Engineering Commons^™

Numerical Simulation Of Laser Induced Elastic Waves In Response To Short And Ultrashort Laser Pulses., Alireza Zarei

All Dissertations

In an era of intensified market competition, the demand for cost-effective, high-quality, high-performance, and reliable products continues to rise. Meeting this demand necessitates the mass production of premium products through the integration of cutting-edge technologies and advanced materials while ensuring their integrity and safety. In this context, Nondestructive Testing (NDT) techniques emerge as indispensable tools for guaranteeing the integrity, reliability, and safety of products across diverse industries.

Various NDT techniques, including ultrasonic testing, computed tomography, thermography, and acoustic emissions, have long served as cornerstones for inspecting materials and structures. Among these, ultrasonic testing stands out as the most prevalent method, …

Comparative Analysis Of The Effects Of Post Processing On The Flexural Fatigue Endurance Of Additively Manufactured Ti-6al-4v, Cristian Banuelos

Open Access Theses & Dissertations

This study delves into analyzing the effects of various machining techniques on the flexural fatigue life of Ti-6Al-4V L-PBF specimens. The fatigue life and fracture behavior of specimens subjected to milling, grinding, polishing, and abrasive media blasting were compared. The findings reveal significant differences in the fatigue resistance between machined and non-machined parts. This study contributes to the understanding of the effects of post-processing on the durability of L-PBF manufactured components, offering insights for enhancing their application in critical aerospace and biomedical applications.

Prediction Modeling Of Foreign Object Impact Debris On Aircraft Through Digital Engineering, Luis Eduardo Rodriguez

Open Access Theses & Dissertations

The contribution of the research made is derived into two sections. The first topic discusses the prediction modeling of Foreign Object debris (FOd) impact on aircraft structures through the use of digital engineering. The program used in this project is Ansys Explicit Dynamics to evaluate the stress and strain caused by the initial conditions of flight trajectory and impact created from FOd found inside of aircraft structures. The prediction modeling consists of creating a repetition of simulations with different FOds to evaluate the damage created to subsystems of the wing bay such as the fuel system and internal structures. The …

Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood

McKelvey School of Engineering Theses & Dissertations

This thesis explores the micromechanical environment induced when cyclically compressing hydrogels via finite element modeling and experimentally on the impact of loading on mesenchymal stem cells (MSCs) when encapsulated withing 3D hydrogel matrices. Degenerative joint diseases, characterized by cartilage degradation, present significant challenges due to cartilage's limited self-repair capacity. Innovative approaches, including stem cell-based therapies and engineered biomaterials, have emerged as promising strategies for cartilage repair and regeneration. This work specifically investigates the calibration of a bioreactor, the uniformity of load response across the hydrogel constructs via finite element modeling (FEM), and the stress response of MSCs subjected to various …

Deep Reinforcement Learning Of Variable Impedance Control For Object-Picking Tasks, Akshit Lunia

All Theses

The increasing deployment of robots in industries with varying tasks has accelerated the development of various control frameworks, enabling robots to replace humans in repetitive, exhaustive, and hazardous jobs. One critical aspect is the robots' interaction with their environment, particularly in unknown object-picking tasks, which involve intricate object weight estimations and calculations when lifting objects. In this study, a unique control framework is proposed to modulate the force exerted by a manipulator for lifting an unknown object, eliminating the need for feedback from a force/torque sensor. The framework utilizes a variable impedance controller to generate the required force, and an …

Blade Design And Validation Of Hydrokinetic Turbine To Harvest Water Current Energy, Setare Sadeqi

University of New Orleans Theses and Dissertations

The innovative aspect of this research lies in the careful integration of cutting-edge technologies throughout the entire process of designing, fabricating, and testing the carbon fiber propeller for the 3-bladed horizontal axis ocean current turbine (OCT). SolidWorks software played a pivotal role in the initial design phase, enabling a meticulous and precise modeling of the propeller's geometry. The utilization of SolidWorks allowed for a detailed exploration of various design parameters, ensuring that the propeller's structure and form were optimized for performance in ocean current conditions. Moving beyond the realm of virtual design, the choice of carbon fiber as the fabrication …

Towing Tank Trials Of Hydrokinetic Turbine Scale Model To Support Marine Energy System Verification, Shahab Rouhi

University of New Orleans Theses and Dissertations

In response to the escalating demand for sustainable energy solutions and the critical reevaluation of conventional fossil fuels due to environmental concerns, this dissertation embarks on a comprehensive exploration of hydrokinetic energy as a promising alternative. The study delves into the underexplored domain of hydrokinetic energy, leveraging innovative methodologies for effective utilization and harnessing, particularly through the development and investigation of hydrokinetic turbines.

