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Articles 1 - 30 of 34
Full-Text Articles in Engineering
A Comparison Of Correlation-Agnostic Techniques For Magnetic Navigation, Clark N. Taylor, Josh Hiatt
A Comparison Of Correlation-Agnostic Techniques For Magnetic Navigation, Clark N. Taylor, Josh Hiatt
Faculty Publications
Navigation using a Global Navigation Satellite System (GNSS) is common for autonomous vehicles (ground or air). Unfortunately, GNSS-based navigation solutions are often susceptible to jamming, interference, and a limited number of satellites. A proposed technique to aid in navigation when a GNSS-based system fails is magnetic navigation - navigation using the Earth's magnetic anomaly field. This solution comes with its own set of problems including the need for quality magnetic maps in every area in which magnetic navigation will be used. Many of the currently available magnetic maps are generated from a combination of dated magnetic surveys, resulting in maps …
Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham
Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham
Theses and Dissertations
Visual Simultaneous Localization and Mapping (VSLAM) algorithms have evolved rapidly in the last few years, however there has been little research evaluating current algorithm's effectiveness and limitations when applied to tracking the position of a fixed-wing aerial vehicle. This research looks to evaluate current monocular VSLAM algorithms' performance on aerial vehicle datasets using the SLAMBench2 benchmarking suite. The algorithms tested are MonoSLAM, PTAM, OKVIS, LSDSLAM, ORB-SLAM2, and SVO, all of which are built into the SLAMBench2 software. The algorithms' performance is evaluated using simulated datasets generated in the AftrBurner Engine. The datasets were designed to test the quality of each …
Effects Of Long-Term Evolution Waveform On Synthetic Aperture Radar Image Quality Metrics, Blake M. Colson
Effects Of Long-Term Evolution Waveform On Synthetic Aperture Radar Image Quality Metrics, Blake M. Colson
Theses and Dissertations
As a greater demand by the private sector for bandwidth drives spectrum allocations away from defense, new methods for coexistence in the spectrum are being explored. One of the prominent areas in defense for this coexistence is passive radar. This mode of radar system allows for data collection by referencing signals already established in the environment of interest. Some of the most prolific signals currently available are those used for mobile communication networks. In particular, Long- Term Evolution (LTE) is a common waveform that could be leveraged for discrete collection of image intelligence. Seeking to build a base of knowledge, …
Improved Fabrication For Micromirror Arrays, Enoc Flores
Improved Fabrication For Micromirror Arrays, Enoc Flores
Theses and Dissertations
Micromirror devices which consisted of one SU-8 2050 layer, two different exposures, and a series of metal depositions were constructed and evaluated. By varying the exposure, a micromirror structure was fabricated with different thicknesses, a ratio of 1.083 µm/(mJ/cm2) was found. The initial design consisted of four layers. The pillar was made of one SU-8 layer, and the top portion had three layers in the following order: gold, SU-8, and gold. This design could not be released and did not have characteristics of a flat and conformal reflective surface. Several variations of the initial design were explored and all of …
Confirmation Bias Estimation From Electroencephalography With Machine Learning, Micah Villarreal
Confirmation Bias Estimation From Electroencephalography With Machine Learning, Micah Villarreal
Theses and Dissertations
Cognitive biases are known to plague human decision making and can have disastrous effects in the fast-paced environments of military operators. Traditionally, behavioral methods are employed to measure the level of bias in a decision. However, these measures can be hindered by a multitude of subjective factors and cannot be collected in real-time. This work investigates enhancing the current measures of estimating confirmation bias with additional behavior patterns and physiological variables to explore the viability of real-time bias detection. Confirmation bias in decisions is estimated by modeling the relationship between Electroencephalography (EEG) signals and behavioral data using machine learning methods.
