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Articles 154501 - 154530 of 194082

Full-Text Articles in Engineering

Executable Architectures And Their Application To A Geographically Distributed Air Operations Center, Robert J. Beal, Jeremy P. Hendrix, Garth P. Mcmurray, William C. Stewart Mar 2005

Executable Architectures And Their Application To A Geographically Distributed Air Operations Center, Robert J. Beal, Jeremy P. Hendrix, Garth P. Mcmurray, William C. Stewart

Theses and Dissertations

Integrated Architectures and Network Centric Warfare represent two central concepts in the Department of Defense's (DoD) on-going transformation. The true power of integrated architectures is brought to bear when they are combined with simulation to move beyond a static representation and create an executable architecture. This architecture can then be used to experiment with system configurations and parameter values to guide employment decisions. The process of developing and utilizing an executable architecture will be employed to assess an Air Operations Center (AOC). This thesis applies and expands upon the methodology of Dr. Alexander Levis, former Chief Scientist of the Air …

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Orbit Estimation Algorithms For A Microsatellite Rendezvous With A Non-Cooperative Target, John P. Heslin Mar 2005

Orbit Estimation Algorithms For A Microsatellite Rendezvous With A Non-Cooperative Target, John P. Heslin

Theses and Dissertations

This study investigated the minimum requirements to establish a satellite tracking system architecture for a microsatellite to rendezvous with a non-cooperative target satellite. A prototype optical tracking system was reviewed with emphasis on a proposed tactical employment that could be used by technologically unsophisticated state or non-state adversaries. With the tracking system architecture selected, simulated tracking data was processed with a Non-Linear Least Squares batch orbit estimation algorithm and a Bayes sequential orbit determination filter to update the target satellite's state vector.

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Technical Feasibility Of Loitering Lighter-Than-Air-Near-Space Maneuvering Vehicles, Eric R. Moomey Mar 2005

Technical Feasibility Of Loitering Lighter-Than-Air-Near-Space Maneuvering Vehicles, Eric R. Moomey

Theses and Dissertations

The near-space region of earth's atmosphere above 20 kilometers altitude is greatly underutilized. Lighter-than-air maneuvering vehicles, or airships, using the principle of buoyancy can take advantage of this region to become potential platforms for precision navigation, environmental monitoring, communication relays, missile warning, surveillance, and weapon delivery. These vehicles purportedly provide persistent coverage over large areas of the earth's surface at substantially lower costs than orbiting satellites. This study investigated the technical requirements to loiter an operational payload within this high altitude region using a lighter-than-air maneuvering platform. A parametric analysis was conducted to identify the critical technologies needed to achieve …

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Noise Estimation In The Presence Of Bpsk Digital Burst Transmissions, Susan E. Bettison Mar 2005

Noise Estimation In The Presence Of Bpsk Digital Burst Transmissions, Susan E. Bettison

Theses and Dissertations

This research explores noise estimation techniques in an attempt to improve upon a previously developed digital burst transmission Binary Phase Shift Keyed (BPSK) demodulator. The demodulator success is dependent on the accuracy of the estimate of Power Spectral Density (PSD) of the unknown noise. Given a discrete time signal transformed into the frequency domain, the research seeks to determine if it is possible to effectively estimate the PSD of the unknown noise. The demodulator was developed using a new signal model for digital burst transmissions based on linear spectral subspace theory. Using this model and the redundancy properties of BPSK …

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Timing Of Increasing Electron Counts From Geosynchronous Orbit To Low Earth Orbit, Kirk M. Olson Mar 2005

Timing Of Increasing Electron Counts From Geosynchronous Orbit To Low Earth Orbit, Kirk M. Olson

Theses and Dissertations

Under certain conditions, high energy electron fluxes can increase over short periods of time in the outer radiation belt and diffuse to low altitudes. Sudden increases of high energy electron densities at low altitudes can drastically damage unsuspecting low-earth-orbit satellites. The progression of electron flux increases from a geosynchronous orbit to low-earth orbit during an electron event is somewhat unknown. If the beginning of electron flux increases at low-earth-orbits could be anticipated, warnings could be issued to space system operators allowing time to take proper measures to protect and minimize satellite damage extending satellite lifetimes and space mission operations. The …

