A data-driven parametric model order reduction (MOR) method using a deep
artificial neural network is proposed. The present network, which is the
least-squares hierarchical variational autoencoder (LSH-VAE), is capable of
performing nonlinear MOR for the parametric interpolation of a nonlinear
dynamic system with a significant number of degrees of freedom. LSH-VAE
exploits two major changes to the existing networks: a hierarchical deep
structure and a hybrid weighted, probabilistic loss function. The enhancements
result in a significantly improved accuracy and stability compared against the
conventional nonlinear MOR methods, autoencoder, and variational autoencoder.
Upon LSH-VAE, a parametric MOR framework is presented based on the spherically
linear interpolation of the latent manifold. The present framework is validated
and evaluated on three nonlinear and multiphysics dynamic systems. First, the
present framework is evaluated on the fluid-structure interaction benchmark
problem to assess its efficiency and accuracy. Then, a highly nonlinear
aeroelastic phenomenon, limit cycle oscillation, is analyzed. Finally, the
present framework is applied to a three-dimensional fluid flow to demonstrate
its capability of efficiently analyzing a significantly large number of degrees
of freedom. The performance of LSH-VAE is emphasized by comparing its results
against that of the widely used nonlinear MOR methods, convolutional
autoencoder, and $\beta$-VAE. The present framework exhibits a significantly
enhanced accuracy to the conventional methods while still exhibiting a large
speed-up factor.

提出了使用深度人工神经网络的数据驱动参数模型降阶（MOR）方法，其中采用最小二乘分层变分自动编码器（LSH-VAE），可以进行非线性 MOR，对具有大量自由度的非线性动态系统进行了参数插值，其结果表明相比传统的非线性 MOR 方法、自动编码器和变分自动编码器，LSH-VAE 具有更高的准确性和稳定性，并在三个非线性多物理动力学系统上进行了验证和评估。