Range Information Characterization Of The Hokuyo Ust-20lx Lidar Sensor, Matthew A. Cooper, John F. Raquet, Rick Patton
Range Information Characterization Of The Hokuyo Ust-20lx Lidar Sensor, Matthew A. Cooper, John F. Raquet, Rick Patton
Faculty Publications
This paper presents a study on the data measurements that the Hokuyo UST-20LX Laser Rangefinder produces, which compiles into an overall characterization of the LiDAR sensor relative to indoor environments. The range measurements, beam divergence, angular resolution, error effect due to some common painted and wooden surfaces, and the error due to target surface orientation are analyzed. It was shown that using a statistical average of sensor measurements provides a more accurate range measurement. It was also shown that the major source of errors for the Hokuyo UST-20LX sensor was caused by something that will be referred to as “mixed …
Experimental Validation Of A Heterogeneous Radar Clutter Statistical Estimation Method, Elliot R. Erstein
Experimental Validation Of A Heterogeneous Radar Clutter Statistical Estimation Method, Elliot R. Erstein
Theses and Dissertations
Radar clutter models are important for radar target detection when clutter is present. A new method for estimating single clutter type, homogeneous, radar clutter statistics through measurement of a multiple type, heterogeneous clutter was developed in 2015 by researchers at the Air Force Institute of Technology. The estimation method is greatly valued in the clutter research and modeling world for reducing clutter campaign measurement time and cost. This thesis looks at validation steps for the estimation method through the use of simulations and experimental radar clutter measurements.
Airborne Wireless Communication Modeling And Analysis With Matlab, Matthew J. Vincie
Airborne Wireless Communication Modeling And Analysis With Matlab, Matthew J. Vincie
Theses and Dissertations
Over the past decade, there has been a dramatic increase in the use of unmanned aerial vehicles (UAV) for military, commercial, and private applications. Critical to maintaining control and a use for these systems is the development of wireless networking systems [1]. Computer simulation has increasingly become a key player in airborne networking developments though the accuracy and credibility of network simulations has become a topic of increasing scrutiny [2-5]. Much of the inaccuracies seen in simulation are due to inaccurate modeling of the physical layer of the communication system. This research develops a physical layer model that combines antenna …
Enhancing Electromagnetic Side-Channel Analysis In An Operational Environment, David P. Montminy
Enhancing Electromagnetic Side-Channel Analysis In An Operational Environment, David P. Montminy
Theses and Dissertations
Side-channel attacks exploit the unintentional emissions from cryptographic devices to determine the secret encryption key. This research identifies methods to make attacks demonstrated in an academic environment more operationally relevant. Algebraic cryptanalysis is used to reconcile redundant information extracted from side-channel attacks on the AES key schedule. A novel thresholding technique is used to select key byte guesses for a satisfiability solver resulting in a 97.5% success rate despite failing for 100% of attacks using standard methods. Two techniques are developed to compensate for differences in emissions from training and test devices dramatically improving the effectiveness of cross device template …
Side-Channel Analysis Of Subscriber Identity Modules, John A. Hearle
Side-Channel Analysis Of Subscriber Identity Modules, John A. Hearle
Theses and Dissertations
Subscriber identity modules (SIMs) contain useful forensic data but are often locked with a PIN code that restricts access to this data. If an invalid PIN is entered several times, the card locks and may even destroy its stored data. This presents a challenge to the retrieval of data from the SIM when the PIN is unknown. The field of side-channel analysis (SCA) collects, identifies, and processes information leaked via inadvertent channels. One promising side-channel leakage is that of electromagnetic (EM) emanations; by monitoring the SIM's emissions, it may be possible to determine the correct PIN to unlock the card. …
Kernel Extended Real-Valued Negative Selection Algorithm (Kernsa), Brett A . Smith
Kernel Extended Real-Valued Negative Selection Algorithm (Kernsa), Brett A . Smith
Theses and Dissertations
