针对局部强源问题的物理信息神经网络,通过自适应小波基提升求解精度。
An adaptive wavelet-based PINN for problems with localized high-magnitude source

- 用动态调整的小波基函数替代固定基,缓解高梯度区域的损失不平衡问题。
- 在源项比高达10¹⁰:1的方程上,误差显著低于传统PINN方法。
- 无需自动微分计算导数,训练更快,适合高尺度特征物理问题求解。
近年来,物理信息神经网络(PINNs)在求解微分方程方面备受关注,但存在神经网络固有的频谱偏差和多尺度现象引发的损失不平衡两大根本局限。本文提出自适应小波基物理信息神经网络(AW-PINN),以应对具有局部高幅值源项问题中极端的损失不平衡。此类问题广泛存在于热处理、电磁学、冲击力学及含局部激励的流体动力学中。所提框架根据残差与监督损失动态调整小波基函数,自适应性使其能高效处理高尺度特征而无需大量内存。此外,该方法不依赖自动微分获取损失函数中的导数,加速了训练过程。算法分为两阶段:先进行短时预训练以筛选物理相关的波形族,再进行尺度与平移的自适应优化,避免在整个域内填充高分辨率基函数。理论上,在一定假设下,我们证明了AW-PINN具有高斯过程极限,并推导出其对应的神经正切核(NTK)结构。在多个具有局部高幅值源项且损失比达10¹⁰:1的挑战性偏微分方程上测试,包括瞬态热传导、高度局部泊松问题、振荡流动方程及点电荷源的麦克斯韦方程,AW-PINN在各类问题中均持续优于现有同类方法。
原文摘要 · Abstract (English)
In recent years, physics-informed neural networks (PINNs) have gained significant attention for solving differential equations, although they suffer from two fundamental limitations, namely, spectral bias inherent in neural networks and loss imbalance arising from multiscale phenomena. This paper proposes an adaptive wavelet-based PINN (AW-PINN) to address the extreme loss imbalance characteristic of problems with localized high-magnitude source terms. Such problems frequently arise in various physical applications, such as thermal processing, electro-magnetics, impact mechanics, and fluid dynamics involving localized forcing. The proposed framework dynamically adjusts the wavelet basis function based on residual and supervised loss. This adaptive nature makes AW-PINN handle problems with high-scale features effectively without being memory-intensive. Additionally, AW-PINN does not rely on automatic differentiation to obtain derivatives involved in the loss function, which accelerates the training process. The method operates in two stages, an initial short pre-training phase with fixed bases to select physically relevant wavelet families, followed by an adaptive refinement that adapts scales and translations without populating high-resolution bases across entire domains. Theoretically, we show that under certain assumptions, AW-PINN admits a Gaussian process limit and derive its associated NTK structure. We evaluate AW-PINN on several challenging PDEs featuring localized high-magnitude source terms with extreme loss imbalances having ratios up to $10^{10}:1$. Across these PDEs, including transient heat conduction, highly localized Poisson problems, oscillatory flow equations, and Maxwell equations with a point charge source, AW-PINN consistently outperforms existing methods in its class.
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