Digital Commons Network^™

Design Of A Mobile Underwater Charging System, Brian R. Page

Dissertations, Master's Theses and Master's Reports

Autonomous Underwater Vehicles (AUVs) are extremely capable vehicles for numerous ocean related missions. AUVs are energy limited, resulting in short mission endurance on the scale of hours to days. Underwater Gliders (UGs) are able to operate on the order of months to years by using nontraditional propulsion methods. UGs, however, are unable to perform missions requiring high speed or direct forward motion due to the nature of their buoyancy driven motion. This work reviews the current state of the art in recharging AUVs and offers an underwater recharging network concept at a significantly reduced cost to traditional methods. The solution …

Coupling Granular Activated Carbon Adsorption With Membrane Bioreactor Treatment For Trace Organic Contaminant Removal: Breakthrough Behaviour Of Persistent And Hydrophilic Compounds, Luong N. Nguyen, Faisal I. Hai, William E. Price, Jinguo Kang, Long D. Nghiem

Faisal I Hai

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes …

Coupling Powdered Activated Carbon (Pac) Adsorption With Membrane Bioreactor (Mbr) Treatment For Enhanced Removal Of Trace Organics, Luong Nguyen, Faisal Ibney Hai, Long Nghiem, Jinguo Kang, William Price

Faisal I Hai

the occurrence of trace organics such as pesticides, pharmaceutically active compounds, natural and synthetic hormones as well as varous industrial compounds in the aquatic environment is of great concern due to their potential adverse effects on human health and those of other biota. Therefore, the removal of these compounds from wastewater is an important consideration to ensure safe drinking water and better protection of the environment. In the literature, several techniques have been explored for trace organics removal, namely, conventional activated sludge, membrane bioreactors (MBRs), and absorptioin. However it has been found that neither MBR nor activated carbon on its …

Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian K. Perera, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In future low voltage grids, with multiple inverter interfaced sources connected, voltage regulation may become a necessary task. The potential exists for inverter interfaced sources to be deployed to regulate the voltage at the point of common coupling (PCC) of each inverter interfaced sources. The PCC voltage regulation is attainable with inverter interfaced sources by dynamically controlling the amount of reactive power injected to the power distribution grid by individual systems. In the current research, a closed-loop controller is proposed to regulate the PCC voltage of a solar photovoltaic (PV) system that is connected to a single-phase power distribution feeder …

Nonlinear Optical Conductivity Of Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling In Terahertz Regime, Yee Sin Ang, J C. Cao, Chao Zhang

Yee Sin Ang

We reveal that two-dimensional semiconductors with Rashba spin-orbit interaction (R2DG) exhibit exceptionally strong nonlinear optical response (NOR) in the terahertz frequency regime. The spin-split of the parabolic energy band in R2DG allows strong multiple-photon process to occur via inter-subband mechanism. We show sharp multiple photon edges in the nonlinear conductivity. The edges correspond to the cut-off effect produced by the multiple-photon process. For Rashba coupling parameter of λ R ≈ 10−10 eV m, electric field strength in the order of only 102 V/cm is required for the NOR to dominate over the linear response. Furthermore, the roles of the parabolic …

Chiral-Like Tunneling Of Electrons In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Yee Sin Ang, Zhongshui Ma, C Zhang

Yee Sin Ang

The unusual tunneling effects of massless chiral fermions (mCF) and massive chiral fermions (MCF) in a single layer graphene and bilayer graphene represent some of the most bizarre quantum transport phenomena in condensed matter system. Here we show that in a two-dimensional semiconductor with Rashba spin-orbit coupling (R2DEG), the real-spin chiral-like tunneling of electrons at normal incidence simultaneously exhibits features of mCF and MCF. The parabolic branch of opposite spin in R2DEG crosses at a Dirac-like point and has a band turning point. These features generate transport properties not found in usual two-dimensional electron gas. Albeit its p Berry phase, …

Magnetocaloric Effect And Magnetostructural Coupling In Mn0.92fe0.08coge Compound, Jianli Wang, Precious Shamba, Wayne D. Hutchison, Qinfen Gu, M F. Md Din, Q Y. Ren, Zhenxiang Cheng, Shane J. Kennedy, Stewart J. Campbell, S X. Dou

