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2010

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Articles 4381 - 4410 of 8620

Full-Text Articles in Physical Sciences and Mathematics

Fuel Efficiency Assessment With Dea, Evren Kiymaz Mar 2010

Fuel Efficiency Assessment With Dea, Evren Kiymaz

Theses and Dissertations

In this study, Data Envelopment Analysis (DEA) is used to calculate Air Mobility Command (AMC) airlift fuel efficiency for C-17 aircraft. Fuel is a strategic asset for the United States Air Force and suitable alternatives are not yet feasible or available in the quantity required. The Air Force is pursuing several initiatives to conserve energy and operate more efficiently while sustaining the same level of effectiveness and safety. In order to manage these initiatives, it must measure how well it is doing. To measure airlift efficiency, the AMC Fuel Efficiency Office established a 7 factor weighted Fuel Efficiency Index (FEI). …


Assessing The Economic And Environmental Impacts Associated With Current Street Lighting Technologies, Carlos J. Colon Jr. Mar 2010

Assessing The Economic And Environmental Impacts Associated With Current Street Lighting Technologies, Carlos J. Colon Jr.

Theses and Dissertations

Rising global energy demand and natural disasters continuously threaten energy supplies and prices. As a result, the U.S. government has mandated all government agencies to reduce energy consumption in order to minimize dependence on foreign energy supply and reduce costs. Concern over carbon emissions and environmental impacts has also been expressed in these mandates. One solution may be to invest in newer lighting technologies, such as light-emitting diode (LED) and electrodeless induction, in order to reduce the energy consumption, environmental impact, and costs required for both exterior roadway and parking lot lighting applications. This research compared these lighting technologies with …


A Study Of The Relationship Between Proenvironmental Product Use And Environmnetal Concern, Joshua M. Poulton Mar 2010

A Study Of The Relationship Between Proenvironmental Product Use And Environmnetal Concern, Joshua M. Poulton

Theses and Dissertations

To be sustainable, an organization must be balanced in the three principles of economy, environment, and society. Advances in pro-environmental technology have overcome roadblocks limiting the economic and environmental principles. The remaining hurdle to becoming sustainable is having society’s beliefs and behaviors align. Understanding the interaction between an individual’s environmental belief and environmental behaviors is essential to bringing them into alignment. To explore this relationship, a model was developed that included the new ecological paradigm (NEP) scale and a generalized version of the theory of planned behavior (TPB). The attitudes, intentions, and use of six pro-environmental products were measured in …


Security Vulnerability Trends Related To Electric Power Supplied At Military Installations, Peter A. Sabatowski Mar 2010

Security Vulnerability Trends Related To Electric Power Supplied At Military Installations, Peter A. Sabatowski

Theses and Dissertations

The United States (U.S.) electric grid is considered one of the greatest inventions of the twentieth century, yet it become apparent over the past few decades that it is not without its own set of problems. The deregulation of the U.S. electric system in the late 1990s eliminated monopolies and resulted in the nation's generation, transmission, and distribution systems becoming separate entities owned and operated by multiple companies. This created a market economy in which many electric companies failed to plan for the future, did not invest in maintenance and upgrades, and began to push the aggregate system to its …


Economic Feasibility Of Installing An Anaerobic Digester On A Department Of Defense Installation, Russell A. Strange Mar 2010

Economic Feasibility Of Installing An Anaerobic Digester On A Department Of Defense Installation, Russell A. Strange

Theses and Dissertations

Improving technology has made anaerobic digestion a viable method for disposing of organic waste and creating alternative energy. The purpose of this research was to examine the feasibility of installing an anaerobic digester on a Department of Defense installation, and measure its contribution to the execution of Executive Order 13423. A present worth equation was derived in accordance with 10 Code of Federal Regulations 436 expressing viable costs and benefits of an anaerobic digester. A case study of Wright Patterson Air Force Base (WPAFB) was then presented using the derived equation and operational data from functional digesters in the Ohio …


Improved Modeling Of Midlatitude D-Region Ionospheric Absorption Of High Frequency Radio Signals During Solar X-Ray Flares, Evelyn A. Schumer Mar 2010

Improved Modeling Of Midlatitude D-Region Ionospheric Absorption Of High Frequency Radio Signals During Solar X-Ray Flares, Evelyn A. Schumer

