Engineering Commons^™

Numerical Modeling Of Infrared Thermography Techniques Via Ansys, Hayder Abdulnabi Thajeel

Masters Theses

"Several inspection techniques have been developed over years. Recently, infrared thermography (IRT) technology has become a widely accepted as a nondestructive inspection (NDI) technique for different fields and various applications as well. Infrared thermography stands as one of the most an attractive and a successful NDI technique that has ability to detect the object's surface/subsurface defects remotely based on observing and measuring the surface's emitted infrared heat radiation by using an infrared camera. The finite element modeling FEM ANSYS was successfully used for the modelling of several IRT techniques; such as Pulsed Thermography (PT) and Lock-in Thermography (LT) that can …

Optimized Techniques For Real-Time Microwave And Millimeter Wave Sar Imaging, Joseph T. Case

Doctoral Dissertations

"Microwave and millimeter wave synthetic aperture radar (SAR)-based imaging techniques, used for nondestructive evaluation (NDE), have shown tremendous usefulness for the inspection of a wide variety of complex composite materials and structures. Studies were performed for the optimization of uniform and nonuniform sampling (i.e., measurement positions) since existing formulations of SAR resolution and sampling criteria do not account for all of the physical characteristics of a measurement (e.g., 2D limited-size aperture, electric field decreasing with distance from the measuring antenna, etc.) and nonuniform sampling criteria supports sampling below the Nyquist rate. The results of these studies demonstrate optimum sampling given …

A New Method For Failure Modes And Effects Analysis And Its Application In A Hydrokinetic Turbine System, Liang Xie

Masters Theses

"The traditional failure modes and effects analysis (FMEA) is a conceptual design methodology for dealing with potential failures. FMEA uses the risk priority number (RPN), which is the product of three ranked factors to prioritize risks of different failure modes. The three factors are occurrence, severity, and detection. However, the RPN may not be able to provide consistent evaluation of risks for the following reasons: the RPN has a high degree of subjectivity, it is difficult to compare different RPNs, and possible failures may be overlooked in the traditional FMEA method. The objective of this research is to develop a …

Use Of Ultra-High Performance Concrete To Mitigate Impact And Explosive Threats, Julie Anne Willey

Masters Theses

"This study is a continuation of research conducted by Natalia Carey, Anthony Wulfers, and Dr. John Myers under the DHS ALERT Center. Carey investigated the use of polyurea coating systems to mitigate close range blast threats on wall panels. Wulfers continued this by using both polyurea coatings as well as a sacrificial wood fiber fly ash (WF-FA) layer to try to get increased performance. This research was aimed at the study of ultra-high performance concrete (UHPC) for the use in impact and blast mitigation. There is little information on the performance of UHPC under close range blast loading; therefore it …

Manufacturing And Performance Evaluation Of Out-Of-Autoclave Sandwich Composites, Sriram Nagarajan

Masters Theses

"Composite sandwich structures are being increasingly employed in applications which require high strength, high in-plane and flexural stiffness coupled with a reduction in weight. Sandwich composites used in the aerospace industry are typically manufactured using high pressure autoclave processing which is expensive and time consuming. A viable low cost alternative is the Out-of-autoclave (OOA) process. One of the most dominant failure modes in sandwich composites is the debonding that occurs at the facesheet skin to core interphase leading to severe degradation of structural properties of the sandwich. A well formed adhesive bond at the skin to core interphase and improved …

Enhancement Of Vortex Induced Vibrations Using Roughness Strips, Ashwin Vinod

Masters Theses

"The current experimental work focuses on studying the effects of surface roughness on vortex induced vibration (VIV) of an elastically mounted circular cylinder which is free to vibrate in a direction transverse to the flow. Flow separation in known to occur due to viscous effects when a fluid flows over a bluff body. The separation of fluid causes shedding of alternating vortices in the downstream region, which in turn impart an alternating force on the bluff body. The vibrations incurred due to such forces are called as Vortex Induced Vibrations (VIV) and have been traditionally known to be harmful to …

