Engineering Commons^™

Investigation Of Microstructural Alterations In M50 And 52100 Steel Using Nanoindentation, Kristin R. Paulson

Open Access Theses

Bearing steels are used in rolling elements and are designed to withstand heavy loads for an extended period of time. At the end of life, microstructural alterations within the material have been observed and are linked to failure. In this study, a three ball-on-rod fatigue tester was used to test M50 and 52100 steel cylindrical rods at differing loads of 4.0 GPa, 4.5 GPa, and 5.0 GPa and in lubricated and unlubricated conditions to 10 8 cycles in an attempt to produce microstructural alterations. Microstructural alterations characterized as butterflies were observed and investigated further in two M50 samples that were …

Evaluation Of Collapse Indicators For Seismically Vulnerable Reinforced Concrete Buildings, Nicholas R. Skok

Open Access Theses

Older reinforced concrete buildings can be prone to column shear and compression failures during earthquakes because of inadequate transverse reinforcement. Cities in seismic areas still have large inventories of older and potentially deficient buildings. To analyze every building and estimate its vulnerability in detail is costly. A simple method to rank quickly older buildings according to their seismic vulnerability is needed to help engineers prioritize the use of resources for rehabilitating the most vulnerable buildings.

Four indicators of building damage or collapse were evaluated using numerical analysis and prior data from building surveys: column index (Hassan & Sozen, 1997), R …

Realization And Evaluation Of A 3-Degrees-Of-Freedom Mouse Model, Udayan Umapathi

Open Access Theses

Kinesiology research has shown that translation and rotation are inseparable actions in the real world. Motivated by this fact, this thesis explores a model for the computer mouse, the new addition being rotational input about vertical axis of a mouse. We realize our model through Mushaca, a 3-degrees-of-freedom mouse (3DOF mouse) that can sense rotation, in addition to sensing XY planar translation. The thesis presents two realizations of Mushaca - namely a MEMS version that uses accelerometer and gyroscope, and an optical sensor version that uses two optical sensors. Through a controlled user study we try to find out if …

Evaluation Of Methods For Estimating Prestress Losses In High-Strength Structural Concrete, Mayren Yelitza Mata Carrillo

Open Access Theses

The purpose of this study was to evaluate the applicability of several current approaches used to estimate losses in prestressed concrete members with compressive strengths greater than 15ksi. The scope of the study focused on time-dependent losses for normal weight concrete bonded applications. The approaches evaluated were the PCI Design Handbook (2010) method, the AASHTO Specifications (2012) refined method, the PCI Bridge Design Manual (2003) time-dependent analysis using both the AASHTO (2012) and the PCI-BDM (2003) creep and shrinkage models, and a time-step method developed by Swartz (2010). The methods were compared to existing data on prestress losses from twenty-two …

Usability Of Immersive Virtual Reality Input Devices, Christopher G. Mankey

Open Access Dissertations

This research conducts a usability analysis of human interface devices within an Immersive Virtual Reality Environment. The analysis is carried out for two different interface devices, a commercially available Intersense ^© Wand and a home built pinch glove and wireless receiver. Users were asked to carry out a series of minor tasks involving placement of shaped blocks into corresponding holes within an Immersive Virtual Reality Environment. Performance was evaluated in terms of speed, accuracy and precision via the collection of completion times, errors made and the precision of motion during the experiment.

Evaluating Optimum Levels Of Detail For 3d Interactive Aviation Maintenance Instructions, Nicholas Rohe

Open Access Theses

With the aviation industry shifting from paper based maintenance instructions to digital maintenance instructions, there needs to be a standard for what goes into creating the digital instructions. This study was done to determine what the optimum level of detail for 3D interactive aviation maintenance instructions. The definition of optimum for this study was: lowest amount of geometrical data with lowest rendering needed for comprehension and ease of use.

