Engineering Commons^™

Optimal Excitation Controllers, And Location And Sizing Of Energy Storage For All-Electric Ship Power System, Chuan Yan

Doctoral Dissertations

"The Navy's future all-electric ship power system is based on the integrated power system (IPS) architecture consisting of power generation, propulsion systems, hydrodynamics, and DC zonal electric distribution system (DC-ZEDS). To improve the power quality, optimal excitation systems, and optimal location and sizing of energy storage modules (ESMs) are studied. In this dissertation, clonal selection algorithm (CSA) based controller design is firstly introduced. CSA based controller design shows better exploitation ability with relatively long search time when compared to a particle swarm optimization (PSO) based design. Furthermore, 'optimal' small population PSO (SPPSO) based excitation controller is introduced. Parameter sensitivity analysis …

Intelligent Power System Operation In An Uncertain Environment, Yusuf Yare

Doctoral Dissertations

"This dissertation presents some challenging problems in power system operations. The efficacy of a heuristic method, namely, modified discrete particle swarm optimization (MDPSO) algorithm is illustrated and compared with other methods by solving the reliability based generator maintenance scheduling (GMS) optimization problem of a practical hydrothermal power system. The concept of multiple swarms is incorporated into the MDPSO algorithm to form a robust multiple swarms-modified particle swarm optimization (MS-MDPSO) algorithm and applied to solving the GMS problem on two power systems. Heuristic methods are proposed to circumvent the problems of imposed non-smooth assumptions common with the classical approaches in solving …

Phosphate Post-Treatment Of Cerium-Based Conversion Coatings On Al 2024-T3, Daimon K. Heller

Doctoral Dissertations

"Phosphate post-treatment of cerium-based conversion coatings (CeCCs) on high strength aluminum alloys can significantly improve corrosion resistance. As-deposited CeCCs exhibit corrosion pits and salt tails across the specimen surface after 3 days of exposure, but post-treated CeCCs have withstood 14 days of salt spray exposure without visibly corroding. The morphology, phase, and electrochemical properties of spray deposited CeCCs were affected by post-treatment parameters such as immersion time, solution temperature, and phosphate source. The best performing coatings were post-treated in aqueous orthophosphate solutions for at least 5 min at temperatures of at least 85⁰C. These conditions converted cerium hydroxy/peroxy species in …

Ultracapacitor Character Analysis And Its Application In Unified Power Quality Conditioner As Energy Storage System, Xiaomeng Li

Doctoral Dissertations

"This dissertation focuses on the Ultracapacitor (UCAP) character analysis and its application in Unified Power Quality Conditioner (UPQC) as an Energy Storage System (ESS) for improved UPQC performance. It includes three parts as described below. The first part is Paper I. The UCAP is a popular choice for the ESS because of its distinct characters. In the application UCAP's transient behavior need to be studied for design purpose. Usually these transient characters are not shown in the product data sheet. In this paper UCAP frequency analysis is performed, and based on the test data the equivalent model of the UCAP …

Scaled Experimental Study On Excavation Of Lunar Regolith With Rakes/Rippers And Flat Blade, Masafumi Iai

Doctoral Dissertations

"As humanity's activities expand to the Moon, Mars, and other extra-terrestrial bodies, it will be necessary to use local resources rather than bringing everything from the Earth. This concept is called In-Situ Resource Utilization (ISRU), which starts with excavation and earthmoving. The present study focuses on loosening and moving of the lunar regolith by a ripper (or rake) and a wide blade with consideration of gravel content. After characterizing the lunar regolith and two of its simulants (JSC-1A and FJS-1), the relationship between the excavation energy and different conditions, namely gravel content, relative density, and tine spacing on a rake, …

Synthesis And Characterization Of Conducting Polymer Nanostructures And Their Application In Sensors, Zhe-Fei Li

