Digital Commons Network^™

Fabrication Of Solar Absorber Tube With Internal Fin Structure With In718 And Effect Of Boron With In718 For Solar Absorber Tube Using Selective Laser Melting 3d Printing Technology, Naznin Nuria Afrin

Theses and Dissertations

This research aimed to fabricate Solar Absorber Tubes for Solar-Thermal Power Plant with internal fin structures using Selective Laser Melting (SLM) technology. In this study, we investigated the effect of B with IN718 in 3D printing using SLM for solar absorber tubes. The objective was to study the material-process-properties relationship with goal to identify and validate the optimal parameters for the SLM process. Material selected for this study was IN718 with 0.5% and 1% B particle mixed using a V-shape mixing machine. The flowability test was conducted using the Angle of Repose (AOR) method. 3D printed samples …

Integrating Model-Based Systems Engineering Industry Transformations For Workforce Development, Wilma Analisa Ankobiah

Theses and Dissertations

This study explores whether MBSE industry workforce requirements are being satisfied by the academic curricula of US institutions. Using an industry survey, which is highlighted in Chapter 3, identifies the existing perception of MBSE from various industries and explores the MBSE needs of professionals, such as tools concepts and languages. It examines how industry professionals perceive MBSE, the advantages and challenges of MBSE use and the preferred MBSE tools, languages and knowledge of concepts deemed necessary to ensure project success in the respective industry sectors. Results of phase 1 industry survey will summarize the current MBSE concepts, tools and languages …

The Deflection And Heat Transfer Analysis Of Injection Mold Cavity With Sla Cooling Channel Insert, Olumide Temidayo Aladesiun

Theses and Dissertations

Fast cooling in injection molding is the critical in the process economy. Among many different cooling channel designs available, conformal cooling offers the best and the most efficient cooling. However, limited awareness, accessibility, complexity, cost, knowledge, and experience limit the use of conformal cooling channels to be used into the mold in a molding process.

Typically, SLM(Selective Laser Melting) method is used to create cavity inserts with conformal cooling channels, however, due to the difficulties listed above, applications of conformal cooling channels are very limited. For an inexpensive alternative SLA (Stereolithography Apparatus) can print cavity inserts with conformal cooling channels. …

Fabrication And Characterization Of Force Spun Polymeric Nanofiber For Drug Delivery And Tissue Engineering Applications, Salahuddin Ahmed

Theses and Dissertations

This study focuses on the development and characterization of polymeric nanofiber for drug delivery and tissue engineering applications. In this study, poly(lactic-co-glycolic) acid (PLGA), Poly-vinyl alcohol (PVA), and Pullulan(PL) were used as the base polymers to develop the nanofiber. Bioactive components Oleanolic acid(OA), Oxymatrine(OM), and Salvianolic Acid(SA) were incorporated in PLGA, PVA, and PL, respectively, via solution mixing. The nano fiber systems were developed using the Forcespinning® method. Morphological, thermo-physical, and biological properties of the fiber mats were analyzed. The composite fiber system containing OA showed a very high drug loading efficiency. The composite fiber system containing high concentration of …

Arab American Muslims’ Attitudes Toward Seeking Mental Health Services: The Roles Of Acculturation, Religion, And Cultural Beliefs, Tharwah Alzoubi

Theses and Dissertations

The purpose of this study was to identify the relationship between acculturation, religion, cultural beliefs, and attitudes toward seeking mental health services among Arab American Muslims. A total of 280 participants were surveyed for this study. Regression analysis was conducted to explore relationships among the variables; the alpha level was set at .05. The first research hypothesis was accepted as it showed statistical significance in the relationship between attitudes toward seeking mental health services and demographic variables. The standardized regression coefficients, or beta coefficients ranged from -.008 for gender to .24 for marital status, R=.31 (P<.05). Two variables were significant at the .05 level (marital status, and health insurance). The second hypothesis was also accepted as it showed relationship between attitudes toward mental health services and acculturation, religion and cultural beliefs; the standardized regression coefficients, or beta coefficients ranged from .05 for cultural beliefs to a -.25 for religion, R=.44 (P<.05). The variables of acculturation and religion were significant at the .01 level. Cultural beliefs were not significant at .05 level.

