Digital Commons Network^™

Optimal Adaptive Control Of Time-Delay Dynamical Systems With Known And Uncertain Dynamics, Rohollah Moghadam

Doctoral Dissertations

"Delays are found in many industrial pneumatic and hydraulic systems, and as a result, the performance of the overall closed-loop system deteriorates unless they are explicitly accounted. It is also possible that the dynamics of such systems are uncertain. On the other hand, optimal control of time-delay systems in the presence of known and uncertain dynamics by using state and output feedback is of paramount importance. Therefore, in this research, a suite of novel optimal adaptive control (OAC) techniques are undertaken for linear and nonlinear continuous time-delay systems in the presence of uncertain system dynamics using state and/or output feedback. …

Magnetic Control Of Transport Of Particles And Droplets In Low Reynolds Number Shear Flows, Jie Zhang

Doctoral Dissertations

“Magnetic particles and droplets have been used in a wide range applications including biomedicine, biological analysis and chemical reaction. The manipulation of magnetic microparticles or microdroplets in microscale fluid environments is one of the most critical processes in the systems and platforms based on microfluidic technology. The conventional methods are based on magnetic forces to manipulate magnetic particles or droplets in a viscous fluid.

In contrast to conventional magnetic separation method, several recent experimental and theoretical studies have demonstrated a different way to manipulate magnetic non-spherical particles by using a uniform magnetic field in the microchannel. However, the fundamental mechanism …

History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez

Doctoral Dissertations

”Water is essential for human subsistence. Stable freshwater supplies are needed as a source of food, drinking water, for transportation, recreation and economic development. Despite their recognized importance, anthropogenic activities have altered freshwater ecosystems around the world. Lake Izabal is the habitat for diverse aquatic species of flora and fauna, some of which are endemic and endangered. Its importance notwithstanding, anthropogenic activities developed in Lake Izabal’s catchment in recent years have compromised its status. This study used paleolimnological techniques to link past and recent anthropogenic activities such as mining operations and recent tilapia aquaculture. Relative abundances and concentrations of Pb, …

Tools To Evaluate Nanodiamond-Mediated Delivery Of Tiopronin For Cataract Prevention, Justin Beltz

Doctoral Dissertations

”There is a growing demand for non-surgical means of cataract treatment. This dissertation presents three bodies of work that reflect the early-stage development of eye drop formulations aimed at delaying cataract progression. These formulations consist of the antioxidant 2-mercaptopropionylglycine (MPG) loaded onto nanodiamond particles.

Cataractogenesis is linked to oxidative damage to lens proteins. To investigate the potential of MPG for protection against oxidative damage, A549 cells were incubated in 0.6 mM tert-butylhydroperoxide (tBHP). Cells exposed to tBHP without MPG exhibited elevated levels of reactive oxygen species, which led to the depletion of the vital antioxidant glutathione and, ultimately, apoptosis. Co-administration …

Finite Time Suboptimal Control Design Of Nonlinear Systems With Θ-D Technique And Implementation To Aerospace Applications, Jie Yao

Doctoral Dissertations

“A finite time suboptimal control strategy (named θ - D approximated algorithm) was proposed in this study, which can provide the control engineers with a novel effective and efficient design tool from the finite time optimal perspective. Based on the framework of this proposed method, the original nonlinear dynamics were formulated in pseudo-linear form, and the performance index was denoted by a linear quadratic regulator prototype in this research. After that, the approximated solutions to intractable Hamilton-Jacobi-Bellman (HJB) equation were acquired by putting vanishing perturbation terms into the performance index. By tuning the parameters in perturbation terms, semi-global stability and …

A Reanalyses Of Intercorrelational Matrices Of Visual And Verbal Learners' Abilities, Cognitive Styles, And Learning Preferences, Jeanette Marie Fox

Doctoral Dissertations

In psychology and education, the visual-verbal conceptual distinction is a widely studied bipolar contrast, and this distinction has been the subject of much debate. There are two main issues: One is a construct-validity issue related to the extent that scores from a test measuring the visual- and verbal-conceptual distinction accurately reflect the construct being measured, and the second one is an issue related to the use of different data analysis methods that collect and analyze the data from the visual and verbal measurements. To help resolve these issues, this study examined 21 individual intercorrelation matrices that were illustrative of the …