Doctoral Dissertations

"A one-step synthesis technique has been used to fabricate sensors by growing polyaniline nanofibers and polyaniline/metal nanocomposites in the active area of an interdigitated electrode array. Polyaniline nanofiber sensors can be fabricated by irradiating an aqueous precursor solution containing aniline, HCl, a metal salt, and ammonium persulfate (APS) with a high pressure Hg lamp. The sensors are ready for operation after polymerization is complete, and no additional processing steps are necessary. These sensors showed faster and more intensity response to various organic vapors than conventional bulk polyaniline sensors due to their larger surface area. A chemisorption model and a diffusion …

Advanced Dynamic Response Improvement Methods For Dc-Dc Power Electronic Converters, Lisheng Shi

Doctoral Dissertations

"Dc-dc power electronic converters supplying electric power to digital processors, data centers, and telecommunication systems are required to exhibit a fast dynamic response in response to their instantaneous electric load variations. This requirement is becoming more and more stringent as the operating voltage of such loads is continuously reducing. This voltage level reduction has reached a point where conventional control approaches can barely meet the dynamic response demanded by such loads. In order to overcome this issue, several approaches focusing on the dynamic response improvement for dc-dc converters have been proposed in the literature. Unfortunately, most of them have at …

Dynamic Reconfiguration And Control Of Smart Power Systems, Pinaki Mitra

Doctoral Dissertations

"To address the increasing demand and complexity, modern power systems need intelligence at almost all levels which can transform them into 'smart' power systems. The term 'smart power systems' not only refers to the terrestrial power systems with a significant penetration of distributed energy resources and energy storage such as plug-in electric vehicle parking lots (SmartParks), but also includes other isolated power systems, such as the power systems of naval electric ships. The research presented in this dissertation contributes to the dynamic reconfiguration and control of both terrestrial and ship power system with the application of computational intelligence methods.

In …

Emerging Technology Supply Chain Model For Additive Manufacturing, David M. Dietrich

Doctoral Dissertations

"This research concerns developing an emerging manufacturing technology, additive manufacturing (AM), into a mature and flexible, cost-effective supply chain for aerospace production. The field of additive manufacturing is an approach to low volume manufacturing of plastic or metal parts using three dimensional Computer Aided Design data. As an emerging technology, AM's supply chain is not established compared to conventional aerospace manufacturing technologies, such as injection molding or composite manufacturing. Technical and business challenges limit the robustness of the additive manufacturing system for aerospace applications. The overall intent of this research is to: first, provide an introduction to two main polymer …

Improvised Explosive Device Crater Repair For Enduring Route Remediation, Daniel Roman Kienitz

Doctoral Dissertations

"Recent road repairs performed on main supply routes (MSRs) and alternative supply routes (ASRs) in Iraq and Afghanistan revealed several deficiencies in current repair techniques. Temporary solutions such as aggregate backfill, asphalt, and traditional concrete repairs were unacceptable due to the ease of emplacement of additional improvised explosive devices (IEDs). In addition to the threat of IED placement, the threat from exposure of the repair teams to enemy attack during placement and curing was substantial. In order to address these problems, this project investigated rapid hardening materials for improvised explosive device crater repair. A laboratory test program along with performance …

Transient Study Of The Wetting Films In Porous Media Using 3d X-Ray Computed Micro-Tomography: Effect Of Imbibition Rate And Pore Geometry, Pradeep Bhattad

LSU Doctoral Dissertations

Imbibition in porous media is governed by the complex interplay between viscous and capillary forces, pore structure and fluid properties. Understanding and predicting imbibition is important in many natural and engineered applications; it affects the efficiency of oil production operations, the moisture and contaminant transport in soil science, and the formation of defects in certain types of composite materials. Majority of the studies published on the transient imbibition behavior in a porous medium were conducted in the simplified 2D transparent micromodels or the 2D projection visualization (X-ray or visible light) of the 3D porous medium. However, the pore level transient …

The Weakening Of Branch Predictor Performance As An Inevitable Side Effect Of Exploiting Control Independence, Christopher Joseph Michael

