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Articles 9031 - 9060 of 11510

Full-Text Articles in Engineering

Steady State Stress In A Coated Infinite Half-Space Subjected To A Moving Load, Jason M. Cruthirds Mar 2005

Steady State Stress In A Coated Infinite Half-Space Subjected To A Moving Load, Jason M. Cruthirds

Theses and Dissertations

This research investigates the use of coatings to mitigate the stress distribution into an infinite half-space. High energy impact phenomenon at velocities exceeding the speed of sound is an important area of interest to the Air Force Research Laboratory. Holloman Air Force Base's High Speed Test Track sustains significant damage due to this phenomenon. In this thesis, the track system and coating are modeled analytically with equations of motion in terms of linear displacements. Coating thickness and material properties of epoxy or polymer laminates are investigated to understand their affect of stress distribution in the rail. An analytic solution is …

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Capacitance-Voltage Study On The Effects Of Low Energy Electron Radiation On Al0.27Ga0.73N/Gan High Electron Mobility Transistor, Thomas D. Jarzen Mar 2005

Capacitance-Voltage Study On The Effects Of Low Energy Electron Radiation On Al0.27Ga0.73N/Gan High Electron Mobility Transistor, Thomas D. Jarzen

Theses and Dissertations

The effects of radiation on semiconductors are extremely important to the Department of Defense since the majority of the defense informational, navigational and communications systems are now satellite-based. Due to the high radiation tolerance of gallium nitride and a plethora of high temperature, high power and high frequency applications, the prospect that gallium nitride based devices will become key components in a multitude of military satellite-based systems is highly probable. AlGaN/GaN HEMTs were irradiated at low temperature (~80 K) by 0.45 – 0.8 MeV electrons up to fluences of 1×1015 e-/cm2. Following irradiation, low temperature capacitance-voltage measurements …

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Simulation-Based Design Under Uncertainty For Compliant Microelectromechanical Systems, Jonathan W. Wittwer Mar 2005

Simulation-Based Design Under Uncertainty For Compliant Microelectromechanical Systems, Jonathan W. Wittwer

Theses and Dissertations

The high cost of experimentation and product development in the field of microelectromechanical systems (MEMS) has led to a greater emphasis on simulation-based design for increasing first-pass design success and reliability. The use of compliant or flexible mechanisms can help eliminate friction, wear, and backlash, but compliant MEMS are sensitive to variations in material properties and geometry. This dissertation proposes approaches for design stage uncertainty analysis, model validation, and robust optimization of nonlinear compliant MEMS to account for critical process uncertainties including residual stress, layer thicknesses, edge bias, and material stiffness. Methods for simulating and mitigating the effects of non-idealities …

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Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel Mar 2005

Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel

Theses and Dissertations

This study used simulation and experiment to design and test foil packets for use in the Activation Foil Integrated Detection System (AFIDS). The initial plan to activate foil packets outside with the pulse reactor at White Sands Missile Range (WSMR) was not possible due to WSMR not having safety approval to take the reactor outside. As an alternative, the concept of using liquid nitrous oxide inside a reactor to simulate large volumes of air was investigated. Simulation using the Standardized Computer Analyses for Licensing Evaluation (SCALE) program was used to select ten foils to be included in the foil packet. …

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The Purposes And Evaluation Methods For State Residential General Contractor Licensing, James Ellis Fenn Mar 2005

The Purposes And Evaluation Methods For State Residential General Contractor Licensing, James Ellis Fenn

Theses and Dissertations

The main topic in the licensing debate is whether licensing affects construction quality. Available literature and previous studies indicate that it does not. The real question is not whether licensing improves quality, but whether the improving quality is the actual purpose of licensing. There is little information available on the purpose of licensing as defined by state licensing departments as well as a general lack of information on how states evaluate whether licensing is fulfilling the intended purpose. In order to effectively resolve some of the issues surrounding the construction licensing debate, the true purpose of licensing and the methods …

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Feasibility Analysis Of A Compton Spectrometer System For Identification Of Special Nuclear Material, Chad C. Schools Mar 2005

Feasibility Analysis Of A Compton Spectrometer System For Identification Of Special Nuclear Material, Chad C. Schools

Theses and Dissertations

Current operational needs require the deployment of radiation detection equipment with the ability to accurately and reliably identify special nuclear materials and their byproducts without dependence on cryogenics. This requires a resolution of 0.5% or less over a range of 200 to 700 keV. The feasibility of a Compton spectrometer to achieve this resolution is examined. The Compton spectrometer system used consists of two detectors. The Compton scatter event occurs in a CdTe detector where the Compton electron energy is collected. Gamma rays scattered out of the CdTe at an angle determined by a conical collimator, are collected in a …