Decolonizing Education: Using Mother Tongue And English Side By Side In Nigeria, Omobola Wusu

Doctoral Dissertations

Nigerians lack access to effective mother tongue education (MTE) at all levels of their schooling. It is well established that cognitive and educational benefits are achieved if one’s mother tongue (MT) is used as the medium of education. This study aimed to determine how adult Nigerians around the world who had been deprived of using their mother tongues (MTs) in their education reflect on their past experiences with negative messages or colonial language ideologies received in school. Also, it explored how these past experiences have shaped their positive MT identities, their MT experiences, and their perspectives on MTE. In this …

Exploring Wellbore And Reservoir Temperature Profiles In Fluid Circulation And Production Operations, Ahmed Qasim Al Saedi

Doctoral Dissertations

"The wellbore heat flow occurs during different well operations resulting from any temperature differences between the wellbore fluid and the adjacent formation. Understanding the direction and mechanism of heat flow whether it is conduction or convection help to represent this heat exchange mathematically. However, the only available factor used to understand the heat flow behavior is the measured wellbore temperature which can be obtained from the direct measurement while drilling or circulation operations, well logging, well test, or from the production operations. Also, the initial geothermal formation temperature resulting from the geothermal gradient will help to understand the undistributed formation …

Geophysical Assessment Of The Lake Chesterfield Site, Missouri, Diya Ali Ahmad Alfuqara

Doctoral Dissertations

"Since construction of the Lake Chesterfield, Missouri in 1986, significant leaks have occurred causing the lake to lose substantive volumes of water. Mitigation efforts, have not solved the problem. Indeed, in June of 2017, the water level in Lake Chesterfield dropped at an alarmingly rapid rate. Prior to authorizing additional mitigation work, the Lake Chesterfield. Home Owners Association (LCHOA) decided to acquire geophysical data across the drained and dry lake bed. These information would help a geotechnical engineering firm determine the most appropriate mitigation plan.

In the summer of 2018, electrical resistivity tomography, multichannel analysis of surface wave, and spontaneous-potential …

Operation And Analysis Of High-Voltage-Gain Dc-Dc Converters With Voltage Multipliers, Mohammad Rashed M. Altimania

Doctoral Dissertations

"This research analyzes and investigates the steady-state operations of four different high-voltage-gain step-up dc- dc converters to achieve a high gain. These topologies consist of a two-phase interleaved boost stage with three various voltage multiplier (VM) stages. The first stage of the first three topologies is the same, which is a two-phase interleaved boost stage implemented by using inductors. The first family used in this research is based on a modified Dickson charge pump voltage multiplier stage, and this family has been studied in discontinuous conduction mode (DCM). The second family relies on a non-inverting or inverting diode-capacitors voltage multiplier …

Investigating The Factors Impacting The Success Of Immiscible Carbon Dioxide Injection In Unconventional Shale Reservoirs: An Experimental Study, Sherif M. Fakher

Doctoral Dissertations

"Unconventional shale reservoirs are currently gaining significant interest due to the huge hydrocarbon volumes that they bear. Enhanced oil recovery (EOR) techniques have been suggested to increase recovery from shale reservoirs. One of the most promising EOR methods is gas EOR (GEOR), most notably carbon dioxide (CO₂). Not only can CO₂ increase oil recovery by interacting with the oil and the shale, but it has also been shown to adsorb to the shale rock and thus is effective in both EOR applications and also carbon storage purposes. This research aims to experimentally investigate several of the interactions …

Computational Model For Neural Architecture Search, Ram Deepak Gottapu

Doctoral Dissertations

"A long-standing goal in Deep Learning (DL) research is to design efficient architectures for a given dataset that are both accurate and computationally inexpensive. At present, designing deep learning architectures for a real-world application requires both human expertise and considerable effort as they are either handcrafted by careful experimentation or modified from a handful of existing models. This method is inefficient as the process of architecture design is highly time-consuming and computationally expensive.