In the realm of hydrokinetic energy conversion, our research has exclusively concentrated on horizontal-axis turbines, distinct from other turbine configurations. Noteworthy is the adaptation of a conventional horizontal-axis wind turbine for water currents, revealing enhanced performance through …

Investigation On The Effects Of Biofouling On The Boundary Layer, Adam N. Bacon

University of New Orleans Theses and Dissertations

This study is an investigation of the effect of biofouling on the boundary layer of a flat plate and a NACA 4-digit series foil. Three identical hydrofoils made of resin were placed in the Gulf of Mexico at Grand Isle, Louisiana, and observed and analyzed by marine biologists at the University of New Orleans for their species composition. The resulting biofouling that grew was primarily made up of barnacles and bryozoans. The foils were submerged in an open channel flume at zero incidence and subjected to a series of experiments whose arc-length Reynolds numbers ranged from approximately 13000 to 32000. …

Study Of Accidental Sliding-Mode Control, April Mary Miller

Theses and Dissertations

The objective of this paper is to examine the Quanser SRV-02 motor servo for the presence of an accidental sliding mode. The SRV-02 is used by undergraduate students to learn basic concepts in controls engineering and will display unexpected sliding mode behavior when its in the “out of box” configuration. To gain a strong background understanding in characteristics of sliding mode, a review of literature on sliding-mode control and sliding mode behavior is completed. Next, a theoretical analysis of the SRV-02 motor servo during the sliding mode is developed. An effort is made to find a Lyapunov function that proves …

Aerodynamic Design And Analysis Of A Modified 2006 Mazda Miata, William N. Recher

Honors College Theses

Aerodynamic forces developed by automobiles have destabilizing effects at high speed. These forces tend to skew toward a vehicle’s rear which can present safety concerns, especially for rear-wheel-drive automobiles like the Mazda Miata. To address oversteer and high-speed instability, a vehicle’s design can be tailored to bring about aerodynamic balance and improve traction. LiDAR was used to bring the physical automobile into the digital space. Then, a splitter and diffuser were added to reduce the magnitude of the destabilizing forces. Next, the size and shape of the rear-wing required to balance the vehicle was calculated using a combination of parameters …

Research On 3d Printing Resin Exposure Properties And Its Application On Centrifugal Microfluidic Platform Based On Fluorescence Detection, Zheng Qiao

LSU Doctoral Dissertations

This dissertation encapsulates significant advancements in the field of SLA 3D printing and centrifugal microfluidics. Central to the research is the development of a novel mathematical model for predicting trapped resin thickness in SLA 3D printing, a groundbreaking contribution that addresses a critical aspect of printing intricate structures. This model, the first to establish a mathematical relationship for resin thickness, is rooted in a comprehensive study of the resin curing process. The research leverages the concept of 'critical dosage' for resin curing, leading to a more refined and theoretically grounded approach for calculating curing thickness. Experimentation further validates the model, …

Redesign Of Robotic Walking Training Device To Involve Zero Gravity Capabilities And Daily Activities, Chad Ballard

Mechanical Engineering Theses

Many patients struggle with disabilities that hinder their ability to walk. This project aimed to create a leg assembly capable of variable gravity so that it could be combined with a Robotic Walking Training Device, and lead to better rehabilitation options for patients. This was accomplished by deriving equations of joint torque, creating circuit diagrams for Arduino systems, modeling leg assemblies in CAD, and finally combining it to create a working small-scale prototype. The result of the prototype testing showed accurate movement on each joint, especially the ankle and knee segments, to create virtual zero gravity. In addition to this, …

