Engineering Commons^™

Development Of Robust Control Laws For Disturbance Rejection In Rotorcraft Uavs, Johannes Verberne

Doctoral Dissertations and Master's Theses

Inherent stability inside the flight envelope must be guaranteed in order to safely introduce private and commercial UAV systems into the national airspace. The rejection of unknown external wind disturbances offers a challenging task due to the limited available information about the unpredictable and turbulent characteristics of the wind. This thesis focuses on the design, development and implementation of robust control algorithms for disturbance rejection in rotorcraft UAVs. The main focus is the rejection of external disturbances caused by wind influences. Four control algorithms are developed in an effort to mitigate wind effects: baseline nonlinear dynamic inversion (NLDI), a wind …

A Behavioral Research Model For Small Unmanned Aircraft Systems For Data Gathering Operations, Paul Leonard Myers Iii

Doctoral Dissertations and Master's Theses

According to Hitlin (2017) of the Pew Research Center, only 8% of U.S. citizens own an unmanned aircraft. Additionally, regarding feelings if U.S. citizens saw an unmanned aircraft flying close to where they live, 26% say they would be nervous, 12% feel angry, and 11% are scared. As of March 9, 2018, there were 1,050,328 U.S. small unmanned aircraft system (sUAS) registrations compared to 947,970 November 29, 2017. While sUAS use has increased in the U.S., it has lagged when compared to other items for personal use available to U.S. citizens as 92% own cell phones (Anderson, 2015). This slower …

Low-Tip-Speed High-Torque Proprotor Noise Approximation For Design Cycle Analysis, Xavier G. Santacruz

Doctoral Dissertations and Master's Theses

Noise reduction in aviation would enable urban missions that cannot be own with current generation helicopters because of their noisiness. This goal can be achieved by using electric motors as they are quieter and can produce higher torque at lower RPMs. Therefore, a proprotor system can be designed to exploit this characteristic potentially abating noise levels. This research performed noise approximations included with rotor aerodynamics for a single, electric-driven, hovering proprotor by creating a code meant to be used in design cycle analysis. The approximation was based on geometry by using the blade element momentum theory, and calculating the pressure …

Covering Shock Wave Induced Interfacial Mixing: Numerical Study And A Control Primer, Erik S. Proaño

Doctoral Dissertations and Master's Theses

This document is aiming toward deepening the understanding of the phenomena of mixing and the effect of the initial conditions in the cylindrical & spherical Richtmyer-Meshkov and Rayleigh-Taylor Instabilities. This work is focused on identifying the most energetic structures of the ow in order to define a reduced order model intended for modeling the evolution of the mixing layer after reshocking the density interface. Initially, Simulations are implemented for the two dimensional case of a cylindrical shock wave convergently approaching an initially wave-like perturbed density discontinuity formed by a target of Sulfur Hexauoride immersed into unshocked air with Atwood number …

Cfd Study Of Taylor-Like Vortices In Swirling Flows, Sattar Panahandehgar

Doctoral Dissertations and Master's Theses

Swirling flows are complex fluid motions that appear in various natural phenomena and man-made devices. Numerous engineering applications such as turbomachinery, jet engine combustion chambers, mixing tanks and industrial burners involve swirling flows. This wide range of applications is due to unique characteristics offered by swirling flows such as increase in mixing rate, heat transfer rate and wall shear stress. In this study the axisymmetric swirling flow behavior in the context of a hybrid rocket engine have been analyzed. While modeling the flow inside a cylindrical chamber using CFD, a similarity with the Taylor vortices instability has been observed. Similar …

Optimal Battery Weight Fraction For Serial Hybrid Propulsion System In Aircraft Design, Tsz Him Yeung

Doctoral Dissertations and Master's Theses

This thesis focuses on electric propulsion technology associated with serial hybrid power plants most commonly associated with urban air mobility vehicles. While closed form analytical solutions for parallel hybrid aviation cases have been determined, optimized serial hybrid power plants have not seen the same degree of fidelity. Presented here are the analytical relationships between several preliminary aircraft design objectives and the battery weight fraction. These design objectives include aircraft weight, range, operation cost, and carbon emissions. The relationships are based on a serial hybrid electric propulsion architecture from an energy standpoint, and can be applied to hybrid aircraft of different …

