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Theses and Dissertations

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Full-Text Articles in Engineering

Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein Mar 2010

Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein

Theses and Dissertations

A new flight controller was evaluated through piloted simulation and flight test conducted at the USAF Test Pilot School. The controller, commonly called a disturbance observer, uses inertial sensor feedback routed through a simple control architecture that acts to force the desired response while rejecting sensor noise and atmospheric disturbances. The investigation included both handling qualities testing in the Octonian simulator at the Air Force Research Laboratories Air Vehicle Directorate, and initial flight test conducted as part of a Test Management Project at the USAF TPS. Simulation produced positive results with desired performance throughout a wide flight envelope. In addition, …

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Orbit Maneuver For Responsive Coverage Using Electric Propulsion, Timothy S. Hall Mar 2010

Orbit Maneuver For Responsive Coverage Using Electric Propulsion, Timothy S. Hall

Theses and Dissertations

The use of continuous electric propulsion to manipulate a satellite’s orbit offers significant potential for enhancing coverage of a target in ways not previously considered. Elliptical orbits utilizing a very low perigee can facilitate access to the surface and atmosphere of the Earth at sub-ionosphere altitudes while counteracting atmospheric drag forces using continuous electric propulsion. Additionally, in-plane and out-of-plane manipulation of both circular and elliptical orbits can allow for passage of a satellite over a target at a given time. Sustained low perigee orbit was modeled with an initial perigee altitude of 100 km and various apogee altitudes to derive …

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Mechanical Properties Characterization And Business Case Analysis Of The Fiber Metal Laminate Glare-3 For Use As Secondary Aircraft Structure, Benjamin O. Elton Mar 2010

Mechanical Properties Characterization And Business Case Analysis Of The Fiber Metal Laminate Glare-3 For Use As Secondary Aircraft Structure, Benjamin O. Elton

Theses and Dissertations

This effort explored the mechanical characteristics and economic feasibility of using the fiber metal laminate, GLARE-3, as a secondary aircraft structure; specifically, the cargo floor of a C-130. The mechanical properties were determined through static four-point bending and tensile testing and dynamic impact testing. Aggregate behavior of the constituent materials was predicted using a model which consisted of Mass Volume Fraction (MVF) and Classical Laminated Plate Theory (CLPT) methods using known values for the constituents. Static testing was conducted on coupon-level specimens using standardized testing procedures. Static tensile tests were conducted on specimens with four different fiber orientations, 0°, 22.5°, …

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Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson Mar 2010

Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson

Theses and Dissertations

An instrument for monocular passive ranging based on atmospheric oxygen absorption near 762 nm has been designed, built and deployed to track emissive targets, including the plumes from jet engines or rockets. An intensified CCD array is coupled to variable band pass liquid crystal display filter and 3.5 – 8.8 degree field of view optics to observe the target. By recording sequential images at 7 Hz in three 6 nm width bands, the transmittance of the R-branch of the O2 (X-b) (0,0) band is determined. A metric curve for determining range from transmittance is developed using the HITRAN spectral …

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Fuel Efficiency Assessment With Dea, Evren Kiymaz Mar 2010

Fuel Efficiency Assessment With Dea, Evren Kiymaz

Theses and Dissertations

In this study, Data Envelopment Analysis (DEA) is used to calculate Air Mobility Command (AMC) airlift fuel efficiency for C-17 aircraft. Fuel is a strategic asset for the United States Air Force and suitable alternatives are not yet feasible or available in the quantity required. The Air Force is pursuing several initiatives to conserve energy and operate more efficiently while sustaining the same level of effectiveness and safety. In order to manage these initiatives, it must measure how well it is doing. To measure airlift efficiency, the AMC Fuel Efficiency Office established a 7 factor weighted Fuel Efficiency Index (FEI). …

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Manpower Cost Analysis Of A Distributed En Route Support Structure Versus A Consolidated En Route Support Structure, Phillip M. Rehmert Mar 2010

Manpower Cost Analysis Of A Distributed En Route Support Structure Versus A Consolidated En Route Support Structure, Phillip M. Rehmert

Theses and Dissertations

The United States military has developed an en route support structure for airlift requirements to deploy and sustain combat forces in conflict. The Air Mobility Command (AMC) is interested in determining the cost effectiveness of two distinctly different en route structures, in particular, the cost effectiveness of one large facility versus supporting combat forces with many smaller facilities. With the current operational tempo, continued analysis must be accomplished to determine if a smaller footprint is possible in the deployment and sustainment scenarios of conflicts seen today; conflicts more centered on a leaner and faster deployment force. This research examines the …

