Engineering Commons^™

Estimation Of Basic And Mission Benefit Of Condition-Based Maintenance Deployment In Hums Equipped Ah-64 Aircraft Using Nlp And Regression Analysis, Tanzina Zaman

Theses and Dissertations

Condition-based maintenance (CBM) is a maintenance practice that involves regular monitoring of the mechanical condition of components of interest, processing of information collected, and then decision-making to ensure both maximizing the time interval between repairs and minimizing the number of unscheduled failures. CBM also offers early detection of failure which can prevent major breakdowns and repairs. Vibration monitoring is one of the effective techniques for condition monitoring. Health and Usage Monitoring System (HUMS) is a powerful tool for aviation industry which monitors health status and trending data. Vibration Monitoring Unit (VMU) and Modernized Signal Processing Unit (MSPU) are two forms …

Investigation And Development Of Friction Stir Welding Process For Unreinforced Polyphenylene Sulfide And Reinforced Polyetheretherketone, Hossain Ahmed

Theses and Dissertations

The joining of thermoplastics through welding, a specific form of fusion bonding, offers numerous advantages over mechanical joining. It eliminates the use of costly fasteners and has only a limited effect on the strength of the parts being joined since it does not require the introduction of holes and loading pins, and it does not create significant stress concentrations. A specific form of welding, Friction Stir Welding, was investigated for the creation of butt joints of unreinforced polyphenylene sulfide (PPS) and short carbon fiber reinforced polyetheretherketone (PEEK) plates. Friction stir welding requires a rotating pin, a shoulder arrangement, relative movement …

Solving Atomic Structures Using Statistical Mechanical Searches On X-Ray Scattering Derived Potential Energy Surfaces, Christopher James Wright

Theses and Dissertations

Engineering the next generation of materials, especially nanomaterials, requires a detailed understanding of the material’s underlying atomic structure. These structures give us better insight into structure-property relationships, allowing for property driven material design on the atomic level. Even more importantly, understanding structures in-situ will translate stimuli and responses on the macroscopic scale to changes on the nanoscale. Despite the importance of precise atomic structures for materials design, solving atomic structures is difficult both experimentally and computationally. Atomic pair distribution functions (PDFs) provide information on atomic structure, but the difficulty of extracting the PDF from x-ray total scattering measurements limits their …

Uncertainty Quantification In Computational Catalysis, Eric Alan Walker

Theses and Dissertations

This dissertation augments the field of computational catalysis with uncertainty quantification. An efficient tool to describe the energetics and structure of atomistic systems is density functional theory (DFT). DFT may be used to understand how catalysts work although DFT is inexact in nature due to approximations necessary for computational tractability. These approximations in DFT cause uncertainty in microkinetic model results for catalytic systems. Therefore, reliable model results gained from DFT include a quantification of uncertainty. The case study to examine a systematic framework for uncertainty quantification is water-gas shift (WGS CO+H2O⇌CO2+H2) reaction by Pt/TiO2 catalyst.

Uncertainties are represented with probabilities …

Life-Cycle Analysis Of A Cement Manufacturing Plant Co-Firing Hazardous Waste In The Usa, Stephen P. Holt

Theses and Dissertations

The purpose of this work was to determine the overall environmental impacts associated with the co-firing hazardous waste by burning in a cement kiln to replace the use of coal in the cement manufacturing process. This environmental assessment was conducted using LCA methodology. Understanding the environmental impacts associated with burning hazardous waste in a cement factory could help shape national environmental policy, regulations and the need for site specific human health risk assessments in the environmental regulatory permitting processes. Accordingly, the primary objective of this study was to evaluate the environmental impacts from the hazardous waste burning for energy recovery …

Methane Separation And Purification Via Pressure Swing Adsorption, Lutfi Erden

Theses and Dissertations

Investigations on alternative energy sources have gained increasing attention due to significant shortage in the fossil fuel reserves and increase on the usage of internal combustion engines. Natural gas which mainly consists of Methane has a significant role in short term solution of this issue. Although methane as a greenhouse gas is over 20 times more potent by weight than carbon dioxide, if released directly into the atmosphere, it is a valuable energy source. However, methane is not extracted % 100 pure from the source. Natural gas generally contains many other contaminants such as water, other hydrocarbons, Carbon dioxide, Nitrogen, …

