共查询到20条相似文献，搜索用时 234 毫秒
1.
裂缝诱导的双相具有水平对称轴的横向各向同性(HTI)介质模型是由一组平行排列的垂直裂缝嵌入到统计各向同性的流体饱和多孔隙岩石中而组成的,它综合考虑了裂缝型储层岩石的各向异性和孔隙性.高精度的地震波场数值模拟技术是研究该介质中地震波传播规律的主要方法.本文结合错格伪谱法和时间分裂法,求解描述该介质中地震波传播的一阶速度-应力方程.模拟了单层和双层模型中的地震波场,并对其进行了特征分析.研究结果表明:错格伪谱法能有效消除标准网格伪谱法波场模拟结果中出现的数值伪影现象,与时间分裂法结合能够获得稳定的、高精度的模拟结果;裂缝诱导双相HTI介质中的地震波场兼具裂缝各向异性介质和双相介质中传播的地震波的波场特征. 相似文献
2.
I. S. Knyazeva Yu. A. Nagovitsyn F. A. Urt’ev N. G. Makarenko 《Geomagnetism and Aeronomy》2016,56(7):853-857
Detection of the deterministic component from noised time series is a common procedure in the solar–terrestrial coupling problem when climate is modeled, solar activity is analyzed, or a signal associated with helium is extracted. Such series are mostly generated by the superposition of different processes for which the concept of a noise component cannot be determined formally. A method based on the combination of time-series topological embedding in Euclidean space and the identification of a persistent cycle by homology theory methods is proposed. The method application is demonstrated based on actual data. 相似文献
3.
A new method is proposed to inverse normalization data of hidden variables in a dynamical system by embedding a time series
in multidimensional spaces and applying a normalization analysis to the conditional probability density of points in the reconstructed
phase spaces. The method is robust in the application to Lorenz system and 4-dimensional R?ssler system by testing quantitatively
and qualitatively the correlation coefficient between inverse data and original data in time domain and in frequency domain,
respectively. By applying the method to analyzing the South China Sea data, the normalization data of wind speed is extracted
from the sea surface temperature time series. 相似文献
4.
A bivariate meta-Gaussian density for use in hydrology 总被引：3，自引：0，他引：3
Convenient bivariate densities found in the literature are often unsuitable for modeling hydrologic variates. They either
constrain the range of association between variates, or fix the form of the marginal distributions. The bivariate meta-Gaussian
density is constructed by embedding the normal quantile transform of each variate into the Gaussian law. The density can represent
a full range of association between variates and admits arbitrarily specified marginal distributions. Modeling and estimation
can be decomposed into i) independent analyses of the marginal distributions, and ii) investigation of the dependence structure.
Both statistical and judgmental estimation procedures are possible. Some comparisons to recent applications of bivariate densities
in the hydrologic literature motivate and illustrate the model. 相似文献
5.
A bivariate meta-Gaussian density for use in hydrology 总被引：3，自引：0，他引：3
K. S. Kelly R. Krzysztofowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(1):17-31
Convenient bivariate densities found in the literature are often unsuitable for modeling hydrologic variates. They either
constrain the range of association between variates, or fix the form of the marginal distributions. The bivariate meta-Gaussian
density is constructed by embedding the normal quantile transform of each variate into the Gaussian law. The density can represent
a full range of association between variates and admits arbitrarily specified marginal distributions. Modeling and estimation
can be decomposed into i) independent analyses of the marginal distributions, and ii) investigation of the dependence structure.
Both statistical and judgmental estimation procedures are possible. Some comparisons to recent applications of bivariate densities
in the hydrologic literature motivate and illustrate the model. 相似文献
6.