Australian Institute for Innovative Materials - Papers

The structural properties of Mn_0.92Fe_0.08CoGe have been investigated in detail using synchrotron x-ray diffraction in zero and applied pressure (p = 0-10 GPa). A ferromagnetic transition occurs around T_C = 300 K and a large magnetic-entropy change −ΔS_M = 17.3 J/kg K detected at T_C for a field change of ΔB = 5 T. The field dependence of −ΔS _M ^max can be expressed as −ΔS _M ^max ∝ B. At ambient temperature and pressure, Mn_0.92Fe_0.08CoGe exhibits a co-existence of the orthorhombic TiNiSi-type structure (space group Pnma) and hexagonal …

Voltage Sag Compensation Of Point Of Common Coupling For Low Voltage Ride-Through Enhancment Of Inverter Interfaced Dg Using Bridge Type Fcl, Seyed Behzad Naderi, Michael Negnevitsky, Amin Jalilian, Mehrdad Tarafdar Hagh, Kashem M. Muttaqi

Faculty of Engineering and Information Sciences - Papers: Part A

Fully converter wind turbines and solar power utilise an inverter to connect to grid. The inverters are vulnerable to voltage sag in their terminal due to its damaging effect on semiconductor self-Turnoff switches. In this paper, a bridge-Type fault current limiter (B-FCL) is proposed for low voltage ride-Through (LVRT) of the inverters during different types of fault with simple control system. The proposed B-FCL is capable to compensate the voltage sag in point of common coupling (PCC) and makes a safe condition not only for the inverter but also for any equipment which has been connected to the PCC in …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …

Large Magnetoelectric Coupling In Magnetically Short-Range Ordered Bi5ti3feo15 Film, Hongyang Zhao, Hideo Kimura, Zhenxiang Cheng, Minoru Osada, Jianli Wang, Xiaolin Wang, S X. Dou, Yan Liu, Jianding Yu, Takao Matsumoto, Tetsuya Tohei, Naoya Shibata, Yuichi Ikuhara

Shi Xue Dou

Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. However, single-phase materials with such cross-coupling properties at room temperature exist rarely in nature; new design of nano-engineered thin films with a strong magneto-electric coupling is a fundamental challenge. Here we demonstrate a robust room-temperature magneto-electric coupling in a bismuth-layer-structured ferroelectric Bi5Ti3FeO15 with high ferroelectric Curie temperature of ~1000 K. Bi5Ti3FeO15 thin films grown by pulsed laser deposition are single-phase layered perovskit with nearly (00l)-orientation. Room-temperature multiferroic behavior is demonstrated by a large modulation in magneto-polarization and …

Auxiliary Roles In Stt-Mram Memory, Jayita Das

USF Tampa Graduate Theses and Dissertations

Computer memories now play a key role in our everyday life given the increase in the number of connected smart devices and wearables. Recently post-CMOS memory technologies are gaining significant research attention along with the regular ones. Spin Transfer Torque Magnetoresistive RAM (STT-MRAM) is one such post-CMOS memory technology with a rapidly growing commercial interest and potential across diverse application platforms. Research has shown the ability of STT-MRAM to replace different levels of memory hierarchy as well. In brief, STT-MRAM possesses all the favorable properties of a universal memory technology. In this dissertation we have explored the roles of this …

Design Of A Passive Ankle Prosthesis With Powered Push-Off Using A Cam Timing Mechanism, Jacob J. Rice

Master's Theses (2009 -)

This thesis presents the design and simulation results of the CamWalk, a novel passive prosthetic ankle that has mechanical behavior similar to that for a natural ankle. The CamWalk uses a compression spring network that allows coupling between two degrees of freedom; one for translation along the leg and another for rotation about the ankle joint. When walking, potential energy from the person's weight is stored in the spring network in deflection along the leg. The energy is released by the network as rotation of the foot. The amount of translational work that is converted to rotational work about the …

Simulating High Flux Isotope Reactor Core Thermal-Hydraulics Via Interdimensional Model Coupling, Adam Ross Travis

