Engineering Commons^™

Dynamic Modeling, Stability Analysis, And Controller Design For Dc Distribution Systems, Reza Ahmadi

Doctoral Dissertations

"The dc distribution systems or dc microgrids are known to be best suited for integration of renewable energy sources into the current power grid and are considered to be the key enabling technology for the development of future smart grid. Dc microgrids also benefit from better current capabilities of dc power lines, better short circuit protection, and transformer-less conversion of voltage levels, which result in higher efficiency, flexibility, and lower cost. While the idea of using a dc microgrid to interface distributed energy sources and modern loads to the power grid seems appealing at first, several issues must be addressed …

Fiber Inline Pressure And Acoustic Sensor Fabricated With Femtosecond Laser, Yinan Zhang

Doctoral Dissertations

"Pressure and acoustic measurements are required in many industrial applications such as down-hole oil well monitoring, structural heath monitoring, engine monitoring, study of aerodynamics, etc. Conventional sensors are difficult to apply due to the high temperature, electromagnetic-interference noise and limited space in such environments. Fiber optic sensors have been developed since the last century and have proved themselves good candidates in such harsh environment. This dissertation aims to design, develop and demonstrate miniaturized fiber pressure/acoustic sensors for harsh environment applications through femtosecond laser fabrication. Working towards this objective, the dissertation explored two types of fiber inline microsensors fabricated by femtosecond …

Gas Dynamics And Heat Transfer In A Packed Pebble-Bed Reactor For The 4th Generation Nuclear Energy, Rahman Abdulmohsin

Doctoral Dissertations

"Proper analyses of axial dispersion and mixing of the coolant gas flow and heat transport phenomena in the dynamic core of nuclear pebble-bed reactors pose extreme challenges to the safe design and efficient operation of these packed pebble-bed reactors.

The main objectives of the present work are advancing the knowledge of the coolant gas dispersion and extent of mixing and the convective heat transfer coefficients in the studied packed pebble-beds. The study also provides the needed benchmark data for modeling and simulation validation. Hence, a separate effect pilot-plant scale and cold-flow experimental setup was designed, developed and used to carry …

Design, Development And Characterization Of A Novel Neutron And X-Ray Combined Computed Tomography System, Vaibhav Sinha

Doctoral Dissertations

"Visualizing the three dimensional structure of objects (e.g. nuclear fuel, nuclear materials, explosives and bio materials) and phenomena (e.g. particle tracking) can be very important in nondestructive testing applications. Computed tomography systems are indispensable tools for these types of applications because they provide a versatile non-destructive technique for analysis. A novel neutron and X-ray combined computed tomography (NXCT) system has been designed and developed at the Missouri University of Science & Technology. The neutron and X-ray combined computed tomography system holds much promise for non-destructive material detection and analysis where multiple materials having similar atomic number and differing thermal cross …

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

Doctoral Dissertations

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

A Regional Study Of Landslide Hazards And Related Features In The Upper Indus River Basin, Northern Pakistan, Muhammad Farooq Ahmed

Doctoral Dissertations

"A spatial landslide inventory is a fundamental step preparatory to developing an understanding of regional landslide hazards. The techniques honed for this regional landslide mapping study began with compiling a stitched shaded topographic map of the Upper Indus River watershed; using remotely-sensed topographic maps from Russia combined with ASTER DEM 30m resolution data. Topographic recognition keys were then employed to aid in the visual identification and delineation of past landslides, rockslide avalanches, and landslide dam sites. The first order reconnaissance level inventory excerpted 2,254 landslides (mostly deep seated translational and complex slides) along the main stem of Indus River, land …

Bio-Inspired Design, Fabrication And Testing Of Bipolar Plates For Pem Fuel Cells, Nannan Guo

Doctoral Dissertations

"The flow field of a bipolar plate distributes reactants for polymer electrolyte membrane (PEM) fuel cells and removes the produced water from the fuel cells. It greatly influences the performance of fuel cells, especially the concentration losses. Two approaches were developed to improve flow field designs in this dissertation. One is inspired by the biological circulatory structures and called bio-inspired designs, which have great potential to transport reactant efficiently and hence improve fuel cell performance. Another way is using a network-based optimization model to optimize the conventional flow field configurations, i.e., pin-type, parallel and serpentine designs, to improve flow distributions …

Common Mode Current Estimation For Cable Bundle Inside A Vehicle, Dazhao Liu

Doctoral Dissertations

"In the Section 1, it introduces a methodology to simulate the currents and fields during an air discharge ESD into a product by combining a linear description of the behavior of the DUT with a non-linear arc resistance equation. The most commonly used test standard IEC 61000-4-2 requires using contact mode discharges to metallic surfaces and air discharge mode to non-conducting surfaces. This paper proposes a method that combines the linear ESD generator full wave model and the non-linear arc model to simulate currents and fields in air discharge mode. In Section 2, when simulating surface and thin wire structures, …

