https://etd.auburn.edu/handle/10415/2 2026-08-20T11:45:44Z https://etd.auburn.edu/handle/10415/10649 Evaluating the Safety Performance of Centerline Rumble Strips in Alabama Villegas, Michelle Catheryn While research regarding the safety performance of centerline rumble strips (CLRS) has been studied nationally, no research has been conducted for Alabama. As such, the goal of this research is to assess the safety performance of CLRS in Alabama by executing the simple before-after and comparison group methodologies. The simple before-after analysis experienced reductions of -17.4%, -40.8%, and -45.1%, for total crashes, correctable, and correctable fatal and injury (FI) crashes, respectively. The comparison group analysis produced CMFs of 0.94, 0.62, and 0.61 for total crashes, correctable, and correctable FI crashes, respectively. Finally, changes in distribution for primary contributing circumstance and manner of crash were assessed for correctable and correctable FI crashes to evaluate CLRS efficacy across a variety of primary contributing circumstances and distribution of manner of crash commonly associated with crossover crashes. This research affirms the safety performance of CLRS and can support widespread implementation in Alabama. 2026-08-19T00:00:00Z https://etd.auburn.edu/handle/10415/10648 Artificial Intelligence in K-12 Education: An Investigation of Educators’ Stages of Concern, Perception, and Adoption Williams, Glory Generative artificial intelligence is transforming K-12 education, creating new advantages and significant challenges for educators. Guided by the Concerns-Based Adoption Model (CBAM), this quantitative study examined K-12 educators’ stages of concern regarding AI integration in education; differences in concerns by educator characteristics; the relationships among the stages of concern, perceptions of AI benefits and challenges in education, and adoption intentions. Participants included certified educators from a single public school district in the western United States who completed an adapted version of the Stages of Concern Questionnaire (SoCQ), along with additional survey items on demographics, AI tool use, and two open-ended questions. Quantitative data were analyzed using the SoCQ manual (George et al., 2006), descriptive statistics, Pearson correlations, independent-samples t tests, and one-way analyses of variance. Qualitative responses were analyzed using content analysis. Results indicated that most educators remained in the early stages of concern. AI experience showed stronger relationships with stages of concern than traditional demographics. Educators who reported being in the advanced stages of concern also reported increasingly positive perceptions of AI’s instructional benefits, greater willingness to adopt AI tools designed for educators, and more unease as it relates to ethical AI use. The findings suggest that educators’ responses to AI represent an evolving process rather than simple acceptance or resistance to innovation, even though a cross-sectional design methodology was employed. This study provides several AI implementation recommendations for school leaders, as well as several directions for further research. By applying the Concerns-Based Adoption Model to the emerging field of artificial intelligence, this study contributes to the growing body of knowledge on AI implementation in K-12 framework to support educators through a significant technological innovation. 2026-08-17T00:00:00Z https://etd.auburn.edu/handle/10415/10647 Experimental Evaluation of Shear and Flexure Behavior of Loblolly Pine Cross Laminated Timber Beams DiSalvo, Blake Cross-laminated timber (CLT) is a commonly used mass timber product that utilizes the strength, sustainability, and constructability advantages of timber while reducing many of the limitations associated with traditional timber construction. Recently, CLT has gained traction as a building material for protective structures due to its sustainability, improved resistance under short-duration loading, and ability to be rapidly deployed and assembled. However, design methods for CLT subjected to blast loading and other dynamic load applications are generally lacking. Such methods need robust understanding of the performance of CLT under quasi-static loading as a baseline for characterizing stiffness, strength, failure mechanisms, and post-peak responses that can then be used to quantify dynamic increase factors (DIF). This study experimentally evaluated the shear and flexure behavior of Loblolly Pine CLT beams subjected to quasi-static out-of-plane loading, with the primary objective of advancing and validating analytical methods for predicting the stiffness and expected strength. A total of 65 one-way bending beam tests were executed using a combination of contact-based sensors and Digital Image Correlation (DIC) techniques to capture the response of the CLT beams. The test matrix included varying the ply count, shear span-to-depth ratio, loading