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Articles 8671 - 8700 of 11198
Full-Text Articles in Aerospace Engineering
Using Agent-Based Modeling To Evaluate Uas Behaviors In A Target-Rich Environment, Joseph A. Van Kuiken
Using Agent-Based Modeling To Evaluate Uas Behaviors In A Target-Rich Environment, Joseph A. Van Kuiken
Theses and Dissertations
The trade-off between accuracy and speed is a re-occurring dilemma in many facets of military performance evaluation. This is an especially important issue in the world of ISR. One of the most progressive areas of ISR capabilities has been the utilization of Unmanned Aircraft Systems (UAS). Many people believe that the future of UAS lies in smaller vehicles flying in swarms. We use the agent-based System Effectiveness and Analysis Simulation (SEAS) to create a simulation environment where different configurations of UAS vehicles can process targets and provide output that allows us to gain insight into the benefits and drawbacks of …
Creep And Fatigue Interaction Characteristics Of Pwa1484, Christian J. Pierce
Creep And Fatigue Interaction Characteristics Of Pwa1484, Christian J. Pierce
Theses and Dissertations
One of the main methods for predicting the service life of jet engine turbine blades is through creep analysis. A sample of the turbine blade material will be mechanically tested to characterize its creep performance. This characterization will be used to determine safe operating conditions for the material. While methods for modeling creep behavior are generally well developed, this constant load creep testing does not fully represent the loading conditions present in a jet engine due to cyclic loading caused by the mission profile and throttle movements. As the industry seeks to become more accurate in physics based modeling of …
Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez
Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez
Theses and Dissertations
Existing nanocomposite materials used for satellite applications don't offer the required conductivity and electromagnetic shielding protection, requiring metal shields in order to survive in space. The AFRL Materials and Manufacturing Directorate in conjunction with the private sector have developed a material that promises to blend the attributes of nanocomposites and metal materials. The M55J/RS3 material consists of carbon fibers combined with a polyisocyanate matrix, in which Nickel nanostrandsTM are added. The research effort investigated the changes in the EMI and ESD of the material after being subjected to cyclic loads. Four configurations of a symmetric layup with fibers oriented …
Architecting Human Operator Trust In Automation To Improve System Effectiveness In Multiple Unmanned Aerial Vehicles (Uav), Eric A. Cring, Adam G. Lenfestey
Architecting Human Operator Trust In Automation To Improve System Effectiveness In Multiple Unmanned Aerial Vehicles (Uav), Eric A. Cring, Adam G. Lenfestey
Theses and Dissertations
Current Unmanned Aerial System (UAS) designs require multiple operators for each vehicle, partly due to imperfect automation matched with the complex operational environment. This study examines the effectiveness of future UAS automation by explicitly addressing the human/machine trust relationship during system architecting. A pedigreed engineering model of trust between human and machine was developed and applied to a laboratory-developed micro-UAS for Special Operations. This unprecedented investigation answered three primary questions. Can previous research be used to create a useful trust model for systems engineering? How can trust be considered explicitly within the DoD Architecture Framework? Can the utility of architecting …
Tunable Diode Laser Absorption Spectroscopy Verification Analysis For Use In The Combustion Optimization And Analysis Laser Laboratory, Christina R. Serianne
Tunable Diode Laser Absorption Spectroscopy Verification Analysis For Use In The Combustion Optimization And Analysis Laser Laboratory, Christina R. Serianne
Theses and Dissertations
The AFIT Combustion Optimization and Analysis Laser (COAL) laboratory has state-of-the-art laser diagnostic capability for combustion process. The research for this thesis served to enhance the COAL lab's capability. Currently, there are no known commercially available tunable diode lasers that produce Ultra-Violet radiation required for this analysis. Sum-frequency generation at 313.5 nm was utilized for high speed OH absorption and temperature measurements at a rate of 2kHz. The Tunable Diode Laser Absorption Spectroscopy system was validated by comparison with theoretical and well characterized experimental data by operating the system over a wide range of conditions for an H2 laminar flame …
Predicting Solar Protons: A Statistical Approach, Jonathan C. Spaulding
Predicting Solar Protons: A Statistical Approach, Jonathan C. Spaulding
Theses and Dissertations
A small fraction of solar flares are accompanied by high energy (>10 MeV) protons. These events can cause degradation or failure of satellite systems and can be harmful to humans in space or in high altitude flight. For risk management purposes, the Air Force is interested in predicting these events. Several algorithms exist to do this operationally, but none predict when these events will occur with much accuracy. Here, we analyzed 3610 M1 and greater flares including 106 with proton events from the GOES sensors from 1 Jan 1986 to 31 Dec 2004 to produce new results, including a …
