It is possible to yield incorrect results including false long period components, during the restitution of the ground displacement from digital seismograms directly using FFT.
直接使用FFT由数字地震记录来恢复地面位移可能产生包括虚假的长周期分量在内的不正确结果。
2
The time to produce damage deformation in surrounding rock and possible loosening area are obtained by analyzing in situ measurement of displacement in soft weak coal layer.
A kind of polynomial satisfying the displacement boundary conditions is designed, which makes it possible to evaluate the upper limit of fundamental freqrency by Ritz method.