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Air Force Institute of Technology

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Articles 2161 - 2190 of 5700

Full-Text Articles in Engineering

Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler Mar 2013

Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler

Theses and Dissertations

Engineers have attempted to improve reliability and lifecycle performance using novel micro-contact metals, unique mechanical designs and packaging. Contact resistance can evolve over the lifetime of the micro-switch by increasing until failure. This work shows the fabrication of micro-contact support structures and test fixture which allow for micro-contact testing, with an emphasis on the fixture's design to allow the determination and analysis of the appropriate failure mode. The other effort of this investigation is the development of a micro-contact test fixture which can measure contact force and resistance directly and perform initial micro-contact characterization, and two forms of lifecycle testing …

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Network Intrusion Dataset Assessment, David J. Weller-Fahy Mar 2013

Network Intrusion Dataset Assessment, David J. Weller-Fahy

Theses and Dissertations

Research into classification using Anomaly Detection (AD) within the field of Network Intrusion Detection (NID), or Network Intrusion Anomaly Detection (NIAD), is common, but operational use of the classifiers discovered by research is not. One reason for the lack of operational use is most published testing of AD methods uses artificial datasets: making it difficult to determine how well published results apply to other datasets and the networks they represent. This research develops a method to predict the accuracy of an AD-based classifier when applied to a new dataset, based on the difference between an already classified dataset and the …

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Vehicle Minimization For The Multimodal Pickup And Delivery Problem With Time Windows, Benjamin A . Clapp Mar 2013

Vehicle Minimization For The Multimodal Pickup And Delivery Problem With Time Windows, Benjamin A . Clapp

Theses and Dissertations

The algorithm proposed here is used for heuristic solutions for the Multimodal Multiple Vehicle Routing Problem with Unloading Capacity, Pickup and Dropoff, and Time Windows, solved so as to minimize the number of vehicles used, subject to varying objective function values for each vehicle. The MVRP is simplified and split into a routing problem and a scheduling problem. The routing problem is addressed by Dijkstra's Algorithm. This generates a new network for the second stage of the algorithm. It is assumed that the shortest path is the correct path to use, and shipments each travel unimodally. The scheduling problem is …

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A Mixed Integer Programming Model For Improving Theater Distribution Force Flow Analysis, Micah J. Hafich Mar 2013

A Mixed Integer Programming Model For Improving Theater Distribution Force Flow Analysis, Micah J. Hafich

Theses and Dissertations

Obtaining insight into potential vehicle mixtures that will support theater distribution, the final leg of military distribution, can be a challenging and time consuming process for United States Transportation Command (USTRANSCOM) force flow analysts. The current process of testing numerous different vehicle mixtures until separate simulation tools demonstrate feasibility is iterative and overly burdensome. Improving on existing research, a mixed integer programming model was developed to allocate specific vehicle types to delivery items, or requirements, in a manner that would minimize both operational costs and late deliveries. This gives insight into the types and amounts of vehicles necessary for feasible …

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Aerial Refueling Simulator Validation Using Operational Experimentation And Response Surface Methods With Time Series Responses, Alexander P. Hillman Mar 2013

Aerial Refueling Simulator Validation Using Operational Experimentation And Response Surface Methods With Time Series Responses, Alexander P. Hillman

Theses and Dissertations

An important program in the Department of Defense is the KC-46 Supertanker. Dubbed the future of the Air Force's aerial refueling inventory, the KC-46 will replace dozens of ailing previous generation tanker aircraft. The Aerial Refueling Airplane Simulator Qualification document governs the methods by which Air Mobility Command validates its simulators, some of which will be KC-46 simulators in the near future. The methodology set forward in this thesis utilizes historical data of aircraft performance from similar air frames to gain statistical insight into the performance design space of the KC-46. Leveraging this insight, the methodology provides through a framework …

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Control Variates And Optimal Designs In Metamodeling, Joshua B. Meents Mar 2013

Control Variates And Optimal Designs In Metamodeling, Joshua B. Meents

Theses and Dissertations

At the heart of most modeling issues is a focus on variance reduction. Experimental designs are chosen based on both efficiency and a variety of variance based criteria. In many situations due to cost, time and availability issues it is beneficial to produce metamodels of simulations. Experimental designs for the region of operability are constructed to collect the simulation output required to construct representative metamodels. Independently, the method of control variates is a well established technique often employed to reduce variance in discrete event simulations. This thesis explores the variance reduction benefits that can be obtained by combining optimal experimental …

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Evaluating Courses Of Actions At The Strategic Planning Level, Alhmet Ozdemir Mar 2013

