Engineering Commons^™

Grafting Based Thermoplastic-Thermoset Bonding For Aerospace Structures, Saurabh Vaidya

Theses and Dissertations

The use of carbon fiber composites is rapidly increasing in the aerospace industry. Fiber reinforced plastic composites can primarily be classified as thermoplastic and thermoset, both offer unique advantages over one another. Thermosets cure at relatively low temperature and in general, are lower priced than thermoplastic composites. However, the cost of autoclave for the curing of thermosets is a major drawback. On the other hand, thermoplastics are showing higher damage tolerance. They can be re-melted and re-consolidated and have the potential to be re-used / recycled. The repair of TP composites is not developed yet. Therefore, both the types attract …

Multi-Robot Coordination With Environmental Disturbances, Adem Coskun

Theses and Dissertations

Multi-robot systems are increasingly deployed in environments where they interact with humans. From the perspective of a robot, such interaction could be considered a disturbance that causes a well-planned trajectory to fail. This dissertation addresses the problem of multi-robot coordination in scenarios where the robots may experience unexpected delays in their movements.

Prior work by Čáp, Gregoire, and Frazzoli introduced a control law, called RMTRACK, which enables robots in such scenarios to execute pre-planned paths in spite of disturbances that affect the execution speed of each robot while guaranteeing that each robot can reach its goal without collisions and without …

Instrumentation And Experimentation Development For Robotic Systems, Tristan Kyzer

Theses and Dissertations

Localization of robotic systems is a necessity for control of robotic systems and often requires the use of costly sensors and equipment onboard the robot or installed within a facility. GPS or GNSS sensors are effective for localizing robots in GPSaccessible environments, but do not work as well in dense urban areas or inside fully enclosed buildings, such as factories or warehouses. Sensors such as LiDAR can be costly and require substantial experience and knowledge to utilize as well as potential changes to infrastructure for use. Computer vision-based localization systems offer potential as a localization solution for various applications. A …

Nondestructive Evaluation And Structural Health Monitoring Of Manufacturing Flaws And Operational Damage In Composite Structures, Robin James

Theses and Dissertations

Advanced composite materials have begun to be used extensively in the manufacturing of aerospace structures. Composite aerospace structures can develop complex types of damages during the manufacturing stages and operational lifetime. This creates an indispensable demand for appropriate nondestructive evaluation (NDE) and structural health monitoring (SHM) methods that are tailored to specific types of damage. This dissertation addresses innovative methods for NDE and SHM of manufacturing flaws and operational damage in composite structures.

For the NDE of manufacturing flaws in carbon fiber reinforced polymer (CFRP) composites, an eddy current testing (ECT) NDE method has been developed by conducting multiphysics modeling …

Rehabilitation Of Timber Piles Using Fiber Reinforced Polymers Analyzed With Acoustic Emission, Rebekah Marie Krol

Theses and Dissertations

Assessing the current state of infrastructure and implementing strengthening or rehabilitation methods on old or damaged members is important to ensure safety and longevity of structures. Non-destructive testing is an important tool for localizing and characterizing damage in structures, especially structures that are more susceptible to damage because of age or environment. In addition to locating inadequate members, it is essential to have a repair technique in place so that the structure can continue to be used in a safe manner.

This study aims to review the use of acoustic emission for evaluating damage obtained in timber piles subjected to …

Role Of Ahr Ligands In Immune Modulation To Suppress Inflammation Through The Regulation Of Microrna And Gut Microbiome, Osama Azeldeen Abdulla

Theses and Dissertations

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and an environmental sensor that is highly conserved evolutionarily. It was first discovered in the early 1970s for its ability to bind with high affinity to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an environmental pollutant and induce a xenobiotic-metabolizing enzyme known as aryl hydrocarbon hydroxylase (AHH). AhR was shown to regulate TCDD-mediated toxicity against a variety of tissues including the immune system. More recently, AhR has been characterized as key regulator of the immune system, specifically the differentiation of T cells. Also, several AhR ligands have been characterized in addition to TCDD such as …

Temperature Dependence Of Electroluminescence And Current-Voltage Characteristics Of Arrays Of Deep Ultraviolet Algan Micropixel Led, Dhruvinkumar Prakashchandra Patel

