake,Wuhan     

陈昆仑  刘小琼  陈溪  郭宇琪  董寅 《地理学报(英文版)》2020,30(4):583-600

The shapes of the urban lakes in Wuhan city have been strongly influenced by the rapid industrialization and urbanization experienced in recent decades.Based on topographic maps and remote sensing images,the temporal and spatial changes of East Lake,Wuhan city,over the past two decades were analyzed.The landscape shape index(LSI)and centroid method were applied to analyze the evolution of lake morphology and its causes.Several key results were obtained.(1)The surface area of East Lake decreased sharply by 2.13 km2 from 1995 to 2005,and slightly by 1.00 km2 from 2005 to 2015.The shoreline length of East Lake displayed a continuous trend of decline during the study period:The length reduced by 21.89 km from 1995 to 2005,and by 0.67 km from 2005 to 2015.The LSI values,7.04(1995),6.46(2005),and 6.28(2015),displayed an accelerated downward trend,indicating a reduction of complexity in East Lake and the intensification of manual interventions in the water body.(2)The changes to East Lake displayed a clear temporal and spatial heterogeneity.The centroid of East Lake moved northeast from 1995 to 2005 and southeast from 2005 to 2015.(3)The reduction in the area of East Lake was mainly affected by human activities.A lake area of about 4.8 km2 was converted to other land uses during 1995-2005,most of which was unused land,whereas from 2005 to 2015,0.43 km2 of the lake area was converted into built-up land,and 0.25 km2 was converted into other land uses.The reduction in area was caused by infrastructure construction by the government,the development of the real estate industry,illegal construction by villagers,and the development of scenic spots for tourism.The driving forces of this reduction included Wuhan's growing population,and the rapid development of the economy and urbanization between 1995 and 2015,which has resulted in a large demand for land.Finally,a formation mechanism model was constructed by analyzing the causes of East Lake's morphological evolution.  相似文献   

Efficient sparse polynomial chaos expansion methodology for the probabilistic analysis of computationally‐expensive deterministic models     

T. Al‐Bittar  A.‐H. Soubra 《国际地质力学数值与分析法杂志》2014,38(12):1211-1230

The sparse polynomial chaos expansion (SPCE) methodology is an efficient approach that deals with uncertainties propagation in case of high‐dimensional problems (i.e., when a large number of random variables is involved). This methodology significantly reduces the computational cost with respect to the classical full PCE methodology. Notice however that when dealing with computationally‐expensive deterministic models, the time cost remains important even with the use of the SPCE. In this paper, an efficient combined use of the SPCE methodology and the Global Sensitivity Analysis is proposed to solve such problem. The proposed methodology is firstly validated using a relatively non‐expensive deterministic model that involves the computation of the PDF of the ultimate bearing capacity of a strip footing resting on a weightless spatially varying soil where the soil cohesion and angle of internal friction are modeled by two anisotropic non‐Gaussian cross‐correlated random fields. This methodology is then applied to an expensive model that considers the case of a ponderable soil. A brief parametric study is presented in this case to show the efficiency of the proposed methodology. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

板876地下储气库水砂体评价与扩容利用     

谢俊  潘芝平  王亚洲  梁会珍  王皆明  王金凯 《中国海洋大学学报(自然科学版)》2020,(2):100-106

由常规枯竭型气藏改建的地下储气库仍然以气藏砂体(气砂体)为研究目标,与气藏砂体相邻的含水层(水砂体)亦能作为地下储气库的扩容空间,但这部分砂体很少被关注。板876地下储气库在储层精细描述基础上,结合气藏和气库的注采动、静态分析结果,评价了水砂体的分布范围和发育规模,利用精细地质模型计算了水砂体的总孔隙体积、未动用的及可动用的孔隙体积,应用板876地下储气库数值模拟技术对水砂体的扩容空间进行了验证,结果表明水砂体储集空间对地下储气库的扩容和运行效率具有现实意义。  相似文献   

Crustal Structure of the Chuan-Dian Block Revealed by Deep Seismic Sounding and its Implications for the Outward Expansion of the East Tibetan Plateau     

XIONG Xiaosong  WANG Guan  LI Qiusheng  LU Zhanwu  GAO Rui  FENG Shaoying  WU Guowei 《《地质学报》英文版》2022,96(6):1932-1944

