Mechanical Engineering Commons^™

Heterogeneous Anisotropy Index And Scaling In Multiphase Random Polycrystals, Muhammad Ridwan Murshed

Theses and Dissertations

Under consideration is the finite-size scaling of elastic properties in single and two-phase random polycrystals with individual grains belonging to any crystal class (from cubic to triclinic). These polycrystals are generated by Voronoi tessellations with varying grain sizes and volume fractions. By employing variational principles in elasticity, we introduce the notion of a 'Heterogeneous Anisotropy Index' and investigate its role in the scaling of elastic properties at finite mesoscales. The index turns out to be a function of 43 variables, 21 independent components for each phase and the volume fraction of either phase. Furthermore, the relationship between Heterogeneous Anisotropy Index …

Electrochemical Detection Of Low-Concentration Lead (Ii) Ions From Water, Mohmmad Rizwen Ur Rahman

Theses and Dissertations

The aim of this study was to develop an electrochemical sensor for speedy, selective and sensitive detection of lead ion (Pb2+) using graphene oxide and pyrrole nanocomposite. Different combinations of graphene oxide and pyrrole in layers and mixtures were tested for the finest sensitive detection of lead ion (Pb2+). Reduced graphene oxide and polypyrrole (rGO-PPY as layer) nanocomposite modified screen printed electrode (SPE) showed the best signal in response to the differential pulse anodic stripping voltammetry (DPASV) with a limit of detection to 5 ppb. The rGO-PPY modified electrode possessed a large effective surface area because of the unique 3D …

Pulsed Flow Jet Impingement Cooling: Evaluation Of Heat Transfer Performance, Michael Lee Hamman

Theses and Dissertations

This thesis presents findings from an experimental and numerical investigation into merits of pulse coolant flow as an improvement to impingement cooling. A series of simulations were conducted at Re=12k and 30k for frequencies up to 20Hz and amplitude ratios up to 70% of mean mass flow and standoff and nozzle spacing equal to three diameters. Square waveforms were found to degrade at low frequencies near 1Hz, rendering the use of square waveforms as an invalid mass flow specifications for inlet boundaries in computational predictions. The Power Consumption Ratio is introduced for comparing pulse and steady flow configuration’s energy consumption. …

Study Of Latent Heat Thermal Energy Storage Systems For Concentrated Solar Power Plants, Hermes Chirino

Theses and Dissertations

Concentrated Solar Power (CSP) using phase change material (PCM) as the storage medium in the Thermal Energy Storage (TES) system is a promising technology for large scale utilization of solar thermal energy because heat latent heat thermal energy storage (LHTES) systems can store more energy as the latent heat during the melting process.

This study analyzes the different dimensionless parameters from the 1-D transient enthalpy-based mathematical model used to simulate the heat transfer and flow within the LHTES system. These dimensionless parameters are varied and analyzed with the main objective of increasing thermal energy storage efficiency and exergy efficiency of …

Effect Of Processing Parameters On The Electrochemical Performance Of Forcespun Metal Oxide/Carbon Composite Fibers For Li-Ion Batteries, Howard A. Campos

Theses and Dissertations

Metal oxides have been gaining interest as electrode materials for rechargeable Li-ion batteries due to various properties including low cost, low toxicity, and high theoretical capacity. In this research work the effect of two different metal oxide/carbon fiber composites, Fe3O4/C and ZnO/C, on the electrochemical performance for Li-ion batteries will be explored. This is also the first time that results are reported, to the best of our knowledge, of these fiber composites through the Forcespinning ® method. Scanning electron microscopy (SEM), Energy-Dispersive X-ray Analysis (EDS), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and electrochemical analysis were used to investigate …

Design And Analysis Of Compressed Air Power Harvesting Systems, Zachary James Sadler