Nonlinear ensemble prediction of chaotic daily rainfall 总被引：3，自引：0，他引：3
The significance of treating rainfall as a chaotic system instead of a stochastic system for a better understanding of the underlying dynamics has been taken up by various studies recently. However, an important limitation of all these approaches is the dependence on a single method for identifying the chaotic nature and the parameters involved. Many of these approaches aim at only analyzing the chaotic nature and not its prediction. In the present study, an attempt is made to identify chaos using various techniques and prediction is also done by generating ensembles in order to quantify the uncertainty involved. Daily rainfall data of three regions with contrasting characteristics (mainly in the spatial area covered), Malaprabha, Mahanadi and All-India for the period 1955–2000 are used for the study. Auto-correlation and mutual information methods are used to determine the delay time for the phase space reconstruction. Optimum embedding dimension is determined using correlation dimension, false nearest neighbour algorithm and also nonlinear prediction methods. The low embedding dimensions obtained from these methods indicate the existence of low dimensional chaos in the three rainfall series. Correlation dimension method is done on the phase randomized and first derivative of the data series to check whether the saturation of the dimension is due to the inherent linear correlation structure or due to low dimensional dynamics. Positive Lyapunov exponents obtained prove the exponential divergence of the trajectories and hence the unpredictability. Surrogate data test is also done to further confirm the nonlinear structure of the rainfall series. A range of plausible parameters is used for generating an ensemble of predictions of rainfall for each year separately for the period 1996–2000 using the data till the preceding year. For analyzing the sensitiveness to initial conditions, predictions are done from two different months in a year viz., from the beginning of January and June. The reasonably good predictions obtained indicate the efficiency of the nonlinear prediction method for predicting the rainfall series. Also, the rank probability skill score and the rank histograms show that the ensembles generated are reliable with a good spread and skill. A comparison of results of the three regions indicates that although they are chaotic in nature, the spatial averaging over a large area can increase the dimension and improve the predictability, thus destroying the chaotic nature. 相似文献
7.
Confocal scanning light microscopy is a valuable new method for examining the nature and progress of stone weathering at a level of resolution between optical microscopy and scanning electron microscopy. Not only is it non-destructive, but it can also create three-dimensional images. 相似文献
8.
Jacobo Bielak 《地震工程与结构动力学》1974,3(3):259-274
A study of the dynamics of building-soil interaction is presented that includes embedding of the foundation and material damping. By considering buildings on rigid footings embedded into linear elastic soil with hysteretic damping, it is shown that the earthquake response of the building-foundation model may be found from the response to modified excitation of equivalent one-degree-of-freedom linear, viscously damped oscillators resting on rigid ground. For a single-storey building approximate formulas are developed for the modified natural frequency and damping ratio. Results show that the natural frequency and damping in the system increase with embedding. Effective damping also increases with internal friction in the soil. Ignoring these two factors may underestimate considerably the effective natural frequency and damping in the system. In spite of additional sources of energy dissipation provided by the soil, damping in the equivalent oscillator may be greater or smaller than that corresponding to the superstructure alone, depending upon the system parameters. For lightly damped superstructures, the peak amplitude of the steady-state overturning moment at the base of a building supported on flexible soil is significantly smaller than that corresponding to rigid ground. This result has practical implications for earthquake design. 相似文献
9.
In this work, we present the diagnostics results of the similarity between different temperature paleoreconstructions using network approaches. The correlation patterns of time series are transformed into the geometry of the corresponding graph, which can be analyzed geometrically. To detect a possible nonlinear connection between climatic series and solar activity, we use networks constructed by embedding time series in the space of an appropriate dimension. Finally, we present Markov networks for climatic reconstructions and annual Wolf numbers. 相似文献
10.
根据新丰江中心地震台实际业务工作的需要,在Visual C++6.0平台上,使用ActiveX Data Objects(ADO)技术,通过客户/服务器(C/S)模式访问MySQL数据库表,并基于MFC(微软基本类库,Microsoft Foundation Classes)的OLE(对象链接嵌入,Object Linking and Embedding)编程方法操作EXCEL报表文件,开发出一套地震数据处理软件,完成台站日常数据的录入、查询、修改、转换和报表输出等工作,实现地震台站的无纸化、网络化办公,提高工作效率。 相似文献
11.
在坑道中或地表上,对地壳形变所进行的各种观测,是了解地下应力活动的重要手段。目前,国内外开展在岩石中钻孔进行应力测定存在的问题,是受局部偶然因素的影响较大,需要注意克服。 求取地下岩体中的实际应力值,不仅是地震预报工作的需要,也是建筑、水坝、隧道、 相似文献
12.
本文详细讨论了现有抗震结构破坏评估准则并指出其不足和存在问题,深入研究了抗震结构破坏准则的基本思路和发展趋势。指出了由于结构地震响应从地面运动到结构性能两方面固有的随机性和不确定性,使基于性能的抗震设计应当在概率的基础上形成;破坏模型作为度量结构破坏程度的有效工具,也应当在概率基础上形成。 相似文献
13.
