Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is diffic...Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution （SPWD） were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals.展开更多
运用平滑伪Wigner-Ville分布提取大脑皮层的稳态视觉诱发电位(steady state visual evoked potential,SSVEP)信号,并作为输入信号应用于脑机接口系统。研究结果表明,该方法不需叠加平均信号就可以提高信噪比,提取出的稳态视觉诱发电位...运用平滑伪Wigner-Ville分布提取大脑皮层的稳态视觉诱发电位(steady state visual evoked potential,SSVEP)信号,并作为输入信号应用于脑机接口系统。研究结果表明,该方法不需叠加平均信号就可以提高信噪比,提取出的稳态视觉诱发电位信号能够准确反映使用者的控制意图,为脑机接口选取特征提供了依据。展开更多
基金supported by National Natural Science Foundation of China(Grant No.40874059)
文摘Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner Ville distribution （SPWD） were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals.
文摘运用平滑伪Wigner-Ville分布提取大脑皮层的稳态视觉诱发电位(steady state visual evoked potential,SSVEP)信号,并作为输入信号应用于脑机接口系统。研究结果表明,该方法不需叠加平均信号就可以提高信噪比,提取出的稳态视觉诱发电位信号能够准确反映使用者的控制意图,为脑机接口选取特征提供了依据。