Comparison Of Class Ii Injection Well Area Of Review Requirements With Area Of Evaluation For Hydraulically Fractured Wells, Yashesh Jitendra Panchal

Masters Theses

"Since 2010 the US Environmental Protection Agency (EPA) has been proposing plans to study, and has now initiated research regarding the potential impact of hydraulic fracturing processes on drinking water sources. Their work refers to an 'Area of Evaluation' around a hydraulically fractured well, inferring that the wells immediately around hydraulic fractured wells should be studied, to evaluate the conditions of these wells and their potential to contaminate overlying USDWs. Class II injection wells must have a minimum 1/4 mile radius area of review to determine the condition of wells surrounding the proposed injection well. All wells within this AOR …

Liquid Phase Sintering Of 20bi(Zn₀.₅Ti₀.₅)O₃-80batio₃ Dielectrics With Bismuth-Zinc-Borate And Bismuth Borosilicate Glasses, David I. Shahin

Masters Theses

"Dielectrics in the Bi(Zn₀.₅Ti₀.₅O₃-BaTiO₃ system (specifically 20BZT-80BT, in mol%) are promising candidates for high energy density capacitor applications due to broad temperature-dependent dielectric constant maxima and a relatively field-independent permittivity. Bulk samples require sintering temperatures of greater than 1180ºC to reach useful densities. Due to incompatibility of Bi with low-pO₂ processing, BZT-BT-based multilayer capacitors must utilize noble metal electrodes that resist oxidation during sintering. Sintering temperatures must be reduced to allow use of less expensive electrode materials (Cu, etc.). This work studies the reduced temperature sintering behavior and dielectric properties of BZT-BT sintered with 30 Bi₂O₃-30ZnO-40B₂O₃ and 50Bi₂O₃-25B₂O₃-25SiO₂ (mol%) liquid …

Improving Life Cycle Management Plans For Power Plant Components, Srinath Raghavan

Masters Theses

"Life cycle management (LCM) combines a set of technical and economic activities with the specific goal of improving the long term economic value of an asset. It is necessary to perform a sound LCM exercise on the utility or industrial asset to maintain the profitability of a plant. In most industries, the maintenance budget is either higher than optimal or lower than required, that result in expensive outages, damages and accidents. An LCM plan is a guide to make operational decision for a component over its life cycle. LCM typically consists of a preventive maintenance schedule, condition monitoring, inspection activities, …

Two Essays On Dynamic Programming And Reinforcement Learning, Shuva Ghosh

Doctoral Dissertations

"The semi-Markov decision process (SMDP) is a variant of the Markov decision process (MOP). This dissertation work focuses on the application of SMDPs to disaster response management and to maintenance management. Average and discounted reward are two popular performance metrics for MDPs/SMDPs. While both dynamic programming (DP) methods, i.e., value iteration and policy iteration, are commonly used to solve MDPs/SMDPs, value iteration is easier to apply than policy iteration. The existing value iteration algorithms for average reward SMDPs have some noteworthy limitations, which are sought to be overcome in this work. Reinforcement learning (RL) techniques, which are also studied in …

Bioactive Glass Scaffolds For The Regeneration Of Load-Bearing Bone, Xin Liu

Doctoral Dissertations

"Biocompatible scaffolds that replicate the structure and function of bone would be ideal bone substitutes for structural bone loss, provided they have the requisite mechanical properties for reliable long-term loading. In this dissertation, strong porous scaffolds of silicate 13-93 bioactive glass, created with two different microstructures, were evaluated to determine their mechanical properties and their capacity to regenerate bone in a rat calvarial defect model. Scaffolds with an oriented microstructure of columnar pores were prepared by unidirectional freezing of camphene-based suspensions, followed by thermal annealing and sintering. By optimizing the freezing conditions, annealing time, and sintering temperature, constructs (porosity = …

A Comparison Of American And Asian Automakers' Vehicles In Quality, Reliability, And Safety, Ozge Senoz