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Using Liquid Crystal Spatial Light Modulators For Closed Loop Tracking And Beam Steering With Phase Holography, Michael J. Perry Mar 2005

Using Liquid Crystal Spatial Light Modulators For Closed Loop Tracking And Beam Steering With Phase Holography, Michael J. Perry

Theses and Dissertations

Optical Phased Array (OPA) technology offers advantages in the reduction of size, weight, and power of optical steering devices. Nematic liquid crystal (LC) spatial light modulators (SLMs) have been studied as a potential candidate for building non-mechanical OPAs. They can steer a laser beam and split the beam into multiple beams. This thesis builds upon the prior research showing each split beam can be individually controlled, including variation in intensity. A closed loop tracking scenario shows the flexibility of the SLM by tracking and stabilizing an incoming beam. Results show that applying a phase grating to the SLM has limitations …

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An Analysis Of Seawinds Simultaneous Wind/Rain Retrieval In Severe Weather Events, Jeffrey R. Allen Mar 2005

An Analysis Of Seawinds Simultaneous Wind/Rain Retrieval In Severe Weather Events, Jeffrey R. Allen

Theses and Dissertations

Scatterometers, such as SeaWinds, can provide wide coverage of ocean surface winds. They estimate near-surface wind vectors by relating measured radar backscatter to a geophysical model function. However, SeaWinds measurements are also sensitive to rain, and conventional wind retrieval degrades in rainy conditions. An algorithm that exploits SeaWinds' sensitivity to both wind and rain has be developed. This algorithm, termed simultaneous wind/rain retrieval, retrieves both wind vectors and rain rates for a given ocean area. Instantaneous results of simultaneous wind/rain retrieval in Hurricane events is analyzed through comparison with the NEXRAD ground-based radar system. This comparison allows validation of retrieved …

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Optimization Of Automatic Target Recognition With A Reject Option Using Fusion And Correlated Sensor Data, Trevor I. Laine Mar 2005

Optimization Of Automatic Target Recognition With A Reject Option Using Fusion And Correlated Sensor Data, Trevor I. Laine

Theses and Dissertations

This dissertation examines the optimization of automatic target recognition (ATR) systems when a rejection option is included. First, a comprehensive review of the literature inclusive of ATR assessment, fusion, correlated sensor data, and classifier rejection is presented. An optimization framework for the fusion of multiple sensors is then developed. This framework identifies preferred fusion rules and sensors along with rejection and receiver operating characteristic (ROC) curve thresholds without the use of explicit misclassification costs as required by a Bayes' loss function. This optimization framework is the first to integrate both "vertical" warfighter output label analysis and "horizontal" engineering confusion matrix …

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Real-Time Evaluation Of Vision-Based Navigation For Autonomous Landing Of A Rotorcraft Unmanned Aerial Vehicle In A Non-Cooperative Environment, Dale D. Rowley Mar 2005

Real-Time Evaluation Of Vision-Based Navigation For Autonomous Landing Of A Rotorcraft Unmanned Aerial Vehicle In A Non-Cooperative Environment, Dale D. Rowley

Theses and Dissertations

Landing a rotorcraft unmanned aerial vehicle (RUAV) without human supervision is a capability that would significantly broaden the usefulness of UAVs. The benefits are even greater if the functionality is expanded to involve landing sites with unknown terrain and a lack of GPS or other positioning aids. Examples of these types of non-cooperative environments could range from remote mountainous regions to an urban building rooftop or a cluttered parking lot. The research of this thesis builds upon an approach that was initiated at NASA Ames Research Center to advance technology in the landing phase of RUAV operations. The approach consists …

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Flexural Behavior Of Carbon/Epoxy Isotruss Reinforced-Concrete Beam-Columns, Monica Joy Ferrell Mar 2005

Flexural Behavior Of Carbon/Epoxy Isotruss Reinforced-Concrete Beam-Columns, Monica Joy Ferrell

Theses and Dissertations

This thesis quantifies the flexural behavior (strength, stiffness and failure) of IsoTruss®-reinforced concrete beam-columns for use in deep foundation pile applications. Four-point bending tests were performed in the laboratory on two instrumented carbon/epoxy IsoTruss® reinforced concrete piles (IRC piles) and two instrumented steel reinforced concrete piles (SRC piles). The piles were approximately 14 ft (4.3 m) in length and 14 in (36 cm) in diameter and were loaded to failure while monitoring load, deflection, and strain data. The steel and IsoTruss®® reinforcement cages were designed to have equal flexural stiffness to permit a relative strength comparison. Moment curvature diagrams reveal …

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Developing New Multidimensional Knapsack Heuristics Based On Empirical Analysis Of Legacy Heuristics, Yong Kun Cho Mar 2005

