Digital Commons Network^™

Design And Structural Analysis Of Morphing Wings, Nicholas Fernandez

Electronic Theses and Dissertations

Many natural flyers and marine swimmers can morph their wings during a number of unsteady maneuverings. With such wing morphing they are able to control the unsteady aerodynamic forces. A number of man-made flyers, such as unmanned aerial vehicles and micro air vehicles, fly in comparable Reynolds number range, but they are yet to acquire similar morphing capabilities as natural flyers or swimmers. Moreover, the knowledge of fluid structural interaction (FSI) of such morphing wings is not well developed. Hence there is a need to investigate the FSI of morphing wings. In this thesis, a morphing wing was designed and …

Multiphase Flow Modeling Of Molten Metal Atomization At High Gas Pressure, Kalpana Hanthanan Arachchilage

Electronic Theses and Dissertations

The high-pressure gas atomization is well known as one of the best powder manufacturing processes due to its controllability over powder size distribution. However, with the continuous improvement of new alloys, optimizing the operating parameters to maximize the yield is costly and time-consuming. Therefore, it is essential to understand the high-pressure gas atomization process and the effects of different operational parameters on the powder size distribution. Two-phase numerical simulations are performed to capture the interfacial dynamic during the atomization process and to obtain the effects of gas pressure, melt flow rate, and thermophysical properties of atomizing gas and the molten …

Computational Fluid Dynamics Investigation Of A Novel Hybrid Comprehensive Stage Ii Operation For Single Ventricle Palliation, Marwan Hameed

Electronic Theses and Dissertations

Hypoplastic left heart syndrome (HLHS) is a type of heart defect where the left ventricle is underdeveloped or not developed, resulting in only a single functioning right ventricle. Approximately 7.5% of patients with congenital heart disease are born with a single ventricle (SV) which is accompanied by a spectrum of other malformations such as atrophied ascending aorta, atrial septal defects, and ventricular septal defects (VSD). The existing three-hybrid staged surgical approach serving as a palliative treatment for this anomaly entails multiple complications and achieves a survival rate of only 50%. To reduce the trauma associated with the second stage of …

Probing The Influence Of Cx43 And Glucose On Endothelial Biomechanics, Md Mydul Islam

Electronic Theses and Dissertations

Endothelial cells (ECs) form the innermost layer of all vasculature and constantly receive both biochemical and biomechanical signals, yielding a plethora of biomechanical responses. In response to various biochemical or biomechanical cues, ECs have been documented to generate biomechanical responses such as tractions and intercellular stresses between the cell and substrate and between adjacent cells in a confluent monolayer, respectively. Thus far, the ability of endothelial tight junctions and adherens junctions to transmit intercellular stresses has been actively investigated, but the role of gap junctions is currently unknown. In addition, there is no report of the independent influence of hyperglycemia …

Shock Tube Investigations Of Novel Combustion Environments Towards A Carbon-Neutral Future, Samuel Barak

Electronic Theses and Dissertations

Supercritical carbon dioxide (sCO2) cycles are being investigated for the future of power generation. These cycles will contribute to a carbon-neutral future to combat the effects of climate change. These direct-fired closed cycles will produce power without adding significant pollutants to the atmosphere. For these cycles to be efficient, they will need to operate at significantly higher pressures (e.g., 300 atm for Allam Cycle) than existing systems (typically less than 40 atm). There is limited knowledge on combustion at these pressures or at the high dilution of carbon dioxide. Nominal fuel choices for gas turbines include natural gas and syngas …

Fundamental Characteristics Of Supercritical Co2 Combustion, Raghu Veera Manikantachari Kancherla

Electronic Theses and Dissertations

The direct-fired supercritical CO2 (sCO2) cycle is conceptually superior to many of the trending energy production technologies due to their remarkably promising efficiency, environmental friendliness and cost. The accurate simulation of this combustion is very important because the operating conditions are very challenging to its experimentation. Hence, the current work focuses on identifying various thermal, transport, chemical kinetic models, investigating various fundamental characteristics and verifying the validity of important underlying modeling assumptions in focus to supercritical CO2 combustion. In the current work, various thermal and transport property models are identified based on accuracy, computational cost and ease of implementation for …

