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Air Force Institute of Technology

2016

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Articles 61 - 70 of 70

Full-Text Articles in Physical Sciences and Mathematics

Methods For Passive Remote Turbulence Characterization In The Planetary Boundary Layer, Lee R. Burchett Mar 2016

Methods For Passive Remote Turbulence Characterization In The Planetary Boundary Layer, Lee R. Burchett

Theses and Dissertations

Several methods are presented which allow for the index of refraction structure function constant, C2n , for visible light or IR systems to be determined remotely and passively using a combination of Numerical Weather Prediction, radar, and/or cell phone signals. These methods build on and extend existing techniques and theory, and are shown to be more accurate throughout the year than standard methods. Comparisons are made to 880nm scintillometer measurements of C2n in a temperate suburban and a rural high-desert environment.

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Population Density Measurements Of The Excited States Of An Optically Excited Argon Discharge Using Emission And Absorption Spectroscopy, Steven A. Owens Mar 2016

Population Density Measurements Of The Excited States Of An Optically Excited Argon Discharge Using Emission And Absorption Spectroscopy, Steven A. Owens

Theses and Dissertations

The populations of the excited argon 3s23p54s (s5 only) and 3s23p54p configurations in a 10 W radio frequency discharge has been studied using optical emission and diode laser absorption spectroscopy. By optically bleaching the s5→p9 transition with a narrow band laser pump of about 10 W/cm2 at 811 nm, the p9 population was increased by about a factor of 2 at a pressure of 5 Torr. At higher pressure, collisional mixing to adjacent p-states limited the laser-increased p9 population to less than 10 percent. All other laser-induced p-state populations were minimally affected …

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Kinetics Of Higher Lying Rb States After, Pulsed Excitation Of The D2 Transition In The Presence Of Helium, Austin J. Wallerstein Mar 2016

Kinetics Of Higher Lying Rb States After, Pulsed Excitation Of The D2 Transition In The Presence Of Helium, Austin J. Wallerstein

Theses and Dissertations

The Diode Pumped Alkali Laser (DPAL) is a high power, three-level laser system that employs diode bars to optically excite an alkali metal vapor. It lases along the D1 transition, between the two lowest energy levels, 2P1/2 and 2S1/2. Higher lying energy states are produced at higher population density via energy pooling and multiphoton processes. Pulsed laser excitation of rubidium at approximately 1 MW=cm2 has been studied at helium pressure up to 900 Torr. Emissions from energy states as high as 82D suggests modest ionization, though these intensities decrease drastically at buffer gas …

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A Logistic Regression And Markov Chain Model For The Prediction Of Nation-State Violent Conflicts And Transitions, Nicholas Shallcross Mar 2016

A Logistic Regression And Markov Chain Model For The Prediction Of Nation-State Violent Conflicts And Transitions, Nicholas Shallcross

Theses and Dissertations

Using open source data, this research formulates and constructs a suite of statistical models that predict future transitions into and out of violent conflict and forecasts the regional and global incidences of violent conflict over a ten-year time horizon. A total of thirty predictor variables are tested and evaluated for inclusion in twelve conditional logistic regression models, which calculate the probability that a nation will transition from its current conflict state, either In Conflict or Not in Conflict, to a new state in the following year. These probabilities are then used to construct a series of nation-specific Markov chain models …

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The Closo-Si12C12 Molecule From Cluster To Crystal: A Theoretical Prediction, Xiaofeng F. Duan, Larry W. Burggraf Mar 2016

The Closo-Si12C12 Molecule From Cluster To Crystal: A Theoretical Prediction, Xiaofeng F. Duan, Larry W. Burggraf

Faculty Publications

The structure of closo-Si12C12 is unique among stable SinCm isomers (n, m > 4) because of its high symmetry, π–π stacking of C6 rings and unsaturated silicon atoms at symmetrical peripheral positions. Dimerization potential surfaces reveal various dimerization reactions that form between two closo-Si12C12 molecules through Si–Si bonds at unsaturated Si atoms. As a result the closo-Si12C12 molecule is capable of polymerization to form stable 1D polymer chains, 2D crystal layers, and 3D crystals. 2D crystal structures formed by side-side polymerization satisfy eight Si valences on each monomer …

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Understanding Effects Of Autonomous Agent Timing On Human-Agent Teams Using Iterative Modeling, Simulation And Human-In-The-Loop Experimentation, Tyler J. Goodman Mar 2016

Understanding Effects Of Autonomous Agent Timing On Human-Agent Teams Using Iterative Modeling, Simulation And Human-In-The-Loop Experimentation, Tyler J. Goodman

Theses and Dissertations

Recent U.S. Air Force Research Laboratory strategy documents have suggested the need for research in human-agent teaming. Teaming supports a dynamic shift in roles between the human and the agent, depending upon human performance and mission needs. Further, because the performance of these agents will be highly dependent upon the state of the human and the mission, this strategy suggests the need for increased use of modeling to provide a broader understanding of the automated agent’s behavior. This thesis applies a combination of static modeling in SysML activity diagrams, dynamic modeling of human and agent behavior in IMPRINT, and human …

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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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A Recommendation System For Meta-Modeling: A Meta-Learning Based Approach, Can Cui, Mengqi Hu, Jeffery D. Weir, Teresa Wu Jan 2016

A Recommendation System For Meta-Modeling: A Meta-Learning Based Approach, Can Cui, Mengqi Hu, Jeffery D. Weir, Teresa Wu

Faculty Publications

Various meta-modeling techniques have been developed to replace computationally expensive simulation models. The performance of these meta-modeling techniques on different models is varied which makes existing model selection/recommendation approaches (e.g., trial-and-error, ensemble) problematic. To address these research gaps, we propose a general meta-modeling recommendation system using meta-learning which can automate the meta-modeling recommendation process by intelligently adapting the learning bias to problem characterizations. The proposed intelligent recommendation system includes four modules: (1) problem module, (2) meta-feature module which includes a comprehensive set of meta-features to characterize the geometrical properties of problems, (3) meta-learner module which compares the performance of instance-based …

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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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