configuration, major/minor strength direction, and member width. The measured and calculated mechanical properties included the effective bending stiffness, apparent bending stiffness, effective shear rigidity, flatwise bending capacity, and flatwise rolling shear capacity. These values were compared to the predictions obtained using the shear analogy method as detailed in PRG-320 and PDC-TR 18-02. The study discovered that the ultimate strength predictions were generally conservative, but the degree of conservatism was dependent upon specimen geometry, loading configuration, and failure mode. The shear and flexural failures were highly dependent upon the shear span-to-depth ratio with shorter ratios resulting in shear failures and larger ratios resulting in flexural failures. The stiffness results follow similar trends to previous tests on comparable specimens with the apparent bending stiffness and the effective shear rigidity measuring higher than predicted and the effective bending stiffness measuring lower than predicted. The global response and post-peak behavior of the specimens was highly dependent upon the failure mode. The flexural failures were very brittle with sudden drops in the load carrying capacity of the beams. Conversely, the rolling shear failures developed more progressively and often displayed a gradual “stair-stepping” reduction in the load carrying capacity. Altogether, this study contributes toward a better understanding of the strength, stiffness, failure mechanisms, and residual response of Loblolly Pine CLT beams. 2026-08-17T00:00:00Z https://etd.auburn.edu/handle/10415/10646 Development of a Non-Equilibrium Plasma Coupled Rapid Compression Machine for Advanced Ignition Studies Bopaiah, Karan A plasma-coupled rapid compression machine (PRCM) was developed to investigate plasma-assisted combustion (PAC) under elevated-pressure and elevated-temperature conditions representative of end-of-compression (EOC) engine environments. The facility enables controlled comparison of autoignition, conventional spark ignition (CSI), and nanosecond pulsed discharge (ns-PD) ignition. The experimental approach combines time-resolved pressure measurements, synchronized electrical diagnostics (voltage, current, and energy deposition), and high-speed CH* chemiluminescence imaging to quantify early flame evolution and flame propagation. Baseline autoignition experiments established mixture reactivity under identical thermodynamic conditions. Methane exhibited single-stage ignition with monotonic reduction in ignition delay with increasing temperature, while n-butane showed two-stage ignition with a distinct negative temperature coefficient (NTC) regime, consistent with low-temperature chain-branching chemistry. Ignition experiments at 10 bar and 664 K were performed using CSI and ns-PD systems. Flame development time (FDT) and flame propagation time (FPT) were extracted from pressure traces to separate kernel formation from subsequent flame growth. CSI results show that ignition improvement is primarily governed by early breakdown energy and voltage rise rate, while additional dwell time increases post-kernel energy deposition with limited impact on FPT, indicating diminishing returns once a self-sustaining kernel is formed. Nanosecond pulsed discharge ignition was investigated using three geometries to understand the contribution of distinct glow and spark regimes towards ignition enhancement. Experiments were performed over pulse repetition frequencies (1–100 kHz), voltages (24–29 kV), and pulse counts up to 100 pulses, with selected cases held at constant total energy (~95 mJ) to isolate inter-pulse coupling effects. Compared to CSI, ns-PD ignition reduced both FDT and FPT, with performance strongly dependent on discharge morphology. High-speed CH* chemiluminescence imaging at 25 kHz was used to resolve ignition kernel evolution and flame propagation. Results show that spark-containing discharges produce larger initial kernels due to rapid thermalization, while glow-dominated discharges exhibit slower initial growth but accelerated late-stage flame propagation. Area-averaged emission reveals an initial post-discharge decay in CSI and spark systems due to relaxation of excited species, whereas glow-dominated discharges show smoother evolution due to sustained radical production. Lean-burn experiments demonstrated improved ignition robustness for ns-PD systems relative to CSI, extending the practical lean limit to φ = 0.45 with improved cycle-to-cycle variability. Collectively, these studies advance the experimental understanding of plasma-assisted combustion by establishing the relationships between discharge morphology, energy deposition, inter-pulse coupling towards combustion enhancement. The resulting database provides a comprehensive benchmark for the development, validation, and refinement of plasma-assisted combustion models and PAC-specific chemical kinetic mechanisms applicable to practical high-pressure combustion systems. 2026-08-14T00:00:00Z