arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2109.09338cs.LGcs.AIcs.CEphysics.comp-ph
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基于物理信息的神经网络在正弦空间中的学习

Learning in Sinusoidal Spaces with Physics-Informed Neural Networks

Jian Cheng Wong, Chinchun Ooi, Abhishek Gupta, Yew-Soon Ong

摘要:

物理信息神经网络(PINN)使用物理增强的损失函数,例如,将来自控制偏微分方程(PDE)的残差项合并,以确保其输出与基本物理定律一致。然而,在实际应用中,很多问题都很难训练出精确的PINN模型。在本文中,我们提出了一个新的角度在正弦空间学习的优点与PINN。通过分析模型初始化时的行为,我们首先表明,PINN的表现力增加会导致初始偏差周围平坦的输出函数。值得注意的是,该初始解可以非常接近于满足许多物理偏微分方程,即,落入仅最小化PDE残差的PINN损失的局部最小值,同时仍然远离共同最小化PDE残差和初始和/或边界条件的真实解。梯度下降优化很难从这样的局部最小值陷阱中逃脱,经常导致训练停滞。然后,我们证明了正弦映射的输入,在一个架构中,我们标记为sf-PINN,是有效的,以增加输入梯度的变化,从而避免被困在这种欺骗性的局部最小值。可变性的水平可以被有效地调制,以匹配手头问题中的高频模式。本文的一个关键方面是全面的实证研究,证明了在正弦空间中使用PINN学习跨越多个物理领域的各种正向和反向建模问题的有效性。

英文摘要:

A physics-informed neural network (PINN) uses physics-augmented loss functions, e.g., incorporating the residual term from governing partial differential equations (PDEs), to ensure its output is consistent with fundamental physics laws. However, it turns out to be difficult to train an accurate PINN model for many problems in practice. In this paper, we present a novel perspective of the merits of learning in sinusoidal spaces with PINNs. By analyzing behavior at model initialization, we first show that a PINN of increasing expressiveness induces an initial bias around flat output functions. Notably, this initial solution can be very close to satisfying many physics PDEs, i.e., falling into a local minimum of the PINN loss that only minimizes PDE residuals, while still being far from the true solution that jointly minimizes PDE residuals and the initial and/or boundary conditions. It is difficult for gradient descent optimization to escape from such a local minimum trap, often causing the training to stall. We then prove that the sinusoidal mapping of inputs, in an architecture we label as sf-PINN, is effective to increase input gradient variability, thus avoiding being trapped in such deceptive local minimum. The level of variability can be effectively modulated to match high-frequency patterns in the problem at hand. A key facet of this paper is the comprehensive empirical study that demonstrates the efficacy of learning in sinusoidal spaces with PINNs for a wide range of forward and inverse modelling problems spanning multiple physics domains.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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