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Articles 2101 - 2130 of 5700
Full-Text Articles in Engineering
Rf Emitter Tracking And Intent Assessment, Benjamin J. Kuhar
Rf Emitter Tracking And Intent Assessment, Benjamin J. Kuhar
Theses and Dissertations
Current research in employing pattern recognition techniques in a wireless sensor network (WSN) to detect anomalous or suspicious behavior is limited. The purpose of this research was to determine the feasibility of an accurate tracking and intent assessment system of unknown or foreign radio frequency (RF) emitters in close proximity to and within military installations as a method for physical security. 22 position tracks were collected using a hand-held Global Positioning System (GPS) unit and a training data set from five different features was generated for each position track. Each collected position track was individually classified as suspicious or non-suspicious …
Sensitivity Analysis Of An Automated Calibration Routine For Airborne Cameras, Philip E. Lorenzini
Sensitivity Analysis Of An Automated Calibration Routine For Airborne Cameras, Philip E. Lorenzini
Theses and Dissertations
Given a known aircraft location, a set of camera calibration parameters can be used to correlate features in an image with ground locations. Previously, these calibration parameters were obtained during preflight with a lengthy calibration process. A method to automate this calibration using images taken with an aircraft mounted camera and position and attitude data is developed. This thesis seeks to determine a partial set of circumstances that affect the accuracy of the calibration results through simulation and experimental flight test. A software simulator is developed in which to test an array of aircraft maneuvers, camera orientations, and noise injection. …
Error Characterization Of Vision-Aided Navigation Systems, Daniel A . Marietta
Error Characterization Of Vision-Aided Navigation Systems, Daniel A . Marietta
Theses and Dissertations
The goal of this work is to characterize the errors committed by an Image Aided Navigation (IAN) algorithm that has been developed for use as a navigation tool in GPS denied areas. The filter under study was developed by the Air Force Institute of Technology's Advanced Navigation Technology center, and has been the focus of numerous research efforts. Unfortunately, these studies have all been based on single runs or simulations, and such results may not be indicative of the true filter performance. This problem extends to IAN publications in general; no analysis of IAN based upon a sizable real world …
Rootkit Detection Using A Cross-View Clean Boot Method, Bridget N. Flatley
Rootkit Detection Using A Cross-View Clean Boot Method, Bridget N. Flatley
Theses and Dissertations
In cyberspace, attackers commonly infect computer systems with malware to gain capabilities such as remote access, keylogging, and stealth. Many malware samples include rootkit functionality to hide attacker activities on the target system. After detection, users can remove the rootkit and associated malware from the system with commercial tools. This research describes, implements, and evaluates a clean boot method using two partitions to detect rootkits on a system. One partition is potentially infected with a rootkit while the other is clean. The method obtains directory listings of the potentially infected operating system from each partition and compares the lists to …
Improving Bandwidth Utilization In A 1 Tbps Airborne Mimo Communications Downlink, Jonathan D. Hill
Improving Bandwidth Utilization In A 1 Tbps Airborne Mimo Communications Downlink, Jonathan D. Hill
Theses and Dissertations
FEC techniques are compared for different MIMO configurations of a high altitude, extremely wide bandwidth radio frequency downlink. Monte Carlo simulations are completed in MATLAB® with the aim of isolating the impacts of turbo codes and LDPC codes on system throughput and error performance. The system is modeled as a transmit-only static array at an altitude of 60,000 feet, with no interferers in the channel. Transmissions are received by a static receiver array. Simulations attempt to determine what modulation types should be considered for practical implementation, and what FEC codes enable these modulation schemes. The antenna configurations used in this …
Automatic Modulation Classification Of Common Communication And Pulse Compression Radar Waveforms Using Cyclic Features, John A . Hadjis
Automatic Modulation Classification Of Common Communication And Pulse Compression Radar Waveforms Using Cyclic Features, John A . Hadjis
Theses and Dissertations
This research develops a feature-based MAP classification system and applies it to classify several common pulse compression radar and communication modulations. All signal parameters are treated as unknown to the classifier system except SNR and the signal carrier frequency. The features are derived from estimated duty cycle, cyclic spectral correlation, and cyclic cumulants. The modulations considered in this research are BPSK, QPSK, 16-QAM, 64-QAM, 8-PSK, and 16-PSK communication modulations, as well as Barker coded, Barker coded, Barker coded, Frank coded, Px49 coded, and LFM pulse compression modulations. Simulations show that average correct signal modulation type classification %C 90% is achieved …
