Charles Tong is a member of the technical staff in the Center for Applied Scientific Computing at LLNL. His current research interests include uncertainty quantification, iterative solvers for linear systems, and parallel computing. He is currently working on several research and application projects on uncertainty quantification. He is the author of the PSUADE software package for uncertainty quantification.

Charles received his Ph.D. degree in Computer Science from UCLA in 1990. Before joining LLNL, he held a staff position at Sandia National Laboratories, and a faculty position in the Mathematics Department at the Hong Kong University of Science and Technology.

D. Miller, B. Ng, J. Eslick and C. Tong, "Advanced Computational Tools for Optimization and Uncertainty Quantification of Carbon Capture Processes," Proceedings of the 8th International Conference on Foundations of Computer-aided Process Design, July 13-17, FOCAPD 2014, Cle Elum, WA.

D. Miller, M. Syamlal, D. Mebane, C. Storlie, D. Bhattacharyya, N. Sahinidis, D. Agarwal, C. Tong, S. Zitney, A. Sarkar, X. Sun, S. Sundaresan, E. Ryan, D. Engel, and C. Dale, "Carbon Capture Simulation Initiative: A Case Study in Multiscale Modeling and New Challenges," *Annual Review of Chemical and Biomolecular Engineering*, Vol. 5, pp. 301-323, July 2014.

Y. Gan, Q. Duan, W. Gong, C. Tong, Y. Sun, W. Chu, A. Ye, C. Miao, and Z. Di, "A comprehensive evaluation of various sensitivity analysis methods: A case study with a hydrological model," *Environmental Modelling and Software*. 11/2013.

C. Tong, "Module-Based Hybrid Uncertainty Quantification for Multi-physics Applications: Theory and Software," LLNL report LLNL-TR-644616-DRAFT, Oct. 2013.

X. Chen, B. Ng, Y. Sun, and C. Tong, "A Computational Method for Simulating Subsurface Flow and Reactive Transport in Heterogeneous Porous Media Embedded with Flexible Uncertainty Quantification," *Journal of Water Resources Research*, DOI: 10.1002/wrcr.20454, 2013.

J. Li, Q. Duan, W. Gong, Z. Ye, Y. Dai, C. Miao, Z. Di, C. Tong, and Y. Sun, "Assessing Parameter Importance of the Common Land Model Based on Qualitative and Quantitative Sensitivity Analysis," *Hydrol. Earth Syst. Sci. Discuss*., 10, 243-2286, 2013, doi:10.5194/hessd-10-2243-2013.

M. Chen, Y. Sun, P. Fu, C. Carrigan, Z. Lu, C. Tong, and T. Buscheck, "Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks," *Computers and Geosciences* (2013), doi:10.1016/j.cageo.2013.05.006.

X. Chen, B. Ng, Y. Sun, and C. Tong, "A flexible uncertainty quantification method for linearly coupled multi-physics systems," *J. Comput. Phys*. (2013), doi:10.1016/j.jcp.2013.04.009.

A. Gel, R. Garg, C. Tong, M. Shahnam, and C. Guenther, "Applying Uncertainty Quantificaion to Multi-phase Flow Computational Fluid Dynamics," *Powder Technology*, doi:10.1016/j.powtec.2013.01.045, 2013.

Y. Sun, C. Tong, W. J. Trainor-Guitton, C. Lu, K. Mansoor, and S. Carroll, "Global Sampling for Integrating Physics-specific Subsystems and Quantifying Uncertainties of CO2 Geological Sequestration," *International Journal of Greenhouse Gas Control*, Vol 12, Jan 2013, pp. 108-123.

C. Zhan, X. Song, J. Xia, and C. Tong, "An Efficient Integrated Approach for Global Sensitivity Analysis of Hydrologic Model Parameters," *Environmental Modelling and Software*, Vol. 41, Mar 2013, pp. 39-52.

G. Iaccarino, and B. Lee, C. Tong and Xiao Chen, "A High Performance Embedded Hybrid Methodology for Uncertainty Quantification with Applications," *in Proc. Exascale Research Workshop 2012*, Portland, OR, April 16-16, 2012.

