Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagneti...Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.展开更多
When strong interferences are present in underwater environments, the performance of target of interest(TOI) bearing estimation algorithms can be significantly degraded. To address this problem, an interference suppre...When strong interferences are present in underwater environments, the performance of target of interest(TOI) bearing estimation algorithms can be significantly degraded. To address this problem, an interference suppression method for subspace judgment(SSJ) is proposed, which aims to achieve TOI-bearing estimation in the presence of multiple strong interferences. With prior knowledge of the TOI bearing interval, the proposed method builds a judgment item using the correlation between the TOI-interferencenoise subspace and steering vector. The eigenvectors that are not dominated by the TOI are accurately identified via comparison with the estimated judgment threshold. And the identified eigenvectors will be subtracted from the sample covariance matrix(SCM) for interference suppression. The proposed method can obtain a residual SCM that primarily contains the signal of the TOI. It reduces the output power of interference and acquires TOI with a higher signal-to-interference plus noise ratio(SINR), which provides methodical support for improving the capability of TOI-bearing resolution. Simulation and experimental data processing results demonstrate that the proposed method effectively suppresses strong interferences outside TOI-bearing intervals. It reduces the output power of interference and sidelobe levels while improving the capability of TOI-bearing resolution. Compared with other interference suppression methods with subspace, the proposed method has a more robust interference suppression capability.展开更多
静止无功发生器(Static Var Generator,SVG)微弱谐波信号处于强干扰区域的中心频带时,会影响谐波信号检测有效性。为提升谐波信号检测性能,提出强干扰下的SVG微弱谐波信号传感检测方法。在强干扰下提取出SVG信号,并采用修正投影阻塞法消...静止无功发生器(Static Var Generator,SVG)微弱谐波信号处于强干扰区域的中心频带时,会影响谐波信号检测有效性。为提升谐波信号检测性能,提出强干扰下的SVG微弱谐波信号传感检测方法。在强干扰下提取出SVG信号,并采用修正投影阻塞法消除SVG信号中存在的干扰。选取振动传感器作为SVG微弱谐波信号检测仪器,由于振动传感器中的仪表放大器会对放大后的SVG信号叠加较多高频噪声,所以在强干扰抑制的基础上进一步滤除噪声。将振动传感器放置在振动台上,并检测处理后的SVG信号。通过数字示波器观测SVG微弱谐波信号在放大电路中的输出波形,判断信号在输送期间是否出现失真问题,从而实现SVG微弱谐波信号传感检测。实验结果表明,所提方法的信噪比高于23.51 dB,幅值检测误差低于0.63 Hz,频率检测误差低于7.1 Hz。展开更多
The traditional methods of weak harmonic signal detection under strong chaotic interference often suffer from high computational complexity and poor performance. In this paper, an Extended Kalman Filter (EKF) based de...The traditional methods of weak harmonic signal detection under strong chaotic interference often suffer from high computational complexity and poor performance. In this paper, an Extended Kalman Filter (EKF) based detection method is proposed for the detection of weak harmonic signal. The EKF method avoids matrix inversion by iterating measurement equation and state equation, which simultaneously improves the robustness and reduces the complexity. Compared with the existing detection methods, the proposed method has the following advantages: 1) it has better performance than the neural network method;2) it has similar performance with the optimal filtering method, but with lower computational complexity;3) it is more robust compared with the optimal filtering method.展开更多
We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for ...We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.展开更多
基金Project(2018YFC0807802)supported by the National Key R&D Program of ChinaProject(41874081)supported by the National Natural Science Foundation of China
文摘Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.
基金supported by the National Natural Science Foundation of China (U20A20329,51979061,12204127)。
文摘When strong interferences are present in underwater environments, the performance of target of interest(TOI) bearing estimation algorithms can be significantly degraded. To address this problem, an interference suppression method for subspace judgment(SSJ) is proposed, which aims to achieve TOI-bearing estimation in the presence of multiple strong interferences. With prior knowledge of the TOI bearing interval, the proposed method builds a judgment item using the correlation between the TOI-interferencenoise subspace and steering vector. The eigenvectors that are not dominated by the TOI are accurately identified via comparison with the estimated judgment threshold. And the identified eigenvectors will be subtracted from the sample covariance matrix(SCM) for interference suppression. The proposed method can obtain a residual SCM that primarily contains the signal of the TOI. It reduces the output power of interference and acquires TOI with a higher signal-to-interference plus noise ratio(SINR), which provides methodical support for improving the capability of TOI-bearing resolution. Simulation and experimental data processing results demonstrate that the proposed method effectively suppresses strong interferences outside TOI-bearing intervals. It reduces the output power of interference and sidelobe levels while improving the capability of TOI-bearing resolution. Compared with other interference suppression methods with subspace, the proposed method has a more robust interference suppression capability.
基金the National Natural Science Foundation of China (Grant No. 61871102 and 61731006)Sichuan province science and technology support program under Grant N0. 2017GZ0345.
文摘The traditional methods of weak harmonic signal detection under strong chaotic interference often suffer from high computational complexity and poor performance. In this paper, an Extended Kalman Filter (EKF) based detection method is proposed for the detection of weak harmonic signal. The EKF method avoids matrix inversion by iterating measurement equation and state equation, which simultaneously improves the robustness and reduces the complexity. Compared with the existing detection methods, the proposed method has the following advantages: 1) it has better performance than the neural network method;2) it has similar performance with the optimal filtering method, but with lower computational complexity;3) it is more robust compared with the optimal filtering method.
文摘We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.
