中国断裂构造的分形特征及其大地构造意义   总被引：14，自引：4，他引：10  

谭凯旋 《大地构造与成矿学》1998,22(1):17-20

中国大陆壳体中深大断裂的分布具有分形结构特征。大陆全境的分维值为1．493,各构造区的分维值为0．827～1．624。活动区特别是地洼区中断裂构造分维值（1．236～1．624）显著大于稳定区即地台区的分维值（0．827～1．074）,并且壳体结合部位的分维值大于壳内部位。断裂构造的分维值反映了区域大地构造演化、运动历史的复杂性和构造活动的强弱性,因而可作为大地构造研究的一个定量参数。  相似文献   

基因算法在地质分维数估计中的应用     

黄诗峰  金菊良 《地质科技情报》1998,17(3):81-84

介绍了估计了质分维数的传统基因算法的主要步骤及改进的基因算法,并通过实例与传统的线性最小二乘法和非线性叠代法进行了比较,表明该方法直观,简便,通用性强,并具有较高的拟合精度。  相似文献   

Scattering attenuation and the fractal geometry of fracture systems     

Ian G. Main  Sheila Peacock  Philip G. Meredith 《Pure and Applied Geophysics》1990,133(2):283-304

Scattering of seismic waves can be shown to have a frequency dependenceQ ^{–1 3–v} if scattering is produced by arrays of inhomogeneities with a 3D power spectrumW _3D(k) k ^–v. In the earth's crust and upper mantle the total attenuation is often dominated by scattering rather than intrinsic absorption, and is found to be frequency dependent according toQ ^–1 , where –1<–0.5. IfD ₁ is the fractal dimension of the surface of the 3D inhomogeneities measured on a 2D section, then this corresponds respectively to 1.5<D ₁1.75, since it can be shown that =2(D ₁–2). Laboratory results show that such a distribution of inhomogeneities, if due to microcracking, can be produced only at low stress intensities and slow crack velocities controlled by stress corrosion reactions. Thus it is likely that the earth's brittle crust is pervaded by tensile microcracks, at least partially filled by a chemically active fluid, and preferentially aligned parallel to the maximum principal compressive stress. The possibility of stress corrosion implies that microcracks may grow under conditions which are very sensitive to pre-existing heterogeneities in material constants, and hence it may be difficult in practice to separate the relative contribution of crack-induced heterogeneity from more permanent geological heterogeneities.By constrast, shear faults formed by dynamic rupture at critical stress intensities produceD ₁=1, consistent with a dynamic rupture criterion for a power law distribution of fault lengths with negative exponentD. The results presented here suggest empirically thatD ₁-1/2(D+1), thereby providing the basis for a possible framework to unify the interpretation of temporal variations in seismicb-value (b-D/2) and the frequency dependence of scattering attenuation ().This is PRIS contribution 046.  相似文献   

基于去噪和分形的加密货币投资组合模型优化研究     

曹广喜  张星宇 《南京气象学院学报》2021,13(3):369-376

为提高投资效益,本文针对传统投资组合模型的缺陷,结合经验模态分解（EMD）去噪法和多重分形消除趋势交叉相关分析法（MF-DCCA）,提出经验模态分解去噪下的多重分形投资组合模型（简称EMD-Mean-MF-DCCA）.将新模型应用于极具投机性的加密货币投资组合,结合滚动窗口技术进行样本外检验和分析,实证结果显示：无论加密货币价格处于上升还是下降趋势,EMD-Mean-MF-DCCA相对于其他传统投资组合模型及未去噪的分形投资组合模型,均在盈利能力和夏普比率方面具有明显优化效果,且当加密货币价格大幅下跌时,基于新模型的组合投资策略也具有较好的抵抗风险能力.  相似文献   

The effect of the temporal resolution of the wind forcing on a central Mediterranean Sea model     

《Dynamics of Atmospheres and Oceans》2021

The impact of the wind forcing temporal resolution in the central Mediterranean Sea is addressed using a numerical ocean circulation model. The model uses interactive surface fluxes based on the ERA-Interim 6-hourly atmospheric reanalyses except for the 10 m wind for which ERA5 hourly reanalyses are used. Additional temporal resolution (2, 3, 6, 12 and 24 h) wind sets are deduced from the ERA5 hourly data. An ensemble of simulations (six members) is then performed where only the temporal resolution of the wind forcing is changed. The impact of the temporal resolution is studied based on this set of simulations. The dependence of the surface wind stress and heat flux on the wind resolution is derived based on an analytical expression where the Weibull distribution is used to characterise the probability density function of the wind speed. Results from the analytical model are found close to those from the numerical model when a linear increase of the exchange coefficients with the wind speed is considered. Power input into the sea and surface heat loss both increase with the increase of the temporal resolution but at lower rates when approaching hourly forcing values. The increase of the latent heat loss at these high resolutions is small (~−0.8 Wm^-2) but still important, around 10–20% the Mediterranean basin heat budget (−5 to −7 Wm^-2). The increase of the wind forcing temporal resolution decreases the sea surface temperature (SST) and increases the sea surface salinity (SSS) with largest values in the shallow area of the Gulf of Gabès (eastern coast of Tunisia). A decrease of SSS is however noticed in some areas mainly northwest of the Tunisia coast. Hydrographical changes are also found in the Tunisia-Sicily channel. They are characterised by mesoscale structures with no remarkable change of the major water veins.  相似文献   

