VTechWorks
VTechWorks provides global access to Virginia Tech scholarship, including journal articles, books, theses, dissertations, conference papers, slide presentations, technical reports, working papers, administrative documents, videos, images, and more by faculty, students, and staff. Faculty can deposit items to VTechWorks from Elements, including journal articles covered by the University open access policy. Email vtechworks@vt.edu for help.
Open Access Policy
Virginia Tech's open access policy enables researchers to deposit the accepted version of scholarly articles with no embargo.
Theses and Dissertations
Virginia Tech was first in the world to require ETDs in 1997, and continues to add scans of older theses and dissertations.
Open Textbooks
More than 40 freely available and openly licensed textbooks are among our most downloaded items.
Communities in VTechWorks
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Recent Submissions
Using Water Quality as a Proxy to Estimate Microplastic Concentrations in the New River, VA, via Sentinel 2
Rodriguez Sequeira, Luisana; Allen, George H.; Gray, Austin D. (New River Symposium, 2024-04-12)
Microplastics (<5mm), are pervasive in Earth’s environments, and rivers are a major transport pathway. Microplastic detection methods that rely on counting individual particles are time consuming and require laborious field collection, inhibiting real-time insights over large spatial extents, which are needed in order to better understand the issue. Satellite remote sensing has been used to estimate water quality in rivers with relatively high spatial and temporal coverage. Finding a correlation between water quality and microplastics could allow us to estimate microplastics in rivers via satellite imagery using water quality as a proxy. Though a handful of these assessments have been done, a wide-variety of study sites are needed to form a coherent model. We focused our study in the New River near Blacksburg, VA, and collected weekly water quality measurements and surface-water microplastic samples. We combined these in situ measurements with cotemporal remotely-sensed water quality index observations from Sentinel-2 to develop a model estimating microplastic concentration. We validated the model using in-situ spectrometry and water quality measurements. By providing more observations than what can be done with in situ sampling alone, we can improve large-scale microplastic analyses and modeling leading to better assessments of mismanaged plastic waste in Earth’s rivers.
Crayfishes of the New River watershed and Factors Affecting Their Distributions
Mouser, Joshua; Loughman, Zachary; Frimpong, Emmanuel A. (New River Symposium, 2024-04-12)
Crayfishes are keystone species within aquatic ecosystems and many species require conservation efforts to support their continued persistence. Unfortunately, we lack basic data needed to make effective conservation decisions for many crayfishes, especially those that occur in the New River watershed (hereafter New River). Therefore, we investigated coarse-scale drivers of crayfish occurrence in the New River. We used generalized linear mixed effects models to predict occurrence of eight taxa based on instream and landscape-scale environmental data and biotic interactions. There are at least 10 species of crayfishes that occur in the New River. Faxonius cristavarius, F. virilis, Cambarus appalachiensis, and C. chasmodactylus are found in larger tributaries throughout the New River. The following species occupy smaller tributaries of the New River: F. spp. (either F. sanbornii or F. obscurus), C. aff. robustus, C. cf. bartonii, and C. smilax. We found that increasing anthropogenic disturbance led to declines in F. spp., C. cf. bartonii, and C. smilax but had a positive relationship with F. cristavarius. The presence of the potentially invasive species, F. cristivarius, was negatively associated with most species. Embeddedness, substrate, proportion riffle habitat, and lithology were additional variables that structured crayfish assemblages. Our results reveal that increasing human-mediated changes and invasive crayfishes threaten the persistence of native crayfishes in the New River.
Evaluation of Truck Parking Needs in a Changing Regulatory Environment
Bell, Stephen; Alden, Andrew (National Surface Transportation Safety Center for Excellence, 2024-03-15)
Commercial driver hours-of-service rules were created to ensure that operators of heavy vehicles on US roads have opportunities to receive adequate rest during and between trips. The use of electronic logging devices to replace handwritten logs, along with the implementation of automated vehicle tracking systems, has created a potential opportunity to track the location of truck drivers with respect to their hours-of-service status. It is envisioned that this real-world driving data can inform the siting of new facilities to address a critical, national shortage of safe and convenient truck parking. This investigation sought to provide proof-of-concept for the use of electronically logged hours-of-service data to determine where additional truck parking areas are needed. A sample of this data was purchased from a commercial telematics provider, and a trusted partner was contracted to transform the acquired raw data into a format that could be used within geographic database system to identify where drivers were located as they neared the end of their allowed driving time. This database would also include the locations of existing truck parking facilities so that gaps in coverage could be identified. Unfortunately, the native format of the hours-of-service data as collected and provided was not conducive to creating a continuous record of a driver’s trips that could be synchronized in time with location data. Also, the sample set of real driving data that was provided in line with the project budget contained too few records to be of practical use. Therefore, proof-of-concept was not validated with this effort. It is likely, though, that the evolution of telematic and electronic logging systems, and the perceived value of this type of information, will result in data quality improvements that will enable the type of analysis envisioned. Examples of the problems encountered are described, and lessons learned and suggestions for future efforts have been provided.
