Digital Commons Network^™

A Functional Data Analytic Approach For Region Level Differential Dna Methylation Detection, Mohamed Salem F. Milad

Doctoral Dissertations

"DNA methylation is an epigenetic modification that can alter gene expression without a DNA sequence change. The role of DNA methylation in biological processes and human health is important to understand, with many studies identifying associations between specific methylation patterns and diseases such as cancer. In mammals, DNA methylation almost always occurs when a methyl group attaches to a cytosine followed by a guanine (i.e. CpG dinucleotides) on the DNA sequence. Many statistical methods have been developed to test for a difference in DNA methylation levels between groups (e.g. healthy vs disease) at individual cytosines. Site level testing is often …

Event-Triggered Near Optimal Adaptive Control Of Interconnected Systems, Vignesh Narayanan

Doctoral Dissertations

"Increased interest in complex interconnected systems like smart-grid, cyber manufacturing have attracted researchers to develop optimal adaptive control schemes to elicit a desired performance when the complex system dynamics are uncertain. In this dissertation, motivated by the fact that aperiodic event sampling saves network resources while ensuring system stability, a suite of novel event-sampled distributed near-optimal adaptive control schemes are introduced for uncertain linear and affine nonlinear interconnected systems in a forward-in-time and online manner.

First, a novel stochastic hybrid Q-learning scheme is proposed to generate optimal adaptive control law and to accelerate the learning process in the presence of …

Reliability Prediction In Early Design Stages, Yao Cheng

Doctoral Dissertations

"In the past, reliability is usually quantified with sufficient information available. This is not only time-consuming and cost-expensive, but also too late for occurred failures and losses. For solving this problem, the objective of this dissertation is to predict product reliability in early design stages with limited information. The current research of early reliability prediction is far from mature. Inspired by methodologies for the detail design stage, this research uses statistics-based and physics-based methodologies by providing general models with quantitative results, which could help design for reliability and decision making during the early design stage. New methodologies which accommodate component …

Optimal Design And Freeform Extrusion Fabrication Of Functionally Gradient Smart Parts, Amir Ghazanfari

Doctoral Dissertations

"An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density was developed. In this process, an aqueous paste of ceramic particles with a very low binder content (<1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Sample parts made of alumina and fully stabilized zirconia were produced using this process and their mechanical properties including density, strength, Young's modulus, Weibull modulus, toughness, and hardness were examined. Microstructural evaluation was also performed to measure the grain size, and critical flaw sizes were obtained. The results indicate that the proposed method enables fabrication of geometrically complex parts with superior mechanical properties. Furthermore, several methods were developed to increase the productivity of the CODE process and enable manufacturing of functionally graded materials with an optimum distribution of material composition. As an application of the CODE process, advanced ceramic components with embedded sapphire optical fiber sensors were fabricated and properties of parts and sensors were evaluated using standard test methods"--Abstract, page iv.

Studies On Neutron Diffraction And X-Ray Radiography For Material Inspection, Fahima Fahmida Islam

Doctoral Dissertations

"Among the different probes to study the structures of the bio and structural materials, X-ray and neutron are widely used because of their distinctive usefulness in investigating different structures. X-ray radiography and neutron diffraction are two widely known non-destructive techniques for material inspection. Here we demonstrate the design of neutron diffractometer with low power source and analyze the digital image produced by the X-ray radiography instead of neutron diffraction because of the availability of the data. Neutron diffraction is a powerful tool for understanding the behavior of crystal structures and phase behaviors of materials. While neutron diffraction capabilities continue to …

Thermomechanical Fatigue Life Investigation Of An Ultra-Large Mining Dump Truck Tire, Wedam Nyaaba

Doctoral Dissertations

The cost benefits associated with the use of heavy mining machinery in the surface mining industry has led to a surge in the production of ultra-large radial tires with rim diameters in excess of 35 in. These tires experience fatigue failures in operation. The use of reinforcing fillers and processing aids in tire compounds results in the formation of microstructural inhomogeneity in the compounds and may serve as sources of crack initiation in the tire. Abrasive material cutting is another source of cracks in tires used in mining applications. It suffices, then, to assume that every material plane in the …