File Carving And Malware Identification Algorithms Applied To Firmware Reverse Engineering, Karl A . Sickendick
File Carving And Malware Identification Algorithms Applied To Firmware Reverse Engineering, Karl A . Sickendick
Theses and Dissertations
Modern society depends on critical infrastructure (CI) managed by Programmable Logic Controllers (PLCs). PLCs depend on firmware, though firmware security vulnerabilities and contents remain largely unexplored. Attackers are acquiring the knowledge required to construct and install malicious firmware on CI. To the defender, firmware reverse engineering is a critical, but tedious, process. This thesis applies machine learning algorithms, from the le carving and malware identification fields, to firmware reverse engineering. It characterizes the algorithms' performance. This research describes and characterizes a process to speed and simplify PLC firmware analysis. The system partitions binary firmwares into segments, labels each segment with …
Adaptations And Analysis Of The Afit Noise Radar Network For Indoor Navigation, Russell D. Wilson Iv
Adaptations And Analysis Of The Afit Noise Radar Network For Indoor Navigation, Russell D. Wilson Iv
Theses and Dissertations
After several years of development, the AFIT Noise Radar Network (NoNET) has proven to be an extremely versatile system for many standard radar functions. This pallet of capabilities includes through the wall target tracking capabilities due to its wide bandwidth and UHF operations. Utilizing White Gaussian Noise as its waveform, the NoNET can operate at much lower power levels than other comparable systems while remaining extremely covert. In an effort to explore new applications, the question arose could the NoNET provide a viable option for navigation capability in GPS denied and indoor environments? This research aims to provide proof of …
Feasibility Analysis On The Utilization Of The Iridium Satellite Communications Network For Resident Space Objects In Low Earth Orbit, John R. Claybrook
Feasibility Analysis On The Utilization Of The Iridium Satellite Communications Network For Resident Space Objects In Low Earth Orbit, John R. Claybrook
Theses and Dissertations
In recent years, space has become more congested and contested, particularly in low Earth orbit (LEO), generating the need for a low-latency capability to provide precise orbital knowledge and accurate space situational awareness information. This thesis investigates the feasibility of resident space objects (RSOs) in LEO communicating continuously with ground operators or users through the Iridium Satellite Communications Network. Due to the problem's complexity and required time for computation, a test-industry technique called Design of Experiments is implemented in order to efficiently study the feasibility of the communication link. Specifically, an optimal response surface method is chosen to design the …
Biaxial (Tension-Torsion) Testing Of An Oxide/Oxide Ceramic Matrix Composite, Joseph M. Derienzo
Biaxial (Tension-Torsion) Testing Of An Oxide/Oxide Ceramic Matrix Composite, Joseph M. Derienzo
Theses and Dissertations
High temperatures and structural loads in advanced aerospace structures often result in complex loading conditions. This study is focused on biaxial (tension-torsion) testing of an oxide-oxide porous matrix ceramic matrix composite (CMC) (NextelTM 720/AS) thin wall tube with a novel involute layup. Tests included pure torsion and biaxial (tension- torsion) loading. Strain gages were used in addition to digital image correlation (DIC) to measure strains and to detect crack initiation and propagation. Room temperature and 1100°C uniaxial tests were performed in a build up approach prior to biaxial (tension-torsion) testing. Double-notch shear (DNS) specimens were tested at 1100°C in air …
Application Of Finite Element To Evaluate Material With Small Modulus Of Elasticity, Boyce H. Dauby
Application Of Finite Element To Evaluate Material With Small Modulus Of Elasticity, Boyce H. Dauby
Theses and Dissertations
This thesis describes the development of a series of models utilizing the commercial finite element suite ABAQUS specifically to apply towards the study of biological tissue. The end goal is to be able to obtain the material properties of the Manducca Sexta, a biological inspiration for flapping wing micro-air vehicles. Two finite element models were used to analyze the results of two prior studies of other researchers. A flat punch elastic model examined boundary effects and confirmed that the point of indentation was far enough removed from the boundary. The hyperelastic spherical indentation experiment examined the effects of coefficient of …
Computational Simulation Of Explosively Generated Pulsed Power Devices, Mollie C. Drumm
Computational Simulation Of Explosively Generated Pulsed Power Devices, Mollie C. Drumm
Theses and Dissertations
Technology and size constraints have limited the development of the end game mechanisms of today's modern military weapons. A smaller, more efficient means of powering these devices is needed, and explosive pulsed power devices could be that answer. While most prior research has been in the experimental field, there is a need for more theory-based research and a computer modeling capability. The objective of this research was to use experimental data collected by the US Army at Redstone Arsenal from their ferroelectric generator (FEG) design in combination with the ALEGRA-EMMA code to develop a computer model that can accurately represent …
