Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Browse all Theses and Dissertations

Discipline
Keyword
Publication Year
File Type

Articles 331 - 360 of 1369

Full-Text Articles in Engineering

Growth Of Two-Dimensional Molybdenum Disulfide Via Chemical Vapor Deposition, Zachary Durnell Ganger Jan 2019

Growth Of Two-Dimensional Molybdenum Disulfide Via Chemical Vapor Deposition, Zachary Durnell Ganger

Browse all Theses and Dissertations

Graphene has successfully been a 2D material applied in various fields, but it is not the most appropriate candidate for many electronic devices unless its bandgap structure is tuned through functionalization. Among all other 2D material families, transition metal dichalcogenides (TMDs), represented by molybdenum disulfide (MoS2), are promising and emerging in power electronics due to their large direct bandgap and other electronic properties. 2D MoS2 has been fabricated through different approaches such as mechanical exfoliation, chemical etching, and chemical vapor deposition (CVD). The current major challenge in fabricating 2D MoS2 films is to produce a high-quality large-area monolayer film at …


Design And Manipulation Of A Power-Generating System With High-Temperature Fuel Cells For Hypersonic Applications, Jack Randolph Chalker Jan 2019

Design And Manipulation Of A Power-Generating System With High-Temperature Fuel Cells For Hypersonic Applications, Jack Randolph Chalker

Browse all Theses and Dissertations

Current hypersonic vehicles tend to be incapable of producing onboard power with traditional generators due to their use of supersonic combusting ramjets (scramjets). Because of this, they seek additional energy sources for supporting advanced electronics or other auxiliary power-dependent devices while requiring elaborate thermal management systems to combat temperatures exceeding 700ºC. The incorporation of Solid Oxide Fuel Cell (SOFCs) stacks is an efficient solution, capable of generating large quantities of power through the use of natural fuel sources at high temperatures. Developments in this thesis include the design, construction, and support of a system operating at hypersonic-environment conditions with a …


Unsteady Effects Of A Pulsed Blowing System On An Endwall Vortex, Molly Hope Donovan Jan 2019

Unsteady Effects Of A Pulsed Blowing System On An Endwall Vortex, Molly Hope Donovan

Browse all Theses and Dissertations

The low-pressure turbine is an important component of a gas turbine engine, powering the low-pressure spool which provides the bulk of the thrust in medium- and high-bypass engines. It is also a significant fraction of the engine weight and complexity as it can comprise up to a third of the total engine weight. One way to drastically reduce the weight of the low-pressure turbine is to utilize high lift blades. To advance high-lift technology, the Air Force Research Laboratory (AFRL) designed the L2F blade profile, which was implemented in the linear cascade at AFRL/RQT’s low speed wind tunnel facility. The …


Use Of Virtual Reality Technology In Medical Training And Patient Rehabilitation, Sankalp Mishra Jan 2019

Use Of Virtual Reality Technology In Medical Training And Patient Rehabilitation, Sankalp Mishra

Browse all Theses and Dissertations

Coaching patients to follow the rehabilitation routines correctly and timely after surgery is often a challenge due to the limited medical knowledge of patients and limited availability of clinicians. Similarly, it is also a challenge to train medical professionals with both the technical and communication skills required in their practices. The recent emergence of VR technologies shines the light on improving the current training practices. In this thesis research, I will look at the development and application of VR-based immersive training games for two particular cases: 1. Post hand surgery rehab; and, 2. Training for Social determinants of health (SDOH) …


Retail Facility Layout Considering Shopper Path And Door Placement, Sagarkumar D. Hirpara Jan 2019

Retail Facility Layout Considering Shopper Path And Door Placement, Sagarkumar D. Hirpara

Browse all Theses and Dissertations

The physical design of a retail store is known to influence the attitude and behavior of shoppers, in turn affecting the store’s performance. While literature in retail design has alluded to the impact of changes in department placements on impulse revenue, it has not accounted for the changes in the path of a shopper due to such modifications. Shopper path changes can alter a department’s visibility to the shoppers as they pass by, and such visibility eventually impacts that department’s impulse revenue. To address this gap, we study the retail facility layout problem by accounting for changes in the shopper …


