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

Physical Sciences and Mathematics Commons™

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

Air Force Institute of Technology

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 781 - 810 of 3057

Full-Text Articles in Physical Sciences and Mathematics

Near-Infrared-Sensitive Photorefractive Sn2P2S6 Crystals Grown By The Bridgman Method, O. M. Shumelyuk, A. Y. Volkov, Y. Skrypka, Larry E. Halliburton, Nancy C. Giles, Christopher A. Lenyk, Sergey A. Basun, A. A. Grabar, Y. M. Vysochansky, S. G. Odoulov, D. R. Evans Mar 2020

Near-Infrared-Sensitive Photorefractive Sn2P2S6 Crystals Grown By The Bridgman Method, O. M. Shumelyuk, A. Y. Volkov, Y. Skrypka, Larry E. Halliburton, Nancy C. Giles, Christopher A. Lenyk, Sergey A. Basun, A. A. Grabar, Y. M. Vysochansky, S. G. Odoulov, D. R. Evans

Faculty Publications

Ferroelectric tin hypothiodiphosphate (Sn2P2S6) crystals are well-known for their significant piezoelectric, electro-optic, and nonlinear optical properties. These crystals have usually been grown by a vapor transport technique. We report in this paper on the first study of photorefractive nonlinearity in Sn2P2S6 crystals grown by the Bridgman method. Pronounced photorefraction is observed in the near-infrared region of the spectrum even with no preliminary optical sensitizing.

Go to article

Synthesizing General Electromagnetic Partially Coherent Sources From Random, Correlated Complex Screens, Milo W. Hyde Iv Mar 2020

Synthesizing General Electromagnetic Partially Coherent Sources From Random, Correlated Complex Screens, Milo W. Hyde Iv

Faculty Publications

We present a method to generate any genuine electromagnetic partially coherent source (PCS) from correlated, stochastic complex screens. The method described here can be directly implemented on existing spatial-light-modulator-based vector beam generators and can be used in any application which utilizes electromagnetic PCSs. Our method is based on the genuine cross-spectral density matrix criterion. Applying that criterion, we show that stochastic vector field realizations (corresponding to a desired electromagnetic PCS) can be generated by passing correlated Gaussian random numbers through “filters” with space-variant transfer functions. We include step-by-step instructions on how to generate the electromagnetic PCS field realizations. As an …

Go to article

Cyber-Physical Security With Rf Fingerprint Classification Through Distance Measure Extensions Of Generalized Relevance Learning Vector Quantization, Trevor J. Bihl, Todd J. Paciencia, Kenneth W. Bauer Jr., Michael A. Temple Feb 2020

Cyber-Physical Security With Rf Fingerprint Classification Through Distance Measure Extensions Of Generalized Relevance Learning Vector Quantization, Trevor J. Bihl, Todd J. Paciencia, Kenneth W. Bauer Jr., Michael A. Temple

Faculty Publications

Radio frequency (RF) fingerprinting extracts fingerprint features from RF signals to protect against masquerade attacks by enabling reliable authentication of communication devices at the “serial number” level. Facilitating the reliable authentication of communication devices are machine learning (ML) algorithms which find meaningful statistical differences between measured data. The Generalized Relevance Learning Vector Quantization-Improved (GRLVQI) classifier is one ML algorithm which has shown efficacy for RF fingerprinting device discrimination. GRLVQI extends the Learning Vector Quantization (LVQ) family of “winner take all” classifiers that develop prototype vectors (PVs) which represent data. In LVQ algorithms, distances are computed between exemplars and PVs, and …

Go to article

Integrated Quantum Information Processing Controlled Phase Gate, Richard S. Kim, Attila A. Szep, Michael L. Fanto, Paul M. Alsing, Gordon E. Lott, Christopher C. Tison Feb 2020

Integrated Quantum Information Processing Controlled Phase Gate, Richard S. Kim, Attila A. Szep, Michael L. Fanto, Paul M. Alsing, Gordon E. Lott, Christopher C. Tison

