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Articles 1 - 20 of 20
Full-Text Articles in Engineering
Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb
Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb
The Pegasus Review: UCF Undergraduate Research Journal
Because blood is challenging to use as a working fluid in a laboratory setting due to health and safety concerns, a blood analogue would be useful to perform benchtop experiments. Viscosity is an important fluid property for modeling and experiments, especially because blood is a shear thinning fluid; therefore, it has a decreasing viscosity with higher shear rates. This project seeks to create a blood-mimicking fluid for benchtop laboratory use. Numerous fluids with different combinations of water, glycerin, salt, and xanthan gum (XG) were created to mimic blood viscosity at different hematocrit levels. Four additional solutions were also created from …
Experimentation And Simulation Of Pulsed Eddy Current Thermography Of Subsurface Aircraft Corrosive Defects, Johnathan Hernandez
Experimentation And Simulation Of Pulsed Eddy Current Thermography Of Subsurface Aircraft Corrosive Defects, Johnathan Hernandez
Electronic Theses and Dissertations, 2020-
During the life cycle of aircraft, external structures are under constant attack from environmental degradation in the form of corrosion. Corrosive defects consist of multiple types of surface and subsurface damage that are often undetectable due to surface coatings or insulation leading to loss in structural integrity. Non-destructive techniques for corrosion detection typically require the removal of paint. Detection of corrosion under insulation (CUI) is highly valuable for cost and time effectiveness. Although techniques have been developed for detection of CUI, not many of these satisfy the criteria for portability and hangar operation. To address this, multiple techniques were investigated …
Degradation From Cmas Infiltration In 7ysz Eb-Pvd Thermal Barrier Coatings, Zachary Stein
Degradation From Cmas Infiltration In 7ysz Eb-Pvd Thermal Barrier Coatings, Zachary Stein
Honors Undergraduate Theses
The lifetime of the high temperature ceramic coating 7 wt.% yttria-stabilized zirconia (7YSZ) is reduced when calcium-magnesium-alumino-silicate (CMAS) particulates enters aero-engines during operation in a sandy or dusty environment, melts, and infiltrates into the coating. 7YSZ undergo both chemical and mechanical degradation from CMAS infiltration during cycling. Characterization methods with synchrotron X-ray diffraction (XRD) provides a non-destructive means to measure the impact of time and temperature on coating degradation with high spatial resolution of 7YSZ coatings infiltrated and annealed by CMAS for 1 hour and 10 hours as well as at 1225 °C and 1250 °C. Additionally, qualitative results of …
A Study Into Validating A Coupled Method Of Characteristics And Direct Simulation Monte Carlo Method Against Empirical Data, Andrew Brown
A Study Into Validating A Coupled Method Of Characteristics And Direct Simulation Monte Carlo Method Against Empirical Data, Andrew Brown
Electronic Theses and Dissertations, 2020-
The following will outline the methodology and results of validating a coupled Method of Characteristics (MOC) and Direct Simulation Monte Carlo (DSMC) method. This research focused specifically on modeling plume impingement, induced by Reaction Control System (RCS) thrusters that flew on the National Aeronautics and Space Administration's (NASA's) space shuttle Discovery. For each simulation, the continuum portion of the RCS thruster was simulated using MOC for solving hyperbolic Partial Differential Equations (PDEs) and computed with the NASA code, Reacting and Multi-phase Program (RAMP). The solution was then implemented as a starting condition into the NASA DSMC code, Direct Simulation and …
Rapid Orbital Motion Emulator (Rome): Kinematics Modeling And Control, Ahmed Elsadek Ahmed Seleit
Rapid Orbital Motion Emulator (Rome): Kinematics Modeling And Control, Ahmed Elsadek Ahmed Seleit
Electronic Theses and Dissertations, 2020-
Space missions design requires already tested and trusted control algorithms for spacecraft motion. Rapidly testing control algorithms at a low cost is essential. A novel robotic system that emulates orbital motion in a laboratory environment is presented. The system is composed of a six degree of freedom robotic manipulator fixed on top of an omnidirectional ground vehicle accompanied with onboard computer and sensors. The integrated mobile manipulator is used as a testbed to emulate and realize orbital motion and control algorithms. The kinematic relations of the ground vehicle, robotic manipulator and the coupled kinematics are derived. The system is used …
