Engineering Commons^™

Impedance Characterization Of Ysz Based Nox Sensors, Ling Cui

Doctoral Dissertations

Yttria-stabilized zirconia has been utilized as an electrolyte of SOFC (Solid Oxide Fuel Cell) studies for years. It is also preferred as the electrolyte for solid state electrochemical sensor which is able to measure nitrogen oxides in the exhaust system. Electrochemical Impedance Spectroscopy method yields the change in impedance which is caused by an electron exchange of NO x gases at the sensing electrodes. From the EIS data, the fractional change in the phase angle is calculated for detecting sensor sensitivity.

Considering the fabrication of a sensor, several variables have been investigated which include the choice of electrolyte processing, sensing …

Improving Nano-Drug Delivery By Using Near-Real Time Sensing And Feedback, Pratik Adhikari

Doctoral Dissertations

Personalized medicine, seen as the solution to address the variability among the individuals, is the movement which proposes customization of medical procedures based on the need of the patient during the stages of prevention, diagnosis, treatment, and follow up. As the technology in medicine expands and newer methods of diagnosis and treatment are introduced in the clinic, real time data from the procedures is critical to assess the performance at point of care. Real time feedback, through collection of data at point of care would help make informed clinical decisions, potentially improving the efficacy of the treatment. In this dissertation, …

Size Specific Transfection To Mammalian Cells By Micropillar Array Electroporation, Yingbo Zu

Doctoral Dissertations

Electroporation serves as a promising non-viral gene delivery approach, while its current configurations carry drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here, we developed a new micropillar array electroporation (MAE) platform to advance the delivery of plasmid DNA and RNA to mammalian cells. By introducing well-patterned micropillar array on the electrode surface, the number of pillars each cell faces varies with its cell membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently done and contributed to a 2.5~3 fold increase on plasmid DNA transfection and …

Novel Approaches To Clustering, Biclustering Algorithms Based On Adaptive Resonance Theory And Intelligent Control, Sejun Kim

Doctoral Dissertations

"The problem of clustering is one of the most widely studied area in data mining and machine learning. Adaptive resonance theory (ART), an unsupervised learning clustering algorithm, is a clustering method that can learn arbitrary input patterns in a stable, fast and self-organizing way. This dissertation focuses on unsupervised learning methods, mostly based on variations of ART.

Hierarchical ART clustering is studied by generating a tree of ART units with GPU based parallelization to provide fast and finesse clustering. Experiment results show that the our method achieves significant training speed increase in generating deep ART trees compared with that from …

Using Wireless Sensors And Networks Program For Chemical Particle Propagation Mapping And Chemical Source Localization, Xiang Gao

Doctoral Dissertations

"Chemical source localization is a challenge for most of researchers. It has extensive applications, such as anti-terrorist military, Gas and oil industry, and environment engineering. This dissertation used wireless sensor and sensor networks to get chemical particle propagation mapping and chemical source localization. First, the chemical particle propagation mapping is built using interpolation and extrapolation methods. The interpolation method get the chemical particle path through the sensors, and the extrapolation method get the chemical particle beyond the sensors. Both of them compose of the mapping in the whole considered area. Second, the algorithm of sensor fusion is proposed. It smooths …

Integrated Geophysical Approach Using Electrical Resistivity Tomography And Multichannel Analysis Of Surface Wave In Assessing Wilson Spring Development, Ibrahim E. Ahmed

Doctoral Dissertations

"This research investigated fractured zones leading to preferential flow paths of Wilson Spring. In this context, electrical resistivity tomography (ERT) data and multi-channel analyses of surface waves (MASW) data were acquired at studied site with the purpose of mapping a variable depth to top of bedrock and geological structures.

