Zhenzhou, China
Zhenzhou, China

Time filter

Source Type

Zhu D.-B.,University of South China | Geng J.-N.,University of South China | Huang M.,Geophysical Survey Team | Wang N.,University of South China | Wang M.,University of South China
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

As an example in seismic exploration, tailstock is suitable to those sites always difficult to install geophones with tail-cones, such as, a ballast site in railway. Here, a theoretical analysis was performed with the mobility and modal analysis theory to show the effects of the added mass and contact stiffness of the geophone on its response performance in frequency domain. An actual geophone with tailstock was used in model testing and field tests to the tests were consistent with those of the theoretical analysis from which the field tests is analyzed in contrast to show the influence of added mass and contact stiffness on an ideal bandwidth. It was proved that the tailstock detector is feasible for the real production. The essential characteristics of this kind of geophone with tailstock were described also.

Huang M.,Geophysical Survey Team | Zhu D.,Central South University | Guo Z.-X.,Geophysical Survey Team
Wutan Huatan Jisuan Jishu | Year: 2012

Thought widely applied in engineering exploration, the GPR's detecting section is difficult to have a better response to the relatively deep a nomalies because of some influencing factors such as the rapid decay of high-frequency electromagnetic waves transmitted from GPR in a medium and the large environmental noise, etc. Though using of complex signal analysis to extract three instantaneous parameters can analyze signals in multiple perspectives and highlight the weak reflection information, it is very vulnerable to noise interference, in addition, the conventional filtering method cannot remove the interference effectively. Therefore, by introducing the wavelet transform of dual limitations of time-frequency into complex signal analysis, the issue that complex signal analysis is susceptible to noise will be solved, and its ability to extract anomaly will be restored as well. Putting this algorithm into actual GPR detecting data, satisfying application effect turns out.

Zhu D.-B.,Central South University | Geng J.-N.,Central South University | Huang M.,Geophysical Survey Team | Wang M.,Central South University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2013

When the ground-penetrating radar (GPR) is used in exploration of railway subgrades, its records are severely interfered in data processing by direct-coupled waves from antennas, strong rail reflection, and diffraction and multiple waves caused by sleepers. Sleeper interference in raw records possesses the feature of space-time periodic distribution. In this paper, the resampled multiple channels of records are translated, superposed and reaveraged by one time and multiple times of sleeper-to-sleeper periods to from the time space filter screen holding the interference information of sleepers. It is seen that the time space filter screen can be used to well suppress the diffraction and multiple waves caused by sleepers and direct-coupled waves and strong rail reflections can also be suppressed at the same time. Numerical simulation and measured data processing show the time space filter screen algorithm has obvious effects in improving the SNR and resolution capability of abnormalities of the GPR records.

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