提出ENOR框架,精准量化非局部模型误差并提升长期预测可靠性。
Embedded Nonlocal Operator Regression (ENOR): Quantifying model error in learning nonlocal operators
- 在核函数中嵌入可学习的模型误差项,实现误差自适应建模。
- 通过多级延迟接受MCMC方法,高效完成参数与误差联合推断。
- 在1维异质杆波传播预测中,显著优于传统加性噪声模型。
非局部积分算子因其能表征长程依赖和多尺度效应,已成为自下而上均匀化问题的有效代理模型。然而,非局部均匀化模型不可避免地存在与微观模型的偏差,该误差在长时间模拟中累积并传播,导致预测不可靠。为构建鲁棒可靠的自下而上均匀化框架,本文提出嵌入式非局部算子回归(ENOR)框架,用于学习非局部均匀化代理模型及其结构化模型误差。该框架提供长期模拟中材料响应预测的偏差自适应不确定性量化。方法基于基于优化的非局部核学习方法NOR(Nonlocal Operator Regression),并在可训练核中引入嵌入的模型误差项,随后采用贝叶斯推断联合估计误差项参数与核参数。为提升计算效率,采用多级延迟接受马尔可夫链蒙特卡洛(MLDA-MCMC)方法,实现高效的贝叶斯模型校准与误差估计。实验应用于一维异质杆的长期波传播预测,结果表明,相比加性噪声模型,所学ENOR在后验预测不确定性估计上表现更优。
原文摘要 · Abstract (English)
Nonlocal, integral operators have become an efficient surrogate for bottom-up homogenization, due to their ability to represent long-range dependence and multiscale effects. However, the nonlocal homogenized model has unavoidable discrepancy from the microscale model. Such errors accumulate and propagate in long-term simulations, making the resultant prediction unreliable. To develop a robust and reliable bottom-up homogenization framework, we propose a new framework, which we coin Embedded Nonlocal Operator Regression (ENOR), to learn a nonlocal homogenized surrogate model and its structural model error. This framework provides discrepancy-adaptive uncertainty quantification for homogenized material response predictions in long-term simulations. The method is built on Nonlocal Operator Regression (NOR), an optimization-based nonlocal kernel learning approach, together with an embedded model error term in the trainable kernel. Then, Bayesian inference is employed to infer the model error term parameters together with the kernel parameters. To make the problem computationally feasible, we use a multilevel delayed acceptance Markov chain Monte Carlo (MLDA-MCMC) method, enabling efficient Bayesian model calibration and model error estimation. We apply this technique to predict long-term wave propagation in a heterogeneous one-dimensional bar, and compare its performance with additive noise models. Owing to its ability to capture model error, the learned ENOR achieves improved estimation of posterior predictive uncertainty.
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