With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full wavefo...With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full waveform inversion of local and teleseismic data. We also show that focal depths can be well constrained using the depth phase sPL with single broadband seismic station. Our study indicates that the main shock is located at a depth of ii kin, much shallower than those from other studies, confirming that the earthquake occurs in upper crust. Aftershocks are located in the depth range of 11 16 kin, which is consistent with a ruptured near vertical fault whose width is about 10 km, as expected for an Ms6.1 earthquake.展开更多
Radars and their applications were, for a long time, reserved to national defense, air security or weather service domains. For a few years, with the emergence of new technologies, radar applications have been develop...Radars and their applications were, for a long time, reserved to national defense, air security or weather service domains. For a few years, with the emergence of new technologies, radar applications have been developed and have become known in the civil domain. In particular, the arrival of UWB—Ultra-Wideband technology allows the design of compact and low-cost radars with multiple fields of application. In this paper, we focus on road applications, such as driving assistance with the objective of increasing safety and reducing accidents. In classical UWB radar systems, Gaussian and monocycle pulses are commonly used. In previous works, original waveforms based on orthogonal functions (Hermite and Gegenbauer) were proposed. These provide a good spatial resolution, suitable for radar detection. Another advantage of these waveforms is their multiple access capability, due to their orthogonality. The aim of the study presented in this article is to compare simulation and experimental results obtained, especially for short-range anticollision radar application, using these waveforms in one part and Gaussian and monocycle pulses in the other part. The originality of this paper relies on the new approach. Indeed, this comparison study using these waveforms has never been done before. Finally, some examples of real experiments in a real road environment with different waveforms are presented and analysed.展开更多
实际地震波形观测表明,对于大陆结构相对简单的地壳中的地震而言,有一震相出现在P波和S波之间.一般在30～50km附近发育得较好,其能量主要集中在径向分量,而垂向分量的振幅相对径向要小,切向分量上的振幅很弱,且波形以低频为主,通常没有...实际地震波形观测表明,对于大陆结构相对简单的地壳中的地震而言,有一震相出现在P波和S波之间.一般在30～50km附近发育得较好,其能量主要集中在径向分量,而垂向分量的振幅相对径向要小,切向分量上的振幅很弱,且波形以低频为主,通常没有P波尖锐.在利用FK方法计算合成地震图的基础上,发现该震相是由S波入射到自由地表形成水平传播的P波(文献称为surface P wave,自由地表P波)或者包括S波入射到地表后形成的多次P波或其散射震相.由于该震相是由S波和P波之间耦合而形成,本文将其定义为sPL(s coupled into P)震相.理论波形研究表明,sPL相对直达P波的到时差对震中距离不敏感,而随着震源深度的增加几乎呈线性增加,因此可以很好的约束震源深度.本文以2005年江西九江地震为例,证实了sPL确定震源深度的可行性和可靠性.在观测到sPL震相的情况下,离震源50km以内的一个三分量地震台站的波形就可以帮助获得可靠的震源深度,而不需要精确的震中距离.由于sPL震相出现距离较近,对于较小(三级以上)的地震也可以应用,因此在稀疏台网布局情形下sPL对于确定中小地震深度应该具有很好的应用意义.展开更多
GaN MOSFET作为宽禁带的第三代半导体不仅开关速度快而且导通电阻小,把其用于变换器具有一定的高效性,而LLC谐振变换器作为高效的DC-DC变换器一直被广泛关注。现将GaN MOSFET用作全桥LLC谐振变换器的原边开关管进一步提升变换器的效率,...GaN MOSFET作为宽禁带的第三代半导体不仅开关速度快而且导通电阻小,把其用于变换器具有一定的高效性,而LLC谐振变换器作为高效的DC-DC变换器一直被广泛关注。现将GaN MOSFET用作全桥LLC谐振变换器的原边开关管进一步提升变换器的效率,并且通过PFM(变频)控制将变换器的工作频率划分为3个区域,进而找到效率最高的频率点,使变换器以此频率高效运行,文中对全桥LLC谐振变换器进行了参数设计,并基于Plecs和Matlab软件联合仿真验证参数和方案的可行性,搭建硬件平台得到谐振电流、输出电压的实验波形与仿真波形进行对比。实验结果表明,将GaN器件引入全桥LLC谐振变换器后能提高系统的频率及功率密度且最高效率可达96%。展开更多
基金financial supported by Joint Seismological Science Foundation of China (No.200808078)National Natural Science Foundation of China (Nos.40821160549 and 41074032)
文摘With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full waveform inversion of local and teleseismic data. We also show that focal depths can be well constrained using the depth phase sPL with single broadband seismic station. Our study indicates that the main shock is located at a depth of ii kin, much shallower than those from other studies, confirming that the earthquake occurs in upper crust. Aftershocks are located in the depth range of 11 16 kin, which is consistent with a ruptured near vertical fault whose width is about 10 km, as expected for an Ms6.1 earthquake.
文摘Radars and their applications were, for a long time, reserved to national defense, air security or weather service domains. For a few years, with the emergence of new technologies, radar applications have been developed and have become known in the civil domain. In particular, the arrival of UWB—Ultra-Wideband technology allows the design of compact and low-cost radars with multiple fields of application. In this paper, we focus on road applications, such as driving assistance with the objective of increasing safety and reducing accidents. In classical UWB radar systems, Gaussian and monocycle pulses are commonly used. In previous works, original waveforms based on orthogonal functions (Hermite and Gegenbauer) were proposed. These provide a good spatial resolution, suitable for radar detection. Another advantage of these waveforms is their multiple access capability, due to their orthogonality. The aim of the study presented in this article is to compare simulation and experimental results obtained, especially for short-range anticollision radar application, using these waveforms in one part and Gaussian and monocycle pulses in the other part. The originality of this paper relies on the new approach. Indeed, this comparison study using these waveforms has never been done before. Finally, some examples of real experiments in a real road environment with different waveforms are presented and analysed.
文摘实际地震波形观测表明,对于大陆结构相对简单的地壳中的地震而言,有一震相出现在P波和S波之间.一般在30～50km附近发育得较好,其能量主要集中在径向分量,而垂向分量的振幅相对径向要小,切向分量上的振幅很弱,且波形以低频为主,通常没有P波尖锐.在利用FK方法计算合成地震图的基础上,发现该震相是由S波入射到自由地表形成水平传播的P波(文献称为surface P wave,自由地表P波)或者包括S波入射到地表后形成的多次P波或其散射震相.由于该震相是由S波和P波之间耦合而形成,本文将其定义为sPL(s coupled into P)震相.理论波形研究表明,sPL相对直达P波的到时差对震中距离不敏感,而随着震源深度的增加几乎呈线性增加,因此可以很好的约束震源深度.本文以2005年江西九江地震为例,证实了sPL确定震源深度的可行性和可靠性.在观测到sPL震相的情况下,离震源50km以内的一个三分量地震台站的波形就可以帮助获得可靠的震源深度,而不需要精确的震中距离.由于sPL震相出现距离较近,对于较小(三级以上)的地震也可以应用,因此在稀疏台网布局情形下sPL对于确定中小地震深度应该具有很好的应用意义.