Masters Theses

A coupled interdimensional model is presented for the simulation of the thermal-hydraulic characteristics of the High Flux Isotope Reactor core at Oak Ridge National Laboratory. The model consists of two domains—a solid involute fuel plate and the surrounding liquid coolant channel. The fuel plate is modeled explicitly in three-dimensions. The coolant channel is approximated as a two-dimensional slice oriented perpendicular to the fuel plate’s surface. The two dimensionally-inconsistent domains are linked to one another via interdimensional model coupling mechanisms. The coupled model is presented as a simplified alternative to a fully explicit, fully three-dimensional model. Involute geometries were constructed in …

Field Penetration In Mri-Based Breast Models: A Numerical Investigation, Giuseppe Ruvio, Raffaele Solimene, Antonio Cuccaro, Max Ammann

Articles

The use of reliable computational tools is fundamental to investigate different aspects of microwave breast cancer imaging. From the development of high-definition and realistic numerical breast models, different coupling mechanisms and the reaction of different tissues to microwave signals can be characterized. In this paper, field penetration inside four numerical breast phantoms with varying adipose content is evaluated in the frequency range 0.5 - 10 GHz across sagittal cuts.

A Study Of Acoustic Boom Generation Due To Vibro-Acoustic Coupling In Passenger Cars, Mayuresh Pathak

Dissertations, Master's Theses and Master's Reports - Open

This thesis aims at understanding the vibro-acoustic behavior related to vehicle boom in passenger cars. Acoustic boom in the 40 Hz frequency range is studied on a 2013 Chevrolet Cruze LTZ model. Impact testing, full vehicle structural and acoustic modal tests are first performed to understand, locate and test the boom phenomenon and the fluid-structure interaction between the vehicle structure and acoustic cavity. Later, different iterations like effect of door cavities, trunk cavity and rear seats are also tested to understand their participation. LMS Test.Lab software is used for data acquisition, processing and analysis of the test results.

Finite Element …

Nonlinear Optical Conductivity Of Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling In Terahertz Regime, Yee Sin Ang, J C. Cao, Chao Zhang

Australian Institute for Innovative Materials - Papers

We reveal that two-dimensional semiconductors with Rashba spin-orbit interaction (R2DG) exhibit exceptionally strong nonlinear optical response (NOR) in the terahertz frequency regime. The spin-split of the parabolic energy band in R2DG allows strong multiple-photon process to occur via inter-subband mechanism. We show sharp multiple photon edges in the nonlinear conductivity. The edges correspond to the cut-off effect produced by the multiple-photon process. For Rashba coupling parameter of λ R ≈ 10−10 eV m, electric field strength in the order of only 102 V/cm is required for the NOR to dominate over the linear response. Furthermore, the roles of the parabolic …

Large Magnetoelectric Coupling In Magnetically Short-Range Ordered Bi5ti3feo15 Film, Hongyang Zhao, Hideo Kimura, Zhenxiang Cheng, Minoru Osada, Jianli Wang, Xiaolin Wang, S X. Dou, Yan Liu, Jianding Yu, Takao Matsumoto, Tetsuya Tohei, Naoya Shibata, Yuichi Ikuhara

Australian Institute for Innovative Materials - Papers

Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. However, single-phase materials with such cross-coupling properties at room temperature exist rarely in nature; new design of nano-engineered thin films with a strong magneto-electric coupling is a fundamental challenge. Here we demonstrate a robust room-temperature magneto-electric coupling in a bismuth-layer-structured ferroelectric Bi5Ti3FeO15 with high ferroelectric Curie temperature of ~1000 K. Bi5Ti3FeO15 thin films grown by pulsed laser deposition are single-phase layered perovskit with nearly (00l)-orientation. Room-temperature multiferroic behavior is demonstrated by a large modulation in magneto-polarization and …

Chiral-Like Tunneling Of Electrons In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Yee Sin Ang, Zhongshui Ma, C Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

The unusual tunneling effects of massless chiral fermions (mCF) and massive chiral fermions (MCF) in a single layer graphene and bilayer graphene represent some of the most bizarre quantum transport phenomena in condensed matter system. Here we show that in a two-dimensional semiconductor with Rashba spin-orbit coupling (R2DEG), the real-spin chiral-like tunneling of electrons at normal incidence simultaneously exhibits features of mCF and MCF. The parabolic branch of opposite spin in R2DEG crosses at a Dirac-like point and has a band turning point. These features generate transport properties not found in usual two-dimensional electron gas. Albeit its p Berry phase, …