Linear Systems With Integral Constraints On Transient Step-Response, Bilal Salih

Electronic Theses and Dissertations

The topic of shaping and controlling transient responses of dynamic systems has important applications. Achieving a desired transient response is an essential design requirement for many control system. In this research, we discuss the impact on the transient response of linear systems when it is subjected to a set of integral constraints. The investigation is generalized in a theoretical framework. Formulation of three types of integral constraints is first discussed. The underlying goal of the problem is to shape the step response to generate a specific type of transient response which in turn satisfies the desired integral constraints. The problem …

Integration Of Computational Fluid Dynamics And Machine Learning For Modeling Scaffold Pore Structure For Tissue Engineering, Amir Rouhollahi

Electronic Theses and Dissertations

Freeze-casting is a popular method to produce biomaterial scaffolds with highly porous structures. Three approaches are developed to predict the scaffold pore structure as function of experimental conditions including mold geometry, material and thermal boundary conditions. First, a mathematical model integrating Computational Fluid Dynamics (CFD) with Population Balance Model is developed to predict average pore size (APS) of 3D porous chitosan alginate scaffolds and to assess the influence of the geometrical parameters of mold on scaffold pore structure. The model predicted the crystallization pattern and APS for scaffolds cast in different diameter molds and filled to different heights. The predicted …

Multi-Scale Modeling Of Viscoelastic Thin-Ply Composites, Milinda Madhusanka Yapa Yapa Hamillage

Electronic Theses and Dissertations

Thin ply composites have been under the microscope of researchers for around two decades since Kawabe introduced the thin ply technology, in the Industrial Technology Center in Fukui, Japan. With the advancement of the technological aspects of manufacturing carbon fiber composites the tow spreading has improved so much as to reduce the thickness of a conventional ply up to even six-fold. Over the years carbon fiber composites have gained interest in space structures for reinforcement purposes in antennas, as structural elements that store strain energy and support the deployment of deployable structures, and in reflector concepts. Now thin-ply composites are …

Shape Recovery Behavior Of Carbon Nanopaper Shape Memory Polymer Composite, Veli Bugra Ozdemir

Electronic Theses and Dissertations

This thesis presents analytical, experimental and modeling studies of the shape recovery behavior of electrically activated Carbon Nanopaper (CNP) Shape Memory Polymer (SMP)composite. The composite structure studied consists of a CNP layer sandwiched by two SMP layers where the CNP layer acts as a flexible electrical heater when a voltage difference is applied. The behavior of CNP/SMP composite presents a coupled electrical - thermal - structural problem. The governing equations for the multiphysics behavior are derived. Derived parameters as a result of multiphysics analysis and effects of these parameters on the shape recovery behavior are investigated. The mechanical properties of …

Blade Design And Analysis Of Horizontal-Axis Wind Turbine: Cfd And Experimental Investigation Of Blades Design, Relwinde Fabrice Zongo

Electronic Theses and Dissertations

The present thesis focuses on the investigations of the computational fluid dynamics analysis and the experimental study of small scales Horizontal Axis Wind Turbine (HAWT) blades. The initial steps are taken; in the process of this research were the selection of the airfoil type to be used in each blade design and the creation of a blade design with high efficiency operating in a low wind speed zone. For the mentioned blade design process, the following airfoils were selected respectively NACA 0010, NACA 0012, NACA 1412, NACA 2412, NACA 2414, NACA 4412 and NACA 6412. This selection intends to provide …

Development Of A Neural Network-Based Object Detection For Multirotor Target Tracking, Spencer Harwood

Electronic Theses and Dissertations

Unmanned aerial vehicles (UAVs) have, for the past few decades, seen an increased popularity in industry and research centres. Despite this intense utilization by both markets there exists an active demand for the development of autonomous guidance, navigation, and control strategies. One need relates to the achievement of a high level of autonomy to identify and track a target object. An elective technique for this set of tasks is neural networks. In the development and study of these networks there is a distinct lack of substantive validation techniques to qualify network performances when implemented in a multirotor UAV. This thesis …