Theses and Dissertations

Procedure for site discovery, system design, and optimization of power harvesting systems is developed with an emphasis on application to air compressors. Limitations for the usage of infrared pyrometers is evaluated. A system of governing equations for thermoelectric generators is developed. A solution method for solving the system of equations is created in order to predict power output from the device. Payback analysis is proposed for determining economic viability. A genetic algorithm is used to optimize the power harvesting system payback with changing quantities and varieties of thermoelectric generators, as well as the back work put into cooling the thermoelectric …

Temporal Transformation Of Barrier Islands A Round Nakdong Estuary, Sukzun Youn

Theses and Dissertations

The Nakdong Estuary system near Busan, South Korea consists of dynamic shorelines characterized by morphological transformations that result from both natural disasters (typhoons and flooding) and construction projects (Nakdong Estuary Dam, gates in the West Nakdong River and Busan New-ports). This study aims to synthesize existing data for tides, waves, bathymetry and meteorological data obtained from a variety of institutions with the objectives of (1) identifying and ranking major factors that influence morphological transformations and (2) determining how these factors influence morphological change over time. These objectives were met by analyzing patterns of flow and sediment transport using Center Point …

Design Of Metal Oxides/Metal Sulfides For The Improvement Of Sodium Ion Batteries, David E. Flores

Theses and Dissertations

Herein, the improvement in performance for sodium ion batteries (NIBs) is discussed from available literature and work conducted in the laboratory setting to demonstrate the ability of sodium to perform in the world of energy storage. The reason that sodium is being explored as an alternative to Lithium in energy storage devices is because of the potential depletion of the lithium in the world causing lithium prices to surge. Researchers show that many Sn, Sb, Ge, and other composites perform well as anode materials within NIBs. The research conducted in the dissertation applies the Forcespinning method to produce fibers for …

Towards Green Building: Energy Efficient Roof System For Buildings, Dhruv Sangal

Theses and Dissertations

The present work focusses on investigating the thermal performance of different energy efficient roof systems for buildings for different climates. Buildings constitutes about 40 percent of total energy consumed by United States, and previous research shows that 20 percent of the building cooling load comes through ceiling of a building. Thus, it is important to analyze different energy efficient roof systems which can help in reducing building cooling and heating load. The present study focusses on three technologies – green roof, radiant barriers and photovoltaics. To analyze the performance of these systems, a detailed energy based mathematical model were developed …

Investigating The Influence Of Functional And Nonfunctional Requirements On Change And Change Propagation, Nathaniel Conde Voris

Theses and Dissertations

The research presented in this thesis investigates the nature of change and change propagation in requirement documents as they are influenced by requirement type, that is, “Functional” or “NonFunctional,” and how an understanding of these types may refine utilization of the Automated Requirement Change Propagation Prediction (ARCPP) tool when used by design teams. Functionality is determined by asking the question “Does the requirement prescribe something for the project to accomplish?” This question separates the requirements into their requisite types. Using the ARCPP, the relationship and propagation scores were determined for each requirement. Furthermore, the number of relationships were determined for …

Eigenblades: Application Of Computer Vision And Machine Learning For Mode Shape Identification, Alex W. La

Theses and Dissertations

On August 27, 2016, Southwest Airlines flight 3472 from New Orleans to Orlando had to perform an emergency landing when a fan blade separated from the engine hub and destroyed the cowling and punctured the fuselage. Initial findings from the metallurgical examination conducted in the National Transpiration Safety Board Materials Laboratory found that the fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. Fatigue is often cause by resonate vibrations. Modal analysis is a method that can model the natural frequencies and bending modes of turbomachinery blades. When performing modal analysis with finite …

A Comparison Between Self-Cleaning Properties Via Rolling Droplets And Condensation On Superhyrophobic Surfaces, David Leland Miller

Theses and Dissertations

Superhydrophobic (SH) surfaces are super water repellent surfaces on which a droplet of water will bead up like a marble and roll off the surface with minimal tilting of the surface. This is caused by the combination of a hydrophobic coating and a rough surface structure. To achieve thermodynamic stability, surface tension of the water pulls the droplet into this shape to minimize the contact area between the droplet and the surface. This creates a high contact angle (CA) between the droplet and the surface and a low sliding angle (SA) of which the droplet begins to roll off the …

