Experimental Study On The Fabrication Of Advanced Materials For Energy Applications Using High Energy Mechanical Milling,
2013
University of Texas at El Paso
Experimental Study On The Fabrication Of Advanced Materials For Energy Applications Using High Energy Mechanical Milling, Ashvin Kumar Narayana Swamy
Open Access Theses & Dissertations
The reaction of aluminum (Al) powder with water has the potential for on demand hydrogen generation. Conventional Al powders, however, react with water slowly due to a highly protective oxide layer on the particle surface. Current methods for Al activation involve harmful and expensive materials. The nano-scale Al powders also remain very expensive and have problems such as a large amount of oxide on the surface. The use of aluminum in an energy generation cycle is also hindered by the fact that, although Al is the most abundant metal in the Earth's crust, its recovery from ore consumes a lot …
Effect Of Hafnium-Incorporation On The Microstructure And Dielectric Properties Of Cobalt Ferrite Ceramics,
2013
University of Texas at El Paso
Effect Of Hafnium-Incorporation On The Microstructure And Dielectric Properties Of Cobalt Ferrite Ceramics, Stephen Josiah Wells
Open Access Theses & Dissertations
The effect of hafnium ion (Hf4+) incorporation in cobalt ferrite (CFO) was studied. Samples of Hf substituted CFO ceramic (CoFe2-xHfxO4), were synthesized in the laboratory with hafnium concentrations ranging from x=0.000 to x=0.200. X-ray diffraction scans show that the Hafnium CFO crystalizes in the inverse spinel phase. Inclusion of hafnium causes lattice expansion, increasing the lattice parameter from 8.374 í? for pure CoFe2O4 to 8.391 í? for the highest concentration of hafnium tested (x=0.020). The dielectric properties of CFO are greatly enhanced by inclusion of hafnium. The enhancement is due to the …
Thermal Barrier Coatings (Tbc's) For High Heat Flux Thrust Chambers,
2013
University of Texas at El Paso
Thermal Barrier Coatings (Tbc's) For High Heat Flux Thrust Chambers, Christopher Michael Bradley
Open Access Theses & Dissertations
The last 30 years materials engineers have been under continual pressure to develop materials with a greater temperature potential or to produce configurations that can be effectively cooled or otherwise protected at elevated temperature conditions. Turbines and thrust chambers produce some of the harshest service conditions for materials which lead to the challenges engineers face in order to increase the efficiencies of current technologies due to the energy crisis that the world is facing. The key tasks for the future of gas turbines are to increase overall efficiencies to meet energy demands of a growing world population and reduce the …
Microstructure And Properties For Titanium Aluminide Superalloy Prototypes Fabricated By Electron Beam Melting And Thermally Processed,
2013
University of Texas at El Paso
Microstructure And Properties For Titanium Aluminide Superalloy Prototypes Fabricated By Electron Beam Melting And Thermally Processed, Jennifer Hernandez
Open Access Theses & Dissertations
Gamma TiAl has been considered to be an ideal replacement for Ni-base superalloy aerospace applications, particularly in weight-critical applications. While bulk, fully dense gamma-TiAl is 50% less dense than Ni-base superalloys, it also has excellent mechanical properties at high temperature (up to ~800°C). Pre alloyed (Ti-48Al-2Cr-2Nb) powder was used to fabricate solid, fully dense (3.85 g/cm3) components and foam components with densities ranging from 0.33 g/cm3 to 0.46 g/cm3 by electron beam melting (EBM). A 10:1 blend of 2-phase TiAl (Ti-48Al-2Cr-2Nb in a/o) : Inconel 625 (Ni-22Cr-6Mo-2Nb in a/o) pre-alloyed powders produced …
New Topics On Nanoindentation Of Polymers And Composite Materials,
2013
University of Texas at El Paso
New Topics On Nanoindentation Of Polymers And Composite Materials, Ricardo Martinez-Hernandez
Open Access Theses & Dissertations
In this study, nanoindentation was used to determine Young's modulus of homogeneous plastic materials as well as inhomogeneous epoxy woven fabric composites using various indenters. In the first part, homogeneous PMMA and polycarbonate were characterized using conical and spherical indenters. The conventional approach of the inverse analysis was modified in order to account for effects obtained during spherical nanoindentation. The experimental results were verified using FEA analysis in ABAQUS. It was found that viscous effects were present in conical nanoindentations which led to an overestimation of contact stiffness. The second part, the response of carbon and glass fiber woven fabric …