Theses and Dissertations

III-Nitride based deep ultraviolet (DUV) light emitting diodes are non-toxic light sources that are highly desirable to replace current mercury lamp-based technology for air and water purification, surface and object disinfection, and sterilization. In the present. By freezing out defect related conduction pathways at temperatures less than 50K, the external quantum efficiency (EQE) of an interconnected array of 1,296 AlGaN DUV micropixels is improved by 4 times, underscoring the importance of defect management. Assuming a current injection efficiency (CIE) of 100% and considering that the light extraction efficiency (LEE) is constant with temperature, the 4-fold increase in the EL signal …

An Acoustic Emission And Artificial Intelligence Approach To Structural Health Monitoring For Aerospace Application, Joseph Chandler Garrett

Theses and Dissertations

In the area of aerospace and other applications, structural health monitoring (SHM) has been a significant and growing area of research in recent years. Throughout the operational life of aerospace structures, various damage scenarios may manifest, and it is of great concern to the aerospace community to develop methodologies for detecting and assessing these damage scenarios. In this paper, fundamental research on the use of the acoustic emission (AE) approach to SHM for fatigue crack growth is presented. In general, the AE approach to SHM and non-destructive evaluation (NDE) involves the sensing of ultrasonic Lamb waves propagating through a structure. …

Discovery And Investigation Of Ammonia Decomposition Catalysts, Katherine Mccullough

Theses and Dissertations

Liquid ammonia can be used as a hydrogen transportation and generation source for use in PEM fuel cells. Current Ru catalysts for ammonia decomposition contain high loadings of Ru and require reaction temperatures at or above 550°C to attain equilibrium conversion. For on-site hydrogen generation, it is of interest to combine hydrogen generation from ammonia decomposition directly with PEM fuel cells. For this occur, operating temperatures need to be considerably lowered and effluent concentrations of ammonia need to be minimized to avoid poisoning of the membrane. Therefore, it is of interest to develop a low-cost catalyst that exhibits high activity …

Mitigating Corrosion And Enhancing Energy Density Of Zinc-Based Anodes In Primary And Secondary Aqueous Batteries, Ehsan Faegh

Theses and Dissertations

Today Lithium-ion (Li-ion) batteries are the most-emphasized battery technology among the many different battery systems in the market. However, due to their high cost (especially for electric vehicle applications), flammability and toxicity, the development of inexpensive and safer alternative battery chemistries has been the focus of a significant amount of recent research. Among various battery chemistries, Aluminum-based (Al-based) and Zinc-based (Zn-based) batteries have been touted as promising options to compete with Li-ion batteries. However, the practical realization of Al battery chemistries has been difficult over a long period of time (170 years) due to a number of fundamental and intrinsic …

Separate Effects Tests For Studying Thermal Gradient Driven Cracking In Uo2 Pellets Undergoing Resistive Heating, Sobhan Patnaik

Theses and Dissertations

A variety of normal operation and accident scenarios can generate thermal stresses large enough to cause cracking in light-water reactor (LWR) fuel pellets. Cracking of fuel pellets can lead to reduced heat removal, larger centerline temperatures, and localized stress in cladding, all of which impact fuel performance. It is important to understand the temperature profile on the pellet before and after cracking to improve cracking models in fuel performance codes such as BISON. However, in reactor observation and measurement of cracking is very challenging owing to the harsh environment and design of fuel rods.

Recently, a state-of-the-art experimental pellet cracking …

Degradative Processes Of Commercial And Next-Generation Lithium-Ion Battery Materials, Benjamin Ng

Theses and Dissertations

The work embodied in this thesis bridges the gap between modern and next-generation Li-ion batteries (LIBs). First, a detailed study of the complex interfacial interactions (e.g. electrode/electrolyte, particle/particle, particle/solid-electrolyte interphase) in existing LIBs (graphite anode, Li(Ni_0.5Mn_0.3Co_0.2)O_2 cathode) are investigated and then used to develop strategies for safer, more energy-dense, and more durable electrode materials (i.e. tailored hybrid materials). The first portion of this thesis focuses heavily on decoupling the complex thermodynamics, reaction kinetics, and mass transport properties in commercially available LIBs. This thesis includes a detailed investigation into the operating parameter space for LIBs, including temperature (-30^oC to +52^oC), state-of-charge …

Experimental Investigation Of Spray Cooling Integrated With A Modified Vapor Compression Refrigeration System Using Several Refrigerants, Nabeel Mukhlif Abdulrazzaq

