I am currently a staff scientist in the “Applied Mathematics and Plasma Physics” group at Los Alamos National Laboratory (LANL). Previously, I was a post-doctoral research associate at Center for Nonlinear Studies (CNLS), LANL.
My primary research interests include development of efficient formulations and algorithms for modeling, design and control of complex physical systems. Particularly, I utilize tools from a myriad of disciplines including, mathematical programming and optimization (convex and nonconvex), control theory and uncertainty quantification. In recent years, at LANL, I have been focussing on various interesting problems arising in large-scale energy infrastructure systems. More recently, I have been working on application of discrete optimization methods in Quantum Computing. I was recently awarded with the “Outstanding Reviewer 2019” recognition from IEEE Transactions on Power Systems.
Open Positions
Advanced Network Science Initiative at LANL is looking for motivated graduate students and postdoctoral research associates with interests in optimization, control theory, applied mathematics and energy systems. If working with talented scientists in a collaborative environment excites you, feel free to contact me.PhD in Mechanical Engineering, 2014
Systems, Controls and Applied Optimization Lab, Texas A&M University
Master of Science, 2008
Texas A&M University
Bachelor of Technology, 2006
National Institute of Technology, Trichy
Piecewise Polyhedral Formulations for a Multilinear Term [online] [arXiv]
K. Sundar, H. Nagarajan, J. Linderoth, S. Wang, R. Bent
Operations Research Letters
Optimal Power Flow in Distribution Networks under N-1 Disruptions: A Multi-stage Stochastic Programming Approach [arXiv]
H. Yang, H. Nagarajan
Informs Journal on Computing (Accepted)
Mitigating the Impacts of Uncertain Geomagnetic Disturbances on Electric Grids: A Distributionally Robust Optimization Approach [arXiv]
M. Ryu, H. Nagarajan, R. Bent
IEEE Transactions on Power Systems (Submitted)
Efficient Topology Design Algorithms for Power Grid Stability [arXiv]
S. Bhela, H. Nagarajan, D. Deka, V. Kekatos
IEEE Control Systems Letters (Submitted)
Preliminary Design Process for Networked Microgrids
[online]
K.P. Schneider, H. Nagarajan, A. Pratt, M.J. Reno, B. Ollis, F. Tuffner, S.P. Nandanoori, S. Kundu, W. Du, H. Hijazi, and R. Jain.
Generalized Convex Hull Pricing for the AC Optimal Power Flow Problem [online]
M. Garcia, H. Nagarajan, R. Baldick
IEEE Transactions on Control of Network Systems
Algorithms for Mitigating the Effect of Uncertain Geomagnetic Disturbances in Electric Grids [arXiv] [online]
M. Ryu, H. Nagarajan, R. Bent
Electric Power Systems Research
Presented at 21st Power Systems Computation Conference (PSCC), Porto, Portugal
Optimal Power Flow in Distribution Networks under Stochastic N − 1 Disruptions [arXiv] [online]
H. Yang, H. Nagarajan
Electric Power Systems Research
Presented at 21st Power Systems Computation Conference (PSCC), Porto, Portugal
Proving Global Optimality of ACOPF Solutions [arXiv] [online]
S. Gopinath, H. Hijazi, T. Weisser, H. Nagarajan, M. Yetkin, K. Sundar, R. Bent
Electric Power Systems Research
Presented at 21st Power Systems Computation Conference (PSCC), Porto, Portugal
Distributionally Robust Optimization for a Resilient Transmission Grid During Geomagnetic Disturbances [arXiv]
M. Lu, S.D. Eksioglu, S.J. Mason, R.Bent, H. Nagarajan
