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Articles 5821 - 5850 of 11510

Full-Text Articles in Engineering

Unique Two-Way Field Probe Concept Utilizing A Geodesic Sphere And Quad-Rotor, Travis A. Albee Mar 2015

Unique Two-Way Field Probe Concept Utilizing A Geodesic Sphere And Quad-Rotor, Travis A. Albee

Theses and Dissertations

Surveying the test volume of a radar range normally involves utilizing an antenna field probe to measure the electromagnetic field in that volume of space. Today, field probes vary in size and shape and can be difficult and time consuming to setup. They also have a limited range of motion due to their support structure and translational mechanism, which also has scattering mechanisms that can perturb the field they are measuring. Field probes are useful, but because of these shortcomings they can provide limited characterization of the field illuminating the measurement area. Leveraging quad-rotor technology, coupled with a two-way probe …

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Single Platform Geolocation Of Radio Frequency Emitters, Eric J. Bailey Mar 2015

Single Platform Geolocation Of Radio Frequency Emitters, Eric J. Bailey

Theses and Dissertations

The focus of this research is on single platform geolocation methods where the position of a single stationary radio frequency emitter is estimated from multiple simulated angle and frequency of arrival measurements taken from a single moving receiver platform. The analysis scenario considered consists of a single 6U CubeSat in low earth orbit receiving radio frequency signals from a stationary emitter located on the surface of the Earth. A multiple element receive antenna array and the multiple signal classification algorithm are used to estimate the angles of arrival of an impinging signal. The maximum likelihood estimator is used to estimate …

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Identifying Image Manipulation Software From Image Features, Devlin T. Boyter Mar 2015

Identifying Image Manipulation Software From Image Features, Devlin T. Boyter

Theses and Dissertations

As technology steadily increases in the field of image manipulation, determining which software was used to manipulate an image becomes increasingly complex for law enforcement and intelligence agencies. To combat this difficult problem, new techniques that examine the artifacts left behind by a specific manipulation are converted to features for classification. This research implemented four preexisting image manipulation detection techniques into a framework of modules: Two-Dimensional Second Derivative, One-Dimensional Zero Crossings, Quantization Matrices Identification, and File Metadata analysis. The intent is the creation of a framework to develop a capability to determine which specific image manipulation software program manipulated an …

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Static Scene Statistical Non-Uniformity Correction, Adrian M. Catarius Mar 2015

Static Scene Statistical Non-Uniformity Correction, Adrian M. Catarius

Theses and Dissertations

Non-Uniformity Correction (NUC) is required to normalize imaging detector Focal-Plane Array (FPA) outputs due to differences in the end-to-end photoelectric responses between pixels. Currently, multi-point NUC methods require static, uniform target scenes of a known intensity for calibration. Conversely, scene-based NUC methods do not require a priori knowledge of the target but the target scene must be dynamic. The new Static Scene Statistical Non-Uniformity Correction (S3NUC) algorithm was developed to address an application gap left by current NUC methods. S3NUC requires the use of two data sets of a static scene at different mean intensities but does not require a …

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Leveraging Human Insights By Combining Multi-Objective Optimization With Interactive Evolution, Joshua R. Christman Mar 2015

Leveraging Human Insights By Combining Multi-Objective Optimization With Interactive Evolution, Joshua R. Christman

Theses and Dissertations

Deceptive fitness landscapes are a growing concern for evolutionary computation. Recent work has shown that combining human insights with short-term evolution has a synergistic effect that accelerates the discovery of solutions. While humans provide rich insights, they fatigue easily. Previous work reduced the number of human evaluations by evolving a diverse set of candidates via intermittent searches for novelty. While successful at evolving solutions for a deceptive maze domain, this approach lacks the ability to measure what the human evaluator identifies as important. The key insight here is that multi-objective evolutionary algorithms foster diversity, serving as a surrogate for novelty, …

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The Theory And Application Of Privacy-Preserving Computation, Michael R. Clark Mar 2015

The Theory And Application Of Privacy-Preserving Computation, Michael R. Clark

Theses and Dissertations

Privacy is a growing concern in the digital world as more information becomes digital every day. Often the implications of how this information could be exploited for nefarious purposes are not explored until after the fact. The public is becoming more concerned about this. This dissertation introduces a new paradigm for tackling the problem, namely, transferable multiparty computation (T-MPC). T-MPC builds upon existing multiparty computation work yet allows some additional flexibility in the set of participants. T-MPC is orders of magnitude more efficient for certain applications. This greatly increases the scalability of the sizes of networks supported for privacy-preserving computation.

