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 50 freely available and openly licensed textbooks are among our most downloaded items.
Communities in VTechWorks
Select a community to browse its collections.
Recent Submissions
Human Trafficking Training Supplement for CDL School Curriculums
Manke, Aditi; Crowder, Tarah; Mabry, J. Erin (National Surface Transportation Safety Center for Excellence, 2026-08-31)
The objective of this project was to design and develop a human trafficking education and training module for Virginia CDL schools to integrate into existing CDL curriculums. The project leveraged insights and findings from the research team’s recently completed Human Trafficking Outreach and Education Campaign project (Mabry, 2025) to create focused and engaging content. The module also pulled from best practices reflected in programs offered by Truckers Against Trafficking, the Commercial Vehicle Safety Alliance, Polaris, and the Department of Homeland Security’s Blue Campaign. A focus group was conducted with eight CDL students enrolled at a local community college to beta test the draft training module. Feedback was collected, analyzed via content analysis, and incorporated into the final training. Feedback identified opportunities for improvement, notably the need for stronger human-centered content, broader statistical framing, and repeated reinforcement of available resources. Revisions addressed this feedback to strengthen the emotional impact of the training without extending it beyond the duration that CDL schools can reasonably accommodate.
The final module and accompanying speaker notes were distributed to approximately 30 CDL schools across Virginia. This training will provide Virginia CDL schools with a practical, curriculum-ready option for delivering short, evidence-grounded training that can be incorporated into existing CDL training curriculums in Virginia. Additionally, the module points to longer, more comprehensive education and training programs offered by Truckers Against Trafficking, Transportation Leaders Against Human Trafficking, and the Blue Campaign for schools that elect to provide more in-depth coverage of human training and individual learners who wish to pursue more education on their own.
Adaptive loaner equipment: A case study of the Trackchair loaner program at Ludington and Grand Haven State Parks, Michigan
McGregor, Freya A.; Dayer, Ashley A. (2026-08-31)
According to the Centers for Disease Prevention and Control, more than 12% of the U.S. population lives with some kind of mobility disability – 1 in 8 people. While designing and maintaining accessible trails is often the most effective strategy in serving this population, some trails just aren’t a good fit for that approach. Providing off-road wheelchairs to visitors can allow people to explore nature spaces, engage in hiking, camping, wildlife viewing, hunting or angling, spend time with their family or friends, and otherwise experience lands managed by state wildlife agencies.
Trackchairs are one type of off-road wheelchair. Rather than actual wheels, these battery-operated devices have tracks – like military tanks – which allow them to navigate rocky, uneven and unstable surfaces from gravel to fine sand. These devices are expensive – about $15,000 each – but this cost is not the whole story. Resources including effective human and software infrastructure is needed to support a successful loaner Trackchair program, and this must be ongoing. Maintenance costs must be budgeted for, storage and a power source are required. Outreach to let people with disabilities know this feature is available is needed too – otherwise Trackchairs will sit in a garage gathering dust.
Across Michigan Department of Natural Resources (DNR) properties, 33 state parks out of 143 have loaner Trackchairs; some parks have multiple. This program has come into existence since 2017, and as more locations have obtained Trackchairs and more members of the community appreciated the benefits they can offer, the demand has increased. Many Trackchairs have been purchased by state parks’ Friends groups with DNR providing additional funds. Each location has their own rules regarding where Trackchairs can be used and their own system for making reservations.
This case study report focuses on how the loaner Trackchair program operates at Ludington State Park. It answers the following questions:
- What is adaptive loaner equipment? What are Trackchairs?
- Why have a loaner Trackchair available to visitors?
- Who can benefit from using a Trackchair?
- How much are the Trackchairs used at Ludington State Park?
- How does someone learn about and borrow a TrackChair?
- How did the program get implemented at the agency level, and at Ludington State Park?
- What challenges did staff face in implementing this program? How were they overcome?
- What resources are needed for a Trackchair loaner program?
- What needs to be considered when establishing a loaner Trackchair program?
- Advice on implementing a similar program at your agency
References and appendices are included, including information about methods, information about fundraising for purchasing Trackchairs, how a similar program operates at Grand Haven State Park, and strategies to promote Trackchairs to the public.
We hope you find this report full of helpful, replicable ideas and strategies to implement and operate an effective loaner adaptive equipment program. Thank you for your work to increase accessibility in the outdoors for the 1 in 4 Americans with a disability!