A Hybrid Vortex Solution For Radial Equilibrium In Axial Compressors, Wenyu Li

Doctoral Dissertations and Master's Theses

A hybrid vortex solution using the radial equilibrium equation for three dimensional design in axial compressors is generated. One of the most common used vortex solutions is Free Vortex. However, it ignores the fact that axial velocity varies with radius. The Hybrid Vortex includes axial velocity distribution with radius, which gives a more effective design. A single stage is first designed using the Free Vortex design method. A low hub-to-tip ratio is set to ensure subsonic flow. The axial velocity profile is exported from the CFX solver of the inlet diffuser. Using the Hybrid Vortex solution to the radial equilibrium …

Hypervelocity Impact Analysis Of Hybrid Nanocomposite Sensors For Inflatable Space Structures, Yachna Gola

Doctoral Dissertations and Master's Theses

Future space exploration requires easy-to-transport, and easy-to-build and deploy space habitats. NASA and Bigelow Aerospace have collaborated so that human habitation can be made safe and easy with inflatable space habitats (Litteken, 2017). One of the biggest threats faced by these structures in outer space is impact damage by micrometeoroid orbital debris (MMOD) traveling at velocities as high as 15 km/s (Lemmens, Krag, Rosebrock, & Carnelli, 2013). This work presents fabrication and testing of hybrid nanocomposites with carbon nanotubes (CNT) and coarse graphene nanoplatelets (GNP) as fillers and flexible epoxy matrix, that are proposed to be used for sensing the …

Space Image Processing And Orbit Estimation Using Small Aperture Optical Systems, David Zuehlke

Doctoral Dissertations and Master's Theses

Angles-only initial orbit determination (AIOD) methods have been used to find the orbit of satellites since the beginning of the Space Race. Given the ever increasing number of objects in orbit today, the need for accurate space situational awareness (SSA) data has never been greater. Small aperture (< 0:5m) optical systems, increasingly popular in both amateur and professional circles, provide an inexpensive source of such data. However, utilizing these types of systems requires understanding their limits. This research uses a combination of image processing techniques and orbit estimation algorithms to evaluate the limits and improve the resulting orbit solution obtained using small aperture systems. Characterization of noise from physical, electronic, and digital sources leads to a better understanding of reducing noise in the images used to provide the best solution possible. Given multiple measurements, choosing the best images for use is a non-trivial process and often results in trying all combinations. In an effort to help autonomize the process, a novel “observability metric” using only information from the captured images was shown empirically as a method of choosing the best observations. A method of identifying resident space objects (RSOs) in a single image using a gradient based search algorithm was developed and tested on actual space imagery captured with a small aperture optical system. The algorithm was shown to correctly identify candidate RSOs in a variety of observational scenarios.

Aviation Safety Action Program In The United States Air Force: Mobility Aircrews’ Intentions To Use Safety Reporting, Travis Jared Whittemore

Doctoral Dissertations and Master's Theses

No abstract provided.

The Changing Face Of Airmanship And Safety Culture Operating Unmanned Aircraft Systems, Tracy Lamb

Student Works

The notion of using drones for commercial purposes has evolved in the past 5 years from the initial “boom” of excitement around this, somewhat of a novelty and curiosity, to more calculated and sophisticated use of unmanned aircraft systems (UAS), or drones. In the hands of true professionals, drones can offer highly efficient and profitable solutions for industrial, and commercial inspections and other data capturing tasks. The appetite for safe and efficient collection of data is a changing face of safety cultures and how teams and individuals apply airmanship principles, and how inspection crew and UAS crew interact. UAS are …

Airline Quality Rating 2019, Brent D. Bowen, Dean E. Headley

Airline Quality Rating Report

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The results of the 29th annual national Airline Quality Rating (AQR). The most comprehensive study of the performance quality of the 9 largest airlines in the United States, the AQR is conducted by researchers at the W. Frank Barton School of Business at Wichita State University and Embry-Riddle Aeronautical University’s Prescott, Ariz., campus. Airline performance, as presented by AQR researchers, encompasses a multifactor look at the overall quality of the airlines. It includes on-time performance, denied boardings, mishandled baggage and customer complaints. …