Interpretation of the boreholes, MASW, and ERT data indicated that a depth to top of rock does vary significantly at the studied site due to many solution-widened fractures. Multiple near-vertical solution-widened fractures were mapped in the studied site based on the interpretation of the ERT data. The mapped solution-widened fractures appear …

Cable Shovel Dipper Stress And Fatigue Failure Modeling In Formation Excavation Engineering, Muhammad Azeem Raza

Doctoral Dissertations

"Large capacity shovels are used to achieve economic bulk production in surface mining operations. The suspended payload combined with dipper weight and formation resistive forces results in severe stress loading of the shovel front-end assembly. Material flaws, high stresses and harsh excavation conditions can initiate cracks in the dipper-teeth assembly. High stresses can cause these cracks to propagate to critical lengths resulting in fatigue failure, unscheduled downtimes, costly unplanned repairs, and downstream processing circuit problems. The literature reveals that dipper-related problems significantly reduce shovel up-time. This research is a pioneering effort towards developing a solid frame work for stress profiling, …

Advancing Microalgae Culturing Via Bubble Dynamics, Mass Transfer, And Dynamic Growth Investigations, Aastha Ojha

Doctoral Dissertations

"The major hindrances to large scale cultivation of microalgae are the problems associated with the design, operation, and scale-up of airlift photobioreactors (PBRs), due to a lack of a comprehensive understanding of the gas-liquid interaction process in real microalgae cultures. Thus, the overall objective of this work is to advance the fundamental understanding of microalgae culturing via gas holdup, bubble dynamics, mass transfer, and dynamic growth investigations.

First, a four-point optical fiber probe technique was employed to study the local gas holdup, and bubble dynamics properties such as bubble passage frequency, chord length and bubble velocity distribution, and interfacial area …

Development Of Implants Composed Of Bioactive Materials For Bone Repair, Wei Xiao

Doctoral Dissertations

"The purpose of this Ph.D. research was to address the clinical need for synthetic bioactive materials to heal defects in non-loaded and loaded bone. Hollow hydroxyapatite (HA) microspheres created in a previous study were evaluated as a carrier for controlled release of bone morphogenetic protein-2 (BMP2) in bone regeneration. New bone formation in rat calvarial defects implanted with BMP2-loaded microspheres (43%) was significantly higher than microspheres without BMP2 (17%) at 6 weeks postimplantation. Then hollow HA microspheres with a carbonate-substituted composition were prepared to improve their resorption rate. Hollow HA microspheres with ~12 wt. % of carbonate showed significantly higher …

Wetting Kinetics In Forced Spreading, Amer Mohammad Al-Shareef

Doctoral Dissertations

"Under dynamic conditions, the dynamic contact angle (the angle that the liquid makes with the solid) of a liquid on a solid surface varies dramatically with substrate velocity from its equilibrium value. Experimental data of the dynamic contact angles for polydimethylsiloxane (PDMS or silicone oil) under air on a glass substrate coated with teflon, for water under PDMS, for solutions of the polymer polyethylene oxide (PEO) under air, for solutions of PEO under PDMS, were obtained to simulate and understand the systems of brine or brine containing a polymer displacing viscous crude. A variety of solid substrates were used other …

Evaluating Of Scale-Up Methodologies Of Gas-Solid Spouted Beds For Coating Triso Nuclear Fuel Particles Using Advanced Measurement Techniques, Neven Y. Ali

Doctoral Dissertations

"The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking …

Modeling Of Rheological Properties For Entangled Polymer Systems, Nilanjana Banerjee

Doctoral Dissertations

"The study of entangled polymer rheology both in the field of medicine and polymer processing has their major importance. Mechanical properties of biomolecules are studied in order to better understand cellular behavior. Similarly, industrial processing of polymers needs thorough understanding of rheology so as to improve process techniques. Work in this dissertation has been organized into three major sections. Firstly, numerical/analytical models are reviewed for describing rheological properties and mechanical behaviors of cytoskeleton. The cytoskeleton models are classified into categories according to the length scales of the phenomena of interest. The main principles and characteristics of each model are summarized …

Assessment Of Highway Condition Using Combined Geophysical Surveys, Abdallah Alhadi Dera

