Engineering Commons^™

Characterization Of The Corrosion Protection Mechanism Of Cerium-Based Conversion Coatings On High Strength Aluminum Alloys, William R. Pinc

Doctoral Dissertations

"The aim of the work presented in this dissertation is to investigate the corrosion protection mechanism of cerium-based conversion coatings ( CeCCs) used in the corrosion protection of high strength aluminum alloys. The corrosion resistance of CeCCs involves two general mechanisms; barrier and active. The barrier protection mechanism was influenced by processing parameters, specifically surface preparation, post-treatment, and the use of gelatin. Post-treatment and the addition of gelatin to the coating solution resulted in fewer cracks and transformation of the coating to CeP0₄, which increased the corrosion resistance by improving the barrier aspect of CeCCs. CeCCs were found to best …

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 …

Improvement Of Eeg Based Brain Computer Interface By Application Of Tripolar Electrodes And Independent Component Analysis, Hongbao Cao

Doctoral Dissertations

For persons with severe disabilities, a brain computer interface (BCI) may be a viable means of communication, with scalp-recorded electroencephalogram (EEG) being the most common signal employed in the operation of a BCI. Various electrode configurations can be used for EEG recording, one of which was a set of concentric rings that was referred to as a Laplacian electrode. It has been shown that Lapalacian EEG could improve classification in EEG recognition, but the complete advantages of this configuration have not been established.

This project included two parts. First, a modeling study was performed using Independent Component Analysis (ICA) to …

Radiation Detectors And Sources Enhanced With Micro/Nanotechnology, Chad Michael Whitney

Doctoral Dissertations

The ongoing threat of nuclear terrorism presents major challenges to maintaining national security. Currently, only a small percentage of the cargo containers that enter America are searched for fissionable bomb making materials. This work reports on a multi-channel radiation detection platform enabled with nanoparticles that is capable of detecting and discriminating all types of radiation emitted from fissionable bomb making materials. Typical Geiger counters are limited to detecting only beta and gamma radiation. The micro-Geiger counter reported here detects all species of radiation including beta particles, gamma/X-rays, alpha particles, and neutrons. The multi-species detecting micro-Geiger counter contains a hermetically sealed …

Micro, Nano Encapsulation Methods For Sustained Release Drug Formulations And Biomimetic Applications, Shantanu Balkundi

Doctoral Dissertations

The Layer-by-Layer (LbL) assembly technique was used to obtain a new type of protein/polyphenol microcapsule based on naturally occurring polyphenol (-)-epigallocatechin gallate (EGCG) and gelatin, type A. The dependence of permeability on the molecular weight of permeating substances was studied and compared with commonly used polyallylamine/polystyrene sulfonate capsules. A quartz crystal microbalance was used to monitor the regularities of EGCG adsorption in alternation with type A and B Gelatins and electrophoretic mobility measurements were used that indicated that the nature of assembly was dependent on Gelatin properties. It was shown that EGCG retains its antioxidant activity in the LbL assemblies. …

Applications Of Electricity In The Rehabilitation And Health Monitoring Of Concrete Structures, Saiprasad Vaidya

Doctoral Dissertations

The dissertation research work presented herein consists of two separate findings: one investigates a potential new coating technique that could be used to rehabilitate deteriorated concrete sewer pipes, and the other researches inducing electrical conductivity into geopolymer concrete to serve as smart material by being able to sense stress changes. Both applications utilize electricity to enhance the performance and/or functionality of hardened cementitious materials.

Microbiologically induced corrosion (MIC) in concrete wastewater conveyance systems is a leading deterioration mechanism in such structures. This work focuses on breaking the MIC cycle by preventing colonization of the bacteria responsible for converting hydrogen sulfide …

Applied Electrokinetics For Tissue Engineering Applications, Stephanie R. Tully-Dartez

Doctoral Dissertations

Tissue engineering could provide an alternative source of transplant tissue regardless of donor supply and with reduced risk of immune rejection. Engineered tissue requires three critical components for successful development: the cells, growth factors, and the scaffold on which they will initially grow. The scaffold acts as a temporary extracellular matrix (ECM) allowing cell attachment and acclimation to the environment prior to synthesis and construction of the cell's native ECM. Prior to cell seeding, the scaffold must be characterized to determine whether or not the pore geometry is conducive to cell implantation. Electrochemical impedance spectroscopy (EIS) provides a unique and …

Computational Simulation Of Strain Localization: From Theory To Implementation, Shouxin Wu