An Investigation On Spur Gear Rolling Contact Fatigue Crack Initiation And Crack Propagation Under Ehl Condition, Vignesh Dharmajan Jan 2019

An Investigation On Spur Gear Rolling Contact Fatigue Crack Initiation And Crack Propagation Under Ehl Condition, Vignesh Dharmajan

Browse all Theses and Dissertations

Pitting is a rolling contact fatigue phenomenon commonly observed in mechanical rolling elements, such as gears and bearings. In case of gear contacts, pitting usually takes place in the dedendum region, where both sliding and contact load are high. In this study, a model is developed to predict surface breaking crack formation fatigue lives, including both nucleation and propagation stages, for spur gear contacts operating under mixed elastohydrodynamic lubrication (EHL) condition. The model utilizes a gear load distribution model for tooth contact Analysis. A mixed EHL formulation is implemented to evaluate the surface normal pressure and tangential shear, incorporating the …


Mitochondria-Dependent Cellular Toxicity Of Α-Synuclein Modeled In Yeast, Rajalakshmi Santhanakrishnan Jan 2019

Mitochondria-Dependent Cellular Toxicity Of Α-Synuclein Modeled In Yeast, Rajalakshmi Santhanakrishnan

Browse all Theses and Dissertations

Parkinson’s disease is the second most common neurodegenerative disease. This disease is caused by the degeneration of dopaminergic neurons, leading to debilitating motor symptoms and early mortality. The protein α-synuclein (α-syn), encoded by SNCA, misfolds and forms inclusions in Parkinson’s disease brains. When α-syn is overexpressed in yeast, it causes cellular toxicity and an increased number of aggregates, recapitulating the toxic phenotypes observed in humans and animal models. Yeast models are a powerful tool to perform high-throughput overexpression screening to identify modifiers of α-syn toxicity. α-syn causes mitochondrial dysfunction by inhibiting complex I and inducing mitochondrial fragmentation. Prior screening of …


Multifunctional Oxide Heterostructures For Next-Generation Tunable Rf/Microwave Electronics, Hyung Min Jeon Jan 2019

Multifunctional Oxide Heterostructures For Next-Generation Tunable Rf/Microwave Electronics, Hyung Min Jeon

Browse all Theses and Dissertations

Recent advanced radio frequency (RF) microwave device demands for low power consumption, light weight, compact package, and high performance. To achieve the high performance, applying magnetic materials is becoming indispensable in many of those devices. Thus, the role of magnetism in those devices is important high-quality magnetic materials not only improves the performance of microwave devices but also opens opportunities in developing novel concepts of devices utilizing spin wave excitation, non-reciprocal wave propagation, and the electromagnetic coupling in multiferroic materials. Among all the others, manipulating magnetic properties in multiferroic material started a couple years ago. Multiferroic materials are a group …


Design And Implementation Of Periodic Unsteadiness Generator For Turbine Secondary Flow Studies, Nathan James Fletcher Jan 2019

Design And Implementation Of Periodic Unsteadiness Generator For Turbine Secondary Flow Studies, Nathan James Fletcher

Browse all Theses and Dissertations

A primary source of periodic unsteadiness in low-pressure turbines is the wakes shed from upstream blade rows due to the relative motion between adjacent stators and rotors. These periodic perturbations can affect boundary layer transition, secondary flow, and loss generation. In particular, for high-lift front-loaded blades, the secondary flowfield is characterized by strong three-dimensional vortical structures. It is important to understand how these flow features respond to periodic disturbances. A novel approach was taken to generate periodic unsteadiness which captures some of the physics of turbomachinery wakes. Using stationary pneumatic devices, pulsed jets were used to generate disturbances characterized by …


Scalable Clustering For Immune Repertoire Sequence Analysis, Prem Bhusal Jan 2019

Scalable Clustering For Immune Repertoire Sequence Analysis, Prem Bhusal

Browse all Theses and Dissertations

The development of the next-generation sequencing technology has enabled systems immunology researchers to conduct detailed immune repertoire analysis at the molecule level. Large sequence datasets (e.g., millions of sequences) are being collected to comprehensively understand how the immune system of a patient evolves over different stages of disease development. A recent study has shown that the hierarchical clustering (HC) algorithm gives the best results for B-cell clones analysis - an important type of immune repertoire sequencing (IR-Seq) analysis. However, due to the inherent complexity, the classical hierarchical clustering algorithm does not scale well to large sequence datasets. Surprisingly, no algorithms …


