Mechanical Engineering Commons^™

Raman Spectroscopy Of The Skeleton Of The Coral Acropora Cervicornis, Zachary C. Shepard

Honors Undergraduate Theses

Coral reefs are an important element of marine ecosystem that are critical to maintain a healthy environment. Unfortunately, in recent years coral reefs are doing poorly and many in parts of the ocean are simply dying. Therefore, study of coral’s structural response to external loads could answer what will happen with their structures, while they exhibit different types of loading. Therefore, the proposition of using in-situ micro-Raman spectroscopy to study skeletons of Acropora cervicornis was used. Coral skeleton samples I subjected to mechanical loading studied their vibrational properties by exciting the material with 532nm visible light. A uniaxial compressive load …

Optimal Sintering Temperature Of Ceria-Doped Scandia Stabilized Zirconia For Use In Solid Oxide Fuel Cells, Amanda K. Assuncao

Honors Undergraduate Theses

Carbon emissions are known to cause decay of the Ozone layer in addition to creating pollutant, poisonous air. This has become a growing concern among scientists and engineers across the globe; if this issue is not addressed, it is likely that the Earth will suffer catastrophic consequences. One of the main culprits of these harmful carbon emissions is fuel combustion. Between vehicles, power plants, airplanes, and ships, the world consumes an extraordinary amount of oil and fuel which all contributes to the emissions problem. Therefore, it is crucial to develop alternative energy sources that minimize the impact on the environment. …

Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb

Honors Undergraduate Theses

To confirm computer simulations and Computational Fluid Dynamics (CFD) analysis, benchtop experiments are needed with a fluid that mimics blood and its viscoelastic properties. Blood is challenging to use as a working fluid in a laboratory setting because of health and safety concerns. Therefore, a blood analogue is necessary to perform benchtop experiments. Viscosity is an important property of fluids for modeling and experiments. Blood is a shear thinning fluid, so 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, …

Ignition Studies Of Oxy-Syngas/Co2 Mixtures Using Shock Tube For Cleaner Combustion Engines, Samuel Barak

Electronic Theses and Dissertations

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the …

Characterization, Classification, And Genesis Of Seismocardiographic Signals, Amirtaha Taebi

Electronic Theses and Dissertations

Seismocardiographic (SCG) signals are the acoustic and vibration induced by cardiac activity measured non-invasively at the chest surface. These signals may offer a method for diagnosing and monitoring heart function. Successful classification of SCG signals in health and disease depends on accurate signal characterization and feature extraction. In this study, SCG signal features were extracted in the time, frequency, and time-frequency domains. Different methods for estimating time-frequency features of SCG were investigated. Results suggested that the polynomial chirplet transform outperformed wavelet and short time Fourier transforms. Many factors may contribute to increasing intrasubject SCG variability including subject posture and respiratory …

Characterization Of Anisotropic Mechanical Performance Of As-Built Additively Manufactured Metals, Sanna Siddiqui

Electronic Theses and Dissertations

Additive manufacturing (AM) technologies use a 3D Computer Aided Design (CAD) model to develop a component through a deposition and fusion layer process, allowing for rapid design and geometric flexibility of metal components, for use in the aerospace, energy and biomedical industries. Challenges exist with additive manufacturing that limits its replacement of conventional manufacturing techniques, most especially a comprehensive understanding of the anisotropic behavior of these materials and how it is reflected in observed tensile, torsional and fatigue mechanical responses. As such, there is a need to understand how the build orientation of as-built additively manufactured metals, affects mechanical performance …

Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon

Electronic Theses and Dissertations

Laser additive manufacturing (LAM) is an emerging technology capable of fabricating complex geometries not possibly made by investment casting methods for gas turbine applications. LAM techniques consist of building parts in a layer-by-layer process by selectively melting metal powders. In the present study, a mock leading edge segment of a turbine blade fabricated by LAM of Inconel 718 powders is investigated. For this particular design, the traditional showerhead film cooling holes have been replaced by two strips containing engineered-porous regions with the purpose of simulating the effect of transpiration cooling. Transpiration cooling has been considered a promising external convective cooling …

Hosting Capacity Optimization In Modern Distribution Grids, Mansoor T. Alturki

Electronic Theses and Dissertations

The availability of distributed renewable energy resources and the anticipated increase in new types of loads are changing the way electricity is being produced and supplied to consumers. This shift is moving away from a network delivering power solely from centralized power plants towards a decentralized network which supplements its power production by incorporating local distributed generators (DGs). However, the increased integration of DGs into existing distribution networks is impacting their behavior in terms of voltage profile, reliability, and power quality. To determine the maximum amount of DG that distribution grids can accommodate the concept of hosting capacity is introduced. …

Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues

Electronic Theses and Dissertations

In this research, a computational system was designed to analyze and optimize the layout of wind farms under variable operational conditions. At first, a wind turbine computational fluid dynamic (CFD) model was developed covering the near wake. The near wake flow field was validated against near wake velocity data from the MEXICO experiment. The CFD simulation demonstrated that the tip speed ratio and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. The CFD model was extended to cover the far wake, aiming to become a computational tool …

Lower Back Biomechanics At Non-Chronic Stage Of Low Back Pain, Iman Shojaei

Theses and Dissertations--Biomedical Engineering

Prior studies have reported differences in lower back biomechanics during activities of daily living between individuals with and without chronic low back pain (LBP). Nevertheless, the literature on lower back biomechanics of patients with non-chronic LBP is scant. Therefore, the objective of this study, as the first step towards future prospective studies, was to investigate the lower back biomechanics in patients with non-chronic LBP. Case-control studies were conducted wherein measures of lumbo-pelvic coordination during bending and return tasks as well as measures of mechanical demand on the lower back during lifting tasks in the sagittal plane were investigated between patients …

Assessing The Spatial Accuracy And Precision Of Lidar For Remote Sensing In Agriculture, Surya Saket Dasika

Theses and Dissertations--Biosystems and Agricultural Engineering

The objective of this whole study was to evaluate a LiDAR sensor for high-resolution remote sensing in agriculture. A linear motion system was developed to precisely control the dynamics of LiDAR sensor in effort to remove uncertainty in the LiDAR position/velocity while under motion. A user control interface was developed to operate the system under different velocity profiles and log LiDAR data synchronous to the motion of the system. The LiDAR was then validated using multiple test targets with five different velocity profiles to determine the effect of sensor velocity and height above a target on measurement error. The results …

Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill

Theses and Dissertations--Mechanical and Aerospace Engineering

The effects of system pressure on the performance stability of flow-through capacitive deionization (CDI) cells was investigated. Initial data showed that the highly porous carbon electrodes possessed air/oxygen in the micropores, and the increased system pressure boosts the gases solubility in saline solution and carries them out of the cell in the effluent. Upon applying a potential difference to the electrodes, capacitive-based ion adsorption occurs in competition with faradaic reactions that consume oxygen. Through the addition of backpressure, the rate of degradation decreases, allowing the cell to maintain its salt adsorption capacity (SAC) longer. The removal of oxygen from the …

Characterization Of The Shape Memory Behavior Of High Strength Nitihfpd Shape Memory Alloys, Guher P. Toker

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf alloys have emerged as potential materials for applications requiring high transformation temperatures (> 100 °C) with high strength and work output. Although they have high transformation temperatures, their low damping capacity, brittleness and poor superelastic responses (of Ti-rich NiTiHf) impedes their wider usage in many industrial applications. In this study, the quaternary alloying element of Pd has been added to NiTiHf alloys to improve and tailor their shape memory behavior,. NiTiHfPd alloys were systematically examined regarding the composition and heat treatments effects.

Effects of substituting Hf with Ti on the shape memory behavior of NiTHfPd alloys were investigated. There …

Regression Analysis Of Factors Impacting Problem Solving Engagement Within Lean Systems Implementation, David M. Parsley Ii

Theses and Dissertations--Mechanical and Aerospace Engineering

Organizations around the world have attempted to implement the concepts of the Toyota Production System (TPS), commonly referred to as Lean, with limited sustainable success. The central principles of TPS, continuous improvement and respect for people, are grounded in the Japanese values of Monozukuri and Hitozukuri. Monozukuri deals with creating or making a product, while Hitozukuri conveys the idea of developing people through learning. In order for organizations to adopt these values they must have a system that engages employees at all levels in applying problem solving to improve their work. This research uses organizational assessments obtained from a variety …

Characterization Of Rotary Bell Atomizers Through Image Analysis Techniques, Jacob E. Wilson

Theses and Dissertations--Mechanical and Aerospace Engineering

Three methods were developed to better understand and characterize the near-field dynamic processes of rotary bell atomization. The methods were developed with the goal of possible integration into industry to identify equipment changes through changes in the primary atomization of the bell. The first technique utilized high-speed imaging to capture qualitative ligament breakup and, in combination with a developed image processing technique and PIV software, was able to gain statistical size and velocity information about both ligaments and droplets in the image data. A second technique, using an Nd:YAG laser with an optical filter, was used to capture size statistics …

Intermittency Effects On The Universality Of Local Dissipation Scales In Turbulent Boundary Layer Flows With And Without Free-Stream Turbulence, Sabah Falih Habeeb Alhamdi

Theses and Dissertations--Mechanical and Aerospace Engineering

Measurements of the small-scale dissipation statistics of turbulent boundary layer flows with and without free-stream turbulence are reported for Re_τ ≈ 1000 (Re_θ ≈ 2000). The scaling of the dissipation scale distribution is examined in these two boundary conditions of external wall-bounded flow.