Quantifying The Performance Of The Protodune Single Phase Neutrino Detector Using Computational Fluid Dynamics, Dillon Pedersen

Electronic Theses and Dissertations

The goal of this research is to provide scientifically-valid computationally generated data of the flow, thermal, and impurity data of the ProtoDUNE single phase detector. Results are compared and validated against an actual detector that is currently being utilized to collect temperature and impurity data. This research will investigate the flows inside these detection chambers using computational fluid dynamics to find approximate solutions to the governing equations of fluid mechanics. Impurity and flow data will allow researchers to determine if results collected are being obstructed by high levels of impurity. Novel approaches have been developed to strike a balance between …

Flexure Properties Of 3d Printed Nylon Carbon Fiber Composite And Stiffness Of 3d Printed Modified Cuttlefish Bone Structure, Shashikanth Reddy

Electronic Theses and Dissertations

Flexure strength is one of the most widely used mechanical properties to represent the mechanical behavior of the composite. Fiber reinforcements increase the flexure strength of a composite. Specifically, there has been tremendous growth in the use of Carbon Fiber (CF) in the manufacturing industry due to its significant contribution to enhance the mechanical properties of a composite. Fiber orientation, void content, bonding between the layers (delamination), and fiber distribution are some of the factors that affect the flexure strength of a reinforced composite. The laminate (composite with reinforced layers) composites, has been a focus of study by researchers from …

3d Printed Bioreactor With Optimized Stimulations For Ex-Vivo Bone Tissue Culture, Anirban Chakraborty

Electronic Theses and Dissertations

Motivation: Long term tissue survivability ex-vivo can greatly facilitate research on the influence of external stimulus (loading, radiation, microgravity) on the tissue, including mechanisms of disease transmission and subsequent drug discoveries. Bioreactors (used to culture living tissue ex-vivo) can be a valuable tool to study cell activity during physiological processes by mimicking their in-vivo native 3D environment.
Objective Statement: We have developed a compact, 3D printed bioreactor equipped with both continuous flow-perfusion and dynamic mechanical-loading stimulations, capable of maintaining ex-vivo viability of swine cancellous bone cores over a long period. Qualitative study of the cultured cores (in terms of …

Mechanical Properties Of 3d Printed Acrylonitrile Styrene Acrylate, William Cahyadi

Electronic Theses and Dissertations

Several studies have been conducted on FDM 3d printed materials such as PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene), however, not for ASA (Acrylonitrile Styrene Acrylate). The use of ASA has been increasing due to its resistance to UV, heat, and some chemicals. The resistance to UV prevents the material from degrading its material properties in common outdoor conditions, whereas resistance to heat and oil prevents the material from discoloration. This combination of effects allows designers to use ASA in outdoor applications, however, material properties for ASA in the FDM 3d printing manufacturing process are not well defined. It …

Analysis Of Natural Convection Flow In A Detector Using Computational Fluid Dynamics, Weston Christensen

Electronic Theses and Dissertations

The goal of this research was to simulate the flow, temperature, and impurity concentration within the Deep Underground Neutrino Experiment (DUNE) Single Phase Far Detector using a commercially available computational fluid dynamics (CFD) solver. DUNE is a research collaborative investigating properties of neutrinos in an effort to better understand the origins of matter and behavior of subatomic particles. The Far Detector is a geometrically complex neutrino detector containing: anode plane arrays and cathode plane arrays which induce an electric field within the detection region that causes electrons to drift to the sensing equipment, field cage planes to enclose the neutrino …

Applied Deep Learning In Orthopaedics, William Stewart Burton Ii

Electronic Theses and Dissertations

The reemergence of deep learning in recent years has led to its successful application in a wide variety of fields. As a subfield of machine learning, deep learning offers an array of powerful algorithms for data-driven applications. Orthopaedics stands to benefit from the potential of deep learning for advancements in the field. This thesis investigated applications of deep learning for the field of orthopaedics through the development of three distinct projects.