Doctoral Dissertations

"Four pavement sections were investigated using ground penetrating radar (GPR) and Ultrasonic Surface Wave (USW). The objective of this research was to compare the effectiveness of two non-destructive geophysical tools, GPR and the PSPA, in assessing the condition of the pavements, composed of different construction materials. The GPR data were acquired using a 1.5 GHz antenna along five traverses spaced at two ft. intervals approximately 1000 ft. long. On the other hand, the PSPA data were acquired at the stations spaced at 1000 ft. along the five GPR traverses. Core samples were collected at each site to constrain the interpretation …

Dynamic Impact Of Ageing Dump Truck Suspension Systems On Whole-Body Vibrations In High-Impact Shovel Loading Operations, Saeid R. Dindarloo

Doctoral Dissertations

"Surface mining operations typically deploy large shovels, with 100+ tons per pass capacity, to load dump trucks in a phenomenon described as high-impact shovel loading operations (HISLO). The HISLO phenomenon causes excessive shock and vibrations in the dump truck assembly resulting in whole body vibration (WBV) exposures to operators. The truck suspension system performance deteriorates with time; therefore their effectiveness in attenuating vibrations reduces. No research has been conducted to study the impact of ageing suspension mechanisms on the magnitudes of WBV in HISLO operations.

This study is a pioneering effort to provide fundamental and applied knowledge for understanding the …

Scale-Up Investigation And Hydrodynamics Study Of Gas-Solid Fluidized Bed Reactor Using Advanced Non-Invasive Measurement Techniques, Abdelsalam Efhaima

Doctoral Dissertations

"This research focuses on validating our newly developed mechanistic scale-up methodology for hydrodynamics similarity of gas-solid fluidized bed reactors (FBRs) by implementing our advanced non-invasive measurement techniques which are gamma ray computed tomography (CT) and radioactive particle tracking (RPT) that measure local hydrodynamic parameters. Experiments were carried out in two fluidized beds of 14 cm and 44 cm in diameter using air as the gas phase and particles of different materials. Since in these reactors the gas dynamic dictates the bed hydrodynamics, the new mechanistic scale-up methodology is based on maintaining similar or closer time averaged radial profiles of gas …

Microwave Material Characterization Of Alkali-Silica Reaction (Asr) Gel In Cementitious Materials, Ashkan Hashemi

Doctoral Dissertations

"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive …

Clustering: Methodology, Hybrid Systems, Visualization, Validation And Implementation, Dao Minh Lam

Doctoral Dissertations

"Unsupervised learning is one of the most important steps of machine learning applications. Besides its ability to obtain the insight of the data distribution, unsupervised learning is used as a preprocessing step for other machine learning algorithm. This dissertation investigates the application of unsupervised learning into various types of data for many machine learning tasks such as clustering, regression and classification. The dissertation is organized into three papers. In the first paper, unsupervised learning is applied to mixed categorical and numerical feature data type to transform the data objects from the mixed type feature domain into a new sparser numerical …

Modeling, Analysis, And Simulation For Aqueous-Based Ceramic Pastes In Freeze-Form Extrusion Fabrication Process, Mingyang Li

Doctoral Dissertations

"During the freeze-form extrusion fabrication process, both the extrusion and freezing processes are complex due to the aqueous-based ceramic pastes' non-Newtonian behavior, large latent heat of the water contained in the paste, and the small temperature difference between the ambient and the paste. In this study, the steady-state relationship between plunger velocity and extrusion force is developed based on a modified Herschel-Bulkley viscosity model and the Navier-Stokes equations, and the dynamic response of the extrusion force is described by a first-order nonlinear equation when plunger velocity is taken as an input. It is shown that the extrusion response time depends …

Synthesis And Functionalization Of A Triaryldiamine-Base Photoconductive/Photorefractive Composite, And Its Application To Aberrated Image Restoration, Yichen Liang

