Research / Publications
Machine learning for physical systems.
Scientific machine learning · Uncertainty quantification · Sensitivity analysis
Founder of SVD Lab . Previously, I was a Senior Research Scientist at Bosch and Apple, following postdoctoral research at MIT. I received my PhD from Tsinghua University.
My research focuses on scientific machine learning and uncertainty quantification, with an emphasis on learning physical dynamics, differentiable simulation and sensitivity analysis.
28 papers & preprints20 archived PDFs4 research themes
28 publications
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01
Scientific machine learningDifferentiable simulation · Stiff systems · Reaction network discovery 2023
Xingyu Su, Weiqi Ji , Jian An, Zhuyin Ren, Sili Deng, Chung K. Law
Combustion and Flame, 251, 112732 · 2023 Journal article
Treats kinetic parameter optimization as neural ODE training to calibrate hydrocarbon-fuel models against experimental targets.
neural ODEs parameter optimization hydrocarbon fuels
2022
Weiqi Ji , Franz Richter, Michael J. Gollner, Sili Deng
Combustion and Flame, 240, 111992 · 2022 Journal article
Learns biomass pyrolysis kinetics from thermogravimetric measurements with interpretable chemical reaction neural networks.
CRNN biomass pyrolysis model discovery
2022
Weiqi Ji , Xingyu Su, Bin Pang, Yujuan Li, Zhuyin Ren, Sili Deng
Fuel, 324, 124560 · 2022 Journal article
Uses differentiable simulation and stochastic gradient descent to optimize mechanistic and hybrid chemical kinetic models.
SGD differentiable programming hybrid modeling
2021
Weiqi Ji , Xingyu Su, Bin Pang, Séan J. Cassady, Alison M. Ferris, Yujuan Li, Zhuyin Ren, Ronald K. Hanson, Sili Deng
arXiv · 2021 Preprint
Introduces differentiable combustion modeling in Julia for gradient-based sensitivity analysis, calibration, uncertainty quantification and model discovery.
differentiable programming Julia Arrhenius.jl UQ
2021
Weiqi Ji , Sili Deng
The Journal of Physical Chemistry A, 125(4), 1082-1092 · 2021 Journal article
Infers interpretable reaction pathways and kinetic parameters from concentration time series using a neural architecture based on mass-action and Arrhenius laws.
CRNN reaction discovery neural ODEs interpretable models
2021
Weiqi Ji , Julian Zanders, Ji-Woong Park, Sili Deng
ASME ICEF 2021 · 2021 Conference paper
Applies stochastic gradient descent to calibrate lumped HyChem fuel models against ignition-delay measurements across temperature regimes.
SGD HyChem kinetic calibration jet fuels
2021
Weiqi Ji , Bo Yuan, Ciyue Shen, Aviv Regev, Chris Sander, Sili Deng
ICLR 2021 Workshop on Deep Learning for Simulation (SimDL) · 2021 Workshop paper
Uses adjoint sensitivity and differentiable programming to infer cell-network dynamics from simulated perturbation-response data.
adjoint sensitivity CellBox network inference systems biology
2021
Weiqi Ji , Sili Deng
arXiv · 2021 Preprint
Represents time-stepping chemical kinetics with a residual neural network and multi-step training, with ignition-delay gradients for model refinement.
KiNet neural surrogates BPTT ignition delay
2021
Xingyu Su, Weiqi Ji , Long Zhang, Wantong Wu, Zhuyin Ren, Sili Deng
ASME IMECE 2021 · 2021 Conference paper
Infers unknown inlet composition and flow fluctuations from sparse combustor-temperature measurements using neural differential equations.
inverse problems neural differential equations combustor dynamics
2021
Suyong Kim, Weiqi Ji , Sili Deng, Yingbo Ma, Christopher Rackauckas
Chaos: An Interdisciplinary Journal of Nonlinear Science, 31(9), 093122 · 2021 Journal article
Studies stiff neural ODE training using scale-aware architectures, output and loss scaling, and stabilized gradient calculations.
neural ODEs stiff systems differentiable simulation
2021
Weiqi Ji , Weilun Qiu, Zhiyu Shi, Shaowu Pan, Sili Deng
The Journal of Physical Chemistry A, 125(36), 8098-8106 · 2021 Journal article
Examines PINN failure on stiff chemical kinetics and uses quasi-steady-state reduction to make the studied systems tractable.
PINNs stiff systems QSSA chemical kinetics
02
Uncertainty quantificationActive subspaces · Sensitivity analysis · Bayesian inference 2023
Benjamin C. Koenig, Weiqi Ji , Sili Deng
Proceedings of the Combustion Institute, 39(4), 5229-5238 · 2023 Journal article
Uses a neural-network surrogate to identify multidimensional kinetic subspaces for uncertainty propagation across nonpremixed flamelet profiles.
active subspaces neural surrogates flamelets uncertainty quantification
2023
Huaibo Chen, Weiqi Ji , Séan J. Cassady, Alison M. Ferris, Ronald K. Hanson, Sili Deng
Proceedings of the Combustion Institute, 39(4), 5299-5308 · 2023 Journal article
Examines effective independent-data counts and target selection when using shock-tube species time histories for Bayesian kinetic parameter estimation.
