Engineering Commons^™

Automated Fiber Placement: A Review Of History, Current Technologies, And Future Paths Forward, Alex Brasington, Christopher Sacco, Joshua Halbritter, Roudy Wehbe, Ramy Harik

Faculty Publications

Automated fiber placement (AFP) is a composite manufacturing technique used to fabricate complex advanced air vehicle structures that are lightweight with superior qualities. The AFP process is intricate and complex with various phases of design, process planning, manufacturing, and inspection. An understanding of each of these phases is necessary to achieve the highest possible manufacturing quality. This literature review aims to summarize the entire AFP process from the design of the structure through inspection of the manufactured part to generate an overall understanding of the lifecycle of AFP manufacturing. The review culminates with highlighting the challenges and future directions for …

High-Order Deterministic Sensitivity Analysis And Uncertainty Quantification: Review And New Developments, Dan Gabriel Cacuci

Faculty Publications

This work reviews the state-of-the-art methodologies for the deterministic sensitivity analysis of nonlinear systems and deterministic quantification of uncertainties induced in model responses by uncertainties in the model parameters. The need for computing high-order sensitivities is underscored by presenting an analytically solvable model of neutron scattering in a hydrogenous medium, for which all of the response’s relative sensitivities have the same absolute value of unity. It is shown that the wider the distribution of model parameters, the higher the order of sensitivities needed to achieve a desired level of accuracy in representing the response and in computing the response’s expectation, …

Real Time Simulation And Hardware In The Loop Methods For Power Electronics Power Distribution Systems, Michele Difronzo

Theses and Dissertations

System level testing of Power Electronics Power Distribution Systems (PEPDS) can be challenging when fine temporal resolution is required (time step below 100-200ns). In the recent years, our research group has proposed various methods to simulate in real-time PEPDS using FPGAs and time step as small as 50ns. While the proposed methods allow achieving the desired temporal resolution, they are extremely demanding in terms of resources usage and the size of the PEPDS that can be simulated on a single FPGA is strongly limited.

In this dissertation -work that takes as an example application the US Navy electric Ship Zonal …

Development Of Acoustic Metamaterial Noise Barriers And Simultaneously Harvesting Energy Using Smart Materials, Fariha Mir

Theses and Dissertations

In our surroundings abundant energy, we either feel through component vibration or hear noises from acoustic sources. Harvesting these unused and untapped green energy in the form of ambient vibration, and acoustic sounds is an emerging field of research in recent years. Utilization of the energy within a wide band of the frequency spectrum originated from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring sensors, home, and workshop appliances. These abundant sources of green energy are available in almost all the engineering industries, workshops, manufacturing facilities, …

Effect Of Crystal Size On The Failure Mechanics Of Polymer Bonded Explosives, Chizoba Onwuka

Theses and Dissertations

Polymer bonded explosives (PBXs), typically constitute 80-95% of energetic crystals and 5-20% of a soft polymer binder, are widely used in extreme loading conditions such as rocket propellants and explosive munitions because of their high performance and low sensitivity. The particle size of crystals has a significant effect on the mechanical properties of most polymer particulate composites.

In the study, the effect of particle size on the deformation behavior of PBX under dynamic loading is investigated. The study involves testing polymer bonded sugar (PBS) samples, a well-known mechanical simulant of PBXs, with four different crystal sizes: coarse, intermediate, fine and …

Impact Of Acetylcholine On Internal Pathways To Basal Amygdala Pyramidal Neurons, Tyler Daniel Anderson-Sieg

Theses and Dissertations

The basolateral nuclear complex of the amygdala (BNC) – consisting of the lateral (LA), basolateral (BL), and basomedial nuclei (BM) – detects salient environmental stimuli (cue-detection) and motivates appropriate behavioral responses to their implied meaning (cue-guided behavior) via a precise pattern of internal circuitry. Glutamatergic signals representing environmental stimuli enter the LA and split into parallel streams that activate pyramidal neurons (PNs) in the anterior and posterior BL (BLa and BLp), which putatively mediate negative and positive emotions, respectively. The BL is the most densely innervated target of the cholinergic basal forebrain (CBF) and ACh transients (phasic ACh) in cortex …

Purification Of Uranium Tetrafluoride Using Ammonium Bifluoride, Kyle Robert Foster

Theses and Dissertations

Molten salt reactors are being deployed as one of the Generation IV nuclear reactor concepts starting in 2025. While their applications and safety potential are considered extremely advantageous, there is a lack of operating history to draw on, so thorough understanding of proposed molten salt materials’ thermochemical behavior is crucial to their successful implementation.

