Events

Seminar on "Keynode-Driven Dynamic Mesh Compression" by Dr Truong Nguyen

Date: 22 May 2025, Thursday Time: 11:00 Venue: Room CD634, The Hong Kong Polytechnic University Speaker: Dr Truong Nguyen, University of California San Diego

Seminar on "Multiobjective Complementary Control and Its Application to Mean-Field Games" by Dr Jiapeng Xu

Date: 9 May 2025, Friday Time: 4:30 pm Venue: Room FYW-3316, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Dr Jiapeng Xu, Hong Kong Polytechnic University   Multiobjective Complementary Control and Its Application to Mean-Field Games Dr Jiapeng Xu, Hong Kong Polytechnic University   Abstract:This presentation introduces an interesting control design paradigm for linear time-invariant systems: multiobjective complementary control (MOCC), in which nominal performance and robustness can be achieved in a complementary way instead of a trade-off. In particular, a state-space solution is first established for a new stabilizing control structure consisting of two independently designed controllers coordinated with a Youla-type operator Q. It is then shown by performance analysis that these two independently designed controllers operate in a naturally complementary way for a tracking control system, due to the coordination function of Q driven by the residual signal of a Luenberger observer. An application of MOCC in robust mean-field games is presented. It is shown that the MOCC framework achieves a complementary mean-field control strategy, in contrast to the existing worst-case strategy.   Speaker’s Bio:Jiapeng Xu received the Ph.D. degree in control science and engineering at the East China University of Science and Technology, China, in 2021. He was a Postdoctoral Fellow with the University of Windsor, Canada, from September 2021 to July 2024, with the University of Victoria, Canada, from July 2024 to September 2024, and with the City University of Hong Kong, China, from October 2024 to January 2025. He is currently a Postdoctoral Fellow in the Department of Applied Mathematics, The Hong Kong Polytechnic University, China. His research interests include networked control, multiobjective complementary control, time-delay systems, and mean-field games. Dr. Xu is an Associate Editor for International Journal of Control, Automation, and Systems. He received the Chinese Association of Automation (CAA) Outstanding Doctoral Dissertation Award in 2022.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/

Seminar on "Generating Graphs via Spectral Diffusion" by Prof. Andrea Torsello

Date: 2 May 2025, Friday Time: 12:00pm - 1:00pm Venue: CD634,  The Hong Kong Polytechnic University Speaker: Prof. Andrea Torsello, Ca' Foscari University of Venice Contact person: Prof. ROSSI Luca (luca.rossi@polyu.edu.hk)

Seminar on "Learning to Mitigate Cascading Failure Risk in Power Networks" by Miss Biwei Li

Date: 2 May 2025, Friday Time: 4:30 pm Venue: Room FYW-3316, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Miss Biwei Li, City University of Hong Kong   Abstract:The Cascade Risk Mitigation Set (CRMS) of branches in a power network refers to specific combinations of branches that enhance the capacity to mitigate cascading failure risk. However, identifying the optimal combination is computationally challenging due to the need for repeated cascading failure simulations and the combinatorial explosion of possible solutions. In this talk, I will introduce a novel framework based on graph neural networks (GNNs) to efficiently identify optimal CRMS solutions. The identification problem involves the risk assessment of cascading failure in the objective function, which can be naturally cast as a graph regression task and effectively addressed using GNNs. Two key techniques are incorporated to improve the prediction performance of GNNs. First, the Bus and Branch Graph Attention Network (BB-GAT) is proposed to jointly encode bus and branch features into the graph representation. Second, a pre-training strategy is adopted to reduce the dependency on large amounts of task-specific data and to improve generalization across different operational states. Finally, a hybrid approach is designed to identify the optimal CRMS. This approach prunes the search space using a statistical method, then employs BB-GAT to recommend high-potential candidate solutions and ultimately determines the optimal one via cascading failure simulations. Experimental results on the IEEE 39-bus and 118-bus systems show that this framework achieves near-optimal performance while significantly improving computational efficiency over traditional algorithms.   Speaker’s Bio:Biwei Li is currently a Ph.D. candidate in the Department of Electrical Engineering at the City University of Hong Kong, Hong Kong. She received the B.Eng. degree in mechanical engineering from China University of Geosciences, Wuhan, China, in 2015, and the M.Eng. degree in control science and engineering from Beihang University, Beijing, China, in 2018. Her research interests include complex networks, deep learning applications, and robust analysis of power networks.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/