LSU Doctoral Dissertations

Many algorithms are inherently sequential and hard to explicitly parallelize. Cores designed to aggressively handle these problems exhibit deeper pipelines and wider fetch widths to exploit instruction-level parallelism via out-of-order execution. As these parameters increase, so does the amount of instructions fetched along an incorrect path when a branch is mispredicted. Many of the instructions squashed after a branch are control independent, meaning they will be fetched regardless of whether the candidate branch is taken or not. There has been much research in retaining these control independent instructions on misprediction of the candidate branch. This research shows that there is …

Membranes For Periodontal Regeneration: From Commercially Available To Spatially Designed And Functionally Graded Materials, Marco Cicero Bottino

All ETDs from UAB

The aging of the global population will lead to a considerable increase in the number of surgical and restorative procedures related to oral rehabilitation or periodontal regeneration. Periodontitis is one of the most aggressive pathologies that concern the integrity of the periodontal system that can lead to the destruction of the periodontium. Guided tissue and guided bone regeneration (GTR/GBR) have been used for the repair and regeneration of periodontal tissues by utilizing an occlusive membrane.The goal of this dissertation is to advance the knowledge in the area of periodontal regeneration by investigating the properties of a commercially available freeze-dried collagen-based …

Optical Mapping Of The Interactions Between Cardiac Geometry And Electrical Activity, Elliot B. Bourgeois

All ETDs from UAB

In healthy hearts, the synchronized spread of electrical activation drives contraction. To investigate the role of cardiac geometry in modulating normal and abnormal electrical rhythms, we stained cardiac tissues with a fluorescent, voltage sensitive dye and imaged activation patterns with fast video cameras (optical mapping). This work is presented in three projects. Computer modeling has shown that conduction velocity increases when fibers are bowed toward the oncoming wavefront and decreases when fibers are bowed in the opposite direction. In the first project, cultured monolayers of cardiac myocytes were optically mapped to experimentally verify the theoretical effect of fiber curvature on …

A Novel Approach To Dual Excitation Ratiometric Optical Mapping Of Cardiac Action Potentials With Di-4-Anepps Using Pulsed Led Excitation, Andrew Dennison Bachtel

All ETDs from UAB

We developed a new method for ratiometric optical mapping of transmembrane potential (Vm) in cardiac preparations stained with di-4-ANEPPS (DI-4). The method uses pulsed light emitting diode (LED) excitation. Vm-dependent shifts of excitation and emission spectra establish two excitation bands (<481 nm and >481 nm) that produce positive and negative changes in fluorescence within a single emission band (570-615 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases Vm sensitivity and removes artifacts common to both signals. We pulsed blue (460±20 nm) and cyan (505±20 nm) LEDs at 500 Hz in alternating phase synchronized to a photodetector (1 …

Pre-Disaster Planning For Transportation Infrastructure Recovery, Stephanie Victoria Watson

All ETDs from UAB

The US is dependent upon a functioning transportation network for many aspects of daily life, and those aspects that become largely important during times of disaster. For example, emergency medical response is a crucial activity that relies upon a functioning transportation network during regular daily operations as well as during times of emergency. The US has experienced several natural and manmade devastating events within the past decade including the September 11, 2001 terrorist attacks, Hurricanes Ivan, Katrina and Rita, and record flooding in Tennessee. When disasters occur, the potential of disrupting various infrastructures either individually or simultaneously exists. During a …

Building Occupancy And Energy Conservation In Institutional Buildings Of The University Of Alabama At Birmingham, Atul Nandkumar Kajale

All ETDs from UAB

Building occupancy and lighting surveys were conducted in various campus buildings of the University of Alabama at Birmingham (UAB) in 2007 (summer and fall semesters) and 2008 (spring and summer semesters) to investigate their energy performance. The details of the occupancy, lighting, and utility bills of the Business Engineering Complex, Humanities Building, Hill University Center, Ryals School of Public Health, and Sterne Library are discussed in this thesis. The after-hour occupancy was very low in most of the buildings surveyed and, at the same time, there were several unoccupied and fully lit rooms. In order to reduce energy waste, the …

Development Of A Multiscale Material Model For Brain Tissue And Its Application To The Impact Response Of The Human Head, Sandeep Kulathu