Theses and Dissertations

Spray cooling has gained increasing interest over the last three decades due to its high thermal performance as a direct cooling technique. Researchers are investigating spray cooling in thermal management systems for electronic applications, particularly focusing on the use of dielectric fluids including FC-72, FC-87, ammonia, and refrigerants such as R113 and R134a. Their studies indicate that the usage of dielectric fluids as a working fluid in spray cooling systems is promising and has significant thermal performance enhancement, which is suitable for a wide range of electronic applications. However, several deficiencies have been identified with the working fluids studied thus …

Physical Modeling Of Backward Erosion Piping Phenomenon In A Geotechnical Centrifuge, William Fernando Ovalle Villamil

Theses and Dissertations

Backward erosion piping is a mechanism of internal erosion that has been widely recognized as a potential hazard for water-retaining structures, such as dams and levees, that are founded on granular materials. Backward erosion piping initiates toward the downstream zone of the structure by the concentration of flow at an exit point acting as drainage, which leads to a localized loosening of the soil and eventually to a continuous migration of grains from the foundation following a piping path pattern. Such piping path extends backward toward the impoundment once a certain critical hydraulic condition is met, resulting in the loss …

Mechanism Of Therapeutic Efficacy Of New Drugs In Glioblastoma, Firas Hameed Khathayer

Theses and Dissertations

Glioblastoma is the most malignant and prevalent brain tumor in adults. It can grow and spread quickly causing harm to brain health. The deregulation of epigenetic mechanisms is considered the main agent in the developing of GBM. One of the enzymes involved in epigenetic alternation and cancer development are histone deacetylases enzyme (HDAC) by removal acetyl group from histone and create condensed chromatin that suppresses transcription gene to histone and non-histone proteins involved in tumorigenesis. Histone deacetylase inhibitors (HADCi) are the most common therapeutic methods for many types of cancer treatments. In the present study, we used relative HDAC inhibitor …

Failure Of Ultra-High Molecular Weight Polyethylene Yarns (Uhmpwe) Under Transverse Loading Using Different Indenter Geometries, Karan Shah

Theses and Dissertations

Ultra-high molecular weight polyethylene (UHMWPE) Dyneema® SK-76 fibers are widely used in personnel protection systems. Transverse ballistic impact onto these fibers results in complex multiaxial deformation modes such as axial tension, axial compression, transverse compression, and transverse shear. Previous impact studies on high performance yarns and quasi-static transverse loading of single fibers using different indenter geometries show premature failure of yarns and single fiber caused by the degradation of tensile failure strain due to the presence of such multi-axial deformation modes. However, there is a dearth of failure criterion in the literature for ballistic applications that considers the contribution of …

Nano-Engineered High-Performance Copper-Water Heat Pipes, Ahmed A. Abdulshaheed

Theses and Dissertations

Recently, heat pipes have gained an exceptional reputation as passive systems. They have become an attractive choice for many engineering applications due to their simple design, high rate of heat transfer, low weight, and low cost of maintenance [1]. A Heat pipe consists of a vacuumed shell filled partially with a compatible working fluid. Three main sections comprise a heat pipe: evaporator, adiabatic, and condenser section. The heat pipe utilizes the principle of evaporation and condensation for operations, i.e., the phase change of working fluid. Heat pipe allows high heat rates to transfer over considerable lengths with minimum temperature differences …

Experimental And Computational Investigations Of Type Iii Deep Eutectic Solvents For Btx Removal From Light Naphtha, Kyle Mcgaughy

Theses and Dissertations

Light naphtha is a crucial chemical feedstock that is used to make value-added products from plastic to fuels. Whether it is derived from fossil fuels or renewable resources, naphtha typically contains small fraction of aromatic contaminants such as benzene, toluene, and xylene (BTX). Polar solvents such as sulfolane, ethylene glycol, and glycerol are industrially used to separate BTX from naphtha. Each of these solvents has some processing difficulties though, whether it be sulfolane degrading and corroding equipment or ethylene glycol and glycerol not being particularly selective for BTX over light naphtha. Some of the traditional solvents used for naphtha purification …

Coal Pyrolysis Models For Use In Massively Parallel Oxyfuel-Fired Boiler Simulations, Andrew Perry Richards