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Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli Mar 2005

Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli

Theses and Dissertations

Micro-Raman (µ-Raman) spectroscopy is used to measure residual stress in two silicon carbide (SiC) poly-types: single-crystal, hexagonally symmetric 6H-SiC, and polycrystalline, cubic 3C-SiC thin films deposited on Si substrates. Both are used in micro-electrical-mechanical systems (MEMS) devices. By employing an incorporated piezoelectric stage with submicron positioning capabilities along with the Raman spectral acquisition, spatial scans are performed to reveal areas in the 6H-SiC MEMS structures that contain residual stress. Shifts in the transverse optical (TO) Stokes peaks of up to 2 cm-1 are correlated to the material strain induced by the MEMS fabrication process through the development of phonon …

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Surface Oxidation Study Of Uranium Dioxide Under Wet And Dry Conditions, Gary T. Brett Mar 2005

Surface Oxidation Study Of Uranium Dioxide Under Wet And Dry Conditions, Gary T. Brett

Theses and Dissertations

The surface oxidation of pressed uranium dioxide (UO2) powder under controlled environmental conditions and the oxidation and reduction of pressed uranium trioxide (UO3) powder are presented. This is a continuing research project in the investigation of the oxidation of UO2 powder using Photoluminescence (PL) Spectroscopy. UO2 particles exposed to the ambient atmosphere will oxidize into a number of chemical complexes (specifically hydrates, hydroxides, and carbonates). During certain of these oxidation processes, the uranium ion can lose two of its electrons and change from uranous (UIV+) to uranyl (UVI+). This research …

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A Comparison Of Hazard Predication And Assessment Capability (Hpac) Software Dose-Rate Contour Plots To A Sample Of Local Fallout Data From Test Detonations In The Continental United States, 1945-1962, Richard W. Chancellor Mar 2005

A Comparison Of Hazard Predication And Assessment Capability (Hpac) Software Dose-Rate Contour Plots To A Sample Of Local Fallout Data From Test Detonations In The Continental United States, 1945-1962, Richard W. Chancellor

Theses and Dissertations

A comparison of Hazard Prediction and Assessment Capability (HPAC) software dose-rate contour plots to a sample of local nuclear fallout data from test detonations in the continental United States, 1945 - 1962, is performed. Fallout data from test detonations is obtained from "Compilation of Local Fallout Data from Test Detonations 1945- 1962 Extracted from DASA 1251, Volume I - Continental U.S. Tests." This report contains fallout plots and radiation contours for each test in the atmospheric nuclear test program conducted by the United States prior to 1963. These plots are compared with the plots resulting from Defense Threat Reduction Agency's …

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Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz Mar 2005

Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz

Theses and Dissertations

There are a number of analytical and semi-empirical models that describe the behavior of particulate matter in the atmosphere. Many of these require modification for all types of weather, dry versus wet deposition, and overall effects can be quite non-linear. Rainfall (rate, drop size, etc.), snowfall (rate, flake size, etc.), humidity, pressure, temperature, and combination of these greatly affect particle settling and washout rates. To that end, a method for tracking released constituents using the Regional Atmospheric Modeling System (RAMS) microphysics package is developed by modifying one of the hydrometeor categories (hail) in the microphysics package. The RAMS microphysics package …

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Temperature Dependent Current-Voltage Measurements Of Neutron Irradiated Al0.27Ga0.73N/Gan Modulation Doped Field Effect Transistors, Troy A. Uhlman Mar 2005

Temperature Dependent Current-Voltage Measurements Of Neutron Irradiated Al0.27Ga0.73N/Gan Modulation Doped Field Effect Transistors, Troy A. Uhlman

