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Systems approach to the remote operation of a hydraulic fracturing missile
No full textHydraulic fracturing missiles are a critical piece of equipment in the hydraulic fracturing process. If there is a failure, people have to enter a high-risk area to shut off pressurized lines. Entering the high-pressure zone exposes the field personnel to unnecessary risk. Eliminating the need to have a person in the line of fire through the remotely operated system in these high-risk zones is the motivation for this Thesis.
A complete system for actuating the valves on a hydraulic fracturing missile was created by applying system engineering. The system was designed by following the System Engineering Vee Model. The system was decomposed and iterated throughout the system definition and realization phases of the System Engineering Vee Model.
The system was realized up to a prototype stage. A combination of inspection, analysis, testing, and demonstrations was conducted on the prototype to verify the requirements of the system that were established in the requirements list. The interface requirements were validated, and a plan of what needs to be validated and how was also defined. The validation of the system will primarily need to occur during field testing
The Impact of School and District Fiscal Decisions and Demographic Characteristics on Oklahoma Elementary School Principal Turnover
Get PDFThis study is a quantitative, causal comparative study exploring the effect that various
school-level and district-level fiscal decisions and demographic characteristics have on
elementary principal turnover within Oklahoma public schools. This study was distinguished by
its methods and context in the form of a replication study of Maiden, Crowson, and Byerly
(2020). The population in the study is 987 elementary schools, which are nested within 524
public school districts. The initial analysis used hierarchical linear modeling and binary logistical
regression to measure the relationship between the study predictive variables and principal
turnover. Due to an oversimplification of the dependent variable, a follow-up analysis was
conducted using multinomial logistic regression with an increased precision of the dependent
variable. This study was cross-sectional and conducted analysis from the 2021-2022 school/fiscal
years. The results indicated a significant relationship with principal turnover and the district
percentage of principal turnover. The study results also indicated increased rates of turnover
within schools that employ multi-site and/or multi-principals and increased rates of turnover in
rural schools, especially when the rural school employs a multi-site or multi-role principal. There
were also conclusions of increased rates of lateral turnover in nonrural schools, increased rates of
retention in schools with the highest and lowest concentration of students considered
economically disadvantaged, and the follow-up analysis yielded a significant relationship
between school-level administrative per-pupil expenditures and turnover among schools with
principals who left for promotions
Identifying Preferred Neighborhood Attributes Among Individuals 50 Years and Older, and Analyzing Their Access to the Physical Environment: A Case Study on Age Friendliness of Norman, Oklahoma
Get PDFThe number of people aged 65-and-older has been growing worldwide and in the United States. The needs of these aging individuals will affect the communities in which they live. Faced with this drastic shift in the older adults population, the idea of aging in place was proposed by the World Health Organization (WHO) to focus on making the older adults’ homes and communities safe by tailoring them to their well-being and needs. By aging in place, older individuals can remain in communities for as long as possible while keeping their autonomy and social connections.
The concept of aging-in-place has been studied thoroughly in different fields like gerontology, social policy, and public health. By integrating a planning perspective on this interdisciplinary research topic, this dissertation focuses on the neighborhood preferences of individuals aged 50 or older in Norman, Oklahoma as well as their access to age friendly amenities through conducting a survey and spatial analysis. Successful aging in communities is not possible without access to reliable transportation, health services, recreational opportunities, physical and social support systems, and a wide variety of amenities. However, this study’s findings demonstrate that currently there is a gap between what individuals 50 years and above need to age in their neighborhoods and the current built environment attributes. Understanding this gap and the challenges these individuals face to age in their communities could help planners and designers develop policy and design recommendations to improve age friendliness of neighborhoods.
Keywords: Age friendliness, Aging in Place, Residential Location Choice, Built Environment Attributes, Spatial Analysis, Older Adults, Middle Aged Adult
A simulation and analytical study on the performance of gas-liquid centrifugal downhole separators
Get PDFA common issue in depleted oil and gas wells is the lack of energy to drive the fluids to the surface. Engineers use various artificial lift systems to solve this problem, most commonly by using pumps. Many pump types do not perform at their maximum capacity when working in the presence of gas. To address this problem, downhole separators can be used. This study seeks to understand the dynamics of the fluid flow inside one of the common types of such separators, static downhole centrifugal type. The study compiles an extensive literature review of gas-liquid centrifugal separation.
Data are collected from the literature review to feed a machine learning model and predict the equipment’s efficiency. A total of 272 data points are extracted from the literature. These data are used to perform dimensional analysis and obtain dimensionless numbers to feed five machine learning algorithms: linear regression, random forest, K-nearest neighbor, support vector machine, and voting. The data are used to determine the best model in predicting separation efficiency. The voting algorithm is the best predictor for this dataset. It has a cross-validated adjusted R2 of 0.535 and RMSE of 0.138 on the set. This means that the predictor can represent 53.5% of the variance in gas separation efficiency data with an error of 13.8%.
Single-phase and multiphase study cases are run of the fluid domain of a static centrifugal separator using ANSYS Fluent 2023. Realizable k-epsilon turbulence and multiphase Eulerian models are used for the conducted simulations with pressure and mass-flow rate boundary conditions. Pressure, velocity, and volume fraction contours, and outlet velocity profiles are analyzed for each case.
