共查询到19条相似文献，搜索用时 500 毫秒
1.
探讨了小尺度空间范围内地震能量关于时间和空间分布的统计自仿射分形特征，从中得到了如下认识：地震能量关于时间的分布是自仿射分形的，代表分布结构特征的Ｈ值小于１／２，因而时间关联函数Ｃ（ｔ）＜０，表明地震能量关于时间分布的变化过程具有负相关效应；地震能量在空间上分布也具有自仿射分形特征，有限震例表明，Ｈ值小于但接近于１／２，表明地震能量的空间分布具有更复杂的变化过程 相似文献
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中国省域煤矿事故时空分异特征及影响因素研究 总被引：1，自引：0，他引：1
煤矿事故给国家和人民带来巨大的生命财产损失,科学把握煤矿事故发生的宏观规律及区域煤矿安全的影响因素有助于促进煤矿安全生产。本文尝试采用GIS空间分析方法开展区域煤矿事故的研究,基于空间自相关性、时空演化规律方法研究了2006-2015年中国省域煤矿事故的时空分异特点,并分析了省域煤矿安全的影响因素及相对风险度。主要结论：①中国各省区之间煤矿事故存在明显的空间自相关性,但随着各省区煤矿安全生产形势改善情况的不同,其自相关性在不断下降;②以空间重心转移曲线分析中国煤矿事故发生的时空演化规律,10年间煤矿事故空间重心向东北方向转移。③重特大事故频发的省区由于监管措施的有力执行往往具有较低的煤矿百万吨死亡率;平均煤矿生产能力低的省区具有较高的煤矿百万吨死亡率;④建立基于解释变量的贝叶斯空间模型,以煤炭百万吨死亡率为指标评估中国各省区煤矿事故相对风险度,中国煤矿安全生产相对危险度存在明显的空间分布规律且各省区差异较大,相对危险度较高的省区主要集中在南方地区,包括湖北、福建等,危险度较低的省区主要集中在中东部地区,包括山西、内蒙古等。 相似文献
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利用海上交通事故空间分布特征进行安全分析是海上交通安全管理的重要组成部分。本文使用厦门港2008—2020年的海上交通事故数据,经过事故数据空间分布特征提取、分析及预测等流程,最终得到厦门水域海上交通事故潜在危险区域。本文首先使用原始事故数据在GIS软件中进行空间定位,形成事故点的可视化空间分布图,然后使用核密度分析法鉴别海上交通事故多发区域,再利用空间自相关分析法,得到该区域事故空间的分布特征和具体的聚集点,最后使用该分布特征、对目标水域数据进行标准化网格切分,并利用机器学习算法对潜在事故风险区域进行预测。本文在核密度分析结果中发现：就事故频度而言,厦门湾和西海域交通事故频度较高。在空间自相关分析的结果中表明：就空间分布特征而言,厦门港的空间分布出现聚集特征且为空间正相关模式,且就事故具体的空间聚集点而言,厦门湾和西海域仍是事故高发的中心区域。而最后的厦门湾及周边水域风险预测模型显示：潜在事故风险区域多位于沿海和河口交汇区域。本文研究结果表明在基于地理空间数据分布特征提取和网格化分析的基础上,结合机器学习方法（随机森林）,对于海上交通事故的预测具有良好的效果。 相似文献
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滇西动态重力网的分形特征及空间分辨力 总被引：1，自引：1，他引：0
贾民育 《大地测量与地球动力学》1996,(4)
介绍了用分形学描述地球物理观测网非均匀分布和联合应用分形特征与Ｓｈａｎｎｏｎ定理确定最佳网格距的方法。研究了滇西动态重力网的分形特征，它的分形维Ｄｆ＝１．２７，最佳网格距ｒ０＝２８ｋｍ。讨论了１９８６年至１９９４年间网区发生的８次Ｍｓ＞５．０级地震前重力场变化的可信性，指出这些变化的波长均大于１００ｋｍ，至少２倍于网的最小空间分辨力，因而是可信的 相似文献
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国家安全生产监督管理局通报的2004年全国煤炭企业发生各类伤亡事故3853起,死亡6009人。其中比较惨烈的有2起：2004年10月20日,河南大平煤矿瓦斯爆炸事故造成了127人遇难：11月28日,陕西省铜川矿务局陈家山煤矿发生特大瓦斯爆炸事故,166人遇难。 相似文献
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广东省公路交通网络分形空间特征研究 总被引：2，自引：0，他引：2
基于分形理论,以GIS技术为支撑,利用回转半径法测算了广东省全域及其所辖21个地级市公路交通网络半径维数DL、分枝维数Db和对应相关系数R2。依据广东省公路交通网络的特点,将其辖区分为四个子区域:珠三角、东部沿海、西部沿海和粤北地区,分析其半径维数和分枝维数的空间分布特征。研究表明,珠三角地区为广东省公路交通网络密度最大、结构最复杂、功能最完善、连通性最优的区域;以珠三角为中心,广东省公路交通网络分形半径维数和分枝维数随距离增大而衰减,沿海衰减程度微弱,粤北衰减程度较大。结果显示,半径维数和分枝维数结合能够更为合理系统地分析交通网络分形特征的时空差异特性。 相似文献
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岩石作为一种典型的多孔介质,其内部孔隙结构、形态特征极为复杂,运用常规线性系统内参数描述较为困难,因而采用非线性系统内分形维数这一参数来定量表征孔隙结构的非线性分布特征较为合适。岩石内部孔隙结构分布具有统计意义上的分形特征,因此分形维数的确定对于定量表征孔隙结构分布规律,以及揭示岩石各种力学行为与物理力学指标有着重要意义。将图像处理与阈值分割、分形理论和数理统计相结合,针对CT扫描切片图像,三维重建孔隙结构空间分布模型,计算Hausdorff测度空间下孔隙结构分布盒维数与集束维数。同时,针对孔隙结构空间分布复杂程度的定量表征,提出体素盒维数与圆柱体空间集束维数假想,并通过多种数理统计方法进行假设检验。最后,指出孔隙结构分布是一种多标度分形模型,仅仅单个维数无法描述其全部细节特征,需采用多重分形谱来更为全面表征孔隙分布的细观特征。研究结果表明,Hausdorff测度空间下的平面盒维数可较为全面表征平面孔隙分布特征,但对于针对灰度CT图像构建的体素盒维数可替代传统意义下定义的盒维数,在细观尺度下能更可靠、准确、全面地定量表征孔隙体积分布规律; 集束维数实质是用来定量表征孔隙位置分布规律,若等于欧氏维数,则表明孔隙位置分布具有随机性。 相似文献
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基于CLUE-S模型的长沙市望城区土地利用变化预测 总被引：1，自引：0，他引：1