Evaluating Courses Of Actions At The Strategic Planning Level, Alhmet Ozdemir

Theses and Dissertations

Like almost all real life problems, Strategic planning is a good example of a problem with more than one objective. One of the most important steps of strategic planning is to generate and evaluate the courses of actions (COA) which can fulfill the mission and vision of the organization. This is a critical process since it is impractical to start the executed COA over. In this research, value-focused thinking (VFT) is used as a decision analysis tool to assess COAs. A general model is created to select the best COA for strategic planning such as air force operation planning. To …

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Modeling The Impact Of The Payload Alert Communications System (Pacs) On The Accuracy Of Conjunction Analysis, Landon B. Bastow Mar 2013

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 …

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Fist And The Analytical Hierarchy Process: Comparative Modeling, Trevor A . Gustafson Mar 2013

Fist And The Analytical Hierarchy Process: Comparative Modeling, Trevor A . Gustafson

Theses and Dissertations

FIST is an emerging and unproven rapid acquisition model that stands for Fast, Inexpensive, Simple, and Tiny. The purpose of this research is to develop an Analytical Hierarchy Process (AHP) model based on the FIST concepts, to be applied as a comparative tool against the FIST model. The results indicate that the FIST model is reproducible with the AHP theory and that there are certain program characteristics that denote if a program would benefit from being developed by FIST. However, there are distinct weaknesses to the model that signify not all programs would succeed if FIST was employed during development. …

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Understanding The Effects Of Climate On Airfield Pavement Deterioration Rates, Justin C. Meihaus Mar 2013

Understanding The Effects Of Climate On Airfield Pavement Deterioration Rates, Justin C. Meihaus

Theses and Dissertations

Over the past two decades, pavement engineers at the Air Force Civil Engineer Center have noticed the majority of identified distresses from PCI airfield surveys are climate related. To verify these trends, a comprehensive analysis of the current airfield pavement distress database was accomplished based on a climate region perspective. A four-zone regional climatic model was created for the United States using geospatial interpolation techniques and climate data acquired from WeatherBank Inc. Once the climatic regional model was developed, the climate information for each installation was imported into the Air Force pavement distress database within PAVER. Utilizing the pavement condition …

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Assessment Of Potential Carbon Dioxide-Based Demand Control Ventilation System Performance In Single Zone Systems, Joseph G. Pickenpaugh Mar 2013

Assessment Of Potential Carbon Dioxide-Based Demand Control Ventilation System Performance In Single Zone Systems, Joseph G. Pickenpaugh

Theses and Dissertations

Heating, ventilation, and air conditioning (HVAC) use accounts for 43% of commercial energy consumption, with close to 5% used for ventilation purposes. Federal government agencies face both energy consumption reduction mandates and reduced funding. Carbon dioxide (CO2) based demand control ventilation (DCV) is a technology that allows for reduced energy consumption by allowing facility designers to introduce outside air based on facility occupancy, per American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) standards. This research aims to create a generalized methodology assessing energy and cost reductions from CO2-based DCV and then apply it to a specific facility at …

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Effects Of Stereoscopic 3d Digital Radar Displays On Air Traffic Controller Performance, Jason G. Russi Mar 2013

Effects Of Stereoscopic 3d Digital Radar Displays On Air Traffic Controller Performance, Jason G. Russi

Theses and Dissertations

Air traffic controllers are responsible for directing air traffic based upon decisions made from traffic activity depicted on 2Dimensional (2D) radar displays. Controllers must identify aircraft and detect potential conflicts while simultaneously developing and executing plans of action to ensure safe separation is maintained. With a nearly 100% increase in traffic expected within the next decade (FAA, 2012a), controllers' abilities to rapidly interpret spacing and maintain awareness for longer durations with increased workload will become increasingly imperative to safety. The current display design spatially depicts an aircraft's position relative to the controller's airspace as well as speed, altitude, and direction …

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Applying Hyperspectral Imaging To Heart Rate Estimation For Adaptive Automation, Joshua M. Splawn Mar 2013

Applying Hyperspectral Imaging To Heart Rate Estimation For Adaptive Automation, Joshua M. Splawn

Theses and Dissertations

Automation use continues to increase in Air Force systems with the goal of improving operator efficiency and effectiveness. Unfortunately, systems are often complex, potentially imposing increased mental task load on the operator, or placing the operator in a supervisory role where they can become dependent on automation. Adaptive automation is a proposed solution, where automation is triggered when an operator is overloaded, and disabled as the operator is underloaded. Changes in physiological measures have shown promise in triggering automation. Unfortunately heart rate measurement can be obtrusive and impractical in day-to-day operations. This research used the Air Force Multi-Attribute Task Battery …