From the single-phase cases, it is observed that the velocity of the fluids increases about five times in the outermost section of the helix-type path of the separator. In all the cases, the fluids leave the domain through the top outlet, which has the biggest cross-sectional area. Eddies or vortexes are formed in certain cornering sections of the equipment. Future re-designs can be performed to minimize these eddies. Additionally, eddies in the separator's upper section are caused by the high velocity at which the fluids are expelled from the helical section to the annulus.
The gas-liquid flow was studied inside the helix-type paths through the multiphase study cases. The totality of the liquid was expelled through the bottom outlet. Furthermore, from these cases, it was verified the importance of having a higher pressure at the bottom outlet for the correct convergence of the study cases. Through analysis of the velocity profiles in the outlets, it can be seen how the air tends to leave the domain through the top outlet, while the water through the bottom outlet. It was observed that pressure control influences the separator performance, when the bottom outlet pressure is set as 1500 Pa higher than the top outlet pressure, the water leaving the domain through the bottom outlet is 98.3% and the air leaving through the top outlet is 85%
Working together: School administrators supporting teachers of students with behavioral challenges
Get PDFSpecial educators who teach students with significant or challenging behaviors may experience physical aggression, verbal aggression, the destruction of classroom or personal property, or the elopement of a student. Student behaviors such as these can lead to physical and mental exhaustion and stress in teachers. School leadership needs to know what special educators of students with significant behaviors report as supportive to decrease injury and burnout, to promote educator retention and ultimately student success. This study defines the types of supports provided by school principals that special education teachers in Oklahoma report to be helpful in these difficult situations. This quantitative survey research project used a pragmatic and non-experimental design to describe special education teachers’ perceived support by a principal with the reported desired support types. In previous studies by Littrell, Billingsley, and Cross (1994) the findings of special education teachers' perceived supports were similar to House’s 1981 social supports study, where teachers rated emotional, appraisal, informational, and instrumental supports as important. In this study, the sample was obtained by asking special education directors of Oklahoma public school districts to distribute the survey to teachers in their school district who teach students with challenging behavior. The survey inquired about specific challenging behaviors including elopement, physically aggressive behavior, property destruction, and verbally aggressive behavior. Teachers rated all areas of support as important, with emotional support identified as the most important form of support. Principals can help special education teachers experience greater confidence and skill by providing emotional, appraisal, informational, and instrumental support. With intentional and focused support, principals can influence the work of teachers of students with behavior challenges and be instrumental in supporting teachers through successful behavior interventions and increased academic achievement of students with behavioral challenges (Tschannen-Moran & Gareis, 2015)
“I feel like everyone has anxiety when it comes to math”: an exploration of stereotype threat and anxiety for first-year mathematics students in higher education
No full textUnderstanding of the relationship between anxiety and stereotype threat for students in first-year mathematics courses offers improvement for theoretical, methodological, and classroom practices surrounding the experiences of these constructs. This dissertation aimed to address the poor understanding of this relationship. Using a mixed methods participatory social-justice design (QUANT – QUAL), students’ performance, anxiety, and stereotype threat data were analyzed through a Control-Value Theory (CVT) and Situated Expectancy-Value Theory (SEVT) lens. Design and analysis were also considered through the Quantitative Critical Race Theory (QuantCrit) methodological lens. This study showed that gender-, sexuality, and income-based stereotype threat positively predicted achievement anxiety, while race-based stereotype threat nearly did so. Additionally, students’ anxiety did not predict their performance on the day data was collected, but their most recent math assessment score in their math course negatively predicted achievement anxiety during data collection. Some students identified connections of their emotions, identity, abilities, and changes during the assessment as additional information they wanted researchers to know. These results corroborate some research showing a correlation between achievement anxiety and stereotype threat and extend upon and challenge many previous studies which were not situated in real mathematics classrooms. Recommendations for classroom instructors include providing empowering help to students, providing threat nullification interventions without attempting to control students, and voting in elections to ensure that appropriate interventions remain options for educators. Challenges to future researchers include developing a situative component for CVT, reforming survey measures for stereotype threat, and increasing the use of open-response identity questions and other QuantCrit methodological considerations
A New Front-End System For UAV-Based Antenna Measurements For Polarimetric Weather Radars
Get PDFRadar system calibration is vital for ensuring optimal performance, especially in weather radars that have stringent requirements for co-polarization mismatch. In-field calibration is essential, particularly for mobile weather radars, as environmental conditions can vary between deployments. Traditionally, conventional far-field ranges or airborne systems such as helicopters and aircraft have been used to measure and calibrate radar systems. However, in recent years, Unmanned Aerial Systems (UAS) have emerged as a cost-effective and flexible alternative for antenna measurement and radar calibration.
Previous studies have demonstrated the feasibility of using UAS for far-field antenna measurements across various operating frequencies. These works have achieved high accuracy in characterizing and calibrating polarimetric weather radar systems, meeting critical requirements such as co-polarization mismatch below 0.1 dB and cross-polarization isolation below -45 dB. However, existing UAS-based systems are complex to operate, requiring multiple equipment both on the UAS and the ground station. They are primarily limited to one-way transmission from the UAS to the AUT and lack the capability to switch between RX and TX measurements or H- and V-polarization without physical modifications.