Ensuring Positive Definiteness In Linear Viscoelastic Material Functions Based On Prony Series, Christopher D. Rehberg
Ensuring Positive Definiteness In Linear Viscoelastic Material Functions Based On Prony Series, Christopher D. Rehberg
Honors Undergraduate Theses
This thesis presents a method to correct for non-positive-definiteness in linear viscoelastic material functions. Viscoelastic material functions for anisotropic materials need to be interconverted in a matrix coefficient prony series form, with a requirement of positive definiteness. Fitting is usually done as a uniaxial prony series, resulting in scalar coefficients. When these uniaxial coefficients are placed in a coefficient matrix, the required positive definiteness cannot be guaranteed. For those matrices that do not meet this requirement, finding the nearest symmetric semi-positive definite form of the matrix results in a viable prony series matrix coefficient with the required positive definiteness. These …
Thermal-Hydraulic Optimization Of The Heat Exchange Between A Molten Salt Small Modular Reactor And A Super-Critical Carbon Dioxide Power Cycle, James Sherwood
Thermal-Hydraulic Optimization Of The Heat Exchange Between A Molten Salt Small Modular Reactor And A Super-Critical Carbon Dioxide Power Cycle, James Sherwood
Honors Undergraduate Theses
The next generation of nuclear power sources, Gen. IV, will include an emphasis on small, modular reactor (SMR) designs, which will allow for standardized, factory-based manufacturing and flexibility in the design of power plants by utilizing one or several modular reactor units in parallel. One of the reactor concepts being investigated is the Molten Salt Reactor concept (MSR), which utilizes a molten salt flow loop to cool the reactor and transfer heat to the power conversion cycle (PCS).Here, the use of a supercritical carbon dioxide (S-CO2) Brayton cycle is assumed for that PCS. The purpose of this thesis is to …
A Generalized Low Order Model For Vortex Shedding From A Tandem Cylinder Arrangement Using Delay Coupled Van Der Pol Oscillators, Michael Soroka
A Generalized Low Order Model For Vortex Shedding From A Tandem Cylinder Arrangement Using Delay Coupled Van Der Pol Oscillators, Michael Soroka
Honors Undergraduate Theses
A generalized low order model (LOM) for the fluctuating lift coefficient caused by vortex shedding from a tandem cylinder pair is proposed to expand upon models from previous authors. This model could provide a reduced computational time method for collecting qualitative and quantitive data from a tandem shedding pair. A delay coupled system with sufficient bifurcation characteristics is developed to account for the different flow regimes (extended-body, reattachment, and co-shedding) which occur as cylinder spacing is varied. Coefficient and parameter fitting is performed to fit experimental data. Finally, results and physical interpretations of the interactions in the model are discussed. …
Viscoelastic Analysis Of High Strain Composites For Deployable Structures In Space Applications, Andrew Gomez-Delrio
Viscoelastic Analysis Of High Strain Composites For Deployable Structures In Space Applications, Andrew Gomez-Delrio
Electronic Theses and Dissertations, 2020-
Thin-ply composite laminates capable of enduring high strains are currently under investigation for compliant deployable spacecraft structures. Deployable structures such as booms fabricated from these materials can be flattened and coiled to high curvatures, achieving a compact configuration for stowage. Once in orbit, they are released with minimal actuation for deployment, allowing the operational geometry to be recovered. Previous studies have shown that the viscoelastic properties of the composite epoxy matrix can negatively impact final shape accuracy due to stress relaxation during stowage. In addition, since the strain energy stored is relied upon for deployment, considerable relaxation can potentially result …
Study Of Non-Ideal Effects On Shock Wave Propagation, Cory Kinney
Study Of Non-Ideal Effects On Shock Wave Propagation, Cory Kinney
Electronic Theses and Dissertations, 2020-
Shock tube experiments provide insightful data on combustion, emissions, and ablation characterization for a wide variety of defense and energy sector research topics. Accurate characterization of shock tube facilities is essential to verifying the accuracy of research data. Non-ideal effects, such as boundary layer growth, introduce uncertainty into pressure and temperature conditions, the primary independent variables of interest for shock tube research results. The effect of boundary layer growth on shock tube experiments was investigated by conducting simulations for University of Central Florida's two geometrically different shock tube using StanShock, a quasi-one-dimensional, reacting, compressible flow solver. The characteristic quantities considered …
