为物理约束模型设计可保持结构一致性的不确定性量化方法
Structure-preserving uncertainty quantification for GENERIC dynamics

- 通过轻量级附加网络保留预训练模型的物理约束
- 生成符合热力学定律的随机演化结果,且预测区间校准良好
- 计算成本降低1到3个数量级,适合工程模拟中的不确定性分析
结构保持型机器学习将物理结构直接嵌入模型架构,但此类硬约束模型的不确定性量化(UQ)仍受限于标准方法可能违反可接受性条件、需修改架构或带来高昂计算成本。本文提出结构保持型认知神经网络(S-PENNs),一种通用框架,用于具有硬约束的科学机器学习模型的UQ,并应用于GENERIC(非平衡可逆-不可逆耦合一般方程)动力学。S-PENNs通过在约束组件上附加轻量级epinets,保持预训练模型的结构约束,确保每次采样均物理可接受。应用于GENERIC动力学时,该框架生成满足第一、第二热力学定律的热力学一致性轨迹。此外,结合分裂置信预测作为后处理校准方法,获得具有有限样本边缘覆盖率保证的预测区间。在三个数值案例中验证:耦合热浴的谐振子、理想化学马达(均为常微分方程系统),以及一维黏弹性模型(偏微分方程系统)。所有案例中,S-PENNs均生成热力学一致的随机实现实例,并实现良好校准的预测区间,计算成本较深度集成降低约1至3个数量级。尽管当前研究聚焦GENERIC动力学,S-PENNs可扩展至计算力学中具硬或软约束的科学机器学习模型。
原文摘要 · Abstract (English)
Structure-preserving machine learning embeds physical structure directly into model architectures, yet uncertainty quantification (UQ) for such hard-constrained models remains limited because standard UQ methods may violate the encoded admissibility conditions, require architectural modifications, or impose substantial computational costs. In this work, we propose Structure-Preserving Epistemic Neural Networks (S-PENNs), a general framework for UQ in scientific machine learning models with hard architectural constraints, and instantiate it for GENERIC (General Equation for Non-Equilibrium Reversible-Irreversible Coupling) dynamics. S-PENNs preserve the structural constraints of a pretrained model by attaching lightweight epinets to its constrained components, ensuring that every sampled realization remains physically admissible by construction. When applied to GENERIC dynamics, such a proposed framework yields thermodynamically consistent rollouts that preserve the first and second laws. Furthermore, we combine S-PENNs with split conformal prediction as a post-hoc calibration method to produce prediction intervals with finite-sample marginal coverage guarantees. We validate S-PENNs on three numerical examples: a harmonic oscillator coupled to a heat bath and an idealized chemical motor, both governed by ODEs, and a one-dimensional viscoplastic model governed by PDEs. Across all three examples, S-PENNs produce thermodynamically consistent stochastic realizations and well-calibrated prediction intervals while reducing the computational cost by about one to three orders of magnitude compared to deep ensembles. Although the present study focuses on GENERIC dynamics, S-PENNs can be extended more broadly to scientific machine learning models in computational mechanics with either hard or soft constraints.
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