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Articles 6541 - 6570 of 11510
Full-Text Articles in Engineering
Modeling The Impact Of The Payload Alert Communications System (Pacs) On The Accuracy Of Conjunction Analysis, Landon B. Bastow
Modeling The Impact Of The Payload Alert Communications System (Pacs) On The Accuracy Of Conjunction Analysis, Landon B. Bastow
Theses and Dissertations
The Air Force Institute of Technology (AFIT) and the Air Force Research Laboratory (AFRL) are jointly developing a system known as the Payload Alert Communications System (PACS) whose purpose is to decrease the statistical uncertainty in the location of resident space objects (RSOs). PACS is designed to augment the Joint Space Operations Center's (JSpOC) existing space object tracking capabilities which is expected to increase the accuracy of conjunction estimation. In the current PACS design, a small payload would be attached to certain RSOs prior their launch. It is envisioned that this payload would basically consist of a microcontroller, a Global …
An Analysis Of Cost Premiums And Losses Associated With Usaf Military Construction (Milcon), Daniel L. Blomberg
An Analysis Of Cost Premiums And Losses Associated With Usaf Military Construction (Milcon), Daniel L. Blomberg
Theses and Dissertations
Military construction (MILCON) represents 40% of the federal government's $30 billion construction budget. The federal budget is fixed; therefore, any cost overages likely affect project scope or requirements. This study investigated if MILCON procurement costs more than private industry construction and if so, what causes the cost premiums. A combination of in-depth literature review, expert interviews, a unique case study, expert surveys, and geospatial statistical analysis answered the research question. The case study evaluated two nearly identical projects to determine how internal factors affect MILCON cost premiums. This study confirmed the existence of MILCON cost premiums. Additionally, 11 major cost …
Successfully Implementing Net-Zero Engergy Policy Through The Air Force Military Construction Program, D. Gavin Brost
Successfully Implementing Net-Zero Engergy Policy Through The Air Force Military Construction Program, D. Gavin Brost
Theses and Dissertations
The U.S. Government has issued numerous policies aimed at reducing federal facility energy consumption; the most recent, Executive Order 13514, requires that new construction designed after 2020 can achieve net-zero energy by 2030. The policy defines a Zero-Energy Building as one that is designed, constructed, and operated to reduce energy demand to a level which can be offset from sources of renewable energy. This research develops and evaluates a feasibility assessment model based on life-cycle cost. It incorporates geospatial analysis to calculate and summarize input values for all Air Force installations in the Contiguous U.S. A comparative analysis is then …
Investigation Into Risk And Uncertainty: Identifying Coefficient Of Variation Benchmarks For Air Force Acat I Programs, Shaun T. Carney
Investigation Into Risk And Uncertainty: Identifying Coefficient Of Variation Benchmarks For Air Force Acat I Programs, Shaun T. Carney
Theses and Dissertations
Previous DoD cost growth studies found typical cost growth in defense acquisitions is around forty-six to sixty percent of the original estimate. The research in this study addresses the identification of risk and uncertainty benchmarks by providing decision makers with coefficient of variation ranges for cost estimates. The study recommends coefficient of variation (CV) ranges for Air Force Acquisition programs, determines if different CV ranges should be used based on platform type, and determines if CV decreases over the course of the program's acquisition lifecycle. The analysis found that the Air Force should enhance the CV review process to ensure …
An Analysis Of Factors That Influence The Success Of Expeditionary Civil Engineer Hub-And-Spoke Organizations, Joshua A . Hager
An Analysis Of Factors That Influence The Success Of Expeditionary Civil Engineer Hub-And-Spoke Organizations, Joshua A . Hager
Theses and Dissertations
Expeditionary Air Force Civil Engineer support to recent operations in southwest Asia created a unique organizational learning environment, particularly related supporting the general engineering requirements of geographically separated units in a manpower-constrained contingency environment. One of the direct results of this organizational learning was the hub-and-spoke expeditionary engineer unit featuring elements of both RED HORSE and Prime BEEF capabilities operating with theater-wide visibility of infrastructure requirements. This study acquired insights from literature and a purposeful sample of subject matter experts about operational advantages this hub-and-spoke unit offered compared to those offered by strictly legacy organizational models. The research used a …
