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The moment tensors of these earthquakes as function of time were obtained by the technique of moment tensor inversion in frequency domain.




 To separate the electroencephalogram (EEG) measured on the scalp into the parts generated by deep and shallow electrical sources respectively is a subject of importance both theoretically and clinically, because we can then find in more detail the electrical activities in the deep parts of the brian. Based on the analysis of the spatial frequency of EEG measured by a set of electrodes distributed on the scalp, a method is proposed to solve this problem, which includes two steps. For the first step, the shallow... To separate the electroencephalogram (EEG) measured on the scalp into the parts generated by deep and shallow electrical sources respectively is a subject of importance both theoretically and clinically, because we can then find in more detail the electrical activities in the deep parts of the brian. Based on the analysis of the spatial frequency of EEG measured by a set of electrodes distributed on the scalp, a method is proposed to solve this problem, which includes two steps. For the first step, the shallow dipoles are localized by the higher spatial frequency components and for this purpose, a frequency domain Marquardt algorithm is derived. Then, in the second step, the parts of electrical activities contributed by the deeply located dipoles are revealed after subtraction of the parts of EEG generated by shallow dipoles from the measured EEG. comjputer simulations show that the localization of shallow dipoles by inversion in frequency domain with higher frequency components are quite accurate, and thus the potentials generated by deep and shallow dipoles can be separated effectively.  从头皮测到的脑电信号中把由深层源和浅层源产生的部分分离开，并根据深层源产生的部分观察大脑内部深层的电活动细节，在理论和临床上都有重要意义。通过分析比较深、浅脑电偶极子在头皮一组电极上所产生脑电的空间频率，提出了利用脑电的空间高频分量定位浅层源，进而把浅层源产生的电位从脑电中分离出去的方法，并且将Ｍａｒ－ｑｕａｒｄｔ优化算法由空域推广到了空间频率域。仿真实验表明利用高频分量在空频域求逆可以较准确地定位浅层源，从而有效地把浅层源和深层源的贡献区分开来。  An earthquake of M S=6.9 occurred in Gonghe County, Qinghai Province, China on April 26, 1990.This earthquake was followed by three larger aftershocks of M S=5.5 on May 7, 1990, M S=6.0 on Jan.3, 1994, and M S=5.7 on Feb.16, 1994, consecutively. The moment tensors of these earthquakes as function of time were obtained by the technique of moment tensor inversion in frequency domain . The results inverted indicate that these earthquakes had a very similar focal mechanism of predominantly... An earthquake of M S=6.9 occurred in Gonghe County, Qinghai Province, China on April 26, 1990.This earthquake was followed by three larger aftershocks of M S=5.5 on May 7, 1990, M S=6.0 on Jan.3, 1994, and M S=5.7 on Feb.16, 1994, consecutively. The moment tensors of these earthquakes as function of time were obtained by the technique of moment tensor inversion in frequency domain . The results inverted indicate that these earthquakes had a very similar focal mechanism of predominantly reverse faulting on a plane striking NWW, dipping to SSW.The scalar seismic moments of these earthquakes are M 0=9.4×10 18 Nm for the M S=6.9 event, 8.0×10 16 Nm for the M S=5.5 event, 4.9×10 17 Nm for the M S =6.0 event and 2.9×10 17 Nm for the M S=5.7 event, respectively. The results inverted also show that the source processes of these events were significantly different. The main shock had a very complex process, consisting of two distinct sub events with comparable sizes. The first sub event occurred in the first 12s, having a seismic moment of 4.7×10 18 Nm, and the second one continued from 31s to 41s, having a seismic moment of 2.5×10 18 Nm. In addition, a much smaller sub event, having a seismic moment of about 2.1×10 18 Nm, may exist in the interval of 12 s and 31 s, In contrast, the source processes of the three aftershocks are quite simple. The source time function of each of aftershocks is a single impulse, suggestting that each of aftershocks consists of a mainly uninterrupted rupture. The rise times and total rupture durations are 4 s and 11 s for the M S=5.5 event, 6 s and 16 s for the M S= 6.0 event and 6 s and 13 s for the M S=5.7 event, respectively.  ＳｏｕｒｃｅｐａｒａｍｅｔｅｒｓｏｆｔｈｅＧｏｎｇｈｅ，ＱｉｎｇｈａｉＰｒｏｖｉｎｃｅ，Ｃｈｉｎａ，ｅａｒｔｈｑｕａｋｅｆｒｏｍｉｎｖｅｒｓｉｏｎｏｆｄｉｇｉｔａｌｂｒｏａｄｂａｎｄｗａｖｅｆｏｒｍｄａｔａＬＩ－ＳＨＥＮＧＸＵ（许立生）ａｎｄＹＵＮ...  A method for the dynamic analysis combined with the parameter inversion is proposed in the paper It is used to analyze the subway's tunnel?soil system A plane isoparameteric element is used to model the tunnel structure At same time, the layer element is used to model the ground soils The dynamic equation system and least square formulas for the parameter inversion in frequency domain are derived It is the results of using a displacement function suited for semi?analysis The numerical results... A method for the dynamic analysis combined with the parameter inversion is proposed in the paper It is used to analyze the subway's tunnel?soil system A plane isoparameteric element is used to model the tunnel structure At same time, the layer element is used to model the ground soils The dynamic equation system and least square formulas for the parameter inversion in frequency domain are derived It is the results of using a displacement function suited for semi?analysis The numerical results of the proposed method are in good agreement with that to the practice results It is good reference for the subway design  由半解析方法研究地铁隧道 地层系统的动力参数优化反演和动力响应分析问题。隧道结构由平面等参单元离散 ,地层由层单元离散 ,采用半解析位移函数导出了相应离散系统的动力方程和频域中的最小二乘优化反演方程 ,由此 ,在给出参数反演的同时 ,给出了系统的动力响应分析。这种基于参数反演而进行的动力分析可以给出与实际相符的合理结果 ,对地铁系统的设计有一定的实用价值   << 更多相关文摘 
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