Doctoral Dissertations

"Organic photorefractive (PR) composites have recently emerged as an important class of materials for applications including high-density data storage, optical communication, and biomedical imaging. In an effort to further improve their performance, this study focused on the utilization of functionalized semiconductor nanocrystals to photosensitize triaryamine (TPD)-based PR composites, as well as the application of TPD-based PR composites in the restoration of aberrated optical information. A novel approach to functionalize CdSe quantum dot (QCdSe) was firstly introduced where the sulfonated triarydiamine (STPD) was used as charge-transporting ligand to passivate QCdSe. TPD-based photoconductive and PR composites were photosensitized with the STPD-passivated QCdSe …

Adaptive Filters For Sparse System Identification, Jianming Liu

Doctoral Dissertations

"Sparse system identification has attracted much attention in the field of adaptive algorithms, and the adaptive filters for sparse system identification are studied. Firstly, a new family of proportionate normalized least mean square (PNLMS) adaptive algorithms that improve the performance of identifying block-sparse systems is proposed. The main proposed algorithm, called block-sparse PNLMS (BS-PNLMS), is based on the optimization of a mixed ℓ_2,1 norm of the adaptive filter's coefficients. A block-sparse improved PNLMS (BS-IPNLMS) is also derived for both sparse and dispersive impulse responses. Meanwhile, the proposed block-sparse proportionate idea has been extended to both the proportionate affine projection …

Geophysical Imaging Of Karst Features In Missouri, Jeremiah Chukwunonso Obi

Doctoral Dissertations

"Automated electrical resistivity tomography (ERT) supported with multichannel analysis of surface waves (MASW) and boring data were used to map karst related features in Missouri in order to understand karst processes better in Missouri. Previous works on karst in Missouri were mostly surficial mapping of bedrock outcrops and joints, which are not enough to define the internal structure of karst system, since most critical processes in karst occur underground. To understand these processes better, the density, placement and pattern of karst related features like solution-widened joints and voids, as well as top of bedrock were mapped. In the course of …

Multi-Level Evolutionary Algorithms Resource Allocation Utilizing Model-Based Systems Engineering, Bhanuchander Reddy Poreddy

Doctoral Dissertations

"This research presents an innovative approach to solve the resource allocation problems using Multi-level Evolutionary Algorithms. Evolutionary Algorithms are used to solve resource allocation problems in different domains and their results are then incorporated into a higher level system solution using another Evolutionary Algorithm to solve base camp planning problems currently faced by the U.S. Department of Defense.

Two models are introduced to solve two domain specific models: a logistics model and a power model. The logistic model evaluates routes for logistics vehicles on a daily basis with a goal of reducing fuel usage by delivery trucks. The evaluation includes …

A Domain Independent Method To Assess System Of System Meta-Architectures Using Domain Specific Fuzzy Information, Louis Edward Pape Ii

Doctoral Dissertations

"This research proposes a domain independent method to build and assess systems of systems (SoS) architecture models. A simplified meta-architecture containing each component system's participation and a first order, binary, system-to-system interface is proposed. The method describes how to elicit desired SoS attributes from stakeholders. Measures of the attributes depend on systems' participation and interfaces, that is, on the SoS architecture. The goal is to model a realizable SoS configuration, optimized over multiple attributes. Key attribute measures are combined in a fuzzy inference system to assess an overall fitness measure for any SoS in the meta-architecture. A genetic algorithm is …

On The Spheroidal Graphite Growth And The Austenite Solidification In Ductile Irons, Jingjing Qing

Doctoral Dissertations

"Evolutions of austenite and nodular/spheroidal graphite particles during solidifications of ductile irons were experimentally investigated. Spheroidal graphite particle and austenite dendrite were found nucleated independently in liquid. Austenite dendrite engulfed the spheroidal graphite particles after contact and an austenite shell formed around a spheroidal graphite particle. The graphite diameter at which the austenite shell closed around nodule was determined. Statistically determined graphite size distributions indicated multiple graphite nucleation events during solidification.