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Materials Characterization And Microelectronic Implementation Of Metal-Insulator Transition Materials And Phase Change Materials, Alexander H. Gwin Mar 2015

Materials Characterization And Microelectronic Implementation Of Metal-Insulator Transition Materials And Phase Change Materials, Alexander H. Gwin

Theses and Dissertations

Vanadium dioxide (VO2) is a metal-insulator transition (MIT) material, and germanium telluride (GeTe) is a phase change material (PCM), both of which undergo several orders of magnitude increase in electrical conductivity from room temperature to their transition temperatures. They are candidates for many important technologies, including ultra-fast electronic memory, optical switches and filters, and active layers in terahertz metamaterials, among others. The physical mechanisms causing the phase transitions in these materials are explained and investigated experimentally. These materials were incorporated into six types of microelectronic devices, which were designed, fabricated, and tested at the Air Force Institute of …

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Gate-Level Commercial Microelectronics Verification With Standard Cell Recognition, Leleia A. Hsia Mar 2015

Gate-Level Commercial Microelectronics Verification With Standard Cell Recognition, Leleia A. Hsia

Theses and Dissertations

Within the past two decades, the problem of counterfeit hardware has gained significant attention within the Department of Defense (DoD). Counterfeit electronics compromise national security systems as they may fail to meet durability requirements and/or contain malicious circuits [6, 16, 17]. This necessitates the development of methods to detect counterfeit electronics and prevent the counterfeit electronics from entering DoD systems. The DARPA TRUST program was established to address the need to verify integrated circuit (IC) electronics. This research describes the development of standard cell recognition (SCR) software intended to resolve conflicts in prior TRUST related applications of commercial software to …

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Improving The Performance Of The Space Surveillance Telescope As A Function Of Seeing Parameter, Jae H. Jeon Mar 2015

Improving The Performance Of The Space Surveillance Telescope As A Function Of Seeing Parameter, Jae H. Jeon

Theses and Dissertations

This research paper investigates ways to improve the detection capability and predict the performance of the Space Surveillance Telescope (SST) system when it's relocated to Exmouth, Australia. The dataset collected by the SST observing the Geosynchronous Earth Orbit (GEO) satellite, ANIK-F1, entering the earth's eclipse is used to test the performance of the three existing and one new detection algorithm. The three existing algorithms are the point detection (Binary Hypothesis Test (BHT)), correlation detection (CD-BHT), and Multi-hypothesis Test using ten hypotheses (MHT10), and the new detection algorithm is the Multi-hypothesis Test using six hypotheses (MHT6). To improve the accuracy and …

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Theoretical Limits Of Lunar Vision Aided Navigation With Inertial Navigation System, David W. Jones Mar 2015

Theoretical Limits Of Lunar Vision Aided Navigation With Inertial Navigation System, David W. Jones

Theses and Dissertations

The precision navigation capabilities of the Global Positioning System (GPS) are used extensively within US military operations. However, GPS is highly vulnerable to intentional and unintentional external interference. Therefore, a need exists to develop a non-GPS precision navigation method to operate in GPS degraded environments. This research effort presents the theoretical limits of a precision navigation method based on an inertial navigation system (INS) aided by angle measurements with respect to lunar surface features observed by a fixed camera. To accomplish this task, an extended Kalman filter (EKF) was implemented to estimate INS drift errors and bring in simulated lunar …

