Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem,
2018
Nanjing University of Science and Technology
Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar
SIUE Faculty Research, Scholarship, and Creative Activity
This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters tau_i, i = 1, 2, . . . ,K. The characteristic quasipolynomial of such an equation is a multilinear function of exp(-tau_i s). It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delayper- scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence …
Nonlinear Ocean Energy Harvester,
2018
Florida Institute of Technology
Nonlinear Ocean Energy Harvester, Dane Sequeira
Link Foundation Ocean Engineering and Instrumentation Fellowship Reports
The scientific community has worked to extend communication networks, human safety programs, and environmental monitoring systems across continents, but has struggled to accomplish these same goals beyond the shoreline. Lack of offshore power is the greatest barrier restricting us from exploring the ocean because it is difficult to operate sensors without a reliable power source. Wave energy harvesting has been investigated as a solution; however, current methods have many shortcomings. Traditional ocean energy harvesters (e.g. buoys) extract energy from ocean waves by capturing the change in potential energy as the buoy travels vertically along the wave. A linear design, this …
Surface Modification Of Titanium For Hard-Tissue Engineering Applications,
2018
Northern Illinois University
Surface Modification Of Titanium For Hard-Tissue Engineering Applications, Murali Krishna Duvvuru
Graduate Research Theses & Dissertations
Titanium (Ti) and its alloys are widely used in dental and orthopedic applications due to their advantages such as biocompatibility, excellent corrosion resistance and mechanical properties like low Young’s modulus, low density and high strength as compared to other metallic implants. However, lack of interaction with host tissue (e.g. bioinertness), higher modulus of elasticity as compared to that of bone and resultant stress shielding cause fibrous tissue formation around the implant where the interaction with tissue is minimized. These will eventually cause the implant loosening and revision surgery is needed. Surface modification of Ti by increasing surface roughness and/or incorporation …
Resistance Temperature Detectors In A Cryostat Refrigeration System,
2018
San Diego State University
Resistance Temperature Detectors In A Cryostat Refrigeration System, Kirsten Marie Manahan, Alice Callen
STAR Program Research Presentations
The Large Synoptic Survey Telescope (LSST) is a ground-based telescope that will survey the Southern sky every few nights. Located in the telescope will be a 3.2 gigapixel digital camera. To ensure proper instrumentation of the camera, there must be a monitored stable temperature. As part of my research, I assembled resistance temperature detectors and tested them to verify their reliability in measuring temperature in the camera’s cryostat refrigeration cooling system. Resistance temperature detectors function by the principle of thermal resistivity, in which their electrical resistances vary as temperature varies. Through testing, I was able to determine whether these particular …
Characterization Of Fast Flames For Turbulence-Induced Deflagration To Detonation Transition,
2018
University of Central Florida
Characterization Of Fast Flames For Turbulence-Induced Deflagration To Detonation Transition, Jessica Chambers
Electronic Theses and Dissertations
One of the fundamental mechanisms for detonation initiation is turbulence driven deflagration to detonation transition (TDDT). The research experimentally explores the propagation dynamics demonstrated by fast deflagrated flames interacting with highly turbulent reactants. Fast flames produce extremely high turbulent flame speeds values, increased levels of compressibility and develop a runaway mechanism that leads to TDDT. The flame structural dynamics and reacting flow field are characterized using simultaneous high-speed particle image velocimetry, chemiluminescence, and Schlieren measurements. The investigation classifies the fast flame propagation modes at various regimes. The study further examines the conditions for a turbulent fast flame at the boundary …
The Study Of An Impinging Unsteady Jet - Fluid Mechanics And Heat Transfer Analysis,
2018
University of Central Florida
The Study Of An Impinging Unsteady Jet - Fluid Mechanics And Heat Transfer Analysis, Andrea Osorio
Electronic Theses and Dissertations