Bayesian inference parameter estimation shock tubes data correlation
2021
Xingyu Su, Weiqi Ji , Zhuyin Ren
Combustion and Flame, 227, 135-146 · 2021 Journal article
Combines active subspaces with an intermediate reduction state to separate uncertainty changes caused by parameter truncation and reaction coupling.
active subspaces mechanism reduction uncertainty analysis
2020
Weiqi Ji , Tianwei Yang, Zhuyin Ren, Sili Deng
Combustion and Flame, 220, 16-22 · 2020 Journal article
Investigates how kinetic sensitivity directions vary through premixed flame structures and their connection to laminar flame speed and extinction.
sensitivity analysis premixed flames flame speed extinction
2019
Weiqi Ji , Zhuyin Ren, Chung K. Law
Proceedings of the Combustion Institute, 37(1), 807-815 · 2019 Journal article
Relates the sensitivity directions of temperature, species and ignition delay, enabling efficient evaluation of ignition-delay sensitivities.
sensitivity analysis ignition delay chemical kinetics
2019
Weiqi Ji , Zhuyin Ren, Youssef Marzouk, Chung K. Law
Proceedings of the Combustion Institute, 37(2), 2175-2182 · 2019 Journal article
Uses active subspaces and response surfaces to propagate kinetic uncertainty to the liftoff height of a turbulent Cabra hydrogen jet flame.
active subspaces turbulent combustion uncertainty propagation
2019
Weiqi Ji , Zhuyin Ren, Chung K. Law
arXiv · 2019 Preprint
Builds response surfaces in gradient-based active subspaces to propagate uncertain neural-network inputs at reduced computational cost.
active subspaces neural networks input uncertainty surrogate models
2018
Weiqi Ji , Jiaxing Wang, Olivier Zahm, Youssef M. Marzouk, Bin Yang, Zhuyin Ren, Chung K. Law
Combustion and Flame, 190, 146-157 · 2018 Journal article
Combines single-output active subspaces into a shared low-dimensional representation for propagating kinetic uncertainty to multiple quantities of interest.
active subspaces dimension reduction multiple outputs HCCI
2017
Weiqi Ji , Jiaxing Wang, Bin Yang, Zhuyin Ren, Chung K. Law
10th U.S. National Combustion Meeting · 2017 Conference paper
Explores a low-rank surrogate subspace for propagating kinetic uncertainty, using neural response surfaces and genetic optimization.
surrogate subspaces uncertainty propagation dimension reduction
03
Reviews & applicationsResearch reviews · Energy · Mobility 2022
Lei Zhou, Yuntong Song, Weiqi Ji , Haiqiao Wei
Energy and AI, 7, 100128 · 2022 Journal article
Reviews machine-learning approaches to combustion modeling, experiments and computational prediction.
review machine learning combustion
2020
Shiqi Ou, Xin He, Weiqi Ji , Wei Chen, Lang Sui, Yu Gan, Zifeng Lu, Zhenhong Lin, Sili Deng, Steven Przesmitzki, Jessey Bouchard
Nature Energy, 5(9), 666-673 · 2020 Journal article
Combines pandemic scenarios, mobility data and machine learning to project US motor-gasoline demand during COVID-19.
machine learning energy demand mobility scenario analysis
04
Combustion kineticsIgnition experiments · Reaction kinetics 2017
Tamour Javed, Ehson F. Nasir, Ahfaz Ahmed, Jihad Badra, Khalil Djebbi, Mohamed Beshir, Weiqi Ji , S. Mani Sarathy, Aamir Farooq
Proceedings of the Combustion Institute, 36(1), 315-322 · 2017 Journal article
Measures ignition delays of a fully blended low-octane light naphtha fuel.
ignition delay naphtha fuel kinetics
2017
Peng Zhang, Shuang Li, Yingdi Wang, Weiqi Ji , Wenyu Sun, Bin Yang, Xin He, Zhi Wang, Chung K. Law, Feng Zhang
Combustion and Flame, 183, 30-38 · 2017 Journal article
Studies rapid-compression-machine measurement of a reaction rate using dimethyl carbonate decomposition as a case study.
reaction rates RCM dimethyl carbonate
2017
Weiqi Ji , Peng Zhao, Peng Zhang, Zhuyin Ren, Xin He, Chung K. Law
Proceedings of the Combustion Institute, 36(1), 343-353 · 2017 Journal article
Investigates crossover temperature and the lower turnover state of negative-temperature-coefficient ignition behavior.
NTC autoignition reaction pathways
2016
Peng Zhang, Weiqi Ji , Tanjin He, Xin He, Zhi Wang, Bin Yang, Chung K. Law
Combustion and Flame, 167, 14-23 · 2016 Journal article
Combines experiments and simulations to investigate negative-temperature-coefficient behavior in first-stage ignition delay.
two-stage ignition NTC RCM
2016
Weiqi Ji , Peng Zhao, Tanjin He, Xin He, Aamir Farooq, Chung K. Law
Combustion and Flame, 164, 294-302 · 2016 Journal article
Studies the kinetic mechanisms controlling the upper turnover states in the negative-temperature-coefficient regime.
NTC autoignition chemical kinetics
2015
Weiqi Ji , Peng Zhang, Tanjin He, Zhi Wang, Ling Tao, Xin He, Chung K. Law
Combustion and Flame, 162(10), 3541-3553 · 2015 Journal article
Measures intermediate species during iso-butanol autoignition to examine the underlying oxidation pathways.
iso-butanol species measurements autoignition
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