Warren Distinguished Lecture Series

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. 

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.

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

Constantinos Antoniou
Civil, Geo and Environmental Engineering, Technical University of Munich

ABSTRACT: Antoniou looks at some recent and ongoing research on expected impacts of automation in transforming public transport systems. He describes an integrated framework for a scenario-based impact assessment. Topics include an analysis of multiple waves of survey data collected from users of an automated bus deployment in Stockholm, as well as the development of an analytical model that provides insights into how automation may affect the design and operation of future public transport systems, applied to networks in Germany and Chile.

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Carla A. Ng
Civil and Environmental Engineering, University of Pittsburgh

Per- and polyfluorinated alkyl substances (PFAS) are a diverse group of chemicals used in a dizzying array of applications. Public concern is growing over ubiquitous human exposure to PFAS, and the recognition that some PFAS are bioaccumulative and can be toxic even at extremely low concentrations. This concern has prompted policy action at state, federal, and international levels. Yet the development of sound policy and decisions around PFAS is complicated by lack of data on most members of the broad class of chemicals and by the practical difficulties around a substance-by-substance approach to evaluating these chemicals, particularly given their unique properties and behavior in environmental and biological systems. Ng highlights several initiatives from her research group and collaborative work to tackle the PFAS problem at two levels. At the molecular level, she is developing integrative modeling strategies to predict the behavior and potential hazard of diverse PFAS using computational approaches that help to overcome limitations of traditional testing and increase throughput. At the policy framework level, she is collaborating with a team of international academic and regulatory scientists and policy analysts to develop scientifically sound strategies to eliminate hazardous PFAS from products and processes.

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Jia-Liang Le
Civil, Environmental, and Geo- Engineering, University of Minnesota

ABSTRACT: It is widely acknowledged that no structure can be designed to be risk free, and therefore, reliability analysis plays a central role in the design of engineering structures. The recent focus has been placed on structures made of brittle heterogenous (a.k.a. quasibrittle) materials, such as ceramics, composites, concrete, and many more at the microscale. Le and his team recently developed a level excursion model for analyzing the probabilistic failure of quasibrittle structures, in which the structural failure probability is calculated as a first passage probability. The main feature of the model is that it captures both the spatial randomness of local material resistance and the random stress field induced by microstructures. The model represents a continuum generalization of the classical weakest-link model, which recovers the Weibull distribution as an asymptotic distribution function. In this talk, Le discusses two applications of this model.

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Alireza Khani
Civil, Environmental, and Geo- Engineering, University of Minnesota

ABSTRACT: Transportation systems are confronting disruptive changes due to the emergence of new technologies such as shared mobility and autonomous vehicles. Traditional methods of modeling transportation systems do not capture the characteristics of new modes or the behavior of users in response to new modes. Therefore, new and customized methods are needed for i) analyzing human mobility patterns from new data sources, ii) controlling the operation of on-demand mobility services, and iii) optimizing long term planning of transportation infrastructures considering future technologies. In this seminar, Khani presents optimization methods to solve selected problems from the three research needs. He and his team develop and apply these methods in the context of multimodal transportation systems to increase benefits to society.

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Stefano Gonella
Civil, Environmental, and Geo- Engineering, University of Minnesota

ABSTRACT: Elastic metamaterials are structural materials that owe their unique wave manipulation capabilities to their complex internal architecture. Topological metamaterials are special metamaterials whose behavior is directly controlled by the topology of their phonon band structure. In this talk, we present two problems in topological phononics that deal with the propagation of waves at edges and interfaces. The first problem regards a class of metamaterials known as topological Maxwell lattices. In the second part of the presentation, we demonstrate the existence of valley-Hall edge states in the in-plane dynamics of honeycomb lattices with bi-valued strut thickness.

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Nancy Sims
Libraries, University of Minnesota

Citation, credit, authorship, ownership—at first pass most of these seem like fairly straightforward topics. But beyond a cursory look, these issues are rich and complex, with surprising and subtle nuances across academic disciplines, creative communities, cultural groups, and legal jurisdictions. Technologies intended to address concerns in these areas often fail on numerous edge cases, although they are also sometimes useful. Attorney and librarian Nancy Sims explores some of the tensions inherent in academic understandings of credit and plagiarism.

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Peter Jan van Leeuwen
Atmosphereic Science, Colorado State University

ABSTRACT: In the geosciences, Bayesian inference is known as data assimilation, and many powerful methodologies have been developed, for instance for weather prediction. At present, weather prediction centers try to find useful solutions to the data-assimilation problem in a state space of size 10 billion or more. These methods are all based on linearizations of the problem, while with ever increasing model resolution and more sophisticated observations the problem has become highly nonlinear. Hence, there is a call for fully nonlinear methods. A new possibility has been developed based on so-called particle flows. Van Leeuwen demonstrates the usefulness of this new approach in simple toy problems and in high-dimensional ocean systems discussing theoretical and practical issues. Finally, van Leeuwen discusses how the present-day weather prediction scheme can be adapted to transform weather prediction from an approximate linearized solution to a fully nonlinear solution of the Bayesian Inference problem.

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