Developing New Multidimensional Knapsack Heuristics Based On Empirical Analysis Of Legacy Heuristics, Yong Kun Cho

Theses and Dissertations

The multidimensional knapsack problem (MKP) has been used to model a variety of practical optimization and decision-making applications. Due to its combinatorial nature, heuristics are often employed to quickly find good solutions to MKPs. While there have been a variety of heuristics proposed for the MKP, and a plethora of empirical studies comparing the performance of these heuristics, little has been done to garner a deeper understanding of heuristic performance as a function of problem structure. This dissertation presents a research methodology, empirical and theoretical results explicitly aimed at gaining a deeper understanding of heuristic procedural performance as a function …

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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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Removal Of Cyclohexane From A Contaminated Air Stream Using A Dense Phase Membrane Bioreactor, Michael G. Roberts Mar 2005

Removal Of Cyclohexane From A Contaminated Air Stream Using A Dense Phase Membrane Bioreactor, Michael G. Roberts

Theses and Dissertations

The purpose of this research was to determine the ability of a dense phase membrane bioreactor to remove cyclohexane, a volatile organic compound in JP-8 jet fuel, from a contaminated air stream using a biologically active film for degradation. The research answered questions regarding applications of membrane bioreactors, the ability of cyclohexane to diffuse through a dense phase membrane, growth of a viable microbial culture, and determination of the performance capabilities of the reactor. To answer these questions, a literature review was conducted and laboratory experiments were performed. Through the design, construction, and testing of the dense phase membrane bioreactor …

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Validation Of An Innovative Groundwater Contaminant Flux Measurement Method, Seh J. Kim Mar 2005

Validation Of An Innovative Groundwater Contaminant Flux Measurement Method, Seh J. Kim

Theses and Dissertations

The ability to measure groundwater contaminant flux is increasingly being recognized as crucial in order to prioritize contaminated site cleanups, estimate the efficiency of remediation technologies, measure rates of natural attenuation, and apply proper source terms to model groundwater contaminant transport. An innovative mass flux measurement method using horizontal flow treatment wells (HFTWs) was developed recently to compensate for the disadvantages of other flux measurement methods that are being used. Flux measurement methods can be categorized as either point methods or integral methods. As the name suggests, point methods measure flux at a specific point or points in the subsurface. …

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An Investigation Into Palladium-Catalyzed Reduction Of Perchlorate In Water, Eric G. Barney Mar 2005

An Investigation Into Palladium-Catalyzed Reduction Of Perchlorate In Water, Eric G. Barney

Theses and Dissertations

In this study, application of a catalytic reactor to facilitate chemical reduction of perchlorate was investigated. Palladium-coated pellets were used as the catalyst, and formic acid was used as the reductant. Reactor performance was evaluated under a variety of operating conditions (influent pH, reductant concentration, residence time). Very little perchlorate reduction was observed under any operating condition. At best, approximately 8% perchlorate reduction was observed. This small reduction efficiency is clearly not sufficient for environmental treatment applications. Perchlorate strongly adsorbed to the catalyst at low pH (3 - 3.3). At higher pH (4 - 10), little adsorption was observed. This …

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Dynamic Modeling And Evaluation Of Recurring Infrastructure Maintenance Budget Determination Methods, Matthew P. Jefson Mar 2005

Dynamic Modeling And Evaluation Of Recurring Infrastructure Maintenance Budget Determination Methods, Matthew P. Jefson

Theses and Dissertations

The focus of this research is using system dynamics modeling to evaluate the impact of missed scheduled maintenance due to budgetary constraints. Missed maintenance cannot be made up and the benefit to the facility's serviceability is lost. The cumulative effect on an entire facility's life span is that it is unable to reach its designed life expectancy. Replacement construction costs are hundreds, thousands, or millions times more than the annual maintenance repair costs. Therefore, Air Force civil engineers must be capable of evaluating maintenance strategies in a dynamic environment to determine the budget strategy's prolonged effect on infrastructure serviceable life. …

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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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Exploratory Inquiry: Disparate Air Force Base Area Network Architectures, Charlie W. Boyd Jr. Mar 2005

Exploratory Inquiry: Disparate Air Force Base Area Network Architectures, Charlie W. Boyd Jr.

