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

Electrical and Computer Engineering Commons™

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

Air Force Institute of Technology

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 121 - 150 of 1329

Full-Text Articles in Electrical and Computer Engineering

Towards The Integration Of Ferroelectric Negative Capacitance With Gallium Oxide Semiconductors For High Power Applications, Guillermo A. Salcedo Mar 2022

Towards The Integration Of Ferroelectric Negative Capacitance With Gallium Oxide Semiconductors For High Power Applications, Guillermo A. Salcedo

Theses and Dissertations

Gallium oxide is a relatively new semiconductor material with characteristics auspicious for high frequency and high-voltage applications. Although several research groups have already demonstrated radio-frequency (RF) devices on Ga2O3 with remarkable features, there is still room for improvement. For instance, the operating frequency of RF field-effect transistors (FET) decreases with the parasitic capacitance, which can be counteracted by higher gate capacitance. Implementing ferroelectric dielectrics with suitable parameters in Ga2O3 FET promises to enhance the gate capacitance and therefore increase operating frequency. This work investigated the effect of various factors (film composition, film thickness, TiN …

Go to article

Utilization Of Characteristic Modal Analysis For Antenna Design Needed For An Afit Satellite, Scott C. Podlogar Mar 2022

Utilization Of Characteristic Modal Analysis For Antenna Design Needed For An Afit Satellite, Scott C. Podlogar

Theses and Dissertations

Antenna design is a pervasive, growing field for electrical engineers. As the number of new materials and techniques increase so too does the demand and requirements pushing forth new innovative ideas. Among these ideas is a leading edge analytic technique called Characteristic Modal Analysis (CMA) originally credited to Garbacz and Turpin. CMA works to break down the current distribution along a structure in a way that can offer great insights into how that structure operates as an antenna. This technique has great merits in post design analytics but it is rarely seen to be integrated into the design process. This …

Go to article

Design Study For An Antenna Radar Cross Section Measurement Test Fixture, Wayne C. Kreimeyer Mar 2022

Design Study For An Antenna Radar Cross Section Measurement Test Fixture, Wayne C. Kreimeyer

Theses and Dissertations

Military technology requires equipment to be undetected by adversaries. Stealth aircraft are designed to be undetected through electromagnetic means by minimizing a return signature called the RCS. Therefore, it is essential to understand how antennas, which are necessary for communication, affect the overall RCS of the aircraft. The antenna is measured in a compact RADAR range. The antenna needs a structure to support it, also referred to as a test fixture, that does not interfere with the measuring process of the antenna’s RCS. This thesis set out to get the lowest RCS possible of a test fixture by evaluating different …

Go to article

Monocular Camera Localization Using A Bag Of Visual Words From Virtual World Data, Joshua A. Rinaldi Mar 2022

Monocular Camera Localization Using A Bag Of Visual Words From Virtual World Data, Joshua A. Rinaldi

Theses and Dissertations

The Visual Localization problem is the question of how to use visual information to determine the location of the camera that captured that data. The wide availability and low price of RGB cameras has made this useful in many fields such as SLAM, SAM and AR. This research seeks to determine if a BOVW can adequately overcome repetitious features in indoor environments and be effectively incorporated into a VL pipeline.

Go to article

Deep Learning Techniques To Estimate 3d Position In Stereoscopic Imagery, Jonathan I. Nicholson Mar 2022

Deep Learning Techniques To Estimate 3d Position In Stereoscopic Imagery, Jonathan I. Nicholson

Theses and Dissertations

Current AAR efforts utilize machine vision algorithms to estimate the pose of a receiver aircraft. However, these algorithms are dependent on several conditions such as the availability of precise 3D aircraft models; the accuracy of the pipeline significantly degrades in the absence of high-quality information given beforehand. We propose a deep learning architecture that estimates the 3D position of an object based on stereoscopic imagery. We investigate the use of both machine learning techniques and neural networks to directly regress the 3D position of the receiver aircraft. We present a new position estimation framework that is based on the differences …

Go to article

Evaluation Of The Armas-Som Framework With Real Data, Brandon M. Blakely Mar 2022

Evaluation Of The Armas-Som Framework With Real Data, Brandon M. Blakely

Theses and Dissertations

The ARMAS framework was created with the goal of developing a framework for all-source sensors which is able to combine detection, identification, calibration, model selection, and independent evaluation into a single system. Stable Observability Monitoring (SOM), augments the original ARMAS framework by enabling ARMAS to detect whether or not its Fault Detection and Exclusion (FDE) capabilities can be trusted and when additional sensor information is required to maintain resiliency. While previously tested with simulated sensor data, SOM has yet to be tested with real-life sensor data. Furthermore, ARMAS has only been tested with real-life GNSS data. This work expands on …

