Engineering Commons^™

Correlation Between Delay Time And Measured Concentration And Concentration Uncertainty By Neutron Activation Analysis, James Thomas Seman

Doctoral Dissertations

"For the last several decades, it has been apparent that new methods of identifying explosives can help investigators trace their origins. One way to identify an explosive is through the use of taggants: materials added to a product that encodes information about the product such as when it was manufactured.

This research investigates the survivability of a new identification taggant called the Nuclear Barcode that overcomes some of the downfalls that have been identified in prior taggants. The Nuclear Barcode encodes information as a unique combination of concentrations of rare earths (Ho, Eu, Sm, Lu, and Dy) and precious metals …

Discrete Element And Artificial Intelligence Modeling Of Rock Properties And Formation Failure In Advance Of Shovel Excavation, Muhammad Waqas

Doctoral Dissertations

"Rock tests are performed before the start of every mining or civil engineering project as part of a detailed feasibility study. The feasibility study is costly and it comprises drilling, sample collection, sample handling and laboratory testing. Numerical modeling techniques, such as Particle Flow Code (PFC), can be used to provide reliable estimates of rock strength values. The numerical models for unconfined compressive strength (UCS), direct tension, and Brazilian tests were developed in PFC, and validated using data from literature. A particle size range of 3-5 mm with D_max/D_min = 1.67 gave the best results. The numerical …

Signal Processing For Microwave Imaging Systems With Very Sparse Array, Xiahan Yang

Doctoral Dissertations

"This dissertation investigates image reconstruction algorithms for near-field, two dimensional (2D) synthetic aperture radar (SAR) using compressed sensing (CS) based methods. In conventional SAR imaging systems, acquiring higher-quality images requires longer measuring time and/or more elements in an antenna array. Millimeter wave imaging systems using evenly-spaced antenna arrays also have spatial resolution constraints due to the large size of the antennas. This dissertation applies the CS principle to a bistatic antenna array that consists of separate transmitter and receiver subarrays very sparsely and non-uniformly distributed on a 2D plane. One pair of transmitter and receiver elements is turned on at …

Dragline Excavation Simulation, Real-Time Terrain Recognition And Object Detection, Godfred Somua-Gyimah

Doctoral Dissertations

"The contribution of coal to global energy is expected to remain above 30% through 2030. Draglines are the preferred excavation equipment in most surface coal mines. Recently, studies toward dragline excavation efficiency have focused on two specific areas. The first area is dragline bucket studies, where the goal is to develop new designs which perform better than conventional buckets. Drawbacks in the current approach include operator inconsistencies and the inability to physically test every proposed design. Previous simulation models used Distinct Element Methods (DEM) but they over-predict excavation forces by 300% to 500%. In this study, a DEM-based simulation model …

Direct Numerical Simulation Of Pressure Fluctuations Induced By Supersonic Turbulent Boundary Layers, Chao Zhang

Doctoral Dissertations

"Direct Numerical Simulations are used to generate a database of high-speed zero-pressure-gradient turbulent boundary layers developing spatially over a flat plate with nominal freestream Mach number ranging from 2:5 to 14 and wall-to-recovery temperature ranging from 0:18 to 1:0. The flow conditions of the DNS are representative of the operational conditions of the Purdue Mach 6 quiet tunnel, the Sandia Hypersonic Wind Tunnel at Mach 8, and the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The DNS database is used to gauge the performance of compressibility transformations, including the classical Morkovin's scaling and strong Reynolds analogy as well as …

Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor (Mbr) Using Developed Experimental Methods And Cfd Simulation, Vineet Alexander

Doctoral Dissertations

"Upflow Moving Bed Hydrotreater (MBR) reactor is used for hydrotreating resid crude oil. It is a two-phase upflow reactor having a catalyst bed with conical bottom, and plena. At industrial conditions the reactor is not performing at its best and encountering issues such as hot spots, catalyst agglomeration inside the catalyst bed leading to frequent shutdown of the reactor. The root cause of these problems are linked to the improper hydrodynamics inside the catalyst bed. To investigate this, the industrial scale MBR is scaled down to a pilot scale and indicative and key hydrodynamic parameters are investigated using developed experimental …

High Temperature Polymer Composites Using Out-Of-Autoclave Processing, Sudharshan Anandan