AFIT Patents

An electro-optical directional coupler is provided having a substrate and a first and second optical waveguide formed on the substrate, where the second waveguide extends adjacent to and parallel with the first waveguide for at least one interaction length. The interaction length has a first end and a second end such that an optical signal applied only to one of the first and second waveguides couples to the other of the first and second waveguides between the ends. A first electrode is proximate the first and second waveguides and between the ends of the interaction length. A first voltage applied …

Go to article

An Ultra-Sparse Approximation Of Kinetic Solutions To Spatially Homogeneous Flows Of Non-Continuum Gas, Alexander Alekseenko, Amy Grandilli, Aihua W. Wood Feb 2020

An Ultra-Sparse Approximation Of Kinetic Solutions To Spatially Homogeneous Flows Of Non-Continuum Gas, Alexander Alekseenko, Amy Grandilli, Aihua W. Wood

Faculty Publications

We consider a compact approximation of the kinetic velocity distribution function by a sum of isotropic Gaussian densities in the problem of spatially homogeneous relaxation. Derivatives of the macroscopic parameters of the approximating Gaussians are obtained as solutions to a linear least squares problem derived from the Boltzmann equation with full collision integral. Our model performs well for flows obtained by mixing upstream and downstream conditions of normal shock wave with Mach number 3. The model was applied to explore the process of approaching equilibrium in a spatially homogeneous flow of gas. Convergence of solutions with respect to the model …

Go to article

Metrics To Meet Security & Privacy Requirements With Agile Software Development Methods In A Regulated Environment, Torrey J. Wagner, Thomas C. Ford Feb 2020

Metrics To Meet Security & Privacy Requirements With Agile Software Development Methods In A Regulated Environment, Torrey J. Wagner, Thomas C. Ford

Faculty Publications

This work examines metrics that can be used to measure the ability of agile software development methods to meet security and privacy requirements of communications applications. Many implementations of communication protocols, including those in vehicular networks, occur within regulated environments where agile development methods are traditionally discouraged. We propose a framework and metrics to measure adherence to security, quality and software effectiveness regulations if developers desire the cost and schedule benefits of agile methods. After providing an overview of specific challenges that a regulated environment imposes on communications software development, we proceed to examine the 12 agile principles and how …

Go to article

A Sequential Partial Information Bomber‐Defender Shooting Problem, Krishna Kalyanam, David W. Casbeer, Meir Pachter Feb 2020

A Sequential Partial Information Bomber‐Defender Shooting Problem, Krishna Kalyanam, David W. Casbeer, Meir Pachter

Faculty Publications

No abstract provided.

Go to article

Harmonic Equiangular Tight Frames Comprised Of Regular Simplices, Matthew C. Fickus, Courtney A. Schmitt Feb 2020

Harmonic Equiangular Tight Frames Comprised Of Regular Simplices, Matthew C. Fickus, Courtney A. Schmitt

Faculty Publications

An equiangular tight frame (ETF) is a sequence of unit-norm vectors in a Euclidean space whose coherence achieves equality in the Welch bound, and thus yields an optimal packing in a projective space. A regular simplex is a simple type of ETF in which the number of vectors is one more than the dimension of the underlying space. More sophisticated examples include harmonic ETFs which equate to difference sets in finite abelian groups. Recently, it was shown that some harmonic ETFs are comprised of regular simplices. In this paper, we continue the investigation into these special harmonic ETFs. We begin …

Go to article

Radiation-Induced Electron And Hole Traps In Ge1-XSnX (X = 0-0.094), Michael R. Hogsed, Kevin K. Choe, Norman Miguel, Buguo Wang, John Kouvetakis Feb 2020

Radiation-Induced Electron And Hole Traps In Ge1-XSnX (X = 0-0.094), Michael R. Hogsed, Kevin K. Choe, Norman Miguel, Buguo Wang, John Kouvetakis

