Spatial structure of central places in Jilin Central Urban Agglomeration,Jilin Province,China   总被引：1，自引：1，他引：0  

Shijun Wang  Yongchao Wang  Dan Wang 《中国地理科学(英文版)》2014,24(3):375-383

Using the radius of gyration from fractal theory, this paper describes the calculation of fractal dimensions for the four tiers of central places in the Jilin Central Urban Agglomeration(JCUA), Jilin Province, China and the structural characteristics of each tier: 1) the 1st tier central place, Changchun Proper(not including Shuangyang District), provides the most service functions and has the most stable primate position; 2) the 2nd tier central places, Jilin Proper, Siping Proper, Liaoyuan Proper and Songyuan Proper have unclear statuses and do not provide certain functions; 3) the 3rd tier central places comprise 23 county-level cities, counties and urban districts(including Shuangyang District of Changchun), exhibiting a dense spatial structure that agrees with theory; 4) the 4th tier contains the largest number of central places(248 designated towns), but they are loosely distributed. In this study, a spatial image of the JCUA was created, based on vectorized data of the urban settlement distribution, which was then modified and abstracted to create a hexagonal network covering the JCUA. Compared to the traditional central place model, the modified spatial image conforms to the K = 3 principle. In reality, however, the growth of some 3rd tier central places should be increased with the cities being upgraded to the 2nd tier so as to overcome that tier′s functional deficiency. The loose distribution in the 4th tier should also be changed. This apparent anomaly can be explained by the fact that the classic hexagon model used to describe the way market areas layout does not exist in the real world. However, this should not be viewed as an obstacle to using central place theory. If its assumptions are properly applied, it can still assist research into the spatial structure of regions.  相似文献   

Spatial and temporal variations of coastlines in northern China (2000-2012)     

XU Jinyong  ZHANG Zengxiang  ZHAO Xiaoli  WEN Qingke  ZUO Lijun  WANG Xiao  YI Ling 《地理学报》2014,24(1):18-32

This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques, and calculated the fractal dimension of the coastline by box-counting method, with a time span from 2000 to 2012. Moreover, we analyzed the characteristics of spatial-temporal changes in the coastline's length and fractal dimension, the relationship between the length change and fractal dimension change, and the driving forces of coastline changes in northern China. During the research period, the coastline of the study area increased by 637.95 km, at a rate of 53.16 km per year. On the regional level, the most significant change in coastline length was observed in Tianjin and Hebei. Temporally, the northern China coastline grew faster after 2008. The most dramatic growth was found between 2010 and 2011, with an increasing rate of 2.49% per year. The fractal dimension of the coastline in northern China was increasing during the research period, and the most dramatic increase occurred in Bohai Rim. There is a strong-positive linear relationship between the historical coastline length and fractal dimension (the correlation coefficient was 0.9962). Through statistical analysis of a large number of local coastline changes, it can be found that the increase (or decrease) of local coastline length will, in most cases, lead to the increase (or decrease) of the whole coastline fractal dimension. Civil-coastal engineering construction was the most important factor driving the coastline change in northern China. Port construction, fisheries facilities and salt factories were the top three construction activities. Compared to human activities, the influence of natural processes such as estuarine deposit and erosion were relatively small.  相似文献   

多重水力断裂的分形扩张   总被引：6，自引：2，他引：4  

於崇文 《地学前缘》2004,11(1):11-44

应用复杂性理论对于赣南脉钨矿床的著名“五层楼”式形态垂直分带进行研究 ,获得如下结果。 (1 )赣南脉钨矿床的“五层楼”式形态垂直分带是“多重水力断裂分形扩张”的结果。脉钨矿床的控矿多重断裂是一种以水力断裂为主导的热致与流体驱动断裂构造。脉钨矿床的自组织临界性是多重分形扩张之源 ,而中观破裂尖端周围流体静力学应力场梯度最大区则是分形扩张的驱动力。多重水力断裂的发生和发展是一种分形扩张过程 ,其演化服从串级“崩塌间断平衡”的时空分形生长动力学 ,与地震的Omori余震律相类似。 (2 )脉钨矿床“三环一帽”式的成矿地球化学分带是一种多组分成矿溶液的渗滤、溶解沉淀波结构 ,是成矿反应扩散系统中化学波的时空同步化传播而形成的目标斑图 ,是近平衡地质介质内 ,通过外界的“短暂局部激发”、继之以构造、岩浆和成矿脉动作用等“局部中断”而形成的径向对称、嵌套球状、远离平衡的局域化耗散结构 ,即脉动型自孤子。 (3)赣南脉钨矿床是近平衡区域地质背景中远离平衡的局域化耗散结构。赣南钨矿集区是复合自孤子的群集体。它们是在构造、岩浆多期次脉动条件下 ,来自①矿源层部分熔融的“区域提纯”、②岩浆期后成矿热液输运反应和③含钨地层、岩石淋滤交代的成矿物质 ,通过岩浆和热液孤  相似文献   

