Aerospace Engineering Commons^™

Analysis Of Cyberattacks On Unmanned Aerial Systems, Andrew Morris Shull

Open Access Theses

With the increasing power and convenience offered by the use of embedded systems in control applications, such systems will undoubtedly continue to be developed and deployed. Recently, however, a focus on data-centric systems and developing network-enabled control systems has emerged, allowing for greater performance, safety, and resource allocation in systems such as smart power grids and unmanned military aircraft. However, this increase in connectivity also introduces vulnerabilities into these systems, potentially providing access to malicious parties seeking to disrupt the operation of those systems or to cause damage. Given the high potential cost of a failure in these systems in …

Flow And Heat Transfer In An L-Shaped Cooling Passage With Ribs And Pin Fins For The Trailing Edge Of A Gas-Turbine Vane And Blade, Irsha Ashok Pardeshi

Open Access Theses

Efficient and effective cooling of the trailing edges of gas-turbine vanes and blades is challenging because there is very little space to work with. In this study, CFD simulations based on steady RANS closed by the shear-stress transport turbulence model were performed to study the flow and heat transfer in an L-shaped duct for the trailing edge under two operating conditions. One operating condition, referred to as the laboratory condition, where experimental measurements were made, has a Reynolds number at the duct inlet of Re_D = 15,000, coolant inlet temperature of T_inlet = 300 K, wall temperature of …

Chemical Consequences Of Chicxulub Impact Ejecta Reentry, Devon Donald Parkos

Open Access Theses

The Chicxulub impact 66.0 million years ago initiated the second biggest extinction in the Phanerozoic Eon. The global reentry of material ejected by the impact generated a strong pulse of thermal radiation that wiped out much of the terrestrial biota. The cause of the marine extinction, however, has remained elusive. This report shows that reentering ejecta produces enough NOx to acidify the upper ocean and cause a massive marine extinction. Using non-equilibrium chemically reacting flow simulations coupled with atmospheric transport modeling, it is determined that enough NOx reached the stratosphere and precipitated to overpower the carbonate buffer and acidify the …

Evaluation Of Vertical Profiles To Design Continuous Descent Approach Procedure, Pradeep Priyank

Open Access Theses

The current research focuses on predictability, variability and operational feasibility aspect of Continuous Descent Approach (CDA), which is among the key concepts of the Next Generation Air Transportation System (NextGen). The idle-thrust CDA is a fuel economical, noise and emission abatement procedure, but requires increased separation to accommodate for variability and uncertainties in vertical and speed profiles of arriving aircraft. Although a considerable amount of researches have been devoted to the estimation of potential benefits of the CDA, only few have attempted to explain the predictability, variability and operational feasibility aspect of CDA. The analytical equations derived using flight dynamics …

Development Of A Counter Rotating Vortex Pair (Cvp) Mixer For Aerospace Applications, Jeongmoon Park

Open Access Theses

Swirling motions induced by a counter-rotating vortex pair (CVP) provides a mechanism to entrain fluid from the periphery of this structure and mix surrounding fluids with those within the vortex structure. Eventually, the vortices act upon each other transporting molecularly mixed fluid into the core flow. This mechanism has potential to increase efficiency with more complete mixing. Therefore, a mixer is proposed which directly induces counter rotating vortices by a three dimensional geometry. The proposed swirl mixer is designed to induce counter rotating vortices based on the potential flow theory, Milne-Thomson's Circle Theorem and Rankine vortex. Twelve test models are …

A Mechanism Design Approach To Bandwidth Allocation In Tactical Data Networks, Ankur Mour

Open Access Theses

The defense sector is undergoing a phase of rapid technological advancement, in the pursuit of its goal of information superiority. This goal depends on a large network of complex interconnected systems - sensors, weapons, soldiers - linked through a maze of heterogeneous networks. The sheer scale and size of these networks prompt behaviors that go beyond conglomerations of systems or `system-of-systems'. The lack of a central locus and disjointed, competing interests among large clusters of systems makes this characteristic of an Ultra Large Scale (ULS) system. These traits of ULS systems challenge and undermine the fundamental assumptions of today's software …

Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku

Open Access Dissertations

The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty given by the probability density function (PDF). As even collision events with very low probability are important, accurate prediction of collisions require the representation of the full PDF of the random orbit state. Through representing the full PDF …

Gaseous Corrosion In Hard Disk Drive: A Computational Study, Hardik Shah

Mechanical and Aerospace Engineering Theses - Archive

HDD is the largest digitally encoded data storage device. HDD is used to store digital data in data centers, computers and laptops. A typical HDD consists of a casing, an actuator arm, actuator axis, head, platters, power connectors, and jumper pins. The platter is made up of non-magnetic material and is covered by magnetic material, which stores the data. The magnetic heads are mounted on a moving actuator arm to read and write the data. One of the modes of failure of a HDD is corrosion. The parts of the HDD are corroded by coming in contact with the contaminants. …

Optimal Thickness Distributions Of Aeroelastic Flapping Shells, Bret Stanford, Philip Beran

United States Air Force: Publications

The severe weight limitations of flapping wing micro air vehicles necessitates the use of thin flexible wings, which in turn requires an aeroelastic modeling tool for proper numerical characterization. Furthermore, due to the unconventional nature of these vehicles, wing design guidelines for thrust and/or power considerations are not generally available; numerical design optimization then becomes a valuable tool. This work couples a nonlinear shell model to an unsteady vortex lattice solver, and then computes analytical design gradients: the derivative of aerodynamic force/power quantities with respect to a large vector of thickness variables. Gradient-based optimization is then used to locate the …

Direct Ignition And S-Curve Transition By In Situ Nano-Second Pulsed Discharge In Methane/Oxygen/Helium Counterflow Flame, Wenting Sun, Sang Hee Won, Timothy Ombrello, Campbell Carter, Yiguang Ju

United States Air Force: Publications

A well-defined plasma assisted combustion system with novel in situ discharge in a counterflow diffusion flame was developed to study the direct coupling kinetic effect of non-equilibrium plasma on flame ignition and extinction. A uniform discharge was generated between the burner nozzles by placing porous metal electrodes at the nozzle exits. The ignition and extinction characteristics of CH4/O2/He diffusion flames were investigated by measuring excited OH* and OH PLIF, at constant strain rates and O2 mole fraction on the oxidizer side while changing the fuel mole fraction. It was found that ignition and extinction occurred with an abrupt change of …

Damage Characterization And Analytical Modeling Of Quasi-Statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru, Abhendra K. Singh

Mechanical and Aerospace Engineering - Dissertations

The research conducted for this dissertation focused on understanding the nature and extent of barely visible impact damage (BVID) in composite sandwich structures. This was part of a larger research effort that included studies on the influence of BVID on the compressive strengths and failure modes of composite sandwich structures. In this dissertation, the nature and extent of BVID is studied in aluminum honeycomb core sandwich panels with eight and sixteen ply, quasi-isotropic, graphite/epoxy face sheets. The damage in the sandwich structure is created quasi-statically using spherical indentors of two different sizes. Apart from the face sheet thickness and indentor …

Non-Equilibrium Pressure Control Of The Height Of A Large-Scale, Ground-Coupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan

Mechanical & Aerospace Engineering Faculty Publications

When a ground-coupled, rotating fluid column is modeled incorporating non-equilibrium pressure forces in the Navier-Stokes equations, a new exact solution results. The solution has been obtained in a similar manner to the classical equilibrium solution. Unlike the infinite-height, classical solution, the non-equilibrium pressure solution yields a ground-coupled rotating fluid column of finite height. A viscous, non-equilibrium Rankine vortex velocity distribution, developed previously, was used to demonstrate how the viscous and non-equilibrium pressure gradient forces, arising in the vicinity of the velocity gradient discontinuity that is present in the classical Rankine vortex model, effectively isolate the rotating central fluid column from …

