Stratigraphic absorption compensation based on multiscale shearlet transform     

Chengming Liu  Deli Wang  Jialin Sun  Yibin Li  Fan Yang 《Acta Geophysica》2018,66(4):575-584

Seismic waves propagating through viscoelastic media experience stratigraphic absorption and attenuation effects, which directly affect the imaging resolution in seismic exploration. Without stratigraphic absorption, the ratio of deep reflection energy to shallow reflection energy (attenuation ratio) is invariable at different frequencies. If a seismogram is decomposed into different frequency bands, these signals will show similar time–energy distributions. Therefore, the attenuation ratios should be similar across different frequency bands, except for frequency-variable weights. Nevertheless, the frequency-variable weights for different frequency bands can be obtained by benchmarking against the time–energy distributions of low-frequency information because the loss of low-frequency information is relatively insignificant. In this light, we obtained frequency-variable weights for different frequencies and established a stratal absorption compensation (SAC) model. The anisotropic basis of the shearlet enables nearly optimal representation of curved-shape seismic signals, and shearlets at different scales can represent signals for different frequency bands. Then, we combined the SAC model with the shearlet transform and established the new compensation method. As the signal and noise have different distributions in the shearlet domain, we selectively compensated the signals using a thresholding algorithm. Hence, it was possible to avoid noise enhancement. This is the prominent advantage of the proposed method over other compensation methods.  相似文献   

一种警务岗亭优化选址方法     

李弘哲  王世杰  李成名 《地理空间信息》2022,20(3):131-133,148

从真实犯罪案例数据出发,以湖南省新宁县为实验区,提出了一种警务岗亭优化选址方法.首先利用核密度估计划定高频案发区;然后利用区域覆盖模型,结合点距离计算方法,对主城区进行犯罪预测,并对构造的犯罪预测区进行置信度检核,置信度为84％.考虑到学校、医院等具有重大安全隐患的公共场所,针对划定的高频案发区、犯罪预测区,利用缓冲区...  相似文献