Dosimetry, Activation, And Robotic Instrumentation Damage Modeling Of The Holtec Hi-Storm 100 Spent Nuclear Fuel System, C. Ryan Priest

Theses and Dissertations

The Holtec HI-STORM 100 spent fuel storage system is an intermediate storage mechanism for SNF assemblies. Long term licensing and storage requires consideration of material degradation of the stainless steel multi-purpose canister holding the spent fuel. This material degradation is predicted to take the form of environmentally assisted cracking on weld interfaces of the stainless steel cylinder. Several of these spent fuel storage arrays are located in coastal environments. These sites include both the Hope Creek and Diablo Canyon nuclear power stations. A multi-sensory robotic package is being designed for non-destructive assay of the cask annular environment. It will be …

Physics Based Modeling Of Guided Waves For Detection And Characterization Of Structural Damage In Nde And Shm, Banibrata Poddar

Theses and Dissertations

Guided waves based damage detection techniques are popular for their ease of generation and detection along with their ability to travel long distances. Accurate and efficient modeling is a key for successful implementation of guided waves for NDE/SHM. However, efficient prediction of scattering from various damage is challenging due to the complex nature of these guided waves.

This dissertation presents as physics based efficient and accurate modeling techniques to predict ultrasonic wave propagation and their interaction with various damage. Detection and characterization of damage in structures can typically be divided into two categories, active and passive. This research is aimed …

Positioning Commuters And Shoppers Through Sensing And Correlation, Rufeng Meng

Theses and Dissertations

Positioning is a basic and important need in many scenarios of human daily activities. With position information, multifarious services could be vitalized to benefit all kinds of users, from individuals to organizations. Through positioning, people are able to obtain not only geo-location but also time related information. By aggregating position information from individuals, organizations could derive statistical knowledge about group behaviors, such as traffic, business, event, etc.

Although enormous effort has been invested in positioning related academic and industrial work, there are still many holes to be filled. This dissertation proposes solutions to address the need of positioning in people’s …

Investigation Of Wide Bandgap Semiconductor Devices For Radiation Detection Applications, Rahmi Orhon Pak

Theses and Dissertations

Radioactive materials, as they decay, generate different high-frequency electromagnetic radiation such as alpha particles, beta particles, x-rays, gamma-rays, and neutrons. Nuclear detectors could stop these high-energy ionizing radiations, collect and transport the charges generated to an external circuit, and produce an electrical signal which is amplified by readout electronics to measure the energy of nuclear interaction. Thus, nuclear detectors are important tools for accounting of radioactive materials and have widespread applications in nuclear power plants, nuclear waste management, in national security, in medical imaging such as x-ray mammography, digital chest radiography, CT scan, and in high energy astronomy for NASA …

Ndt And Shm Methods Of Damage Detection In Welded Structures, Saad Mohammed

Theses and Dissertations

There has been an increasing demand for Nondestructive Testing (NDT) and Structural Health Monitoring (SHM) techniques to continuously monitor during all processes of a structure to prevent catastrophic failure and reduce maintenance costs. NDT and SHM are inspection processes which form part of the quality assurance/quality control (QA/QC) scheme. Among NDT and SHM methods, ultrasonic and guided wave techniques are the most commonly and widely used in industry. Ultrasonic methods provide the advantage of accurately locating and dimensioning defects within structures. Most of these structures consist of welded joints because welding is an economical and efficient method for obtaining a …

Implementation Of Agile Project Management In The Classroom, Michael Jerrod Myers

Theses and Dissertations

The world of engineering and engineering practices is advancing rapidly. In response to this rapid change, engineering education practices have to advance to ensure students are properly trained for the workforce. The purpose of this report is to address and substantiate the hypothesis that if engineering instruction incorporated Agile project management methods, then students will be challenged by professors to accomplish course objectives with a systematic and timely approach that will improve assessment performance metrics and present the framework of how agile methods of project management can be integrated into the classroom. The agile methods incorporated will also encourage the …