Augmented Reality Application Utility For Aviation Maintenance Work Instruction, John Bryan Pourcho

Open Access Theses

Current aviation maintenance work instructions do not display information effectively enough to prevent costly errors and safety concerns. Aircraft are complex assemblies of highly interrelated components that confound troubleshooting and can make the maintenance procedure difficult (Drury & Gramopadhye, 2001). The sophisticated nature of aircraft maintenance necessitates a revolutionized training intervention for aviation maintenance technicians (United States General Accounting Office, 2003). Quite simply, the paper based job task cards fall short of offering rapid access to technical data and the system or component visualization necessary for working on complex integrated aircraft systems. Possible solutions to this problem include upgraded standards …

Nuclear Magnetic Resonance Studies On Lithium And Sodium Electrode Materials For Rechargeable Batteries, Tetiana Nosach

Dissertations, Theses, and Capstone Projects

In this thesis, Nuclear Magnetic Resonance (NMR) spectroscopic techniques are used to study lithium and sodium electrode materials for advanced rechargeable batteries. Three projects are described in this thesis. The first two projects involve 6Li, 7Li and 31P NMR studies of two cathode materials for advanced rechargeable batteries. The third project is a study of sodium titanate cathode materials for Na-ion batteries, where 1H, 7Li, and 23Na static and magic angle spinning NMR were used in order to obtain detailed information on the chemical environments.

Dynamics Of Nanoparticles In Fluids And At Interfaces, Weikang Chen

Dissertations, Theses, and Capstone Projects

In this thesis, we use molecular dynamics simulation to study three basic behaviors or properties of nanoparticles: deposition during droplets evaporation, slip boundary condition and Brownian motion. These three problems address the need for an in-depth understanding of the dynamics of nanoparticles in fluids and at interfaces. In the first problem, evaporation of the droplets dispersed with particles, we investigated the distribution of evaporative flux, inner flow field, density and temperature. And we use these numerical experiments to check on our hydrodynamic theory of the "coffee ring" phenomenon. The simulations reveal the connection between the particle interactions and the deposit …

Synthesis And Evaluation Of Sensitizer Drug Photorelease Chemistry: Micro-Optic Method Applied To Singlet Oxygen Generation And Drug Delivery, Goutam Ghosh

Dissertations, Theses, and Capstone Projects

This thesis summarizes a new micro-optic method for singlet oxygen generation and sensitizer drug delivery, which include i) synthesis and evaluation of a first generation device for drug delivery from native and fluorinated silica probe tips, ii) synthesis of PEG conjugated sensitizers to study phototoxicity in ovarian cancer cells, and iii) synthesis and evaluation of tris-PEGylated chlorin conjugated fluorinated silica for its future integration into the device to use as a 2nd generation device. A first generation micro-optic device was developed that works by sparging O2 gas and light generating cytotoxic singlet oxygen that cleaves the covalently attached drug (sensitizer) …

Transport And Optical Properties Of Low-Dimensional Complex Systems, Andrii Iurov

Dissertations, Theses, and Capstone Projects

Over the last five years of my research work, I, my research was mainly concerned with certain crucial tunneling, transport and optical properties of novel low-dimensional graphitic and carbon-based materials as well as topological insulators. Both single-electron and many-body problems were addressed. We investigated the Dirac electrons transmission through a potential barrier in the presence of circularly polarized light. An anomalous photon-assisted enhanced transmission is predicted and explained in a comparison with the well-known Klein paradox. It is demonstrated that the perfect transmission for nearly-head-on collision in an infinite graphene is suppressed in gapped dressed states of electrons, which is …

Water Conservation To Reduce Wet Weather Pollution Loads To The Gowanus Canal, Brooklyn, Ny, Suzanne Carol Stempel

Dissertations, Theses, and Capstone Projects

Public participation plays an important role in wet weather pollution management. However, the effects of participation programs on local water quality are often difficult to quantify. This project aims to quantify the potential effects of a community based, non-structural, BMP aimed at controlling inputs to combined sewage systems by encouraging residents to reduce their water use during rain events. A household could participate by reducing the amount of water they use for flushing toilets, washing dishes, taking showers, etc. during rain events; thereby reducing stress on the system during the time of highest demand. The Gowanus Canal sewershed in Brooklyn, …

Control Of Light-Matter Interaction Via Dispersion Engineering, Harish Natarajan Swaha Krishnamoorthy