Theses and Dissertations

Accurately modeling key aspects of coal combustion allows for the virtual testing and application of new technologies and processes without the need for investments in lab- and pilot-scale facilities, since such facilities may only be used for a few small tests. However, modeling of subprocesses must not only be accurate but computationally efficient. Modeling of coal devolatilization reactions and processes are one of the important parts of large-scale simulations of coal combustion systems. The work presented here details efforts to improve the modeling of coal devolatilization processes in massively-parallel simulations of coal combustors, including: (1) devolatilization rate/yield models, (2) modeling …

A New Method And Python Toolkit For General Access To Spatiotemporal N-Dimensional Raster Data, Riley Chad Hales

Theses and Dissertations

Scientific datasets from global-scale scientific models and remote sensing instruments are becoming available at greater spatial and temporal resolutions with shorter lag times. These data are frequently gridded measurements spanning two or three spatial dimensions, the time dimension, and often several data dimensions which vary by the specific dataset. These data are useful in many modeling and analysis applications across the geosciences. Unlike vector spatial datasets, raster spatial datasets lack widely adopted conventions in file formats, data organization, and dissemination mechanisms. Raster datasets are often saved using the Network Common Data Format (NetCDF), Gridded Binary (GRIB), Hierarchical Data Format (HDF), …

Engineering Cell-Free Protein Expression Systems For Biotherapeutics And Biosensing, John Porter Hunt

Theses and Dissertations

Therapeutic proteins have become a cornerstone of modern medicine since the FDA approval of recombinant human insulin in 1982. Likewise, biosensors transform chemical detection and disease diagnostics by identifying biomarkers, chemical contaminants, and infective agents. Long-standing methods for creating therapeutics and biosensors employ whole cells such as Escherichia coli (E. coli). Alternatively, cell-free protein synthesis (CFPS) employs the enzymatic reactions necessary for protein production and biosensing within a cell, but in an engineered reactor environment facilitating unprecedented access to and control over biochemical machinery, preservation by cryodesiccation for portable deployment, and functionality in cytotoxic applications. This dissertation reports advances in …

Evaluation Of Concrete Bridge Decks Comprising Twisted Steel Micro Rebar, Aubrey Lynne Hebdon

Theses and Dissertations

The objective of this research was to investigate the effects of twisted steel micro rebar (TSMR) fibers on 1) the mechanical properties of concrete used in bridge deck construction and 2) the early cracking behavior of concrete bridge decks. This research involved the evaluation of four newly constructed bridge decks through a series of laboratory and field tests. At each location, one deck was constructed using a conventional concrete mixture without TSMR, and one was constructed using the same conventional concrete mixture with an addition of 40 lb of TSMR per cubic yard of concrete. Regarding laboratory testing, the conventional …

Developing A Cost Of Delay (Cod) Framework For The Dod & Analyzing The Current State Of Air Force Agile Cost Estimation, James Goljan

Theses and Dissertations

The study has two research objectives. The first research objective develops a proof of concept for a Cost of Delay (CoD) framework to evaluate the Air Forces Kessel Run Software Factory. CoD provides a means to justify and prioritize competing interests regarding budgetary, manpower, and overall strategic decisions. DoD organizations can employ a cost minimization framework to conduct CoD Analysis. The results demonstrate Software Factories eschew trends in the literature towards more complicated cost models that incorporate machine learning with Data-Based techniques in lieu of simpler models that utilize Engineering Build-up Capacity Based techniques.

Enhancement Of Electrospun Nanofiber Properties Via Automated Track Post-Draw Processing, David Anthony Brennan

Theses and Dissertations

Electrospinning is an alternative manufacturing method, capable of producing fibers with nanoscale diameters from a wide range of different polymers in a process which is relatively simple and inexpensive in comparison to other forms of nanofiber production. This has made electrospinning the subject a great deal of research as a method of producing nanofibers for various high-performance applications. However, electrospun nanofiber tensile strength is weak in comparison to conventional fibers of the same material, preventing widespread use and marketization. This disparity in mechanical strength is attributed to poor polymer chain alignment in individual fibers, caused by the absence of a …

Kontrollimi I Cilësisë Ne Vendin E Ndertimit-Punishte Gjatë Zbatimit Të Strukturave Betonarme, Florim H. Bytyqi