岩石颗粒破碎的尺寸效应     

徐永福  王益栋  奚悦  褚飞飞 《工程地质学报》2014,22(6):1023-1027

固体颗粒破碎强度的尺寸效应是一种普遍存在的现象,冰块、岩石颗粒、陶瓷和混凝土块等的破碎强度都表现出随颗粒直径增加而减小的现象,分形模型为解释固体颗粒破碎强度的尺寸效应提供了可行的方法。本文采用Steacy和Sammis分形模型模拟了岩石颗粒压碎特征,分析岩石颗粒破碎后的颗粒分布规律,给出颗粒破碎分维的确定方法,建立颗粒压碎强度与粒径的理论关系,颗粒破碎强度与颗粒粒径的关系用分维D表示为fdD-3。已有的颗粒破碎分布的数据表明,岩石颗粒破碎的分维大约为2.50～2.60,颗粒破碎强度符合用分维表示的尺寸效应。  相似文献   

Selection of Less Biased Threshold Angles for SAM Classification Using the Real Value–Area Fractal Technique     

Hadi Shahriari  Hojjatollah Ranjbar  Mehdi Honarmand  Emmanuel John M. Carranza 《Resource Geology》2014,64(4):301-315

The accuracy of classification of the Spectral Angle Mapping (SAM) is warranted by choosing the appropriate threshold angles, which are normally defined by the user. Trial‐and‐error and statistical methods are commonly applied to determine threshold angles. In this paper, we discuss a real value–area (RV–A) technique based on the established concentration–area (C–A) fractal model to determine less biased threshold angles for SAM classification of multispectral images. Short wave infrared (SWIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images were used over and around the Sar Cheshmeh porphyry Cu deposit and Seridune porphyry Cu prospect. Reference spectra from the known hydrothermal alteration zones in each study area were chosen for producing respective rule images. Segmentation of each rule image resulted in a RV–A curve. Hydrothermal alteration mapping based on threshold values of each RV–A curve showed that the first break in each curve is practical for selection of optimum threshold angles. The hydrothermal alteration maps of the study areas were evaluated by field and laboratory studies including X–ray diffraction analysis, spectral analysis, and thin section study of rock samples. The accuracy of the SAM classification was evaluated by using an error matrix. Overall accuracies of 80.62% and 75.45% were acquired in the Sar Cheshmeh and Seridune areas, respectively. We also used different threshold angles obtained by some statistical techniques to evaluate the efficiency of the proposed RV–A technique. Threshold angles provided by statistical techniques could not enhance the hydrothermal alteration zones around the known deposits, as good as threshold angles obtained by the RV–A technique. Since no arbitrary parameter is defined by the user in the application of the RV‐A technique, its application prevents introduction of human bias to the selection of optimum threshold angle for SAM classification.  相似文献   

