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Air Force Institute of Technology

2016

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Articles 1 - 30 of 193

Full-Text Articles in Engineering

Generation Of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators, Milo W. Hyde Iv, Santasri Bose-Pillai, David G. Voelz, Xifeng Xiao Dec 2016

Generation Of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators, Milo W. Hyde Iv, Santasri Bose-Pillai, David G. Voelz, Xifeng Xiao

Faculty Publications

A simple and flexible optical system for generating electromagnetic or vector partially coherent sources or beams is presented. The alternative design controls field amplitude (beam shape), coherence, and polarization using only spatial light modulators. This improvement makes the apparatus simpler to construct and significantly increases the flexibility of vector partially coherent source generators by allowing many different types of sources to be produced without changing the physical setup. The system’s layout and theoretical foundations are thoroughly discussed. The utility and flexibility of the proposed system are demonstrated by producing a vector Schell-model and non-Schell-model source. The experimental results are compared …

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Improvements To Micro-Contact Performance And Reliability, Tod V. Laurvick Dec 2016

Improvements To Micro-Contact Performance And Reliability, Tod V. Laurvick

Theses and Dissertations

Microelectromechanical Systems (MEMS) based devices, and specifically microswitches, continue to offer many advantages over competing technologies. To realize the benefits of micro-switches, improvements must be made to address performance and reliability shortfalls which have long been an issue with this application. To improve the performance of these devices, the micro-contacts used in this technology must be understood to allow for design improvements, and offer a means for testing to validate this technology and determine when such improvements are ready for operational environments. To build devices which are more robust and capable of continued operation after billions of cycles requires that …

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Integrated Circuit Wear-Out Prediction And Recycling Detection Using Radio-Frequency Distinct Native Attribute Features, Randall D. Deppensmith Dec 2016

Integrated Circuit Wear-Out Prediction And Recycling Detection Using Radio-Frequency Distinct Native Attribute Features, Randall D. Deppensmith

Theses and Dissertations

Radio Frequency Distinct Native Attribute (RF-DNA) has shown promise for detecting differences in Integrated Circuits(IC) using features extracted from a devices Unintentional Radio Emissions (URE). This ability of RF-DNA relies upon process variation imparted to a semiconductor device during manufacturing. However, internal components in modern ICs electronically age and wear out over their operational lifetime. RF-DNA techniques are adopted from prior work and applied to MSP430 URE to address the following research goals: 1) Does device wear-out impact RF-DNA device discriminability?, 2) Can device age be continuously estimated by monitoring changes in RF-DNA features?, and 3) Can device age state …

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Spacex: Breaking The Barrier To The Space Launch Vehicle Industry, Matthew M. Liskowcyz Dec 2016

Spacex: Breaking The Barrier To The Space Launch Vehicle Industry, Matthew M. Liskowcyz

Theses and Dissertations

The Space Launch Vehicle (SLV) industry has been around for a long time, but few companies have managed to enter this industry. SpaceX was founded only 10 years ago, but it has managed to become a leader in the U.S. industry and a dominant player worldwide. The purpose of this thesis research is to discover what it took for SpaceX to break into this tightly controlled industry. A qualitative analysis was performed to compare SpaceX to companies that overcame the barriers of entry for their respective industries. SpaceX, like FedEx, could implement a unique technique to the industry and find …

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Flow Field Dynamics In A High-G Ultra-Compact Combustor, Andrew E. Cottle Dec 2016

Flow Field Dynamics In A High-G Ultra-Compact Combustor, Andrew E. Cottle

Theses and Dissertations

The Ultra Compact Combustor (UCC) presents a novel solution to the advancement of aircraft gas turbine engine performance. A high-g UCC design operates by diverting a portion of the axial compressor flow into a circumferential combustion cavity positioned about the engine outer diameter. The circumferential cavity (CC) provides the necessary residence length and time for combustion within reduced axial lengths; furthermore, high rates of centrifugal acceleration termed high-g loading are imposed upon the swirling cavity flow. These high-g conditions are hypothesized to increase flame speed, reduce flame length, and improve lean blow-out performance. Work at AFIT was sponsored by the …