Go to article

Malware Detection Using Electromagnetic Side-Channel Analysis, Matthew A. Bergstedt Mar 2022

Malware Detection Using Electromagnetic Side-Channel Analysis, Matthew A. Bergstedt

Theses and Dissertations

Many physical systems control or monitor important applications without the capacity to monitor for malware using on-device resources. Thus, it becomes valuable to explore malware detection methods for these systems utilizing external or off-device resources. This research investigates the viability of employing EM SCA to determine whether a performed operation is normal or malicious. A Raspberry Pi 3 was set up as a simulated motor controller with code paths for a normal or malicious operation. While the normal path only calculated the motor speed before updating the motor, the malicious path added a line of code to modify the calculated …

Go to article

Detection And Identification Of Cellphone Emitted Light Detection And Ranging Light In Security Camera Video Footage, Tristan V. Creek Mar 2022

Detection And Identification Of Cellphone Emitted Light Detection And Ranging Light In Security Camera Video Footage, Tristan V. Creek

Theses and Dissertations

The prevalence of Light Detection and Ranging (LiDAR) sensors in consumer cellphones has ushered in an era of access to technologies previously inaccessible to the average person. Although LiDAR sensors emit light in the infrared spectrum invisible to the naked eye, many security cameras possess the ability to capture infrared light reflected off surfaces to detect LiDAR light in an environment. Once detected and recorded to video footage, current classification methods fail to identify the LiDAR light. Therefore, this research develops a methodology to detect LiDAR light in security camera video footage and identify it as cellphone LiDAR. A proposed …

Go to article

Applications Of A Lightning Proxy To Generate Synthetic Lightning For Use In Physics-Based Image-Chain Models, Bryan G. Castro Mar 2022

Applications Of A Lightning Proxy To Generate Synthetic Lightning For Use In Physics-Based Image-Chain Models, Bryan G. Castro

Theses and Dissertations

A method of generating synthetic lightning through the use of a convective available potential energy (CAPE) times precipitation rate (P) proxy is applied over three distinct climatological zones of the world for a single warm season: central and southern AZ of the United States, central Cuba, and North Korea. Global Forecast System (GFS) 0.25° by 0.25° forecast data for June, July, and August of 2019 is used to provide 6-hourly CAPE and precipitation rate, while Global Lightning Dataset (GLD360) data for the period 2016 to 2020 is used to provide observed lightning strokes. A five-year lightning climatology study is conducted …

Go to article

Relative Magnetic Position And Rotation Sensor Assisted Dual-Foot Pedestrian Dead Reckoning, Jenario Y. Johnson Mar 2022

Relative Magnetic Position And Rotation Sensor Assisted Dual-Foot Pedestrian Dead Reckoning, Jenario Y. Johnson

Theses and Dissertations

The use of wearable foot-based inertial measurement units (IMUs) incorporated in a navigation system can address the problem of single-person location tracking in situations and environments where GPS signals may be unavailable or inconsistent. This Pedestrian Dead Reckoning (PDR) approach enables standalone personal tracking. A notable solution involves using inertial measurement units (IMUs) in a filter to apply zero-velocity updates to a Kalman filter to get a position solution. This paper continues on the path of the former method by investigating the feasibility of PDR using a pair of low cost IMUs along with a pair of relative position and …

Go to article

Considering Dds In The Domain Of Dis - Pros And Cons, Nathaniel R. Peck Mar 2022

Considering Dds In The Domain Of Dis - Pros And Cons, Nathaniel R. Peck

Theses and Dissertations

DIS is a legacy IEEE standard for defining and structuring PDUs in large scale distributed wargames. Although the standard specifies various QoS appropriate for certain PDUs, a one-size-fits-all transport strategy is traditionally employed via UDP. Since the inception of DIS, the OMG has produced a standard for a DDS which has been implemented by several middleware vendors. DDS middleware offers an abstraction for network communications that allows applications and developers to easily employ configurable QoS by topic. Adoption and use of these QoS in DIS applications may introduce greater compliance with the IEEE standard and enrich the service features available …

Go to article

Global Sporadic-E Climatological Analysis Using Gps Radio Occultation And Ionosonde Data, Travis J. Hodos Mar 2022

Global Sporadic-E Climatological Analysis Using Gps Radio Occultation And Ionosonde Data, Travis J. Hodos

