Engineering Commons^™

A Hybrid Method Of Performing Electric Power System Fault Ride-Through Evaluations On Medium Voltage Multi-Megawatt Devices, John Fox

All Dissertations

This dissertation explores the design and analysis of a Hybrid Method of performing electrical power system fault ride-through evaluations on multi-megawatt, medium voltage power conversion equipment. Fault ride-through evaluations on such equipment are needed in order to verify and validate full scale designs prior to being implemented in the field. Ultimately, these evaluations will help in reducing the deployment risks associated with bringing new technologies into the marketplace. This is especially true for renewable energy and utility scale energy storage systems, where a significant amount of attention in recent years has focused on their ever increasing role in power system …

Engineering Beta-Cell Spheroids For Type 1 Diabetes Treatment, Xiaoyan Liu

All Dissertations

Diabetes mellitus, the third most common disease in the world, is a chronic metabolic disorder caused by a failure of insulin production and/or an inability to respond to insulin. Specifically, type 1 diabetes is a disorder characterized by targeted autoimmune-directed destruction of a patient's beta-cell population within the pancreatic islets of Langerhans. The current primary treatment for type 1 diabetes is daily multiple insulin injections. However, this treatment cannot provide sustained physiological release, and the insulin amount is not finely tuned to glycemia. Pancreatic transplants or islet transplants would be the preferred treatment method but the lack of donor tissue …

Identification Of Novel Genes Regulating Elastic Fiber Formation Through Expression Profiling Analysis Of Elastogenic Models, Erin Sproul

All Dissertations

Background: Particularly important to the mechanical performance of native arterial blood vessels is elastin, an extracellular matrix (ECM) protein deposited by VSMCs in the form of elastic fibers, arranged in concentric lamellae in the media of the vessel wall. In addition to serving as major structural elements of arterial walls, providing extensibility and elastic recoil, elastic fibers also influence vascular cell behaviors. For these reasons tissue engineers are attempting to exploit elastic fiber biology to enhance vascular graft design and patency. Therefore, developing a greater understanding of the molecular mechanisms of elastogenesis may offer opportunities to control elastogenesis in tissue …

Assessment Of The Human Factors Analysis And Classification System (Hfacs): Intra-Rater And Inter-Rater Reliability, Awatef Ergai

All Dissertations

Human error has been identified as the primary contributing cause for up to 80% of the accidents in complex, high risk systems such as aviation, oil and gas, mining and healthcare. Many models have been proposed to analyze these incidents and identify their causes, focusing on the human factor. One such safety model is the Human Factors Analysis and Classification System (HFACS), a comprehensive accident investigation and analysis tool which focuses not only on the act of the individual preceding the accident but on other contributing factors in the system as well. Since its development, HFACS has received substantial research …

Exploring Multiple Levels Of Performance Modeling For Heterogeneous Systems, Venkittaraman Vivek Pallipuram Krishnamani

All Dissertations

The current trend in High-Performance Computing (HPC) is to extract concurrency from clusters that include heterogeneous resources such as General Purpose Graphical Processing Units (GPGPUs) and Field Programmable Gate Array (FPGAs). Although these heterogeneous systems can provide substantial performance for massively parallel applications, much of the available computing resources are often under-utilized due to inefficient application mapping, load balancing, and tuning. While several performance prediction models exist to efficiently tune applications, they often require significant computing architecture knowledge for reliable prediction. In addition, they do not address multiple levels of design space abstraction and it is often difficult to choose …

Effect Of Graphitic Carbon Nanomodifiers On The Electromagnetic Shielding Effectiveness Of Linear Low Density Polyethylene Nanocomposites, Byron Villacorta Hernandez

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Conductive polymer composites have become alternative materials for providing electromagnetic and electrostatic shielding where metals are not suitable. In this study, the effect of crystallinity, morphology, concentration and orientation of carbon nanomodifiers on shielding provided by their polyethylene-based composites has been investigated relative to their transport properties.