Rbd2po4: Room Temprature Synthesis, Chemical And Structural Stablity Upon Heating,
2013
University of Texas at El Paso
Rbd2po4: Room Temprature Synthesis, Chemical And Structural Stablity Upon Heating, Masoud Mollaee
Open Access Theses & Dissertations
Monoclinic RbD2PO4 polycrystals were synthesized via the room temperature crystallization of RbH2PO4 dissolved in D2O. Powder x-ray diffraction (XRD) data collected at T=25 ºC indicate that this deuterated compound crystallizes in space group P21/m with unit cell parameters a=7.688í?, b=6.192í?, c=4.781í? and β=109.02°, and is isomorphic with the intermediate-temperature phase of its hydrogenated counterpart rubidium dihydrogen phosphate (RDP). We found no evidence of previously reported [Phase Transitions 80, 17 (2007)] polymorphic phase transition in rubidium dideuterium phosphate (DRDP) upon heating from room temperature to 210 ºC. All lattice parameters vary smoothly within this temperature range, demonstrating that the P21/m phase …
Carbon-Based Nanostructured Materials As Electrode In Lithium-Ion Batteries And Supercapacitors,
2013
Wright State University
Carbon-Based Nanostructured Materials As Electrode In Lithium-Ion Batteries And Supercapacitors, Zhuo Yao
Browse all Theses and Dissertations
Carbon-based nancomposites attract much attention as electrode materials in electrochemical energy storage systems due to their low-cost, extraordinary high electrical and thermal conductivity, super high surface area etc. In this research, graphene nanosheets (GNS) and their nanocomposites with manganese oxides (GNS/MnOx) or silicon nanowires (GNS/SiNWs/CF) are studied for their applications in Li-ion batteries and supercapacitors. GNS powders are synthesized via a chemical oxidation of nature graphite followed by appropriate reduction process. GNS/MnOx composites are synthesized rendering MnOx nanoparticles embedded on the surfaces of GNS. SiNWs grown in carbon fibers are mechanically mixed with GNS powders. The impacts of the manganese …
Active Optimal Control Strategies For Increasing The Efficiency Of Photovoltaic Cells,
2013
Univesrity of Kentucky
Active Optimal Control Strategies For Increasing The Efficiency Of Photovoltaic Cells, Sharif Aljoaba
Theses and Dissertations--Electrical and Computer Engineering
Energy consumption has increased drastically during the last century. Currently, the worldwide energy consumption is about 17.4 TW and is predicted to reach 25 TW by 2035. Solar energy has emerged as one of the potential renewable energy sources. Since its first physical recognition in 1887 by Adams and Day till nowadays, research in solar energy is continuously developing. This has lead to many achievements and milestones that introduced it as one of the most reliable and sustainable energy sources. Recently, the International Energy Agency declared that solar energy is predicted to be one of the major electricity production energy …
Solution-Processed Nanoparticle
Super-Float-Gated Organic Field-Effect
Transistor As Un-Cooled Ultraviolet And
Infrared Photon Counter,
2013
University of Nebraska-Lincoln
Solution-Processed Nanoparticle Super-Float-Gated Organic Field-Effect Transistor As Un-Cooled Ultraviolet And Infrared Photon Counter, Yongbo Yuan, Qingfeng Dong, Bin Yang, Fawen Guo, Qi Zhang, Ming Han, Jinsong Huang
Department of Mechanical and Materials Engineering: Faculty Publications
High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The photon-generated charges on the floating gate cause high resistance regions in the transistor channel and tune the source-drain output current. This ‘‘super-float-gating’’ mechanism enables very high sensitivity photodetectors with a minimum detectable ultraviolet light intensity of 2.6 photons/µm2s at room temperature as well …
Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators,
2013
University of Nebraska-Lincoln
Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators, Huijing He, Guo-Quan Nie, Jin-Xi Liu, Jiashi Yang
Department of Mechanical and Materials Engineering: Faculty Publications
We study the electrically forced thickness-shear and thickness-twist vibrations of stepped thickness piezoelectric plate mesa resonators made of polarized ceramics or 6-mm class crystals. A theoretical analysis based on the theory of piezoelectricity is performed, and an analytical solution is obtained using the trigonometric series. The electrical admittance, resonant frequencies, and mode shapes are calculated, and strong energy trapping of the modes is observed. Their dependence on the geometric parameters of the resonator is also examined.