The research presents an approach to automate the process of deep learning architecture design through a modeling procedure. In particular, it first introduces a framework that treats …

Observer-Based Event-Triggered And Set-Theoretic Neuro-Adaptive Controls For Constrained Uncertain Systems, Abdul Ghafoor

Doctoral Dissertations

"In this study, several new observer-based event-triggered and set-theoretic control schemes are presented to advance the state of the art in neuro-adaptive controls. In the first part, six new event-triggered neuro-adaptive control (ETNAC) schemes are presented for uncertain linear systems. These comprehensive designs offer flexibility to choose a design depending upon system performance requirements. Stability proofs for each scheme are presented and their performance is analyzed using benchmark examples. In the second part, the scope of the ETNAC is extended to uncertain nonlinear systems. It is applied to a case of precision formation flight of the microsatellites at the Sun-Earth/Moon …

Experimental And Modeling Studies Using Packed Bed Reactors: Liquid Phase Ethylene Production By Hydrogenation Of Acetylene, Humayun Shariff

Doctoral Dissertations

"Gas-phase catalytic hydrogenation of acetylene to produce ethylene, commonly practiced in industries, has green oil formation, which leads to catalyst deactivation and sometimes reactor runaway risks due to high exothermicity. To overcome these issues as well as to increase the selectivity and conversion, liquid-phase hydrogenation of acetylene was investigated in packed bed reactors (PBR) using a commercial catalyst. The reactor performance of two-phase flow PBRs was assessed experimentally complemented by a validated mathematical model at different scales.

The selective hydrogenation of acetylene in the liquid phase over a commercial 0.5 wt% Pd/Al₂O₃ catalyst was investigated in a …

Stabilization Dynamics Of The Ozone Molecular System, Sangeeta Sur

Doctoral Dissertations

"The observation of larger-than-expected concentrations of heavier isotopologues of ozone known as 'ozone isotopic anomaly' in the stratosphere is a mass-independent effect (in contrast to most kinetic isotope effects familiar to chemists) that is traced back to the recombination process in the formation of ozone in the Chapman cycle. Understanding the relative efficiencies (often approximated as equal for different isotopologues) of the stabilization step (some of the details of which are still a mystery) which involves energy transfer from a highly excited ozone molecule to a third body, M (argon atom in this case) to form stable ozone is a …

A Broad Iceland Plume Associated With Two Phase Transitions At The 660 Km Discontinuity: Constraints From Receiver Functions, Dan Wang

Doctoral Dissertations

"In spite of the fact that Iceland is frequently regarded as the archetypal example of mantle plumes, the existence, depth extent, origin, dimension and excess temperature of the hypothesized plume remain enigmatic and hotly debated. The controversy mostly originates from the limited vertical resolution of seismic tomography techniques and the associated uncertainty in the depth and lateral extents of the lower wavespeed anomaly. Here we utilize a robust receiver-function-based technique to image the topography of the 410 and 660 km discontinuities bordering the mantle transition zone beneath Iceland and surrounding oceanic regions, and construct thermal and seismic wavespeed models of …

Seismological Investigations Of Lithospheric Structure Beneath The East African Rift System And The Kalahari Craton, Tuo Wang

Doctoral Dissertations

"In spite of numerous geophysical studies have been conducted in East African Rift System and Southern Africa, the structure and evolution of the crust and upper mantle are still controversial. In this study, we applied multiple seismological techniques to investigate the structure in the crust and uppermost mantle beneath the East African Rift System and Kalahari Craton in southern Africa. First, the technique of ambient noise tomography was applied to image shear wave velocity model from surface to the depth of 40 km beneath the Malawi and Luangwa rift zones. For the first time, a high-resolution 3-D shear wave velocity …

Trajectory Control Of A Wheeled Robot Using Interaction Forces For Intuitive Overground Human-Robot Interaction, George Leno Holmes Jr.