Results demonstrated that the local large-scale Reynolds number based on the measured longitudinal integral length-scale fails to properly normalize the dissipation scale distribution near the wall in these two free-stream conditions, due to the imperfect characterization of the upper bound of the inertial cascade by the integral length-scale. When a length-scale based on Townsend's …

Laminar And Turbulent Study Of Combustion In Stratified Environments Using Laser Based Measurements, Stephen William Grib

Theses and Dissertations--Mechanical and Aerospace Engineering

Practical gas turbine engine combustors create extremely non-uniform flowfields, which are highly stratified making it imperative that similar environments are well understood. Laser diagnostics were utilized in a variety of stratified environments, which led to temperature or chemical composition gradients, to better understand autoignition, extinction, and flame stability behavior. This work ranged from laminar and steady flames to turbulent flame studies in which time resolved measurements were used.

Edge flames, formed in the presence of species stratification, were studied by first developing a simple measurement technique which is capable of estimating an important quantity for edge flames, the advective heat …

Scale Models Of Acoustic Scattering Problems Including Barriers And Sound Absorption, Nan Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

Scale modeling has been commonly used for architectural acoustics but use in other noise control areas is nominal. Acoustic scale modeling theory is first reviewed and then feasibility for small-scale applications, such as is common in the electronics industry, is investigated. Three application cases are used to examine the viability. In the first example, a scale model is used to determine the insertion loss of a rectangular barrier. In the second example, the transmission loss through parallel tubes drilled through a cylinder is measured and results are compared to a 2.85 times scale model with good agreement. The third example …

NoX Formation In Light-Hydrocarbon, Premixed Flames, Robert T. Hughes

Theses and Dissertations--Mechanical and Aerospace Engineering

This study explores the reactions and related species of NO_x pollutants in methane flames in order to understand their production and consumption during the combustion process. To do this, several analytical simulations were run to explore the behavior of nitrogen species in the pre-flame, post- flame, and reaction layer regions. The results were then analyzed in order to identify all "steady-state" species in the flame as well as the determine all the unnecessary reactions and species that are not required to meet a defined accuracy. The reductions were then applied and proven to be viable.

Numerical And Experimental Techniques For Assessing The Acoustic Performance Of Duct Systems Above The Plane Wave Cutoff Frequency, Kangping Ruan

Theses and Dissertations--Mechanical and Aerospace Engineering

This research deals with determining the acoustic attenuation of heating, ventilation, and air conditioning (HVAC) ductwork. A finite element approach was developed for calculating insertion loss and breakout transmission loss. Procedures for simulating the source and receiving rooms were developed and the effect of structureborne flanking was included. Simulation results have been compared with measurements from the literature and the agreement is very good. With a good model in place, the work was extended in three ways. 1) Since measurements on full-scale equipment are difficult, scale modeling rules were developed and validated. 2) Two different numerical approaches were developed for …

Characterization Of Methane-Air Diffusion Flames For Flame Synthesis Application Through Optical Diagnostics, Zhaojin Diao

Theses and Dissertations--Mechanical and Aerospace Engineering

Flame synthesis is a growing field of research aiming at forming new materials and coatings through injection of seed materials into a flame. Accurate prediction of the thermal structure of these flames requires detailed information on the radiative properties and a thorough understanding of the governing combustion processes. The objective of this work is to establish a basic optical diagnostic characterization of different methane-air diffusion flames of different complexity. The basic principles are developed and demonstrated at a rotational symmetric co-flow burner and finally applied to a burner consisting of six clustered microflames which is designed for future flame synthesis …

Bayesian-Integrated System Dynamics Modelling For Production Line Risk Assessment, Sudhir Punyamurthula

Theses and Dissertations--Mechanical and Aerospace Engineering

Companies, across the globe are concerned with risks that impair their ability to produce quality products at a low cost and deliver them to customers on time. Risk assessment, comprising of both external and internal elements, prepares companies to identify and manage the risks affecting them. Although both external/supply chain and internal/production line risk assessments are necessary, internal risk assessment is often ignored. Internal risk assessment helps companies recognize vulnerable sections of production operations and provide opportunities for risk mitigation.

In this research, a novel production line risk assessment methodology is proposed. Traditional simulation techniques fail to capture the complex …

The Kentucky Re-Entry Universal Payload System (Krups): Sub-Orbital Flights, James Devin Sparks

Theses and Dissertations--Mechanical and Aerospace Engineering

The Kentucky Re-entry Universal Payload System (KRUPS) is an adaptable testbed for atmosphere entry science experiments, with an initial application to thermal protection systems (TPS). Because of the uniqueness of atmospheric entry conditions that ground testing is unable to replicate, scientists principally rely on numerical models for predicting entry conditions. The KRUPS spacecraft, developed at the University of Kentucky, provides an inexpensive means of obtaining validation data to verify and improve these models.