The objective of this thesis is to develop a lightweight and self-contained front-end system for UAS-based in-situ antenna characterization. This system will eliminate the need for additional RF instruments on the ground, providing remote real-time control to switch between RX and TX modes in both V- and H-polarization. It will also facilitate the transmission and reception of measurement data over long distances, enabling far-field measurements beyond 120 m.
The proposed system aims to address the limitations of existing UAS-based calibration systems, offering a sophisticated and accurate solution for measuring the strictest radar systems. By developing a versatile and lightweight front-end system, this research seeks to advance the field of UAS-based antenna characterization and contribute to the improvement of radar calibration techniques
Determination of SHmax using drilling induced fractures and focal mechanism
Get PDFKnowledge of in-situ stress is essential to well development technologies such as wellbore stability, hydraulic fracturing, well spacing design, and the monitoring of induced seismicity. As energy exploration has become more prevalent in unconventional reservoirs and as it has shifted focus to sustainable energy such as geothermal energy, the knowledge of in situ stresses plays a crucial role in the success of energy production. In this project, the in-situ stress S_Hmax in the geothermal reservoir of Utah FORGE is computed and analyzed using multiple stress analysis methodologies in both vertical and horizontal wells.
In a stress analysis, the understanding of three principal stresses is needed and they are vertical stress (S_v), minimum horizontal principal stress (S_hmin), and maximum horizontal principal stress (S_Hmax). In general, S_v is calculated by integrating the density log over the depth, while S_hmin is determined by hydraulic fracturing-based tests such as DFIT, leak-off test, and micro frac test. The direction of S_hmin and S_Hmax can be interpreted from the azimuth of drilling induced fractures and/or borehole breakouts. However, the determination of the magnitude of maximum horizontal principal stress (S_Hmax) is challenging especially in an inclined wellbore. Traditionally, S_Hmax can be estimated using hydraulic fracturing data and the Kirsch solution. However, this method of using hydraulic fracturing data imposes uncertainties as it is sensitive to the models and the assumption to rock formation is too sample (Schmitt and Zoback, 1989; Zi et al., 2022). With the gaining use of image log tools such as FMI and UBI, the method of using borehole failures such as breakouts and drilling induced fractures gives rise to more access to assess in situ stresses (Zoback, et al., 2003). Thus, the need of integrating multiple stress analysis methods and the incorporation of drilling induced fractures and breakouts around the wellbore is required to constrain a more comprehensive S_Hmax magnitude estimation.
In this paper, we present the wellbore in-situ stress models of the vertical and deviated wells in Utah FORGE based on the drilling-induced fractures and breakouts observed from borehole image logs. We also applied an in-situ stress inversion program based on focal mechanism and validated the program using the data from the Geyser geothermal reservoirs. This program can be used for the Utah FORGE reservoir once its focal mechanism data is available.
In Utah FOREG, we integrated multiple methods such as fracture mechanics, and wellbore failure analysis with the incorporation of drilling-induced fractures, borehole breakouts, and thermal stresses to constrain the wellbore stress model and input parameters. The validated wellbore in-situ stress models and parameters were then applied to establish the in-situ stress profiles of wells. The stress results in all wells yield a range of S_Hmax of 0.80 – 1.05 psi/ft, suggesting a normal faulting regime in Utah FORGE. The orientation of S_Hmax has a range of N20E to N40E with a mean of N33E based on drilling induced fractures in vertical wells.
In Geyser, an in-situ stress inversion program based on the focal mechanism has been applied and validated. The stress variation analysis confirmed that the Geyser reservoir has a mixture of normal and strike-slip fault regimes sandwiched by strike-slip fault regimes on the top and bottom of the reservoir. The Geyser injection test also was shown to alter the stress regimes of the reservoir and cause the stress regime to transit from strike slip to normal and to transtensional fault during a cycle of injection activities
Essays In Finance
No full textIn my dissertation, I exhibit three studies in Finance. In Chapter 1, I provide a new perspective on the optimal call policy for corporate callable bonds by evaluating the proportion called in call exercises. My data suggests that firms on average call only 66% of the amount initially offered when they call their bonds with fixed-price call provisions, and 69% when they call their bonds with make-whole call provisions. I examine how the proportion called in a call exercise is correlated with bond and firm characteristics. In Chapter 2, I analyze the impact of the maturity of a firm’s bonds upon the liquidity of the firm’s remaining bonds. The results suggest that a reduction in the number of bonds outstanding leads a reduction in liquidity. In Chapter 3, I characterize the presence and consequences of sustainability compensation targets using novel hand-collected data of managerial annual incentive plans (AIP) goals in 1994-2020. The data indicates that sustainability targets are often quantified with corresponding overall weight in the incentive plan instead of rarely observed sustainability modifiers. Moreover, sustainability compensation goals are valuable if implemented in firms with high past pollution levels, exclusively, consistent with optimal contracting