Mechanical Stresses On Nasal Mucosa Using Nose-On-Chip Model, Zachary Edward Brooks Jan 2019

Mechanical Stresses On Nasal Mucosa Using Nose-On-Chip Model, Zachary Edward Brooks

Browse all Theses and Dissertations

The objective of this research was to design and fabricate a nose-on-chip device and bi-directional airflow system that models flow within the nasal cavity to investigate how airflow induced mechanical stresses impact nasal secretion rates and cytoskeletal remodeling. This research hypothesizes that the airflow induced shear stresses on the nasal mucosa will influence mucus production and the cytoskeleton of the cells. The RPMI 2650 cell line was used to model the nasal mucosa. The system was used to replicate the wall shear stresses (WSS) and wall shear forces (WSF) present in the anterior region of the nose. The WSS and …


High Security Cognitive Radio Network Via Instantaneous Channel Information, Kaiyu Huang Jan 2019

High Security Cognitive Radio Network Via Instantaneous Channel Information, Kaiyu Huang

Browse all Theses and Dissertations

The cognitive radio network has been considered one of the most promising communication technologies for next generation wireless communication. One important aspect of cognitive radio network research is the so-called Primary User Authentication. Naturally, the primary user authentication in the cognitive radio network requires strong encryption. For the primary user identification, this dissertation provides a method which hides the user information in the header of the data frames with an underlay waveform. It is important to note that the underlay waveform will not bring redundancy data to the communication system. Using the synchronizing frequency as the underlay waveform carrier also …


Two Player Zero Sum Multi-Stage Game Analysis Using Coevolutionary Algorithm, Sumedh Sopan Nagrale Jan 2019

Two Player Zero Sum Multi-Stage Game Analysis Using Coevolutionary Algorithm, Sumedh Sopan Nagrale

Browse all Theses and Dissertations

A New Two player zero sum multistage simultaneous Game has been developed from a real-life situation of dispute between two individual. Research identifies a multistage game as a multi-objective optimization problem and solves it using Coevolutionary algorithm which converges to a solution from pareto optimal solution. A comparison is done between individual stage behaviour and multistage behaviour. Further, simulations over a range for Crossover rate, Mutation rate and Number of interaction is done to narrow down the range for a range with optimal computation speed. A relationship has been observed which identifies a relationship between population size, number of interactions, …


Accelerating Reverse Engineering Image Processing Using Fpga, Matthew Joshua Harris Jan 2019

Accelerating Reverse Engineering Image Processing Using Fpga, Matthew Joshua Harris

Browse all Theses and Dissertations

In recent decades, field programmable gate arrays (FPGAs) have evolved beyond simple, expensive computational components with minimal computing power to complex, inexpensive computational engines. Today, FPGAs can perform algorithmically complex problems with improved performance compared to sequential CPUs by taking advantage of parallelization. This concept can be readily applied to the computationally dense field of image manipulation and analysis. Processed on a standard CPU, image manipulation suffers with large image sets processed by highly sequential algorithms, but by carefully adhering to data dependencies, parallelized FPGA functions or kernels offer the possibility of significant improvement through threaded CPU functions. This thesis …


Effects Of Lubrication Starvation On Flash Temperature For Thermal Mixed Elastohydrodynamic Gear Contacts, Danielle D. Massé Jan 2019

Effects Of Lubrication Starvation On Flash Temperature For Thermal Mixed Elastohydrodynamic Gear Contacts, Danielle D. Massé

Browse all Theses and Dissertations

Lubrication is provided to the gear trains in automotive and aerospace transmission systems to prevent mechanical contact through the formation of a full lubricant film, which in turn removes heat generated at the gear contact surfaces. When debris blocks the inlet nozzle, the flow of lubricant is restricted and mechanical components experience lubrication starvation. Under starved lubrication the temperatures of the contact surfaces become elevated which can lead to the formation of a weld between them, a catastrophic failure mode called scuffing. For spur gears, the occurrence of scuffing is due to high sliding in the vicinity of the root …