The Future Of Mobile Information And Communication Technology In Austere Environments: A Command And Control Technology Integration Perspective, James W. Harker
The Future Of Mobile Information And Communication Technology In Austere Environments: A Command And Control Technology Integration Perspective, James W. Harker
Theses and Dissertations
The information and communications technology (ICT) field is undergoing a period of tremendous and rapid change. As ICT develops more rapidly, the United States Air Force needs to remain responsive and adaptive to maintain military advantages. The need to integrate ICT developments sooner than our adversaries prompted an assessment of guidelines evaluating how well the AF is doctrinally positioned from a Command and Control perspective to support integration of emerging ICT. A Delphi Study was commissioned by the 689th CCW to forecast the future of mobile Information and Communication Technology (ICT) in austere environments. Using the ICT forecast data as …
The Moderating Effect Of Network Centrality On The Relationship Between Work Experience Variables And Organizational Commitment, Luke M. Kaspari
The Moderating Effect Of Network Centrality On The Relationship Between Work Experience Variables And Organizational Commitment, Luke M. Kaspari
Theses and Dissertations
The purpose of this research was to identify the effect of an individual's network position on the relationship between work experience variables and affective commitment. This study tested three hypotheses, which were introduced through a comprehensive literature review, regarding the relationships between work experience variables and affective commitment. Research has indicated linkages between social network centrality and organizational commitment; however, the specific effects of centrality remain unclear. Therefore, this research developed and tested a moderation model to identify relationships between network centrality, affective commitment, and three work experience variables: psychological empowerment (PE), leader-member exchange (LMX), and perceived organizational support (POS). …
An Evaluation Of The Organizational Structure Of Air Force Emergency Operations Centers Using Social Network Analysis And Design Structure Matrices, John W. Marshall
An Evaluation Of The Organizational Structure Of Air Force Emergency Operations Centers Using Social Network Analysis And Design Structure Matrices, John W. Marshall
Theses and Dissertations
The terrorist attacks on September 11, 2001 demonstrated that the United States' emergency response capability, while robust, was disorganized in that organizations were not prepared or equipped to coordinate response actions across multiple agencies at a national level. This research investigates whether NIMS and the AFIMS structure is optimal for Air Force emergency managers, or whether, while maintaining NIMS compliance, there is a more effective way for the Air Force to organize its emergency management and response forces. Specifically this research focuses on the organization of the EOC and investigates whether shifting from the current structure of the ESFs to …
Influence Of Media Size And Flow Rate On The Transport Of Silver Nanoparticles In Saturated Porous Media: Laboratory Experiments And Modeling, Travis J. Meidinger
Influence Of Media Size And Flow Rate On The Transport Of Silver Nanoparticles In Saturated Porous Media: Laboratory Experiments And Modeling, Travis J. Meidinger
Theses and Dissertations
Silver nanoparticles (AgNPs) are widely produced and used. Because of their potential toxicity and the possibility of their release into the environment, it is important to understand the factors involved in their transport; particularly how they may move in groundwater, which is a potential pathway to human and environmental receptors. By passing a solution of 15 mg/L AgNPs with an average size of 17 nm through sand-filled glass columns, this study looks at the physical effects of flow rate and media size on transport. Three different sand sizes ( 0.074, 0.21-0.297, and 0.4-2.0mm) were used, as well as two different …
Using Geographic Information Systems To Evaluate Energy Initiatives In Austere Environments, D. Jason Murley
Using Geographic Information Systems To Evaluate Energy Initiatives In Austere Environments, D. Jason Murley
Theses and Dissertations