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Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2P2S6 Crystals, Brant E. Kananen, Eric M. Golden, Sergey A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton Dec 2016

Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2P2S6 Crystals, Brant E. Kananen, Eric M. Golden, Sergey A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Doping photorefractive single crystals of Sn2P2S6 with antimony introduces both electron and hole traps. In as-grown crystals, Sb3+ (5s2) ions replace Sn2+ ions. These Sb3+ ions are either isolated (with no nearby perturbing defects) or they have a charge-compensating Sn2+ vacancy at a nearest-neighbor Sn site. When illuminated with 633 nm laser light, isolated Sb3+ ions trap electrons and become Sb2+ (5s25p1) ions. In contrast, Sb3+ ions with an adjacent Sn vacancy trap holes during illumination. The hole is primarily …

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Simulation Of Aircraft Sortie Generation Under An Autonomic Logistics System, Gunduz Bingol Dec 2016

Simulation Of Aircraft Sortie Generation Under An Autonomic Logistics System, Gunduz Bingol

Theses and Dissertations

Parallel to the developments in diagnostic and prognostic technology, autonomic logistics systems (ALS) have been a potential improvement for the aircraft sortie generation process. Currently, Lockheed Martin and the Joint Program Office are developing a new autonomic logistics system for the multibillion F-35 Lightning Joint Strike Fighter project, which is named the Autonomic Logistics Information System (ALIS). Generally, researchers make an analogy between the ALS and the human bodys autonomic nervous system since both of them monitor, control, and adjust autonomic responses to external stimuli. Based on this perspective, ALS aims to switch the Air Force logistics mentality from a …

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Benchmarking Approach For Empirical Comparison Of Pricing Models In Drms, Seif Azghandi, Kenneth M. Hopkinson, Kennard R. Laviers Nov 2016

Benchmarking Approach For Empirical Comparison Of Pricing Models In Drms, Seif Azghandi, Kenneth M. Hopkinson, Kennard R. Laviers

Faculty Publications

emand response management systems often involve the use of pricing schemes to motivate the efficient use of electrical power. Achieving this efficiency requires the detection of electrical power patterns. The detection of these patterns normally involves use of non-linear, quasi-non-linear, and at times linear data pattern detection models. The behavioural disparities of these models and specifically when used for a specific set of data make it hard to select the most efficient model. The contribution of this study is devising an empirical benchmark (reference) ( perfect ) control pricing (PCP) model through which various models are compared in order to …

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Methodology For Simulation And Analysis Of Complex Adaptive Supply Network Structure And Dynamics Using Information Theory, Joshua V. Rodewald, John M. Colombi, Kyle F. Oyama, Alan W. Johnson Oct 2016

Methodology For Simulation And Analysis Of Complex Adaptive Supply Network Structure And Dynamics Using Information Theory, Joshua V. Rodewald, John M. Colombi, Kyle F. Oyama, Alan W. Johnson

Faculty Publications

Supply networks existing today in many industries can behave as complex adaptive systems making them more difficult to analyze and assess. Being able to fully understand both the complex static and dynamic structures of a complex adaptive supply network (CASN) are key to being able to make more informed management decisions and prioritize resources and production throughout the network. Previous efforts to model and analyze CASN have been impeded by the complex, dynamic nature of the systems. However, drawing from other complex adaptive systems sciences, information theory provides a model-free methodology removing many of those barriers, especially concerning complex network …

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Degradation Of Carbon Fiber Reinforced Polymer And Graphite By Laser Heating, Nicholas C. Herr Sep 2016

Degradation Of Carbon Fiber Reinforced Polymer And Graphite By Laser Heating, Nicholas C. Herr