Review Of Electrochemical And Electrodischarge Machining,
2013
University of Nebraska-Lincoln
Review Of Electrochemical And Electrodischarge Machining, Kamlakar P. Rajurkar, M. M. Sundaram, A. P. Malshe
Department of Mechanical and Materials Engineering: Faculty Publications
Electrochemical and electro-discharge machining processes are the two major electro-machining processes with unique capabilities. Electrical Discharge Machining (EDM) and Electrochemical Machining (ECM) offer a better alternative or sometimes the only alternative in generating accurate 3-D complex shaped macro, micro and nano features and components of difficult–to-machine materials. Technological advances reported in electrochemical and electro discharge machining processes, which reflect the state of the art in academic and industrial research and applications, are briefly reviewed in this paper.
Wire Electro-Discharge Machining Of Titanium Alloy,
2013
University of Nebraska-Lincoln
Wire Electro-Discharge Machining Of Titanium Alloy, Farnaz Nourbakhsh, Kamlakar P. Rajurkar, Ajay P. Malshe, Jian Cao
Department of Mechanical and Materials Engineering: Faculty Publications
This paper presents an experimental investigation of wire electro-discharge machining (WEDM) of titanium alloy. The objective is to investigate the effect of seven process parameters including pulse width, servo reference voltage, pulse current, and wire tension on process performance parameters (such as cutting speed, wire rupture and surface integrity). A Taguchi L18 design of experiment (DOE) has been applied. All experiments have been conducted using Charmilles WEDM. It was also found that the cutting speed increases with peak current and pulse interval. Surface roughness was found to increase with pulse width and decrease with pulse interval. The Analysis of Variance …
Selective Detection And Automated Counting Of Fluorescently-Labeled Chrysotile Asbestos Using A Dual-Mode High-Throughput Microscopy (Dm-Htm) Method,
2013
Kookmin University
Selective Detection And Automated Counting Of Fluorescently-Labeled Chrysotile Asbestos Using A Dual-Mode High-Throughput Microscopy (Dm-Htm) Method, Myoung-Ock Cho, Hyo Mi Chang, Donghee Lee, Yeon Gyu Yu, Hwataik Han, Jung Kyung Kim
Department of Mechanical and Materials Engineering: Faculty Publications
Phase contrast microscopy (PCM) is a widely used analytical method for airborne asbestos, but it is unable to distinguish asbestos from non-asbestos fibers and requires time-consuming and laborious manual counting of fibers. Previously, we developed a high-throughput microscopy (HTM) method that could greatly reduce human intervention and analysis time through automated image acquisition and counting of fibers. In this study, we designed a dual-mode HTM (DM-HTM) device for the combined reflection and fluorescence imaging of asbestos, and automated a series of built-in image processing commands of ImageJ software to test its capabilities. We used DksA, a chrysotile-adhesive protein, for selective …
Photovoltaic Device,
2013
Lincoln, NE
Photovoltaic Device, Jinsong Huang, Bin Yang, Yongbo Yuan
Department of Mechanical and Materials Engineering: Faculty Publications
An apparatus includes a substrate; and a photoactive layer disposed on the substrate. The photoactive layer includes an electron acceptor material; an electron donor material; and a material having dipoles.