Organizations that operate in austere environments at the end of long logistics chains face significant energy challenges which often represent financial and security vulnerabilities. Reducing fuel consumption in these operations causes a proportional fuel reduction throughout the supply system as the need for transportation of fuel is reduced. Accordingly, the total fuel reduction across the supply system should be considered to capture the fully burdened cost savings when conducting economic analysis of energy reduction initiatives. This research examined the energy savings potential of improving the thermal properties of expeditionary shelters, and then evaluated these measures using a fully burdened cost …
Identifying System Patterns To Resolve Challenges In The Test And Evaluation Operation, Daniel K. Mutunga
Identifying System Patterns To Resolve Challenges In The Test And Evaluation Operation, Daniel K. Mutunga
Theses and Dissertations
This research focuses on identification and description of patterns used in Test and Evaluation (T&E) operations. Patterns are defined as named and well-known problem/solution pairs that can be applied in new contexts, with advice on how to apply it in a novel situations and discussion of its trade-offs, implementations, and variations. They have a well established and used in software engineering, but have only recently been considered for systems engineering. In the Department of Defense (DOD), T&E is required for all acquisitions prior to transitioning into operations. As identified and described in this thesis, each of the patterns fits in …
Using Value-Focused Thinking As An Alternative Means Of Opportunity Assessment For Strategic Sourcing Applications, Andrew R. Myers
Using Value-Focused Thinking As An Alternative Means Of Opportunity Assessment For Strategic Sourcing Applications, Andrew R. Myers
Theses and Dissertations
In recent years, the Federal Government has attempted to utilize strategic sourcing to reduce acquisitions expenses. Currently accepted best practices for strategic sourcing developed in the private sector fail to account for the diverse and unique set of objectives present in public sector acquisitions. Value Focused Thinking was used to develop a hierarchy of values and objectives for the Air Force Civil Engineer Commodity Council (CECC) strategic sourcing program. This hierarchy represents the full range of program objectives, and was used to develop a value function useful for systematically evaluating service and commodity contract areas for strategic sourcing potential.
Case Study Analysis Of Trust And Commitment Between The Civil Engineering Commodity Council And The Civil Engineering Career Field, Jonnathan B. Page
Case Study Analysis Of Trust And Commitment Between The Civil Engineering Commodity Council And The Civil Engineering Career Field, Jonnathan B. Page
Theses and Dissertations
The Air Force is pursuing strategic sourcing as a strategy for reducing costs of goods and services to help meet budget reductions while still performing its mission. These commodities are sourced through a number of commodity councils, each of which whom interact with their stakeholders throughout the sourcing process for that specific commodity. This research identifies factors that influence the success or failure of the sourcing process from the perspective of the Civil Engineering Commodity Council (CECC) and attempts to organize these factors within a framework built around trust and its effect on commitment and cooperation. These factors were identified …
The Use Of Multi-Criteria Evaluation And Network Analysis In The Area Development Planning Process, Peeter E. Pleake-Tamm
The Use Of Multi-Criteria Evaluation And Network Analysis In The Area Development Planning Process, Peeter E. Pleake-Tamm
Theses and Dissertations
The purpose of this research was to develop improvements to the area development planning process. These plans are used to improve operations within an installation sub-section by altering the physical layout of facilities. One methodology was developed based on apply network analysis concepts to the generation of alternative facility layouts. A second methodology was developed using multi-criteria evaluation to the selection of evaluated alternative facility layouts. The results of this study are two methodological processes that can be executed at base level requiring minimal additional information. The functional network map, based in network analysis, increases the use of socio-economic data …
Supplementary Computer Generated Cueing To Enhance Air Traffic Controller Efficiency, Laurienne Cibelle Rodrigues De Assis Santana
Supplementary Computer Generated Cueing To Enhance Air Traffic Controller Efficiency, Laurienne Cibelle Rodrigues De Assis Santana