First, the electrical properties and EM SE of composites consisting of heat-treated carbon nanofibers (Pyrograf^® -III PR-19 CNF) in a linear low density polyethylene (LLDPE) matrix were assessed. Heat treatment (HT) of CNF at 2500°C significantly improved their graphitic crystallinity and intrinsic transport properties, thereby increasing the EM SE of the nanocomposites. …

Encapsulated And Monolithic Resonant Structures For Laser Applications, Aaron Pung

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Typically, the composition of a laser system includes a gain medium, a pump illumination source, and an external feedback cavity. This cavity consists of a highly reflective mirror and an outcoupler component. The geometry of the outcoupler can be engineered to tailor the reflected or transmitted beam's spatial and spectral distribution. Functionally, the transmitted beam profile is dependent on the laser application. Broadband reflection profiles can be obtained by utilizing a distributed Bragg reflector (DBR). A DBR device consists of multiple layers of alternating materials. Constructive interference of the reflected light off each interface between different materials produces the spectrally …

Predicting Surgical Flow Disruption Recovery In Cardiothoracic Operating Rooms, Gary Palmer Ii

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Disruptions are common occurrences in a variety of healthcare settings and early research has shown that they are likely contributors to medical errors. For this reason, healthcare researchers have focused on studying and understanding the nature of Surgical Flow Disruptions (SFDs) to increase patient safety and quality of care within the operating room (OR). Many researchers have used simplistic taxonomies to collect and categorize the types of SFD that occur within the OR. Others have gone further to study SFD recovery and have link unrecovered and recovered SFD to minor and major adverse events experienced by patients. This dissertation, focused …

Adaptive Transmission Protocols For Wireless Communication Systems With Fountain Coding, Jason Ellis

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We present low-complexity adaptive protocols for both unicast and multicast transmission in wireless communication systems that employ higher layer fountain codes. Our adaptive protocols respond to variations in channel conditions by adapting the modulation and channel coding of transmitted packets, and they provide efficient communication over wireless channels that experience fading, shadowing, and other time-varying propagation losses. The operation of our protocols is governed by simple receiver statistics that can be obtained during the demodulation of received packets. We present three adaptive protocols for fountain-coded unicast transmission, and compare the throughput performance of our protocols with that of fixed-rate systems, …

Design And Synthesis Of Polymer - Magnetic Nanoparticle Composites For Use In Biomedical Applications, Roland Stone

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The future of diagnostics and therapeutic drugs in biomedicine is nanoparticles. These nanoparticles come in many different shapes, sizes, and combination of materials. Magnetic nanoparticles have been studied for many years for use in biomedicine, not only for their high surface area, but also because of its unique magnetic properties. They can magnetically interact with their environment, be guided to a specific location, and manipulated to release energy in the form of heat. To ensure that these magnetic nanoparticles survive in the circulatory system, they must be modified with materials to make them colloidally stable in water and shield them …

Hybrid Low-Order Modeling For Conceptual Vehicle Design, Robert Mau

All Dissertations

Design freedom, and particularly the freedom to incorporate innovative designs and strategies, is greatest at the very beginning of vehicle conceptual design. Conversely, this is when the least knowledge of the product exists. As product content decisions are made the level of freedom in the design decreases and the design becomes "locked in." The majority of vehicle lifecycle cost is also set by the end of vehicle conceptual design. This makes it critical to make well-informed and validated decisions in the concept design phase to avoid expensive iterations and redesign in the detailed design phase. Parametric vehicle modeling permits rapid …

Understanding The Role Of Requirements In Engineering Design By Novices, Shraddha Joshi

All Dissertations

Requirements play a critical role in the design process. The broader impact of this research is to develop a systematic understanding of the current use of requirements with an ultimate goal to develop guidelines and recommendations for more effective use of requirements throughout the design process. Thus, this research begins to answer the question about what is the role of requirements in design process and, specifically, its role in idea generation? The answer to this question is explored in three phases. The first phase is to understand how requirements are currently taught to students. To that end, two surveys were …

Primary Resonance Behavior Of Expanded Polymer Cushion Material Under Low-Intensity Harmonic Excitations, Gregory Batt

