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Development And Validation Of An Absorption Sensor For Time-Resolved Measurements Of Co And Co2, Kyle Thurmond
Development And Validation Of An Absorption Sensor For Time-Resolved Measurements Of Co And Co2, Kyle Thurmond
HIM 1990-2015
A sensor was developed for simultaneous measurements of carbon monoxide and carbon dioxide fluctuations in internal combustion engine exhaust gases. This sensor utilizes low-cost and compact LEDs that emit in the 3-5[micro]m wavelength range which are more appropriate for practical applications than the more traditionally used lasers. An affordable, fast response sensor that can measure these gases has broad application that can lead to more efficient, fuel flexible engines and regulations of harmful emissions. LEDs have a more spectrally broad and diverging emission than lasers which presented many design challenges. The optical design software ZEMAX was utilized to overcome these …
Fracture Toughness Of A Hyperelastic Material During Surgical Cutting, Kevin Smith
Fracture Toughness Of A Hyperelastic Material During Surgical Cutting, Kevin Smith
HIM 1990-2015
Despite being one of the most important organs of vertebrates, the material properties of skin are also one of the most poorly understood. In the field of designing medical devices and surgical tools there are significant advantages to having a model that describes the interaction of forces between a blade tip and skin during surgical cutting. In general, skin can best be described as a composite layer consisting of a viscoelastic dermis with interwoven collagen and elastin fibers beneath a superficial epidermis. The purpose of this research is to study the fracture toughness of porcine skin during practical cutting applications, …
Characterization Of Polyetherimide Under Static, Dynamic, And Multiple Impact Conditions, Bryan Zuanetti
Characterization Of Polyetherimide Under Static, Dynamic, And Multiple Impact Conditions, Bryan Zuanetti
HIM 1990-2015
The application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In this thesis, the mechanical response of polyethermide (PEI) is characterized under quasi-static, high strain rate, and multiple impact conditions. Standard tension, torsion, and compression experiments are performed …
A Simplified Approach To Thermomechanical Fatigue And Application To V-Shaped Notches, Thomas Bouchenot
A Simplified Approach To Thermomechanical Fatigue And Application To V-Shaped Notches, Thomas Bouchenot
HIM 1990-2015
A vast array of high value parts in land- and air-based turbomachinery are subjected to non-isothermal cycling in the presence of mechanical loading. Crack initiation, growth and eventual failure more significantly reduce life in these components compared to isothermal conditions. More accurate simulation of the stress and strain evolution at critical locations of components, as well as test specimens, can lead to a more accurate prediction of remaining life to a structural integrity specialists. The focus of this thesis is to characterize the effects of thermomechanical fatigue (TMF) on generic turbomachinery alloy. An expression that can be used to estimate …
Microscopic Surface Textures Created By Interfacial Flow Instabilities, Jing Gu
Microscopic Surface Textures Created By Interfacial Flow Instabilities, Jing Gu
HIM 1990-2015
In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with various weight concentrations in acetone. In order to study the morphology of the porous structure of PVDF films, wet deposition samples were fabricated by spin coating or near-field …
A Computed Tomography-Based Model Of The Infant Hip Anatomy For Dynamic Finite Element Analysis Of Hip Dysplasia Biomechanics, Kyle Snethen
A Computed Tomography-Based Model Of The Infant Hip Anatomy For Dynamic Finite Element Analysis Of Hip Dysplasia Biomechanics, Kyle Snethen
HIM 1990-2015
Newborns diagnosed with hip dysplasia face severe consequences when treatments fail. The Pavlik harness presents the most common worldwide treatment for correcting this medical hip abnormality in newborns, but becomes increasingly ineffective as subluxation increases. A dynamic finite element analysis on the hip joint would yield results that could provide insight to physicians as to how the Pavlik harness could be optimized to increase its success rate and develop patient-specific treatment plans. The study completes the first step in such an analysis by generating a three-dimensional model of an infant hip joint directly derived from computed tomography imaging in order …