To increase the technology readiness level (TRL) of the spacecraft, two sub-orbital missions were developed. The first mission, KUDOS, launched August 13th, 2017 on a Terrier-Improved Malamute …

Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen

Theses and Dissertations--Mechanical and Aerospace Engineering

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and …

Design And Analysis Of A 3d-Printed, Thermoplastic Elastomer (Tpe) Spring Element For Use In Corrective Hand Orthotics, Kevin Thomas Richardson

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis proposes an algorithm that determine the geometry of 3D-printed, custom-designed spring element bands made of thermoplastic elastomer (TPE) for use in a wearable orthotic device to aid in the physical therapy of a human hand exhibiting spasticity after stroke. Each finger of the hand is modeled as a mechanical system consisting of a triple-rod pendulum with nonlinear stiffness at each joint and forces applied at the attachment point of each flexor muscle. The system is assumed quasi-static, which leads to a torque balance between the flexor tendons in the hand, joint stiffness and the design force applied to …

Multiphase Interaction In Low Density Volumetric Charring Ablators, Ali D. Omidy

Theses and Dissertations--Mechanical and Aerospace Engineering

The present thesis provides a description of historical and current modeling methods with recent discoveries within the ablation community. Several historical assumptions are challenged, namely the presence of water in Thermal Protection System (TPS) materials, presence of coking in TPS materials, non-uniform elemental production during pyrolysis reactions, and boundary layer gases, more specifically oxygen, interactions with the charred carbon interface.

The first topic assess the potential effect that water has when present within the ablator by examining the temperature prole histories of the recent flight case Mars Science Laboratory. The next topic uses experimental data to consider the instantaneous gas …

Attitude Control On So(3) With Piecewise Sinusoids, Shaoqian Wang

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation addresses rigid body attitude control with piecewise sinusoidal signals. We consider rigid-body attitude kinematics on SO(3) with a class of sinusoidal inputs. We present a new closed-form solution of the rotation matrix kinematics. The solution is analyzed and used to prove controllability. We then present kinematic-level orientation-feedback controllers for setpoint tracking and command following.

Next, we extend the sinusoidal kinematic-level control to the dynamic level. As a representative dynamic system, we consider a CubeSat with vibrating momentum actuators that are driven by small $\epsilon$-amplitude piecewise sinusoidal internal torques. The CubeSat kinetics are derived using Newton-Euler's equations of motion. …

Discrete-Time Adaptive Control Algorithms For Rejection Of Sinusoidal Disturbances, Mohammadreza Kamaldar

Theses and Dissertations--Mechanical and Aerospace Engineering

We present new adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. To achieve asymptotic disturbance rejection, adaptive control algorithms of this dissertation rely on limited or no system model information. These algorithms are developed in discrete time, meaning that the control computations use sampled-data measurements. We demonstrate the effectiveness of algorithms via analysis, numerical simulations, and experimental testings. We also present extensions to these algorithms that address systems with decentralized control architecture and systems subject to disturbances with unknown frequencies.

Fluid Dynamics Modeling And Sound Analysis Of A Bileaflet Mechanical Heart Valve, Fardin Khalili

Electronic Theses and Dissertations

Cardiovascular disease (CVD) is one of the main causes of death in the world. Some CVD involve severe heart valve disease that require valve replacement. There are more than 300,000 heart valves implanted worldwide, and about 85,000 heart valve replacements in the US. Approximately half of these valves are mechanical. Artificial valves may dysfunction leading to adverse hemodynamic conditions. Understanding the normal and abnormal valve function is important as it help improve valve designs. Modeling of heart valve hemodynamics using computational fluid dynamics (CFD) provides a comprehensive analysis of flow, which can potentially help explain clinical observations and support therapeutic …

Biomechanical Models Of Human Upper And Tracheal Airway Functionality, Don Nadun Kuruppumullage

Electronic Theses and Dissertations

The respiratory tract, in other words, the airway, is the primary airflow path for several physiological activities such as coughing, breathing, and sneezing. Diseases can impact airway functionality through various means including cancer of the head and neck, Neurological disorders such as Parkinson's disease, and sleep disorders and all of which are considered in this study. In this dissertation, numerical modeling techniques were used to simulate three distinct airway diseases: a weak cough leading to aspiration, upper airway patency in obstructive sleep apnea, and tongue cancer in swallow disorders. The work described in this dissertation, therefore, divided into three biomechanical …