Warren Distinguished Lecture Series

Banners that illustrate CEGE's mission and vision hang in the Charles Fairhurst Rotunda

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!

Upcoming Events

Mar 15  Roman Y Makhnenko, Civil & Environmental Engineering, University of Illinois Urbana-Champaign
Mar 22  Joseph Vantassel, Civil and Environmental Engineering, Virginia Tech
Mar 29  Elowyn Yager, Civil & Environmental Engineering, University of Idaho
Apr   5  Kyle Doudrick, Civil & Environmental Engineering & Earth Sciences, University of Notre Dame
Apr 12  Tim Strathmann, Civil & Environmental Engineering, Colorado School of Mines
Apr 19  Henry Liu, Civil and Environmental Engineering, and Mechanical Engineering, University of Michigan 
Apr 26  Dimitrios Lignos, Resilient Steel Structures Laboratory, École Polytechnique Fédérale de Lausanne (EPFL),  Lausanne (Switzerland)

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Past Warren Lectures

Warren Lecture with Srijan Aggarwal

Srijan Aggarwal
Civil, Geological, and Environmental Engineering, University of Alaska Fairbanks
"Water and Sanitation Infrastructure in Remote Alaska Communities: Challenges and Solutions"

ABSTRACT:  While 99.6% of Americans can mindlessly turn on a tap in their homes, more than 1 million Americans, equivalent to the country’s seventh largest city, lack access to running water. In Alaska, 4% of households overall and 20% of rural homes lack access to in-home plumbing facilities and, consequently, running water and sewer services - the highest rate in the country. The COVID-19 pandemic has renewed attention to the importance of secure water and sanitation services in protecting human health. Many remote Alaskan communities are particularly vulnerable to infectious disease transmission because of inadequate water and sanitation services. The well-being of Alaskan Indigenous communities depends on access to safe drinking water. However, water pollution has remained a reality for many of these communities due to inadequate infrastructure, as well as naturally occurring and anthropogenic pollutants. As the climate warms, environmental changes will likely exacerbate water contamination problems by releasing entombed microorganisms, ancient organic carbon, nutrients, and metals through thawing of permafrost and melting of glaciers. In addition, a number of socio-economic, physical, and infrastructure factors in these predominantly Alaska Native communities (e.g., remoteness, household overcrowding, climate change impacts, limited medical facilities, and high prevalence of chronic diseases) exacerbate the impacts of inadequate water and sanitation and contribute to the potential for more severe disease outcomes, such as due to COVID-19. Aggarwal presents results from several water related projects he is involved in that will highlight some of the water quality issues in remote and rural Alaskan communities, infrastructure challenges including high per capita energy costs for water treatment, and development of potential solutions (e.g., decentralized water systems) being pursued by the state agencies that have techno-economic feasibility in harsh Arctic climate and are also culturally sensitive and acceptable.

Warren Lecture with Yanfeng Ouyang

Yanfeng Ouyang
Civil and Environmental Engineering, University of Illinois at Urbana-Champaign
Demand-Responsive Mobility Services: From Flexible Transit to Ridesharing

ABSTRACT: Yanfeng Ouyang presents a few efforts on designing demand-responsive mobility service systems that provide door-to-door transportation in cities. These systems include combinations of traditional transit, nonshared taxis, paratransit services (such as dial-a-ride), and newer forms of ridesharing (shared taxis or carpooling) used by crowd-sourced companies like DiDi and Uber. Operational similarities and differences of these systems will be discussed, along with a quantitative comparison of their resource requirements (for example, the required operating fleet size) and passengers’ expected level of service (for example, average door-to-door travel time). Integration of emerging mobility services with traditional transit systems will also be discussed. Ouyang also shows how these models can help mobility service providers and government agencies systematically explore operating, pricing, and regulatory strategies to enhance sustainability of urban transportation.

 

Three-minute Thesis Contest

CEGE 3MT (3 minute Thesis Contest) 2021

Graduate students from our programs competed by sharing their thesis research in just three-minutes.