Evaluation Of Convective Heat Transfer Numerical Methods On Rough Surfaces From Additive Manufacturing, Jose Urcia
Evaluation Of Convective Heat Transfer Numerical Methods On Rough Surfaces From Additive Manufacturing, Jose Urcia
Electronic Theses and Dissertations, 2020-
The high versatility of additive manufacturing has led to an increase in use in a number of different fields. Surface roughness then comes as a natural consequence of additive manufacturing which interferes with a smooth wall assumption such as those found in gas turbine blades. The Discrete Element Roughness Method (DERM) has been used to improve convective heat transfer predictions on surface roughness. This work aims to validate the core momentum and heat transfer correlation of DERM through an evaluation of Computational fluid dynamics (CFD)-based solution of the flow around individual roughness elements with the goal of improving the correlations. …
Inertial Orbit Estimation Using Multiple Space Based Observers: A New Measurement Model, James Hippelheuser
Inertial Orbit Estimation Using Multiple Space Based Observers: A New Measurement Model, James Hippelheuser
Electronic Theses and Dissertations, 2020-
Presented within this work is a new method for inertial orbit estimation of an object, either known or unknown, adaptable to a network of low-cost observation satellites. The observation satellites would only require a monocular camera for line of sight measurements. Using the line of sight measurements of each observer, a pair of orthogonal geometric planes that intersect both the observation satellite and the target are created. The intersection of the two planes in the inertial frame defines the new measurement model that is implemented with multiple observation nodes. Total system observability is analyzed and the instantaneous (per node) observability …
Dynamic Modeling And Simulation Of A Power Plant Steam Condenser On The Siemens Sppa-T3000 Platform, Mohammad Odeh
Dynamic Modeling And Simulation Of A Power Plant Steam Condenser On The Siemens Sppa-T3000 Platform, Mohammad Odeh
Electronic Theses and Dissertations, 2020-
With rapidly increasing computational power, modeling and simulation of complex systems is gradually becoming the norm for evaluating and predicting performance. This research focuses on modeling and simulating thermodynamic behavior of condensers within Combined Cycle Power Plants. This is particularly useful for power generation companies as this allows a wide range of operating conditions to be simulated and characterized without risking damage or the need to shut down the power plant, all of which results in losing revenue in the process. Moreover, being able to observe the thermodynamic evolution of the system provides useful insight into efficiency and response to …
Operability And Wave Characterization Of Hydrogen And Oxygen Fed Rotating Detonation Rocket Engine, Robert Burke
Operability And Wave Characterization Of Hydrogen And Oxygen Fed Rotating Detonation Rocket Engine, Robert Burke
Electronic Theses and Dissertations, 2020-
Recently, novel experimental evidence of continuous rotating detonations for gaseous H2/O2 propellants with a rotating detonation rocket engine (RDRE) was attained on the 3-inch Air Force Research Laboratory (AFRL) Distribution A RDRE, with the fuel and oxidizer injectors modified for H2/O2 gas propellants. Evident in previous experiments, detonation instabilities arising from upstream deflagration, from recirculation zones, and from insufficient gas mixing challenged resolution of detonation wave behavior from back-end imaging with the available optical equipment. Images were often over-illuminated from both the high amount of deflagration in the plume and the higher density of detonation waves in the annulus coupled …
Development Of A Computationally Inexpensive Method Of Simulating Primary Droplet Breakup, Brendon A. Cavainolo
Development Of A Computationally Inexpensive Method Of Simulating Primary Droplet Breakup, Brendon A. Cavainolo
Honors Undergraduate Theses
Liquid droplet impingement on aircraft can be problematic as it leads to ice accretion. There have been many incidents of aircraft disasters involving ice accretion, such as American Eagle Flight 4184. Understanding liquid droplet impingement is critical in designing aircraft that can mitigate the damages caused by icing. However, the FAA's regulations are only specified for "Appendix C" droplets; thus, aircraft designs may not be safe when accounting for droplets such as Supercooled Large Droplets. The assumptions of many models, such as the Taylor-Analogy Breakup (TAB) model, are no longer accurate for Supercooled Large Droplets, and the physics of those …
