ʡʡʡᘤᘤᘤᱥᱥᱥᳮᳮᳮɂɂɂ
Machine Learning and Physics-based Modeling:
How can we construct interpretable and truly reliable physical models
using concurrent machine learning?
⎎⎎⎎ᓭᓭᓭ
Princeton University
Joint work with:
Jiequn Han, Han Wang, Linfeng Zhang
Roberto Car, Chao Ma, Zheng Ma, Huan Lei, ......
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Outline
Outline
1 PDEs and fundamental laws of physics
2 Machine learning
3 Concurrent learning
4 Molecular modeling
5 Kinetic model for gas dynamics
6 Concluding remarks
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Outline
PDEs and fundamental laws of physics
1 PDEs and fundamental laws of physics
2 Machine learning
3 Concurrent learning
4 Molecular modeling
5 Kinetic model for gas dynamics
6 Concluding remarks
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Two main themes of scientific research
PDEs and fundamental laws of physics
9ʠțᳮ
Physics: Newton’s laws, Maxwell equations, Quantum mechanics
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“Engineering” (industrial) problems: ᑴ⌼ʹ ᩞᧇ ȕᶭʹ
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9ʠțᳮPaul Dirac’s claim (1929)
PDEs and fundamental laws of physics
”The underlying physical laws necessary for the mathematical theory of a large part of
physics and the whole of chemistry are thus completely known, and the difficulty is only that
the exact application of these laws leads to equations much too complicated to be soluble. ”
◀ᦪᱥᳮ⚞9 Pᱥᳮ ᪶ᱥᳮ ᜩᱥᳮ ᡃA˯N
ᑮḄ_⚪ ᓄ, ᩞᧇ, ˯ᱥ, ⚞9Ḅ_⚪ [ȑɏ
8`Ḅʖ [ȑᦪɐ8`
H= Ḅ6ϛ
i∂tΨ = HΨ, Ψ = Ψ(x1, x2,··· , xN)
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ɘ᪵9ʠțᳮ35Y3▭_⚪
PDEs and fundamental laws of physics
ᦪǷA
ᓄɂ
ɏɂ
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ᓄɂ
PDEs and fundamental laws of physics
ᓄɂḄ⌕
express fundamental physical principles (e.g. conservation laws)
obey physical constraints (e.g. symmetries, frame-indifference, Galilean invariance)
(universally) accurate (transferrable): physical parameters can be measured using simple
experiments
physically meaningful (interpretable)
Very successful example: Euler’s equation for gas dynamics (for dense gas)
A not very successful example: extended Euler equation for rarified gas (e.g. Grad’s
13-moment equation)
Kn =
ᑖᙳQᵫ
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ɘ᪵ᓄɂ
PDEs and fundamental laws of physics
ᱥᳮA
generalized hydrodynamics: Onsager
Landau: gradient expansion, weakly nonlinear theory
successful example: Ericksen-Leslie equation for liquid crystals
unsuccessful example: Non-Newtonian fluids
ᦪA
ᑖ᪆, e.g. PLK (Poincar´e-Lighthill-Kuo) method
projection onto principal components
truncation (e.g. Lorenz system)
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