Chance-Constrained Unit Commitment with N-1 Security and Wind Uncertainty [online]
K. Sundar, H. Nagarajan, L. Roald, S. Misra, R. Bent, D. Bienstock
IEEE Transactions on Control of Network Systems
Resilient Design of Large-Scale Distribution Feeders with Networked Microgrids [online]
A. Barnes, H. Nagarajan, E. Yamangil, R. Bent, S. Backhaus
Electric Power Systems Research
Designing Power Grid Topologies for Minimizing Network Disturbances: An Exact MILP Formulation [arXiv] [online]
S. Bhela, D. Deka, H. Nagarajan, V. Kekatos
American Control Conference (ACC), Philadelphia, USA
Evaluating Ising Processing Units with Integer Programming [online]
C. Coffrin, H. Nagarajan, R. Bent
International Conference on AI and OR Techniques in Constraint
Programming for Combinatorial Optimization Problems (CPAIOR),
Thessaloniki, Greece
Convex Hull Formulations for Mixed-Integer Multilinear Functions
[arXiv] [online]
H. Nagarajan, K. Sundar, H. Hijazi, R. Bent
Proceedings of the XIV International Global Optimization Workshop
LeGO 18, Leiden, Netherlands
An Adaptive, Multivariate Partitioning Algorithm for Global Optimization of Nonconvex Programs [arXiv] [online] [poster]
H. Nagarajan, M. Lu, S. Wang, R. Bent, K. Sundar
Journal of Global Optimization
Probabilistic N-k Failure-identification for Power Systems [arXiv] [online]
K. Sundar, C. Coffrin, H. Nagarajan, R. Bent
Networks, Wiley online Library
Communication-Constrained Expansion Planning for Resilient Distribution Systems [online] [arXiv]
G. Byeon, P.V. Hentenryck, R. Bent, H. Nagarajan
INFORMS Journal on Computing
Hierarchical Predictive Control Algorithms for Optimal Design and Operation of Microgrids [arXiv] [online]
S.K.K. Hari, K. Sundar, H. Nagarajan, R. Bent, S. Backhaus
Power Systems Computation Conference (PSCC), Dublin, Ireland
Tight Piecewise Convex Relaxations for Global Optimization of Optimal Power Flow [arXiv] [online]
M. Lu, H. Nagarajan, R. Bent, S.D. Eksioglu, S.J. Mason
Power Systems Computation Conference (PSCC), Dublin, Ireland
Juniper: An Open-Source Nonlinear Branch-and-Bound Solver in Julia [arXiv] [online]
O. Kröger, C. Coffrin, H. Hijazi, H. Nagarajan
International Conference on AI and OR Techniques in Constraint
Programming for Combinatorial Optimization Problems (CPAIOR),
Delft, Netherlands
Comparison of Various Trilinear Monomial Envelopes for Convex Relaxations of Optimal Power Flow Problems
[arXiv]
M.R. Narimani, D.K. Molzahn, H. Nagarajan, M.L. Crow
IEEE Global Conference on Signal and Information Processing
GlobalSIP 2018, Anaheim, CA, USA
Optimal Transmission Line Switching under Geomagnetic Disturbances [arXiv] [online] [PPT]
M. Lu, H. Nagarajan, E. Yamangil, R. Bent, S. Backhaus, A. Barnes
IEEE Transactions on Power Systems
Resilient Off-grid Microgrids: Capacity Planning and N-1 Security [Poster] [online]
S.C. Madathil, E. Yamangil, H. Nagarajan, A. Barnes,
R. Bent, S. Backhaus, S.J. Mason, S. Mashayekh, M. Stadler
IEEE Transactions on Smart Grid
Security-constrained Design of Isolated Multi-energy Microgrids [online]
S. Mashayekh, M. Stadler, G. Cardoso, M. Heleno, S.C. Madathil,
H. Nagarajan, R. Bent, M. Mueller-Stoffels, X. Lu and J. Wang
IEEE Transactions on Power Systems
Ising Processing Units: Potential and Challenges for Discrete Optimization [arXiv] [PPT]
C. Coffrin, H. Nagarajan, R. Bent
(Under Review)
Adaptive Convex Relaxations for Gas Pipeline Network Optimization [online]
