Inverse Structure Functions In The Canonical Wind Turbine Array Boundary Layer,
2016
Portland State University
Inverse Structure Functions In The Canonical Wind Turbine Array Boundary Layer, Bianca Viggiano, Moira Gion, Naseem Ali, Murat Tutkun, Raúl Bayoán Cal
Mechanical and Materials Engineering Faculty Publications and Presentations
Wind tunnel measurements for a 3×3 canonical wind turbine array boundary layer are obtained using hot-wire anemometer velocity signals. Two downstream locations are considered, referring to the near- and far-wake, and 21 vertical points are acquired per profile. Velocity increments and exit distances are used to quantify inverse structure functions at both downstream locations. Inverse structure functions in the near-wake show a similar profile for the main vertical locations, but diverge as the moment is increased. In the far-wake, inverse structure functions converge toward a single function for all vertical location and moments. The scaling exponents for inverse structure functions …
High-Temperature Corrosion Testing Of Uranium Silicide Surrogates,
2016
Boise State University
High-Temperature Corrosion Testing Of Uranium Silicide Surrogates, B. J. Jaques, G. Alanko, D. P. Butt
Materials Science and Engineering Faculty Publications and Presentations
The corrosion resistance of cerium silicide, a surrogate of uranium silicide, is investigated to gain insight into the reaction of uranium silicide with water. As-received and proton-irradiated Ce3Si2, CeSi2, and CeSi1.x monolithic pellets are subjected to corrosion tests in water at 300°C and 9 MPa for up to 48 h. Results show that an oxide layer composed of Ce4.67 (SiO4)3O forms on the surface of all samples, and it grows thicker with extended exposure times. Irradiated samples corrode to a greater extent than their unirradiated counterparts, which is …
Sample Preparation Techniques For Grain Boundary Characterization Of Annealed Triso-Coated Particles,
2016
Idaho State University
Sample Preparation Techniques For Grain Boundary Characterization Of Annealed Triso-Coated Particles, M. L. Dunzik-Gougar, I. J. Van Rooyen, C. M. Hill, T. Trowbridge, J. Madden, J. Burns
Materials Science and Engineering Faculty Publications and Presentations
Crystallographic information about layers of silicon carbide (SiC) deposited by chemical vapor deposition is essential to understanding layer performance, especially when the the layers are in nonplanar geometries (e.g., spherical). Electron backscatter diffraction (EBSD) was used to analyze spherical SiC layers using a different sampling approach that applied focused ion beam (FIB) milling to avoid the negative impacts of traditional sample polishing and address the need for very small samples of irradiated materials for analysis. The mechanical and chemical grinding and polishing of sample surfaces can introduce lattice strain and result in the unequal removal of SiC and the surrounding …
Computational Fluid Dynamics Study Of Molten Steel Flow Patterns And Particle-Wall Interactions Inside A Slide-Gate Nozzle By A Hybrid Turbulent Model,
2016
Missouri University of Science and Technology
Computational Fluid Dynamics Study Of Molten Steel Flow Patterns And Particle-Wall Interactions Inside A Slide-Gate Nozzle By A Hybrid Turbulent Model, Mahdi Mohammadi-Ghaleni, Mohsen Asle Zaeem, Jeffrey D. Smith, Ronald J. O'Malley
Materials Science and Engineering Faculty Research & Creative Works
Melt flow patterns and turbulence inside a slide-gate throttled submerged entry nozzle (SEN) were studied using Detached–Eddy Simulation (DES) model, which is a combination of Reynolds–Averaged Navier–Stokes (RANS) and Large–Eddy Simulation (LES) models. The DES switching criterion between RANS and LES was investigated to closely reproduce the flow structures of low and high turbulence regions similar to RANS and LES simulations, respectively. The melt flow patterns inside the nozzle were determined by k–ε (a RANS model), LES, and DES turbulent models, and convergence studies were performed to ensure reliability of the results. Results showed that the DES model has significant …
Analysis Of Fatigue Crack Propagation In Welded Steels,
2016
Marquette University
Analysis Of Fatigue Crack Propagation In Welded Steels, Roberto Angelo Demarte
Master's Theses (2009 -)