Benchmarking Of A Sco2 Heat Exchanger Flow Loop, David Velasco

Doctoral Dissertations and Master's Theses

Heat transfer of supercritical carbon dioxide (sCO2) was studied experimentally by commissioning a sCO2 flow loop featuring a horizontal tube-in-tube counterflow heat exchanger with a circular cross section. The main objective was to establish experimental heat transfer research capabilities for sCO2 at Embry-Riddle Aeronautical University’s (ERAU) Thermal Science Lab. sCO2 experiences a drastic change in thermophysical properties near its critical point that results in unique heat transfer characteristics. The high pressures at which sCO2 exists make the large gradients in thermophysical and transport properties difficult to study, experimentally and numerically. However, understanding the heat transfer characteristics and thermophysical behavior of …

A Study Of The Effect Of Preparation Parameters On The Mechanical Properties Of Freeze-Dried Gelatin-Elastin-Hyaluronate Scaffolds, Mansour Qamash

Master's Theses (2009 -)

This thesis is dedicated to a detailed study of changes in the properties of Gelatin-Elastin-Hyaluronate (GEH) tissue engineering scaffold resulting from changes in preparation parameters. More specifically, utilizing a combination of foaming and freeze-drying techniques, this research investigates the effects of different parameters, including agitation speed, duration time, and chilling temperature on the scaffold’s structural integrity, porosity, and mechanical properties. The methodology involves a carefully calibrated process in which the scaffold matrix is initially prepared by incorporating 8% gelatin, 2% elastin, and 0.5% hyaluronate (w/v) into a homogenous aqueous solution, followed by controlled agitation and subsequent freezing at designated temperatures. …

Investigating The Impacts Of Bin Variability On Particle Size Distributions In Multiphase Eulerian-Eulerian Simulations, Wilbert Alexander Cruz

Master's Theses (2009 -)

In this study, a 3D steady-state Eulerian-Eulerian simulation was developed to investigate flow performance in a dilute pneumatic conveying system. The investigation focused on two main objectives: (1) assessing the influence of bin selection on solution accuracy for representing the polydisperse mixture, and (2) exploring methods to simplify the modeling of polydisperse particles in the simulation by utilizing a mean diameter derived from the mixture’s particle size distribution. The system's geometry and initial boundary conditions featured a 10.6 m long, 150 mm diameter horizontal pipe with both gaseous and solid phases initially moving at 27 m/s . The steady-state simulation …

Thermo-Elasto-Plastic Stability Of Biaxially Loaded Hollow Rectangular Section Steel Beam-Columns With Applied Torsion, George Adomako Kumi

Civil & Environmental Engineering Theses & Dissertations

Presented herein is an experimental and theoretical study of biaxially loaded hollow rectangular section steel beam-columns with applied torsion at elevated temperatures. The theoretical analysis is based on a system of simultaneous materially nonlinear differential equations of equilibrium for which an iterative semi-analytic solution approach is formulated. Although the primary goal of this research is to study the influence of elevated temperatures on the steel member with the complex loading, rigorous analysis is also conducted of the member at ambient temperature for comparison. The experimental part of the study involves conducting tests on the members at both ambient and high …

Structural Characterization Of A Tritruss Module, Lauren M. Simmons

Mechanical & Aerospace Engineering Theses & Dissertations

The TriTruss is a novel structural module developed by researchers at NASA Langley Research Center (LaRC) that can be used in space to assemble large support structures for a variety of applications. One such application is the metering truss or primary mirror backbone support structure of an In-Space Assembled Telescope (iSAT). For the iSAT application, the TriTruss will be supporting mirror segments, payloads, and instruments, all of which require the TriTruss to have a high stiffness. Structural characterization from testing and analysis is needed to ensure the integrity of the struts that make up a TriTruss module is maintained when …

Application Of The Fokker-Planck Equation For Quantifying Initial Condition Uncertainty Of Reversible Dynamic Systems, Troy S. Newhart

Mechanical & Aerospace Engineering Theses & Dissertations

Characterizing the behavior of dynamic systems requires the inclusion of initial conditions to propagate behavior forward in time. More realistic representations of system behavior quantify uncertainty about the initial conditions to assess sensitivity, reliability, and other stochastic response parameters. In many engineering applications, the uncertain initial conditions may be unknown given a desired response. This research applies the Fokker-Planck equation to reversible dynamic systems of select multi-dimensional nonlinear differential equations as a means for predicting the uncertainty about initial conditions. An alternating directions implicit numerical scheme is used to numerically solve the Fokker-Planck equation for both forward and reversed equations …

Technical Evaluation Of Floating Offshore Wind Plants And Installation Operations, Cengizhan Cengiz