F. Wu, H. Nagarajan, A. Zlotnik, R. Sioshansi, A.M. Rudkevich
American Control Conference (ACC), Seattle, USA
Optimal Configurations to Minimize Disturbance Propagation in Manufacturing Networks [online]
H. Nagarajan, P.R. Pagilla, S.Darbha, R. Bent, P.P. Khargonekar
American Control Conference (ACC), Seattle, USA
Optimal Topology Design for Disturbance Minimization in Power Grids [arXiv][online]
D. Deka, H. Nagarajan, S. Backhaus
American Control Conference (ACC), Seattle, USA
Resilient Transmission Grid Design: AC Relaxation vs. DC Approximation [arXiv]
H. Nagarajan, R. Bent, P.V. Hentenryck, S. Backhaus, E. Yamangil
A Numerical Methodology for Enforcing Maximum Principles and the Non-Negative Constraint for Transient Diffusion Equations [arXiv] [online]
K.B. Nakshatrala, H. Nagarajan, M. Shabouei
Communications in Computational Physics, Cambridge University Press
Tightening McCormick Relaxations for Mixed-Integer Nonlinear Programs via Dynamic Multivariate Partitioning [arXiv] [online]
H. Nagarajan, M. Lu, E. Yamangil, R. Bent
International Conference on Principles and Practice of
Constraint Programming, Toulouse, France
Optimal Resilient Transmission Grid Design [online]
H. Nagarajan, E. Yamangil, R. Bent, S. Backhaus, P.V. Hentenryck
Power Systems Computation Conference (PSCC), Genoa, Italy
Unit Commitment with N-1 Security and Wind Uncertainty [arXiv] [online]
K. Sundar, H. Nagarajan, M. Lubin, L. Roald, S. Misra, R. Bent, D. Bienstock
Power Systems Computation Conference (PSCC), Genoa, Italy
Synthesizing Robust Communication Networks for Unmanned Aerial Vehicles With Resource Constraints [online]
H. Nagarajan, S. Rathinam, S. Darbha
Journal of Dynamic Systems, Measurement, and Control
On Maximizing Algebraic Connectivity of Networks for Various Engineering Applications [online]
H. Nagarajan, S. Rathinam, S. Darbha
European Control Conference (ECC), Linz, Austria
Synthesizing Robust Networks for Engineering Applications with Resource Constraints [online]
H. Nagarajan
PhD Dissertation, Texas A&M University
Heuristics for Synthesizing Robust Networks with a Diameter Constraint [online]
H. Nagarajan, P. Wei, S. Rathinam, D.Sun
Mathematical Problems in Engineering, Hindawi
Algorithms for Finding Diameter-Constrained Graphs with Maximum Algebraic Connectivity [online]
H. Nagarajan, S. Rathinam, S. Darbha, K.R. Rajagopal
Dynamics of Information Systems: Mathematical Foundations
Algorithms for Synthesizing Mechanical Systems with Maximal Natural Frequencies [online]
H. Nagarajan, S. Rathinam, S. Darbha, K.R. Rajagopal
Nonlinear Analysis: Real World Applications, Elsevier
Enforcing the Non-negativity Constraint and Maximum Principles for Diffusion with Decay on General Computational Grids [arXiv] [online]
H. Nagarajan, K.B. Nakshatrala
International Journal for Numerical Methods in Fluids
Synthesizing Robust Communication Networks for UAVs [online]
H. Nagarajan, S. Rathinam, S. Darbha, K.R. Rajagopal
American Control Conference (ACC), Montréal, Canada
Air Transportation Network Robustness Optimization under Limited Legs Itinerary Constraint [online]
H. Nagarajan, P. Wei, S. Rathinam, D.Sun
International Conference on Research in Air Transportation (ICRAT),
Berkeley, CA, USA
In the challenging world of Science and Engineering with increasingly complex problems, collaborative research is the key to success. I have been fortunate to have collaborated with excellent mentors and researchers over the years. Below is the list:
| Name | Institution | Topic |
|---|---|---|
| Swaroop Darbha | TAMU | Synthesis of Robust UAV networks (thesis chair), Control Theory |
| Sivakumar Rathinam | TAMU | Synthesis of Robust UAV networks (thesis co-chair), Approximation Algorithms |
| K.R. Rajagopal | TAMU | Algebraic Connectivity in Mechanical and Biological Systems |
| K.B. Nakshatrala | University of Houston | Discrete Maximum-Minimum Principles for PDEs |
| Russell Bent | LANL | Resilient Energy Infrastructure Systems |
| Scott Backhaus | LANL | Controls and Operation of Networked Microgrids |
| Pascal Van Hentenryck | Georgia Tech | Communication-constrained Power System Resilience |
| Daniel Bienstock | Columbia University | Power Systems Operation with Wind Uncertainty |
| Pramod Khargonekar | UC Irvine | Disturbance Minimization in Linear Dynamical Systems Network |
| Michael Stadler | LBNL, BioEnergy2020+ | Design and Operation of Microgrids |
Below is the list of talented students and postdocs with whom I have really enjoyed working with:
| Name | Institution | Duration | Topic |
|---|---|---|---|
| Haoxiang Yang | LANL (Postdoc) | 2019 - Present | Stochastic Disruptions in Power Networks |
| Kaarthik Sundar | LANL (Postdoc) | 2016 - 2018 | Tight Formulations for Piecewise Convex Relaxations |
| Mowen Lu | Clemson | 2016 - Present | Global Optimization of Optimal Power Flow, Grid Design for Geomagnetic Disturbances (DTRA best poster award) - with Russell Bent |
| S.Chalil Madathil | Clemson | 2016 - 2018 | Off-grid Microgrid Design and Operation - LANL/UNM best poster award (with Russell Bent ) |
| Site Wang | Clemson | 2016 - Present | POD.jl - An Open-source Solver for Global Optimization of MINLPs in Julia (with Russell Bent ) |
| Sai Krishna | TAMU | 2017 - 2018 | Hierarchical Model Predictive Control Algorithms for Microgrid Design and Operation (with Kaarthik Sundar ) |
| Fei Wu | Ohio State | 2016 | Gas Pipeline Network Optimization (with Anatoly Zlotnik ) |
| Sid Bhela | Virginia Tech | 2018 | Minimizing induced disturbances in power grids (with Deep Deka ) |
| Minseok Ryu | U. of Michigan | 2019 | Distributionally Robust Optimization in Power Grids with GMDs |
Alpine.jl is a novel global optimization solver that uses an adaptive, piecewise convexification scheme and constraint programming methods to solve non-convex MINLPs efficiently. Alpine is entirely built on JuMP in Julia, which provides incredible flexibility for usage and further development.
https://github.com/lanl-ansi/Alpine.jlWe would like to thank LANL for funding this project under the auspices of Laboratory Directed Research & Development - Exploratory Research (2017-2019).
Pajarito.jl: A JuMP-based package for solving mixed-integer convex programs, including MISOCPs and MISDPs. And, if you are wondering what Pajarito.jl was named after, check out this link.
Juniper.jl: A JuMP-based package for solving Nonlinear Mixed-Integer Programs to local optimality.
1663 article on how LANL-ANSI scientists strategize best to keep the lights on with a modern and secure national power grid. [url] [pdf]
American Mathematical Society article on how early career path as a scientist can be at Los Alamos National Laboratory. [url] [pdf]
“The Texas A&M System National Laboratories Office” article on design robust complex networks. [url] [pdf]
“LANL Collaborative Program” article on integrating renewables in microgrids. [url-1] [pdf-1] [url-2]