Theses and Dissertations
Air traffic controllers are often required to simultaneously communicate with several aircraft over multiple radio frequencies. As a result, during peak loading, it is common for the controller to receive multiple concurrent communications, each from a different aircraft, making it difficult to discern audio messages received from multiple pilots simultaneously. To address this problem, a modified air traffic control (ATC) interface was prototyped with the goal of increasing controller-to-pilot communication efficiency. This prototype included supplementary text cueing which was provided by a hypothetical automated text to speech system in an on-screen text box for controller reference in the event of …
Development Of Autonomous Optimal Cooperative Control In Relay Rover Configured Small Unmanned Aerial Systems, Timothy J. Shuck
Development Of Autonomous Optimal Cooperative Control In Relay Rover Configured Small Unmanned Aerial Systems, Timothy J. Shuck
Theses and Dissertations
This thesis documents the research effort to develop, integrate and implement the system hardware and the software necessary to validate the Air Force Institute of Technology's theoretical advances in small unmanned aerial systems (SUAS) cooperative control. The end state objective of the research effort was to flight test an autonomous control algorithm on a communication relay unmanned aerial vehicle (UAV) that was actively relaying data to and from a rover UAV. The relay UAV is one part of a SUAS designed to utilize cooperative control to extend the effective line-of-sight operating range for a rover UAV. An algorithm is integrated …
Needed Actions Within Defense Acquisitions Based On A Forecast Of Future Mobile Information And Communications Technologies Deployed In Austere Environments, Andrew T. Soine
Theses and Dissertations
The purpose of this research was twofold. First, it developed a forecast of future mobile information and communications technologies (ICT) suitable for use by military forces in austere environments in 5-10, 10-20, and beyond 20 years. Secondly, it explored whether or not current acquisitions practices will be adequate to meet the needs of warfighters who depend on mobile ICT. These questions were explored by conducting utilization of the Delphi technique. Eight panelists from within the private sector conducted three rounds of iterative feedback. This research resulted in a technology forecast for the three timeframes aforementioned, and the potential impacts to …
Evaluating The Effect Of Integrated System Health Management On Mission Effectiveness, Sarah E. Storm
Evaluating The Effect Of Integrated System Health Management On Mission Effectiveness, Sarah E. Storm
Theses and Dissertations
This research used systems architecture to develop a model that determined the effect of Integrated System Health Management (ISHM) on mission success rates for unmanned aerial systems (UAS). To evaluate this effect, a simulation model was developed and used to analyze the difference between mission success rates for a theoretical UAS with and without ISHM. Design of Experiments analysis techniques were used to map a response surface that modeled the difference between mission success rates calculated for current health management technology and ISHM. Using representative data for a UAS, the analysis determined that the failure distribution parameters, sensor quality (which …
An Investigation And Analysis Of The Vestibulo-Ocular Reflex In A Vibration Environment, Daniel J. Uribe
An Investigation And Analysis Of The Vestibulo-Ocular Reflex In A Vibration Environment, Daniel J. Uribe
Theses and Dissertations
Forty years of innovations have greatly improved Helmet-Mounted Displays (HMDs) and their integration into military systems. However, a significant issue with HMDs is the effect of vibration and the associated Vestibulo-Ocular Reflex (VOR). When a human’s head is subject to low-frequency vibration, the VOR stabilizes the eye with respect to objects in the external environment. However, this response is inappropriate in HMDs as the display moves with the user’s head and the VOR blurs the image as it is projected on the human retina. Current compensation techniques suggest increasing the size of displayed graphics or text to compensate for the …
Calibration And Extension Of A Discrete Event Operations Simulation Modeling Multiple Un-Manned Aerial Vehicles Controlled By A Single Operator, Jonathan W. Welborn
Calibration And Extension Of A Discrete Event Operations Simulation Modeling Multiple Un-Manned Aerial Vehicles Controlled By A Single Operator, Jonathan W. Welborn
Theses and Dissertations
