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Electrical and Computer Engineering

Air Force Institute of Technology

2016

Articles 31 - 40 of 40

Full-Text Articles in Engineering

Field-Based Phase Retrieval Using Under-Sampled Data, Tatsuki L. Watts Mar 2016

Field-Based Phase Retrieval Using Under-Sampled Data, Tatsuki L. Watts

Theses and Dissertations

A phase retrieval algorithm designed for use with under-sampled astronomical data is developed in this thesis. Blind-deconvolution, Gerchberg Saxton (GS), and a field-based compass search are combined into an algorithm capable of recovering Zernike coefficients 4 through 11 from single frames of noisy, under-sampled data without the need to unwrap the recovered phase. The performance of the algorithm in data under-sampled by a factor of 2 is compared the performance of the algorithm on Nyquist-sampled data. In simulation trials, the magnitudes of all 8 estimated Zernike coefficients converged to within half a wave of the true values for 98% of …

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Electromagnetic Characterization Of Materials Using A Dual Chambered High Temperature Waveguide, Jeffrey S. Sovern Mar 2016

Electromagnetic Characterization Of Materials Using A Dual Chambered High Temperature Waveguide, Jeffrey S. Sovern

Theses and Dissertations

Measurement of the electromagnetic properties of materials at high temperatures is important for industrial, scientific, medical, and aerospace applications [1]. Current high-temperature electromagnetic material characterization is a time consuming process that typically requires three days to collect data from one material specimen. For example, the standard high-temperature process involving rectangular waveguides [2] requires measurements of the sample (1), the empty waveguide (2), and a metal short standard (3) completed in separate heated runs over three days to perform the Nicolson-Ross-Weir inversion algorithm for computing permittivity and permeability. The technique developed here will reduce the high-temperature measurement process from three days …

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Comparison Of Radio Frequency Distinct Native Attribute And Matched Filtering Techniques For Device Discrimination And Operation Identification, Barron D. Stone Mar 2016

Comparison Of Radio Frequency Distinct Native Attribute And Matched Filtering Techniques For Device Discrimination And Operation Identification, Barron D. Stone

Theses and Dissertations

The research presented here provides a comparison of classification, verification, and computational time for three techniques used to analyze Unintentional Radio- Frequency (RF) Emissions (URE) from semiconductor devices for the purposes of device discrimination and operation identification. URE from ten MSP430F5529 16-bit microcontrollers were analyzed using: 1) RF Distinct Native Attribute (RFDNA) fingerprints paired with Multiple Discriminant Analysis/Maximum Likelihood (MDA/ML) classification, 2) RF-DNA fingerprints paired with Generalized Relevance Learning Vector Quantized-Improved (GRLVQI) classification, and 3) Time Domain (TD) signals paired with matched filtering. These techniques were considered for potential applications to detect counterfeit/Trojan hardware infiltrating supply chains and to defend …

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Optically Stimulated Luminescence From Ag-Doped Lithium Tetraborate (Li2b4o7), Ember S. Maniego Mar 2016

Optically Stimulated Luminescence From Ag-Doped Lithium Tetraborate (Li2b4o7), Ember S. Maniego

Theses and Dissertations

Silver-doped lithium tetraborate (Li2B4O7) crystals emit optically stimulated luminescence (OSL) in response to stimulating light around 400 nm. Photoluminescence, optical absorption, and electron paramagnetic resonance (EPR) were used to identify the defects in the crystal that cause this OSL. Lithium tetraborate crystals have Ag+ ions at Li+ sites and at interstitial sites. Upon ionization at room temperature via x rays, electron-hole pairs are generated. The electrons are trapped at Ag+ occupying interstitial sites, while the holes are trapped at Ag+ at lithium sites. The trapped electron centers become Ag0 …

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Automated Sunspot Classification And Tracking Using Sdo/Hmi Imagery, Maclane A. Townsend Mar 2016

Automated Sunspot Classification And Tracking Using Sdo/Hmi Imagery, Maclane A. Townsend

Theses and Dissertations

Verification of an automated sunspot detection and classification algorithm is conducted utilizing two years of solar imagery from NASA's Solar Dynamics Observatory (SDO) satellite. Automated McIntosh classifications are compared against sunspot reports from the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center (SWPC) using a three-tiered comparison metric. Statistical confidence is demonstrated for algorithm performance and consistency when compared against the SWPC data set, suggesting future applications of the algorithm will perform similarly. A sunspot tracking algorithm is added to the existing code and demonstrates reliable feature tracking for time periods out to four days between consecutive images. …

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Efficacy Of Physical Layer Preamble Manipulation For Ieee 802.11a/Ac, Benjamin W. Ramsey, Jonathan D. Fuller, Christopher W. Badenhop Mar 2016

Efficacy Of Physical Layer Preamble Manipulation For Ieee 802.11a/Ac, Benjamin W. Ramsey, Jonathan D. Fuller, Christopher W. Badenhop

Faculty Publications

Wireless physical layer manipulation is a recently discovered technique for selective packet obfuscation. This process exploits the unique and proprietary nature of transceiver designs rather than manufacturing imperfections. To date, preamble manipulation has only successfully been demonstrated on low data rate transceivers operating in the2.4 GHz band. This Letter investigates the effectiveness of preamble manipulation on common 5 GHz IEEE 802.11a and IEEE 802.11ac wireless transceivers for the first time. Herein it is demonstrated that the preamble short training sequence length can be manipulated to discern among the six transceiver designs under test with greater than 99% accuracy using fewer …

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Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie Feb 2016

Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie

Faculty Publications

In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom …

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System And Method For Identifying Electrical Properties Of Integrate Circuits, Mary Y. Lanzerotti Jan 2016

System And Method For Identifying Electrical Properties Of Integrate Circuits, Mary Y. Lanzerotti

AFIT Patents

A new method for displaying electrical properties for integrated circuit (IC) layout designs provides for improved human visualization of those properties and comparison of as designed layout design parameters to as specified layout design parameters and to as manufactured layout parameters. The method starts with a circuitry as designed layout in a first digital format, extracts values for electrical properties from that circuitry as designed layout then annotates those values back into the first digital format. The annotated circuitry as designed layout is then converted from the first digital format to a second digital format that can be converted to …

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Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides, Hengky Chandrahalim, Stephen C. Rand, Xudong Fan Jan 2016

Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides, Hengky Chandrahalim, Stephen C. Rand, Xudong Fan

Faculty Publications

We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator – waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3′-Diethyloxacarbocyanine iodide (CY3) …

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Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake Jan 2016

Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake

Faculty Publications

This paper investigates the ability to improve Space Domain Awareness (SDA) by increasing the number of detectable Resident Space Objects (RSOs) from space surveillance sensors. With matched filter based techniques, the expected impulse response, or Point Spread Function (PSF), is compared against the received data. In the situation where the images are spatially undersampled, the modeled PSF may not match the received data if the RSO does not fall in the center of the pixel. This aliasing can be accounted for with a Multiple Hypothesis Test (MHT). Previously, proposed MHTs have implemented a test with an equal a priori prior …

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