高密度电阻率成像

介绍了高密度电阻率法的概念及该方法的工作特点，重点介绍了对阵列数据进行电阻率成像的佐迪法和2D积分法．并利用数值模拟结果及研究实例证实，两种成像方法均为可行的高密度电阻率成像方法．     

地电阻率的多年动态和中期异常判定方法的优化研究

叙述了地电阻率变化的主要影响因素和多年动态变化特征。根据地电阻率中期异常标志，研制了提取地电阻率强震中期异常的3种数学处理方法，对其方法的特点做了简要分析。以河北张北6．2级地震为例，应用所述3种方法，对河北昌黎台北南道地电阻率作了计算。结果表明，不同分析方法所得出的异常，彼此之间有较强的可比性，似可为地震综合预报提供一套有效的强震中期异常判定方法。     

地电阻率各向异性参量计算法及地震前兆实例

讨论了有效电阻率椭圆及各向异性奇象现象．对任意夹角三道测线或相互垂直二道测线并增测横向有效电阻率的二种情况，分别给出了定量计算地电阻率各向异性参量的方法，即求最小电阻率1主轴方位角，平均电阻率(13)1/2，(23)1/2及各向异性系数=(2/1)1/2的方法．作为实例对大同台的资料进行了处理，结合原地电阻率剪切实验结果，得出在1989年10月19日大同6.1级地震前后，震中附近大同、阳原二台NE向地电阻率异常上升，NW道异常下降系介质受到纯剪切所致．其最大主应力方向为北东，与地震断层走向夹锐角．断层面上的剪应力较大，正应力甚小，断层易于滑动，故地震的震级并不特别大．震前与震时介质应力状态相同，故地电阻率前兆与同震变化符号一致．      

电流线追踪电位电阻率层析成像方法初探

电阻率层析成像技术尽管已有了一些比较好的结果，但从国内外发表的文章可以看出，基本上采用的都是有限元方法，而电阻率层析成像的核心问题也就是雅可比矩阵的求取问题。有限元方法能够很好地实现该问题的求解，但需要的计算机内存及计算时间相当的大，为此我们类比地震学中走时射线追踪技术，开展了电流线追踪电位电阻率层析成像方法研究。     

裂隙非均匀分布岩石中的电位及视电阻率计算

计算了在均匀高阻介质中含有低阻裂隙的岩石的电场分布，并由此推导出裂隙非均匀分布的岩石中视电阻率的计算公式．结果表明，裂隙的埋深、规模、走向（平行或垂直视电阻率测线）以及真电阻率等，对视电阻率的观测和计算结果都有不同程度的影响．本文结果对视电阻率法用于地震分析预报提供了一种有效的计算方法．      

地电阻率短临前兆异常的判定方法研究

本文用一阶差分和相干加权计算等方法对地电阻率观测资料进行处理，其结果较好地突出了短临前兆异常。进而研究了地电阻率短临前兆变化特征及其短临预报指标；采用归一化方法将电阻率各异常参量转换为地震前兆信息量，为多种前兆方法进行综合跟踪预报提供了必要的基础资料。     

高密度电阻率法在城市活断层调查中的应用

目的 在城市活断层调查中应用高密度电阻率层析成像测量方法。资料和方法 利用电阻率层析成像测量方法，在北京某地的活断层、郑州老鸦陈断层、安阳南断裂等处理进行了地震活断层调查，采用正、反演处理软件进行资料处理和解释。结果 取得了较理想的勘探效果。结论 在城市活断层调查中，电阻率层析成像测量方法是一种十分有效的勘探方法。     

用正向供电技术提高视电阻率观测精度

定量地实验研究了在采用不同观测方法时相同干扰对视电阻率测量的影响。结果表明，采用正反向供电方法可大幅度提高视电阻率的观测精度。同时还在ＺＤ８地电仪上实现了这种观测方法，试验结果与理论推算值基本相符。     

用正向供电技术提高视电阻率观测精度

定量地实验研究了在采用不同观测方法相同干扰对视电阻率测量的影响。结果表明，采用正反向供电方法可大幅度提高视电阻率的观测测精度。同时还在ＺＤ８地电仪上实现了这种观测方法，试验结果与理论推算值基本相符。     

高密度电阻率法在隐伏断层探测中的应用

以实例说明高密度电阻率法在隐伏断层探测中的成功应用；讨论了用高密度电阻率法反演结果的地质解译方法；提出用高密度电阻率法探测隐伏断层的野外工作设想，对“十五”重大项目——城市活断层探测极具参考意义。     

建筑抗震实时混合试验时滞补偿方法研究综述

时滞补偿是建筑抗震实时混合试验的重要问题。文章对时滞补偿方法的研究进行总结,将时滞补偿方法分为基于时间的位移预测时滞补偿方法、基于反馈力的位移预测时滞补偿方法、基于加载系统模型求逆的时滞补偿方法、基于控制理论的时滞补偿方法和基于集成理念的综合补偿方法。     

Numerical approaches to solid-state convection in planetary bodies

Numerical methods suitable for the calculation of finite-amplitude thermal convection in planetary interiors are reviewed. Three methods of approach are described and compared; namely, finite-difference, finite-element and spectral procedures. Application of each approach to three-dimensional solid-state convection with complex rheology is examined. Finite-difference methods have enjoyed some success to date. However, future developments are likely to favor finite-element methods when rheology and boundaries are complex, and spectral methods when accuracy is paramount and rheology and boundaries are simple.     