The Chuan-Dian Block (CDB) is located in the southeastern margin of the Tibetan Plateau, with a complex geological structure and active regional faults. The present tectonic condition with strong crustal deformation is closely related to the ongoing collision of the India and Eurasia plates since 65 Ma. The study of the crustal structure of this area is key to revealing the evolution and deep geodynamics of the lateral collision zone of the Tibetan Plateau. Deep seismic sounding is the most efficient method with which to unravel the velocity structure of the whole crust. Since the 1980s, 19 deep seismic sounding profiles have been captured within the CDB area. In this study, we systematically integrate the research results of the 19 profiles in this area, then image the 3D crustal velocity, by sampling with a 5 km spacing and 2D/3D Kriging interpolation. The results show the following. (1) The Moho depth in the study area deepens from 30 km in the south to 66 km in the north, whereas there is no apparent variation from west to east. The Pn wave velocity is higher in stable tectonic units, such as 7.95 km/s in the Lanping-Simao block and 7.94 km/s in the western margin of the Yangtze block, than in active or mobile tectonic units, such as 7.81 km/s in the Baoshan block, 7.72 km/s in the Tengchong block and 7.82 km/s in the Zhongdian block. (2) The crustal nature of the Tengchong block, the northern Lanping-Simao block and the Zhongdian block reflects a type of orogenic belt, having relatively strong tectonic activities, whereas the crustal nature of the central Lanping-Simao block and the western margin of the Yangtze block represents a type of platform. The different features of the upper-middle crust velocity, Moho depth and Pn wave velocity to both sides of the Red River fault zone and the Xianshuihe fault zone, reflect that they are clearly ultra-crustal. (3) Based on the distribution of the low velocity zones in the crust, the crustal material of the Tibetan Plateau is flowing in a NW–SE direction to the north of 26°N and to the west of 101°E, then diverting to flowing eastwards to the east of 101°E.  相似文献   

一种改进的自适应Wallis滤波算法     

王博  张永军  陈奇 《测绘科学》2015,40(5):95-98

针对影像增强过程中的边缘扩张、灰度过饱和及"块效应"等问题,文章提出了一种改进的自适应Wallis滤波算法:结合影像特征提取的实践应用,在影像局部范围内进行灰度均值和方差的统计,能够较好地实现自适应的判断二值分割阈值,利用迭代的方法,可以有效保证影像在增强处理下的保真度。最后以几组典型影像为例,证明该方法相对于传统方法较好地保证了影像增强后的影像质量,处理效率较高、应用面广。  相似文献   

2000年以来南京城市三维空间扩展特征   总被引：4，自引：0，他引：4  

乔伟峰  刘彦随  王亚华  陆昱颖 《地理研究》2015,34(4)

以南京市建成区为例,基于四期城市三维模型,运用城市天际线、城市体积及分维数、城市三维重心、高层建筑的数量与占地面积的关系等方法从多角度分析2000年以来南京城市三维空间增长特征.研究表明:南京城市天际线起伏明显,西—东方向的形态由2000年的“一高两低三峰”演化为2012年的“中部、西部双峰耸立,东部较为平缓”的格局;城市体积处于持续增长的态势,其中2000-2004年是体积增长最快的时期,增长率为51％,体积分维数在不断变大,表明城市扩展在不断从二维向三维形态发展演变;三维重心平面投影的移动方向从东南转向西,反映了三维城市的发展方向主要为城市南部和西部地区;2000年城市立体形态发展为弱金字塔阶段,至2012年,在高楼密集的中心城区已经发展至均衡金字塔阶段甚至在向穹隆顶阶段过渡.  相似文献   

京津冀地区城镇空间扩张模拟与分析   总被引：7，自引：2，他引：5  

刘翠玲  龙瀛 《地理科学进展》2015,34(2)

准确把握城镇扩张过程中空间形态的变化规律对城镇规划水平的提高具有重要的现实意义。当前,京津冀的协同发展已上升为国家战略,为了对京津冀远景的城镇增长进行预测,本文将北京城市空间发展分析模型(BUDEM)扩展到京津冀(JJJ)区域,构建了京津冀城镇空间发展分析模型(BUDEM-JJJ)。该模型以城市增长理论和约束性元胞自动机(Constrained Cellular Automata,Constrained CA)模型为基础,以京津冀区域为研究对象,以Logistic回归和单一参数循环方法(Monoloop)为模型参数识别方法,利用2000-2005年和2005-2010年两个历史阶段的城镇建设用地数据对模型进行了参数识别,并进行了模型验证。在此基础上,对京津冀区域2049年的城镇形态进行了多种情景模拟,分析了不同发展情景(Scenario)下京津冀地区城镇空间发展格局的变化,可为当前京津冀城镇发展方向的调整和下一轮的城镇规划提供参考。  相似文献   

基于工业用地扩展的长沙城市空间演变与优化     

刘路云  郑伯红 《地域研究与开发》2015,(4)

以工业园区形式为主的工业用地扩展对城市空间演变产生着深刻影响。利用长沙市1949—2013年的城市用地资料,通过计算城市与工业的用地扩展强度指数、等距扩散缓冲强度峰值、重心轨迹、形状紧凑度与空间效率等城市空间衡量指标,分析工业用地扩展的时间特征,揭示工业用地扩展引导城市空间发展由内向填充走向外向扩展、空间模式由单中心走向多中心、空间结构由圈层走向轴向、空间联系由松散走向紧凑等规律,并从总体规划层面提出相应的城市空间优化策略,引导工业用地的合理规划。  相似文献