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Fpga Accelerated Discrete-Surf For Real-Time Homography Estimation, Andrew C. Leighner Mar 2015

Fpga Accelerated Discrete-Surf For Real-Time Homography Estimation, Andrew C. Leighner

Theses and Dissertations

This paper describes our hardware accelerated, FPGA implementation of SURF, named Discrete SURF, to support real-time homography estimation for close range aerial navigation. The SURF algorithm provides feature matches between a model and a scene which can be used to find the transformation between the camera and the model. Previous implementations of SURF have partially employed FPGAs to accelerate the feature detection stage of upright only image comparisons. We extend the work of previous implementations by providing an FPGA implementation that allows rotation during image comparisons in order to facilitate aerial navigation. We also expand beyond feature detection as the …

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Pilot Assisted Inertial Navigation System Aiding Using Bearings-Only Measurements Taken Over Time, Anthony T. Mirabile Mar 2015

Pilot Assisted Inertial Navigation System Aiding Using Bearings-Only Measurements Taken Over Time, Anthony T. Mirabile

Theses and Dissertations

The objective of this work is to develop an alternative INS aiding source other than the GPS, while preserving the autonomy of the integrated navigation system. It is proposed to develop a modernized method of aerial navigation using driftmeter measurements from an E/O system for ground feature tracking, and an independent altitude sensor in conjunction with the INS. The pilot will track a ground feature with the E/O system, while the aircraft is on autopilot holding constant airspeed, altitude, and heading during an INS aiding session. The ground feature measurements from the E/O system and the INS output form measurements …

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Estimating Single And Multiple Target Locations Using K-Means Clustering With Radio Tomographic Imaging In Wireless Sensor Networks, Jeffrey K. Nishida Mar 2015

Estimating Single And Multiple Target Locations Using K-Means Clustering With Radio Tomographic Imaging In Wireless Sensor Networks, Jeffrey K. Nishida

Theses and Dissertations

Geolocation involves using data from a sensor network to assess and estimate the location of a moving or stationary target. Received Signal Strength (RSS), Angle of Arrival (AoA), and/or Time Difference of Arrival (TDoA) measurements can be used to estimate target location in sensor networks. Radio Tomographic Imaging (RTI) is an emerging Device-Free Localization (DFL) concept that utilizes the RSS values of a Wireless Sensor Network (WSN) to geolocate stationary or moving target(s). The WSN is set up around the Area of Interest (AoI) and the target of interest, which can be a person or object. The target inside the …

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Modeling Navigation System Performance Of A Satellite-Observing Star Tracker Tightly Integrated With An Inertial Measurement Unit, Scott J. Pierce Mar 2015

Modeling Navigation System Performance Of A Satellite-Observing Star Tracker Tightly Integrated With An Inertial Measurement Unit, Scott J. Pierce

Theses and Dissertations

This dissertation evaluates a navigation system using satellite observations from a star tracker tightly-integrated with an inertial measurement unit (IMU) and a barometric altimeter using an extended Kalman filter. The star tracker measurement accuracy of a satellite is derived. Several system configurations are simulated comparing the performance of the estimate with respect to system parameters of the IMU, and star tracker, as well as comparing performance when providing a remote sensor satellite ephemeris error correction. Experimental observations are used to evaluate the model performance. Additionally, power requirements were calculated for a satellite signal operating in imaging bands, such that a …

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A Novel Analysis Of Performance Classification And Workload Prediction Using Electroencephalography (Eeg) Frequency Data, Donovan L. Ricks Mar 2015

A Novel Analysis Of Performance Classification And Workload Prediction Using Electroencephalography (Eeg) Frequency Data, Donovan L. Ricks

Theses and Dissertations

Across the DOD each task an operator is presented with has some level of difficulty associated with it. This level of difficulty over the course of the task is also known as workload, where the operator is faced with varying levels of workload as he or she attempts to complete the task. The focus of the research presented in this thesis is to determine if those changes in workload can be predicted and to determine if individuals can be classified based on performance in order to prevent an increase in workload that would cause a decline in performance in a …

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Counter Weapon Control, Brian J. Roadruck Mar 2015

Counter Weapon Control, Brian J. Roadruck

Theses and Dissertations

In this work, pursuit-evasion differential game theory is applied to the target defense scenario. The targets, attackers, and the defenders positional information is assumed to be known to the players. With positional information, a computational efficient method of strategy synthesis can be derived applying a differential game theory approach. We demonstrate that when non-optimal strategies are employed by one of the players, e.g. Line Of Sight guidance, the outcome will favor the players that employ the optimal strategy given by the solution of the pursuit-evasion differential game.