Faculty Publications

The band structure of germanium changes significantly when alloyed with a few percent concentrations of tin, and while much work has been done to characterize and exploit these changes, the corresponding deep-level defect characteristics are largely unknown. In this paper, we investigate the dominant deep-level defects created by 2 MeV proton irradiation in Ge1 -xSnx (x = 0.0, 0.020, 0.053, 0.069, and 0.094) diodes and determine how the ionization energies of these defects change with tin concentrations. Deep-level transient spectroscopy measurements approximate the ionization energies associated with electron transitions to/from the valence band (hole traps) and conduction band (electron traps) …

Go to article

Twisted Space-Frequency And Space-Time Partially Coherent Beams, Milo W. Hyde Iv Jan 2020

Twisted Space-Frequency And Space-Time Partially Coherent Beams, Milo W. Hyde Iv

Faculty Publications

We present partially coherent sources that are statistically twisted in the space-frequency and space-time domains. Beginning with the superposition rule for genuine partially coherent sources, we derive source plane expressions for the cross-spectral density (CSD) and mutual coherence functions (MCFs) for twisted space-frequency and space-time Gaussian Schell-model (GSM) beams. Using the Fresnel approximation to the free-space Green’s function, we then paraxially propagate the CSD and MCF to any plane z> 0. We discuss the beams’ behavior as they propagate, with particular emphasis on how the beam shape rotates or tumbles versus z. To validate our analysis, we simulate the generation …

Go to article

Digital Holography Experiments With Degraded Temporal Coherence, Douglas E. Thornton, Davin Mao, Mark F. Spencer, Christopher A. Rice, Glen P. Perram Jan 2020

Digital Holography Experiments With Degraded Temporal Coherence, Douglas E. Thornton, Davin Mao, Mark F. Spencer, Christopher A. Rice, Glen P. Perram

Faculty Publications

To simulate the effects of multiple-longitudinal modes and rapid fluctuations in center frequency, we use sinusoidal phase modulation and linewidth broadening, respectively. These effects allow us to degrade the temporal coherence of our master-oscillator laser, which we then use to conduct digital holography experiments. In turn, our results show that the coherence efficiency decreases quadratically with fringe visibility and that our measurements agree with our models to within 1.8% for sinusoidal phase modulation and 6.9% for linewidth broadening.

Go to article

Analytic Non-Adiabatic Derivative Coupling Terms For Spin-Orbit Mrci Wavefunctions. I. Formalism, Lachlan T. Belcher, Gary S. Kedziora, David E. Weeks Dec 2019

Analytic Non-Adiabatic Derivative Coupling Terms For Spin-Orbit Mrci Wavefunctions. I. Formalism, Lachlan T. Belcher, Gary S. Kedziora, David E. Weeks

Faculty Publications

Analytic gradients of electronic eigenvalues require one calculation per nuclear geometry, compared to at least 3n + 1 calculations for finite difference methods, where n is the number of nuclei. Analytic nonadiabatic derivative coupling terms (DCTs), which are calculated in a similar fashion, are used to remove nondiagonal contributions to the kinetic energy operator, leading to more accurate nuclear dynamics calculations than those that employ the Born-Oppenheimer approximation, i.e., that assume off-diagonal contributions are zero. The current methods and underpinnings for calculating both of these quantities, gradients and DCTs, for the State-Averaged MultiReference Configuration Interaction with Singles and Doubles (MRCI-SD) …

Go to article

Monte Carlo And Experimental Analysis Of A Novel Directional Rotating Scatter Mask Gamma Detection System, Julie V. Logan, Darren E. Holland, Larry W. Burggraf, Justin A. Clinton, Buckley E. O'Day Iii Dec 2019

Monte Carlo And Experimental Analysis Of A Novel Directional Rotating Scatter Mask Gamma Detection System, Julie V. Logan, Darren E. Holland, Larry W. Burggraf, Justin A. Clinton, Buckley E. O'Day Iii

Faculty Publications

Excerpt: This work demonstrates successful experimental operation of a prototype system to identify source direction which was modeled using a library of signals simulated using GEANT and a novel algorithm....