The most prominent fissile fuel proposed for molten salts is uranium tetrafluoride (UF4) using ²³³U of the thorium fuel cycle. UF₄ is extremely hygroscopic, meaning it will react with moisture and oxygen in its environment, so as-received powders contain significant levels of impurity. In …

Cyclic Triaxial Testing To Evaluate Factors Affecting The Unsaturated Cyclic Behavior Of A Silty Sand, Zachary R. Howard

Theses and Dissertations

This study assesses the cyclic resistance of a non-plastic silty sand, representative of a common mine tailings material. Two series of unsaturated cyclic triaxial tests were conducted, which varied wetting and drying path specimen preparation techniques, initial matric suction, initial net normal stress, and cyclic stress ratio. Specimens prepared using the wetting path experienced significantly higher cyclic resistance than those prepared using the drying path. Specimens that were exposed to higher initial matric suction values experienced higher cyclic resistance than those consolidated with lower initial matric suction values. Initial net normal stress was found to contribute more to specimen cyclic …

Implementation Of Stereo Digital Image Correlation For In-Plane Strain Measurements To Quantify The Anisotropic Behavior, Plastic Flow, And Strain Hardening Of Extruded Aluminum Alloy, Farzana Yasmeen

Theses and Dissertations

The efficient use of metals is important in various industries, including aerospace, automotive, and energy systems. In each case, the type and range of combined loading conditions can be quite different. The approaches to stress analysis of such complex engineering components and assemblies often are limited to elastic conditions. For those cases where components are relatively thin, elastic-plastic conditions are present; there is continuing interest in assessing the accuracy of analytic and computational models for combined loading conditions. In such cases, experiments performed with axial and shear loads (e.g., tension-torsion) provide baseline data regarding the relationship between applied stresses and …

Application Of Digital Transformation In The Water Desalination Industry To Develop Smart Desalination Plants, Ibrahim Yousif

Theses and Dissertations

Fresh water shortage threatens the development and prosperity of many countries including several areas in the United States. Sea and ground water reverse osmosis desalination is rapidly becoming a dominant technology for overcoming water shortage threats by providing cost-effective freshwater production. Digital transformation can be used to help facilitate and advance water treatment technologies by reducing costs and minimizing downtime. Digital transformation is a process that encapsulates digital tools and technologies such as cloud computing, machine learning, artificial intelligence, the internet of things, and virtual/augmented reality. It is a process where objects in the physical world are given virtual replicas …

Role Of Estrogen In Regulating Diet-Induced Obesity In Females, Ahmed Aladhami

Theses and Dissertations

Menopause puts a female at risk for several chronic diseases, including an increased risk of obesity. Estrogens are major sex hormones of females that dramatically decrease during menopause. Several murine studies have established the crucial role of estrogen and estrogen receptor alpha (ERα) on energy homeostasis, glucose metabolism, and insulin action. However, previous works have produced contradicting findings, hence, further work is needed to optimize better outcomes. Therefore, my dissertation focuses on optimizing and characterizing different estrogen-deficient models, as well as using novel double transgenic inducible and tissue-specific models that overexpress aromatase (estrogen producing enzyme) and estrogen receptor isomers alpha …

Study Of The Effect Of B-Cell-Intrinsic Mhcii Antigen Presentation On Germinal Center B Cell Evolution Using The Brainbow Mouse Model, Nia Hall

Theses and Dissertations

Major histocompatibility complex class II (MHCII) are molecules that are essential for B cell activation, as well as clonal competition among activated B cell clones during germinal center (GC) reactions. However, it is unknown to what extent MHCII drives the selection of some clones over others. This is of particular importance since MHCII is highly polymorphic with the ability to indirectly alter gutmicrobiome composition by altering the immunoglobulin A (IgA) repertoire. To study this, we utilized a novel triple-transgenic mouse model to assess how B-cellintrinsic MHCII influences GC responses and GC clonal diversity, with an eyeforward to understanding the relevance …