Dynamic Soil Properties In The Lower Rio Grande Valley: Carbon And Nitrogen Responses To Different Tillage Practices, Luzyannet Ballesteros Gonzalez

Theses and Dissertations

There has been increased attention in utilizing agriculture for carbon sequestration. Soil carbon and nitrogen are two dynamic soil properties (DSPs) that are indicators of soil health and function and have overlapping cycles. These soil properties change frequently as a result of environmental conditions and agricultural management practices. This study focuses on the impact of tillage practices in unirrigated agricultural fields in Hidalgo and Willacy counties located in South Texas on Hidalgo Sandy Clay Loam; With a particular focus on Soil Total Carbon (TC), Soil Inorganic Carbon (SIC), Permanganate Oxidizable Carbon (POXC), Carbon and Nitrogen ratio (C:N), Soil Organic Matter …

Ultrafast Laser Direct Writing Of Conductive Patterns On Modified Polyimide Film For Flexible Electronic Applications, Ishrat Jahan Biswas

Theses and Dissertations

Conductive patterns can be printed on a flexible polymer substrate using the direct laser writing (DLW) method. In order to write conductive circuits in such polymer using a laser, polyimide (PI) is a desirable material choice due to its electrical, chemical, and mechanical properties. Electrically non-conductive PI has shown great potential for flexible printed electronics as LDW enables selective carbonization in the bulk of such material leading to the formation of conductive lines. The technique is shown to be a rapid and minimal cost method for printing electrodes to nanoscale devices. However, investigations in this field show several limitations to …

Dynamic Soil Properties In The Lower Rio Grande Valley: Understanding Responses Of Infiltration Rate, Bulk Density, Aggregate Stability To Different Tillage Practices, Temiloluwa Faith Awotoye

Theses and Dissertations

Dynamic Soil Properties (DSPs) are soil properties that change in response to both natural and human-caused interruptions and pressures such as agro-based and wildland management. These soil properties can transform for months or even years in response to the farm use and management procedures. This research project investigates the relationship between different dynamic soil physical properties and tillage practices in the Texas Hidalgo sandy clay loam benchmark soil series. Data analyses was done to compare the effect of tillage to these soil physical properties and build a discussion about relationships between on-farm practices to other aspects of farm viability. We …

A Study Of The Surface Properties Of Additive Manufactured Inconel 718 After Laser Surface Treatment And Cnc Grinding, Sampson K. Canacoo

Theses and Dissertations

This study investigated the surface properties of additive manufactured Inconel 718 produced through selective laser melting, and the effects of laser ablation and CNC grinding on the surface finish. The objectives were to investigate the effects of the various parameters of laser ablation and CNC grinding on the Inconel 718 surface. The parameters used for the laser experiments were pulse energy (4, 20, and 30 µJ), scanning speed (5, 10, and 15 mm/s), and hatch distance (10, 30, and 50 µm). For the grinding experiments, the wheel speed was kept constant at 20.3 m/sec, however, two different workpiece speed (8.6 …

The Molecular Evolution Of Insect Opsin Genes, Maria Jose Cardenas Muedano

Theses and Dissertations

Opsins are part of the superfamily of G-coupled receptor proteins and together with chromophores, are responsible for initiating the signal transduction cascade responsible for animal vision. Since opsins have a critical role on visual perception these genes are crucial for a myriad of adaptive traits and behaviors and should show diverse signs of natural selection at the molecular level. Understanding the evolution of opsins across the wide diversity of insect groups will allow us to better understand the evolutionary pressure on insect opsins and serve as a model for both other gene systems and other taxonomic groups of animals that …

Conjunctive Management For Groundwater-Surface Water Resources: Numerical Modeling And Potential Assessment Of Managed Aquifer Recharge (Mar) At Lower Rio Grande Valley In South Texas, Dwight Zedric Q. Capus

Theses and Dissertations

Texas is well known to frequent floods and droughts, and yet has mounting concerns in very imbalanced water availability and water demands from growth in population and economical activities. Capturing and storing water is essential to long-term and climate-smart management of the “already-scarce” water resources. This study aimed to apply numerical modeling to evaluate potentials and impacts of Managed Aquifer Recharge (MAR) to regional groundwater systems in the Lower Rio Grande Valley. Using Visual MODFLOW Flex 3D package, different scenarios were simulated for groundwater flow patterns and storage capacities. Water injections tested ranged between 7.30x105 ft3 to 3.65x109 ft3 , …

A Numerical Simulation Of The Powder Bed Additive Manufacturing Process With Molecular Dynamics Simulation, Yeasir Mohammad Akib

