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Articles 1 - 19 of 19
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E700xd Portable Doppler Radar Energy Systems Analysis, Brandon M. Bailey [*], Torrey J. Wagner, Jada Williams
E700xd Portable Doppler Radar Energy Systems Analysis, Brandon M. Bailey [*], Torrey J. Wagner, Jada Williams
Faculty Publications
Occurring in industrialized nations, inexpensive and abundantly available power is routinely taken for granted. However, energy resilience and to a lesser extent price are key concerns when considering potential solutions for disaster response, disaster relief, or military operations. The Department of Defense (DoD) currently uses a 5 kW generator to power the E700XD portable Doppler radar system when grid power is unavailable [1]. While the radar has an approximate power consumption of 2.5 kW, there is a potential for higher demand due to weather conditions [2]. This paper examines the cost of operating a currently installed generator, compared to the …
Generating Electromagnetic Nonuniformly Correlated Beams, Milo W. Hyde Iv, Xifeng Xiao, David G. Voelz
Generating Electromagnetic Nonuniformly Correlated Beams, Milo W. Hyde Iv, Xifeng Xiao, David G. Voelz
Faculty Publications
We develop a method to generate electromagnetic nonuniformly correlated (ENUC) sources from vector Gaussian Schell-model (GSM) beams. Having spatially varying correlation properties, ENUC sources are more difficult to synthesize than their Schell-model counterparts (which can be generated by filtering circular complex Gaussian random numbers) and, in past work, have only been realized using Cholesky decomposition—a computationally intensive procedure. Here we transform electromagnetic GSM field instances directly into ENUC instances, thereby avoiding computing Cholesky factors resulting in significant savings in time and computing resources. We validate our method by generating (via simulation) an ENUC beam with desired parameters. We find the …
Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory
Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory
Faculty Publications
Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain …
Measurement Of Electron Density And Temperature From Laser-Induced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao [*], Mark Gragston, Anil K. Patnaik, Paul S. Hsu, Michael B. Shattan
Measurement Of Electron Density And Temperature From Laser-Induced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao [*], Mark Gragston, Anil K. Patnaik, Paul S. Hsu, Michael B. Shattan
Faculty Publications
Laser-induced plasmas experience Stark broadening and shifts of spectral lines carrying spectral signatures of plasma properties. In this paper, we report time-resolved Stark broadening measurements of a nitrogen triplet emission line at 1–6 bar ambient pressure in a pure nitrogen cell. Electron densities are calculated using the Stark broadening for different pressure conditions, which are shown to linearly increase with pressure. Additionally, using a Boltzmann fit for the triplet, the electron temperature is calculated and shown to decrease with increasing pressure. The rate of plasma cooling is observed to increase with pressure. The reported Stark broadening based plasma diagnostics in …
Adaptive-Hybrid Redundancy With Error Injection, Nicholas S. Hamilton, Scott R. Graham, Timothy Carbino, James C. Petrosky, J. Addison Betances
Adaptive-Hybrid Redundancy With Error Injection, Nicholas S. Hamilton, Scott R. Graham, Timothy Carbino, James C. Petrosky, J. Addison Betances
Faculty Publications
Adaptive-Hybrid Redundancy (AHR) shows promise as a method to allow flexibility when selecting between processing speed and energy efficiency while maintaining a level of error mitigation in space radiation environments. Whereas previous work demonstrated AHR’s feasibility in an error free environment, this work analyzes AHR performance in the presence of errors. Errors are deliberately injected into AHR at specific times in the processing chain to demonstrate best and worst case performance impacts. This analysis demonstrates that AHR provides flexibility in processing speed and energy efficiency in the presence of errors
Multiple Pursuer Multiple Evader Differential Games, Eloy Garcia, David Casbeer, Alexander Von Moll, Meir Pachter
Multiple Pursuer Multiple Evader Differential Games, Eloy Garcia, David Casbeer, Alexander Von Moll, Meir Pachter
Faculty Publications