Effects Of Process Variants On Metallurgical And Mechanical Properties In Friction Stir Welding Of Aluminum Alloys, Xiaomin Huang

Theses and Dissertations

Conventional shoulder friction stir welding (CSFSW) produces uneven heat input through welded material thickness: higher close to the top and lower close to the bottom. When CSFSW is applied on certain aluminum alloys, such as 7xxx and 2xxx series high strength aluminum alloys which contain low melting point intermetallic, overheating and local melting may happen close to weld crown. Stationary shoulder friction stir welding (SSFSW) may generate much more uniform heat input through plate thickness than CSFSW due to the non-rotating shoulder and rotating pin. Therefore, overheating and local melting are expected to be avoided in SSFSW. Furthermore, local properties …

Evaluation Of Concrete Degradation Using Acoustic Emission: Data Filtering And Damage Detection, Marwa A. Abdelrahman

Theses and Dissertations

The prevalence of aging and deteriorating infrastructure in the U.S. has raised concerns regarding its level of serviceability, reliability, and vulnerability to natural disasters. This issue has gained attention recently and efforts are being conducted to accelerate the delivery of enhanced nondestructive testing (NDT) and structural health monitoring (SHM) methods. Acoustic emission (AE) is a strong candidate for these applications due to its high sensitivity and potential for damage detection in different materials. However, several challenges associated with the technique hinder the development of automated, reliable, real-time SHM using AE.

This study aims to advance the use of AE for …

Interest Detection In Image, Video And Multiple Videos: Model And Applications, Yuewei Lin

Theses and Dissertations

Interest detection is detecting an object, event, or process that draws attention. In this dissertation, we focus on interest detection in images, video and multiple videos. Interest detection in an image or a video is closely related to visual attention. However, the interest detection in multiple videos needs to consider all the videos as a whole rather than considering the attention in each single video independently.

Visual attention is an important mechanism of human vision. The computational model of visual attention has recently attracted a lot of interest in the computer vision community mainly because it helps find the objects …

Rational Design And Synthesis Of Pt/Silica-Alumina Metal-Acid Bifunctional Catalysts, Jadid Ettaz Samad

Theses and Dissertations

In the domain of rational catalyst design and synthesis, Strong Electrostatic Adsorption (SEA) has been applied with tremendous potential and use. In this study, SEA method has been advanced to thick slurries as well as to mixed oxide systems with a view to synthesizing stable, active and selective catalysts fine-tuned for specific applications.

The main objective was to synthesize metal-acid bifunctional catalysts with controlled ratio and proximity between metal and acid sites in order to analyze their effects on a bifunctional reaction. At first, the difference in charging behavior of silica and alumina in solution was used to selectively deposit …

Techno Economical Analysis Of Solid Oxide Iron-Air Redox Battery For Power Generation And Energy Storage, Farzana Yasmeen

Theses and Dissertations

The largest source of greenhouse gas emissions in the United States is from burning fossil fuels for electricity, heat, and transportation. Due to increasing environmental constraints associated with greenhouse gas emissions and uncertainty in the supply of fossil fuels, power systems of the future will become more reliable on renewable power source. To overcome the intermittency issue of renewable power, a promising cost effective electricity-storage systems is vital. The U.S. Department of Energy (DOE) has established detailed cost targets for energy storage system. One of the targets is capital cost which should be under $150/kWh for new technology. Another target …

Improved Assessment Of The Magnitude And Acceleration Of Prehistoric Earthquakes In The South Carolina Coastal Plain, Emad Gheibi

Theses and Dissertations

Seismically-induced soil liquefaction is one the most hazardous geotechnical phenomenon that can cause loss of life and devastating damage to infrastructure. Proper estimation of critical ground motion parameters (e.g. peak ground acceleration and earthquake magnitude) is vital for seismic design of new structures and retrofit of existing structures, especially in regions such as the South Carolina Coastal Plain (SCCP) where the frequency of re-occurrence of large earthquakes is low (studies of paleoliquefaction features have revealed seven, large, prehistoric earthquakes occurring within the last 6000 years) and the locations of potential sources are not exactly known. Moreover, due to mechanical and …