Doctoral Dissertations

Strain localization in the form of shear bands or slip surfaces has widely been observed in most engineering materials, such as metals, concrete, rocks, and soils. Concurrent with the appearance of localized deformation is the loss of overall load-carrying capacity of the material body. Because the deformation localization is an important precursor of material failure, computational modeling of the onset and growth of the localization is indispensable for the understanding of the complete mechanical response and post-peak behavior of materials and structures. Simulation results can also be used to judge the failure mechanisms of materials and structures so that the …

Nano-Formulation And Controlled Delivery Of Low Solubility Anticancer Drugs, Anshul Agarwal

Doctoral Dissertations

Optimal drug delivery and reduction of systemic adverse effects have been age old problems in chemotherapeutics in all types of human cancer. During chemotherapy, using water insoluble drugs like paclitaxel and tamoxifen, it has been realized that better formulations are needed for more specific and controlled drug delivery of these agents. In a novel approach to form high content stable nanocolloids of these drugs with controllable release rate, a sonicated layer-by-layer (LbL) polyelectrolyte coating technology is suggested. The desired features of pharmaceutical carriers for intravenous administration include their small size and biodegradability, good loading capacity for a given drug, high …

Single-Walled Carbon Nanotube Device Fabrication Using Spin Coating Of Dispersions, Paul Jeremy Hummel

Doctoral Dissertations

This research looks at ways to utilize already synthesized carbon nanotubes (CNT) to manufacture electrical connections using current tools and fabrication methods employed in the semiconductor industry. Purchased single-walled carbon nanotubes (SWNT) are separated and placed in suspension using poly(sodium styrene sulfonate) (PSS). The PSS non-covalently bonds to the SWNTs, causing them to repel each other due to the negative charge of the PSS. The suspension of SWNTs is spin coated over a processed silicon (Si) wafer with fabricated trenches. A Si wafer with a top silicon dioxide (SiO 2) layer is spin coated with Shipley 1827 photoresist. UV light …

Chasing Μ, Joseph P. Cannon

Doctoral Dissertations

Conducting and semiconducting, π-conjugated polymers are promising materials for micro- and nano-optoelectronic applications because of their widely tunable physical, electrical, and optical properties. These polymers have been used to fabricate a number of electronic devices including field-effect transistors, light-emitting diodes, and photovoltaic cells. However, widespread commercial application of these devices has yet to be realized, due in part to poor electronic transport characteristics and device degradation.

Nanostructuring of conjugated polymers by various methods has demonstrated marked improvements in molecular ordering and electronic transport. In this research, nanoscale, tubular structures of semiconducting polymers fabricated by template wetting nanofabrication procedures are explored. …

Computational Study Of Pristine And Titanium-Doped Sodium Alanates For Hydrogen Storage Applications, Gopi Krishna Phani Dathar

Doctoral Dissertations

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained …

Chipless Rfid Sensor Tag System With Microstrip Transmissionline Based Id Generation Schemes, Sudhir Shrestha

Doctoral Dissertations

This dissertation presents a chipless radio frequency identification (RFID) sensor tag system consisting of passive chipless RFID sensor tags and specialized reader. The chipless sensor tags are fabricated on a flexible substrate and contain an ID generation circuit, a sensor, and a microstrip antenna. The ID generation circuit consists of meandered microstrip transmission lines and uses a novel reflection and delay based ID generation scheme. The scheme, using an input RF pulse, constructs an on-off keying (OOK) or pulse position modulated (PPM) signal pattern representing a unique ID code. Two transmission lines and OOK representation are used and the generation …

Infrared Light Activated Floating Micro Stimulators For Neuro-Prosthetic Applications, Kimberlyn M. Gray

Doctoral Dissertations

The most common failures in neural stimulation implants are due to interconnect complications such as tissue response, lead migration, and lead breakages. The challenge in eliminating interconnects lies in minimizing device size to maintain spatial selectivity required in the CNS. One approach to this problem is a current generating device that can be stimulated by an external signal, such as light or sound. Here, we report the design, construction and testing of rnicrophotodiode devices that can be stimulated remotely with near-infrared (NIR) light to generate current that can be injected locally into the peripheral nervous system. The use of near-infrared …

Membrane Properties Of Intact Rock Cores Of Burlington Limestone, Jefferson Dolomite, Darrington Phyllite, And Low Permeability Concrete, Megan Hart