Theses and Dissertations

In this research, the first ever neutron irradiation study of AlGaN/GaN MODFETs was conducted. Devices irradiated to a total 1 MeV Eq (Si) neutron fluence of 1.2x1016 n/sq cm demonstrated the temperature dependence of irradiation and annealing. Devices irradiated at 80 K exhibited significant persistent electrical degradation at only 5.4 rad (Si), whereas those irradiated at elevated temperatures exhibit transient increases in gate and drain current up to 400 krad (Si). I-V measurements indicate substantial radiation-induced increased gate and drain currents occur only at low-temperature irradiations. The introduction of a high-density of donor defects is hypothesized as the primary …

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Using Value-Focused Thinking To Evaluate The Practicality Of Ground-Source Heat Pumps At Military Installations, Jimmy J. Jeoun Mar 2005

Using Value-Focused Thinking To Evaluate The Practicality Of Ground-Source Heat Pumps At Military Installations, Jimmy J. Jeoun

Theses and Dissertations

Because of potential cost and energy savings, military decision-makers may want to consider the use of energy-efficient heating, ventilating, and air-conditioning (HVAC) systems at their installations. Ground source heat pumps (GSHPs), in particular, show great promise because of their low energy requirements and low life-cycle costs. However, there currently exists no design guidance or established criteria for HVAC selection. Consequently, military decision-makers have no basis for comparing conventional HVAC systems and GSHPs. The Value-Focused Thinking (VFT) methodology was used to create a multi-objective decision analysis model that measures the value of different HVAC systems. Consisting of five bottom-tier values and …

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An Analysis Into The Effectiveness Of Aircraft Maintenance Under The Combat Wing Structure, Derrick R. Barthol Mar 2005

An Analysis Into The Effectiveness Of Aircraft Maintenance Under The Combat Wing Structure, Derrick R. Barthol

Theses and Dissertations

Organizational structure builds the foundation from which organizations operate. To gain full potential of structural efficiencies in the current operating environment, public and private firms are continually modifying their organizational structure. The U.S. Air Force is no different and underwent its most recent reorganization in the fall of 2002 replacing the post-Gulf War format of the previous decade. Air Force leadership needs to understand how well the current structure is performing at achieving its intended objectives. This research investigates the effectiveness of the recent change to Air Force organizational structure on aircraft maintenance performance through an analysis of aircraft maintenance …

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Minimizing Security Forces Response Times Through The Use Of Facility Location Methodologies, Michael C. Dawson Mar 2005

Minimizing Security Forces Response Times Through The Use Of Facility Location Methodologies, Michael C. Dawson

Theses and Dissertations

Since the events of September 11, 2001, security for the nation's Intercontinental Ballistic Missile force has become a prominent concern for personnel in the highest levels of government. This has resulted in many physical security upgrades and new methods to counter hostile activities. This research seeks to find the optimal placement for one layer of the security net protecting these crucial assets, the daily-deployed security forces Fire Teams. The problem of finding the optimal placement for these forces is modeled as a facility location problem. Three of the methods of locating facilities available in the literature are selected to solve …

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Comparing Management Approaches For Automatic Test Systems: A Strategic Missile Case Study, William C. Ford Mar 2005

Comparing Management Approaches For Automatic Test Systems: A Strategic Missile Case Study, William C. Ford

Theses and Dissertations

From 1980 to 1992, the DoD spent over $50 billion acquiring Automatic Test Systems (ATS) used to test weapon systems. At that time, procuring unique ATS to support single weapon systems was the norm. In 1994, the DoD made a dramatic change to their ATS acquisition policy; common ATS that supported multiple weapon systems was preferred over ATS tailored to support a single weapon system. Expected benefits of this new policy included: more reliable equipment, increased supportability, decreased cost, smaller logistics footprint, and decreased manning. To date, the common ATS initiative has garnered little support AF-wide due to lack of …

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Air Force Jp-8 Fuel Distribution System: A Statistical Analysis To Determine Where And When To Sample, Eric J. Heath Mar 2005

Air Force Jp-8 Fuel Distribution System: A Statistical Analysis To Determine Where And When To Sample, Eric J. Heath

