Open Research Oklahoma (Oklahoma State Univ.)
Not a member yet
42035 research outputs found
Sort by
Development of a quantitative Wildland Urban Interface fire resilience assessment model
No full textWildland-Urban Interface (WUI) fires are growing in frequency and intensity as communities continue to develop in wildland areas and climate change increases fire season severity, posing a great risk to people and structures within these communities. In the United States, risk mitigation is typically handled through a prescriptive approach that establishes an intended level of resilience, i.e., the adoption of codes and standards. However, a disconnect exists between intended resilience and actual resilience observed during fire events. Intended resilience reflects system performance as agreed upon by code developers, while actual resilience emerges from complex interactions during a fire. Often, these complex interactions are not covered by prescriptive codes and are difficult to accurately represent through performance-based modeling (PBD). This research aims to bridge the gap between intended and actual resilience through a novel conceptual modeling approach to visualize and quantify both intended and actual resilience in WUI communities. Two conceptual maps were developed using qualitative analysis: one from WUI codes, standards, and guidelines (intended resilience), and another from fire investigation reports from the 2018 Camp Fire and 2023 Lahaina Fire (actual resilience). Each map visualizes the relationships between resilience concepts, allowing the user to better understand the complexity of code requirements as well as interactions during a real WUI fire event. These two maps were implemented into a Microsoft® Excel®-based tool that includes a computational framework for quantifying resilience. By assigning performance scores, weighting factors, and a directional constant, the tool propagates the scores through the conceptual hierarchy to calculate the overall resilience scores for a community. The models allow authorities in WUI communities to assess community resilience, compare intended versus actual resilience, and identify how to best use resources to improve their community’s resilience scores. The models are intended to continuously evolve through field testing, expert feedback, and incorporation of additional literature. The findings highlight a mismatch between prescriptive intent and real-world outcomes, with actual fires containing much more complex interactions. Also, a noticeable lack of the recovery phase of emergency management is present in both the codes and reports. The proposed tool allows WUI communities to step away from a purely prescriptive approach and towards a more performance-based approach to WUI fire risk mitigation that better represents the complex interactions that occur during WUI fires. This research advances fire safety and emergency management theory and offers a practical solution to assess community resilience
Formation of amide bonds using acid fluorides and germylamines: A versatile method for the generation of peptide linkage
No full textThe formation of the amide linkage is a fundamentally important process since these are relevant in biological systems and pharmaceuticals. It was recently demonstrated that germylamines R₃GeNR’₂, which have previously been used as synthons for a wide variety of oligogermanes, are useful reagents for the conversion of acid fluorides to amides. The pathway of this reaction occurs via sigma bond metathesis as determined using density functional theory, and it has a very low activation energy barrier such that it proceeds rapidly at room temperature.The focus of this investigation is the determination of the scope and limitations of the amidation reaction of acid fluorides by germylamines. It was demonstrated that the germylamines Ph₃GeNMe₂, Buⁿ₃GeNMe₂, and Prᶦ₃GeNMe₂ converted an array of 13 different aryl acid fluorides to their corresponding dimethylamides in generally high yields. The acid fluorides employed had diverse substitution patterns and included both a thiophene and a ferrocene acid fluoride. Additionally, in order to confirm the formation of the germanium fluoride byproducts by ¹⁹F NMR spectroscopy Buⁿ₃GeF and Pri₃GeF were synthesized from the corresponding germanes R₃GeH and [Ph₃C][BF4]. This is a useful method for the preparation of fluorogermanes that circumvents the use of hydrogen fluoride.
In contrast, recently it has been shown that the sterically encumbered germylamine Ph₃GeN(SiMe₃)₂ does not convert acid fluorides to amides. After obtaining the crystal structure it was shown that the germanium atom in this species was completely encapsulated by the substituents causing its lack of reactivity. DFT studies also indicated that the energies of the frontier orbitals in Ph₃GeN(SiMe₃)₂ also affect its reactivity
Machine learning based modeling and designing of cyclorotor for an eVTOL aircraft
No full textThe rise of electric vertical take-off and landing (eVTOL) vehicles has received significant attention in recent years because of their potential to transform transportation and solve key challenges in urban air mobility. These vehicles offer a variety of potential advantages, including lower environmental impact, improved energy efficiency, reduced noise, and operational flexibility and accessibility. However, majority of the existing eVTOL platforms face limitations in range, endurance, and payload capability. This thesis explores the use of a novel propulsion system, known as cycloidal rotor, that has the potential to overcome the limitations of existing eVTOL platforms. One of the key advantages of the cycloidal rotor is its instantaneous 360° thrust vectoring capability. This enables it to be used as a primary propulsion system for both vertical take-off landing (VTOL) and cruise conditions.