Theses and Dissertations

A climatology of sporadic-E (Es) derived from a combined data set of GPS radio occultation (GPS-RO) and ground-based ionosonde soundings is presented for the period from September 2006 to February 2019. The ionosonde soundings were measured using the Lowell Digisonde International (LDI) Global Ionosphere Radio Observatory (GIRO) network consisting of 65 sites and 13,141,060 total soundings. The GPS-RO observations were taken aboard the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites and processed using two binary Es detection algorithms, totaling 9,072,922 occultations. The first algorithm is an S4 amplitude threshold calibrated to the occurrence of any blanketing Es …

Go to article

Uav Positioning Data Determined Via Aruco Tags For Aircraft Surface Inspection, Caleb B. Schmidt Mar 2022

Uav Positioning Data Determined Via Aruco Tags For Aircraft Surface Inspection, Caleb B. Schmidt

Theses and Dissertations

Aircraft are frequently inspected to ensure that military and civilian safety standards are adhered to. These inspections are performed pre- and post-flight and are currently performed by trained maintenance personnel. This work furthers the automation of aircraft surface inspection by using ArUco tags to determine the position of the UAV during aerial inspections. The ArUco tag based position data was then compared to a highly accurate infrared motion capture system to determine the viability of this for accurate positioning of the vehicle. This work includes flight experiments with two different UAVs to perform a system viability comparison.

Go to article

A Comparison Of Sporadic-E Occurrence Rates Using Gps Radio Occultation And Ionosonde Measurements, Rodney Carmona, Omar A. Nava, Eugene V. Dao, Daniel J. Emmons Jan 2022

A Comparison Of Sporadic-E Occurrence Rates Using Gps Radio Occultation And Ionosonde Measurements, Rodney Carmona, Omar A. Nava, Eugene V. Dao, Daniel J. Emmons

Faculty Publications

Sporadic-E (Es) occurrence rates from Global Position Satellite radio occultation (GPS-RO) measurements have shown to vary by a factor of five between studies, motivating the need for a comparison with ground-based measurements. In an attempt to find accurate GPS-RO techniques for detecting Es formation, occurrence rates derived using five previously developed GPS-RO techniques are compared to ionosonde measurements over an eight-year period from 2010–2017. GPS-RO measurements within 170 km of a ionosonde site are used to calculate Es occurrence rates and compared to the ground-truth ionosonde measurements. The techniques are compared individually for each ionosonde site …

Go to article

Magneto-Exothermic Catalytic Chemical Reaction Along A Curved Surface, Muhammad Ashraf, Uzma Ahmad, Saqib Zia, Rama S. R. Gorla, Amnah S. Al-Johani, Ilyas Khan, Mulugeta Andualem Jan 2022

Magneto-Exothermic Catalytic Chemical Reaction Along A Curved Surface, Muhammad Ashraf, Uzma Ahmad, Saqib Zia, Rama S. R. Gorla, Amnah S. Al-Johani, Ilyas Khan, Mulugeta Andualem

Faculty Publications

In the current study, the physical behavior of the boundary layer flows along a curved surface owing exothermic catalytic chemical reaction, and the magnetic field is investigated. The mathematical model comprised of a part of momentum, energy, and mass equations, which are solved using a finite difference method along with primitive variable formulation. Numerical solutions, using the method of quantitative differentiation, are made with the appropriate choice of dimensionless parameters. Analysis of the results obtained shows that the field temperature and flow of fluids are strongly influenced by the combined effects of catalytic chemical reactions and the magnetic field. The …

Go to article

Machine Learning Land Cover And Land Use Classification Of 4-Band Satellite Imagery, Lorelei Turner, Torrey J. Wagner, Paul Auclair, Brent T. Langhals Jan 2022

Machine Learning Land Cover And Land Use Classification Of 4-Band Satellite Imagery, Lorelei Turner, Torrey J. Wagner, Paul Auclair, Brent T. Langhals

Faculty Publications

Land-cover and land-use classification generates categories of terrestrial features, such as water or trees, which can be used to track how land is used. This work applies classical, ensemble and neural network machine learning algorithms to a multispectral remote sensing dataset containing 405,000 28x28 pixel image patches in 4 electromagnetic frequency bands. For each algorithm, model metrics and prediction execution time were evaluated, resulting in two families of models; fast and precise. The prediction time for an 81,000-patch group of predictions wasmodels, and >5s for the precise models, and there was not a significant change in prediction time when a …

Go to article

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Dec 2021

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

Go to article

On The Synthesis Of Optimal Control Laws, Meir Pachter, Isaac E. Weintraub Dec 2021

