Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in ...Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in this research field. In this article, I have, first, made a brief review on those developments and then introduced and summarized a unified and efficient method, global generalized reflection-transmission (abbreviated to R/T thereafter) matrices method, for synthetic seismograms in multi-layered media with irregular interfaces developed by the author [24~26]. As demonstrated in this article, this method could be regarded as an extension of the generalized R/T coefficients method for the horizontally layered case [2,5] to the layered media with irregularly shaped interfaces by incorporating the T matrices technique [27,28]. Because of the use of a recursive scheme in computing the global generalized R/T matrices, this method is efficient, particularly for the case with a large number of展开更多
Surface wave methods have received much attention due to their efficient, flexible and convenient characteristics. However, there are still critical issues regarding a key step in surface wave inversion. In most exist...Surface wave methods have received much attention due to their efficient, flexible and convenient characteristics. However, there are still critical issues regarding a key step in surface wave inversion. In most existing methods, the number of layers is assumed to be known prior to the process of inversion. However, improper assignment of this parameter leads to erroneous inversion results. A Bayesian nonparametric method for Rayleigh wave inversion is proposed herein to address this problem. In this method, each model class represents a particular number of layers with unknown S-wave velocity and thickness of each layer. As a result, determination of the number of layers is equivalent to selection of the most applicable model class. Regarding each model class, the optimization search of S-wave velocity and thickness of each layer is implemented by using a genetic algorithm. Then, each model class is assessed in view of its efficiency under the Bayesian framework and the most efficient class is selected. Simulated and actual examples verify that the proposed Bayesian nonparametric approach is reliable and efficient for Rayleigh wave inversion, especially for its capability to determine the number of layers.展开更多
A broadband T/R frond-end of active holographic imaging system is presented. Compact autodyne mode circuit structure front-end is adopted to achieve higher signal to noise ratio and higher reliability, which is benefi...A broadband T/R frond-end of active holographic imaging system is presented. Compact autodyne mode circuit structure front-end is adopted to achieve higher signal to noise ratio and higher reliability, which is beneficial to the after-end imagining. The factors that influence the dynamic range and the transverse resolution ratio of holographic imaging system have been analyzed. Wide-band oscillator, wide-band low noise amplifier and the tapered slot antennas are implemented to meet the requirements of the holographic imagining system. According to the measured results, the output power is uniform in the broadband working frequency. The sub-harmonic suppression is better than 25 dBc from the frequency of 28 GHz to 33 GHz. The isolation between antennas channel is greater than 20 dB. The experimental result shows that the performance of the front-end is good enough to meet the needs of active millimeter-wave holographic imaging system.展开更多
7223例份24h DCG检出的3987例份室早中,呈R on T现象者58例。老年性R on T(23例)与对照组(35例)比较,在多发于器质性心脏病、频发于白天及活动状态、发作时室早QRS多宽大畸形,以及多合并有其它室上性心律失常上,两组并无统计学差异(P>...7223例份24h DCG检出的3987例份室早中,呈R on T现象者58例。老年性R on T(23例)与对照组(35例)比较,在多发于器质性心脏病、频发于白天及活动状态、发作时室早QRS多宽大畸形,以及多合并有其它室上性心律失常上,两组并无统计学差异(P>0.05)。两组在DCG上伴随缺血性ST-T改变、持续性室速、传导阻滞、以及普通ECG上QT延长、室/房肥大、异位节律比率上亦无显著差别(P>0.05)。较之对照组,老年性R on T的特征为:男性更多(87%:60%,P<0.05),无痛性发作尤频(95.7%∶65.75%,P<0.01),DGC:室早多呈多源性(78.3%∶45.7%,P<0.05),普通ECG呈缺血性ST-T改变者多(56.2%∶17.1%,P<0.01),电轴显著左偏者多(50%∶20%,P<0.05)。展开更多
文摘Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in this research field. In this article, I have, first, made a brief review on those developments and then introduced and summarized a unified and efficient method, global generalized reflection-transmission (abbreviated to R/T thereafter) matrices method, for synthetic seismograms in multi-layered media with irregular interfaces developed by the author [24~26]. As demonstrated in this article, this method could be regarded as an extension of the generalized R/T coefficients method for the horizontally layered case [2,5] to the layered media with irregularly shaped interfaces by incorporating the T matrices technique [27,28]. Because of the use of a recursive scheme in computing the global generalized R/T matrices, this method is efficient, particularly for the case with a large number of
基金Science and Technology Development Fund of the Macao SAR under research grant SKL-IOTSC-2018-2020the Research Committee of University of Macao under Research Grant MYRG2016-00029-FST。
文摘Surface wave methods have received much attention due to their efficient, flexible and convenient characteristics. However, there are still critical issues regarding a key step in surface wave inversion. In most existing methods, the number of layers is assumed to be known prior to the process of inversion. However, improper assignment of this parameter leads to erroneous inversion results. A Bayesian nonparametric method for Rayleigh wave inversion is proposed herein to address this problem. In this method, each model class represents a particular number of layers with unknown S-wave velocity and thickness of each layer. As a result, determination of the number of layers is equivalent to selection of the most applicable model class. Regarding each model class, the optimization search of S-wave velocity and thickness of each layer is implemented by using a genetic algorithm. Then, each model class is assessed in view of its efficiency under the Bayesian framework and the most efficient class is selected. Simulated and actual examples verify that the proposed Bayesian nonparametric approach is reliable and efficient for Rayleigh wave inversion, especially for its capability to determine the number of layers.
文摘A broadband T/R frond-end of active holographic imaging system is presented. Compact autodyne mode circuit structure front-end is adopted to achieve higher signal to noise ratio and higher reliability, which is beneficial to the after-end imagining. The factors that influence the dynamic range and the transverse resolution ratio of holographic imaging system have been analyzed. Wide-band oscillator, wide-band low noise amplifier and the tapered slot antennas are implemented to meet the requirements of the holographic imagining system. According to the measured results, the output power is uniform in the broadband working frequency. The sub-harmonic suppression is better than 25 dBc from the frequency of 28 GHz to 33 GHz. The isolation between antennas channel is greater than 20 dB. The experimental result shows that the performance of the front-end is good enough to meet the needs of active millimeter-wave holographic imaging system.
文摘7223例份24h DCG检出的3987例份室早中,呈R on T现象者58例。老年性R on T(23例)与对照组(35例)比较,在多发于器质性心脏病、频发于白天及活动状态、发作时室早QRS多宽大畸形,以及多合并有其它室上性心律失常上,两组并无统计学差异(P>0.05)。两组在DCG上伴随缺血性ST-T改变、持续性室速、传导阻滞、以及普通ECG上QT延长、室/房肥大、异位节律比率上亦无显著差别(P>0.05)。较之对照组,老年性R on T的特征为:男性更多(87%:60%,P<0.05),无痛性发作尤频(95.7%∶65.75%,P<0.01),DGC:室早多呈多源性(78.3%∶45.7%,P<0.05),普通ECG呈缺血性ST-T改变者多(56.2%∶17.1%,P<0.01),电轴显著左偏者多(50%∶20%,P<0.05)。
