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Air Force Institute of Technology

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Articles 1261 - 1290 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran Mar 2010

Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran

Theses and Dissertations

Monte Carlo uncertainty quantification (UQ) capability has been added to a code for modeling multi-component steady-state isotope-separation enrichment cascades to characterize the propagation of uncertainties in input data that define the cascade and the feed. Random samples of error for every computational input are drawn from its individual uncertainty distribution and added to the inputs, creating a set of enrichment cascade problems with perturbed inputs. The set of problems is solved using the verified code. The cascade outputs are then characterized using the empirical cumulative distribution. The uncertainty output data are analyzed to gain new insights into the behaviors of …

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Nuclear Forensics: Measurements Of Uranium Oxides Using Time-Of-Flight Secondary Ion Mass Spectrometry (Tof-Sims), Wesley A. Schuler Mar 2010

Nuclear Forensics: Measurements Of Uranium Oxides Using Time-Of-Flight Secondary Ion Mass Spectrometry (Tof-Sims), Wesley A. Schuler

Theses and Dissertations

Over the past decade, law enforcement, governmental and public agencies have been stymied by the threat of the trafficking of nuclear materials. During this time span, reports from the International Atomic Energy Agency of illicit trafficking have increased eightfold from 20 to 160. For this reason, nuclear forensics is a burgeoning science focused on the identification of seized special nuclear materials. Identification of these materials is based upon the wealth of information that can be obtained by applying multiple analytical and measurement technologies. All of the information gained from each sample can then be used to further characterize other samples …

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Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy, Douglas E. Thornton Mar 2010

Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy, Douglas E. Thornton

Theses and Dissertations

To better understand the laser kinetics of an alkali gain medium, hard collisions, or velocity-changing collisions, has been studied and a velocity-changing collisional rate has been calculated. Previous works have studied these collisions, but no rate has been calculated. Using the precise tool of sub-Doppler spectroscopy, atomic hard collisions can be observed. The collected spectra are fitted with two different line shapes to demonstrate the accuracy of this method. From the fits, the number of hard collisions can be extracted. The time scale of the hard collisions in rubidium is interpolated by varying the chopping frequency of the pump beam, …

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A Multi-Objective Approach To A Bipartite Assignment Matching Problem Using Weighted Values From Multiple Contraints, Greg S. Jeong Mar 2010

A Multi-Objective Approach To A Bipartite Assignment Matching Problem Using Weighted Values From Multiple Contraints, Greg S. Jeong

Theses and Dissertations

US Air Force recruiters routinely assign new recruits to available jobs every month. The goal is to find the best assignments in an efficient manner. Although this problem is modeled as a bipartite assignment matching problem, it is not new to the field of Operations Research. This research presents a new approach to solve assignment matching problems given multiple side constraints. Using two multi-criteria optimization techniques, lexicographic optimization and the elastic constraint method, the assignment matching algorithm efficiently produces an optimal solution in a fraction of the time currently spent. This approach is demonstrated in assigning new USAF recruits to …

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An Evaluation Of Compressed Work Schedules And Their Impact On Electricity Use, Ryan R. Archambault-Miliner Mar 2010

An Evaluation Of Compressed Work Schedules And Their Impact On Electricity Use, Ryan R. Archambault-Miliner

Theses and Dissertations

As the largest energy consumer in the United States, the Department of Defense must consider all fiscally responsible means to improve energy efficiency. Budgetary and environmental concerns are a catalyst for numerous initiatives designed to reduce energy consumption. Congressional mandates outline the rate at which agencies must reduce facility energy use. In this study, Monte Carlo simulation was used to compare electricity consumption, cost, and emissions produced under 5-day workweeks and compressed work schedules. The research provides energy managers a template for evaluating compressed work schedules as a means to improve energy efficiency. The study found the relationship between the …

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Assessing Resilience In Power Grids As A Particular Case Of Supply Chain Management, Gabriel Alejandro Montoya Mar 2010

Assessing Resilience In Power Grids As A Particular Case Of Supply Chain Management, Gabriel Alejandro Montoya

Theses and Dissertations

Electrical power grids represent a critical infrastructure for a nation as well as strategically important. Literature review identified that power grids share basic characteristics with Supply Chain Management. This thesis presents a linear programming model to assess power grid resilience as a particular case of Supply Chain Management. Since resilient behavior is not an individual or specific system's attribute but a holistic phenomenon based on the synergic interaction within complex systems, resilience drivers in power grids were identified. Resilience is a function of Reliability, Recovery Capability, Vulnerability and Pipeline Capacity. In order to embed heterogeneous variables into the model, parameterization …

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Screening And Sufficiency In Multiobjective Decision Problems With Large Alternative Sets, Michael D. Cote Mar 2010

Screening And Sufficiency In Multiobjective Decision Problems With Large Alternative Sets, Michael D. Cote

Theses and Dissertations

Portfolio selection problems with combinatorially-large alternative sets can be impossible to evaluate precisely on a reasonable timescale. When portfolios require complex modeling for performance assessment, prohibitive computational processing times can result. Eliminating a small number of alternatives through an intelligent screening process can greatly reduce the number of alternative combinations, thereby decreasing a problem's evaluation time and cost. A methodology was developed for the class of hierarchical portfolio selection problems in which multiple objectives are all judged on the same sub-objectives. First, a novel capability-based alternative screening process was devised to identify and remove poor alternatives, thereby reducing the number …

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Developing A Qualia-Based Multi-Agent Architecture For Use In Malware Detection, Bobby D. Birrer Mar 2010

Developing A Qualia-Based Multi-Agent Architecture For Use In Malware Detection, Bobby D. Birrer

Theses and Dissertations

Detecting network intruders and malicious software is a significant problem for network administrators and security experts. New threats are emerging at an increasing rate, and current signature and statistics-based techniques are not keeping pace. Intelligent systems that can adapt to new threats are needed to mitigate these new strains of malware as they are released. This research detects malware based on its qualia, or essence rather than its low-level implementation details. By looking for the underlying concepts that make a piece of software malicious, this research avoids the pitfalls of static solutions that focus on predefined bit sequence signatures or …

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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). …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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