This research improved a simulation that models a single operator responsible for multiple UAV rovers. The improvement calibrated the model by increasing the realism of its expected time that the target will be within the field of view of a UAV's camera and how much of that will be observed by an operator that has multiple tasks to perform throughout the mission. The calibration was derived from multiple flight tests, by using a Field of View Algorithm in MATLAB and by visually recording times for loiter loops by hand. It was determined that the target will be within the field …
Heat Exchanger Design And Testing For A 6-Inch Rotating Detonation Engine, Scott W. Theuerkauf
Heat Exchanger Design And Testing For A 6-Inch Rotating Detonation Engine, Scott W. Theuerkauf
Theses and Dissertations
This thesis explains the design and testing of a water-cooled rotating detonation engine (RDE) run on hydrogen and air. The change in water temperature as it cooled the engine was used to find the steady heat rate into the containing walls of the detonation channel. The engine successfully ran four times for 20 seconds each. The steady-state heat rate was measured to be 2.5% of the propellant lower heating value (LHV) into the outer wall and 7.1% of LHV into the inner wall. Additionally, a quick-response resistance temperature detector (RTD) was used in an uncooled RDE of similar dimension to …
Real-Time Heading Estimation Using Perspective Features, James W. Dean
Real-Time Heading Estimation Using Perspective Features, James W. Dean
Theses and Dissertations
There are a large number of commercially available quad-rotor helicopters available from various manufacturers. All of these systems rely on a low cost MEMS based inertial measurement system for stabilization and navigation. These low cost inertial systems are all subject to rapid error growth in their attitude and position estimates unless bounded by external measurements. This thesis created real-time algorithm to integrate measurements from visual cues with measurements from onboard sensors to estimate the attitude position and velocity of a quad-rotor helicopter in a local navigation frame, a system model for the ARDrone, and a feed-back controller for the vehicle's …
Aerial Networking For The Implementation Of Cooperative Control On Small Unmanned Aerial Systems, Scott A . Songer
Aerial Networking For The Implementation Of Cooperative Control On Small Unmanned Aerial Systems, Scott A . Songer
Theses and Dissertations
The employment of Small Unmanned Aerial Systems (SUAS) for reconnaissance and surveillance missions is a vital capability of the United States military. Cooperative control algorithms for SUAS can enable tactical multi-vehicle configurations for communications extension, intelligent navigation, and a multitude of other applications. Past research at AFIT has designed and simulated a cooperative rover-relay algorithm for extended communications and has investigated its implementation through various modem configurations. This research explores aerial networking options for implementing cooperative control and applies them to an actual SUAS. Using Commercial Off-The-Shelf (COTS) hardware, a system was designed and flight tested to implement the rover-relay …
Power Requirements For Bi-Harmonic Amplitude And Bias Modulation Control Of A Flapping Wing Micro Air Vehicle, Justin R. Carl
Power Requirements For Bi-Harmonic Amplitude And Bias Modulation Control Of A Flapping Wing Micro Air Vehicle, Justin R. Carl
Theses and Dissertations
Flapping wing micro air vehicles (FWMAV) have been a growing field in the research of micro air vehicles, but little emphasis has been placed on control theory. Research is ongoing on how to power FWMAVs where mass is a major area of concern. However, there is little research on the power requirements for the controllers to manipulate the wings of a FWMAV. A novel control theory, BABM, allows two actuators to produce forces and moments in five of the FWMAV's six DOF. Several FWMAV prototypes were constructed and tested on a six-component balance. Data was collected for varying control parameters …
Integration Of An Inter Turbine Burner To A Jet Turbine Engine, Matthew M. Conrad
Integration Of An Inter Turbine Burner To A Jet Turbine Engine, Matthew M. Conrad
Theses and Dissertations
As aircraft power requirements continue to grow, whether for electrical systems or increased thrust, improved engine efficiency must be found. An Ultra-Compact Combustor (UCC) is a proposed apparatus for accomplishing this task by burning in the circumferential direction as a main combustor or an Inter-Turbine Burner (ITB). In order for the UCC to be viable it is important to study the effects of feeding the core and circumferential flows from a common gas reservoir. This research effort has developed a diffuser, for the AFIT Combustion Laboratory, that is capable of 80/20, 70/30, and 60/40 mass flow splits between the core …
