Digital Commons Network^™

A Remote Observatory For Geocoronal Hydrogen Emissions, Margaret A. Gallant

Doctoral Dissertations and Master's Theses

The Investigating Near Space Interaction Regions (INSpIRe) observatory is an adapt- able research facility that is designed to use Fabry-Perot interferometer (FPI) to study the faint Balmer series emissions of the terrestrial upper thermosphere and exosphere, collectively known as the geocorona. This instrumentation is designed to be deployable to a clear-air site, necessitating remote operations of the entire observatory, including control and monitoring. The facility currently employs a siderostat to allow for pointing at sky targets, a pressure-tuned dual-etalon FPI to allow for high spectral resolution (R_80,000) measurements, and several charge-coupled device (CCD) imagers for guiding and collecting data. The …

Nonlinear Sliding Mode Observer Applied To Microalgae Growth, Rebecca J. Griffith

Doctoral Dissertations and Master's Theses

Modeling biological processes, such as algae growth, is an area of ongoing research. The ability to understand the multitude of parameters that influence this system provides a platform for better understanding the dynamics of microalgae growth. Empirical modeling efforts look to understand sources of driving nutrients that influence harmful algal blooms (HABs). These harmful algal blooms are dense aggregates that have an increasingly negative impact on local economics, marine and freshwater systems, and public health. They result from a high influx of nitrogen and nutrients that drive the algae biomass to exponentially grow. This growth blocks out the sun, potentially …

Shape-Stabilization Of Pcm/Hdpe Composites With 3d-Printing Applications For Battery Thermal Management, Thomas Benjamin Freeman

Doctoral Dissertations and Master's Theses

Phase-change materials (PCMs) are a useful alternative to more traditional methods of thermal management of Li-ion batteries in electric or hybrid-electric vehicles. PCMs are materials which absorb large amounts of latent heat and undergo solid-to-liquid phase change at near-constant temperature. The goal of this thesis is to experimentally investigate the thermal properties of a novel shape-stabilized PCM/HDPE composite extruded filament. The extruded filament can then be used in a 3D printer for custom PCM/HDPE shapes. These custom PCM/HDPE shapes can be used to help reduce weight, energy consumption, and complexity of the thermal management of the ESS. The PCM used …

Design And Implementation Of Intelligent Guidance Algorithms For Uav Mission Protection, Karina Rivera

Doctoral Dissertations and Master's Theses

In recent years, the interest of investigating intelligent systems for Unmanned Aerial Vehicles (UAVs) have increased in popularity due to their large range of capabilities such as on-line obstacle avoidance, autonomy, search and rescue, fast prototyping and integration in the National Air Space (NAS). Many research efforts currently focus on system robustness against uncertainties but do not consider the probability of readjusting tasks based on the remaining resources to successfully complete the mission. In this thesis, an intelligent algorithm approach is proposed along with decision-making capabilities to enhance UAVs post-failure performance. This intelligent algorithm integrates a set of path planning …

Control Driven Scaling Effects Of Motor And Rotors For Urban Air Mobility Design, Agustin A. Giovagnoli

Doctoral Dissertations and Master's Theses

Through this thesis research the problem of controllability and propulsion associated with scaling-up consumer drones to vehicles that may carry significantly larger payloads, including passenger will be analyzed and tested. Controllability is mainly compromised due to the increasing response time of a larger rpm controlled rotor. This requires a more powerful motor, which translates into heavier and larger devices compromising the thrust-to-weight ratio. Collective pitch control at constant rpm is proposed as a first approach to mitigate the controllability problem, and it is tested in a MATLAB Simulink environment. This solution, linked to a Non-linear Dynamic Inversion controller, is simulated …

Design Of An Attitude Control System For A Spacecraft With Propellant Slosh Dynamics, Nolan Coulter

Doctoral Dissertations and Master's Theses

The presence of propellant slosh dynamics in a spacecraft system during a maneuver leads to attitude control system (ACS) performance degradation resulting in attitude tracking errors and instability. As spacecraft missions become more complex and involve longer durations, a substantial propellant mass is required to achieve the mission objectives and perform orbital maneuvers. When the propellant tanks are only partially filled, the liquid fuel moves inside the tanks with translational and rotational accelerations generating the slosh dynamics. This research effort performs a comparative study with different optimal control techniques and a novel application of a model reference artificial immune system …