Go to article

Evaluating The Resiliency Of Industrial Internet Of Things Process Control Using Protocol Agnostic Attacks, Hector L. Roldan Dec 2019

Evaluating The Resiliency Of Industrial Internet Of Things Process Control Using Protocol Agnostic Attacks, Hector L. Roldan

Theses and Dissertations

Improving and defending our nation's critical infrastructure has been a challenge for quite some time. A malfunctioning or stoppage of any one of these systems could result in hazardous conditions on its supporting populace leading to widespread damage, injury, and even death. The protection of such systems has been mandated by the Office of the President of the United States of America in Presidential Policy Directive Order 21. Current research now focuses on securing and improving the management and efficiency of Industrial Control Systems (ICS). IIoT promises a solution in enhancement of efficiency in ICS. However, the presence of IIoT …

Go to article

E700xd Portable Doppler Radar Energy Systems Analysis, Brandon M. Bailey, Torrey J. Wagner, Jada Williams Dec 2019

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 …

Go to article

Analytic Non-Adiabatic Derivative Coupling Terms For Spin-Orbit Mrci Wavefunctions. Ii. Derivative Coupling Terms And Coupling Angle For Khe (A2Π1/2) ⇔ Khe B2Σ1/2), Lachlan T. Belcher, Charlton D. Lewis, Gary S. Kedziora, David E. Weeks Dec 2019

Analytic Non-Adiabatic Derivative Coupling Terms For Spin-Orbit Mrci Wavefunctions. Ii. Derivative Coupling Terms And Coupling Angle For Khe (A2Π1/2) ⇔ Khe B2Σ1/2), Lachlan T. Belcher, Charlton D. Lewis, Gary S. Kedziora, David E. Weeks

Faculty Publications

A method for calculating the analytic nonadiabatic derivative coupling terms (DCTs) for spin-orbit multi-reference configuration interaction wavefunctions is reviewed. The results of a sample calculation using a Stuttgart basis for KHe are presented. Additionally, the DCTs are compared with a simple calculation based on the Nikitin’s 3 × 3 description of the coupling between the Σ and Π surfaces, as well as a method based on Werner’s analysis of configuration interaction coefficients. The nonadiabatic coupling angle calculated by integrating the radial analytic DCTs using these different techniques matches extremely well. The resultant nonadiabatic energy surfaces for KHe are presented.

Go to article

Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Timothy D. Gustafson, Larry E. Halliburton, Nancy C. Giles Dec 2019

Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Timothy D. Gustafson, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR), infrared absorption, and thermoluminescence (TL) are used to determine the Fe2+/3+ level in Fe-doped β-Ga2O3 crystals. With these noncontact spectroscopy methods, a value of 0.84 ± 0.05 eV below the conduction band is obtained for this level. Our results clearly establish that the E2 level observed in deep level transient spectroscopy (DLTS) experiments is due to the thermal release of electrons from Fe2+ ions. The crystals used in this investigation were grown by the Czochralski method and contained large concentrations of Fe acceptors and Ir donors, and trace amounts of Cr …

Go to article

Effect Of Ar(3p54p; 2p)+M -> Ar(3p54s; 1s)+M Branching Ratio On Optically Pumped Rare Gas Laser Performance, Daniel J. Emmons Ii, David E. Weeks Nov 2019

Effect Of Ar(3p54p; 2p)+M -> Ar(3p54s; 1s)+M Branching Ratio On Optically Pumped Rare Gas Laser Performance, Daniel J. Emmons Ii, David E. Weeks

Faculty Publications

Optically pumped rare gas laser performance is analyzed as a function of the Ar(3p54p; 2p) + M → Ar(3p54s; 1s) + M branching ratios. Due to the uncertainty in the branching ratios, a sensitivity study is performed to determine the effect on output and absorbed pump laser intensities. The analysis is performed using a radio frequency dielectric barrier discharge as the source of metastable production for a variety of Argon in Helium mixtures over pressures ranging from 200 to 500 Torr. Peak output laser intensities show a factor of 7 increase as the branching ratio is …

