关于层状介质视电阻率响应系数的研究

本文从水平层状介质的电法理论出发,定义了电性层的响应系数S_i,并指出:S_i代表各层电阻率的变化对△ρs/ρs贡献的“权”,同时还给出了二层、三层和深埋电极时S_i的计算公式和部分计算结果,着重讨论了电性结构对表层响应系数S_1和底层响应系数S_n的影响。最后以此理论讨论了九个地电台站的具体情况。根据理论和实际资料的分析,得出以下几点结论: 1)从电性上,台址最佳观测条件是:表层响应系数S_1=0;底层响应系数S_n=1。2)台址的表层电阻率ρ_1高一些,底层电阻率ρ_3低一点,比较接近最佳观测条件。但各层电阻率之间的搭配关系需有一定范围,过高或过低的值都会偏离最佳观测条件。3)仅仅以电性剖面类型区分台址电性条件的优劣是不完善的,最好通过具体计算S_1来评判。     

湿热老化后膨胀型钢结构防火涂层导热系数数值计算

通过对已有多孔材料导热系数计算模型的总结和分析,提出了湿热老化后膨胀型钢结构防火涂层导热系数的计算模型。为考察该模型的计算精度,进行了湿热老化试验及隔热性能试验,测量涂层膨胀倍率、炭化层泡孔尺寸和钢板温度等数据。结果显示,湿热老化后炭化层泡孔尺寸增大导致涂层导热系数增大,隔热性能下降,钢板温度上升。利用本文试验测量数据（泡孔尺寸）计算炭化层导热系数,再根据炭化层导热系数的数值计算结果分析钢板温度,并将钢板温度的计算结果与试验结果进行对比,两者吻合良好,验证了膨胀型防火涂层导热系数计算模型的适用性。     

基于Boltzmann机的矿产靶区预测

矿产靶区预测是一种从统计单元集合中识别找矿靶区的非线性模式识别过程,可以利用Boltzmann机能够对外部刺激进行编码和重建的功能,实现基于Boltzmann机的矿产靶区非线性统计预测过程.鉴于此,笔者定义了面向矿产靶区预测的三层Boltzmann机模型,模型输入层神经元数目等于找矿证据数目,输出层只有一个神经元,隐藏层神经元数目由用户根据矿产靶区预测的精度要求确定;模型应用Hebbian编码和模拟退火算法相结合的随机学习算法进行训练,根据学习训练后模型输入层与隐藏层神经元之间的连接权确定找矿证据的权系数;根据证据权系数和统计单元证据组合特征计算单元成矿有利度,圈定找矿靶区.在GDAL数字图像输入输出函数库基础上,用VC++语言开发了面向栅格数据的矿产靶区预测Boltzmann机算法程序并应用于新疆阿勒泰地区的矿产靶区预测研究.结果表明,Boltzmann机模型预测的统计单元成矿有利度能够正确反映研究区已知矿床(点)的空间分布规律,因此,基于Boltzmann机的矿产靶区非线性统计预测模型是有效的.     

大高宽比隔震结构地震反应的实用分析方法

本文提出了高层隔震结构等大高宽比隔震结构体系地震反应分析的单质点、2质点和3质点剪切型简化计算模型,同时还提出了高宽比影响系数的概念和计算式。这种纯剪切的简化计算模型成功地模拟了剪切加转动多质点计算模型的动力特性,通过高宽比影响系数对剪切型计算模型得到的剪力系数进行非线性放大,使数十质点的隔震结构体系都能够简化成单质点、2质点和3质点体系进行地震反应分析。文末对22层高宽比为5．01的某22层隔震结构进行了算例分析,简化计算理论的计算结果和时程分析法计算结果一致性良好。     