In this paper an N-pursuer vs. M-evader team conflict is studied. The differential game of border defense is addressed and we focus on the game of degree in the region of the state space where the pursuers are able to win. This work extends classical differential game theory to simultaneously address weapon assignments and multi-player pursuit-evasion scenarios. Saddle-point strategies that provide guaranteed performance for each team regardless of the actual strategies implemented by the opponent are devised. The players' optimal strategies require the co-design of cooperative optimal assignments and optimal guidance laws. A representative measure of performance is proposed and …
Nonlinearities And Carrier Dynamics In Refractory Plasmonic Tin Thin Films, Heather George, Jennifer Reed, Manuel R. Ferdinandus, Clayton Devault, Alexei Lagutchev, Augustine Urbas, Theodore B. Norris, Vladimir M. Shalaev, Alexandra Boltasseva, Nathaniel Kinsey
Nonlinearities And Carrier Dynamics In Refractory Plasmonic Tin Thin Films, Heather George, Jennifer Reed, Manuel R. Ferdinandus, Clayton Devault, Alexei Lagutchev, Augustine Urbas, Theodore B. Norris, Vladimir M. Shalaev, Alexandra Boltasseva, Nathaniel Kinsey
Faculty Publications
Titanium nitride is widely used in plasmonic applications, due to its robustness and optical properties which resemble those of gold. Despite this interest, the nonlinear properties have only recently begun to be investigated. In this work, beam deflection and non-degenerate femtosecond pump-probe spectroscopy (800 nm pump and 650 nm probe) were used to measure the real and imaginary transient nonlinear response of 30-nm-thick TiN films on sapphire and fused silica in the metallic region governed by Fermi-smearing nonlinearities. In contrast to other metals, it is found that TiN exhibits non-instantaneous positive refraction and reverse saturable absorption whose relaxation is dominated …
Insulation Sensitivity Analysis For An Optimized Fabric Shelter Off-Grid Hybrid Energy System, Jay F. Pearson [*], Torrey J. Wagner, Steven Schuldt
Insulation Sensitivity Analysis For An Optimized Fabric Shelter Off-Grid Hybrid Energy System, Jay F. Pearson [*], Torrey J. Wagner, Steven Schuldt
Faculty Publications
During military and disaster relief operations, connecting to an established electrical grid is rarely an option. In these situations, camps consisting of poorly insulated fabric shelters are predominantly powered by inefficient diesel generators that require frequent fuel resupply. In order to reduce the fuel demand of these generators, camps may utilize photovoltaic-battery systems. This paper presents an innovative cost-performance model capable of optimizing solar array size, battery backup system, and shelter insulation type to minimize the operating cost of powering a single fabric shelter. Model performance was evaluated using one year of insolation, weather and energy requirement data from a …
Near-Field Effects On Partially Coherent Light Scattered By An Aperture, Milo W. Hyde Iv, Michael J. Havrilla
Near-Field Effects On Partially Coherent Light Scattered By An Aperture, Milo W. Hyde Iv, Michael J. Havrilla
Faculty Publications
We investigate how the near field affects partially coherent light scattered from an aperture in an opaque screen. Prior work on this subject has focused on the role of surface plasmons, and how they affect spatial coherence is well documented. Here, we consider other near-field effects that might impact spatial coherence. We do this by examining the statistics of the near-zone field scattered from an aperture in a perfect electric conductor plane—a structure that does not support surface plasmons. We derive the near-field statistics (in particular, cross-spectral density functions) by applying electromagnetic equivalence theorems and the Method of Moments. We …
System And Method For Radio Tomographic Image Formation, Richard K. Martin
System And Method For Radio Tomographic Image Formation, Richard K. Martin
AFIT Patents
A system and method for generating radio tomographic images is provided. A plurality of transceivers positioned around a region to be imaged is divided into a plurality of pixels. A control apparatus is configured to cause each of the plurality of transceivers in turn to send a signal to each of the other transceivers. The control apparatus is further configured to determine an attenuation in the received signals, generate weighing, derivative, and attenuation matrices from the signals, group the pixels into a plurality of provinces, select each province in turn and solve for a change in attenuation in each of …
3d Plasmonic Design Approach For Efficient Transmissive Huygens Metasurfaces, Bryan M. Adomanis, D. Bruce Burckel, Michael A. Marciniak
3d Plasmonic Design Approach For Efficient Transmissive Huygens Metasurfaces, Bryan M. Adomanis, D. Bruce Burckel, Michael A. Marciniak
Faculty Publications