A key contribution of the thesis is the development of a computationally efficient cycloidal rotor aerodynamic model that can be utilized for preliminary vehicle design and optimization purposes. The developed aerodynamic model utilizes a novel physics-guided neural network (PGNN) architecture that combines a physics-based unsteady aerodynamic model with a neural network (NN). Validations with existing experimental data show remarkable accuracy of the developed PGNN model. In the next step, this cycloidal rotor model is utilized for the conceptual design of an eVTOL aircraft propelled by a set of cycloidal rotors. After developing a baseline configuration, a coupled-trim model of the entire aircraft is developed by combining vehicle response equations with the trim equations of the aircraft. This model predicts the control inputs required to balance the forces and moments for a steady-level flight and also computes the cycloidal rotor performance corresponding to the predicted control inputs. This coupled trim model is further leveraged to perform systematic parametric study while designing key parameters of the cycloidal rotors and other aircraft components. The performance of the final designed cycloidal rotor is verified through high-fidelity CFD simulations. The present study along with the developed computational models forms an important foundation for developing a cycloidal rotor-based eVTOL aircraft
Evaluation of low value lipids for thermal storage applications
No full textThe urgent need to reduce greenhouse gas emissions necessitates a shift from fossil fuels to clean energy sources. Renewable energy sources like solar and wind offer enormous potential, but their intermittency requires efficient thermal energy storage (TES), where phase change materials (PCMs) play a vital role.
PCMs which absorb and release latent heat during phase change, are important components of TES systems. This study examined viability of low value lipids, byproducts of crude vegetable oil refining and food production as PCMs. Four different types of animal fats, pork, goat, lamb, beef, and crude sunflower oil wax were examined as potential alternatives to highly refined, costly and petroleum based PCMs like stearic, palmitic and lauric acids, paraffin and plant-based waxes from soy and sunflower oils.
Results showed that phase change temperature and thermal stability of low value lipids were similar to those of the refined commercial products. High saturated fatty acid content of beef, lamb and goat fat makes them suitable as PCM. Yet, the presence of highly unsaturated fatty acids in pork fat excludes its potential as PCM but can be used in sensible heat storage. Highly refined commercial samples had higher thermal conductivity and phase change enthalpy than the crude samples. The substandard quality of the low value crude lipids was shown to be due to improper processing and handling conditions, hence, thermal properties of these materials can easily be improved by downstream processing/refining.
Furthermore, eastern red cedar wood, an underutilized, locally available and low-cost material, was demonstrated as a potential resource for high porosity carbon, serving as a support material for lipid shape stabilization. All lipid samples were successfully loaded into carbon pores by vacuum impregnation, though optimization is needed. Converting animal fats to their fatty acid methyl esters improved shape stabilization efficiency of the products.