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Digitally Programmable Rf Mems Filters With Mechanically Coupled Resonators, Hengky Chandrahalim, Sunil Ashok Bhave Mar 2013

Digitally Programmable Rf Mems Filters With Mechanically Coupled Resonators, Hengky Chandrahalim, Sunil Ashok Bhave

AFIT Patents

A digitally-tunable RF MEMS filter includes a substrate and a plurality of mechanically coupled resonators, wherein a first and a last resonator of the plurality of mechanically coupled resonators are configured to be electrostatically transduced. One or more of the plurality of mechanically coupled resonators are configured to be biased relative to the substrate such that the one or more biased resonators may be brought substantially in contact with the substrate. In a method of digitally tuning an RF MEMS filter having a mechanically coupled resonator array, a DC bias voltage is applied to at least a first resonator and …

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Mosaic Imager Using Wave Front Control, Mark T. Gruneisen, Matthew B. Garvin, Raymond C. Dymale, James R. Rotge Mar 2013

Mosaic Imager Using Wave Front Control, Mark T. Gruneisen, Matthew B. Garvin, Raymond C. Dymale, James R. Rotge

AFIT Patents

A wave front control system ("WFCS") organizes the object scene into a mosaic comprised of a grid of segments and transmits each segment in a temporal sequence. The WFCS steers the light fronts emanating from each segment, one segment at a time, through a series of optical components that transmit the light fronts respectively emanating from each segment onto a digital imaging sensor. An optical recording device records each sensed segment, and the object scene is composed by assembling the recorded segments. This abstract is provided to comply with the rules requiring an abstract, and is intended to allow a …

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Examining The Validity Of Using A Gaussian Schell-Model Source To Model The Scattering Of A Fully Coherent Gaussian Beam From A Rough Impedance Surface, Santasri Basu, Milo W. Hyde Iv, Salvatore J. Cusumano, Michael A. Marciniak, Steven T. Fiorino Mar 2013

Examining The Validity Of Using A Gaussian Schell-Model Source To Model The Scattering Of A Fully Coherent Gaussian Beam From A Rough Impedance Surface, Santasri Basu, Milo W. Hyde Iv, Salvatore J. Cusumano, Michael A. Marciniak, Steven T. Fiorino

Faculty Publications

Military applications that use adaptive optics (AO) often require a point source beacon at the target to measure and correct for wavefront aberrations introduced by atmospheric turbulence. However, turbulence prevents the formation of such a point beacon. The extended beacons that are created instead have finite spatial extents and exhibit varying degrees of spatial coherence. Modeling these extended beacons using a Gaussian Schell-model (GSM) form for the autocorrelation function would be a convenient approach due to the analytical tractability of Gaussian functions. We examine the validity of using such a model by evaluating the field scattered from a rough impedance …

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Development And Characterization Of A Chromotomosynthetic Hyperspectral Imaging System, Randall L. Bostick Mar 2013

Development And Characterization Of A Chromotomosynthetic Hyperspectral Imaging System, Randall L. Bostick

Theses and Dissertations

A chromotomosynthetic imaging (CTI) methodology based upon mathematical reconstruction of a set of 2-D spectral projections to collect high-speed (100 Hz) 3-D hyperspectral data cube has been proposed. The CTI system can simultaneously provide usable 3-D spatial and spectral information, provide high-frame rate slitless 1-D spectra, and generate 2-D imagery equivalent to that collected with no prism in the optical system. The wavelength region where prism dispersion is highest (500 nm) is most sensitive to loss of spectral resolution in the presence of systematic error, while wavelengths 600 nm suffer mostly from a shift of the spectral peaks. The quality …

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Discrimination Between Child And Adult Forms Using Radar Frequency Signature Analysis, Stephanie R. Keith Mar 2013

Discrimination Between Child And Adult Forms Using Radar Frequency Signature Analysis, Stephanie R. Keith

Theses and Dissertations

In this thesis we develop a method to discriminate between adult and child radar signatures. In particular, we examine radar data measured from behind a wall, which introduces radar signal attenuation and multipath effects. To investigate the child/adult discrimination problem in a through-wall, multipath scenario, a previously developed free-space human scattering model was expanded to incorporate multiple paths, and the effects of transmission through, and reflections from, walls and ground. The ground was modeled as a perfectly reflecting surface, while the walls were modeled as homogeneous concrete slabs. Twenty-five reflection paths were identified, involving the direct paths, as well as …