Raman Scattering Reveals Strong Lo-Phonon-Hole-Plasmon Coupling In Nominally Undoped Gaasbi: Optical Determination Of Carrier Concentration, Julian Steele, R A. Lewis, M Henini, O M. Lemine, D. Fan, Yu. I. Mazur, V G. Dorogan, P C. Grant, S Q. Yu, G J. Salamo

Faculty of Engineering and Information Sciences - Papers: Part A

We report room-temperature Raman scattering studies of nominally undoped (100) GaAs1−xBix epitaxial layers exhibiting Bi-induced (p-type) longitudinal-optical-plasmon-coupled (LOPC) modes for 0.018 ≤ x ≤ 0.048. Redshifts in the GaAs-like optical modes due to alloying are evaluated and are paralleled by strong damping of the LOPC. The relative integrated Raman intensities of LO(Γ) and LOPC ALO/ALOPC are characteristic of heavily doped p-GaAs, with a remarkable near total screening of the LO(Γ) phonon (ALO/ALOPC → 0) for larger Bi concentrations. A method of spectral analysis is set out which yields estimates of hole concentrations in excess of 5 × 1017cm−3 and correlates …

90° Magnetic Coupling In A Nife/Femn/Biased Nife Multilayer Spin Valve Component Investigated By Polarized Neutron Reflectometry, S J. Callori, J Bertinshaw, David L. Cortie, J W. Cai, A P. Le Brun, T Zhu, Frank Klose

Australian Institute for Innovative Materials - Papers

We have observed 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer system using polarized neutron reflectometry. Magnetometry results show magnetic switching for both the biased and free NiFe layers, the latter of which reverses at low applied fields. As these measurements are only capable of providing information about the total magnetization within a sample, polarized neutron reflectometry was used to investigate the reversal behavior of the NiFe layers individually. Both the non-spin-flip and spin-flip neutron reflectometry signals were tracked around the free NiFe layer hysteresis loop and were used to detail the evolution of the magnetization during reversal. At low …

Electronic Coupling And Catalytic Effect On H2 Evolution Of Mos2/Graphene Nanocatalyst, Ting Liao, Ziqi Sun, Chenghua Sun, S X. Dou, Debra J. Searles

Australian Institute for Innovative Materials - Papers

Inorganic nano-graphene hybrid materials that are strongly coupled via chemical bonding usually present superior electrochemical performance. However, how the chemical bond forms and the synergistic catalytic mechanism remain fundamental questions. In this study, the chemical bonding of the MoS 2 nanolayer supported on vacancy mediated graphene and the hydrogen evolution reaction of this nanocatalyst system were investigated. An obvious reduction of the metallic state of the MoS 2 nanolayer is noticed as electrons are transferred to form a strong contact with the reduced graphene support. The missing metallic state associated with the unsaturated atoms at the peripheral sites in turn …

Imaging The Electron-Boson Coupling In Superconducting Fese Films Using A Scanning Tunneling Microscope, Canli Song, Yi-Lin Wang, Yeping Jiang, Zhi Li, Lili Wang, Ke He, Xi Chen, Jennifer E. Hoffman, Xu-Cun Ma, Qi-Kun Xue

Australian Institute for Innovative Materials - Papers

Scanning tunneling spectroscopy has been used to reveal signatures of a bosonic mode in the local quasiparticle density of states of superconducting FeSe films. The mode appears below Tc as a "dip-hump" feature at energy Ω ∼ 4.7kBTc beyond the superconducting gap Δ. Spectra on strained regions of the FeSe films reveal simultaneous decreases in Δ and Ω. This contrasts with all previous reports on other high-Tc superconductors, where Δ locally anticorrelates with Ω. A local strong coupling model is found to reconcile the discrepancy well, and to provide a unified picture of the electron-boson coupling in unconventional superconductors.

