Congratulations to the following six members of the SIAM community who will receive awards at the virtual SIAM Conference on Control and Its Applications (CT21). Additional information about each recipient, including Q&As, can be found below.
Lukas Hertlein and Michael Ulbrich
Lukas Hertlein and Michael Ulbrich are the 2021 recipients of the SIAM Activity Group on Control and Systems Theory Best SICON Paper Prize. The award will be presented at the SIAM Conference on Control and Its Applications (CT21) to be held in a virtual format July 19 – 21, 2021. The prize is awarded to Hertlein and Ulbrich for their paper titled “An Inexact Bundle Algorithm for Nonconvex Nonsmooth Minimization in Hilbert Space''. They will present their paper in a lecture at CT21 on July 20, 2021 at 12:00 p.m. Eastern Time.
The SIAM Activity Group on Control and Systems (SIAG/CST) awards this prize every two years to the authors of the two most outstanding papers, as determined by the prize committee, published in SICON in the three calendar years preceding the award year.
Lukas Hertlein is a final-year doctoral candidate at the Technical University of Munich under the supervision of Michael Ulbrich. He is conducting research in nonsmooth, nonconvex, infinite-dimensional optimization. His focus is on the development of algorithms that allow for the use of inexact function values and subgradients, and on applications to optimal control problems governed by the obstacle problem.
Michael Ulbrich is a Professor holding the Chair of Mathematical Optimization in the Department of Mathematics at the Technical University of Munich (TUM). He is also affiliated with the Department of Informatics and a member of the TUM Senate and the TUM Board of Trustees. He received a Ph.D. and a Habilitation from TUM and, as a Postdoc, spent two extended research stays at CAAM, Rice University. From 2002 to 2006 he held a Professor position at the University of Hamburg before returning to TUM. His research interests include mathematical optimization, optimal control, numerical optimization algorithm, nonsmooth analysis, as well as applications in engineering and other fields.
Q: Why are you excited to receive the SIAG/CST Best SICON Paper Prize?
A: We are very glad and honored that the committee selected our work for this best paper prize. It is exciting that our work at the intersection of numerical optimization methods, nonsmooth analysis, and functional analysis receives special attention and recognition through this prize and was chosen among the many excellent recent papers published in SICON, which is one of the highest valued journals in our field. Also, we are grateful that this work received funding from the DFG within the priority program SPP 1962.
Q: Could you tell us a bit about the research that won you the prize?
A: Models for systems and processes in mechanics and many other fields are often governed by partial differential equations that involve nonsmooth structure. Motivated by the goal of optimally designing or controlling such systems, our paper develops a general bundle method that can solve the resulting challenging class of nonsmooth nonconvex infinite-dimensional optimization problems. The approach allows for inexactness in the computation of function values and subgradients, thus enabling implementations with adaptive error control. We develop a global convergence theory and, for the example of optimal control of obstacle problems, we present error estimates for inexactness control and conduct numerical experiments. Our work appears to be the first that features a full convergence theory for bundle methods that can solve nonconvex nonsmooth infinite-dimensional optimization problems.
Q: What does your work mean to the public?
A: Models for complex system often exhibit nonsmooth behavior, e.g., by involving systems of inequalities. In many applications, such as contact mechanics, these systems are infinite-dimensional and require a discretization to enable computer simulations. Motivated by the goal of optimally controlling or designing such systems, our work develops a class of optimization methods that can solve a broad class of nonsmooth, nonconvex, infinite-dimensional optimization problems. The need for discretization is taken into account by allowing for approximate function and subgradient evaluations and it is discussed how the arising inexactness can be controlled to achieve convergence. The results are illustrated by applications to optimal control problems for obstacle problems.
Q: What does being a SIAM member mean to you?
A: Hertlein: As a junior scientist, the articles published in SIAM Journals inspire me in my research and, at the same time, give me the opportunity to improve as a mathematician. The quality of SIAM journals and books has always been impressive to me and they have been a constant source for my work. I am thankful to SIAM and its members for publishing and promoting high-quality research.
Ulbrich: I have been a SIAM member ever since I was a Ph.D. student. Over the years, I have attended numerous, excellent SIAM conferences and I have published a monograph and many of my best papers with SIAM. With its reasonably priced, highest quality journals that are run and edited highly professionally and its broad range of excellent services to our community, the importance of SIAM for my work cannot be overemphasized
The authors collaborated on their answers to our questions.