Modelling And Configuration Control Of Wing-Shaped Bi-Stable Piezoelectric Composites Under Aerodynamic Loads, Andres F. Arrieta, Onur Bilgen, Michael I. Friswell, Paolo Ermanni

Mechanical & Aerospace Engineering Faculty Publications

Bi-stable composites have been considered for morphing applications thanks to their ability to hold two statically stable shapes with no energy consumption. In this paper, the modelling of the dynamic response of cantilevered wing-shaped bi-stable composites is presented. To this end, an analytical model approximating the dynamic response about each statically stable shape of wing-shaped bi-stable composites is derived. Theoretical modal properties are obtained to attain or stabilise a desired configuration following a previously introduced resonant control strategy. The resonant control technique is evaluated for a wing-shaped bi-stable composite subject to aerodynamic loads. Wind tunnel experiments are conducted on a …

Proceedings Of The First International Conference On Smarandache Multispace & Multistructures, Florentin Smarandache, Linfan Mao

Branch Mathematics and Statistics Faculty and Staff Publications

In recent decades, Smarandache’s notions of multispace and multistructure were widely spread and have shown much importance in sciences around the world. Organizedby Prof.Linfan Mao, a professional conference on multispaces and multistructures, named the First International Conference on Smarandache Multispace and Multistructure was held in Beijing University of Civil Engineering and Architecture of P. R. China on June 28-30, 2013, which was announced by American Mathematical Society in advance.

Bio-Inspired Cooperative Optimal Trajectory Planning For Autonomous Vehicles, Charles Remeikas

Electronic Theses and Dissertations

With the recent trend for systems to be more and more autonomous, there is a growing need for cooperative trajectory planning. Applications that can be considered as cooperative systems such as surveying, formation flight, and traffic control need a method that can rapidly produce trajectories while considering all of the constraints on the system. Currently most of the existing methods to handle cooperative control are based around either simple dynamics and/or on the assumption that all vehicles have homogeneous properties. In reality, typical autonomous systems will have heterogeneous, nonlinear dynamics while also being subject to extreme constraints on certain state …

Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application, Chao Ji

Mechanical and Aerospace Engineering Theses - Archive

Lithium-ion batteries are currently widely used in electronics, electrical vehicles and other devices/machines. Along with the mounting demand for much improved performance in these developing technological fields, silicon was recognized to possess much higher energy capacity when used as an anode than graphite that is currently used. However, there occurs colossal volume expansion of silicon anode during the lithiation process. The material consequently suffers enormous stresses, especially, at the interface with a current collector, which deteriorate the device quickly during cycling. To prevent the active material (Si) from falling off from a current collector, nanoengineering strategies have been suggested, including …

Application Of Phase Change Material In Sustainable Cooling Of Data Centers, Nikhil Dhiman

Mechanical and Aerospace Engineering Theses - Archive

The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. In recent years, more effort is being made on the development of a new technique to use the phase change materials as pump-able heat transfer fluid and as heat storage system.Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a …

Thermal Management Method For Foil Bearings In Turbine Hot Section, Tejas Devidas Patil

Mechanical and Aerospace Engineering Theses - Archive

Recently, Air Foil Bearings (AFB) are gaining higher industrial acceptance in micro-turbo machinery. AFB show high speed operating capability and environmental friendly operation in comparison to rolling element bearings. Utilization of ambient air as a lubricant eliminates maintenance of a pressurized oil lubricating system. AFBs are therefore a feasible alternative to oil lubricated bearings in small machines. High speed operation results in thermal management issues which can be solved through a suitable cooling mechanism. Axial cooling by passing air through bearing support structure (called bump foils) is the most commonly used. In this method, cooling is achieved in the heat …

Immersion Cooling Of High End Data Center Server And Validation Through Experiments, Harsh Patel