W. King, A. Arsenlis, C. Tong, and W. Oberkampf, "Uncertainties in Predictions of Material Performance Using Experimental Data that is Only Distantly Related to the System of Interest,"* IFIP Advances in Information and Communication Technology Series*, Vol 0377, 2012.

A. Gel, C. Tong, T. Li, M. Shahnam, C. Guenther, M. Syamlal, and R. Garg, "Uncertainty Quantification in Reactive Multiphase CFD," *Proceedings of The 6th Sino-US Joint Conference of Chemical Engineering*, SINOPEC Conference Centre, Beijing, China, November 7-10, 2011.

D. C. Miller, M. Syamlal, J. C. Meza, D. L. Brown, M. M. Fox, M. A. Khaleel, R. K. Cottrell, J. D. Kress, X. Sun, S. Sundaresan, N. V. Sahinidis, S. E. Zitney, D. A. Agarwal, C. Tong, G. Lin, B. C. letellier, D. W. Engel, P. Calafiura, G. A. Richards, and J. H. Shinn, "Overview of the U. S. DOE's Carbon Capture Simulation Initiative for Accelerating the Commercialization of CCS Technology," *Proceedings of The 36th International Technical Conference on Clean Coal and Fuel Systems*, June 5-9, 2011, Clearwater, Florida, USA.

C. Tong and A. Gel, "Applying Uncertainty Quantification to Multi-phase Flow CFDs," *Proceedings of the 2011 NETL Multiphase Flow Science Workshop*, August 16-18, 2011, Pittsburgh, PA.

Y. Sun, c. Tong, Q. Duan, T. Buscheck and J. Blink, "Combining Simulation and Emulation for Calibrating Sequentially Reactive Transport Systems," *Transport Porous Med*., (2001), DOI: 10.1007/s11242-011-9917-4.

C. Tong, G. Iaccarino, and B. Lee, "A High Performance Embedded Hybrid Methodology for Uncertainty Quantification with Applications," in *Proc. SciDAC 2011*, Denver, CO. July 10-14, 2011.

D. Miller, D. Agarwal, X. Sun and C. Tong, "CCSI and the role of Advanced Computing in Accelerating the Commercial Deployment of Carbon Capture Systems," in *Proc. SciDAC 2011*, Denver, CO. July 10-14, 2011.

C. Tong, "Self-Validated Variance-based Methods for Sensitivity Analysis of Model Outputs," *Reliability Engineering and System Safety*, Vol. 95, Issue 3, (2010), pp. 301-309.

Z. Cai, C. Tong, P. Vassilevski, and C. Wang, "A Mixed Finite Element Method for Incompressible Flow: Stationary Stokes Equation,"* Numerical Methods for Partial Differential Equations*, published online, May 2009.

C. Tong and F. Graziani, "A Global Sensitivity Analysis Methodology for Multi-physics Applications," Computational Methods in Transport: Verification and Validation, *Lecture Notes in Computational Science and Engineering*, Springer-Verlag, 2008.

A. Baker, R. Falgout, T. Kolev, B. Lee, J. Painter, C. Tong, P. Vassilevski and U. Yang, "Performance Assessment and Improvements of HYPRE in ASC Codes," LLNL report UCRL-TR-235618, 2007.

D. Goto and C. Tong, "A Sensitivity Analysis Study of Rayleigh-Taylor Mixing in the Linear Electric Motor Experiment," LLNL report UCRL-TR-235811, 2007.

D. Goto and C. Tong, "Sensitivity Analysis Applied to a Hydrodynamic Pin Shot Simulation," COPJ-2007-0232, Lawrence Livermore National Laboratory, 2007.

D. Goto, F. Graziani, H. Hsieh, J. Pruet, P. Stern, and C. Tong, "Sensitivity Analysis, Uncertainty Quantification and Primary Performance," NECDC (14th Nuclear Explosives Code Development Conference) Proceeding, 2006.

D. Echeverria and C. Tong, "Toward Multi-level Optimization: Space-Mapping and Manifold-Mapping," LLNL report UCRL-TR-22288, 2006.