This thesis presents the study of fatigue crack propagation in a low carbon steel (ASTM A36) and two different weld metals (AWS A5.18 and AWS A5.28). Fatigue crack propagation data for each weld wire is of interest because of its use for predicting and analyzing service failures. Fatigue crack growth test specimens were developed and fabricated for the low carbon steel base metal and for each weld wire. Weld specimens were stress relieved prior to fatigue testing. Specimens were tested on a closed-loop servo hydraulic test machine at two different load ratios. Fatigue test data was collected to characterize both …
Plasticized Polymer Coatings For Sh-Saw Sensors For High Sensitivity And Long-Term Monitoring Of Btex Analytes In Liquid Phase,
2016
Marquette University
Plasticized Polymer Coatings For Sh-Saw Sensors For High Sensitivity And Long-Term Monitoring Of Btex Analytes In Liquid Phase, Pintu Adhikari
Master's Theses (2009 -)
BTEX compounds (benzene, toluene, ethylbenzene, and xylene) are constituents of crude oil and hazardous to human health. Among them, benzene has the lowest maximum contaminant level for drinking water because of its carcinogenicity. Spills or leakage from underground storage tanks or hazardous waste sites can contaminate nearby groundwater with these volatile organic compounds. Therefore, it is very important to detect the presence of BTEX contamination as early as possible in order to start the remediation process and maintain a healthy environment. To develop an in-situ continuous monitoring sensor system, shear horizontal surface acoustic wave (SH-SAW) sensor devices are being investigated …
Effect Of Fiber Material On Ozone Removal And Carbonyl Production From Carpets,
2016
Portland State University
Effect Of Fiber Material On Ozone Removal And Carbonyl Production From Carpets, Omed A. Abbass, David J. Sailor, Elliott T. Gall
Mechanical and Materials Engineering Faculty Publications and Presentations
Indoor air quality is affected by indoor materials such as carpets that may act as sources and/or sinks of gas-phase air pollutants. Heterogeneous reactions of ozone with carpets may result in potentially harmful products. In this study, indoor residential carpets of varying fiber types were tested to evaluate their ability to remove ozone, and to assess their role in the production of carbonyls when exposed to elevated levels of ozone. Tests were conducted with six types of new unused carpets. Two sets of experiments were conducted, the first measured ozone removal and ozone deposition velocities, and the second measured primary …
Puddle Jumping: Spontaneous Ejection Of Large Liquid Droplets From Hydrophobic Surfaces During Drop Tower Tests,
2016
Portland State University
Puddle Jumping: Spontaneous Ejection Of Large Liquid Droplets From Hydrophobic Surfaces During Drop Tower Tests, Babek Attari, Mark M. Weislogel, Andrew Paul Wollman, Yongkang Chen, Trevor Snyder
Mechanical and Materials Engineering Faculty Publications and Presentations
Large droplets and puddles jump spontaneously from sufficiently hydrophobicsurfaces during routine drop tower tests. The simple low-cost passive mechanism can in turn be used as an experimental device to investigate dynamic droplet phenomena for drops up to 104 times larger than their normal terrestrial counterparts. We provide and/or confirm quick and qualitative design guides for such “drop shooters” as employed in drop tower tests including relationships to predict droplet ejection durations and velocities as functions of drop volume, surface texture, surface contour, wettability pattern, and fluid properties including contact angle. The latter is determined via profile image comparisons with numerical …
An Examination Of The Indentation Size Effect In Fcc Metals And Alloys From A Kinetics Based Perspective Using Nanoindentation,
2016
Old Dominion University
An Examination Of The Indentation Size Effect In Fcc Metals And Alloys From A Kinetics Based Perspective Using Nanoindentation, David Earl Stegall
Mechanical & Aerospace Engineering Theses & Dissertations
The indentation size effect (ISE) in metals is described as the rise in hardness with decreasing depth of indentation and contradicts conventional plasticity behavior. The goal of this dissertation is to further examine the fundamental dislocation mechanisms that may be contributing to the so-called indentation size effect. In this work, we examined several metals and alloys including 99.999% Aluminum (SFE ~200 mJ/m2), 99.95% Nickel (SFE ~125 mJ/m2), 99.95% Silver (SFE ~22 mJ/m2), and three alloys, alpha brass 70/30 (SFE >10 mJ/m2), 70/30 nickel copper (SFE ~100 mJ/ …
Electronic Properties Of Mos2/Moox Interfaces: Implications In Tunnel Field Effect Transistors And Hole Contacts,
2016
The University of Texas at Dallas
Electronic Properties Of Mos2/Moox Interfaces: Implications In Tunnel Field Effect Transistors And Hole Contacts, Santosh Kc, Roberto Longo, Rafik Addou, Robert Wallace, Kyeongjae Cho