Theses and Dissertations

The Air Force Petroleum Office at Wright-Patterson Air Force Base, Ohio collects JP-8 sampling data, but this data doesn't undergo analysis to determine the health of the base-level JP-8 fuel distribution system. Commanders possess no known confidence level when assessing base-level fuel health. Therefore, the objective of this research is to assess Air Force base-level fuel sampling data to determine the base-level sampling point that ensures a quality and healthy product at the aircraft. Also, this research seeks to identify how often correlation sampling should take place. Sample test pass rates are analyzed from three locations, receipt, storage, and vehicles/aircraft, …

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Selection And Application Of Distorted Risk Measures, Edwin J. Offutt Mar 2005

Selection And Application Of Distorted Risk Measures, Edwin J. Offutt

Theses and Dissertations

This thesis develops and illustrates a methodology for the selection of probability distributions and distortion functions associated with risk scenarios resulting from military capability shortfalls. Distorted (or transformed) risk measures are analyzed and applied to account for loss scenarios that may occur with low frequency but result in catastrophic outcomes. After reviewing the rudimentary concepts of distortion, four well-known continuous distributions, suitable for modeling risk scenarios, are chosen using defined criteria. Based on subject matter expert inputs, a simple method for assigning exactly one of the four distributions to any risk scenario is proposed. Four parametric distortion functions from the …

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Optimal Sampling Of A Chemical Hazard Area, Jennifer R. Plourde Mar 2005

Optimal Sampling Of A Chemical Hazard Area, Jennifer R. Plourde

Theses and Dissertations

This thesis proposes a methodology for optimally sampling a chemical hazard area subsequent to a chemical weapons attack. The objective is to identify the maximum number of areas that no longer require protective gear for safe operations. We model the area as an undirected graph and employ network analysis techniques to provide a methodological framework for identifying an optimal sampling sequence within a fixed time limit. We propose four models that characterize the secondary vapor concentrations: i) static and deterministic, ii) static and stochastic, iii) dynamic and deterministic, and iv) dynamic and stochastic. Comparisons of the static cases and their …

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Strategic Airlift En Route Analysis And Considerations To Support The Global War On Terrorism, Michael C. Sere Mar 2005

Strategic Airlift En Route Analysis And Considerations To Support The Global War On Terrorism, Michael C. Sere

Theses and Dissertations

The Global War on Terrorism has mandated the need for additional global en route airfields. En route airfields consist of bases that are strategically located at intermediate locations between the Continental United States and the intended theater of operations. These airfields serve as refueling, crew staging, or maintenance stops for strategic airlift aircraft flying transoceanic routes. The focus of this study is to examine concepts to meet this need and to address important aspects that should be considered in devising new en route strategies. Based on various important factors associated with potential en route airfields, a goal programming methodology was …

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An Evaluation Of Wind Turbine Technology At Peterson Afb, Randy C. Combs Mar 2005

An Evaluation Of Wind Turbine Technology At Peterson Afb, Randy C. Combs

Theses and Dissertations

Wind energy technology is a viable source for attaining the emission reduction and renewable energy use goals set forth by the executive office. In accordance with Executive Orders, the Air Force must reduce greenhouse emissions and energy consumption, and expand the use of renewable energy sources within its facilities nation-wide by year 2010. This mandate requires that the Air Force look at alternative electrical production and rely more on such renewable energy resources as wind power. The specific problem addressed by this research is whether on-site wind energy generation can be more economically feasible than the conventional energy consumption at …

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Estimating Performance Time For Air Force Military Construction Projects, Greg J. Hoffman Mar 2005

Estimating Performance Time For Air Force Military Construction Projects, Greg J. Hoffman

Theses and Dissertations

The prediction of construction time performance is a problem of interest to both researchers and construction industry practitioners. This research seeks to identify significant factors which may influence construction durations for Air Force Military Construction (MILCON) projects to establish a time prediction model. Data were collected for 856 MILCON projects completed between 1988 and 2004; this included both traditional facility and non-facility (e.g. airfield pavements, utilities) projects. These data were analyzed using Bromilow's time-cost (BTC) model (1969) as well as multiple linear regression. Neither model produced acceptable results for non-facility projects; however, the multiple linear regression model was found to …