Theses and Dissertations

The availability of high power, diode pumped solid state and fiber lasers at powers 10 kW and shorter wavelengths (1.07 micrometer) has invigorated the development of tactical laser weapons. This shift to tactical missions greatly increases the variety of potential targets including carbon fiber reinforced polymers and related materials. The complexity of laser-material interactions has driven a historical reliance on live-fire testing and empirical models, but this becomes more difficult as the number of target materials grow. This dissertation combines thermal imagery and existing thermal models of the fire response of composite materials to develop a hybrid modeling approach of …

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Air Force Project Risk Management – The Impact Of Inconsistent Processes, Eric J. Perez Sep 2016

Air Force Project Risk Management – The Impact Of Inconsistent Processes, Eric J. Perez

Theses and Dissertations

On the surface, the majority of Air Force units appear to be executing some form of project risk management (PRM). Deeper investigation exposes many of the PRM practices currently in place to often be ad hoc, and as such, have the potential to poorly inform decisions when risk data is escalated to the enterprise levels of the Air Force. Resultantly, there is inconsistency between the PRM processes practiced by Air Force units. This inconsistency is an indication of risk mishandling at the project level and erroneous risk data provided at the enterprise levels of the Air Force. It may be …

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Space Qualification Testing Of A Deployable Shape Memory Alloy Cubesat Antenna, Carl L. Kobza Sep 2016

Space Qualification Testing Of A Deployable Shape Memory Alloy Cubesat Antenna, Carl L. Kobza

Theses and Dissertations

Increasingly capable CubeSat missions require antenna with improved Radio Frequency performance over the traditional CubeSat antennas. Deployable quadrifilar helical antennas (QHA) enable an acceptable stowing volume and deploy to provide increased gain and bandwidth over traditional patch and dipole antennas. Extensive ground testing is required to ensure the antenna is space qualified and to characterize the antenna deployment in the space environment. AFIT requires a QHA to perform a future CubeSat geolocation mission and contracted Helical Communication Technologies (HCT) to design and manufacture a Shape Memory Alloy (SMA) L-band deployable QHA. Vibration, thermal vacuum, laser vibrometer, and Voltage Standing Wave …

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Effect Of Stress Ratio On Fatigue Crack Growth Rate At Notched Hole In 7075-T6 Aluminum Alloy Under Biaxial Fatigue, Reja Alshahrani Sep 2016

Effect Of Stress Ratio On Fatigue Crack Growth Rate At Notched Hole In 7075-T6 Aluminum Alloy Under Biaxial Fatigue, Reja Alshahrani

Theses and Dissertations

This research investigates the behavior of fatigue crack growth rate in both laboratory air and saltwater (3.5% NaCl) environments for notched cruciform specimen made from 7075-T6 aluminum alloy sheet at different stress ratios. With biaxility ratio of 1, and frequency of applied load of 10 Hz, the crack growth behavior was investigated under in-plane biaxial tension-tension fatigue with 0.1, 0.5, 0.7 stress ratios and then compared them to study the effect of stress ratio on the crack growth rate. Finite Element Analysis (FEA) was used to calculate cyclic variation of stress intensity factors (delta K) at the crack tips. The …

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Orbit Determination Using Vinti's Solution, Steven P. Wright Sep 2016

Orbit Determination Using Vinti's Solution, Steven P. Wright

Theses and Dissertations

Orbital altitudes congested with spacecraft and debris combined with recent collisions have all but negated the Big Sky Theory. As the sheer number of orbital objects to track grows unbounded so does interest in prediction methods that are rapid and minimally computational. Claimed as the \other solvable solution, the recently completed solution too orbital motion about the earth, based on Vinti's method and including the major effects of the equatorial bulge, opens up the prospect of much more accurate analytical models for space situational awareness. A preliminary examination of this solution is presented. A numerical state transition matrix is found …

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Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature, Mohamed Noomen Sep 2016

Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature, Mohamed Noomen

Theses and Dissertations

The tension-tension fatigue behavior of a newly developed unitized composite material system was investigated. The unitized composite consisted of a polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC). The PMC portion consisted of an NRPE high-temperature polyimide matrix reinforced with carbon fibers woven in an eight harness satin weave (8HSW). The CMC layer is a single-ply non-crimp 3D orthogonal weave composite consisting of ceramic matrix reinforced with glass fibers. In order to assess the performance and suitability of this composite for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions …

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Application Of Executable Architecture In Early Concept Evaluation Using The Dod Architecture Framework, Zhongwang Chua Sep 2016

Application Of Executable Architecture In Early Concept Evaluation Using The Dod Architecture Framework, Zhongwang Chua

Theses and Dissertations

The increasing complexity in the development of today's modern warfighting systems demands a systematic evaluation approach in the assessment of the envisaged capability and estimating the cost effectiveness, especially in the early stages of Concept Development. This research focused on the development of early Concept evaluation methodology through the use of Executable Architecture (EA) through the System Architecting process. Particularly, the methodology was applied in the assessment of a proposed Multi-tiered Unmanned Aircraft System System-of-System that is designed provide target acquisition and conduct dynamic strike on Theater Ballistic Missile launchers. Through the implementation of the evaluation methodology using dynamic modeling …

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Optimal Control Of An Uninhabited Loyal Wingman, Clay J. Humphreys Sep 2016

Optimal Control Of An Uninhabited Loyal Wingman, Clay J. Humphreys

Theses and Dissertations

As researchers strive to achieve autonomy in systems, many believe the goal is not that machines should attain full autonomy, but rather to obtain the right level of autonomy for an appropriate man-machine interaction. A common phrase for this interaction is manned-unmanned teaming (MUM-T), a subset of which, for unmanned aerial vehicles, is the concept of the loyal wingman. This work demonstrates the use of optimal control and stochastic estimation techniques as an autonomous near real-time dynamic route planner for the DoD concept of the loyal wingman. First, the optimal control problem is formulated for a static threat environment and …

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Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event, Andrew J. Lingenfelter Sep 2016

Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event, Andrew J. Lingenfelter

Theses and Dissertations

Hydrodynamic Ram can cause damage to industrial and aircraft systems. The resulting transient spray increases the probability of fire. To better understand the driving mechanisms behind transient spray, internal, and external measurements of the cavity geometry, and entrained flow field were accomplished. Research determined cavity contraction and separation are pre-cursors to the initiation of the transient spray phases. The entrained flow measurement required development of a new and novel technique using a continuous wave laser and atomized water particles. The peak mass flow correlated well with cavity geometric features, such as cavity contraction. Using the mass flow, cavity diameter at …

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Evaluation Of The Impact Of An Additive Manufacturing Enhanced Cubesat Architecture On The Cubesat Development Process, Rachel E. Sharples Sep 2016

Evaluation Of The Impact Of An Additive Manufacturing Enhanced Cubesat Architecture On The Cubesat Development Process, Rachel E. Sharples

Theses and Dissertations

Additive manufacturing (AM) is a fabrication method ideally suited to low-quantity, highly customized builds, leading to interest in its application to satellite development and manufacturing, where each build is unique. Due to the issues of long development schedules and high development and manufacturing costs, methods are needed in the CubeSat development process to reduce the weight and volume of subsystems and decrease integration time. The work develops an architecture for an AM-augmented CubeSat and examines the AM techniques of embedded electronics, embedded thrusters, and custom radiation-hardened materials can impact the subsystems of a CubeSat. The AM-augmented architecture shows a shift …

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Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Different Biaxial Stress Ratios, Khalid A. Alghamdi Sep 2016

Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Different Biaxial Stress Ratios, Khalid A. Alghamdi

Theses and Dissertations

This thesis presents the results of a study to quantify the effects of biaxial loading on fatigue crack behavior in both air and saltwater (3.5% NaCl) environments from pre-cracked notched circular hole in a 7075-T6 cruciform specimen using a fracture mechanics approach. With stress ratio of R = 0.5, the crack growth behavior was investigated under fatigue loading with 0.5, 0, -0.5, and -1 biaxial stress ratio lambda. The crack propagation was monitored using optical microscopy. Finite Element Analysis was performed using the different stress ranges and stress ratios with various crack sizes to compute of stress intensity factors (delta …

