Warren Distinguished Lecture Series
The Warren Distinguished Lecture Series is made possible by a generous, renewing gift by Alice Warren Gaarden in 1961. Since 1989, we have been bringing in accomplished researchers and speakers from around the world to share their work with students, faculty, and friends of CEGE. Please join us for these lectures!
- Join us in person in the George J. Schroepfer Conference Theater, 210 Civil Engineering Building, Fridays at 10:10 a.m., unless otherwise noted. Coffee and refreshments served.
- Join us via Zoom. Registration is required. Link information will be sent when you register.
- Recordings are available on the CEGE YouTube channel, Warren Lecture Series playlist , where you can also search past lectures.
Past Warren Lectures
Using detailed elemental analysis of airborne particulate matter to quantify local and global dust sources
Shankar Chellam
Department of Civil and Environmental Engineering
University of Houston
Abstract
Airborne particulate matter contributes to haze, acid rain, global climate change, asthma and other respiratory ailments, cardiopulmonary disease, and decreased life expectancy. For the past approximately 10-years, we have successfully quantified emissions from petroleum refining operations, tailpipe and non-tailpipe emissions from light-duty motor vehicles, and formation of secondary sulfate aerosols. More recently, we have demonstrated that long-range transport of dust from North Africa occasionally increases fine and coarse particulate matter concentrations in Houston. This was accomplished by systematic and highly sensitive measurements of representative elements as well as transition and lanthanoid metals in ambient urban aerosols and source samples using inductively coupled plasma – mass spectrometry. The seminar will cover two topics: (1) the routine and episodic atmospheric enrichment of rare earth elements in Houston that was traced to crude oil cracking catalysts and (2) trans-Atlantic transport of dust from the Sahara-Sahel region which occasionally increases ambient aerosol concentrations in Houston.
Evaluation and Repair of Steel Bridge Structures with Fatigue Induced Damage
Mark D. Bowman
School of Civil Engineering
Purdue University
Abstract
Steel bridge structures are commonly used throughout the United States. Many of these structures have been in service for more than fifty years, and some of these structures are showing signs of distress through fatigue cracks that have developed. The initiation of a fatigue crack, while undesirable, does not necessarily mean that the bridge is beyond repair, and retrofit or repair measures to extend the useful service life of the bridge should be implemented if it is economically and operationally desirable. However, reliable information is needed to both evaluate the extent of the fatigue damage that has occurred and to subsequently recommend an effective repair. An experimental study was recently completed to explore the fatigue resistance of two different bridge details that are commonly encountered: tack welds left in place on primary or secondary members and details susceptible to distortion-induced cracking. The results of the study indicate that the fatigue resistance of members with tack welds may be greater than previously believed and often may not need to be retrofitted, while the behavior of details subjected to distortion-induced cracking are difficult to evaluate but can often be effectively repaired by using a stiffening detail that reduces the out-of-plane distortion.
Bio
Mark D. Bowman, Professor of Civil Engineering, Purdue University, has been a member of the Structural Engineering faculty for thirty-two years. He has BSCE and MSCE degrees from Purdue University and a PhD from the University of Illinois at Urbana-Champaign. Prior to his doctoral studies, Dr. Bowman worked as a structural design engineer for Precast/Schokbeton, Inc. in Kalamazoo, Michigan for two years. His research and refereed publications are primarily in the areas of steel design, fatigue and fracture, bridge engineering, and the behavior of structural connections. He has taught several courses on both structural analysis and the design of steel structures, and he has been involved in a lead role in the development and teaching of the Bridge Engineering class at Purdue for the last se veral years. He has been active in conducting several research projects for the INDOT, FHWA, NCHRP, NSF, Pankow Foundation, and other agencies over a broad range of different topics. These research projects range from laboratory experimental testing of individual members to field monitoring and structural evaluation of full bridge structures. Dr. Bowman has been active in technical committees in the American Society of Civil Engineers, the American Institute of Steel Construction, American Welding Society, the American Railway Engineering and Maintenance-of-Way Association, and the Transportation Research Board. At Purdue, he is presently serving as the Director of the Bowen Laboratory and as a member of the University Residence Review Committee.