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The demand to lower costs and reduce the amount of packaging materials utilized in a packaged-product system has placed increased importance on the development of tools to model the behavior of packaging systems. In this dissertation, the free and forced vibration response of a nonlinear, distributed-parameter model of a viscoelastic rod with an applied tip-mass is used to investigate the response of expanded polymer cushion materials to low-intensity harmonic excitations. The rod and tip-mass represent an idealized packaged product system. A nonlinear model is developed from constitutive relations. A classical Maxwell-Weichert model, represented via a Prony series, is used to …

Seismic Site Coefficient Model And Improved Design Response Spectra Based On Conditions In South Carolina, Shimelies Aboye

All Dissertations

A new seismic site coefficient model is developed from the results of over 60,000 total stress, one-dimensional equivalent ground response simulations assuming conditions in South Carolina. Computed site coefficients ( F ) are plotted versus average shear wave velocity in the top 30 m (V_S30 ) and grouped by location, spectral acceleration (S_outcrop ) and spectral period. Locations considered in the Coastal Plain include Aiken, Charleston, Columbia, Florence, Lake Marion, Myrtle Beach, and the South Carolina side of Savannah. Locations considered in the Piedmont include Columbia, Greenville, Greenwood, and Rock Hill. In all the plots of …

Nonlinear Energy Harvesting Under White Noise, Qifan He

All Theses

While purposeful introduction of stiffness nonlinearities into the dynamics of energy harvesters is aimed at enhancing performance under non-stationary and random excitations, most of the conclusions reported in the current literature are based on the steady-state response which assumes a harmonic fixed-frequency excitation. As a result, we still do not have a clear understanding of how the nature of the excitation influences the output power, or what role stiffness nonlinearities play in the transduction of energy harvesters under random excitations. To fill this gap in the current knowledge, this thesis investigates the response of nonlinear mono- and bi-stable energy harvesters …

Averting Hiv Infections In New York City: A Modeling Approach Estimating The Future Impact Of Additional Behavioral And Biomedical Hiv Prevention Strategies, Jason Kessler, Julie E. Myers, Kimberly A. Nucifora, Nana Mensah, Alexis Kowalski, Monica Sweeney, Christopher Toohey, Amin Khademi, Colin Shepard, Blayne Cutler, R. Scott Braithwaite

Publications

Background: New York City (NYC) remains an epicenter of the HIV epidemic in the United States. Given the variety of evidence-based HIV prevention strategies available and the significant resources required to implement each of them, comparative studies are needed to identify how to maximize the number of HIV cases prevented most economically.

Methods: A new model of HIV disease transmission was developed integrating information from a previously validated micro-simulation HIV disease progression model. Specification and parameterization of the model and its inputs, including the intervention portfolio, intervention effects and costs were conducted through a collaborative process between the academic modeling …

Design Optimization Of Geometrical Parameters And Material Properties Of Vibrating Bimorph Cantilever Beams With Solid And Honeycomb Substrates For Maximum Energy Harvested, Jasmin Adeshara

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The objective of this thesis is to maximize the energy harvested from a vibrating bimorph cantilever beam by optimizing the geometrical parameters and the material properties of the piezoelectric beam. A three-dimensional finite element (FEA) model is developed to design a vibrating bimorph cantilever beam for energy harvesting. The reference piezoelectric material used in the design is Lead Zirconate Titanate (PZT-5H) and the substrate sandwiched between the two piezoelectric plates is brass. Three types of models are analyzed and compared in this work by modifying the brass substrate geometry- a solid homogenous substrate, a regular honeycomb substrate and an auxetic …

Moving Domain Computational Fluid Dynamics To Interface With An Embryonic Model Of Cardiac Morphogenesis, Juhyun Lee, Mahdi Esmaily Moghadam, Ethan Kung, Hung Cao, Tyler Beebe, Yury Miller, Beth L. Roman, Ching-Ling Lien, Neil C. Chi, Alison L. Marsden, Tzung K. Hsiai