针对长沙市望城区未来土地利用在类型数量和空间分布上的变化预测问题,在该区2009～2012年期间土地利用/覆盖现状图的基础上,提出了通过Markov链模型预测类型数量、利用CLUE-S模型预测空间分布的土地利用变化预测方法。在综合影响该区土地利用变化的地形、距离驱动因子的基础上,利用CLUE-S模型预测了研究区2012年和2020年的土地利用空间分布状况。实验表明,2012年土地利用预测结果得到了较高的Kappa系数和ROC值,间接证明了2020年的预测结果具有一定的可信度,对该区土地资源优化配置具有一定的参考价值和借鉴意义。 相似文献
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李杰陈思宇张静文徐培罡 《地理信息世界》2020,(3):31-34
疫情地理传播与网络舆情之间的时空关系对于开展突发疫情应对具有重要意义,是国家新型城镇化与发展全球化的重要课题。利用H7N9突发疫情感染人数、网络舆情关注数、网民人数、地理行政区划等数据,应用大数据分析与地理可视化方法,对疫情地理传播与网络舆情时空关系进行了研究。结果表明,疫情地理空间传播与网络舆情传播之间存在潜在的时空关系,主要表现为突发疫情引起的网络舆情的空间分布与现实疫情事件的地理空间分布特性具有总体相似一致性和局部偏差性。疫情传播与其引起的网络舆情传播的数量特性、时间特性、地理区域特性具有整体一致性;网络舆情反映疫情地理分布具有局部偏差性。 相似文献
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XU Jianhua CHEN Yaning LI Weihong DONG Shan 《中国地理科学(英文版)》2008,18(1):77-84
Based on the time series data from the Aral hydrological station for the period of 1958-2005, the paper reveals the long-term trend and fractal of the annual runoff process in the mainstream of the Tarim River by using the wavelet analysis method and the fractal theory. The main conclusions are as follows： 1） From a large time scale point of view, i.e. the time scale of 16 （24） years, the annual runoff basically shows a slightly decreasing trend as a whole from 1958 to 2005. If the time scale is reduced to 8 （23） or 4 （22） years, the annual runoff still displays the basic trend as the large time scale, but it has fluctuated more obviously during the period. 2） The correlation dimension for the annual runoff process is 3.4307, non-integral, which indicates that the process has both fractal and chaotic characteristics. The correlation dimension is above 3, which means that at least four independent variables are needed to describe the dynamics of the annual runoff process. 3） The Hurst exponent for the first period （1958-1973） is 0.5036, which equals 0.5 approximately and indicates that the annual runoff process is in chaos. The Hurst exponents for the second （1974-1989） and third （1990-2005） periods are both greater than 0.50, which indicate that the annual runoff process showed a long-enduring characteristic in the two periods. The Hurst exponent for the period from 1990 to 2005 indicates that the annual runoff will show a slightly increasing trend in the 16 years after 2005. 相似文献
12.
Relationship between changes of river-lake networks and water levels in typical regions of Taihu Lake Basin, China 总被引：1，自引：0，他引：1
The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence. 相似文献
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ZHUXiao-hua CAIYun-long 《中国地理科学(英文版)》2004,14(1):9-14
