Events Calendar

Astani CEE Department Seminar

Speaker: Ioannis A. Kougioumtzoglou , University of Liverpool

Talk Title: Wavelet Techniques & Path Integral Methods for Diverse Civil Engineering Applications

Abstract: Limitations pertaining to available information and the interpretation of underlying mechanisms, as well as inherent uncertainty and nonlinearity of critical engineering problems, have necessitated the study of nonlinear systems with stochastic parameters, input and initial/boundary conditions. In such cases, a stochastic approach constitutes a rational basis for modeling, analysis, design, monitoring and maintenance of resilient complex engineering systems. Further, stochastic dynamics has been the focus of diverse engineering and scientific disciplines for more than a century. Consequently, theoretical research has already led to seminal advancements towards analyzing and predicting the stochastic behavior of complex nonlinear dynamic phenomena. Nevertheless, the development of novel mathematical tools and of potent signal processing techniques, originating from computer science, applied mathematics and theoretical physics, offers a new framework for addressing complex problems for the first time and even posing new challenging questions.

In this regard, in the first part of the seminar talk, recent work related to the development of signal processing techniques for spectral analysis, stochastic modeling, and nonlinear system joint time/space-frequency response determination and parameter identification will be presented. A common denominator of the above techniques is the use of wavelets, and in particular, generalized harmonic wavelets which have proven to be particularly useful for engineering dynamics/mechanics related applications due to their non-overlapping, box-shaped frequency spectrum, their orthogonality properties, and the convenience of combining harmonic balance with statistical linearization techniques. Further, ongoing work related to the development of signal processing techniques which couple the localization capabilities of wavelets with compressive sensing methodology features for handling cases where available/measured data are highly sparse/incomplete will be delineated as well. Current and potential applications include translating (limited/incomplete/sparse and non-stationary) raw data into engineering load models and system/material properties, vibration diagnostics and mitigation, damage detection/assessment, cost-efficient structural health monitoring, and real-time risk optimization and decision making towards addressing the big challenge of analysis/design and operation of resilient and intelligent complex systems and civil infrastructure.

In the second part of the seminar talk, recent work related to the development of uncertainty quantification techniques for efficient response determination and reliability assessment of complex nonlinear systems will be presented. A common denominator of the above techniques is the use of path integrals. In this regard, it is noted that although path integrals have revolutionized the field of theoretical physics, the engineering community has neglected their potential as a potent uncertainty quantification tool. Current and potential applications include response analysis and reliability assessment of engineering systems following the versatile Preisach (hysteretic) model (e.g. smart materials), or modelled using fractional derivative elements (e.g. viscoelastic materials), as well as the determination of the capsizing probability of a ship model. Overall, it is shown that the path integral constitutes a versatile tool which can treat complex engineering problems and potentially address current and future challenges in engineering mechanics, such as nonlinearity and stochasticity at a multi-physics/scale level.


Biography: Dr. Ioannis Kougioumtzoglou (IK) is a Lecturer (Assistant Professor equivalent) in Uncertainty & Engineering, and a member of the Institute for Risk and Uncertainty and of the Centre for Engineering Sustainability in the School of Engineering, University of Liverpool, UK. He obtained his M.Sc. (2009) and Ph.D. (2011) degrees from the Civil and Environmental Engineering department of Rice University, TX, USA, under the supervision of Professor Pol D. Spanos. He also holds a five-year Diploma (2007) in Civil Engineering from the National Technical University of Athens (NTUA), Greece.

IK's primary research interests focus on the general area of Uncertainty Quantification and Modeling/Analysis of Complex Systems with applications mainly in Civil/Mechanical Engineering & Engineering Mechanics, and in diverse disciplines such as Financial Mathematics. Specifically, the development of numerical and/or analytical techniques for Stochastic Engineering Dynamics/Mechanics constitutes one of the main research themes. Systems exhibiting nonlinear/hysteretic behavior and/or exposed to hazard/risk inducing conditions are of particular interest.

IK has been awarded several scholarships for outstanding academic performance from the National State Scholarships Foundation (Greece), the Eugenides Foundation (Greece) and the Hellenic Professional Society of Texas (USA). He has also received an invited Visiting Professor appointment at the Structural Engineering Department, University of Sao Paulo, sponsored by the Sao Paulo State Research Funding Agency (Brazil). He is a member of the Engineering Mechanics Institute (EMI), an associate member of the American Society of Civil Engineers (ASCE), and a Registered (Licensed/Chartered) Professional Civil Engineer in Greece. He is the co-Editor of the Encyclopedia of Earthquake Engineering (Springer) and currently serves as a Guest Editor for two Special Issues in the Journal of Probabilistic Engineering Mechanics and in the International Journal of Reliability and Safety. He currently supervises and co-supervises nine PhD students, many of them in multi/cross-disciplinary topics.


Host: Astani CEE Department

Location: Kaprielian Hall (KAP) - 209

Audiences: Everyone Is Invited

Contact: Cassie Cremeans