Warren Distinguished Lecture Series

“Developing a Reliable and Resilient Freeway Network”
with Eli Kwon
Civil Engineering, University of Minnesota Duluth

The ultimate challenge facing transportation engineers is developing and maintaining a reliable and resilient freeway network, which can absorb and adapt to various traffic disturbances and recover from congestion with maximum efficiency. The key elements in developing such a resilient freeway network include: 1) the capability to monitor and assess the performance of traffic flows under different operating conditions at a corridor level, 2) a set of the traffic-management strategies that can optimize the corridor-wide traffic performance under time-variant geometric/operational environment, and 3) the corridor-wide geometry structure that can maximize the operational resilience of a given corridor- traffic system in dealing with both normal and abnormal traffic patterns. To address the above issues, several research projects have been conducted at the University of Minnesota Duluth (UMD) in cooperation with the Minnesota Department of Transportation (MnDOT). In this seminar, Eli Kwon presents the results from some of those projects. 

Per- and Polyfluoroalkyl Substances in Drinking Water: Community Impacts and Interventions to Reduce Human Exposure

Detlef Knappe 
Civil, Construction, and Environmental Engineering 
North Carolina State University

The Cape Fear River basin is the largest watershed in North Carolina, and it provides drinking water for about 1.5 million North Carolinians. In this presentation, Knappe highlights advances in analytical methods to characterize sources of per- and polyfluoroalkyl substances (PFAS) and their effects on surface water quality in the Cape Fear River basin. In addition, Knappe describes how stakeholder engagement has led to source control efforts and engineered interventions that have dramatically reduced human exposure to PFAS in communities that receive drinking water from public water systems that treat surface water. Finally, Knappe presents effects of air emission from a fluorochemical manufacturer on private well communities.

"Elasto-frictional length scales and slip dynamics on rate-and-state faults"

A Warren Distinguished Lecture with
Federico Ciardo
Civil and Environmental Engineering , Northwestern University

A fault is a geological discontinuity that accommodates slip when applied loading overcomes frictional resistance. From a modeling perspective, one of the simplest representations consists of a planar, frictional interface separating elastic half-spaces. The coupling between elasticity and friction along this interface gives rise to length scales that define critical dimensions. These critical dimensions impact spatial-temporal evolution of slip. Ciardo shows that more than a single critical dimension is relevant to slip instability on rate-and-state faults. 

"Two Surprising Links Between Convection Velocities and Non-Linearities in Wall-Bounded Turbulence"

A Warren Distinguished Lecture with
Ian Jacobi
Aerospace Engineering, Technion Israel Institute of Technology

ABSTRACT
Coherent large-scale motions in turbulence are major contributors to important environmental flow phenomena, from river sediment dynamics and wind farm power fluctuations, to heat and momentum transport near the ground or along ocean waves. Determining the convection velocities of these large-scale motions is crucial for inferring their spatial structure from temporal field measurements; for developing mode-based models for turbulence prediction; and for developing new actuation schemes for controlling turbulent flows. In this talk, I will explore two surprisingly divergent aspects of the convection velocities of large-scale structures in turbulence. I will first show how accounting for non-linear interactions broadens the predicted spectrum of convection velocities in turbulence modeling, and then, contrariwise, how convection velocity variations can easily be mistaken for evidence of non-linear interactions. The first problem will be examined through laboratory experiments and modeling and has implications for developing more accurate predictions of the space-time spectrum of turbulence. The second problem is an analytical re-examination of the widely used amplitude modulation coefficient but has broader implications for identifying non-linear dynamics in any experimental system. 

Ilenia Battiato 
Energy Science and Engineering
Stanford University

Geologic porous media play a critical role in the energy transition. Modeling and prediction of fluid flow and reacting species in the Earth's subsurface continues to be a major challenge in computational physics because geologic porous media are inherently multiscale, and the relevant scales of interest can easily span 10 orders of magnitude. Battiato and her team propose the first symbolic-numeric framework fully integrating automated symbolic deduction capabilities for multiscale model development and automated numerical code generation, which can be run with minimal human interaction.

Erica Fischer
Civil and Construction Engineering
Oregon State University

Recent fire activity and “mega-fires” resulted in record breaking fire events that have damaged civil infrastructure throughout wildland-urban interface (WUI) communities. These fires are causing massive impacts to civil infrastructure due to burning of homes. Erica Fischer summarizes a study that used machine learning algorithms to examine housing survivability in the 2021 Marshall Fire, investigating the role of housing, parcel, and neighborhood characteristics. The Marshall grass fire affected suburban communities and destroyed more than 1,000 houses. The identification of the most important parameters showed that the majority of the most impactful variables were not within the homeowner’s control. This conclusion demonstrates the importance of neighborhood and community characteristics that are controlled by the jurisdiction on housing survival, especially in a home rule state where building codes and planning may differ across jurisdictional boundaries.

The Sehlin Lecture
Kari Edison Watkins
Civil and Environmental Engineering
University of California at Davis 

ABSTRACT
Traffic crashes are the #1 cause of death from age 1 to 24. Forty-two percent 42% of adults in the US are obese and risk increases 6% with every additional hour spent commuting. Transportation accounts for 29% of total US Greenhouse Gas Emissions. The way we travel creates many societal problems, and yet our system has been designed the same way for generations. Decades of research has shown that how we use our physical roadway space is key to enabling active and shared public transportation to overcome these transportation issues. In this talk, Watkins discusses what drives people’s willingness to bike and to use transit and how we can design cities to improve safety, health, and sustainability.  

Otto Strack
Civil, Environmental, and Geo- Engineering
University of Minnesota

The motivation for this work is the critical importance of efficient recovery of groundwater from all kinds of aquifers, including fractured rock, in today's environment of widespread water shortage. This presentation concerns flow of groundwater through fractured rock as in karst in Minnesota and Germany, and in granite in Sweden. Such flow is poorly understood; information from wells is difficult to interpret because we do not know from which fractures the sampled water is collected. An attractive alternative is to construct an accurate mathematical/numerical model capable of dealing with very large numbers of fractures of vastly different sizes. The advantage of a computer model is access to all data such as pressures and velocities. The idea of numerical tests is inspired by that pioneered by Peter Cundall and Otto Strack in the nineteen seventies for numerical testing of granular media on the scale of particles.

Julia R. Greer
Materials Science, Mechanics, and Medical Engineering
California Institute of Technology

Creation of reconfigurable and multi-functional materials can be achieved by incorporating architecture into material design. Greer and her team design and fabricate three-dimensional (3D) nano-architected materials that can exhibit superior and often tunable thermal, photonic, electrochemical, biochemical, and mechanical properties at extremely low mass densities (lighter than aerogels), which renders them useful and enabling in technological applications. Dominant properties of such meta-materials are driven by their multi-scale hierarchy: from characteristic material microstructure (atoms) to individual constituents (nanometers) to structural components (microns) to overall architectures (millimeters and above).

The Robert Dexter Memorial Lecture

Matthew Eatherton  
Civil and Environmental Engineering, Virginia Tech

 Matthew Eatherton discusses the critical role of a diaphragm in the lateral force resisting system. During the 1994 Northridge Earthquake, several parking garages collapsed due to diaphragm deficiencies. It was found that the US building codes severely underestimate the magnitude of lateral force that can occur in diaphragms during design earthquakes. Development has led to a new approach to diaphragm design, a significant shift in how researchers and engineers think about diaphragms. Eatherton provides an overview of the Steel Diaphragm Innovation Initiative (SDII) project, an introduction to seismic diaphragm design considering inelasticity, and some discussion of implications for the design of steel deck diaphragms.