Doctoral Dissertations

"A number of laboratory studies have shown that clays exhibit membrane properties. However, little research has been performed on lithologies outside of pure clays. Recently, research focusing on mixed sand and clay membrane properties for engineering applications was performed. Still, literature only suggests the possibilities of membrane properties, osmotic or reverse-osmotic, associated with other naturally occurring 'tight' rock types. Therefore, the objectives of this research was to perform a series of hyperfiltration experiments using actual rock discs of Quarry Ridge Jefferson Dolomite, Darrington Phyllite, Lower Burlington Limestone, and low permeability concrete to determine if tight lithologies can function as membranes"--Abstract, …

Guidance, Navigation And Control System For Autonomous Proximity Operations And Docking Of Spacecraft, Daero Lee

Doctoral Dissertations

"This study develops an integrated guidance, navigation and control system for use in autonomous proximity operations and docking of spacecraft. A new approach strategy is proposed based on a modified system developed for use with the International Space Station. It is composed of three "V-bar hops" in the closing transfer phase, two periods of stationkeeping and a "straight line V-bar" approach to the docking port. Guidance, navigation and control functions are independently designed and are then integrated in the form of linear Gaussian-type control. The translational maneuvers are determined through the integration of the state-dependent Riccati equation control formulated using …

Rational Construction By Molecular Dynamics Modeling And Simulations Of Porous Adsorbent Media For Bioseparation, Enrico Riccardi

Doctoral Dissertations

"Ion-exchange chromatography employing porous adsorbent particles or monoliths in which charged ligands are immobilized onto polymeric extender molecules grafted on the pore surfaces of a base matrix has become a very important method for bioseparations. In this dissertation, a novel fundamental and systematic methodology has been developed that uses the molecular dynamics (MD) modeling and simulation approach to rationally design, construct, and characterize polymeric porous adsorbent media and study the transport and adsorption of a charged biomolecule (desmopressin) in a representative adsorbent medium. The MD results have also been utilized in a macroscopic model to study the large-scale dynamic behavior …

On Unified Computational Intelligence: Neural Networks, Dynamic Programming, And Applications To Economics And Finance, John E. Seiffertt Iv

Doctoral Dissertations

"This dissertation introduces the concept of unified computational intelligence and encompasses algorithm design, applications, theoretical developments, and the identification of new frontiers for multidisciplinary research. It presents a new way to look at unified learning systems and presents a novel Adaptive Resonance Theory-based unified learning architecture. An application to robotic security and sensor fusion is given in detail.

Work on the theoretical developments of unified computational intelligence is also presented. A new theorem in the time scales calculus is proven and theorems on the Hamilton-Jacobi-Ballman equation of dynamic programming and the dynamic programming algorithm are presented, both for various general …

Anti Wetting Additives For Aluminosilicate Refractories In Molten Aluminum Contact Applications, Devdutt Pramod Shukla

Doctoral Dissertations

"Aluminosilicate based refractories are widely used in furnace installations for melting aluminum because they are inexpensive, readily available and generally exhibit the properties desired from a refractory material. However, they face severe corrosion and degradation issues due to the extremely reducing nature of molten aluminum alloys. Isothermal static cup testing is widely used as a tool to evaluate the performance of refractories against penetration by molten aluminum alloys. Various testing methods were reviewed and an upgraded static cup test was recommended. Commercially available aluminosilicate refractories were tested using this method and their results were studied in order to understand the …

Systematic Functional And Object-Oriented Product Design Frameworks, Jen-Chi Wu

Doctoral Dissertations

"The existing co-design methods of mechatronic products focus on co-design of mechanical and electronic components or co-design of computer hardware and software components. There exist no effective co-design methods for mechanical, electronic and software components at the concept design stage. The research objective of this dissertation work is to develop more effective systematic product design approaches for co-design of mechatronic products. Three innovative functional and object-oriented integrated design frameworks and one virtual prototyping application, which leverages on these three design frameworks, have been developed for co-design of mechatronic products. The three frameworks are: I) Hierarchical Object-Oriented Functional Modeling Framework, 2) …

A Computational Study On Novel Carbon-Based Lithium Materials For Hydrogen Storage And The Role Of Carbon In Destabilizing Complex Metal Hydrides, Mohammed Minhaj Ghouri

Doctoral Dissertations

One of the major impediments in the way of the realization of hydrogen economy is the storage of hydrogen gas. This involves both the storage for stationary applications as well as that of storage onboard vehicles for transportation applications. For obvious reasons, the system targets for the automotive applications are more stringent. There are many approaches which are still being researched for the storage of hydrogen for vehicular applications. Among them are the high pressure storage of hydrogen gas and the storing of liquid hydrogen in super insulated cryogenic cylinders. While both of them have been demonstrated practically, the high …