Doctoral Dissertations

"Consumer Reports (CR) and J.D. Power and Associates (JDP) are two widely-known agencies that gather data on automobile quality and prepare reports on the data gathered that are related to various aspects of automobiles for different models for each manufacturer. This research has two overarching goals: The first is to determine if there are any clear differences in reliability, between the Japanese and U.S. auto-makers. The second is to determine if there is consistency between JDP and CR in the reliability ratings of vehicles. In order to attain these goals, this dissertation starts with the evaluation of these two major …

Topics In Voice Echo Cancellation, Pratik Vijay Shah

Doctoral Dissertations

"Acoustic echo cancellation (AEC) is a well studied problem. The underlying assumption in most echo cancellation solutions is that the echo path following the reference signal is completely linear. However, in many handheld devices, the echo path following the reference signal is nonlinear. The reason for this nonlinearity in the echo path is the use of smaller and cheaper loudspeakers. In order to cut the manufacturing cost, device manufactures use cheaper loudspeakers such that they satisfy the carrier specifications. Such loudspeaker can be easily over driven in to their nonlinear region and thus add nonlinearities to the downlink path. This …

Utilization Of Booster Fans In Underground Mines, Arash Habibi Javanbakht

Masters Theses

"Booster fans are large underground fans that can increase the volumetric efficiency of ventilation systems by balancing the pressure and quantity distribution throughout a mine, reducing leakage and reducing the total power requirement. The objective of this study is to provide potential users of booster fans with the necessary information on the design, installation and operation of main underground fans. The guidelines listed in this paper were formulated based on current U.S. and international standards, safe operating practices developed by the mining industry, and recommendations provided by fan manufacturers. The principles involved in the design and installation of booster fans …

Significance And Analysis Of Milia-Like Cysts In Dermoscopy Skin Lesion Images, Sneha K. Mahajan

Masters Theses

“Milia-like cysts (MLCs) are dermoscopic structures frequently observed in seborrheic keratoses(SKs), which are the most common type of skin lesions. Diverse appearances of these skin lesions make them difficult to differentiate from melanoma, a deadly type of skin cancer. Classified by size into two main groups, starry MLCs and cloudy MLCs, the presence of these structures in a skin lesion has been known to help differentiate benign lesions from melanoma. Though the presence of cloudy MLCs is not exclusively associated with SKs, they can be a useful tool to differentiate SKs from melanoma. This research study determines the statistical occurrence …

Development Of A Methodology For Pseudo-Rigid-Body Models Of Compliant Segments With Inserts, And Experimental Validation, Raghvendra Sharadchandra Kuber

Masters Theses

"Compliant mechanisms have shown a great deal of potential in the last few decades in providing better solutions to design problems with numerous benefits; however, their use has been limited due to current challenges in the material selection. With ever increasing focus on the applications of compliant mechanisms, it is necessary to find alternatives to the existing materials and methods of prototyping. The purpose of this work is to develop a methodology for pseudo-rigid-body models of compliant segments with compliant inserts, comprised of a resilient material placed between the layers of a softer material, to alleviate any creep and strength …

Wolf Creek Dam: A Case Study Of Foundation Remediation For Dams Built On Karst Foundations, Kyla Justene Erich

Masters Theses

"Wolf Creek Dam was completed in 1952 as a 5,736-foot long and 258-foot high combination embankment-concrete gravity dam. Its storage capacity of 6 million acre feet makes it the ninth largest reservoir in the nation. The dam was built on a heavily karstified limestone foundation and began exhibiting signs of excess foundation seepage in late 1967. This led to extensive corrective work in the 1970s beneath the earthen core of the embankment to reduce underseepage. In 2006 an independent assessment by the Dam Safety Action Classification (DSAC) Peer Review Panel recommended that Wolf Creek Dam exhibited "Urgent and Compelling" foundation …

Green Roof Water Quality Impacts And Physicochemical Stability, Grace Ella Harper

Masters Theses

"Green roofs can provide environmental benefits and conserve energy; this research evaluated green roof stormwater management, nutrient loading, and erosion prevention for two green roof media. During a pilot study, the runoff quantity and composition from green roof material was evaluated continuously under field conditions for two different media, both tested under planted and unplanted conditions. Water quantity results show over a 40% reduction in runoff from just the growing media and over 60% reduction in runoff with established plants in green roof media over the eight month study. Previous studies have reported a "first flush" of excess nutrients but …