On The Synthesis Of Optimal Control Laws, Meir Pachter, Isaac E. Weintraub

Faculty Publications

In this paper we advocate for Isaacs' method for the solution of differential games to be applied to the solution of optimal control problems. To make the argument, the vehicle employed is Pontryagin's canonical optimal control example, which entails a double integrator plant. However, rather than controlling the state to the origin, we correctly require the end state to reach a terminal set that contains the origin in its interior. Indeed, in practice, it is required to control to a prescribed tolerance rather than reach a desired end state; achieving tight tolerances is expensive, and from a theoretical point of …

Go to article

System, Method And Apparatus For Recovering Polarization Radar Data, Julie A. Jackson, Forest Lee-Elkin Dec 2021

System, Method And Apparatus For Recovering Polarization Radar Data, Julie A. Jackson, Forest Lee-Elkin

AFIT Patents

A method and apparatus that measure M coupled channels of radar polarization data (ỹ), that is a subset, which is less than the full set of received coupled channels. Sparse recovery operations are performed on the measured M coupled channels of radar polarization data (ỹ) and a representation of a set of more than M channels of radar polarization data is generated from the sparse recovery performed on the subset of coupled channels.

Go to article

Ionospheric F-Layer Dipole Flute Instability Effects On Electromagnetic Scattering In A Magnetohydrodynamic Plasma, Andrew J. Knisely Nov 2021

Ionospheric F-Layer Dipole Flute Instability Effects On Electromagnetic Scattering In A Magnetohydrodynamic Plasma, Andrew J. Knisely

Theses and Dissertations

The ionosphere has significant impact on radio frequency (RF) applications such as satellites, over-the-horizon radar, and commercial communication systems. The dynamic processes effecting the behavior of the ionic content leads to a variety of instabilities that adversely affect the quality of RF signals. In the F-layer ionosphere, flute instability persists, appearing as two radial regions of high and low density perturbations elongated along the earth's geomagnetic field lines. The sizes of flute structures are comparable to the wavelengths in the high frequency spectrum. The objective is to characterize the high frequency scattering of an incident field by developing a 3D …

Go to article

Method Of Making Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Oct 2021

Method Of Making Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A method of making passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes forming a three-dimensional microscopic optical structure on a cleaved tip of an optical fiber that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

Go to article

Evaluating Testing Procedures For Openflow Controller Network Re-Provisioning Time, Steven J. Jensen Sep 2021

Evaluating Testing Procedures For Openflow Controller Network Re-Provisioning Time, Steven J. Jensen

Theses and Dissertations

Software-Defined Networking promises several advantages over traditional networking architectures, but has seen little adoption. Recently codified controller evaluation methodologies have seen little validation without strong statistical analysis of the results. The research developed an environment testing implementing a published Network Re-provisioning Time methodology to evaluate five OpenFlow controllers. The methodology is strong with required parameters but had issues with some edge cases. Further refinement and adding a convergence metric may close the gaps.

Go to article

Collaborative All-Source Navigation With Integrity, Jonathon S. Gipson Sep 2021

Collaborative All-Source Navigation With Integrity, Jonathon S. Gipson

Theses and Dissertations

The novel ARMAS-SOM framework fuses collaborative all-source sensor information in a resilient manner with fault detection, exclusion, and integrity solutions recognizable to a GNSS user. This framework uses a multi-filter residual monitoring approach for fault detection and exclusion and is augmented with an additional "observability" EKF sub-layer for resilience. We monitor the a posteriori state covariances in this sub-layer to provide intrinsic awareness when navigation state observability assumptions required for integrity are in danger. This is used to selectively augment the framework with offboard information to preserve resilience. By maintaining split parallel collaborative and proprioceptive estimation instances and employing a …

Go to article

Characterization Of Anisotropic Materials Using Scattered Field Measurements, Hirsch M. Chizever Sep 2021

Characterization Of Anisotropic Materials Using Scattered Field Measurements, Hirsch M. Chizever

Theses and Dissertations

This research uses monostatic far-zone scattered field measurements to estimate the permittivity of biaxial materials at X-Band. Utilizing Radar Cross Section (RCS) measurement techniques, this effort examines the efficacy of whole-sample TEM illumination in the estimation of anisotropic permittivity, in contrast with traditional subsample illumination methods. The research examines the impact that dielectric supports have on measurement error and uncertainty in permittivity estimates. Following an incremental approach, the research first demonstrates successful estimation of permittivity for isotropic spheres followed by a Teflon isotropic cube. Finally, the method is applied to uniaxial and biaxial cubes whose anisotropic permittivity is validated through …

Go to article

New Methods In Wavelet Analysis For Applications Of The Wavelet Transform, Jeffrey D. Williams Sep 2021

New Methods In Wavelet Analysis For Applications Of The Wavelet Transform, Jeffrey D. Williams

