Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Air Force Institute of Technology

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 1 - 30 of 1210

Full-Text Articles in Engineering

Autonomous And Resilient Management Of All-Source Sensors For Navigation Assurance, Juan D. Jurado Sep 2019

Autonomous And Resilient Management Of All-Source Sensors For Navigation Assurance, Juan D. Jurado

Theses and Dissertations

All-source navigation has become increasingly relevant over the past decade with the development of viable alternative sensor technologies. However, as the number and type of sensors informing a system increases, so does the probability of corrupting the system with sensor modeling errors, signal interference, and undetected faults. Though the latter of these has been extensively researched, the majority of existing approaches have constrained faults to biases, and designed algorithms centered around the assumption of simultaneously redundant, synchronous sensors with valid measurement models, none of which are guaranteed for all-source systems. This research aims to provide all-source multi-sensor resiliency, assurance, and ...


Piezoelectric Sensor Crack Detection On Airframe Systems, Kevin J. Lin Mar 2019

Piezoelectric Sensor Crack Detection On Airframe Systems, Kevin J. Lin

Theses and Dissertations

In 2008, the Department of Defense published a guidebook for a methodology named Condition-Based Maintenance Plus (CBM+) which capabilities include improving productivity, shortening maintenance cycles, lowering costs, and increasing availability and reliability. This push replaces existing inspection criteria, often conducted as non-destructive testing (NDT), with structural health monitoring (SHM) systems. The SHM system addressed utilizes guided Lamb waves generated by piezoelectric wafer active sensors (PWAS) to detect the existence, size, and location of damage from through-thickness cracks around a rivet hole. The SHM field lacks an experiment testing how small changes in receiver sensor distances affect damage detection. In addition ...


Displacement Damage Effects In Gesn Light Emitting Diodes, Kevin K. Choe Mar 2019

Displacement Damage Effects In Gesn Light Emitting Diodes, Kevin K. Choe

Theses and Dissertations

Potential future use on Earth-orbiting satellites calls for investigation into the suitability of GeSn based photonic devices in high energy proton environments. The electroluminescence (EL) intensity of Ge1-xSnx (x = 0, 0.02, 0.069, and 0.094) light emitting diodes was measured before and after irradiation by 2 MeV protons at relatively high fluence levels. The results showed that GeSn devices with higher Sn content were up to 10 times more resistant against proton displacement damage than the pure Ge (x = 0) devices. As Sn concentration increased, the band gap decreased, and V-P hole trap energy level moved further from ...


Orthogonal Frequency Division Multiplexed Waveform Effects On Passive Bistatic Radar, Forrest D. Taylor Mar 2019

Orthogonal Frequency Division Multiplexed Waveform Effects On Passive Bistatic Radar, Forrest D. Taylor

Theses and Dissertations

Communication waveforms act as signals of opportunity for passive radars. However, these signals of opportunity suffer from range-Doppler processing losses due to their high range sidelobes and pulse-diverse waveform aspects. Signals such as the long term evolution (LTE) encode information within the phase and amplitude of the waveform. This research explores aspects of the LTE, such as the encoding scheme and bandwidth modes on passive bistatic Doppler radar. Signal space-time adaptive processing (STAP) performance is evaluated and parameters are compared with the signal to interference-plus-noise ratio (SINR) metric.


Motivating Airmen To Engage With Technical Education: Experimentation And Analysis Using Modern Gamification Techniques, Landon G.M. Tomcho Mar 2019

Motivating Airmen To Engage With Technical Education: Experimentation And Analysis Using Modern Gamification Techniques, Landon G.M. Tomcho

Theses and Dissertations

The development and integration of computer systems into today’s society and the subsequent growth of cyber as a warfighting domain has led to changes in military and civilian conflict. Several traits unique to cyber, including disruption and fast pace of change, has led to issues never before seen in the military environment, especially with educating and training. A new approach that leverages crowd-sourced content has been proposed. This approach relies on motivating military members to voluntarily engage with technical (cyber) education. The application of gamification, a design practice aimed at increasing user engagement by targeting core motivators in humans ...