Masters Theses

Offshore wind energy is witnessing remarkable growth, driven by the global shift towards sustainable and renewable energy sources. A pivotal innovation in this domain is floating offshore wind technology, which represents a transformative opportunity in harnessing wind energy from deep waters, where conventional fixed-bottom offshore wind systems face limitations due to depth constraints and escalating costs. In light of regional commitments to lower carbon emissions in energy generation, the accessibility of deep-water zones, rich in offshore wind resources, becomes increasingly critical. Despite the promising prospects, the floating offshore wind turbine (FOWT) developments present intricate challenges encompassing design, installation, and operational …

Comparison Of Conventional And Adaptive Acoustic Beamforming Algorithms Using A Tetrahedral Microphone Array In Noisy Environments, Megan Brittany Ewers

Dissertations and Theses

In situ acoustic measurements are often plagued by interfering sound sources that occur within the measurement environment. Both adaptive and conventional beamforming algorithms, when applied to the outputs of a microphone array arranged in a tetrahedral geometry, are able to capture sound sources in desired directions and reject sound from unwanted directions. Adaptive algorithms may be able to measure a desired sound source with greater spatial precision, but require more calculations and, therefore, computational power. A conventional frequency-domain phase-shift algorithm and a modified adaptive frequency-domain Minimum Variance Distortionless Response (MVDR) algorithm were applied to simulated and recorded signals from a …

Atomistic Insights Into The Mechanisms Of Ultrasonic Bonding, Milad Khajehvand

Engineering Ph.D. Theses

This thesis research uses a combination of computational and experimental approaches to provide atomistic insights into the mechanisms of ultrasonic bonding (UB), a family of solid-state metal-metal joining techniques, including ultrasonic wire bonding, ultrasonic flip-chip bonding, ultrasonic additive manufacturing, and ultrasonic spot welding. The work investigates the atomic-scale contact formation (i.e., the so-called Jump-to-Contact (JC) mechanism) between the UB counterparts, generation of a network of dislocations (i.e., one-dimensional crystallographic defects) at their interface, and the evolution of the network when the interface is under ultrasonic vibration. In particular, the thesis delivers invaluable insights on the mechanisms for contact formation, bond …

Efficacy Of Passive Ventilation With High Exhaust Demands: A Case Study Of Cal Poly Sst, Siddarth Bokka

Construction Management

The Simpson Strong Tie Demonstration Laboratory serves as a multipurpose space allowing students at the College of Architecture and Environmental Design at California Polytechnic State University to build full scale construction projects. The building features a material storage area, a high bay for construction of full-scale projects, and a mezzanine level that houses digital fabrication equipment. However, the building was never designed to house the specific equipment currently installed on the mezzanine and ventilate the exhaust fumes from them. Rather, the building relies on passive natural ventilation that is likely ineffective at properly exhausting hazardous fumes, resulting in complaints from …

Quantum-Powered Battery Scheduling In Modern Distribution Grids, Diba Ehsani

Electronic Theses and Dissertations

The rising need for exploiting a novel and evolved computation is an increasing concern in the power distribution system to address the exponential growth of distribution-connected devices. Scheduling numerous battery energy storage systems in an optimal way is one of the emerging challenges that will be more noticeable as the number of batteries, including residential, community, and vehicle batteries, increases in the grid. This thesis focuses on this topic and offers a necessary component in building the quantum-compatible distribution system of the future. Using a constrained quadratic model (CQM) on D-Wave’s hybrid solver as well as a binary quadratic model …

Finite Element Analysis Of Thermal-Mechanical Instabilities In Nonmetallic Friction Composite Material, Joseph-Shaahu Shaahu

Electronic Theses and Dissertations

Thermal-mechanical instability (TMI) has been a research topic of interest as it focuses a lot on transportation systems. Thermal-mechanical instability was first noticed in railway and experimentally studied with a pin-to-pin or pin-to-surface setup of sliding contact. The topic has been extended into brakes and clutches which are two of the most common sliding systems most susceptible to thermal buckling and thermoelastic instability (TEI), where thermal buckling and thermoelastic instability are two sub-categories of thermal-mechanical instability. Thermal-mechanical instability is an ongoing research to better understand the phenomenon and the limits at which such instability occurs. This work delved into the …