Gamma Spectroscopy By Artificial Neural Network Coupled With Mcnp, Huseyin Sahiner

Doctoral Dissertations

"While neutron activation analysis is widely used in many areas, sensitivity of the analysis depends on how the analysis is conducted. Even though the sensitivity of the techniques carries error, compared to chemical analysis, its range is in parts per million or sometimes billion. Due to this sensitivity, the use of neutron activation analysis becomes important when analyzing bio-samples. Artificial neural network is an attractive technique for complex systems. Although there are neural network applications on spectral analysis, training by simulated data to analyze experimental data has not been made. This study offers an improvement on spectral analysis and optimization …

The Effect Of Testing Conditions On Lost Circulation Materials' Performance In Simulated Fractures, Montri Jeennakorn

Doctoral Dissertations

"Lost circulation (LOC) problems increase costs of drilling significantly. It is not only the cost of the drilling fluid that is lost into the formation but also the costs of subsequent problems that can be higher than the cost of the drilling fluids. LOC also possibly leads to a serious risk of blowout incident.

Lost circulation materials (LCM) are regularly added to the drilling fluids with an expectation of plugging the flow path. Due to the difficulties of testing and monitoring LCM sealing processes in the field, LCM evaluation in the laboratory is often used to prove and assure successful …

Modeling Dynamic Community Acceptance Of Mining Using Agent-Based Modeling, Mark Kofi Boateng

Doctoral Dissertations

"This research attempts to provide fundamental understanding into the relationship between perceived sustainability of mineral projects and community acceptance. The main objective is to apply agent-based modeling (ABM) and discrete choice modeling to understand changes in community acceptance over time due to changes in community demographics and perceptions. This objective focuses on: 1) formulating agent utility functions for ABM, based on discrete choice theory; 2) applying ABM to account for the effect of information diffusion on community acceptance; and 3) explaining the relationship between initial conditions, topology, and rate of interactions, on one hand, and community acceptance on the other …

Experimental Study Of Natural Convection Heat Transfer And Gaseous Dynamics From Dual-Channel Circulation Loop, Ibrahim Ahmed Said Abdallah

Doctoral Dissertations

"This research focuses on establishing a range of scaled separate and integral effects experiments for studying thermal-hydraulic behavior occurring within a component or region of the prismatic very high-temperature reactor (VHTR) such as plenum-to-plenum heat transfer and gaseous dynamics during natural circulation. Natural circulation of the coolant is the leading capability for VHTR to transport the decay heat from the core to the reactor vessel during accident scenarios. To address this need, a scaled-down facility is designed and developed with only two channels with upper and lower plena. The emphasis is placed on high-resolution and high-fidelity experimental data for local …

Pillar Design For St. Peter Sandstone Formation, Francis Anohomah Arthur

Doctoral Dissertations

"Silica sands produced primarily from St. Peter Sandstone are used for hydraulic fracturing in the petroleum industry, glassmaking, chemicals, ceramics, filtration and the foundry industry in the US. The recent high demand for silica sands for hydraulic fracturing has triggered increased production and commissioning of new silica sand mines to support natural gas production from shale and tight gas deposits in the US. Most mines use surface mining methods to extract St. Peter Sandstone. The room and pillar mining method has been successfully used for St. Peter Sandstone mining in a few US locations, however, no one has proposed a …

Theoretical Calculations For Electron Impact Ionization Of Atoms And Molecules, Sadek Mohamed Fituri Amami

Doctoral Dissertations

"In the last twenty years, significant progress has been made for the theoretical treatment of electron impact ionization (e,2e) of atoms and molecules and, for some cases, very nice agreement between experiment and theory has been achieved. In particular, excellent agreement between theory and experiment and theory has been achieved for ionization of hydrogen and helium. However, agreement between experiment and theory is not nearly as good for ionization of larger atoms and molecules. In the first part of this dissertation, different theoretical approaches will be employed to study the triply differential cross section (TDCS) for low and intermediate energy …

Efficient Algorithms For Analyzing Large Scale Network Dynamics: Centrality, Community And Predictability, Sima Das