Impaired Metabolic Flexibility In A Mouse Model Of Leigh Syndrome, Richard Sterling Mccain Jr

Theses and Dissertations

Metabolic dysfunction burdens tissues with high energy demands, particularly the brain. Leigh syndrome is a mitochondrial encephalopathy stemming from genetic defects in the electron transport chain. Leigh syndrome patients develop lactic acidosis, ataxia, bilateral necrotizing lesions in the brainstem and basal ganglia, lesion microgliosis, and eventually death due to respiratory failure. The NADH dehydrogenase [ubiquinone] iron-sulfur protein 4 (NDUFS4) knockout mouse is an established model of Leigh syndrome due to impaired assembly of mitochondrial Complex I that develops motoric deficits and necrotizing lesions in the brainstem vestibular nuclei and olfactory bulb. In addition to the Complex I-derived bioenergetics defect, altered …

The Immune Modulatory Role Of Endocannabinoid Anandamide To Suppress Inflammation Through Regulation Of Microrna And Microbiome, Muthanna Ali Sultan

Theses and Dissertations

Cannabinoids are group of compounds that exerts their anti-inflammatory action through activation of CB1 and CB2 receptors and other minor receptors. In the current study, we investigated the effect of Anandamide (AEA) on Acute Respiratory Distress Syndrome (ARDS) induced by exposure to Staphylococcus Enterotoxin B (SEB) intranasally. We found that C57BL/6 mice treated with AEA showed improvement in the clinical functions of the lungs, accompanied by a decrease in the infiltration of inflammatory cells in the lung tissue, and a decrease in the secretion of pro-inflammatory cytokines. Furthermore, AEA regulated the miRNA profile of the mononuclear cells in the lungs …

On The Need To Determine Accurately The Impact Of Higher-Order Sensitivities On Model Sensitivity Analysis, Uncertainty Quantification And Best-Estimate Predictions, Dan Gabriel Cacuci

Faculty Publications

This work aims at underscoring the need for the accurate quantification of the sensitivities (i.e., functional derivatives) of the results (a.k.a. “responses”) produced by large-scale computational models with respect to the models’ parameters, which are seldom known perfectly in practice. The large impact that can arise from sensitivities of order higher than first has been highlighted by the results of a third-order sensitivity and uncertainty analysis of an OECD/NEA reactor physics benchmark, which will be briefly reviewed in this work to underscore that neglecting the higherorder sensitivities causes substantial errors in predicting the expectation and variance of model responses. The …

Insights Into Rational Catalysts Synthesis, Abolfazl Shakouri

Theses and Dissertations

Atomically distributed metal centers with maximized atom utilization efficiency called single-atom catalysts (SACs) have attracted significant attention in catalysis. SACs with the advantages of both homogeneous and heterogeneous catalysts have been rising as a new frontier in the field of catalysis. New catalytic technologies are ever-growing, considering 90% of all chemical processes employ catalysts, securing modern society’s sustainable future. A classical field in catalysis has been dedicated to catalysis by supported metals. Recently, a vast effort has been devoted to smaller catalyst particles where size is restricted to a single atom on a surface. Single atoms supported or embedded on …

Integration Of Process Planning Into The Automated Fiber Placement Design For Manufacturing Cycle, Alex Brasington

Theses and Dissertations

Automated Fiber Placement (AFP) is a composite manufacturing technique utilizing a robotic or gantry-based system and an attached fiber placement head to lay a prescribed number of strips of composite material, additively forming large composite structures. This technique has enabled increased throughput with increased accuracy and reliability when compared with prior composite manufacturing methods. However, even with the current state-of-the-art AFP process which employs advanced computer simulations and complex robotic operations, the data from various levels of the manufacturing lifecycle is isolated. This results in an incoherent system between the initial design phase and final part completion with limited ability …

Mechanical Strength Of Sic Composite Tubing Under Uniaxial And Multiaxial Loading, Colton Corley

