Engineering Commons^™

Tracking Missing Drivers, James G. Strathman

TREC Project Briefs

By understanding driver absenteeism, transit providers can learn to manage it, Portland State University research suggests.

Multiple Trophic Levels Fueled By Recirculation In The Columbia River Plume, Raphael M. Kudela, Alexander R. Horner-Devine, Neil S. Banas, Barbara M. Hickey, Tawnya D. Peterson, Ryan M. Mccabe, Evelyn J. Lessard, Elizabeth R. Frame, Kenneth W. Bruland, David A. Jay, Jay O. Peterson, William T. Peterson, P. Michael Kosro, Sherry L. Palacios, Maeve C. Lohan, Edward P. Dever

Civil and Environmental Engineering Faculty Publications and Presentations

Large rivers represent gateways for the transport of terrigenous and anthropogenic material to the coastal ocean. Here we document a ?700 km2 recirculation or bulge associated with the Columbia River plume that retains recently discharged river water sufficiently to create a regional bioreactor. Fueled by a fluvial nitrate source, this feature stimulated growth across three trophic levels and may buffer this gateway system during periods of increased warming and stratification that lead to decreased ocean productivity, potentially enhancing production at multiple trophic levels and enriching surfacewaters far from the river mouth.

Mixing Layer Dynamics In Separated Flow Over An Estuarine Sill With Variable Stratification, Stefan A. Talke, Alexander R. Horner-Devine, C. Chris Chickadel

Civil and Environmental Engineering Faculty Publications and Presentations

We investigate the generation of a mixing layer in the separated flow behind an estuarine sill (height H ∼ 4 m) in the Snohomish River, Washington as part of a larger investigation of coherent structures using remote and in situ sensing. During increasing ebb flows the depth d and stratification decrease and a region of sheared flow characterized by elevated production of turbulent kinetic energy develops. Profiles of velocity and acoustic backscatter exhibit coherent fluctuations of order 0.1 Hz and are used to define the boundaries of the mixing layer. Variations in the mixing layer width and its embedded coherent …

The Effect Of Tidal Asymmetry And Temporal Settling Lag On Sediment Trapping In Tidal Estuaries, Alexander S. Chernetsky, Henk M. Schuttelaars, Stefan A. Talke

Civil and Environmental Engineering Faculty Publications and Presentations

Over decades and centuries, the mean depth of estuaries changes due to sea-level rise, land subsidence, infilling, and dredging projects. These processes produce changes in relative roughness (friction) and mixing, resulting in fundamental changes in the characteristics of the horizontal (velocity) and vertical tides (sea surface elevation) and the dynamics of sediment trapping. To investigate such changes, a 2DV model is developed. The model equations consist of the width-averaged shallow water equations and a sediment balance equation. Together with the condition of morphodynamic equilibrium, these equations are solved analytically by making a regular expansion of the various physical variables in …

Characteristics Of Transitions In Freeway Traffic, Robert L. Bertini, Soyoung Ahn

Civil and Environmental Engineering Faculty Publications and Presentations

This research seeks to understand the characteristics of transitions as freeway traffic changes from one state to another. This study addresses the features of two types of transitions; transitions near a merge and transitions along shock waves during the onsets and dissipations of queues at several freeway sites.

Individual vehicle trajectory data were analyzed for studying the transitions near a merge. The length of a transition zone was measured by analyzing the spatial changes in flow, density and speed along kinematic waves near a merge. It was found that the length of transition in terms of flow, density and speed …

Improving Robustness Of Hydrologic Parameter Estimation By The Use Of Moving Block Bootstrap Resampling, Hamid Moradkhani, Mohammad Ebtehaj, Hoshin V. Gupta

Civil and Environmental Engineering Faculty Publications and Presentations

Modeling of natural systems typically involves conceptualization and parameterization to simplify the representations of the underlying process. Objective methods for estimation of the model parameters then require optimization of a cost function, representing a measure of distance between the observations and the corresponding model predictions, typically by calibration in a static batch mode and/or via some dynamic recursive optimization approach. Recently, there has been a focus on the development of parameter estimation methods that appropriately account for different sources of uncertainty. In this context, we introduce an approach to sample the optimal parameter space that uses nonparametric block bootstrapping coupled …

The Surface Expression Of Semidiurnal Internal Tides Near A Strong Source At Hawaii. Part I: Observations And Numerical Predictions, Cedric Chavanne, P. Flament, Glenn S. Carter, M. Merrifield, D. Luther, Edward D. Zaron, K. W. Gurgel