Doctoral Dissertations

"High performance polymer composites possess high strength-to-weight ratio, corrosion resistance, and have design flexibility. Carbon/epoxy composites are commonly used aerospace materials. Bismaleimide based composites are used as a replacement for epoxy systems at higher service temperatures. Aerospace composites are usually manufactured, under high pressure, in an autoclave which requires high capital investments and operating costs. In contrast, out-of-autoclave manufacturing, specifically vacuum-bag-only prepreg process, is capable of producing low cost and high performance composites. In the current study, out-of-autoclave processing of high temperature carbon/bismaleimide composites was evaluated. The cure and process parameters were optimized. The properties of out-of-autoclave cured laminates compared …

Modeling And Characterization Of Thermo-Oxidative Behavior Of Bismaleimide Composites, Rafid Muhammad Hussein

Doctoral Dissertations

"High-temperature polymer matrix composites (HTPMCs) are susceptible to thermo-oxidation, which accelerates the composites' degradation and reduces the service life. Mechanical properties of HTPMCs deteriorate due to coupled thermo-oxidation and cross-linking mechanisms. Bismaleimides (BMIs) are commonly used high-temperature resins for aerospace applications. This work presents the viability of using experimental weight loss to model the spatial distribution of oxidation when the oxidized polymer matrix is not discernible. Three tasks are introduced: (1) Anisotropic oxidation prediction using optimized weight loss behavior of bismaleimide composites, (2) A multi-scale modeling of thermo-oxidative effects on the flexural behavior of cross-ply bismaleimide composites, and (3) Thermo-oxidative …

Modeling And Simulation Of Viscoplasticity, Recrystallization, And Softening Of Alloyed Steel During Hot Rolling Process, Xin Wang

Doctoral Dissertations

"Hot rolling is one of the most important and complex deformation processes in steel manufacturing and is essential to final product quality. The objective of this study is to investigate viscoplasticity, dynamic recrystallization, and static softening of alloyed metal during hot rolling process. Gleeble hot compression tests were performed to provide experimental stress-strain curves at different temperatures and strain rates. An inverse finite element analysis was performed to calibrate the experimental curves. Viscoplastic models including a Johnson-Cook (JC) model, a Zerilli-Armstrong (ZA) model, and a combined JC and ZA model were developed. Dynamic recrystallization behavior was investigated and modeled based …

Adaptive Data Analysis For Damage Detection And System Identification In Civil Infrastructure, Hongya Qu

Doctoral Dissertations

"Time-varying structural systems are often encountered in civil engineering. As extreme events occur more frequently and severely in recent years, more structures are loaded beyond their elastic conditions and may thus experience damage in the years to come. Even if structures remain elastic, energy dissipation devices installed on structures often reveal hysteretic behaviors under earthquake loads. Therefore, it is imperative to develop and implement novel technologies that enable the identification and damage detection of time-varying systems. In this dissertation, adaptive wavelet transform (AWT) and multiple analytical mode decomposition (M-AMD) are proposed and applied to identify system properties and detect damage …

Modeling And Control Of Probe-On-Probe Dynamics In Dual-Probe Atomic Force Microscopy, Ayad Al-Ogaidi

Doctoral Dissertations

“The atomic force microscope (AFM) is a widely used instrument for imaging and direct manipulation of materials and particles at the nanoscale. The AFM uses a probe, which is a microcantilever with a sharp point at the end. Typically, the AFM is constructed with a single probe. The disadvantage of this construction is that it can only be used either for imaging or manipulation in one implementation. An AFM was constructed using two probes, permitting simultaneous imaging and manipulation. A dual-probe AFM (DP-AFM) provides a foundation for feedback controlled manipulation.

Paper I investigates probe-on-probe contact stability and examines the dynamics …

Design For Optical Metamaterial Design For Optical Metamaterial Absorber, Huixu Deng

Doctoral Dissertations

“Optical metamaterlal (MM) absorbers in the visible or near-infrared range have been widely investigated in these years since they are crucial in many promising applications, such as solar energy harvesting systems, thermo-photovoltaic energy conversion devices, thermal imaging and emissivity control. This dissertation aims to design and investigate various optical metamaterial absorbers based on different mechanisms and theories, such as cavity resonance, impedance match, equivalent circuit model and waveguide stop light mode. First, via utilizing the cavity resonance, a tunable narrowband MM absorber/emitter for thermophotovoltaic (TPV) is designed and analyzed based on gold nanowire cavities to improve the overall efficiency of …

