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
Baseball Catcher’s Mask STAR Testing Protocol
Shunk, Eric; Stark, Nicole; Miller, Barry; Begonia, Mark T.; Rowson, Steven (Virginia Tech, 2026-10-19)
This document details the protocol used to rate baseball catcher's masks and helmets for the Virginia Tech Helmet Ratings.
Serious Games for One Health Governance: Exploring Skills, Evidence, and Collaboration in Antimicrobial Resistance Policy Deliberations
Riddle, Rebekah Broyles (Virginia Tech, 2026-10-19)
This dissertation examines collaborative governance to tackle antimicrobial resistance (AMR), a wicked One Health problem that spans the human, animal, and environmental sectors. Using a role-play simulation exercise, it explores how technical evidence, stakeholder values and interests, and power shape collaborative governance, as well as what skills are used in these types of deliberations.
Chapter 2 investigates how STEM-H students and early-career researchers employed 21st - century skills in the role-play simulation exercise. It tackles the question: How do engineering students demonstrate and reflect on 21st-century skills during a serious-game-based policy deliberation on antimicrobial resistance? Skills such as communication, collaboration, problem solving, and evidence integration are commonly seen as necessary for these types of deliberations; this research shows that these interrelated skills can be practiced through serious games, which can help prepare technical professionals to work across sectors and engage at the science-policy interface.
Chapter 3 examines the politics of evidence when scientific information is being used in multistakeholder deliberations. Specifically, this chapter answers two questions. First, how did novice participants' understanding of the politics of evidence change as a result of participating in a role-play simulation exercise? Second, what dynamics around the use of evidence emerged during the simulation? Participants used, contested, and interpreted scientific information in ways shaped by stakeholder interests, values, and power. Coalition-building, selective evidence use, and narrative framing demonstrated that evidence-informed policy requires attention to political and relational dynamics as well as technical rigor. Participants also left with a unique tension; they found that stakeholders' values, interests, and priorities were more influential than they had initially anticipated, yet believed those factors should play a more limited role relative to scientific evidence.
Chapter 4 focuses on the challenges and opportunities associated with collaborative governance that emerged as AMR practitioners and content experts participated in the role-play simulation exercise. This chapter answers: What opportunities and constraints for collaborative governance emerge when stakeholders deliberate in a multistakeholder antimicrobial resistance policy simulation? Although cross-sector representation allowed for more holistic and creative policy development and discussion of burden sharing, it did not automatically produce trust, consensus, or implementable action. Time constraints, resource concerns, competing values, and the absence of actors with decision-making authority limited what could be done during the deliberations and provided opportunities for improvement.
Together, this dissertation shows many different aspects of AMR governance and multi-stakeholder deliberations. Furthermore, it demonstrates that serious games can serve as both pedagogical and research tools, providing opportunities for participants to practice and reflect on many aspects of multi-stakeholder deliberation while making its underlying dynamics more visible to researchers.
Resilience through Cyber-Layer Defense in Digital Substations
Herath, Akila Asansana Bandara (Virginia Tech, 2026-10-19)
Modern power grids operate as highly interconnected cyber-physical systems (CPSs), with extensive integration of information and communications technology (ICT) enabling efficient and automated operation. As part of this evolution, IEC 61850-based digital substations have become a key advancement in power-system monitoring, protection, and control. However, the reliance on cyber components such as Intelligent Electronic Devices (IEDs) increases susceptibility to cyber intrusions, demanding enhanced substation cyber resilience.
Existing research has not yet established an integrated framework that comprehensively ad dresses the key dimensions of cyber resilience in digital substations, particularly cyber-attack mitigation and recovery. Mitigation refers to containing a cyber-attack within the cyber layer before it propagates to the physical system. Recovery refers to restoring normal operation following an intrusion. To address these challenges, the Smart Cyber Switching (SCS) con troller with a novel IED concurrency feature is proposed. Upon detecting an attack by the embedded intrusion detection schemes, Software-Defined Networking (SDN) capabilities of the SCS controller isolate compromised IED traffic and restore system operation via Concur rent IEDs (CIEDs). The proposed methodology is validated using an advanced CPS security testbed, whose design, implementation, and validation are also developed and presented in this dissertation.
Furthermore, this dissertation contributes to enhancing cyber-layer intrusion detection. Cyber attacks against digital substations are often carried out as broader multi-phase strategies.
Existing Intrusion Detection Systems (IDSs) often flag only isolated symptoms and lack the attack-phase context needed for effective mitigation. The proposed Substation Cyber Attack Strategy Phasing (SubCASP) fuses IDS data logs to infer the attack phases. The method is validated using an ATTandCK-based attack-graph dataset.