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An Exploration Of The Effects Of Maintenance Manning On Combat Mission Readiness Utilizing Agent Based Modeling, Adam S. Mackenzie Mar 2010

An Exploration Of The Effects Of Maintenance Manning On Combat Mission Readiness Utilizing Agent Based Modeling, Adam S. Mackenzie

Theses and Dissertations

Agent based models have been shown to be powerful tools in describing processes and systems centered on individual behaviors and local interactions (i.e. “bottom-up”) between specific entities. Current application areas tend to be focused within the business and social science arenas, although their usefulness has been demonstrated in the modeling of various chemistry and physics-based systems. Conversely, many highly process-oriented systems, such as manufacturing environments, tend to be modeled via “top-down” methods, including discrete or continuous event simulations among others. As a result, potentially critical attributes of the entities or resources modeled with these methods (spatial properties, “learning curve” or …

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Using Decision Analysis To Select Facility Maintenance Management Information Systems, Marchello T. Graddy Mar 2010

Using Decision Analysis To Select Facility Maintenance Management Information Systems, Marchello T. Graddy

Theses and Dissertations

Maintenance organizations, charged with preserving the built environment, are receiving a shrinking portion of an organization’s operational budget to do its job. It has been demonstrated through various studies that efficiencies can be gained by implementing a maintenance management information system (MMIS). However, with so many choices available, maintenance organizations often select the wrong system. This research effort used value-focused thinking decision analysis to create a model based on values from the Air Force Civil Engineer career field. Data for values and weights were collected from official documents and interviews. The resulting model is highly flexible, allowing the ultimate decision-maker …

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Optimization Of Environmental Conditions To Maximize Carbon Dioxide Sequestration Through Algal Growth, Kenneth M. Karcher Mar 2010

Optimization Of Environmental Conditions To Maximize Carbon Dioxide Sequestration Through Algal Growth, Kenneth M. Karcher

Theses and Dissertations

The micro-alga Chlorella vulgaris was cultivated under a variety of environmental conditions in various culture media solutions to assess and optimize growth rate and biomass productivity. Efforts during this work investigated growth parameters at the micro-scale in an air-lift bubble system with the goal of interpreting performance characteristics that can be applied to a larger serpentine tubular Photo-bioreactor. Maximum growth rates and biomass yields were 0.65 d-1 and 2.003 g biomass/L and achieved in seven days using urea in de-ionized water under a 24:0 Photoperiod (Light:Dark). Additionally, growth rates and biomass yields of 0.65 d-1 and 1.964 g …

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Development Of A Novel Noise Delivery System For Jp-8 Ototoxicity Studies, John E. Stubbs Mar 2010

Development Of A Novel Noise Delivery System For Jp-8 Ototoxicity Studies, John E. Stubbs

Theses and Dissertations

Numerous chemicals with ototoxic properties may cause hearing loss directly, potentiate noise-induced hearing loss, or produce additive effects. Of interest to the US Air Force are studies showing ototoxic effects of JP-8 jet fuel and its hydrocarbon constituents. The Naval Health Research Center (NHRC) at Wright-Patterson AFB, Ohio, in conjunction with the USAF, is studying the ototoxic effects of JP-8 in rats. The study requires a white noise source that is one octave band wide, centered at 8 kHz frequency, delivered from outside of exposure chambers. Sound pressure levels must be within ± 2 dB at all exposure points within …

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Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr Mar 2010

Afm-Patterned 2-D Thin-Film Photonic Crystal Analyzed By Complete Angle Scatter, Nicholas C. Herr

Theses and Dissertations

The purpose of this research was to use an atomic force microscope (AFM) to generate a 2-D square array of sub-wavelength surface features from a single material over a region large enough to permit optical characterization. This work is an extension of previous AFIT nano-patterning work and is in response to the small subunit sizes demanded for the production of optical metamaterials and photonic crystals. A diamond nano-indentation AFM probe was used to produce a 325-μm by 200-μm array of indentations in a 120-nm thick polystyrene film deposited on silicon. Indentation spacing of 400 nm produced well-defined surface features with …

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Changes To Electrical Conductivity In Irradiated Carbon-Nickel Nanocomposites, David F. Coy Mar 2010

Changes To Electrical Conductivity In Irradiated Carbon-Nickel Nanocomposites, David F. Coy