Finite Element Analysis Of The Bearing Component Of Total Ankle Replacement Implants During The Stance Phase Of Gait, Timothy S. Jain

Master's Theses

Total ankle replacement (TAR) implants are an effective option to restore the range of motion of the ankle joint for arthritic patients. An effective tool for analyzing these implants’ mechanical performance and longevity in-silico is finite element analysis (FEA). ABAQUS FEA was used to statically analyze the von Mises stress and contact pressure on the articulating surface of the bearing component in two newly installed fixed-bearing total ankle replacement implants (the Wright Medical INBONE II and the Exactech Vantage). This bearing component rotates on the talar component to induce primary ankle joint motion of plantarflexion and dorsiflexion. The stress response …

A Study On High-Frequency Bending Fatigue, Microhardness, Tensile Strength, And Microstructure Of Parts Made Using Atomic Diffusion Additive Manufacturing (Adam) And Additive Friction Stir Deposition (Afsd), Hamed Ghadimi

LSU Doctoral Dissertations

This dissertation reports the findings of several studies on the mechanical and microstructural properties of parts made using atomic diffusion additive manufacturing (ADAM) and additive friction stir deposition (AFSD). The design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in Chapter 1. The design was optimized based on the finite element analysis and analytical solution. The stress–life (S–N) curve is obtained for Inconel alloy 718. Chapter 2 presents the findings of ultrasonic bending-fatigue and tensile tests carried out on the ADAM test specimens. The S-N curves were created in the very high-cycle fatigue regime. …

Steminism: Analyzing Factors That Improve Retention Of Women In Stem, Kira Carter, Jane Kelley, Jason Vasser-Elong, Rc Patterson

Dissertations

Our co-authored research ‘Steminism: Analyzing Factors That Improve Retention for Women as STEM Majors’ analyzed factors that contributed to the retention of women in science, technology, engineering, and mathematics (STEM) programs at Missouri University of Science & Technology (Missouri S&T). Women make up half of the US population, and while careers in (STEM) are an integral part of the US economy, women are underrepresented in these career fields. The purpose of our dissertation is to address the underrepresentation of women in STEM majors. Our methodology included homogeneous sampling to collect qualitative data. More specifically, we consulted with academic advisors and …

Modeling Thermosyphon And Heat Pipe Performance For Mold Cooling Applications, Dwaipayan Sarkar

Electronic Thesis and Dissertation Repository

Thermosyphons are enhanced heat transfer devices that can continuously transfer very large amounts of heat rapidly over long distances with small temperature differences. The high heat transfer rate is achieved through simultaneous boiling and condensation of the working fluid and the continuous heat transfer is achieved through recirculation of the working fluid in its liquid and vapor phase. A potentially important application of the thermosyphons has been towards reducing the cycle times of the mold cooling processes which would provide economic incentives to the automotive industry.

Different operational and geometrical parameters such as the input heating power, fill ratio (FR), …

Analyses For Assessing The Centreline Translation, Asymmetrical Wind-Field, And Velocity Fluctuations Of Tornado Vortices, Niall C. Bannigan

Electronic Thesis and Dissertation Repository

Tornadoes present an ever-increasing threat to communities worldwide, especially those with geographic conditions that place them in the path of several tornadoes annually. These conditions are likely to be exacerbated by ongoing trends in the climate. As such, it is necessary to move towards experimental and numerical tornado-like vortex studies that allow for more advanced simulation methods. Novel techniques for tracking and analysing tornado vortices simulated at high spatial and temporal resolution are presented herein. Significant wandering of the tornado's position and large peaks in the velocity field can be captured, demonstrating tangential gusting at more than 1.5 times the …

Containerization Of Seafarers In The International Shipping Industry: Contemporary Seamanship, Maritime Social Infrastructures, And Mobility Politics Of Global Logistics, Liang Wu

Dissertations, Theses, and Capstone Projects

This dissertation discusses the mobility politics of container shipping and argues that technological development, political-economic order, and social infrastructure co-produce one another. Containerization, the use of standardized containers to carry cargo across modes of transportation that is said to have revolutionized and globalized international trade since the late 1950s, has served to expand and extend the power of international coalitions of states and corporations to control the movements of commodities (shipments) and labor (seafarers). The advent and development of containerization was driven by a sociotechnical imaginary and international social contract of seamless shipping and cargo flows. In practice, this liberal, …