In this paper we present a design concept for 3D plasmonic scatterers as high- efficiency transmissive metasurface (MS) building blocks. A genetic algorithm (GA) routine partitions the faces of the walls inside an open cavity into a M x N grid of voxels which can be either covered with metal or left bare, and optimizes the distribution of metal coverage needed to generate electric and magnetic modes of equal strength with a targeted phase delay (Φt) at the design wavelength. Even though the electric and magnetic modes can be more complicated than typical low order modes, with their spectral overlap …
Analyzing The Efficiency Of Horizontal Photovoltaic Cells In Various Climate Regions, Parker A. Hines, Torrey J. Wagner, Clay M. Koschnick, Steven J. Schuldt
Analyzing The Efficiency Of Horizontal Photovoltaic Cells In Various Climate Regions, Parker A. Hines, Torrey J. Wagner, Clay M. Koschnick, Steven J. Schuldt
Faculty Publications
This research presents the development of linear regression models to predict horizontal photovoltaic power output. We collected a dataset from 14 global Department of Defense (DoD) installations over a timeframe of one year using an experimental apparatus, resulting in 24,179 usable data points. We developed a linear model to predict power output, which incorporated site-specific weather and geographical characteristics, along with Köppen-Geiger climate classifications in order to determine the effect of adding climate to the model. After performing a Wald test between the full model and a reduced model without Köppen-Geiger climate variables, it was determined that including Köppen-Geiger climate …
36% Reduction In Fuel Resupply Using A Hybrid Generator & Battery System For An Austere Location, David J. Chester [*], Torrey J. Wagner, Douglas S. Dudis
36% Reduction In Fuel Resupply Using A Hybrid Generator & Battery System For An Austere Location, David J. Chester [*], Torrey J. Wagner, Douglas S. Dudis
Faculty Publications
The DOD energy policy is to increase energy security resiliency, and mitigate costs in the use and management of energy[1] Forward operating bases (FOBs) are remote, austere base camps that support an operationally defined mission with a limited or no ability to draw from an energy grid and have historically relied on diesel-powered generators for the primary production of energy.[2] Generators are sized to meet a theoretical peak demand, but steady state loads are far below this peak, resulting in under-loaded generators.[3] Under-loaded diesel generators decrease efficiency and increase the need for maintenance, affecting the lifespan of …
Improving Regional And Teleseismic Detection For Single-Trace Waveforms Using A Deep Temporal Convolutional Neural Network Trained With An Array-Beam Catalog, Joshua T. Dickey, Brett J. Borghetti, William Junek
Improving Regional And Teleseismic Detection For Single-Trace Waveforms Using A Deep Temporal Convolutional Neural Network Trained With An Array-Beam Catalog, Joshua T. Dickey, Brett J. Borghetti, William Junek
Faculty Publications
The detection of seismic events at regional and teleseismic distances is critical to Nuclear Treaty Monitoring. Traditionally, detecting regional and teleseismic events has required the use of an expensive multi-instrument seismic array; however in this work, we present DeepPick, a novel seismic detection algorithm capable of array-like detection performance from a single-trace. We achieve this performance through three novel steps: First, a high-fidelity dataset is constructed by pairing array-beam catalog arrival-times with single-trace waveforms from the reference instrument of the array. Second, an idealized characteristic function is created, with exponential peaks aligned to the cataloged arrival times. Third, a deep …
A Triaxial Applicator For The Measurement Of The Electromagnetic Properties Of Materials, Saranraj Karuppuswami, Edward Rothwell, Premjeet Chahal, Michael J. Havrilla
A Triaxial Applicator For The Measurement Of The Electromagnetic Properties Of Materials, Saranraj Karuppuswami, Edward Rothwell, Premjeet Chahal, Michael J. Havrilla
Faculty Publications
The design, analysis, and fabrication of a prototype triaxial applicator is described. The applicator provides both reflected and transmitted signals that can be used to characterize the electromagnetic properties of materials in situ. A method for calibrating the probe is outlined and validated using simulated data. Fabrication of the probe is discussed, and measured data for typical absorbing materials and for the probe situated in air are presented. The simulations and measurements suggest that the probe should be useful for measuring the properties of common radar absorbing materials under usual in situ conditions.