Theses and Dissertations

Pre and post irradiation resistivity and XAFS measurements have been conducted to examine the effects of 0.5 MeV electron irradiations on nickel-carbon composites. Results showed a decrease in surface resistivity in all sample types of 14-30% following irradiation with a total electron exposure of 4 x 10-16 cm-2. Results also showed a corresponding decrease in NiO content for the irradiated samples as compared to measurements of non-irradiated samples. Surface resistivity measurement capabilities were established and measurement techniques refined to produce repeatable results of sufficient precision to discern changes in resistivity for an exposure of 2 x 10 …

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Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran Mar 2010

Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran

Theses and Dissertations

Monte Carlo uncertainty quantification (UQ) capability has been added to a code for modeling multi-component steady-state isotope-separation enrichment cascades to characterize the propagation of uncertainties in input data that define the cascade and the feed. Random samples of error for every computational input are drawn from its individual uncertainty distribution and added to the inputs, creating a set of enrichment cascade problems with perturbed inputs. The set of problems is solved using the verified code. The cascade outputs are then characterized using the empirical cumulative distribution. The uncertainty output data are analyzed to gain new insights into the behaviors of …

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Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai Mar 2010

Development Of A Methodology For Customizing Insider Threat Auditing On A Linux Operating System, William T. Bai

Theses and Dissertations

Insider threats can pose a great risk to organizations and by their very nature are difficult to protect against. Auditing and system logging are capabilities present in most operating systems and can be used for detecting insider activity. However, current auditing methods are typically applied in a haphazard way, if at all, and are not conducive to contributing to an effective insider threat security policy. This research develops a methodology for designing a customized auditing and logging template for a Linux operating system. An intent-based insider threat risk assessment methodology is presented to create use case scenarios tailored to address …

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A Distributed Network Logging Topology, Nicholas E. Fritts Mar 2010

A Distributed Network Logging Topology, Nicholas E. Fritts

Theses and Dissertations

Network logging is used to monitor computer systems for potential problems and threats by network administrators. Research has found that the more logging enabled, the more potential threats can be detected in the logs (Levoy, 2006). However, generally it is considered too costly to dedicate the manpower required to analyze the amount of logging data that it is possible to generate. Current research is working on different correlation and parsing techniques to help filter the data, but these methods function by having all of the data dumped in to a central repository. Central repositories are limited in the amount of …

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Visually Managing Ipsec, Peter J. Dell'accio Mar 2010

Visually Managing Ipsec, Peter J. Dell'accio

Theses and Dissertations

The United States Air Force relies heavily on computer networks to transmit vast amounts of information throughout its organizations and with agencies throughout the Department of Defense. The data take many forms, utilize different protocols, and originate from various platforms and applications. It is not practical to apply security measures specific to individual applications, platforms, and protocols. Internet Protocol Security (IPsec) is a set of protocols designed to secure data traveling over IP networks, including the Internet. By applying security at the network layer of communications, data packets can be secured regardless of what application generated the data or which …

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Developing Cyberspace Data Understanding: Using Crisp-Dm For Host-Based Ids Feature Mining, Joseph R. Erskine Mar 2010

Developing Cyberspace Data Understanding: Using Crisp-Dm For Host-Based Ids Feature Mining, Joseph R. Erskine

Theses and Dissertations

Current intrusion detection systems generate a large number of specific alerts, but do not provide actionable information. Many times, these alerts must be analyzed by a network defender, a time consuming and tedious task which can occur hours or days after an attack occurs. Improved understanding of the cyberspace domain can lead to great advancements in Cyberspace situational awareness research and development. This thesis applies the Cross Industry Standard Process for Data Mining (CRISP-DM) to develop an understanding about a host system under attack. Data is generated by launching scans and exploits at a machine outfitted with a set of …

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Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly Mar 2010

Augmenting Latent Dirichlet Allocation And Rank Threshold Detection With Ontologies, Laura A. Isaly

Theses and Dissertations

In an ever-increasing data rich environment, actionable information must be extracted, filtered, and correlated from massive amounts of disparate often free text sources. The usefulness of the retrieved information depends on how we accomplish these steps and present the most relevant information to the analyst. One method for extracting information from free text is Latent Dirichlet Allocation (LDA), a document categorization technique to classify documents into cohesive topics. Although LDA accounts for some implicit relationships such as synonymy (same meaning) it often ignores other semantic relationships such as polysemy (different meanings), hyponym (subordinate), meronym (part of), and troponomys (manner). To …

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Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady Mar 2010

Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady

Theses and Dissertations

Radar systems provide an important remote sensing capability, and are crucial to the layered sensing vision; a concept of operation that aims to apply the right number of the right types of sensors, in the right places, at the right times for superior battle space situational awareness. The layered sensing vision poses a range of technical challenges, including radar, that are yet to be addressed. To address the radar-specific design challenges, the research community responded with waveform diversity; a relatively new field of study which aims reduce the cost of remote sensing while improving performance. Early work suggests that the …

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Global Navigation Satellite System Software Defined Radio, Jason M. Mcginthy Mar 2010

Global Navigation Satellite System Software Defined Radio, Jason M. Mcginthy

Theses and Dissertations

The GNSS world is quickly growing. The United States’ GPS, the European Union’s Galileo, China’s Compass, and Russia’s GLONASS systems are all developing or modernizing their signals, and there will soon be more navigation satellites in space than ever before. The goal of this research was to develop an initial capability for an AFIT GNSS software receiver. This software receiver is intended to be used for research purposes at the Advanced Navigation Technology (ANT) Center. First a GPS-only software receiver was built. It successfully acquired, tracked, and provided reasonable position estimates. Next, the receiver was successfully modified to acquire and …

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Development And Evaluation Of A Multistatic Ultrawideband Random Noise Radar, Matthew E. Nelms Mar 2010

Development And Evaluation Of A Multistatic Ultrawideband Random Noise Radar, Matthew E. Nelms

Theses and Dissertations

This research studies the AFIT noise network (NoNET) radar node design and the feasibility in processing the bistatic channel information of a cluster of widely distributed noise radar nodes. A system characterization is used to predict theoretical localization performance metrics. Design and integration of a distributed and central signal and data processing architecture enables the Matlab®-driven signal data acquisition, digital processing and multi-sensor image fusion. Experimental evaluation of the monostatic localization performance reveals its range measurement error standard deviation is 4.8 cm with a range resolution of 87.2(±5.9) cm. The 16-channel multistatic solution results in a 2-dimensional localization error of …

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Monocular Vision Localization Using A Gimbaled Laser Range Sensor, Don J. Yates Mar 2010

Monocular Vision Localization Using A Gimbaled Laser Range Sensor, Don J. Yates

Theses and Dissertations

There have been great advances in recent years in the area of indoor navigation. Many of these new navigation systems rely on digital images to aid an inertial navigation estimates. The Air Force Institute of Technology (AFIT) has been conducting research in this area for a number of years. The image-aiding techniques are centered around tracking stationary features in order to improve inertial navigation estimates. Previous research has used stereo vision systems or terrain constraints with monocular systems to estimate feature locations. While these methods have shown good results, they do have drawbacks. First, as unmanned exploration vehicles become smaller …

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Assembly, Integration, And Test Methods For Operationally Responsive Space Satellites, Lisa A. Baghal Mar 2010

Assembly, Integration, And Test Methods For Operationally Responsive Space Satellites, Lisa A. Baghal

Theses and Dissertations

Current government and industry standards in spacecraft testing result in an Assembly, Integration, and Test (AIT) timeline greater than six months. These standards will not support the vision of Operationally Responsive Space (ORS) to deploy a satellite within six days to fill an urgent need. Using the Air Force Research Laboratory’s Plug-and-Play Satellite (PnPSat), multiple Rapid AIT trials were conducted. By exercising the AIT process with various spacecraft configurations and personnel, methods for reducing or modifying traditional testing regimen were investigated.

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Experiments With Geometric Non-Linear Coupling For Analytical Validation, Jonathan D. Boston Mar 2010

Experiments With Geometric Non-Linear Coupling For Analytical Validation, Jonathan D. Boston

Theses and Dissertations

This study was focused on obtaining accurate experimental data for the validation of the geometrically exact beam theory from a series of experiments in which high quality surface shape and deflection data was collected. Many previous experiments have experienced issues with data collection or test articles which the researchers were unable to overcome. The test program was performed in two stages: qualification and joined-wing. The qualification stage validated the experimental procedures on simple 72 in long aluminum beams with 8 in x 0.5 in cross-sections. The joined-wing stage was the primary experiment focused on obtaining quality data for use in …

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Fatigue Behavior Of An Advanced Sic/Sic Composite With An Oxidation Inhibited Matrix At 1200°C In Air And In Steam, Jacob Delapasse Mar 2010

Fatigue Behavior Of An Advanced Sic/Sic Composite With An Oxidation Inhibited Matrix At 1200°C In Air And In Steam, Jacob Delapasse