Eigenblades: Application Of Computer Vision And Machine Learning For Mode Shape Identification, Alex W. La

Theses and Dissertations

On August 27, 2016, Southwest Airlines flight 3472 from New Orleans to Orlando had to perform an emergency landing when a fan blade separated from the engine hub and destroyed the cowling and punctured the fuselage. Initial findings from the metallurgical examination conducted in the National Transpiration Safety Board Materials Laboratory found that the fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. Fatigue is often cause by resonate vibrations. Modal analysis is a method that can model the natural frequencies and bending modes of turbomachinery blades. When performing modal analysis with finite …

An Obstacle Avoidance System For The Visually Impaired Using 3-D Point Cloud Processing, Evan Justin Taylor

Theses and Dissertations

The long white cane offers many benefits for the blind and visually impaired. Still, many report being injured both indoors and outdoors while using the long white cane. One frequent cause of injury is due to the fact that the long white cane cannot detect obstacles above the waist of the user. This thesis presents a system that attempts to augment the capabilities of the long white cane by sensing the environment around the user, creating a map of obstacles within the environment, and providing simple haptic feedback to the user. The proposed augmented cane system uses the Asus Xtion …

Microstructural Evaluation Of Hydrogen Embrittlement And Successive Recovery In Advanced High Strength Steel, Quentin Scott Allen

Theses and Dissertations

Advanced high strength steels (AHSS) have high susceptibility to hydrogen embrittlement, and are often exposed to hydrogen environments in processing. In order to study the embrittlement and recovery of steel, tensile tests were conducted on two different types of AHSS over time after hydrogen charging. Concentration measurements and hydrogen microprinting were carried out at the same time steps to visualize the hydrogen behavior during recovery. The diffusible hydrogen concentration was found to decay exponentially, and equations were found for the two types of steel. Hydrogen concentration decay rates were calculated to be -0.355 /hr in TBF steel, and -0.225 /hr …

Design And Analysis Of Compressed Air Power Harvesting Systems, Zachary James Sadler

Theses and Dissertations

Procedure for site discovery, system design, and optimization of power harvesting systems is developed with an emphasis on application to air compressors. Limitations for the usage of infrared pyrometers is evaluated. A system of governing equations for thermoelectric generators is developed. A solution method for solving the system of equations is created in order to predict power output from the device. Payback analysis is proposed for determining economic viability. A genetic algorithm is used to optimize the power harvesting system payback with changing quantities and varieties of thermoelectric generators, as well as the back work put into cooling the thermoelectric …

Characterizing The Electromechanical Response Of Flexible Foam For Multifunctional Impact-Sensing Applications, Evan Troy Bird

Theses and Dissertations

Flexible foams have unique properties that make them well-suited to several engineering systems. They are often used in impact-related applications because of their superior energy absorption performance. Many multifunctional materials are also derived from flexible foams due to their high customizability, which allows them to satisfy a wide range of performance requirements. Though flexible foams have high potential in these and other classes of material applications, their success relies on the proper characterization of their complex behavior. This thesis promotes the application of flexible foams by characterizing their electromechanical response through both experimental and theoretical approaches. One study in this …

Developing New Classes Of Thick-Origami-Based Mechanisms: Conceal-And-Reveal Motion And Folding Printed Circuit Boards, Bryce Parker De Figueiredo

Theses and Dissertations

Origami-adapted mechanisms form the basis of an increasing number of engineered systems. As most of these systems require the use of non-paper materials, various methods for accommodating thickness have been developed. These methods have opened new avenues for origami-based design. This work introduces approaches for the design of two new classes of thick-origami systems and demonstrates the approaches in hardware. One type of system, called "conceal-and-reveal,'' is introduced, and a method of designing these mechanisms is developed. Techniques are also developed for designing folding printed circuit boards which are fabricated from a single sheet of material. This enables areas of …