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Urban Environment Navigation With Real-Time Data Utilizing Computer Vision, Inertial, And Gps Sensors, Johnathan L. Rohde Mar 2015

Urban Environment Navigation With Real-Time Data Utilizing Computer Vision, Inertial, And Gps Sensors, Johnathan L. Rohde

Theses and Dissertations

The purpose of this research was to obtain a navigation solution that used real data, in a degraded or denied global positioning system (GPS) environment, from low cost commercial o the shelf sensors. The sensors that were integrated together were a commercial inertial measurement unit (IMU), monocular camera computer vision algorithm, and GPS. Furthermore, the monocular camera computer vision algorithm had to be robust enough to handle any camera orientation that was presented to it. This research develops a visual odometry 2-D zero velocity measurement that is derived by both the features points that are extracted from a monocular camera …

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Non-Linear Optimization Applied To Angle-Of-Arrival Satellite-Based Geolocation With Correlated Measurements, Joshua S. Sprang Mar 2015

Non-Linear Optimization Applied To Angle-Of-Arrival Satellite-Based Geolocation With Correlated Measurements, Joshua S. Sprang

Theses and Dissertations

A common remote sensing application is producing geolocation estimates for an object of interest from multiple sensor platforms. Geolocation estimates are desired to help improve situational awareness when dealing with space objects that do not actively broadcast their location. A depiction of the error parameters are calculated in conjunction with the positional estimates. Problems occur when multiple measurements from a single sensor are used to estimate a location due to correlations in sensor error. A non-linear optimization approach is presented for determining geolocation estimates and their associated error parameters. The error parameters directly reflect the error present on the individual …

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On The Integration Of Medium Wave Infrared Cameras For Vision-Based Navigation, Justin S. Tharp Mar 2015

On The Integration Of Medium Wave Infrared Cameras For Vision-Based Navigation, Justin S. Tharp

Theses and Dissertations

The ubiquitous nature of GPS has fostered its widespread integration of navigation into a variety of applications, both civilian and military. One alternative to ensure continued flight operations in GPS-denied environments is vision-aided navigation, an approach that combines visual cues from a camera with an inertial measurement unit (IMU) to estimate the navigation states of a moving body. The majority of vision-based navigation research has been conducted in the electro-optical (EO) spectrum, which experiences limited operation in certain environments. The aim of this work is to explore how such approaches extend to infrared imaging sensors. In particular, it examines the …

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Surface Geometry And Chemistry Of Hydrothermally Synthesized Single Crystal Thorium Dioxide, Scott W. Key Mar 2015

Surface Geometry And Chemistry Of Hydrothermally Synthesized Single Crystal Thorium Dioxide, Scott W. Key

Theses and Dissertations

The surface chemistry and geometry of hydrothermally grown, single crystal ThO2 was studied using X-ray Photoemission Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The crystal was studied before and after sputter etching with Ar+, heating up to 675 K, and dehydration with dry nitrogen. The hydrothermal growth technique incorporated Cs and F into the near surface bulk. Heating to 675 K drove off the F, but did not the Cs. Sputtering with Ar+ at 75° cleaned the crystal and created a more uniform surface geometry. The Th 4f peak resolution, as measured by XPS improved by …

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The Effect Of Anisotropic Scatter On Atmospheric Neutron Transport, Nicholas J. Mcintee Mar 2015

The Effect Of Anisotropic Scatter On Atmospheric Neutron Transport, Nicholas J. Mcintee