A new scheme for fast calculation of seismic traveltimes and ray paths in heterogeneous media 总被引：2，自引：0，他引：2
IntroductionBoth traveltimes and ray paths are vital information for seismic theoretical research and practice such as stack migration, traveltime inverse, calculation of covering time and so on (Xu, et al,1992). At present, they are obtained usually by either ray shooting (Liu, el al, 1986) or finite difference solution of the eikonal equation (Vidale, 1988; Zhang, et al, 1996). The ray shootingmethod can be understood and programmed easily. However, it is difficult for the method to treatc… 相似文献
14.
针对辽宁省数字化地电阻率观测数据的特点,找出同步高频变化干扰数据的识别及处理方法;观测资料中缺测数据的干扰识别及处理方法;无物理基础的观测量值识别及处理方法等;通过VB编程快捷、方便地剔除瞬时干扰数据,有利于地震预报人员对数字化观测干扰数据的处理,并对地下介质的动态变化做出正确的分析、判断. 相似文献
15.
为了剖析大地电磁信号和强干扰的本质特征,进一步精细分离出微弱的大地电磁有用信号,提出基于递归分析和聚类的大地电磁信噪辨识及分离方法.首先,运用递归分析法扩展大地电磁一维时间序列的维数,分析了嵌入维数、延迟时间和判别阈值对递归图的性能,并研究了不同长度的序列对递归定量分析参数的影响情况,然后,构建典型的大地电磁强干扰类型和微弱的大地电磁有用信号样本库,针对样本库讨论了强干扰和微弱大地电磁信号之间的递归定量分析参数,分析了K均值聚类和模糊C均值聚类的信噪辨识效果.最后,对实测大地电磁数据进行信噪辨识处理,并仅对辨识为强干扰的时间段采用数学形态滤波进行噪声压制.实验结果表明,递归分析能定性及定量地描述大地电磁信号时间序列的非线性特征和原动力系统的本质规律,与聚类算法相结合能对矿集区实测大地电磁信号进行信噪辨识;处理后的卡尼亚电阻率-相位曲线更为光滑、连续,其结果更为精细地保留了大地电磁信号低频段的缓变化信息,整个低频段的大地电磁数据质量得到了明显改善. 相似文献
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17.
Introduction When seismic waves propagate in a medium of complex geometry,such as a dam,it pro-duces stress concentration area at some spots of the dam because of the interface reflection and refraction of the waves,resulting in serious safety risk.Understanding seismic wave propagation in complex mediums becomes very important.In order to reduce the damage from natural earth-quakes,precaution measures should be designed on the basis of the seismic propagation charac-teristics.Experimental geo… 相似文献
18.
《中国科学:地球科学(英文版)》2015,(10)
This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-resolution field emission SEM allows observation and investigation of a very fine micro area in situ.Using low-vacuum mode SEM,geological insulating samples can be analyzed directly without coating,demonstrating the wide application prospect.Combined with backscatter detector(BSE),energy dispersal X-ray spectroscopy(EDS),cathodoluminescence spectrometry(CL),and electron back-scattering diffraction(EBSD),SEM can yield multiple types of information about geological samples at the same time,such as superficial microstructure,CL analysis,BSE image,component analysis,and crystal structure features.In this paper,we use examples to discuss the geological application of SEM.We stress that we should not only focus on the CL image analysis,but strengthen CL spectrum analyses of minerals.These results will effectively reveal the mineral crystal lattice defects and trace element composition and can help to reconstruct mineral growth conditions precisely. 相似文献
19.
A semi-analytical time integration method is proposed for the numerical simulation of transient groundwater flow in unconfined aquifers by the nonlinear Boussinesq equation. The method is based on the analytical solution of the system of ordinary differential equations with constant coefficients. While it is unconditionally stable and more accurate than the finite difference methods, the computational cost is much more expensive than (can be more than 10 times) that of the finite difference methods for a single time step. However, by partitioning the nonlinear parameters into linear and nonlinear parts, the costly computation can be performed only once. With larger and less variable time step sizes, the total computational cost can be significantly reduced. Three examples are included to illustrate the advantages and limitations of the proposed method. 相似文献
20.
三维土-结构动力相互作用的一种时域直接分析方法 总被引：1，自引：0，他引：1
本文提出了一种分析三维土-结构动力相互作用的时域直接方法。该方法采用集中质量显式有限元和透射人工边界模拟无限域地基,通过编制的FORTRAN程序实现;采用ANSYS软件对上部结构进行建模分析,并通过FORTRAN程序对ANSYS软件的调用,实现了土与结构系统在地震作用下的整体分析。该方法为显隐式相结合的方法,地基和上部结构可采用不同的时间步距进行分析,可大大提高效率。通过两算例,验证了该方法的可行性。 相似文献