Effects Of Temperature On The Performance Of A Small Internal Combustion Engine At Altitude, Travis D. Husaboe
Effects Of Temperature On The Performance Of A Small Internal Combustion Engine At Altitude, Travis D. Husaboe
Theses and Dissertations
The effects of atmospheric pressure and temperature variations on the performance of small internal combustion (IC) engines operating at altitudes significantly above sea level are not widely documented. Using an altitude chamber and fuel-injected twostroke engine, data were collected while varying air temperature along with pressure. The peak engine power was 4.1 kW at roughly sea level standard conditions and dropped to 3.5 kW at the standard conditions for an altitude of 1.5 km. At a combination of pressure and temperature corresponding to an altitude of 3 km, peak power fell further to 2.5 kW. The combined effects of standard …
A Study Of The Thermal Environment Developed By A Traveling Slipper At High Velocity, Kathleen H. Le
A Study Of The Thermal Environment Developed By A Traveling Slipper At High Velocity, Kathleen H. Le
Theses and Dissertations
The research presented in this thesis is developed from the relative sliding motion of a traveling slipper and stationary rail at the Holloman High Speed Test Track located at Holloman AFB, NM. The high velocity condition of the slipper traveling down the rail creates a thermal environment that is of interest to the researchers at the Air Force Institute of Technology. The high temperatures coupled with high velocity leads to a non-linear problem known as melt wear. The goal of this research is to characterize the amount of heat flow going into the slipper as it traverses the rail and …
Experimental Characterization Of The Structural Dynamics And Aero-Structural Sensitivity Of A Hawkmoth Wing Toward The Development Of Design Rules For Flapping Wing Micro Air Vehicles, Aaron G. Norris
Theses and Dissertations
A case is made for why the structures discipline must take on a more central role in the research and design of flapping-wing micro-air-vehicles, especially if research trends continue toward bio-inspired, insect-sized flexible wing designs. In making the case, the eigenstructure of the wing emerges as a key structural metric for consideration. But with virtually no structural dynamic data available for actual insect wings, both engineered and computational wing models that have been inspired by biological analogs have no structural truth models to which they can be anchored. An experimental framework is therefore developed herein for performing system identification testing …
Porous Emitter Colloid Thruster Performance Characterization Using Optical Techniques, Eric T. Wolf
Porous Emitter Colloid Thruster Performance Characterization Using Optical Techniques, Eric T. Wolf
Theses and Dissertations
This research focuses on experimentally characterizing the performance parameters of a colloid thruster with porous emitters through optical techniques. Porous emitters are different than traditional needle emitters in how they allow a variation in the number and size of Taylor Cones throughout a range of propellant volumetric flow rate conditions. An algorithm is created to calculate the estimated minimum and maximum number of emitter sites based on magnified images of the porous emitter heads. Theoretical thruster performance parameters are then established from the estimated number of emitter sites. Experimental techniques for measuring the thrust and exhaust exit velocity are proposed. …
Training Maneuver Evaluation For Reduced Order Modeling Of Stability & Control Properties Using Computational Fluid Dynamics, Craig C. Porter
Training Maneuver Evaluation For Reduced Order Modeling Of Stability & Control Properties Using Computational Fluid Dynamics, Craig C. Porter
Theses and Dissertations
System identification has long been used as a tool for flight test engineers to characterize systems under test; however, the inputs to these characterization activities have previously been limited to wind tunnel and flight test data. There has been a recent effort to incorporate computational fluid dynamics (CFD) into the system identification process. An integral piece of the process is the simulation of training maneuvers utilizing CFD. Up until now, the suitability of particular training maneuvers has been assessed by comparing the reduced model to known results. This research strives to recommend a set of parameters to be used in …
Computer Based Behavioral Biometric Authentication Via Multi-Modal Fusion, Kyle O. Bailey
Computer Based Behavioral Biometric Authentication Via Multi-Modal Fusion, Kyle O. Bailey
Theses and Dissertations
Biometric computer authentication has an advantage over password and access card authentication in that it is based on something you are, which is not easily copied or stolen. One way of performing biometric computer authentication is to use behavioral tendencies associated with how a user interacts with the computer. However, behavioral biometric authentication accuracy rates are much larger then more traditional authentication methods. This thesis presents a behavioral biometric system that fuses user data from keyboard, mouse, and Graphical User Interface (GUI) interactions. Combining the modalities results in a more accurate authentication decision based on a broader view of the …