Hydrodynamic And Thermal Effects Of Sub-Critical Heating On Superhydrophobic Surfaces And Microchannels, Adam M. Cowley

Theses and Dissertations

This dissertation focuses on the effects of heating on superhydrophobic (SHPo) surfaces. The work is divided into two main categories: heat transfer without mass transfer and heat transfer in conjunction with mass transfer. Numerical methods are used to explore the prior while experimental methods are utilized for the latter. The numerical work explores convective heat transfer in SHPo parallel plate microchannels and is separated into two stand-alone chapters that have been published archivally. The first considers surfaces with a rib/cavity structure and the second considers surfaces patterned with a square lattice of square posts. Laminar, fully developed, steady flow with …

Highly Compressible Origami Bellows For Harsh Environments, Jared J. Butler

Theses and Dissertations

The use of origami-based bellows is of interest in fields where traditional metal bellows are incapable of meeting compression, mass, or flexibility constraints. Metal bellows are often used in space applications but frequently complicate spacecraft design. Origami-based bellows capable of meeting design constraints while adequately shielding sensitive spacecraft parts may be advantageous to space mechanism design. The design and testing of a highly compressible origami bellows for harsh environments is described. Several origami patterns were evaluated and the Kresling fold pattern was designed to meet constraints and selected for use in the bellows design. Origami bellows were prototyped in five …

Considering Manufacturing In The Design Of Thick-Panel Origami Mechanisms, Erica Brunson Crampton

Theses and Dissertations

Origami has been investigated and demonstrated for engineering applications in recent years. Many techniques for accommodating the thickness of most engineering materials have been developed. In this work, tables comparing performance and manufacturing characteristics are presented. These tables can serve as useful design tools for engineers when selecting an appropriate thickness-accommodation technique for their application. The use of bent sheet metal for panels in thick-origami mechanisms shows promise as a panel design approach that mitigates several trade-offs between performance and manufacturing characteristics. A process is described and demonstrated that can be employed to use sheet metal in designs of origami-adapted …

Distribution Of Essential Tremor In The Degrees Of Freedom Of The Upper Limb, Adam Charles Pigg

Theses and Dissertations

This study seeks to understand upper limb tremor in subjects with essential tremor (ET). A thorough understanding of tremor distribution will allow for the more effective development of tremor suppression devices, which offer an alternative to current treatments. Previous studies primarily focused on tremor in the hand only. This study seeks to characterize the distribution of tremor throughout the upper limb.We measured tremor in 25 subjects diagnosed with ET using motion capture, which provided displacement information of the limb during multiple postural and kinetic tasks. Inverse kinematics allowed us to analyze the motion capture data in the 7 major degrees …

Distribution Of Essential Tremor In The Degrees Of Freedom Of The Upper Limb, Charles Charles Pigg

Theses and Dissertations

This study seeks to understand upper limb tremor in subjects with essential tremor (ET). A thorough understanding of tremor distribution will allow for the more effective development of tremor suppression devices, which offer an alternative to current treatments. Previous studies primarily focused on tremor in the hand only. This study seeks to characterize the distribution of tremor throughout the upper limb. We measured tremor in 25 subjects diagnosed with ET using motion capture, which provided 0displacement information of the limb during multiple postural and kinetic tasks. Inverse kinematics allowed us to analyze the motion capture data in the 7 major …

Design For Safety: Characterization Of Structural Impact On Lithium-Ion Batteries, Mehdi Gilaki

Theses and Dissertations

The goal of this research is to develop a framework for design for safety of battery modules used in EV/HEV applications. Such a framework can enhance the crash safety of lithium-ion batteries by investigating prevailing failure mechanisms such as thermal runaway. The problem involves different scales from module level to laminate level. The multi-scale nature of the problem makes the analysis computationally complex and expensive. Furthermore, because of the risk of explosion, a battery testing apparatus needs special safety provisions making it difficult to test charged and ready-to-use battery cells. In this study, we have numerically investigated feasibility of using …