Theses and Dissertations

The fatigue behavior of an advanced Silicon Carbide/Silicon Carbide (SiC/SiC) ceramic matrix composite (CMC) with oxidation inhibited matrix was investigated at 1200˚C in laboratory air and in steam environments. The composite consisted of an oxidation inhibited SiC matrix reinforced with Hi-Nicalon fibers coated with pyrolytic carbon (PyC) with a boron carbide overlay woven into eight-harness-satin (8HS) weave plies. Tensile stress-strain behavior and tensile properties were evaluated at 1200˚C. Tension-tension fatigue tests were conducted in both laboratory air and in steam at 1200˚C at frequencies of 0.1 Hz, 1.0 Hz, and 10 Hz. The tension-tension fatigue tests had a ratio of …

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Consideration Of Wear Rates At High Velocities, Stephen P. Meador Mar 2010

Consideration Of Wear Rates At High Velocities, Stephen P. Meador

Theses and Dissertations

The goal of this research is to study sliding contact wear of test sled slippers at high velocities. Experimentation representative of the slippers is infeasible, so numerical studies are used. An Eulerian-Lagrangian hydrocode called CTH is used to study mechanical wear. Failure criteria have been established to evaluate the stresses and strains resulting from the hydrocode simulation of a single asperity collision. The results from the hydrocode simulations are scaled to account for slipper bounce and multiple asperities, and these results produce total wear values that are approximately 90% of total experimental wear. Slipper thermodynamics have also been evaluated. The …

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Back-Pressure Effect On Shock-Train Location In A Scramjet Engine Isolator, Richard I. Paek Mar 2010

Back-Pressure Effect On Shock-Train Location In A Scramjet Engine Isolator, Richard I. Paek

Theses and Dissertations

The isolator of the scramjet decelerates the incoming high Mach flow to a lower Mach number and stabilizes the flow before it enters the combustor. Because of the unsteady combustion phenomenon and inconsistent completeness of the combustion, pressures within the combustor can vary drastically. These pressure variations can propagate forward and affect the flow field in the isolator - worst case unstarting the inlet. In this research, the shock train location versus the back-pressure is examined experimentally. The back-pressure is artificially created by symmetric (top & bottom) ramps that can close the flow area. Raising/lowering ramps result in higher/lower back-pressure. …

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Conceptual Design Tool For Fuel-Cell Powered Micro Air Vehicles, Paul M. Hrad Mar 2010

Conceptual Design Tool For Fuel-Cell Powered Micro Air Vehicles, Paul M. Hrad

Theses and Dissertations

A conceptual design tool was built to explore power requirements of a hybrid-power system for Micro Air Vehicles (MAVs) comparable in size to the Cooper's Hawk. An inviscid aerodynamic code, Athena Vortex Lattice (AVL), and a motor-propeller analysis code, QPROP, provide overall lift, drag, and thrust data for power-required calculation as functions of many variables to include mass, platform geometry, altitude, velocity, and mission duration. Phoenix Technologies’ Model Center was used to integrate multi-disciplinary components that employ specific power and specific energy of two power sources to determine power system mass required for a designated mission. The tool simulated a …

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Design Of A Film Cooling Experiment For Rocket Engines, Andrew L. Sincock Mar 2010

Design Of A Film Cooling Experiment For Rocket Engines, Andrew L. Sincock

Theses and Dissertations

The Film Cooling Rig (FCR) is a new test rig at the Air Force Institute of Technology (AFIT) to study film cooling for rocket engine applications. The original researcher designed, built, and then utilized the FCR to study radial curvature effects on film cooling for a non-combustion environment. This effort modified the FCR by adding propane-air combustion. Modular stainless steel test sections were produced to allow study of various curvatures and coolant injection angles. A pre-mixed burner was designed and built to deliver main flow mass flow rates necessary to produce blowing ratios as low as 0.5. A water cooling …

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Analysis Of Slewing And Attitude Determination Requirements For Ctex, William J. Starr Jr. Mar 2010

Analysis Of Slewing And Attitude Determination Requirements For Ctex, William J. Starr Jr.

Theses and Dissertations

This thesis examines the slewing and attitude determination requirements for the Chromotomographic Experiment (CTEX), a chromotomographic-based hyperspectral imager, to be mounted on-board the Japanese Experiment Module (JEM) External Facility (EF). The in-track slewing requirement is driven by the facts that CTEx has a very small field of view (FOV) and is required to collect 10 seconds of data for any given collection window. The need to slew in the cross-track direction is a product of the small FOV and target/calibration site access. CTEx incorporates a two-axis slow-steering dwell mirror with a range of ± 8 degrees and an accuracy of …

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