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Film Cooling In Fuel Rich Environments, Jacob J. Robertson Mar 2013

Film Cooling In Fuel Rich Environments, Jacob J. Robertson

Theses and Dissertations

The ultra compact combustor is a high performance gas turbine design concept that portends reduced weight for future weapons platforms. A natural outcome of the design is the continual presence of fuel-rich air in the turbine component of the engine. Because modern cooling schemes for hot section turbine blades involve injecting cool, oxygen-rich air adjacent to the surface, the potential arises for reaction with the unconsumed radicals in the mainstream ow and augmented heat transfer to the blade. This outcome is contrary to the purpose of film cooling, and can lead to early life-cycle turbine failure. This study examined the …

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Design And Testing Of An H2/O2 Predetonator For A Simulated Rotating Detonation Engine Channel, Stephen J. Miller Mar 2013

Design And Testing Of An H2/O2 Predetonator For A Simulated Rotating Detonation Engine Channel, Stephen J. Miller

Theses and Dissertations

A study is presented on the relationship between a pre-detonator and a detonation channel of an RDE. Testing was conducted on a straight narrow channel made of clear polycarbonate windows connected to an H2/O2 pre-detonator to simulate the RDE initiation scheme and allow for flow visualization. A comparison is made on decoupling distance and wave velocities for a range of pre-detonator designs, inclination angles, equivalence ratios and geometries placed within the simulated channel. Regardless of inclination angle or equivalence ratio the detonation wave decoupled within 25 mm from the pre-detonator exit into the channel. A step change in diameter 25 …

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Insertion Of Lithium Ions Into Tio2 (Rutile) Crystals: An Electron Paramagnetic Resonance Study Of The Li-Associated Ti3+ Small Polaron, A. T. Brant, Nancy C. Giles, Larry E. Halliburton Feb 2013

Insertion Of Lithium Ions Into Tio2 (Rutile) Crystals: An Electron Paramagnetic Resonance Study Of The Li-Associated Ti3+ Small Polaron, A. T. Brant, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify a Ti3+-Li+ complex in TiO2 crystals having the rutile structure. This defect consists of an interstitial Li+ ion adjacent to a substitutional Ti3+ ion (the unpaired electron on the Ti3+ ion provides charge compensation for the Li+ ion). The neutral Ti3+-Li+ complex is best described as a donor-bound small polaron and is similar in structure to the recently reported neutral fluorine and hydrogen donors in TiO2 (rutile). Lithium ions are diffused into the crystals at …

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Guided Wave-Based J-Integral Estimation For Dynamic Stress Intensity Factors Using 3d Scanning Laser Doppler Vibrometry, J. Ayers, Christopher Todd Owen, Eric D. Swenson, Anindya Ghoshal, V. Weiss Jan 2013

Guided Wave-Based J-Integral Estimation For Dynamic Stress Intensity Factors Using 3d Scanning Laser Doppler Vibrometry, J. Ayers, Christopher Todd Owen, Eric D. Swenson, Anindya Ghoshal, V. Weiss

Faculty Publications

The application of guided waves to interrogate remote areas of structural components has been researched extensively in characterizing damage. However, there exists a sparsity of work in using piezoelectric transducer-generated guided waves as a method of assessing stress intensity factors (SIF). This quantitative information enables accurate estimation of the remaining life of metallic structures exhibiting cracks, such as military and commercial transport vehicles. The proposed full wavefield approach, based on 3D laser vibrometry and piezoelectric transducer-generated guided waves, provides a practical means for estimation of dynamic stress intensity factors (DSIF) through local strain energy mapping via the J-integral. Strain energies …

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Graduate School Of Engineering And Management 2013-2014 Catalog, Graduate School Of Engineering And Management, Air Force Institute Of Technology Jan 2013

Graduate School Of Engineering And Management 2013-2014 Catalog, Graduate School Of Engineering And Management, Air Force Institute Of Technology

AFIT Documents

The Graduate Catalog represents the offerings, programs, and requirements in effect at the time of publication.

