分形方法分析和预测月平均海面水温   总被引：5，自引：0，他引：5  

付昱华 《海洋预报》1995,12(1):49-54

本文用分段变维分形方法分析了西北太平洋３０°Ｎ、１２５°Ｅ坐标点处１９４９～１９７５年各年月平均海面水温资料，给出各年分形分布的平均分线数Ｄ．应用分形方法还给出了某些情况下适用的，根据任一点处１～８月月平均海面水温预测９～１２月月平均海面水温的方法．  相似文献   

Variation of singularity of earthquake-size distribution with respect to tectonic regime     

Qiu-Ming Cheng  Hong-Yun Sun 《地学前缘(英文版)》2018,9(2):453-458

Frequency-size relation of earthquakes in a region can be approximated by the Gutenberg-Richter law(GR). This power-law model involves two parameters: a-value measuring seismic activity or earthquake productivity, and b-value describing the relation between frequencies of small and large earthquakes.The spatial and temporal variations of these two parameters, especially the b-value, have been substantially investigated. For example, it has been shown that b-value depends inversely on differential stress. The b-value has also been utilized as earthquake precursor in large earthquake prediction.However, the physical meaning and properties of b-value including its value range still remain as an open fundamental question. We explore the property of b-value from frequency-size GR model in a new form which relates average energy release and probability of large earthquakes. Based on this new form of GR relation the b-value can be related to the singularity index(1-2/3 b) of fractal energy-probability power-law model. This model as applied to the global database of earthquakes with size M ≥ 5 from 1964 to 2015 indicates a systematic increase of singularity from earthquakes occurring on mid-ocean ridges, to those in subduction zones and in collision zones.  相似文献   

从美国地球物理学会2001秋季年会谈非线性地球物理进展   总被引：1，自引：0，他引：1  

成秋明 《地球物理学进展》2002,17(2):356-359

简要介绍美国地球物理协会2001秋季年会“非线性地球物理”分会的活动情况。它可以大致反映出目前非线性理论和非线性地球物理的发展现状和趋势,尤其是在分形,多维分形,尺度独立性,混沌和自组织临界理论方面的研究。  相似文献   

Optimal Design of a Gravity Survey Network and its Application to Delineate the Jabera-Damoh Structure in the Vindhyan Basin,Central India     

Ravi Prakash Srivastava  Nimisha Vedanti  V. P. Dimri 《Pure and Applied Geophysics》2007,164(10):2009-2022

Fractal dimension analysis was carried out for optimal designing of 2-D gravity survey network and to determine an optimum range of gridding interval to generate least aliased Bouguer anomaly maps. As a test case, this method has been successfully applied to the Jabera-Damoh region of the Vindhyan Basin, which is considered as a potential hydrocarbon bearing area. In particular, we aim to delineate accurately the lateral extent of a possible hydrocarbon bearing structure. To achieve this aim, fractal dimension of survey network was computed using 2-D distributions of observation points in the planning phase of the survey so that the optimum station spacing for gravity survey can be obtained. A range of optimum gridding interval for the gravity data set was suggested using the box-counting method of fractal dimension determination. Bouguer anomaly maps of the region are prepared utilizing the optimum gridding interval. For the first time, these anomaly maps clearly outline the gravity evidence of an anomalous rifted structure, which is bounded by parallel faults on either side. This structure is interpreted as a favorable basin for the occurrence of hydrocarbons. Another finding of this study has been the delineation of an apparently small ridge-like structure running east-west, dividing this basin in two parts. A subsurface geological model along a profile across the Jabera structure has also been presented.  相似文献   

Statistical self-affinity, fractal dimension, and geologic interpretation     

James R. Carr 《Engineering Geology》1997,48(3-4):269-282

Properties of statistical self-affinity are explored and explained. Semi-variogram analysis can be used for identifying statistical self-affine behavior. This is, however, not the only method available for such an analysis. Some error and interpretation is involved; therefore, estimating the Hurst dimension (and from this the fractal dimension) from the semi-variogram can be misleading. Simulations based on statistical self-affine properties are alternatively used to develop an empirical approach to assessing statistical self-affine behavior. Analyzing simulations using semi-variograms, and comparing these semi-variograms to those from actual data, offers an alternate and perhaps superior approach to the understanding of the statistical self-affine properties of a geologic phenomenon. This empirical approach offers a method of reverse modeling for verifying estimates of Hurst dimension from semi-variograms.  相似文献   

Detailed gravity studies over Jabera — Damoh region of the Vindhyan basin (Central India) and crustal evolution     

Ravi P. Srivastava  Nimisha Vedanti  O. P. Pandey  V. P. Dimri 《Journal of the Geological Society of India》2009,73(5):715-723

