Engineering Commons^™

Surface Phonon Polariton-Enhanced Ring Resonator And E-Plane Hybrid Ring Coupler, Cláudio Augusto Barreto Saunders Filho

Theses and Dissertations

Surface polaritons are known for providing the ability to confine light beyond the Abbe’s limit of diffraction. While metals efficiently support surface plasmon polaritons in the visible-UV spectrum, some semiconductors can support surface phonon polaritons in the infrared. Ring resonators are devices with high integration level with optical interconnects and with applications including filters, directional couplers, modulators and interferometers. Loss associated to ring curvature yields ring radius on the order of tens of free-space wavelengths. SPhP-enhanced micro-ring resonator was proposed and it was shown that ring dimensions are reduced. Advances in nanofabrication processes allow the design of optical interconnects using …

Advancing Numerical Calculation Of Mixed Sized Sediment Transport And Morphology Change, Irene Margaret Watts

Theses and Dissertations

Numerical modeling of sediment transport and morphologic change has become a powerful tool for studying and working in the coastal zone. Numerical calculation can assist in a broad range of projects from regional sediment management to beach nourishment as well as evaluating environmental aspects of dredging and placement and implications to water quality and turbidity. Success in application of these tools is partially dependent on the quality of characterization of the sediments in the field. These parameters could include grain size, mineralogical composition, specific gravity and fall velocity. Sediment transport formulations are sensitive to the spatial representation of the sediments …

A Coastal Estuarine Ensemble Forecasting System, Peyman Taeb

Theses and Dissertations

This research has been conducted in an effort to reduce the computational costs associated with high-resolution coastal estuarine modeling in ADCIRC. It was proposed that model scalability will be significantly enhanced if the conventional single-domain technique is replaced by a nesting method. Preliminary testing indicated the potential for 50% to more than 80% simulation runtime reduction (depending on the study site) by implementing a nesting technique. Once the concept was proved, the development of an operational, ensemble-based forecasting system, exclusively for the east coast of Central Florida and the IRL system, was implemented. The system, referred to as Ensemble Multistage, …

Developing An Interview Protocol For An Engineering Design Capstone Course To Measure Student Motivation And Engineering Identity, Mckenzie Clark

Theses and Dissertations

This thesis examines the process of developing an effective in-depth interview protocol to measure student motivation and engineering identity. Several methods were employed during the creation, refining, and analysis portions of this study to ensure reliability and validity of the qualitative research instrument. In a multifaceted course such as senior capstone design, it is integral to ensure students are receiving a value adding experience. In most universities across the United States, senior capstone design is a multiple semester sequence where design is heavily emphasized and students are encouraged to test their skills, both technical and nontechnical, by solving and implementing …

Modeling To Predict The Salt Transport Between A Scale Model Estuary And The Unconfined Aquifer With Groundwater Flow, Abeer Ibraheem Khazaly

Theses and Dissertations

In many field studies, variation in fluid density may have important effects on controlling groundwater flow and solute transport processes. These studies include: Indian River Lagoon (IRL), a coastal estuary, located on the east coast of Florida, saline disposal basins, radioactive waste disposal and contaminant spills. In the environment, where the fresh groundwater region is in direct contact with the saline seawater region in coastal aquifers, dynamic equilibrium normally exists between these two regions, but there are numerous human and environmental factors that can adversely impact the equilibrium and lead to severe saltwater contamination of the freshwater region. Intrusion of …

Merging Parallel-Plate And Levitation Actuators To Enable Linearity And Tunability In Electrostatic Mems, Mark Pallay, Ronald N. Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

In this study, a linear electrostatic MEMS actuator is introduced. The system consists of a MEMS cantilever beam with combined parallel-plate and electrostatic levitation forces. By using these two forcing methods simultaneously, the static response and natural frequency can be made to vary linearly with the voltage. The static response shows a linear increase of 90 nm/V and is maintained for more than 12μm of the tip displacement. The natural frequency shows a linear increase of 16 Hz/V and is maintained throughout a 2.9 kHz shift in the natural frequency. This wide range of linear displacement and frequency tunability is …

