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Air Force Institute of Technology

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Articles 601 - 630 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Development Of A Model For 11C Production Via The 14N(P,Α) Reaction Using A Ge Pettrace Cyclotron, Amy C. Hall Mar 2019

Development Of A Model For 11C Production Via The 14N(P,Α) Reaction Using A Ge Pettrace Cyclotron, Amy C. Hall

Theses and Dissertations

The GE PETtrace 800 Series cyclotron at the Missouri University Research Reactor (MURR) facility is used extensively for medical and research radioisotope production. However, no model exists of its radioisotope production performance, and the energy, full intensity, and spatial profile of the cyclotron proton beam has never been measured. To improve production planning for research and medical isotopes, a MCNP6 model of the isotope production process was developed to maximize efficiency in target design and better understand irradiation conditions. Since the cyclotron beam energy and profile has a significant impact on the types of reactions that take place and the …

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Comparing Dual-Polarization Radar Lightning Forecast Methods Across Southwest Utah, Daniel O. Katuzienski Mar 2019

Comparing Dual-Polarization Radar Lightning Forecast Methods Across Southwest Utah, Daniel O. Katuzienski

Theses and Dissertations

Lightning poses a significant hazard to space launch operations to include ground processing, launch window forecasts, and rocket-triggered lightning events. Two lightning initiation forecast methods using weather radar developed in Gremillion and Orville (1999) and Travis (2015) for Cape Canaveral Air Force Station (CCAFS) and Kennedy Space Center (KSC), Florida are tested in a new geographical region. This is accomplished by applying the highest-performing radar parameters from Gremillion and Orville (1999): reectivity (Z) ≥ 40 dBZ for two consecutive volume scans at the -10°C thermal height and Travis (2015): Z ≥ 36.5 dBZ with differential reflectivity (ZDR) ≥ 0.31 dB …

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Instantaneous Bandwidth Expansion Using Software Defined Radios, Nicholas D. Everett Mar 2019

Instantaneous Bandwidth Expansion Using Software Defined Radios, Nicholas D. Everett

Theses and Dissertations

The Stimulated Unintended Radiated Emissions (SURE) process has been proven capable of classifying a device (e.g. a loaded antenna) as either operational or defective. Currently, the SURE process utilizes a specialized noise radar which is bulky, expensive and not easily supported. With current technology advancements, Software Defined Radios (SDRs) have become more compact, more readily available and significantly cheaper. The research here examines whether multiple SDRs can be integrated to replace the current specialized ultra-wideband noise radar used with the SURE process. The research specifically targets whether or not multiple SDR sub-band collections can be combined to form a wider …

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Preserving Privacy In Automotive Tire Pressure Monitoring Systems, Kenneth L. Hacker Mar 2019

Preserving Privacy In Automotive Tire Pressure Monitoring Systems, Kenneth L. Hacker

Theses and Dissertations

The automotive industry is moving towards a more connected ecosystem, with connectivity achieved through multiple wireless systems. However, in the pursuit of these technological advances and to quickly satisfy requirements imposed on manufacturers, the security of these systems is often an afterthought. It has been shown that systems in a standard new automobile that one would not expect to be vulnerable can be exploited for a variety of harmful effects. This thesis considers a seemingly benign, but government mandated, safety feature of modern vehicles; the Tire Pressure Monitoring System (TPMS). Typical implementations have no security-oriented features, leaking data that can …

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A Blockchain-Based Anomalous Detection System For Internet Of Things Devices, Joshua K. Mosby Mar 2019

A Blockchain-Based Anomalous Detection System For Internet Of Things Devices, Joshua K. Mosby

Theses and Dissertations

Internet of Things devices are highly susceptible to attack, and owners often fail to realize they have been compromised. This thesis describes an anomalous-based intrusion detection system that operates directly on Internet of Things devices utilizing a custom-built Blockchain. In this approach, an agent on each node compares the node's behavior to that of its peers, generating an alert if they are behaving differently. An experiment is conducted to determine the effectiveness at detecting malware. Three different code samples simulating common malware are deployed against a testbed of 12 Raspberry Pi devices. Increasing numbers are infected until two-thirds of the …

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Two-On-One Pursuit With A Non-Zero Capture Radius, Patrick J. Wasz Mar 2019

Two-On-One Pursuit With A Non-Zero Capture Radius, Patrick J. Wasz

Theses and Dissertations

In this paper, we revisit the "Two Cutters and Fugitive Ship" differential game that was addressed by Isaacs, but move away from point capture. We consider a two-on-one pursuit-evasion differential game with simple motion and pursuers endowed with circular capture sets of radius l > 0. The regions in the state space where only one pursuer effects the capture and the region in the state space where both pursuers cooperatively and isochronously capture the evader are characterized, thus solving the Game of Kind. Concerning the Game of Degree, the algorithm for the synthesis of the optimal state feedback strategies of the …