Plasma Treatment Method For Ohmic Contacts On Zinc Oxide Thin Film Transistors, Blaine Z. Underwood Mar 2019

Plasma Treatment Method For Ohmic Contacts On Zinc Oxide Thin Film Transistors, Blaine Z. Underwood

Theses and Dissertations

This research utilizes plasma treatments as a method to decrease the contact resistance on zinc oxide (ZnO) thin film transistors (TFT). In recent years, researchers have achieved gigahertz RF switch cutoff frequency with ZnO TFTs. To further increase the cutoff frequency, the total resistance of this device must be minimized. Modern ZnO TFTs are fabricated with submicron channel lengths, which contains minimal resistance due to the TFT channel, making contact resistance significant to the total resistance of the device. This research developed a method to integrate plasma treatments into the fabrication of ZnO TFT to decrease the contact resistance, thus ...


A Mems Dual Vertical Electrometer And Electric Field-Mill, George C. Underwood Mar 2019

A Mems Dual Vertical Electrometer And Electric Field-Mill, George C. Underwood

Theses and Dissertations

Presented is the first iteration of a Microelectromechanical System (MEMS) dual vertical electrometer and electric field-mill (EFM). The device uses a resonating structure as a variable capacitor that converts the presence of a charge or field into an electric signal. Previous MEMS electrometers are lateral electrometers with laterally spaced electrodes that resonate tangentially with respect to each other. Vertical electrometers, as the name suggests, have vertically spaced electrodes that resonate transversely with respect to each other. The non-tangential movement reduces damping in the system. Both types demonstrate comparable performance, but the vertical electrometer does so at a fraction of the ...


Multi-Sensor Data Fusion Between Radio Tomographic Imaging And Noise Radar, Christopher Vergara Mar 2019

Multi-Sensor Data Fusion Between Radio Tomographic Imaging And Noise Radar, Christopher Vergara

Theses and Dissertations

The lack of situational awareness within an operational environment is a problem that carries high risk and expensive consequences. Radio Tomographic Imaging (RTI) and noise radar are two proven technologies capable of through-wall imaging and foliage penetration. The intent of this thesis is to provide a proof of concept for the fusion of data from RTI and noise radar. The output of this thesis will consist of a performance comparison between the two technologies followed by the derivation of a fusion technique to produce a single image. Proposals have been made for the integration of multiple-input multiple-output (MIMO) radar with ...


Confirmation Bias Estimation From Electroencephalography With Machine Learning, Micah Villarreal Mar 2019

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.


Two-On-One Pursuit With A Non-Zero Capture Radius, Patrick J. Wasz Mar 2019

Two-On-One Pursuit With A Non-Zero Capture Radius, Patrick J. Wasz

Theses and Dissertations

In this paper, we revisit the "Two Cutters and Fugitive Ship" differential game that was addressed by Isaacs, but move away from point capture. We consider a two-on-one pursuit-evasion differential game with simple motion and pursuers endowed with circular capture sets of radius l > 0. The regions in the state space where only one pursuer effects the capture and the region in the state space where both pursuers cooperatively and isochronously capture the evader are characterized, thus solving the Game of Kind. Concerning the Game of Degree, the algorithm for the synthesis of the optimal state feedback strategies of the ...


A Quantitative Analysis Of The Fusion Of 3-D Scanning Lidar Systems And 2-D Imaging Systems, Michael F. Milton Jr. Mar 2019

A Quantitative Analysis Of The Fusion Of 3-D Scanning Lidar Systems And 2-D Imaging Systems, Michael F. Milton Jr.

Theses and Dissertations

This research will demonstrate the feasibility of fusing the superior spatial resolution of a 2-D imaging system with the precise range to target information of a 3-D imaging system to create a LIDAR imaging system that can accurately find what and where a target is. The 3-D imaging system will use a scanning method as opposed to a flash method that has been used in similar research. The goal of this research is to improve performance of scanning LIDAR so it has better spatial resolution. The research in this thesis proves that incorporating 2-D imaging data into 3-D scanning LIDAR ...


Event-Based Visual-Inertial Odometry On A Fixed-Wing Unmanned Aerial Vehicle, Kaleb J. Nelson Mar 2019

Event-Based Visual-Inertial Odometry On A Fixed-Wing Unmanned Aerial Vehicle, Kaleb J. Nelson

Theses and Dissertations

Event-based cameras are a new type of visual sensor that operate under a unique paradigm. These cameras provide asynchronous data on the log-level changes in light intensity for individual pixels, independent of other pixels' measurements. Through the hardware-level approach to change detection, these cameras can achieve microsecond fidelity, millisecond latency, ultra-wide dynamic range, and all with very low power requirements. The advantages provided by event-based cameras make them excellent candidates for visual odometry (VO) for unmanned aerial vehicle (UAV) navigation. This document presents the research and implementation of an event-based visual inertial odometry (EVIO) pipeline, which estimates a vehicle's ...