Bahman Gharesifard, Abdol-Reza Mansouri, and Drew Steeves
Bahman Gharesifard, Abdol-Reza Mansouri, and Drew Steeves are 2021 recipients of the SIAM Activity Group on Control and Systems Theory Best SICON Paper Prize. The award will be presented at the SIAM Conference on Control and Its Applications (CT21) to be held in a virtual format July 19 – 21, 2021. The prize is awarded to Gharesifard, Mansouri, and Steeves for their paper titled ''Controllability of Coupled Parabolic Systems with Multiple Underactuations’'. They will present their paper in a lecture at CT21 on July 20, 2021 at 12:25 p.m. Eastern Time
The SIAM Activity Group on Control and Systems (SIAG/CST) awards this prize every two years to the authors of the two most outstanding papers, as determined by the prize committee, published in SICON in the three calendar years preceding the award year.
Bahman Gharesifard is an Associate Professor with the Department of Mathematics and Statistics at Queen's University. He held an Alexander von Humboldt visiting professorship with the Institute for Systems Theory and Automatic Control at the University of Stuttgart, and postdoctoral positions with the Department of Mechanical and Aerospace Engineering at University of California, San Diego, and the Coordinated Science Laboratory at the University of Illinois at Urbana-Champaign. His research interests include systems and controls, distributed control, distributed optimization and learning, geometric control theory, social and economic networks, game theory, geometric mechanics, and applied Riemannian geometry.
Abdol-Reza Mansouri is a Professor in the Department of Mathematics and Statistics at Queen's University (in Kingston, ON). He received his Undergraduate degree in Electrical Engineering and his Master's degree in Mathematics from McGill University, and his Ph.D. in Applied Mathematics from Harvard University. He joined Queen's University following a one-year postdoctoral stay in the Laboratory for Information and Decision Systems at MIT. His research interests include sub-Riemannian geometry, and, in particular, heat kernel asymptotics, as well as the study of topological obstructions in control problems. More recent research interests have to do with inverse PDE problems as well as Stochastic Analysis, and, in particular, the problem of regularization by noise.
Drew Steeves is finishing his Ph.D. in Dynamics and Control at the University of California, San Diego. He received his bachelor's and master’s degrees in Mathematics and Engineering at Queen’s University. His master’s research focused on controllability problems (finite-time, open-loop) for coupled PDEs. He has broad research interests with a recent focus on accelerated convergence algorithms for ODEs and PDEs; in particular, stabilization, estimation, motion planning, and tracking designs in prescribed finite time for complex coupled systems that are motivated by a wide array of engineering problems, such as multi-agent deployment, man-environment epidemic spreading, and selective laser sintering.
Q: Why are you excited to receive the SIAG/CST Best SICON Paper Prize?
A: We are humbled and honored that the committee is recognizing our work, which advances controllability results for coupled parabolic partial differential equations (PDEs). We are delighted that control problems for coupled PDEs, which are of theoretical importance and of high practical value, are being cast in this spotlight.
Q: Could you tell us a bit about the research that won you the prize?
A: In this work, we have characterized when the evolutions of coupled linear parabolic PDEs can be controlled by interior control inputs, where actuation is available on a limited number of subsystems. Our treatment extends to systems with couplings appearing as spatially–distributed reaction– and advection–like terms within each equation. We advance the so-called algebraic solvability method to derive a sufficient condition under which null controllability holds for systems with less controls than equations. Algebraic solvability pursues this control problem by reformulating it into two interconnected components: an analytic control problem (where “fictitious” controls act on every equation in the coupled system), and an algebraic control problem (where underactuation is permitted). For the algebraic part, we advance an algebraic method to “solve” (from a differential operator perspective) systems of coupled linear parabolic PDEs. For the analytic part, we construct controls with sufficient high-order regularity to invoke the algebraic part and achieve null controllability. These two parts produce a controllability condition that is reminiscent of the Kalman rank condition for finite–dimensional systems, in that it is a condition on the rank of a matrix composed of coupling coefficients for the unactuated part. Moreover, by first designing “fictitious” controllers to achieve a desired control objective for the fully actuated analytic problem, our approach can be used to reduce the number of controllers required to meet this objective.
Q: What does your work mean to the public?
