UNT Theses and Dissertations - 93 Matching Results

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3D Printed Self-Activated Carbon Electrodes for Supercapacitor Applications

Description: This study investigated a new approach to achieving high energy density supercapacitors (SCs) by using high surface area self-activated carbon from waste coffee grounds (WCGs) and modifying 3D printed electrodes' porous structure by varying infill density. The derived activated carbons' surface area, pore size, and pore volume were controlled by thermally treating the WCGs at different temperatures (1000˚C, 1100˚C, and 1200˚C) and post-treating with HCL to remove water-soluble ashes and contami… more
Date: July 2023
Creator: Disi, Onome Aghogho
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

3D Printing of Zinc Anode for Zinc Ion Batteries

Description: Recently, 3D printing has received increasing attention for the fabrication and assembly of electrodes for batteries due to the freedom of creating structures in any shape or size, porosity, flexibility, stretchability, and chemistry. Particularly, zinc ion batteries (ZIBs) are favored due to high safety, cheap materials cost, and high volumetric capacity (5,849 mAh/cm3), however, rapid evaporation of Zn due to low melting temperature has limited its 3D printability via conventional laser-based… more
Date: December 2021
Creator: Amoko, Stephen Adot Oyo
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

Description: Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer M… more
Date: May 2016
Creator: Wu, Min
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Aerodynamic Optimization of a 2D Airfoil for Rotary-Wing Aircraft at Mars Atmospheric Conditions

Description: The interest toward Mars exploration has been considerably increasing due to also the successful deployment of the Perseverance rover and the continuous tests developed by SpaceX's launch vehicle, Starship. While the Mars 2020 mission is currently in progress, the first controlled flight on another planet have been proven in April 2021 with the vertical take-off and landing of the Ingenuity rotorcraft on Mars. In addition, the rotorcraft Dragonfly is expected to achieve the same endeavor in Tit… more
Date: December 2021
Creator: Saez, Aleandro G.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Analysis of Heat Transfer Enhancement in Channel Flow through Flow-Induced Vibration

Description: In this research, an elastic cylinder that utilized vortex-induced vibration (VIV) was applied to improve convective heat transfer rates by disrupting the thermal boundary layer. Rigid and elastic cylinders were placed across a fluid channel. Vortex shedding around the cylinder led to the periodic vibration of the cylinder. As a result, the flow-structure interaction (FSI) increased the disruption of the thermal boundary layer, and therefore, improved the mixing process at the boundary. This … more
Date: December 2017
Creator: Kota, Siva Kumar k
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Analysis of Sources Affecting Ambient Particulate Matter in Brownsville, Texas

Description: Texas is the second largest state in U.S.A. based on geographical area, population and the economy. It is home to several large coastal urban areas with major industries and infrastructure supporting the fossil-fuel based energy sector. Most of the major cities on the state have been impacted by significant air pollution events over the past decade. Studies conducted in the southern coastal region of TX have identified long range transport as a major contributor of particulate matter (PM) pol… more
Date: May 2012
Creator: Diaz Poueriet, Pablo
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Analyze and Rebuild an Apparatus to Gauge Evaporative Cooling Effectiveness of Micro-Porous Barriers.

Description: The sample used for evaporative cooling system is Fabric defender 750 with Shelltite finish. From the experimental data and equations we have diffusion coefficient of 20.9 ± 3.71 x 10-6 m2/s for fabric with one layer with 17%-20% fluctuations from the theory, 27.8 ± 4.5 x 10-6 m2/s for fabric with two layers with 6%-14% fluctuations from the theory and 24.9 ± 4.1 x 10-6 m2/s for fabric with three layers with 13%-16% fluctuations from the theory. Since the thickness of the fabric increases so… more
Date: December 2008
Creator: Mohiti Asli, Ali
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Application of High Entropy Alloys in Stent Implants

Description: High entropy alloys (HEAs) are alloys with five or more principal elements. Due to these distinct concept of alloying, the HEA exhibits unique and superior properties. The outstanding properties of HEA includes higher strength/hardness, superior wear resistance, high temperature stability, higher fatigue life, good corrosion and oxidation resistance. Such characteristics of HEA has been significant interest leading to researches on these emerging field. Even though many works are done to unders… more
Date: May 2017
Creator: Alagarsamy, Karthik
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Artificial Neural Network Based Thermal Conductivity Prediction of Propylene Glycol Solutions with Real Time Heat Propagation Approach