In conclusion, low value lipids present a promising alternative to expensive, refined PCMs, exhibiting suitable phase change temperatures, high thermal stability, and moderate activation energy. These materials may be utilized as PCMs in low-temperature solar units, building and electronic device temperature control, and on-farm heating and cooling applications, and small-scale processing facilities
Social Presence Enabled Augmented Reality (SPEAR) tool for online engineering education
No full textTraditional online engineering education often faces challenges such as student disengagement, lack of hands-on learning, and limited interaction, which can negatively affect motivation and comprehension. Emerging technologies, particularly Augmented Reality (AR), have shown promise in enhancing learning experiences by providing immersive, interactive environments. However, the integration of AR with social presence features to foster collaboration and improve motivation in online engineering education has not been thoroughly explored. This dissertation addresses this gap by introducing and evaluating the Social Presence Enabled Augmented Reality (SPEAR) tool, a novel AR-based application designed to improve student engagement, comprehension, and performance in online engineering education. SPEAR leverages the AR Foundation framework within the Unity game engine to create an interactive learning experience focused on structural beam-bending mechanics. The tool enables users to manipulate 3D virtual beams in real-world environments, offering real-time simulations of beam deformation using a custom C# script based on the Finite Element Method. Visualizations of moment/shear diagrams and bending stresses enhance the learning process. A key feature of SPEAR is the integration of a cloud-based voice chat powered by Photon Unity Networking (PUN) 2, which fosters social presence, enabling collaborative learning among users. The effectiveness of SPEAR was assessed through a combination of academic achievement tests, surveys on social presence, and the Instructional Materials Motivation Survey (IMMS), based on the ARCS model. The results demonstrated that the inclusion of social presence features in AR tool significantly improved students’ academic performance, motivation, and peer interaction compared to the control group. Focus group discussions further revealed that the integration of voice chat reduced feelings of isolation and improved comprehension of complex engineering concepts, fostering enhanced collaboration. This dissertation highlights the potential of SPEAR to transform online engineering education by providing an immersive, collaborative learning environment. It contributes to the pedagogical applications of AR in education and offers insights into future research on interactive and engaging online learning technologies
Natural disasters and internal migration in southwest coastal Bangladesh
No full textNatural disasters in coastal Bangladesh are a regular phenomenon, affecting thousands of people every year. The vulnerable population survives these situations either by migrating elsewhere and/or seeking external assistance. The decision to migrate is not an easy one to make, as there are numerous sociocultural barriers and obstacles to moving to a new place with uncertainties. This research explores the following research question: “How do natural disasters impact internal migration in southwestern coastal Bangladesh?” A series of hypotheses is derived from a combination of push-pull migration theory, the new economics of labor theory, the concept of renewable resource communities (RRC), and perceptions of the Bangladeshi government’s ability to help its citizens after a natural disaster. The study employs secondary survey data of 4000 households, employing a quantitative approach of bivariate and multivariate (zero-inflated negative binomial model) analysis, this study examines how heads of household in coastal Bangladesh make their migration decisions. The findings show that the head of the household will migrate more if the household has a lower socioeconomic status, and they rely on fishing for income. Additionally, it also explores the reasons why individuals might decide to stay despite experiencing economic loss. The thesis next illustrates how the coastal region of Bangladesh can be considered a RRC and then highlights the influence of effective local government on migration decisions. The Discussion and Conclusion section situates the findings in the literature, discusses limitations and possibilities for future research
Interpreting between my parents and siblings: The emotional and relational impact of Intra-Family Language Brokering on Latino youth
No full textThis dissertation explores Intra-Family Language Brokering (IFLB), a phenomenon in which Latino youth interpret between family members, particularly between parents and siblings, due to experiencing Shared Language Erosion (SLE). As language fluency diverges within immigrant families often between generations or siblings, youth who are more proficient in English or Spanish assume the role of broker to sustain family communication. Using a mixed-methods design, this study examines the emotional and relational consequences of IFLB and its role in family functioning. Study 1 draws on survey data from 131 Latino youth in Oklahoma to assess the frequency of IFLB, its impact on family dynamics, and the emotional experiences of Youth Providing Language Brokering (YPLB). Descriptive statistics, correlation analyses, and Exploratory Factor Analysis (EFA) reveal patterns in emotional outcomes. Study 2 includes in-depth interviews with eight youth across eight families, analyzing how brokering roles are shared, negotiated, and emotionally interpreted. Thematic analysis uncovered strategies youth use to manage linguistic limitations, the moral and emotional labor involved in brokering, and the nuanced power dynamics in sibling and parent-child communication. Findings show that IFLB is more than an “act of interpreting” ; it is a deeply relational and developmentally significant practice. Youth often serve as cultural and emotional mediators, demonstrating adaptability, emotional regulation, and moral reasoning. The Family Resilience Framework was applied to interpret these findings, revealing how IFLB activates adaptive systems (emotion, control, meaning, and maintenance) in response to SLE. While IFLB can support cohesion and agency, it may also generate role confusion and emotional strain, especially when youth are unequally burdened. This research extends our understanding of family resilience in immigrant contexts, positioning IFLB as both a stressor and strength. It contributes to Human Development and Family Science by integrating cultural, emotional, and developmental dimensions into the study of language brokering. The study offers implications for educators, clinicians, and policymakers to better support bilingual youth navigating linguistic responsibilities within families experiencing SLE
Exploring academic advising for students from historically marginalized racial backgrounds at large, public, four-year predominantly White U.S. institutions
No full textThe purpose of this study was to explore the personal and professional experiences and beliefs, in addition to professional practices, of academic advisors at a large, predominantly White, public four-year U.S. institution in their work with students from historically marginalized racial backgrounds (HMRBs). Some studies suggested that students from HMRBs attributed experiences of discrimination and low sense of belonging at PWIs (Shearman et al., 2023; Tausen et al., 2023; Wood & Harris, 2022). Other studies suggested that a lack of precollege preparation (Thiem & Dasgupta, 2022), financial literacy (Blanco et al., 2022), and socioeconomic factors (Klonoski et al., 2017) attributed to the lower success of students from HMRBs than their White peers. The multiple case study specifically focused on concerns and meaning-making related to seven undergraduate academic advisors at one large, predominantly White, public, four-year US institution who worked with students from HMRBs. Each participant’s experiences were examined through two in-depth interviews and an online questionnaire.
