论文标题
使用加固学习的数据驱动的FWI的不合适功能选择
A data-driven choice of misfit function for FWI using reinforcement learning
论文作者
论文摘要
在全波反转(FWI)的工作流程中,我们经常调整反转参数,以帮助我们避免循环跳过并获得高分辨率模型。例如,通常是从使用避免循环跳过的目标函数(例如基于层析成像和图像)或仅使用低频的目标函数开始,然后以后,我们利用最小二乘不合适来接受高分辨率信息。我们还可以执行各向同性(声学)反转以首先更新速度模型,然后切换到多参数各向异性(弹性)反转以完全恢复复杂的物理学。这种层次结构方法在FWI中很常见,它们通常取决于我们的手动干预,基于许多因素,当然,结果取决于经验。但是,随着较大的数据大小通常参与了过程的复杂性,即使对于经验丰富的从业人员来说,做出最佳选择也很困难。因此,作为一个例子,在加固学习的框架内,我们利用深Q网络(DQN)来学习最佳策略来确定在不同的不合适函数之间切换的适当时机。具体而言,我们训练状态行动值函数(Q),以预测何时使用常规的L2-Norm失配函数或更高级的最佳运输匹配器(OTMF)失误来减轻循环滑条并获得高分辨率,并获得高分辨率,并提高了融合。我们使用一个简单的同时,同时说明性转移的反演示例来证明所提出方法的基本原理。
In the workflow of Full-Waveform Inversion (FWI), we often tune the parameters of the inversion to help us avoid cycle skipping and obtain high resolution models. For example, typically start by using objective functions that avoid cycle skipping, like tomographic and image based or using only low frequency, and then later, we utilize the least squares misfit to admit high resolution information. We also may perform an isotropic (acoustic) inversion to first update the velocity model and then switch to multi-parameter anisotropic (elastic) inversions to fully recover the complex physics. Such hierarchical approaches are common in FWI, and they often depend on our manual intervention based on many factors, and of course, results depend on experience. However, with the large data size often involved in the inversion and the complexity of the process, making optimal choices is difficult even for an experienced practitioner. Thus, as an example, and within the framework of reinforcement learning, we utilize a deep-Q network (DQN) to learn an optimal policy to determine the proper timing to switch between different misfit functions. Specifically, we train the state-action value function (Q) to predict when to use the conventional L2-norm misfit function or the more advanced optimal-transport matching-filter (OTMF) misfit to mitigate the cycle-skipping and obtain high resolution, as well as improve convergence. We use a simple while demonstrative shifted-signal inversion examples to demonstrate the basic principles of the proposed method.