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Unguided Cyber Education Techniques Of The Non-Expert, Seth A. Martin Mar 2019

Unguided Cyber Education Techniques Of The Non-Expert, Seth A. Martin

Theses and Dissertations

The United States Air Force and Department of Defense continues to rely on its total workforce to provide the first layer of protection against cyber intrusion. Prior research has shown that the workforce is not adequately educated to perform this task. As a result, DoD cybersecurity strategy now includes attempting to improve education and training on cyber-related concepts and technical skills to all users of DoD networks. This paper describes an experiment designed to understand the broad methods that non-expert users may use to educate themselves on how to perform technical tasks. Preliminary results informed subsequent experiments that directly compared …

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Global Ionosonde And Gps Radio Occultation Sporadic-E Intensity And Height Comparison, Joshua Y. Gooch Mar 2019

Global Ionosonde And Gps Radio Occultation Sporadic-E Intensity And Height Comparison, Joshua Y. Gooch

Theses and Dissertations

A global, multi-year comparison of low and mid-latitude COSMIC GPS radio occultation (RO) sporadic-E (Es) plasma frequency and altitude and Digisonde blanketing frequency (fbEs) and altitude within 150 km and 30 minutes of each other. RO methods used to estimate the intensity of the Es layer include the scintillation index S4, total electron content (TEC) with both a constant and variable Es cloud thickness, and an Abel transform. The S4 and TEC with varying thickness techniques both under-represent the fbEs values while the TEC with constant thickness and Abel transform better estimate Digisonde fbEs values. …

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Coupled Atmospheric Surface Observations With Surface Aerosol Particle Counts For Daytime Sky Radiance Quantification, Scott S. Wolfmeyer Mar 2019

Coupled Atmospheric Surface Observations With Surface Aerosol Particle Counts For Daytime Sky Radiance Quantification, Scott S. Wolfmeyer

Theses and Dissertations

This study investigates the radiative transfer code, Laser Environmental Effects Definition and Reference (LEEDR), developed by the Center for Directed Energy at the Air Force Institute of Technology. Many multi- and hyperspectral applications are limited to the nighttime due in large part to daytime solar background noise and it is advantageous to be able to quantify this background noise using LEEDR. Real-time meteorological surface observations, numerical weather prediction, and aerosol particle concentrations were used to investigate the accuracy of LEEDR radiances simulations. Comparisons between simulations and measured values show that aerosol concentrations, weather predictions, and meteorological observations provide enough information …

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Modeling High-Altitude Nuclear Detonations Using Existing Ionospheric Models, Sophia G. Schwalbe Mar 2019

Modeling High-Altitude Nuclear Detonations Using Existing Ionospheric Models, Sophia G. Schwalbe

Theses and Dissertations

One threat to the United States is a nuclear weapon being detonated at high altitude over the country. The resulting electromagnetic pulse (EMP) could devastate the nation. Despite its destructive nature, the response of the ionosphere to such an event is poorly understood. This study assesses if existing ionospheric models, which are used to nowcast and forecast ionospheric changes, can be used to model the response to a high-altitude nuclear detonation (HAND). After comparing five ionosphere models, the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) was selected and modified to incorporate an array of F10.7 indices to serve as a proxy for …

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Non-Contact Height Estimation For Material Extrusion Additive Systems Via Monocular Imagery, Andrew C. Gorospe Mar 2019

Non-Contact Height Estimation For Material Extrusion Additive Systems Via Monocular Imagery, Andrew C. Gorospe

Theses and Dissertations

Additive manufacturing is a dynamic technology with a compelling potential to advance the manufacturing industry. Despite its capacity to produce intricate designs in an efficient manner, industry still has not widely adopted additive manufacturing since its commercialization as a result of its many challenges related to quality control. The Air Force Research Laboratory (AFRL), Materials and Manufacturing Directorate, Functional Materials Division, Soft Matter Materials Branch (RXAS) requires a practical and reliable method for maintaining quality control for the production of printed flexible electronics. Height estimation is a crucial component for maintaining quality control in Material Extrusion Additive Manufacturing (MEAM), as …

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The Effect Of Modeling Simultaneous Events On Simulation Results, John M. Carboni Mar 2019

The Effect Of Modeling Simultaneous Events On Simulation Results, John M. Carboni