Theses and Dissertations

Many manufacturing industries utilize powder bed fusion (PBF) since it can produce microscale precision 3D parts. During PBF, powder particles are selectively fused layer by layer using thermal energy. The build quality in the PBF process relies heavily on powder bed properties and thermal energy deposition. Powder flowability, spreadability, and packing fraction are some of the insightful factors that determine the quality of the powder bed. In this study, a two-dimensional powder bed is developed using the LAMMPS package. A cloud-based pouring of powders with varying volumes and initialization is adopted for the work. A blade-type and circular recoater is …

Recuerdos De Mi Niñez, Noel Barsenas

Theses and Dissertations

This thesis contains an original work for orchestra that features programmatic elements and musical gestures referencing previous generations of composers as well as other influential relatives of the author that are then recombined into a personal style. The document also contains commentary about the piece’s personal, historic, and cultural contexts, as well as a theoretical analysis addressing the form, structure, and harmonic content of the work.

Ambient Air-Processed Cspbi3-Based Perovskite Solar Cell Via Semi-Sputtering Deposition And Numerical Studies Of Cs3sb2i9-Based Perovskite Solar Cell, Shamik Datta

Theses and Dissertations

Commercialization of Perovskite solar cells as a clean energy source can augment the reduction of carbon footprint. CsPbI3, a well-known perovskite material, has been synthesized in ambient air and high-humidity conditions and utilized as the active layer in a perovskite solar cell. The rest of the solar cell layers have been sputter-deposited. This solar cell with a p-i-n configuration ITO/NiOx/CsPbI3/ZnO/Au exhibited a champion efficiency of 3.7%. Nonetheless, lead incorporation in the conventional Pb-cation-based perovskites poses an environmental threat. The physical proximity of living organisms to lead point sources exhibits a wide spectrum of negative consequences. In this study, we have …

My Journey As An Elementary Science Teacher: From Linear To Authentic, Johanna Lynn Esparza

Theses and Dissertations

The purpose of this dissertation is to provide a personalized narrative of one science teacher’s use of reflexive teaching as an agent of change. This dissertation is about a journey of change in instruction fostered by a change of identity as a science teacher, using the butterfly cycle as a metaphor. This dissertation narrates the identity evolution of the teacher. This study has relevance because the process utilized by the teacher provides a method of self-examination and identity construction for other elementary science classroom teachers who want to improve their science practices. This study also has relevance because it describes …

Salas Y Gómez Benthic Habitat And Community Assessment Of Seamounts And Oceanic Islands, Kara Eckley

Theses and Dissertations

Seamounts are essential benthic habitats that are ecologically important, providing habitat and functioning as stepping stones for dispersal and possible refugia, and economically valuable, supporting deep-sea fisheries and potential mineral mining activities. The Salas y Gómez Ridge in the southeast Pacific Ocean longitudinally contains dozens of seamounts that extend ~2,900 km across the South Pacific Subtropical Gyre. The ridge contains a range of oxygen and nutrient conditions that, along with the distance between seamounts, have led to high levels of endemism, reported in the few studies that have been conducted on seamounts of the region; this study is the first …

Search For Gravitational Waves From Core Collapse Supernovae In Ligo's Observation Runs Using A Network Of Detectors, Shahrear Khan Faisal

Theses and Dissertations

Core-Collapse Supernova (CCSN) is one of the most anticipated sources of Gravitational Waves (GW) in the fourth observation run (O4) of LIGO and other network of GW detectors. A very low rate of galactic CCSN, coupled with the fact that the CCSN waveforms are unmodeled, make detection of these signals extremely challenging. Mukherjee et. al. have developed a new burst search pipeline, the Multi-Layer Signal Enhancement with cWB and CNN or MuLaSEcC, that integrates a non-parametric signal estimation and Machine Learning. MuLaSEcC operates on GW data from a network of detectors and enhances the detection probability while reducing the false …

Monsters & Men, Christopher Ernest Garcia

Theses and Dissertations

Monsters & Men is a collection of poetry and illustrations that explores the complex emotions associated with masculinity, grief, and personal development. I achieve this by heavily reflecting on my relationship with my late father and using this medium as an outlet to express my trauma in a healthy manner. How we perceive ourselves as men, and what is possible, is not reflected enough in society and I aim to be a proponent in stimulating the conversation revolving around men’s mental health. Men and the patriarchy impose themselves on others to the point where we need to address the unethical …