Using the SECI Model to Map Knowledge Systems of Urban Farmers in Virginia
McCausland, William Alexander (Virginia Tech, 2026-08-28)
Urban farmers face significant issues with representation and the ability to access information from institutions designed to provide support for agricultural producers. This study examines the knowledge systems of urban farmers in Virginia through the Socialization, Externalization, Combination, and Internalization (SECI) model of knowledge creation to better understand how agricultural knowledge is acquired, exchanged, and applied in Virginia. A qualitative research design was employed using semi-structured interviews with self-identified urban farmers across Virginia who produced for either financial production or public good. Participants were recruited through statewide urban agriculture networks, conferences, and snowball sampling. Interview transcripts were analyzed using in vivo and descriptive coding, followed by thematic analysis aligned with the SECI framework. Four themes emerged from the analysis: (1) agricultural identity through experience; (2) navigating diversified knowledge systems; (3) knowledge transmission and experiential learning through reciprocal relationships; and (4) envisioning decentralized, community driven futures. The findings demonstrate that urban agricultural knowledge systems are dynamic, relationship-based networks that depend on the interaction of formal organizations, peer communities, and experiential learning rather than a single centralized source of expertise. This research is significant because it serves to strengthen collaboration among knowledge institutions, while also supporting existing community networks for urban farmers. This study also addresses research gaps that relate to educational access, knowledge dissemination, awareness of urban agriculture nationally and in Virginia, and the connection between knowledge systems and urban agriculture.
Wave Holtz: Theory and High Performance Applications
Rotem, Amit (Virginia Tech, 2026-08-28)
The solution to the Helmholtz equation describes the spatial waveform of a time-harmonic wave and arises in acoustics, electromagnetism, and seismology. Its efficient numerical treatment makes engineering problems tractable but presents two central difficulties. First, the waves must be sufficiently resolved. Engineering problems often span hundreds to thousands of wavelengths, over which phase error accumulates, demanding many points per wavelength and yielding systems with millions to billions of degrees of freedom. Second, standard discretizations produce a complex-valued, highly indefinite linear system on which general-purpose iterative methods perform poorly or fail outright, making specialized methods for the equation a challenging, active research topic. This dissertation advances one such method: WaveHoltz, which relates the Helmholtz equation to its time-dependent counterpart, the wave equation. WaveHoltz evolves the wave equation and filters its solution over a short time interval to estimate the Helmholtz solution; this estimate is fed back as an initial condition, iteratively improving the estimate until convergence; this iteration can be accelerated by standard Krylov methods. On the theoretical side, convergence of the discrete iteration is established, the temporal error of the wave solve is eliminated, and WaveHoltz-HMM, a homogenization method with error estimates, is introduced. On the computational side, a high-performance GPU implementation combining multigrid-accelerated time stepping with massively parallel algorithms and a GPU-tailored domain decomposition approach made efficient by using WaveHoltz as a subdomain solver are presented. Altogether, WaveHoltz proves robust and efficient for solving the Helmholtz equation.
Assessment of Peanut (Arachis hypogaea L.) Responses to Heat and Drought Stress Through Physiological, Machine Learning, and Transcriptomic Approaches
Vennam, Ranadheer Reddy (Virginia Tech, 2026-08-28)
Heat-exacerbated drought stress is an increasing constraint on peanut (Arachis hypogaea L.) production in the rainfed Virginia–Carolina region, yet the physiological, phenotypic, and molecular consequences of this combined stress remain incompletely characterized. This dissertation integrated growth chamber, multi-year field, high-throughput phenotyping, and transcriptomic approaches across five interconnected studies to address this gap. In growth chamber and field trials, combined heat and drought stress (HS+DS) significantly reduced stomatal conductance and transpiration relative to control or rainfed treatment. Under sustained mid- to late-season HS+DS imposed with rainout shelters across two field seasons, canopy temperature increased by up to 6 °C, accompanied by greater leaf wilting severity and pod yield reductions of 52–73%. Yield, grade, and economic analyses across 12 genotypes showed that HS+DS reduced the percentages of extra-large kernels and total sound mature kernels and eliminated profitability, with losses exceeding $2,000 ha⁻¹ in 2025. However, breeding line 14x009-1-5-1-1 maintained comparatively stable pod yield across both years. Leaf wilting and stomatal conductance were the strongest predictors of yield loss (R² = 0.86–0.89). To scale wilting assessment beyond manual scoring, a machine learning framework combining UAV multispectral imagery and accumulated growing degree days was developed utilizing data across three years and five sites; Extreme Gradient Boosting achieved the highest predictive accuracy (R² = 0.82–0.87), enabling pixel-level mapping of wilting severity. Finally, RNA sequencing of four virginia-type genotypes under field HS+DS identified 1,733 differentially expressed genes, revealing that genotypes with similar physiological responses employed largely distinct transcriptional strategies. Collectively, these findings demonstrate that HS+DS imposes convergent physiological and yield penalties on peanut via distinct molecular pathways, while also establishing scalable phenotyping tools that can support management and breeding strategies for improved resilience to heat and drought in rainfed peanut production.