This paper presents a multiple material-phase level-set approach for acoustic full-waveform inversion in the time domain. By using a single level set (LS) function, several level values are used to define virtual boundaries between material phases with different (and known) wave propagation velocities. The aim of the proposed approach is to provide a suitable framework to identify multiple/nested inclusions or a finite number of almost homogeneous sedimentary layers with sharp interfaces between them. The use of a single LS function provides a significant reduction in the number of variables to be identified, when compared with the usual multi-material phase approaches defined by multiple functions, especially for problems with a high number of degrees of freedom. Numerical experiments show satisfactory results in identifying simultaneously different interfaces. Cases with and without inverse crime are evaluated, showing that the approach is reasonably robust in dealing with such a condition.

中文翻译：

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应用于时域全波形反演的多材料相的单水平集函数方法

本文提出了一种用于时域声学全波形反演的多材料相水平集方法。通过使用单个水平集 (LS) 函数，可以使用多个水平值来定义具有不同（且已知）波传播速度的材料相之间的虚拟边界。所提出方法的目的是提供一个合适的框架来识别多个/嵌套的包裹体或有限数量的几乎均匀的沉积层，它们之间具有清晰的界面。与由多个函数定义的常见多材料相方法相比，使用单个 LS 函数可以显着减少要识别的变量数量，特别是对于具有高自由度的问题。数值实验在同时识别不同界面方面显示出令人满意的结果。对有和没有逆犯罪的案例进行了评估，表明该方法在处理这种情况方面相当稳健。