Characterizing The Exhaust Plume Of The Three-Electrode Micro Pulsed Plasma Thrusters, Myeongkyo Seo
Characterizing The Exhaust Plume Of The Three-Electrode Micro Pulsed Plasma Thrusters, Myeongkyo Seo
Theses and Dissertations
Three-electrode micro-PPTs are a new version of two electrode micro-PPTs devices. Performance predictions and contamination expectations are essential characteristics needed by satellite designers. In order to focus on thruster specific impulse, thrust and efficiency, measuring the exhaust velocity or impulse bit and propellant consumption rate is essential. While this is not always possible to measure directly, focusing on the ejected mass from the PPT provides significant information allowing determination of these performance statistics. Specifically, focusing on exhaust angle distribution and velocity of the exhaust particles is the emphasis of this work. The results show that the three-electrode micro-PPT is more …
Effects Of Prior Aging At 316°C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 316°C: Experiment And Modeling, Ozgur Ozmen
Theses and Dissertations
The inelastic deformation behavior of PMR-15 neat resin, a high-temperature polymer, was investigated at 316°C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain at zero stress and creep response are strongly affected by prior strain …
An Analysis Of Multiple Configurations Of Next-Generation Cathodes In A Low Power Hall Thruster, John E. Rotter
An Analysis Of Multiple Configurations Of Next-Generation Cathodes In A Low Power Hall Thruster, John E. Rotter
Theses and Dissertations
The research presented here is an effort to integrate an existing hollow cathode design with a low power production Hall thruster in multiple geometries. Both externally- and internally-mounted cathodes were fabricated and operated in conjunction with a Busek BHT-1500 Hall thruster. Three insert materials were evaluated; Cerium Hexaboride (CeB6), Lanthanum Hexaboride (LaB6), and impregnated tungsten. The thruster was operated at a single operating condition for all testing. The operating specifications for the discharge were 300 V and 2.25 A, giving a total power of 675 W. The boride-based cathodes were tested in both geometries while the tungsten-based cathode was only …
An Investigation Into The Feasibility Of Using A Modern Gravity Gradient Instrument For Passive Aircraft Navigation And Terrain Avoidance, Marshall M. Rogers
An Investigation Into The Feasibility Of Using A Modern Gravity Gradient Instrument For Passive Aircraft Navigation And Terrain Avoidance, Marshall M. Rogers
Theses and Dissertations
Recently, Gravity Gradient Instruments (GGIs) - devices which measure the spatial derivatives of gravity, have improved remarkably due to development of accelerometer technologies. Specialized GGIs are currently flown on aircraft for geological purposes in the mining industries. As such, gravity gradient data is recorded in flight and detailed gradient maps are created after post mission processing. These maps, if stored in a database onboard an aircraft and combined with a GGI, form the basis for a covert navigation system using a map matching process. This system is completely passive and essentially unjammable. To determine feasibility of this method, a GGI …
Wind Tunnel Analysis And Flight Test Of A Wing Fence On A T-38, Michael D. Williams
Wind Tunnel Analysis And Flight Test Of A Wing Fence On A T-38, Michael D. Williams
Theses and Dissertations
A low-speed wind tunnel study and flight tests were performed to examine the effects of a wing fence on the T-38A. Wind tunnel results were based upon force and moment data collected with a six-component balance and flow visualization at Reynolds numbers up to 0.3 x 106, based on mean aerodynamic chord. The model did not include the last 7.79 feet of the aircraft, and the engine and exhaust were modeled as through-holes. Five fence geometries, placed at wing station 125 (± 0.825 semispan), were compared. The best performer of these designs, based on drag polar, was the …
Boundary Avoidance Tracking: Consequences (And Uses) Of Imposed Boundaries On Pilot-Aircraft Performance, Ryan D. Blake
Boundary Avoidance Tracking: Consequences (And Uses) Of Imposed Boundaries On Pilot-Aircraft Performance, Ryan D. Blake
Theses and Dissertations
This thesis presents the results of research into the Boundary Avoidance Tracking (BAT) theory, which states that often pilots control an aircraft not in an attempt to maintain some condition, but to avoid some real or perceived boundaries. This pilot modeling concept was studied using over 30 pilots in simulator and flight tests. The pilot-aircraft system was evaluated with 3 different lateral-directional control models. Pilots were given a roll angle tracking task in the presence of shrinking boundaries. Pilots were also given a secondary task in some of the profiles in order to measure workload. Approximately 42 hours of simulation …
Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan
Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan
Theses and Dissertations