A: Coupled parabolic PDEs abound the study of practical dynamical systems, for example, in atmospheric, epidemic and lithium-ion battery modeling. Complex models for the spread of wildfires involve reaction-diffusion systems coupled with fluid dynamical systems; the spread of epidemics due to environmental transmission is modeled by coupled parabolic PDE and ODE systems; and coupled parabolic PDEs also model lithium-ion batteries with electrodes comprised of multiple active materials. They also appear in the broader areas of thermal, geochemical and biological systems, whose systems can be cast as parabolic PDEs with in-domain couplings and interior controls. When tasked with regulating such systems, it is seldom the case that controls enter every equation within the system. This underactuation elicits the problem of determining whether such systems are controllable. Our work provides an easily-verifiable sufficient controllability condition for coupled parabolic PDEs, and in doing so, advances a control design technique that can be utilized to reduce the number of controls.
Q: What does being a SIAM member mean to you?
A: Being a SIAM member means being part of a community that shares our passion for mathematics and that values rigorous mathematical treatments of interdisciplinary research topics. It also means access to a wealth of wonderful publications: we all have found many gems over the years in SIAM journals and books. Last but not least, it means participation in enriching meetings and high-quality conferences and venues which have always been a source of inspiration for us. We urge any researchers and students with interests in applied mathematics to consider becoming members of this wonderful society.
The authors collaborated on their answers to our questions.
Giulia Giordano
Giulia Giordano is the 2021 recipient of the SIAM Activity Group on Control and Systems Theory Prize. The award will be presented at the SIAM Conference on Control and Its Applications (CT21) to be held in a virtual format July 19 – 21, 2021. Giordano will give a presentation at CT21 titled “Capture the Structure: Parameter-free Analysis and Control of Dynamic Behaviours” on July 21, 2021 at 12:45 p.m. Eastern Time.
The prize is awarded to Giordano for her significant contributions to the development of innovative methodologies for the structural analysis of networked control systems and their applications to biological networks.
The SIAM Activity Group on Control and Systems (SIAG/CST) awards this prize every two years to one outstanding early career researcher for distinguished contributions to mathematical theory of systems and control in the three calendar years preceding the award year.
Giulia Giordano is currently on faculty at the Department of Industrial Engineering, University of Trento, Italy. She received the B.S. (2010) and M.S. (2012) degrees in electrical engineering and the Ph.D. degree in systems and control theory (2016) from the University of Udine, Italy. She visited the California Institute of Technology, USA, in 2012, and the University of Stuttgart, Germany, in 2015. She was a Research Fellow at Lund University, Sweden (2016-2017) and an Assistant Professor at the Delft University of Technology, The Netherlands (2017-2019). She received the Outstanding Reviewer Letter from the IEEE Transactions on Automatic Control in 2016, the EECI Ph.D. Award 2016 from the European Embedded Control Institute for her thesis “Structural Analysis and Control of Dynamical Networks”, and the NAHS Best Paper Prize 2017. Her main research interests include the study of dynamical networks, the analysis of biological systems, and the control of networked systems.
Q: Why are you excited to receive the award of the SIAG/CST Prize?
A: I am honored to receive this prestigious prize, awarded by such an important mathematical organization. I am deeply grateful to the award committee and to the SIAM community for this recognition of my research, which fills me with enthusiasm and motivation. I also warmly thank the colleagues who worked with me and who supported my nomination.
Q: Could you tell us a bit about the research that won you the prize?
A: I am fascinated by interdisciplinary research challenges at the intersection between engineering and the life sciences, and mathematics is a precious common language to describe and understand phenomena in both fields. In particular, I am fond of structural analysis, aimed at revealing qualitative properties of networked dynamical systems that exclusively depend on their inherent interconnection structure and are independent of parameter values, which are often deeply uncertain. Despite huge uncertainties, variations and fluctuations, biological networks are able to preserve fundamental behaviors and properties that are crucial for survival: structural analysis can provide insight into the sources of their extraordinary robustness.
Q: What does your work mean to the public?
A: Structural approaches can not only unravel the intrinsic functioning of biological systems, but also help synthesize biomolecular systems that are guaranteed to exhibit the desired behavior even in highly uncertain environments, or suggest to adopt the same clever strategies selected by nature in the design of bio-inspired robust engineering systems.
Also, the recent pandemic has reminded us all of the importance of mathematics to model, understand, predict and control the contagion of infectious diseases: I am happy to have given my small contribution to this huge endeavor.
Q: What does participating in SIAM mean to you?
A: I greatly value SIAM and its excellent journals, books, conferences, and activity groups promoting cutting-edge research in applied mathematics. The SIAM community is inspiring, open and makes everyone feel welcome, because it fosters interdisciplinary research and applications of mathematics to all areas of engineering and science.