  • Shi’an Wang: "Regulating mixed traffic flow: the power of automated vehicles"
  • Brandon Sloan: "Do plants drink responsibly?"
  • Sajad Vahedizade: "Blind spots of snowfall: Can satellite data deceive us?"
  • Mingfeng Shang: "Are lower-level automated vehicles (AVs) beneficial to the traffic flow?"
  • Jiyong Lee: "Small vs large sandwaves: What crafts the shape of a river?"
  • Svetlana Baranova: “High order imperfect interface modeling of thin layers”
The rules: Each presenter had exactly 3 minutes to make their pitch. They used only ONE static slide (no builds, animations, or embedded movies). At the end of all the presentations a panel of judges picked the winner and runner up and the audience (in person and remote) selected the “peoples choice.” The winner and runner-up will compete in the CSE competition Thursday, Oct. 21, 2021, 4-5:30 p.m. Keller Hall, Room 3-180 and on Zoom (participants must register, search CSE Three Minute Thesis Contest).

Warren Lecture with Michele Guala

Michele Guala
Civil, Environmental, and Geo- Engineering, University of Minnesota
"An Open Conversation about Sand Grain and Vortex Organization in Turbulent Flows"

ABSTRACT:  Remarkable geometrical and scaling similarities emerge when a turbulent boundary layer acts on a rough or erodible surface. Both sand grains and vortices self-organize into aggregates which exhibit general ramp-like patterns and hierarchies extending up to a significant fraction of the reference outer scale, e.g., the river depth or the boundary layer height. These aggregates represent ripples and dunes in rivers, and attached-eddy coherent structures in near surface atmospheric flows, respectively.

While their advection velocity displays systematic differences, leading to a scale-dependent migration of fluvial bedforms that we do not observe for coherent structures, the dependency on the shear velocity remains a hallmark feature of these aggregates. Not only that, the shear velocity also percolates down to the scaling of the respective elemental components, governing both the velocity of the moving grains and the maximum azimuthal velocity of the vortices in the flow. Hence, this qualitative comparative analysis between bedforms and flow-structures has some quantitative ramifications in the modeling, confirming that the shear velocity is indeed a star.

Guala concludes by highlighting a second order effect, represented by a weak dependency on the outer scale observed both in the scaling of bedform migrating velocity and in the largest coherent structures of the flow. The qualitative flow structures – bedforms comparison could then be extended: in the same way attached-eddy structures may be imagined as frozen into dunes, so very-large-scale motions may end up being frozen into alternate distortions of the mean river bed. 

 

Warren Lecture with Kimberly Hill

Kimberly Hill
Civil, Environmental, and Geo- Engineering, University of Minnesota
"'Granular Mud' in Natural and Human Infrastructure Materials"

ABSTRACT: “Granular mud,” i.e., mixtures of particles and viscous-like fluids are ubiquitous in natural and man-made systems, from muddy geophysical flows to hot mixed asphalt and concrete. As we strive toward a “greener economy,” predicting their behaviors in asphalt compaction toward efficient processing becomes increasingly important given the wide-spread use of asphalt in our roadways. At the same time, and at a much greater scale, predicting behaviors of this granular mud in the form of rocky/muddy geophysical flows (debris flows) would help with hazard mitigation, particularly critical in the face of their increasing frequency and intensity under recent higher intensity storms. While we don’t typically think of such vastly different materials in the same context, we have found that considering them in a similar multiscale framework sheds light on both problems. 

Hill first presents these issues in the context of hot mixed asphalt compaction, particularly in mixture design toward increasing compaction efficiency. Likely because of the wide range of particle sizes, we find that a simple single phase model is not effective in capturing the mechanistic influence of specific components. However, when we model the particle dynamics specifically at two different scales using our new two-scale discrete (or distinct) element method approach we capture changes of the compaction efficiency to material additives and grain size distributions. At the same time, because of the nature of the DEM approach in representing the motion of and forces on individual particles, the model provides intuition on the mechanics involved. Hill ends with a brief discussion of her research team's ongoing experimental and field research in which they have begun to apply this approach to understand behaviors of debris flows (large rocky/muddy flows in steep regions) and various channelization signatures on alluvial fans.  