Micro-Slotting Technique For Measurement Of Local Residual Stress In Metallic Materials, Elizabeth Anne Burns

Doctoral Dissertations

"Micro-slotting, a micro-scale relaxation residual stress measurement technique, has been shown in recent years to be a reliable method for measuring local residual stresses in metallic materials. This technique employs an SEM-focused ion beam system for milling and imaging, digital image correlation software to track displacements due to residual stress relaxation, and finite element analysis for interpolation of the original local stress state. In this research, a micro-slotting procedure was established using finite element models and was used to obtain sub-surface residual stress measurements on machined and shot peened planar Ti-6Al-4V samples. These measurements were compared to macro-scale XRD residual …

Design And Characterization Of Multi-Spectral Underwater Beam-Port For Pool-Type Research Reactors, Meshari Mesfer Alqahtani

Doctoral Dissertations

“The beam-port is a cardinal facility at research reactors necessary for dry irradiation, testing and measurement experiments. The Missouri University of Science and Technology Reactor (MSTR) is one such reactor with a beam-port. Installation of additional beam-port in such reactor facilities can be prohibitive. A novel remedy to this is an underwater beam-port for pool-type reactors. The design and characterization of a conceptual underwater multi-spectral beam-port for neutron and gamma fluxes were completed for the MSTR. The neutron spectra from the MSTR were simulated using the Monte Carlo N-particle (MCNP). The determined neutron spectra were experimentally validated using SAND-II. The …

Quantitative Phase-Field Modeling Of Crack Propagation In Multi-Phase Materials, Arezoo Emdadi

Doctoral Dissertations

”Research presented in this dissertation is focused on developing and validating a computational framework for study of crack propagation in polycrystalline composite ceramics capable of designing micro-architectures of phases to improve fracture toughness and damage tolerance of ZrB₂-based ultra-high temperature ceramics (UHTCs). A quantitative phase-field model based on the regularized formulation of Griffith’s theory is presented for crack propagation in homogenous and heterogeneous brittle materials. This model utilizes correction parameters in the total free energy functional and mechanical equilibrium equation within the crack diffusive area to ensure that the maximum stress in front of the crack tip is …

Synthesis And Comprehensive Studies Of Nanogels For Enhanced Oil Recovery, Jiaming Geng

Doctoral Dissertations

“Nanomaterials have been developed and applied for enhanced oil recovery (EOR) in oil industry. Among the developed nanomaterials, nano-sized crosslinked polymeric gel particles (nanogels) have shown the potential in improving both the macro- and micro-displacing efficiency. This dissertation focuses on the synthesis and the potential EOR mechanisms of nanogels. Nanogels with positive, negative, and neutral charges were synthesized through suspension polymerization. The morphology, size distribution, and zeta potential of nanogels were elucidated by corresponding technologies, such as scanning electron microscopy and dynamic light scattering. The ability of nanogels in oil-water interfacial tension (IFT) reduction and oil-in-water (o/w) emulsion stabilization was …

Shear Performance And Behavior Of Long Carbon Fiber Reinforced Concrete, Benjamin Paul Gliha

Doctoral Dissertations

”In this study, a laboratory testing program was developed to investigate the shear performance of fiber reinforced concrete beams. Long carbon fibers, to be included with a traditional fresh concrete mix, were developed and their shear performance was evaluated and compared to the performance and behavior of unreinforced concrete, traditionally reinforced concrete, and fiber reinforced concrete (FRC) with other fiber types.

The experimental program consisted of 30 large-scale beams tested for shear performance under monotonic loading. In addition to the large-scale beams, small-scale specimens were constructed of the same materials to correlate large-scale performances to ASTM C1609 testing and to …

Engineering Polymeric Hollow Fiber Membrane Reactors For Sustainable Chemical Transformation Reactions, Yingxin He

Doctoral Dissertations

“Over the past decade, laboratory-scale continuous-flow processes have witnessed explosive developments and have attracted a great deal of interest with respect to the significance of the economic and environmentally-sustainable production of pharmaceuticals, fine chemicals, and agrochemicals, as well as upgrading of biomass feedstocks. Immobilization of organocatalysts and metal nanoparticles on continuous-flow microreactors offers an efficient catalytic system that exploits and enhances the advantages of both nanocatalysis and flow chemistry, the so-called flow nanocatalysis approach. Various approaches have been developed for the development of continuous-flow reactions including immobilization and subsequent anchoring of organocatalysts and metal nanoparticles within microfluidic reactors. However, many …