Doctoral Dissertations

"Effective and intuitive physical human robot interaction (pHRI) requires an understanding of how humans communicate movement intentions with one another. It has been suggested that humans can guide another human by hand through complex tasks using force information only. However, no clear and applicable paradigm has been set forth to understand these relationships. While the human partner can readily understand and adhere to this expectation, it would be difficult for anyone to explain their intuitive motions with strict rules, algorithms, or steps. Uncovering such a procedural framework for the control of robotic systems to execute expected performance simply from force …

An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas

Doctoral Dissertations

”The Zubair Formation is the most prolific reservoir in Iraq, which is comprised of sandstones interbedded with shale sequences. Due to the weak nature of the shale sequence, the instability of a wellbore is one of the most critical challenges that continuously appears during drilling across this formation. Historically, over 90% of wellbore problems in the Zubair Formation were due to wellbore instability. Problems associated with wellbore instability, such as tight hole, shale caving, stuck logging tools along with subsequent fishing, stuck pipe, and sidetracking result in increasing the non-productive time. This non-productive time has cost an enormous amount of …

Characterization Of Neutron Irradiated Accident Tolerant Nuclear Fuel Cladding Silicon Carbide & Radiation Detector Deadtime, Bader Almutairi

Doctoral Dissertations

“In part I, the pulse shape characteristics generated by a Geiger Muller (GM) detector and recorded by an oscilloscope manually, were investigated. The objective of part I was (1) to find a correlation between pulse shape and the operating voltage; and (2) to assess if pulse shape properties followed distinct patterns comparable to detector deadtime findings reported by a previous study. It was observed that (1) there is a strong correlation between pulse shape and operating voltage, and (2) pulse shape falls in three distinct regions similar to detector deadtime. Furthermore, parts II and III are companions and share the …

Modeling A Nuclear Research Reactor And Radiation Dose Estimation In An Accident Scenario, Abdulaleem Abdulmajeed Bugis

Doctoral Dissertations

“A detailed, flexible three-dimensional (3D) model of the Missouri S&T Reactor (MSTR) with a heterogeneous core geometry was developed using the Standardized Computer Analyses for Licensing Evaluation (SCALE). A Graphical User Interface (GUI) was developed for SCALE, which allows the user to generate an input file automatically. The SCALE model was validated with a Monte Carlo N-Particle Transport (MCNP) model of the MSTR. The validation process was based on the criticality calculations using the Criticality Safety Analysis Sequence (CSAS6). Three geometrical models were examined. The SCALE model that has the full detailed geometry showed a good agreement with the MCNP …

Development Of A System Architecture For The Prediction Of Student Success Using Machine Learning Techniques, Tatiana A. Cardona

Doctoral Dissertations

“ The goals of higher education have evolved through time based on the impact that technology development and industry have on productivity. Nowadays, jobs demand increased technical skills, and the supply of prepared personnel to assume those jobs is insufficient. The system of higher education needs to evaluate their practices to realize the potential of cultivating an educated and technically skilled workforce. Currently, completion rates at universities are too low to accomplish the aim of closing the workforce gap. Recent reports indicate that 40 percent of freshman at four-year public colleges will not graduate, and rates of completion are even …

Understanding The Deformation Mechanisms In Ni-Based Superalloys With Using Crystal Plasticity Finite Element Method, Tianju Chen

Doctoral Dissertations

“Ni-based superalloy is considered as a good candidate due to its excellent resistance to elevated temperature deformation for long term period application. Understanding the deformation and failure mechanisms of Ni-Based superalloys is very helpful for providing design guidelines for processing Ni-based superalloys. Experimental characterization indicates that the deformation mechanisms of Ni based superalloy is strongly microstructure dependent. Besides, damage transform from the void nucleation to the macro cracks by voids growth leading to the failure of the Ni-based superalloys are also showing strong microstructure sensitivity. Therefore, this work focuses on the prediction and comprehension of the deformation and void growth …

Symmetry-Breaking In The Multi-Photon Ionization Dynamics Of Oriented Atoms, Aruma Handi Nishshanka Chandrajith De Silva

Doctoral Dissertations

“Laser cooling and trapping, femtosecond light creation, and coincident electron and ion momentum imaging was combined in a world-wide unique experimental setup. These state-of-the-art techniques were used to control atomic systems and analyze the few-body quantum dynamics in multi-photon ionization of lithium. An all-optical, near-resonant laser atom trap (AOT) was developed to prepare a lithium gas at milli-Kelvin temperatures. The atoms can be resonantly excited to the state 2² P_3/2(ml = +1) with a high degree of polarization and are used as a target to study atomic multi-photon ionization in the field of an intense laser source …