Harmonic Compensation In A Grid Using Doubly Fed Induction Generators, Omkar Amol Ghatpande

Masters Theses

"Ideally, electric utilities are expected to deliver a sinusoidal voltage with a constant rated frequency, while customers are expected to draw a sinusoidal current with unity power factor. The recent widespread use of harmonic producing equipment in industrial applications, especially non-linear loads, has increased the distortion of electric currents and voltages in transmission and distribution systems. This thesis proposes a method of using multiple reference frame theory for measuring and mitigating harmonic currents of nonlinear loads using a doubly fed induction generator. The most significant low-order harmonics to be compensated are calculated using a multiple reference frame harmonic observer. This …

Tensile Failure During Structural Development Of Single-Layer Buckle Folds, Xiaolong Liu

Masters Theses

"Folds and fold trains of sedimentary strata are among the most common structural traps systems for hydrocarbon reservoirs. The existence of tensile fractures associated to buckle folding is associated to the distribution of extensional strain in the outer arc of the fold hinges. This study investigates the conditions under which tensile stresses develop due to buckling in a realistic in situ stress scenario. By applying a 2D finite element modeling approach, the influence of realistic mechanical stratigraphy (including strain rate, overburden depth, competence contrasts, viscosity, and permeability) on the development of single-layer buckle folds with Newtonian viscous rheology is studied. …

Fuzzy Logic Color Detection: Blue Areas In Dermoscopy Melanoma Images, Mounika Lingala

Masters Theses

"Malignant melanoma is one of the deadliest forms of skin cancer and is one of the most rapidly increasing cancers in the world. Image analysis techniques for the early detection of melanoma are dependent upon the detection of multiple color shades in melanoma images. Use of magnified visible-light imaging by dermoscopy allows detailed investigation of these color shades. This research explores the fuzzy logic methods for the detection and characterization of blue color shades to discriminate melanoma from benign skin lesions. Standard thresholds are placed on the RGB dermoscopy images firstly and then the restrictiveness is explored by implementing fuzzy …

Development Of A New Temporary Fastener For Aerospace Automation, Xiangwen Zhang

Masters Theses

"Temporary fasteners are required in aircraft assembly, especially in the assembly of wings, fuselage, and aircraft skin's substructure prior to drilling holes for permanent fasteners by automated drilling machines. The objective was to develop a temporary fastener that can be installed, clamped, loosened, and removed from one side with a short head length. Published papers, web pages and patents relating to temporary fasteners were reviewed. Then by considering the ability to meet the operation requirements and concerns, a temporary fastener was designed with the following advantages:

• a simple structure that can be easily fabricated
• a short head length to save …

Behavior And Effects Of Nanoparticles In Complex Fluid Systems, Chen Wang

Doctoral Dissertations

"The development of nanoscale technologies has greatly expanded the scientific and engineering horizons and also has the potential to turn molecular discoveries into worldwide benefits on multiple fronts. Despite recent extensive efforts, the focus of nanoparticle studies has been on their synthesis and various possible derivatives. In this dissertation, molecular based modeling and simulation studies have been performed to characterize and understand the behavior, properties, and effects of nanoparticles in some important material systems. The results show that small nanoparticles that are highly faceted have significant shape effects, which are not captured by classical continuum-based approaches. When dissolved in confined …

Development Of An Integrative Commissioning Methodology For New-Building Construction, William L. Gillis Iii

Doctoral Dissertations

"Commissioning (Cx) is a quality process for building construction used to verify that the owner's project requirements (OPR) are being met by the final design, construction, and operations and maintenance. The goal is to confirm that each phase of the project is linked back to the OPR through quality assurance methods. Leadership in Energy and Environmental Design (LEED) certification is an OPR which contributes to difficulties within the design and construction (D&C) process. Though LEED certification is only part of the OPR, too often the design drifts from the OPR and simply focuses on meeting the LEED certification.