Elastic–Plastic Analysis And Strength Evaluation Of Adhesive
Joints In Wind Turbine Blades,
2013
University of Nebraska–Lincoln
Elastic–Plastic Analysis And Strength Evaluation Of Adhesive Joints In Wind Turbine Blades, Yi Hua, Ananth Ram Mahanth Kasavajhala, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
The objective of this paper is to investigate the performance of adhesive joints of carbon/epoxy wind turbine blade subjected to combined bending and tension loadings through finite element method. The influence of adhesive material properties and geometrical details including fillet and imperfections was examined in terms of interlaminar stresses in the adhesive layer. The variation of stress intensity with change in adhesive shear modulus has also been investigated, while contour integral method was used for evaluating the stress intensity factors (SIF) at the imperfection tip. Furthermore, the strength of the joint was assessed through the crack initiation and propagation analysis. …
Scaling Of The Coercive Field In Ferroelectrics At The Nanoscale,
2013
Institute of Crystallography, Russian Academy of Science, Moscow
Scaling Of The Coercive Field In Ferroelectrics At The Nanoscale, R. V. Gaynutdinov, M. Minnekaev, S. Mitko, A. L. Tolstikhina, A. Zenkevich, Stephen Ducharme, Vladimir M. Fridkin
Stephen Ducharme Publications
The scaling of the coercive field in ferroelectric films at the nanoscale is investigated experimentally. The scaling in the films of copolymer vinylidene fluoride and BaTiO3 with thickness equal by the order of value to the critical domain nucleus size 1–10 nm reveals deviation from the well-known Kay–Dunn law. At this thickness region coercive field does not depend on thickness and coincides with Landau–Ginzburg–Devonshire value.
Experiments To Measure The Effects Of Timber Harvesting Equipment On Surface Lithic Scatters,
2013
Central Washington University
Experiments To Measure The Effects Of Timber Harvesting Equipment On Surface Lithic Scatters, Douglas J. Baughman
All Master's Theses
The importance of cultural resource preservation cannot be overstated; however local economies are at least as important. Due to conservative archaeological site protection practices in Region 5 of the United States Forest Service, the economy of Northeastern California is being adversely affected. In an attempt to help the Forest Service make more informed management decisions and improve the Northeastern California economy, I undertook experiments on the effects of timber harvesting on lithic scatters on Modoc National Forest. The experiments involved placement of 225 glass tiles (proxy lithics) in each of three plots subject to vehicle traffic and log dragging by …
Impedance Changes In Biceps Brachii Due To Isometric Contractions And Muscle Fatigue Using Electrical Impedance Myography (Eim),
2013
Georgia Southern University
Impedance Changes In Biceps Brachii Due To Isometric Contractions And Muscle Fatigue Using Electrical Impedance Myography (Eim), Travis Orth
College of Graduate Studies: Theses & Dissertations
Electrical impedance myography (EIM) is a non-invasive technique used to evaluate neuromuscular conditions by using a quantitative parameter called impedance (Z). It relies upon the application and measurement of high-frequency, low-intensity electrical current imbedded over a localized muscle to determine its opposition to current flow. In brevity, impedance determines the resistance of muscle fibers due to changes in muscle composition. The objective of this thesis was to establish a relationship between muscles at rest and during isometric contractions at various force levels(25%, 50%, and 100% of maximum voluntary contraction) of the biceps brachii over a multifrequency spectrum. Impedance measurements due …
Quantification Of The Environmental Impact Of Titanium Dioxide Photocatalytic Pavements For Air Pollution Remediation,
2013
Louisiana State University and Agricultural and Mechanical College
Quantification Of The Environmental Impact Of Titanium Dioxide Photocatalytic Pavements For Air Pollution Remediation, Heather Lee Dylla
LSU Doctoral Dissertations
Photocatalytic concrete pavements are a promising technology for mobile source air pollution remediation, however before widespread application of this technology is realized many unanswered questions remain regarding its overall environmental impact. In response to these questions, the goal of this study was to increase the understanding of the environmental impact of photocatalytic concrete pavement highways. To achieve this goal, the objectives of this study were to (A) construct a model that evaluates the nitrogen oxides (NOx) reduction from photocatalytic pavements, (B) quantify the nitrates released from the photocatalytic degradation of NOx, and (C) identify and characterize pathways for TiO2 nanoparticle …
Silver Nanoparticles As Drug Delivery Systems,
2013
Louisiana State University and Agricultural and Mechanical College
Silver Nanoparticles As Drug Delivery Systems, Ammar Tahseen Qureshi
LSU Doctoral Dissertations
The goal of this project is to study the potential applications of silver nanoparticles (SNPs) in the medical device and pharmaceutical industries. Bone cements have been used in the orthopedic surgeries for many years to anchor prosthetics while filling up the spaces between the prostheses and bone. Antibiotics are an active component of bone cements but the increasing bacterial resistance to these antibiotics and difficulty of shaping and molding the bone cements increases the need for new antimicrobial biomaterials. Adult stem cell based regenerative therapies have been one of the most widely researched areas of tissue engineering. This is due …
