Engineering Commons^™

Considerations For The Design Optimization Of Floating Offshore Wind Turbine Blades, Evan M. Gaertner

Doctoral Dissertations

Floating offshore wind turbines are an immature technology with relatively high costs and risk associated with deployment. Of the few floating wind turbine prototypes and demonstration projects deployed in real metocean conditions, all have used standard turbines design for onshore or offshore fixed bottom conditions. This neglects the unique unsteady aerodynamics brought on by floating support structure motion. While the floating platform has been designed and optimized for a given rotor, the global system is suboptimal due to the rotor operating in conditions outside of which it was design for. If the potential offered by floating wind turbines is to …

Improving Drivers’ Behaviour When Partial Driving Automation Fails, Yalda Ebadi

Doctoral Dissertations

With the advent of automated vehicle systems, the role of drivers has changed to a more supervisory role. However, it is known that all vehicles with Level 2 (L2) systems have a very specific operational design domain (ODD) and can only function on limited conditions. Hence, it is important for drivers to perceive the situations properly and regain the control from the L2 system when needed. As suggested by past research, designing an informative interface could help drivers in their new supervision and intervention role while driving with L2 vehicles by providing feedback to drivers when hazards or event that …

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey

Doctoral Dissertations

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions. VFSI …

Encapsulation And Stabilization Of Biomacromolecules, Whitney Blocher Blocher Mctigue

Doctoral Dissertations

Recent work in the area of protein encapsulation has turned away from traditional methods of sequestration toward gentler, purely aqueous techniques. Among them, complex coacervation has become a topic of discussion. Complex coacervation is an all-aqueous liquid-liquid phase separation phenomenon dominated by electrostatic interactions and entropic gains. The use of coacervates as protein encapsulants has garnered much attention, but there has been little headway in determining a set of design rules. We considered coacervation between two oppositely-charged polypeptides and a biomacromolecule cargo to investigate the effects of changing aspects of the coacervating polymers and/or various solution parameters. We characterized the …

Theory And Improved Methods For Probing The Cavitation To Fracture Transition, Christopher Barney

Doctoral Dissertations

A material is considered soft when its bulk modulus is significantly greater than its shear modulus. Rubbery polymers are a class of soft materials where resistance to extension is mainly entropic in nature. Polymeric soft solids differ from liquids due to the presence of a percolated network of strong bonds that resist deformation and flow on a given time scale. The incompressible nature, entropically driven elasticity, and molecular scale network structure of soft polymeric solids combine to impart unique mechanical behavior that often results in complex material responses to simple loading situations. An important example of this is cavitation in …

Investigating The Role Of Iron In The Photogranulation Phenomenon, Abeera Ayaz Ansari

Doctoral Dissertations

Oxygenic photogranules (OPGs) are dense spherical microbial aggregates that are used for self-aerating wastewater treatment. Filamentous cyanobacteria are key granulating species, providing structural backbone and integrity in OPGs. Currently, the mechanisms for selecting filamentous cyanobacteria and their ability to form spherical OPGs are not well understood. Literature shows that iron (Fe) availability plays a significant role in the cyanobacterial growth and colony formation. Moreover, Fe availability is known to be dependent upon light, which is an essential growth substrate for the phototrophs. This research has investigated the role of Fe in the photogranulation phenomenon and the impact of light intensity …

Controlled Membrane Remodeling By Nanospheres And Nanorods: Experiments Targeting The Design Principles For Membrane-Based Materials, Sarah Zuraw-Weston

Doctoral Dissertations

In this thesis we explore two experimental systems probing the interactions of nanoparticles with lipid bilayer membranes. Inspired by the ability of cell membranes to alter their shape in response to bound particles, we report two experimental studies: one of nanospheres the other of long, slender nano-rods binding to lipid bilayer vesicles and altering the membrane shape. Our work illuminates the role of particle geometry, particle concentration, adhesion strength and membrane tension in how membrane morphology is determined. We combine giant unilamellar vesicles with oppositely charged nanoparticles, carefully tuning adhesion strength, membrane tension and particle concentration. In the case of …

System Design And Implementation For Hybrid Network Function Virtualization, Xuzhi Zhang

Doctoral Dissertations

With the application of virtualization technology in computer networks, many new research areas and techniques have been explored, such as network function virtualization (NFV). A significant benefit of virtualization is that it reduces the cost of a network system and increases its flexibility. Due to the increasing complexity of the network environment and constantly improving network scale and bandwidth, it is imperative to aim for higher performance, extensibility, and flexibility in the future network systems. In this dissertation, hybrid NFV platforms applying virtualization technology are proposed. We further explore the techniques used to improve the performance, scalability and resilience of …

