Engineering Commons^™

Experimental Analysis Of The Automated Fiber Placement Manufacturing Parameters For High And Low Tack Prepreg Material, Anis Baz Radwan

Theses and Dissertations

Automated Fiber Placement (AFP) is a flexible but complex manufacturing technique which is used to layup carbon fiber tows into flat or curved structures. That could be achieved through linear and steered paths of fibers. The quality of AFP layup is highly dependent on the manufacturing process parameters such as layup temperature, tow feedrate, compaction force, and tow tension. Understanding how those parameters affect the process is crucial for achieving the desirable quality and productivity. For this work, an experimental investigation is carried out to determine the processing window that yields optimal quality for two types of material: High tack …

Astrocyte Sensitivity To Dopamine In Culture And Ex Vivo, Ashley L. Galloway

Theses and Dissertations

Dopamine is critical for processing of reward and etiology of drug addiction. Astrocytes throughout the brain express dopamine receptors, but consequences of astrocytic dopamine receptor signaling are not well established. This thesis illustrates effects of dopamine on cultured astrocytes and astrocytes in brain slices (ex vivo). In striatal cultures, extracellular dopamine triggered changes in astrocytic Ca²⁺ signaling and rapid concentration-dependent stellation of astrocytic processes that was not a result of dopamine oxidation, but instead relied on both cAMP-dependent and cAMP-independent dopamine receptor signaling. To isolate possible mechanisms underlying these structural and functional changes, whole-genome RNA sequencing was …

Flame Spray Pyrolysis Of Ce-Mn Solid Solutions For Catalytic Applications, Nicole Cordonnier

Theses and Dissertations

Flame spray pyrolysis (FSP) is a method of quickly synthesizing active particles in a flame. Precursors are dissolved in a flammable organic solvent before being sprayed into the flame environment where they rapidly burn. Particle formation occurs on the order of 10 milliseconds. FSP has been shown to be a viable method of producing materials on an industrial scale, capable of producing grams of particles per minute. Metastable structures which exist in the liquid phase, but are difficult to synthesize using traditional impregnation methods can be formed with FSP due to fast quenching times. For example, solid solutions of Ce-Zr …

Machine Learning Methods For Rapid Inspection Of Automated Fiber Placement Manufactured Composite Structures, Christopher Sacco

Theses and Dissertations

The advanced manufacturing capabilities provided through the automated fiber placement (AFP) system has allowed for faster layup time and more consistent production across a number of different geometries. This contributes to the modern production of large composite structures and the widespread adaptation of composites in industry in general and aerospace in particular. However, the automation introduced in this process increases the difficulty of quality assurance efforts and inspection. The AFP process can induce a number of manufacturing defects including wrinkles, twists, gaps, and overlaps. The manual identification of these defects is often laborious and requires a measure of expert knowledge. …

Development Of An Automated Fiber Placement Process For The Fabrication Of Thermoplastic Composite Laminates, Anthony M. Sabido

Theses and Dissertations

An automated fiber placement process is desired for manufacturing variable-stiffness thermoplastic composite laminates. By developing such a composite laminate, it is possible to take advantage of the tunable performance increases that are achievable by spatially steering individual tows. In addition, using a thermoplastic polymer as the matrix material has many advantages: a high toughness, ability to employ thermoplastic joining processes that do not require adhesives, long storage life, and lacks the need to be refrigerated. This process was experimentally developed, where the effect of various process parameters on the quality of the laminate were evaluated. An experimental AFP head was …

Dc Bus Stabilization And Dynamic Performance Improvement Of A Multi-Converter System, Silvia Arrua

Theses and Dissertations

Evolution of semiconductor devices is allowing to implement power electronics technology in a variety of applications, moving traditional AC systems to more efficient and reliable DC systems. Some examples are shipboard power distribution systems, DC microgrids, electric vehicles and more electric aircrafts. Even though these types of systems offer significant advantages that make them attractive in different areas, the interconnection of feedback-controlled power converters leads to emergent dynamic behavior that a system designer must take into account to ensure proper operation of the system. Additionally, system reconfiguration is very likely to happen in applications such as a shipboard power distribution, …

