A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domai...A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrationM signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analy- sis and time-frequency analysis.展开更多
In this paper,we adopt the observation data of two 10Hz YRY 4-component borehole strainmeters and one 100Hz FBS-3B broadband seismometer to study the responses of their observations to the April 11,2012 MW8. 6 earthqu...In this paper,we adopt the observation data of two 10Hz YRY 4-component borehole strainmeters and one 100Hz FBS-3B broadband seismometer to study the responses of their observations to the April 11,2012 MW8. 6 earthquake off the west coast of northern Sumatra,and compare the response characteristics during the coseismic stage after preprocessing of the data. We analyze the spectrum's dynamic process during the coseismic stage with the S transformation method,and discuss the spectrum's details in different seismic phases. The S transformation results of the data of seismometer and borehole strainmeter at the same station show that the coseismic spectrum evolution of the two kinds of observation are similar to each other and can be cross-referenced in indentifying the wave signals,which proves that the borehole strainmeter measurements at high frequencies are reliable.展开更多
The dynamic characteristics of flow field in cyclone separators with different dust hopper structures were studied by coupling Reynolds Stress Model(RSM)and Lagrangian Particle Tracking(LPT)methods.The characteristic ...The dynamic characteristics of flow field in cyclone separators with different dust hopper structures were studied by coupling Reynolds Stress Model(RSM)and Lagrangian Particle Tracking(LPT)methods.The characteristic frequencies of cylinder section,cone section and dust hopper were calculated as f_(1)=53 Hz,f_(2)=65 Hz,and f_(3)=8 Hz by using Fast Fourier Transform(FFT)method,respectively.Based on the effects of f3 on the motion of vortex,the separated space was divided into none affected region,weakly affected region,and strongly affected region.The characteristic frequency of dust hopper increased with the decrease of dust hopper diameter,while it was independent of the height.The dust hopper with d=1.5D(model D3)and h=1.5D(model H3)can significantly decrease the effect of back-mixing on the motion of inner vortex,which is beneficial to improve the efficiency of cyclone separator.展开更多
文摘A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrationM signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analy- sis and time-frequency analysis.
基金funded jointly by the Special Fund for Earthquake-related Scientific Research of China Earthquake Administration(201108009)the Basic Scientific Research Fund of Institute of Earthquake Science,CEA(2012IES0202)the Youth Earthquake Regime Tracing Project for the Year 2012(2012020212)
文摘In this paper,we adopt the observation data of two 10Hz YRY 4-component borehole strainmeters and one 100Hz FBS-3B broadband seismometer to study the responses of their observations to the April 11,2012 MW8. 6 earthquake off the west coast of northern Sumatra,and compare the response characteristics during the coseismic stage after preprocessing of the data. We analyze the spectrum's dynamic process during the coseismic stage with the S transformation method,and discuss the spectrum's details in different seismic phases. The S transformation results of the data of seismometer and borehole strainmeter at the same station show that the coseismic spectrum evolution of the two kinds of observation are similar to each other and can be cross-referenced in indentifying the wave signals,which proves that the borehole strainmeter measurements at high frequencies are reliable.
基金gratefully acknowledge the support from the Fundamental Research Funds for the Central Universities/the Development Fund of State Key Laboratory of Heavy Oil Processing(grant No.20CX02215A)the Natural Science Foundation of Shandong Province(grant No.ZR2021ME036)the National Natural Science Foundation of China(grant No.51806248).
文摘The dynamic characteristics of flow field in cyclone separators with different dust hopper structures were studied by coupling Reynolds Stress Model(RSM)and Lagrangian Particle Tracking(LPT)methods.The characteristic frequencies of cylinder section,cone section and dust hopper were calculated as f_(1)=53 Hz,f_(2)=65 Hz,and f_(3)=8 Hz by using Fast Fourier Transform(FFT)method,respectively.Based on the effects of f3 on the motion of vortex,the separated space was divided into none affected region,weakly affected region,and strongly affected region.The characteristic frequency of dust hopper increased with the decrease of dust hopper diameter,while it was independent of the height.The dust hopper with d=1.5D(model D3)and h=1.5D(model H3)can significantly decrease the effect of back-mixing on the motion of inner vortex,which is beneficial to improve the efficiency of cyclone separator.