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Adaptive Estimation And Heuristic Optimization Of Nonlinear Spacecraft Attitude Dynamics, Joshuah A. Hess Sep 2016

Adaptive Estimation And Heuristic Optimization Of Nonlinear Spacecraft Attitude Dynamics, Joshuah A. Hess

Theses and Dissertations

For spacecraft conducting on-orbit operations, changes to the structure of the spacecraft are not uncommon. These planned or unanticipated changes in inertia properties couple with the spacecraft's attitude dynamics and typically require estimation. For systems with time-varying inertia parameters, multiple model adaptive estimation (MMAE) routines can be utilized for parameter and state estimates. MMAE algorithms involve constructing a bank of recursive estimators, each assuming a different hypothesis for the systems dynamics. This research has three distinct, but related, contributions to satellite attitude dynamics and estimation. In the first part of this research, MMAE routines employing parallel banks of unscented attitude …

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Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances Sep 2016

Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances

Theses and Dissertations

Cognitive Radio (CR) is a promising technology that works by detecting unused parts of the spectrum and automatically reconfiguring the communication system's parameters in order to operate in the available communication channels while minimizing interference. CR enables efficient use of the Radio Frequency (RF) spectrum by generating waveforms that can coexist with existing users in licensed spectrum bands. Spectrum sensing is one of the most important components of CR systems because it provides awareness of its operating environment, as well as detecting the presence of primary (licensed) users of the spectrum.

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The Scaling Of Loss Pathways And Heat Transfer In Small Scale Internal Combustion Engines, Joseph K. Ausserer Sep 2016

The Scaling Of Loss Pathways And Heat Transfer In Small Scale Internal Combustion Engines, Joseph K. Ausserer

Theses and Dissertations

Prior literature indicates fuel conversion efficiency and normalized power deteriorate increasingly rapidly with decreasing displacement, but does not fully reveal the driving losses. The literature also suggested that increasing losses relax the required fuel anti-knock index (AKI), but offered conflicting conclusions on the performance impact. This comprehensive experimental study of three, 28 cm3 to 85 cm3 displacement, commercial-off-the-shelf (COTS), two-stroke ICEs identified short-circuiting as having the most deleterious impact on COTS engine performance in this size range. Heat transfer losses were comparable to larger engines for displaced volumes greater than 10 cm3. An engine friction model was developed that uses …

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Absolute Positioning Using The Earth's Magnetic Anomaly Field, Aaron J. Canciani Sep 2016

Absolute Positioning Using The Earth's Magnetic Anomaly Field, Aaron J. Canciani

Theses and Dissertations

Achieving worldwide alternatives to GPS is a challenging engineering problem. Current GPS alternatives often suffer from limitations such as where and when the systems can operate. Navigation using the Earth's magnetic anomaly field, which is globally available at all times, shows promise to overcome many of these limitations. We present a navigation filter which uses the Earth's magnetic anomaly field as a navigation signal to aid an inertial navigation system (INS) in an aircraft. The filter utilizes highly-accurate optically pumped cesium (OPC) magnetometers to make scalar measurements of the Earth's magnetic field and compare them to a map using a …

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Conceptual Architecture To Measure The Effects Of Subauroral Polarization Streams On Radar Operations, Shayla K. Redmond Sep 2016

Conceptual Architecture To Measure The Effects Of Subauroral Polarization Streams On Radar Operations, Shayla K. Redmond

Theses and Dissertations

This thesis provides the initial conceptual development of taking into account subauroral polarization streams when preparing for a radar operation. The DoDAF views created to portray the architecture consisted of operational, capabilities, data and information, and finally system views to ensure consistency and realistic outcomes. OV-2 was the significant view because it set the baseline for required actions necessary for the proposed results the Flow Integration of Ionospheric Activity and Radar Evaluation (FIIARE) system would produce. FIIARE is a computer based system concept that performs consolidations and produce predictions using algorithms from the International Reference Ionosphere (IRI). The data portrayed …

