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open access

Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement

Description: This thesis aims to develop a new type of highly stretchable strain sensor to measure large deformation of a specimen subjected to dynamic loading. The sensor was based on the piezo-resistive response of carbon nanotube(CNT)/polydimethysiloxane (PDMS) composites thin films, some nickel particles were added into the sensor composite to improve the sensor performance. The piezo-resistive response of CNT composite gives high frequency response in strain measurement, while the ultra-soft PDMS matri… more
Date: May 2016
Creator: Yao, Shulong
Partner: UNT Libraries
open access

Biomass-Derived Activated Carbon Through Self-Activation Process

Description: Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up… more
Date: May 2016
Creator: Xia, Changlei
Partner: UNT Libraries
open access

A study of the impact of unconventional sources within a large urban area: evidence from spatio-temporal assessment of volatile organic compounds.

Description: Conventional sources of emissions have been a prime target for policymakers in designing pollution control strategies. However, the evolution of shale gas activities is a growing concern over the impact of unconventional sources on urban and regional air quality. Owing to the development of Barnett Shale production, the fast-growing Dallas-Fort Worth (DFW) metroplex has encountered both types of these emissions. Oil and gas activities result in emissions of ozone precursors, notably volatile or… more
Date: May 2016
Creator: Matin, Maleeha
Partner: UNT Libraries
open access

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.
Partner: UNT Libraries
open access

Investigation of the Effect of Particle Size and Particle Loading on Thermal Conductivity and Dielectric Strength of Thermoset Polymers

Description: Semiconductor die attach materials for high voltage, high reliability analog devices require high thermal conductivity and retention of dielectric strength. A comparative study of effective thermal conductivity and dielectric strength of selected thermoset/ceramic composites was conducted to determine the effect of ceramic particle size and ceramic particle loading on thermoset polymers. The polymer chosen for this study is bismaleimide, a common aerospace material chosen for its strength and t… more
Date: May 2016
Creator: Warner, Nathaniel A.
Partner: UNT Libraries
open access

Ozone Pollution of Shale Gas Activities in North Texas

Description: The effect of shale gas activities on ground-level ozone pollution in the Dallas-Fort Worth area is studied in detail here. Ozone is a highly reactive species with harmful effects on human and environment. Shale gas development, or fracking, involves activities such as hydraulic fracturing, drilling, fluid mixing, and trucks idling that are sources of nitrogen oxides (NOX) and volatile organic compounds (VOC), two of the most important precursors of ozone. In this study two independent approach… more
Date: May 2016
Creator: Ahmadi, Mahdi
Partner: UNT Libraries
open access

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
Partner: UNT Libraries
open access

Feasibility of a New Technique to Determine Dynamic Tensile Behavior of Brittle Materials

Description: Dynamic tensile characterization of geo-materials is critical to the modeling and design of protective structures that are often made of concrete. One of the most commonly used techniques currently associated with this type of testing is performed with a Kolsky bar and is known as the spall technique. The validity of the data from the spall technique is highly debated because the necessary boundary conditions for the experiment are not satisfied. By using a technique called pulse shaping, a new… more
Date: May 2016
Creator: Dean, Andrew W.
Partner: UNT Libraries
open access

Field Validation of Zero Energy Lab Water-to-Water Ground Coupled Heat Pump Model

Description: Heat pumps are a vital part of each building for their role in keeping the space conditioned for the occupant. This study focuses on developing a model for the ground-source heat pump at the Zero Energy lab at the University of North Texas, and finding the minimum data required for generating the model. The literature includes many models with different approaches to determine the performance of the heat pump. Each method has its pros and cons. In this research the equation-fit method was used … more
Date: May 2016
Creator: Abdulameer, Saif
Partner: UNT Libraries
open access

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
Partner: UNT Libraries
open access

Feasibility Study of Consolidation by Direct Compaction and Friction Stir Processing of Commercially Pure Titanium Powder

Description: Commercially pure titanium can take up to six months to successfully manufacture a six-inch in diameter ingot in which can be shipped to be melted and shaped into other useful components. The applications to the corrosion-resistant, light weight, strong metal are endless, yet so is the manufacturing processing time. At a cost of around $80 per pound of certain grades of titanium powder, the everyday consumer cannot afford to use titanium in the many ways it is beneficial simply because the numb… more
Date: August 2016
Creator: Nichols, Leannah Marie
Partner: UNT Libraries
open access