Doctoral Dissertations

"Large scale networks are an indispensable part of our daily life; be it biological network, smart grids, academic collaboration networks, social networks, vehicular networks, or the networks as part of various smart environments, they are fast becoming ubiquitous. The successful realization of applications and services over them depend on efficient solution to their computational challenges that are compounded with network dynamics. The core challenges underlying large scale networks, for example: determining central (influential) nodes (and edges), interactions and contacts among nodes, are the basis behind the success of applications and services. Though at first glance these challenges seem to be …

Event-Triggering Architectures For Adaptive Control Of Uncertain Dynamical Systems, Ali Talib Oudah Albattat

Doctoral Dissertations

"In this dissertation, new approaches are presented for the design and implementation of networked adaptive control systems to reduce the wireless network utilization while guaranteeing system stability in the presence of system uncertainties. Specifically, the design and analysis of state feedback adaptive control systems over wireless networks using event-triggering control theory is first presented. The state feedback adaptive control results are then generalized to the output feedback case for dynamical systems with unmeasurable state vectors. This event-triggering approach is then adopted for large-scale uncertain dynamical systems. In particular, decentralized and distributed adaptive control methodologies are proposed with reduced wireless network …

Geophysical Assessment Of Soil And Rock In The New Madrid Seismic Zone, Faraj Mohamed Eljabri

Doctoral Dissertations

"The research presented here consists of two case studies: the first from a study site in Illinois and the second from a site in Arkansas. In both instances, geophysical investigations were conducted to characterize the subsurface. At the Illinois site, borehole control, downhole seismic (DHS), seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW) data were acquired for the purpose of seismic site characterization. Shear wave and compressional wave velocities were used to estimate depth to bedrock and to generate 1-D plots depicting variations in Poisson's Ratio, elastic moduli and density. The average shear wave velocity in the …

Development Of Active Microwave Thermography For Structural Health Monitoring, Ali Foudazi

Doctoral Dissertations

"Active Microwave Thermography (AMT) is an integrated nondestructive testing and evaluation (NDT&E) method that incorporates aspects of microwave NDT and thermography techniques. AMT uses a microwave excitation to generate heat and the surface thermal profile of the material or structure under test is subsequently measured using a thermal camera (or IR camera). Utilizing a microwave heat excitation provides advantages over traditional thermal excitations (heat lamps, etc.) including the potential for non-contact, selective and focused heating. During an AMT inspection, two heating mechanisms are possible, referred to as dielectric and induction heating. Dielectric heating occurs as a result of the interaction …

Node Localization In Underwater Sensor Networks (Uwsn), Huai Huang

Doctoral Dissertations

"This dissertation focuses on node localization in underwater wireless sensor networks (UWSNs) where anchor nodes have knowledge of their own locations and communicate with sensor nodes in acoustic or magnetic induction (MI) means. The sensor nodes utilize the communication signals and the locations of anchor nodes to locate themselves and propagate their locations through the network.

For UWSN using MI communications, this dissertation proposes two localization methods: rotation matrix (RM)-based method and the distance-based method. Both methods require only two anchor nodes with arbitrarily oriented tri-directional coils to locate one sensor node in the 3-D space, thus having advantages in …

Modal Based Bga Modeling In High-Speed Package, Shuai Jin

Doctoral Dissertations

"In the Section 1, the improved "Root-Omega" method for extracting dielectric properties from fabricated multilayer printed circuit boards is proposed. Based on the electrical properties of fabricated transmission lines, the improved "Root-Omega" method applied to cases with smooth and rough conductors is validated using simulations. Error sensitivity analysis is performed to demonstrate the potential errors in the original "Root-Omega" procedure and the error sensitivity is significantly reduced by the proposed improvements.