Spatial Distribution,Scaling and Self-similar Behavior of Fracture Arrays in the Los Planes Fault,Baja California Sur,Mexico     

A. F.?Nieto-SamaniegoEmail author  S. A.?Alaniz-Alvarez  G.?Tolson  K.?Oleschko  G.?Korvin  S. S.?Xu  J. A.?Pérez-Venzor 《Pure and Applied Geophysics》2005,162(5):805-826

We present a case of detailed analysis of fracture arrays spanning four orders of magnitude in length; all of them measured at a single natural site by acquiring images at progressively larger scales. There is a high dispersion of cumulative-length exponents, box dimensions and fracture densities. However, the fractal analysis supports the fractal nature of fracture arrays. Our data indicate the existence of an upper limit for the density parameters, as similarly reported by other authors. We prove that box dimension is in inverse relation with fracture concentration and in direct relation with fracture density. These relations are also observed in our data and additionally there is an upper limit for the box dimensions. We interpret the dispersion in our results as more fundamental than methodological problems. It represents a truncation in the complete evolution of the fracture systems because in natural cases strain initiates overprinting of previous fracture arrays. Considering that larger fractures accommodate strain more efficiently than small fractures, the generation of small fractures is inhibited in the presence of pre-existing larger fractures. Maximum values of fracture density prevent accommodating an excess of strain in a single or restricted range of scales; we claim this condition produces migration of fracturing to larger scales originating fracture scaling.  相似文献   

Multifractality as a Measure of Spatial Distribution of Geochemical Patterns   总被引：3，自引：0，他引：3  

Alireza Panahi  Qiuming Cheng 《Mathematical Geology》2004,36(7):827-846

To quantify the spatial distribution of geochemical elements, the multifractality indices for Zn, Cu, Pt, Pd, Cr, Ni, Co, Pb, and As in lake-sediment samples in the Shining Tree area in the Abitibi area of Ontario are determined. The characterization of multifractal distribution patterns is based on the box-counting moment method and involves three functions: a mass exponent function (q); Coarse Hölder Exponent (q); and fractal dimension spectrum f( (q)). Properties of these functions at different values of q, characterize the spatial distribution of the variable under study. It is shown that the degree of multifractality defined by (1) can be used as a measure of irregularity of geochemical spatial dispersion patterns. The variations of Zn and Cu in the study area are characterized by relatively low degree of multifractality, whereas those for Pt, Pd, Cr, Ni, and Co; and particularly for As and Pb are characterized by higher multifractality indices.In the case of Zn and Cu, singularity spectra are close to a monofractal compared to the ones for As an Pb. The determination of multifractality indices allows us, in a quantitative way, to study the pattern of metal dispersions and link them to different physical processes, such as metal adsorption by organic material or glaciogenic processes.  相似文献   

基岩海岸节理对区域宏观断裂系的响应及其对海岸线分形性质的影响研究--以中国福州市基岩海岸为例   总被引：1，自引：1，他引：1  

朱晓华  王建  蔡运龙 《海洋通报》2003,22(5):23-25

在跟踪国内外相关研究进展的基础上，通过采取野外实地勘测与室内分析相结合的研究方法，以中国福州市基岩海岸为例探讨了基岩海岸节理对区域宏观断裂系的响应以及节理对海岸线分形性质的影响问题。得到的基本结论为：第一，节理与区域大尺度宏观断裂系存在着一定的响应关系；第二，节理由于其空间复杂程度的不同和发育走向的差异，对海岸线的分形性质产生着不同程度的重要影响。  相似文献   

大亚湾海水温度的时空分布   总被引：1，自引：0，他引：1  

曾刚  许金殿 《台湾海峡》1991,10(2):110-116

本文根据1987年1～12月逐月的水文实测资料,利用统计方法,详细地分析了大亚湾海水温度的时空分布和年、日变化特征以及影响水温变化的主要因子,文内还指出了本海域常见的两种不同类型的水温日变化的特征。  相似文献   

热带太平洋海区混沌特征分析     

姜华  吴德星 《中国海洋大学学报(自然科学版)》2001,31(1):1-6

基于 TOGA- TAO锚定于热带太平洋海区的 53个浮标站 1994年冬季海表温度 ( SST)资料 ,采用多种分析非线性动力系统的方法。如谱分析 ,相空间重构法等 ,以及计算描述混沌行为的重要指标 ,如分维数、L yapunov指数等 ,对热带太平洋是否存在混沌现象进行判别分析。发现在热带太平洋 130°W至 12 0°W之间存在强混沌区 ,在西边界附近也存在混沌区。但通过吸引子的相型可以看出热带东太平洋与西太平洋是不同性质的非线性动力系统 ,导致系统出现混沌现象的原因可能是不同的。  相似文献