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
Partner: UNT Libraries
open access

Modeling of Fracture Toughness of Magnesium Alloy WE43 Before and After Friction Stir Processing

Description: Magnesium alloys are a popular research topic for structural applications because they have a lower density than conventional structural materials, including steel, titanium, and aluminum; however, the reliability and safety of their mechanical properties must be further proven. An important mechanical property for this purpose is fracture toughness, which is the measure of the material's resistance to crack propagation. In this study, a model of an experiment to investigate the fracture toughn… more
Date: December 2016
Creator: Lipscomb, Celena Andrea
Partner: UNT Libraries
open access

Particle Image Velocimetry Sensitivity Analysis Using Automatic Differentiation

Description: A particle image velocimetry (PIV) computer software is analyzed in this work by applying automatic differentiation on it. We create two artificial images that contained particles that where moved with a known velocity field over time. These artificial images were created with parameters that we would have on real PIV experiments. Then we applied a PIV software to find the velocity output vectors. As we mentioned before, we applied automatic differentiation through all the algorithm to track th… more
Date: December 2016
Creator: Grullon Varela, Rodolfo Antonio
Partner: UNT Libraries
open access

Quantification of Human Thermal Comfort for Residential Building's Energy Saving

Description: Providing conditioned and fully controlled room is the final goal for having a comfortable building. But on the other hand making smart controllers to provide the required cooling or heating load depending on occupants' real time feeling is necessary. This study has emphasized on finding a meaningful and steady state parameter in human body that can be interpreted as comfort criterion which can be expressed as the general occupants' sensation through their ambient temperature. There are lots of… more
Date: August 2016
Creator: Sharifani, Pooya
Partner: UNT Libraries
open access

Performance Evaluation of UNT Apogee Stadium Wind Turbines

Description: The following report chronicles the University of North Texas Wind Turbine Project at Apogee Stadium. The timeline of events will include the feasibility study conducted by and for the university, grant awards from the Texas State Energy Conservation Office to fund the project, and a three-year sample of real time performance data since installation. The purpose of this case study is to compare the energy generation estimates by various stakeholders to the measured energy generation using a new… more
Date: May 2016
Creator: McCary, William D., III
Partner: UNT Libraries
open access

Programmable Mechanical Metamaterials with Negative Poisson's Ratio and Negative Thermal Expansion

Description: Programmable matter is a material whose properties can be programmed to achieve particular shapes or mechanical properties upon command. This is an essential technique that could one day lead to morphing aircraft and ground vehicles. Metamaterials are the rationally designed artificial materials whose properties are not observed in nature. Their properties are typically controlled by geometry rather than chemical compositions. Combining metamaterials with a programmable function will create… more
Date: December 2016
Creator: Heo, Hyeonu
Partner: UNT Libraries
open access

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
Partner: UNT Libraries
open access

Enhanced Coarse-Graining for Multiscale Modeling of Elastomers

Description: One of the major goal of the researchers is to reduce energy loss including nanoscale to the structural level. For instance, around 65% of fuel energy is lost during the propulsion of the automobiles, where 11% of the loss happens at tires due to rolling friction. Out of that tire loss, 90 to 95% loss happens due to hysteresis of tire materials. This dissertation focuses on multiscale modeling techniques in order to facilitate the discovery new rubber materials. Enhanced coarse-grained models o… more
Date: December 2016
Creator: Uddin, Md Salah
Partner: UNT Libraries
open access

Modeling of Hexagonal Boron Nitride Filled Bismalemide Polymer Composites for Thermal and Electrical Properties for Electronic Packaging

Description: Due to the multi-tasking and miniaturization of electronic devices, faster heat transfer is required from the device to avoid the thermal failure. Die-attached polymer adhesives are used to bond the chips in electronic packaging. These adhesives have to hold strong mechanical, thermal, dielectric, and moisture resistant properties. As polymers are insulators, heat conductive particles are inserted in it to enhance the thermal flow with an attention that there would be no electrical conductivity… more
Date: December 2016
Creator: Uddin, Md Salah
Partner: UNT Libraries
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