Seismic Design of Symmetric Structures for Accidental Torsion

The paper presents an analytical estimation of the dynamic effects, caused by the shifting of the centre of mass with accidental eccentricity in symmetric structures. The approximate analytical solution proves, that even under small accidental eccentricities the symmetric structures exhibit “irregular behaviour” and the accidental torsional effects cannot be described properly by static application of torsional moments. The prescribed application rule by Eurocode 8 for multimodal analysis underestimates the accidental torsional effects up to 21% for 5% eccentricity for the structures considered in the paper. An expression for the correction of member responses is derived. It is proved by numerical simulations of the dynamic response of three-dimensional models of symmetric structures, that the proposed correction coefficient gives accurate results in cases of single-storey and multi-storey structures. It gives a convenient way for the design practice to estimate accurately the accidental torsional effects on planar and 3-D models of symmetric structures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of causal and acausal filters on elastic and inelastic response spectra

With increasing interest in displacement spectra and long‐period motions, it is important to check the sensitivity of both elastic and inelastic response spectra to the filtering that is often necessary to remove long period artifacts, even from many modern digital recordings. Using two records of very different character from the M=7.1, 1999 Hector Mine, California, earthquake, we find that the response spectra can be sensitive to the corner periods used in causal filtering, even for oscillator periods much less than the filter corner periods. The effect is most pronounced for inelastic response spectra, where the ratio of response spectra computed from accelerations filtered at 25 and 200 sec can be close to a factor of 2 for oscillator periods less than 5 sec. Published in 2003 by John Wiley Sons, Ltd.     

磁通门磁变仪状态函数的测定与记录的校正计算

对磁通门磁变仪状态函数的测定方法进行了研究，提出了磁通门磁变仪标度值——状态函数的测定和磁通门磁变仪记录的校正计算方法。     

Multiplet relative location approach and waveform correlation correction and their application

Introduction When the distribution of a cluster of earthquakes is concentrated, distance between hypocen-ters is much smaller than the event-station distance and than the scale length of the velocity het-erogeneity in the hypocenter region; in this case, the ray path from each hypocenter to a common station will be almost the same. The relative location method can be applied to accurate location of the cluster in the above case. In this approach, the relative location is calculated with the ar…     

实时洪水预报综合修正方法初探

利用误差的相似性扩大实时修正信息量,结合神经网络异联想记忆技术,提出了综合实时修正方法。并在七里街流域用11场洪水分别采用自回归(AR)模型和综合修正方法进行实时修正。分析结果表明,采用综合修正方法既能获得比AR模型更好的精度,又不损失洪水预报的预见期。进一步对闽江的6个支流流域近50场洪水进行综合修正方法实时修正检验,都获得了较好的结果。     

叠后地震记录分频去噪

主要叙述了叠后地震记录分频去噪方法原理。该方法可对叠后各时间场道集记录进行分频谱白化与一致性校正迭加，消除由于地表激发，接收不一致，倾角及表层因素引起的剩余时差和噪音对记录的影响，从而提高地震记录的信噪比和分辨率。通过对实际资料处理，应用效果明显。     

冀北坳陷大地电磁测深研究

根据冀北坳陷化皮-翟杖子剖面大地电磁测深结果。划分了具有不同电性特征的地层沿剖面的变化格局，确定了基底起伏形态，推断了断层分布位置，沿剖面分布有3个隐伏局部构造，分别为瀑河构造，塔子山构造和翟杖子构造，其中瀑河构造和翟杖子构造具有油气过错景，党坝-小寺沟断裂和双洞南断为构造控制断裂，将剖面分为3个断陷区，北店-抬头山断裂为一条较大的西倾逆断裂，常州沟组逆冲超覆在雾迷山组之上，断距近4000m。     

CSAMT在陕西凤太地区寻找隐伏金属矿上的应用

文章介绍了可控源音频大地电磁法（CSAMT）在陕西凤（县）太（白）地区寻找隐伏金属矿上的应用效果。首无在已在地质剖面上进行了方法的有效性研究，确定合理的数据处理解释方法，认识矿体与CSAMT异常的对应规律，进而根据区域地质背景，成矿条件，在确定了勘探区后， 开展了CSAMT的探测研究。通过对CSAMT资料的数据处理，定性，定量解释和地质推断，圈定出有望的隐伏矿体异常及位置。     

黑河流域TM/ETM+影像数字镶嵌图的制作与应用研究

对研究区内两个时期(1986-1990年和1999-2000年)20景Landsat TM5或Landsat ETM7影像图进行多波段合成、色彩优化、几何配准和数字镶嵌等预处理工作,生成试验区两个时期的TM/ETM+影像数字镶嵌图,并利用均方根(Root mean square, RMS)误差法评价几何配准的精度,用采样法评价数字镶嵌的精度. 结果表明,单景TM/ETM+影像图几何配准的精度可以控制在1个像元以内. 多景数字镶嵌时多数点的RMS误差小于2个像元,总的RMS误差在1.3～1.5之间. 利用影像图作为几何配准的数据源的方法要优于利用地形图作为几何配准的数据源的方法.     

频域波动方程的多重网格法

针对差分法求解过程中细网格计算所需时间和空间要求高以及在粗网格上计算又达不到所要求的精度等问题，利用粗网格上的残差校正特性消除迭代误差的低频分量，同时利用细网格上的松弛光滑特性消除迭代误差的高频分量，采用不同疏密的网格距消除不同频率范围内的误差分量，将多重网格方法成功应用于频域波动方程的求解，并给出了实际算例。算例中，分别用Gauss-Seidel迭代法和多重网格法求其数值解，并绘出效果图；比较得出多重网格方法具有精度高、收敛速度快和易于实现的特性，更适合于高维波动问题的求解。