Search Results for author: George Em. Karniadakis

Found 33 papers, 17 papers with code

Physics-Informed Neural Networks for Nonhomogeneous Material Identification in Elasticity Imaging

no code implementations2 Sep 2020 Enrui Zhang, Minglang Yin, George Em. Karniadakis

We apply Physics-Informed Neural Networks (PINNs) for solving identification problems of nonhomogeneous materials.

Solving Inverse Stochastic Problems from Discrete Particle Observations Using the Fokker-Planck Equation and Physics-informed Neural Networks

no code implementations24 Aug 2020 Xiaoli Chen, Liu Yang, Jinqiao Duan, George Em. Karniadakis

The Fokker-Planck (FP) equation governing the evolution of the probability density function (PDF) is applicable to many disciplines but it requires specification of the coefficients for each case, which can be functions of space-time and not just constants, hence requiring the development of a data-driven modeling approach.

Generative Ensemble Regression: Learning Particle Dynamics from Observations of Ensembles with Physics-Informed Deep Generative Models

no code implementations5 Aug 2020 Liu Yang, Constantinos Daskalakis, George Em. Karniadakis

Particle coordinates at a single time instant, possibly noisy or truncated, are recorded in each snapshot but are unpaired across the snapshots.

regression

Physics-informed neural network for ultrasound nondestructive quantification of surface breaking cracks

no code implementations7 May 2020 Khemraj Shukla, Patricio Clark Di Leoni, James Blackshire, Daniel Sparkman, George Em. Karniadakis

The ultrasonic surface wave data is represented as a surface deformation on the top surface of a metal plate, measured by using the method of laser vibrometry.

On the convergence of physics informed neural networks for linear second-order elliptic and parabolic type PDEs

no code implementations3 Apr 2020 Yeonjong Shin, Jerome Darbon, George Em. Karniadakis

By adapting the Schauder approach and the maximum principle, we show that the sequence of minimizers strongly converges to the PDE solution in $C^0$.

B-PINNs: Bayesian Physics-Informed Neural Networks for Forward and Inverse PDE Problems with Noisy Data

no code implementations13 Mar 2020 Liu Yang, Xuhui Meng, George Em. Karniadakis

In this Bayesian framework, the Bayesian neural network (BNN) combined with a PINN for PDEs serves as the prior while the Hamiltonian Monte Carlo (HMC) or the variational inference (VI) could serve as an estimator of the posterior.

Uncertainty Quantification Variational Inference

hp-VPINNs: Variational Physics-Informed Neural Networks With Domain Decomposition

1 code implementation11 Mar 2020 Ehsan Kharazmi, Zhongqiang Zhang, George Em. Karniadakis

We formulate a general framework for hp-variational physics-informed neural networks (hp-VPINNs) based on the nonlinear approximation of shallow and deep neural networks and hp-refinement via domain decomposition and projection onto space of high-order polynomials.

Reinforcement Learning for Active Flow Control in Experiments

1 code implementation6 Mar 2020 Dixia Fan, Liu Yang, Michael S. Triantafyllou, George Em. Karniadakis

We demonstrate experimentally the feasibility of applying reinforcement learning (RL) in flow control problems by automatically discovering active control strategies without any prior knowledge of the flow physics.

Fluid Dynamics Robotics

SympNets: Intrinsic structure-preserving symplectic networks for identifying Hamiltonian systems

1 code implementation11 Jan 2020 Pengzhan Jin, Zhen Zhang, Aiqing Zhu, Yifa Tang, George Em. Karniadakis

We propose new symplectic networks (SympNets) for identifying Hamiltonian systems from data based on a composition of linear, activation and gradient modules.

Physics-informed neural networks for inverse problems in nano-optics and metamaterials

1 code implementation2 Dec 2019 Yuyao Chen, Lu Lu, George Em. Karniadakis, Luca Dal Negro

In this paper we employ the emerging paradigm of physics-informed neural networks (PINNs) for the solution of representative inverse scattering problems in photonic metamaterials and nano-optics technologies.