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Applying Lean To The Ac-130 Maintenance Process For The Royal Saudi Air Force, Fisal A. Alzahrani Sep 2016

Applying Lean To The Ac-130 Maintenance Process For The Royal Saudi Air Force, Fisal A. Alzahrani

Theses and Dissertations

The ideas expressed in this research come from the researchers experiences working in the AC-130 maintenance squadron in the Royal Saudi Air Force. The AC-130 maintenance process is not currently being used as effectively as it could be to make AC-130 fully mission capable. That can be done by improving communication, reducing distances needed to move or transport anything during the maintenance process and by efficient use of the available qualified workforces, tools and equipment. Consideration is given to applying an existing management technique to the Royal Saudi Air Forces AC-130 Maintenance Squadrons. The selected technique is the Lean management …

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Improving Real-World Performance Of Vision Aided Navigation In A Flight Environment, Donald T. Venable Sep 2016

Improving Real-World Performance Of Vision Aided Navigation In A Flight Environment, Donald T. Venable

Theses and Dissertations

The motivation of this research is to fuse information from an airborne imaging sensor with information extracted from satellite imagery in order to provide accurate position when GPS is unavailable for an extended duration. A corpus of existing geo-referenced satellite imagery is used to create a key point database. A novel algorithm for recovering coarse pose using by comparing key points extracted from the airborne imagery to the reference database is developed. This coarse position is used to bootstrap a local-area geo-registration algorithm, which provides GPS-level position estimates. This research derives optimizations for existing local-area methods for operation in flight …

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An Examination Of Commercial Motor Vehicle Hours Of Service Safety Regulation, Jason R. Anderson Sep 2016

An Examination Of Commercial Motor Vehicle Hours Of Service Safety Regulation, Jason R. Anderson

Theses and Dissertations

The Federal Motor Carrier Safety Administration (FMSCA) stipulates Hours of Service (HOS) regulations in order to minimize or eliminate fatigued truck driving, a major cause of truck-related accidents. This research examines the efficacy of HOS with three unique research approaches: 1) a typology classification model to indicate differences in HOS regulation from other safety regulations, 2) an exhaustive enumeration method utilizing the theoretical foundation of perishable inventory theory, and 3) a statistical analysis on accidents caused by or involving truck drivers. This research provides insight into similar Air Force Instructions regarding flight-time restrictions for pilots, which attempt to prevent flying …

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Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman Sep 2016

Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman

Faculty Publications

This paper examines a passive cooling technique using microelectromechanical systems (MEMS) for localized thermal management of electronic devices. The prototype was designed using analytic equations, simulated using finite element methods (FEM), and fabricated using the commercial PolyMUMPs™ process. The system consisted of an electronic device simulator (EDS) and MEMS bimorph cantilever beams (MBCB) array with beams lengths of 200, 250, and 300 μm that were tested to characterize deflection and thermal behavior. The specific beam lengths were chosen to actuate in response to heating associated with the EDS (i.e. the longest beams actuated first corresponding to the hottest portion of …

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Reconfigurable Liquid Attenuated Collimator, Larry W. Burggraf, Benjamin R. Kowash, Jack G. M. Fitzgerald Aug 2016

Reconfigurable Liquid Attenuated Collimator, Larry W. Burggraf, Benjamin R. Kowash, Jack G. M. Fitzgerald

AFIT Patents

A reconfigurable radiographic aperture mask collimator apparatus includes a body portion configured to receive an attenuating liquid having a first attenuation value per unit volume. The apparatus further includes a grid portion mated to a face of the body portion and a plurality of passageways each having a cross sectional area and a length. The plurality of passageways is disposed within the grid portion. A plurality of plugs is slidably disposed within the plurality of passageways, and each of the plurality of plugs has a second attenuation value per unit volume less than the first attenuation value. One of the …

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