Machine Translation With Image Context From Mandarin Chinese To English, Brooke E. Johnson Mar 2019

Machine Translation With Image Context From Mandarin Chinese To English, Brooke E. Johnson

Theses and Dissertations

Despite ongoing improvements in machine translation, machine translators still lack the capability of incorporating context from which source text may have been derived. Machine translators use text from a source language to translate it into a target language without observing any visual context. This work aims to produce a neural machine translation model that is capable of accepting both text and image context as a multimodal translator from Mandarin Chinese to English. The model was trained on a small multimodal dataset of 700 images and sentences, and compared to a translator trained only on the text associated with those images ...


Monocular Visual Odometry For Fixed-Wing Small Unmanned Aircraft Systems, Kyung M. Kim Mar 2019

Monocular Visual Odometry For Fixed-Wing Small Unmanned Aircraft Systems, Kyung M. Kim

Theses and Dissertations

The popularity of small unmanned aircraft systems (SUAS) has exploded in recent years and seen increasing use in both commercial and military sectors. A key interest area for the military is to develop autonomous capabilities for these systems, of which navigation is a fundamental problem. Current navigation solutions suffer from a heavy reliance on a Global Positioning System (GPS). This dependency presents a significant limitation for military applications since many operations are conducted in environments where GPS signals are degraded or actively denied. Therefore, alternative navigation solutions without GPS must be developed and visual methods are one of the most ...


Unresolved Object Detection Using Synthetic Data Generation And Artificial Neural Networks, Yong U. Sinn Mar 2019

Unresolved Object Detection Using Synthetic Data Generation And Artificial Neural Networks, Yong U. Sinn

Theses and Dissertations

This research presents and solves constrained real-world problems of using synthetic data to train artificial neural networks (ANNs) to detect unresolved moving objects in wide field of view (WFOV) electro-optical/infrared (EO/IR) satellite motion imagery. Objectives include demonstrating the use of the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET) as an effective tool for generating EO/IR motion imagery representative of real WFOV sensors and describing the ANN architectures, training, and testing results obtained. Deep learning using a 3-D convolutional neural network (3D ConvNet), long short term memory (LSTM) network, and U-Net are used ...


3-D Multifunctional Sensors Fabricated On Fiber Tips Using A Two-Photon Polymerization Process, Jonathan W. Smith Mar 2019

3-D Multifunctional Sensors Fabricated On Fiber Tips Using A Two-Photon Polymerization Process, Jonathan W. Smith

Theses and Dissertations

This thesis conducts research involving designing, fabricating, and testing optical fiber tip refractive index sensors. The fabrication process used for these sensors is a two-photon polymerization process utilizing a photo sensitive polymer. Unlike planar lithography, this fabrication process allows the creation of arbitrary shapes with a great degree of freedom. Three different fiber tip sensors were fabricated and tested. The first is a flat surfaced single cavity Fabry-Pérot interferometer (FPI) device, the second is a flat surfaced double cavity FPI device, and the final is a confocal surfaced double cavity FPI device. These sensors are tested for thermal radiation and ...


Examining Effectiveness Of Web-Based Internet Of Things Honeypots, Lukas A. Stafira Mar 2019

Examining Effectiveness Of Web-Based Internet Of Things Honeypots, Lukas A. Stafira

Theses and Dissertations

The Internet of Things (IoT) is growing at an alarming rate. It is estimated that there will be over 25 billion IoT devices by 2020. The simplicity of their function usually means that IoT devices have low processing power, which prevent them from having intricate security features, leading to vulnerabilities. This makes IoT devices the prime target of attackers in the coming years. Honeypots are intentionally vulnerable machines that run programs which appear as a vulnerable device to a would-be attacker. They are placed on a network to entice and trap an attacker and then gather information on them, including ...


Direct Path Interference Suppression And Received Signal Processing For Ofdm Passive Radar, Aileen Nundu Mar 2019

Direct Path Interference Suppression And Received Signal Processing For Ofdm Passive Radar, Aileen Nundu

Theses and Dissertations

Passive bistatic radar (PBR) is a fairly active area of research due to the opportunities offered by the ability to use emitters of opportunity for target detection and tracking as well as Synthetic Aperture Radar (SAR) imaging. There is an increasing variety and availability of signals that can be exploited for passive radar and there is also the advantage of angular diversity offered by the bistatic geometry and the potential for stealth operations afforded a passive receiver. Notwithstanding its merits, PBR is complicated by the inevitable presence of Direct Path Interference (DPI) from the transmitter to the receiver, which can ...