Artificial Immune Systems (AISs) are a type of statistical Machine Learning (ML) algorithm based on the Biological Immune System (BIS) applied to classification problems. Inspired by increased performance in other ML algorithms when combined with kernel methods, this research explores using kernel methods as the distance measure for a specific AIS algorithm, the Real-valued Negative Selection Algorithm (RNSA). This research also demonstrates that the hard binary decision from the traditional RNSA can be relaxed to a continuous output, while maintaining the ability to map back to the original RNSA decision boundary if necessary. Continuous output is used in this research …
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 …
Constitutive Parameter Measurement Using Double Ridge Waveguide, Nathan J. Lehman
Constitutive Parameter Measurement Using Double Ridge Waveguide, Nathan J. Lehman
Theses and Dissertations
Electromagnetic materials characterization is important in the design of systems that interact with electromagnetic waves. Determining the constitutive parameters of a material is a vast area of research and practice. For this paper, discussion will focus on a destructive method using waveguides in the frequency range of 6-18 GHz. Traditional methods to perform similar measurements include using coaxial cable, stripline, focus beam and rectangular waveguides. This work will use Double Ridged Waveguide (DRWG) to compare to these other methods and will discuss the attributes and drawbacks of this new approach. The most similar method utilizes rectangular waveguide, so the primary …
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 …
A Study Of Dim Object Detection For The Space Surveillance Telescope, Stephen D. Maksim
A Study Of Dim Object Detection For The Space Surveillance Telescope, Stephen D. Maksim
Theses and Dissertations
Current methods of dim object detection for space surveillance make use of a Gaussian log-likelihood-ratio-test-based detector that only considers the probability that a single point in an image resulted from the propagation of a point source through space. This paper proposes the application of a correlating Gaussian log-likelihood-ratio-test-based detector, which makes use of all the pixels in the window, to the arena of dim object detection. The requirements for comparing these detectors using the same threshold of detection are established. The performance of the detectors is compared using images taken by the Space Surveillance Telescope in New Mexico of a …
Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam
Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam
Theses and Dissertations
For conventional imaging systems, GEO space objects cannot be resolved due to their 40 Mm distance. There exists a strong need to obtain high resolution images of GEO objects and to accomplish this task, investigation into the suitability of ISAL is currently underway. A critical component in determining this suitability is to accurately model the atmospheric impacts on LADAR pulses. Conventional knowledge says that while the atmosphere churns, wind is the predominant cause of temporal evolution which simplifies all modeling and simulation into the frozen flow hypothesis. The concern is that the frozen flow hypothesis based phase screen generation techniques …
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. …
Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer
Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer
Theses and Dissertations
A new method for characterization of unknown targets using passive multispectral polarimetric imagery is presented. Previous work makes use of a pBRDF derived equation for the degree of linear polarization and with the aid of measurements at multiple incident angles estimates refractive index and reflection angle. This work uses known incident and reflection angles along with dispersion equations and polarimetric data at multiple wavelengths to recover the index of refraction. Although imagery is collected with a division of time polarimeter and a spectral filter wheel in iterative, manual steps, the new algorithm could be applied to any set of registered …
Exploitation Of Rf-Dna For Device Classification And Verification Using Grlvqi Processing, Donald R. Reising
Exploitation Of Rf-Dna For Device Classification And Verification Using Grlvqi Processing, Donald R. Reising
Theses and Dissertations
This dissertation introduces a GRLVQI classifier into an RF-DNA fingerprinting process and demonstrates applicability for device classification and ID verification. Unlike MDA/ML processing, GRLVQI provides a measure of feature relevance that enables Dimensional Reduction Analysis (DRA) to enhance the experimental-to-operational transition potential of RF-DNA fingerprinting. Using 2D Gabor Transform RF-DNA fingerprints extracted from experimentally collected OFDM-based 802.16 WiMAX and 802.11 WiFi device emissions, average GRLVQI classification accuracy of %C greater than or equal to 90% is achieved using full and reduced dimensional feature sets at SNR greater than or equal to 10.0 dB and SNR greater than or equal to …