Vindhyan Basin of Central India situated just north of SONATA rift zone, forms one of the major geotectonic segment of the Indian subcontinent which is associated with complex thermo-tectonic history. Southern part of this basin is known to contain favorable conditions for hydrocarbon entrapment. Keeping this in view, a detailed gravity survey network comprising 40 gravity bases and 1500 data points in an area of about 110 × 100 km² was planned in and around Jabera-Damoh region. Analysis of Bouguer and free air gravity anomaly maps, prepared using fractal based gridding method, indicates presence of two sedimentary basins (Jabera and Damoh) faulted on either sides beside ridge like features. However, well-known Jabera domal structure appeared to be a shallow feature only. Inversion of gravity data further reveals presence of 5 to 6 km thick Vindhyan sediments in the Jabera basin which are underlain by Mahakoshal/Bijawar group of rocks, resting directly over the lower crust, thereby indicating almost total absence of granitic crust from this region. It appears that due to an underlying thermal anomaly, the entire region may have been subjected to sustained uplift, deformation, erosion and consequent crustal extension during early to mid Proterozoics which brought high velocity mafic crust to such shallow levels.  相似文献   

Experimental study of slaking properties of red-bed mudstones from the Three Gorges Reservoir area     

Peiwu Shen  Dingjian Wang 《Marine Georesources & Geotechnology》2013,31(8):891-901

Abstract

The slake durability; grain quantity, size, roundness, and slake degree of red-bed mudstones are experimentally investigated using the slake durability test and the cyclic wetting and drying test. Results indicate that the complete slaking process exhibits three distinct stages. During the process, the slake durability index decreases linearly with increasing cycle number. Slight variation in grain quantity is observed. Smaller grain size fractions tend to have higher slaking degree indexes in earlier cycles. Grain roundness fluctuates. Two parameters, namely, fractal dimension and surface energy, are revealed to have the ability to represent the degree of slaking of red-bed mudstones.  相似文献   

Modelling of magnetic data for scaling geology     

A.R. Bansal  V.P. Dimri 《Geophysical Prospecting》2014,62(2):385-396

Interpretation of magnetic data can be carried out either in the space or frequency domain. The interpretation in the frequency domain is computationally convenient because convolution becomes multiplication. The frequency domain approach assumes that the magnetic sources distribution has a random and uncorrelated distribution. This approach is modified to include random and fractal distribution of sources on the basis of borehole data. The physical properties of the rocks exhibit scaling behaviour which can be defined as P(k) = Ak^?β, where P(k) is the power spectrum as a function of wave number (k), and A and β are the constant and scaling exponent, respectively. A white noise distribution corresponds to β = 0. The high resolution methods of power spectral estimation e.g. maximum entropy method and multi‐taper method produce smooth spectra. Therefore, estimation of scaling exponents is more reliable. The values of β are found to be related to the lithology and heterogeneities in the crust. The modelling of magnetic data for scaling distribution of sources leads to an improved method of interpreting the magnetic data known as the scaling spectral method. The method has found applicability in estimating the basement depth, Curie depth and filtering of magnetic data.  相似文献   

Ecological and socio-economical thresholds of land and plant-community degradation in semi-arid Mediterranean areas of southeastern Spain     

C.L. Alados  J. Puigdefábregas  J. Martínez-Fernández 《Journal of Arid Environments》2011,75(12):1368-1376

The climate of semi-arid Mediterranean areas is characterized by highly variable rainfall and seasonal droughts, which favor highly specialized flora, high biodiversity, and the emergence of a large number of endemic species. Such highly specialized complex ecosystems are expected to be more difficult to return to a previous state following perturbation than are more mild ecosystems and lead to dramatic transitions in vegetation. An understanding of the circumstances under which irreversible transition shifts occur is vital in an age of climate change and socio-economic globalization. This will have significant consequences for those highly specialized areas unless management practices, conservation, and preventive measures are increased. Within ecosystems, the interactions between multiple factors acting at multiple temporal and spatial scales, and the inertia of ecological processes, make the consequences of current management practices persist for a long time. To understand the relative importance of the underlying mechanisms that influence the resilience of drylands in southeastern Spain, we reviewed what is known about plant–soil interactions and the spatial distribution of vegetation to detect early warning signs of desertification. We analyzed the role of the self-organizing capacity of vegetation in the formation of vegetation spatial patterns at multiple spatial scales. In addition, we evaluated the importance of threshold indicators as early detectors of transition shifts in dryland ecosystems.  相似文献   

Discrete Scale Relativity     

Robert L. Oldershaw 《Astrophysics and Space Science》2007,311(4):431-433

The possibility that global discrete dilation invariance is a fundamental symmetry principle of nature is explored. If the discrete self-similarity observed in nature is exact, then the Principle of General Covariance needs to be broadened in order to accommodate this form of discrete conformal invariance, and a further generalization of relativity theory is required.  相似文献