"Big" Data as a Foundation for Measuring and Improving Public Transport Operations
Robert Bertini
Department of Civil and Environmental Engineering
Portland State University
Abstract
Over the past 20 years the transportation engineering field has witnessed a data revolution — some might say that we have transitioned from a data "desert" to a data "ocean." Intelligent transportation systems data can be archived and managed carefully to provide a platform for analysis, visualization and modeling. With increasing attention being paid to performance and financial issues related to the operation of public transportation systems, it is necessary to develop tools for improving the efficiency and effectiveness of service offerings. With the availability of high resolution archived stop-level bus performance data, it is shown that a bus trip time model and a bus stop spacing model can be generated and tested with the aim of minimizing the operating cost while maintaining a high degree of transit accessibility. In this research, two cost components are considered in the stop spacing model including passenger access cost and in-vehicle passenger stopping cost, and are combined and optimized to minimize total cost. A case study is conducted using one bus route in Portland, Oregon, using one year's stop-level archived Bus Dispatch System (BDS) data provided by TriMet, the regional transit provider for the Portland metropolitan area. Based on previous research considering inbound trips over the entire day, the theoretical optimized bus stop spacing was about 1,200 feet, as compared to the current value of 950 feet. Trade-offs will be discussed as well as an estimate of transit operating cost savings based on the optimized spacing. Given the availability of high resolution archived data, the paper illustrates that this modeling tool can be applied in a routine way across multiple routes as part of an ongoing service planning and performance measurement process.
Solids production in porous media Experiments, models and simulations
Euripides Papamichos
Department of Civil Engineering
Aristotle University of Thessaloniki
Abstract
Solids production in porous media such as sand or chalk remains a major issue for conventional oil production. In sandstone fields, sand quantification is becoming an important analysis tool even in sand controlled wells. A review of recent advances in experiments, theory, and analysis in sand rate quantification will be presented. Laboratory experiments concentrate on the effects of water breakthrough, multiphase flow, and the scale effect on solids production rate. Theoretical models concentrate on the coupled description of the erosion-mechanical problem using finite element and discrete element analyses. In chalk, new completion techniques like acidizing are applied to improve stability and productivity. Laboratory experiments in acidized chalk tests will be presented and the stability of acidized boreholes is analyzed.
Bio
Euripides Papamichos is Professor of Mechanics and Director of the Mechanics of Materials Laboratory at the Department of Civil Engineering at the Aristotle University of Thessaloniki, Greece. He is also a Senior Scientist at the Formation Physics Department of SINTEF Petroleum Research in Trondheim, Norway. His work includes a variety of petroleum- related geomechanical problems such as sand and chalk production and mechanics, reservoir compaction and subsidence, reservoir geomechanics, and core damage. He has expertise in constitutive and numerical modeling, in thermo-poro-elasto-plasticity, damage mechanics, and micromechanics of granular materials. He is author of over 120 scientific publications and four books and entertains more than 1200 citations in his work. He has been Principal Investigator of over 20 industry and state sponsored research projects. He holds a Diploma in Mining and Metallurgical Engineering from the National Technical University of Athens, Greece, and MSc and PhD in Civil Engineering under Prof. I Vardoulakis from the University of Minnesota, U.S.A. Previously he worked as a Research Scientist for Elf Aquitaine Production in Pau, France and a Research Associate at the Univ of Colorado at Boulder, Colorado, U.S.A.