Temporal Patterns in U.S. Pedestrian Traffic Crashes
Witcher, Christina; Henry, Scott; Sullivan, Kaye; Laituri, Tony (2024-04-18)
The number of pedestrian traffic fatalities in the U.S. has been increasing since 2009, despite a general decline during the preceding decades (Figure ES1). In contrast, changes in the number of non-fatal injured pedestrians in traffic crashes were less pronounced during the same period. Our 2022 pedestrian-centric study, funded by the National Surface Transportation Safety Center for Excellence, focused on the differences between those two populations (i.e., fatal and non-fatal injured pedestrians).
This analysis extended that study by exploring fatal and non-fatal injured pedestrians from the perspective of temporal characteristics (e.g., year, month, day of week, hour of day), collected from U.S. national datasets for police-reported traffic crashes maintained by the National Highway Traffic Safety Administration. Fatal pedestrian crash data from the Fatality Analysis Reporting System for the 2010–2019 calendar years were examined. Non-fatal injured pedestrian crash data were weighted estimates from two national data sources: the General Estimates System for calendar years 2010–2015 and the Crash Report Sampling System for calendar years 2016–2019.
The findings of this temporal analysis can be used to identify potential factors influencing the continued increase in fatalities and the differences between fatal and non-fatal pedestrian crashes. In addition to providing distributions for each temporal characteristic, the ratio of fatal to non-fatal injured pedestrians in traffic crashes was used to identify “peaks” during which fewer pedestrian-involved crashes occurred and/or the injuries were more severe. This ratio was also used to develop categories that typify weekly driving operations. These measures showed distinct differences for fatal and non-fatal injured pedestrians. Fatal pedestrians occurred more often during early hours, weeknights, and weekend-nights, with peaks at night. Non-fatal injured pedestrians occurred more often during weekdays, evening commutes, and weeknights, with peaks during the day. There were no notable differences observed in the 2020 calendar year temporal patterns for fatal and non-fatal injured pedestrians compared with the period 2017–2019. This information is important for determining areas of further study needed to develop or refine vehicle and infrastructure countermeasures and public campaigns to improve pedestrian traffic safety.
Assessment of a Fixed Media Partial Denitrification/Anammox Process Startup in a Full-Scale Treatment Train
Wieczorek, Nathan Vincent (Virginia Tech, 2024-04-18)
Partial denitrification anammox (PdNA) is an emerging wastewater treatment technology with the potential to increase process capacity and save on energy and carbon. PdNA circumvents potential issues with stability of the more familiar mainstream partial nitritation anammox (PNA) process. The PdNA process can be used to effectively remove ammonia, nitrate, and nitrite from mainstream municipal waste streams. To retain slow growing anammox, some sort of retention system is needed with media being a common solution to this problem. PdNA has been successfully implemented in mainstream full-scale systems in sand filters and with moving media. The goal of this study was to assess the denitrifying capabilities, anammox treatment capacity, and effective surface area to volume of two types of fixed media. A nitrifying pilot was set up to assess the effective surface area to volume. To assess the nitrifying and anammox ammonia removal capabilities of the fixed media, a fixed media PdNA system was installed in the second anoxic zone of a full-scale municipal wastewater treatment plant. The fixed media system consisted of three modules of sheets modified to mimic a plug flow system. After accounting for the estimated nitrate removal from mixed liquor, denitrification rates normalized to media surface area were 0.52 +/- 1.9 g/m2-day in the first module, 0.62 +/- 0.91 g/m2-day for the second module, and 0.56 +/- 0.90 g/m2-day for the third module. In ex situ batch testing it was found that maximum ex-situ anammox ammonia removal rates for the