By analysing the propagation law of electromagnetic wave,the distribution pattern of the field and the theory of frequency electromagnetic sounding,the physical mechanisms that make the frequency electromagnetic sound...By analysing the propagation law of electromagnetic wave,the distribution pattern of the field and the theory of frequency electromagnetic sounding,the physical mechanisms that make the frequency electromagnetic sounding in near-field zone difficult are discussed.Based on the theory of near source field,a new method of dual-frequency electromagnetic sounding of combination wave in near-field zone is advanced.Meanwhile,the method of measurement of fields,the definition of apparent resistivity and the numerical algorithm are approached.展开更多
The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environ...The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environmental sounds using the double-level energy detection (DED) was presented. The DED was used to detect the existence of the sound signals under noise conditions. In addition, MFCC features from the frames which were detected the presence of the sound signals by DED were extracted. Experimental results show that the proposed technology has better noise immunity than classic MFCC, and also outperforms time-domain energy detection (TED) and frequency-domain energy detection (FED) respectively.展开更多
On the basis of the frequency domain acoustic solation of sources in arbitrary motion, in this paper an approximate acoustic solution of a rotating point source in near field is given, which is the superposition of th...On the basis of the frequency domain acoustic solation of sources in arbitrary motion, in this paper an approximate acoustic solution of a rotating point source in near field is given, which is the superposition of the well-Known far field solution and three near field modification items on the condition that the rotating radius is acoustically compact compared with the field sound wavelength. Accordingly the near field Green function in free space is obtained. The characteristic directionality of the sound field induced by source rotating is discussed, and the influences of source position, source frequency and rotating frequency are studied in detail.展开更多
基金Project supported by the Post-Doctoral Science Foundation and the Doctoral Fund of Education Commission of China.
文摘By analysing the propagation law of electromagnetic wave,the distribution pattern of the field and the theory of frequency electromagnetic sounding,the physical mechanisms that make the frequency electromagnetic sounding in near-field zone difficult are discussed.Based on the theory of near source field,a new method of dual-frequency electromagnetic sounding of combination wave in near-field zone is advanced.Meanwhile,the method of measurement of fields,the definition of apparent resistivity and the numerical algorithm are approached.
文摘The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environmental sounds using the double-level energy detection (DED) was presented. The DED was used to detect the existence of the sound signals under noise conditions. In addition, MFCC features from the frames which were detected the presence of the sound signals by DED were extracted. Experimental results show that the proposed technology has better noise immunity than classic MFCC, and also outperforms time-domain energy detection (TED) and frequency-domain energy detection (FED) respectively.
文摘On the basis of the frequency domain acoustic solation of sources in arbitrary motion, in this paper an approximate acoustic solution of a rotating point source in near field is given, which is the superposition of the well-Known far field solution and three near field modification items on the condition that the rotating radius is acoustically compact compared with the field sound wavelength. Accordingly the near field Green function in free space is obtained. The characteristic directionality of the sound field induced by source rotating is discussed, and the influences of source position, source frequency and rotating frequency are studied in detail.
