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.
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Virginia Tech's open access policy enables researchers to deposit the accepted version of scholarly articles with no embargo.
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Virginia Tech was first in the world to require ETDs in 1997, and continues to add scans of older theses and dissertations.
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More than 50 freely available and openly licensed textbooks are among our most downloaded items.
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Recent Submissions
CFT Connections: State-of-the-art Report and Numerical Validation by 3D FEM
Wilches, Jose; Leon, Roberto; Maria, Hernan Santa; Graterol, Anibal (Korean Society for Steel Construction-KSSC, 2024-08-01)
Connections between concrete filled members are common in tall buildings, bridges, and offshore structures because of their robust structural performance. While extensive research has been done on isolated concrete-filled structural members, relatively little research has been conducted on composite connection regions. This article first describes a database on experimental/analytical investigations on concrete-filled connections comprising 135 tests. It then develops a generic numerical model capable of capturing the entire range of behavior of these connections, including local buckling of the steel tubes and friction/contact resistance between steel and concrete. The model was calibrated against a single test and its performance was verified against three other very different tests. The results indicate that the four models can track well the strength and stiffness of the specimens up to ultimate and predict well different failure patterns. Comparisons of the experimental and numerical load-deformation curves show very good agreement in predicting the strength and deformations at which different behaviors arise, and that performance is controlled primarily by both the strength of the concrete and the confinement effect of the steel tube in the connection area.
Solvent-Mediated, Reversible Ternary Graphite Intercalation Compounds for Extreme-Condition Li-Ion Batteries
Tao, Lei; Xia, Dawei; Sittisomwong, Poom; Zhang, Hanrui; Lai, Jianwei; Hwang, Sooyeon; Li, Tianyi; Ma, Bingyuan; Hu, Anyang; Min, Jungki; Hou, Dong; Shah, Sameep Rajubhai; Zhao, Kejie; Yang, Guang; Zhou, Hua; Li, Luxi; Bai, Peng; Shi, Feifei; Lin, Feng (American Chemical Society, 2024-06-07)
Traditional Li-ion intercalation chemistry into graphite anodes exclusively utilizes the cointercalation-free or cointercalation mechanism. The latter mechanism is based on ternary graphite intercalation compounds (t-GICs), where glyme solvents were explored and proved to deliver unsatisfactory cyclability in LIBs. Herein, we report a novel intercalation mechanism, that is, in situ synthesis of t-GIC in the tetrahydrofuran (THF) electrolyte via a spontaneous, controllable reaction between binary-GIC (b-GIC) and free THF molecules during initial graphite lithiation. The spontaneous transformation from b-GIC to t-GIC, which is different from conventional cointercalation chemistry, is characterized and quantified via operando synchrotron X-ray and electrochemical analyses. The resulting t-GIC chemistry obviates the necessity for complete Li-ion desolvation, facilitating rapid kinetics and synchronous charge/discharge of graphite particles, even under high current densities. Consequently, the graphite anode demonstrates unprecedented fast charging (1 min), dendrite-free low-temperature performance, and ultralong lifetimes exceeding 10 000 cycles. Full cells coupled with a layered cathode display remarkable cycling stability upon a 15 min charging and excellent rate capability even at -40 degrees C. Furthermore, our chemical strategies are shown to extend beyond Li-ion batteries to encompass Na-ion and K-ion batteries, underscoring their broad applicability. Our work contributes to the advancement of graphite intercalation chemistry and presents a low-cost, adaptable approach for achieving fast-charging and low-temperature batteries.
Further regularity results in P- extremal setting
Perera, Menuja (Springernature, 2024-12-01)
In our paper, Pluripotential theory and convex bodies: a Siciak-Zaharjuta theorem (Computational Methods and Function Theory (2020), 20(3-4), 571-590) by Bayraktar et al., we proved a regularity result of P-extremal function. In this paper, we prove some other stronger regularity results analogue to those in the standard setting. Specifically we focus on proving the following proposition: Proposition: Let K = Dsubset of C-d be the closure of a bounded domain D with partial derivative D of class C-1,C-1. Then, for any Q is an element of C-alpha(K), where C-alpha(K) is the H & ouml;lder class alpha on K, we have V-P,V-K,V-Q is an element of C-alpha(C-d) for a convex body P subset of(R+)(d).
Spatial Intracranial Pressure Fields Driven by Blast Overpressure in Rats
Norris, Carly; Murphy, Susan F.; Talty, Caiti-Erin; VandeVord, Pamela J. (Springer, 2024-10-01)
Free-field blast exposure imparts a complex, dynamic response within brain tissue that can trigger a cascade of lasting neurological deficits. Full body mechanical and physiological factors are known to influence the body's adaptation to this seemingly instantaneous insult, making it difficult to accurately pinpoint the brain injury mechanisms. This study examined the intracranial pressure (ICP) profile characteristics in a rat model as a function of blast overpressure magnitude and brain location. Metrics such as peak rate of change of pressure, peak pressure, rise time, and ICP frequency response were found to vary spatially throughout the brain, independent of blast magnitude, emphasizing unique spatial pressure fields as a primary biomechanical component to blast injury. This work discusses the ICP characteristics and considerations for finite element models, in vitro models, and translational in vivo models to improve understanding of biomechanics during primary blast exposure.
How good are large language models at product risk assessment?
Collier, Zachary A.; Gruss, Richard J.; Abrahams, Alan S. (Wiley, 2025-04-01)
Product safety professionals must assess the risks to consumers associated with the foreseeable uses and misuses of products. In this study, we investigate the utility of generative artificial intelligence (AI), specifically large language models (LLMs) such as ChatGPT, across a number of tasks involved in the product risk assessment process. For a set of six consumer products, prompts were developed related to failure mode identification, the construction and population of a failure mode and effects analysis (FMEA) table, risk mitigation identification, and guidance to product designers, users, and regulators. These prompts were input into ChatGPT and the outputs were recorded. A survey was administered to product safety professionals to ascertain the quality of the outputs. We found that ChatGPT generally performed better at divergent thinking tasks such as brainstorming potential failure modes and risk mitigations. However, there were errors and inconsistencies in some of the results, and the guidance provided was perceived as overly generic, occasionally outlandish, and not reflective of the depth of knowledge held by a subject matter expert. When tested against a sample of other LLMs, similar patterns in strengths and weaknesses were demonstrated. Despite these challenges, a role for LLMs may still exist in product risk assessment to assist in ideation, while experts may shift their focus to critical review of AI-generated content.