Go to article

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 Nov 2019

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 …

Go to article

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 Nov 2019

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 …

Go to article

Nonlinear Characterizing Of A New Titanium Nitride On Aluminum Oxide Metalens, Michael A. Cumming Oct 2019

Nonlinear Characterizing Of A New Titanium Nitride On Aluminum Oxide Metalens, Michael A. Cumming

Theses and Dissertations

A sample metalens generated from Titanium Nitride deposited onto Aluminum Oxide was designed to focus at 10 microns with a beam centered at 800nm, and when analyzed with high intensity illumination was found to have a focal length of 9.650 ±.003µm at an intensity of 16.93[MW/cm2 ]. Analyzing this change by comparing it to a Fresnel Lens’ physics shows that for this lens, the effective nonlinear index of refraction is certainly greater than the nonlinear index of just Titanium Nitride itself, at −1.6239 × 10−15[m2/W] compared to the materials −1.3 × 10−15[m2 …

Go to article

Generating Electromagnetic Schell-Model Sources Using Complex Screens With Spatially Varying Auto- And Cross-Correlation Functions, Milo W. Hyde Iv Sep 2019

Generating Electromagnetic Schell-Model Sources Using Complex Screens With Spatially Varying Auto- And Cross-Correlation Functions, Milo W. Hyde Iv

Faculty Publications

We present a method to generate any physically realizable electromagnetic Schell-model source. Our technique can be directly implemented on existing vector-beam generators that utilize spatial light modulators for coherence control, beam shaping, and relative phasing. This work significantly extends published research on the subject, where control over the partially coherent source’s cross-spectral density matrix was limited. We begin by presenting the statistical optics theory necessary to derive and implement our method. We then apply our technique, both analytically and in simulation, to produce two electromagnetic Schell-model sources from the literature. We demonstrate control over the full cross-spectral density matrices of …

Go to article

Numerical Simulation Of Unstable Laser Resonators With A High Gain Medium, Robert L. Lloyd Sep 2019

Numerical Simulation Of Unstable Laser Resonators With A High Gain Medium, Robert L. Lloyd

Theses and Dissertations

This research focused on the numeric simulation of unstable laser resonators with high gain media. In order to accomplish the research, the modes and eigenvalues for various bare cavity resonator were computed followed by modes of a resonator in the presence of gain. Using a Fourier Split Step Method in a Fox and Li iteration scheme, different laser outputs for various laser cavities with gain were computed. Various parameters defining positive branch confocal unstable resonators were chosen corresponding to four studies. The four studies focused on modifying laser cavity Fresnel number, gain medium parameters, gain cell position, and gain cell …

Go to article

Statistical L-Moment And L-Moment Ratio Estimation And Their Applicability In Network Analysis, Timothy S. Anderson Sep 2019

Statistical L-Moment And L-Moment Ratio Estimation And Their Applicability In Network Analysis, Timothy S. Anderson

Theses and Dissertations

This research centers on finding the statistical moments, network measures, and statistical tests that are most sensitive to various node degradations for the Barabási-Albert, Erdös-Rényi, and Watts-Strogratz network models. Thirty-five different graph structures were simulated for each of the random graph generation algorithms, and sensitivity analysis was undertaken on three different network measures: degree, betweenness, and closeness. In an effort to find the statistical moments that are the most sensitive to degradation within each network, four traditional moments: mean, variance, skewness, and kurtosis as well as three non-traditional moments: L-variance, L-skewness, and L-kurtosis were examined. Each of these moments were …

Go to article

Sample Size Requirements And Considerations For Models To Assess Human-Machine System Performance, Jennifer S. G. Lopez Sep 2019

Sample Size Requirements And Considerations For Models To Assess Human-Machine System Performance, Jennifer S. G. Lopez