Micro Air Vehicles (MAV) are a subset of Unmanned Aircraft (UAS) that are up to two orders of magnitude smaller than manned systems. Near-Earth environments, such as forests, caves, tunnels and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Therefore, MAVs are considered ideal for these types of missions. However, the data using full size aircraft is inadequate to characterize miniature aircraft parameters due to the lower Reynolds numbers and low aspect ratio (LAR) wings and impact of wing-propeller interactions. The main objectives of this research were to: collect and synthesize the available data/tools; create …
Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver
Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver
Theses and Dissertations
This research effort seeks to characterize a vision-aided approach for an Unmanned Aerial System (UAS) to autonomously determine relative position to another aircraft in a formation, specifically to address the autonomous aerial refueling problem. A system consisting of a monocular digital camera coupled with inertial sensors onboard the UAS is analyzed for feasibility of using this vision-aided approach. A three-dimensional rendering of the tanker aircraft is used to generate predicted images of the tanker as seen by the receiver aircraft. A rigorous error model is developed to model the relative dynamics between an INS-equipped receiver and the tanker aircraft. A …
A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston
A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston
Theses and Dissertations
This research analyzes the use of modern Real Time Locating Systems (RTLS), such as the Global Positioning System (GPS), to improve the safety of aircraft, equipment, and personnel onboard a United States Navy (USN) aircraft carrier. The results of a detailed analysis of USN safety records since 1980 show that mishaps which could potentially be prevented by a persistent monitoring system result in the death of a sailor nearly every other year and account for at least $92,486,469, or 5.55% of the total cost of all flight deck and hangar bay related mishaps. A system to continually monitor flight deck …
Cubesats, Any Applications?, Robert J. Twiggs
Cubesats, Any Applications?, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs titled "CubeSats, Any Applications?" from March 3, 2009.
Molecular Dynamics Study Of Crystal Plasticity During Nanoindentation In Ni Nanowires, V. Dupont, F. Sansoz
Molecular Dynamics Study Of Crystal Plasticity During Nanoindentation In Ni Nanowires, V. Dupont, F. Sansoz
Aerospace Engineering - Daytona Beach
Molecular dynamics simulations were performed to gain fundamental insight into crystal plasticity, and its size effects in nanowires deformed by spherical indentation. This work focused on-oriented single-crystal, defect-free Ni nanowires of cylindrical shape with diameters of 12 and 30 nm. The indentation of thin films was also comparatively studied to characterize the influence of free surfaces in the emission and absorption of lattice dislocations in single-crystal Ni. All of the simulations were conducted at 300 K by using a virtual spherical indenter of 18 nm in diameter with a displacement rate of1 ms1. No significant effect of sample size was …
Miniaturization Techniques To Realize Very Small Satellites, Robert J. Twiggs
Miniaturization Techniques To Realize Very Small Satellites, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs titled "Miniaturization techniques to realize very small satellites" from April 1, 2009.
Fun & Games With Space Projects, Robert J. Twiggs
Fun & Games With Space Projects, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs titled "Fun & Games with Space Projects" from February 27, 2009.
Communication Free Robot Swarming, Zachary C. Gray
Communication Free Robot Swarming, Zachary C. Gray
Theses and Dissertations
As the military use of unmanned aerial vehicles increases, a growing need for novel strategies to control these systems exists. One such method for controlling many unmanned aerial vehicles simultaneously is the through the use of swarm algorithms. This research explores a swarm robotic algorithm developed by Kadrovach implemented on Pioneer Robots in a real-world environment. An adaptation of his visual sensor is implemented using stereo vision as the primary method of sensing the environment. The swarm members are prohibited from explicitly communicating other than passively through the environment. The resulting implementation produces a communication free swarming algorithm. The algorithm …
Automated Knowledge Generation With Persistent Surveillance Video, Daniel T. Schmitt
Automated Knowledge Generation With Persistent Surveillance Video, Daniel T. Schmitt
Theses and Dissertations
The Air Force has increasingly invested in persistent surveillance platforms gathering a large amount of surveillance video. Ordinarily, intelligence analysts watch the video to determine if suspicious activities are occurring. This approach to video analysis can be a very time and manpower intensive process. Instead, this thesis proposes that by using tracks generated from persistent video, we can build a model to detect events for an intelligence analyst. The event that we chose to detect was a suspicious surveillance activity known as a casing event. To test our model we used Global Positioning System (GPS) tracks generated from vehicles driving …
Space In Education, Robert J. Twiggs
Space In Education, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs titled "Space in Education" from February 20, 2009.
