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2010

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Articles 3181 - 3210 of 5382

Full-Text Articles in Engineering

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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Investigation Of Thermal Management And Metamaterials, Calvin T. Roman Mar 2010

Investigation Of Thermal Management And Metamaterials, Calvin T. Roman

Theses and Dissertations

Thermal metamaterials are materials composed of engineered, microscopic structures that exhibit unique thermal performance characteristics based primarily on their physical structures and patterning, rather than just their chemical composition or bulk material properties. The heat transfer performance attributes of a thermal metamaterial are such that similar performance cannot be obtained using conventional materials or compounds. Thermal metamaterials are an emerging technology, and are just now beginning to be acknowledged and developed by the microelectronics and material sciences community. This thesis effort analyzed the current state of thermal metamaterial research, examined the physics and theory of heat transfer and electrical conductivity …

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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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Development Of A Flapping Wing Design Incorporating Shape Memory Alloy Actuation, Jeffrey A. Barrett Mar 2010

Development Of A Flapping Wing Design Incorporating Shape Memory Alloy Actuation, Jeffrey A. Barrett

Theses and Dissertations

This research sought to validate a proof of concept regarding shape memory alloy actuation of a flapping-wing blimp. Specimen wires were subjected to cyclic voltage at increasing frequencies to quantify expected strains. A laser vibrometer captured 2048 sample velocities during single contraction and elongation cycles, and the resulting samples were used to calculate displacements. Displacements were determined ten times for each specimen and frequency to compute averages. Subsequently, a circumventing frame was designed to encase a blimp envelope and provide support for a flapping motion actuation system. Contraction of shape memory wire translated force to the flapping mechanism via bellcranks, …

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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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Thrust And Performance Study Of Micro Pulsed Plasma, Jeremy J. Selstrom Mar 2010

Thrust And Performance Study Of Micro Pulsed Plasma, Jeremy J. Selstrom

Theses and Dissertations

This research is focused on several areas of the μPPT performance. An important idea studied is the effect of lifetime use on the performance. The thruster is fired for a simulated lifetime of use to see if there is an impact on the thrust of the thruster later in life. Also vital is the efficiency of the thruster. A μPPT performing at max efficiency will ionize all ablated material; however, we know that not to be the case. In this research the effort is made to collect these non-ionized particles in order to measure their mass post-test. With this collected …

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Dive Angle Sensitivity Analysis For Flight Test Safety And Efficiency, Matthew T. Schneider Mar 2010

Dive Angle Sensitivity Analysis For Flight Test Safety And Efficiency, Matthew T. Schneider

Theses and Dissertations

Flutter envelope expansion is one of the most critical types of developmental flight tests. The regions that present the most dangerous flight profiles are those test points in the negative PS realm of the flight envelope. These points develop into high-speed dives and require an accurate predictive model to prevent possible testing accidents. As a flight test is conducted, several conditions such as aircraft weight and ambient air temperature can change, causing a drastic shift in the excess power profiles resulting in significant alteration in the test conditions. Using a dive planning model, a number of parameters were analyzed to …

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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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Cfd Analysis Of Experimental Wing And Winglet For Falconlaunch 8 And The Exfit Program, Benjamin P. Switzer Mar 2010

Cfd Analysis Of Experimental Wing And Winglet For Falconlaunch 8 And The Exfit Program, Benjamin P. Switzer

Theses and Dissertations

Reusable launch vehicles have many benefits over their expendable counterparts. These benefits range from cost reductions to increased functionality of the vehicles. Further research is required in the development of the technology necessary for reusable launch vehicles to come to fruition. The Air Force Institute of Technology’s future involvement in the ExFIT program will entail designing and testing of a new wing tip mounted vertical stabilizer in the hypersonic regime. One proposed venue for experimentation is to utilize the United States Air Force Academy’s FalconLAUNCH Program which annually designs, builds, and launches a sounding rocket capable of reaching hypersonic speeds. …

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Relative Orbit Elements For Satellites In Elliptical Orbits, Kirk W. Johnson Mar 2010

Relative Orbit Elements For Satellites In Elliptical Orbits, Kirk W. Johnson

Theses and Dissertations

The purpose of this research was to describe the unperturbed relative motion of Earth satellites in elliptical orbits using a simple dynamics model whose parameters allow significant geometrical insight and operational efficacy. The goal was to retain the advantages of the Relative Orbit Elements (ROE) realization of the Hill-Clohessy-Wiltshire (HCW) equations, a linearized dynamics model for circular reference orbits. Specifically, this thesis analyzed the geometry of satellite rendezvous and proximity operations using the ROE parameters to characterize the model’s utility. Next, through a comprehensive literature review, this thesis sought possible approaches for developing a similarly useful parameterization for chief orbits …

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Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller Mar 2010

Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller

Theses and Dissertations

This research effort develops an interdisciplinary design tool to optimize an orbit for the purpose of wirelessly beaming power from the International Space Stations (ISS) Japanese Experimental Module Exposed Facility (JEM/EF) to a target satellite. For the purpose of this initiative, the target satellite will be referred to as FalconSAT6, a reference to the proposed follow-on satellite to the U.S. Air Force Academy’s (USAFA) FalconSAT5 program. The USAFA FalconSAT program provides cadets an opportunity to design, analyze, build, test and operate small satellites to conduct Department of Defense (DoD) space missions. The tool developed for this research is designed to …

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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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Methods To Streamline Laminate Composite Design, Analysis, And Optimization, Ammon Ikaika No Kapono Hepworth Mar 2010

Methods To Streamline Laminate Composite Design, Analysis, And Optimization, Ammon Ikaika No Kapono Hepworth

Theses and Dissertations

Advanced composite materials have seen major market growth in recent years due to their high strength and low weight properties. These materials are often made using a process that creates a composite laminate by stacking several composite layers together. However, the design, analysis and optimization of laminate composite materials are often a labor intensive process when done manually. This thesis discusses CAD independent algorithms that are integrated into commercial CAD tools to streamline these processes. Methods have been developed to automatically create 3D ply geometry for a laminate composite lay-up, streamline the creation of a laminate composite finite element model …

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Evidence Based Evaluation Research In Engineering, Kevin Kelly Mar 2010

Evidence Based Evaluation Research In Engineering, Kevin Kelly

Other resources

No abstract provided.

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Isolated Cellulose Synthase Promoter Regions, Chandrashekhar P. Joshi Mar 2010

Isolated Cellulose Synthase Promoter Regions, Chandrashekhar P. Joshi

Michigan Tech Patents

The invention relates to methods of inducing expression of coding sequences including cellulose synthase coding sequences in transgenic plants using promoters of cellulose synthase genes from Populus plant species and transgenic plants produced by the methods.

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Integrating Engineering And Communication Tools For The Automation Of Design Rationale Capture, Kenneth John Mix Mar 2010

Integrating Engineering And Communication Tools For The Automation Of Design Rationale Capture, Kenneth John Mix

Theses and Dissertations

Product development is continually becoming more challenging as global competition requires more efficient design methods. The reuse of company knowledge, specifically the design rationale that occurs during projects is essential to success. This thesis presents a method for integrating engineering and communication tools for purposes of automating the capture of communication-based design rationale. The method is based on four basic principles: to integrate, to make data retrievable, to minimize user interaction, and to store as much DR as possible. The core method consists of two primary operations, the first being to capture the design rationale, and the second being to …

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Service-Differentiated And Reliable Communication In Event-Based Wireless Sensor Networks, Yuyan Xue Mar 2010

Service-Differentiated And Reliable Communication In Event-Based Wireless Sensor Networks, Yuyan Xue

School of Computing: Dissertations, Theses, and Student Research

Wireless Sensor Networks (WSNs) consist of low-power embedded devices with integrated sensing, computing and wireless communication capabilities. These devices, called sensor nodes or motes, are often battery-powered and deployed in a distributed manner to provide observations on the physical world. Reliably and promptly collecting the sensing data to convey the features of a surveillance area, especially the events of interest, to the sink is one of the most critical requirements of WSN design. However, dynamic wireless channel conditions and the constrained energy resources make it a challenging task to provide the end-to-end performance guarantees in multi-hop WSNs. The objective of …

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Digital Delay Device, Guna Seetharaman, Paul E. Kladitis Mar 2010

Digital Delay Device, Guna Seetharaman, Paul E. Kladitis

AFIT Patents

A digitally controlled optical delay apparatus providing optical signal delays electrically selectable in the picosecond to nanosecond range by way of selectable signal path lengths. Path lengths are incremented in physical length and path delay time according to digital ratios. The delay element includes micro-miniature path changing mirrors controlled in path length selecting positioning by input signals of logic level magnitude. Fiber optic coupling of signals to and from the delay element and a combination of fixed position and movable mirror included optical signal path lengths are included.

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Multi-Aperture Coherent Change Detection And Interferometry For Synthetic Aperture Radar, David D. Madsen Mar 2010

Multi-Aperture Coherent Change Detection And Interferometry For Synthetic Aperture Radar, David D. Madsen

Theses and Dissertations

Interferometry and coherent change detection (CCD) utilize phase differences between complex SAR images to find terrain height and to detect small changes between images, respectively. A new method for improving interferometry and CCD using multiple sub-apertures is proposed. Using backprojection processing, multiple sub-aperture images are created for a pair of flights. An interferogram and coherence map is made from each sub-aperture. For CCD, each sub-aperture coherence map offers an independent estimate of the coherence over the same area. By combining coherence maps, low coherence areas associated with residual motion errors are reduced, shadowed areas are minimized, and the overall coherence …