Joint Determination Of Rack Configuration And Shelf Space Allocation To Maximize Retail Impulse Profit, Uttam Karki Jan 2019

Joint Determination Of Rack Configuration And Shelf Space Allocation To Maximize Retail Impulse Profit, Uttam Karki

Browse all Theses and Dissertations

For brick-and-mortar retailers to be successful, it is critical for them to optimally design their rack layout and place products in order to draw attention of shoppers. Literature suggests that racks placed at acute (or obtuse) angles to the main aisle frequented by shoppers can enhance visibility of products compared to racks placed orthogonally (i.e., 90˚). Placing products with high impulse purchase potential in the resulting highly visible locations on the rack can increase shopper impulse purchases. However, placing racks at angles other than 90˚ can increase the required floor space. Additionally, while reducing the height of the racks just …


Rasters Vs Contours For Thin Wall Ultem 9085 Fdm Applications, Vausman Kota Jan 2019

Rasters Vs Contours For Thin Wall Ultem 9085 Fdm Applications, Vausman Kota

Browse all Theses and Dissertations

Currently many components are additively manufactured via fused deposition modeling (FDM). However, FDM results in gaps between passes which produces a poor surface finish and porous material that is difficult to hold pressure. Commercial scale air systems require a pressure to be maintained within thin walled components with minimal post processing and clean up after fabrication. A design of experiments (DOE) was created to identify the optimal raster vs contour ratio for UTLEM 9085 CG fabricated using FDM at different build angles and wall thicknesses. A custom-built pressurized test system was developed, the leak rates were calculated and the surfaces …


10-Bit C2c Dac Design In 65nm Cmos Technology, Jeevani Kommareddy Jan 2019

10-Bit C2c Dac Design In 65nm Cmos Technology, Jeevani Kommareddy

Browse all Theses and Dissertations

Many wired and wireless communication systems require high-speed and high-performance data converters. These data converters act as bridge between digital signal processing blocks and power amplifiers. However, these data converters have been the bottleneck in the communication systems. This thesis presents the design of a 10-bit C2C digital to analog converter (DAC) for high resolution, wide bandwidth and low power consumption applications. The DAC is implemented in CMOS 65nm technology. The SFDR of this C2C DAC is 71.95dB at 500MHz input frequency and consumes 88.14µW of power with ENOB as 11.65 with 1.0GHz sample frequency with 0.31LSB of INL and …


Virtual Reality And Analysis Framework For Studying Different Layout Designs, Madison Glines Jan 2019

Virtual Reality And Analysis Framework For Studying Different Layout Designs, Madison Glines

Browse all Theses and Dissertations

This thesis describes the tools for studying different design prototypes. The goal was to develop effective tools to study these designs using a data-driven approach. “Proof of concept” experiments were conducted, in which participants were allowed to interact with a virtual environment depicting different designs as data pertaining to their virtual location and orientation was recorded for later analysis. The designs included “flat” store racks, as opposed to racks with more varied shapes, as well as “curved” racks. Focus of the design studies was to assist in identifying optimal locations for different product types. The automated data collection mechanisms required …


Securing Modern Cyberspace Using A Multi-Faceted Approach, Yu Li Jan 2019

Securing Modern Cyberspace Using A Multi-Faceted Approach, Yu Li

Browse all Theses and Dissertations

Security has become one of the most significant concerns for our cyberspace. Securing the cyberspace, however, becomes increasingly challenging. This can be attributed to the rapidly growing diversities and complexity of the modern cyberspace. Specifically, it is not any more dominated by connected personal computers (PCs); instead, it is greatly characterized by cyber-physical systems (CPS), embedded systems, dynamic services, and human-computer interactions. Securing modern cyberspace therefore calls for a multi-faceted approach capable of systematically integrating these emerging characteristics. This dissertation presents our novel and significant solutions towards this direction. Specifically, we have devised automated, systematic security solutions to three critical …