Direct Adaptive Control For A Trajectory Tracking Uav, Nirmit Prabhakar

Doctoral Dissertations and Master's Theses

This research focuses on the theoretical development and analysis of a direct adaptive control algorithm to enable a fixed-wing UAV to track reference trajectories while in the presence of persistent external disturbances. A typical application of this work is autonomous flight through urban environments, where reference trajectories would be provided by a path planning algorithm and the vehicle would be subjected to significant wind gust disturbances. Full 6-DOF nonlinear and linear UAV simulation models are developed and used to study the performance of the direct adaptive control system for various scenarios. A stability proof is developed to prove convergence of …

A Numerical And Experimental Evaluation Of The Turbulent Heat Flux In A Heated Jet In Crossflow, Michael R. Borghi Jr.

Doctoral Dissertations and Master's Theses

The injection of fully-developed turbulent heated air from a tube into a cooler turbulent duct flow is examined, as an analogy to film cooled turbine blades. Scale Resolving Simulations (SRS) are used to examine the flow numerically. A Detached Eddy Simulation (DES) methodology is examined but found to be ineffective at correctly capturing the physics of the flow. A Large Eddy Simulation (LES) numerical model is developed and applied in which tube and duct turbulence inflow effects are emulated using a divergence-free synthetic eddy method (SEM). The LES sensitivity to the synthetic inflow turbulence is examined with a series of …

Topology Optimization Using Load Path And Homogenization, Kaveh Gharibi

Doctoral Dissertations and Master's Theses

In this work, the connection between topology optimization and load transfer has been established. New methods for determining load paths in two dimensional structures, plates and shells are introduced. In the two-dimensional space, there are two load paths with their total derivative equal to the transferred load, their partial derivatives related to stress tensor, and satisfying equilibrium. In the presence of a body load the stress tensor can be decomposed into solenoidal and irrotational fields using Gurtin or Helmholtz decomposition. The load path is calculated using the solenoidal field. A novel method for topology optimization using load paths and total …

Variable Fidelity Studies In Wake Vortex Evolution, Safety, And Control, Petr Kazarin

Doctoral Dissertations and Master's Theses

The purpose of this research is to develop a variable-fidelity approach for addressing the safety of unmanned aerial system (UAS) operations in the national aerospace system (NAS). This task is implemented on the basis of safety investigation toolkit for analysis and reporting wake vortex safety system (SITAR WVSS) code, which is a dynamic low-fidelity model addressing generation, evolution, and interaction of the leader-aircraft wake vortex with the follower-aircraft lifting surfaces.

The first part of the dissertation deals with the generation, evolution, and interaction of the wake vortices produced by an aircraft. In particular, it presents the results of the vortex …

Application Of Dupont’S Dirty Dozen Framework To Commercial Aviation Maintenance Incidents, Greg M. Mellema

Doctoral Dissertations and Master's Theses

This study examined the 12 preconditions for maintenance errors commonly known as the Dirty Dozen and applied them to actual incident and accident data provided by a participating airline (PA). The data provided by the PA consisted of Maintenance Event Reports (MERs) (reactive), Maintenance Operations Safety Assessment (MOSA) reports (proactive), and the results of the 2017 Maintenance Climate Awareness Survey (MCAS) (subjective). The MER and MOSA reports were coded by aviation maintenance subject matter experts (SMEs) using the 12 Dirty Dozen categories as the coding scheme, while the MCAS responses were parsed according to the precondition category they best represented. …

Identifying Criteria To Predict Army Rifle Marksmanship Proficiency, Katlin Makina Anglin

Doctoral Dissertations and Master's Theses

The United States Army requires each Soldier to develop marksmanship proficiency in an effort to achieve combat readiness. Soldiers currently develop marksmanship proficiency through Basic Rifle Marksmanship (BRM) training, but significant skill deficiencies are apparent at the end of training. These skill deficiencies remain throughout training because instructors rarely assess Soldiers objectively before the final qualification, reducing the opportunity for instructors to diagnose skill deficiencies until it is too late. Therefore, the goal of the current research is to identify individual differences and sensor-based performance measures for inclusion in a formative assessment during BRM training. The results of the current …