Theses and Dissertations

This thesis explores the method that governs the prioritizing process for simultaneous events in relation to simulation results for discrete-event simulations. Specifically, it contrasts typical discrete-event simulation (DES) execution algorithms with how events are selected and ordered by the discrete-event system specification (DEVS) formalism. The motivation for this research stems from a desire to understand how the selection of events affects simulation output (i.e., response). As a particular use case, we briefly investigate the processing of simultaneous events by the Advanced Framework for Simulation, Integration and Modeling (AFSIM), a military discrete-event combat modeling and simulation package. To facilitate the building …

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Testing The Fault Tolerance Of A Wide Area Backup Protection System Using Spin, Kenneth James Mar 2019

Testing The Fault Tolerance Of A Wide Area Backup Protection System Using Spin, Kenneth James

Theses and Dissertations

Cyber-physical systems are increasingly prevalent in daily life. Smart grids in particular are becoming more interconnected and autonomously operated. Despite the advantages, new challenges arise in the form of defending these assets. Recent studies reveal that small-scale, coordinated cyber-attacks on only a few substations across the U.S. could result in cascading failures affecting the entire nation. In support of defending critical infrastructure, this thesis tests the fault tolerance of a backup protection system. Each transmission line in the system incorporates autonomous agents which monitor the status of the line and make decisions regarding the safety of the grid. Various malfunctions …

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Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone, Tara E. Crouch Mar 2019

Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone, Tara E. Crouch

Theses and Dissertations

Direct numerical simulation (DNS) computational fluid dynamic (CFD) calculations were performed on a 30° slice of 7° half-angle cones with increasing nose radii bluntness at Mach 10 while simulating a distributed roughness pattern on the cone surface. These DNS computations were designed to determine if the non-modal transition behavior observed in testing performed at the Arnold Engineering Development Center (AEDC) Hypervelocity Wind Tunnel 9 was induced via distributed surface roughness. When boundary layer transition is dominated by second mode instabilities, an increase in nose radius delays the transition location downstream. However, blunt nose experiments indicated that as the nose radius …

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Time Series Analysis Of Stochastic Networks With Correlated Random Arcs, Brendon T. Sands Mar 2019

Time Series Analysis Of Stochastic Networks With Correlated Random Arcs, Brendon T. Sands

Theses and Dissertations

While modern day weather forecasting is not perfect, there are many benefits given by the multitude and variety of predictive models. In the interest of routing airplanes, this paper uses time series analysis on successive weather forecasts to predict the optimal path and fuel burn of wind-based, fuel-burn networks with stochastic correlated arcs. Networks are populated with either deterministic or ensemble-based weather data, and the two data sources with and without time series analysis are compared. Methods were compared by fuel burn prediction accuracy and ability to predict a future optimal path. Of the four options, the ensemble-based methods were …

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Investigation Of Endwall Vortex Manipulation In High Lift Turbines Caused By Active Endwall Forcing, Horatio J. Babcock Mar 2019

Investigation Of Endwall Vortex Manipulation In High Lift Turbines Caused By Active Endwall Forcing, Horatio J. Babcock

Theses and Dissertations

With the increased demand for lighter, more fuel efficient and smaller gas turbine engines, the impetus to reduce the weight and size of the turbine has become apparent. One approach to reduce this weight is to reduce the number of blades in the turbine. However, to maintain power output, each blade must be capable of supporting a greater amount of lift. While several high-lift turbine profiles have been detailed in literature, most of these profiles have increased endwall losses, despite their desirable mid-span characteristics. To mitigate this endwall loss, a number of active and passive flow approaches have been studied …

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Fracture Toughness And Fatigue Crack Growth Rate Characterization Of Inconel 718 Formed By Laser Powder Bed Fusion, Charles C. Hohnbaum Mar 2019

Fracture Toughness And Fatigue Crack Growth Rate Characterization Of Inconel 718 Formed By Laser Powder Bed Fusion, Charles C. Hohnbaum

Theses and Dissertations

Continuing improvement in the field of AM of metals provides the opportunity for direct fabrication of aerospace parts. AM was once used in large part for rapid prototyping but improvements in technology and increases in the knowledge base of AM materials has provided the opportunity for manufacture of AM parts for operational use. The ability to create low numbers of unique parts without having to invest in expensive tooling provides great economic incentive to utilize this technique. IN718 is the most common high temperature alloy used in the aerospace industry and lends itself readily to formation by LPBF. The superior …

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Creep Of Nextel 720/Alumina Ceramic Matrix Composite With Diamond-Drilled Effusion Holes At 1200°C In Air And In Steam, Megan L. Harkins Mar 2019

