针对RLW方程,提出自适应与守恒两种PINN改进方法,提升求解精度。
Enhancing PINN Accuracy for the RLW Equation: Adaptive and Conservative Approaches
- 采用自适应损失加权和显式守恒律约束两种策略
- 在复杂非线性相互作用中误差低于10^-5
- 发现守恒强制未必提升性能,需针对性设计训练
标准物理信息神经网络(PINN)在求解正则化长波(RLW)方程时误差较大。本文提出两种改进方法:自适应损失加权的PINN与显式施加守恒律的保守型PINN。通过三个基准测试验证其有效性:单个孤立子传播、两个孤立子碰撞、以及t=250时的涌流波演化。结果表明,自适应PINN在复杂非线性相互作用(如孤立子碰撞)中显著优于保守型和标准PINN;而保守型在单个孤立子及长期行为(如涌流波)上表现更优。最重要发现是,显式强制守恒律可能对高度非线性系统优化有害,需特殊训练策略。两种方法求解结果与已有数值解偏差均在10^-5量级,证明了无网格方法可准确求解复杂偏微分方程组。研究挑战了‘守恒强制必然提升性能’的假设,为特定问题设计PINN提供指导。
原文摘要 · Abstract (English)
Standard physics-informed neural network implementations have produced large error rates when using these models to solve the regularized long wave (RLW) equation. Two improved PINN approaches were developed in this research: an adaptive approach with self-adaptive loss weighting and a conservative approach enforcing explicit conservation laws. Three benchmark tests were used to demonstrate how effective PINN's are as they relate to the type of problem being solved (i.e., time dependent RLW equation). The first was a single soliton traveling along a line (propagation), the second was the interaction between two solitons, and the third was the evolution of an undular bore over the course of $t=250$. The results demonstrated that the effectiveness of PINNs are problem specific. The adaptive PINN was significantly better than both the conservative PINN and the standard PINN at solving problems involving complex nonlinear interactions such as colliding two solitons. The conservative approach was significantly better at solving problems involving long term behavior of single solitons and undular bores. However, the most important finding from this research is that explicitly enforcing conservation laws may be harmful to optimizing the solution of highly nonlinear systems of equations and therefore requires special training methods. The results from our adaptive and conservative approaches were within $O(10^{-5})$ of established numerical solutions for the same problem, thus demonstrating that PINNs can provide accurate solutions to complex systems of partial differential equations without the need for a discretization of space or time (mesh free). Moreover, the finding from this research challenges the assumptions that conservation enforcement will always improve the performance of a PINN and provides researchers with guidelines for designing PINNs for use on specific types of problems.
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