Impacts Of Anisotropy, Wave Heating, And Neutral Winds On High-Latitude Ionospheric Dynamics, Meghan R. Burleigh

Doctoral Dissertations and Master's Theses

Significant amounts of ionospheric plasma can be transported to high altitudes (ion upflow) in response to a variety of plasma heating and uplifting processes such as DC electric fields and precipitation. Once ions have been lifted to high altitudes, transverse ion acceleration by broadband ELF waves can give the upflowing ions sufficient energy for the mirror force to propel these ions to escape into the magnetosphere (ion outflow). In order to accurately examine the connection between upflow and outflow processes, a new two dimensional, anisotropic fluid model is developed.

The new model, named GEMINI-TIA, is based on a Bi-Maxwellian distribution …

Systems Engineering Design Of An Electronically Interactive Application For Runway Incursion Prevention, Yixuan Cheng

Doctoral Dissertations and Master's Theses

Runway Incursion is the leading cause of serious incidents or accidents in airports. One of the most common causes of a runway incursion is airport unfamiliarity. Therefore, the researcher designed an electronically interactive application as a practice tool for pilots to utilize during flight preparation. The objective of this application is to enhance airport familiarity to ultimately reduce runway incursion. This application is interactive, affordable, accessible, and mobile device-based. It was designed using the Systems Engineering approach, following Human Factors Engineering principles to make this application user-friendly and to provide optimized human machine interaction. A model-based Systems Engineering software-CORE was …

Evaluation Of Airline Efficiency And Environmental Impacts Using Data Envelopment Analysis, Arun Paul Saini

Doctoral Dissertations and Master's Theses

Airline efficiency has been a focus of research since the birth of the airline industry. Data envelopment analysis has become a highly accepted methodology for performing efficiency analysis and assessing relative differences between comparable business entities; over the last decade, airline efficiency research has proliferated into this linear programming domain. While early airline efficiency research focused primarily on revenue generation and profitability, growing commercial social responsibility is driving greater investment into understanding and improving the environmental impact of airline operations. This study is intended to partially fill a gap in exigent literature. While limited data envelopment analysis including environmental impacts …

Effect Of Chemistry On Electrodynamics In The Martian Dynamo Region, Morgan M. Matheny

Doctoral Dissertations and Master's Theses

Electromagnetic interactions between Mars remnant crustal magnetic fields and solar and planetary ions lead to time and space variations of the ionosphere. In this work, we continue the investigations started by Riousset et al. [2013] and address the effect of chemistry on ion populations in the dynamo region, where ion dynamics are driven by collisions while electrons are still mostly magnetized. We adopt a mesoscale model to simulate dynamics of electrons and ions in the upper atmosphere (100–400 km). Our approach focuses on numerical studies using the Martian Multifluid Magnetohy drodynamic (MF-MHD) Model (M4). The dynamo is a region which …

Biofidelic Piezoresistive Sandwich Composites, Nengda Jiang

Doctoral Dissertations and Master's Theses

Silicone based biofidelic surrogates are being used in many biomedical applications; e.g. to understand the body injury mechanisms, evaluate protective equipment like helmets and armors. Apart from matching the mechanical behavior of bodily tissues, there is an increasing requirement for these materials to be electrically conductive and piezoresistive to facilitate direct instrumentation. Carbon nanotubes (CNTs) are a possible filler to impart electrical conductivity and piezoresistivity to silicone biofidelic materials. A sandwich structure of silicone and CNT sheet, comprising two dielectric facesheets and a highly conductive core layer has added advantages of raising the dielectric permittivity and suppressing dielectric loss.