Epigenetic And Purinergic Regulation Of Mast Cells Mediator Release, Zahraa Abdulmohsin Mohammed

Theses and Dissertations

Mast cells (MCs) are well known for their implications in allergic reactions. They are also known to have multiple functions in the innate and adaptive immune system. Their activation plays an essential role in many aspects of physiological and pathological conditions. Allergies are considered chronic conditions that affect more than 60 million people in the U.S. These diseases are driven by the activation of MCs in response to IgE-mediated antigen, rendering these cells as targets for the management of allergies and asthma. Therefore, this research considers the understanding of their activation and the regulation of their response to be an …

Modeling Particle Dispersal In Bedload Dominated Settings, Sanaz Borhani

Theses and Dissertations

Tracer particles are used to study bedload transport in gravel bed rivers. One of the advantages associated with their use is that they allow for direct measurements of particle entrainment rates in bedload transport and particle displacement. The main issue in field studies with tracer particles is the difference between tracer short term and long term behavior. This difference is due to the fact that particles undergo vertical mixing or move to less active locations such as bars or even floodplains. For these reasons the mean tracer velocity decreases over time. This phenomenon has been called tracer slowdown and it …

Damage Evaluation Of Concrete Structures Using Acoustic Emission, Rafal Anay

Theses and Dissertations

The deterioration and aging of the infrastructure in the U.S. have become a crucial issue, especially for highway bridges and nuclear power plants. The reliability and safety of existing structures are affected by growing populations and limited resources. This issue has gained significant concern during the last two decades and efforts are being conducted to accelerate the improvement of nondestructive testing (NDT) and structural health monitoring (SHM) methods. Additional information regarding the condition of existing structures and the early detection of damage can aid in reducing overall maintenance costs. The studies presented in this dissertation employ acoustic emission (AE) as …

Damping In Transient Pressurized Flows, Sahad Salim Elyass Khilqa

Theses and Dissertations

Piping systems are commonly designed to withstand the first transient pressure peak, which is unaffected by dissipation. However, for multiple operations of control equipment, e.g., pump start-up following pump shutdown, load acceptance following load rejection on hydraulic turbines, etc., an accurate prediction of the dissipation of pressure oscillations is needed to determine a suitable time for the second operation. For this purpose, a method is presented to compute the dissipation of pressure oscillations in piping system following a simple procedure used for computing the dissipation of vibrations of bridges and other structures. Similar to structural engineering, this method is simple …

Health Monitoring Of Liquid Pipelines, Mohammed Hameed Sabhan Al-Tofan

Theses and Dissertations

The crude and refined oil, water, and other liquids are widely transported through pipelines over long distances within geographical boundaries of countries or beyond. Pipeline accidents, however, are frequent, affecting operation and reducing targeted performance. The frequency of these accidents presents a growing concern and necessitates the need for an effective health monitoring plan. This plan requires monitoring of flow conditions and warning of any changes or abnormal conditions. Abnormalities in the flow conditions include changes in the piping system performance due to defects, such as leaks and blockages. These changes can be located and quantified utilizing different approaches. Two …

The Study Of Flow Hydrodynamics And Transport Processes Over Mixed Bedrock-Alluvial Reaches, Mohammad Sadegh Jafarinik

Theses and Dissertations

Research efforts on mixed bedrock-alluvial rivers primary focused on the bedrock incision and very few studies investigated the alluvial morphodynamics of such systems. To the best of my knowledge none of these models have been considered the spatial variability of the sediment grain size of the bed surface in mixed bedrock-alluvial reaches and very few models focused on the spatial changes in alluvial cover within these reaches. Furthermore, a perusal of the literature on mixed bedrock-alluvial river morphodynamics reveals that very little information is available on 1) bedform geometry and flow resistances and 2) sediment sorting patterns in presence of …

The Contribution Of Adipose Tissue From Ovariectomized Mice To Colon Cancer, Meredith Smith Carson

Theses and Dissertations

Obesity is considered a major public health concern worldwide due to the increased incidences of metabolic dysfunction and cancer risk. The obese state is, in part, attributable to the overconsumption of calorie-dense foods commonly seen in a standard Western diet, which aids in the progression of chronic, lowgrade inflammation. The role of estrogen varies depending on menopausal status, where estrogen deficiency coupled with increased visceral fat associated with post-menopause leads to increased secretions of pro-inflammatory adipokines and cytokines. However, the presence of estrogen in a premenopausal state has been shown to attenuate the pro-inflammatory response, which has been demonstrated when …