Co-Optimization Approach To Post-Storm Recovery For Interdependent Power And Transportation Systems, Yinyin Ge, Lili Du, Hongzing Ye

Electrical and Computer Engineering Faculty Publications

The power and transportation systems are urban interdependent critical infrastructures (CIs). During the post-disaster restoration process, transportation mobility and power restoration process are interdependent, and their functionalities significantly affect other well-beings of other urban CIs. Therefore, to enhance the resilience of urban CIs, successful recovery strategies should promote CI function cooperatively and synergistically to distribute goods and services efficiently. This paper develops an integrative framework that addresses the challenges of enhancing the recovery efficiency of urban power and transportation systems in short-term recovery period. Specifically, the post-storm recovery process is considered as a scheduling problem under the constraints representing crew …

Development Of Prognostics Techniques For Surface Defect Growth In Railroad Bearing Rolling Elements, Nancy De Los Santos

Theses and Dissertations

One of the major causes of failure in railroad bearings used in freight service is rolling contact fatigue (RCF). RCF is due to subsurface inclusions which are a result from impurities in the steel that is used to fabricate the bearings. Once the bearings initiate subsurface fatigue cracks, they will then propagate upward and initiate spalling of the rolling surfaces. These spalls will begin small and continuously propagate with operation as this induces additional crack forming and spalling. Studies have indicated that bearing temperature is not a good indicator of spall initiation. In many cases, the temperature of the bearing …

Cost-Effective Methods To Retrofit Metal Culverts Using Composites, Mahmoud Reda Taha, Susan Bogus Halter

Publications

One of the current pressing problems for all DOTs is the corrosion-oriented deterioration of existing metal culverts. These metal culverts typically are designed for a life of 50 years. However, corrosion is making them last no longer than 30 years. A Glass Fiber Reinforced Polymers (GFRP) pipe section has been evaluated as a fit-in GFRP profile liner for complete repair and rehabilitation of the corroded metal culvert with an expected life of 75 years. This is mainly because of the corrosion free nature of the GFRP material. A comprehensive rehabilitation methodology and laboratory scale three-point bending test was conducted to …

A Longitudinal Analysis Of The Impact Of The Indicators In The Networked Readiness Index (Nri), Satya Pratipatti, Ahmed Gomaa

Journal of International Technology and Information Management

World Economic Forum publishes the Networked Readiness Index (NRI) annually, to reflect the Information and Communication Technology (ICT) status of different countries. The NRI is developed by aggregating 53 indicators. The study identifies the most critical indicators to focus on, to improve the NRI status of countries at different stages of economic development. It uses data from 117 countries and analyzes the changes in the indicators along with their impacts between the years 2012 and 2016. The study explores the differences between countries by grouping them into four groups based on their NRI status. The analysis identifies six indicators with …

Design Principles And Preliminary Testing Of A Micropropulsion Electrospray Thruster Research Platform, Will Alan Mcgehee

Master's Theses

The need for micropropulsion solutions for spacecraft has been steadily increasing as scientific payloads require higher accuracy maneuvers and as the use of small form-factor spacecraft such as CubeSats becomes more common. Of the technologies used for this purpose, electrospray thrusters offer performance that make them an ideal choice. Electrosprays offer high accuracy impulse bits at low power and high efficiency, and have low volume requirements. Design choice reasoning and preliminary testing results are presented for two electrospray thruster designs. The first thruster, named the Demonstration thruster, is operated in atmospheric conditions and serves as a highly visible example of …

Supplemental Vibrotactile Feedback Of Real-Time Limb Position Enhances Precision Of Goal-Directed Reaching, Nicoletta Risi, Valay Shah, Leigh A. Mrotek, Maura Casadio, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

We examined vibrotactile stimulation as a form of supplemental limb state feedback to enhance planning and ongoing control of goal-directed movements. Subjects wore a two-dimensional vibrotactile display on their nondominant arm while performing horizontal planar reaching with the dominant arm. The vibrotactile display provided feedback of hand position such that small hand displacements were more easily discriminable using vibrotactile feedback than with intrinsic proprioceptive feedback. When subjects relied solely on proprioception to capture visuospatial targets, performance was degraded by proprioceptive drift and an expansion of task space. By contrast, reach accuracy was enhanced immediately when subjects were provided vibrotactile feedback …