Theses and Dissertations

The purpose of this research was to improve modeling of midlatitude D-region ionospheric absorption of high frequency radio signals during solar X-ray flares through analysis of HF propagation data obtained during the HF Investigation of D-region Ionospheric Variation Experiment (HIDIVE) and obtained at the Canadian Space Agency NORSTAR riometer in Pinawa, Manitoba, Canada and X-ray flux data, as reported by GOES satellites. The findings of the data analysis were then used to validate and suggest improvements for two existing HF absorption models, the operational Space Weather Prediction Center (SWPC) D-region Absorption model and the physical AbbyNormal model. Analysis of the …


Optical And Electrical Characterization Of Bulk Grown Indium-Gallium-Arsenide Alloys, Austin C. Bergstrom Mar 2010

Optical And Electrical Characterization Of Bulk Grown Indium-Gallium-Arsenide Alloys, Austin C. Bergstrom

Theses and Dissertations

Advances in crystal growth techniques have allowed increased quality in growth of bulk ternary InxGa1-xAs. Here, the optical and electrical properties of samples grown through the vertical Bridgman (or multi-component zone melting growth) method have been investigated through photoluminescence spectroscopy and Hall effect measurements. Indium mole fractions varied from 0.75 for 1. Hall effect measurements at temperatures ranging from 10 to 300 K revealed moderate n-type doping with carrier concentrations ranging from 1.5 to 9.6×1016 cm-3 at 10 to 15 K. Carriers from deep donor levels became appreciable between 50 and 100 K. Hall …


Evaluation Of Interplanetary Magnetic Field Tracing Models Using Impulsive Seps, Brian P. Elliott Mar 2010

Evaluation Of Interplanetary Magnetic Field Tracing Models Using Impulsive Seps, Brian P. Elliott

Theses and Dissertations

Current Interplanetary Magnetic Field (IMF) models are evaluated in this study to determine which model(s) perform an accurate representation of this magnetic structure. These IMF models include the Parker Spiral model, the Potential Field Source Surface (PFSS) model, the Wang-Sheeley-Arge (WSA) model and the ENLIL model. Impulsive Solar Energetic Particles (SEPs) are used as tracers to determine the magnetic structure of the IMF and provide source locations for model comparisons. Each individual model is analyzed, compared to the identified solar source region and a longitude/latitude offset of these traces assigned. The model connection of the PFSS and Parker models is …


Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris Mar 2010

Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris

Theses and Dissertations

Investigation of the optical and electrical behavior of some semiconductors at very high temperatures has not been an area of much study, at least not experimentally. The importance of such research becomes obvious due to the effects of high temperatures on semiconductor devices such as infrared detectors and light emitters. Besides the destructive effects of thermal stress and melting, changes in the optical properties of the material can greatly affect device performance. In this research, the infrared absorption of Si, Ge, GaAs, GaSb, InAs, and InP was measured from 0.6 to 25 μm at temperatures ranging from 295 up to …


Thermal Neutron Point Source Imaging Using A Rotating Modulation Collimator (Rmc), Nathan O. Boyce Mar 2010

Thermal Neutron Point Source Imaging Using A Rotating Modulation Collimator (Rmc), Nathan O. Boyce

Theses and Dissertations

This thesis demonstrates a previously untested capability of the Rotating Modulation Collimator (RMC) to image a point-like neutron source. The encouraging results, achieved using low-energy neutrons, provide motivation for further refinement and continued research with higher-energy neutrons. The detector and the masks on an existing RMC imaging system were exchanged to function with neutrons. The source in this research produced a poly-energetic spectrum of neutrons through the reaction. The source of alpha particles was a 72.7 mCi 239Pu source. The RMC detector was located 250 cm from the bare source and operated for three hours to generate a modulation …


Changes To Electrical Conductivity In Irradiated Carbon-Nickel Nanocomposites, David F. Coy Mar 2010

Changes To Electrical Conductivity In Irradiated Carbon-Nickel Nanocomposites, David F. Coy

Theses and Dissertations

Pre and post irradiation resistivity and XAFS measurements have been conducted to examine the effects of 0.5 MeV electron irradiations on nickel-carbon composites. Results showed a decrease in surface resistivity in all sample types of 14-30% following irradiation with a total electron exposure of 4 x 10-16 cm-2. Results also showed a corresponding decrease in NiO content for the irradiated samples as compared to measurements of non-irradiated samples. Surface resistivity measurement capabilities were established and measurement techniques refined to produce repeatable results of sufficient precision to discern changes in resistivity for an exposure of 2 x 10 …


Improving Low Order, Linear, Positive Spatial Quadratures For The Partial Current Neutron Transport Method, John M. Snyder Mar 2010

