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Civil and Environmental Engineering Commons™

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Civil and Environmental Engineering Faculty Research and Publications

2009

Articles 1 - 5 of 5

Full-Text Articles in Civil and Environmental Engineering

Highway Work Zone Risk Factors And Their Impact On Crash Severity, Yingfeng Li, Yong Bai Oct 2009

Highway Work Zone Risk Factors And Their Impact On Crash Severity, Yingfeng Li, Yong Bai

Civil and Environmental Engineering Faculty Research and Publications

Numerous factors may contribute to high-severity crashes in highway work zones. Identifying these factors and then alleviating their impact is a challenging task that traffic engineers and researchers have to confront. In this study, the work zone risk factors that could increase the probability of causing fatalities when severe crashes occur were examined using a comprehensive approach. The researchers first identified the significant risk factors based on a screening process that incorporates both statistical analyses and empirical research findings. They then systematically investigated these factors using logistic regression and frequency analysis techniques. The severe crashes including the fatal crashes between …

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A Comparison Of Pilot-Scale Photocatalysis And Enhanced Coagulation For Disinfection Byproduct Mitigation, Daniel Gerrity, Brooke Mayer, Hodon Ryu, John Crittenden, Morteza Abbaszadegan Apr 2009

A Comparison Of Pilot-Scale Photocatalysis And Enhanced Coagulation For Disinfection Byproduct Mitigation, Daniel Gerrity, Brooke Mayer, Hodon Ryu, John Crittenden, Morteza Abbaszadegan

Civil and Environmental Engineering Faculty Research and Publications

This study evaluated pilot-scale photocatalysis and enhanced coagulation for their ability to remove or destroy disinfection byproduct (DBP) precursors, trihalomethane (THM) formation potential (FP), and THMs in two Arizona surface waters. Limited photocatalysis (/m3) achieved reductions in most of the DBP precursor parameters (e.g., DOC, UV254, and bromide) but led to increased chlorine demand and THMFP. In contrast, enhanced coagulation achieved reductions in the DBP precursors and THMFP. Extended photocatalysis (/m3) decreased THMFP once the energy consumption exceeded 20 kWh/m3. The photocatalytic energy requirements for THM destruction were considerably lower (EEO = …

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Effectiveness Of Temporary Traffic Control Measures In Highway Work Zones, Yingfeng Li, Yong Bai Mar 2009

Effectiveness Of Temporary Traffic Control Measures In Highway Work Zones, Yingfeng Li, Yong Bai

Civil and Environmental Engineering Faculty Research and Publications

In the United States, hundreds of people lose their lives each year and many more are injured due to vehicle crashes in the work zones. Over the years, temporary traffic control (TCC) measures have been developed and deployed in work zones. To continuously improve the safety, there is a need to identify the traffic control deficiencies in work zones by evaluating the effectiveness of existing TTC measures based on the real crash cases. In this study, researchers evaluated the effectiveness of several commonly used TTC methods using logistic regression techniques and various significance test methods including likelihood ratio test, score …

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An Analytical Model For Transient Deformation Of Viscoelastically Coated Beams: Applications To Static-Mode Microcantilever Chemical Sensors, Stephen M. Heinrich, Michael J. Wenzel, Fabien Josse, Isabelle Dufour Jan 2009

An Analytical Model For Transient Deformation Of Viscoelastically Coated Beams: Applications To Static-Mode Microcantilever Chemical Sensors, Stephen M. Heinrich, Michael J. Wenzel, Fabien Josse, Isabelle Dufour

Civil and Environmental Engineering Faculty Research and Publications

The problem governing the transient deformation of an elastic cantilever beam with viscoelastic coating, subjected to a time-dependent coating eigenstrain, is mathematically formulated. An analytical solution for an exponential eigenstrain history, exact within the context of beam theory, is obtained in terms of the coating and base layer thicknesses, the elastic modulus of the base material, the initial coating modulus, the coating relaxation percentage (0%–100%), and the time constants of the coating’s relaxation process and its eigenstrain history. Approximate formulas, valid for thin coatings, are derived as special cases to provide insight into system behavior. Main results include (1) the …

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Deflection Of A Viscoelastic Cantilever Under A Uniform Surface Stress: Applications To Static-Mode Microcantilever Sensors Undergoing Adsorption, Michael J. Wenzel, Fabien Josse, Stephen M. Heinrich Jan 2009

Deflection Of A Viscoelastic Cantilever Under A Uniform Surface Stress: Applications To Static-Mode Microcantilever Sensors Undergoing Adsorption, Michael J. Wenzel, Fabien Josse, Stephen M. Heinrich

Civil and Environmental Engineering Faculty Research and Publications

The equation governing the curvature of a viscoelastic microcantilever beam loaded with a uniform surface stress is derived. The present model is applicable to static-mode microcantilever sensors made with a rigid polymer, such as SU-8. An analytical solution to the differential equation governing the curvature is given for a specific surface stress representing adsorption of analyte onto the viscoelastic beam’s surface. The solution for the bending of the microcantilever shows that, in many cases, the use of Stoney’s equation to analyze stress-induced deflection of viscoelastic microcantilevers (in the present case due to surface analyte adsorption) can lead to poor predictions …

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