Publications

Peristaltic contraction of the embryonic heart tube produces time- and spatial-varying wall shear stress (WSS) and pressure gradients (∇P) across the atrioventricular (AV) canal. Zebrafish (Danio rerio) are a genetically tractable system to investigate cardiac morphogenesis. The use of Tg(fli1a:EGFP)y1 transgenic embryos allowed for delineation and two-dimensional reconstruction of the endocardium. This time-varying wall motion was then prescribed in a two-dimensional moving domain computational fluid dynamics (CFD) model, providing new insights into spatial and temporal variations in WSS and ∇P during cardiac development. The CFD simulations were validated with particle image …

Experimental Development And Analysis Of A Novel Setup For Insulated Dielectrophoresis, Johnie Hodge

All Theses

Dielectrophoresis has long been studied and utilized for the manipulation of microscale particles in solution. This phenomenon is due to the induced polarization of dielectric particles subjected to an electric field. When the field is also inhomogeneous in terms of the distribution of its strength through space, the polarized particles move and come to rest in certain areas due to the relationship between their and the solvent's relative permittivities. If the electric field is homogenous, such as within a parallel plate capacitor, the particles are polarized according to their permittivity and the field's frequency, but they will not move.
These …

Renovation Of Ammonia Contaminated Produced Water Using Constructed Wetlands, Donald Beebe

All Dissertations

Pilot-scale wetland treatment systems were designed and constructed to evaluate renovation of simulated oilfield produced water contaminated with ammonia (20 mg/L ammonia-N). A process-based pilot-scale constructed wetland was designed to meet specific biogeochemical conditions for conversion of ammonia to nitrogen gas through microbial nitrification and denitrification. The process-based constructed wetland treated the simulated produced water to meet stringent discharge requirements (less than 1.2 mg/L ammonia-N). Clinoptilolite, a zeolite mineral, was evaluated for use in constructed wetlands to increase ammonia sorption and nitrification activity. Clinoptilolite increased wetland ammonia sorption capacity and served as a microbial carrier for nitrifying bacteria when ranges …

Biological Production Of Succinic Acid Using A Cull Peach Medium, Janani Krishnakumar

All Theses

Biological production of succinic acid from a cull peach based medium was studied using Escherichia coli AFP 184 in a dual-phase batch process including an aerobic growth phase and an anaerobic production phase. Experiments were performed to study the effects of corn steep liquor supplement and exogenous hydrogen supply. About one half of the sucrose in the medium was converted to fermentable sugars glucose and fructose during sterilization. The remaining sucrose was hydrolyzed with invertase. The viscosity of the medium was reduced from 350 cP to 50 cP to allow efficient oxygen transfer by a commercial enzyme product. In the …

Topology Optimization Using A Level Set Penalization With Constrained Topology Features, Luis Fernandez

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Topology optimization techniques have been applied to structural design problems in order to determine the best material distribution in a given domain. The topology optimization problem is ill-posed because optimal designs tend to have infinite number of holes. In order to regularize this problem, a geometrical constraint, for instance the perimeter of the design (i.e., the measure of the boundary of the solid region, length in 2D problems or the surface area in 3D problems) is usually imposed. In this thesis, a novel methodology to solve the topology optimization problem with a constraint on the number of holes is proposed. …

Thermo-Mechanical Effects Of Thermal Cycled Copper Through Silicon Vias, James Marro

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The semiconductor industry is currently facing transistor scaling issues due to fabrication thresholds and quantum effects. In this 'More-Than-Moore' era, the industry is developing new ways to increase device performance, such as stacking chips for three-dimensional integrated circuits (3D-IC). The 3D-IC's superior performance over their 2D counterparts can be attributed to the use of vertical interconnects, or through silicon vias (TSV). These interconnects are much shorter, reducing signal delay. However TSVs are susceptible to various thermo-mechanical reliability concerns. Heating during fabrication and use, in conjunction with coefficient of thermal expansion mismatch between the copper TSVs and silicon substrate, create harmful …

