论文标题

通过神经净核对非线性反问题的变异推断:与贝叶斯神经网络的比较,应用于拓扑优化

Variational Inference for Nonlinear Inverse Problems via Neural Net Kernels: Comparison to Bayesian Neural Networks, Application to Topology Optimization

论文作者

Keshavarzzadeh, Vahid, Kirby, Robert M., Narayan, Akil

论文摘要

逆问题,尤其是从数据中推断出未知或潜在参数在工程模拟中无处不在。识别未知参数的主要观点是贝叶斯推断,其中将有关参数的先前信息和通过可能性评估的观测值进行的信息都纳入了推理过程。在本文中,我们采用了类似的观点,其数值过程与标准推理方法略有不同,以提供有关未知基础参数的局部行为的见解。我们提出了一种变异推理方法,该方法主要以一个点的方式合并观察数据,即,我们扭转了有限数量的观察数据,该数据利用了前向映射相对于参数的梯度信息,并找到前向前映射的潜在参数的真实单个样本是无噪声和一对一的。对于统计计算(作为模拟的最终目标),从训练有素的神经网络中生成了大量样品,该样本是从后部潜在参数之前用作传输图。我们的神经网络机械是推理框架的一部分,被称为神经净核(NNK),基于分层(深)内核,与标准神经网络相比,它为训练提供了更大的灵活性。与包括马尔可夫链蒙特卡洛采样方法和贝叶斯神经网络方法在内的多种方法相比,我们展示了推理程序在识别双峰和不规则分布方面的有效性。

Inverse problems and, in particular, inferring unknown or latent parameters from data are ubiquitous in engineering simulations. A predominant viewpoint in identifying unknown parameters is Bayesian inference where both prior information about the parameters and the information from the observations via likelihood evaluations are incorporated into the inference process. In this paper, we adopt a similar viewpoint with a slightly different numerical procedure from standard inference approaches to provide insight about the localized behavior of unknown underlying parameters. We present a variational inference approach which mainly incorporates the observation data in a point-wise manner, i.e. we invert a limited number of observation data leveraging the gradient information of the forward map with respect to parameters, and find true individual samples of the latent parameters when the forward map is noise-free and one-to-one. For statistical calculations (as the ultimate goal in simulations), a large number of samples are generated from a trained neural network which serves as a transport map from the prior to posterior latent parameters. Our neural network machinery, developed as part of the inference framework and referred to as Neural Net Kernels (NNK), is based on hierarchical (deep) kernels which provide greater flexibility for training compared to standard neural networks. We showcase the effectiveness of our inference procedure in identifying bimodal and irregular distributions compared to a number of approaches including Markov Chain Monte Carlo sampling approaches and a Bayesian neural network approach.

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