Observability-Enhanced Dual-Filter Design For Attitude Estimation With Minimum Observations, Jason D. Searcy

Doctoral Dissertations

"Determining spacecraft attitude in real time using only magnetometer data presents a challenging filtering problem. A flexible and computationally efficient method for solving the spacecraft attitude using only an inexpensive and reliable magnetometer would be a useful option for satellite missions, particularly those with modest budgets. The primary challenge is that magnetometers only instantaneously resolve two axes of the spacecraft attitude. Typically, magnetometers are used in conjunction with other sensors to resolve all three axes. However, by using a filter over an adequately long orbit arc, the magnetometer data can yield full attitude, and in near real time. The method …

Finite-Horizon Optimal Control Of Linear And A Class Of Nonlinear Systems, Qiming Zhao

Doctoral Dissertations

"Traditionally, optimal control of dynamical systems with known system dynamics is obtained in a backward-in-time and offline manner either by using Riccati or Hamilton-Jacobi-Bellman (HJB) equation. In contrast, in this dissertation, finite-horizon optimal regulation has been investigated for both linear and nonlinear systems in a forward-in-time manner when system dynamics are uncertain. Value and policy iterations are not used while the value function (or Q-function for linear systems) and control input are updated once a sampling interval consistent with standard adaptive control. First, the optimal adaptive control of linear discrete-time systems with unknown system dynamics is presented in Paper I …

Interacting Stress Concentration Factors And Their Effect On Fatigue Of Metallic Aerostructures, David Warren Whitley

Doctoral Dissertations

"During fabrication of certain aerostructure components, a situation can arise where a hole is mislocated so that it interferes with a radius, chem-mill step, machined step, or some other similar detail. The interaction of stress concentration effects between a hole and step are not well understood and the resulting impact on fatigue performance is difficult to predict. There exists a need for fatigue data that can be used to determine the analysis methods for evaluation of the interaction of machined steps and fastener holes. In this dissertation, the effect of stress concentrations placed in close proximity to each other and …

Regional Geomorphic Analysis And Gis Susceptibility Mapping Of Landslides In The Blue Nile And The Tekeze River Basins Of Ethiopia, Elamin Hassan Dai Ismail

Doctoral Dissertations

"The Plateau region of Ethiopia lies within a seismically active continental extensional regime, which is being rapidly incised by the Blue Nile and the Tekeze Rivers. Extremely large landslides pose serious hazards in this highly populated region (>27 million), which is in the process of developing its hydrologic resources. This research sought to develop cost-effective methods to compile regional landslide inventory and landslide susceptibility maps, using geomorphic tools and GIS technologies. This work also sought to evaluate the relationships between landslide dams and knickpoints, caused by channel bed incision from those caused by slope failures, by utilizing identified knickpoints …

Model Based Fault Diagnosis And Prognosis Of Nonlinear Systems, Hasan Ferdowsi

Doctoral Dissertations

"Rapid technological advances have led to more and more complex industrial systems with significantly higher risk of failures. Therefore, in this dissertation, a model-based fault diagnosis and prognosis framework has been developed for fast and reliable detection of faults and prediction of failures in nonlinear systems. In the first paper, a unified model-based fault diagnosis scheme capable of detecting both additive system faults and multiplicative actuator faults, as well as approximating the fault dynamics, performing fault type determination and time-to-failure determination, is designed. Stability of the observer and online approximator is guaranteed via an adaptive update law. Since outliers can …

Numerical Analyses Of Long Carbon Fiber Reinforced Concrete Panels Exposed To Dynamic Loading, Zahra Sadat Tabatabaei

Doctoral Dissertations

"The purpose of this research was to evaluate impact and blast performance of long carbon fiber reinforced concrete experimentally and numerically. Experimental tests were conducted on plain concrete (PC), reinforced concrete, and four different types of long carbon fiber reinforced concrete (LCFRC). The results from each test were then compared to one another. This comparison indicates that adding long carbon fibers to concrete both increases the post-cracking behavior of concrete and decreases the spalls in either an impact or blast test. Among all of the fibers tested, Fiber Type B3 outperformed the other fibers, absorbing more energy during impact. Numerical …

Enamel Coated Steel Reinforcement For Improved Durability And Life-Cycle Performance Of Concrete Structures: Microstructure, Corrosion, And Deterioration, Fujian Tang