Performance Evaluation Of Classical And Quantum Communication Systems, Gayane Vardoyan

Doctoral Dissertations

The Transmission Control Protocol (TCP) is a robust and reliable method used to transport data across a network. Many variants of TCP exist, e.g., Scalable TCP, CUBIC, and H-TCP. While some of them have been studied from empirical and theoretical perspectives, others have been less amenable to a thorough mathematical analysis. Moreover, some of the more popular variants had not been analyzed in the context of the high-speed environments for which they were designed. To address this issue, we develop a generalized modeling technique for TCP congestion control under the assumption of high bandwidth-delay product. In a separate contribution, we …

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …

Engineering Mesothelin-Binding Proteins As Targeted Cancer Diagnostics And Therapeutics, Allison Rita Sirois

Doctoral Dissertations

Cancer is a significant global health concern; and traditional therapies, including chemotherapeutics, are often simultaneously toxic yet ineffective. There is a critical need to develop targeted cancer therapeutics which specifically inhibit molecules or molecular pathways essential for tumor growth and maintenance. Furthermore, a targeted therapy is only effective when a patient's tumor expresses the molecular target; therefore, companion diagnostics, including molecular imaging agents, are a necessary counterpart of targeted therapies. Mesothelin (MSLN) is a cell surface protein overexpressed in numerous cancers, including triple-negative breast, pancreatic, ovarian, liver, and lung, with limited expression in normal tissues. Aberrant MSLN expression promotes tumor …

Multiscale Simulations Of Polymeric Electrolytes For Electrochemical Devices, Xubo Luo

Doctoral Dissertations

Polymeric electrolytes are polymers containing the ionic moieties used for ion conduction in electrochemical devices. The strategic design of these materials requires the in-depth understanding of the relation between the molecular structure and the properties. This dissertation reports on computational simulations for two types of materials: hydrated anion exchange membranes (AEMs) for fuel cells and the polymerized ionic liquids (PolyILs). Various chemical structures were covered for systematic investigations.

For AEMs, the ion conducting channels or domains are essential for the efficient ion transport, and thus the morphology of the hydrated membrane is worthy of study. Dissipative particle dynamics simulations were …

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH₄ that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH₄ in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO₂, which energetically takes place of the …

Dynamic Neuromechanical Sets For Locomotion, Aravind Sundararajan

Doctoral Dissertations

Most biological systems employ multiple redundant actuators, which is a complicated problem of controls and analysis. Unless assumptions about how the brain and body work together, and assumptions about how the body prioritizes tasks are applied, it is not possible to find the actuator controls. The purpose of this research is to develop computational tools for the analysis of arbitrary musculoskeletal models that employ redundant actuators. Instead of relying primarily on optimization frameworks and numerical methods or task prioritization schemes used typically in biomechanics to find a singular solution for actuator controls, tools for feasible sets analysis are instead developed …

A Method For Developing And Testing Nuclear Reactor Systems With Space Applications And Improving Performance Of Heat Pipe Reactor Systems, David Duff Dixon

Doctoral Dissertations

The concept of using nuclear reactor technology in propulsion systems is nearly as old as nuclear reactors themselves. Numerous publications, many at very primitive conceptual levels, suggested nuclear propulsion in the 1940s. Since then, numerous attempts have been made to build and fly a nuclear rocket, yet there have been no such systems advanced to the point of a system test in more than half a century.

This dissertation presents an approach to reactor system development, a testing approach developed by the author that resulted in the operation of the world’s first heat pipe reactor system, and the world’s first …

Distributed Sensor Network Data Fusion For Nuclear Security Applications, Ian Robert Stewart

Doctoral Dissertations

Detecting, locating, and interdicting radiological materials out of regulatory control or that pose a threat to the general public remains a high national security priority. Conventional methods employed a radiation detection system to detect radiological materials and alert the appropriate authorities for interdiction procedures. More recently, the concept of operations has focused to deploying multiple radiation detection systems to detect and track radiological materials, providing more detail to aid end-users during the interdiction process. The research proposed in this document utilizes data from a distributed sensor network to detect and track radiation anomalies through a network. The primary original contributions …

Development Of (Α,N) Signatures As A Viable Safeguards Measurement For Electrochemical Reprocessing, Stephen N. Gilliam