Search And Rescue: The Importance Of Using Tracking Systems In Rural 135 Operations, April Larsen, Brent D. Bowen

Student Works

In January 2020, under the NextGen initiative put in place by the Federal Aviation Administration (FAA), all aircraft flying in controlled airspace, both general aviation and commercial operations, will be required to have an Automatic Dependent Surveillance – Broadcast (ADS–B) system installed and operational. However, this is not required for Title 14 Code of Federal Regulations (CFR) Part 135 operations taking place outside of controlled airspace. Part 135 of the Federal Aviation Regulations (FAR) refers to aircraft operating as on-demand or air taxi services. A substantial amount of these operator’s bases, as well as flights, are conducted outside of controlled …

Quality Analysis Of United States Commercial Air Carriers: Airline Quality Rating 2019, Kaetlyn Blocker, Brent D. Bowen, Erin Bowen, Timothy B. Holt, Dean E. Headley

Student Works

Past research regarding major U.S. commercial air carriers and consumer perceptions of airline performance has provided little more than a descriptive “snapshot” of the average air traveler. Using the most recent data and findings, as well as building on the previous 29 continuous years of research with the national Airline Quality Rating (AQR), the present study attempts to move beyond the basic descriptive information by identifying significant changes that have occurred over the previous year. Collectively, changes may influence the way consumers, at varying levels of travel frequency, view the commercial air industry. This research utilizes trend analysis methodology by …

High Consequence Safety Research And Policy: The Us Airline Application, Calissa Spooner, Tori Kobayashi, Brent D. Bowen

Student Works

The implementation of safety programs in Flight Operations has been successful since the Federal Aviation Administration formally introduced Safety Management Systems (SMS) procedures in 2000. The addition of safety programs like SMS into aviation organizations has been confirmed to improve safety culture, communication, and overall hazard mitigation. This research explores the changes and improvements that are made in maintenance programs where an SMS is formally implemented. In the United States it is legal for children under the age of twenty-four months to fly in commercial aircraft on the lap of a parent or guardian, while being unsecured or unrestrained. Throughout …

Aviation Safety, Quality, And Economic Impact: A Policy Research System, Calissa Spooner, Tori Kobayashi, Cindy Greenman, Brent D. Bowen, Kaetlyn Blocker

Student Works

The United States airline industry is experiencing an underlying mix of challenges in areas of Quality, Safety, and Economics. This research focuses on three major components and the economic impact of each. The first aspect, Airline Quality and Safety Analysis, lays down a focus on imperative safety factors that affect major airlines in overall performance. Quality and Safety findings relate to potential safety shortcomings in the second aspect, aviation maintenance Safety Management Systems (SMS). The third aspect involves implementing the Policy Research Construct (PRC) methodology, which relates the underlying challenges in Airline Quality, Safety, and Economic areas by conducting research …

Building And Integrating An Information Security Trustworthiness Framework For Aviation Systems, Anna Baron Garcia

Doctoral Dissertations and Master's Theses

The aviation infrastructure is broadly composed of aircraft, air traffic control systems, airports and public airfields. Much attention has been given to physical security along the years this industry has been expanding; and now, in the new age of interconnection devices, a growing concern about cybersecurity has risen.