MANDELBROT enunciated the uncertainty of the length of a coastline in his paper “How long is the coastline of Britain?” published in Science in 1967. The fractal concept was presented for the first time in that paper and has been applied to many fields ever since. Although fractal dimensions of lots of phenomena were calculated by the box-counting method, the quantitative influence of series of square grids on them is ignored. The issue is systematically discussed as a case study of the mountains of China‘s Mainland in this paper. And some significant conclusions are drawn as follows: 1) Although the fractal character objectively exists in the mountains of China‘s Mainland, and it does not vary with the changes of series of square grids, the fractal dimensions of the mountains of China‘s Mainland are different with these changes. 2) The fractal dimensions of the mountains of China‘s Mainlandvary with the average lengths of sides of series of square grids. The fractal dimension of the mountains of China‘s Mainland is the function of the average length of side of square grid. They conform to the formula D=f(r) (where D is the fractal dimension, and r is the average length of side of square grid). 3) Different dots of data collection can affect the fractal dimension of the mountains of China‘s Mainland. 4) The same range of length of side of square grid and dots of data collection can ensure the comparison of fractal dimensions of the mountains of China‘ s Mainland. The research is helpful to get the more understanding of fractal and fractal dimension, and ensure that the fractal studies would be scientific. 相似文献
14.
??????????κ??????R/S????????????????????????????M??4.5????1970??2010??????M??1.0?????з???????????????????????????????????????????????????????е?H???H=0.79????????????е?H?(H=0.87)???????????????????????????ν??? 相似文献
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地学现象的分维与标度关系——以中国大陆山系为例 总被引：2，自引：1，他引：1
分形理论产生以后,已经在许多领域里取得了较为广泛的应用,但是在分形维数的计算方面仍存在一定的问题,最根本的问题之一是大量相关研究往往忽略了标度问题的影响,而将计算出的分维结果随意比较。本文则是以中国大陆山系为例,对地学现象的分维与标度的关系进行了研究,得出:(1)中国大陆山系的分形性质是客观存在的,其分形性质是不以测算标度而出现变化的,是始终存在的;(2)虽然在不同的测算标度下,中国大陆山系的分形性质始终是客观存在的,但是随着测算标度范围的变化,中国大陆山系的分维也会相应地出现一定的变化,即中国大陆山系客观存在的分形性质是绝对的,而分维则是一个相对的值,是随着测算标度而出现变化的;(3)分维不仅随着测算标度的变化而出现一定的变化,而且,分维是测算平均标度的函数,即D=f(r)(式中:r为测算平均标度,D为分维)关系成立;(4)因为分维值会随着不同标度范围的变化而出现相应的变化,所以,如果要进行分维之间的比较,则应选择相同的标度范围和标度值点。 相似文献
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Patel NILANCHAL 《中国地理科学(英文版)》2006,(1)
1INTRODUCTIONMandelbrot stated the uncertainty of the length of a coastline in his paper "How long is the coast of Britain? Statistical self-similarity and fractional dimension" pub- lished in Science in 1967 (MANDELBROT, 1967). The concepts of fractal and fractal dimension were presented for the first time in that paper and have been applied to quantitatively describing the difference of crooked coastlines of British and South Africa. Compared with the Euclidean geometry with more… 相似文献
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Ｆｒｏｍｔｈｅｅｎｄｏｆｔｈｅｎｉｎｅｔｅｅｎｔｈｃｅｎｔｕｒｙｔｏｔｈｅｂｅｇｉｎｎｉｎｇｏｆｔｈｅｔｗｅｎｔｉｅｔｈｃｅｎｔｕｒｙ，Ｄａｖｉｓ（１８９９）ｐｒｏｖｉｄｅｄｅｒｏｓｉｏｎａｌｃｉｒｃｕｌａｒｔｈｅｏｒｙ，ｔｏｏｋｇｅｏｍｏｒｐｈｉｃｃｈａｒａｃｔｅｒｉｓｔｉｃｓａｓｔｈｅｆｕｎｃｔｉｏｎｓｏｆｔｅｃｔｏｎｉｃｆｏｒｃｅｓａｎｄｔｉｍｅ，ｄｉｖｉｄｅｄｇｅｏｍｏｒｐｈｉｃｇｒｏｗｔｈｉｎｔｏｔｈｒｅｅｐｈａｓｅｓ：ｙｏｕｎｇ，ｍｉｄｄｌｅａｇｅｄａｎｄｏｌｄ，ａｎｄｔｈｅｎｒａ… 相似文献
