唐山地震前兆场的分布特征     

梁子彬  石玉成  蔡红卫 《高原地震》1995,(3)

本文对唐山地震昌黎等七个台的地电阻率日均值时间序列进行了关联维计算．取每年为一个时间段，其目的在于探索分数维对地震各个阶段的反应，以便达到利用分数维进行地震预报的目的。计算结果表明大部分地电台的地电阻率在地震前有明显的降维特征。通过地震前后七个台的地电阻率分数维的变化，得到了地震前后前兆场的分布特征，这一结果对于未来震源区的判定有重要意义。  相似文献   

从时间序列中提取维数信息   总被引：2，自引：1，他引：2       下载免费PDF全文

罗勇 《气象》1995,21(4):16-21

作者介绍了分形和分维的概念、性质和意义，重点讨论了从一维时间序列中提取维数信息的方法，并给出了一些在天气和气候中的应用。  相似文献   

节理岩体断裂的分形机理研究          下载免费PDF全文

杨太华 《地震工程学报》1995,17(1):10-14,22

本文在考察了节理化岩体的断裂力学特征的基础上，结合现代分形几何原理，建立起追踪裂纹裂分形模型，对不连续岩体的断裂韧性的分形效应进行了深入研究，并通过压剪试验得到难。  相似文献   

Multi-phase flow modeling of air sparging   总被引：3，自引：0，他引：3  

M. I. J. van Dijke  S. E. A. T. M. van der Zee  C. J. van Duijn 《Advances in water resources》1995,18(6)

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论"单位涌水量就是导水系数"   总被引：2，自引：0，他引：2  

兰太权 《地下水》2007,29(5):43-45,68

单位涌水量是井抽水水位降深换算为1 m时的单井出水量;导水系数是含水层宽度为1 m时,地下水水力坡度为1时的单宽流量.二者之间从定义上看毫无关系,但它们的单位(m3/d·m)(m2/d)是相同的.笔者经过多年探讨和初步试验后发现,单位涌水量就是管井抽水所利用含水层的导水系数.  相似文献   

闽江河口湿地资源动态变化的分形研究     

钟春棋  曾从盛  柳铮铮 《湿地科学与管理》2007,3(3):50-53

本研究以分形理论为基础,并借助GIS、RS技术,利用1986年和2002年两期TM遥感影像,提取获得了1986年和2002年闽江河口湿地资源的空间信息,根据分形理论中分形维数和稳定性指数的物理意义,揭示了闽江河口湿地资源动态变化情况。研究表明:闽江河口的湿地类型具有分形结构.并且由于受到较强的人类活动的干预,湿地斑块的形状较为复杂,且稳定性较差。  相似文献   

Suspended sediment load transport in the Mississippi River basin at St. Louis: temporal scaling and nonlinear determinism     

Bellie Sivakumar  Ji Chen 《地球表面变化过程与地形》2007,32(2):269-280

This study investigates the dynamic behavior of suspended sediment load transport at different temporal scales in the Mississippi River basin. Data corresponding to five successively doubled temporal scales (i.e. daily, two‐day, four‐day, eight‐day and 16‐day) from the St. Louis gaging station in Missouri are analyzed. The investigation is focused on identifying possible low‐dimensional deterministic behavior in the suspended sediment load transport dynamics, with an aim towards reduction in model complexity. The correlation dimension method is used to identify low‐dimensional determinism. The suspended sediment load dynamics are represented through phase‐space reconstruction, and the variability is estimated using the (proximity of) reconstructed vectors in the phase space. The results indicate the presence of low‐dimensional determinism in the suspended sediment load series at each of the five temporal scales, with the variables dominantly governing the dynamics in the order of three or four. These results not only suggest the appropriateness of relatively simpler models but also hint at possible scale invariance in the suspended sediment load transport dynamics. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Nonlinear determinism in river flow: prediction as a possible indicator   总被引：2，自引：0，他引：2  

Bellie Sivakumar 《地球表面变化过程与地形》2007,32(7):969-979

Whether or not river flow exhibits nonlinear determinism remains an unresolved question. While studies on the use of nonlinear deterministic methods for modeling and prediction of river flow series are on the rise and the outcomes are encouraging, suspicions and criticisms of such studies continue to exist as well. An important reason for this situation is that the correlation dimension method, used as a nonlinear determinism identification tool in most of those studies, may possess certain limitations when applied to real river flow series, which are always finite and often short and also contaminated with noise (e.g. measurement error). In view of this, the present study addresses the issue of nonlinear determinism in river flow series using prediction as a possible indicator. This is done by (1) reviewing studies that have employed nonlinear deterministic methods (coupling phase‐space reconstruction and local approximation techniques) for river flow predictions and (2) identifying nonlinear determinism (or linear stochasticity) based on the level of prediction accuracy in general, and on the prediction accuracy against the phase‐space reconstruction parameters in particular (termed as the ‘inverse approach’). The results not only provide possible indications to the presence of nonlinear determinism in the river flow series studied, but also support, both qualitatively and quantitatively, the low correlation dimensions reported for such. Therefore, nonlinear deterministic methods are a viable complement to linear stochastic ones for studying river flow dynamics, if sufficient caution is exercised in their applications and in interpreting the outcomes. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

土壤水分特性曲线的分形模拟   总被引：23，自引：1，他引：23       下载免费PDF全文

黄冠华  詹卫华 《水科学进展》2002,13(1):55-60

应用Menger海绵结构模型,推导出包含有分形维数的土壤水分特征曲线的解析模型,该模型与Brook Corey (1964)及Campbell (1974)经验模型的结构相似。通过对不同地区所采集的10种土壤样本利用压力薄膜仪实测得到水分特性曲线资料反求得到相应的分形维数,分析了分形维数与土壤质地、结构之间的关系,结果表明分形维数随土壤粘粒含量的增大而增大,随砂粒含量的增大而减小。同时对土壤水分特性曲线模型的分形维数与基于质量的土壤颗粒分布分形维数进行了比较,结果表明,两者十分接近,而且具有良好的线性相关关系。根据上述关系,利用易测得的土壤粒径分形维数结合所推导的解析模型,对土壤水分特性曲线进行了预测,预测值与实测值具有良好的一致性。  相似文献   

淮南矿区潘三矿构造发育规律定量研究   总被引：1，自引：0，他引：1  

周云霞  曹代勇等 《中国煤田地质》2002,14(3):4-6

本文采用煤层构造形态空间分析、断裂要素数理统计分析等方法,并引入断裂分形维数指标作为刻划断裂构造发育强度的指标之一,对准南矿区潘三矿地质构造进行了定性—定量分析,揭示了矿井地质构造发育的南北分带性和东西分区性特征。  相似文献