小波分析在结构损伤识别中的应用

为提高结构损伤识别方法的准确性和适用性,将小波分析引入到结构损伤识别中。本文首先介绍了小波分析的基本原理,然后详细论述了小波分析用于结构损伤识别的三种方法:基于时域响应的方法、基于空间域响应的方法和小波分析与其他方法联合使用,接着分析了各种方法的应用现状、适用范围和存在的问题。通过比较可以看出小波分析用于结构损伤识别有着广阔的应用前景,本文最后针对进一步研究的方向提出了五点建议。     

横波技术在工程物探中的应用

概述了横波勘探的方法技术及应用范围，指出了横波勘探在工程地震和工程物探工作中的重要性，根据实际工作需要，对某些方法所存在的问题提出了改进措施。介绍了几种方法的应用实例，实际应用效果显示该方法是比较实用的。     

Adaptive split-operator methods for modeling transport phenomena in porous medium systems

Split-operator methods are commonly used to approximate environmental models. These methods facilitate the tailoring of different approximation approaches to different portions of the differential operator and provide a means to split large coupled problems into pieces that are more amenable to parallel computation than the original fully-coupled problem. However, split-operator methods introduce an additional source of approximation error into the solution, which is typically either ignored or controlled heuristically. In this work, we develop two methods to estimate and control the error in split-operator methods, which lead to a dynamic adjustment of the temporal splitting step based upon the error estimators. The proposed methods are shown to yield robust solutions that provide the desired control of error. In addition, for a typical nonlinear reaction problem, the new methods are shown to reduce the solution error by more than two orders of magnitude compared to standard methods for an identical level of computational effort. The algorithms introduced and evaluated have widespread applicability in environmental modeling.     

SELECTION OF SUITABLE METHODS FOR TERRAIN MODELLING FOR RIVER ENGINEERING

LINTRODUCTIONTerrainmodellingisatermtodescribetheprocessofrepresentingthesurfaceoftheEarth.Mathemahcally,theproblemcanbedescribedas;Givenasetofn(3sn相似文献   

A Review Of Environmental Applications Of Quasi-Stationary Electromagnetic Techniques

Electromagnetic (EM) techniques are the most commonly used geophysical methods in mineral exploration. However, the use of EM measurements for environmental and engineering applications like the detection of contaminant plumes or the exploration of waste sites is relatively new.The reason for the success of the application of EM methods to environmental problems lies in the variation of conductivity caused by different geometry of pore fluids and clay contents in rocks, and by the presence of organic and inorganic contaminants.Many EM methods/instruments used for mapping near surface geology exist and nowadays they play a central role in environmental geophysics. In general, these methods can be classified in two blocks: EM methods using a plane wave source of excitation and EM methods using a controlled source like a magnetic dipole or a loop source. The Very Low Frequency (VLF, VLF-R) and Radiomagnetotelluric (RMT) methods are chosen as representative methods for plane wave techniques, while horizontal loop EM methods operating in low induction numbers (EM31, EM34) and Transient Electromagnetic methods (TEM) are chosen as representatives of magnetic dipole or loop source techniques. Basic principles, advantages and disadvantages of each technique as well as their connection to specific environmental problems will be discussed.Different successful applications of these methods are reported in the literature. However, this review will focus on three major subjects: waste site exploration, detection of contaminated earth layers, and groundwater exploration. Case histories are presented illustrating the suitability of EM methods for solving such problems.     

医学图像配准综述

医学领域,医生需要比较不同的解剖影像信息和功能影像信息。将对应于同一物体的不同影像的像素点对应起来就是医学图像配准的主要任务。鉴于需要配准的图像的采集的方法和时间等方面不同,配准所采用的方法也不同。本文介绍了医学图像配准的新近方法。首先从图像配准的任务出发,介绍了配准过程的主要涉及的方面和配准流程。然后从配准时变换的参数角度考虑,将图像的配准分成两大类考虑:参数配准和非参数配准。每一类中给出基本的配准方法,并讨论其用法和特点。对参数配准,主要讨论它们各自不同的方法和适合处理的图像对;对非参数配准,侧重于考虑控制方程的由来和整体外力的计算。     

结构损伤识别方法研究综述

对工程结构进行损伤识别与检测,可以发现结构损伤位置,评估损伤程度,为结构加固与修复提供依据,从而保证工程结构正常运行,进而保护人们生命财产安全,因此结构损伤识别方法研究一直是土木工程领域重要研究课题。结构损伤识别方法总体上分为确定性方法和不确定性方法,相比于确定性方法,不确定性方法考虑了识别过程中不确定因素的影响,成为目前损伤识别领域的研究热点。本文回顾了确定性方法和不确定性方法发展历程,阐述了几种常见的损伤识别方法及其优缺点,并根据国内外研究现状对结构损伤识别方法发展进行了展望,可供损伤识别方法研究与应用参考。     

Accuracy‐constrained optimisation methods for staggered‐grid elastic wave modelling

The classical finite‐difference methods for seismic wave modelling are very accurate at low wavenumbers but suffer from inaccuracies at high wavenumbers, particularly at Nyquist wavenumber. In contrast, the optimisation finite‐difference methods reduce inaccuracies at high wavenumbers but suffer from inaccuracies at low wavenumbers, particularly at zero wavenumber when the operator length is not long and the whole range of wavenumbers is considered. Inaccuracy at zero wavenumber means that the optimisation methods only have a zeroth‐order accuracy of truncation and thus are not rigorously convergent. To guarantee the rigorous convergence of the optimisation methods, we have developed accuracy‐constrained optimisation methods. Different‐order accuracy‐constrained optimisation methods are presented. These methods not only guarantee the rigorous convergence but also reduce inaccuracies at low wavenumbers. Accuracy‐constrained optimisation methods are applied to staggered‐grid elastic wave modelling.