Predictive Maturity Of Inexact And Uncertain Strongly Coupled Numerical Models, Ismail Farajpour

All Dissertations

The Computer simulations are commonly used to predict the response of complex systems in many branches of engineering and science. These computer simulations involve the theoretical foundation, numerical modeling and supporting experimental data, all of which contain their associated errors. Furthermore, real-world problems are generally complex in nature, in which each phenomenon is described by the respective constituent models representing different physics and/or scales. The interactions between such constituents are typically complex in nature, such that the outputs of a particular constituent may be the inputs for one or more constituents. Thus, the natural question then arises concerning the validity …

Coupling Granular Activated Carbon Adsorption With Membrane Bioreactor Treatment For Trace Organic Contaminant Removal: Breakthrough Behaviour Of Persistent And Hydrophilic Compounds, Luong N. Nguyen, Faisal I. Hai, William E. Price, Jinguo Kang, Long D. Nghiem

William E. Price

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes …

Advances In The Redcat Software Package, Chris Schmidt, Stephanie J. Irausquin, Homayoun Valafar

Faculty Publications

Background

Residual Dipolar Couplings (RDCs) have emerged in the past two decades as an informative source of experimental restraints for the study of structure and dynamics of biological macromolecules and complexes. The REDCAT software package was previously introduced for the analysis of molecular structures using RDC data. Here we report additional features that have been included in this software package in order to expand the scope of its analyses. We first discuss the features that enhance REDCATs user-friendly nature, such as the integration of a number of analyses into one single operation and enabling convenient examination of a structural ensemble …

Graphene Micro-Substrate Induced High Electron-Phonon Coupling In Mgb2, W X. Li, X Xu, K S. B De Silva, F X. Xiang, S X. Dou

Shi Xue Dou

Electron-phonon coupling strength was studied in graphene-MgB2 composites to explore the possibilities for a higher superconducting transition temperature (Tc). For the first time in the experimental work on MgB2, the Raman active E2g mode was split into two parts: a softened mode corresponding to tensile strain and a hardened mode attributed to the carbon substitution effect. The tensile strain effect is suggested to improve Tc of graphene-MgB2 composites because it increases the electron-phonon coupling strength of MgB2.

Transient Small Wind Turbine Tower Structural Analysis With Coupled Rotor Dynamic Interaction, George R. Katsanis

Master's Theses

Structural dynamics is at the center of wind turbine tower design - excessive vibrations can be caused by a wide range of environmental and mechanical sources and can lead to reduced component life due to fatigue, noise, and impaired public perception of system integrity. Furthermore, periodic turbulent wind conditions can cause system resonance resulting in significantly increased structural loads. Structural vibration issues may become exacerbated in small wind applications where the analytical and experimental resources for system verification and optimization are scarce. This study combines several structural analysis techniques and packages them into a novel and integrated form that can …

Graphene Micro-Substrate Induced High Electron-Phonon Coupling In Mgb2, W X. Li, X Xu, K S. B De Silva, F X. Xiang, S X. Dou

Faculty of Engineering and Information Sciences - Papers: Part A

Electron-phonon coupling strength was studied in graphene-MgB2 composites to explore the possibilities for a higher superconducting transition temperature (Tc). For the first time in the experimental work on MgB2, the Raman active E2g mode was split into two parts: a softened mode corresponding to tensile strain and a hardened mode attributed to the carbon substitution effect. The tensile strain effect is suggested to improve Tc of graphene-MgB2 composites because it increases the electron-phonon coupling strength of MgB2.

Energy-Loss Rate Of A Fast Particle In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Wei Feng, Asya Tawfiq, J.C Cao, Chao Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

The energy-loss rate (ELR) of a charged particle in a two-dimensional semiconductor with Rashba spin-orbit coupling is studied. Our model takes into account of the temperature and density dependence of the electronic properties of the Rashba system. The energy and temperature dependence of the ELR are presented. It is found that a finite Rashba spin-orbit coupling offers a mechanism of tuning the mean scattering time in narrow-gap semiconductors. With a change of Rashba parameter of around 3 times, the mean scattering time can change by one to two orders of magnitude. © 2013 American Institute of Physics.

Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian K. Perera, Philip Ciufo, Sarath Perera

Faculty of Engineering and Information Sciences - Papers: Part A

In future low voltage grids, with multiple inverter interfaced sources connected, voltage regulation may become a necessary task. The potential exists for inverter interfaced sources to be deployed to regulate the voltage at the point of common coupling (PCC) of each inverter interfaced sources. The PCC voltage regulation is attainable with inverter interfaced sources by dynamically controlling the amount of reactive power injected to the power distribution grid by individual systems. In the current research, a closed-loop controller is proposed to regulate the PCC voltage of a solar photovoltaic (PV) system that is connected to a single-phase power distribution feeder …