The never-ending improvement of new digital technology has given birth to a new generation of electronic-enabled (e-enabled) aircraft that implement a remarkable amount of new technologies such as IP-enabled networks, COTS (commercial off-the- shelf) components, wireless connectivity, and global positioning systems (GPSs). For example, aircraft manufacturers are building wireless systems to reduce …

Fiber-Reinforced Polymer Bridge Girders For Extremely Aggressive Environments, Abdellah Emad Azeez

Doctoral Dissertations and Master's Theses

In 2012, the federal government estimated that $17.5 billion was spent on inspection, rehabilitation, maintenance, and replacement of the nation’s bridges. While the average lifespan of steel and reinforced concrete bridges is 50 years, certain bridges subjected to extremely aggressive marine environments may not reach this desired target. This research paper investigates using fiber-reinforced polymer (FRP) materials as primary bridge girders in medium span bridges (30 ft. to 75 ft.). The goal of this research is to identify the most efficient and cost-effective alternative for these corrosion-resistant materials and potentially extend the lifespan of these bridges up to 75 years. …

Uncover The Power Of Multipath : Detecting Nlos Drones Using Low-Cost Wifi Devices, Ashok Vardhan Raja

Doctoral Dissertations and Master's Theses

In recent years, consumer UAV technology has seen considerable advances. Consumer UAVs have become an ideal vector for privacy invasions due to their affordability, size, maneuverability, and their ability to stream live high-quality video. There is considerable proliferation of drones in both civil and military domains. Hence it is critical to detect invading unmanned aerial vehicles (UAVs) or drones in a timely manner for both security and safeguarding privacy. Currently available solutions like active radar, video or acoustic sensors are very expensive (especially for individuals) and have considerable constraints (e.g., requiring visual line of sight).

Recent research on drone detection …

Geometric Effects Of Thermal Barrier Coating Damage On Turbine Blade Temperatures, Shane Colon

Doctoral Dissertations and Master's Theses

Thermal barrier coatings (TBC) found on turbine blades are a key element in the performance and reliability of modern gas turbines. During the life of the turbine components, the TBC surface may be damaged due to manufacturing imperfections, handling damage, service spalling, or service impact damage, producing chips in the coating. While a chip in the TBC coating is expected to cause an increase in airfoil temperature, it is unknown to what degree the blade will be affected and what parameters of the chip shape affect this result. The goal of this preliminary study is to identify the major driving …

Global Estimation Methodology For Wave Adaptation Modular Vessel Dynamics Using A Genetic Algorithm, Marco Alan Schoener

Doctoral Dissertations and Master's Theses

Determining parameters for a system model for marine vessels becomes more difficult as the model is made more complex. Work has been done to determine the equations of motion, but not to fully define how to estimate all of the system parameters. This work utilizes a global optimization methodology for estimating the system parameters using a genetic algorithm. The optimizer uses training data sets created from a set of ship maneuvering standards to minimize the error in the 3 degree-of-freedom equations of motion. The model has been optimized using a “No Surge-Yaw” model (minimal surge coupling) and a “Full” model …

Non-Linear Bending Analysis Of Functionally Graded Beams With Spring Constraints And Thermal Effects, Swetha Suresh

Doctoral Dissertations and Master's Theses

No abstract provided.

Finite Element Model Validation And Testing Of An Off-Road Vehicle Under Dynamic Loading Conditions, Mackenzie Susan Cunningham

Doctoral Dissertations and Master's Theses

In the vehicle design life cycle, validation tests consume a significant portion of the available development time. With a short, one-year design cycle, the Embry-Riddle Baja Team leverages computer-aided engineering (CAE) tools to simulate critical test cases whose loading conditions can be accurately represented by a series of static loads and constraints. Using these conditions, a Finite Element Model (FEM) can be employed to accurately predict the effects of the loading conditions in the components. During the initial design of the front suspension, one major load case was determined to be the main failure load. However, after validation testing the …

Scale Interactions Within A Perturbed Plane Wall Jet, Shibani Bhatt

Doctoral Dissertations and Master's Theses

The current work focuses on exploiting this behavior to manipulate wall turbulence by targeting the large-scales of the flow. In wall turbulence the large-scales of the flow interact with the smaller scales in a non-linear manner including through a process of amplitude and frequency modulation. A plane wall jet (PWJ) is chosen as the model flow field for this work as its unique geometry allows for the controlled introduction of large-scale perturbations through acoustic forcing. The corresponding interactions because of forcing are characterized using single hot-wire measurements. The nearwall response of the PWJ over a range of large-scale forcing showed …

Exergetic Relationship Between The Thermal Properties Of Direct Contact Membrane Distillation, D. Perdue, L. Chen, L. Schaefer