View Papamichos's presentation
2013 Vardoulakis Lecture
This lecture is named in honor of Ioannis Vardoulakis, a former faculty member and internationally renowned researcher in geoengineering, who tragically passed away in September 2009. Prof. Vardoulakis joined the Department of Civil Engineering at the University of Minnesota as an assistant professor in 1980, where he earned the rank of professor in seven years. In 1990, he returned to Greece and he was a Professor of Applied Mathematics and Physics at the National Technical University of Athens. He received a diploma of civil engineering in structures from the National Technical University of Athens, Greece in 1972, and a doctor of engineering (with highest honors) in soil mechanics from the University of Karlsruhe, Germany in 1977. He was born on February 28, 1949, and he passed away on September 19, 2009.
Fluid-Structure Interaction (FSI): methods, applications
Anvar Gilmanov
Research Associate
St. Anthony Falls Laboratory
University of Minnesota
Abstract
Over the past decades, problems involving the coupled response of structures and flows have become of increasing interest in various engineering areas such as aeronautical engineering, coastal engineering, and biomedical engineering. Due to nonlinear properties of fluid and deformable structures, only numerical approaches can be used to solve such problems. Simulation of the fluid-structure interaction where the dynamics of these flows dominates poses a formidable challenge to even the most advanced numerical techniques, and is currently at the forefront of ongoing work in computational fluid dynamics. I will talk about approaches and techniques for solving FSI problems. Among common existing methods to solve FSI problems, an efficient technique with focusing on modeling of large displacements/deformations of thin shells in the fluid flow will be discussed. This technique is based on the combination of Hybrid Immersed Boundary Method (HIBM) as a fluid solver and Finite Element Method (FEM)/Material Point Method (MPM) as a solid structure solver. The proposed method is a powerful tool to investigate complex FSI problems and has been applied to a wide number of FSI problems. I will provide some of applications in biomechanics (cardiovascular) and aeronautic areas that have been modeled by this methodology.
Mechanics of Nanomaterials: The Pivotal Role of Molecular Interactions
Dinesh R. Katti, PH.D, P.E.
Interim Chair and Professor
Department of Civil and Environmental Engineering
North Dakota State University, Fargo, ND
Abstract
This talk will expound the dominant role of molecular interactions on the mechanics of nanomaterials that include biological and synthetic nanocomposites and smectite clays. The presentation will focus on four nanomaterials, 1) nacre, the inner layer of seashells, 2) bone, 3) polymer-clay-nanocomposites and 4) swelling clays. The mechanisms that control mechanical properties of the nanomaterials are elucidated using innovative multiscale modeling and experimental techniques. The important discoveries and key findings made by the Katti group that reveal the important mechanisms that lead to unique properties exhibited by these nanomaterials will be described. The modeling and experimental techniques developed for these studies bridge wide range of length scales from molecular to nano/micro to macroscale using ab-inito, molecular dynamics, discrete element and finite element for modeling; and spectroscopy, electron microscopy and nanomechanical testing for experimental investigation. These techniques have led to simulations based materials design of synthetic nanocomposite materials. In nanocomposites, the nanoscale proximity of minerals and macromolecules alter the mechanics of the macromolecules, thus strongly influencing the mechanics of nanomaterials at the macroscale. This phenomenon is observed in naturally occurring nanocomposites such as seashells and bone as well as engineered nanocomposites and is thus a characteristic of nanoscale material systems.
Bio
Prof. Dinesh Katti received his B.S. degree in civil engineering from National Institute of Technology, Srinagar, India, M.S. degree in geotechnical engineering from Indian Institute of Technology, Bombay, India and Ph.D. in civil engineering from University of Arizona, Tucson. After receiving his doctoral degree in 1991, he joined the industry as a geotechnical consulting engineer for two companies in the Seattle area, Dames and Moore and Terra Associates where he worked on over 125 projects. He joined North Dakota State University in the department of civil engineering in the fall of 1996 as an associate professor. In 2002 he was promoted to the rank of full professor. He served as chairman of the department of civil engineering at NDSU from 2004 to 2009. During the same period, he served as Associate Dean of Research for the College of Engineering and Architecture. Since fall 2013 he serves as interim chair of the department.