The high heat transfer capabilities of impinging jets have led to their widespread use in industrial applications, such as gas turbine cooling. These impinging jets are usually manufactured on the walls of super-alloy metals and are influenced by being positioned with a confined setting. Studies have been shown to enhance the heat transfer of impinging jets by fluctuating the flow which will be analyzed in this project with two designs. The first design is a self-sustaining stationary fluidic oscillator that causes a sweeping motion jet to impinge on the surface. This is investigated using Particle Image Velocimetry (PIV) to study …
Multi-Scale Fluid-Structure Interaction Model Analysis Of Patient-Specific Geometry For Optimization Of Lvad Outflow Graft Implantation: An Investigation Aimed At Reducing Stroke Risk,
2018
University of Central Florida
Multi-Scale Fluid-Structure Interaction Model Analysis Of Patient-Specific Geometry For Optimization Of Lvad Outflow Graft Implantation: An Investigation Aimed At Reducing Stroke Risk, Ray Prather
Electronic Theses and Dissertations
A Left Ventricular Assist Device (LVAD), is a mechanical pump capable of providing circulatory myocardium relief when used as bridge-to-transplantation by reducing the workload of a failing heart, with the additional bonus of allowing for cardiac recovery when used as destination therapy. The newer generations of continuous flow VADs are essentially axial or radial flow pumps, and while these devices are capable their efficiency depends upon fluid composition and flow field patterns. The most devastating complication of VAD therapy is caused by embolization of thrombi formed within the LVAD or inside the heart into the brain leading to stroke. Anticoagulation …
Mechanical Annealing Of Model Glasses: Effects Of Strain Amplitude And Temperature,
2018
Wright State University - Main Campus
Mechanical Annealing Of Model Glasses: Effects Of Strain Amplitude And Temperature, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics simulations are performed to examine the dynamic response of amorphous solids to oscillatory shear at finite temperatures. The data were collected from a poorly annealed binary glass, which was deformed periodically in the elastic regime during several hundred shear cycles. We found that the characteristic time required to reach a steady state with a minimum potential energy is longer at higher temperatures and larger strain amplitudes. With decreasing strain amplitude, the asymptotic value of the potential energy increases but it remains lower than in quiescent samples. The transient decay of the potential energy correlates well with a gradual …
Numerical Study Of Interfacial Flow Using Algebraic Coupled Level Set-Volume Of Fluid (A-Clsvof) Method,
2018
University of Central Florida
Numerical Study Of Interfacial Flow Using Algebraic Coupled Level Set-Volume Of Fluid (A-Clsvof) Method, Majid Haghshenas
Electronic Theses and Dissertations
Solving interfacial flows numerically has been a challenge due to the lack of sharpness and the presence of spurious currents at the interface. Two methods, Algebraic Coupled Level Set-Volume of Fluid (A-CLSVOF) method and Ghost Fluid Method (GFM) have been developed in the finite volume framework and employed in several interfacial flows such as Rayleigh-Taylor instability, rising bubble, impinging droplet and cross-flow oil plume. In the static droplet simulation, A-CLSVOF substantially reduces the spurious currents. The capillary wave relaxation shows that this method delivers results comparable to those of more rigorous methods such as Front Tracking methods for fine grids. …
Investigation Of Oxy-Fuel Combustion Behind Reflected Shockwaves,
2018
University of Central Florida
Investigation Of Oxy-Fuel Combustion Behind Reflected Shockwaves, Owen Pryor
Electronic Theses and Dissertations
Supercritical carbon dioxide has brought about new questions on the chemical kinetics of several small hydrocarbon fuels and the effects of carbon dioxide as the primary diluent on the different fuels. This report presents work on the ignition delay times and several species time-histories of methane, ethylene and syngas over a range of conditions. All experiments were conducted behind reflected shock waves using two different shock tubes. The ignition delay times were measured using a GaP photodetector to measure the emission of light. The species time-histories were measured using single laser spectroscopy. The effect of CO2 as a diluent on …
In Vitro Assessment Of The Effects Of Valvular Stenosis On Aorta Hemodynamics And Left Ventricular Function,
2018
Wright State University