Computational Physics Optics

DeepONet: Learning nonlinear operators for identifying differential equations based on the universal approximation theorem of operators

4 code implementations8 Oct 2019 Lu Lu, Pengzhan Jin, George Em. Karniadakis

This universal approximation theorem is suggestive of the potential application of neural networks in learning nonlinear operators from data.

PPINN: Parareal Physics-Informed Neural Network for time-dependent PDEs

no code implementations23 Sep 2019 Xuhui Meng, Zhen Li, Dongkun Zhang, George Em. Karniadakis

Consequently, compared to the original PINN approach, the proposed PPINN approach may achieve a significant speedup for long-time integration of PDEs, assuming that the CG solver is fast and can provide reasonable predictions of the solution, hence aiding the PPINN solution to converge in just a few iterations.

Small Data Image Classification

Physics-informed semantic inpainting: Application to geostatistical modeling

no code implementations19 Sep 2019 Qiang Zheng, Lingzao Zeng, Zhendan Cao, George Em. Karniadakis

A fundamental problem in geostatistical modeling is to infer the heterogeneous geological field based on limited measurements and some prior spatial statistics.

Generative Adversarial Network

Potential Flow Generator with $L_2$ Optimal Transport Regularity for Generative Models

no code implementations29 Aug 2019 Liu Yang, George Em. Karniadakis

We propose a potential flow generator with $L_2$ optimal transport regularity, which can be easily integrated into a wide range of generative models including different versions of GANs and flow-based models.

Translation

Trainability of ReLU networks and Data-dependent Initialization

no code implementations23 Jul 2019 Yeonjong Shin, George Em. Karniadakis

In order to quantify the trainability, we study the probability distribution of the number of active neurons at the initialization.

Quantifying the generalization error in deep learning in terms of data distribution and neural network smoothness

1 code implementation27 May 2019 Pengzhan Jin, Lu Lu, Yifa Tang, George Em. Karniadakis

To derive a meaningful bound, we study the generalization error of neural networks for classification problems in terms of data distribution and neural network smoothness.

Learning in Modal Space: Solving Time-Dependent Stochastic PDEs Using Physics-Informed Neural Networks

no code implementations3 May 2019 Dongkun Zhang, Ling Guo, George Em. Karniadakis

One of the open problems in scientific computing is the long-time integration of nonlinear stochastic partial differential equations (SPDEs).

Dying ReLU and Initialization: Theory and Numerical Examples

no code implementations15 Mar 2019 Lu Lu, Yeonjong Shin, Yanhui Su, George Em. Karniadakis

Numerical examples are provided to demonstrate the effectiveness of the new initialization procedure.

A composite neural network that learns from multi-fidelity data: Application to function approximation and inverse PDE problems

2 code implementations26 Feb 2019 Xuhui Meng, George Em. Karniadakis

It is comprised of three NNs, with the first NN trained using the low-fidelity data and coupled to two high-fidelity NNs, one with activation functions and another one without, in order to discover and exploit nonlinear and linear correlations, respectively, between the low-fidelity and the high-fidelity data.

Computational Physics

Physics-Informed Generative Adversarial Networks for Stochastic Differential Equations

no code implementations5 Nov 2018 Liu Yang, Dongkun Zhang, George Em. Karniadakis

We developed a new class of physics-informed generative adversarial networks (PI-GANs) to solve in a unified manner forward, inverse and mixed stochastic problems based on a limited number of scattered measurements.

Gaussian Processes

Nonlocal flocking dynamics: Learning the fractional order of PDEs from particle simulations

no code implementations27 Oct 2018 Zhiping Mao, Zhen Li, George Em. Karniadakis

Instead of specifying the fPDEs with an ad hoc fractional order for nonlocal flocking dynamics, we learn the effective nonlocal influence function in fPDEs directly from particle trajectories generated by the agent-based simulations.

