A physics-informed neural network method for the approximation of slow invariant manifolds for the general class of stiff systems of ODEs

TL;DR

This paper introduces a physics-informed neural network method to accurately approximate slow invariant manifolds in stiff ODE systems, outperforming traditional methods near boundary regions.

Contribution

The paper develops a novel PINN framework that decomposes vector fields and derives explicit SIM functionals for general stiff ODEs, advancing reduced order modeling.

Findings

PINN achieves higher accuracy than QSSA, PEA, and CSP methods.

The approach effectively captures SIMs near boundaries.

Validated on biochemical and reaction system benchmarks.

Abstract

We present a physics-informed neural network (PINN) approach for the discovery of slow invariant manifolds (SIMs), for the most general class of fast/slow dynamical systems of ODEs. In contrast to other machine learning (ML) approaches that construct reduced order black box surrogate models using simple regression, and/or require a priori knowledge of the fast and slow variables, our approach, simultaneously decomposes the vector field into fast and slow components and provides a functional of the underlying SIM in a closed form. The decomposition is achieved by finding a transformation of the state variables to the fast and slow ones, which enables the derivation of an explicit, in terms of fast variables, SIM functional. The latter is obtained by solving a PDE corresponding to the invariance equation within the Geometric Singular Perturbation Theory (GSPT) using a single-layer feedforward neural network with symbolic differentiation. The performance of the proposed physics-informed ML framework is assessed via three benchmark problems: the Michaelis-Menten, the target mediated drug disposition (TMDD) reaction model and a fully competitive substrate-inhibitor(fCSI) mechanism. We also provide a comparison with other GPST methods, namely the quasi steady state approximation (QSSA), the partial equilibrium approximation (PEA) and CSP with one and two iterations. We show that the proposed PINN scheme provides SIM approximations, of equivalent or even higher accuracy, than those provided by QSSA, PEA and CSP, especially close to the boundaries of the underlying SIMs.