In Vitro Assessment Of The Effects Of Valvular Stenosis On Aorta Hemodynamics And Left Ventricular Function, Ashish Madan
Browse all Theses and Dissertations
Calcific aortic stenosis (CAS) is the most common valvular heart disease and is associated with aortopathy and ventricular dysfunction. Hemodynamic alterations due CAS could affect the aorta lining (endothelium), that is in direct contact with the blood, triggering adverse biological responses that may possibly cause aortic dilation and dissection. Also, CAS could impose excessive ventricular load leading to ventricular wall thickening, thus putting an individual at a higher risk of heart attack or stroke. These pathophysiological effects of CAS are highly dependent on the degree of calcification. However, the impact of CAS development on aorta flow and left ventricular workload …
Hydrophobicity Of Low Temperature Vibrating Surfaces,
2018
Virginia Commonwealth University
Hydrophobicity Of Low Temperature Vibrating Surfaces, Christian Fergusson
Theses and Dissertations
This study proposes a method to enhance the anti-icing capabilities of superhydrophobic surfaces by utilizing vibration to further reduce contact time of an impacting droplet in addition to keeping the droplet in the Cassie-Baxter regime, where surface adhesion is lower than the opposing Wenzel regime. We tested this with two methods: by investigating the effects of vibration normal to the plane of a superhydrophobic surface being impacted by water droplets in a room temperature environment, with the surface horizontal in a room temperature environment and tiled in a subzero degree environment. The amplitude and frequency of the vibration were varied …
A Quantitative Environmental Assessment Of Incorporating Torrefaction Into Farming Enterprises In Eastern South Dakota,
2018
South Dakota State University
A Quantitative Environmental Assessment Of Incorporating Torrefaction Into Farming Enterprises In Eastern South Dakota, Dinesh Fuyal
Electronic Theses and Dissertations
The use of renewable energy sources has been increasing in the recent years due to population growth and environmental concerns. Biomass is a promising energy source that can be used to produce biofuels or torrefied pellets. Torrefied biomass may be used in power plants, industrial and residential heating, feedstocks for gasification, air and water filtrating, and soil amendment. The interest of torrefied pellets as energy sources for various applications has been increased in the recent years due to the concerns about energy security and environmental issues. This study focuses on the economic and environmental assessment of agricultural feedstocks like corn …
Nonlinear Stochastic Filtering For Online State Of Charge And Remaining Useful Life Estimation Of Lithium-Ion Battery,
2018
South Dakota State University
Nonlinear Stochastic Filtering For Online State Of Charge And Remaining Useful Life Estimation Of Lithium-Ion Battery, Suresh Daravath
Electronic Theses and Dissertations
Battery state monitoring is one of the key techniques in Battery Management System (BMS). Accurate estimation can help to improve the system performance and to prolong the battery lifetime. The main challenges for the state online estimation of Li-ion batteries are the flat characteristic of open circuit voltage (OCV) with the function of the state of charge. Hence, the focus of this thesis study is to estimation of the state of charge (SOC) of Li-ion with high accuracy, more robustness. A 2nd order RC equivalent circuit model is adapted to battery model for simulation, mathematical model analysis, and dynamics characteristic …
Simulation Of Non-Premixed Ethylene-Air Crossflow Jet Flame,
2018
South Dakota State
Simulation Of Non-Premixed Ethylene-Air Crossflow Jet Flame, Jennifer Onyinye Chikelu
Electronic Theses and Dissertations
Computational fluid dynamics tool has been employed in the past to determine and analyze efficiency or performance in combustion engines and for combustion analysis. This paper represents a systematic investigation on the best model predicts the temperature and soot production in coflow jet flame, by applying various RANS turbulent model, soot models and radiation models in presence or absence of gravity. It also applies this model predicted in crossflow jet flame and investigates the velocity ratio (ratio of the velocity of fuel jet to the velocity of air stream) variation effect on temperature and soot production. ANSYS-Fluent CFD software tool …
Development Of An Indoor Multirotor Testbed For Experimentation On Autonomous Guidance Strategies,
2018
South Dakota State University