Improving Low Order, Linear, Positive Spatial Quadratures For The Partial Current Neutron Transport Method, John M. Snyder

Theses and Dissertations

AFIT researchers have developed a new approach to solving Discrete Ordinates equations, which approximate the linear Boltzmann Transport Equation (BTE). The usual approach is von Neumann iteration on the scattering source, which requires repeated sweeps through the spatial-angular grid. Acceptable convergence requires complicated and expensive acceleration schemes. The new approach, Partial-Current Transport (PCT) with Adaptive Distribution Iteration, eliminates scattering source iteration through matrix inversions and a reduced-size global linear algebra problem. It creates the needed matrices directly from the standard spatial quadratures used in the sweeping. Positivity, linearity, and (higher-than-first-order) accuracy are the key desirable qualities with all Discrete Ordinates …


An Evaluation Of A Networked Radiation Detection System, Leif A. Hansen Mar 2010

An Evaluation Of A Networked Radiation Detection System, Leif A. Hansen

Theses and Dissertations

First responders assess a Nuclear/Radiological (NUCRAD) event in a timely and accurate manner by creating a site characterization that reflects the location of various levels of contamination based on their instruments’ readings. The survey team experiences difficulty in accurately recording this critical data due to the challenge of operating multiple devices and communicating the devices’ readings to other survey members. First responders produce a representation of the contamination or activity on a map that contain rings outlining the levels of activity and/or single locations of a single activity. Recently, several agencies began creating software programs that record a first responder’s …


Multi-Objective Constraint Satisfaction For Mobile Robot Area Defense, Kenneth W. Mayo Mar 2010

Multi-Objective Constraint Satisfaction For Mobile Robot Area Defense, Kenneth W. Mayo

Theses and Dissertations

In developing multi-robot cooperative systems, there are often competing objectives that need to be met. For example in automating area defense systems, multiple robots must work together to explore the entire area, and maintain consistent communications to alert the other agents and ensure trust in the system. This research presents an algorithm that tasks robots to meet the two specific goals of exploration and communication maintenance in an uncoordinated environment reducing the need for a user to pre-balance the objectives. This multi-objective problem is defined as a constraint satisfaction problem solved using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). Both …


A Distributed Network Logging Topology, Nicholas E. Fritts Mar 2010

A Distributed Network Logging Topology, Nicholas E. Fritts

Theses and Dissertations

Network logging is used to monitor computer systems for potential problems and threats by network administrators. Research has found that the more logging enabled, the more potential threats can be detected in the logs (Levoy, 2006). However, generally it is considered too costly to dedicate the manpower required to analyze the amount of logging data that it is possible to generate. Current research is working on different correlation and parsing techniques to help filter the data, but these methods function by having all of the data dumped in to a central repository. Central repositories are limited in the amount of …


Performance Characteristics Of A Kernel-Space Packet Capture Module, Samuel W. Birch Mar 2010

Performance Characteristics Of A Kernel-Space Packet Capture Module, Samuel W. Birch

Theses and Dissertations

Defending networks, network-connected assets, and the information they both carry and store is an operational challenge and a significant drain on resources. A plethora of historical and ongoing research efforts are focused on increasing the effectiveness of the defenses or reducing the costs of existing defenses. One valuable facet in defense is the ability to perform post mortem analysis of incidents that have occurred, and this tactic requires accurate storage and rapid retrieval of vast quantities of historical network data. This research improves the efficiency of capturing network packets to disk using commodity, general-purpose hardware and operating systems. It examines …


Developing Cyberspace Data Understanding: Using Crisp-Dm For Host-Based Ids Feature Mining, Joseph R. Erskine Mar 2010

Developing Cyberspace Data Understanding: Using Crisp-Dm For Host-Based Ids Feature Mining, Joseph R. Erskine

Theses and Dissertations

Current intrusion detection systems generate a large number of specific alerts, but do not provide actionable information. Many times, these alerts must be analyzed by a network defender, a time consuming and tedious task which can occur hours or days after an attack occurs. Improved understanding of the cyberspace domain can lead to great advancements in Cyberspace situational awareness research and development. This thesis applies the Cross Industry Standard Process for Data Mining (CRISP-DM) to develop an understanding about a host system under attack. Data is generated by launching scans and exploits at a machine outfitted with a set of …


Evolutionary Artificial Neural Network Weight Tuning To Optimize Decision Making For An Abstract Game, Corey M. Miller Mar 2010

Evolutionary Artificial Neural Network Weight Tuning To Optimize Decision Making For An Abstract Game, Corey M. Miller