Experimental Methods And Techniques For Improved Biomechanical Characterization Of Diverse Murine Aortopathies, Brooks Alexander Lane

Theses and Dissertations

Aortopathies constitute a broad class of diseases affecting the aorta – the largest artery responsible for distributing oxygenated blood to the systemic circulation. Specifically, aortic aneurysms (AAs) are described as a focal dilation of the vascular wall exceeding 50% of the normal vessel diameter. Ultimately AAs may stabilize, dissect, or rupture, with the latter virtually ensuring mortality. Currently clinicians consider prophylactic intervention based on size and growth-rate criteria that have been estimated from large-cohort statistical analyses. These criteria, however, fail to address the underlying mechanisms. Furthermore, 13% of small-to-mid sized AAs have been found to rupture prior to meeting these …

Effect Of Tcdd, An Environmental Contaminant, On Activation Of Ahr Leading To Induction Of Myeloid Derived Suppressor Cells (Mdscs) And The Ability Of Resveratrol, A Botanical, To Neutralize This Effect, Wurood Hantoosh Neamah

Theses and Dissertations

Aryl hydrocarbon receptor (AhR), is a ligand-activated transcription factor that integrates environmental, dietary, microbial and metabolic cues to control various cellular processes, such as the cell cycle, epithelial barrier function, cell migration and immune function. AhR was discovered as the receptor that binds with high affinity to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and leads to numerous of toxicological outcomes. In the current study, we discovered a critical role played by AhR, following activation by TCDD, in modulating a variety of immunological functions through regulation of epigenetic and microbial pathways. Our data demonstrated that AhR activation triggers MDSC mobilization from bone marrow to peritoneal …

Role Of Epigenetic, Molecular And Cellular Pathways In The Regulation Of Inflammation, William James Becker

Theses and Dissertations

Dysregulated inflammation is at the heart of countless human diseases. Graft rejection is the process by which an organ from an incompatible donor is rejected by the recipient whose immune cells attack the foreign tissue. Colitis is an inflammatory disorder caused by undue chronic inflammation in the colon and rectum that can progress to cancer. Colitis incidence is on the rise, especially in developing nations and Asia; and the list of patients who need organ transplants grow by the day. Therapies for both graft rejection and colitis are limited to immunosuppressive drugs that leaves patients vulnerable to infection, heart disease, …

Enhancing Thermal-Hydraulic Performance Of Parallel And Counter Flow Mini-Channel Heat Sinks Utilizing Secondary Flow: A Numerical And Experimental Study, Amitav Tikadar

Theses and Dissertations

Continual growth of hydraulic and thermal boundary layers along stream wise direction in conventional straight fin mini-channel heat sink causes gradual deterioration of their thermal performance. To enhance thermal-hydraulic performance by breaking and redevelopment of the boundary layers, this research aims to introduce a novel inter-connected mini-channel sinks. Two inter-connectors were positioned transversely between two adjacent mini-channels, which segmented the flow domain into three zones. Secondary flow was generated through the inter-connectors utilizing the pressure difference of the adjacent channels resulting in hydraulic and thermal boundary layers disruption and hence enhanced thermal-hydraulic performance of the mini-channel heat sink was achieved. …

3d Topology Optimization Of Spatially Reinforced Composites, Luis G. Bahamonde Jácome

Theses and Dissertations

Topology optimization is a numerical design tool used to generate structural concepts that present optimal load paths for a given set of functional requirements. This functional generative design capability has been used to lightweight high performance structures with 1D, 2D and 3D stress states. On the other hand, fiber-reinforced composites are the perfect candidate material to use in high performance structures due to the tailorability of their stiffness and strength properties. Although numerical tools that simultaneously tailor the composite material properties while optimizing the structural topology exist, these tools are inherently limited to 1D and 2D stress states.