Development Of An Indoor Multirotor Testbed For Experimentation On Autonomous Guidance Strategies, Kidus Guye
Electronic Theses and Dissertations
Despite the vast popularity of rotary wing unmanned aerial vehicles and research centres that develop their guidance software, there are only a limited number of references that provide an exhaustive description of a step-by-step procedure to build-up a multirotor testbed. In response to such need, the first part of this thesis aims to describe, in detail, the complete procedure to establish and operate an autonomous multirotor unmanned aerial vehicle indoor experimental platform to test and validate guidance, navigation and control strategies. Both hardware and software aspects of the testbed are described to offer a complete understanding of the different aspects. …
Analytical Cpg Model Driven By Limb Velocity Input Generates Accurate Temporal Locomotor Dynamics,
2018
West Virginia University
Analytical Cpg Model Driven By Limb Velocity Input Generates Accurate Temporal Locomotor Dynamics, Sergiy Yakovenko, Anton Sobinov, Valeriya Gritsenko
Faculty & Staff Scholarship
The ability of vertebrates to generate rhythm within their spinal neural networks is essential for walking, running, and other rhythmic behaviors. The central pattern generator (CPG) network responsible for these behaviors is well-characterized with experimental and theoretical studies, and it can be formulated as a nonlinear dynam- ical system. The underlying mechanism responsible for locomotor behavior can be expressed as the process of leaky integration with resetting states generating appropriate phases for changing body velocity. The low-dimensional input to the CPG model generates the bilateral pattern of swing and stance modulation for each limb and is consistent with the desired …
Fabrication And Thermoelectric Characterization Of Transition Metal Silicide-Based Composite Thermocouples,
2018
West Virginia University
Fabrication And Thermoelectric Characterization Of Transition Metal Silicide-Based Composite Thermocouples, Gunes A. Yakaboylu, Rajalekshmi C. Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
Faculty & Staff Scholarship
Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi2, WSi2, ZrSi2, or TaSi2 with an additional 10 vol % Al2O3 to form a silicide–oxide composite. The structural and high-temperature thermoelectric properties of the composite thermocouples were examined using X-ray diffraction, scanning electron microscopy and a typical hot–cold junction measurement technique. MoSi2-Al2O3 and WSi2-Al2O3 composites exhibited higher intrinsic Seebeck coefficients (22.2–30.0 μV/K) at high-temperature gradients, which were calculated from the thermoelectric data of …
Interval Fuzzy Model For Robust Aircraft Imu Sensors Fault Detection,
2018
Universita di Perugia
Interval Fuzzy Model For Robust Aircraft Imu Sensors Fault Detection, Michele Crispoltoni, Mario Luca Fravolini, Fabio Balzano, Stephane D'Urso, Marcello Rosario Napolitano
Faculty & Staff Scholarship
This paper proposes a data-based approach for a robust fault detection (FD) of the inertial measurement unit (IMU) sensors of an aircraft. Fuzzy interval models (FIMs) have been introduced for coping with the significant modeling uncertainties caused by poorly modeled aerodynamics. The proposed FIMs are used to compute robust prediction intervals for the measurements provided by the IMU sensors. Specifically, a nonlinear neural network (NN) model is used as central prediction of the sensor response while the uncertainty around the central estimation is captured by the FIM model. The uncertainty has been also modelled using a conventional linear Interval Model …
Learning Local, Quenched Disorder In Plasticity And Other Crackling Noise Phenomena,
2018
West Virginia University & The John Hopkins University
Learning Local, Quenched Disorder In Plasticity And Other Crackling Noise Phenomena, Stefanos Papanikolaou
Faculty & Staff Scholarship
When far from equilibrium, many-body systems display behavior that strongly depends on the initial conditions. A characteristic such example is the phenomenon of plasticity of crystalline and amorphous materials that strongly depends on the material history. In plasticity modeling, the history is captured by a quenched, local and disordered flow stress distribution. While it is this disorder that causes avalanches that are commonly observed during nanoscale plastic deformation, the functional form and scaling properties have remained elusive. In this paper, a generic formalism is developed for deriving local disorder distributions from field- response (e.g., stress/strain) timeseries in models of crackling …