Space Program For Kentucky, Robert J. Twiggs
Space Program For Kentucky, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs titled "Space Program for Kentucky" from February 15, 2009.
On The Inside Of Spaceshipone, Dan Linehan
On The Inside Of Spaceshipone, Dan Linehan
ERAU Prescott Aviation History Program
Hear the inside story of the development, testing and flight of the world’s first privately built and piloted manned spacecraft by the author of “SpaceShip One” An Illustrated History”. Exciting photos, videos and animations will help explain how and why all this took place.
A System For Measuring The Lift And Drag Forces Of A Spinning Golf Ball Held Fixed Within A Wind Tunnel, Ryan R. Miller
A System For Measuring The Lift And Drag Forces Of A Spinning Golf Ball Held Fixed Within A Wind Tunnel, Ryan R. Miller
Master's Theses
A system was designed, built and tested in order to test the aerodynamic properties of a standard golf ball in a wind tunnel manufactured by ELD, Inc. model 406(B). The system consists of a rotating shaft, on which the golf ball is attached, connected to a two-axis force transducer. Additionally, an automated data acquisition system was built for enhanced precision of measurements. Data for wind speeds up to 160 ft/s and rotational speeds up to 8,600 rpm were obtained and analyzed. The purpose of the designed apparatus was to allow for studies to better understand the lift and drag coefficients …
Reconfigurable Communication Systems For Cubesats Xat-52100-Pre-001-Uvigo.Inta, Gabriel Gonzalez Fernandez, Fernando Aguado-Agelet, Cesar Martinez-Fernandez
Reconfigurable Communication Systems For Cubesats Xat-52100-Pre-001-Uvigo.Inta, Gabriel Gonzalez Fernandez, Fernando Aguado-Agelet, Cesar Martinez-Fernandez
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Gabriel González Fernández, Fernando Aguado-Agelet, and César Martínez-Fernández titled "Reconfigurable communication systems for CubeSats XAT-52100-PRE-001-UVIGO.INTA" from January 22, 2009.
A System Approach For A Double Cubesat, Sindre Persen, Anton Bolstad
A System Approach For A Double Cubesat, Sindre Persen, Anton Bolstad
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Sindre Persen and Anton Bolstad titled "A system approach for a double CubeSat" from January 22, 2009.
Cubesat Technology Demonstration Mission, Tanya Vladimirova, Christopher Bridges, Saad Malik, Muhammad Fayyaz, Muhammad Owais, Adeel Shahzeb, Robert Barnes, Asim Qureshi, Jean Paul, Guoxia Yu, Abdul-Halim Jallad, Martin Sweeting
Cubesat Technology Demonstration Mission, Tanya Vladimirova, Christopher Bridges, Saad Malik, Muhammad Fayyaz, Muhammad Owais, Adeel Shahzeb, Robert Barnes, Asim Qureshi, Jean Paul, Guoxia Yu, Abdul-Halim Jallad, Martin Sweeting
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Tanya Vladimirova, Christopher Bridges, Saad Malik, Muhammad Fayyaz, Muhammad Owais, Adeel Shahzeb, Robert Barnes, Asim Qureshi, Jean Paul, Guoxia Yu, Abdul-Halim Jallad and Martin Sweeting titled "CubeSat Technology Demonstration Mission" from January 22, 2009.
Analysing Multi‐Mission Capability In Cubesat Design, Steve Greenland
Analysing Multi‐Mission Capability In Cubesat Design, Steve Greenland
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Steve Greenland titled "Analysing multi‐mission capability in CubeSat design" from January 22, 2009.
Novel Electric Propulsion Technology Demonstration On Estcube-1 Mission, Urmas Kvell
Novel Electric Propulsion Technology Demonstration On Estcube-1 Mission, Urmas Kvell
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Urmas Kvell titled "Novel electric propulsion technology demonstration on EstCube-1 mission" from January 22, 2009.