First, algorithms were developed for the automatic segmentation of the structures in the knee from MRI. The resulting algorithms can be used to accurately segment full MRI scans in …

Cavitation And Heat Transfer Over Micro Pin Fins, Arash Nayebzadeh

Electronic Theses and Dissertations

With the dramatic increase in the usage of compact yet more powerful electronic devices, advanced cooling technologies are required to maintain delicate electronic components below their maximum allowable temperatures and prevent them from failure. One solution is to use innovative pin finned heat sinks. This research is centered on the evaluation of hydrodynamic cavitation properties downstream pin fins and extended toward single-phase heat transfer enhancement of array of pin fins in microchannel. In this work, transparent micro-devices capable of local wall temperature measurements were micro fabricated and tested. Various experimental methods, numerical modeling and advanced data processing techniques are presented. …

Controlled Bubble Dynamics Inside Micropillar Arrays, Faraz Khalil Arya

Electronic Theses and Dissertations

Bubble dynamics inside micro domains was manipulated and used to pump liquid. Micropillars were formed inside two 1.5 mm wide and 220 µm high microchannels with a length of 23 mm. One microchannel had three arrays of micropillars with diameters of 40 µm and the other had a single array of micropillars with diameters of 30 µm. An array of five 200 µm by 200 µm heaters was deposited inside these micropillar arrays and was used to control bubble size and trajectory. A sequential power switching of the heaters was used to pump liquid in a desired direction with a …

A Study Of Organo-Phosphorous Simulants Thermal Destruction Using Shock Tube/Laser Diagnostics Techniques And Chemical Kinetics Modeling, Sneha Neupane

Electronic Theses and Dissertations

High-fidelity chemical kinetic models are critical in predictive modeling during design and optimization of next generation energy systems. Shock tube provides an ideal tool to investigate high-temperature chemical kinetics. Non-intrusive laser absorption diagnostics provide in-situ measurements of quantitative, time-resolved species concentration data in this complex chemically reacting system. In this work, shock tube and laser absorption spectroscopy were utilized to measure species concentration time-histories during pyrolysis and oxidation of organo-phosphorous compounds (OPCs). The experiments data obtained were used as benchmark to develop an improved kinetic model of OPCs combustion. Interest in combustion chemistry of OPCs is associated to their use …

Dynamics Of A Perfectly Premixed Jet Flame Exhibiting Self-Excited High-Frequency, Transverse Thermoacoustic Instabilities, Lucky Tran

Electronic Theses and Dissertations

This work is an investigation of the behavior of a premixed turbulent jet flame in a cylindrical dump combustor. The degeneracy of the simple configuration in this study lends itself for a detailed study of inherent mechanisms of a self-excited thermoacoustic instability in isolation from system coupling effects, enabling detailed numerical simulations to be carried out to supplement experimental findings. Tests were done at a nominal pressure of 8 bar and inlet temperature around 450 ˚C. Self-excited large eddy simulations were also carried out in OpenFOAM, using a b-Ξ flame-wrinkling model to model the combustion process. Eigenfrequency analysis in COMSOL …

Compressible Turbulent Reactions For Hypersonic Propulsion Applications, Jonathan Sosa

Electronic Theses and Dissertations

This work presents the first measurement of turbulent burning velocities of a highly-turbulent compressible standing flame induced by shock-driven turbulence in a Turbulent Shock Tube. High-speed schlieren, chemiluminescence, PIV, and dynamic pressure measurements are made to quantify flame-turbulence interaction for high levels of turbulence at elevated temperatures and pressure. Distributions of turbulent velocities, vorticity and turbulent strain are provided for regions ahead and behind the standing flame. The turbulent flame speed is directly measured for the high-Mach standing turbulent flame. From measurements of the flame turbulent speed and turbulent Mach number, transition into a non-linear compressibility regime at turbulent Mach …

Empirical Evaluation Of Ground, Ceiling, And Wall Effect For Small-Scale Rotorcraft, Stephen Austin Conyers

