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中国物理学会期刊

基于稀疏重构的尾波干涉成像方法

CSTR: 32037.14.aps.68.20190831

Imaging through coda wave interferometryvia sparse reconstruction

CSTR: 32037.14.aps.68.20190831
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  • 尾波干涉成像是利用尾波时延和扩散近似敏感核来反演散射介质中微小速度扰动空间分布的技术. 该问题本质上是一个欠定问题, 一般无确定解, 导致其难以精确定位介质中微小波速变化的区域. 为解决上述缺陷, 本文利用速度扰动分布在空间上具有稀疏性的特点, 提出了一种基于压缩感知理论中稀疏重构算法的尾波干涉成像方法. 该方法可在散射介质中较准确地获取速度扰动的空间位置和范围, 同时具有较高的计算效率. 数值仿真和实验结果表明: 相比于现有的线性最小二乘差分成像方法, 无论是单个还是多个扰动区域, 该方法均能更精确地进行定位成像, 同时明显减少了计算时间.

     

    The coda wave interferometry is widely used in the fields of geophysics and material science. As an extension of coda wave interferometry, imaging through coda wave interferometry is a technique to obtain the spatial distribution of small velocity perturbations within a scattering medium by using time lapse and sensitivity kernels in the diffusion approximation. However, imaging through coda wave interferometry is essentially an undetermined problem without definite solution, resulting in some difficulties in accurately locating small velocity perturbations within a scattering medium. Meanwhile, compressed sensing has been used in many physical imaging systems in recent years. In this paper, we present an imaging method through coda wave interferometry to solve aforementioned problems by using sparse reconstruction algorithm which is involved in compressed sensing theory. The sparsity of velocity perturbation in its space distribution is taken into account in the proposed method. Firstly, the undetermined equation for inversion imaging is established based on the time-lapse data obtained by coda wave interferometry and the sensitivity kernel matrix in the diffusion approximation. Secondly, the inversion equation is reconstructed by using the sparse transformation within the framework of compressed sensing theory. Finally, the minimization of l1 norm is solved by the compressed sensing reconstruction algorithm, and the imaginary part for the spatial distribution of velocity perturbations is subsequently obtained. This method can accurately capture the spatial locations and ranges of both single velocity perturbation and multiple velocity perturbations in scattering medium with high computational efficiency. The numerical simulations are compared with the results from the existing linear least squares method, demonstrating that the proposed method can avoid the complex parameter determination operation, thus greatly improving the accuracy of inversion images, and also significantly reducing the calculating time.

     

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