Monitoring Cerebral Functional Response Using Scmos-Based High Density Near Infrared Spectroscopic Imaging, Dharminder Singh Langri Jan 2019

Monitoring Cerebral Functional Response Using Scmos-Based High Density Near Infrared Spectroscopic Imaging, Dharminder Singh Langri

Browse all Theses and Dissertations

Neurovascular coupling is an important concept that indicates the direct link between neuronal electrical firing with the vascular hemodynamic changes. Functional Near Infrared Spectroscopy (fNIRS) can measure changes in cerebral vascular parameters of oxy-hemoglobin and deoxyhemoglobin concentrations and thus can provide neuronal activity through neurovascular coupling. Currently many commercial fNIRS devices are available, but they are limited by the number of channels (usually having only 8 detectors), which can limit the sensitivity, contrast, and resolution of imaging. High-density imaging can improve sensitivity, contrast, and resolution by providing many measurements and averaging the signals originating from the target cerebral focus area …


Mixed Signal Detection, Estimation, And Modulation Classification, Yang Qu Jan 2019

Mixed Signal Detection, Estimation, And Modulation Classification, Yang Qu

Browse all Theses and Dissertations

Signal detection, parameter estimation and modulation classification are widely applied to many areas and plays a very important role in civilian and military, such as bio-science, criminal psychology, communication engineering, radar system, electronic warfare and so on. In the civilian field, with the increasing number of wireless electronic devices and higher transmission data rate demand, the problem of spectrum congestion becomes more and more highlighted and urgent. In recent years, wireless industry has shown great interest in Cognitive Radio (CR) and Dynamic Spectrum Access (DSA) network, whose primary function is to use limited frequency bands to transmit own signals without …


Islands Of Fitness Compact Genetic Algorithm For Rapid In-Flight Control Learning In A Flapping-Wing Micro Air Vehicle: A Search Space Reduction Approach, Kayleigh E. Duncan Jan 2019

Islands Of Fitness Compact Genetic Algorithm For Rapid In-Flight Control Learning In A Flapping-Wing Micro Air Vehicle: A Search Space Reduction Approach, Kayleigh E. Duncan

Browse all Theses and Dissertations

On-going effective control of insect-scale Flapping-Wing Micro Air Vehicles could be significantly advantaged by active in-flight control adaptation. Previous work demonstrated that in simulated vehicles with wing membrane damage, in-flight recovery of effective vehicle attitude and vehicle position control precision via use of an in-flight adaptive learning oscillator was possible. Most recent approaches to this problem employ an island-of-fitness compact genetic algorithm (ICGA) for oscillator learning. The work presented provides the details of a domain specific search space reduction approach implemented with existing ICGA and its effect on the in-flight learning time. Further, it will be demonstrated that the proposed …


Immersive Rehearsal In A Simulated Environment (Irise), Cassandra Clouse Jan 2019

Immersive Rehearsal In A Simulated Environment (Irise), Cassandra Clouse

Browse all Theses and Dissertations

Recent advancements in virtual environment (VE) technology and the growth of VE use in treating and training individuals are opening up new possibilities for rehearsal in safe and rich environments. Research has shown that VEs can be used to treat those with Post Traumatic Stress Disorder (PTSD), but very little research has been done to suggest good guidelines for creating an effective environment. This research was conducted to help inform the design of systems that let veterans rehearse potentially stressful experiences in a safe environment before having to physically step into that environment. We investigated responses to specific design components …


Blended Wing Design Considerations For A Next Generation Commercial Aircraft, Jay Abhilash Vora Jan 2019

Blended Wing Design Considerations For A Next Generation Commercial Aircraft, Jay Abhilash Vora

Browse all Theses and Dissertations

The current aircraft design has not changed significantly in the last few decades. Growing environmental concerns and fuel prices are driving manufacturers to develop unconventional but efficient aircraft configurations. The blended wing body (BWB) configuration provides an alternate and more efficient means of subsonic travel. The BWB aircraft replaces the traditional wings and fuselage with hybrid wing shape where the fuselage and wings have integrated. Major aircraft manufacturers are researching the BWB concept incorporating electric propulsion for civil transport use. In this research a 300 passenger BWB aircraft aerodynamic shape is designed. This aircraft is used to assess the aerodynamic …