Using Qr Factorization For Real-Time Anomaly Detection Of Hyperspectral Images, Kelly R. Bush
Using Qr Factorization For Real-Time Anomaly Detection Of Hyperspectral Images, Kelly R. Bush
Theses and Dissertations
Anomaly detection has been used successfully on hyperspectral images for over a decade. However, there is an ever increasing need for real-time anomaly detectors. Historically, anomaly detection methods have focused on analysis after the entire image has been collected. As useful as post-collection anomaly detection is, there is a great advantage to detecting an anomaly as it is being collected. This research is focused on speeding up the process of detection for a pre-existing method, Linear RX, which is a variation on the traditional Reed-Xiaoli detector. By speeding up the process of detection, it is possible to create a real-time …
Near Earth Object Detection Using A Poisson Statistical Model For Detection On Images Modeled From The Panoramic Survey Telescope And Rapid Response System, Curtis J. R. Peterson
Near Earth Object Detection Using A Poisson Statistical Model For Detection On Images Modeled From The Panoramic Survey Telescope And Rapid Response System, Curtis J. R. Peterson
Theses and Dissertations
The purpose of this research effort is to develop, simulate, and test a new algorithm to detect Near Earth Objects (NEOs) using a Likelihood Ratio Test (LRT) based on a Poisson statistical model for the arrival of photons. One detection algorithm currently in use is based on a Gaussian approximation of the arrival of photons, and is compared to the proposed Poisson model. The research includes three key components. The first is a quantitative analysis of the performance of both algorithms. The second is a system model for simulating detection statistics. The last component is a collection of measured data …
Integrated Approach To Free Space Optical Communications In Strong Turbulence, Jason A. Tellez
Integrated Approach To Free Space Optical Communications In Strong Turbulence, Jason A. Tellez
Theses and Dissertations
The propagation of a free space optical communication signal through atmospheric turbulence experiences random fluctuations in intensity, including signal fades which negatively impact the communications link performance. This research develops an analytical probability density function (PDF) to model the best case scenario of using multiple independent beams to reduce the intensity fluctuations. The PDF was further developed to account for partially correlated beams, such as would be experienced by beams having finite separation. The PDF was validated with results obtained from digital simulations as well as lab experiments. The research showed that as the number of transmitted beams increases the …
Performance Analysis And Optimization Of The Winnow Secret Key Reconciliation Protocol, Kevin C. Lustic
Performance Analysis And Optimization Of The Winnow Secret Key Reconciliation Protocol, Kevin C. Lustic
Theses and Dissertations
Currently, private communications in public and government sectors rely on methods of cryptographic key distribution that will likely be rendered obsolete the moment a full-scale quantum computer is realized, or efficient classical methods of factoring are discovered. There are alternative methods for distributing secret key material in a post-quantum era. One example of a system capable of securely distributing cryptographic key material, known as Quantum Key Distribution (QKD), is secure against quantum factorization techniques as its security rests on generally accepted laws of quantum physics. QKD protocols typically include a phase called Error Reconciliation, a clear-text classical-channel discussion between legitimate …
Software And Critical Technology Protection Against Side Channel Analysis Through Dynamic Hardware Obfuscation, John R. Bochert
Software And Critical Technology Protection Against Side Channel Analysis Through Dynamic Hardware Obfuscation, John R. Bochert
Theses and Dissertations
Side Channel Analysis (SCA) is a method by which an adversary can gather information about a processor by examining the activity being done on a microchip though the environment surrounding the chip. Side Channel Analysis attacks use SCA to attack a microcontroller when it is processing cryptographic code, and can allow an attacker to gain secret information, like a crypto-algorithm's key. The purpose of this thesis is to test proposed dynamic hardware methods to increase the hardware security of a microprocessor such that the software code being run on the microprocessor can be made more secure without having to change …
Effects Of Cyclic Prefix Jamming Versus Noise Jamming In Ofdm Signals, Amber L. Scott