Design And Development Of A Robot Guided Rehabilitation Scheme For Upper Extremity Rehabilitation, Md Assad-Uz-Zaman

Theses and Dissertations

To rehabilitate individuals with impaired upper-limb function, we have designed and developed a robot guided rehabilitation scheme. A humanoid robot, NAO was used for this purpose. NAO has 25 degrees of freedom. With its sensors and actuators, it can walk forward and backward, can sit down and stand up, can wave his hand, can speak to the audience, can feel the touch sensation, and can recognize the person he is meeting. All these qualities have made NAO a perfect coach to guide the subjects to perform rehabilitation exercises. To demonstrate rehabilitation exercises with NAO, a library of recommended rehabilitation exercises …

A Study Of Development Of A Micro Hydro Turbine System With A Rim Drive And Air Injection Treatment For Cavitation., Tomoki Sakamoto

Theses and Dissertations

This thesis presents the study of Kaplan hydro turbines system at a very low head and air injection treatment to reduce cavitation happening around a turbine. Regarding the study of Kaplan hydroturbine system, optimization of hydro turbine system with a rim generator to gain a better performance was conducted by CFD and experiment. E-Motors, the partner of this research, is developing an integrated design to simplify manufacturing and installation. The integrated design includes a rim in the outside of the turbine runner to house the electrical generator rotor, namely rim drive. This approach enables a compact and simple assembly without …

Characterization Of Lift And Drag On Two Dimensional Airfoils With And Without Sinusoidal Leading Edges, Gregorio I. Acosta

Theses and Dissertations

An experimental investigation was taken on a 63-021 NACA airfoil, to characterize lift and drag and how the effects of sinusoidal leading edges affect the aerodynamic properties. A theoretical model is also purposed by implementing a perturbation on thin-airfoil theory.

Two sets of airfoils were machined and tested inside a low-speed open circuit wind tunnel. Data from a pressure scanner and particle image velocity will give an insight of how the modified leading edges affect the aerodynamic properties. A Fourier series expansion was used to solve for the lifting-line model, by use of thin-airfoil theory and complex number theory.

An Array Of Circular Dielectrophoresis Traps To Separate And Charaterize Individual Microparticles From Population, Hwangjae Lee

Theses and Dissertations

Dielectrophoretic traps have been broadly studied in light of their many advantages of high controllability, ease of operation, and high efficiency. In the previous studies, however, it was challenging to count captured particles or required work to capture particles. In the thesis, an array of circular dielectrophoresis (DEP) traps was developed and tested to manipulate population of microparticles in single particle level. The circular DEP traps enable more precise control of the force field than conventionally used interdigitated electrodes due to its omnidirectional and symmetric properties. The location of the captured microparticle inside the trap was confirmed by both of …

Numerical Study Of Thermal Performance Improvement By Novel Structures In The Building Energy Storage Systems, Junling Xie

Theses and Dissertations

In this work, numerical studies were conducted to investigate the effectiveness of two fin-like novel structures used for heat-transfer enhancement in two building energy storage systems including thermal energy storage and battery energy storage.

Firstly, thin layer ring structure was numerically investigated for thermal performance improvement in the thermal energy storage. From the results obtained in this study, the area ratio can be increased by 4% when using the thin layer ring during the same time period. The thin layer ring structure can shorten ice formation period and increase its efficiency. Further study was conducted for the factorial analysis of …

Improving Crash Safety Of Jet Dragsters Through Modeling And Analysis, Paige Leigh Sanchez

Theses and Dissertations

The objective of this thesis was to analyze how additional foam implementation in a jet dragster driver’s compartment can improve driver safety in the case of an accident. This analysis was divided into two sections: a crash simulation analysis and a base excitation mass-spring-damper model analyzing foam behavior. The jet dragster crash simulation modeled, reflected a Larsen Motorsports jet dragster accident in 2011, where a dragster hit the wall at 270 mph between a 43 to 60 degree angle. A static structural simulation, using the dragster chassis, was modeled in ANSYS and several dynamic simulations at varying impact angles were …