Faculty Publications
In an electronic device based on two dimensional (2D) transitional metal dichalcogenides (TMDs), finding a low resistance metal contact is critical in order to achieve the desired performance. However, due to the unusual Fermi level pinning in metal/2D TMD interface, the performance is limited. Here, we investigate the electronic properties of TMDs and transition metal oxide (TMO) interfaces (MoS2/MoO3) using density functional theory (DFT). Our results demonstrate that, due to the large work function of MoO3 and the relative band alignment with MoS2, together with small energy gap, the MoS2/MoO3 interface is a good candidate for a tunnel field effect …
Partial Oxidation Of Surrogate Jet-A Fuel Over Sio2 Supported Moo2,
2016
Washington State University
Partial Oxidation Of Surrogate Jet-A Fuel Over Sio2 Supported Moo2, Shreya Shah, Oscar G. Marin-Flores, Chinnathambi Karthik, M. Grant Norton, Su Ha
Materials Science and Engineering Faculty Publications and Presentations
A SiO2-supported MoO2 nanoparticle catalyst was synthesized by a sol-gel method and tested as catalytic material for the partial oxidation of n-dodecane. MoO2 nanoparticles supported on SiO2 are °C, which is a typical reforming temperature for n-dodecane. The formation of Mo O Si bonds at the interface between MoO2 nanoparticles and SiO2 support appear to be responsible for the enhanced stability to sintering displayed by the nanoparticles. As a result of this particle size stabilization, SiO2 supported MoO2 nanoparticles show an improved reforming activity in terms of syngas generation …
Effect Of Stress Ratio On Fatigue Crack Growth Rate At Notched Hole In 7075-T6 Aluminum Alloy Under Biaxial Fatigue,
2016
Air Force Institute of Technology
Effect Of Stress Ratio On Fatigue Crack Growth Rate At Notched Hole In 7075-T6 Aluminum Alloy Under Biaxial Fatigue, Reja Alshahrani
Theses and Dissertations
This research investigates the behavior of fatigue crack growth rate in both laboratory air and saltwater (3.5% NaCl) environments for notched cruciform specimen made from 7075-T6 aluminum alloy sheet at different stress ratios. With biaxility ratio of 1, and frequency of applied load of 10 Hz, the crack growth behavior was investigated under in-plane biaxial tension-tension fatigue with 0.1, 0.5, 0.7 stress ratios and then compared them to study the effect of stress ratio on the crack growth rate. Finite Element Analysis (FEA) was used to calculate cyclic variation of stress intensity factors (delta K) at the crack tips. The …
Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Different Biaxial Stress Ratios,
2016
Air Force Institute of Technology
Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Different Biaxial Stress Ratios, Khalid A. Alghamdi
Theses and Dissertations
This thesis presents the results of a study to quantify the effects of biaxial loading on fatigue crack behavior in both air and saltwater (3.5% NaCl) environments from pre-cracked notched circular hole in a 7075-T6 cruciform specimen using a fracture mechanics approach. With stress ratio of R = 0.5, the crack growth behavior was investigated under fatigue loading with 0.5, 0, -0.5, and -1 biaxial stress ratio lambda. The crack propagation was monitored using optical microscopy. Finite Element Analysis was performed using the different stress ranges and stress ratios with various crack sizes to compute of stress intensity factors (delta …
Degradation Of Carbon Fiber Reinforced Polymer And Graphite By Laser Heating,
2016
Air Force Institute of Technology
Degradation Of Carbon Fiber Reinforced Polymer And Graphite By Laser Heating, Nicholas C. Herr
Theses and Dissertations
The availability of high power, diode pumped solid state and fiber lasers at powers 10 kW and shorter wavelengths (1.07 µm) has invigorated the development of tactical laser weapons. This shift to tactical missions greatly increases the variety of potential targets including carbon fiber reinforced polymers and related materials. The complexity of laser-material interactions has driven a historical reliance on live-fire testing and empirical models, but this becomes more difficult as the number of target materials grow. This dissertation combines thermal imagery and existing thermal models of the fire response of composite materials to develop a hybrid modeling approach of …
Nonlinear Machine Learning And Design Of Reconfigurable Digital Colloids,
2016
University of Illinois at Urbana-Champaign
Nonlinear Machine Learning And Design Of Reconfigurable Digital Colloids, Andrew W. Long, Carolyn L. Phillips, Eric Jankowski, Andrew L. Ferguson