Dissertations, Theses, and Capstone Projects

This thesis describes the design, fabrication and characterization of certain nanostructures to engineer light-matter interaction. These materials have peculiar dispersion properties owing to their structural design, which is exploited to control spontaneous emission properties of emitters such as quantum dots and dye molecules. We will discuss two classes of materials based on the size of their unit cell compared to the wavelength of the electromagnetic radiation they interact with. The first class are hyperbolic metamaterials (HMM) composed of alternate layers of a metal and a dielectric of thicknesses much smaller than the wave- length. Using a HMM composed of silver …

Characterization Of Wide Band Gap Semiconductors And Multiferroic Materials, Bo Cai

Dissertations, Theses, and Capstone Projects

Structural, optical and electrical properties of zinc oxide (ZnO), aluminum nitride (AlN), and lutetium ferrite (LuFe₂O4) have been investigated. Temperature dependent Hall Effect measurements were performed between 80 and 800 K for phosphorus (P) and arsenic (As) doped ZnO thin films grown on c-plane sapphire substrate by RF magnetron sputtering. These samples exhibited n-type conductivity throughout the temperature range with carrier concentration of 3.85 × 10 ¹⁶ cm^-3 and 3.65 × 10 ¹⁷ cm^-3 at room temperature for P-doped and As-doped ZnO films, respectively. The Arrhenius plots of free electron concentration of those doped samples showed …

Cited2-Mediated Mechanotransduction And Its Use For Chondroprotection, Daniel J. Leong

Dissertations, Theses, and Capstone Projects

Novel prevention and therapeutic treatment for cartilage degradation is urgently called for, as cartilage degradation is a hallmark for arthritic diseases including osteoarthritis (OA) and rheumatoid arthritis (RA), and there is a high incidence of arthritis-related disability and high medical costs. While both underuse (e.g. physically inactive lifestyle) and overuse (e.g. high impact or intense repetitive joint use as seen in certain sports) are risk factors for cartilage degradation, recent studies highlight that dynamic moderate loading is associated with reduced incidence of developing OA. Exercise is prescribed in most cases at moderate levels for both OA and RA patients, and …

Synthesis, Fabrication And Characterization Of Magnetic And Dielectric Nanoparticles And Nanocomposite Films, Xiaohua Liu

Dissertations, Theses, and Capstone Projects

Materials science is an interdisciplinary field investigating the structure-property relationship in solid-state materials scientifically and technologically. Nanoscience is concerned with the distinctive properties that matter exhibits when confined to physical dimensions on the order of 10^-9 meters. At these length scales, behaviors of particles or elaborate structures are often governed by the rules of quantum mechanics in addition to the physical properties associated with the bulk material.

The work reported here seeks to employ nanocystals, binary nanocomposites and thin films of materials, to build versatile, functional systems and devices. With a focus on dielectric, ferroelectric, and magnetoelectric performance, a …

Design Of Well-Defined Mesoporous Silicas Via Surfactant Templating Method Enhanced By The Use Of Swelling Agents, Tiffany Man

Dissertations, Theses, and Capstone Projects

Surfactant-templated ordered mesoporous materials continue to attract tremendous attention as these materials are characterized by reproducibility and predictability of their synthesis as well as their wide range of potential applications, which serve as future opportunities for additional advancement. The main purpose of this dissertation is to advance the understanding how to control the structural features and properties in the synthesis of well-defined porous materials via surfactant templating method, while keeping in mind that the uniformity of pore size and structural ordering are essential characteristics for these well-defined materials. The work was primarily focused on the issue of the unit-cell size …

2014 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2014.

Novel On-Chip Applications Using Silicon Photonics, Rania Gamal

Theses and Dissertations

The emerging field of silicon photonics offers solutions to designing CMOScompatible optical devices. By taking advantage of the immense fabrication infrastructure offered by the silicon industry, it would be possible to design optical structures that are smaller, faster, less-power consuming and cheaper than traditional, non-silicon-based optical devices. In this dissertation, the design and performance testing of two novel silicon photonic structures are presented: 1) Silicon nanowire ridge waveguide for sensing applications at the optical transmission frequency. 2) Doped silicon plasmonic structures for negative-index, epsilon-near-zero and sensing applications at the mid-infrared. For the first design, silicon nanowires are arranged in a …

