非线性地球物理反演方法:回顾与展望   总被引：19，自引：13，他引：19  

杨文采 《地球物理学进展》2002,17(2):255-261

自20世纪90年代以来，非线性地球物理反演方法已走向成熟，这些方法包括线性化迭代法，仿真淬火法，遗传算法及联合反演方法等，线性化迭代反演基于开放物理系统状态发生相变的原理，要进一步改善模型参数化的技术和迭代过程的自组织；仿真淬火法与遗传算法基于自然过程的指数率或生物演化的优生率，可以相互结合以提高解估计的分辨率与置信度；联合反演要结合岩石物理性质的统计规律，才能取得兼容地质与综合方法的应用效果，地球动力学中的反问题不仅涉及偏微分方程系数项的求解，而且涉及初始条件或初始边界的求解，对地球动力学作用过程研究特别重要。  相似文献   

The experimental studies on electrical con-ductivities and P-wave velocities of anortho-site at high pressure and high temperature   总被引：1，自引：0，他引：1  

白利平  杜建国  刘巍  周文戈 《地震学报(英文版)》2002,15(6):667-676

Introduction The measurements of the compressional wave velocity and electrical conductivity of minerals and rocks are of fundamental importance to look into the earths interior, including composition, geotherm, generation and distribution of fluids and melts. Hydrous minerals formed by metamatu-siom are abundant within the earth. Previous studies have been carried out on the dehydration effect on the electrical conductivity and wave velocity of rocks such as serpentine, amphibole, most of whi…  相似文献   

河南豫北地震台网地区波速的探讨     

韩美玲  张炜  郑培玲 《山西地震》2002,(3):5-7,12

为了解决河南豫北地区地震的定位问题 ,对豫北台网内的 10个典型地震 ,使用了 7个地震台站的资料 ,用波速比求出横波速度 ;用和达定位法 (有的同时使用高桥法 )进行了精确定位 ,求出震源深度 ;测量了震中至各台的震中距 ,以此反算出了纵波速度。通过计算 ,确定出了较为适合河南豫北地震台网地区的波速。  相似文献   

帕隆藏布河流纵剖面演化的最小功模式   总被引：3，自引：0，他引：3  

蒋忠信 《山地学报》2002,20(1):26-31

河流地貌最小功原理表明河流纵误时面形态将向力示使流速增大的方向演化，据此推导出矩形流域全程流速的平均值（u^-）与河流纵误时面形态指数（N）的关系式：u^∝-f(N)={1/2-1/[(N 1)(N 2)]}^1/2，f(N)被称为流速函数。这一最小功模式表明河流纵剖面演化方向是N由小变大。以西藏帕隆藏布中上游流域系统、干流全程及Ⅰ级阶地为例，由最小功模式计算的全程流速均值与实测值相吻合，从而检验了上述最小功原理和数学模式。  相似文献   

Active tectonics of the South Caspian Basin   总被引：15，自引：0，他引：15  

James Jackson  Keith Priestley  Mark Allen  Manuel Berberian 《Geophysical Journal International》2002,148(2):214-245

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The effect of scattering in surface wave tomography   总被引：6，自引：1，他引：6  

Jesper Spetzler  Jeannot Trampert  Roel Snieder 《Geophysical Journal International》2002,149(3):755-767

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Monte-Carlo inversion for a global shear-velocity model of the crust and upper mantle   总被引：15，自引：1，他引：15  

N. M. Shapiro  M. H. Ritzwoller 《Geophysical Journal International》2002,151(1):88-105

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Velocity profile of a sand cloud blowing over a gravel surface   总被引：2，自引：0，他引：2  

Zhibao Dong  Hongtao Wang  Xiaoping Liu  Fang Li  Aiguo Zhao 《Geomorphology》2002,45(3-4)

Particle dynamic analyzer (PDA) measurement technology was used to study the turbulent characteristics and the variation with height of the mean horizontal (in the downwind direction) and vertical (in the upward direction) particle velocity of a sand cloud blowing over a gravel surface. The results show that the mean horizontal particle velocity of the cloud increases with height, while the mean vertical velocity decreases with height. The variation of the mean horizontal velocity with height is, to some extent, similar to the wind profile that increases logarithmically with height in the turbulent boundary layer. The variation of the mean vertical velocity with height is much more complex than that of the mean horizontal velocity. The increase of the resultant mean velocity with height can be expressed by a modified power function. Particle turbulence in the downwind direction decreases with height, while that in the vertical direction is complex. For fine sands (0.2–0.3 mm and 0.3–0.4 mm), there is a tendency for the particle turbulence to increase with height. In the very near-surface layer (<4 mm), the movement of blown sand particles is very complex due to the rebound of particles on the bed and the interparticle collisions in the air. Wind starts to accelerate particle movement about 4 mm from the surface. The initial rebound on the bed and the interparticle collisions in the air have a profound effect on particle movement below that height, where particle concentration is very high and wind velocity is very low.  相似文献   

Wind velocity and sand transport on a barchan dune   总被引：2，自引：0，他引：2  

G. Sauermann  J. S. Andrade  Jr.  L. P. Maia  U. M. S. Costa  A. D. Araújo  H. J. Herrmann 《Geomorphology》2003,54(3-4):245-255

We present measurements of wind velocity and sand flux performed on the windward side of a large barchan dune in Jericoacoara, northeastern Brazil. From the measured profile, we calculate the air shear stress using an analytical approximation and treat the problem of flow separation by an heuristic model. We find that the results from this approach agree well with our field data. Moreover, using the calculated shear velocity, we predict the sand flux according to well-known equilibrium relations and with a phenomenological continuum saltation model that includes saturation transients and thus allows for nonequilibrium conditions. Based on the field data and theoretical predicted results, we indicate the principal differences between saturated and nonsaturated sand flux models. Finally, we show that the measured dune moves with invariant shape and predict its velocity from our data and calculations.  相似文献   

饱和土一维简谐响应解析解的求解和应用：II 应用     

杨军  宋二祥  陈肇元 《岩土力学》2003,24(5):710-714

将相关论文[1]中得到的饱和土一维简谐响应解析解，应用到饱和土中两类压缩波的独立作用、饱和土中波的传播速度、u-p方程的适用范围等研究中。在两类压缩波的独立作用研究中，克服了以前文献中的数学不严密性。研究了饱和土各参数对三种体波波速的影响。通过比较u-w和u-p方程的解答，定量地说明了u-p方程的适用范围。  相似文献