Theses and Dissertations

Abstract strategy games present a deterministic perfect information environment with which to test the strategic capabilities of artificial intelligence systems. With no unknowns or random elements, only the competitors’ performances impact the results. This thesis takes one such game, Lines of Action, and attempts to develop a competitive heuristic. Due to the complexity of Lines of Action, artificial neural networks are utilized to model the relative values of board states. An application, pLoGANN (Parallel Lines of Action with Genetic Algorithm and Neural Networks), is developed to train the weights of this neural network by implementing a genetic algorithm over a …


Effects Of Channel Mismatches On Beamforming And Signal Detection, Christopher I. Allen Mar 2010

Effects Of Channel Mismatches On Beamforming And Signal Detection, Christopher I. Allen

Theses and Dissertations

Tuner gain measurements of a multichannel receiver are reported. A linear regression model is used to characterize the gain, as a function of channel number, tuner set-on frequency, and intermediate frequency. Residual errors of this model are characterized by a t distribution. Very strong autocorrelation of tuner gain at various frequencies is noted. Tuner performance from one channel to the next is diverse; several defects at specific frequencies are noted. The Wilcoxon signed rank test is used to test normality of tuner gain among devices; normality is rejected. Antenna directivity and phase pattern measurements are also reported. An antenna element …


Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady Mar 2010

Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady

Theses and Dissertations

Radar systems provide an important remote sensing capability, and are crucial to the layered sensing vision; a concept of operation that aims to apply the right number of the right types of sensors, in the right places, at the right times for superior battle space situational awareness. The layered sensing vision poses a range of technical challenges, including radar, that are yet to be addressed. To address the radar-specific design challenges, the research community responded with waveform diversity; a relatively new field of study which aims reduce the cost of remote sensing while improving performance. Early work suggests that the …


Handshaking Protocols And Jamming Mechanisms For Blind Rendezvous In A Dynamic Spectrum Access Environment, Aaron A. Gross Mar 2010

Handshaking Protocols And Jamming Mechanisms For Blind Rendezvous In A Dynamic Spectrum Access Environment, Aaron A. Gross

Theses and Dissertations

Blind frequency rendezvous is an important process for bootstrapping communications between radios without the use of pre-existing infrastructure or common control channel in a Dynamic Spectrum Access (DSA) environment. In this process, radios attempt to arrive in the same frequency channel and recognize each other’s presence in changing, under-utilized spectrum. This paper refines existing blind rendezvous techniques by introducing a handshaking algorithm for setting up communications once two radios have arrived in the same frequency channel. It then investigates the effect of different jamming techniques on blind rendezvous algorithms that utilize this handshake. The handshake performance is measured by determining …


Environmental Life Cycle Assessment Of Coal-Biomass To Liquid Jet Fuel Compared To Petroleum-Derived Jp-8 Jet Fuel, Wayne C. Kinsel Mar 2010

Environmental Life Cycle Assessment Of Coal-Biomass To Liquid Jet Fuel Compared To Petroleum-Derived Jp-8 Jet Fuel, Wayne C. Kinsel

Theses and Dissertations

The United States (U.S.) imported 57% of the petroleum products that it consumed in 2008. The Department of Defense (DOD) and in particular, the United States Air Force (USAF), consumes a large amount of oil to support the mission of defending the U.S. According to the USAF energy policy, by 2016, the Air Force (AF) must be prepared to cost competitively acquire 50% of its domestic aviation fuel requirement via an alternative fuel blend in which the alternative component is derived from domestic sources produced in a manner that is “greener” than fuels produced from conventional petroleum. This study employed …


Three Dimensional Positron Annihilation Momentum Measurement Technique (3dpamm) Applied To Measure Oxygen-Atom Defects In 6h Silicon Carbide, Christopher S. Williams Mar 2010

Three Dimensional Positron Annihilation Momentum Measurement Technique (3dpamm) Applied To Measure Oxygen-Atom Defects In 6h Silicon Carbide, Christopher S. Williams

Theses and Dissertations

A three-dimensional Positron Annihilation Spectroscopy System (3DPASS) capable to simultaneously measure three-dimensional electron-positron (e--e+) momentum densities measuring photons derived from e--e+ annihilation events was designed and characterized. 3DPASS simultaneously collects a single data set of correlated energies and positions for two coincident annihilation photons using solid-state double-sided strip detectors (DSSD). Positions of photons were determined using an interpolation method which measures a figure-of-merit proportional to the areas of transient charges induced on both charge collection strips directly adjacent to the charge collection strips interacting with the annihilation photons. The subpixel resolution was measured for both double-sided strip detectors (DSSD) and …


Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai Mar 2010

Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai

Theses and Dissertations

Insider threats can pose a great risk to organizations and by their very nature are difficult to protect against. Auditing and system logging are capabilities present in most operating systems and can be used for detecting insider activity. However, current auditing methods are typically applied in a haphazard way, if at all, and are not conducive to contributing to an effective insider threat security policy. This research develops a methodology for designing a customized auditing and logging template for a Linux operating system. An intent-based insider threat risk assessment methodology is presented to create use case scenarios tailored to address …


Coalition Formation Under Uncertainty, Daylond J. Hooper Mar 2010

Coalition Formation Under Uncertainty, Daylond J. Hooper

Theses and Dissertations

Many multiagent systems require allocation of agents to tasks in order to ensure successful task execution. Most systems that perform this allocation assume that the quantity of agents needed for a task is known beforehand. Coalition formation approaches relax this assumption, allowing multiple agents to be dynamically assigned. Unfortunately, many current approaches to coalition formation lack provisions for uncertainty. This prevents application of coalition formation techniques to complex domains, such as real-world robotic systems and agent domains where full state knowledge is not available. Those that do handle uncertainty have no ability to handle dynamic addition or removal of agents …


Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller Mar 2010

Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller

Theses and Dissertations

Laser induced fluorescence was used to study how pump pulse duration and alkali recycle time effects maximum power output in a Diode Pumped Alkali Laser (DPAL) system. A high intensity short pulsed pump source was used to excited rubidium atoms inside a DPAL-type laser. The maximum output power of the laser showed a strong dependence upon the temporal width of the pump pulse in addition to the input pump intensity. A linear relationship was observed between the maximum output power and the pulse width due to the effective lifetime of the excited state, defined as the time it takes for …


Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr Mar 2010

Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr

Theses and Dissertations

The purpose of this research was to use an atomic force microscope (AFM) to generate a 2-D square array of sub-wavelength surface features from a single material over a region large enough to permit optical characterization. This work is an extension of previous AFIT nano-patterning work and is in response to the small subunit sizes demanded for the production of optical metamaterials and photonic crystals. A diamond nano-indentation AFM probe was used to produce a 325-μm by 200-μm array of indentations in a 120-nm thick polystyrene film deposited on silicon. Indentation spacing of 400 nm produced well-defined surface features with …


Evaluation Of Alternative Technologies To Supply Drinking Water To Marines In Forward Deployed Locations, Derek R. George Mar 2010

Evaluation Of Alternative Technologies To Supply Drinking Water To Marines In Forward Deployed Locations, Derek R. George

Theses and Dissertations

With recent increases, there are approximately 20,000 Marines deployed in the Helmand Province of Afghanistan. The cost of delivering bottled water to the troops is rapidly becoming unsustainable and convoys delivering bottled water are vulnerable to Improvised Explosive Devices (IEDs). Currently, raw water from indigenous sources, which has chemical and microbiological contaminants, is treated with reverse osmosis (RO), but only used for hygiene, with bottled water used for drinking. Due to the economic costs and risks to life of providing bottled water, decision-makers need to evaluate technology alternatives to treat raw water to supply safe drinking water. In this study, …


Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler Mar 2010

Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler

Theses and Dissertations

Collisional cross sections were calculated as a function of energy for two coupled one dimensional, spherically symmetric potentials. The Split Operator Method was used to propagate an initial Moller state, chosen to be a Gaussian in the asymptotic limit, through a potential. The correlation between the wave packet and Moller final state was calculated at each time step. Using the Channel Packet Method, the correlation function was used to obtain scattering matrix elements. From scattering matrix elements for several different effective potential values and using the Method of Partial Waves, the collisional cross section is calculated for the transition from …


Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly Mar 2010

Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly

Theses and Dissertations

In an ever-increasing data rich environment, actionable information must be extracted, filtered, and correlated from massive amounts of disparate often free text sources. The usefulness of the retrieved information depends on how we accomplish these steps and present the most relevant information to the analyst. One method for extracting information from free text is Latent Dirichlet Allocation (LDA), a document categorization technique to classify documents into cohesive topics. Although LDA accounts for some implicit relationships such as synonymy (same meaning) it often ignores other semantic relationships such as polysemy (different meanings), hyponym (subordinate), meronym (part of), and troponomys (manner). To …