Piezospectroscopic Sensing Systems - Multi-Scale And In-Situ Sensing Technology For Structural Integrity, Remelisa Esteves
Piezospectroscopic Sensing Systems - Multi-Scale And In-Situ Sensing Technology For Structural Integrity, Remelisa Esteves
Electronic Theses and Dissertations, 2020-
The aerospace industry relies on nondestructive evaluation (NDE) to ensure aircraft safety and will benefit from methods that allow for early damage detection. Photoluminescence piezospectroscopy (PS) has demonstrated stress and damage sensing of substrates when coupled with alpha-alumina nanoparticles in a polymer matrix applied as a sensor coating. Alpha phase alumina exhibits photoluminescent spectral emission lines (R-lines) that shift due to changes in the stress state of the alumina. The coatings' capability for sensing early subsurface damage suggests the potential for implementing stress sensing paint for integrity monitoring of aircraft structures. To achieve a viable stress sensing coating that can …
Mechanical Properties Of Boron Carbide (B4c), Ruslan Kuliiev
Mechanical Properties Of Boron Carbide (B4c), Ruslan Kuliiev
Electronic Theses and Dissertations, 2020-
Boron carbide (B4C) is one of the most important opaque boride ceramics that has high hardness and Young's modulus that along with low density lead to a significant resistance to ballistic impact and, thus, B4C is broadly used as a protective material. B4C has also high neutron capturing cross section; therefore, it is used as control rods and neutron absorption shielding in nuclear reactors. In this work thermal, electrical and mechanical properties of dense B4C ceramics (99%) sintered using Spark Plasma Sintering (SPS) were investigated. The Young's modulus of B4C measured by three different techniques – IE, RUS, and nanoindentation …
Efforts In Numerical Modeling Of Undulating Propulsion, George Loubimov
Efforts In Numerical Modeling Of Undulating Propulsion, George Loubimov
Electronic Theses and Dissertations, 2020-
Naval propulsion is a critical component for every vessel, and it is the subject of this thesis, specifically bio-inspired propulsion. Numerical modeling is used as a tool to understand the relationship between mechanical undulation and the hydrodynamic response. Through three stages, the research presented here examines and refines tools for understanding fundamentals of undulating propulsion. Those three objectives are: to verify and validate the proposed numerical models against existing experiments, establishing a baseline of fidelity; to examine the causal linkage between fluid-boundary interactions and undulating propulsion; and to create a moment based method for characterizing generalized undulating propulsive mechanisms. First, …
Design And Visual Servo Control Of A Mechanical Gripper For Autonomous Strawberry Harvesting, Jonah Mapes
Design And Visual Servo Control Of A Mechanical Gripper For Autonomous Strawberry Harvesting, Jonah Mapes
Electronic Theses and Dissertations, 2020-
With rising labor costs and high consumer demand, economic conditions are becoming increasingly favorable for mechanization in the strawberry industry. However, virtually all strawberry crops are still picked by hand because the harvesting process is very challenging to automate, and strawberries are susceptible to bruising. For these reasons, the development of a harvester which can avoid damaging the fruit is of interest. Conventional designs for robotic grippers are less than ideal, as precise positioning or force feedback capabilities are required to reduce the risk of bruising. As an alternative, a novel "camera-in-hand" gripper design is presented which effectively avoids bruising …
Hybrid Physics-Informed Neural Networks For Dynamical Systems, Renato Giorgiani Do Nascimento
Hybrid Physics-Informed Neural Networks For Dynamical Systems, Renato Giorgiani Do Nascimento
Electronic Theses and Dissertations, 2020-
Ordinary differential equations can describe many dynamic systems. When physics is well understood, the time-dependent responses are easily obtained numerically. The particular numerical method used for integration depends on the application. Unfortunately, when physics is not fully understood, the discrepancies between predictions and observed responses can be large and unacceptable. In this thesis, we show how to directly implement integration of ordinary differential equations through recurrent neural networks using Python. We leveraged modern machine learning frameworks, such as TensorFlow and Keras. Besides offering basic models capabilities (such as multilayer perceptrons and recurrent neural networks) and optimization methods, these frameworks offer …