Multi-Agent Orienteering Problem With Time-Dependent Capacity Constraints, Cen Chen, Shih-Fen Cheng, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

In this paper, we formulate and study the Multi-agent Orienteering Problem with Time-dependent Capacity Constraints (MOPTCC). MOPTCC is similar to the classical orienteering problem at single-agent level: given a limited time budget, an agent travels around the network and collects rewards by visiting different nodes, with the objective of maximizing the sum of his collected rewards. The most important feature we introduce in MOPTCC is the inclusion of multiple competing agents. All agents in MOPTCC are assumed to be self-interested, and they interact with each other when arrive at certain nodes simultaneously. As all nodes are capacitated, if a particular …

A Regression Approach For Estimation Of Anthropogenic Heat Flux Based On A Bottom-Up Air Pollutant Emission Database, Sanghyun Lee, Stuart A. Mckeen, David J. Sailor

Mechanical and Materials Engineering Faculty Publications and Presentations

A statistical regression method is presented for estimating hourly anthropogenic heat flux (AHF) using an anthropogenic pollutant emission inventory for use in mesoscale meteorological and air-quality modeling. Based on bottom-up AHF estimated from detailed energy consumption data and anthropogenic pollutant emissions of carbon monoxide (CO) and nitrogen oxides (NO_x) in the US National Emission Inventory year 2005 (NEI-2005), a robust regression relation between the AHF and the pollutant emissions is obtained for Houston. This relation is a combination of two power functions (Y = aX^b) relating CO and NO_x emissions to AHF, giving a determinant …

Pixel-Based Absorption Correction For Dual-Tracer Fluorescence Imaging Of Receptor Binding Potential, Stephen C. Kanick, Kenneth M. Tichauer, Jason Gunn, Kimberley S. Samkoe, Brian W. Pogue

Dartmouth Scholarship

Ratiometric approaches to quantifying molecular concentrations have been used for decades in microscopy, but have rarely been exploited in vivo until recently. One dual-tracer approach can utilize an untargeted reference tracer to account for non-specific uptake of a receptor-targeted tracer, and ultimately estimate receptor binding potential quantitatively. However, interpretation of the relative dynamic distribution kinetics is confounded by differences in local tissue absorption at the wavelengths used for each tracer. This study simulated the influence of absorption on fluorescence emission intensity and depth sensitivity at typical near-infrared fluorophore wavelength bands near 700 and 800 nm in mouse skin in order …

Distributed Event Detection In Sensor Networks Under Random Spatial Deployment, P. Zhang, G. Peters, I. Nevat, G. Xiao, Hwee-Pink Tan

Research Collection School Of Computing and Information Systems

We present a novel event detection algorithm in sensor networks for the case where the sensors are randomly deployed in space. In particular we consider a random sensors deployment according to a Homogeneous Finite Binomial Point Process. We first derive the optimal event detection decision rule. We then develop a novel algorithm to evaluate the intractable marginal likelihood based on the Gram-Charlier series expansion. We evaluate our algorithms through extensive Monte Carlo simulations. Simulation results present the detection and false alarm rates for different system parameters such as number of sensors deployed, deployment region size etc.

Survey On Wakeup Scheduling For Environmentally-Powered Wireless Sensor Networks, Alvin Cerdena Valera, Wee-Seng Soh, Hwee-Pink Tan

Research Collection School Of Computing and Information Systems

Advances in energy harvesting technologies and ultra low-power computing and communication devices are enabling the realization of environmentally-powered wireless sensor networks (EPWSNs). Because of limited and dynamic energy supply, EPWSNs are duty-cycled to achieve energy-neutrality, a condition where the energy demand does not exceed the energy supply. Duty cycling entails nodes to sleep and wakeup according to a wakeup scheduling scheme. In this paper, we survey the various wakeup scheduling schemes, with focus on their suitability for EPWSNs. A classification scheme is proposed to characterize existing wakeup scheduling schemes, with three main categories, namely, asynchronous, synchronous, and …

Effect Of Air Carrier Restructuring Strategies On Post-Bankruptcy Performance, Harold Dale Townsend

Doctoral Dissertations and Master's Theses

Air carrier bankruptcy is a common occurrence in the aviation industry. However, there is a paucity of research on the topic of air carrier restructuring during the post-bankruptcy period. General restructuring literature has identified four types of actions: operational, financial, managerial, and portfolio. The purpose of this study was to partially fill the large literature gap in the area of air carrier post-bankruptcy performance through theoretical and practical contributions.

