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Simulation Study of Tremor Suppression and Experiment of Energy Harvesting with Piezoelectric Materials

Description: The objective of this research is to develop a wearable device that could harvest waste mechanical energy of the human hand movement and utilize this energy to suppress wrist tremors. Piezoelectric material is used to measure the hand movement signals, and the signal of wrist tremor is filtered to be utilized to suppress the tremor. In order to conduct the experiment of energy harvesting and tremor suppression, an experimental rig was fabricated. Two types of piezoelectric materials, PVDF (poly… more
Date: August 2012
Creator: Ou, Jianqiang
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Electrodepostion of Iron Oxide on Steel Fiber for Improved Pullout Strength in Concrete

Description: Fiber-reinforced concrete (FRC) is nowadays extensively used in civil engineering throughout the world due to the composites of FRC can improve the toughness, flexural strength, tensile strength, and impact strength as well as the failure mode of the concrete. It is an easy crazed material compared to others materials in civil engineering. Concrete, like glass, is brittle, and hence has a low tensile strength and shear capacity. At present, there are different materials that have been employed … more
Date: August 2014
Creator: Liu, Chuangwei
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Optimization of Silica Nanocomposite Membranes for Air Dehumidification

Description: This thesis is focused on understanding the correct method to simulate atomistic models to calculate coefficient of diffusion of water through the membrane. It also aims to fix the method previously used in molecular modelling in which the simulation results did not match the experimental results. These membranes will be used in air dehumidification systems. The four types of membranes namely, polyurethane, polyurethane with silica nano particles, polyurethane with silica nano particles and ami… more
Date: May 2022
Creator: Appaji, Tejas
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Electromagnetic Shielding Properties of Iron Oxide Impregnated Kenaf Bast Fiberboard

Description: The electromagnetic shielding effectiveness of kenaf bast fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted to remove the lignin and extractives from the pores in fibers, and then magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed… more
Date: December 2014
Creator: Ding, Zhiguang
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Laminar Natural Convection From Isothermal Vertical Cylinders

Description: Laminar natural convection heat transfer from the vertical surface of a cylinder is a classical subject, which has been studied extensively. Furthermore, this subject has generated some recent interest in the literature. In the present investigation, numerical experiments were performed to determine average Nusselt numbers for isothermal vertical cylinders (103 < RaL < 109, 0.5 < L/D <10, and Pr = 0.7) with and without an adiabatic top in a quiescent ambient environment which will allow for plu… more
Date: August 2012
Creator: Day, Jerod
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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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
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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Optimization of Superhydrophobic Surfaces to Maintain Continuous Dropwise Condensation

Description: In the past decade, the condensation on superhydrophobic surfaces has been investigated abundantly to achieve dropwise condensation. There is not a specific approach in choosing the size of the roughness of the superhydrophobic surfaces and it was mostly selected arbitrarily to investigate the behavior of condensates on these surfaces. In this research, we are optimizing the size of the roughness of the superhydrophobic surface in order to achieve dropwise condensation. By minimizing the resist… more
Date: May 2014
Creator: Vandadi, Aref
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Experimental and Numerical Investigation of a Novel Cold-Formed Steel Long Span Truss

Description: This thesis describes the experimental and numerical investigation of a novel cold-formed steel 48ft and 54ft long span truss. The truss we designed was to be used as the roofs of large buildings, such as warehouses, hangars, sports arenas. The investigation includes both experimental and numerical testing, the experimental testing of the truss under uniform loads (increasing loads) to determine its deflection and load carrying capacity. The numerical test included developing a finite element m… more
Date: December 2023
Creator: Nalla, Sai Kumar
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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Suppression of Higher Acoustic Harmonics by Application of Solid-Solid Periodic Layered Structure in Nonlinear Ultrasonics Nondestructive Evaluation Field

Description: Nondestructive testing (NDT) using ultrasound band 1-5 MHz, has been widely used for the early-stage detection of structural failure; however, it fails to detectf material degradation, fatigue, and microcracks. NDT with nonlinear ultrasound (NLU) can detect a microscopic discontinuity or imperfection that may be a source of the second harmonic in the reflected signal. In this research, we focus on creating a metamaterial band filter that filters out nonlinearities induced by the instrument itse… more
Date: May 2023
Creator: Kang, Jinho
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Loading Mode Dependent Effective Properties of Octet-truss Lattice Structures Using 3D-Printing

Description: Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, … more
Date: May 2015
Creator: Challapalli, Adithya
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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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
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Ultrafast Laser Sampling of a Plant Tissue and ion Conductivity Measurement for Investigation of Light Stress Generation Mechanisms