Production, Control And Actuation Of Micron-Sized Particles In A Microfluidic T-Junction, James Wilson
Production, Control And Actuation Of Micron-Sized Particles In A Microfluidic T-Junction, James Wilson
HIM 1990-2015
This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micrometers], from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40°C-50°C. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at …
Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson
Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson
Electronic Theses and Dissertations
Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through …
Heat And Fluid Flow Characterization Of A Single-Hole-Per-Row Impingement Channel At Multiple Impingement Heights, Roberto Claretti
Heat And Fluid Flow Characterization Of A Single-Hole-Per-Row Impingement Channel At Multiple Impingement Heights, Roberto Claretti
Electronic Theses and Dissertations
The present work studies the relationship between target and sidewall surfaces of a multirow, narrow impingement channel at various jet heights with one impingement hole per row. Temperature sensitive paint and constant flux heaters are used to gather heat transfer data on the target and side walls. Jet-to-target distance is set to 1, 2, 3, 5, 7 and 9 jet diameters. The channel width is 4 jet diameters and the jet stream wise spacing is 5 jet diameters. All cases were run at Reynolds numbers ranging from 5,000 to 30,000. Pressure data is also gathered and used to calculate the …
Study Of Transport Phenomena In Carbon-Based Materials, Walid Aboelsoud
Study Of Transport Phenomena In Carbon-Based Materials, Walid Aboelsoud
Electronic Theses and Dissertations
In air-cooled heat exchangers, air-side thermal resistance is usually the largest compared to conduction and liquid-side thermal resistances. Thus, reducing the air-side thermal resistance with fin-like structures can greatly improve overall cooling performance. The performance of these structures is usually characterized by the rate of heat which can be transferred and the pumping power required. One promising solution is to use a high-thermal-conductivity material with a large surface per unit volume such as carbon foam. This study presents a method of utilizing V-shape corrugated carbon foam. The air-side heat transfer coefficient and the pressure drop across the foam have been …
Generation And Printing Of Strictly Monodisperse Droplets, Hongxu Duan
Generation And Printing Of Strictly Monodisperse Droplets, Hongxu Duan
Electronic Theses and Dissertations
Highly monodisperse droplets are attracting great attention both in many research areas, such as aerosol science, combustion, and Nano-manufacturing. This thesis invents a novel aerosol generator: “Periodic Electro Hydro-dynamic Chopper” termed as “PEHD chopper”, and develops a new method to directly print micro-patterns with monodisperse droplets. The principle of the PEHD chopper is to use the fringe electric field of a capacitor to introduce controlled perturbation on a liquid jet. We first derived the governing equations for a circular inviscid liquid jet under transverse electric fields. The electric fields were obtained through numerical simulation. Then we used a high speed …
A Linear Multiplexed Electrospray Thin Film Deposition System, Brandon Lojewski
A Linear Multiplexed Electrospray Thin Film Deposition System, Brandon Lojewski
Electronic Theses and Dissertations
Liquid spray is essential to industries requiring processes such as spray coating, spray drying, spray pyrolysis, or spray cooling. This thesis reports the design, fabrication, and characterization of a thin film deposition system which utilizes a linear multiplexed electrospray (LINES) atomizer. First, a thorough review of the advantages and limitations of prior multiplexed electrospray systems leads to discussion of the design rationale for this work. Next, the line of charge model was extended to prescribe the operating conditions for the experiments and to estimate the spray profile. The spray profile was then simulated using a Lagrangian model and solved using …
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones
Electronic Theses and Dissertations
Particulate composites are widely used in many aerospace and military applications as energetic materials, armor materials or coatings and their behavior under dynamic loads have gained increasing significance. The addition of modifiers such as alumina nanoparticles generally facilitates the improvement of the mechanical strength to density ratio due to high specific area and particle rigidity. This allows for sufficient particlematrix bonding and therefore improved stiffness and load transfer in the composite. Photo-luminescent α-alumina nanoparticles when embedded in an epoxy matrix allow for the added benefit of in situ measurements at low strain rates to provide stress-sensitive information using the particle …
