Analysis Of Cyberattacks On Unmanned Aerial Systems,
2013
Purdue University
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,
2013
Purdue University
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 ReD = 15,000, coolant inlet temperature of Tinlet = 300 K, wall temperature of …
Chemical Consequences Of Chicxulub Impact Ejecta Reentry,
2013
Purdue University
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,
2013
Purdue University
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,
2013
Purdue University
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,
2013
Purdue University
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,
2013
Purdue University
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,
2013
University of Texas at Arlington
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,
2013
Wright–Patterson AFB
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,
2013
Princeton University
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,
2013
Syracuse University
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,
2013
Old Dominion University
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,
2013
Old Dominion University
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 …
Manual Modification And Plasma Exposure Of Boron Nitride Ceramic To Study Hall Effect Thruster Plasma Channel Material Erosion,
2013
Missouri University of Science and Technology
Manual Modification And Plasma Exposure Of Boron Nitride Ceramic To Study Hall Effect Thruster Plasma Channel Material Erosion, Alexander J. Satonik
Masters Theses
"Worn Hall effect thrusters (HET) show a variety of unique microstructures and elemental compositions in the boron nitride thruster channel walls. Worn thruster channels are typically created by running test thrusters in vacuum chambers for hundreds of hours. Studies were undertaken to manually modify samples of boron nitride without the use of a hall effect thruster. Samples were manually abraded with an abrasive blaster and sandpaper, in addition to a vacuum heater. Some of these samples were further exposed to a xenon plasma in a magnetron sputter device. Sandpaper and abrasive blaster tests were used to modify surface roughness values …
A Computational Study Of Driven Micro-Cavities In Supersonic Flat Plate Flow,
2013
Missouri University of Science and Technology
A Computational Study Of Driven Micro-Cavities In Supersonic Flat Plate Flow, Thomas Ryan Rehmeier
Masters Theses
"Driven micro-cavities embedded in the wall beneath turbulent supersonic boundary layers are analyzed using two-dimensional computational fluid dynamics. This concept is a passive flow control technique in which very small cavities formed by arrays of thin vertical walls are oriented transverse to the flow direction and underlie the boundary layer. The purpose is to reduce or eliminate skin friction drag. Various micro-cavity configurations were analyzed at locations (0.1 m and 1 m) downstream of the leading edges of flat plates, for free-stream Mach numbers of 1.2, 2.0, and 3.0. Results focus on net drag reduction achieved, cavity flow-field effects, perforation …
Modeling Of Fracture And Durability Of Paste-Bonded Composite Joints Subjected To Hygro-Thermal-Mechanical Loading,
2013
Missouri University of Science and Technology
Modeling Of Fracture And Durability Of Paste-Bonded Composite Joints Subjected To Hygro-Thermal-Mechanical Loading, David Lee Harris
Masters Theses
"The objective of the research is to characterize the behavior of composite/composite joints with paste adhesive using both experimental testing and analytical modeling. In comparison with the conventional tape adhesive, joining composites using paste adhesive provides several advantages. The carbon fiber laminate material systems employed in this study included IM7 carbon fibers and 977-3 epoxy matrix assembled in prepreg tape, and AS4 carbon fibers and 977-3 epoxy matrix as a five-harness satin weave. The adhesive employed was EA 9394 epoxy. All laminates and test specimens were fabricated and inspected by Boeing using their standard propriety procedures. Three types of test …
Libration Point Orbits Near Small Bodies In The Elliptic Restricted Three-Body Problem,
2013
Missouri University of Science and Technology
Libration Point Orbits Near Small Bodies In The Elliptic Restricted Three-Body Problem, Bharat Mahajan
Masters Theses
"In this study, the feasibility of using libration point orbits to explore small solar system bodies, including asteroids and comets, is considered. A novel design for a small body mission is proposed that makes use of libration point orbits as "parking" orbits. In considering a human exploration mission to asteroids or comets, these "parking" orbits may provide benefits including a safe vantage point for staging/observation, reduced perturbation effects from the nonuniform gravitational field of the body, fewer communication blackouts, ease of guidance and control of a lander on the surface, etc. Because small solar system bodies have extremely low mass …
Effects Of Machining Parameters And Cooling Strategies On Cutting Forces And Surface Integrity In High-Speed Slot End-Milling Of Titanium Alloy,
2013
Missouri University of Science and Technology
Effects Of Machining Parameters And Cooling Strategies On Cutting Forces And Surface Integrity In High-Speed Slot End-Milling Of Titanium Alloy, Emenike Chukwuma
Masters Theses
“Paper 1 presents the results of the investigations of the effects of cooling strategies [Emulsion cooling, Minimum Quantity Lubrication (MQL) and Liquid Nitrogen (LN2)] and machining parameters (feed rate and spindle speed) on cutting force components, cutting temperature and tool wear during slot end-milling of titanium Ti-6Al-4V workpiece. All machining experiments were conducted using four-flute 0.5 inch diameter uncoated solid carbide end-mill on Cincinnati Milacron, Sabre 750 vertical machining center equipped with Acramatic 2100 controller. Cutting force components were acquired and tool wear was indirectly measured from maximum cutting force variation per slot from the first pass to …
Proceedings Of The First International Conference On Smarandache Multispace & Multistructures,
2013
University of New Mexico
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,
2013
University of Central Florida
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 …
