Upcoming Talks:
April 15th, 11:00am-11:50am, Skye285 & zoom
Dr. Domenico Santoro, USP Technologies and Western University, Canada.
Title: From Equations to Infrastructure: How Applied Mathematics Supports Innovation in Water Technologies
Abstract: Water and wastewater systems are often viewed as collections of physical assets (pipes, tanks, and treatment units) but in practice they behave as complex, dynamic systems shaped by transport, reaction, and operational variability. This seminar will present how applied mathematics supports the development and deployment of real-world water technologies at USP Technologies, with a focus on bridging theory and industrial practice. Through selected case studies, the talk will illustrate how modeling tools, ranging from simplified process representations to computational fluid dynamics (CFD), are used to better understand, design, and optimize treatment systems. Examples will include sewer networks behaving as distributed reactive systems, advanced chemical treatment processes, intensified biological treatment configurations, and real-time control strategies for disinfection.
Attention will be given to how models are adapted to deal with practical constraints such as limited data, system variability, and scale-up from laboratory to full-scale applications. The seminar will also highlight the growing role of integrating mechanistic understanding with data-driven approaches to support decision-making and process optimization. The overall goal is to show how different disciplines can contribute to solving impactful engineering challenges, not only by developing models, but by making them robust, usable, and relevant in real operational environments.
April 22th, 11:00am-11:50am, Skye285 & zoom
Dr. Jiajia Yu, Duke University
Title: Learning in Mean-Field Games
Abstract: Mean-field games (MFGs) study systems with a continuum of indistinguishable, non-cooperative agents, with applications ranging from physical, biological, financial, and social systems to more recent connections with reinforcement learning and generative modeling. In these models, an individual’s optimal control depends on the evolving population distribution, and a central object of interest is the mean-field Nash equilibrium (MFNE), where individual behavior is consistent with the resulting population dynamics. Computing the MFNE leads to a highly nonlinear problem and is particularly challenging in the high-dimensional settings that arise in many applications.
In this talk, I will present our recent work on developing a scalable, structure-preserving solver for MFNE. I will first highlight the structure of MFNEs through the concept of best response, and show how this perspective clarifies both the equilibrium problem and the behavior of the fictitious play algorithm. Motivated by these insights, I will introduce a Lagrangian reformulation and use flow-matching ideas from machine learning to adapt fictitious play for scalable high-dimensional computation. If time permits, I will conclude by discussing applications, recent progress, and many exciting open problems in inverse mean-field games.
This talk is based on joint work with Xiuyuan Cheng, Jian-Guo Liu, and Hongkai Zhao at Duke University, and Junghwan Lee and Yao Xie at the Georgia Institute of Technology.
May 27th, 11:00am-11:50am, zoom
Dr. Paula Chen, US Naval Research Laboratory
Title: Algorithms and Differential Game Representations for Exploring Nonconvex Pareto Fronts in High Dimensions
Abstract: We develop a new Hamiton-Jacobi (HJ) and differential game approach for exploring the Pareto front of (constrained) multi-objective optimization (MOO) problems. Given a preference function, we embed the scalarized MOO problem into the value function of a parameterized zero-sum game, whose upper value solves a first-order HJ equation that admits a Hopf-Lax representation formula. For each parameter value, this representation yields an inner minimizer that can be interpreted as an approximate solution to a shifted scalarization of the original MOO problem. Under mild assumptions, the resulting family of solutions maps to a dense subset of the weak Pareto front. Finally, we propose a primal-dual algorithm based on this approach for solving the corresponding optimality system. Numerical experiments show that our algorithm mitigates the curse of dimensionality (scaling polynomially with the dimension of the decision and objective spaces) and is able to expose continuous curves along nonconvex Pareto fronts in 100D in just ~100 seconds. Distribution Statement A. Approved for Public Release; Distribution is Unlimited. PR 26-0024.