Theses and Dissertations

A commonality in the many applications and domains where signal processing (SP)is applied is the detection of events. Detection in SP requires the identification of the occurrence of an event, within a signal, and distinguishing the occurrence from no event. In a classical application of SP, seismologists seek to detect abnormalities in an electromagnetic (EM) signal to detect or not detect the occurrence of an earthquake, represented as an anomalous EM pulse. Since many signals are noisy, such as those produced by a seismograph, it can be challenging to distinguish a significant EM pulse from incident noise. In SP, smoothing …

Go to article

Efficient, Dual-Particle Directional Detection System Using A Rotating Scatter Mask, Robert Olesen, Bryan V. Egner, Darren E. Holland, Valerie Martin, James E. Bevins, Larry W. Burggraf, Buckley E. O'Day Iii Jul 2021

Efficient, Dual-Particle Directional Detection System Using A Rotating Scatter Mask, Robert Olesen, Bryan V. Egner, Darren E. Holland, Valerie Martin, James E. Bevins, Larry W. Burggraf, Buckley E. O'Day Iii

AFIT Patents

A directional radiation detection system and an omnidirectional radiation detector. The omnidirectional radiation detector detects radiation comprising at least one of: (i) gamma rays; and (ii) neutron particles. A radiation scatter mask (RSM) of the radiation detection system includes a rotating sleeve received over the omnidirectional radiation detector and rotating about a longitudinal axis. The RSM further includes: (i) a fin extending longitudinally from one side of the rotating sleeve; and (ii) a wall extending from the rotating sleeve and spaced apart from the fin having an upper end distally positioned on the rotating sleeve spaced apart or next to …

Go to article

Sar Collection Planning And Data Quality Assessment, Jacob M. Brumfield Jun 2021

Sar Collection Planning And Data Quality Assessment, Jacob M. Brumfield

Theses and Dissertations

Radar resource management is an important research topic in the radar community. Identifying the performance of a synthetic aperture radar image early into a data processing chain can improve intelligence collection mission performance. To achieve that goal, separate flags can be presented to a radar technician along a data processing chain to identify various errors within a data collection. Toward the end, this thesis analyzes he radar image processing chain and identifies data quality checks that could be implemented. The first quality check is to identify canonical targets and the necessary Nyquist-Shannon sampling requirements. Then, observations can be made to …

Go to article

Design And Fabrication Of Zinc Oxide Optofluidic Laser Elements, Kyle T. Bodily Jun 2021

Design And Fabrication Of Zinc Oxide Optofluidic Laser Elements, Kyle T. Bodily

Theses and Dissertations

This thesis systematically goes through the derivation, simulation, and experimentation of Zinc Oxide optofluidic micro laser elements. Single and coupled ring resonators were simulated to show single mode transmission as well as enhanced coupling capabilities when surrounded by high refractive index liquid. Devices with diameters ranging from 100-500 µm were successfully fabricated inexpensively through standard cleanroom procedures. The devices were tested using two different pump laser systems. Testing included such factors as high pump intensity, various angles of excitation, and low temperature. In all cases PL emission was observed and recorded.

Go to article

Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh Jun 2021

Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh

Theses and Dissertations

Piezoelectric contour mode resonator technology has the unique advantage of combining low motional resistance with the ability to define multiple frequencies on the same substrate. Contour mode resonators can be mechanically coupled together to form robust band-pass filters for the next generation of GPS satellites with extreme size reduction compared to electrically coupled filters. Piezoelectric zinc oxide (ZnO) contour mode resonators have the potential for monolithic integration with current ZnO transistor further reducing size, power consumption, and cost of filter modules. Barium strontium titanate (BST) contour mode resonators have incredible frequency tunability due to the fundamental nature of the thin …

Go to article

Synthetic Aperture Radar Image Recognition Of Armored Vehicles, Christopher Szul, Torrey J. Wagner, Brent T. Langhals Jun 2021

Synthetic Aperture Radar Image Recognition Of Armored Vehicles, Christopher Szul, Torrey J. Wagner, Brent T. Langhals

Faculty Publications

Synthetic Aperture Radar (SAR) imagery is not affected by weather and allows for day-and-night observations, however it can be difficult to interpret. This work applies classical and neural network machine learning techniques to perform image classification of SAR imagery. The Moving and Stationary Target Acquisition and Recognition dataset from the Air Force Research Laboratory was used, which contained 2,987 total observations of the BMP-2, BTR-70, and T-72 vehicles. Using a 75%/25% train/test split, the classical model achieved an average multi-class image recognition accuracy of 70%, while a convolutional neural network was able to achieve a 97% accuracy with lower model …

Go to article

First Prev Next Last