Green Synthesis Of Spiro Compounds And The Phytochemical Investigation Of Diethyl Ether Fraction Of Camu-Camu (Myrciaria Dubia) Leaves, Judith Anane

Theses and Dissertations

There are a lot of lucrative plant species found in the Amazon and camu-camu (Myrciaria dubia (H.B.K.) Mc Vaugh) is distinct among them. This is due to its exceptional Vitamin C content which varies from 1600 to 6112 mg/100g of pulp. Besides the fruits which is popularly used, different parts of camu-camu plants including the stems, leaves, seeds, barks, and roots are also traditionally used in folklore practices for treating various ailments and diseases and research has showed the presence of antioxidant, antimicrobial, anticancer, anti-inflammatory agents present in these parts. In this study, the characterization of a bioactive compound, …

Glitch Estimation And Removal Using Adaptive Spline Fitting And Wavelet Shrinkage On The Gravitational Wave Data, Mohammad Abu Thaher Chowdhury

Theses and Dissertations

The false alarm rate and reduced sensitivity of searches for astrophysical signals are caused by transient signals of earthly origin, or "glitches," in gravitational wave strain data from groundbased detectors. The greater number of observable astrophysical signals will increase the likelihood of glitch overlaps and exacerbate their negative impact for future detectors with higher sensitivities. The wide morphological diversity and unpredictable waveforms of glitches, and with the vast majority of cases lacking supplemental data present the main obstacles to their mitigation. Thus, nonparametric glitch mitigation techniques are required, which should operate for a wide range of glitches and, in the …

The Mediating Role Of Gun Attitudes In The Association Between Dsm-5 Posttraumatic Stress Disorder Symptom Clusters, And Gun Ownership In Young Hispanic Adults With Exposure To Interpersonal Trauma, Vanessa Gonzalez

Theses and Dissertations

Despite growing interest in gun attitudes and gun ownership among United States citizens, the current body of literature is limited and tends to focus on white non-Hispanic individuals. The present study examined the effect of interpersonal trauma-related PTSD symptoms on gun attitudes and protective gun ownership. The associations between experiencing PTSD symptoms, gun attitudes, and protective gun ownership were examined in a sample of 176 young Hispanic adults (n = 127 women, n = 49 men) with exposure to interpersonal trauma. Specifically, the mediating role of positive attitudes towards guns in the associations between the four clusters of DSM-5 …

South Texas Wildlife Activity Across A Fragmented Landscape And Road Mitigation Corridor, Caitlin K. Brett

Theses and Dissertations

Wildlife crossing structures (WCS) and roadside fencing are commonly installed to mitigate habitat fragmentation, wildlife road mortalities, and other negative effects that roads can have on the surrounding landscape. Eight such WCS were constructed below Farm-to-Market (FM)106 in Cameron County, Texas, across a 16 km corridor transecting the Laguna Atascosa National Wildlife Refuge. These WCS, paired with adjacent roadside fencing, were intended to prevent road mortalities of the endangered ocelot (Leopardus pardalis) and to mitigate the barrier effect of FM106 on this and other meso-mammal species. This study will analyze camera trap data from roadside and habitat reference …

Dismembering Monstrous Metaphors In Latinx Speculative Fiction, Danielle Garcia-Karr

Theses and Dissertations

U.S. public discourse and popular media are rife with monstrous metaphors of Latinxs. This thesis argues that these gothic monstrous metaphors construct an affective economy of fear, which results in material violence and the devastation of Latinx lives. I further argue that to intervene within this affective economy, Latinx authors write speculative fiction, employing critical race methodologies, to negotiate monstrosity in relation to citizenship. In other words, speculative Latinx authors disidentify with monsters and enact epistemic disobedience, problematizing the known and naturalized and delinking Latinx people from monstrous metaphors to interrupt cycles of fear and violence. In exploring this metaphoric …

Safety-Aware Longitudinal And Lateral Control Of Autonomous Vehicles, Randy Guadalupe Chapa

Theses and Dissertations

Safety is undoubtedly the most critical design requirement regarding autonomous vehicle controllers. This research considers an autonomous vehicle to keep a desired distance from the leader vehicle, as well as stay centered within the lane. To achieve this, the lateral control problem and the combined longitudinal and lateral control problem were studied. Adaptive control laws were proposed with the aid of the backstepping technique and the barrier function technique. Simulation was done to verify the effectiveness of the proposed control laws.