Curbside Antenna To Vehicle Path Loss Measurements And Modeling In Three Frequency Bands, Patrick Murphy

Theses and Dissertations

V2V and V2I systems have been an increasingly important topic of study in recent years. Future V2I systems could involve antennas near or on the curb at intersections or on the ground along highways. To this end the curbside antenna to vehicle channel has not been studied very much. The scope of this thesis is to develop initial models for the path loss for examples of this channel. This was done through a measurement campaign where the transmitting antenna is located on the ground near the road and the receiver is in a vehicle driving towards the transmitter. The vehicle …

Modeling Particle Dispersal In Bedload Dominated Settings, Sanaz Borhani

Theses and Dissertations

Tracer particles are used to study bedload transport in gravel bed rivers. One of the advantages associated with their use is that they allow for direct measurements of particle entrainment rates in bedload transport and particle displacement. The main issue in field studies with tracer particles is the difference between tracer short term and long term behavior. This difference is due to the fact that particles undergo vertical mixing or move to less active locations such as bars or even floodplains. For these reasons the mean tracer velocity decreases over time. This phenomenon has been called tracer slowdown and it …

The Study Of Flow Hydrodynamics And Transport Processes Over Mixed Bedrock-Alluvial Reaches, Mohammad Sadegh Jafarinik

Theses and Dissertations

Research efforts on mixed bedrock-alluvial rivers primary focused on the bedrock incision and very few studies investigated the alluvial morphodynamics of such systems. To the best of my knowledge none of these models have been considered the spatial variability of the sediment grain size of the bed surface in mixed bedrock-alluvial reaches and very few models focused on the spatial changes in alluvial cover within these reaches. Furthermore, a perusal of the literature on mixed bedrock-alluvial river morphodynamics reveals that very little information is available on 1) bedform geometry and flow resistances and 2) sediment sorting patterns in presence of …

Experimental Analysis Of The Automated Fiber Placement Manufacturing Parameters For High And Low Tack Prepreg Material, Anis Baz Radwan

Theses and Dissertations

Automated Fiber Placement (AFP) is a flexible but complex manufacturing technique which is used to layup carbon fiber tows into flat or curved structures. That could be achieved through linear and steered paths of fibers. The quality of AFP layup is highly dependent on the manufacturing process parameters such as layup temperature, tow feedrate, compaction force, and tow tension. Understanding how those parameters affect the process is crucial for achieving the desirable quality and productivity. For this work, an experimental investigation is carried out to determine the processing window that yields optimal quality for two types of material: High tack …

Impact Of Cycloalkanes On Ignition Propensity Measured As Derived Cetane Number In Multi-Component Surrogate Mixtures, Dalton Odell Carpenter

Theses and Dissertations

Cycloalkanes are one type of hydrocarbons present in real jet fuels. The distinct cyclic structure of the cyclo-alkanes impacts the chemical kinetic behavior differently compared to n- and iso-alkanes. At high temperatures, thermal decomposition reactions dominate, producing n-alkyl radicals similar to the oxidation reactions of n-alkanes thus promoting the reactivity. Whereas in low temperatures, the presence of the ring structure essentially suppresses the formation of alkylhydroperoxy radicals (QOOH) from alkylperoxy radicals (RO2), thus exhibiting similar reactivity to iso-alkanes. In previous generations of surrogate fuels, the cyclo-alkane functional group were largely ignored due to low levels of cycloalkanes in traditional jet …

Liquid Phase Modeling In Heterogeneous Catalysis, Mohammad Shamsus Saleheen

Theses and Dissertations

Conversion of lignocellulosic biomass into transportation fuels or commodity and specialty chemicals will be an important and fast-growing industry within the United States over the coming decades. Its growth will be driven by a variety of factors, including increased energy demands, environmental considerations, national security, and government mandates. To achieve the desired energy efficiency and economic impact, the emerging biorefining industries need novel heterogeneous catalysts with exceptional activity, selectivity, and stability. Catalytic materials developed in the petrochemical industries are generally not suitable for processing highly functionalized feedstocks typical of the biorefinery landscape. Due to the characteristics of this biomass feedstock …

