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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.
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Recent Submissions
The Influence of Ultraprocessed Food Consumption on Energy Intake in Emerging Adulthood: A Controlled Feeding Trial
Rego, Maria L. M.; Leslie, Emma; Schmall, Emily; Capra, Bailey; Hudson, Summer; Ahrens, Monica L.; Katz, Benjamin; Davy, Kevin P.; Hedrick, Valisa E.; DiFeliceantonio, Alexandra G.; Davy, Brenda M. (Wiley, 2025-11-19)
OBJECTIVE: This study examined the impact of a 2-week eucaloric diet high in ultraprocessed foods (UPF) compared to a diet without UPF (non-UPF) on ad libitum energy intake (EI) and food selection in individuals aged 18-25. METHODS: In a randomized, crossover, proof-of-concept trial, participants completed two 14-day controlled feeding periods (81% UPF vs. 0% UPF), with a 4-week washout. Diets were matched for macronutrients, fiber, added sugar, diet quality, and energy density. Following each condition, participants consumed an ad libitum buffet meal including UPF and non-UPF. Energy and food grams consumed were quantified. Statistical analyses were conducted for the full sample, late adolescents (aged 18-21), and young adults (aged 22-25). RESULTS: Twenty-seven individuals aged 22 ± 2 years (mean BMI = 24 ± 3 kg/m2) were included. Diet compliance was ~99% overall. There was no effect of diet condition on meal total kcal or grams consumed or UPF or non-UPF consumption in the full sample (all p > 0.05). In the exploratory age subgroup analysis, an interaction between diet and age was observed for total EI (p < 0.001), where total EI increased among adolescents following the UPF diet (p = 0.03, d = 0.79), but not in young adults. CONCLUSIONS: Late adolescents may be susceptible to increased EI following a UPF diet. Future trials are warranted to evaluate this possibility. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05550818.
Toward Predictable and Efficient Deep Neural Network Inference on Graphics Processing Units
Fakhim Babaei, Amir (Virginia Tech, 2025-11-20)
GPUs dominate DNN inference but remain difficult to control predictably under multi-tenant load. This thesis presents a practical, end-to-end approach for predictable, efficient single-GPU inference built around a closed loop of predict → allocate → power-tune.
First, we introduce SGPRS, a spatio–temporal scheduler that combines spatial partitioning with stream-based temporal concurrency and explicit staging for coarse preemption and partition reuse without costly reconfiguration.
Second, we develop GRAIL, a lightweight online predictor of latency and throughput under varying TPC (SM-group) and clock settings, and GRAIL-A, a zero-overhead allocator that turns those predictions into fast TPC and clock decisions.
Third, we design SAGE, a power-aware runtime that coordinates DVFS and TPC control via a central partitioner and per-tenant local schedulers.
Across diverse CNN and Transformer models and workload mixes, the system improves total throughput, tightens P95 and P99 latency, and reduces energy compared to temporal-only, spatial-only, and framework baselines, while preserving deadline behavior. The result is a resource-aware, empirically validated path to predictable multi-tenant inference on a single NVIDIA GPU.
Quantum K-theory of incidence varieties
Xu, Weihong (Springer, 2024-06-01)
We prove a conjecture of Buch and Mihalcea in the case of the incidence variety X = Fl(1, n - 1; n) and determine the structure of its (T-equivariant) quantum K-theory ring. Our results are an interplay between geometry and combinatorics. The geometric side concerns Gromov-Witten varieties of 3-pointed genus 0 stable maps to X with markings sent to Schubert varieties, while on the combinatorial side are formulas for the (equivariant) quantum K-theory ring of X. We prove that the Gromov-Witten variety is rationally connected when one of the defining Schubert varieties is a divisor and another is a point. This implies that the (equivariant) K-theoretic Gromov-Witten invariants defined by two Schubert classes and a Schubert divisor class can be computed in the ordinary (equivariant) K-theory ring of X. We derive a positive Chevalley formula for the equivariant quantum K-theory ring of X and a positive closed formula for Littlewood-Richardson coefficients in the non-equivariant quantum K-theory ring of X. The Littlewood-Richardson rule in turn implies that non-empty Gromov-Witten varieties given by Schubert varieties in general position have arithmetic genus 0.