Electronic Theses and Dissertations

Ground effect refers to the apparent increase in lift that an aircraft experiences when it flies close to the ground. For helicopters, this effect has been modeled since the 1950's based on the work of Cheeseman and Bennett, perhaps the most common method for predicting hover performance due to ground effect. This model, however, is based on assumptions that are often not realistic for small-scale rotorcraft because it was developed specifically for conventional helicopters. It is clear that the Cheeseman-Bennett model cannot be applied to today's multirotor UAVs. Experimental findings suggest that some of the conventional thinking surrounding helicopters cannot …

Knee Balance Assessment During Cementation Is Detrimental To Initial Tka Tibial Tray Fixation, Yashar Ali Behnam

Electronic Theses and Dissertations

Despite recent advancements in implant design and cement technique, aseptic tibial loosening remains the primary cause of revision after cemented total knee arthroplasty (TKA) [1]. While the mechanisms of tibial loosening are multifactorial, previous research has shown that third-generation cement techniques, including the use of jet lavage and cement pressurization, can reduce contamination of the implant surface by lipids endogenous to the surrounding cancellous bone and thereby enhance fixation strength between the implant and bone [2]. The purpose of this thesis is to understand the role contaminating lipids play in the mechanism of aseptic loosening and to perform a cadaveric …

Coupling Numerical Analysis Of Vibration And Thermal Buckling Of An Automotive Brake Disc, Joseph-Shaahu Shaahu

Electronic Theses and Dissertations

An engaged brake system generates high temperature gradients in the brake rotor and brake pads. This high temperature gradient in turn induces thermal buckling. During high speed rotation, vibration is likely to occur in the system. In terms of a brake disc vibration will occur when there is a misalignment of the brake disc or thermoelastic instability (hot spot) forms on the brake rotor. Coupled and uncoupled problems of thermal buckling and vibration of a brake disc are analyzed and presented using finite element analysis in this paper. Thermal buckling depends on the direction of the high temperature gradient. Having …

Side-To-Side Comparison Of Total Shoulder Arthroplasty And Intact Function In Individuals, Sarah Rose Walden

Electronic Theses and Dissertations

Total Shoulder Arthroplasty (TSA) is a surgery which replaces the shoulder joint, or the interface between the humerus and the scapula glenoid. To test TSA success, most prior research compares patients with TSA to healthy controls. However, the shoulder anthropometry, motion, and musculature of individuals varies widely across the population making it important to assess TSA performance in individuals. The overall goal of this study is to determine if patients with one of two TSA implant designs on one side achieve the same range of motion as their intact side, and if so to find if they compensate using increased …

Analytical Modeling And Life Cycle Assessment Of A Solar Powered Vapor Absorption Cooling System, Harold A. Walters

Electronic Theses and Dissertations

Vapor absorption cooling systems (VACS) offer an environmentally friendly alternative to the standard vapor compression cooling systems (VCCS) for cooling homes, businesses, factories, and other buildings. VACS use low-grade thermal energy to achieve a cooling effect and require minimal electrical input for the liquid solution pump used for circulation within the system. The thermal energy which powers these systems can be provided through several means; one popular form is through the use of solar thermal collectors. This paper provides a process for determining the overall size and configuration of the VACS depending upon the operating conditions of selected components. A …

Molecular Dynamics Study Of Sintering Behavior Of Single-Crystal, Bimetallic Core/Shell Alloy, And Intermetallic Alloy Nanoparticles, Jungmin Jeon

Electronic Theses and Dissertations

There has been rapidly growing interest in the sintering process of nanoparticles (NPs) among academia and modern industry due to their promising applications in additive manufacturing (AM) based on the overall improved properties at nanoscale. In the past decade a lot of experimental and computational work has been conducted to study the sintering process of powder materials. However there is still a significant knowledge gap in a fundamental understanding of the thermodynamics and nanostructural evolution of NPs undergoing additive manufacturing. This thesis aims to gain fundamental insights into melting behavior of different materials including single-crystal bimetallic core/shell alloy and intermetallic …

Modeling And Transient Simulation Of A Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000, Jonathan Mcconnell

Electronic Theses and Dissertations

The focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids have brought forth a necessity to gain a comprehensive understanding of transient behavior within an HRSG in order to efficiently manage …