Healthcare In A Time Of Crisis: An Investigation Of The Association Between Socioeconomic Status, Counties, And Covid-19, Jorge F. Contreras

Theses and Dissertations

The COVID-19 pandemic has stressed social structural institutions such as hospitals, schools, the economy, and governmental bodies (local, state, and federal), exacerbating existing health inequality. Fundamental Cause Theory (FCT) provides a framework for understanding which factors drive such inequality, but its primary focus is on within-group variation. By highlighting the role of fundamental causes as systems of exposure, the Systems-of-Exposure (SOE) approach expands on FCT to account for variation more directly between populations. I performed a Qualitative Comparative Analysis (QCA) of county-level data from Texas and California to test the utility of SOE in assessing the impact of a pandemic …

The Impact Of Supervisory Training And Workload Upon The Licensed Specialist In School Psychology Supervisors’ Perception Providing Field-Based Supervision To Interns In A Public-School Setting, Christopher L. King

Theses and Dissertations

Quality supervision is essential for developing high-performing professionals in the mental health profession. Licensed Specialists in School Psychology (LSSP) in Texas can begin supervising LSSP Interns after three years of unsupervised field experience. Workloads for LSSP supervisors can be highly diverse, and LSSP supervision training can be limited. The present study explored the impact of workload and lack of supervision training on the supervisors’ perceived ability to supervise Licensed Specialist in School Psychology (LSSP) interns in Texas public school settings. Using a quantitative cross-sectional survey design, 146 LSSP supervisors with at least three years of unsupervised field experience, and one …

Investigation Of Process Parameters To Fabricate Refractory Medium-Entropy Alloy By Selective Laser Melting Process, Abdullah Al Masum Jabir

Theses and Dissertations

This thesis proposal investigates the synthesis of TiWMo refractory medium entropy alloy (RMEA) by selective laser melting process from elemental powder. Steel, titanium and tungsten substrates were used to study the impact on the formation of TiWMo RMEA. Different process parameters were applied to investigate the effects on melting, diffusion and formation of RMEA. The microstructure of TiWMo and elemental distribution were observed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). SEM analysis revealed that with higher energy density the pores and microcracks were improved. EDS data validated the composition is homogenized and stable after few layers …

Liminal Beings Are We, John Kenneth Froozan Ii

Theses and Dissertations

This thesis establishes a foundation for liminality in political theory. Liminality, a concept mostly developed in anthropology, is used by them to describe middle periods in rites of passage. Unlike the anthropologists, I argue that liminality should be theorized phenomenologically. Utilizing the history of political philosophy, liminality is defined as a dialectical phenomenon that acts between and beyond the limits of things, Self, and Other. I describe liminality as an ontological-epistemological or existential condition that acts as a connecting tissue to both define what is and the space between things. This requires that notions of power, politics, and their ends …

Emotion Identification Ability And Perspective-Taking In Children With Autism Spectrum Disorder, Ana Lucia Garrido Huerta

Theses and Dissertations

Autism spectrum disorder (ASD) is characterized by persistent deficits in social interaction. Perspective-taking and emotion identification are important skills to develop appropriate social interactions. Previous research has shown that children with ASD may lack the ability to relate emotionally to others. Research has also shown a deficit in perspective-taking skills in children with ASD. The selected studies reviewed in this thesis analyze seven articles that show research on children with ASD regarding their emotional identification and perspective-taking skills. Articles searched under the words “emotion identification,” “perspective-taking,” and “autism” obtained from the Psychology and Behavioral Sciences Collection using the EBSCO database …

Development Of Vegetable Oil-Based Nano-Lubricants Using Ag, H-Bn And Mgo Nanoparticles As Lubricant Additives, Kollol Sarker Jogesh

Theses and Dissertations

Because of the harmful impact of petroleum-based lubricant on the environment and human body, vegetable oil-based lubricant with eco-friendly nanoparticles has a great potential to be an alternative lubricant if it possesses proper lubricating properties. In this study, thermal conductivity, viscosity and tribological properties (wear scar diameter and coefficient of friction) of vegetable oil-based nanolubricant, developed from soybean oil and sunflower oil, modified with Ag, h-BN and MgO nanoparticles as lubricant additives, were evaluated. For thermal conductivity evaluation, a line heat source method was used with KD2 Pro-Thermal Property Analyzer. For viscosity evaluation, Haake Mars 40-rheometer was used to evaluate …