Seminar on "Sensing of Molecules with Nano-scale Structures: Plasmon Resonance and Nanopores" by Prof Aaron H.P. HO

Date: 28 April 2025, Monday Time: 4:30pm Venue: BC303, PolyU Speaker: Prof Aaron H.P. HO, The Chinese University of Hong Kong   Seminar on “Sensing of Molecules with Nano-scale Structures: Plasmon Resonance and Nanopores” conducted by Prof Aaron H.P. HO.

Seminar on "Transient Stability of Grid-Connected Converters: Effects of Synchronization Control, Output Regulation, and Converter Interaction" by Mr Charles Liu

Date: 25 April 2025, Friday Time: 4:30 pm Venue: Room FYW-3316, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Mr Charles Liu, City University of Hong Kong   Transient Stability of Grid-Connected Converters: Effects of Synchronization Control, Output Regulation, and Converter Interaction Mr Charles Liu, City University of Hong Kong   Abstract: In the past decades, power electronics converters have been increasingly integrated into power grids. Generally, grid-connected converters exhibit nonlinear dynamics, thus inevitably resulting in the risk of transient instability. This talk will discuss the effects of the nonlinear behavior of grid-connected converters on their transient stability. Specifically, the talk focuses on dynamics in three scales: synchronization control, output regulation, and converter interaction. The conventional methods of power electronics address these dynamics in a separate and linear way. However, such a standard approach becomes invalid for the problem of transient stability. The talk will employ nonlinear methods to explain the mechanisms behind the rich oscillation phenomena of grid-connected converters. Moreover, the analysis is design-oriented and consequently, yields practical design guidance for enhancing transient stability.   Speaker’s Bio:Chao Charles Liu is currently pursuing the Ph.D. degree in the Department of Electrical Engineering, City University of Hong Kong, Hong Kong. He received the B.S. and M.S. degrees in electrical engineering from Wuhan University, Wuhan, China, in 2018 and 2021, respectively. His research interests include transient stability of grid-connected converters, applications of nonlinear dynamics, and smart meter data analytics.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/

PolyU x NuttyShell Cybersecurity CTF 2025

Competition Info 19 April 2025, 8:00PM HKT - 21 April 2025, 8:00PM HKT Mode: Online (The system will operate for 48 hours continuously, and participants can access it anytime during the contest)   Contest Information https://2025.polyuctf.com/

Seminar on "Cybersecurity of Multiagent Systems: Susceptibility Against Defense and Trade-offs with Privacy Guarantees" by Mr Shiyong Zhu

Date: 11 April 2025, Friday Time: 4:30 pm Venue: Room FYW-3316, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Mr Shiyong Zhu, City University of Hong Kong Cybersecurity of Multiagent Systems: Susceptibility Against Defense and Trade-offs with Privacy Guarantees Mr Shiyong Zhu, City University of Hong Kong   Abstract: Abstract: Cybersecurity has in recent years emerged as a paramount concern in the design and operation of industrial systems and civil infrastructures, due mainly to their susceptibility to malicious cyber-attacks which take advantage of the vulnerability of communication networks and IT devices. This seminar will present several control-theoretic perspectives on the cybersecurity of multiagent systems, with particular emphasis on the system susceptibility against defenders, and tradeoffs between security and privacy. The analytical results provide several theoretically grounded yet practical indicators for both attackers and defenders to weigh the pros and cons subject to, e.g., agent dynamics, strongly controllable subspaces, weakly observable subspaces, network topologies, and privacy levels.   Speaker’s Bio: Shiyong Zhu is currently pursuing the Ph.D. degree with the Department of Electrical Engineering, City University of Hong Kong, Hong Kong. His current research interests are cybersecurity and privacy of cyber-physical systems, and explicit computation for the minimal control nodes over networks. From the PhD study, he has held the visiting student positions with Princeton University, USA, Lund University, Sweden, and the Tokyo Institute of Technology, Japan. Mr. Zhu is a recipient of Outstanding Thesis Award from the International Consortium of Chinese Mathematicians (ICCM), the Chinese Association of Automation (CAA), and Jiangsu Province, China. He is also an invited Reviewer of the Mathematical Reviews of the American Mathematical Society.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/

