Interpretation of seismic surface waves in regional networks: joint estimation of wavefield geometry and local phase velocity. Method and numerical tests     

Wolfgang Friederich  Erhard Wielandt 《Geophysical Journal International》1995,120(3):731-744

  相似文献   

Neural network analyses of stress-induced overpressures in the Pannonian Basin   总被引：1，自引：0，他引：1  

R. Van  Balen S. Cloetingh 《Geophysical Journal International》1995,121(2):532-544

  相似文献   

Migmatite structures in the Central Gneiss Complex, Boca de Quadra, Alaska   总被引：3，自引：0，他引：3  

E.L. McLELLAN 《Journal of Metamorphic Geology》1988,6(4):517-542

Abstract Migmatite structures in the Coast Plutonic-Metamorphic Complex are well exposed in the inlet of Boca de Quadra, southeast Alaska. Two types of anatectic migmatites are present. Patch migmatites formed by in situ melting and subsequent crystallization of melt. Diktyonitic migmatites comprise a discontinuous veined network of leucocratic material, in which leucosomes enclose boudins of host rock. The margins of these boudins show the development of both melanosomes and shear band fabrics.
Strain analysis of diktyonitic melanosomes indicates that these regions have undergone volume decreases of 20-27%. This volume decrease is attributed to melt extraction into the adjacent fracture-filling leucosomes. Thus, diktyonitic migmatites formed by shear-induced segregation of partial melt, whereas in patch migmatites the lack of shear stresses inhibited melt segregation. The variable structural style of anatectic migmatites in Boca de Quadra is not related to host-rock composition, but may be due to differences in the amount of differential stress during migmatization. These in turn may be controlled by host-rock strength and/or diachroneity of migmatization and deformation.
Determination of volume changes during migmatization using strain analysis is potentially capable of discriminating intrusive and anatectic migmatites and consequently of documenting melt segregation and subsequent migration across crustal levels.  相似文献   

西北地区地震综合预报判据与指标研究     

李海华  张文孝 《内陆地震》1989,3(1):1-16

本文简述了西北地区各类前兆台网的分布及效能,系统论述了地震综合预报判据与指标的研究现状。主要研究结果是:认为无论是地震活动性异常还是前兆异常均显示出近源异常占优势;通过分析多样和复杂的前兆现象提取了其若干共同特征;结合综合预报判据和指标阐述了跟踪震情不断修正预报意见的思路。  相似文献   

Thrust and nappe tectonics of west Devon     

K.P. Isaac 《Proceedings of the Geologists' Association. Geologists' Association》1985,96(2):109-127

  相似文献   

Model-free estimation of fracture aperture with neural networks     

Marek Kacewicz 《Mathematical Geology》1994,26(8):985-994

The feedforward backpropagation technique provides a model-free estimation with neural networks. The algorithm was used to estimate fracture aperture of natural fractures in three dimensional space. A three-layer neural network with at least 5 nodes in a hidden layer was trained on a data set consisting of formation imaging microscanner logs (FMS)from horizontal boreholes. Sensitivity studies were performed to account for the rate of learning convergence, convergence to local error minima, etc. Among the factors contributing mostly to the overall good or bad performance of the network, the following are worth mentioning: number of data points, data spacing, and data variability. It is shown that a smoothing operation applied to aperture data along the wellbore often helps to reduce disorientation of the network and to switch from oscillations or chaotic jumps to convergence.  相似文献   

盾构施工地面长期沉降的神经网络预测   总被引：1，自引：0，他引：1  

璩继立  峁会勇 《上海国土资源》2004,(3):42-46

基于逆传播人工神经网络方法，建立了盾构施工地面长期沉降的非线性预测模型，建立了沉降与诸多影响因素：所处位置、时间、上覆土性参数及盾构施工参数等的关系模型。通过在上海地铁2号线龙东路一中央公园站区间资料的验证，发现与实际比较吻合。  相似文献   

河网非恒定水沙数学模型研究   总被引：12，自引：0，他引：12       下载免费PDF全文

孙昭华  李义天  曹志芳 《水科学进展》2004,15(2):165-172

建立了能够适用于多种情况的河网非恒定流水沙数学模型。推导提出了河网泥沙方程组的分级解法,提出了适用于河网计算的汊点分沙模式,分析和对比了多种分沙模式的适用性,对河网区域中可蓄水汊点也提出了相应的处理办法。采用汉江杜家台分蓄洪区的资料作了模型的验证和应用。  相似文献   

小波神经网络在基桩动测信号处理中的应用   总被引：1，自引：0，他引：1  

麦榕  贺怀建  潘冬子  黄正华 《水文地质工程地质》2004,31(5):91-96

基于小波变换的时频局部化特性及人工神经网络的非线性映射特性，将小波变换和人工神经网络的优点结合起来，从基桩动测信号二进小波变换的频域中提取特征，最后将这些特征输入人工神经网络进行训练和分类，进而实现基桩缺陷的诊断。数值模拟试验显示了该方法的合理性，在此基础上进行了工程桩的现场试验研究，结果表明训练成功的神经网络可以作为智能分类器对基桩常见缺陷进行识别和诊断。  相似文献   

GA+BP神经网络在薄互层储层预测中的应用   总被引：3，自引：0，他引：3  

刘洪林  胡建  王金山  朱秋影 《物探与化探》2004,28(5):460-462,470

地震信号的特征是由地下岩石、流体的物理特征及其变化直接引起的,有效挖掘隐藏于地震数据中的有关岩性和储层物性信息具有深远而现实的意义。地震属性参数之间多是非线性关系,并且地震属性参数受环境的影响很大。神经网络可以建立属性参数与预测目标之间的高度非线性映射,而遗传算法选择适者生存。改进BP算法,综合BP的快速收敛和GA的全局寻优的特点,具体应用于薄互层储层厚度预测。  相似文献