基于ADCIGS预测地层孔隙压力的方法研究

工业界计算孔隙压力系数普遍应用的Eaton和Fillippone方法都需要构建能够准确表征低速层的层速度模型,层速度模型精度及效率成为制约孔隙压力预测的关键参数,但目前工业界层速度建模的精度及效率很难满足孔隙压力预测的要求.本文由正常压实情况下的背景速度场出发,基于时距曲线公式及角道集抽取公式,创新推导了以角度域共成像点道集(ADCIGS)剩余曲率为自变量的孔隙压力系数计算公式,该公式完全由去噪后的地震数据进行驱动,不需要构建层速度模型,该方法大幅提高了计算孔隙压力系数的效率.由模型测试及实际数据应用证明,利用本文提出方法进行孔隙压力预测是有效可行的,该方法可以有效提高预测孔隙压力精度,还可以有效提高预测孔隙压力效率.     

基础隔震结构在竖向荷载作用下的内力分布特点

以一个3跨4排柱建筑为例,对非隔震结构和隔震结构在竖向荷载作用下的内力分布特点进行了对比研究,其中考虑了隔震层顶部梁板结构的荷载、刚度以及结构的梁柱刚度比等因素的影响.研究中发现,与非隔震结构相比,隔震结构一层柱子的柱端弯矩明显增大,隔震层顶部梁的梁端弯矩与其倚载成正比等规律.同时提出了基于非隔震结构的隔震结构在竖向荷载作用下内力的计算方法和“隔震影响系数”的概念.即,隔震结构的内力等于非隔震结构的内力乘以“隔震影响系数”.其中还进一步对“隔震影响系数”的影响因素进行了定量研究,得出了“隔震影响系数”的计算公式.本文所提出的计算方法与隔震结构在水平地震荷载作用下的内力计算方法思路一致,因此,该方法也进一步完善了隔震结构的设计理论.     

电磁辐射异常分析方法研究

利用河北省电磁台网１９８８～１９９２年的观测资料，对不同台站不同方向的异常映震能力进行了分析研究。并运用信息论方法计算了各台信息水平作为其信息可信度的权系数，对各台资料采用加权平均的方法进行了合成处理，发现比平时采用的等权平均效果要好。同时对其异常频次的累加合成对应地震的异常特征进行了初步的探讨     

利用卫星重力数据计算地球内部密度异常

地球外部重力场是由地球内部物质分布决定的。本文利用ＲＡＰＰ８１１８０阶卫星重力位系数根据异常源埋深与重力位系数阶数的关系和重力场分离方法计算了经度为９０°Ｅ的地球密度异常剖面，得到了地球内部不同深度的密度异常结果，并初步作了地球物理解释．计算结果得到的深度为６５ｋｍ处的低密度异常带与地球模型的ＬＩＤ层和Ｃ层较为接近。     

基于能量被动耗能结构抗震设计方法的研究

将结构前两阶振型各自等效为单自由度,采用模态pushover分析确定各等效单自由度的屈服强度系数和延性系数,然后由反应谱计算各阶振型耗散能量需求,利用各振型能量分布曲线,求得各层耗散能量需求,叠加得到各层地震总能量需求,据此确定耗能装置的类型及设计参数.运用该方法对9层钢框架进行了设计,并通过非线性动力分析进行了验证,结果表明该方法精确度符合实际工程需求.     

数字强震记录“精确”插值、积分和微分的权函数算法——I.时域离散序列数值分析方法与应用研究

现有强震记录常规处理程度中采用的插值、积分、微分运算方法计算简单、省时,但在某些情况下,不能确保所要求的计算精度,针对这一问题,本文假定强震记录是理想的有限长记录并满足采定理,在此基础上提出了对强震记录进行“精确”插值,积分和微分运算以及权函数的概念,并推导建立了相应的计算公式,理论和算例分析表明：（１）本文算法中使用的插值,积分和微分运算权函数均具有不变和快速收敛的性质;（２）只需要少量的权系数,本文算法就能获得足够的计算精度;（３）选取足够多的权系数,本文算法能以任意精度副近真实的精确解序列,（４）本文算法可以成为强震数据处理和相关结构动力分析的基础。     