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An Analysis Of The Relationship Between Environmental Management And Environmental Compliance At Marine Corps Installations, Bevin J. Keen Mar 2005

An Analysis Of The Relationship Between Environmental Management And Environmental Compliance At Marine Corps Installations, Bevin J. Keen

Theses and Dissertations

Environmental compliance on military is challenging for a number of reasons, including the complexity of regulations, and the variety of operations which impact the environment. At times, public concerns and penalties stemming from environmental issues has infringed upon the United States Marine Corps' (USMC) ability to use all installation resources without restriction. This thesis examines which facets of environmental management are closely associated with high levels of compliance. Five variables of interest: Total Compliance, Total Management, Audit Management, Policy Management, and Training Management were isolated from 1998-2004 USMC environmental audit data, and subjected to statistical analysis. Through the examination of …

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Decision Analysis Using Value-Focused Thinking To Select Renewable Alternative Fuels, Eric A. Queddeng Mar 2005

Decision Analysis Using Value-Focused Thinking To Select Renewable Alternative Fuels, Eric A. Queddeng

Theses and Dissertations

The United States relies on imported oil as a result of domestic petroleum consumption rates greatly exceeding production rates. Alternative fuels are a major force in the effort to reduce petroleum consumption in the transportation industry. The transportation industry also accounts for 1/3 of all greenhouse gas emissions and nearly half of all cancers attributed to outdoor sources of pollutants. The purpose of this research was to evaluate the economic and environmental feasibility of renewable alternative fuels and associated blends (ethanol, methanol, 100% biodiesel (B100), 20% biodiesel (B20) and e-diesel) compared to non-renewable alternative fuels (compressed natural gas and propane) …

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Decision Analysis Using Value-Focused Thinking For Infrastructure Prioritization, Mona A. Tenorio Mar 2005

Decision Analysis Using Value-Focused Thinking For Infrastructure Prioritization, Mona A. Tenorio

Theses and Dissertations

Infrastructure systems and facilities have deteriorated due to the impact of limited defense funding and competing priorities within the Air Force. The current method used for infrastructure prioritization is influenced by political sensitivity and uncertainty regarding the consequences of various funding decisions. Senior leaders need to better understand how their funding decisions will impact the overall condition and service life of the installation's infrastructure systems and facilities. The purpose of this research was to improve the method of prioritizing infrastructure projects through the use of a decision analysis methodology known as Value-Focused Thinking. The value model was created based on …

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Assessing The Usefulness Of The Decision Framework For Identifying And Selecting Knowledge Management Projects, Kevin G. Budai Mar 2005

Assessing The Usefulness Of The Decision Framework For Identifying And Selecting Knowledge Management Projects, Kevin G. Budai

Theses and Dissertations

Knowledge management (KM) is becoming recognized as a valuable tool for the Department of Defense (DoD) in its effort to maintain a competitive, strategic advantage against its enemies in a new threat environment. Decision superiority is the ultimate end result and is only possible through the effective and efficient use of its chief key resource--knowledge. As the Air Force seeks to transform the way it does business the concept of knowledge management has made its way to the forefront of both the Air Force's Information Strategy and Information Resource Flight Plan. This research assesses the usefulness of a knowledge management …

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Status Of Department Of Defense Architecture Framework (Dodaf) Implementation Within The Aeronautical Systems Center (Asc), Chad A. Millette Mar 2005

Status Of Department Of Defense Architecture Framework (Dodaf) Implementation Within The Aeronautical Systems Center (Asc), Chad A. Millette

Theses and Dissertations

The purpose of this research was to identify the current status of the use of the Department of Defense Architecture Framework (DoDAF) systems architecture products within the Aeronautical Systems Center (ASC) program offices. There are regulatory requirements dictating the creation of DoDAF products as annexes to programmatic documentation, such as the Joint Capabilities Integration Development System (JCIDS) requirement for systems architectures as annexes for acquisition milestone decision documentation. In addition, the DoDAF itself identifies several products as being highly applicable for the development of acquisition strategies. This thesis investigated the use of systems architectures, and particularly DoDAF products, within the …