Synthesis And Thermodynamic Characterization Of Free And Surface Water Of Colloidal Unimolecular Polymer (Cup) Particles Utilizing Dsc And Tga, Peng Geng

Doctoral Dissertations

“Colloidal Unimolecular Polymer (CUP) is spheroidal nanoscale polymer particle (3-9 nm) with charged hydrophilic gruops on the surface and a hydrophobic core. The formation of CUPs involves a simple free radical polymerization and a water reduction process. CUPs are thermodynamically stable in water, molecular weight, particle size and charge density can be designed and controlled. CUPs have a layer of surface associated water, due to the small particle size, the surface water/CUP volume ratio is ultra-high. Therefore, CUP is a very promising candidate to investigate the thermodynamic of surface water characteristics. In addition, CUP solution is free of surfactant and …

Applications Of Information Theory In Filtering And Sensor Management, Matthew James Gualdoni

Doctoral Dissertations

“A classical sensor tasking methodology is analyzed in the context of generating sensor schedules for monitoring resident space objects (RSOs). This approach, namely maximizing the expected Kullback-Leibler divergence in a measurement update, is evaluated from a probabilistic perspective to determine the accuracy of the conventional approach. In this investigation, a newdivergence-based approach is proposed to circumvent themyopic nature of the measure, forecasting the potential information contribution to a time of interest and leveraging the system dynamics and measurement model to do so. The forecasted objective exploits properties of a batch measurement update to frequently exhibit faster optimization times when compared …

Predicting Complex System Behavior Using Hybrid Modeling And Computational Intelligence, Vinayaka Gude

Doctoral Dissertations

“Modeling and prediction of complex systems is a challenging problem due to the sub-system interactions and dependencies. This research examines combining various computational intelligence algorithms and modeling techniques to provide insights into these complex processes and allow for better decision making. This hybrid methodology provided additional capabilities to analyze and predict the overall system behavior where a single model cannot be used to understand the complex problem. The systems analyzed here are flooding events and fetal health care. The impact of floods on road infrastructure is investigated using graph theory, agent-based traffic simulation, and Long Short-Term Memory deep learning to …

Multi-Physics-Based Approach To Active Microwave Thermography, Seyed Ali Mirala

Doctoral Dissertations

“The goal of this work is to advance a novel nondestructive testing (NDT) method for controlled, rapid, and effective inspection of a structure through the integration of microwave NDT and thermography, referred to as Active Microwave Thermography (AMT). In AMT, the structure under test is exposed to microwave radiation and the thermal profile of the structure is monitored via a thermal camera in order to obtain desired information regarding the structure. This new technique is applicable across a wide range of NDT needs including detection of voids, delamination, water ingress, debonding, and cracks in numerous structures such as carbon fiber …

Accurate Modeling Techniques For Power Delivery, Jingdong Sun

Doctoral Dissertations

“Power delivery is essential in electronic systems to provide reliable power from voltage sources to load devices. Driven by the ambitious user demands and technology evolutions, the power delivery design is posed serious challenges. In this work, we focus on modeling two types of power delivery paths: the power distribution network (PDN) and the wireless power transfer (WPT) system.

For the modeling of PDN, a novel pattern-based analytical method is proposed for PCB-level PDN impedance calculations, which constructs an equivalent circuit with one-to-one correspondences to the PCB’s physical structure. A practical modeling methodology is also introduced to optimize the PDN …

Human Behavior Understanding For Worker-Centered Intelligent Manufacturing, Wenjin Tao

Doctoral Dissertations

“In a worker-centered intelligent manufacturing system, sensing and understanding of the worker’s behavior are the primary tasks, which are essential for automatic performance evaluation & optimization, intelligent training & assistance, and human-robot collaboration. In this study, a worker-centered training & assistant system is proposed for intelligent manufacturing, which is featured with self-awareness and active-guidance. To understand the hand behavior, a method is proposed for complex hand gesture recognition using Convolutional Neural Networks (CNN) with multiview augmentation and inference fusion, from depth images captured by Microsoft Kinect. To sense and understand the worker in a more comprehensive way, a multi-modal approach …