Materials Science and Engineering Faculty Publications and Presentations
Digital colloids, a cluster of freely rotating “halo" particles tethered to the surface of a central particle, were recently proposed as ultra-high density memory elements for information storage. Rational design of these digital colloids for memory storage applications requires a quantitative understanding of the thermodynamic and kinetic stability of the configurational states within which information is stored. We apply nonlinear machine learning to Brownian dynamics simulations of these digital colloids to extract the low-dimensional intrinsic manifold governing digital colloid morphology, thermodynamics, and kinetics. By modulating the relative size ratio between halo particles and central particles, we investigate the size-dependent configurational …
High-Performance And Flexible Thermoelectric Films By Screen Printing Solution-Processed Nanoplate Crystals,
2016
Boise State University
High-Performance And Flexible Thermoelectric Films By Screen Printing Solution-Processed Nanoplate Crystals, Tony Varghese, Courtney Hollar, Joseph Richardson, Nicholas Kempf, Chao Han, Pasindu Gamarachchi, David Estrada, Yanliang Zhang
Materials Science and Engineering Faculty Publications and Presentations
Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate …
Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides,
2016
Air Force Institute of Technology
Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides, Hengky Chandrahalim, Stephen C. Rand, Xudong Fan
Faculty Publications
We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator – waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3′-Diethyloxacarbocyanine iodide (CY3) …
Protective Conversion Coating On Mixed-Metal Substrates And Methods Thereof,
2016
Missouri University of Science and Technology
Protective Conversion Coating On Mixed-Metal Substrates And Methods Thereof, Matthew O'Keefe, Surender Maddela
Materials Science and Engineering Faculty Research & Creative Works
Mixed-metal automotive vehicle bodies-in-white comprising ferrous metal surfaces, zinc surfaces, aluminum alloy surfaces, and magnesium alloy surfaces are cleaned and immersed in an aqueous bath comprising an adhesion promoter and an aqueous electrocoat bath (the adhesion promoter may be in the electrocoat bath. The adhesion promoter, which may be a cerium salt, is selected to react with each metal in the body surfaces to form an oxide layer that provides corrosion resistance for the surface and adherence for the deposited polymeric paint coating. The body is cathodic in the electrocoat deposition.
Gc Verification Of The Spacecraft Atmosphere Monitor,
2016
California Polytechnic State University, San Luis Obispo
Gc Verification Of The Spacecraft Atmosphere Monitor, Jessica S. Castro, Richard D. Kidd, Jeffrey D. Hein
STAR Program Research Presentations
International Space Station crew members face the unique challenge of maintaining air quality due to the volatile organic compounds (VOCs) that have the potential to accumulate at unsafe levels. The Spacecraft Atmosphere Monitor (SAM) is a miniature gas chromatograph/mass spectrometer (GCMS) designed to measure major constituents (such as N2, O2 and CO2) and trace VOCs within the cabin of the spacecraft. The gas chromatograph is responsible for separating the sample into its components in order to be characterized. The oven of the gas chromatograph must reach a temperature of 150°C in order to heat constituents …
Local Writing Of Exchange Biased Domains In A Heterostructure Of Co/Pd Pinned By Magnetoelectric Chromia,
2016
University of Nebraska - Lincoln
Local Writing Of Exchange Biased Domains In A Heterostructure Of Co/Pd Pinned By Magnetoelectric Chromia, Uday Singh, William Echtenkamp, M. Street, Christian Binek, Shireen Adenwalla
Shireen Adenwalla Papers
The writing of micrometer-scaled exchange bias domains by local, laser heating of a thin-film heterostructure consisting of a perpendicular anisotropic ferromagnetic Co/Pd multilayer and a (0001) oriented film of the magnetoelectric antiferromagnet Cr2O3 (chromia) is reported. Exchange coupling between chromia’s boundary magnetization and the ferromagnet leads to perpendicular exchange bias. Focused scanning magneto-optical Kerr measurements are used to measure local hysteresis loops and create a map of the exchange bias distribution as a function of the local boundary magnetization imprinted in the antiferromagnetic pinning layer on field cooling. The robust boundary magnetization of the Cr2O …