Uranium Dioxide Actinide Detection Device Support Design For Space Applications, Jennifer N. Ramos Mar 2019

Uranium Dioxide Actinide Detection Device Support Design For Space Applications, Jennifer N. Ramos

Theses and Dissertations

Attention concerning the proliferation of nuclear weapons and materials has generated many research initiatives to detect, identify, and locate radiation emitted by actinides. In support of this effort, the `Fission Induced Neutron Detection of Nuclear Materials' (FIND'NM) program was established to comprise a joint effort to explore this issue. The objective also co-extends the Air Force Research Laboratory uranium dioxide (UO2) detection sample growth, characterization, and electrical interface research. AFIT's study accomplishes the design and fabrication of a space-tolerant PCB to support a UO2-based neutron detector. Further design considerations are made with the expectation of the platform to ...


Characterization Of Metal Contacts On Hydrothermally Synthesized Uranium Dioxide For Novel Semiconductor Applications, Tory E. Robinson Mar 2019

Characterization Of Metal Contacts On Hydrothermally Synthesized Uranium Dioxide For Novel Semiconductor Applications, Tory E. Robinson

Theses and Dissertations

This research is focused on determining which metals or combinations of metals form effective electrical contacts on hydrothermally synthesized UO2 substrates to allow for additional work in characterization of the material as well as the feasibility of its use in semiconductor devices such as solid-state neutron detectors. A methodology was established for selection of candidate metals. Target mixtures composed of Au, Ag, Pt, and Mg were chosen along with several single-metals. Thin metal films were deposited onto tungsten probe tips and hydrothermally synthesized UO2 samples to allow for analysis of mechanical and deposited contact to the substrates through I-V measurements.


Analysis Of Satellite Timing And Navigation Receiver Pseudorange Biases Due To Spreading Code Puncturing And Phase Optimized Constant Envelope Transmission, Nathaniel J. Raquet Mar 2019

Analysis Of Satellite Timing And Navigation Receiver Pseudorange Biases Due To Spreading Code Puncturing And Phase Optimized Constant Envelope Transmission, Nathaniel J. Raquet

Theses and Dissertations

There is a desire for future GPS satellites to be software-defined to enable greater operational flexibility and adapt to a variety of current and future threats. This includes implementing new modulation techniques such as phase optimized constant envelope transmission (POCET) and asymmetric signal authentication methods such as chips message robust authentication (Chimera). Any new GPS signal transmitted must be backwards compatible with the millions of receivers already in use. This thesis shows a variety of tests performed to demonstrate the effects of Chimera and POCET-enabled signals. It is shown through actual radio frequency signal generation, testing the response of current-generation ...


A Blockchain-Based Anomalous Detection System For Internet Of Things Devices, Joshua K. Mosby Mar 2019

A Blockchain-Based Anomalous Detection System For Internet Of Things Devices, Joshua K. Mosby

Theses and Dissertations

Internet of Things devices are highly susceptible to attack, and owners often fail to realize they have been compromised. This thesis describes an anomalous-based intrusion detection system that operates directly on Internet of Things devices utilizing a custom-built Blockchain. In this approach, an agent on each node compares the node's behavior to that of its peers, generating an alert if they are behaving differently. An experiment is conducted to determine the effectiveness at detecting malware. Three different code samples simulating common malware are deployed against a testbed of 12 Raspberry Pi devices. Increasing numbers are infected until two-thirds of ...


Micro-Contacts With 3-D Surfaces Made With Grayscale Lithography, Paul L.J. Michaud Mar 2019

Micro-Contacts With 3-D Surfaces Made With Grayscale Lithography, Paul L.J. Michaud

Theses and Dissertations

MEMS switches show advantages over FET transistors and PIN diodes for switching applications due to low contact resistance, high linearity, low power use, better isolation and lower insertion loss. The switches have not replaced FETs or PIN diodes due to perceived limitations in their reliability and the need for stable contact resistance. In order to create switches acceptable for industry applications, research on micro-contact physics and failure mechanisms of micro-contacts is necessary to develop durable contact surfaces. The aim of this research was to design and fabricate micro-contacts with three-dimensional surfaces using grayscale lithography. The goal was to create devices ...


