Engineering Commons^™

Turbulent Gas Breakup Modeling And Acoustic Void-Fraction Determination Studies In Support Of Cavitation Damage Mitigation Of The Spallation Neutron Source Target Vessel, Stuart Alexander Walker

Doctoral Dissertations

Pressure pulses induced by proton beam deposition lead to cavitation and pitting erosion of the SNS target vessel; this damage limits the lifetime of the vessel. Dampening the pressure pulse by adding compressibility to the bulk mercury in the form of microbubbles is a promising technique for damage mitigation. The physics governing gas bubble breakup in turbulent flows is examined leading to mechanistic based scaling models for the gas breakup in a swirling jet type microbubble generator. These models are verified experimentally in an air/water system and compared to a legacy empirical model. Verifying the performance of a microbubble generator …

Towards Sustainable Development Of Nanomanufacturing, Sasikumar Ramdas Naidu

Doctoral Dissertations

"Sustainability" is a buzz word these days not just among regulatory agencies but even with corporations, as evident by the release of annual sustainability report by a large number of firms. Companies are starting to portray profit making along with corporate environmental responsibility.

Nanotechnology and nanomanufacturing which holds a lot of promise for development in a multitude of fields in science and engineering is the new kid on the block and carries a lot of apprehension due to public concern about their potential unwanted side effects that may result in the case of an untoward incident or lack of oversight. …

Hydrologic Reconstructions Using Dendroclimatology, Climate Signals, And Pacific Ocean Sea Surface Temperature Variability, Sallyrose Anderson

Doctoral Dissertations

The Colorado River provides water to over 25 million people. Given the importance of this water supply, it is critical to understand the hydrologic variables in the Colorado River Basin. In this dissertation, I reconstructed hydrologic conditions (soil moisture, snowpack) in the Upper Colorado River Basin (UCRB) and examined different factors that influence water supply in the region (climate oscillations, oceanic-atmospheric variability).

Firstly, I reconstructed soil moisture in the UCRB. Principal components analysis (PCA) and k-Nearest Neighbor (k-NN) techniques were used to regionalize the gridded data. Correlated tree-ring chronologies (TRCs) were used as predictor variables in stepwise linear regression (SLR) …

Uwb Pulse Radar For Human Imaging And Doppler Detection Applications, Yazhou Wang

Doctoral Dissertations

We were motivated to develop new technologies capable of identifying human life through walls. Our goal is to pinpoint multiple people at a time, which could pay dividends during military operations, disaster rescue efforts, or assisted-living. Such system requires the combination of two features in one platform: seeing-through wall localization and vital signs Doppler detection.

Ultra-wideband (UWB) radar technology has been used due to its distinct advantages, such as ultra-low power, fine imaging resolution, good penetrating through wall characteristics, and high performance in noisy environment. Not only being widely used in imaging systems and ground penetrating detection, UWB radar also …

Deep Machine Learning With Spatio-Temporal Inference, Thomas Paul Karnowski

Doctoral Dissertations

Deep Machine Learning (DML) refers to methods which utilize hierarchies of more than one or two layers of computational elements to achieve learning. DML may draw upon biomemetic models, or may be simply biologically-inspired. Regardless, these architectures seek to employ hierarchical processing as means of mimicking the ability of the human brain to process a myriad of sensory data and make meaningful decisions based on this data. In this dissertation we present a novel DML architecture which is biologically-inspired in that (1) all processing is performed hierarchically; (2) all processing units are identical; and (3) processing captures both spatial and …

Analyses Of Measurements From The Crater Instrument On The Lro Spacecraft Using Space Radiation Transport Codes, Jamie Alicia Anderson

Doctoral Dissertations

In June 2009, the Lunar Reconnaissance Orbital (LRO) Spacecraft was launched to orbit Earth’s Moon. Objectives of this mission are to find potential safe landing sites, locate potential resources, test new technologies, and characterize the lunar radiation environment. Located on the LRO is the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument which is designed to characterize the lunar radiation environment, its biological impact on humans, and impact on equipment. CRaTER will provide a better and more accurate understanding of the lunar radiation environment by measuring linear energy transfer (LET). This lunar environment includes solar particle events (SPEs) …