Prof. Katti's research expertise is in the area of multiscale modeling of materials. His research contributions are in a number of materials systems such as swelling clays, nacre, bone, polymer clay nanocomposites, bone tissue engineering and oil shales. His research is supported by NSF, USDA and DoE. He has authored or coauthored over 150 papers, 3 books and 7 book chapters. He also holds 3 provisional patents. He was awarded the 2011 John R. Booker excellence award from IACMAG for "major contributions to geomechanics". He has also received the Fred Waldron award for excellence in research in 2013. He has served as chair of the Engineering Mechanics Institute Poromechanics and Properties of Materials Committees, and currently chairs the EMI Molecular Scale Modeling and Experimentation Committee. He is also an associate editor of two EMI journals and has been instrumental in organizing symposium series on biological and biologically inspired materials for ASCE EMD/EMI for over a decade.
A Priority System for Multi-Modal Traffic Signal Control
Larry Head
Associate Professor and Department Head
Department of Systems & Industrial Engineering
University of Arizona
Abstract
There are many users of signalized traffic intersections including passenger vehicles, commercial vehicles/trucks, pedestrians, bicycles, transit buses, light rail vehicles, snowplows, and emergency vehicles such as fire trucks and ambulances. Traditional approaches to traffic signal control are centered on general vehicles with either accommodations for other modes or exceptions for special considerations such as emergency vehicles. We have developed a unified framework for multi-modal traffic signal control that simultaneously considers the needs of different modal users. This framework is based on a mathematical optimization model where each mode can request service using priority requests. In addition to modal users, system-operating principles such as coordination are included in the decision framework. The system has been developed and tested using both microscopic traffic simulation and in a live network of six intersections in Anthem, Arizona using emerging technology developments in Connected Vehicle systems.
Short Biography
K. Larry Head, Ph.D. is currently the Department Head and an Associate Professor of Systems and Industrial Engineering at The University of Arizona. He received his Ph.D. in Systems Engineering from the University of Arizona in 1989. He has 18 years of research and development experience related to the design and implementation of adaptive traffic signal control (RHODES), transit priority, emergency vehicle priority, and traffic management systems. From 1996 to 2003 he was a Senior Vice President at a business unit of Siemens where he lead the development of advanced traffic management systems including special traffic signal priority systems for light rail that is used in Salt Lake City, Houston, and Phoenix. He is the Chair of the Transportation Research Board's Traffic Signal Systems Committee (AHB25), and a member of INCOSE, INFORMS, IEEE, IIE and ITE.
Stochastic Virtual Test Systems for Continuous Fiber Composites
Brian Cox
Teledyne Scientific & Imaging, LLC
Thousand Oaks, California
Abstract
We will describe a Virtual Test system for continuous fiber composites. The virtual tests draw from a new wave of advanced experiments and theory that address physical, mathematical, and engineering aspects of material definition and failure prediction. The methods go far beyond currently standard tests and conventional FEM analysis to challenge our conception of what can constitute a practicable engineering approach. Some emphasis will be given to high temperature ceramic matrix composites with textile reinforcement.
Development has been organized as a "pipeline" that links the separate disciplinary efforts of groups housed in seven institutions spread across the US. The main research steps are: high resolution three-dimensional (3D) imaging of the microstructure, statistical characterization of the microstructure, formulation of a probabilistic generator for creating virtual specimens that replicate the measured statistics, creation of a computational model for a virtual specimen that allows general representation of discrete damage events, calibration of the model using room and high temperature tests, simulation of failure, and model validation. Key new experiments include digital surface image correlation and µm-resolution 3D imaging of the microstructure and evolving damage, both executed at temperatures exceeding 1500°C. Conceptual advances include using both geometry and topology to characterize stochastic microstructures. Computational methods include new probabilistic algorithms for generating stochastic virtual specimens and a new Augmented Finite Element Method (A-FEM) that yields extreme efficiency in dealing with arbitrary cracking in such heterogeneous materials. The challenge of relating variance in engineering properties to stochastic microstructure in a computationally tractable manner, while retaining necessary physical details in models, is discussed.