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Performance Based Service Acquisition: A Quantitative Evaluation Of Implementation Goals And Performance In The United States Air Force, Dylan D. Pope Mar 2005

Performance Based Service Acquisition: A Quantitative Evaluation Of Implementation Goals And Performance In The United States Air Force, Dylan D. Pope

Theses and Dissertations

In an attempt to maximize cost savings in the rapidly growing services sector, the DoD established a Performance Based Service Acquisition (PBSA) strategy that focuses on evaluating contractor performance based on their ability to meet desired outcomes rather than the means to which the outcomes are obtained. In April 2000, Dr. Gansler, then Under Secretary of Defense for Acquisition, Technology and Logistics, mandated that 50 percent of all eligible service acquisitions be awarded using PBSA methods by FY 2005. Since then very little research has been focused on USAF implementation of PBSA and the progress and attainment of the PBSA …

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Enabling Intrusion Detection In Ipsec Protected Ipv6 Networks Through Secret-Key Sharing, Patrick J. Sweeney Mar 2005

Enabling Intrusion Detection In Ipsec Protected Ipv6 Networks Through Secret-Key Sharing, Patrick J. Sweeney

Theses and Dissertations

As the Internet Protocol version 6 (IPv6) implementation becomes more widespread, the IP Security (IPSec) features embedded into the next-generation protocol will become more accessible than ever. Though the network-layer encryption provided by IPSec is a boon to data security, its use renders standard network intrusion detection systems (NIDS) useless. The problem of performing intrusion detection on encrypted traffic has been addressed by differing means with each technique requiring one or more static secret keys to be shared with the NIDS beforehand. The problem with this approach is static keying is much less secure than dynamic key generation through the …

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Simple Public Key Infrastructure Analysis Protocol Analysis And Design, Alexander G. Vidergar Mar 2005

Simple Public Key Infrastructure Analysis Protocol Analysis And Design, Alexander G. Vidergar

Theses and Dissertations

Secure electronic communication is based on secrecy, authentication and authorization. One means of assuring a communication has these properties is to use Public Key Cryptography (PKC). The framework consisting of standards, protocols and instructions that make PKC usable in communication applications is called a Public Key Infrastructure (PKI). This thesis aims at proving the applicability of the Simple Public Key Infrastructure (SPKI) as a means of PKC. The strand space approach of Guttman and Thayer is used to provide an appropriate model for analysis. A Diffie-Hellman strand space model is combined with mixed strand space proof methods for proving the …

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Geolocation Of A Node On A Local Area Network, John R. Clarson Mar 2005

Geolocation Of A Node On A Local Area Network, John R. Clarson

Theses and Dissertations

Geolocation is the process of identifying a node using only its Internet Protocol (IP) address. Locating a node on a LAN poses particular challenges due to the small scale of the problem and the increased significance of queuing delay. This study builds upon existing research in the area of geolocation and develops a heuristic tailored to the difficulties inherent in LANs called the LAN Time to Location Heuristic (LTTLH). LTTLH uses several polling nodes to measure latencies to end nodes, known locations within the LAN. The Euclidean distance algorithm is used to compare the results with the latency of a …

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Using Multiple Mems Imus To Form A Distributed Inertial Measurement Unit, Ryan D. Hanson Mar 2005

Using Multiple Mems Imus To Form A Distributed Inertial Measurement Unit, Ryan D. Hanson

Theses and Dissertations

MEMS IMUs are readily available in quantity and have extraordinary advantages over conventional IMUs in size, weight, cost, and power consumption. However, the poor performance of MEMS IMUs limits their use in more demanding military applications. It is desired to use multiple distributed MEMS IMUs to simulate the performance of a single, more costly IMU, using the theory behind Gyro-Free IMUs. A Gyro-Free IMU (GF-IMU) uses a configuration of accelerometers only to measure the three accelerations and three angular rotations of a rigid body in 3-D space. Theoretically, almost any configuration of six distributed accelerometers yields sufficient measurements to solve …

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