F. Graziani, D. Miller, D. Sloane, and C. Tong, "Effective Mean Free Paths in Absorbing and Scattering Media: Direct Numerical Simulation," Proceeding on CD-ROM, Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications, Palais des Papes, Avignon, France, Septempber 12-15, 2005, Americal Nuclear Society, LaGrange Park, IL (2005).

R. Bank, S. Lu, C. Tong, and P. Vassilevski, "Scalable Parallel Algebraic Multigrid Solvers, LLNL Report UCRL-TR-210788, 2005.

M. Brezina, C. Tong, and R. Becker, " Parallel Algebraic Multigrids for Structural Mechanics ," accepted for publication in * SIAM Journal on Scientific Computing, *Vol 27, Issue 4, 2006, pp.1534-1554.

C. Tong, " Refinement Strategies for Stratified Sampling Methods, " accepted for publication in * Reliability Engineering and System Safety, Vol. 91, Issue 10-11, 2006, pp. 1257-1265.*

E. Chow, T. Manteuffel, C. Tong, and B. Wallin, " Algebraic Elimination of Slide Surface Constraints in Implicit Structural Analysis ," in * International Journal for Numerical Methods in Engineering *, Vol 57, pp. 1129-1144, 2003.

C. Tong, " Numerical Methods for Saddle Point Problems Arising from Linear Elasticity with Intersecting Slide Surfaces ," LLNL technical report LLNL-JC-148529, 2002.

R. S. Tuminaro, C. Tong, J. N. Shadid, K. D. Devine, D. M. Day, " On a Multilevel Preconditioing Module for Unstructured Mesh Krylov Solver: Two-level Schwarz ," * Comm. Num. Meth. Eng. *, 18, 363-389, 2002.

R.S. Tuminaro and C. Tong, "Parallel Smoothed Aggregation Multigrid: Aggregation Strategies on Massively Parallel Machines," * Proceedings of Supercomputing 2000 *, November 2000.

C. Tong and R.S. Tuminaro, * ML 2.0 Smoothed Aggregation User's Guide *, Report SAND2001-8028, Sandia National Laboratories, 2000.

C. Tong and Q. Ye, " Finite Precision Analysis of the Biconjugate Gradient Algorithm for Nonsymmetric Linear Systems ", *Mathematics of Computation*, 69(232), pp. 1559-1575, 2000. Also available as Stanford SCCM Report SCCM-95-11.

C. Tong, J.C. Meza, and C.D. Moen, " Simulation of Equipment Design Optimization in Microelectronics Manufacturing ", * Proceeding of the 30th Annual Simulation Symposium, * 1997.

J.C. Meza, C.D. Moen, T.D. Plantenga, P.A. Spence, C. Tong, B.A. Hendrickson, R.W. Leland, and G.M. Reese, *Parallel Optimization Methods for Agile Manufacturing, * Sandia Report SAND97-8275, 1997.

C. Tong and Q. Ye, " A Linear System Solver Based on a Modified Krylov Subspace Method for Breakdown Recovery ", * Numerical Algorithms *, 1996.

C. Tong, "The Analysis and Implementation of a Parallel Object-Oriented Toolkit for the Iterative Solution of Partial Differential Equations ," * Proceedings of High Performance Computing, Asia *, Taipei (1995).

D.M. Butler, W.E. Mason, and C. Tong, "An object-Oriented Domain Analysis of Partial Differential Equations, " * Proceedings of OON-SKI *, from Rogue Wave Software, Corvalis, Oregon (1994).

C. Tong, "A Family of Quasi-Minimal Residual Methods for Nonsymmetric Linear Systems, " *SIAM Journal on Scientific and Statistical Computing *, 15(1), pp. 89-105, January 1994.

T.F. Chan, E. Gallopoulos, V. Simoncini, T. Szeto, and C. Tong, " A Quasi-Minimal Residual Variant of the Bi-CGSTAB Algorithm for Nonsymmetric Systems, " * SIAM Journal on Scientific Computing *, 15(2), (1994).