Theses and Dissertations

Anisotropy is present in the angular distributions of neutrons departing from a nuclear scattering event. This anisotropy cannot be defined in a closed-form solution, and it is dependent on the incident neutron energy, elastic or inelastic scatter, along with the inelastic level, and the species struck. The underlying question is, if anisotropic behavior is worth the computational cost to be included in certain simulations, and if so, what level of precision is effected by the inclusion of anisotropic scatter. A Watt spectrum of U235 fission neutrons was examined as it collided with species in a nitrogen-oxygen atmosphere. In a …

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Overcoming Hurdles Implementing Multi-Skilling Policies, Joshua M. Isom Mar 2015

Overcoming Hurdles Implementing Multi-Skilling Policies, Joshua M. Isom

Theses and Dissertations

Ogden ALC at Hill AFB has been authorized to promote wage grade employees if they are multi-skilled, but that authorization will expire at the end of Fiscal Year 2018. Simulation research by Capt Wesley Sheppard demonstrated significant cost savings/cost avoidance if multi-skilling is pursued, but there are significant challenges to implementation. This research examined two challenges in implementation. First, how many employees can be multi-skilled and still maintain proficiency in both skills? Second, once multi-skilled, is there a technique that can be applied to easily and effectively schedule the new multi-skilled workforce. Using linear programming, staffing numbers were calculated based …

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A Risk Based Approach To Node Insertion Within Social Networks, Chancellor A. J. Johnstone Mar 2015

A Risk Based Approach To Node Insertion Within Social Networks, Chancellor A. J. Johnstone

Theses and Dissertations

Social Network Analysis (SNA) is a primary tool for counter-terrorism operations, ranging from resiliency and influence to interdiction on threats stemming from illicit overt and clandestine network operations. In an ideal world, SNA would provide a perfect course of action to eliminate dangerous situations that terrorist organizations bring. Unfortunately, the covert nature of terrorist networks makes the effects of these techniques unknown and possibly detrimental. To avoid potentially harmful changes to enemy networks, tactical involvement must evolve, beginning with the intelligent use of network in filtration through the application of the node insertion problem. The framework for the node insertion …

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Value Focused Thinking Applications To Supervised Pattern Classification With Extensions To Hyperspectral Anomaly Detection Algorithms, David S. Scanland Mar 2015

Value Focused Thinking Applications To Supervised Pattern Classification With Extensions To Hyperspectral Anomaly Detection Algorithms, David S. Scanland

Theses and Dissertations

Hyperspectral imaging (HSI) is an emerging analytical tool with flexible applications in different target detection and classification environments, including Military Intelligence, environmental conservation, etc. Algorithms are being developed at a rapid rate, solving various related detection problems under certain assumptions. At the core of these algorithms is the concept of supervised pattern classification, which trains an algorithm to data with enough generalizability that it can be applied to multiple instances of data. It is necessary to develop a logical methodology that can weigh responses and provide an output value that can help determine an optimum algorithm. This research focuses on …

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The Cognition Of Multiaircraft Control (Mac): Cognitive Ability Predictors, Working Memory, Interference, And Attention Control In Radio Communication, Kelly M. Amaddio Mar 2015

The Cognition Of Multiaircraft Control (Mac): Cognitive Ability Predictors, Working Memory, Interference, And Attention Control In Radio Communication, Kelly M. Amaddio

Theses and Dissertations

As the number of U.S. Air Force missions requiring UAVs has rapidly increased without commensurate increases in manpower, systems which permit a single operator to supervise and control multiple, highly-automated aircraft are being considered. The operator of such a system may be required to monitor and respond to voice communications for multiple UAVs, each of which can have aircraft specific call signs. The need to monitor this array of call signs may impose excessive requirements on constrained operator attention, working memory, and cognitive processing. The current research investigates the cognitive load (number of aircraft call signs) an individual can handle …

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Functionality, Complexity, And Approaches To Assessment Of Resilience Under Constrained Energy And Information, Jason B. Clark Mar 2015