Warren Lecture with Ardeshir Ebtehaj

Ardeshir Ebtahaj
Civil, Environmental, and Geo- Engineering, University of Minnesota
"Unraveling Changes of Global Water Cycle using Satellite Data"

ABSTRACT: Satellite observations of the Earth’s radiation in microwave bands play an indispensable role, not only for unraveling the impacts of climate change on the global water cycle but also for accurate prediction of droughts and extreme storms. On the one hand, satellite remote sensing of the water cycle involves inversion of radiative transfer equations that link the amount of water in land and atmosphere to radiation intensity, observed by spaceborne radiometers at the top of the atmosphere. On the other hand, improved predictability of the hydrologic cycle requires optimal integration of satellite observations with the outputs of Earth System Models (ESMs). Ebtehaj presents recent advances in physically informed inversion of land emission models and in multi-satellite statistical learning for high-resolution remote sensing of soil moisture and snowstorms from space. Furthermore, he presents a new paradigm for satellite data assimilation over a Riemannian manifold equipped with the Wasserstein metric. Unlike classic approaches over the Euclidean space, this new framework can formally penalize geophysical biases in a non-Gaussian state space. The advantages of this approach for improved geophysical forecasts are demonstrated using chaotic dynamical systems, representing atmospheric circulation.

 

Warren Lecture with John Gulliver

John S. Gulliver
Civil, Environmental and Geo- Engineering, University of Minnesota
"Gismos for Stormwater Runoff"

ABSTRACT: Technology for stormwater treatment has different challenges from water treatment and wastewater treatment. Stormwater control measures need to be applied throughout the watershed, such that infrequent maintenance is needed. Second, the water to be treated tends to flow more infrequently than water or wastewater, resulting in a different paradigm for stormwater control measures. Gulliver discusses three technologies to assist in the choice of stormwater control measures: a falling head infiltrometer that can be used to determine the saturated hydraulic conductivity at multiple locations simultaneously; a baffle that will turn a standard sump into a stormwater control device; and an enhanced sand filter that will remove phosphate from stormwater runoff before it reaches the receiving water body.

Warren Lecture with Nikolaos Geroliminis

Nikolaos Geroliminis
EPFL Lausanne, Switzerland
"On the Inefficiency of Ride-sourcing Services Towards Urban Congestion"

ABTRACT: The advent of shared-economy and smartphones made on-demand transportation services possible, which created additional opportunities but added more complexity to urban mobility. Companies that offer these services are called Transportation Network Companies (TNCs) due to their internet-based nature. Ride-sourcing is the most notorious service TNCs provide. Little is known about the degree to which ride-sourcing operations interfere in traffic conditions. We experimentally analyze the efficiency of TNCs using taxi trip data from a Chinese megacity and an agent-based simulation with a trip-based MFD model for determining the speed. We investigate the effect of expanding fleet sizes for TNCs, passengers’ inclination towards sharing rides, and strategies to alleviate urban congestion. 

Warren Lecture with Andrew J Whelton

Andrew J Whelton
Civil Engineering and Environmental and Ecological Engineering, Purdue University
"Preventing Future Safety and Environmental Problems: Experiences of Polymers in Water Infrastructure Systems"

ABSTRACT: As buried water infrastructure in the U.S. continues to deteriorate, many communities are racing to replace and replace these assets. Many of these communities are choosing to repair pipes in place, or replace with polymer materials. This is also the case for building systems and new construction, where polymer material use can be 90% less costly than legacy materials and methods. Whelton describes his experience with polymer prevalence in water infrastructure systems and product failures, and recommends education to lessen the chance of future failures and health impacts.

Modeling Soil-Machine Interaction: Evolving Research on Evolutionary Plasticity Problems

James Hambleton
Civil and Environmental Engineering, Northwestern University
"Modeling Soil-Machine Interaction: Evolving Research on Evolutionary Plasticity Problems"

ABSTRACT: Problems in soil-machine interaction (SMI) are ubiquitous on Earth, and they are beginning to play important roles elsewhere as we explore and perhaps eventually colonize the moon and other planets. Irrespective of the application, SMI problems are “evolutionary plasticity problems” defined characteristically by the presence of large, plastic deformation as machine components come into contact with soils. Hambleton discusses the formulation and validation of efficient analytical and semi-analytical techniques for predicting forces and deformations in SMI problems.