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Uncertainty quantification of turbulent premixed flames
Get PDFThis thesis presents an uncertainty quantification (UQ) study of turbulent premixed flames, focusing on the impact of uncertainties in operating conditions on the normalized consumption speed. Namely, temperature, pressure, and equivalence ratio are the operating conditions that are under study. Due to significant computational demands associated with direct MC methods for UQ, surrogate modeling techniques including Polynomial Chaos Expansion (PCE), Stochastic Collocation (SC), and Gaussian Process (GP) are evaluated based on efficiency and accuracy. Through this study, PCE is identified as the optimal surrogate model due to its accuracy and significantly reduced computational costs. PCE is subsequently applied to investigate how variability in temperature, pressure, and equivalence ratio affect the normalized consumption speed of turbulent premixed flames. Results highlight that the normalized consumption speed has considerable sensitivity to variations in temperature and equivalence ratio, with nonlinear behaviors shown through probability density functions and statistical metrics. Pressure variations had only small impacts on the normalized consumption speed of turbulent premixed flames. The framework employed in this study can be applied to other complex combustion simulations
The effects of No Child Left Behind on teachers’ perceptions of their chosen profession
Get PDFSince the enactment of NCLB (2001), it has been the source of major controversy. And although it was replaced by the Every Student Succeeds Act in 2015, its impact is still apparent. NCLB’s intention was to ensure that all students in the United States had equal access to a high-quality education, regardless of race, gender, ability, or socioeconomic status (Mills, 2008). To achieve this goal, the Act introduced new requirements surrounding teachers, testing, and school improvement. These requirements have led to, among other things, teacher dissatisfaction. To identify the sources and level of dissatisfaction, a survey was distributed to teachers in east Tennessee, asking questions regarding curriculum and assessment post-NCLB. The survey results show state and standardized testing are the main causes of dissatisfaction. While the focus of policymakers remains on testing and test scores, this dissatisfaction is not likely to decrease
Observations of silicified stromatolites from the late Cambrian-early Ordovician of Adairsville, Georgia
Get PDFThis study describes and analyzes silicified stromatolite samples collected near Adairsville, Georgia, from Cambrian–Ordovician system rocks likely belonging to the Copper Ridge Dolomite of the Knox Group. Using the classification system outlined by Grey and Awramik (2020), the stromatolites were systematically described at the macro-, meso-, and microscales. The samples display two primary mesostructural morphologies—branched-bifurcate and layered-linked columnar forms—with non-couplet lamination, smooth to wavy laminae, moderate to high synoptic relief, and alternating microlaminae textures. Unlike previous studies of stromatolites from nearby Murray County, Georgia the stromatolites samples from Adairsville, Georgia preserve well-defined mesoscale and microscale lamination visible in thin section under plane polarized light (PPL), suggesting better early silicification and reduced diagenetic overprinting. Dolomite rhombs, chalcedony veins, and voids document a complex multi-phase diagenetic history involving early dolomitization and subsequent silica replacement. Although no clearly recognizable microfossils were found, the preserved laminar fabrics, curious brown spherical features in some samples, and consistent microbialite structures support a biological origin linked to microbial mat growth in a shallow subtidal to intertidal environment. This study contributes to a broader effort to document stromatolite-bearing formations in northwest Georgia and highlights the need for further petrographic, Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy, and fluid inclusion studies to better constrain the diagenetic pathways and microbial signatures preserved within the Knox Group of northwest, Georgia
Mathematical modeling of zoonotic disease transmission under the impact of land use change
No full textLand conversion is occurring worldwide due to a growing population and expanding economy. This process increases the likelihood of pathogen spillover, posing significant economic and public health risks. The objective of this thesis is to model pathogen spillover under the impact of land use change. We develop a zoonotic disease transmission model that describes spillover of Puumala virus from bank voles to humans during land conversion. Our model introduces a land conversion index to capture the dependence of the carrying capacity and the death rate of bank voles on the proportion of converted land. This index is then used to examine how different levels of land conversion influence pathogen spillover. Through simulations, we demonstrate that the risk of pathogen spillover from bank voles to humans is highest at lower levels of land conversion
Exploring community violence, anxiety and substance use among Black adults