Computational Representation Of Linguistic Semantics For Requirement Analysis In Engineering Design, Alex Lash

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The objective of this research is to use computational linguistics to identify semantic implicit relationships between text-based relationships. Specifically, natural language processing is used to implement linguistic semantics in requirement analyzers. Linguistic semantics is defined as the meaning of words beyond their string form, part of speech, and syntactic function. Many existing design tools use part of speech tagging and sentence parsing as the foundation of their requirement analysis but ultimately use string algorithms to evaluate requirements. These string algorithms cannot capture the implicit knowledge in requirements. This research compares five methods of requirement analysis. A manual analysis provides the …

Improved Photolithography Scheduling In Semiconductor Manufacturing, Sreenath Chalil Madathil

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Photolithography is typically the bottleneck process in semiconductor manufacturing. In this thesis, we present a model for optimizing photolithography job scheduling in the presence of both individual and cluster tools. The combination of individual and cluster tools that process various layers or stages of the semiconductor manufacturing process flow is a special type of flexible flowshop. We seek separately to minimize total weighted completion time and maximize on-time delivery performance. Experimental results suggest that our mathematical- and heuristic-based solution approaches show promise for real world implementation as they can help to improve resource utilization, reduce job completion times, and decrease …

Effectiveness Of Display Trays On Attention And Purchase Of Consumer Products, Erin Snyder

All Theses

Through the collection of qualitative and quantitative data, consumer perception and preference of display trays in the retail environment was examined and evaluated. Purchase decision and eye-tracking data was collected, as well as qualitative survey information, to determine if participants favored packages in a display tray opposed to packages placed directly on store shelving. This preference was measured in terms of time to first fixation, total fixation duration, fixation count as well as final purchasing decision. The experiment analyzed liquid dish soap and canned tomatoes, and was organized as a 2 (products per category) x 1 (display tray per category) …

Flexural Strength Reliability Of Visually Graded Southern Pine Dimensional Lumber, Mengyu Yang

All Theses

The reference design values published in the National Design Specification (NDS) for Wood Construction are derived from full-scale testing of lumber samples performed in the 1980s. This testing program is commonly known as the In-GradeTest Program. Selective annual sample tests of visually graded Southern Pine lumber from 1994 to 2010 revealed an overall decreasing trend in the mechanical properties. Because of this alarming observation, a new round of full-scale In-Grade test of visually graded Southern Pine was initiated in 2010. The new test data indicated significant reductions in certain design values published in the current design code (2005 NDS). …

Improvement Of Onsite Wastewater Treatment By Use Of Electrically Conductive Carbon Cloth, Christopher Weber

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The purpose of this research is primarily focused on carbon oxidation in domestic septic systems. Small-scale septic waste reactors utilizing electrically conductive carbon cloth were assessed for improving carbon oxidation and therefore the overall efficiency of on-site wastewater treatment systems.
A bioelectrochemical system was developed to enhance carbon oxidation in septic systems using electrically conductive carbon cloth as an anode/cathode bridge to transfer electrons from strictly anoxic septic wastewater to an oxic system outside of the septic reactor. This 'septic snorkel' (so named since the system 'breathes' via the carbon cloth extends into an aerobic zone) was designed to lower …

Elaboration And Optimization Of Tellurite-Based Materials For Raman Gain Application, Guillaume Guery

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Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational …

Occlusion-Aware Multi-View Reconstruction Of Articulated Objects For Manipulation, Xiaoxia Huang

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The goal of this research is to develop algorithms using multiple views to automatically recover complete 3D models of articulated objects in unstructured environments and thereby enable a robotic system to facilitate further manipulation of those objects. First, an algorithm called Procrustes-Lo-RANSAC (PLR) is presented. Structure-from-motion techniques are used to capture 3D point cloud models of an articulated object in two different configurations. Procrustes analysis, combined with a locally optimized RANSAC sampling strategy, facilitates a straightforward geometric approach to recovering the joint axes, as well as classifying them automatically as either revolute or prismatic. The algorithm does not require prior …