针对直方图方法分选脉间参差雷达信号能力不佳且无法解析其调制模式的问题,结合参差信号的交织特性,提出联合到达时间差值(Difference of Time Of Arrival,DTOA)的一阶差分曲线和相关分析的分选方法.该方法基于DTOA一阶差分曲线提取DTO...针对直方图方法分选脉间参差雷达信号能力不佳且无法解析其调制模式的问题,结合参差信号的交织特性,提出联合到达时间差值(Difference of Time Of Arrival,DTOA)的一阶差分曲线和相关分析的分选方法.该方法基于DTOA一阶差分曲线提取DTOA关注项,然后基于关注项的自相关和交叠率识别参差调制模式、基于关注项的互相关分析参差调制模式,最后结合参差分析结果进行序列检索.实验结果表明,所提方法所需计算量较少,可以有效分选参差信号并解析其完整的调制模式,对脉冲丢失表现出较强的适应性,对子周期分布的均匀程度和干扰脉冲有较好的稳健性.展开更多
We present a finite difference （FD） method for the simulation of seismic wave fields in fractured medium with an irregular （non-fiat） free surface which is beneficial for interpreting exploration data acquired in ...We present a finite difference （FD） method for the simulation of seismic wave fields in fractured medium with an irregular （non-fiat） free surface which is beneficial for interpreting exploration data acquired in mountainous regions. Fractures are introduced through the Coates-Schoenberg approach into the FD scheme which leads to local anisotropic properties of the media where fractures are embedded. To implement surface topography, we take advantage of the boundary-conforming grid and map a rectangular grid onto a curved one. We use a stable and explicit second-order accurate finite difference scheme to discretize the elastic wave equations （in a curvilinear coordinate system） in a 2D heterogeneous transversely isotropic medium with a horizontal axis of symmetry （HTI）. Efficiency tests performed by different numerical experiments clearly illustrate the influence of an irregular free surface on seismic wave propagation in fractured media which may be significant to mountain seismic exploration. The tests also illustrate that the scattered waves induced by the tips of the fracture are re-scattered by the features of the free surface topography. The scattered waves provoked by the topography are re-scattered by the fractures, especially Rayleigh wave scattering whose amplitudes are much larger than others and making it very difficult to identify effective information from the fractures.展开更多
文摘针对直方图方法分选脉间参差雷达信号能力不佳且无法解析其调制模式的问题,结合参差信号的交织特性,提出联合到达时间差值(Difference of Time Of Arrival,DTOA)的一阶差分曲线和相关分析的分选方法.该方法基于DTOA一阶差分曲线提取DTOA关注项,然后基于关注项的自相关和交叠率识别参差调制模式、基于关注项的互相关分析参差调制模式,最后结合参差分析结果进行序列检索.实验结果表明,所提方法所需计算量较少,可以有效分选参差信号并解析其完整的调制模式,对脉冲丢失表现出较强的适应性,对子周期分布的均匀程度和干扰脉冲有较好的稳健性.
基金sponsored by the Knowledge Innovation Program of the Chinese Academy of Sciences No.KZCX2-YW-132)the Important National Science and Technology Specific Projects(No.2008ZX05008-006)the National Natural Science Foundation of China Nos.41074033,40721003,40830315,and 40874041)
文摘We present a finite difference （FD） method for the simulation of seismic wave fields in fractured medium with an irregular （non-fiat） free surface which is beneficial for interpreting exploration data acquired in mountainous regions. Fractures are introduced through the Coates-Schoenberg approach into the FD scheme which leads to local anisotropic properties of the media where fractures are embedded. To implement surface topography, we take advantage of the boundary-conforming grid and map a rectangular grid onto a curved one. We use a stable and explicit second-order accurate finite difference scheme to discretize the elastic wave equations （in a curvilinear coordinate system） in a 2D heterogeneous transversely isotropic medium with a horizontal axis of symmetry （HTI）. Efficiency tests performed by different numerical experiments clearly illustrate the influence of an irregular free surface on seismic wave propagation in fractured media which may be significant to mountain seismic exploration. The tests also illustrate that the scattered waves induced by the tips of the fracture are re-scattered by the features of the free surface topography. The scattered waves provoked by the topography are re-scattered by the fractures, especially Rayleigh wave scattering whose amplitudes are much larger than others and making it very difficult to identify effective information from the fractures.