High Frequency Magnetic Field Direction Finding Using Mgl-S8a B-Dot Sensors, Michael D. Archer
High Frequency Magnetic Field Direction Finding Using Mgl-S8a B-Dot Sensors, Michael D. Archer
Theses and Dissertations
Aircraft based direction finding (DF) in the high frequency (HF) band is difficult due to the aircraft's size with respect to wavelength and limited azimuthal resolution. A B-dot sensor is useful for detection of the time varying magnetic field and offers improved integration into an aircraft. What the B-dot sensor gains in integration it gives up in sensitivity because it is designed for frequencies above 5 GHz. Design of an airborne HFDF array using Bdot sensors is based in maximizing the physical extent of the array and eliminating multiple main beams. The goals of this research are to complete a …
Machine Conscious Architecture For State Exploitation And Decision Making, Mark M. Derriso
Machine Conscious Architecture For State Exploitation And Decision Making, Mark M. Derriso
Theses and Dissertations
This research addressed a critical limitation in the area of computational intelligence by developing a general purpose architecture for information processing and decision making. Traditional computational intelligence methods are best suited for well-defined problems with extensive, long-term knowledge of the environmental and operational conditions the system will encounter during operation. These traditional approaches typically generate quick answers (i.e., reflexive responses) using pattern recognition methods. Most pattern recognition techniques are static processes which consist of a predefined series of computations. For these pattern recognition approaches to be effective, training data is required from all anticipated environments and operating conditions. The proposed …
Laser Illuminated Imaging: Multiframe Beam Tilt Tracking And Deconvolution Algorithm, David J. Becker
Laser Illuminated Imaging: Multiframe Beam Tilt Tracking And Deconvolution Algorithm, David J. Becker
Theses and Dissertations
A laser-illuminated imaging system operating in the presence of atmospheric turbulence will encounter several sources of noise and diffraction induced errors. As the beam propagates, turbulence induced tilt will cause the beam to wander off axis from the target. This is especially troublesome when imaging satellites, since most turbulence is closer to the Earth's surface and greatly affects the beam in the early stages of propagation. Additionally, the returning beam convolved with the target will encounter turbulence induced tilt that appears as apparent movement of the target between image frames. This results in varying beam intensities at the target surface …
Using Rf-Dna Fingerprints To Discriminate Zigbee Devices In An Operational Environment, Clay K. Dubendorfer
Using Rf-Dna Fingerprints To Discriminate Zigbee Devices In An Operational Environment, Clay K. Dubendorfer
Theses and Dissertations
This research was performed to expand AFIT's Radio Frequency Distinct Native Attribute (RF-DNA) fingerprinting process to support IEEE 802.15.4 ZigBee communication network applications. Current ZigBee bit-level security measures include use of network keys and MAC lists which can be subverted through interception and spoofing using open-source hacking tools. This work addresses device discrimination using Physical (PHY) waveform alternatives to augment existing bit-level security mechanisms. ZigBee network vulnerability to outsider threats was assessed using Receiver Operating Characteristic (ROC) curves to characterize both Authorized Device ID Verification performance (granting network access to authorized users presenting true bit-level credentials) and Rogue Device Rejection …
Photoacoustic Detection Of Terahertz Radiation For Chemical Sensing And Imaging Applications, Stjepan Blazevic
Photoacoustic Detection Of Terahertz Radiation For Chemical Sensing And Imaging Applications, Stjepan Blazevic
Theses and Dissertations
The main research objective is the development of photoacoustic sensor capable of detecting weak terahertz (THz) electromagnetic radiation. The feasibility of THz remote sensing is seen in the utilization of Microelectromechanical systems (MEMS) cantilever-based sensor. The overall sensing functionality of the detector in development is based on the photoacoustic spectroscopy and direct piezoelectric effect phenomena, as a result of which significant part of investigation has been conducted in the areas of terahertz electromagnetic radiation and its detection. The main focus of this research work was the detector analytical and Finite Element Method (FEM) simulation modeling, involving necessary material properties investigations …
Characterization Of Metal-Insulator-Transition (Mit) Phase Change Materials (Pcm) For Reconfigurable Components, Circuits, And Systems, Brent L. Danner
Characterization Of Metal-Insulator-Transition (Mit) Phase Change Materials (Pcm) For Reconfigurable Components, Circuits, And Systems, Brent L. Danner
Theses and Dissertations