Influences Of Sample Preparation On The Indentation Size Effect And Nanoindentation Pop-In On Nickel, Zhigang Wang

Doctoral Dissertations

Careful experiments were performed with a well characterized indenter to systematically investigate the influences of sample preparation on the indentation size effect (ISE) and nanoindentation pop-in behavior in nickel. The Ni (100) surface was prepared by electropolishing and then damaged in a controlled way by polishing with alumina slurry. The damaged layer was systematically removed in steps by colloidal silica polishing (0.02 µm (micrometer)) with the pop-in behavior statistically characterized and the depth dependence of the hardness measured at each step. AFM observation revealed that the electropolished surface is free from scratches, and has the largest roughness. Numerous scratches were …

Leksell Gamma Knife Treatment Planning Via Kernel Regression Data Mining Initialization And Genetic Algorithm Optimization, Joseph Michael Bowling

Doctoral Dissertations

Gamma Knife is a medical procedure that is used to treat several types of intracranial disease. The system utilizes gamma rays from Cobalt-60 radiation sources focused at an isocenter and a stereotactic frame system that serves as an immobilization device coordinate system. Treatment is performed by localizing the patient’s disease with a medical imaging study and positioning the diseased area at the focused intersection of the beams. Patient treatment may require multiple treatment positions and varying beam sizes. The treatment position, time, and beam size is determined through a treatment planning process. Traditionally Gamma Knife treatment planning is performed manually …

Metallurgical Effects On Long-Term Creep-Rupture In A New Nickel-Based Alloy, John P Shingledecker

Doctoral Dissertations

A series of creep-rupture studies were conducted on a new nickel-based alloy, Inconel Alloy 740, for use in Advanced Ultrasupercritical (A-USC) Steam boiler applications. The research quantitatively showed, for the first time, that the formation of a small amount of eta phase during long-term creep testing at 750 degrees Celsius does not degrade the rupture strength or ductility of the alloy. A unique full-scale pressurized tubular creep test was conducted, and a new analysis methodology was developed to evaluate the effect of cold-straining on the creep performance of tube bends made from the alloy. The results showed that 15% cold-work …

Liquid Jet Experiments And Simulations For A Verification And Validation Study, Lee Paul Tschaepe

Doctoral Dissertations

The velocity field for two vertical parallel water jets impinging into a large stationary volume of water is mapped using ultrasonic interrogation. Thermal mapping of the vertical parallel water jets at high Reynolds numbers has been performed. The velocity data and associated statistics are related to the measurement volume and the ultrasonic Doppler measurement technique. The data are also compared to the literature for twin jets. The interaction of parallel jets is of interest to liquid metal reactor design. Liquid metal fast reactor (LMFR) coolant enters the bottom of the fuel bundles and exits through the top of the bundles. …

A Novel Imaging System For Automatic Real-Time 3d Patient-Specific Knee Model Reconstruction Using Ultrasound Rf Data, Rimon Adel Messiha Tadross

Doctoral Dissertations

This dissertation introduces a novel imaging method and system for automatic real-time 3D patient-specific knee model reconstruction using ultrasound RF data. The developed method uses ultrasound to transcutaneously digitize a point cloud representing the bone’s surface. This point cloud is then used to reconstruct 3D bone model using deformable models method.

In this work, three systems were developed for 3D knee bone model reconstruction using ultrasound RF data. The first system uses tracked single-element ultrasound transducer, and was experimented on 12 knee phantoms. An average reconstruction accuracy of 0.98 mm was obtained. The second system was developed using an ultrasound …

Derivation Of Correction Terms To The Eikonal Approximations In The Formulation Of Analytical Abrasion-Ablation Model, Santosh Bhatt

Doctoral Dissertations

Analytical models for the quantitative predictions of spectra from the neutrons and light ions produced from the high energy, heavy ion (HZE) reactions are extremely important in assessment of the radiation damage during long duration deep space missions, and for various accelerator applications. The fundamental physics of the secondary particle production and transport from these HZE reactions is described using the abrasion-ablation model. The abrasion part of the model is based on the Glauber multiple scattering theory while the ablation process is based on statistical decay based on an evaporation model. The current formulations for the abrasion process are based …

Hydrology, Soil Erosion And Climate Interactions On Low Compaction Steep-Sloped Reclaimed Sites In The Southern Appalachian Coal Fields, Tennessee, Siavash Hoomehr

Doctoral Dissertations

The use of loose spoil on steep slopes for surface coal mining reclamation sites has been promoted by the US Department of Interior, Office of Surface Mining for the establishment of native forest. Although low-compaction spoils improve tree survival and growth, the erodibility and hydrology of steep slopes may change due to this practice. The purpose of this study was to quantify the erodibility (K factor), and the Curve Number (CN) value for low compaction, steep-sloped (> 20%) reclaimed mine lands in the Appalachian region, USA. This study also investigated the performance of the SEDCAD model in estimating erosion and …

Low-Voltage Bulk-Driven Amplifier Design And Its Application In Implantable Biomedical Sensors, Liang Zuo

Doctoral Dissertations

The powering unit usually represents a significant component of the implantable biomedical sensor system since the integrated circuits (ICs) inside for monitoring different physiological functions consume a great amount of power. One method to reduce the volume of the powering unit is to minimize the power supply voltage of the entire system. On the other hand, with the development of the deep sub-micron CMOS technologies, the minimum channel length for a single transistor has been scaled down aggressively which facilitates the reduction of the chip area as well. Unfortunately, as an inevitable part of analytic systems, analog circuits such as …

Fabrication And Characterization Of Hybrid Energy Harvesting Microdevices, Zhongcheng Gong

Doctoral Dissertations

In this dissertation, a hybrid energy harvesting system based on a lead zirconate titanate (PZT) and carbon nanotube film (CNF) cantilever structure has been designed, fabricated and studied. It has the ability to harvest light and thermal radiation energy from ambient energy and convert them to electricity.

The proposed micro-scale energy harvesting device consists of a composite cantilever beam (SU-8/CNF/Pt/PZT/Pt) which is fixed on a silicon based anchor and two electrode pads for wire bonding. The CNF acts as an antenna to receive radiation energy and convert it to heat energy and then transfer to the whole cantilever structure. The …

Basic Capillary Microfluidic Chip And Highly Sensitive Optical Detector For Point Of Care Application, Mingjin Yao

Doctoral Dissertations

A cost-effective and highly sensitive portable diagnostic device is needed to enable much more widespread monitoring of health conditions in disease prevention, detection, and control. Miniaturized and easy-to-operate devices can reduce the inherent costs and inefficiencies associated with healthcare testing in central laboratories. Hence, clinicians are beginning to use point of care (POC) testing and flexible clinical chemistry testing devices which are beneficial for the patient.

In our work, a low-cost and simple autonomous microfluidic device for biochemical detection was developed. The pumpless capillary system with capillary stop valves and trigger valves is fabricated on a silicon (Si) wafer and …

Numerical Simulation Of Nanopulse Penetration Of Biological Matter Using The Adi-Fdtd Method, Fei Zhu

Doctoral Dissertations

Nanopulses are ultra-wide-band (UWB) electromagnetic pulses with pulse duration of only a few nanoseconds and electric field amplitudes greater than 105 V/m. They have been widely used in the development of new technologies in the field of medicine. Therefore, the study of the nanopulse bioeffects is important to ensure the appropriate application with nanopulses in biomedical and biotechnological settings. The conventional finite-difference time-domain (FDTD) method for solving Maxwell's equations has been proven to be an effective method to solve the problems related to electromagnetism. However, its application is restricted by the Courant, Friedrichs, and Lewy (CFL) stability condition that confines …

The Engineering Design Process As A Model For Stem Curriculum Design, Krystal Sno Corbett

Doctoral Dissertations

Engaging pedagogics have been proven to be effective in the promotion of deep learning for science, technology, engineering, and mathematics (STEM) students. In many cases, academic institutions have shown a desire to improve education by implementing more engaging techniques in the classroom. The research framework established in this dissertation has been governed by the axiom that students should obtain a deep understanding of fundamental topics while being motivated to learn through engaging techniques. This research lays a foundation for future analysis and modeling of the curriculum design process where specific educational research questions can be considered using standard techniques. Further, …

The Search For An Optimal Means Of Determining The Minmax Control Parameter Using Sensitivity Analysis, John Teye Brown

Doctoral Dissertations

The use of computational methods for design and simulation of control systems allows for a cost-effective trial and error approach. In this work, we are concerned with the robust, real-time control of physical systems whose state space is infinite-dimensional. Such systems are known as Distributed Parameter Systems (DPS). A body whose state is heterogeneous is a distributed parameter. In particular, this work focuses on DPS systems that are governed by linear Partial Differential Equations, such as the heat equation. We specifically focus on the MinMax controller, which is regarded as being a very robust controller. The mathematical formulation of the …

Mathematical Modeling Of Pipeline Features For Robotic Inspection, Yang Gao

Doctoral Dissertations

Underground pipeline systems play an indispensable role in transporting liquids in both developed and developing countries. The associated social and economic cost to repair a pipe upon abrupt failure is often unacceptable. Regular inspection is a preventative action that aims to monitor pipe conditions, catch abnormalities and reduce the chance of undesirable surprises. Robots with CCTV video cameras have been used for decades to inspect pipelines, yielding only qualitative information. It is becoming necessary and preferable for municipalities, project managers and engineers to also quantify the 3-D geometry of underground pipe networks. Existing robots equipped specialized hardware and software algorithms …

Discrete Fiber-Reinforced Polyurea Systems For Infrastructure Strengthening And Blast Mitigation, Natalia L. Carey

Doctoral Dissertations

"The research presented in this dissertation focused on evaluating the effectiveness of various blast mitigation materials and coating technologies to be used for enhancing blast resistance of structural members. Mechanical properties and blast mitigation performance of different discrete fiber-reinforced polyurea (DFRP) systems were investigated through experimental and analytical work. Four technical papers discuss the research efforts conducted within this dissertation.

The first paper examined the development and characterization of different DFRP systems for infrastructure strengthening and blast retrofit. The behavior of various systems which consisted of chopped E-glass fibers discretely integrated in with the polyurea matrix was evaluated through coupon …

Influence Of Temperature And Microstructural Modification On Formability Of Magnesium Alloys, Arun Mohan

Doctoral Dissertations

"The ß-precipitate free AZ31, ß-precipitate rich AZ91 and a few Mg-Y-Zn alloys were studied to understand the dependence of Mg formability on microstructural condition and temperature. Friction stir processing (FSP) was used to refine the grain size and to obtain desirable distribution of precipitates in the matrix. Since Mg alloys exhibit challenges in achieving room temperature formability, superplastic deformation was utilized. This work focused on high strain rate superplasticity (HSRS, ≥10⁻² s⁻¹) which is more attractive for industrial applications as compared to the slower rates of conventional superplasticity.

Thermally stable fine grains and pinning particles at HSRS temperatures were essential …

Two Essays On The Domain Translation From Financial Options To Real Options, Hongyan Chen

Doctoral Dissertations

"Real options (ROs) extend the financial option pricing theory to the valuation of real asset investment and managerial flexibility under uncertainty. However, differences between financial and non-financial markets, and the complex real world environment of applications, build obstacles for the domain translation from financial options to ROs.

This dissertation is motivated by the challenges of domain translation and developed in two essays. The first essay studies the incentive function of ROs (named the RO incentive). The essay develops an option-game framework to model the RO incentive, examines the change of investment behavior caused by the RO incentive, and values the …

Global Homotopy Continuation And Stability Analysis: Optimal Application To Chemical Engineering Design, David Anthony Harney

Doctoral Dissertations

"The design of chemical engineering process equipment routinely necessitates the solution of large systems of non-linear equations. The processing speed of standard desktop computers have allowed for equation-oriented process simulators to become commercially viable. For a fully equation-oriented simulator to be competitive with standard iterative solvers, a robust and reliable non-linear equation solver is required and standard Newton methods fail to provide the necessary reliability.

Homotopy continuation methods have been proposed as a way to greatly expand the domain of convergence of the process simulator's equation solving algorithm. This research expands upon existing homotopy continuation algorithms, investigates bounding algorithms, corrector …

Stress Corrosion Cracking Behavior Of Friction Stir Processed Ultrafine Grained Light Metal Alloys, Gaurav Ramchandra Argade

Doctoral Dissertations

"The influence of friction stir processing (FSP), a microstructural modification tool, on the corrosion behavior of Al-Mg, Al-Mg-Sc, Mg-Al-Zn and Mg-Y-RE alloys has been studied. An attempt has been made to establish correlation between processing parameters and the subsequent microstructural evolution especially matrix grain size on the corrosion and stress corrosion properties of the alloys. A relationship between grain size and corrosion rate for Mg-Y-RE alloys was envisaged and power law type behavior was proposed. Ultrafine fine grained (UFG) microstructure showed one order magnitude lower corrosion rate.

Grain refinement achieved through different FSP parameters showed lower corrosion currents for Al-Mg …

The Effects Of Personal Protective Respirators On Human Motor, Visual, And Cognitive Skills, Anas Ahmed Alghamri

Doctoral Dissertations

"In oxygen-deficient or toxic environments in which controlling the hazard is not feasible, workers wear personal protective respirators. Hazard controls include but are not limited to engineering controls, such as ventilation, and substituting less hazardous materials. However, respirator selection and the design of tasks that require respirators are critical issues. Understanding the effects of respirators on human abilities is critical to respirator selection and therefore to the safety and efficiency of workers. This research investigated the effect of respirators on human abilities. A review of the relevant literature was conducted, revealing that respirators can affect physiological, psychological, motor, and visual …

Analyses Of Alternative Energy Deployments, Mathew Thomas

Doctoral Dissertations

"Energy use around the world is rising drastically. Fossil fuels, including liquid fuels, natural gas, and coal, are expected to supply 80% of the world's energy need in 2035. As a result, the world's energy-related carbon dioxide emission is expected to increase from 30.2 billion metric tons in 2008 to 43.2 billion metric tons in 2035. Significant steps are necessary to reduce the dependence on fossil fuel and to reduce greenhouse gas emissions. Renewable and alternative energy technologies can assist in reducing the use of fossil fuels and can reduce greenhouse gas emissions. However, most of the renewable energy technologies …

A Socio-Technical Analysis Of Widespread Electric Vehicle Adoption, Onanwa Nneka Egbue

Doctoral Dissertations

A combination of high fuel costs, concerns about petroleum availability, and environmental issues associated with conventional vehicles powered by fossil fuels are driving interests in electric vehicles (EVs). Large-scale deployment of EVs can play a significant role in addressing some of these problems. In spite of the benefits of EVs, several obstacles need to be overcome before EVs will be widely adopted. This research focuses on two socio-technical issues that affect widespread adoption and sustainability of EVs, consumer attitudes and perceptions, and supply chain risks of raw materials for EV battery technology. A major barrier is that consumers tend to …

Compressive Sensing For 3d Microwave Imaging Systems, Hamed Kajbaf

Doctoral Dissertations

"Compressed sensing (CS) image reconstruction techniques are developed and experimentally implemented for wideband microwave synthetic aperture radar (SAR) imaging systems with applications to nondestructive testing and evaluation. These techniques significantly reduce the number of spatial measurement points and, consequently, the acquisition time by sampling at a level lower than the Nyquist-Shannon rate. Benefiting from a reduced number of samples, this work successfully implemented two scanning procedures: the nonuniform raster and the optimum path.

Three CS reconstruction approaches are also proposed for the wideband microwave SAR-based imaging systems. The first approach reconstructs a full-set of raw data from undersampled measurements via …

Characterization Of Soil Variability For Reliability-Based Design, Sitenikechukwu Onyejekwe

Doctoral Dissertations

"A very carefully planned Missouri-wide field exploration and laboratory investigation program, with a focus on fine-grained soils, was executed with the aim of characterizing the variability of geotechnical parameters statistically with a view to increasing the use of reliability-based design (RBD) among geotechnical engineers. Geotechnical parameters were characterized in terms of both their first and second statistical moments and their coefficient of variation (COV). Their probability distributions and their scale of fluctuation, θ, were also determined. Correlations between difficult-to-obtain parameters and more easily-obtained parameters were developed and the degree of fit of study data to published empirical correlations was investigated. …