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.
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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
Analysis of the Multi-Scale Spatial Heterogeneity of Factors Influencing the Electric Bike-Sharing Travel Demand in Small and Medium-Sized Cities
Wang, Xin; Peng, Zhiyuan; Li, Xuefeng; Du, Mingyang; Lyu, Fangzheng; Kang, Jeon-Young; Lee, Kangjae; Liu, Dong (MDPI, 2025-11-21)
The spatial heterogeneity of the electric bike-sharing (EBS) travel demand in small and medium-sized cities is influenced by a combination of the built environment, socio-economic gradients, transportation accessibility, and residents’ travel behavior patterns, and is significantly different from the shared travel characteristics of developed cities. In order to explore the influencing mechanisms of the EBS travel demand under different travel distance scales in small and medium-sized cities, this paper utilizes multi-source data from Tongxiang, Zhejiang Province, including operational data of EBS and built environment data. This paper analyzes the impact of the built environment on the EBS travel demand and its spatial heterogeneity across various distance scales from a local perspective. The results demonstrate that the fit of the multiscale geographically weighted regression (MGWR) model is superior to that of the geographically weighted regression (GWR) and the ordinary least squares (OLS) model. The explanatory variables exhibit significant spatial heterogeneity in their influence on the demand for EBS trips across different distance scenarios. The density of primary roads demonstrates a positive correlation with EBS travel demand in the western urban core area, but it is negatively correlated with travel demand in the eastern urban core area. Accommodation services show a negative correlation with long-distance EBS travel demand in the urban core area and the northern city, but they are positively correlated with short-distance EBS travel demand in the urban core area. There is competition between long-distance EBS and public transportation in city centers. However, short-distance EBS and public transportation exhibit a complementary relationship in the urban periphery. The research findings are beneficial for gaining a deeper understanding of the patterns of change in the EBS travel demand and promoting the refined and sustainable development of shared transportation.
Time-Based Capnography to Diagnose Airway Obstruction During Lung Lobectomy in a Dog
Ishihara, Toshitsugu; Chang, Li-Jen (MDPI, 2025-11-21)
A 10-year-old, 7.0 kg, female spayed mixed-breed dog presented for a second opinion regarding lobectomy for a lung mass. Mechanical ventilation was initiated due to hypercapnia (ETCO2 of 61 mmHg) with PIP of 8 cmH2O. The PIP was gradually increased to 16 cmH2O. Six minutes after increasing PIP to 16 cmH2O, ETCO2 suddenly dropped to 0 mmHg and the capnography waveform was lost. The endotracheal (ET) tube connection to the ventilator circuit was intact, and no visible abnormalities were noted on the ET tube. Although the ETCO2 sampling line and water trap, and the monitor were replaced, the ETCO2 remained at 0 mmHg. Meanwhile, suspecting obstruction within the ET tube or the airway, extubation was performed. A large blood clot in the ET tube was noticed. Reintubation was performed using a new ET tube and mechanical ventilation was restarted with PIP set to 10 cmH2O. The ETCO2 showed a reading of 55 mmHg. Five minutes after reintubation, the ETCO2 waveform disappeared again. The inside of ET tube was suctioned, and a blood clot was again identified. Clinicians should be aware of these risks when performing lung lobectomy without one lung ventilation.
Methodology for Real-Time Hydroplaning Risk Estimation Using an Intelligent Tire System: An Analytical Approach
Vilsan, Alexandru; Sandu, Corina; Anghelache, Gabriel; Warfford, Jeffrey (MDPI, 2025-11-30)
This study presents a real-time capable methodology for quantifying the hydroplaning risk of a passenger car tire using data from an intelligent tire system. An analytical water lift force formulation is applied to convert measured peak lift force values into longitudinal water velocity. Based on the water velocity and groove dimensions, the intake flow rate that the tire must evacuate is estimated. Hydroplaning risk is then defined as the ratio between the intake flow rate and the maximum flow capacity of the tire before total hydroplaning occurs. Experimental investigations under real-world conditions were carried out at 45 mph and 65 mph, yielding average hydroplaning risk values of 12.6% and 21.3%. The proposed model was validated by performing hydroplaning tests under a controlled water depth of 1 mm at Michelin Laurens Proving Grounds. The hydroplaning risk values computed by the intelligent tire system were compared with reference data from the literature obtained under similar test conditions. Additionally, the critical hydroplaning speed of the test tire was estimated and compared against predictions from established numerical models, such as those proposed by Gengenbach and Spitzhüttl. The methodology is confirmed as a reliable algorithm for real-time hydroplaning risk monitoring with the potential to improve vehicle safety.
An Ergonomic Design and Evaluation of a Chair with a Flexible Seat Pan for the Maintenance of Correct Sitting Posture
Park, Seongwoo; Rho, Joohwee; Tak, Yohan; Lee, Wonsup; Park, Chanwook (MDPI, 2025-12-01)
This study evaluates the ergonomic benefits of a novel chair featuring a four-segment flexible seat pan designed to support correct sitting posture. Motion capture and electromyography tools are used to quantitatively assess the impact of different chair designs on pelvic and lumbar angles and muscle usage through two ergonomic experiments (short- and long-term). In the short-term experiment (30 participants), the proposed chair demonstrated significant improvements in maintaining the spine’s S-shape, with hip and lumbar angle enhancements of up to 15.3° compared to a conventional chair. The long-term experiment (20 participants) revealed that the proposed chair led to a more favourable muscle fatigue profile during prolonged sitting, with a 47% decrease at lower frequencies (0 to 20 Hz) and a 34% increase at higher frequencies (60 to 80 Hz) compared to the conventional chair, indicating reduced muscle fatigue. These results suggest that the proposed chair can significantly improve posture and reduce fatigue in settings that require prolonged sitting.
Elevated Soybean Seed Oil Phenotype Associated with a Single Nucleotide Polymorphism in GmNFR1α
Patibandla, Sri Veda; Carrero-Colón, Militza; Song, Qijian; Qin, Quilin; Clevinger, Elizabeth; Zhu, Hongyan; Maroof, M. A. Saghai; Hudson, Karen (MDPI, 2025-12-03)
Soybean seed composition, particularly the oil and protein content of the seed, has been a longstanding focus of research due to the economic and nutritional importance of these components for both feed and industrial applications. Through forward genetic screening of a mutagenized population derived from the soybean cultivar Williams-82, a mutant line designated PID 17238 was identified for high seed oil content. This phenotype is associated with a decrease in levels of protein with respect to Williams-82. The phenotype was mapped to chromosome 2 to a region near Satt459. Fine mapping and whole-genome resequencing were used to identify the causative mutation. Analysis of the resequencing data within the candidate region uncovered 55 sequence variants. Glyma.02G270800 contained a single nucleotide polymorphism (SNP) within the coding sequence. Glyma.02G270800 encodes a lysin motif (LysM) receptor-like kinase previously reported in the literature as GmNFR1α. Importantly, this locus is allelic to the well-characterized rj1 locus, a recessive mutation known to cause a non-nodulating phenotype in soybean. Nodulation in soybeans, which enables nitrogen fixation, is crucial for protein synthesis in seeds, and the lack of nodulation may explain the lower protein content in PID 17238.