Functionality, Complexity, And Approaches To Assessment Of Resilience Under Constrained Energy And Information, Jason B. Clark

Theses and Dissertations

While system functions, functionality, and complexity are widely used concepts in systems engineering, there is significant diversity in their definitions and no unified approach to measurement. This research establishes a method for measuring impacts to functionality in dynamic engineered systems based on changes in kinetic energy. This metric is applied at particular levels of abstraction and system scales, consistent with the established multiscale nature of systems. By measuring system behavior in context with expected scenarios, it is possible to estimate expected functionality or set bounds on a system's maximum functionality. Functionality and system effectiveness is heavily influenced by the amount …

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Using Earned Value Data To Forecast The Duration Of Department Of Defense (Dod) Space Acquisition Programs, Shedrick M. Bridgeforth Mar 2015

Using Earned Value Data To Forecast The Duration Of Department Of Defense (Dod) Space Acquisition Programs, Shedrick M. Bridgeforth

Theses and Dissertations

The accuracy of cost estimates is vital during this era of budget constraints. A key component of this accuracy is regularly updating the cost estimate at completion (EAC). A 2014 study by the Air Force Cost Analysis Agency (AFCAA) improved the accuracy of the cost estimate at completion (EAC) for space system contracts. The study found schedule duration to be a cost driver, but assumed the underlying duration estimate was accurate. This research attempts to improve the accuracy of the duration estimate from the AFCAA study; accuracy is evaluated with the Mean Absolute Percent Error (MAPE). The methods researched here …

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Modeling, Simulation, And Analysis Of A Decoy State Enabled Quantum Key Distribution System, Ryan D. Engle Mar 2015

Modeling, Simulation, And Analysis Of A Decoy State Enabled Quantum Key Distribution System, Ryan D. Engle

Theses and Dissertations

Quantum Key Distribution (QKD) is an emerging technology which uses the principles of quantum mechanics to provide unconditionally secure key distribution. QKD systems are unique in their ability to detect an eavesdropper's presence and are being marketed for applications where high levels of secrecy are required such as banking, government, and military environments. QKD systems are composed of electrical, optical, and electrooptical components. Their design requires expertise across multiple disciplines including computer science, computer engineering, electrical engineering, information theory, optical physics, and quantum physics. This multidisciplinary nature makes QKD an ideal candidate for study using Model Based Systems Engineering (MBSE) …

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Integrating Pavement Crack Detection And Analysis Using Autonomous Unmanned Aerial Vehicle Imagery, Patrick J. Grandsaert Mar 2015

Integrating Pavement Crack Detection And Analysis Using Autonomous Unmanned Aerial Vehicle Imagery, Patrick J. Grandsaert

Theses and Dissertations

Efficient, reliable data is necessary to make informed decisions on how to best manage aging road assets. This research explores a new method to automate the collection, processing, and analysis of transportation networks using Unmanned Aerial Vehicles and Computer Vision technology. While there are current methodologies to accomplish road assessment manually and semi-autonomously, this research is a proof of concept to obtain the road assessment faster and cheaper with a vision for little to no human interaction required. This research evaluates the strengths of applying UAV technology to pavement assessments and identifies where further work is needed. Furthermore, it validates …

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Analysis Of Air Force Wartime Contracted Construction Project Performance, Ryan M. Hoff Mar 2015

Analysis Of Air Force Wartime Contracted Construction Project Performance, Ryan M. Hoff

Theses and Dissertations

Using a dataset of 25 Afghan wartime projects, two questions were investigated: 1) What factors affect the success of construction projects; and 2) How do project outcomes differ based on the contract type? Current literature suggests that wartime projects may face the same cost and schedule factors as peacetime projects, with some notable additions. Project factors, health and safety compliance, quality of work, technical performance, work productivity, and external environmental factors were tested with contingency tables to determine dependency with schedule or cost performance. External environmental factors, including weather and wartime security, were not predictive of project performance. However, cost …

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