Effects Of Cyclic Prefix Jamming Versus Noise Jamming In Ofdm Signals, Amber L. Scott
Theses and Dissertations
Signal jamming of an orthogonal frequency-division multiplexing (OFDM) signal is simulated in MATLAB. Two different means of jamming are used to see, which is a more efficient way to disrupt a signal using the same signal power. The first way is a basic additive white Gaussian noise (AWGN) jammer that equally jams the entire signal. The second way is an AWGN jammer that targets only the cyclic prefix (CP) of the signal. These two methods of jamming are simulated using different channel models and unknowns to get varying results. The three channel models used in the simulations are the no …
Characteristics Of A High Intensity, Pulsed, Potassium Vapor Laser In A Heat Pipe, Edward J. Hurd
Characteristics Of A High Intensity, Pulsed, Potassium Vapor Laser In A Heat Pipe, Edward J. Hurd
Theses and Dissertations
This thesis research paper presents the results of experiments using an optically pumped, pulsed potassium vapor laser in a heat pipe. The absorption on the potassium D2 line, output laser characteristics, and Raman scattering in potassium vapor are discussed. The spectral full width at half maximum (FWHM) of the D2 absorption line was much greater than predicted values for pressure broadening due to the high number density of potassium atoms and the long path length. At 320°C and 0 torr of helium, the FWHM was 765 GHz. At 100 torr it was 968 GHz. At 200 torr it …
Blind Deconvolution Method Of Image Deblurring Using Convergence Of Variance, Quentin D. Macmanus
Blind Deconvolution Method Of Image Deblurring Using Convergence Of Variance, Quentin D. Macmanus
Theses and Dissertations
Images are used for both aerial and space imagery applications, including target detection and tracking. The current problem concerning objects in geosynchronous orbit is that they are dim and hard to resolve because of their distance. This work will further the combined effort of AFIT and AFRL to provide enhanced space situational awareness (SSA) and space surveillance. SSA is critical in a time when many countries possess the technology to put satellites into orbit. Enhanced imaging technology improves the Air Force's ability to see if foreign satellites or other space hardware are operating in the vicinity of our own assets …
A Linear Combination Of Heuristics Approach To Spatial Sampling Hyperspectral Data For Target Tracking, Barry R. Secrest
A Linear Combination Of Heuristics Approach To Spatial Sampling Hyperspectral Data For Target Tracking, Barry R. Secrest
Theses and Dissertations
Persistent surveillance of the battlespace results in better battlespace awareness which aids in obtaining air superiority, winning battles, and saving friendly lives. Although hyperspectral imagery (HSI) data has proven useful for discriminating targets, it presents many challenges as a useful tool in persistent surveillance. A new sensor under development has the potential of overcoming these challenges and transforming our persistent surveillance capability by providing HSI data for a limited number of pixels and grayscale video for the remainder. The challenge of exploiting this new sensor is determining where the HSI data in the sensor's field of view will be the …
A Physical Model Of Human Skin And Its Application For Search And Rescue, Abel S. Nunez
A Physical Model Of Human Skin And Its Application For Search And Rescue, Abel S. Nunez
Theses and Dissertations
For this research we created a human skin reflectance model in the VIS and NIR. We then modeled sensor output for an RGB sensor based on output from the skin reflectance model. The model was also used to create a skin detection algorithm and a skin pigmentation level (skin reflectance at 685nm) estimation algorithm. The average root mean square error across the VIS and NIR between the skin reflectance model and measured data was 2%. The skin reflectance model then allowed us to generate qualitatively accurate responses for an RGB sensor for different biological and lighting conditions. To test the …
Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler
Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler
Theses and Dissertations
This research studies the growth of carbon nanotubes (CNT) from a nickel catalyst to be used on a field emission device. This thesis can be divided into three sections: the construction of a vacuum chamber for field emission testing, the design and fabrication of a triode structure to enable improved electron emission, and the pretreatment and growth of CNTs. To experimentally test the field emission of CNTs, a vacuum chamber must attain a vacuum of at least 10-5 torr. Our vacuum chamber designed and built achieved a maximum, final pressure of 10-8 torr. A triode structure was designed …