Description: Machine learning is fast growing field as it can be applied to solve a large amount of problems. One large subsection of machine learning are artificial neural networks (ANN), these work on pattern recognition and can be trained with data sets of known solutions. The objective of this thesis is to discuss the creation of an ANN capable of classifying differences in propylene glycol concentrations, up to 10%. Utilizing a micro pipette thermal sensor (MTS) it is possible to measure the heat propa… more
Date: August 2022
Creator: Jarrett, Andrew Caleb
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Bioinspired & biocompatible coatings of poly(butylene adipate-co-terephthalate) and layer double hydroxide composites for corrosion resistance

Description: Hierarchical arrangement of biological composites such as nacre and bone containing high filler (ceramic) content results in high strength and toughness of the natural material. In this study we mimic the design of layered bone microstructure and fabricate an optimal multifunctional bio-nanocomposite having strength, toughness and corrosion resistance. Poly (butylene adipate-co-terephthalate) (PBAT), a biodegradable polymer was used as a substrate material with the reinforcement of LDH (Layered… more
Date: May 2016
Creator: Rizvi, Hussain R.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

CFD Study of Ship Hydrodynamics in Calm Water with Shear Current and in Designed Wave Trails

Description: Although the capability of computational fluid dynamics (CFD) in modeling ship hydrodynamics is well explored in many studies, they still have two main limitations. First, those studies ignore the effect of non-uniform shear current which exists in realistic situation. Second, the focus of most studies was laid more on the seakeeping/maneuvering performance and less attention was paid to survivability of ships due to extreme ship response events in waves, which are considered rare events but i… more
Date: May 2022
Creator: Phan, Khang Minh
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Characterization of Viscoelastic Properties of a Material Used for an Additive Manufacturing Method

Description: Recent development of additive manufacturing technologies has led to lack of information on the base materials being used. A need arises to know the mechanical behaviors of these base materials so that it can be linked with macroscopic mechanical behaviors of 3D network structures manufactured from the 3D printer. The main objectives of my research are to characterize properties of a material for an additive manufacturing method (commonly referred to as 3D printing). Also, to model viscoelasti… more
Date: December 2013
Creator: Iqbal, Shaheer
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Conceptual Framework for the Development of an Air Quality Monitoring Station in Denton, Texas

Description: Denton, Texas consistently reaches ozone nonattainment levels. This has led to a large focus of air pollution monitoring efforts in the region, with long-range transport being explored as a key contributor. For this study, the University of North Texas Discovery Park campus was chosen as a prospective location for an extensive air quality monitoring station. Sixteen years of ozone and meteorological data for five state-run monitoring sites within a 25 mile radius, including the nearest Denton A… more
Date: August 2016
Creator: Boling, Robyn
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Deleterious Synergistic Effects of Concurrent Magnetic Field and Superparamagnetic (Fe3O4) Nanoparticle Exposures on CHO-K1 Cell Line

Description: While many investigations have been performed to establish a better understanding of the effects that magnetic fields and nanoparticles have on cells, the fundamental mechanisms behind the interactions are still yet unknown, and investigations on concurrent exposure are quite limited in scope. This study was therefore established to investigate the biological impact of concurrent exposure to magnetic nanoparticles and extremely-low frequency magnetic fields using an in-vitro CHO-K1 cell line mo… more
Date: May 2015
Creator: Coker, Zachary
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Denim Fiberboard Fabricated from MUF and pMDI Hybrid Resin System

Description: In this study, a series of denim fiberboards are fabricated using two different resins, malamine urea formaldehyde (MUF) and polymeric methylene diphenyl diisocyanate (pMDI). Two experimental design factors (1) adhesive content and (2) MUF-pMDI weight ratio, were studied. All the denim fiberboard samples were fabricated following the same resin blending, cold-press and hot-press procedures. The physical and mechanical tests were conducted on the fiberboard following the procedures described in … more
Date: May 2019
Creator: Cui, Zhiying
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Design, Fabrication and Testing of a Novel Dual-Axis Automatic Solar Tracker System Using a Fresnel-Lens Solar Concentrator

Description: This thesis project investigates, analyzes, designs, simulates, constructs and tests a dual-axis solar tracker system to track the sun and concentrates the heat of the sunlight, using a Fresnel lens, into a small area, which is above of an evaporator, to increase the temperature of the seawater to convert it into freshwater. The dual-axis solar tracker was designed with the main objectives that the structure was portable, dismountable, lightweight, low cost, corrosion resistant, wires inside pi… more
Date: August 2021
Creator: Almara, Laura Mabel
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Design of a Lower Extremity Exoskeleton to Increase Knee ROM during Valgus Bracing for Osteoarthritic Gait