Doctoral Dissertations

"This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl …

Advances In Blind Source Separation, Christopher Osterwise

Doctoral Dissertations

"Blind Source Separation (BSS) is a classic problem that attempts to separate unknown sources from observed mixtures. A common framework of this is the Cocktail Party problem, where multiple individuals speaking in a noisy room are recorded by a configuration of microphones, with the challenge being to split the observed signals into individual conversations. This dissertation covers the evaluation of an existing algorithm known as Cascaded ICA with Intervention Alignment (CICAIA), the establishment of a new parameter for characterizing blind mixtures, and three new algorithms, of which two are capable of separating any number of sources given more microphones than …

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

Doctoral Dissertations

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

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

Doctoral Dissertations

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

Quality function …

Effect Of Dense Heat Exchanging Internals On The Hydrodynamics Of Bubble Column Reactors Using Non-Invasive Measurement Techniques, Mohammed Khloofh Al Mesfer

Doctoral Dissertations

"Given their efficiency and capital cost reduction, bubble/slurry bubble column reactors are the reactors of choice for Fischer-Tropsch (FT) synthesis, offering clean alternative fuels and chemicals. FT synthesis is an exothermic process that requires many heat exchanging tubes in order to remove heat efficiently and maintain the desired temperature and isothermal operating condition. The impact of the heat exchanging tubes (internals) on the hydrodynamics is not fully understood. Reliably designing and scaling up bubble column reactors requires proper understanding of hydrodynamics, as well as heat and mass transfer parameters.

The main objective of this work is to advance the understanding …

Minimizing Formation Damage For Preformed Particle Gels Treatment In Mature Reservoirs, Mahmoud Omran Elsharafi

Doctoral Dissertations

"This research studied the effect of preformed particle gels (PPGs) on unswept, low-permeable zones/areas. The objective was to find methods that minimized the damage caused by PPGs on unswept, low-permeable zones/areas, thus improving PPG treatment efficiency. These results can help to identify of the best PPG types, particle sizes, and brine concentrations for specific reservoirs and treatments. This study used sandstone core samples with various degrees of permeability. Two types of particle gels, a strong Daqing gel (DQ) and a weak Liquiblock™ 40k gel (40K), were used, each with a different strength.

This research included two stages. Firstly, both a …

Source Reconstructions For Ic Radiated Emissions Based On Magnitude-Only Near-Field Scanning, Ji Zhang

Doctoral Dissertations

"In this dissertation, a source reconstruction method is proposed to model the emission behavior of an IC by using magnitude-only information during near-field scanning. The phase-retrieval is accomplished during the back-forth iterations between two scanning planes of different heights. The magnitudes of fields on two planes of different heights are recorded and used to constrain the amplitude of the calculated fields during iterations. Three essential transformations among dipoles and fields are continued at each iteration step, until the convergence condition is achieved. The proposed algorithm has been verified by using a set of dipole-array as the original emitting sources, and …

Spatial Variation Of Amd Related Co₂ Emissions On Reclaimed Mine Spoil, Moagabo Mathiba

Doctoral Dissertations

"Carbon dioxide (CO₂) from acid mine drainage (AMD)-carbonate neutralization reactions in reclaimed mine spoils, can intermittently invade homes and structures constructed on or adjacent to these spoils in hazardous and even lethal concentrations (>15%) and rendering them uninhabitable. This phenomenon is beginning to be recognized as an emerging environmental, safety and health threat with potential environmental and financial liability for mine operators, developers and owners.

Like in natural soils, soil temperature and moisture, and possibly elevation are likely to influence CO₂ emissions from reclaimed mine spoils. However, mine spoil soils are heterogeneous and have significant convective transport due to …

Quantitation And Identification Of Protein S-Nitrosylation: Implication For The Progression Of Alzheimer's Disease, Siyang Wang

Doctoral Dissertations

Protein S-nitrosylation, the covalent modification of a cysteine sulfhydryl group by nitric oxide (NO), plays a critical role in post-translational modification (PTM) that regulates a large variety of cellular functions and signalling events. The nitrosylation state changes with oxidative damage and is involved in variety of cancers and neurodegeneration diseases.