Theses and Dissertations

Hierarchical Linear Models (HLMs), also known as multi-level models, are an extension of multiple regression analysis and can aid in the understanding of human and machine workloads of a system. These models allow for prediction and testing in systems with hierarchies of two or more levels. The complex interrelated variability of these multi-level models exists in operational settings, such as the Air Force Distributed Common Ground System Full Motion Video (AF DCGS FMV) community which is composed of individuals (Level-1), groups (Level-2), units (Level-3), and organizations (Level-4). Through the development of sample size requirements and considerations for multi-level models, this …

Go to article

Digital Holography Efficiency Experiments For Tactical Applications, Douglas E. Thornton Sep 2019

Digital Holography Efficiency Experiments For Tactical Applications, Douglas E. Thornton

Theses and Dissertations

Digital holography (DH) uses coherent detection and offers direct access to the complex-optical field to sense and correct image aberrations in low signal-to-noise environments, which is critical for tactical applications. The performance of DH is compared to a similar, well studied deep-turbulence wavefront sensor, the self-referencing interferometer (SRI), with known efficiency losses. Wave optics simulations with deep-turbulence conditions and noise were conducted and the results show that DH outperforms the SRI by 10's of dB due to DH's strong reference. Additionally, efficiency experiments were conducted to investigate DH system losses. The experimental results show that the mixing efficiency (37%) is …

Go to article

Quantitative Analysis Of Cerium-Gallium Alloys Using A Hand-Held Laser Induced Breakdown Spectroscopy Device, Ashwin P. Rao, Matthew Cook, Howard L. Hall, Michael B. Shattan Sep 2019

Quantitative Analysis Of Cerium-Gallium Alloys Using A Hand-Held Laser Induced Breakdown Spectroscopy Device, Ashwin P. Rao, Matthew Cook, Howard L. Hall, Michael B. Shattan

Faculty Publications

A hand-held laser-induced breakdown spectroscopy device was used to acquire spectral emission data from laser-induced plasmas created on the surface of cerium-gallium alloy samples with Ga concentrations ranging from 0–3 weight percent. Ionic and neutral emission lines of the two constituent elements were then extracted and used to generate calibration curves relating the emission line intensity ratios to the gallium concentration of the alloy. The Ga I 287.4-nm emission line was determined to be superior for the purposes of Ga detection and concentration determination. A limit of detection below 0.25%was achieved using a multivariate regression model of the Ga I …

Go to article

Ion Software-Defined Radio Metadata Standard Final Report, Sanjeev Gunawardena, Alexander Rugamer, Muhammad Subhan Hameed, Markel Arizabaleta, Thomas Pany, Javier Arribas Sep 2019

Ion Software-Defined Radio Metadata Standard Final Report, Sanjeev Gunawardena, Alexander Rugamer, Muhammad Subhan Hameed, Markel Arizabaleta, Thomas Pany, Javier Arribas

Faculty Publications

The ION GNSS SDR Metadata Standard describes the formatting and other essential PNT-related parameters of sampled data streams and files. This allows processors to seamlessly consume such data without the need to input these parameters manually. The technical development phase of the initial version of the standard has now been deemed complete and is currently undergoing the last remaining procedural steps towards adoption as a formal standard by the Institute of Navigation. This paper reports on the activities of the working group since September 2018 and summarizes the final products of the standard. It also reports on examples of early …

Go to article

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace Aug 2019

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace

Theses and Dissertations

Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre and post irradiation. …

Go to article

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom Aug 2019

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom

Theses and Dissertations

This dissertation covers pulsed laser ablation of Al, Si, Ti, Ge, and InSb, with pulse durations from tens of picosecond to hundreds of microseconds, fluences from ones of J/cm2 to over 10,000 J/cm2, and in ambient air and vacuum. A set of non-dimensional scaling factors was created to interpret the data relative to the laser and material parameters, and it was found that pulse durations shorter than a critical timescale formed craters much larger than the thermal diffusion length, and longer pulse durations created holes much shallower than the thermal diffusion length. Low transverse order Gaussian beams …

Go to article

First Prev Next Last