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Miller M.A.,Princeton University | Estejab B.,Virgina Technology | Bailey S.C.C.,University of Kentucky
Experiments in Fluids | Year: 2014

Several recent spatial filtering corrections for Reynolds stress measured by single component hot-wire probes were assessed using turbulent channel flow data measured over a moderate Reynolds number range. Using measurements with a variety of hot-wire lengths and aspect ratios, the current work determines the impact of these corrections on the actual magnitude and Reynolds number dependence of the near-wall turbulent peak in Reynolds stress and compares it to results from prior direct numerical simulations of turbulent channel flow. Comparison of the results following application of previously published correction schemes were found to produce similar results, with some limitations observed for each technique. Comparison to direct numerical simulation results suggested that additional corrections were needed to correct for end conduction effects. An additional modification for these effects was devised which improved agreement between probes of different lengths and aspect ratios and improved agreement between the measured and direct numerical simulation results. © 2014 Springer-Verlag Berlin Heidelberg. Source

Petrides A.C.,University of Portland | Stewart R.,Virgina Technology | Bower R.,Golder Associates | Cuenca R.H.,Oregon State University | Wolcott B.,Walla Walla BasinWatershed Council
Journal of Hydrologic Engineering | Year: 2015

Recharge rates evaluated from pilot projects of surface managed aquifer recharge are extrapolated to develop design criteria for full-scale projects. Field experiments at surface-managed artificial aquifer recharge facilities in the Walla Walla River basin, Oregon, United States, were used to estimate recharges rates in relation to groundwater mounding and to the expansion in surface area of infiltration basins. Analysis of the results shows that in the case scenarios where the water table mounding does not reach the infiltration basin floor (thereby maintaining an unsaturated zone between the water table and the infiltration basin), the recharge rates from pilot tests scale linearly with the basin's surface area expansion. However, in the case where the groundwater mound reaches the bottom of the basin floor (thereby providing a full hydraulic connection between the infiltration basins and the aquifer), recharge rates should be extrapolated using the perimeter of the infiltration basin. The explanation for this effect is offered by evaluating the distribution of the water velocities at the infiltration basin floor as the length difference between aquifer thickness and the radius of the infiltration basins increases. These findings enable pilot project results to be used as design criteria for full scale projects. © 2014 American Society of Civil Engineers. Source

Harwood V.J.,University of South Florida | Staley C.,University of South Florida | Staley C.,University of Minnesota | Badgley B.D.,Virgina Technology | And 2 more authors.
FEMS Microbiology Reviews | Year: 2014

Microbial source tracking (MST) describes a suite of methods and an investigative strategy for determination of fecal pollution sources in environmental waters that rely on the association of certain fecal microorganisms with a particular host. MST is used to assess recreational water quality and associated human health risk, and total maximum daily load allocations. Many methods rely on signature molecules (markers) such as DNA sequences of host-associated microorganisms. Human sewage pollution is among the greatest concerns for human health due to (1) the known risk of exposure to human waste and (2) the public and regulatory will to reduce sewage pollution; however, methods to identify animal sources are receiving increasing attention as our understanding of zoonotic disease potential improves. Here, we review the performance of MST methods in initial reports and field studies, with particular emphasis on quantitative PCR (qPCR). Relationships among human-associated MST markers, fecal indicator bacteria, pathogens, and human health outcomes are presented along with recommendations for future research. An integrated understanding of the advantages and drawbacks of the many MST methods targeting human sources advanced over the past several decades will benefit managers, regulators, researchers, and other users of this rapidly growing area of environmental microbiology. This review of microbial source tracking (MST) methods for determining the dominant sources of fecal pollution in environmental waters focuses on qPCR-based assays, method performance, and the relationship of MST markers to fecal indicator bacteria, pathogens, and human health outcomes. © 2013 Federation of European Microbiological Societies. Source

Gero J.S.,George Mason University | Jiang H.,National University of Singapore | Williams C.B.,Virgina Technology
ICDC 2012 - 2nd International Conference on Design Creativity, Proceedings | Year: 2012

This paper presents the results of measuring and comparing design cognition while using different creativity techniques for concept generation in collaborative engineering design settings. Eleven design teams, each consisted of two senior mechanical engineering students, were given the same two design tasks, respectively using an unstructured concept generation technique (brainstorming) and a structured technique (TRIZ). A protocol analysis was carried out where the designing activities were audio-visually recorded and analysed using the FBS ontologically-based coding scheme. Preliminary results indicate that the students' design cognition differed when designing with different concept generation creativity techniques. The inter-technique differences were mainly noticeable in the early stages of designing. Specifically, designers tend to focus more on problem-related aspects of designing, i.e., design goals and requirements, when using the structured technique of TRIZ. Alternatively, when using the unstructured technique of brainstorming, designers focused more on solution-related aspects of designing, i.e., a solution's structure and behaviour. Source

Buehlmann U.,Virgina Technology | Espinoza O.,University of Minnesota
IEEE International Conference on Industrial Engineering and Engineering Management | Year: 2014

Experiential learning has not yet found the attention it deserves in academic teaching. This paper describes a successful way to teach students highly complex subjects using experiential learning methods. To teach Lean, Virginia Tech students have created a student-driven, faculty supported team who conducts lean transformation events at cooperating companies, conducts industry workshop to teach Lean, and uses self-guided learning to improve team member performance and knowledge. Results show that students are highly motivated and become self-driven agents through the opportunity to be a member of a high performing team and to contribute to the team's success. When graduating, students remain connected to the team and continue to contribute and participate in the team's activities. © 2014 IEEE. Source

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