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Design And Evaluation Of A Humanoid Robot For Autism Therapy, Daniel J. Ricks Mar 2010

Design And Evaluation Of A Humanoid Robot For Autism Therapy, Daniel J. Ricks

Theses and Dissertations

Recent evidence has shown that children with autism may behave more pro-socially when interacting with a robot than with a human. The objective of this research is to develop a robotic system for use in the clinical treatment of children with autism. The governing assumption behind this thesis is that using a robot in a clinic, under the guidance of a trained therapist, may lead to therapeutic benefits that may not be achieved without the presence of the robot. The robot Troy was developed to fulfill such a role in a clinical setting. The primary objective was to design a …

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Strain-Induced, Off-Diagonal, Same-Atom Parameters In Empirical Tight-Binding Theory Suitable For [110] Uniaxial Strain Applied To A Silicon Parametrization, Timothy B. Boykin, Mathieu Luisier, Mehdi Salmani-Jelodar, Gerhard Klimeck Mar 2010

Strain-Induced, Off-Diagonal, Same-Atom Parameters In Empirical Tight-Binding Theory Suitable For [110] Uniaxial Strain Applied To A Silicon Parametrization, Timothy B. Boykin, Mathieu Luisier, Mehdi Salmani-Jelodar, Gerhard Klimeck

Birck and NCN Publications

State-of-the-art transistors achieve their improved performance through strain engineering. The somewhat unusual uniaxial [110] strain is of particular importance as it provides a significant mobility increase for electrons. Empirical tight binding has shown tremendous benefits in modeling realistically large structures including standard strain conditions, but often fails to predict the correct uniaxial [110] strain behavior because most treatments neglect the same-atom different-orbital matrix elements induced by this strain. Two separate mechanisms are responsible for these conditions: Loumlwdin orbital changes and displacement of nearest-neighbor potentials. We present a model which separately includes both mechanisms via parameters whose range of validity can …

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Study Of Physical Layer Security In Wireless Communications, Mustafa Duruturk Mar 2010

Study Of Physical Layer Security In Wireless Communications, Mustafa Duruturk

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

This thesis has investigated security in wireless communications at physical layer. Security is an important issue for wireless communications and poses many challenges. Most security schemes have been applied to the upper layers of communications networks. Since in a typical wireless communication, transmission of data is over the air, third party receiver(s) may have easy access to the transmitted data. This work discusses a new security technique at the physical layer for the MIMO (802.11n) transmitters. For this project, the wireless medium is secured by transmitting a noise signal that is only recoverable by the receiver. This report includes an …

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Mercury In The Environment: Field Studies From Tampa, Bolivia, And Guyana, Joniqua A'Ja Howard Mar 2010

Mercury In The Environment: Field Studies From Tampa, Bolivia, And Guyana, Joniqua A'Ja Howard

USF Tampa Graduate Theses and Dissertations

Tampa (US), Guyana (SA), and Bolivia (SA), are geographically, socially, economically, and politically unique which make them ideal sites to study issues of mercury and sustainability. Mercury’s innate ability to bioaccumulate and biomagnify in aquatic and terrestrial ecosystems poses a severe threat to both human and environmental health. The most vulnerable populations affected by mercury consumption include coastal communities, children, women of child-bearing age, the indigenous poor and persons with high environmental/occupational exposure factors. Communities in the regions of Florida, Bolivia, and Guyana whose diets are high in fish and are environmentally/occupationally exposed to mercury may be at a higher …

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Ceas E-News 03.04.2010, College Of Engineering And Applied Sciences Mar 2010

Ceas E-News 03.04.2010, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Engineers' Week serves up food, fun, and a glimpse into the future

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Average Run Length Of Two-Span Moving Sum Algorithms, Swarnendu Kar, Kishan G. Mehrotra, Pramod Varshney Mar 2010

Average Run Length Of Two-Span Moving Sum Algorithms, Swarnendu Kar, Kishan G. Mehrotra, Pramod Varshney

Electrical Engineering and Computer Science - All Scholarship

Among the various procedures used to detect potential changes in a stochastic process the moving sum algorithms are very popular due to their intuitive appeal and good statistical performance. One of the important design parameters of a change detection algorithm is the expected interval between false positives, also known as the average run length (ARL). In this paper, we have derived closed form expressions of ARL for two special cases - namely the two-span moving sum and filtered derivative algorithms. We have assumed that the random variables are uniformly distributed.

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North American Standard For Cold-Formed Steel Framing -- Lateral Design, 2007 Edition With Supplement No 1. October 2009 (Reaffirmed 2012), American Iron And Steel Institute Mar 2010

North American Standard For Cold-Formed Steel Framing -- Lateral Design, 2007 Edition With Supplement No 1. October 2009 (Reaffirmed 2012), American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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