All ETDs from UAB

The development of a finite element model capable of predicting brain injury sustained as a result of an impact load to the head is of considerable importance not only for the development of adequate protection systems but also in deciding an appropriate mode of treatment for an individual. With advancements in imaging technologies, it is now possible to visualize the neuron fiber structures in the brain. In the first half of this project, an analytical micro-mechanical model was developed from the individual isotropic behaviors of the Cerebro-Spinal Fluid (CSF) and brain tissue present in the brain, such that the resultant …

Spin Echo Ss-Parse: A Parse Mri Method To Estimate R2, R2' And Frequency In A Single Shot, Ningzhi Li

All ETDs from UAB

Rapid and accurate mapping of relaxation rates applies to a number of neuroimaging and functional magnetic resonance imaging (fMRI) studies. Previously developed relaxation rate mapping methods are based mostly on non-linear fitting of intensity images. For the first time, this study developed an ultrafast and direct transverse relaxation rate mapping technique, Spin Echo Single-Shot Parameter Assessment by Retrieval from Single Encoding (SE-SS-PARSE). Four useful imaging parameters, local transverse magnetization magnitude (Mxy0), frequency (f), reversible and irreversible transverse re-laxation rate (R2' and R2), can be estimated using an iterative searching algorithm simul-taneously and quantitatively. In addition, the SE-SS-PARSE technique is free …

Development Of Multi-Shot Parse Mri Techniques, Rajiv G. Menon

All ETDs from UAB

Fast imaging Magnetic Resonance Imaging (MRI) techniques such as Echo Planar Imaging (EPI) often suffer from artifacts such as signal dropouts, geometric distortions and susceptibility artifacts due to background gradients. Parameter Assessment by Retrieval from Signal Encoding (PARSE) was introduced as a single shot, inverse estimation technique that models the MRI process more accurately and estimates the initial transverse magnetization, M0 and its phase, the decay rate R2* and local frequency at each pixel. This technique is devoid of the aforementioned artifacts seen in EPI techniques. The goal of this work is to develop multi-shot parameter assessment by retrieval from …

Interface Characterization Of Metal-Thermoplastic Composites, Carol Ochoa Putman

All ETDs from UAB

Hybrid materials featuring thermoplastic polymer composites in conjunction with metals can be used as structural materials in military and commercial transport vehicles and for protection of buildings and infrastructure. Constituent thermoplastics and metals have distinct advantages as protective materials; however, metals on their own are heavy; hence, hybrid materials offer an option as lighter materials. Since the optimal performance of a composite strongly depends on the behavior of the interface, the present study focuses on understanding the mechanisms of mechanical and chemical bonding as well as the effect of thermal stresses at the interface of metal-thermoplastic composites. The mechanical interactions …

Cardiovascular Endothelial Regeneration On An Electrospun Scaffold, Xing Zhang

All ETDs from UAB

A bi-layer electrospun nano-fibrous scaffold comprising synthetic polymers and natural proteins was constructed as the prototype of an arterial substitute for coronary ar-tery disease. This scaffold featured a highly porous microstructure analogous to native extracellular matrix. Uni-axial tensile test suggested that its excellent mechanical strength could restore normal blood flow immediately after implantation. Subsequent biocompati-bility study demonstrated that scaffolding materials, either traditional or degraded, were non-toxic to the regenerated human endothelium on the luminal layer. Moreover, this re-generated endothelium possessed critical functions, such as the formation of tight junc-tions, the secretion of prostacyclin, and the prevention of platelet adhesion. Thereafter, …

Bridge Weigh-In-Motion For Bridge Safety And Maintenance, Hua Zhao

All ETDs from UAB

amounts of these two nutrients. Further evaluation to identify cost effective programs to

A Framework For Composite Service Development: Process-As-A-Concept, Varadraj Prabhu Gurupur

