Subramanian Ramakrishnan

Dr. Ramakrishnan's core research interests are in nonlinear, stochastic dynamic systems and control and their applications. Focusing on theoretical and computational analyses, he is an author or co-author of more than 60 peer-reviewed research publications and the National Science Foundation and the U.S. Army Research Office have supported his research.

He has advised multiple graduate student theses and mentored several undergraduate research projects.

He serves as a proposal review panelist for the NSF and also as an associate editor for the American Society of Mechanical Engineers (ASME) Dynamic Systems and Control Conferences, the ASME/IEEE American Control Conferences, and the International Federation of Automatic Control (IFAC) Modeling, Estimation and Control Conferences.

He also serves as a reviewer for multiple journals.

Undergraduate and graduate students, as well as post-doctoral fellows are encouraged to contact Dr. Ramakrishnan at sramakrishnan1@udayton.edu to discuss research opportunities.

• B.Tech., mechanical engineering, Mahatma Gandhi University; Kerala, India
• M.Sc., mechanical engineering; University of Calgary, Alberta, Canada,
• MSE, mechanical engineering, Johns Hopkins University
• Ph.D., mechanical engineering, Rutgers University

• Post-doctoral researcher, University of Maryland
• Post-doctoral research, University of Cincinnati
• Research assistant professor, Center for Nonlinear Dynamics and Control, Villanova University
• Assistant professor, University of Minnesota Duluth
• Associate professor, University of Minnesota Duluth

• nonlinear, stochastic dynamics and control with applications in areas including robotics, dynamics of nanoelectromechanical systems, energy localization and epidemiological modeling.

• NSF Research Experience for Undergraduates (REU) Supplemental Grant to NSF Award Number: 2140405, National Science Foundation, $8,000 (2023-2024).
• Understanding Stochastic Spatiotemporal Dynamics of Epidemic Spread to Improve Control Interventions - From COVID-19 to Future Pandemics, Award No: CMMI - 2140405, National Science Foundation (awarded April 2022, ongoing).
• Characterization and Control of Emergent Behavior in Complex Systems, Award
  Number: EFRI -1024608, National Science Foundation, (Sept. 2010-Sept. 2012).
• Modeling and Analysis of Swarm Robotic Systems using the Fokker-Planck formalism, Award No: W911NF-09-1-0561, Short-Term Innovative Research Grant (STIR), Division of Mathematical and Information Sciences, US Army Research Office (Nov. 2009-July 2010).

• "Models to Combat Epidemics," on The Academic Minute, WAMC Northeast Public Radio, National Public Radio affiliate, October 2022.
• "Local scientists are trying to track the next virus down to the zip code," on WVXU-FM Focus on Technology, Cincinnati's NPR affiliate, May 2022.