Creep Of Nextel 720/Alumina Ceramic Matrix Composite With Diamond-Drilled Effusion Holes At 1200°C In Air And In Steam, Megan L. Harkins

Theses and Dissertations

A recent study evaluated tensile stress-strain and tensile creep behavior of an oxide-oxide composite (Nextel™720/alumina) with laser-drilled effusion holes at 1200°C. It was determined that the presence of laser-drilled holes degraded the mechanical properties and performance of the CMC as a result of damage caused to the composite microstructure by the laser drilling process. Based on these results, the present effort sought to assess the effects of diamond-drilled holes on the mechanical behavior of this CMC. Tensile properties of the N720/A composite at 1200°C in laboratory air were unaffected by the presence of an array of 17 diamond-drilled effusion holes. …

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Scaling Film Cooling Adiabatic Effectiveness With Mass Transfer And Thermal Experimental Techniques, Luke J. Mcnamara Mar 2019

Scaling Film Cooling Adiabatic Effectiveness With Mass Transfer And Thermal Experimental Techniques, Luke J. Mcnamara

Theses and Dissertations

With increasing engine temperatures, it is becoming more important to design effective film cooling schemes. Low temperature, large scale tests are often implemented in the design process to reduce cost and complexity. A nondimensional adiabatic effectiveness can be used as an indication of the performance of a film cooling scheme. However, the coolant flow rate must be properly scaled between the low temperature tests and engine temperatures to accurately predict film cooling effectiveness. This process is complicated by gas property variation with temperature. Tests are commonly conducted using thermal measurement techniques with infrared thermography (IR), but the use of pressure …

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Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung Mar 2019

Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung

Theses and Dissertations

A recent research effort, sponsored by the Air Force Office of Scientific Research, numerically investigated the unsteady aerodynamic flow field around an oscillating, straked, delta wing. The study was centered on determining the importance of the unsteady aerodynamic forces acting as a driver for a nonlinear motion known as limit cycle oscillations. The current effort focused on creating a computational model to compare to the results of previous tests and modeling efforts and discover new information regarding the onset of LCO. The computational model was constructed using the Cartesian overset capabilities of the CREATE-AV™ fixed wing fluid dynamics solver Kestrel. …

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Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt Mar 2019

Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt

Theses and Dissertations

Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, time-averaged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide time-accurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain time-accurate force …

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Lightning Prediction Using Recurrent Neural Networks, Dominick V. Speranza Mar 2019

Lightning Prediction Using Recurrent Neural Networks, Dominick V. Speranza

Theses and Dissertations

Cape Canaveral Air Force Station (CCAFS), Kennedy Space Center (KSC), and Patrick Air Force Base (PAFB) all reside in the thunderstorm capital of the United States. According to the Florida Climate Center, these installations experience more thunderstorms per year than any other place in the United States. It is the mission of the 45th Weather Squadron to provide timely and accurate warnings of weather conditions such as lightning that pose a risk to assets and personnel CCAFS, KSC and PAFB. To aid 45th Weather Squadron forecasters, a network of 30 Electric Field Mills (EFM) was installed in the area in …

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Virus Adsorption To Colloids In Water: Interactions Between Bacteriophage Ms2, Kaolinite, And Fiberglass, Ashlee N. Ellis Mar 2019

Virus Adsorption To Colloids In Water: Interactions Between Bacteriophage Ms2, Kaolinite, And Fiberglass, Ashlee N. Ellis

Theses and Dissertations

Virus adsorption to colloidal particles is an important issue in the water quality community, and it is a particularly important issue for conventional wastewater treatment plants that accept biohazardous waste. Colloids impact the transport of viruses in engineered treatment systems, and they also provide protection against oxidants and other destructive mechanisms. This study evaluated the adsorption of bacteriophage MS2 to colloidal suspensions of kaolinite (KAO) and fiberglass (FG). A series of laboratory batch tests were carried out over a range of experimental conditions to determine kinetic rate constants and characterize bond strength, and computational experiments were done to assess both …

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Analyzing The Efficiency Of Horizontal Photovoltaic Cells At Air Force Installations In Various Climate Regions, Parker A. Hines Mar 2019

Analyzing The Efficiency Of Horizontal Photovoltaic Cells At Air Force Installations In Various Climate Regions, Parker A. Hines

Theses and Dissertations

The U.S. Air Force relies heavily on electrically powered facilities to ensure mission-critical capabilities can be carried out. Without a resilient electrical system in place, the U.S. Air Force could be without power for extended periods, resulting in severe implications. Installing a photovoltaic array on an installation is one strategy to improve energy resiliency. The amount of power a photovoltaic array can produce is reliant on its geographical location, position and weather characteristics. This research presents the development of novel linear regression models based upon 14 case studies from global Department of Defense (DoD) installations to predict horizontal photovoltaic power …