Publications

Direct contact membrane distillation (DCMD) is a process that has shown promise within the field of desalination due to its less energy intensive methods and widespread applications. DCMD is a thermally driven microfiltration separation process that operates on the principle of vapor–liquid equilibrium conditions where heat and mass transfer occur simultaneously. Fundamentally, DCMD is based on a porous hydrophobic membrane separating the hot solution (feed) from the cold solution (permeate) where desalinated water condenses. The membrane interfacial temperatures determine the vapor pressure difference across the membrane. In this work, a direct simulation Monte Carlo analysis is employed to investigate how …

Efficacy Of The Localized Aviation Mos Program In Ceiling Flight Category Forecasts, Douglas D. Boyd, Thomas A. Guinn

Publications

(1) Background: Flying in instrument meteorological conditions (IMC) carries an elevated risk of fatal outcome for general aviation (GA) pilots. For the typical GA flight, aerodrome-specific forecasts (Terminal Aerodrome Forecast (TAF), Localized Aviation Model Output Statistics Program (LAMP)) assist the airman in pre-determining whether a flight can be safely undertaken. While LAMP forecasts are more prevalent at GA-frequented aerodromes, the Federal Aviation Administration (FAA) recommends that this tool be used as supplementary to the TAF only. Herein, the predictive accuracy of LAMP for ceiling flight categories of visual flight rules (VFR) and instrument flight rules (IFR) was determined. (2) Methods: …

Emerging Need For A European Approach To Space Traffic Management, Tomas Hrozensky

Space Traffic Management Conference

The intensification of space activities worldwide, together with the emergence of new actors and disruptive concepts (e.g. miniaturized satellites, mega-constellations, in-orbit operations), create new challenges to ensure the safety and security of space systems and operations as well as the long-term sustainability of space activities. Among policy responses to these challenges, the development of a new approach to space traffic management was recently brought to the forefront by the adoption of a policy directive in this domain by the United States.

A comparable STM policy has not yet been developed in Europe even though considerations for the safety, security and …

Satellite Conjunction Assessment Risk Analysis For “Dilution Region” Events: Issues And Operational Approaches, Matthew D. Hejduk

Space Traffic Management Conference

An important activity within Space Traffic Management is the detection and prevention of possible on-orbit collisions between space objects. The principal parameter for assessing collision likelihood is the probability of collision, which is widely accepted among conjunction assessment practitioners; but it possesses a known deficiency in that it can produce a false sense of safety when the orbital position uncertainties for the conjuncting objects are high. The probability of collision is said to be “diluted” in such a situation and to understate the possible risk; certain approaches have been recommended by researchers to provide (largely conservative) risk estimates and remediation …

End To End Satellite Servicing And Space Debris Management, Aman Chandra, Himangshu Kalita, Roberto Furfaro, Jekan Thanga

Space Traffic Management Conference

There is growing demand for satellite swarms and constellations for global positioning, remote sensing and relay communication in higher LEO orbits. This will result in many obsolete, damaged and abandoned satellites that will remain on-orbit beyond 25 years. These abandoned satellites and space debris maybe economically valuable orbital real-estate and resources that can be reused, repaired or upgraded for future use. Space traffic management is critical to repair damaged satellites, divert satellites into warehouse orbits and effectively deorbit satellites and space debris that are beyond repair and salvage. Current methods for on-orbit capture, servicing and repair require a large service …

Analogies And Comparisons For Stm Data Bodies, Phillip M. Cunio, Brien Flewelling

Space Traffic Management Conference

Space Traffic Management (STM) has already demonstrated its potential to be extremely data-intensive. The large number of objects on orbit today, if observed constantly throughout their lifetimes, could produce a staggeringly large number of observations that might in turn generate large numbers of orbits. Orbit data with a lengthy time history can be used to produce estimates of maneuver frequency, susceptibility to natural forces such as drag, and (if combined with photometric data) assessments of behavioral patterns of life.

A future of mega-constellations and a growing number of nations and organizations with assets on orbit would make it likely that …