M.E. Colvin, C.L. Janssen, R.A. Whiteside, and C. Tong, " Parallel Direct SCF for Large-Scale Calculations, " *Theoretica Chimica Acta *, 84, pp. 301-314 (1993).

C. Tong, T.F. Chan, and J.C.C. Kuo, " Multilevel Filtering Preconditioners: Extensions to More General Elliptic Problems, " *SIAM Journal on Scientific and Statistical Computing *, 13(1), (1992).

C. Tong, * A Comparative Study of Preconditioned Lanczos Methods for Nonsymmetric Linear Systems, * Sandia Report SAND91-8240B (1991).

C. Tong and P.N. Swarztrauber, *Massively Parallel Hypercube FFTs: CM-2 Implementation and Error Analysis of a Parallel Trigonometric Factor Generation Method,* Sandia Report, SAND91-8500 (1991).

C. Tong, T.F. Chan, and J.C.C. Kuo, " A Domain Decomposition Preconditioner Based on a Change to the Multilevel Nodal Basis, " *SIAM J. on Scientific and Statistical Computing *, 12(67), (1991).

C. Tong and P.N. Swarztrauber, " Ordered Fast Fourier Transforms on a Massively Parallel Hypercube Multiprocessor, " *J. Parallel and Distributed Computing,* 12, pp. 50-59 (1991).

H.D. Cheng, and C.H. Tong, " Clustering Analyzer, " * IEEE Trans. on Circuits and Systems *, Vol. 38, No. 1, pp. 124-128, (1991).

J.C.C. Kuo, T.F. Chan, and C. Tong, " Multilevel Filtering Elliptic Preconditioners, " *SIAM J. Matrix Analysis and Applications *, 11(3), 1991.

H. D. Cheng, C. Tong, and Y. J. Lu, " VLSI Curve Detector ", * Pattern Recognition *, Vol. 23, No. 1/2, pp. 35-50 (1990).

T.F. Chan, J.C.C. Kuo, and C. Tong, " Parallel Elliptic Preconditioners: Fourier Analysis and Performance on the Connection Machine, " *Computer Physics Communications,* 53, pp. 237-252 (1989).

C. Tong, " The Preconditioned Conjugate Gradient Method on the Connection Machine, " * International Journal of High Speed Computing, 2nd Issue: Scientific Applications of the Connection Machine*, (1989). Also in * Proceeding on the Scientific Application of the Connection Machine*, Horst Simon, Ed., World Scientific Publishing Co., pp. 188-213 (1989).

C. Tong, H.D. Cheng, "VLSI Architecture for Curve Detection ," * Proc. Comput. Eur. 87, *, Hamburg (1987).

C. Tong and H. D. Cheng, "Clustering Analyzer for Pattern Recognition ," * SPIE Vol. 845 Visual Communications and Image Processing II *, pp. 350-360 (1987).

C. Tong, * Algebraic Multilevel Preconditioners for Nonsymmetric Systems based on Compatible Relaxation*, 2003.

C. Tong, * Preconditioned Krylov Subspace Methods for Time-dependent Incompressible Navier Stokes Equations,* 2001.

C. Tong, * The Mathematics of Algebraic Multigrid (AMG) Coarsening *, 2000.

C. Tong, R.S. Tuminaro, K.D. Devine, and J.N. Shadid, *Design and Implementation of A Parallel Multigrid Framework for Unstructured Finite Element Calculations *, 1998.

C. Tong, *DOOMSDACE : A Distributed Object-Oriented Software with Multiple Samplings for the Design and Analysis of Computer Experiments, * 1997.

C. Tong, * Improving Parallel Efficiency and Stability of the Conjugate Gradient Squared Algorithm on Massively Parallel Computers, * 1997.

C. Tong and Q. Ye, * A Comparative Analysis of Different Variations of the BICG Algorithm in Finite Precision, *, 1995.

C. Tong, * Analysis of Some Approximate Inverse Preconditioners for Sparse Linear Systems *, 1994.

C. Tong, * Parallel Implementation of a Fast Multipole-like Algorithm for N-body Problems, * 1993.

C. Tong, * Performance Analysis of a Multilevel Preconditioner on the Connection Machine, * 1990.