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Modeling Power Output Of Horizontal Solar Panels Using Multivariate Linear Regression And Random Forest Machine Learning, Christil K. Pasion Mar 2019

Modeling Power Output Of Horizontal Solar Panels Using Multivariate Linear Regression And Random Forest Machine Learning, Christil K. Pasion

Theses and Dissertations

United States Air Force energy resiliency goals are aimed to increase renewable energy implementation among its facilities. Researchers at the Air Force Institute of Technology designed, manufactured, and distributed 37 photovoltaic test systems to Air Force installations around the world. This research uses two types of modeling techniques, multivariate linear regression and random forest machine learning, to determine which technique will better predict power output for horizontal solar panels. Many previous solar panel prediction studies use solar irradiation data as an input. This study does not use irradiation as an input and aims to predict power output with input variables …

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Non-Intrusive Occupancy Detection Methods And Models, James C. Tyhurst Mar 2019

Non-Intrusive Occupancy Detection Methods And Models, James C. Tyhurst

Theses and Dissertations

Occupants in the built environment impact facility energy consumption and indoor air quality. Predicting the presence of occupants within the built environment can therefore be used to manage these factors while providing additional benefits in terms of emergency management and future space utilization. Detecting occupancy requires a combination of sensors and models to accurate assess data collected within facilities to predict occupancy. This thesis investigated occupancy detection through a non-invasive data collection sensors and model. Specifically, this thesis sought to answer two research questions examining the ability of a radial basis function to accurately predict occupancy when generated from data …

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Characterization Of Tropical Cyclone Intensity Using Microwave Imagery, Amanda M. Nelson Mar 2019

Characterization Of Tropical Cyclone Intensity Using Microwave Imagery, Amanda M. Nelson

Theses and Dissertations

In the absence of wind speed data from aircraft reconnaissance of tropical cyclones (TCs), analysts rely on remote sensing tools to estimate TC intensity. For over 40 years, the Dvorak technique has been applied to estimate intensity using visible and infrared (IR) satellite imagery, but its accuracy is sometimes limited when the radiative effects of high clouds obscure the TC convective structure below. Microwave imagery highlights areas of precipitation and deep convection revealing different patterns than visible and IR imagery. This study explores application of machine learning algorithms to identify patterns in microwave imagery to infer storm intensity, particularly focusing …

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Initial Stage Of Fluid-Structure Interaction Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Dustin P. Graves Mar 2019

Initial Stage Of Fluid-Structure Interaction Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Dustin P. Graves

Theses and Dissertations

The analysis of a celestial icosahedron geometry is considered as a potential design for a Vacuum Lighter than Air Vehicle (VLTAV). The goal of the analysis is ultimately to understand the initial fluid-structure interaction of the VLTAV and the surrounding airflow. Up to this point, previous research analyzed the celestial icosahedron VLTAV in relation to withstanding a symmetric sea-level pressure applied to the membrane of the structure. This scenario simulates an internal vacuum being applied in the worst-case atmospheric environmental condition. The next step in analysis is to determine the aerodynamic effects of the geometry. The experimental setup for obtaining …

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Control Strategies For Multi-Evaporator Vapor Compression Cycles, Sunderlin D. Jackson Mar 2019

Control Strategies For Multi-Evaporator Vapor Compression Cycles, Sunderlin D. Jackson

Theses and Dissertations

Next-generation military aircraft must be able to handle highly transient thermal loads that exceed the ability of current aircraft thermal subsystems. Vapor compression cycle systems are a particular refrigeration technology that is an attractive solution for dealing with this challenge, due primarily to their high efficiency. However, there are several barriers to realizing the benefits of vapor cycles systems for controlling thermal loads in military aircraft. This thesis focuses on addressing the challenge of controlling vapor cycles in the presence of highly transient evaporator heat loads. Specifically, a linear quadratic regulator (LQR) is designed for a simple vapor cycle system, …

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Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda Mar 2019

Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda

Theses and Dissertations

High-speed Schlieren photography was utilized to visualize flow in the Air Force Research Laboratory Mach 6 Ludwieg tube facility. A 7° half-angle cone/flare model with variable nosetip radius and flare angle options was used in the study. Testing was performed at two driver tube pressures, generating freestream Reynolds numbers of 10.0x106 and 19.8x106 per meter. The variable-angle flare portion of the model provided a method for adjusting the intensity of the adverse pressure gradient at the cone/flare junction. As expected from existing literature, boundary layer separation along the cone frustum occurred further upstream as the magnitude of the …

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