Abstract: The phase or argument of a complex number is an important concept known to most of the university students in STEM. We will begin the talk by asking the following question:
• What are the phases of a complex matrix?
A novel answer to this question will then be followed by further questions:
• What are the phases of a MIMO system?
• What are the phases of a nonlinear system (e.g., robot, UAV)?
• What are the phases of a dynamic network (e.g., power network, social network)?
• What are the phases of a data set (e.g., data cube)?
These are the questions to be answered in the newly developed phase theory for complex systems, in which we will also be shown why the phases are important in system analysis and data analytics. In this talk we will give a glimpse of the phase theory and we will also give some future speculations.

Biography: Li Qiu received his Ph.D. degree in electrical engineering from the University of Toronto in 1990. After briefly working in the Canadian Space Agency, the Fields Institute for Research in Mathematical Sciences (Waterloo), and the Institute of Mathematics and its Applications (Minneapolis), he joined Hong Kong University of Science and Technology in 1993, where he is now a Professor of Electronic and Computer Engineering. Prof. Qiu’s research interests include system, control, optimization theory, and mathematics for information technology, as well as their applications in manufacturing industry and energy systems. He is also interested in control education and coauthored an undergraduate textbook “Introduction to Feedback Control” which was published by Prentice-Hall in 2009. He served as an associate editor of the IEEE Transactions on Automatic Control and an associate editor of Automatica. He was the general chair of the 7th Asian Control Conference, which was held in Hong Kong in 2009. He was a Distinguished Lecturer from 2007 to 2010 and was a member of the Board of Governors in 2012 and 2017 of the IEEE Control Systems Society. He is the founding chairperson of the Hong Kong Automatic Control Association and a vice president of Asian Control Association. He is a Fellow of IEEE and a Fellow of IFAC.