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
Electronic Theses and Dissertations
In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to …
Electrohydrodynamic Manipulation Of Liquid Droplet Emulsions In A Microfluidic Channel, Jonathan Wehking
Electrohydrodynamic Manipulation Of Liquid Droplet Emulsions In A Microfluidic Channel, Jonathan Wehking
Electronic Theses and Dissertations
This work specifically aims to provide a fundamental framework, with some experimental validation, for understanding droplet emulsion dynamics in a microfluidic channel with an applied electric field. Electrification of fluids can result in several different modes of electrohydrodynamics (EHD). Several studies to date have provided theoretical, experimental, and numerical results for stationary droplet deformations and some flowing droplet configurations, but none have reported a method by which droplets of different diameters can be separated, binned and routed through the use of electric fields. It is therefore the goal of this work to fill that void and report a comprehensive understanding …
Biomechanical Factors Influencing Treatment Of Developmental Dysplasia Of The Hip (Ddh) With The Pavlik Harness, Orlando Ardila
Biomechanical Factors Influencing Treatment Of Developmental Dysplasia Of The Hip (Ddh) With The Pavlik Harness, Orlando Ardila
Electronic Theses and Dissertations
Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the acetabular labrum, using the medical segmentation software Mimics. The lower extremity was modeled by three segments: thigh, leg, and foot. The mass and the location of the …
The Characterization Of The Effects Of Stress Concentrations On The Mechanical Behavior Of A Micronic Woven Wire Mesh, Steven Kraft
The Characterization Of The Effects Of Stress Concentrations On The Mechanical Behavior Of A Micronic Woven Wire Mesh, Steven Kraft
Electronic Theses and Dissertations
Woven structures are steadily emerging as excellent reinforcing components in dualphase composite materials subjected to multiaxial loads, thermal shock, and aggressive reactants in the environment. Metallic woven wire mesh materials display good ductility and relatively high specific strength and specific resilience. While use of this class of materials is rapidly expanding, significant gaps in mechanical behavior classification remain. This thesis works to address the mechanics of material knowledge gap that exists for characterizing the behavior of a metallic woven structure, composed of stainless steel wires on the order of 25 microns in diameter, and subjected to various loading conditions and …
Investigation Of Multiscale Fluid Structure Interaction Modeling Of Flow In Arterial Systems, Sebastian Sotelo
Investigation Of Multiscale Fluid Structure Interaction Modeling Of Flow In Arterial Systems, Sebastian Sotelo
Electronic Theses and Dissertations
The study of hemodynamic patterns in large blood vessels, such as the ascending aortic artery, brachiocephalic trunk, right carotid artery and right subclavian artery presents the challenging complexity of vessel wall compliance induced by the high levels of shear stress gradients and blood flow pulsatility. Accurate prediction of hemodynamics in such conditions requires a complete Fluid Structure Interaction (FSI) analysis that couples the fluid flow behavior throughout the cardiac cycle with the structural response of the vessel walls. This research focuses on the computational study of a Multiscale Fluid-Structure Interaction on the arterial wall by coupling Finite Volumes Method (FVM) …
Experimental And Numerical Investigation Of Aerodynamic Unsteadiness In A Gas Turbine Midframe, Matthew Golsen
Experimental And Numerical Investigation Of Aerodynamic Unsteadiness In A Gas Turbine Midframe, Matthew Golsen
Electronic Theses and Dissertations
As modern gas turbines implement more and more complex geometry to increase life and efficiency, attention to unsteady aerodynamic behavior becomes more important. Computational optimization schemes are contributing to advanced geometries in order to reduce aerodynamic losses and increase the life of components. These advanced geometries are less representative of cylinder and backward facing steps which have been used as analogous geometries for most aerodynamic unsteadiness research. One region which contains a high degree of flow unsteadiness and a direct influence on engine performance is that of the MidFrame. The MidFrame (or combustor-diffuser system) is the region encompassing the main …