INDUCED POLARIZATION RESPONSE OF A HORIZONTALLY MULTILAYERED EARTH WITH NO RESISTIVITY CONTRAST*

The induced polarization response of a horizontally multilayered earth with no resistivity contrast can rapidly be calculated on a desk calculator or minicomputer for any electrode array. The formulation is a simple series summation of the products of weighting coefficients and the true induced polarization responses for each of the layers. The coefficients are directly derivable from the corresponding resistivity model. This series approach to IP formulation was originally described by Seigel but has not been treated extensively in the present-day geophysical literature. This method can be applied to either time or frequency domain induced polarization measurements. Once the coefficients are known, apparent induced polarization response can readily be obtained by judicious substitution of known, suspected, or assumed values of the true induced polarization of each layer. Basic formulation is presented for the IP potential coefficients (pole-pole or two array) with no resistivity contrast between the layers. From these coefficients, response of any number of layers for any electrode array can be obtained by suitable differentiation. Some examples of Wenner array for a three-layered earth and dipole-dipole array for a four-layered earth are used to illustrate the application. The results of this technique are valid for many natural situations of modest resistivity contrast. However, they definitely cannot be used if there are highly contrasting resistivity layers present. Such an approach is conceptually simple and is useful for survey planning, checking or setting the “depth-of-penetration”of a given array. For field induced polarization data that fits reasonably well to the no-resistivity-contrast model, this simple approach facilitates quantitative interpretation.     

ON THE TRANSFORMATION OF DIPOLE TO SCHLUMBERGER SOUNDING CURVES *

A method is described to transform a dipole sounding curve, obtained with any one of the common dipole arrays over a horizontally layered earth, to the form of a Schlumberger sounding curve. Starting from the general expression which relates the dipole apparent resistivity to the Schlumberger apparent resistivity and its derivative with respect to the spacing, it is possible with some approximations to derive an easy numerical computation procedure in order to perform the transformation. The applicability of the method is discussed briefly.     

THE DETERMINATION OF FILTER COEFFICIENTS FOR THE COMPUTATION OF STANDARD CURVES FOR DIPOLE RESISTIVITY SOUNDING OVER LAYERED EARTH BY LINEAR DIGITAL FILTERING *

The technique of linear digital filtering developed for the computation of standard curves for conventional resistivity and electromagnetic depth soundings is applied to the determination of filter coefficients for the computation of dipole curves from the resistivity transform function by convolution. In designing the filter function from which the coefficients are derived, a sampling interval shorter than the one used in the earlier work on resistivity sounding is found to be necessary. The performance of the filter sets is tested and found to be highly accurate. The method is also simple and very fast in application.     

地电阻率年变化的一种物理解释——大柏舍台不同极距地电阻率观测结果

本文通过河北省隆尧县大柏舍地电台不同供电极距试验观测资料,与地下潜水水位动态的相关分析及数学模型计算结果,给出地电阻率年变化的一种物理解释,即认为大柏舍台地电阻率年变化是由于供电极距短,勘探深度浅,从而受潜水动态影响的结果。为消除大柏舍台地电阻率年变化,应采用不小于1500米的供电装置。     

A DIGITAL LINEAR FILTER FOR RESISTIVITY SOUNDING WITH A GENERALIZED ELECTRODE ARRAY*

This paper presents a digital linear filter which maps composite resistivity transforms to apparent resistivities for any four—electrode array over a horizontally layered earth. A filter is provided for each of three sampling rates; the choice of filter will depend on resistivity contrasts and computational facilities. Two methods of filter design are compared. The Wiener-Hopf least-squares method is preferable for low sampling rate filters. The Fourier transform method is more successful in producing a filter with a high sampling rate which can handle resistivity contrasts of 100 000: 1.     