Theses and Dissertations

Joint Vision 2020, the Department of Defense (DoD) blueprint for development and transformation, identifies information and technology as critical enablers for our nation's military and calls for the development of a joint force capable of integrated information sharing to provide decision superiority, the ability to make and implement better decisions before enemies can react (DoD, 2000). Networks have been identified as the single most important element for transforming our current military forces. Ironically, Air Force base-level communications networks have been identified as a weakness. This research follows the qualitative approach to increases the current understanding of base level communications networks …

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Medical Devices, Support Networks, And Their Vulnerabilities: A Case Study Of The Integration Of Medical Networks Into The Air Force Information Network, Paul G. Oleksiak Mar 2005

Medical Devices, Support Networks, And Their Vulnerabilities: A Case Study Of The Integration Of Medical Networks Into The Air Force Information Network, Paul G. Oleksiak

Theses and Dissertations

With the implementation of "one Air Force, one network" under way it is important to look at how the Air Force plans to incorporate the medical field and its unique systems, networks, and mission. The medical field presents distinctive problems not seen in other areas. Open network vulnerabilities in the medical information systems not only pose a problem for the individual, but to the military service also. Possible security holes provide both access to vital military & personal information (end strength numbers, current status of personnel, social security), and a door way into the "network". Intruders now can possibly access …

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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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Determining A Relationship Between Foreign News Media Reports Covering U.S. Military Events And Network Incidents Against Dod Networks, Jason D. Jaros Mar 2005

Determining A Relationship Between Foreign News Media Reports Covering U.S. Military Events And Network Incidents Against Dod Networks, Jason D. Jaros

Theses and Dissertations

This thesis explores the nature of the relationship between foreign news media and network incidents against DoD networks. A rank correlation was performed between the number of network incidents against DoD networks and foreign news media reports covering U.S. Military events. Further analysis was conducted to determine the key terms used in the contents of foreign news media reports for the months the reports were significantly correlated with network incidents. Several significant correlations were found between various combinations of regions and categories of network incidents. However, the correlations were only moderate and the key terms only led to a slightly …

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A Study To Determine Damage Assessment Methods Or Models On Air Force Networks, Lisa S. Thiem Mar 2005

A Study To Determine Damage Assessment Methods Or Models On Air Force Networks, Lisa S. Thiem

Theses and Dissertations

Damage assessment for computer networks is a new area of interest for the Air Force. Previously, there has not been a concerted effort to codify damage assessment or develop a model that can be applied in assessing damage done by criminals, natural disasters, or other methods of damaging a computer network. The research undertaken attempts to identify if the Air Force MAJCOM Network Operations Support Centers (NOSC) use damage assessment models or methods. If the Air Force does use a model or method, an additional question of how the model was attained or decided upon is asked. All information comes …

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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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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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A Line-Of-Slight Sensor Network For Wide Area Video Surveillance: Simulation And Evaluation, Jamie R. Morrison Mar 2005

A Line-Of-Slight Sensor Network For Wide Area Video Surveillance: Simulation And Evaluation, Jamie R. Morrison

Theses and Dissertations

Substantial performance improvement of a wide area video surveillance network can be obtained with the addition of a Line-of-Sight sensor. The research described in this thesis shows that while the Line-of-Sight sensor cannot monitor areas with the ubiquity of video cameras alone, the combined network produces substantially fewer false alarms and superior location precision for numerous moving people than video. Recent progress in the fabrication of inexpensive, robust CMOS-based video cameras have triggered a new approach to wide area surveillance of busy areas such as modeling an airport corridor as a distributed sensor network problem. Wireless communication between these cameras …

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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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Weapon Release Scheduling From Multiple-Bay Aircraft Using Multi-Objective Evolutionary Algorithms, Francis R. Lyons Iv Mar 2005

Weapon Release Scheduling From Multiple-Bay Aircraft Using Multi-Objective Evolutionary Algorithms, Francis R. Lyons Iv

Theses and Dissertations

The United States Air Force has put an increased emphasis on the timely delivery of precision weapons. Part of this effort has been to us multiple bay aircraft such the B-1B Lancer and B-52 Stratofortress to provide Close Air Support and responsive strikes using 1760 weapons. In order to provide greater flexibility, the aircraft carry heterogeneous payloads which can require deconfliction in order to drop multiple different types of weapons. Current methods of deconfliction and weapon selection are highly crew dependent and work intensive. This research effort investigates the optimization of an algorithm for weapon release which allows the aircraft …

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Determination Of Structure From Motion Using Aerial Imagery, Paul R. Graham Mar 2005

Determination Of Structure From Motion Using Aerial Imagery, Paul R. Graham

Theses and Dissertations

The structure from motion process creates three-dimensional models from a sequence of images. Until recently, most research in this field has been restricted to land-based imagery. This research examines the current methods of land-based structure from motion and evaluates their performance for aerial imagery. Current structure from motion algorithms search the initial image for features to track though the subsequent images. These features are used to create point correspondences between the two images. The correspondences are used to estimate the motion of the camera and then the three-dimensional structure of the scene. This research tests current algorithms using synthetic data …

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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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