Differential Microrna Expression In Barrett's Esophagus Correlates With Regulation Of Posterior Homeotic Genes, Reilly June Clark Jan 2019

Differential Microrna Expression In Barrett's Esophagus Correlates With Regulation Of Posterior Homeotic Genes, Reilly June Clark

Browse all Theses and Dissertations

Barrett’s Esophagus (BE) is characterized by the appearance of an intestinal-like epithelium in the distal esophagus. The molecular mechanisms behind BE development are unknown. BE is often preceded by Gastroesophageal Reflux Disease (GERD) and predisposes patients to esophageal adenocarcinoma (EAC). Due to the high mortality rate associated with EAC, BE patients are continuously monitored through upper endoscopy with biopsy for progression to low grade dysplasia (LGD), high grade dysplasia, and EAC. This monitoring technique poses numerous risks, so alternative surveillance and diagnostic techniques for BE pathogenesis are continually studied. microRNA biomarkers in BE pathogenesis may provide alternative means of diagnosis …


Power/Thermal Interaction Within An Adaptive Turbine Engine, Andrew K. Desomma Jan 2019

Power/Thermal Interaction Within An Adaptive Turbine Engine, Andrew K. Desomma

Browse all Theses and Dissertations

Usually power take off (PTO) with a two-spool turbofan engine has been accomplished via the high pressure (HP) shaft and bleed air from the high-pressure compressor (HPC). The PTO is used to run various aircraft components such as generators and hydraulic pumps, which also produce waste heat. To better understand the coupled transient nature of balancing engine thrust, power take off and thermal management, a transient variable cycle three stream turbofan engine model has been developed to investigate the integrated behavior. The model incorporates many dynamic features including a third-stream heat exchanger as a heat sink for thermal management and …


Towards Data And Model Confidentiality In Outsourced Machine Learning, Sagar Sharma Jan 2019

Towards Data And Model Confidentiality In Outsourced Machine Learning, Sagar Sharma

Browse all Theses and Dissertations

With massive data collections and needs for building powerful predictive models, data owners may choose to outsource storage and expensive machine learning computations to public cloud providers (Cloud). Data owners may choose cloud outsourcing due to the lack of in-house storage and computation resources or the expertise of building models. Similarly, users, who subscribe to specialized services such as movie streaming and social networking, voluntarily upload their data to the service providers' site for storage, analytics, and better services. The service provider, in turn, may also choose to benefit from ubiquitous cloud computing. However, outsourcing to a public cloud provider …


Hierarchical Carbon Structures With Vertically- Aligned Nanotube Carpets For Oil-Water Separation Under Different Conditions, Kimia Kiaei Jan 2019

Hierarchical Carbon Structures With Vertically- Aligned Nanotube Carpets For Oil-Water Separation Under Different Conditions, Kimia Kiaei

Browse all Theses and Dissertations

The primary purpose of this study is to investigate the role of surface nano-structuring in fluid separation. It is hypothesized that hierarchical carbon structures consisting of aligned carbon nanotube arrays strongly adhered to the surface of porous carbon solids such as fabric and foam, can be used for separation of polar and non-polar fluids by selective wettability of one fluid and rejection of another. The vertically-aligned carbon nanotube arrays, as synthesized, possess super hydrophobicity demonstrated by high water contact angle on their surfaces. On the other hand, they are incredibly oleophilic, showing a high affinity to adsorb oil. These properties …


Abusive And Hate Speech Tweets Detection With Text Generation, Abhishek Nalamothu Jan 2019

Abusive And Hate Speech Tweets Detection With Text Generation, Abhishek Nalamothu

Browse all Theses and Dissertations

According to a Pew Research study, 41% of Americans have personally experienced online harassment and two-thirds of Americans have witnessed harassment in 2017. Hence, online harassment detection is vital for securing and sustaining the popularity and viability of online social networks. Machine learning techniques play a crucial role in automatic harassment detection. One of the challenges of using supervised approaches is training data imbalance. Existing text generation techniques can help augment the training data, but they are still inadequate and ineffective. This research explores the role of domain-specific knowledge to complement the limited training data available for training a text …