18.
LI Yong LIU Jingling CHEN Xiaoqing WEI Fangqiang 《山地科学学报》2007,4(1):071-076
Debris flows consist of grains of various sizes ranging from 10~(-6) m ～1 m. Field observations in the Jiangjia Gully (JJG) and other sites throughout China indicate that the grain size distribution of sediment in debris flows can be characterized by an exponential function fit to the cumulative distribution. The exponent value for the function varies by location and may be useful in distinguishing between debris flows from different valleys. For example, minimum values and ranges of the exponent are associated with the high frequency of debris flows in the JJG. Furthermore, the distribution presents piecewise fractality (i.e. scaling laws hold in various ranges of the grain size) and we propose that the fractal structure determines the matrix and that the fractal dimension plays a crucial role in material exchange between a debris flow and the substrate it flows over. Finally, the empirical data support an exponential relation between grain composition and non-dimensional shear stress for the critical state of the channel. Overall we propose a material-determinism approach to studying debris flows which contrasts with the enviro-determinism that has dominated much recent work in this field. 相似文献
19.
ZHUXiao－hua WANGJian 《中国地理科学(英文版)》2002,12(2):142-145
MANDELBROT enunciated the uncertainty of the length of a coastline in his paper“How long is the coast-line of Britain?“ published in “Science“in 1967.The fractal concept was presented for the first time in that paper and has been applied to many fields ever since.According to the fractal theory and conditions of fractal research of coastline,the controls of faults and biologic function on the fractal character of coastline are preliminarily discussed on the basis of GIS in this paper.Finally,some significant conclusions are drawn:1)the faults control the basic trends of coastlines of two study areas;2)the fractal dimension of coastline of Taiwan is smaller than that of Changle-Lufent,because the faults of Taiwan more intensely control the trend and fractal dimension of the coastline;3)the larger the fractal dimension of the faults or the major faults ,the more the controlling effect of them on the trend and fractal dimension of coastline;4)the larger fractal dimension of the coastline of Changle-Lufeng indicates that the biologic function intensely shapes the coastline .In a word ,the controls of faults and biologic function on the fractal character of coastline are discussed with a case study of China in this paper,it can be seen that faults and biologic function both have influence over the trend and fractal dimension of coastline,the fractal mechanism of coastline of two study areas may be so. 相似文献