M2 Factor Of A Vector Schell-Model Beam, Milo W. Hyde Iv, Mark F. Spencer
M2 Factor Of A Vector Schell-Model Beam, Milo W. Hyde Iv, Mark F. Spencer
Faculty Publications
Extending existing scalar Schell-model source work, we derive the M2 factor for a general electromagnetic or vector Schell-model source to assess beam quality. In particular, we compute the M2 factors for two vector Schell-model sources found in the literature. We then describe how to synthesize vector Schell-model beams in terms of specified, desired M2 and present Monte Carlo simulation results to validate our analysis.
Variations Of Heavy Ion Abundances Relative To Proton Abundances In Large Solar Energetic (E > 10 Mev) Particle Events, J. F. Round, Robert D. Loper, Omar A. Nava, Stephen W. Kahler
Variations Of Heavy Ion Abundances Relative To Proton Abundances In Large Solar Energetic (E > 10 Mev) Particle Events, J. F. Round, Robert D. Loper, Omar A. Nava, Stephen W. Kahler
Faculty Publications
The elemental composition of heavy ions (with atomic number Z > 2) (hi-Z) in large gradual E > 10 MeV nuc-1 SEP events has been extensively studied in the 2-15 MeV nuc-1 range to determine the acceleration processes and transport properties of SEPs. These studies invariably are based on abundances relative to those of a single element such as C or O and often neglect H and He, the elements of primary interest for space weather. The total radiation of an SEP event is determined not only by the H and He properties but also by those of hi-Z ions …
A Sustainable Prototype For Renewable Energy: Optimized Prime-Power Generator Solar Array Replacement, Nathan Thomsen, Torrey J. Wagner, Andrew J. Hoisington, Steven J. Schuldt
A Sustainable Prototype For Renewable Energy: Optimized Prime-Power Generator Solar Array Replacement, Nathan Thomsen, Torrey J. Wagner, Andrew J. Hoisington, Steven J. Schuldt
Faculty Publications
Remote locations such as disaster relief camps, isolated arctic communities, and military forward operating bases are disconnected from traditional power grids forcing them to rely on diesel generators with a total installed capacity of 10,000 MW worldwide. The generators require a constant resupply of fuel, resulting in increased operating costs, negative environmental impacts, and challenging fuel logistics. To enhance remote site sustainability, planners can develop stand-alone photovoltaic-battery systems to replace existing prime power generators. This paper presents the development of a novel cost-performance model capable of optimizing solar array and Li-ion battery storage size by generating tradeoffs between minimizing initial …
Real-Time Path Planning In Constrained, Uncertain Environments, Randall Christensen, Robert C. Leishman
Real-Time Path Planning In Constrained, Uncertain Environments, Randall Christensen, Robert C. Leishman
Faculty Publications
A key enabler of autonomous vehicles is the ability to plan the path of the vehicle to accomplish mission objectives. To be robust to realistic environments, path planners must account for uncertainty in the trajectory of the vehicle as well as uncertainty in the location of obstacles. The uncertainty in the trajectory of the vehicle is a difficult quantity to estimate, and is influenced by coupling between the vehicle dynamics, guidance, navigation, and control system as well as any disturbances acting on the vehicle. Monte Carlo analysis is the conventional approach to determine vehicle dispersion, while accounting for the coupled …