A multilevel exploratory factor analysis was conducted to explore whether the same restructuring areas were found in air carrier specific metrics. All four restructuring areas were found in the factor analysis. …

National Culture: Understanding The Impact Of Cross-Culture On Airline Pilots' Safety Performance In The Middle-East And North Africa (Mena) Region, Shareef Abdulla Kaddas Al-Romaithi

Doctoral Dissertations and Master's Theses

The continuous expansion of Middle Eastern airlines has created a pilot shortage. Since the local pilot population in the Middle East is relatively small, airlines have been relying on foreign pilots to satisfy their operational requirements. Consequently, pilots with diverse cultural perspectives have been operating together. In order to manage this cultural diversity and ensure safe operations, airlines have been applying a number of training and operational strategies such as Crew Resource Management (CRM) with emphasis on adherence to Standard Operating Procedures (SOP). However, CRM was designed and implemented by North Americans as a solution for human factor intricacies among …

Investigation Of Pulse Detonation Engine Flow Conditions For Turbomachinery Integration, Luis Estefano Ferrer-Vidal EspañA-Heredia

Doctoral Dissertations and Master's Theses

Pressure gain combustion has been known to be more thermodynamically efficient than its constant pressure counterpart, which employs deflagration. Integration of pressure gain combustors into gas turbine engines has been and still is one of the most important challenges facing the gas turbine industry. Pressure gain combustion devices are inherently unsteady. This unsteadiness affects turbomachinery components designed using steady operation assumptions, and results in mechanical inefficiencies which could outweigh the thermal efficiency benefits. Understanding of turbine components specifically made to operate in the exhaust conditions provided by a pressure gain combustor may yield new turbine design paradigms. As a first …

Reduction Of Secondary Flow Losses In A Turbine For Use In Man-Portable Power Generation, Andrew J. Yatsko

Doctoral Dissertations and Master's Theses

As the world has moved into a more energy-demanding environment, there has been the push for higher energy density in a smaller package. One of the potential solutions is through the application of a gas turbine engine; yet the challenge is extracting the energy efficiently through the small components. The focus of the research is on the turbine components and how the secondary flow losses from the generated airfoil shapes can be reduced to improve component performance. One of the secondary flow loss items to be addressed is the generation of the Horseshoe Vortex. The Horseshoe Vortex is an aerodynamic …

The Effects Of Rewards On The Ability Of An Autonomous Uav Controlled By A Reinforcement Learning Agent To Accomplish A Target Localization Task, Hemali Dinesh Virani

Doctoral Dissertations and Master's Theses

The need for Unmanned Aerial System (UASs) is increasing in the fields of science, security, military and others. With an increasing number of challenges faced by mankind the need for system with advance autonomous and intelligent capabilities is growing rapidly. The required intelligent behavior can be achieved in an unmanned system with machine learning methods such as Reinforcement Learning (RL) theory. This theory presents algorithms which have the capability to learn how to adapt to its environment. Using RL methods, autonomous systems have the ability to use past experiences to improve future mission performance. In this research, the effects of …

A Subject-Specific Multiscale Model Of Transcranial Magnetic Stimulation, Brian Daniel Goodwin

Dissertations (1934 -)

Transcranial magnetic stimulation (TMS) is a neuromodulation technique used to treat a variety of neurological disorders. While many types of neuromodulation therapy are invasive, TMS is an attractive alternative because it is noninvasive and has a very strong safety record. However, clinical use of TMS has preceded a thorough scientific understanding: its mechanisms of action remain elusive, and the spatial extent of modulation is not well understood. We created a subject-specific, multiscale computational model to gain insights into the physiological response during motor cortex TMS. Specifically, we developed an approach that integrates three main components: 1) a high-resolution anatomical MR …