Seminar on "Impedance-Based Approach for Stability Analysis in Inverter-Dominated Power Systems" by Dr Bei Sun

Date: 28 March 2025, Friday Time: 4:30 pm Venue: Y5-305, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Dr Bei Sun, City University of Hong Kong   Impedance-Based Approach for Stability Analysis in Inverter-Dominated Power Systems Dr Yue Zhu, City University of Hong Kong   Abstract: The high and growing penetration of inverter-based resources (IBR) in modern power systems has brought challenges to system stability, especially to small-signal stability reflected by the concerning oscillations. This seminar will discuss the impedance-based approach for oscillation root-cause tracing, tuning, and early warning. The new approach establishes the relationship between the impedance model and the conventional state-space model and opens up the path of using black-box impedance model to extract useful insights similar to those obtained from the white-box model. New technologies, such as using a single perturbation to restore the whole-system impedance model based on a hybrid data/model-driven method will also be introduced.   Speaker’s Bio: Dr. Yue Zhu is an Assistant Professor in the Department of Electrical Engineering, City University of Hong Kong (CityUHK). Prior to joining CityUHK, He was a Postdoctoral Research Associate in Department of Electrical and Electronic Engineering, Imperial College London. He received his B.Eng. and M.Sc. degrees from Zhejiang University and his PhD degree from Imperial College London. His research focuses on stability, dynamics, and control of large-scale inverter-dominated power systems, addressing critical challenges including system oscillations, data-driven impedance identification, and system strength assessment for connections of new inverter-based resources.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/

Seminar on "Population Dynamics of Frog Species under Seasonal Factors and Disease Transmission" by Dr Bei Sun

Date: 21 March 2025, Friday Time: 4:30 pm Venue: Y5-305, City University of Hong Kong Zoom Meeting ID: 899 0158 1173 Password: 123456 Speaker: Dr Bei Sun, Hong Kong Polytechnic University Population Dynamics of Frog Species under Seasonal Factors and Disease Transmission Dr Bei Sun, Hong Kong Polytechnic University   Abstract:Frog populations play a vital role in ecosystems, and their decline can significantly impact biodiversity and ecosystem stability. Their growth and reproduction are heavily influenced by seasonal climates and suitable ecological conditions. My research reviews stage-structured single-species population models, utilizing integral forms and partial differential equations under gamma and Dirac distributions. Guided by biological insights, I develop models that incorporate seasonal succession, competition, pathogen transmission, and mating behaviors. Using theories of monotone dynamical systems, global attractors, persistence, coexistence states, and basic reproduction numbers, I analyze key properties and global dynamics. Numerical simulations validate theoretical findings, assess parameter sensitivity, and evaluate factors influencing population dynamics.   Speaker’s Bio:Dr. Bei Sun received her Ph.D. in Applied Mathematics from the Hong Kong Polytechnic University in February 2025, following a master’s degree in applied Statistics from Northeastern University in 2021. With an interdisciplinary background in mathematics and statistics, her research focuses on applied dynamical systems, differential equations, mathematical epidemiology, and theoretical biology. She has published five papers in reputable international journals, including Mathematical Biosciences, Journal of Mathematical Biology, and Journal of Biological Systems.   WEBINAR WEBSITE: https://www.ee.cityu.edu.hk/~cccn/webinar/