3d Topology Optimization Of Spatially Reinforced Composites, Luis G. Bahamonde Jácome

Theses and Dissertations

Topology optimization is a numerical design tool used to generate structural concepts that present optimal load paths for a given set of functional requirements. This functional generative design capability has been used to lightweight high performance structures with 1D, 2D and 3D stress states. On the other hand, fiber-reinforced composites are the perfect candidate material to use in high performance structures due to the tailorability of their stiffness and strength properties. Although numerical tools that simultaneously tailor the composite material properties while optimizing the structural topology exist, these tools are inherently limited to 1D and 2D stress states.

This work …

Mechanical Characterization And Non-Destructive Evaluation Of SicF/SicM Composites For Nuclear Applications, Donald J. Mccleeary

Theses and Dissertations

The SiC_f/SiC_m composite material is a promising candidate for accident tolerant fuel cladding in light water reactors and for structural elements in high temperature reactors. The material demonstrates exceptional toughness when compared to monolithic ceramics. It is critical to characterize the mechanical behavior, internal damage and ultimate strength of these composites under relevant loading conditions. In this thesis, the author developed and improved several mechanical characterization and non-destructive evaluation methods and applied them to SiC_f/SiC_m composites. Impulse excitation (IE) analysis of damaged SiC_f/SiC_m composite disks following controlled impact testing shows a …

Development Of An Automated Fiber Placement Process For The Fabrication Of Thermoplastic Composite Laminates, Anthony M. Sabido

Theses and Dissertations

An automated fiber placement process is desired for manufacturing variable-stiffness thermoplastic composite laminates. By developing such a composite laminate, it is possible to take advantage of the tunable performance increases that are achievable by spatially steering individual tows. In addition, using a thermoplastic polymer as the matrix material has many advantages: a high toughness, ability to employ thermoplastic joining processes that do not require adhesives, long storage life, and lacks the need to be refrigerated. This process was experimentally developed, where the effect of various process parameters on the quality of the laminate were evaluated. An experimental AFP head was …

Damping In Transient Pressurized Flows, Sahad Salim Elyass Khilqa

Theses and Dissertations

Piping systems are commonly designed to withstand the first transient pressure peak, which is unaffected by dissipation. However, for multiple operations of control equipment, e.g., pump start-up following pump shutdown, load acceptance following load rejection on hydraulic turbines, etc., an accurate prediction of the dissipation of pressure oscillations is needed to determine a suitable time for the second operation. For this purpose, a method is presented to compute the dissipation of pressure oscillations in piping system following a simple procedure used for computing the dissipation of vibrations of bridges and other structures. Similar to structural engineering, this method is simple …

Automating School Fees Transactions In Nigerian Universities And Tertiary Institutions: A Systems Engineering And System Management Approach, Clement Aladi

LMU Theses and Dissertations

This project uses system engineering and system management principles to analyze the problem of transactions in Nigerian universities and tertiary institutions. System management principles shall be used to highlight the imperfections in the transaction method currently in use especially the disconnect between the bank and the institutions using their services. It will explore other payment systems available in the country. This project will provide a recommendation of how to implement a better payment option through automating the process of school payments by using a system with a cloud-based educational software at the school bursary office and through the online payment …

Surrogate Formulation Based On Chemical Functional Group Analysis, Stuart Nates

Theses and Dissertations

Chemical kinetic characteristics of real fuels exhibit high-dimensional complexity due to the excessive number of molecules and molecular classes. As a method of projecting this high-dimensional complexity, which is pertinent to real fuels, to the low-dimensional description, either a surrogate approach or detailed experiments have been utilized, can guide the construction of chemical kinetic models for real fuel. Although the validity of the surrogate approach has been extensively demonstrated by a wide range of canonical experiments for whole fuel/air mixtures, the use of empirical fuel property indicators still worries whether or not the surrogate mixture truly captures the more complex …

Spacecraft Trajectory Planning For Optimal Observability Using Angles-Only Navigation, Francisco José Franquiz

Doctoral Dissertations and Master's Theses

This work leverages existing techniques in angles-only navigation to develop optimal range observability maneuvers and trajectory planning methods for spacecraft under constrained relative motion. The resulting contribution is a guidance method for impulsive rendezvous and proximity operations valid for elliptic orbits of arbitrary eccentricity.