Three technologies were developed for nitrosylated protein detection and identification. Capillary gel electrophoresis with laser induced fluorescence (CGE-LIF) detection was used for the detection and quantitation of nitrosylated proteins. A two-dimensional micro-electrophoresis (2D μ-CE) separations system was also built to detect nitrosylated proteins via poly (methylmethacrylate) microchips. Proteomics following nitrosylated …

Exploitation And Exploration Of Pcr In Microfluidic Systems With Gradient Temperature Environments, Ilija Pjescic

Doctoral Dissertations

The main goal of the work was to establish a wholesome picture off all relevant processes for a sample-in, answer out genetic system and to integrate the whole process on a one step device from sample collection to final result. The genetic analysis process consists of ideally three steps: sample preparation, chemical reaction, and analysis. Each of the steps is different and requires a specific environment, where sample preparation might use additives, they might later interfere with the reaction itself or lead to misleading results in the analysis phase. It was found to be quite a challenging process to synchronize …

The Contribution Of Oxidative Stress In The Protein Damage And Dna Lesion In Alzheimer's Disease Neuropathology, Cheng Zhang

Doctoral Dissertations

Glutathione (GSH) plays an essential role in the intracellular antioxidant defense against the oxidant radicals, especially the ·OH radical. To understand the early and progressive cellular changes in Alzheimer's disease (AD) development, we investigated reduced glutathione/oxidized glutathione (GSH/GSSG) status in a double mutated AD transgenic mouse model (B6.Cg-Tg), which carries Swedish amyloid precursor protein mutation (APPswe) and exon 9 deletion of the PSEN1 gene. Likewise, S-glutathionylation (Pr-SSG) is a specific post-translational modification (PTM) of cysteine residues by the addition of glutathione. S-glutathionylated proteins induced by oxidative stress play an essential role in understanding the pathogenesis of the aging …

A Novel Microfluidic Enrichment Technique For Carbonylated Proteins, Bryant C. Hollins

Doctoral Dissertations

Proteins are the building blocks of cells in living organisms, and are composed of amino acids. The expression of proteins is regulated by the processes of transcription and translation. Proteins undergo post-translational modifications in order to dictate their role physiologically within a cell.

Not all post-translational modifications are beneficial for the protein or the cell. One type of post-translational modification, called carbonylation, irreversibly places a carbonyl group onto an amino acid residue, most commonly proline, lysine, arginine, and threonine. This modification can have severe consequences physiologically, including loss of solubility, loss of function, and protein aggregation.

Carbonylated proteins have commonly …

Oscillator-Based Neuronal Modeling For Seizure Progression Investigation And Seizure Control Strategy, Wu Chen

Doctoral Dissertations

The coupled oscillator model has previously been used for the simulation of neuronal activities in in vitro rat hippocampal slice seizure data and the evaluation of seizure suppression algorithms. Each model unit can be described as either an oscillator which can generate action potential spike trains without inputs, or a threshold-based unit. With the change of only one parameter, each unit can either be an oscillator or a threshold-based spiking unit. This would eliminate the need for a new set of equations for each type of unit. Previous analysis has suggested that long kernel duration and imbalance of inhibitory feedback …

A Hybrid Brain-Computer Interface Based On Motor Intention And Visual Working Memory, Ching-Chang Kuo

Doctoral Dissertations

Non-invasive electroencephalography (EEG) based brain-computer interface (BCI) is able to provide alternative means for people with disabilities to communicate with and control over external assistive devices. A hybrid BCI is designed and developed for following two types of system (control and monitor).

Our first goal is to create a signal decoding strategy that allows people with limited motor control to have more command over potential prosthetic devices. Eight healthy subjects were recruited to perform visual cues directed reaching tasks. Eye and motion artifacts were identified and removed to ensure that the subjects' visual fixation to the target locations would have …

Real-Time Analysis Of Brain Tumor Cell Dynamics: Novel Thermoelectric Detection Of L-Glutamate And Cell Metabolism Using Microfluidics, Siva Mahesh Tangutooru

Doctoral Dissertations

This study describes the design, fabrication and applications of a novel thermoelectric microfluidic bio-sensor. The bio-sensor is used for real time detection of the L-glutamate (L-glu) dynamics and metabolism for brain tumor cells immobilized in a microfluidic device. The microfluidic device is fabricated using a polymer/glass laminating technique (Xurography). An antimony-bismuth thin-film thermopile (primary sensing element) is integrated to the microfluidic device. The brain tumor cells are immobilized over the thermopile covering measuring and reference junctions of the thermopile using a poly-l-lysine coating layer. L-glutamate oxidase (L-GLOD) is immobilized over the measuring junctions of the thermopile prior to the immobilization …

Low Power Data Acquisition For Microimplant Biometric Monitoring Of Tremors, Tania Khanna '01

Doctoral Dissertations

In recent years, trends in the medical industry have created a growing demand for implantable medical devices. In particular, the need to provide doctors a means to continuously monitor biometrics over long time scales with increased precision is paramount to efficient healthcare. To make medical implants more attractive, there is a need to reduce their size and power consumption. Small medical implants would allow for less invasive procedures, greater comfort for patients, and increased patient compliance. Reductions in power consumption translate to longer battery life. The two primary limitations to the size of small medical implants are the batteries that …