In …

Development To A Flexible Surface Acoustic Wave Sensor For Strain Sensing, Neha Vedavathi Ramachandran

Doctoral Dissertations and Master's Theses

Surface acoustic wave (SAW) sensors have increasing demand in structural health monitoring due to its passive, variable bandwidth, reliable life-cycle, high accuracy, small size, and light nature. SAW sensors can not only provide the static states of the structural system, such as temperature and pressure but also enable continuous real-time monitoring of dynamic states including strains. SAW sensors are generally fabricated with a rigid piezoceramic substrate, incapable of adapting to highly curved surfaces or flexible objects. The ongoing demands of sensor adaptability with flexible substrates, which is also capable of wireless monitoring, is the basis of the research that can …

Prediction Of Airport Arrival Rates Using Data Mining Methods, Robert William Maxson

Doctoral Dissertations and Master's Theses

This research sought to establish and utilize relationships between environmental variable inputs and airport efficiency estimates by data mining archived weather and airport performance data at ten geographically and climatologically different airports. Several meaningful relationships were discovered using various statistical modeling methods within an overarching data mining protocol and the developed models were tested using historical data. Additionally, a selected model was deployed using real-time predictive weather information to estimate airport efficiency as a demonstration of potential operational usefulness.

This work employed SAS® Enterprise Miner TM data mining and modeling software to train and validate decision tree, neural network, and …

Parametric Study Of Aerodynamic Performance Of An Airfoil With Active Circulation Control Using Leading Edge Embedded Cross-Flow Fan, M A Qayyum Mazumder

Doctoral Dissertations and Master's Theses

A concept of a cross-flow fan (CFF) embedded near the leading edge of an airfoil to actively control the boundary layer for lift and thrust enhancement has been proposed. The design places a cross-flow fan near the leading edge of an airfoil and flow is drawn in from the pressure side of the airfoil, energized and expelled out to the suction side near the leading edge. This CFF system simulates the active boundary layer control by blowing commercial computational fluid dynamics (CFD) code ANSYS Fluent is employed to perform 2-D calculations based on various parameters of the CFF and compared …

Nonlinear Acoustic Waves Generated By Surface Disturbances And Their Effect On Lower Thermospheric Composition, Benedict Piñeyro

Doctoral Dissertations and Master's Theses

Recent nonlinear atmospheric models have provided important insight into acoustic waves generated by seismic events, which may steepen into shocks or saw-tooth trains while also dissipating strongly in the thermosphere. Although they have yielded results that agree with observations of ionospheric perturbations, dynamical models for the diffusive and stratified lower thermosphere often use single gas approximations with height-dependent physical properties (e.g. mean molecular weight, specific heats) that do not vary with time (fixed composition). This approximation is simpler and less computationally expensive than a true multi-fluid model, yet captures the important physical transition between molecular and atomic gases in the …

A Study Into Data Analysis Of Varying Types Of Langmuir Probes, William Merritt

Doctoral Dissertations and Master's Theses

Langmuir probes are ubiquitously used for in-situ measurements of plasma parameters. These probes have been placed on many different platforms, including experimental sounding rockets for measurements in mesosphere-lower-thermosphere, and also onboard satellites to obtain data sets over an extended period of time in the ionosphere. To accommodate such different situations, many different variations of the Langmuir probe design have been made. This thesis covers two such implementations, as well as the data analysis and issues that can arise with such instruments. The first of these implementations is a set of sweeping Langmuir probes on the Floating Potential Measurement Unit (FPMU) …

Determining The Location Of Runway Exits Using Airport Surface Detection Equipment, Christopher Bryan Clemmer

Doctoral Dissertations and Master's Theses

Airport surface detection equipment, such as ASDE-X, is used by thirty-five commercially operated airports throughout the United States. ASDE-X is responsible for the safe monitoring of aircraft movements as well as ground support vehicle operating on the airfield. Like most radar-based technologies, ASDE-X can report the position of any aircraft within a one second time interval. This data not only contains the geographic position, but also reports speed, heading, altitude, and aircraft specific characteristics. Using a quantitative approach, this research will use the data reported by ASDE-X to analyze current runway exit locations and develop an improved method of determining …

A Computational Fluid Dynamics Study On The Aerodynamic Performance Of Ram-Air Parachutes, Angelo A. Fonseca Pazmiño

Doctoral Dissertations and Master's Theses

The modeling of a ram-air parachute presents challenges in the prediction of the inflight geometry, as there is a strong interaction between the flow field and parachute structure. This thesis presents the development of a CAD design and CFD methodology to the simulation of ram-air parachutes in steady-state conditions. Starting from a 2D rib drawing, methods were developed to approximate the 3D geometry and efficiently model the parachute as a rigid and impermeable body. The use of distortions was implemented on a 2D, pseudo-2D, and 3D model to enhance their behavior during a real flight. The SST turbulence model was …