Description: Knee osteoarthritis (KOA) is the primary cause of chronic immobility in populations over the age of 65. It is a joint degenerative disease in which the articular cartilage in the knee joint wears down over time, leading to symptoms of pain, instability, joint stiffness, and misalignment of the lower extremities. Without intervention, these symptoms gradually worsen over time, decreasing the overall knee range of motion (ROM) and ability to walk. Current clinical interventions include offloading… more
Date: May 2017
Creator: Cao, Jennifer M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Development of a Cost Effective Wireless Sensor System for Indoor Air Quality Monitoring Applications

Description: Poor air quality can greatly affect the public health. Research studies indicate that indoor air can be more polluted than the outdoor air. An indoor air quality monitoring system will help to create an awareness of the quality of air inside which will eventually help in improving it. The objective of this research is to develop a low cost wireless sensor system for indoor air quality monitoring. The major cost reduction of the system is achieved by using low priced sensors. Interface circuits … more
Date: May 2014
Creator: Abraham, Sherin
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Development of a Natural Fiber Mat Plywood Composite

Description: Natural fibers like kenaf, hemp, flax and sisal fiber are becoming alternatives to conventional petroleum fibers for many applications. One such applications is the use of Non-woven bio-fiber mats in the automobile and construction industries. Non-woven hemp fiber mats were used to manufacture plywood in order to optimize the plywood structure. Hemp fiber mats possess strong mechanical properties that comparable to synthetic fibers which include tensile strength and tensile modulus. This study … more
Date: August 2017
Creator: Anthireddy, Prasanna Kumar
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Development of an Enclosed Evaporation Chamber Utilizing a Fresnel Lens Solar Concentrator

Description: This thesis project investigates the configuration of an enclosed evaporation chamber with the intention of converting seawater into potable freshwater. The evaporation chamber's sole heat source is provided by a Fresnel lens, located above the chamber, which concentrates sunlight onto a 3-inch diameter focal plate built into the core of the chamber. The design of the evaporation chamber is modeled after a solar still and is coupled with a heat exchanger to boost efficiency of the system. The c… more
Date: August 2022
Creator: Planz, Bridger T
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Dissimilar Friction Stir Welding Between Magnesium and Aluminum Alloys

Description: Joining two dissimilar metals, specifically Mg and Al alloys, using conventional welding techniques is extraordinarily challenging. Even when these alloys are able to be joined, the weld is littered with defects such as cracks, cavities, and wormholes. The focus of this project was to use friction stir welding to create a defect-free joint between Al 2139 and Mg WE43. The stir tool used in this project, made of H13 tool steel, is of fixed design. The design included an 11 mm scrolled and concav… more
Date: December 2016
Creator: Reese, Gregory A
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Dissimilar Joining of Al (AA2139) – Mg (WE43) Alloys Using Friction Stir Welding

Description: This research demonstrates the use of friction stir welding (FSW) to join dissimilar (Al-Mg) metal alloys. The main challenges in joining different, dissimilar metal alloys is the formation of brittle intermetallic compounds (IMCs) in the stir zone affecting mechanical properties of joint significantly. In this present study, FSW joining process is used to join aluminum alloy AA2139 and magnesium alloy WE43. The 9.5 mm thick plates of AA2139 and WE43 were friction stir butt welded. Different pr… more
Date: December 2016
Creator: Poudel, Amir
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Effect of Dispersed Particles and Branching on the Performance of a Medium Temperature Thermal Energy Storage System

Description: The main objective of my thesis is to develop a numerical model for small-scale thermal energy storage system and to see the effect of dispersing nano-particles and using fractal-like branching heat exchanger in phase change material for our proposed thermal energy storage system. The associated research problems investigated for phase change material (PCM) are the low thermal conductivity and low rate of heat transfer from heat transfer fluid to PCM in thermal energy storage system. In this st… more
Date: August 2013
Creator: Hasib, A. M. M. Golam
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Effect of Surface Treatment on the Performance of CARALL, Carbon Fiber Reinforced Aluminum Dissimilar Material Joints

Description: Fiber-metal laminates (FML) are the advanced materials that are developed to improve the high performance of lightweight structures that are rapidly becoming a superior substitute for metal structures. The reasons behind their emerging usage are the mechanical properties without a compromise in weight other than the traditional metals. The bond remains a concern. This thesis reviews the effect of pre-treatments, say heat, P2 etch and laser treatments on the substrate which modifies the surface … more
Date: August 2017
Creator: Bandi, Raghava
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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