All ETDs from UAB

This dissertation addresses the problem of bridging the gap that exists between user requirements and the implemented software solution. This gap between the user needs and the actual implementation is usually termed the semantic gap problem. In this dissertation, the software solution is viewed as a composite of available software services and seeking semantically motivated approaches for the composition of a final solution. Representing user needs by capturing the semantic components of these needs and using this representation to build a composite service solution are therefore critical in reducing the aforementioned semantic gap. Although scientists have presented solutions that contribute …

Characterization Of Explanted Endovascular Stents: A Study Of In-Vivo Corrosion And The Role Of Vascular Calcification In Stent Fracture, Dina Halwani

All ETDs from UAB

The electrochemical and mechanical stability of endovascular stents in-vivo is essential for their biocompatibility. Limited information is available regarding the condition of stents following interaction with vascular tissue, as a result, twenty seven stented vessels containing 45 stents (33 bare metal and 12 drug eluting) were retrieved during autopsy and vascular surgery. The stent/tissue components were carefully separated using a rigorous tissue dissolution protocol. Stent surfaces were characterized using 3D digital optical and scanning electron microscopy. Transferred metallic elements in dissolved tissue were measured using mass spectroscopy. Histopathologic assessment of stented tissue, when available, was also performed. Fifteen out of …

Development And Implementation Of Challenge Based Instruction In Statics And Dynamics, Robert Freeman, Horacio Vasquez, Arturo A. Fuentes, Martin Knecht, Taylor Martin, Joan Walker, Araceli Ortiz

Mechanical Engineering Faculty Publications

This paper discusses challenge-based instructional (CBI) materials developed for courses in Statics and Dynamics. This effort is a component of a funded College Cost Reduction and Access Act (CCRAA) grant from the Department of Education, and focuses on student retention and development of adaptive expertise. Studies have shown that minority science, technology, engineering, and math (STEM) students leave STEM undergraduate fields in part due to lack of real world connections to their classroom learning experiences. Furthermore, in STEM fields the conventional approach is to teach for efficiency first and for innovation only in the latter years of the curriculum. This …

Hazard Identification, Risk Assessment And Risk Control (Hirarc) In A Steel Foundry., Lee Hooi Nee

Student Works (2010-2019)

Abstract NA

Design Of An Integrated Starter-Alternator For A Series Hybrid Electric Vehicle: A Case Study In Axial Flux Permanent Magnet Machine Design, Jessica L. Colton

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This thesis details the design of an electric machine to perform as both a starter and alternator in a series hybrid electric vehicle. The focus of the work is on practical design aspects specific to single-sided axial flux permanent magnet machines with non-overlapped windings. First, a characterization of the rotor losses in these machine types is presented through experimental validation of finite element analysis estimates. The approaches taken to model the axial flux geometry, especially in two-dimensions, are detailed, and the difficult issue of validating the finite element analysis estimates with experimental data is addressed with a prototype 24-slot, 20-pole …

Modeling Biological Structures Via Abstract Grammars To Solve Common Problems In Computational Biology, David J. Russell

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Grammars are generally understood to be the set of rules that define the relationships between elements of a language. However, grammars can also be used to elucidate structural relationships within sequences constructed from any finite alphabet. In this work abstract grammars are used to model the primary and secondary structures present in biological data. These grammar models are inferred and applied to efficiently solve various sequence analysis problems in computational biology, including multiple sequence alignment, fragment assembly, database redundancy removal, and structural prediction.

The primary structures, or sequential ordering of symbols, of biological data are first modeled with Lempel-Ziv (LZ) …

Growth And Characterization Of Silicon Carbide Thin Films Using A Nontraditional Hollow Cathode Sputtering Technique, James Huguenin-Love

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Silicon carbide (SiC) is considered a suitable candidate for high-power, high-frequency devices due to its wide bandgap, high breakdown field, and high electron mobility. It also has the unique ability to synthesize graphene on its surface by subliming Si during an annealing stage. The deposition of SiC is most often carried out using chemical vapor deposition (CVD) techniques, but little research has been explored with respect to the sputtering of SiC.

Investigations of the thin film depositions of SiC from pulse sputtering a hollow cathode SiC target are presented. Although there are many different polytypes of SiC, techniques are discussed …