Opto-Mechanical Design Of A Chromotomographic Imager Direct-Vision Prism Element, Timothy E. Coon
Opto-Mechanical Design Of A Chromotomographic Imager Direct-Vision Prism Element, Timothy E. Coon
Theses and Dissertations
Chromotomographic Imaging (CTI) offers advantages in remote sensing by resolving intensity distribution spatially, spectrally, and temporally. The Chromotomography Experiment (CTEx) at the Air Force Institute of Technology (AFIT) explores the application of CTI as a space-based observer. Previous work in instrument development has revealed many of the intricacies of component fabrication and how they impact the resolving of image data. The proposed CTEx instrument has as its chromatic dispersion element a direct-vision prism (DVP) that is made to rotate in order to achieve multiple projection angles. Analysis of previous research established the need for a more accurate characterization of the …
Using Hysteretic Energy To Evaluate Damping Characteristics Of Hard Coating On Titanium, Colin C. Engebretsen
Using Hysteretic Energy To Evaluate Damping Characteristics Of Hard Coating On Titanium, Colin C. Engebretsen
Theses and Dissertations
Current methods of material damping evaluation consist of bending tests involving half-power bandwidth base excitation or free decay methods measured by laser vibrometer. These methods are accompanied by complex, nonlinear strain evaluation; they are vulnerable to undesired air damping; and they require less than commonplace equipment. The measurement of hysteretic energy loss in axial cyclic loading alleviates these difficulties. By using common tensile testing machines, strain is kept linear and air damping is of no concern. Furthermore, the static test section allows for simplified environmental variation for high temperature or high humidity testing. This study set forth to advance and …
Dynamic Constellation Tasking And Management, Steven P. Ingraham
Dynamic Constellation Tasking And Management, Steven P. Ingraham
Theses and Dissertations
Responsive orbits have gained much attention in recent years and many AFIT theses have addressed this topic. Specifically, the following topics have been studied: phasing within an orbit, adjusting time of arrival, avoidance, and maneuver detection. This thesis seeks to determine the feasibility of maneuvering satellites from circular (600 km) orbits to eccentric (600 km by 175 km) orbits in order to collect high resolution images for Earth surveillance. Coverage is calculated for multiple 6-satellite constellations. Perturbations for the subject orbits are analyzed and compared to simulation results.
Design Of A Control Moment Gyroscope Attitude Actuation System For The Attitude Control Subsystem Proving Ground, Samuel C. Johnson
Design Of A Control Moment Gyroscope Attitude Actuation System For The Attitude Control Subsystem Proving Ground, Samuel C. Johnson
Theses and Dissertations
All spacecraft represent a considerable investment of both time and money. To ensure mission success, testing and validation of all vital systems is crucial to the design process. The attitude control subsystem (ACS) is typically tested thoroughly, to include both hardware and control algorithms. Computer simulations offer a simple and relatively cheap method of predicting the performance of the ACS; however, computer simulations cannot provide the assurances necessary to qualify an ACS hardware configuration or control algorithm spaceworthy. For this reason, physical spacecraft simulators must be used to validate ACS dynamics. Previous research showed there is room for significant improvement …
Experimental Analysis Of Dampened Breathing Mode Oscillation On Hall Effect Thruster Performance, Christopher D. Vineski
Experimental Analysis Of Dampened Breathing Mode Oscillation On Hall Effect Thruster Performance, Christopher D. Vineski
Theses and Dissertations
Experiments were performed at AFIT to determine the effect of active control of the magnetic field strength to reduce the breathing mode oscillation on the efficiency of a 200W Hall thruster. The breathing mode oscillation amplitude was measured by the root mean square (RMS) variation in the AC portion of the discharge current. Experiments were run using krypton and xenon propellant. Using the xenon propellant control of the RMS improved the propellant utilization efficiency by approximately 2% in two cases, while reducing the magnet current efficiency by about 10%. Control of the RMS's effect on the divergence angle of the …