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Radar Based Navigation In Unknown Terrain, Kyle J. Kauffman Dec 2012

Radar Based Navigation In Unknown Terrain, Kyle J. Kauffman

Theses and Dissertations

There is a great need to develop non-GPS based methods for positioning and navigation in situations where GPS is not available. This research focuses on the development of an Ultra-Wideband Orthogonal Frequency Division Multiplexed (UWB-OFDM) radar as a navigation sensor in GPS-denied environments. A side-looking vehicle-fixed UWB-OFDM radar is mounted to a ground or aerial vehicle continuously collecting data. A set of signal processing algorithms and methods are developed which use the raw radar data to aide in calculating the vehicle position and velocity via a simultaneous localization and mapping (SLAM) approach. The radar processing algorithms detect strong, persistent, and …

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A Nonparametric Approach To Segmentation Of Ladar Images, Eric A. Buschelman Dec 2012

A Nonparametric Approach To Segmentation Of Ladar Images, Eric A. Buschelman

Theses and Dissertations

The advent of advanced laser radar (ladar) systems that record full-waveform signal data has inspired numerous inquisitions which aspire to extract additional, previously unavailable, information about the illuminated scene from the collected data. The quality of the information, however, is often related to the limitations of the ladar camera used to collect the data. This research project uses full-waveform analysis of ladar signals, and basic principles of optics, to propose a new formulation for an accepted signal model. A new waveform model taking into account backscatter reflectance is the key to overcoming specific deficiencies of the ladar camera at hand, …

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Modeling The Effects Of The Local Environment On A Received Gnss Signal, Marshall E. Haker Dec 2012

Modeling The Effects Of The Local Environment On A Received Gnss Signal, Marshall E. Haker

Theses and Dissertations

There is an ongoing need in the GNSS community for the development of high-fidelity simulators which generate data that replicates what can truly be expected from a challenging environment such as an urban canyon or an indoor environment. The algorithm developed for use in the research in this dissertation, the Signal Decomposition and Parameterization Algorithm (SDPA), is presented in order to respond to this need. This algorithm is designed to decompose a signal received using a GNSS recording and playback system and output parameters that can be used to reconstruct the effects on the signal of the environment local to …

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The Effects Of Observations And Maneuvers On Orbit Solutions, Christine M. Schudrowitz Dec 2012

The Effects Of Observations And Maneuvers On Orbit Solutions, Christine M. Schudrowitz

Theses and Dissertations

The purpose of this research is to characterize the performance of the optimal sequential filter used in ODTK with a maneuvering satellite. Specifically, this thesis sought to characterize the performance using two scenarios: performance with a maneuver in between passes and performance with a limited number of measurements. The performance of the filter is evaluated by analyzing the covariance values generated during the orbit estimation process. Larger covariance values signify reduced performance of the filter. Several variables for the maneuvering satellite are used, including the maneuver direction and the maneuver magnitude. The time of the maneuver is also varied, which …

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Electronic Device, Display And Touch-Sensitive User Interface (Dec 2012), Michael E. Miller, Jerald J. Muszak, Michael J. Telek Dec 2012

Electronic Device, Display And Touch-Sensitive User Interface (Dec 2012), Michael E. Miller, Jerald J. Muszak, Michael J. Telek

AFIT Patents

Display devices and methods for operating the same are provided. In one embodiment, the display device has an electronic display having an active area for presenting visual content; a housing holding the electronic display and having an opening allowing a person to view a first portion of the active area; and a bezel about the opening, the bezel covering a second portion of the active area and providing a window through which at least a part of the second portion can be viewed. A sensor system senses when a person is close to touching the bezel or when a person …

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Predicting The Wear Of High Speed Rocket Sleds, Lauren B. Wuertemberger Dec 2012

Predicting The Wear Of High Speed Rocket Sleds, Lauren B. Wuertemberger

Theses and Dissertations

Holloman Air Force Base houses the 10 mile long Holloman High Speed Test Track (HHSTT) in New Mexico and can run hypersonic experiments at speeds up to 10,000m/s. Tested objects are loaded onto sleds, which are connected to the track by slippers that slide along the rails. The payload sled is propelled down the track by a series of rocket sleds. The ability to predict the wear that will occur on the slippers during these experiments is important for slipper design and preventing catastrophic failure. However, high speeds complicate wear prediction as there additional contributing factors, including inconsistent surface contact, …

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Passive Ranging Using A Dispersive Spectrometer And Optical Filters, Jacob A. Martin Dec 2012

Passive Ranging Using A Dispersive Spectrometer And Optical Filters, Jacob A. Martin

Theses and Dissertations

Monocular passive ranging using atmospheric oxygen absorption has been demonstrated in the past using an FTS. These instruments are very sensitive to vibration making them di cult to use on an airborne platform. This work focuses on whether passive ranging can be done with instruments that are easier to deploy. Two potential instruments are tested and compared: a diffraction grating spectrometer and optical filters. A grating spectrometer was able to estimate range to within 5% for a static solid rocket motor ring at a distance of 910 m using the NIR absorption band of oxygen. Testing at shorter ranges produced …

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