In recent years we have witnessed a growth in mathematics for deep learning, which has been used to solve inverse problems of partial differential equations (PDEs). However, most deep learning-based inversion methods either require paired data or necessitate retraining neural networks for modifications in the conditions of the inverse problem, significantly reducing the efficiency of inversion and limiting its applicability. To overcome this challenge, in this paper, leveraging the score-based generative diffusion model, we introduce a novel unsupervised inversion methodology tailored for solving inverse problems arising from PDEs. Our approach operates within the Bayesian inversion framework, treating the task of solving the posterior distribution as a conditional generation process achieved through solving a reverse-time stochastic differential equation. Furthermore, to enhance the accuracy of inversion results, we propose an ODE-based Diffusion Posterior Sampling inversion algorithm. The algorithm stems from the marginal probability density functions of two distinct forward generation processes that satisfy the same Fokker-Planck equation. Through a series of experiments involving various PDEs, we showcase the efficiency and robustness of our proposed method.

利用基于评分的生成扩散模型，我们介绍了一种新颖的无监督反演方法，针对由偏微分方程引起的逆问题，通过解决一个逆向时间的随机微分方程来实现将后验分布作为条件生成过程的任务。此外，为了提高反演结果的准确性，我们提出了一种基于ODE的扩散后验采样反演算法。通过一系列涉及各种偏微分方程的实验证明了我们提出方法的效率和鲁棒性。

ODE-DPS: 基于ODE的扩散后验采样方法解决偏微分方程逆问题