According to dispersion theory of coda of local events, using near-field data of aftershocks recorded by two mobile digital stations at the Tianxin and Yunlong after the Wuding, Yunnan Ms=6.5 main-shock and sampling a...According to dispersion theory of coda of local events, using near-field data of aftershocks recorded by two mobile digital stations at the Tianxin and Yunlong after the Wuding, Yunnan Ms=6.5 main-shock and sampling at different central frequencies (1.5-sim;20 Hz), spatial distribution features of coda attenuation ratio β(f) are studied. The results show that there exists obvious non-uniformity of coda attenuation ratio β(f) given by the two stations in small region. When f less than or equal 6.0 Hz the coda attenuation ratio β(f) observed on both sides of earthquake-generating fault are basically identical. Yunlong station is located on east side and Tianxin station on west side. The corresponding Qc(f) is in the range of 66-120. However, in the range of high frequency (f greater than or equal 6.0 Hz) the coda in near field going through major fault encounters a strong absorption from the fracture zone. The β(f) going through the fault observed at Yunlong station is 30% lower than that in Tianxin station in which the seismic waves do not go through the fault. The reason for the difference in space distribution of coda attenuation is discussed. The results also show that factor A0(f) of wave source is not only related to the source strength, but also to frequency f. The mean free path L of S wave obtained using 1.5-20 Hz is respectively 30 km on east side of the fault and 40 km on west side, from which it is verified that there is a stronger dispersion body when seismic waves go through the fracture zone.展开更多
ACGS模型(Active Contours With Group Similarity)在CV模型(Active Contours Without Edges)的基础上结合了矩阵的低秩性约束,是能较好地分割目标特征缺失或错误的相似图像组的一种活动轮廓模型,但其对于局部灰度不均的相似图像组分割...ACGS模型(Active Contours With Group Similarity)在CV模型(Active Contours Without Edges)的基础上结合了矩阵的低秩性约束,是能较好地分割目标特征缺失或错误的相似图像组的一种活动轮廓模型,但其对于局部灰度不均的相似图像组分割效果较差。对此,本文提出了包含演化曲线内外的动态亮度信息的改进的ACGS模型。在全局信息的基础上引入曲线内外动态变化的亮度信息,不仅增强了曲线对于局部灰度不均图像的模糊边界的识别,而且提高了能量函数梯度趋于零的速度,使函数更快达到最小值,从而加快了演化曲线达到目标边界的速度。最后,实验结果验证了改进的ACGS模型对于局部灰度不均的相似图像组,无论在分割效果还是分割速度上均优于ACGS模型。展开更多
基金National Key Fundamental Research Plan (Mechanism and Prediction of Continental Strong Earthquake( - Moving Test Field in Wester
文摘According to dispersion theory of coda of local events, using near-field data of aftershocks recorded by two mobile digital stations at the Tianxin and Yunlong after the Wuding, Yunnan Ms=6.5 main-shock and sampling at different central frequencies (1.5-sim;20 Hz), spatial distribution features of coda attenuation ratio β(f) are studied. The results show that there exists obvious non-uniformity of coda attenuation ratio β(f) given by the two stations in small region. When f less than or equal 6.0 Hz the coda attenuation ratio β(f) observed on both sides of earthquake-generating fault are basically identical. Yunlong station is located on east side and Tianxin station on west side. The corresponding Qc(f) is in the range of 66-120. However, in the range of high frequency (f greater than or equal 6.0 Hz) the coda in near field going through major fault encounters a strong absorption from the fracture zone. The β(f) going through the fault observed at Yunlong station is 30% lower than that in Tianxin station in which the seismic waves do not go through the fault. The reason for the difference in space distribution of coda attenuation is discussed. The results also show that factor A0(f) of wave source is not only related to the source strength, but also to frequency f. The mean free path L of S wave obtained using 1.5-20 Hz is respectively 30 km on east side of the fault and 40 km on west side, from which it is verified that there is a stronger dispersion body when seismic waves go through the fracture zone.
文摘ACGS模型(Active Contours With Group Similarity)在CV模型(Active Contours Without Edges)的基础上结合了矩阵的低秩性约束,是能较好地分割目标特征缺失或错误的相似图像组的一种活动轮廓模型,但其对于局部灰度不均的相似图像组分割效果较差。对此,本文提出了包含演化曲线内外的动态亮度信息的改进的ACGS模型。在全局信息的基础上引入曲线内外动态变化的亮度信息,不仅增强了曲线对于局部灰度不均图像的模糊边界的识别,而且提高了能量函数梯度趋于零的速度,使函数更快达到最小值,从而加快了演化曲线达到目标边界的速度。最后,实验结果验证了改进的ACGS模型对于局部灰度不均的相似图像组,无论在分割效果还是分割速度上均优于ACGS模型。