Theses and Dissertations

Silicon carbide fiber reinforced silicon carbide matrix composite is one of the candidate materials for accident tolerant nuclear fuel cladding concepts. In a Nuclear power plant, the reactions between the fuel, cladding, and coolant in a potential loss of coolant accident(LOCA) are of utmost importance to ensure safety in the accident tolerance of such plants. It is for this reason that SiC(silicon carbide) composite tubes have been selected as a possible alternative to the older Zirconium based cladding methods currently used in the industry, which were a partial cause of the Fukushima 2011 meltdown. To serve as fuel cladding, a …

Development Of A Converging-Channel Drop Tower For Sphere Symmetric Isolated Single Droplet Combustion, Nicholas Alexander Demaio

Theses and Dissertations

The dawn of a new Space Age is upon us; Microgravity combustion of hydrocarbon fuels is a popular method of research and characterization. This allows for a one-dimensional analysis by suppressing the buoyancy forces produced by gravity and the large temperature differential between the flame boundary and the surrounding air. The current testing methods are expensive and require extensive preparation on the researchers behalf. There is a need to investigate an alternative method that is inexpensive, repeatable, and comparable to the other approaches that coincides with the literature.

A low-cost converging-channel drop tower was designed and fabricated for sphero-symmetric single …

Combined Effects Of Welding Residual Stress And Thermal Expansion In Cwr, Brennan Gedney

Theses and Dissertations

Continuously welded rail with flash-butt welded joints has become standard practice for railway construction around the world. Through the process of welding, a residual stress field develops in the joint which typically remains in the rail through its service life. Consequently, the total stress is altered locally in the presence of operation induced stresses. One such stress develops due to thermal expansion of the rail during the daily and seasonal solar radiation heating cycle. This paper seeks to ascertain the combined effects of welding residual stress with thermal expansion through computer simulations. This is aimed at two objectives: determining whether …

Computer Vision-Based Automatic Railroad Crossing Monitoring And Track Inspection, Feng Guo

Theses and Dissertations

Currently, there are many imminent challenges in the railroad infrastructure system of the United States, impacting the operation, safety, and management of railroad transportation. In this work, three major challenges which are overcrowded traffic congestion at the grade crossing, low-efficiency and accuracy on inspection of missing or broken rail track components, and dense rail surface defects without quantification, respectively are studied. The congested railroad grade crossing not only introduces significant traffic delays to travelers but also brings potential safety concerns to the first responders. However, limited studies have been devoted on developing an intelligent traffic monitoring system which is significant …

Evaluation Of A Trigonometric Grey Model For Estimating And Predicting Pavement Condition, Amara Kouyate

Theses and Dissertations

States, counties, and municipalities rely on pavement performance curves to forecast future pavement conditions in their jurisdictions. Accurate prediction is essential for budget planning and the identification of candidates for rehabilitation. This study investigates the use of a grey model (GM) to estimate and predict pavement conditions. An advantage of the GMs is that they do not require a large sample size for model estimation. This aspect is important since smaller towns and municipalities often cannot afford to collect pavement condition data frequently due to cost. There are other situations where sample size may be limited, such as using project-level …

Fine Points For Broad Bumps: The Extension Of Rietveld Refinement For Benchtop Powder Xrd Analysis Of Ultra-Small Supported Nanoparticles, Jeremiah W. Lipp

Theses and Dissertations

The goal of this work is to demonstrate the capabilities of benchtop Bragg diffraction in characterizing ultra-small (< 2nm) nanoparticles. To this end we have established a method for accurately separating the background, adjusting for relevant intensity effects, and analyzing the results with Rietveld refinement. This method is applied to the characterization of six silica-supported “noble” metals under ambient conditions: Pt, Pd, Ir, Rh, Ru, and Au. Surprisingly, Bragg diffraction is capable of shining light on this difficult-to-characterize size region – revealing the propensity of these metal nanoparticles to oxidize at room temperature. Preliminary findings for future work are also discussed: extending our method to crystalline supports and fluorescent samples.