Doctoral Dissertations

As interest grows in electrochemistry for material separations and reprocessing of nuclear fuel research and development into the safegaurdability of such a system is needed. Plutonium quantification via (α,n) neutrons within the electrorefiner vessel is examined as a potential alternative means to the traditional spontaneous fission tracking. An MCNP model of an Epi-Thermal Neutron Multiplicity counter was used in the calculation of curium from a sample of curium, plutonium, and eutectic salt. This and the multiplicity variable alpha, the ratio between (α,n) neutron and spontaneous fission, were then used to define the plutonium mass as it related to its (α,n) …

Application Of Crowdsourced Data In Transportation Operations And Safety, Nima Hoseinzadeh

Doctoral Dissertations

Crowdsourcing refers to the acquisition of data from users who contribute their information via smartphone, social media, or the internet. In transportation systems, crowdsourcing turns users into real-time sensors, providing data on traffic speed, travel time, mile traveled, incidents, roadway conditions, weather severity, irregularities in traffic patterns, and hazards. These data can be collected actively or passively in quantitative or qualitative forms. With the emergence of smartphones and navigation apps, crowdsourced data are gaining increased attention in transportation. Crowdsourced data have advantages over traditional fixed-location sensors and camera monitoring: low implementation costs, extended geographic coverage, high resolution, real-time application, increased …

Design And Implementation Of An Isfet Sensor With Integration Of An On-Chip Processor, Shaghayegh Aslanzadeh

Doctoral Dissertations

Portable sensors are used in many applications. Among them, pH sensors are suitable for quantifying and identifying various analytes in real-time and doing so non-invasively. The analytes may have environmental impact such as in water quality monitoring. The analytes may also have biological impact such as monitoring cell culture or remote patient health assessment. CMOS based sensors are compact and enable low power consumption suitable for these portable applications.

This work reports on the development of a portable CMOS based pH sensor. The contributions of this dissertation are as follows. First, a differential pH sensor, with two different sized electrodes …

Multi-Layer Utilization Of Beamforming In Millimeter Wave Mimo Systems, Mustafa S. Aljumaily

Doctoral Dissertations

mmWave frequencies ranging between (30-300GHz) have been considered the perfect solution to the scarcity of bandwidth in the traditional sub-6GHz band and to the ever increasing demand of many emerging applications in today's era. 5G and beyond standards are all considering the mmWave as an essential part of there networks. Beamforming is one of the most important enabling technologies for the mmWave to compensate for the huge propagation lose of these frequencies compared to the sub-6GHz frequencies and to ensure better spatial and spectral utilization of the mmWave channel space. In this work, we tried to develop different techniques to …

Characterization Of A Digital Holography Diagnostic For In Situ Erosion Measurement Of Plasma-Facing Components In Fusion Devices, Cary Dean Smith

Doctoral Dissertations

Fusion energy devices, particularly tokamaks, face the challenge of interior surface damage occurring over time from the heat flux of the high-energy plasma they generate. The ability to monitor the rate of surface modification is therefore imperative, but to date no proven technique exists for real-time erosion measurement of planar regions of interest on plasma-facing components in fusion devices. In order to fill this diagnostic gap, a digital holography system has been established at ORNL [Oak Ridge National Laboratory] for the purpose of measuring the erosion effects of plasma-material interaction in situ.

The diagnostic has been designed with the …

3d Study Of Gas Hydrate Formation And Dissociation In Porous Media And Dem Modeling Of Granular Materials, Zaher Jarrar

Doctoral Dissertations

Natural methane gas hydrates availability and ongoing rise in demand for energy, motivated researchers to consider gas hydrates as a potential energy source. Production of methane from hydrate-bearing sediments requires hydrate dissociation for releasing mobile methane gas in sediments prior to gas production operations. Fines may migrate through or clog the pore space of sandy sediments depending on the geometry and topology of the pore space. This dissertation employs unique in situ experiments and techniques to gain a comprehensive understanding of the associated physical processes (such as fines migration, clogging and gas driven fracture) and validation of hydrate dissociation models’ …

Approaches To Studying Bacterial Biofilms In The Bioeconomy With Nanofabrication Techniques And Engineered Platforms., Michelle Caroline Halsted

Doctoral Dissertations

Studies that estimate more than 90% of bacteria subsist in a biofilm state to survive environmental stressors. These biofilms persist on man-made and natural surfaces, and examples of the rich biofilm diversity extends from the roots of bioenergy crops to electroactive biofilms in bioelectrochemical reactors. Efforts to optimize microbial systems in the bioeconomy will benefit from an improved fundamental understanding of bacterial biofilms. An understanding of these microbial systems shows promise to increase crop yields with precision agriculture (e.g. biosynthetic fertilizer, microbial pesticides, and soil remediation) and increase commodity production yields in bioreactors. Yet conventional laboratory methods investigate these micron-scale …