Many microelectromechanical systems (MEMS) use metal contact micro-switches as part of their reconfigurable device design. These devices utilize a mechanical component that can wear down and fail over time. Metal insulator transition (MIT) materials, also known as phase change materials (PCMs), exhibit a reversible transition that can be used to replace the mechanical component in reconfigurable devices. In the presence of a thermal or electric field stimuli, the PCMs will transition back and forth between a crystalline and amorphous state. During this transformation, the resistivity, reflectivity, and Young's modulus of the material drastically change. This research effort focuses on characterizing …
Cognitive Augmentation For Network Defense, James E. Emge
Cognitive Augmentation For Network Defense, James E. Emge
Theses and Dissertations
Traditionally, when a task is considered for automation it is a binary decision, either the task was completely automated or it remains manual. LOA is a departure from the tradition use of automation in cyber defense. When a task is automated, it removes the human administrator from the performance of the task, compromising their SA of the state of the network. When the administrator loses SA of the network performance and its current state, failure recovery time becomes much longer. This is because the administrators must orient themselves to the current state of the network at the time of failure …
Finite Element Analysis Of A Highly Flexible Flapping Wing, Justin K. Mason
Finite Element Analysis Of A Highly Flexible Flapping Wing, Justin K. Mason
Theses and Dissertations
Small unmanned aerial systems are being designed to emulate the flapping kinematics of insects and birds which show superior control in slow speed regimes compared to fixed wing or rotorcraft aircraft. The flight of flapping wing vehicles is characterized by aeroelastic effects. Most research has been dedicated towards understanding the aerodynamic side of the aeroelastic response with minimal effort spent towards validating the structural response. A finite element model of a wing from a commercial flapping wing vehicle was created to validate the structural response. Vacuum testing allowed the isolation of the inertial response for a direct comparison to the …
Heat Exchanger Design And Testing For A 6-Inch Rotating Detonation Engine, Scott W. Theuerkauf
Heat Exchanger Design And Testing For A 6-Inch Rotating Detonation Engine, Scott W. Theuerkauf
Theses and Dissertations
This thesis explains the design and testing of a water-cooled rotating detonation engine (RDE) run on hydrogen and air. The change in water temperature as it cooled the engine was used to find the steady heat rate into the containing walls of the detonation channel. The engine successfully ran four times for 20 seconds each. The steady-state heat rate was measured to be 2.5% of the propellant lower heating value (LHV) into the outer wall and 7.1% of LHV into the inner wall. Additionally, a quick-response resistance temperature detector (RTD) was used in an uncooled RDE of similar dimension to …
Real-Time Heading Estimation Using Perspective Features, James W. Dean
Real-Time Heading Estimation Using Perspective Features, James W. Dean
Theses and Dissertations
There are a large number of commercially available quad-rotor helicopters available from various manufacturers. All of these systems rely on a low cost MEMS based inertial measurement system for stabilization and navigation. These low cost inertial systems are all subject to rapid error growth in their attitude and position estimates unless bounded by external measurements. This thesis created real-time algorithm to integrate measurements from visual cues with measurements from onboard sensors to estimate the attitude position and velocity of a quad-rotor helicopter in a local navigation frame, a system model for the ARDrone, and a feed-back controller for the vehicle's …
Estimating The Probability Of Being The Best System: A Generalized Method And Nonparametric Hypothesis Test, Aaron M. Lessin
Estimating The Probability Of Being The Best System: A Generalized Method And Nonparametric Hypothesis Test, Aaron M. Lessin
Theses and Dissertations
This thesis provides two new approaches for comparing competing systems. Instead of making comparisons based on long run averages or mean performance, the first paper presents a generalized method for calculating the probability that a single system is the best among all systems in a single trial. Unlike current empirical methods, the generalized method calculates the exact multinomial probability that a single system is best among competing systems. The ability to avoid time consuming empirical estimate techniques could potentially result in significant savings in both time and money when comparing alternate systems. A Monte Carlo simulation is conducted comparing the …
Needed Actions Within Defense Acquisitions Based On A Forecast Of Future Mobile Information And Communications Technologies Deployed In Austere Environments, Andrew T. Soine
Theses and Dissertations
The purpose of this research was twofold. First, it developed a forecast of future mobile information and communications technologies (ICT) suitable for use by military forces in austere environments in 5-10, 10-20, and beyond 20 years. Secondly, it explored whether or not current acquisitions practices will be adequate to meet the needs of warfighters who depend on mobile ICT. These questions were explored by conducting utilization of the Delphi technique. Eight panelists from within the private sector conducted three rounds of iterative feedback. This research resulted in a technology forecast for the three timeframes aforementioned, and the potential impacts to …