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CSAMT自适应正则化一维全资料反演 总被引:2,自引:0,他引:2
相比于传统反演算法对初始模型依赖性强的弱点,自适应正则化对初始模型要求较低,正则化因子可以根据每次迭代的数据目标函数和模型目标函数的关系,快速计算得到.这里采用自适应正则化反演算法尝试对一维全资料CSAMT的层状介质进行反演,通过三层和五层模型及其使用近场视电阻率数据的反演计算,表明了CSAMT自适应正则化一维全资料反演算法稳定,也发现该方法不仅能够避免传统CSAMT近场校正带来的误差,而且由于不用反复搜索正则化因子,加快了迭代收敛速度. 相似文献
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Most of the present earthquake early warning systems are based on broadband or strong motion recordings. How-ever, the short-period instruments are still deployed. It is well-known that short-period recordings have saturation problems for large earthquakes when estimating the size of an earthquake. Thus, it is necessary to make clear the magnitude at which saturation starts to occur for the commonly used τc and Pd measurements, respectively. To investigate the possibility of using short-period seismic recordings for earthquake early warning, we conducted a simulated experiment using the strong motion data of the 1999 Chi-Chi earthquake sequence including its main shock and 31 aftershocks, with magnitude span from 4 to 7.6. The strong motion acceleration recordings were convolved with the instrument response of short-period seismographs in northern China to simulate short-period seismograms. Parameters τc and Pd from the first-three-second seismograms were calculated for the simulated short-period recordings and compared with that obtained by the original strong ground motion recordings. The result showed that to some extent, short-period recordings can be used for threshold earthquake early warning, while the magnitude saturation of Pd estimation can be up to 6.5, better than τc estimation. 相似文献
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首先给出瞬变电磁(TEM)场卷积计算式,并将关断电流变化率函数看成冲击函数,垂直阶跃脉冲激发的场分量看成输入信号,卷积结果就是任意形状关断电流的TEM响应。把电流激发脉冲看成是许多垂直阶跃函数的叠加,通过叠加这些阶跃函数的响应求得任意电流脉冲激发的瞬变电磁响应。当已知TEM场的实测值和关断电流形状,就可按编程的方法计算全期视电阻率。文中给出了2个斜坡关断电流激发的电偶极源TEM垂直磁场算例,一个为均匀半空间的响应及其全期视电阻率,另一个为三层K型地电断面的响应及其全期视电阻率。 相似文献
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现有的地震早期预警系统大多采用宽频带记录或强震记录, 然而很多地震台站仍然使用短周期地震仪. 用短周期地震记录估计大地震震级时会出现饱和的现象早已众所周知. 但需要研究的问题是tau;c和Pd方法估计地震震级时出现饱和的震级到底是多少.为研究使用短周期记录进行地震早期预警的可能性,本文使用1999年集集地震序列的强震数据(包括主震和31次余震)进行模拟实验,所选地震序列的震级在4级到7.6级范围内. 用强震记录与短周期地震仪响应函数的卷积模拟短周期记录,利用其前3秒波形计算参数tau;c和Pd,并与用原始的强地面运动记录计算得到的结果进行比较. 结果表明, 在一定程度上,短周期地震记录仍可用作地震的早期阈值预警,并且Pd方法直到6.5级才出现饱和,好于tau;c方法. 相似文献
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