On Radar Deception, As Motivation For Control Of Constrained Systems, Hadi Hajieghrary
On Radar Deception, As Motivation For Control Of Constrained Systems, Hadi Hajieghrary
Electronic Theses and Dissertations
This thesis studies the control algorithms used by a team of ECAVs (Electronic Combat Air Vehicle) to deceive a network of radars to detect a phantom track. Each ECAV has the electronic capability of intercepting the radar waves, and introducing an appropriate time delay before transmitting it back, and deceiving the radar into seeing a spurious target beyond its actual position. On the other hand, to avoid the errors and increase the reliability, have a complete coverage in various atmosphere conditions, and confronting the effort of the belligerent intruders to delude the sentinel and enter the area usually a network …
Thermomechanical Fatigue Life Prediction Of Notched 304 Stainless Steel, Justin Karl
Thermomechanical Fatigue Life Prediction Of Notched 304 Stainless Steel, Justin Karl
Electronic Theses and Dissertations
The behavior of materials as they are subjected to combined thermal and mechanical fatigue loads is an area of research that carries great significance in a number of engineering applications. Power generation, petrochemical, and aerospace industries operate machinery with expensive components that undergo repeated applications of force while simultaneously being exposed to variable temperature working fluids. A case of considerable importance is found in steam turbines, which subject blades to cyclic loads from rotation as well as the passing of heated gases. The complex strain and temperature histories from this type of operation, combined with the geometric profile of the …
Automated Hybrid Singularity Superposition And Anchored Grid Pattern Bem Algorithm For The Solution Of The Inverse Geometric Problem, Marcus Ni
Electronic Theses and Dissertations
A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of …
Transient Multi-Scale Computational Fluid Dynamics (Cfd) Model For Thrombus Tracking In An Assit Device Vascular Bed, Ruben Osorio
Transient Multi-Scale Computational Fluid Dynamics (Cfd) Model For Thrombus Tracking In An Assit Device Vascular Bed, Ruben Osorio
Electronic Theses and Dissertations
Heart failure occurs when the heart is not capable to pump blood at a sufficient rate to meet the demands of the body. Depending on the health of the heart, doctors may recommend a heart transplant, but finding a suitable donor is often a long duration process and the patient might be at an advance condition or the patient is not adequate for a heart transplant. In such cases Ventricular assist devices (VAD) are implemented. The purpose of a VAD is to aid the heart to pump the correct amount of blood, by doing so it relives the load that …
Planning And Control Of Swarm Motion As Continua, Hossein Rastgoftar
Planning And Control Of Swarm Motion As Continua, Hossein Rastgoftar
Electronic Theses and Dissertations
In this thesis, new algorithms for formation control of multi agent systems (MAS) based on continuum mechanics principles will be investigated. For this purpose agents of the MAS are treated as particles in a continuum, evolving in an n-D space, whose desired configuration is required to satisfy an admissible deformation function. Considered is a specific class of mappings that is called homogenous where the Jacobian of the mapping is only a function of time and is not spatially varying. The primary objectives of this thesis are to develop the necessary theory and its validation via simulation on a mobile-agent based …
Thermoacoustic Riemann Solver Finite Volume Method With Application To Turbulent Premixed Gas Turbine Combustion Instability, Perry Johnson
Thermoacoustic Riemann Solver Finite Volume Method With Application To Turbulent Premixed Gas Turbine Combustion Instability, Perry Johnson
Electronic Theses and Dissertations
This thesis describes the development, verification, and validation of a three dimensional time domain thermoacoustic solver. The purpose of the solver is to predict the frequencies, modeshapes, linear growth rates, and limit cycle amplitudes for combustion instability modes in gas turbine combustion chambers. The linearized Euler equations with nonlinear heat release source terms are solved using the finite volume method. The treatment of mean density gradients was found to be vital to the success of frequency and modeshape predictions due to the sharp density gradients that occur across deflagration waves. In order to treat mean density gradients with physical fidelity, …
