用少样本数据增强训练神经微分方程,提升系统建模精度与稳定性。
Data-Augmented Few-Shot Neural Emulator for Computer-Model System Identification
- 通过空间填充采样生成稀疏但覆盖广的微分算子训练数据
- 仅用10步数值模拟数据即达传统方法数千条轨迹效果
- 适合需要高效建模复杂物理系统的科研与工程人员
偏微分方程(PDEs)是许多自然与工程系统建模的基础。将部分或全部控制方程替换为神经网络表示,可构建神经PDE,其在求导、线性化、降维和不确定性量化方面优于传统数值求解器。现有方法通常基于长时间滚动仿真获得的解轨迹训练,存在时空冗余。本文提出一种更高效的样本生成策略:通过空间填充采样局部“微分模板”状态,生成神经PDE训练数据。该方法消除轨迹数据中的大量冗余,同时高概率采样罕见但关键的状态,促进模型在状态空间中泛化。实验表明,仅需相当于10步数值模拟的合成数据,即可训练出高精度的神经微分模板算子;若额外获取一条完整轨迹(实践中常见),性能进一步提升。在多个PDE系统上,相比直接从轨迹中随机采样的模板数据,本方法训练的神经算子表现更优。最终,仅用10步求解器计算量的增强数据,其长期滚动预测精度与稳定性已超越基于数千条轨迹训练的传统机器学习代理模型。
原文摘要 · Abstract (English)
Partial differential equations (PDEs) underpin the modeling of many natural and engineered systems. It can be convenient to express such models as neural PDEs rather than using traditional numerical PDE solvers by replacing part or all of the PDE's governing equations with a neural network representation. Neural PDEs are often easier to differentiate, linearize, reduce, or use for uncertainty quantification than the original numerical solver. They are usually trained on solution trajectories obtained by long-horizon rollout of the PDE solver. Here we propose a more sample-efficient data-augmentation strategy for generating neural PDE training data from a computer model by space-filling sampling of local "stencil" states. This approach removes a large degree of spatiotemporal redundancy present in trajectory data and oversamples states that may be rarely visited but help the neural PDE generalize across the state space. We demonstrate that accurate neural PDE stencil operators can be learned from synthetic training data generated by the computational equivalent of 10 timesteps' worth of numerical simulation. Accuracy is further improved if we assume access to a single full-trajectory simulation from the computer model, which is typically available in practice. Across several PDE systems, we show that our data-augmented stencil data yield better trained neural stencil operators, with clear performance gains compared with naively sampled stencil data from simulation trajectories. Finally, with only 10 solver steps' worth of augmented stencil data, our approach outperforms traditional ML emulators trained on thousands of trajectories in long-horizon rollout accuracy and stability.
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