Friday, September 13th, 2019
Speaker: Dr. Mohamed S. Ghidaoui, Chinese Estates Professor of Engineering, Chair Professor, Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology
Title: “Time reversal of waves and defect detection in underground water infrastructure”
Time: 9:00 – 10:00 AM
Location: School of Kinesiology and Health Studies, Rm. 101
M.S. Ghidaoui is the Chinese Estates Professor of Engineering and Chair Professor in the Department of Civil and Environmental Engineering at the Hong Kong University of Science & Technology (HKUST). He received the BASc (1989), MASc (1991) and Ph.D. (1993) all in civil engineering, University of Toronto, Canada. His general interests are in the fields of hydraulics, water resources and environmental fluid mechanics. In particular, unsteady friction and turbulence in waterhammer; defect detection in pipes using waterhammer (transient) waves; numerical modelling of surface and closed conduit flows; and stability of shallow shear flows. Currently, he leads a large-scale theme-based project on smart urban water supply systems (Smart UWSS). He is the editor of the Journal of Hydraulic Research, which is the flagship journal of IAHR, and served as its associate editor for 15 years. Under his leadership, the journal achieved its highest ever impact factor. He is also the associate editor of the Journal of Hydraulic Engineering, ASCE; and Journal of Hydro-environment Research, IAHR-APD. He is an editorial board member of the Theoretical & Applied Mechanics Letters (TAML), Chinese Academy of Sciences and The Chinese Academy of Theoretical and Applied Mechanics and served as an advisory board of the Journal of Hydroinformatics for 12 years. He served as the chair of IAHR’s Fluid Mechanics Committee from 2013 to 2018. He is a founding member of the IAHR Hong Kong Chapter and served as its chair over 10 years ago. He chaired the university senate committee on research and university senate committee on undergraduate studies. His awards include the Arthur Ippen Award, IAHR; the Albert Berry Memorial Award, American Water Works Association; and Hilgard Award for best paper (runner-up), Journal of Hydraulic Engineering, ASCE. He received the Outstanding Faculty Award, HKUST. In addition, Prof Ghidaoui received two teaching excellence awards from the school of engineering at HKUST.
Providing an overview of the intriguing concept of time reversal (TR) of waves. Examples show how TR has been instrumental in many fields and how TR underpins the foundation of a variety of practical equipment. Applications include, for example, some approaches for destroying tumors and kidney stones as well as methodologies for detecting defects in solids, for pinpointing underground mineral deposits, and for assisting long distance communication.The recent experimental and theoretical research by the speaker’s group on TR of compressibility waves in pressurized elastic and visco-elastic pipes with frequencies ranging from a few Hz to tens of kHz will be elaborated. The challenging effect of damping on TR and how such effects are dealt with will be discussed. How the TR property can been exploited to develop robust, efficient and high resolution defect detection in water supply lines will be highlighted. Illustrative examples of defect detection in both the lab and field context will be provided.