COMPARISON OF FIVE LEAST-SQUARES INVERSION TECHNIQUES IN RESISTIVITY SOUNDING*

A brief history of the development of the inverse problem in resistivity sounding is presented with the development of the equations governing the least-squares inverse. Five algorithms for finding the minimum of the least-square problem are described and their speed of convergence is compared on data from two planar earth models. Of the five algorithms studied, the ridge-regression algorithm required the fewest numbers of forward problem evaluations to reach a desired minimum. Solution space statistics, including (1) parameter-standard errors, (2) parameter correlation coefficients, (3) model parameter eigenvectors, and (4) data eigenvectors are discussed. The type of weighting applied to the data affects these statistical parameters. Weighting the data by taking log₁₀ of the observed and calculated values is comparable to weighting by the inverse of a constant data error. The most reliable parameter standard errors are obtained by weighting by the inverse of observed data errors. All other solution statistics, such as dataparameter eigenvector pairs, have more physical significance when inverse data error weighting is used.     

NUMERICAL MODELLING OF STANDARD AND CONTINUOUS VERTICAL ELECTRICAL SOUNDINGS1

Analytical solutions of vertical electrical soundings (VES) have mostly been applied to groundwater exploration and monitoring groundwater quality on terrains of fairly simple geology and geomorphology on which the electrode arrays are symmetrical (e.g. Schlumberger or Wenner configurations). The sounding interpretation assumes flat topography and horizontally stratified layers. Any deviations from these simple situations may be impossible to interpret analytically. The recently developed GEA-58 geoelectrical instrument can make continuous soundings along a profile with any colinear electrode configuration. This paper describes the use of finite-difference and finite-element methods to model complex earth resistivity distributions in 2D, in order to calculate apparent resistivity responses to any colinear current electrode distribution in terrains in which the earth resistivities do not vary along the strike. The numerical model results for simple situations are compared with the analytical solutions. In addition, a pseudo-depth section of apparent resistivities measured in the field with the GEA-58 is compared with the numerical solution of a real complex resistivity distribution along a cross-section. The model results show excellent agreement with the corresponding analytical and experimental data.     

NUMERICAL INTERPRETATION OF RESISTIVITY SOUNDINGS OVER HORIZONTAL BEDS*

The digital computer technique described for interpreting resistivity soundings over a horizontally stratified earth requires two steps. First, the kernel function is evaluated numerically from the inverse Hankel transform of the observed apparent resistivity curve. Special attention is given to the inversion of resistivity data recorded over a section with a resistant basement. The second step consists in the least-squares estimation of layer resistivities and thicknesses from the kernel function. For the case of S or T-equivalent beds only one layer-parameter can be obtained, either the longitudinal conductance, or the transverse resistance respectively. Two examples given in the paper show that a wide tolerance is permitted for Choosing the starting values of the layering parameters in the successive approximation procedure. Another important feature for practical applications is good convergence of the iterations. The method is probably best suited for interpreting profiles of electrical soundings with the purpose of mapping approximately horizontal interfaces at depth.     

非均匀套管井中的过套管电阻率测井响应

套管井壁的电势分布包含了金属套管和地层模型的信息,套管电阻率的变化对过套管电阻率测井有重要影响,本文考虑了套管电阻率的变化对传输线方程系数的影响,给出了非均匀套管壁电势分布的计算方法．利用套管井壁电势分布实现了非均匀套管测井响应的计算,考察了套管电阻率变化对过套管电阻率测井响应的影响,模拟结果表明,套管的变薄或变厚对测井响应均有一定影响,当套管电阻突然变小（套管变厚）或突然变大（套管变薄）时过套管电阻率测井异常发生在套管电阻突变界面附近．模拟结果还显示电极距对测井结果有明显影响．     

视电阻率年变的定量计算

本文定量分析地温、地下水位变化对视电阻率的影响。首先建立与地温、地下水位变化相应的地电断面,这种断面的电性不是分层均匀的,然后用有限单元法计算视电阻率。计算结果表明,对与临沂地电台相近的地电断面,地下水位的变化对视电阻年变的影响大于地温年变的影响,前者约为后者的两倍。基岩对年变大小有强烈的控制作用,基岩浅,年变明显,基岩深,年变大为减弱。