Multiphysics Assessment Of Accident Tolerant Fuel, Cladding, And Core Structural Material Concepts, Jacob Preston Gorton

Doctoral Dissertations

The severe accident at the Fukushima-Daiichi nuclear power plant in 2011 ignited a global research and development effort to replace traditionally-used materials in Light Water Reactors (LWRs) with Accident Tolerant Fuel (ATF) materials. These materials are intended to extend the coping time of nuclear power plants during severe accident scenarios, but must undergo thorough safety and performance evaluations before being implemented. Four ATF concepts are analyzed in this dissertation using state-of-the-art computer modeling tools: (1) iron-chromium-aluminum (FeCrAl) fuel rod cladding, (2) silicon carbide (SiC) fiber-reinforced, SiC matrix composite (SiC/SiC) boiling water reactor (BWR) channel boxes, (3) mixed thorium mononitride (ThN) …

Automated Intelligent Cueing Device To Improve Ambient Gait Behaviors For Patients With Parkinson's Disease, Nader Naghavi

Doctoral Dissertations

Freezing of gait (FoG) is a common motor dysfunction in individuals with Parkinson’s disease (PD). FoG impairs walking and is associated with increased fall risk. Although pharmacological treatments have shown promise during ON-medication periods, FoG remains difficult to treat during medication OFF state and in advanced stages of the disease. External cueing therapy in the forms of visual, auditory, and vibrotactile, has been effective in treating gait deviations. Intelligent (or on-demand) cueing devices are novel systems that analyze gait patterns in real-time and activate cues only at moments when specific gait alterations are detected. In this study we developed methods …

Engineered Carbon Materials With Nano-Graphitic Domains Derived From Lignin, Valerie Garcia Negron

Doctoral Dissertations

This work focuses on establishing a comprehensive understanding of lignin-derived materials as a function of carbonization with the goal of identifying processing-structure-property-performance relationships. A combination of modeling, statistical, and empirical materials characterization techniques are applied to lignin materials varying in feedstock source, extraction method, and processing conditions. The first part of this study evaluates the structure of carbon composite materials, possessing both crystalline and amorphous domains, using scattering techniques. One approach performs atomistic simulations of a proposed structure, from which the analogous scattering pattern can be obtained for validation. An alternative approach based on a hierarchical decomposition of the radial …

Mechanics Of The Solid-State Bonding Under Severe Thermomechanical Processes, Xue Wang

Doctoral Dissertations

Friction stir welding (FSW) has found increased applications in automotive and aerospace industries due to its advantages of solid-state bonding, no fusion and melting, and versatility in various working conditions and material combinations. The extent and quality of the solid-state bonding between workpieces in FSW is the ultimate outcome of their industrial applications. However, the relationship among processing parameters, material properties, and bonding extent and fidelity remains largely empirical, primarily because of the lack of the mechanistic understanding of (1) tool-workpiece frictional behavior, and (2) bonding formation and evolution.

In this dissertation, to study the underlying mechanism of tool-workpiece frictional …

Supplier Ranking System And Its Effect On The Reliability Of The Supply Chain, Farshad Rabib

Doctoral Dissertations

Today, due to the growing use of social media and an increase in the number of

A HITS with a solution in PageRank (Massimo, 2011) sharing their opinions globally, customers can review products and services in many novel ways. However, since most reviewers lack in-depth technical knowledge, the true picture concerning product quality remains unclear. Furthermore, although product defects may come from the supplier side, making it responsible for repair cost, it is ultimately the manufacturer whose name is damaged when such defects are revealed. In this context, we need to revisit the cost vs. quality equations. Observations of customer …

Rational Design Of Non-Noble Metal Intermetallic Compounds With Tunable Surface And Catalytic Chemistry Via Combined Computational And Experimental Method, Yuanjun Song

Doctoral Dissertations

This study focuses upon understanding and rationally tuning the surface reactivity towards C, H, and O of non-noble metal intermetallic compounds (IMCs) catalysts in olefin production and hydrocarbons reforming reactions. In these reactions, different degrees of surface reactivity towards C, H, and O are required to achieve high activity and selectivity as well as stability. A combined computational and experimental method was performed to build this understanding how to rationally design catalysts. Investigations based on quantum chemical calculations indicate surface reactivity towards C, H, and O is a function of element size of constituent elements as well as bulk and …