Building upon the proposed technologies for digital substations, this dissertation extends cyber-layer defense to another emerging CPS, Artificial Intelligence Data Centers (AIDCs), whose manipulation as mega-loads can impose significant impacts on the power grid. Specif ically, a potential coordinated cyber-attack targeting multiple AIDC mega-loads is modeled, and a cyber-layer defense methodology is proposed and validated through integrated cyber physical simulations utilizing the IEEE 39-bus system model. This extension demonstrates that the proposed cyber-layer defense concepts can transcend digital substations, paving the way for proactive containment of cyber threats before they inflict physical damage across modern CPSs.
Experimental Investigation of Two-Bubble Cavitation Collapse Near a Rigid Wall: Effects of Stand-Off and Inter-Bubble Distance
Upadhyay, Kushal Jitendrabhai (Virginia Tech, 2026-10-16)
Cavitation bubble collapse near solid boundaries can generate intense pressure waves and liquid microjets that contribute to material erosion and structural damage. This study experimentally investigates the interaction and collapse of two laser-induced cavitation bubbles arranged coaxially near a rigid wall, focusing on the effects of bubble-to-wall stand-off distance and inter-bubble separation. Two bubbles were generated in deionized water using independently controlled pulsed Nd:YAG lasers. High-speed shadowgraphy and Schlieren imaging were used to characterize bubble dynamics and pressure-wave propagation, while a flush-mounted pressure sensor measured the transient wall pressure. The stand-off distance was varied from γ = 0.52 to 1.97, and the inter-bubble distance was varied between β = 5.84, 4.92, and 4.03 mm. The results show that stand-off distance strongly affects collapse morphology and wall pressure. At small stand-off distances, both bubbles undergo toroidal collapse, while at larger distances the near-wall bubble transitions to tip collapse. The maximum first collapse wall pressure of approximately 34.8 MPa was measured at γ = 0.52 and β = 5.84 mm. The farther bubble generally collapses first, generating a pressure disturbance that modifies the collapse of the near-wall bubble. Reducing the inter-bubble distance does not monotonically increase wall pressure; instead, the pressure response depends on bubble interaction, collapse timing, deformation, and energy redistribution. These findings demonstrate the importance of bubble-bubble and bubble-wall interactions in determining cavitation-induced wall loading.
Computational Approaches to Answering Evolutionary Biology Questions
Sarkar, Chandra (Virginia Tech, 2026-10-15)
Advances in computational biology have expanded the scale at which evolutionary questions can be addressed, allowing patterns of molecular evolution, genome evolution, and host-symbiont diversification to be examined using large comparative datasets. Additionally, the repurposing of publicly available datasets provides opportunities to address new questions beyond those for which the data were originally generated, thus avoiding contributing to already exploding amounts of data in the current data-driven world. In this dissertation, I reuse and integrate existing next-generation sequencing datasets through computational pipelines to investigate contradictions to an already established molecular evolution paradigm, survey the occurrence of possible symbiotic bacteria and elucidate host-symbiont co-evolution. My first chapter provides insight into the current state of bioinformatics and challenges in evolutionary biology and provides an overview of the aims of my dissertation. My second chapter examines how cellular environment and spatial organization of proteins influences protein evolutionary rates. Highly expressed proteins evolve slowly, a pattern known as the expression level evolutionary rate anticorrelation (E-R anticorrelation). Using transmembrane proteins, I found that this anticorrelation is stronger in intracellular domains of the proteins as compared to their extracellular counterparts. These results support the hypothesis that protein evolution is constrained to selection against misfolding and deleterious molecular interactions. My third chapter provides a literature review of lice-Wolbachia endosymbiosis, an understudied ectoparasitic-endosymbiont system, that provides the background for my work in the following chapters. My fourth chapter uses publicly available whole-genome sequencing data from avian chewing lice to investigate their associations with the known arthropod-associated Alphaproteobacteria, Wolbachia. Screening and genome reconstruction from a large dataset of 1025 avian chewing lice shotgun sequences show a substantial association between the two organisms. I also report on the classification of these associated Wolbachia into supergroups and their substantial variation of genomic characteristics including genome size, GC content, and coding sequence counts among other metrics. My fifth and last chapter delves into understanding the possible coevolution events of lice and their associated Wolbachia. I use phylogenomics and comparative genomic analyses to understand their shared evolutionary history and indicate possible candidates for mutualism using computational validation. Together, these studies illustrate how existing biological datasets can be reanalyzed through computational pipelines to address new evolutionary questions and aims. Across molecular, genomic, and host-symbiont scales, this dissertation examines how we can understand layers of biological processes using computational prowess.