Controlled ion transport in the subsurface: A coupled advection-diffusion-electromigration system
Tang, Kunning; Bo, Zhenkai; Li, Zhe; Da Wang, Ying; McClure, James; Su, Hongli; Mostaghimi, Peyman; Armstrong, Ryan T. (AIP Publishing, 2024-06-01)
Ion transport within saturated porous media is an intricate process in which efficient ion delivery is desired in many engineering problems. However, controlling the behavior of ion transport proves challenging, as ion transport is influenced by a variety of driving mechanisms, which requires a systematic understanding. Herein, we study a coupled advection-diffusion-electromigration system for controlled ion transport within porous media using the scaling analysis. Using the Lattice-Boltzmann-Poisson method, we establish a transport regime classification based on an Advection Diffusion Index (ADI) and a novel Electrodiffusivity Index (EDI) for a two-dimensional (2D) microchannel model under various electric potentials, pressure gradients, and concentration conditions. The resulting transport regimes can be well controlled by changing the applied electric potential, the pressure field, and the injected ions concentration. Furthermore, we conduct numerical simulations in a synthetic 2D porous media and an x-ray microcomputed tomography sandstone image to validate the prevailing transport regime. The simulation results highlight that the defined transport regime observed in our simple micromodel domain is also observed in the synthetic two- and three-dimensional domains, but the boundary between each transport regime differs depending on the variation of the pore size within a given domain. Consequently, the proposed ADI and EDI emerge as dimensionless indicators for controlled ion transport. Overall, our proof-of-concept for ion transport control in porous media is demonstrated under advection-diffusion-electromigration transport, demonstrating the richness of transport regimes that can develop and provide future research directions for subsurface engineering applications.
Variability of Atomic Hydrogen Brightness in the Martian Exosphere: Insights From the Emirates Ultraviolet Spectrometer on Board Emirates Mars Mission
Susarla, R.; Deighan, J.; Chaffin, M. S.; Jain, S.; Lillis, R. J.; Chirakkil, K.; Brain, D.; Thiemann, E.; Eparvier, F.; Lootah, F.; Holsclaw, G.; Gacesa, M.; Fillingim, M. O.; El-Kork, N.; England, Scott L.; Evans, J. S.; AlMazmi, H.; AlMatroushi, H. (American Geophysical Union, 2024-06-01)
The Emirates Mars Ultraviolet Spectrometer (EMUS), aboard the Emirates Mars Mission (EMM), has been conducting observations of ultraviolet emissions within the Martian exosphere. Taking advantage of the distinctive orbit of the EMM around Mars, EMUS utilizes a dedicated strafe observation strategy to scan the illuminated Martian exosphere at tangential altitudes ranging from 130 to over 20,000 km. To distinguish between emissions of Martian origin and those from the interplanetary background, EMUS conducts specialized background observations by looking away from the planet. This approach has allowed us to investigate the radial and seasonal variations in Martian coronal emission features at H Lyman-alpha, beta and gamma wavelengths. Our analysis supports the previous studies indicating that Martian exospheric hydrogen Lyman emission brightness attains its highest levels around the southern summer solstice and reaches its lowest levels when Mars is near aphelion. Additionally, a secondary peak emission at all altitudes is observed after perihelion during Martian Year (MY) 36, which can be attributed to a Class C dust storm. Our study establishes a strong correlation between solar flux and coronal brightness for these emissions, highlighting the impact of solar activity on the visibility of Martian corona. In addition, we have examined interannual variability and found that emission intensities in MY 37 surpassed those in MY 36, primarily due to increased solar activity. These observations help to understand potential seasonal patterns of exospheric hydrogen, which is driven by underlying mechanisms in the lower atmosphere and solar activity, eventually suggesting an impact on water loss in the Martian atmosphere. Atomic hydrogen primarily forms as a product when Martian water undergoes various photochemical reactions. These hydrogen atoms encircle Mars and become illuminated by solar radiation, leading to the creation of Martian hydrogen corona. The Emirates Mars Ultraviolet Spectrometer (EMUS), on the Emirates Mars Mission spacecraft, is currently studying the Martian atmosphere using the ultraviolet light emissions of different atoms and molecules on Mars. In this study, we have analyzed EMUS observations and determined that atomic hydrogen emission intensities increase during the Martian southern summer and decrease as Mars moves farther away from the Sun. Furthermore, we have compared the hydrogen brightness between two consecutive Martian years and have found that the hydrogen brightness is higher in the most recent year primarily due to increased solar radiation. These observations help us understand possible patterns that occur during different seasons on Mars and the mechanisms underlying water loss in the Martian atmosphere. We present the variability in Martian atomic hydrogen brightness from early Martian year (MY) 36 to the first quarter of MY 37 Martian exospheric H Ly-beta and gamma emissions reach their peak brightness during the southern summer of MY 36 Martian corona is much brighter at H Ly-beta wavelength in MY 37 compared to the previous year due to increased solar irradiance