No full textThe impact of community violence on Black individuals, remains a concern. Despite statistics showing the disproportionate rates of violence among Black individuals, there is a gap in understanding its effects on Black adults. This current study examined how the perception of community violence influences anxiety levels among Black adults. It is suggested that heightened anxiety, stemming from exposure to violence, contributes to maladaptive coping, such as substance use, as individuals attempt to alleviate distress. Among a sample of 202 black adults, we found that higher exposure to community violence (ECV) had a relationship with increased substance use (SU) and anxiety. Similarly, it was discovered that individuals with higher anxiety had higher substance use scores. Although, anxiety did not moderate the relationship between SU and ECV. Further, perceptions of violence in the community related to harm and challenge were associated with higher anxiety levels. Limitations, future directions, and implications are discussed
Mathematical model for tripledemic disease (COVID-19, RSV, and Influenza)
Get PDFThe concurrent circulation of COVID-19, Influenza (Flu), and Respiratory Syncytial Virus (RSV), collectively termed the ”Tripledemic,” poses substantial public health challenges due to their overlapping transmission patterns and compounded healthcare demands. The discovery of COVID-19 vaccines such as Moderna (mRNA-1273, Spikevax) and Johnson & Johnson’s, among other vaccines, has reduced COVID-19 cases but has not completely eradicated the disease. In the 2022-2023 season, the world witnessed a ”tripledemic” of Flu, COVID-19, and RSV. We propose Susceptible-Infectious-Recovered (SIR) and SusceptibleExposed-Infectious-Recovered (SEIR) mathematical models to estimate transmission rates, compute the basic reproduction number, forecast infections, and analyze seasonal variations and comparative transmission dynamics among the three diseases. Our models are applied to seasonal weekly rate cases reported by the CDC from fifteen sites across the United States. Our results indicate that COVID-19 and RSV will eventually die out. However, influenza is expected to continue to circulat
Sexism in syntax: language and its relationship with female leadership
Get PDFDespite a global trend towards more equal gender representation, not every country has improved at the same pace or to the same level. This study investigates language as a potential tool for better understanding the differences between countries regarding the presence of female managers. By using language as a tool, I arrive at two primary results: (i) pronoun drop is significantly and inversely associated with the presence of female managers, but gendered language structures have little association, and (ii) a gender intensity index can produce misleading results. These results suggest that language structures, such as pronoun drop, which are associated with collectivism, may also be associated with lower levels of female leadership in businesses. However, those language structures that directly emphasize sex do not make that much of a difference
Analysis of signal resampling effects on attention-driven SEI for IoT systems
No full textThe rapid growth of the Internet of Things (IoT) has connected billions of devices, many with minimal security, making them vulnerable to attacks. Specific Emitter Identification (SEI) offers a passive and reliable security solution by identifying devices through their unique hardware features, enabling serial number level distinction without altering the emitter. SEI can serve as the “something the entity is” factor in zero-trust multi-factor authentication frameworks. However, conventional SEI methods rely on high sampling rates, which are impractical for resource-limited IoT devices. This work evaluates an attention-based SEI model that maintains high identification accuracy at reduced sampling rates. The proposed approach achieves over 97% accuracy using only 2,500 signals sampled at 5 MHz and sustains above 90% accuracy under Rayleigh fading, reducing memory usage by 87.5% without compromising performance. These results highlight the potential of attention mechanisms for efficient, scalable IoT device identification
Child development: a Developmentally Appropriate Practices approach, second edition
No full textThe book follows a topical approach and covers children from prenatal to late childhood/early adolescence. The book follows a Developmentally Appropriate Practices approach, emphasizing that development results from the interaction of age-related expectations, culture and context, and individual child characteristics. The text is written for education majors, as well as others who will work with children and families in a variety of fields, including psychology, social work, nursing, and others.https://scholar.utc.edu/open-textbooks/1007/thumbnail.jp
Modeling reactive rarefied flows in Chemical Vapor Infiltration using Direct Simulation Monte Carlo
Get PDFChemical Vapor Infiltration (CVI) is a key method for fabricating silicon carbide (SiC) matrix composites. Gas-phase precursors flow into a porous fiber, react, and deposit to form the ceramic matrix. Deposition quality and rate are strongly influenced by surface reactions, depending on temperature, gas flow, and reactor pressure. This study applies a computational model to better understand rarefied gas behavior and surface chemistry during CVI. We use the Direct Simulation Monte Carlo method to simulate gas flow and chemical reactions around the fibers. Simulations span Knudsen numbers 0.001–20 and temperatures 1000–1600 K (near‑continuum to free‑molecular). As rarefaction increases, deposition rate decreases, yet temperature remains significant. In forced‑flow CVI, deposition becomes uneven: the fiber\u27s inlet side grows more, the opposite side less. To improve gas‑phase chemistry accuracy, we adapt a Quantum‑Kinetic model for methyltrichlorosilane and chlorine reactions. Overall, it clarifies how rarefied gas dynamics and activation energy control CVI