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arXiv 1711.02475stat.ML
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不确定性传播的贝叶斯模型和降维:在随机介质中的应用

Bayesian model and dimension reduction for uncertainty propagation: applications in random media

Constantin Grigo, Phaedon-Stelios Koutsourelakis

摘要:

求解随机偏微分方程(SPDE)的成熟方法通常在高维输入/输出问题中挣扎。这种困难只会在大规模应用中被放大,在大规模应用中,即使几十次全阶模型运行也是不可行的。虽然降维可以缓解其中的一些问题,但尚不知道(高维)输入的哪些特征以及多少特征实际上预测(高维)输出。在本文中,我们主张贝叶斯公式,是能够同时进行维数和模型阶减少。它包括一个组件,该组件通过采用稀疏执行先验和解码组件,利用粗粒度模型的解决方案,以重建的全阶模型的高维输入到一组低维的特征函数。这两个组件表示的概率图形模型中的潜变量,并同时使用随机变分推断方法进行训练。该模型能够量化由于在任何模型阶/降维中必然发生的信息损失以及有限大小的训练数据集产生的不确定性而导致的预测不确定性。我们展示了它的能力,在随机介质中,精细尺度的波动可以引起随机输入与成千上万的变量。通过几十次全阶模型模拟,该模型能够识别显著的物理特征,并在由数千个组件组成的全输出的不同边界条件下产生尖锐的预测。

英文摘要:

Well-established methods for the solution of stochastic partial differential equations (SPDEs) typically struggle in problems with high-dimensional inputs/outputs. Such difficulties are only amplified in large-scale applications where even a few tens of full-order model runs are impracticable. While dimensionality reduction can alleviate some of these issues, it is not known which and how many features of the (high-dimensional) input are actually predictive of the (high-dimensional) output. In this paper, we advocate a Bayesian formulation that is capable of performing simultaneous dimension and model-order reduction. It consists of a component that encodes the high-dimensional input into a low-dimensional set of feature functions by employing sparsity-enforcing priors and a decoding component that makes use of the solution of a coarse-grained model in order to reconstruct that of the full-order model. Both components are represented with latent variables in a probabilistic graphical model and are simultaneously trained using Stochastic Variational Inference methods. The model is capable of quantifying the predictive uncertainty due to the information loss that unavoidably takes place in any model-order/dimension reduction as well as the uncertainty arising from finite-sized training datasets. We demonstrate its capabilities in the context of random media where fine-scale fluctuations can give rise to random inputs with tens of thousands of variables. With a few tens of full-order model simulations, the proposed model is capable of identifying salient physical features and produce sharp predictions under different boundary conditions of the full output which itself consists of thousands of components.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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