Structures in a graphite nodule varied depending on the growth stages of the nodule in ductile iron. Curved graphene layers appearing as faceted growth ledges swept circumferentially around the …

Boundary Control Of Parabolic Pde Using Adaptive Dynamic Programming, Behzad Talaei

Doctoral Dissertations

"In this dissertation, novel adaptive/approximate dynamic programming (ADP) based state and output feedback control methods are presented for distributed parameter systems (DPS) which are expressed as uncertain parabolic partial differential equations (PDEs) in one and two dimensional domains. In the first step, the output feedback control design using an early lumping method is introduced after model reduction. Subsequently controllers were developed in four stages; Unlike current approaches in the literature, state and output feedback approaches were designed without utilizing model reduction for uncertain linear, coupled nonlinear and two-dimensional parabolic PDEs, respectively. In all of these techniques, the infinite horizon cost …

Thorium-Based Mixed Oxide Fuel In A Pressurized Water Reactor: A Feasibility Analysis With Mcnp, Lucas Powelson Tucker

Doctoral Dissertations

"This dissertation investigates techniques for spent fuel monitoring, and assesses the feasibility of using a thorium-based mixed oxide fuel in a conventional pressurized water reactor for plutonium disposition. Both non-paralyzing and paralyzing dead-time calculations were performed for the Portable Spectroscopic Fast Neutron Probe (N-Probe), which can be used for spent fuel interrogation. Also, a Canberra ³He neutron detector's dead-time was estimated using a combination of subcritical assembly measurements and MCNP simulations. Next, a multitude of fission products were identified as candidates for burnup and spent fuel analysis of irradiated mixed oxide fuel. The best isotopes for these applications were …

Subterranean Photobioreactors For Commercial-Industrial Scale Algal Culture, Daniel James Vidt

Doctoral Dissertations

"There are many potential benefits to the mining industry accruing from the application of algal biotechnology. The main benefits are in the production of biodiesel and in the remediation of mining brownfields. The research in this study was centered in the original idea that these brownfields represent a tremendous opportunity for use as a hybrid model for redevelopment into sustainable "mines" of biomass. The ability of these underground spaces serving as bioreactors to control all aspects of the growing environment, from lighting, to temperature, to biosecurity, are key advantages that have been identified in the literature. The many benefits inherent …

Study Of Heat Transfer Phenomenon During Natural Convection, Muhammad Yousaf

Doctoral Dissertations

"The purpose of the present study was to numerically investigate the effects of the roughness elements on the heat transfer during natural convection. A computational algorithm was developed based on the Lattice Boltzmann method to conduct numerical study in two-dimensional rectangular cavities and Rayleigh-Bénard cell. A single relaxation time Bhatnagar-Gross-Krook model of Lattice Boltzmann method was used to solve the coupled momentum and energy equations in two-dimensional lattices. Computational model was validated against previous benchmark solutions, and a good agreement was found to exist. A Newtonian fluid of Prandtl (Pr) number 1.0 was considered for this numerical study. The range …

Hierarchical Control Of Complex Manufacturing Processes, Hesam Zomorodi Moghadam

Doctoral Dissertations

"The need for changing the control objective during the process has been reported in many systems in manufacturing, robotics, etc. However, not many works have been devoted to systematically investigating the proper strategies for these types of problems. In this dissertation, two approaches to such problems have been suggested for fast varying systems. The first approach, addresses problems where some of the objectives are statically related to the states of the systems. Hierarchical Optimal Control was proposed to simplify the nonlinearity caused by adding the statically related objectives into control problem. The proposed method was implemented for contour-position control of …

Geotechnical State-Of-The-Art In Guatemala -- Ground Stabilization, Fernando Rafael Callejas Benitez

Doctoral Dissertations

"History provides an understanding of the present and in a way, a guide for the future. The state-of-the-art is often referred to as a snapshot of the most significant works and contributions made in a field of study; In this case the focus is on Guatemalan geotechnical engineering. This study presents a comprehensive description of the different events that impulse geotechnical engineering in Guatemala.

As part of the description of the state-of-the-practice an investigation of the different human (engineers/contractors) and physical resources (laboratories/field equipment) and their capabilities are presented. An overview of the civil engineering programs is presented. Then, the …