Development Of A Rapid Compression And Expansion Machine To Characterize The Ignition Propensity Of Multi-Component Liquid Fuels, Jonathan Joseph Morreale

Theses and Dissertations

Combustion has been the primary source for energy production, whether it be from coal, oil, or natural gas, for a very long time. With increasing population and therefore an increased demand for energy, efficiency is becoming a concern. In order to increase efficiency, engines have been downsized and compression ratios have been increased. In doing so, problems have arisen such as knock and low speed pre-ignition. To better understand these problems, an investigation into how fuels ignite at higher pressures is necessary. Real fuels are comprised of multiple components that exhibit significant variations in their own physical and chemical characteristics. …

Searching Extreme Mechanical Properties Using Active Machine Learning And Density Functional Theory, Joshua Ojih

Theses and Dissertations

Materials with extreme mechanical properties leads to future technological advancements. However, discovery of these materials is non-trivial. The use of machine learning (ML) techniques and density functional theory (DFT) calculation for structure properties prediction has helped to the discovery of novel materials over the past decade. ML techniques are highly efficient, but less accurate and density functional theory (DFT) calculation is highly accurate, but less efficient. We proposed a technique to combine ML methods and DFT calculations in discovering new materials with desired properties. This combination improves the search for materials because it combines the efficiency of ML and the …

An Investigation Of The Ignition Propensities Of Fuels Perturbed By Nitrogen Monoxide, Ackmer Robinson Iii

Theses and Dissertations

Quantitative structure property relationship (QSPR) regression models were developed based on the chemical functional group distribution of toluene reference fuels (TRF, mixtures of n-heptane, iso-octane, and toluene) for RON, MON, and DCN. The QSPR regression models were developed using DCN measurements from this study as well as RON/MON data available in literature. The correlations between RON/MON and DCN were analyzed. The ignition propensity of TRFs perturbed by NO addition was also investigated in this study. The interactions between the chemical functional groups and NO were investigated using an ignition quality tester (IQT). It was found that the increase in the …

Mathematical Model For Sei Growth Under Open-Circuit Conditions, Wei Shang

Theses and Dissertations

An irreversible capacity loss will take place in lithium ions batteries due to the solid electrolyte interface (SEI) creating, which consumes the active lithium and reduces solvent. SEI is either good since it can prevent further electrolyte decomposition or bad for lessening batteries' lifetime. Mathematical modeling of SEI formation is done within a porous electrode to model an empirical battery in the x-direction.A solid electrolyte interphase (SEI) growth model is developed in a mixed-mode which contains solvent diffusion through the SEI layer and its corresponding kinetics of solvent reduction at the electrode surface. The governing equations are numerically solved by …

A Novel Model To Study Adipose-Derived Stem Cell Differentiation, Austin N. Worden

Theses and Dissertations

The use of three-dimensional (3D) culture systems (hydrogels) and adipose-derived stem cells (ADSCs) in regenerative medicine to advance early-stage investigation and modeling of the mechanisms of diseases, treatments, targets, etc. has recently increased. ADSCs, specifically, are utilized due to their innate programming during embryogenesis and in adult tissues in addition to their ability to differentiate into mesodermal, endodermal, and ectodermal cell-specific lineages. Of importance is that these advancements do not involve a model specimen (i.e. mice or rats) and simulate the numerous conflicting signals a migrating cell is exposed to in vivo such as chemokines, extracellular matrix (ECM), growth factors, …

Preparation, Characterization And Evaluation Of Rationally Designed Catalysts By Electroless Deposition, Wen Xiong

Theses and Dissertations

In heterogeneous catalysis, it is a proven factor that the surface-specific activity and the catalyst selectivity strongly depends on the active sites which are determined by the composition, size, and shape of the particle. For structure-sensitive reactions favored by specific surface sites, such as corners, steps, or edges, TOF and selectivity can be greatly changed by the size of catalyst particles since the active site distribution will change with the size of the catalysts. Usually, metal particles are synthesized by two methods in industry, namely precipitation and impregnation, which often exhibit a broad size distribution. The grand challenge of colloidal …

Operating Strategies And Disturbance Characterization For Dc Microgrids, Miles Leonard-Albert

Theses and Dissertations

The present state of the electrical grid is unable to meet the demands of transmission. Digital twin technology provides a promising solution to this problem by allowing for analysis and control of distributed energy resources. This thesis presents initial work towards development of a digital twin for a DC power system. Two versions of the DC power system are created and evaluated against randomly generated load profiles. System performance is evaluated on the basis of the quantity of the load that is unserviced by the generation and energy storage. Energy storage operating strategies that modify the model to prioritize different …