This study applied a posteriori theories to the data collected. Six findings emerged from the data analysis. First, academic advisors’ race mattered to their understanding of, and application of practices for serving students from HMRBs. Second, advisors worked in a colorblind institutional space where a colorblind agenda and practices framed how academic advisors worked with students from HMRBs. Third, White advisors within the study did not seem to understand racialized occurrences, particularly the impact of colorblindness and White fragility, in academic advising. Fourth, White advisors did not know how to help students from HMRBs, in part based upon the lack of training provided by the institution. Fifth, at a cost to personal and professional well-being, Black advisors actively utilized practices and approaches designed to dismantle institutional barriers and reduce the likelihood of attrition of students from HMRBs. Finally, an institutional colorblind agenda enabled White advisors to utilize colorblind practices, causing Black advisors to feel caught between acting in ways aligned with institutional policies and expectations and the needs of students from HMRBs. These findings have significant implications for the professional development, training, and growth of academic advisors and the advising profession as a whole
Synthesis of 4-tert-butylpyridine from DHP and 4-cyanopyridine utilizing photo mediated redox processes
No full textThe generation of tertiary radicals via photo-mediated redox processes represents a significant advancement in the introduction of sp³ hybridized carbons, which are crucial in pharmaceutical research. Traditional methods for generating tertiary alkyl radicals often rely on an exogenous photocatalyst, which are typically precious-metal complexes, and current photocatalyst- free approaches often involve hazardous reagents and complex procedures, posing safety and reproducibility challenges. Inspired by our lab’s prior work, we present a safer and more efficient photocatalyst- free approach by utilizing 4-tert-alkyl-1,4-dihydropyridine (DHP) derivatives as tertiary radical precursors under visible light irradiation for sp³-sp² C-C coupling reactions
Assessing spatial accessibility of maternal healthcare in Cape Coast, Ghana
No full textGhana has seen encouraging improvements in reducing infant and maternal mortality rates over the past decades, but it remains a challenging issue. This is as a result of several factors, including transportation and socioeconomic factors, which affect maternal healthcare access, and eventually affect the healthcare outcomes. A clear understanding of the spatial accessibility patterns of healthcare services can help policymakers identify potential problems and make wise decisions to improve maternal healthcare in an area. In this study, we examined the spatial variability in access to maternal healthcare services across the Cape Coast Metropolitan area in Ghana. Incorporating transportation conditions and socioeconomic factors in our analysis, we implemented an augmented two-step floating catchment area (A2SFCA) method to investigate the spatial accessibility to maternal healthcare facilities in Cape Coast. The method uses different catchment area sizes to reflect the resource capacity of healthcare facilities and applies varying network-based distances to capture the reality that people may have different transportation modes available to them when visiting facilities due to their socioeconomic status. Accessibility analysis results reveal significant disparities in maternal healthcare access between population clusters of different socioeconomic status in the Cape Coast Metropolitan area. High socioeconomic areas enjoy better access to maternal healthcare, while low socioeconomic groups, especially those living at the peripheries, experience poor or no access. Consequently, these underserved areas have been identified as problematic areas for potential interventions. To enhance access to maternal healthcare, three potential solutions were proposed and evaluated: (1) adding one large hospital, (2) improving transport conditions, and (3) implementing small multiple healthcare facilities known as the Community-Based Health Planning and Services (CHPS) in Ghana. Evaluation results suggest the third potential solution as the most effective, ensuring that almost all communities in the region have access to maternal healthcare services. The study provides useful findings that will help assist healthcare policymakers, planners, and the government in improving maternal access across the region