基于Budyko假设和分形理论的水沙变化归因识别——以北洛河流域为例   总被引：1，自引：0，他引：1  

薛帆  张晓萍  张橹  刘宝元  杨勤科  易海杰  何亮  邹亚东  贺洁  许小明  吕渡 《地理学报》2022,77(1):79-92

全球气候变化及人类活动深刻影响了区域水文过程,进行水沙变化归因识别对流域生态保护和高质量发展尤为重要。基于Budyko假设和分形理论,采用弹性系数法,对北洛河流域上（丘陵沟壑区）、中（土石山林—高塬沟壑区）、下游（渭北旱塬农区）3种不同地貌和植被类型区1959—2019年的水、沙通量变化进行归因分析。结果表明,北洛河上、中、下游径流量均显著减少,由20世纪60年代的35 mm、32 mm、34 mm,减少到21世纪10年代的19 mm、24 mm、6 mm,60 a减少率分别为0.3 mm a^-1、0.2 mm a^-1、0.4 mm a^-1。上游输沙量极显著减少,中游降低趋势不显著,下游显著减少,由20世纪60年代的99×10⁶ t、8×10⁶ t、3×10⁶ t,减少到21世纪10年代的10×10⁶ t、3×10⁶ t、0.3×10⁶ t,60 a减少率分别为1.5×10⁶ t a^-1、0.04×10⁶ t a^-1、0.1×10⁶ t a^-1。20世纪70年代以来,上游径流变化逐渐受人类活动影响,且影响程度逐渐增强,21世纪10年代人类活动贡献率达66.3%;气候变化是中游径流变化的主控因子,21世纪10年代降雨和潜在蒸散发的贡献率分别为77.0%和20.2%;下游径流减少主要为人类活动影响,21世纪10年代其贡献率为64.3%。对比20世纪60年代流域输沙量变化始终受人类活动主导,21世纪10年代人类活动对上、中、下游输沙量减少的贡献率分别为80.7%、59.2%和92.7%。上游人类活动对输沙量减少的贡献中,退耕还林等沟坡措施和沟道工程措施分别为39.0%、42.7%,中、下游人类活动贡献的估算结果反映出高植被覆盖区和农区汲水灌溉对区域水、沙的影响特征。  相似文献   

全球超大城市空间扩张及分形特征研究     

侯亚丽  匡文慧  窦银银 《地理学报》2022,77(11):2687-2702

超大城市是全球经济、文化以及高科技产业发展的承载体和重要纽带,其形态结构特征和人口聚集效应是城市化影响的典型表现,然而当前对于全球超大城市形态特征及扩张模式的研究相对不足。基于2000—2020年全球城市土地利用/覆盖变化数据（GULUC-30）,利用城市扩张强度差异指数分析了超大城市用地的时空变化规律;而后运用面积—半径标度分析模型研究了超大城市的分形特征及扩张模式,最后基于城市用地面积和城市人口之间的线性关系评价城市用地效率。结果发现：① 2000—2020年东南亚和东亚的中国超大城市用地扩张最剧烈,城市用地面积分别扩张了3148.32 km²和5996.26 km²,城市扩张强度差异指数平均值大于3;② 2000—2020年超大城市的形态特征和扩张模式向着更加集约和紧凑的方向发展,径向维数平均值由1.54增加至1.56,分维差呈逐年减少趋势,城市内部结构一体化特征显著;③ 北美和欧洲的超大城市用地效率低,2020年城市用地面积与城市人口比值系数范围为0.89~4.11;南亚和非洲城市用地效率高,比值范围为0.23~0.87。超大城市空间扩张格局和形态变化的认识对于城市用地的集约利用和可持续发展具有重要参考价值。严格控制超大城市扩张规模,促进城市用地的均衡发展是建设韧性城市和实现城市地区可持续发展的必要条件。  相似文献   

企业三维仿真Web GIS系统的设计     

张留民  田耀勇 《地理空间信息》2004,2(1):18-19,50

随着Internet的发展和人们对各类信息需求的增加及企业面向社会提高知名度的需要,使得企业三维仿真WebGIS系统有着较为广泛的应用前景。文章探讨了利用VisualBasic等开发企业三维仿真webGIS系统的过程和方法。  相似文献   

利用背景噪声的分形方法监控台站观测系统运行状态     

丁莉莎  马洁美  齐军伟  谢剑波  廖一帆  卢子晋  叶世山  劳谦  吕仲杭 《大地测量与地球动力学》2021,41(4):436-440

使用全国23个国家测震台站和17个实验台站地震计记录的背景噪声数据,研究特定尺度(限定频带内)的背景噪声特性,分析利用分形方法监测台站观测系统运行状态的可行性。结果表明,分形方法具有较强的时域性,定量化程度高、抗干扰能力强,基本不受观测系统参数约束,可用于台站观测系统运行状态检测,减少正常记录瞬间中断和引入人为干扰的情况。  相似文献   

中国铜矿床品位吨位模型   总被引：9，自引：0，他引：9  

肖克炎李景朝  陈郑辉何凯涛 严光生 《地质论评》2004,50(1):50-56

笔者等以1999年底的全国铜矿储量数据为基础,研究了中国铜矿不同成矿类型的品位吨位分布特征,在此基础上研究了中国斑岩型铜矿的品位、吨位分形特征。在研究铜矿的品位吨位特征的基础上,在矿产资源评价系统(MRAS)上集成MRAK3计算方式,进行全国的铜矿资源量预测评价。  相似文献