Enhancement Of Heat Transfer Coefficient Using Nanofluids For Multi-Stage Flash Desalination (Msf) Plant, Nasser Zouli

Doctoral Dissertations

“The enhancement of thermal conductivity and local heat transfer coefficient, under laminar and turbulent flow regimes, of water-based spherical Al₂O₃, CuO, and Fe₂O₃ nanofluids have been experimentally investigated for the improvement of the thermal desalination processes using a newly developed sophisticated noninvasive heat transfer coefficient probe that is flush mounted on the inner wall surface of the test section. The nanoparticles have been selected because of their superior thermal conductivity and low cost, as well as the magnetic characteristic of Fe₂O₃ nanoparticle since a magnet can collect it and reuse. …

Effects Of Milling Methods, Cooling Strategies And End-Mill Coatings On Machinability In High Speed End-Milling Of Inconel- 718 Using Carbide End-Mills, Paras Mohan Jasra

Doctoral Dissertations

“Inconel-718 superalloy is used extensively in aerospace and nuclear industries due to its excellent properties such as: high strength-to-weight ratio, ability to retain its properties at high temperature, high corrosion and creep resistance. However, Inconel-718 is characterized as a “difficult-to-cut metal”, because it poses severe problems during machining such as: high temperature at the cutting zone due to low thermal conductivity, hardening tendency at elevated temperature, high cutting forces, rapid tool wear and high chemical affinity with many cutting tools. Appropriate cooling strategies, milling methods, tool coatings and cutting speeds play important roles in addressing these problems. This research presents …

Cerebral Vasospasm Detection And Treatment Using Transcranial Doppler Signal Analysis And Adaptive Medication Pump Mechanism, Khaled Elzaafarany

All ETDs from UAB

In the United States, many patients pass away due to delayed detection of Cerebral Vasospasm (CV). Transcranial Doppler (TCD) is an efficient noninvasive, reliable device that can monitor the blood flow in various parts of the human brain like middle cerebral artery and basilar artery without any surgical intervention. It can help neurologists to diagnose many brain problems like edema, trauma, hemorrhage, and aneurysm. Unfortunately, continuous or even daily TCD monitoring is challenging due to the operator expertise and certification required in the form of a trained technologist, and certified physician to perform these studies. This barrier exists due to …

Characterization And Mechanical Evaluation Of Discontinuous Carbon Fiber Based Liquid Molded Nylon-6 Composites, Siddhartha Brahma

All ETDs from UAB

The Anionic Ring Opening Polymerization (AROP) of caprolactam to form polyamide-6 (PA6) or liquid molding for polyamide-6 (LMPA6) presents the opportunity for a new class of composite materials with excellent performance and wide applicability from automotive, energy, transportation, and aerospace. Despite the inherent advantages with the process, industrial adoption is virtually nonexistent. Additionally, the growing trend of reclaiming fibers can also be coupled with this process with relative ease. The following work will evaluate the liquid molding process, particularly for the use of recycled or reclaimed carbon fibers, in the following ways. First, the adaptability of the process to use …

Nanomedicine: Electrohydrodynamic Atomization (Ehda) To Engineer Next-Generation Biomimetic Microphysiological Systems (Mps) And Precision Drug Delivery Systems (Dds), Karim Ismail Budhwani

All ETDs from UAB

Cancer is poised to become the leading cause of death worldwide with lifetime probability of 1-in-2 men and 1-in-3 women developing cancer. Despite this, research and development of new treatment options remains expensive and slow, in part, due to inadequate disease models, therapy evaluation assays, and absence of delivery control in leading treatment options. These factors also impede patient-specific personalized medicine. Electrohydrodynamic atomization (EHDA) fabrication technologies, such as electrospinning (ESp) and electrospraying (ESy), offer promising nanomedicine pathways toward addressing these challenges. ESp has garnered much interest in tissue engineering but is dwarfed by softlithography in microphysiological systems (MPS), including lab-chip …

A Unified Method For The Design Of Circular Bolted Flange Plate Connections, Pratima Chitrakar