Bio-Inspired, Varying Manifold Based Method With Enhanced Initial Guess Strategies For Single Vehicle's Optimal Trajectory Planning, Ni Li
Electronic Theses and Dissertations
Trajectory planning is important in many applications involving unmanned aerial vehicles, underwater vehicles, spacecraft, and industrial manipulators. It is still a challenging task to rapidly find an optimal trajectory while taking into account dynamic and environmental constraints. In this dissertation, a unified, varying manifold based optimal trajectory planning method inspired by several predator-prey relationships is investigated to tackle this challenging problem. Biological species, such as hoverflies, ants, and bats, have developed many efficient hunting strategies. It is hypothesized that these types of predators only move along paths in a carefully selected manifold based on the prey’s motion in some of …
Combustion Synthesis And Characterization Of Porous Niti Intermetallic For Structural Application, Jessica Vanterpool
Combustion Synthesis And Characterization Of Porous Niti Intermetallic For Structural Application, Jessica Vanterpool
Electronic Theses and Dissertations
This thesis describes experimental investigation of thermal and combustion phenomena as well as structure for self- propagating combustion synthesis of porous Ni - Ti intermetallic aimed for structural biomedical application. The control parameters for the porosity distribution have been investigated experimentally through varying the preheat temperature, initial porosity, initial elemental particle size, and applied pressure during the fabrication process. Ni and Ti elemental powders are mixed using a 1:1 ratio. The mixture is compressed using several different compression forces to produce cylindrical samples of 1.1 cm diameter and 2-3cm length, with initial porosity ranging from 30% to 40%. The samples …
Creep-Fatigue Crack Initiation And Propagation Of A Notched Stainless Steel, Scott Keller
Creep-Fatigue Crack Initiation And Propagation Of A Notched Stainless Steel, Scott Keller
Electronic Theses and Dissertations
Premature failures of vital gas turbine components, such as blades and vanes, have been the result of increasing demands of power generation facilities. As power needs fluctuate throughout the day, operators are quickly firing up gas turbines as a means of providing instant power. Traditionally, these engines run at constant operating conditions; however, contemporary operating conditions call for these engines to be applied on an “as necessary” basis. The result of the cyclic startup and shutdown of gas turbines has led to a phenomenon known as creep-fatigue (CF). A coupling of two primary failure mechanisms in gas turbines, CF conditions …
Experimental Investigation Of Breakup And Coalescence Characteristics Of A Hollow Cone Swirling Spray, Joshua Lee
Experimental Investigation Of Breakup And Coalescence Characteristics Of A Hollow Cone Swirling Spray, Joshua Lee
Electronic Theses and Dissertations
Atomization can be achieved by discharging liquid at relative high velocities into a slow moving environment (hydraulic nozzles) or by discharging liquid at low velocities into a fast moving gas flow (air-blast nozzles). These two types of injector nozzles are featured in majority of the industry applications such as power generation, food or pharmaceutical powder formation, spray painting, petroleum refining, and thermal sprays. The most common atomizer used in combustion engines is the pressure-swirl nozzle (Simplex nozzle) to obtain a homogenous mixture at different equivalence ratios. The experimental studies performed with pressure-swirl nozzles have reported contradictory results over the last …
Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres
Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres
Electronic Theses and Dissertations
Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy and have the potential to become a reliable renewable energy source that can be used on a large scale. SOFCs have 3 main components; the electrolyte, the anode, and the cathode. Typically, SOFCs work by reducing oxygen at the cathode into O2- ions which are then transported via the electrolyte to the anode to combine with a fuel such as hydrogen to produce electricity. Research into better materials and manufacturing methods is necessary to reduce costs and improve efficiency to make the technology commercially viable. The …