This work …

Mechanical Characterization And Non-Destructive Evaluation Of SicF/SicM Composites For Nuclear Applications, Donald J. Mccleeary

Theses and Dissertations

The SiC_f/SiC_m composite material is a promising candidate for accident tolerant fuel cladding in light water reactors and for structural elements in high temperature reactors. The material demonstrates exceptional toughness when compared to monolithic ceramics. It is critical to characterize the mechanical behavior, internal damage and ultimate strength of these composites under relevant loading conditions. In this thesis, the author developed and improved several mechanical characterization and non-destructive evaluation methods and applied them to SiC_f/SiC_m composites. Impulse excitation (IE) analysis of damaged SiC_f/SiC_m composite disks following controlled impact testing shows a …

Interdependent Mechanisms Of Stress Susceptibility, Julie Elaine Finnell

Theses and Dissertations

Social stress is a significant risk factor for the emergence of psychiatric disorders including depression and anxiety. While there are a number of commercially available therapeutic options for the treatment of these disorders, these treatments require weeks of continuous use to produce behavioral efficacy. It has also been suggested that these traditional therapies are only marginally effective in producing complete remission, suggesting that our understanding as it pertains to the mechanisms underlying stressinduced behavioral dysfunction is still in its infancy. In the last few years, inflammation has become a major focus in the field of stress and depression as clinical …

Implementation Of View Factor Model And Radiative Heat Transfer Model In Moose, Abdurrahman Ozturk

Theses and Dissertations

View factors are functions that represent the geometric relationship between surfaces. They are important parameters for radiative heat transfer calculations. View factor catalogues are available for simple geometries in the current literature. However, in the case of complicated geometry, analytical or numerical methods are needed to evaluate view factors. The Monte Carlo (MC) method is the most flexible one among numerical methods, which are used to calculate view factors, since it can be applied to any geometry.

When experimental studies are not affordable to conduct, modeling of engineering problems gains more importance. Idaho National Laboratory (INL)’s finite element framework Multiphysics …

A Model For Condensation Heat Transfer In Hydrophobic-­Hydrophilic Surfaces, Abdulwahab E. Alhashem

Theses and Dissertations

The primary focus of this research is to provide a validated model for a comprehensive understanding of hydrophobic-­‐hydrophilic condensation on patterned-­‐ hybrid surface. Establishing the model requires the modeling of fully dropwise condensation (DWC) before applying modifications to evaluate heat transfer performance of patterned-­‐hybrid condensation surface.

The model for fully DWC consists of defining expressions for heat transfer through a single drop, maximum radius of the drop and drop-­‐size distribution which all are primarily based on the work in the literature. In this work the author utilized a proposed modified version of the simulation for drop-­‐size distribution for fully DWC, …

Too Agile? - Devops Software Development Challenges In A Military Environment, Burl T. Kenner Iii

Theses and Dissertations

Agile and DevOps software development processes now represent proven, commonly accepted models in commercial industry. For DoD military environments however, empowering teams of software developers and end user operators to build, test and release solutions without direct oversight and management of leadership is a brand new experience. In 2017, a DoD software acquisitions revolution occurred when approval was granted to scrap the former ineffective, cost prohibitive process and initiate the agile DevOps model. After one year since its introduction, this paper may represent the very first look at how well this nontraditional process is working out in a military command …

Impact Of Cycloalkanes On Ignition Propensity Measured As Derived Cetane Number In Multi-Component Surrogate Mixtures, Dalton Odell Carpenter

Theses and Dissertations

Cycloalkanes are one type of hydrocarbons present in real jet fuels. The distinct cyclic structure of the cyclo-alkanes impacts the chemical kinetic behavior differently compared to n- and iso-alkanes. At high temperatures, thermal decomposition reactions dominate, producing n-alkyl radicals similar to the oxidation reactions of n-alkanes thus promoting the reactivity. Whereas in low temperatures, the presence of the ring structure essentially suppresses the formation of alkylhydroperoxy radicals (QOOH) from alkylperoxy radicals (RO2), thus exhibiting similar reactivity to iso-alkanes. In previous generations of surrogate fuels, the cyclo-alkane functional group were largely ignored due to low levels of cycloalkanes in traditional jet …