Mechanical and Aerospace Engineering Theses - Archive

Despite recent improvements in data center cooling efficiency such as hot and cold aisle and air side economizer, air cooling may not have the capacity to cool high end racks such as from IBM's NetBAY42 (150Kw and above). Increasing computer capabilities in data center has resulted in increase in rack power density per square ft as indicated by the latest uptime. The cooling of such high powered servers and corresponding racks poses a significant challenge to thermal engineers.The use of immersion cooling is novel approach for data center cooling. In this study after some modification high powered server is fully …

Vision-Based Sensing And Optimal Control For Low-Cost And Small Satellite Platforms, Bradley Sease

Electronic Theses and Dissertations

Current trends in spacecraft are leading to smaller, more inexpensive options whenever possible. This shift has been primarily pursued for the opportunity to open a new frontier for technologies with a small financial obligation. Limited power, processing, pointing, and communication capabilities are all common issues which must be considered when miniaturizing systems and implementing low-cost components. This thesis addresses some of these concerns by applying two methods, in attitude estimation and control. Additionally, these methods are not restricted to only small, inexpensive satellites, but offer a benefit to large-scale spacecraft as well. First, star cameras are examined for the tendency …

Mission Analysis For Pico-Scale Satellite Based Dust Detection In Low Earth Orbits, Jacob Belli

Electronic Theses and Dissertations

A conceptual dust detection mission, KnightSat III, using pico-scale satellites is analyzed. The purpose of the proposed KnightSat III mission is to aid in the determination of the size, mass, distribution, and number of dust particles in low earth orbits through a low cost and flexible satellite or a formation of satellites equipped with a new dust detector. The analysis of a single satellite mission with an on-board dust detector is described; though this analysis can easily be extended to a formation of pico-scale satellites. Many design aspects of the mission are discussed, including orbit analysis, power management, attitude determination …

A Numerical Study Of Incompressible Fluid Flow Over A Forward Facing Step At Various Grades, Peter Andrew Martinez

Mechanical and Aerospace Engineering Theses - Archive

The study of the effect of natural forces on hydraulic structures is of great concern for the accurate prediction of when a design could be at risk of failure. In recent times the use of the shallow water equations to predict the behavior of the free surface for flow over a step has proven inaccurate because only a hydrostatic pressure distribution is considered. One of the phenomena that will not be accounted for with the shallow water equations in such a setup is the formulation of undular bore type waves on the surface. In order for a more accurate representation …

Design, Fabrication And Test Of Surface Tension-Driven Microboats And Thermally Oscillatory Bubble-Propelled Microsubmarines, Lei Qiao

Mechanical and Aerospace Engineering Dissertations - Archive

In this work, we develop microboats and microsubmarines, which are capable of moving on and under water, respectively. The microboat is propelled due to the difference between surface tensions around stern and bow. This difference is generated by releasing a liquid with lower surface tension than water from the stern. We explore both horizontal and vertical motions of the microboats through a combination of experimental and theoretical investigations. It has a length of 8 mm and weight of 20 mg with the highest speed of 25 cm/s and travel distance of 85 cm. Moreover, we design, fabricate and test microboats …

Experimental Characterization Of Roughness And Flow Injection Effects In A High Reynolds Number Turbulent Channel, Mark A. Miller

Theses and Dissertations--Mechanical and Aerospace Engineering

A turbulent channel flow was used to study the scaling of the combined effects of roughness and flow injection on the mean flow and turbulence statistics of turbulent plane Poiseuille flow. It was found that the additional momentum injected through the rough surface acted primarily to enhance the roughness effects and, with respect to the mean flow, blowing produced similar mean flow effects as increasing the roughness height. This was not found to hold for the turbulence statistics, as a departure from Townsend’s hypothesis was seen. Instead, the resulting outer-scaled streamwise Reynolds stress for cases with roughness and blowing deviated …

Near Wall Shear Stress Modification Using An Active Piezoelectric Nanowire Surface, Christopher R. Guskey