Bayesian Optimization

Quantifying total uncertainty in physics-informed neural networks for solving forward and inverse stochastic problems

no code implementations21 Sep 2018 Dongkun Zhang, Lu Lu, Ling Guo, George Em. Karniadakis

Here, we propose a new method with the objective of endowing the DNN with uncertainty quantification for both sources of uncertainty, i. e., the parametric uncertainty and the approximation uncertainty.

Active Learning Uncertainty Quantification

Deep Learning of Vortex Induced Vibrations

1 code implementation26 Aug 2018 Maziar Raissi, Zhicheng Wang, Michael S. Triantafyllou, George Em. Karniadakis

Of interest is the prediction of the lift and drag forces on the structure given some limited and scattered information on the velocity field.

Collapse of Deep and Narrow Neural Nets

1 code implementation ICLR 2019 Lu Lu, Yanhui Su, George Em. Karniadakis

However, here we show that even for such activation, deep and narrow neural networks (NNs) will converge to erroneous mean or median states of the target function depending on the loss with high probability.

Hidden Fluid Mechanics: A Navier-Stokes Informed Deep Learning Framework for Assimilating Flow Visualization Data

1 code implementation13 Aug 2018 Maziar Raissi, Alireza Yazdani, George Em. Karniadakis

We present hidden fluid mechanics (HFM), a physics informed deep learning framework capable of encoding an important class of physical laws governing fluid motions, namely the Navier-Stokes equations.

Multistep Neural Networks for Data-driven Discovery of Nonlinear Dynamical Systems

2 code implementations4 Jan 2018 Maziar Raissi, Paris Perdikaris, George Em. Karniadakis

The process of transforming observed data into predictive mathematical models of the physical world has always been paramount in science and engineering.

Physics Informed Deep Learning (Part I): Data-driven Solutions of Nonlinear Partial Differential Equations

29 code implementations28 Nov 2017 Maziar Raissi, Paris Perdikaris, George Em. Karniadakis

We introduce physics informed neural networks -- neural networks that are trained to solve supervised learning tasks while respecting any given law of physics described by general nonlinear partial differential equations.

Physics Informed Deep Learning (Part II): Data-driven Discovery of Nonlinear Partial Differential Equations

23 code implementations28 Nov 2017 Maziar Raissi, Paris Perdikaris, George Em. Karniadakis

We introduce physics informed neural networks -- neural networks that are trained to solve supervised learning tasks while respecting any given law of physics described by general nonlinear partial differential equations.

Hidden Physics Models: Machine Learning of Nonlinear Partial Differential Equations

1 code implementation2 Aug 2017 Maziar Raissi, George Em. Karniadakis

While there is currently a lot of enthusiasm about "big data", useful data is usually "small" and expensive to acquire.

BIG-bench Machine Learning Gaussian Processes +1

Numerical Gaussian Processes for Time-dependent and Non-linear Partial Differential Equations

1 code implementation29 Mar 2017 Maziar Raissi, Paris Perdikaris, George Em. Karniadakis

Numerical Gaussian processes, by construction, are designed to deal with cases where: (1) all we observe are noisy data on black-box initial conditions, and (2) we are interested in quantifying the uncertainty associated with such noisy data in our solutions to time-dependent partial differential equations.

Gaussian Processes

Machine Learning of Linear Differential Equations using Gaussian Processes

2 code implementations10 Jan 2017 Maziar Raissi, George Em. Karniadakis

This work leverages recent advances in probabilistic machine learning to discover conservation laws expressed by parametric linear equations.

BIG-bench Machine Learning Gaussian Processes

Inferring solutions of differential equations using noisy multi-fidelity data

1 code implementation16 Jul 2016 Maziar Raissi, Paris Perdikaris, George Em. Karniadakis

For more than two centuries, solutions of differential equations have been obtained either analytically or numerically based on typically well-behaved forcing and boundary conditions for well-posed problems.

Active Learning

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