• Instabilities and Pattern Formation in Epidemic Spread Induced by Nonlinear Saturation Effects and Ornstein-Uhlenbeck Noise, A.K. Singh, C. Buschmeyer, S. Ramakrishnan, and M. Kumar, ASME Letters in Dynamic Systems and Control, (5)(1):011002 (2025). DOI Link: https://doi.org/10.1115/1.4066628 
• Instabilities and self–organization in spatiotemporal epidemic dynamics driven by nonlinearity and noise, A.K. Singh, S. Ramakrishnan, and M. Kumar, Physical Biology,  (21) 046001 (2024). DOI Link: https://iopscience.iop.org/article/10.1088/1478-3975/ad5d6a
• Stochastic dynamics of a nonlinear vibration energy harvester subjected to a combined parametric and external random excitation: The distinct cases of It\^o and Stratonovich stochastic integration, S. Ramakrishnan S.} and A.K. Singh, International Journal of Non-Linear Mechanics, (162) 104700 (2024). DOI: https://www.sciencedirect.com/science/article/abs/pii/S0020746224000659
• LSTM-based Estimation of Time-Varying Parameters in a Spatiotemporal PDE Model for Prediction of Epidemic Spread, D.A. David, L. Street, S. Ramakrishnan, and M. Kumar, Proceedings of the MECC 2024 International Federation of Automatic Control - Modeling, Estimation and Control Conference, Chicago IL, Oct 2024, (accepted, in press).
• Nonlinear Model Predictive Control for Mitigating Epidemic Spread using a Partial Differential Equation based Compartmental Dynamic Model, L. Street, D.A. David, C. Liu, S. Ehrlich, M. Kumar, and S. Ramakrishnan, Proceedings of the MECC 2024 International Federation of Automatic Control - Modeling, Estimation and Control Conference, Chicago IL, Oct 2024, (accepted, in press).
• Noise-induced instabilities in nonlinear epidemic dynamics, A.K. Singh, S. Ramakrishnan, and M. Kumar, Abstract 234, MS-14 - Random Dynamical Systems - Recent Advances and New Directions, ENOC 2024 European Nonlinear Oscillations Conference, Delft, The Netherlands, July 2024.
• Turing-type instabilities and pattern formation induced by saturation effects and randomness in nonlinear, diffusive epidemic spread, A.K. Singh, N. Boltz, M. Kumar, and S. Ramakrishnan, Paper No. 933, Proceedings of the ACC 2024 American Control Conference, Toronto, Canada, July 2024 pp. 4711-4716. DOI Link: https://doi.org/10.23919/ACC60939.2024.10644593
• On the Nonlinear Stochastic Dynamics of an Atomic Force Microscope cantilever, A.K. Singh, and S. Ramakrishnan, ASME Letters in Dynamic Systems and Control, (3) 031006 (2023). DOI Link: https://doi.org/10.1115/1.4063601
• Dynamic Instabilities and Pattern Formation in Diffusive Epidemic Spread, A.K. Singh, G. Miller, M. Kumar, and S. Ramakrishnan, IFAC-Papers OnLine, (56) (3) pp 463-468 (2023). DOI Link: https://doi.org/10.1016/j.ifacol.2023.12.067
• On the nonlinear stochastic dynamics of an Atomic Force Microscope cantilever,  A.K. Singh and S. Ramakrishnan, Abstract No: 106, International Federation of Automatic Control (IFAC) - Modeling, Estimation and Control Conference 2023.
• Prediction of the Effective reproduction number from a novel Spatiotemporal Model of epidemic spread and validation using COVID-19 data: An interdisciplinary approach, D.D. Antony, C. Liu, S. Ramakrishnan, M. Kumar, and S. Ehrlich, Poster No: P395, Society of Epidemiologic Research (SER) - Annual Conference 2023, Portland OR, June 2023.
• On the emergence of traffic jams in a stochastic traffic flow driven by additive and multiplicative white Gaussian noise processes, A.K. Singh, J. Meyer and S. Ramakrishnan, Journal of Statistical Mechanics: Theory and Experiment, (2022), 123401 (2022).
• Non-Pharmaceutical Interventions as Controls to mitigate the spread of epidemics: An analysis using a spatiotemporal PDE model and COVID–19 data, F. Majid, M. Gray, A.M. Deshpande, S. Ramakrishnan, M. Kumar and S. Ehrlich, ISA Transactions (124) 215-224 (2022).
• Stochastic stability of a piezoelectric vibration energy harvester under a parametric excitation and noise-induced stabilization, C. Edlund and S. Ramakrishnan, Mechanical Systems and Signal Processing (140) 106566 (2020).
• An analytical study of vibrational energy harvesting using piezoelectric tiles in stairways subjected to human traffic, C. Edlund and S. Ramakrishnan, European Journal of Applied Mathematics (30) 5, 968-985 (2019).
• On the stochastic dynamics of a nonlinear vibration energy harvester driven by Lévy flight excitations, S. Ramakrishnan, C. Edlund and C. Lambrecht, European Journal of Applied Mathematics (30) 5, 945-967 (2019).
• Efficient spatial coverage by a robotic swarm based on an ant foraging model and the Lévy distribution, A. Schroeder, S. Ramakrishnan, M. Kumar, M. and B. Trease, Swarm Intelligence (11) 1, 39-69 (2017).
• Stochastic nonlinear oscillator models of EEG: the Alzheimer's disease case, P. Ghorbanian, S. Ramakrishnan and H. Ashrafiuon, Frontiers in Computational Neuroscience (9) 48, 1-14 (2015).
• A phenomenological model of EEG based on the dynamics of a stochastic Duffing – van der Pol oscillator network, P. Ghorbanian, S. Ramakrishnan, A. Whitman and H. Ashrafiuon, Biomedical Signal Processing and Control (15) 1-10 (2015).
• Spatiotemporal chemotactic model for ant foraging, S. Ramakrishnan, T. Laurent, M. Kumar and A. L. Bertozzi, Modern Physics Letters B (28), 1450238 (2014).
• Cyclic pursuit in a multi-agent robotic system with double-integrator dynamics under linear interactions, B. R. Sharma, S. Ramakrishnan and M. Kumar, Robotica (31) 1037-1050 (2013).
• Energy localization and white noise induced enhancement of response in a micro-scale oscillator array, S. Ramakrishnan and B. Balachandran, Nonlinear Dynamics (62) 1-16, (2010).
• Dynamics of a Duffing nanomechanical resonator coupled to a single-electron transistor: A master equation approach, S. Ramakrishnan, Y. Gulak and H. Benaroya, Physical Review B (78) 174304 (2008).
• Controlling discrete breathers in a nonlinear electrical lattice using random excitation, C. Edlund and S. Ramakrishnan, No: MS-16, 306354, ENOC2022 – European Nonlinear Dynamics Conference, Lyon, France (2022).
• Analysis of epidemic spread dynamics using a PDE model and COVID-19 data from Hamilton County OH USA, F. Majid, A.M. Deshpande, S. Ramakrishnan, S. Ehrlich and M. Kumar, International Federation of Automatic Control – IFAC Papers Online, (54) 322 -327 (2021).
• Morphological Computation using a Soft Robot: A Nonlinear Oscillator Network Model, S. Ramakrishnan and H. Harma H., No:425, NODYCON2021 Second International Nonlinear Dynamics Conference, Rome, Italy (2021).
• On Quality Factor Improvement in a NEMS Resonator with Nonlinear Damping, S. Ramakrishnan and Md. R. Shougat, No: IDETC2019-98505, IDETC 2019 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Anaheim, CA (2019).
• The Hysteresis Phenomenon and Q Factor Enhancement in Nonlinear NEMS Resonators Driven by Lévy Stable Stochastic Processes, Md. R. Shougat and S. Ramakrishnan, No: 1570463877, IEEE 2018 Nanotechnology Materials and Devices Conference, Portland OR, (2018).
• Nonlinear damping in nanomechanical resonators, S. Ramakrishnan, No: ISBN: 978-3-200-05210-9, 13th International Conference on Theoretical and Computational Acoustics, Vienna, Austria (2017) (Invited Contribution).
• Energy harvesting using nonlinear piezoelectric tiles on stairways, C. Edlund and S. Ramakrishnan, No: 297, ENOC2017 - European Nonlinear Dynamics Conference, Budapest, Hungary (2017).
• Density-based control of multiple robots, S. Zhao, S. Ramakrishnan and M. Kumar, No: DOI: 10.1109/ACC.2011.5990615, 2011 American Control Conference, San Francisco, CA (2011).