All ETDs from UAB

The use of steel tubular structures for transmission and distribution poles is increasing widely in the U.S as they are easy to construct and install, require less land space and has aesthetic benefits. In these steel tubular structures, the use of bolted flange plate connection is common. The bolted flange-plate connection is used to connect tubular element and transfer load from one element to the other and then to the foundation. The size and thickness of flange-plate connection depend on the applied loads, number of bolts and material type. For the industrial manufacturing purpose, the simplified and unified design method …

An Interdisciplinary Model For The Development Of Alabama Oil Sands, Daniel Edward Smith

All ETDs from UAB

In July 2013, a memorandum of understanding (MOU) was signed by the Governors of the states of Alabama and Mississippi to jointly conduct a comprehensive geologic, engineering, and legal assessment of oil sands resources associated with the Hartselle Sandstone formation including the identification of environmental best practices associated with developing these resources. Pursuant to the MOU, the Geological Survey of Alabama (GSA) began a limited geological evaluation of the potential development of Alabama’s oil sand resources. This dissertation compliments those GSA efforts by identifying and assessing environmental and social sustainability risks associated with the potential development of Alabama’s oil sands …

Geometry- And Image-Based Methods For Analyzing Metal Casting Process Features, William Warriner

All ETDs from UAB

There are no known visual software tools relating metal casting geometry directly to features of the casting process. Solidification simulations do not explicitly disclose defect locations and do not generate rigging geometry. Having geometry-based process feature models would enable cast component designers to improve castability before production. Such models would also allow for a greater degree of workflow automation in casting process optimization. Three papers are written which develop geometry-based process feature models for analysis of metal castings. The first paper explores the relationship between component geometry and solidification order and demonstrates how to rapidly estimate hotspot locations using a …

Intergrading Connected Vehicle Data Into The Transportation Performance Measurement Process, Md Ahsanul Islam

All ETDs from UAB

Transportation system performance measurements are used to evaluate the operating conditions of local and regional transportation systems and determine if they meet national performance goals. Performance measurement is an integral part of the congestion management process and assists transportation agencies to set programmatic and funding priorities and make policy decisions. Transportation system performance measures are currently derived from various sources such as point sensors, automatic vehicle matching technologies, third party vendors, incident and work zone databases, weather databases, video analytics, high-resolution controller data, and management and control sources. Emerging vehicle technologies like connected vehicle (CV) technologies create new opportunities for …

Multimodal Imaging In Schizophrenia, Kristin Lottman

All ETDs from UAB

Schizophrenia is a heterogeneous psychiatric disorder that affects approximately 1% of the population. Due to its heterogeneity, critical gaps in knowledge about the disorder persist as the underlying neural mechanisms and etiology remain poorly understood. In order to fill this gap in knowledge, identification of an imaging biomarker characteristic of schizophrenia’s pathophysiology is critical in not only furthering understanding of the disorder, but also improving patient prognosis and outcome. Attempts toward filling this critical gap in knowledge and thus uncovering the neurobiological basis of schizophrenia are continually being made with neuroimaging and electrophysiological studies. The primary objective of this dissertation …

Inception Of A Cellulose Nitrate-Layered Silicate Nanocomposite Coating: Study Of The Formulation Procedure, Degree Of Dispersion, Coating Properties, And Uv Stability, Precious Mitchell

All ETDs from UAB

Cellulose nitrate lacquer is a coating system that is used in the conservation of silver art pieces in museums. This coating degrades prematurely in the presence of extensive light exposure, which is prominent in display cases, thus comprising the surface of the art piece. When facing this fact, it is imperative to create a new polymer coating system with an in-crease in barrier properties so that the life expectancy of the coating increases. The synthesis of a cellulose nitrate-layered silicate nanocomposite coating stands to enhance the barrier properties of cellulose nitrate through proper dispersion of layered silicates. A proper formulation …

Bioprocess Development For Novel Anti-Cancer Therapies And High Value Biochemical, Jianfa Ou

All ETDs from UAB

Cancer treatment is one of the most daunting challenges of human health improvement. Bioprocess development, or biomanufacturing, is an important step in anti-cancer therapy developments. Novel surface receptors were revealed by integrating proteomics data and live-cell characterization, and were used for antibody design with improved specific targeting. A high titer (>2 g/L) of monoclonal antibody (mAb) was produced by Chinese hamster ovary cells from fed-batch cell culture. Live-cell confocal microscopy imaging and flow cytometry analysis demonstrated the strong and specific binding of the produced mAb to cancer cell lines. The cancer treatment effect of mAb was enhanced through the …