Civil and Environmental Engineering Faculty Publications and Presentations

Observations of semidiurnal currents fromhigh-frequency radioDoppler currentmeters andmoored acoustic Doppler current profilers (ADCPs) in the Kauai Channel, Hawaii, are described and compared with two primitive equation numerical models of the tides. The Kauai Channel, separating the islands of Oahu and Kauai, is a site of strong internal tide generation by the barotropic tides flowing over Kaena Ridge, the subsurface extension of Oahu. The nature and impacts of internal tide generation in the Kauai Channel were intensively studied during the 2002–03 near-field component of the Hawaii Ocean Mixing Experiment. Comparisons of observed coherent (i.e., phase locked to the astronomical forcing)M_{2 …}

Freight Performance Measures: Approach Analysis, B. Starr Mcmullen, Christopher M. Monsere

Civil and Environmental Engineering Faculty Publications and Presentations

This report reviews the existing state of the art and also the state of the practice of freight performance measurement. Most performance measures at the state level have aimed at evaluating highway or transit infrastructure performance with an emphasis on passenger transportation. Freight performance measurement ultimately requires evaluation of performance of the entire freight transportation system, which includes highways, waterways, rail, air, and modal connections. This requires considerable expansion of thinking beyond the traditional focus of state Departments of Transportation (DOTs) on highway performance.

This project builds upon past and current work in the area of freight performance measurement and …

Instrumentation For Mechanistic Design Implementation, Todd Scholz

TREC Final Reports

The Oregon Department of Transportation (ODOT) Pavement Services Unit is in the process of implementing a new pavement design procedure being developed under the sponsorship of the American Association of State Highway and Transportation Officials. Fatigue cracking is a key distress mechanism that is predicted as part of the overall process using a theoretical model calibrated to empirical data. Tensile strain at the underside of the hot-mix asphalt pavement layers induced by truck axle loads is, in turn, a key input into the fatigue cracking model. In the new design procedure tensile strain is predicted utilizing a layered elastic analysis …

River Influences On Shelf Ecosystems: Introduction And Synthesis, Barbara M. Hickey, Raphael M. Kudela, Jonathan Nash, Kenneth W. Bruland, William T. Peterson, P. Maccready, Evelyn J. Lessard, David A. Jay, Neil S. Banas, Antonio M. Baptista, Edward P. Dever, P. Michael Kosro, Levi Kilcher, Alexander R. Horner-Devine, Edward D. Zaron, Ryan M. Mccabe, Jay O. Peterson, Philip M. Orton, Jiayi Pan

Civil and Environmental Engineering Faculty Publications and Presentations

River Influences on Shelf Ecosystems (RISE) is the first comprehensive interdisciplinary study of the rates and dynamics governing the mixing of river and coastal waters in an eastern boundary current system, as well as the effects of the resultant plume on phytoplankton standing stocks, growth and grazing rates, and community structure. The RISE Special Volume presents results deduced from four field studies and two different numerical model applications, including an ecosystem model, on the buoyant plume originating from the Columbia River. This introductory paper provides background information on variability during RISE field efforts as well as a synthesis of results, …

Organic Particulate Matter Formation At Varying Relative Humidity Using Surrogate Secondary And Primary Organic Compounds With Activity Corrections In The Condensed Phase Obtained Using A Method Based On The Wilson Equation, James F. Pankow, E. I. Chang

Civil and Environmental Engineering Faculty Publications and Presentations

Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N · 2p) approach. The N · 2p approach neglects: 1) variation of activity coefficient (i) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N ·2p)pMW, approach (is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of i …

A Survey Of China's Logistics Industry And The Impacts Of Transport Delays On Importers And Exporters, Zeyan Zhang, Miguel Andres Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

In the last decades, China?s booming economy has greatly benefited from globalization and trade liberalization. China has found a niche as the world?s manufacturing centre and it is playing a crucial role in a growing number of global supply chains. This research focuses on the performance of international and domestic transport and logistics systems as perceived by Chinese importers and exporters. A broad literature review of Chinese meteoric logistics industry development is provided. Results and analysis of in?depth interviews with Chinese importers and exporters are presented. These interviews provide significant information regarding international freight transport chains, the impact of delays …

Initial Expansion Of The Columbia River Tidal Plume: Theory And Remote Sensing Observations, David A. Jay, Edward D. Zaron, Jiayi Pan

Civil and Environmental Engineering Faculty Publications and Presentations

Analysis of the Columbia River tidal plume using Lagrangian frontal equations provides a concise description of the evolution of frontal depth H, velocity U, reduced gravity g', and frontal internal Froude number F (sub R) . Because the estuary mouth is narrow, the initial radial plume motion is supercritical (F (sub R) > 1) for up to 12 hours. Understanding this supercritical phase is vital, because plume properties change rapidly, with strong ecosystem impacts. To analyze this expansion, analytical and numerical models (the latter with three mixing formulations) were tested. Model results are compared to synthetic aperture radar images to verify …