Improving Seaglider Efficiency: An Analysis Of Wing Shapes, Hull Morphologies, And Propulsion Methods, Christopher James Hockley

Doctoral Dissertations and Master's Theses

Autonomous underwater gliders are a family of autonomous underwater vehicles used for long-term observation of oceanic environments. These gliders leverage changes in buoyancy and the resulting vertical motion, to generate forward locomotion via hydrodynamic surfaces. In order to function for extended periods, these systems operate in a low-speed, low-drag regime. This research examines factors impacting the operational efficiencies of gliders, including morphological changes, configuration changes, and propulsion. An interesting question arises when considering the operational efficiencies of conventionally propelled systems at the operating speeds typical of gliders. Can a conventional propulsion system match the efficiency of an underwater glider buoyancy …

Sensitivity Analyses Of Optimized Attitude Estimators Using Sensor Fusion Solutions For Low-Cost Mems Configurations, Ryan W. Hoffman

Doctoral Dissertations and Master's Theses

Since the 1990’s, there has been increased focus on creating navigation systems for small unmanned systems, particularly small unmanned aerial systems (SUAS). Due to size, weight, and cost restrictions, compared to larger more costly manned systems, navigation systems for SUAS have evolved to be quite different from the proven systems of the past. Today, there are many solutions for the problem of navigation for SUAS. The problem has now become choosing the most fitting navigation solution for a given application/mission. This is particularly true for evaluating solutions that are fundamentally different.

This research analyses the performance and sensitivity of four …

General Aviation Pilot Acceptance And Adoption Of Electronic Flight Bag Technology, Troy Ernest Techau

Doctoral Dissertations and Master's Theses

This research used an adapted version of the extended Unified Theory of Acceptance and Use of Technology (UTAUT2) to examine electronic flight bag (EFB) acceptance and adoption for general aviation (GA) pilots. EFBs are a common tool in almost all types of aviation and feature many useful capabilities such as the ability to display traffic, weather, and aviation charts. Despite their potential benefits, while some pilots choose to use EFBs in their flight operations, others continue to rely on traditional paper charts and reference materials. Determination of which factors explain differences in pilot acceptance and adoption of EFBs could influence …

A Computational Analysis Of The Aerodynamics And Aeroacoustics Of Jets With Fluid Injection, Marco Coderoni

Doctoral Dissertations and Master's Theses

A detailed numerical analysis of fluidic injection as a tool to reduce noise emission is presented here. The noise reduction strategy, developed at the Pennsylvania State University, is based on injectors that blow air into the diverging section of the nozzle to emulate the effect of interior corrugation on the jet plume. The advantage is that the injection can be activated during takeoff and turned o_ during other phases of flight so that performance is not affected. Numerical simulations are performed on a military-style nozzle based on the GE F400-series engines, with a design Mach number of 1:65, for over-expanded …

Communication And Trust In Virtual And Face-To-Face Teams, Anthony Lee Baker

Doctoral Dissertations and Master's Theses

Virtual teams (VTs) accomplish shared goals by relying on technology-mediated communication to counteract geographic disparities. Rapid advances in technology have led to the near-ubiquity of VTs within modern organizations, but gaps in existing research designs afflict extant empirical VT research. This experiment evaluates the constructs of trust, communication, and effectiveness in VTs. Two-hundred six participants (103 teams) completed an interdependent task either face-to-face, mediated by a videoconferencing telepresence robot, or mediated by a voice call. I collected measures of cognitive trust, trust propensity, communication quality, and team effectiveness, and conducted in-depth communication analyses. Results suggest that while virtual teamwork does …

Parametrization Of Triple Screw Pumps For Aerospace Applications, Allison Putira

Doctoral Dissertations and Master's Theses

Triple Screw Pumps, a form of positive displacement pump, offer steady, high-pressure flow. In very small launch vehicles or upper stages turbopumps are not practical. This paper examines the performance of triple screw pumps to determine if they may serve as an alternative to turbopumps for use in small launch vehicles or upper stages. To this end, the geometry of the screws is first determined from the relative sizes of the screws and tooth height. From this — along with the screw angle and screw clearance — the performance parameters of flow rate, output pressure, and efficiency can be computed. …