The system dynamics describe the relative motion of an arbitrary number of maneuvering (chaser) spacecraft about a single non-cooperative resident-space-object (RSO). The chaser spacecraft motion is constrained in terms of the 1) collision bounds of the RSO, 2) maximum fuel usage, 3) eclipse avoidance, and 4) optical sensor field of view restrictions. When more than one …

Sustainability Assessment Of U.S. Beef Processing And Its Antimicrobial Systems, Shaobin Li

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

With the increasing meat demand and awareness of sustainability, concerns have been raised regarding the sustainability of beef production and processing. However, scarce data and inadequate sustainability assessment frameworks for the U.S. beef processing industry limit the ability to develop new technologies and policies comprehensively without shifting sustainability burdens. To fill those gaps, various assessments of the U.S. beef processing industry were conducted from multiple perspectives regarding the environmental, economic, microbial effectiveness of its antimicrobial systems, and human health impacts from foodborne illness, occupational hazards, and environmental pollution.

First, process-level water and energy usage at a typical large-size beef processing …

English Language Proficiency And Aviation Safety, Robert Fowler Jr.

Student Works

The goal of this research study is to determine if aviation incidents and accidents due to deficiencies in English language proficiency have increased in the last 10 years based on data from the National Aeronautics and Space Administration (NASA) Aviation Safety Reporting System (ASRS). In addition, this study will determine whether deficiencies in English language proficiency have a significant impact on aviation safety. There are currently 184,636 student pilots according to the Federal Aviation Administration Airmen Certification System. Included in this number are 11,776 student pilots with a foreign address (Federal Aviation Administration [FAA], 2019). Findings presented at a NASA …

Photopumped Laser Diode Continuous Wave For Optical Gain Determination Of Nd:Yvo4 And Nd:Yag Crystal Medium, J Rajagukguk, W Chaiphaksa, J Kaewkhao, R Hidayat, F Fitrilawati

Journal of Metals, Materials and Minerals

Photopumped based on laser diode (LD) has designed by employing optical instruments which consist of laser source, optical lens and mirrors as resonator. This setup is aimed to determine of luminescence intensity of laser gain medium based on Nd:YAG and Nd:YVO4 crystals. Laser diode at 805 nm with continuous wave (CW) mode was used as pumping light source with the maximum output power 1 W. The 1064 nm wavelength laser can be obtained through a LD side pumped to laser gain medium, Nd3+ doped YAG and YVO4 crystals respectively. Laser gain medium is placed between intra cavity resonator and generates …

Too Agile? - Devops Software Development Challenges In A Military Environment, Burl T. Kenner Iii

Theses and Dissertations

Agile and DevOps software development processes now represent proven, commonly accepted models in commercial industry. For DoD military environments however, empowering teams of software developers and end user operators to build, test and release solutions without direct oversight and management of leadership is a brand new experience. In 2017, a DoD software acquisitions revolution occurred when approval was granted to scrap the former ineffective, cost prohibitive process and initiate the agile DevOps model. After one year since its introduction, this paper may represent the very first look at how well this nontraditional process is working out in a military command …

Enabling High Energy Density Aluminum Anodes For Alkaline Batteries, Xinyi Zhao

Theses and Dissertations

Zn-MnO₂ primary alkaline batteries stood out immediately among all batteries after it was introduced in the late 1980s and has attracted world-wide attention. These batteries have dominated the portable power market for decades as a highly effective energy storage system with high energy density, long life and low self-discharge, dependable safety and other superiorities.

In order to achieve higher cell-level energy density, Aluminum has long been considered a very attractive anode material for alkaline batteries because of its high theoretical capacity (2980 mAh/g; 2.60 Ah/cm³) and low price. However, some early efforts to utilize aluminum anodes did …