In the Section 2, a fast modal-based approach is developed to accurately and efficiently capture the proximity effect. Image theory is also applied in the proposed approach to reduce …

Characterization And Numerical Simulation Of The Microstructural And Micromechanical Viscoelastic Behavior Of Oil Sands Using The Discrete Element Method, Eric Kofi Gbadam

Doctoral Dissertations

"Oil sands are naturally geologic formations of predominantly quartz sand grains whose void spaces are filled with bitumen, water, and dissolved gases. The electric rope shovel is the primary equipment used for excavating the Athabasca oil sand formations. The equipment's static and dynamic loads are transferred to the formation during excavation and propel. These loads cause ground instability leading to sinkage or rutting, crawler wear, and fracture failures. These problems result in unplanned downtimes, production losses, and high maintenance costs. In order to address these problems, there is a need to develop valid models that capture the behavior and performance …

Real-Time Diesel Particulate Matter Monitoring In Underground Mine Atmospheres, Association With The Standard Method And Related Challenges, Muhammad Usman Khan

Doctoral Dissertations

"Diesel-powered equipment is a significant component of underground mining operations. Miners' exposure to diesel exhaust is harmful. The standard Diesel Particulate Matter (DPM) monitoring method (NIOSH 5040 method) has limitations that preclude rapid DPM estimation and detailed understanding of DPM variations over time. However, real-time DPM monitors do not inherit these limitations. Biodiesel is often used as a substitute for regular petroleum-diesel because of its ability to emit less DPM. However, accuracy of available real-time DPM monitors has not been determined in mines using 70% to 99% (high-percent) biodiesel. The present research addresses this need by rigorous testing of a …

Lhd Vibrations Analysis And Numerical Modeling During Operations, Kgosietsile Kolobe

Doctoral Dissertations

"Load-haul-dump vehicles (LHDs) are extensively used as primary loaders in mining operations. LHDs have proven to be vigorous, extremely productive and reliable in mining applications. They have a wide range of tramming capacities that have enabled them to become an essential component in the hard rock mining industry.

Increased mining economic challenges and global competition means the mining industry has to maximize productivity by cutting down operating and capital costs. Also, improvements in safety standards have led to the demand for safer and efficient machines.

LHD operators are at a high risk of whole-body vibrations (WBVs) exposure leading to musculoskeletal …

Optimization Of Solvent Suppression Sequences For Nmr Analysis Of Aqueous Solutions, Annalise Rose Pfaff

Doctoral Dissertations

"When the use of deuterated solvents is precluded in the NMR analysis of biomolecules in their natural environment, pre-saturation solvent suppression pulse sequences are frequently employed to avoid interference from the overbearing solvent signal. However, these sequences generally require extensive re-adjustment of NMR parameters between samples. For this reason, the EXCEPT (EXponentially Converging Eradication Pulse Train) solvent suppression sequence was developed, which exhibits a tolerance of over an order of magnitude in sample T₁ variation. EXCEPT uses an innovative version of "inversion-recovery nulling" with frequency-selective, low-power adiabatic pulses and exponentially decreasing interpulse delays that effectively reduce solvent net magnetization by …

Cognition-Based Approaches For High-Precision Text Mining, George John Shannon

Doctoral Dissertations

"This research improves the precision of information extraction from free-form text via the use of cognitive-based approaches to natural language processing (NLP). Cognitive-based approaches are an important, and relatively new, area of research in NLP and search, as well as linguistics. Cognitive approaches enable significant improvements in both the breadth and depth of knowledge extracted from text. This research has made contributions in the areas of a cognitive approach to automated concept recognition in.

Cognitive approaches to search, also called concept-based search, have been shown to improve search precision. Given the tremendous amount of electronic text generated in our digital …

Characterizing Long-Term Groundwater Conditions And Lithology For The Design Of Large-Scale Borehole Heat Exchangers, David Charles Smith

Doctoral Dissertations

"Construction of large scale ground coupled heat pump (GCHP) systems that operate with hundreds or even thousands of boreholes for the borehole heat exchangers (BHE) has increased in recent years with many coming on line in the past 10 years. Many large institutions are constructing these systems because of their ability to store energy in the subsurface for indoor cooling during the warm summer months and extract that energy for heating during the cool winter months.

Despite the increase in GCHP system systems constructed, there have been few long term studies on how these large systems interact with the subsurface. …

Atomic/Molecular Layer Deposition Prepared Size-Selective Catalysts And Supported Nickel Catalysts, Zeyu Shang

Doctoral Dissertations

"Heterogeneous catalysts are widely used because of their many advantages. In this dissertation, the application of atomic/molecular layer deposition (ALD/MLD) in heterogeneous catalyst synthesis and modification was examined.