Theses and Dissertations--Mechanical and Aerospace Engineering

An experimental study was conducted to explore the possible application of dynamically actuated nanowires to effectively disturb the wall layer in fully developed, turbulent channel flow. Actuated nanowires have the potential to be used for the mixing and filtering of chemicals, enhancing convective heat transfer and reducing drag. The first experimental evidence is presented suggesting it is possible to manipulate and subsequently control turbulent flow structures with active nanowires. An array of rigid, ultra-long (40 μm) TiO₂ nanowires was fabricated and installed in the bounding wall of turbulent channel flow then oscillated using an attached piezoelectric actuator. Flow velocity …

Numerical Modeling And Characterization Of Vertically Aligned Carbon Nanotube Arrays, Johnson Joseph

Theses and Dissertations--Mechanical and Aerospace Engineering

Since their discoveries, carbon nanotubes have been widely studied, but mostly in the forms of 1D individual carbon nanotube (CNT). From practical application point of view, it is highly desirable to produce carbon nanotubes in large scales. This has resulted in a new class of carbon nanotube material, called the vertically aligned carbon nanotube arrays (VA-CNTs). To date, our ability to design and model this complex material is still limited. The classical molecular mechanics methods used to model individual CNTs are not applicable to the modeling of VA-CNT structures due to the significant computational efforts required. This research is to …

Wind Loading On Trees Integrated With A Building Envelope, Aly Mousaad Aly, Alberto Zasso, Girma Bitsuamlak, Alberto Nicola Longarini, Arindam Gam Chowdhury

Faculty Publications

With the sustainability movement, vegetated building envelopes are gaining more popularity. This requires special wind effect investigations, both from sustainability and resiliency perspectives. The current paper focuses on wind load estimation on small- and full-scale trees used as part of green roofs and balconies. Small-scale wind load assessment was carried out using wind tunnel testing in a global-effect study to understand the interference effects from surrounding structures. Full-scale trees were investigated at a large open-jet facility in a local-effect study to investigate the wind-tree interaction. The effect of Reynolds number combined with shape change on the overall loads measured at …

The Potential Costs To The Dod Of Not Preparing For The Nextgen Nas Overhaul: Lessons Learned From Rvsm, Casey Richardson

Graduate Student Works

In order to facilitate a significant overhaul of the civilian National Airspace System (NAS), the Federal Aviation Administration (FAA) has partnered with many federal agencies, such as the departments of Transportation (DOT), Defense (DoD), Homeland Security (DHS), and Commerce (DOC) and the National Aeronautics & Space Administration (NASA) through a consolidated Joint Planning and Development Office (JPDO) that was established by Congress in 2003 in the VISION 100 – Century of Aviation Reauthorization Act (JPDO, 2012). The JPDO has proposed replacing the old NAS structure of primarily ground-based navigation with robust satellite-enabled air traffic procedures and to supplement ground-based air …

Observability-Enhanced Dual-Filter Design For Attitude Estimation With Minimum Observations, Jason D. Searcy

Doctoral Dissertations

"Determining spacecraft attitude in real time using only magnetometer data presents a challenging filtering problem. A flexible and computationally efficient method for solving the spacecraft attitude using only an inexpensive and reliable magnetometer would be a useful option for satellite missions, particularly those with modest budgets. The primary challenge is that magnetometers only instantaneously resolve two axes of the spacecraft attitude. Typically, magnetometers are used in conjunction with other sensors to resolve all three axes. However, by using a filter over an adequately long orbit arc, the magnetometer data can yield full attitude, and in near real time. The method …

Indeterminate Masses, Elements And Models In Information Fusion, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper at the beginning, we make a short history of the logics, from the classical Boolean logic to the most general logic of today neutrosophic logic. We define the general logic space and give the definition of the neutrosophic logic. Then we introduce the indeterminate models in information fusion, which are due either to the existence of some indeterminate elements in the fusion space or to some indeterminate masses.

The best approach for dealing with such models is the neutrosophic logic, which is part of neutrosophy. Neutrosophic logic is connected with neutrosophic set and neutrosophic probability and statistics.