Liquid Phase Modeling In Heterogeneous Catalysis, Mohammad Shamsus Saleheen

Theses and Dissertations

Conversion of lignocellulosic biomass into transportation fuels or commodity and specialty chemicals will be an important and fast-growing industry within the United States over the coming decades. Its growth will be driven by a variety of factors, including increased energy demands, environmental considerations, national security, and government mandates. To achieve the desired energy efficiency and economic impact, the emerging biorefining industries need novel heterogeneous catalysts with exceptional activity, selectivity, and stability. Catalytic materials developed in the petrochemical industries are generally not suitable for processing highly functionalized feedstocks typical of the biorefinery landscape. Due to the characteristics of this biomass feedstock …

Acoustoelastic Metamaterial With Simultaneous Noise Filtering And Energy Harvesting Capability From Ambient Vibrations, Fariha Mir

Theses and Dissertations

Harvesting unused and untapped energy from ambient vibration noise and acoustic sound waves is an emerging field of research in the recent years. Utilization of the energy with a wide band of the frequency spectrum from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring (SHM) sensors and home and workshop appliances. Various sources of ambient vibration and acoustic noise can be found around us in our everyday life. These sources are abundant in almost all the engineering industries and manufacturing facilities for example in aerospace, mechanical …

Three-Dimensional Plasma Cell Survival Microniche In Multiple Myeloma, Katrina A. Harmon

Theses and Dissertations

Multiple myeloma (MM) is an incurable malignancy characterized by the uncontrolled proliferation of long-lived plasma cells (PCs) in the bone marrow (BM), which constitute at least 10% of BM cellularity. Normally, long-lived plasma cells make up less than 1% of BM cells. Plasma cells become neoplastic when a clonal PC population produces a monoclonal immunoglobulin protein. A diagnosis of monoclonal gammopathy of undetermined significance (MGUS) is made when there is an increase in monoclonal PCs within the BM, but less than 10%, and the patient does not present with end-organ damage, which is associated with active MM. Though not considered …

Continuous Tow Path Generation For Constant And Variable Stiffness Composite Laminates On Single And Double Curved Surfaces, Caleb R. Pupo

Theses and Dissertations

A novel approach for the generation of steered tow paths on curved shell surfaces is presented. The approach is used to translate optimal theoretical analysis expressed from ply to ply as fiber angle distributions for steered laminates into discrete tow paths on planar, single and double curved surfaces. By adapting the multi mesh approach earlier developed by van Tooren and Elham [1–3] to the new tow path generation code. Two meshes are utilized, a coarse mesh which is generated during the optimization and contains the optimal fiber angle distributions, and a denser mesh obtained from tessellating the surface to better …

Modeling Complex Oxides: Thermochemical Behavior Of Nepheline-Forming Na-Al-Si-B-K-Li-Ca-Mg-Fe-O And Hollandite-Forming Ba-Cs-Ti-Cr-Al-Fe- Ga-O Systems, Stephen A. Utlak

Theses and Dissertations

High concentrations of Na2O and Al2O3 in the liquid high-level radioactive waste (HLW) stored at the Hanford Site can cause nepheline (NaAlSiO4) to precipitate in a vitrified monolithic waste form upon cooling. Nepheline phase formation removes glass- former SiO2 and -modifier Al2O3 from the immobilization matrix in greater proportion to alkalis, which can reduce glass durability and consequently increase the leach rate of radionuclides into the surrounding environment.

Current uncertainty in defining the HLW glass composition region prone to precipitating nepheline necessitates targeting a conservative waste loading, which raises operational costs by extending the liquid radioactive waste disposal mission and …

Plasma Surface Functionalization Of Afp Manufactured Composites For Improved Adhesive Bond Performance, Ibrahim Sarikaya

Theses and Dissertations

High-performance composite structures not only require a reliable fabrication process when creating primary structures, but also a high fidelity and repeatable bonding process for the assembled components. During the assembly process, surface contaminants are a major concern as they have the potential to compromise the bond quality resulting in poor bond strength, low failure load, and undesirable failure modes of the adhesively bonded structures. This is further complicated by composite materials inherently possessing low surface energy and thus exhibiting low adhesive property. Therefore, detecting and removing contaminants on the pre-bond composite surface is an active research topic in pursuit of …