Uncertainty Quantification for Mechanical Systems Reliability Management
Sankaran Mahadevan
John R. Murray Sr. Chair in Engineering
Professor of Civil and Environmental Engineering, Professor of Mechanical Engineering
Director, NSF-IGERT Program in Reliability and Risk Engineering and Management
Vanderbilt University, Nashville, TN, USA
Abstract
This talk will focus on uncertainty quantification (UQ) in performance prediction and risk assessmentmanagement of engineered systems. Model- based simulation becomes attractive for systems that are too large and complex for full-scale testing. However, model-based simulation involves many approximations and assumptions, and thus confidence in the simulation result is an important consideration in risk-informed decision-making. Sources of uncertainty are both aleatory and epistemic, stemming from natural variability, information uncertainty, and modeling approximations. The presentation will draw on illustrative problems in aerospace, mechanical, civil, and environmental engineering disciplines to discuss recent research on (1) quantification of various types of errors and uncertainties, particularly focusing on data uncertainty and model uncertainty (both due to model form assumptions and solution approximations); (2) information fusion from multiple sources (models, tests, experts), multiple model development activities (calibration, verification, validation), and multiple formats; and (3) use of UQ for risk-informed decision-making throughout the life cycle of engineered systems, such as testing, design, operations, health and risk assessment, and risk management.
Bio
Professor Sankaran Mahadevan Has More Than Twenty-Five Years Of Research And Teaching Experience In Reliability And Risk Analysis Methods, Design Optimization, Structural Health Monitoring, And Model Verification, Validation And Uncertainty Quantification (V&V And Uq) Methods. His Research Has Been Extensively Funded By Nsf, Nasa, Faa, Doe, Dod, Dot, General Motors, Chrysler, Union Pacific, American Railroad Association, And Sandia, Idaho, Los Alamos And Oak Ridge National Laboratories. His Research Contributions Are Documented In More Than 400 Technical Publications, Including Two Books And 170 Journal Articles. He Has Directed 38 Ph.D. Dissertations And 24 M. S. Theses, And Has Taught Many Industry Short Courses On Reliability And Risk Analysis Methods. He Has Served As Chair Of Several Technical Committees And Conferences In Asce And Aiaa, As Associate Editor And Editorial Board Member For Several Journals, And As Keynote Speaker In Several Conferences. He Has Received Awards For Research, Teaching And Service From Several Organizations Such As Asce, Aiaa, Asme, Sae, And Nasa.
Professor Mahadevan obtained his B.Tech from Indian Institute of Technology, Kanpur, M.S. from Rensselaer Polytechnic Institute, Troy, NY, and Ph.D. from Georgia Institute of Technology, Atlanta, GA.
Building Sustainable and Healthy Cities: A Social-Ecological-Infrastructural Systems Approach
Anu Ramaswami
Charles M. Denny Jr. Chair Professor of Science Technology & Public Policy
Hubert H. Humphrey School of Public Affairs
University of Minnesota
Abstract
Cities would not function without infrastructures that provide water, energy, food, shelter, waste management and mobility services to more than half the world's people living in them today.
How do people, infrastructures and the natural system interact with each other across spatial scale to shape multiple sustainability outcomes for cities – including environmental, economic, risk/resiliency and public health outcomes? How can we better design our urban infrastructure systems to achieve these multiple sustainability outcomes? Who governs the design and diffusion of these more sustainable infrastructure systems in society – and what motivates them to do so (or not)?
These important questions will be explored using a novel social-ecological- infrastructural systems (SEIS) framework for developing sustainable, healthy and climate-resilient cities. The framework will be applied to describe recent efforts to measure and mitigate greenhouse gas (GHG) emissions associated with cities, using a portfolio of interventions including: infrastructure design/technology interventions, as well as behavior change and policy interventions.