Publications

2024

  • Robust Partitioning and Operation for Maximal Uncertain-Load Delivery in Distribution Grids [arXiv]
    H. Moring, H. Nagarajan, K. Girigoudar, D.M. Fobes, J.L. Mathieu
    Electric Power Systems Research
    Presented at 23nd Power Systems Computation Conference (PSCC), Paris, France

  • Optimal Robust Network Design: Formulations and Algorithms for Maximizing Algebraic Connectivity [arXiv]
    N. Somisetty, H. Nagarajan, S. Darbha

  • Learning to Accelerate Tightening of Convex Relaxations of the AC Optimal Power Flow Problem [online]
    F. Cengil, H. Nagarajan, R. Bent, S. Eksioglu, B. Eksioglu

  • Multi-market Optimal Energy Storage Arbitrage with Capacity Blocking for Emergency Services [arXiv]
    M.U. Hashmi, S. Hardy, D. Van Hertem, H. Nagarajan

2023

  • Learning to Accelerate Partitioning Algorithms for Global Optimization of Quadratically-Constrained Quadratic Programs [arXiv] [Optimization Online]
    R. Kannan, H. Nagarajan, D. Deka

  • Learning for Interval Prediction of Electricity Demand: A Cluster-based Bootstrapping Approach [arXiv]
    R. Dube, N. Gautam, A. Banerjee, H. Nagarajan

  • Tightening Quadratic Convex Relaxations for the AC Optimal Transmission Switching Problem [arXiv] [Optimization Online]
    C. Guo, H. Nagarajan, M. Bodur

  • Impact of Ordering of Heterogeneous Vehicles on String Stability [online]
    N. Somisetty, H. Nagarajan, S. Darbha
    26th IEEE International Conference on Intelligent Transportation Systems (ITSC), Bilbao, Spain

  • Optimization-based bound tightening using a strengthened QC-relaxation of the optimal power flow problem [online][arXiv]
    K. Sundar, H. Nagarajan, S. Misra, M. Lu, C. Coffrin, R. Bent
    62nd IEEE Conference on Decision and Control (CDC), Marina Bay Sands, Singapore

2022

  • Optimal Microgrid Networking for Maximal Load Delivery in Phase Unbalanced Distribution Grids: A Declarative Modeling Approach [online]
    D. Fobes, H. Nagarajan, R. Bent
    IEEE Transactions on Smart Grid

  • Mitigating the Impacts of Uncertain Geomagnetic Disturbances on Electric Grids: A Distributionally Robust Optimization Approach [online] [arXiv]
    M. Ryu, H. Nagarajan, R. Bent
    IEEE Transactions on Power Systems

  • Learning to Accelerate Globally Optimal Solutions to the AC Optimal Power Flow Problem [online]
    F. Cengil, H. Nagarajan, R. Bent, S. Eksioglu, B. Eksioglu
    Electric Power Systems Research
    Presented at 22nd Power Systems Computation Conference (PSCC), Porto, Portugal

  • Optimal Power Flow under Stochastic N-1 Disruptions in Electric Transmission Grids [online]
    H. Yang, H. Nagarajan
    Electric Power Systems Research
    Presented at 22nd Power Systems Computation Conference (PSCC), Porto, Portugal

  • Exploring Non-linear Programming Formulations in QuantumCircuitOpt for Optimal Circuit Design
    E.R. Henderson, H. Nagarajan, C. Coffrin
    SC22: The International Conference for High Performance Computing, Networking, Storage, and Analysis (Workshop on Quantum Computing Software)

2021

  • 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)

  • Efficient Topology Design Algorithms for Power Grid Stability [online][arXiv]
    S. Bhela, H. Nagarajan, D. Deka, V. Kekatos
    IEEE Control Systems Letters

  • Sequence of Polyhedral Relaxations for Nonlinear Univariate Functions [online] [arXiv]
    K. Sundar, S. Sanjeevi, H. Nagarajan
    Optimization and Engineering

  • QuantumCircuitOpt: An Open-source Framework for Provably Optimal Quantum Circuit Design [arXiv] [online]
    H. Nagarajan, O. Lockwood, C. Coffrin
    SC21: The International Conference for High Performance Computing, Networking, Storage, and Analysis (Workshop on Quantum Computing Software)

2020

  • 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).

  • 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).

  • 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

2019

  • 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

2018

  • 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

2017

  • 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

2016

  • 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

2015

  • 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

2014 and earlier

  • 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

Collaborations

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

Students and Postdocs

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

Software

Media Features

Out of the Dark

1663 article on how LANL-ANSI scientists strategize best to keep the lights on with a modern and secure national power grid. [url] [pdf]

Early career paths at national labs

American Mathematical Society article on how early career path as a scientist can be at Los Alamos National Laboratory. [url] [pdf]

TAMU-LANL partnership

“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]

R&D 100

R&D 100 Award winning team for PowerModelsONM [Award announcement], [Youtube video]

Contact