Deformation Induced Martensitic Transformation In 304 Stainless Steels, Junliang Liu

Theses and Dissertations

304 stainless steel is an austenitic steel widely used for various applications due to a good combination of strength and ductility and relative low cost. It is known to be metastable as the austenite phase can transform into martensite under stress. In this work, a new method (in-situ tensile TEM) and the traditional method (ex-situ tensile tests and TEM, XRD characterization) were used to investigate the mechanisms of deformation-induced martensitic transformation in 304SS samples at different temperatures.

The ex-situ tensile tests were conducted under a strain rate of 10-3 s-1 until rupture. After the tensile tests, the fractured area was …

A Mechanical Approach To The Characterization Of Material Failure Of Atherosclerotic Lesions, Lindsey A. Davis

Theses and Dissertations

Failure of atherosclerotic plaques can lead to potentially life threatening clinical events such as myocardial infarction (MI), stroke, or transient ischemic attack (TIA). The most frequently described plaque failure mechanism is tensile rupture of the fibrous cap; however, often during angioplasty another plaque failure mechanism occurs in which the atherosclerotic plaque separates from the internal elastic lamina (IEL). This study aims assess the material strength of atherosclerotic lesions using mechanical concepts.

To assess likelihood of plaque dissection at the vessel wall, adhesion strength was assessed in both mouse and human specimens using plaque delamination experiments. Measuring plaque adhesion in transgenic …

Mechanical Characterization Of Sicf-Sicm Nuclear Fuel Cladding By A Novel Hydraulic Internal Pressurization Method, Kirill Shapovalov

Theses and Dissertations

Ceramic Matrix Composites (CMC) have been actively researched for applications requiring high temperature strength and damage tolerance. Examples are turbine engine hot section components, leading edges for hypersonic vehicles, nuclear fusion reactor first wall and blanket, and recently nuclear fuel claddings. Predictable material damage behavior is desirable for these applications so early damage accumulation can be detected before a catastrophic failure occurs. Many ceramic materials can withstand high temperature environments, but due to inherent brittleness of ceramics the high damage tolerance and the predictable damage behavior are difficult to achieve. Ceramic fiber reinforced ceramic composites (CFCC) have demonstrated the above …

A Theoretical Study Of Polymer Based Drug Delivery Systems, Ebtisam Abdullatif Aldaais

Theses and Dissertations

Polymer nanostructured materials for drug delivery applications have witnessed tremendous progress in recent years due to their vast potential. One-end-grafted polymers can form grafted micelles with specific mechanical properties. Biological conditions can alter these properties resulting in the protection or release of drugs. Charged surfactants can also form micelles in an aqueous solution, which can also be manipulated through special conditions. On the micellar surface, self-organized polyelectrolytes can be stimulated to extend their attached ligands and thus increase the probability of binding to targeted receptors. This thesis focuses on modeling polymer-based drug delivery systems by studying the physical interactions between …

Airborne Collision Detection And Avoidance For Small Uas Sense And Avoid Systems, Laith Rasmi Sahawneh

Theses and Dissertations

The increasing demand to integrate unmanned aircraft systems (UAS) into the national airspace is motivated by the rapid growth of the UAS industry, especially small UAS weighing less than 55 pounds. Their use however has been limited by the Federal Aviation Administration regulations due to collision risk they pose, safety and regulatory concerns. Therefore, before civil aviation authorities can approve routine UAS flight operations, UAS must be equipped with sense-and-avoid technology comparable to the see-and-avoid requirements for manned aircraft. The sense-and-avoid problem includes several important aspects including regulatory and system-level requirements, design specifications and performance standards, intruder detecting and tracking, …

Electrophysiology Of Basal Ganglia (Bg) Circuitry And Dystonia As A Model Of Motor Control Dysfunction, Deepak Kumbhare