A novel nanostructured size-selective catalyst was synthesized by depositing ultra-thin porous shells on the surface of catalysts. The ultra-thin porous shells were formed by oxidation of aluminum alkoxide films deposited by MLD. The catalytic activity of the size-selective catalyst was improved by introducing gaps between the porous shell and catalytic metal nanoparticles. The introduction of gaps greatly reduced the catalyst activity loss, which resulted from the contact areas between the active sites …

Experimental Investigations Of Natural Circulation In A Separate-And-Mixed Effects Test Facility Mimicking Prismatic Modular Reactor (Pmr) Core, Mahmoud M. Taha

Doctoral Dissertations

"After the Fukushima Daiichi nuclear power plant accident in 2011, significant attention was directed to investigate natural circulation thermal-hydraulics in Prismatic Modular Reactors (PMRs). Natural circulation is employed as a passive safety feature that passively removes the decay heat released after the loss of flow accidents (LOFA). Several computational studies have addressed such phenomena, however, validation of Computational Fluid Dynamics (CFD) is needed by providing high-quality data obtained from separate test facilities designed with reference to the corresponding reference PMRs. To address this need, a separate effects Plenum-to-Plenum Facility (P2PF) was designed and developed with dual channels and plena for …

Design And Performance Of Cost-Effective Ultra High Performance Concrete For Bridge Deck Overlays, Mahdi Valipour

Doctoral Dissertations

"The main objective of this research is to develop a cost-effective ultra-high performance concrete (UHPC) for bonded bridge deck overlays. The high durability and mechanical properties of such repair material can offer shorter traffic closures and prolong the service life of the pavement. The UHPC was optimized using supplementary cementitious materials (SCMs), proper combinations of sands, and adequate selection of fiber types and contents. Packing density studies included paste, sand, and fiber combinations. The robustness of optimized UHPC mixtures to variations of mixing and curing temperatures was examined. The efficiency of various shrinkage mitigation approaches in reducing autogenous and drying …

The Maculoprotective Effect Of A Thiol Antioxidant In Retinal Degeneration Models, Hsiu-Jen Wang

Doctoral Dissertations

"Age-related macular degeneration (AMD) is a leading cause of irreversible blindness among adults, age 60 and older, in developed countries. While oxidative stress is implicated in the pathogenesis of AMD, clinical studies have shown that dietary antioxidants can delay progression of AMD. Currently, there is no FDA-approved treatment for AMD. Therefore, we hypothesized that N-acetylcysteine amide (NACA), a thiol antioxidant, would protect retinal pigment epithelium and impede the progression of retinal degeneration. The goal of this work was to evaluate the efficacy of NACA in preventing retinal pigment epithelial cell and photoreceptor death in AMD models. To achieve this, we …

Impact Of Vertical Internals On The Hydrodynamics And Heat Transfer Coefficient In A Gas-Solid Fluidized Bed, Haidar Moafaq Taofeeq

Doctoral Dissertations

"This research studied the impact of the dense vertical immersed heat exchanging tubes on the gas and solids hydrodynamic characteristics, flow regime, pressure drop, and heat transfer in a 0.14 m inside diameter gas-solid fluidized bed column of. Two sizes of vertical internal tube bundles (0.0127 and 0.0254 m) of circular arrangement have been implemented to represent the heat exchange tubes covering 25% of the column cross-sectional area. The experimental work was achieved at different operating conditions and various solids particle types that differ in average particle size, solids density, particles shape, and particles sphericity. The experimental measurements were performed …

Continuous Focusing And Separation Of Microparticles With Acoustic And Magnetic Fields, Ran Zhou

Doctoral Dissertations

"Microfluidics enables a diverse range of manipulations (e.g., focusing, separating, trapping, and enriching) of micrometer-sized objects, and has played an increasingly important role for applications that involve single cell biology and the detection and diagnosis of diseases. In microfluidic devices, methods that are commonly used to manipulate cells or particles include the utilization of hydrodynamic effects and externally applied field gradients that induce forces on cells/particles, such as electrical fields, optical fields, magnetic fields, and acoustic fields.

However, these conventional methods often involve complex designs or strongly depend on the properties of the flow medium or the interaction between the …