论文标题

傅立叶延续,用于物理知识神经操作员的精确衍生化计算

Fourier Continuation for Exact Derivative Computation in Physics-Informed Neural Operators

论文作者

Maust, Haydn, Li, Zongyi, Wang, Yixuan, Leibovici, Daniel, Bruno, Oscar, Hou, Thomas, Anandkumar, Anima

论文摘要

物理知识的神经操作员(Pino)是一种机器学习体系结构,已显示出有希望的学习部分微分方程的经验结果。 Pino使用傅立叶神经操作员(FNO)体系结构来克服物理知识神经网络通常面临的优化挑战。由于Pino中的卷积运算符使用傅立叶级数表示,因此可以在傅立叶空间上精确计算其梯度。尽管傅立叶系列不能代表非周期性功能,但Pino和FNO仍然具有通过填充傅立叶扩展来学习非周期性问题的表现力。但是,计算物理知识优化中的傅立叶延伸需要解决不良条件的系统,从而导致不准确的衍生物,从而阻止有效优化。在这项工作中,我们提出了一种利用傅立叶延续(FC)的体系结构,将确切的梯度方法应用于Pino,以解决非周期性问题。本文通过测试其在1D爆炸问题上的性能来调查FC可以将FC纳入Pino的三种不同方式。实验表明,FC-Pino的表现优于填充的Pino,将方程式损失提高了几个数量级,并且可以准确捕获非平滑溶液函数的三阶导数。

The physics-informed neural operator (PINO) is a machine learning architecture that has shown promising empirical results for learning partial differential equations. PINO uses the Fourier neural operator (FNO) architecture to overcome the optimization challenges often faced by physics-informed neural networks. Since the convolution operator in PINO uses the Fourier series representation, its gradient can be computed exactly on the Fourier space. While Fourier series cannot represent nonperiodic functions, PINO and FNO still have the expressivity to learn nonperiodic problems with Fourier extension via padding. However, computing the Fourier extension in the physics-informed optimization requires solving an ill-conditioned system, resulting in inaccurate derivatives which prevent effective optimization. In this work, we present an architecture that leverages Fourier continuation (FC) to apply the exact gradient method to PINO for nonperiodic problems. This paper investigates three different ways that FC can be incorporated into PINO by testing their performance on a 1D blowup problem. Experiments show that FC-PINO outperforms padded PINO, improving equation loss by several orders of magnitude, and it can accurately capture the third order derivatives of nonsmooth solution functions.

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