Theses and Dissertations

Në këtë temë do të flasim për Cilësin e betonit dhe vetitë e betonit të njomë dhe të ngurtësuar, në veçanti për betonin, komponentët e betonit, përparësitë dhe mangësit, vetitë e tij, si dhe për llojet e betonit, poashtu edhe për rezistencën në shtypje. Duke ditur që betoni është njëri ndër materialet më të përdorura në ndërtimin e strukturave, të cilat përditë e më tepër po bëhen objekt i arritjeve shkencore në inxhinierinë e ndërtimit si në aspektin e lartësisë (etazhitetit), e po ashtu edhe aplikimin e betoneve “të reja” speciale. Fabrikave per prodhimie betonit si dhe mjetet e transportit …

Auditimi I Elementeve Të Sigurisë Rrugore Në Autostradën “Arbën Xhaferi”, Lekë Krasniqi

Theses and Dissertations

Ky hulumtim ka të bëjë me auditimin e sigurisë së elementeve të rrugës pas përfundimit të punimeve ndërtimore të Autostradës “Arbën Xhaferi”, ndërtimi i së cilës ka nisur në vitin 2015, me gjatësi 65km nga kryeqyteti i Republikës së Kosovës - Prishtina në drejtim të kryeqytetit të Maqedonisë Veriore - Shkupit, inaugurimi i së cilës është bërë në muajin maj të vitit 2019.

Teza e masterit përshkruan konceptin e Auditimit të elementeve të sigurisë rrugore në autostradën “Arbën Xhaferi” i cili është bërë para se të bëhet hapja, në mënyrë që të bëhet auditimi i të gjitha elementeve të sigurisë …

Materialet Ndërtimore Ndikimi I Lagështisë Së Drurit Në Vetitë Fiziko-Mekanike, Armend Konjush

Theses and Dissertations

Punimi i realizuar bazohet në lëndën: Konstruksionet e Drurit. Kjo përmbledhje ofron një pamje të përditësuar të njohurive aktuale në lidhje me Drurin si material ndërtimorë, mekanizmat e hidratimit, përfshirë origjinën e periudhës së reaksionit të ngadaltë në vetitë fiziko mekanike, natyra e periudhës së nxitimit, roli i vetive fiziko mekanike në Drurin si meterial ndertimi po ashtu edhe tharja e cila konsiderohet nje nder proceset kryesore.

Qëllimi i kësaj teme është të bëj hulumtim rreth procesit të Drurit duke ju nenshtruar vetive fiziko-mekanike . Shtjellimin dhe ndarjen e llojeve të ndryshme të Drunjëve.

Po ashtu do te shtjellohen analiza …

Meta-Heuristic Optimization Methods For Quaternion-Valued Neural Networks, Jeremiah P. Bill

Theses and Dissertations

In recent years, real-valued neural networks have demonstrated promising, and often striking, results across a broad range of domains. This has driven a surge of applications utilizing high-dimensional datasets. While many techniques exist to alleviate issues of high-dimensionality, they all induce a cost in terms of network size or computational runtime. This work examines the use of quaternions, a form of hypercomplex numbers, in neural networks. The constructed networks demonstrate the ability of quaternions to encode high-dimensional data in an efficient neural network structure, showing that hypercomplex neural networks reduce the number of total trainable parameters compared to their real-valued …

Evaluating The Impact Of Culture On Customer Satisfaction For Fms Projects, Yaquari A. Adams Ii

Theses and Dissertations

The cost, time, and quality pillars of the iron triangle in project management are often considered the most important factors for managers to consider when striving to achieve project success. However, recent literature suggests customer satisfaction and end-user benefit are the most important elements to prioritize during project development. This research analyzes the Air Force Security Assistance Center Construction Division and Foreign Military Sales (FMS) joint construction operations in relation to two Project Management Body of Knowledge (PMBOK) knowledge areas, project stakeholder management and project risk management. Project stakeholder management is addressed by identifying the relationship between cultural competency and …

Exploring The Limits Of Strategic Thought: Evaluating How Different Communication Modalities Affect The Nature Of Strategic Decision-Making Using Cognitive Hierarchy, Stephen D. Donnel

Theses and Dissertations

This research examines and quantifies the degree to which both information communication modality and the situational complexity affect individuals' ability to process the provided information and determine an effective strategy. Human subject testing herein consists of benign benevolent intervention involving the presentation of a series of strategic situations. For each situation, a participant attempts to identify their best response for a two-player, normal-form game with complete information. In each such game, players seek to maximize their own utility while considering their own actions, their opponent's actions, and each player's respective preferences over outcomes resulting from the possible combinations of actions. …