Description: In this study we applied ultra-short laser pulses on a biological sample (Arabidopsis), in order to cut it precisely in a square pattern and subsequently use it for studying stress generation mechanisms. For this purpose, we utilized femtosecond laser pulses at 100 fs pulse width and 80 MHz repetition rate. We took two processing parameters into consideration such as laser power, laser exposure time which is related to the stage speed. Therefore, we were able to find the laser optimum condition… more
Date: August 2010
Creator: Abtahi, Seyed Ali
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Study of Comprehensive Reinforcement Mechanism of Hexagonal Boron Nitride on Concrete

Description: The addition of hexagonal boron nitride (h-BN) has introduced a comprehensive reinforcing effect to the mechanical and electrochemical properties of commercial concrete, including fiber reinforced concrete (FRC) and steel fiber reinforced concrete (SFRC). Although this has been proven effective and applicable, further investigation and study is still required to optimize the strengthen result which will involve the exfoliation of h-BN into single-layered nano sheet, improving the degree of disp… more
Date: August 2015
Creator: He, Qinyue
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Gradient-Index Metamaterial Infrared Detector for Enhanced Photo-Response and Image Quality

Description: An enhanced thermal imaging concept made possible through the development of a gradient-indexed metamaterial infrared detector that offers broadband transmission and reflection in THz waves. This thesis proposes a proof of feasibility for a metamaterial infrared detector containing an anti-reflective coating with various geometrically varying periodic metasurfaces, a gradient-indexed dielectric multilayer for near-perfect longpass filtering, and a gradient index of refraction (GRIN) metalens fo… more
Date: May 2022
Creator: Adams, Kelsa Derek
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Heat Transfer Analysis of a Small Thermochemical Reactor for Hydrogen Production from Ammonia

Description: Several types of research are ongoing throughout the world, to discover economical and reliable techniques to create hydrogen, and propagate the vision of a hydrogen economy. This research examines a COMSOL Multiphysics 5.4 heat transfer model for a hydrogen production system consisting of a retort with two different heat sources, namely a heat tape and an infrared (IR) lamp. The main objective was to compare the two heat sources and find out which one offers a better technique for producing hy… more
Date: August 2020
Creator: Owusu-Ansah, Nana
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers

Description: Electrospinning has been recognized as an efficient technique for the fabrication of polymer fibers. These electrospun fibers have many applications across a broad range of industries. In this research, optical transparent composites were successfully fabricated by embedding polyacrylonitrile (PAN) hollow nanofibers into poly (methyl methacrylate) (PMMA) matrix. The hollow PAN nanofibers were prepared by coaxial electrospinning. The PAN was used as the shell solution, and the mineral oil was us… more
Date: May 2013
Creator: Antoine, Donley
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
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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
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Investigation of an Investment Casting Method Combined with Additive Manufacturing Methods for Manufacturing Lattice Structures

Description: Cellular metals exhibit combinations of mechanical, thermal and acoustic properties that provide opportunities for various implementations and applications; light weight aerospace and automobile structures, impact and noise absorption, heat dissipation, and heat exchange. Engineered cell topologies enable one to control mechanical, thermal, and acoustic properties of the gross cell structures. A possible way to manufacture complex 3D metallic cellular solids for mass production with a relativel… more
Date: August 2013
Creator: Kodira, Ganapathy D.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Heat Transfer Analysis of Bio-Printed Tissue Mimicking Material Mixed with Silver Nanoparticles

Description: Novel tissue mimicking materials have been developed for cancer treatment research. In the present research work, the tissue mimicking material is printed using 3D bioprinting technology. The nanoparticles are homogeneously mixed with tissue mimicking materials to enhance the heating capacity. The thermal conductivity of tissue mimicking materials is measured using a micropipette thermal sensor (MTS). Further, the optimal value is identified based on optimization technique and incorporated into… more
Date: August 2022
Creator: Chandrasegaran, Jedeshkeran
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Investigation of Interfacial Property with Imperfection: A Machine Learning Approach

Description: Interfacial mechanical properties of adhesive joints are very crucial in board applications, including composites, multilayer structures, and biomedical devices. Establishing traction-separation (T-S) relations for interfacial adhesion can evaluate mechanical and structural reliability, robustness, and failure criteria. Due to the short range of interfacial adhesion such as micro to nanoscale, accurate measurements of T-S relations remain challenging. The advent of machine learning (ML) became … more
Date: July 2023
Creator: Ferdousi, Sanjida
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
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