| Coal plays an important role in the energy structure of our country,the safety production of coal mine has been concerned.After the accident,to know the situation under the collapse as soon as possible,which is very important and urgent to carry out rescue work.The UWB signal has strong penetrating ability,high target recognition,stubborn multipath resolution capability,unyielding anti-interference ability,small detection blind area and many other advantages,which is very suitable for penetration detection under the mine.In the process of accident rescue,the use of electromagnetic wave to detect the life under the landslide can greatly improve the efficiency.In this paper,the electromagnetic characteristics of the landslide are analyzed.The attenuation characteristics of ultra wide band electromagnetic wave are theoretically analyzed.Based on the theory of plane electromagnetic wave and Finel’s formula,the transmission loss and reflection loss characteristics of ultra wide band electromagnetic wave in rock,concrete,and complex collapse medium are analyzed.The numerical simulation results show that the larger the incident angle is,the larger the loss is;with the increase of frequency,the loss of ultra wide band electromagnetic wave becomes larger;The loss of electromagnetic wave increases with the increase of frequency;and the transmission loss of the parallel polarized wave decreases first and then increases with the increase of the incident angle;for the medium with large dielectric constant,the attenuation of the ultra wideband signal is dominated by the reflection loss.On the basis of the above work,this paper studies the method of detecting the life under the collapse body based on UWB signal.There is a big fluctuation of the ultra wide band signal clutter in mine,a hybrid algorithm based on empirical mode decomposition and independent component analysis is applied.The independent component analysis(ICA)method is used to filter the clutter components,and the echo signal is decomposed into several components by empirical mode decomposition(EMD),and the life characteristic curve is analyzed in time domain,in the case of high SNR,get breathing and heartbeat signal.The simulation results show that the algorithm can reconstruct the breath and heartbeat waveform information of the target,therefore,it is suitable for non-contact life detection under the landslide. |