Theses and Dissertations

The basal ganglia (BG) is a complex set of heavily interconnected nuclei located in the central part of the brain that receives inputs from the several areas of the cortex and projects via the thalamus back to the prefrontal and motor cortical areas. Despite playing a significant part in multiple brain functions, the physiology of the BG and associated disorders like dystonia remain poorly understood. Dystonia is a devastating condition characterized by ineffective, twisting movements, prolonged co-contractions and contorted postures. Evidences suggest that it occurs due to abnormal discharge patterning in BG-thalamocortocal (BGTC) circuitry. The central purpose of this study …

Electric Field Controlled Strain Induced Switching Of Magnetization Of Galfenol Nanomagnets In Magneto-Electrically Coupled Multiferroic Stack, Hasnain Ahmad

Theses and Dissertations

The ability to control the bi-stable magnetization states of shape anisotropic single domain nanomagnets has enormous potential for spawning non-volatile and energy-efficient computing and signal processing systems. One of the most energy efficient switching methods is to adopt a system of a 2-phase multiferroic nanomagnet, where a voltage applied on the piezoelectric layer generates a strain in it and the strain is elastically transferred to the magnetostrictive nanomagnet which rotates the magnetization states of the nanomagnet at room temperature via the converse magnet-electric effect. Recently, it has been demonstrated that the magnetization of a Co nanomagnet can be switched between …

Characterization Of Fibrin Matrix Incorporated Electrospun Polycaprolactone Scaffold, Cho Yi Wong

Theses and Dissertations

Specific objective: Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a barrier membrane. For the GTR procedures to be successful, barrier membranes are required to be present at the surgical site for an extended period of time (weeks to months). Synthetic membranes have the advantage of prolonged presence in a wound site; however, they do not actively contribute to wound healing. Biologic membranes are recognized by the host tissue and participate in wound healing but have the disadvantage of early resorption. Therefore, the goal of this study is …

In-Shoe Plantar Pressure System To Investigate Ground Reaction Force Using Android Platform, Ahmed A. Mostfa

Theses and Dissertations

Human footwear is not yet designed to optimally relieve pressure on the heel of the foot. Proper foot pressure assessment requires personal training and measurements by specialized machinery. This research aims to investigate and hypothesize about Preferred Transition Speed (PTS) and to classify the gait phase of explicit variances in walking patterns between different subjects. An in-shoe wearable pressure system using Android application was developed to investigate walking patterns and collect data on Activities of Daily Living (ADL). In-shoe circuitry used Flexi-Force A201 sensors placed at three major areas: heel contact, 1st metatarsal, and 5th metatarsal with a PIC16F688 microcontroller …

In Vitro Visualization Of Pediatric Sized Mechanical Heart Valve Performance Using Aortic Root Model In Mock Circulatory Loop, Sarah Lederer

Theses and Dissertations

Congenital heart valve disease is one of the most common abnormalities in children, with common valve defects being aortic stenosis, mitral stenosis, and valvular regurgitation. Although adult sized mechanical heart valve (MHV) replacements are widely studied and utilized, there are currently no FDA approved prosthetic heart valves available for the pediatric population. This is due to a variety of reasons such as a limited patient pool for clinical trials, limited valve sizes, and complex health histories in children. Much like adult sized mechanical heart valves, potential complications with pediatric heart valve replacements include thrombosis, blood damage due to high shear …

Growth And Characterization Of Wide Bandgap Quaternary Bemgzno Thin Films And Bemgzno/Zno Heterostructures, Mykyta Toporkov

Theses and Dissertations

This thesis reports a comprehensive study of quaternary BeMgZnO alloy and BeMgZnO/ZnO heterostructures for UV-optoelectronics electronic applications. It was shown that by tuning Be and Mg contents in the heterostructures, high carrier densities of two-dimensional electron gas (2DEG) are achievable and makes its use possible for high power RF applications. Additionally, optical bandgaps as high as 5.1 eV were achieved for single crystal wurtzite material which allows the use of the alloy for solar blind optoelectronics (E_g>4.5eV) or intersubband devices.

A systematic experimental and theoretical study of lattice parameters and bandgaps of quaternary BeMgZnO alloy was performed for …

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …