Engineering Commons^™

Engineering Magnetic Properties Of Nanoparticles For Biomedical Applications And Magnetic Thin Film Composite Heterostructures For Device Applications., Shivakumar Hunagund

Theses and Dissertations

The motivation of this study is to investigate the size dependent properties of Gadolinium silicide nanoparticles and their potential applications in Biomedicine. We use two approaches in our investigation - size dependence and possible exchange interaction in a core-shell structure. Past results showed Gd₅Si₄ NPs exhibit significantly reduced echo time compared to superparamagnetic iron oxide nanoparticles (SPION) when measured in a 7 T magnetic resonance imaging (MRI) system. This indicates potential use of Gd₅Si₄ ferromagnetic nanoparticles as T2 contrast agents for MRI.

Until recently most contrast agents (CA) that are used in Magnetic Resonance …

Modeling Cascading Failures In Power Systems In The Presence Of Uncertain Wind Generation, Mir Hadi Athari

Theses and Dissertations

One of the biggest threats to the power systems as critical infrastructures is large-scale blackouts resulting from cascading failures (CF) in the grid. The ongoing shift in energy portfolio due to ever-increasing penetration of renewable energy sources (RES) may drive the electric grid closer to its operational limits and introduce a large amount of uncertainty coming from their stochastic nature. One worrisome change is the increase in CFs.

The CF simulation models in the literature do not allow consideration of RES penetration in studying the grid vulnerability. In this dissertation, we have developed tools and models to evaluate the impact …

Design Of A Truck-Mounted Attenuator With Tube Folding Technology, Santosh Gautam

All ETDs from UAB

DESIGN OF A TRUCK-MOUNTED ATTENUATOR WITH TUBE FOLDING TECHNOLOGY SANTOSH GAUTAM MECHANICAL ENGINEERING ABSTRACT Highway safety features have been continuously developed and employed over the years to protect vehicle occupants, pedestrians and work zone personnel from injuries in roadside accidents. The new truck-mounted attenuator designed and evaluated in this study aims to dissipate impacting energy of the errant vehicle in a controlled manner using a tube folding mechanism. Finite element modeling using LS-DYNA is used to study the performance of the designed truck-mounted attenuator. It is required to safely bring passenger vehicles travelling at a speed of 62 mph to …

Improving Base Metal Electrowinning, Charles Ebenezer Abbey

Doctoral Dissertations

"In zinc electrowinning, Mn oxidizes to form MnO₂ on Pb-Ag anodes, cell walls and pipes. MnO₂ reduces anode corrosion but also leads to short circuits and maintenance issues. MnO₂ is thought to interact with chloride ions and produce oxidized chlorine species. The interactions between Mn and Cl are not well understood. Bench scale experiments were conducted to investigate the effects of the manganese to chloride ratio on anode corrosion rate and electrolyte chemistry using rolled Pb-Ag anodes. Increasing the average Mn/Cl^- ratio from ~7:1 to ~11:1 reduced the anode corrosion rate. Anode scales produced with Mn/Cl …

Hardware Architectures For Compact Microwave And Millimeter Wave Cameras, Matthew Jared Horst

Doctoral Dissertations

"Millimeter wave SAR imaging has shown promise as an inspection tool for human skin for characterizing burns and skin cancers. However, the current state-of-the-art in microwave camera technology is not yet suited for developing a millimeter wave camera for human skin inspection. Consequently, the objective of this dissertation has been to build the necessary foundation of research to achieve such a millimeter wave camera. First, frequency uncertainty in signals generated by a practical microwave source, which is prone to drift in output frequency, was studied to determine its effect on SAR-generated images. A direct relationship was found between the level …

Pressure Versus Impulse Graph For Blast-Induced Traumatic Brain Injury And Correlation To Observable Blast Injuries, Barbara Rutter

Doctoral Dissertations

"With the increased use of explosive devices in combat, blast induced traumatic brain injury (bTBI) has become one of the signature wounds in current conflicts. Animal studies have been conducted to understand the mechanisms in the brain and a pressure versus time graph has been produced. However, the role of impulse in bTBIs has not been thoroughly investigated for animals or human beings.

This research proposes a new method of presenting bTBI data by using a pressure versus impulse (P-I) graph. P-I graphs have been found useful in presenting lung lethality regions and building damage thresholds. To present the animal …

Military Applications Of Geological Engineering, Stephen H. Tupper

Doctoral Dissertations

"This work examines the premise that military engineering and geological engineering are intellectually paired and overlapped in practice to a significant extent. Geological engineering is an established, albeit young, academic discipline that enjoys wide industry and civil demand and is supported by many professional organizations. In contrast, military engineering is an ancient, empirically derived training or "OJT" program with practice-based trade-associations that has narrow government-only utility. The premise is formed by decades-long observation of U. S. Army military engineer officers completing a Master of Science degree in geological engineering as a complement to their practice-based training in military engineering at …

Plugging Performance Of Preformed Particle Gels In Fractures And Its Influencing Factors, Ze Wang

Doctoral Dissertations

"Preformed particle gels (PPG) has been successfully applied to combat the water channeling caused by fractures or fracture-like channels. Understanding the placement and plugging of PPG in fractures is crucial for gel treatment design. The objective of the dissertation is to explore the plugging performance of three PPG products in two types of fracture models, the partially and fully open fractures. The following studies has been conducted and conclusions have been drawn based on the results and analysis. First, the placement and plugging performance of conventional PPG was investigated using core flooding experiments conducted partially open fractures. The plugging efficiency …

Underwater Acoustic Communications And Adaptive Signal Processing, Mohammadhossein Behgam

Doctoral Dissertations

"This dissertation proposes three new algorithms for underwater acoustic wireless communications. One is a new tail-biting circular MAP decoder for full tail-biting convolution (FTBC) codes for very short data blocks intended for Internet of Underwater Things (IoUT). The proposed algorithm was evaluated by ocean experiments and computer simulations on both Physical (PHY) and Media access control (MAC) layers. The ocean experimental results show that without channel equalization, the full tail-biting convolution (FTBC) codes with short packet lengths not only can perform similarly to zero-tailing convolution (ZTC) codes in terms of bit error rate (BER) in the PHY layer. Computer simulation …

Oxide Inclusion Evolution And Factors That Influence Their Size And Morphology, Obinna M. Adaba

Doctoral Dissertations

"The evolution of oxide inclusion size distribution and the shape of the distribution during steelmaking and casting and the process variables that influence the inclusion characteristics at different stages were investigated and documented. A statistical method for transforming the 2D size distribution to their actual 3D distributions and the application of a kinetic model to determine nucleation and growth mechanisms were tested. Finally, laboratory experiments were performed to study the effects of preexisting inclusions, steel active oxygen content, and supersaturation on the size and morphology of Al₂O₃ inclusions.

The inclusion size, composition, and morphology following steel deoxidation …

Electrodeposition Of Epitaxial Metal Thin Films On Silicon For Energy Conversion And Flexible Electronics, Qingzhi Chen

Doctoral Dissertations

"This research focuses on epitaxial electrodeposition of two coinage metals: Au and Ag thin films on the silicon surface and their applications in flexible electronics and energy conversion and storage. The first paper: Photoelectrochemistry of ultrathin, semi-transparent, and catalytic gold films electrodeposited epitaxially onto n-silicon (111) describes the epitaxial electrodeposition of Au thin films on n-type Si using a simple HAuCl4 bath and the photoelectrochemical properties of the Au-Si junction barrier. The effect of the Au layer on the interfacial energetics as well as the stability of the photoelectrode as a function of the Au coverage/thickness is determined in a …

Non-Invasive Microwave And Millimeter Wave Reflectometry And Imaging For Human Skin Diagnosis And Materials Characterization, Yuan Gao

Doctoral Dissertations

"Microwave and millimeter wave reflectometry and synthetic aperture radar (SAR) imaging techniques have been successfully applied in many applications, such as nondestructive testing and evaluation (NDT&E), security inspection and medical diagnosis. In this dissertation, the feasibility of using microwave and millimeter reflectometry and SAR imaging for burn diagnosis is investigated through both simulations and measurements, with promising results. To correctly model the interaction between electromagnetic waves and skin, the proper knowledge of the complex permittivity of healthy skin is critically important. To this end, the common used measurement methods for in vivo skin complex permittivity are reviewed and analyzed in …

Nanomorphology Dependent Optical And Mechanical Properties Of Aerogels, Chandana Mandal

Doctoral Dissertations

"Aerogels are very low density, light weight open pore materials. A hypothesis that is under intense current investigation by the scientific community states that the mechanical properties of nanostructured polymers depend on their nanomorphology. Aerogels are nanostructured ultra-lightweight nanoporous materials with skeletal frameworks that can display a wide range of nanomorphologies. Thereby aerogels comprise a suitable platform for testing not only that hypothesis but also a wide range of other properties such as light scattering for applications, for example, in thermally insulating windows.

To study the mechanical properties of nanostructured matter as a function of nanomorphology, various shape-memory polyurethane aerogels …

A Systems And Cost Analysis Of Human Rated Mars Entry, Descent, And Landing Vehicles, Paul Daniel Friz

Doctoral Dissertations

"Cost is one of the biggest obstacles to sending humans to Mars. However, spacecraft costs are typically not taken into consideration until after the preliminary vehicle and mission concepts have been designed. Once costs have been estimated, managers and project teams often lack confidence that the final cost of the mission will match the preliminary estimates. The present work provides a robust methodology for using cost as a valid metric early in the design phase of future human Mars Entry, Descent, and Landing (EDL) vehicles. This is done in three parts. First, state of the art parametric costing methods are …

Reactor Configurations To Support Advanced Material Research, Thaqal Mazyad Alhuzaymi

Doctoral Dissertations

"The research goal is to configure a research reactor with multi-spectral capability for advance material research. This required the consideration of high and low-power levels alongside advanced fuel with high physical density and low enriched ²³⁵U. Selected fuel was U-10Mo with 19.75% ²³⁵U enrichment. The fuel and control rods system geometries were adopted from Missouri S&T Reactor (MSTR).

A high-power configuration (HPC) at 2 megawatts and low-power configuration (LPC) at 200 kilowatts were considered. Neutronic performances of the configurations were modeled using Monte Carlo N-particle (MCNP) transport code, version 6. Thermal-hydraulic analysis was performed with ANSYS Fluent. The …

Novel Insights Into Low Salinity Water Flooding Enhanced Oil Recovery In Sandstone Reservoirs, Hasan N. Al-Saedi

Doctoral Dissertations

"Ever growing global energy demand and the natural decline in oil production from mature oil fields have been the main incentives to search for methods to increase recovery efficiency for several decades. Water flooding is extensively applied worldwide to improve oil recovery. The recent drop in oil prices has turned the oil industry to the cheapest improved oil recovery (IOR) techniques, such as low salinity (LS) waterflooding. Also, the reduction in reservoir energy and the friendly environmental aspects of low salinity water flooding (LSWF) provide additional incentives for its use. That LS water requires decreasing only the active divalent cations …

Investigating The Performance Of High Viscosity Friction Reducers Used For Proppant Transport During Hydraulic Fracturing, Mohammed Salem Ba Geri

Doctoral Dissertations

"Over the last few recent years, high viscosity friction reducers (HVFRs) have been successfully used in the oil and gas industry across all premier shale plays in North America including Permian, Bakken, and Eagle Ford. However, selecting the most suitable fracture fluid system plays an essential role in proppant transport and minimizing or eliminating formation damage.

This study investigates the influence of the use of produced water on the rheological behavior of HVFRs compared to a traditional linear guar gel. Experimental rheological characterization was studied to investigate the viscoelastic property of HVFRs on proppant transport. In addition, the successful implication …

Development And Characterization Of Nanostructured Steels And High Entropy Alloys For Nuclear Applications, Andrew Kalevi Hoffman

Doctoral Dissertations

"Nuclear reactor materials are subjected to a harsh environment including high temperatures and radiation fluences. In order to extend the lifetime of current light water reactors (LWRs) and realize the development of advanced Gen IV nuclear reactors new materials must be developed which can withstand such an environment. This thesis involves two approaches to solving this materials problem: advanced manufacturing of current commercial alloys using severe plastic deformation (SPD) and the development of new advanced high entropy alloys (HEAs).

Because SPD is effective at achieving grain refinement, this technique was used to obtain material having a high volume fraction of …

Application Of Computational Intelligence To Explore And Analyze System Architecture And Design Alternatives, Gene Lesinski

Doctoral Dissertations

"Systems Engineering involves the development or improvement of a system or process from effective need to a final value-added solution. Rapid advances in technology have led to development of sophisticated and complex sensor-enabled, remote, and highly networked cyber-technical systems. These complex modern systems present several challenges for systems engineers including: increased complexity associated with integration and emergent behavior, multiple and competing design metrics, and an expansive design parameter solution space. This research extends the existing knowledge base on multi-objective system design through the creation of a framework to explore and analyze system design alternatives employing computational intelligence. The first research …

Multi-Body Dynamic And Finite Element Modeling Of Ultra-Large Dump Truck - Haul Road Interactions For Machine Health And Haul Road Structural Integrity, Bruno Ayaga Kansake

Doctoral Dissertations

"Haul truck capacities have increased due to their economies of scale in large-scale surface mine production systems. Ultra-large trucks impose high dynamic loads on haul roads. The dynamic loads are exacerbated by road surface roughness and truck over-loading. The dynamic forces also subject trucks to high torsional stresses, which affect truck health. Current haul road response models are 2D and use static truckloads for low capacity trucks. Existing 3D models consider the road as a two-layer system. No models capture the truck dynamic effects on haul roads and predict strut pressures during haulage.

Lagrangian mechanics was used to formulate the …

Smart Control Architecture For Microgrid Application, Vikram Roy Chowdhury

Doctoral Dissertations

"This research proposes non-linear control architectures dedicated towards improving transient response, reliability and computational burden for grid connected inverters applicable for ac micro-grids. Also this work proposes an optimization procedure applied to a small microgrid to reduce the billing cost for power incorporating battery degradation mechanism.

Three works are discussed in this research that discusses methodologies to improve the operation of a three phase grid connected inverters. The first work discusses a globally stable estimation architecture for estimating the plant parameters for a grid connected inverter during its operation. Then a Lyapunov based control architecture is utilized and online parameter …

Biomaterials For Bone Regeneration, Youqu Shen

Doctoral Dissertations

"The purpose of this Ph.D. research is to investigate and improve two classes of hydroxyapatite (HA)-based biomaterials for bone repair: calcium phosphate microspheres and bioactive silicate glass scaffolds. These biomaterials were prepared with modified compositions and microstructures and then were evaluated for bone regeneration.

The open HA microspheres with dense convex surfaces and rough and porous concave surfaces were obtained by sectioning closed hollow HA microspheres. Bone regeneration with the open HA microspheres was greater than with the closed HA microsphere at 12 weeks. Hollow biphasic calcium phosphate (BCP) microspheres have been prepared with different fractions of HA and β-TCP …

Thermomechanical Analysis Of Rock Asperity In Fractures Of Enhanced Geothermal Systems, Chao Zeng

Doctoral Dissertations

"Enhanced Geothermal Systems (EGS) offer great potential for dramatically expanding the use of geothermal energy and become a promising supplement for fossil energy. The EGS is to extract heat by creating a subsurface system to which cold water can be added through injection wells. Injected water is heated by contact with rock and returns to the surface through production well. Fracture provides the primary conduit for fluid flow and heat transfer in natural rock. Fracture is propped by fracture roughness with varying heights which is called asperity. The stability of asperity determines fracture aperture and hence imposes substantial effect on …

Improvements In Digital Image Correlation And Application In Material Mechanical Test, Yunlu Zhang

Doctoral Dissertations

"Digital image correlation (DIC) is a non-contact full-field optical measurement method. With the advantages of high accuracy, low cost, and simple implementation, it has been widely applied in the area of experimental mechanics. In this study, DIC algorithm has been improved in the aspects of the pixel-level searching method and reference frame update strategy. The feature matching based method is proposed to provide an initial guess for all points of interest with semi-subpixel level accuracy in cases with small or large translation, deformation, or rotation. The bisection searching strategy is presented to automatically adjust the frame step for varying practical …

Long Period Fiber Grating, Thin Coating Of Graphene And Silver Nanowires, And Corrosion Sensing For Life-Cycle Assessment Of Steel Structures, Chuanrui Guo

Doctoral Dissertations

"This study aims to develop and validate a compact, integrated lab-on-sensor system for simultaneous measurement of strain, temperature and corrosion-induced mass loss in steel structures and concrete reinforcement elements in order to assess their life-cycle performance. The sensing system operates based on the principle of long period fiber gratings (LPFG) that are responsive to both thermal and mechanical deformation, and the change in refractive index of any medium surrounding the optical fiber. To fabricate a LPFG sensor for strain and temperature measurement, a CO₂ laser aided fiber grating system was assembled. To enable mass loss measurement, a low pressure …

Deep Neural Network Learning-Based Classifier Design For Big-Data Analytics, Krishnan Raghavan

Doctoral Dissertations

"In this digital age, big-data sets are commonly found in the field of healthcare, manufacturing and others where sustainable analysis is necessary to create useful information. Big-data sets are often characterized by high-dimensionality and massive sample size. High dimensionality refers to the presence of unwanted dimensions in the data where challenges such as noise, spurious correlation and incidental endogeneity are observed. Massive sample size, on the other hand, introduces the problem of heterogeneity because complex and unstructured data types must analyzed. To mitigate the impact of these challenges while considering the application of classification, a two step analysis approach is …

Feasibility And Assessment Of Using Recycled Rubber For Infrastructure Applications, Ahmed A. Gheni

Doctoral Dissertations

“The United States needs to mine billions of tons of raw natural aggregate each year. At the same time, millions of scrap tires are stockpiled every year. Therefore, replacing natural aggregate with recycled crumb rubber aggregate will be beneficial to the construction industry and environment. This research aimed to investigate the feasibility of using recycled rubber in new construction applications. Based on size, recycled rubber was selected to match its natural counterpart. Different ratios of recycled crumb rubber were used as a fine aggregate replacement in concrete masonry units (CMUs) where the rubberized units showed a lower unit weight, higher …

Three-Dimensional Nanotube Arrays For Solar Energy Harvesting And Production Of Solar Fuels, Wipula P. R. Liyanage

Doctoral Dissertations

"Over the past decade extensive research has been carried out on photovoltaic semiconductors to provide a solution towards a renewable energy future. Fabricating high-efficiency photovoltaic devices largely rely on nanostructuring the photoabsorber layers due to the ability of improving photoabsorption, photocurrent generation and transport in nanometer scale. Vertically aligned, highly uniform nanorods and nanowire arrays for solar energy conversion have been explored as potential candidates for solar energy conversion and solar-fuel generation owing to their enhanced photoconversion efficiencies.

However, controlled fabrication of nanorod and especially nanotube arrays with uniform size and shape and a pre-determined distribution density is still a …

Intelligent Data-Driven Decision-Making To Mitigate Or Stop Lost Circulation, Husam Hasan Alkinani

Doctoral Dissertations

”Lost circulation is a challenging problem in the oil and gas industry. Each year, millions of dollars are spent to mitigate or stop this problem. The aim of this work is to utilize machine learning and other intelligent solutions to help to make better decision to mitigate or stop lost circulation. A detailed literature review on the applications of decision tree analysis, expected monetary value, and artificial neural networks in the oil and gas industry was provided. Data for more than 3000 wells were gathered from many sources around the world. Detailed economics and probability analyses for lost circulation treatments’ …

Computational Fluid Dynamics Modeling And Comparison Of Advanced Techniques For Heat Transfer Augmentation For Nuclear Applications, Salman Mohammed Alzahrani

Doctoral Dissertations

“Passive safety is the most important feature of NuScale’s reactor designs. Twist tape is one passive heat enhance heat technique. The present research investigated thermo-hydraulic characteristics of natural and forced convection of water under different configurations of twisted tape inserted in tube as well as NuScale rod bundles for uniform wall heat flux using computational fluid dynamics (CFD) using ANSYS Fluent 18.1. Results for twist tape inserted in tube under natural circulation showed that heat transfer enhanced and pressure drop increased to 28% and 102.8% over the plain tube respectively. Regularly spaced tapes, and different widths of the twisted tapes …