Quality function …

Fluidic Sensor Devices Utilizing Dry Film Resist As Main Structural Materials, Sijia Gong

Masters Theses

"In this thesis, two types of fluidic sensor devices are demonstrated. The first device utilizes a dry film resist (DFR) as the main structural material of fluidic device utilizing the photolithography process. The second one involves a simple, low-cost sensor platform composed of ubiquitous materials such as polymer tubing and metal wires. Both devices are prepared to measure the dissolved oxygen content, as a model target analyte, based on the oxygen quenching reaction of a ruthenium complex fluorophore as the reporting agent. Characterization of sensors is conducted based on the fluorescence lifetime measurement. The first type of sensor is constructed …

Effects Of Machining Parameters And Cooling Strategies On Cutting Forces And Surface Integrity In High-Speed Slot End-Milling Of Titanium Alloy, Emenike Chukwuma

Masters Theses

“Paper 1 presents the results of the investigations of the effects of cooling strategies [Emulsion cooling, Minimum Quantity Lubrication (MQL) and Liquid Nitrogen (LN₂)] and machining parameters (feed rate and spindle speed) on cutting force components, cutting temperature and tool wear during slot end-milling of titanium Ti-6Al-4V workpiece. All machining experiments were conducted using four-flute 0.5 inch diameter uncoated solid carbide end-mill on Cincinnati Milacron, Sabre 750 vertical machining center equipped with Acramatic 2100 controller. Cutting force components were acquired and tool wear was indirectly measured from maximum cutting force variation per slot from the first pass to …

Rotary Displacement Piezoelectric Energy Harvester, Headman Sanei

Masters Theses

“This study proposes a novel piezoelectric energy harvester for rotary motion applications. It is based on an annular unimorph plate, mounted on a shaft rotating at a constant angular velocity, under constant amplitude point-wise force. The mathematical model and the analysis was proposed for the inverse problem of a rotating disk under a static stationary force. The disk, however, is assumed to be stationary subjected to a traveling force. The distributed parameter electromechanical equations governing the behavior of the system are provided in closed-form, incorporating both an AC and a simple rectifier circuit. The performance of the energy harvester was …

Stochastic-Optimization Of Equipment Productivity In Multi-Seam Formations, Elijah Adadzi

Masters Theses

"Short and long range planning and execution for multi-seam coal formations (MSFs) are challenging with complex extraction mechanisms. Stripping equipment selection and scheduling are functions of the physical dynamics of the mine and the operational mechanisms of its components, thus its productivity is dependent on these parameters. Previous research studies did not incorporate quantitative relationships between equipment productivities and extraction dynamics in MSFs. The intrinsic variability of excavation and spoiling dynamics must also form part of existing models. This research formulates quantitative relationships of equipment productivities using Branch-and-Bound algorithms and Lagrange Parameterization approaches. The stochastic processes are resolved via Monte …

Kinetics Of Human And Bovine Insulin Amyloid Fibril Formation In The Presence Of Solid/Liquid Interfaces, Paulina Barranco Morales

Masters Theses

"The purpose of this thesis was to study the rate and extent of aggregation of human and bovine insulin in bulk and in the presence of either polystyrene microspheres with different surface chemistries or liposomes of different composition. Insulin aggregation was followed by turbidimetry, Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering. The Congo red assay was used to corroborate the presence of amyloid deposits and transmission electron microscopy (TEM) was used to analyze the morphology of the amyloid deposits. Our results show that not all the surfaces shortened the lag time. On the other hand, most surfaces had …

Wideband Characterization Of Printed Circuit Board Materials Up To 50 Ghz, Aleksei Rakov

Masters Theses

"A traveling-wave technique developed a few years ago in the Missouri S&T EMC Laboratory has been employed until now for characterization of PCB materials over a broad frequency range up to 30 GHz. This technique includes measuring S-parameters of the specially designed PCB test vehicles. An extension of the frequency range of printed circuit board laminate dielectric and copper foil characterization is an important problem. In this work, a new PCB test vehicle design for operating up to 50 GHz has been proposed. As the frequency range of measurements increases, the analysis of errors and uncertainties in measuring dielectric properties …