Active Control Of A Morphing Wing Aircraft And Failure Analysis For System Reliability, Madison J. Montgomery Mar 2019

Active Control Of A Morphing Wing Aircraft And Failure Analysis For System Reliability, Madison J. Montgomery

Theses and Dissertations

A morphing wing aircraft has the ability to increase the efficiency of an aircraft by better optimizing lift and drag characteristics during a flight. A morphing wing UAV was designed and constructed by AFRL/RQVS and required a means of control and method of characterizing the performance of the aircraft through flight testing. This research presents the design and construction of a control system capable of adjusting the morphing wing shape based on pilot commands and current flight status. The control system was tested and improved following a flight test crash utilizing failure mode analysis.


A Framework For Cyber Vulnerability Assessments Of Infiniband Networks, Daryl W. Schmitt Mar 2019

A Framework For Cyber Vulnerability Assessments Of Infiniband Networks, Daryl W. Schmitt

Theses and Dissertations

InfiniBand is a popular Input/Output interconnect technology used in High Performance Computing clusters. It is employed in over a quarter of the world’s 500 fastest computer systems. Although it was created to provide extremely low network latency with a high Quality of Service, the cybersecurity aspects of InfiniBand have yet to be thoroughly investigated. The InfiniBand Architecture was designed as a data center technology, logically separated from the Internet, so defensive mechanisms such as packet encryption were not implemented. Cyber communities do not appear to have taken an interest in InfiniBand, but that is likely to change as ...


Autonomous Association Of Geo Rso Observations Using Deep Neural Networks, Ian W. Mcquaid Mar 2019

Autonomous Association Of Geo Rso Observations Using Deep Neural Networks, Ian W. Mcquaid

Theses and Dissertations

Ground-based non-resolved optical observations of resident space objects (RSOs) in geosynchronous orbit (GEO) represent the majority of the space surveillance network’s (SSN’s) deep-space tracking. Reliable and accurate tracking necessitates temporal separation of the observations. This requires that subsequent observations be associated with prior observations of a given RSO before they can be used to create or refine that RSO’s ephemeris. The use of astrometric data (e.g. topocentric angular position) alone for this association task is complicated by RSO maneuvers between observations, and by RSOs operating in close proximity. Accurately associating an observation with an RSO thus ...


A Multi-Vehicle Cooperative Localization Approach For An Autonomy Framework, Edwin A. Mora Mar 2019

A Multi-Vehicle Cooperative Localization Approach For An Autonomy Framework, Edwin A. Mora

Theses and Dissertations

Offensive techniques produced by technological advancement present opportunities for adversaries to threaten the operational advantages of our joint and allied forces. Combating these new methodologies requires continuous and rapid development towards our own set of \game-changing" technologies. Through focused development of unmanned systems and autonomy, the Air Force can strive to maintain its technological superiority. Furthermore, creating a robust framework capable of testing and evaluating the principles that define autonomy allows for the exploration of future capabilities. This research presents development towards a hybrid reactive/deliberative architecture that will allow for the testing of the principles of task, cognitive, and ...


Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes Mar 2019

Electromagnetic Characterization Of Conductor-Backed Media Using Stepped Rectangular Waveguide, Avian Y. Hughes

Theses and Dissertations

A new single stepped-iris waveguide technique is used to nondestructively determine the permittivity and permeability of conductor-backed media. This thesis will demonstrate a proof-of-concept that obtains two independent reflection measurements with a magnetic radar absorbing material (magRAM). Using a two measurement procedure, in which, the first measurement will apply a single rectangular waveguide to a known conductor-backed absorbing material under test (MUT) and the second measurement will insert a stepped-iris in between the single rectangular waveguide and MUT reducing the aperture to retrieve two independent electromagnetic properties (i.e. permittivity and permeability). The theoretical reflection coefficients are obtained using a ...


A Focal Plane Array And Electronics Model For Cmos And Ccd Sensors In The Afit Sensor And Scene Emulation Tool (Asset), Fernando D. Fernandez Mar 2019

A Focal Plane Array And Electronics Model For Cmos And Ccd Sensors In The Afit Sensor And Scene Emulation Tool (Asset), Fernando D. Fernandez

Theses and Dissertations

Electro-optical and infrared (EO/IR) sensor models are useful tools that can facilitate understanding a system's behavior without expensive and time-consuming testing of an actual system. EO/IR models are especially important to the military industry where truth data is required but is sometimes impractical to obtain through experimentation due to expense or difficulties in procuring hardware. This work describes implementation of a focal plane array (FPA) model of charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) photodetectors as a component in the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET). The FPA model covers ...


Improved Fabrication For Micromirror Arrays, Enoc Flores Mar 2019

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 ...