Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Electrical and Computer Engineering (15382)
- Mechanical Engineering (13558)
- Civil and Environmental Engineering (12908)
- Physical Sciences and Mathematics (8363)
- Computer Engineering (6519)
-
- Materials Science and Engineering (6132)
- Chemical Engineering (6092)
- Aerospace Engineering (6019)
- Biomedical Engineering and Bioengineering (5510)
- Civil Engineering (5395)
- Operations Research, Systems Engineering and Industrial Engineering (4926)
- Electrical and Electronics (3941)
- Computer Sciences (3092)
- Environmental Engineering (2955)
- Industrial Engineering (2137)
- Construction Engineering and Management (1976)
- Physics (1806)
- Engineering Science and Materials (1753)
- Power and Energy (1580)
- Operational Research (1484)
- Life Sciences (1481)
- Social and Behavioral Sciences (1440)
- Manufacturing (1422)
- Metallurgy (1402)
- Environmental Sciences (1304)
- Medicine and Health Sciences (1242)
- Nanoscience and Nanotechnology (1242)
- Other Engineering (1196)
- Electromagnetics and Photonics (1119)
- Institution
-
- California Polytechnic State University, San Luis Obispo (6016)
- Missouri University of Science and Technology (5428)
- Air Force Institute of Technology (5109)
- New Jersey Institute of Technology (4158)
- University of Central Florida (3949)
-
- University of Texas at Arlington (2996)
- Chulalongkorn University (2554)
- Brigham Young University (2438)
- Louisiana State University (2431)
- University of Arkansas, Fayetteville (2270)
- Clemson University (2261)
- Old Dominion University (2225)
- Utah State University (1607)
- University of New Mexico (1533)
- University of South Florida (1499)
- University of Kentucky (1479)
- Wright State University (1369)
- University of Texas at El Paso (1323)
- Michigan Technological University (1213)
- Embry-Riddle Aeronautical University (1098)
- University of South Carolina (1092)
- Santa Clara University (926)
- Purdue University (904)
- Portland State University (886)
- Western Michigan University (874)
- The University of Akron (835)
- Washington University in St. Louis (829)
- West Virginia University (784)
- Montana Tech Library (736)
- University of Nevada, Las Vegas (704)
- Keyword
-
- Applied sciences (1096)
- Optimization (666)
- Machine learning (665)
- Machine Learning (604)
- Engineering (559)
-
- Simulation (537)
- Modeling (423)
- Design (357)
- Sustainability (353)
- Daniel Felix Ritchie School of Engineering and Computer Science (336)
- CFD (321)
- Department of Computer Science and Engineering (320)
- Additive manufacturing (310)
- Robotics (310)
- #antcenter (293)
- Additive Manufacturing (293)
- Mechanical Engineering (291)
- Deep learning (279)
- Department of Mechanical and Materials Engineering (274)
- Deep Learning (269)
- Department of Electrical Engineering (269)
- Montana (265)
- Concrete (260)
- Construction (259)
- Nanoparticles (255)
- Doctor of Philosophy (PhD) School of Engineering (244)
- Computer Science (242)
- Computer vision (235)
- Manufacturing (235)
- UAV (232)
- Publication Year
- Publication
-
- Theses and Dissertations (11532)
- Electronic Theses and Dissertations (4149)
- Masters Theses (3922)
- Theses (3498)
- Chulalongkorn University Theses and Dissertations (Chula ETD) (2554)
-
- Master's Theses (2028)
- Doctoral Dissertations (1811)
- Dissertations (1650)
- USF Tampa Graduate Theses and Dissertations (1499)
- Browse all Theses and Dissertations (1369)
- Open Access Theses & Dissertations (1323)
- LSU Master's Theses (1308)
- All Theses (1247)
- Graduate Theses and Dissertations (1238)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (1187)
- Dissertations and Theses (1105)
- All Dissertations (1006)
- LSU Doctoral Dissertations (997)
- Construction Management (995)
- Mechanical Engineering (835)
- Williams Honors College, Honors Research Projects (835)
- Doctoral Dissertations and Master's Theses (827)
- Retrospective Theses and Dissertations (811)
- Mechanical & Aerospace Engineering Theses & Dissertations (790)
- McKelvey School of Engineering Graduate Student Theses & Dissertations (785)
- Graduate Theses, Dissertations, and Problem Reports (ETD) (783)
- Dissertations, Master's Theses and Master's Reports (738)
- UNLV Theses, Dissertations, Professional Papers, and Capstones (698)
- Mechanical and Aerospace Engineering Theses - Archive (688)
- Honors Theses (670)
- File Type
Articles 68281 - 68310 of 77841
Full-Text Articles in Engineering
Investigation Of Aerodynamic Alterations For Improving The Kc-135 Boom Performance During Aerial Refueling, Debra A. Nawrocki
Investigation Of Aerodynamic Alterations For Improving The Kc-135 Boom Performance During Aerial Refueling, Debra A. Nawrocki
Theses and Dissertations
This study investigated the eligibility of the KC-135 air refueling boom for improved capabilities in the areas of control and performance. By using a thick airfoil cross-section for the boom tube, rather than the current circular cross-section, the ability to increase the lift characteristics was verified Prior compiled test data was used for comparison against analytical computer solutions. The possibility and effects of control frequency oscillations were also examined due to the unstable nature of the flow at test conditions. Additionally, the effect of other cross-section shapes, such as the blunt fairing, on the size of the flyable envelope for …
Methodology For Implementing Fracture Mechanics In Global Structural Design Of Aircraft, Clifton D. Nees
Methodology For Implementing Fracture Mechanics In Global Structural Design Of Aircraft, Clifton D. Nees
Theses and Dissertations
The analysis and design criteria of fracture mechanics are investigated for implementation with the Automated Structural Optimization System (ASTROS) global optimization design tool. The main focus is the optimal design of aircraft wing panels by applying fracture mechanics design criteria within the global finite element model. This effort consists of four main phases: investigation of fracture mechanics analysis methods and design criteria, formulation of a computational technique for damage tolerance design consistent with global optimization requirements, integration of the technique into the ASTROS design tool, and demonstration of the results.
Influence Of A Moving Endwall On The Tip Clearance Vortex In An Axial Compressor Cascade, Lawrence J. Peter
Influence Of A Moving Endwall On The Tip Clearance Vortex In An Axial Compressor Cascade, Lawrence J. Peter
Theses and Dissertations
This experiment involved the design, construction, validation and testing of a new facility for the investigation of vortices generated by compressor rotor blade tip clearance with a moving endwall. A five-tube pressure rake placed downstream of the trailing edge of a cascade of blades measured the pressure field for flow coefficients ranging from 20 to 1.66 and tip clearances of 0.33, 1.0, 1.7 and 2.4 percent chord. Contour plots of mass averaged pressure loss coefficient appear to show the no-flow tip vortex becomes entrained and diffused by the moving wall boundary layer. The high loss region near the moving wall …
Frequency Effects On Fatigue Behavior Of A Unidirectional Metal Matrix Composite At Elevated Temperature, Robert N. Pittman
Frequency Effects On Fatigue Behavior Of A Unidirectional Metal Matrix Composite At Elevated Temperature, Robert N. Pittman
Theses and Dissertations
The fatigue response and life of a unidirectional SCS-6/Ti-6-4 metal-matrix composite were examined under tension-tension, load-controlled conditions at elevated temperatures and different frequencies. Composite specimens were fatigued at frequencies of 0.01, 0.1, 1 and 10 Hz, and at three stress levels. Plots of cycles to failure versus maximum stress and test frequency showed that fatigue life was more cycle-dependent at higher frequencies and more time-dependent at lower frequencies. Comparisons of tests at 427°C with their counterparts at 370°C and 538°C showed that these frequency effects were magnified as temperature increased: lower frequency tests at 538°C exhibited greater time-dependence than tests …
Prediction Of An Axial Compressor Stage Characteristic From A One-Point Measurement, Shahnaz M. Punjani
Prediction Of An Axial Compressor Stage Characteristic From A One-Point Measurement, Shahnaz M. Punjani
Theses and Dissertations
This study focuses on predicting axial compressor stage characteristics using a single performance point comprised of mass flow, temperature and pressure rise coefficients obtained in experimental testing and a generic stage temperature characteristic. A new temperature characteristic is generated using a mapping technique where changes in stage blade angles are iterated from assumptions of free vortex flow and constant increment of flow turning angle with increased flow incidence. If additional data corresponding to the new curve are available, the characteristic is adjusted using non-linear least squares estimation, Essentially, the modified mapped curve results from a re-estimated change in the stator …
Experimental Investigation Of Non-Adiabatic Supersonic Slot Injection Into A Supersonic Cross-Flow, Kelly C. Tucker
Experimental Investigation Of Non-Adiabatic Supersonic Slot Injection Into A Supersonic Cross-Flow, Kelly C. Tucker
Theses and Dissertations
Turbulence and mean flow measurements were acquired downstream of a normal, supersonic (M=1.6), two-dimensional, slot injection into Mach 3.0 flow (Re/m = 15x106). Two non-adiabatic cases Ti/T∞ = 1.11 and Ti/T∞ = 0.93) were studied. Multiple overheat anemometry and conventional mean flow analysis, as well as shadowgraph and schlieren photography, were utilized to study the turbulent mixing layer. The mean flow data included the Pitot, cone-static, and Mach number profiles. The measured turbulence data included shear stresses, mass flux, total temperature turbulence intensities, and turbulent heat fluxes. The temperature and density variation …
Compressible Turbulence Measurement In The Mixing Layer Of An Adiabatic Normal Slot Injection Into Supersonic Flow, Christopher D. Whitcomb
Compressible Turbulence Measurement In The Mixing Layer Of An Adiabatic Normal Slot Injection Into Supersonic Flow, Christopher D. Whitcomb
Theses and Dissertations
In this study mean flow and compressible turbulence measurements were taken at a station x = 72W downstream of the injection, where W is the injector throat width, of an adiabatic 2-D Mach 1.6 normal slot injection into a Mach 2.9 flow. Data were collected using a conventional Pitot probe, a cone-static probe, and multiple overheat cross-wire anemometry. In addition, schlieren and shadowgraph flow visualization was used to investigate the flow structure at both the injection point and at the downstream data collection point. From these measurements, mass flux component turbulence intensities of 8% to 10% were seen. The total …
Effects Of Base Cavity Depth On A Free Spinning Wrap-Around Fin Missile Configuration, Jon A. Struck
Effects Of Base Cavity Depth On A Free Spinning Wrap-Around Fin Missile Configuration, Jon A. Struck
Theses and Dissertations
This study investigated the role base cavity depth plays in altering the overall subsonic aerodynamic forces on a free spinning axisymmetric body with wrap around fins. Wind tunnel usage allowed the forces to be monitored for varying base cavity depths and angles of attack. A base cavity depth analysis was also performed on a non-spinning axisymmetric body for comparison. Oil visualizations were conducted on the non-spinning configuration to further describe airflow patterns around the body and within the cavity. Results revealed that the aerodynamic forces, mostly drag, changed with increasing cavity depth but not to the extent previously believed. The …
Fatigue Response Of Cracked Aluminum Panel With Partially Bonded Composite Patch, Jason J. Denney
Fatigue Response Of Cracked Aluminum Panel With Partially Bonded Composite Patch, Jason J. Denney
Theses and Dissertations
More and more aircraft, both commercial and military, are being called upon to fly well beyond their economic and structural service lives. Budget cuts and dwindling new aircraft development has forced the United States Air Force (USAF) to look toward more reliable structural repairs. One of these repair techniques, which was the subject of this study, is the repair of metallic aircraft structures using high strength composite materials. This study investigated the fatigue response of a precracked, 508x1 52x1 mm, 2024-T3 aluminum panel repaired with a partially bonded, unidirectional, three-ply boron/epoxy composite reinforcement with ply lengths of 68, 56 and …
Numerical Study Of A Transpiration Cooled Rocket Nozzle, Jay A. Landis
Numerical Study Of A Transpiration Cooled Rocket Nozzle, Jay A. Landis
Theses and Dissertations
This study proved that transpiration cooling provides a better cooling scheme than regenerative cooling for long operating duration, liquid-fueled rocket engine nozzles. This proof was made on the basis of maximum wall temperature. This study compared transpiration cooling to regenerative cooling in the throat region of the Space Shuttle Main Engine Main Combustion Chamber. The study also analyzed the effects of porosity, solid thermal conductivity, and porous sphere size on a porous wall made of packed spheres. The transpiration cooled nozzle operated 35% cooler than a regeneratively cooled nozzle, but the temperature gradient at the hot gas surface was 72 …
Sub-Optimal Control Of Rigid Spacecraft Reorientation Using Three Momentum Wheels, Gregory W. Schultz
Sub-Optimal Control Of Rigid Spacecraft Reorientation Using Three Momentum Wheels, Gregory W. Schultz
Theses and Dissertations
This thesis addresses sub-optimal employment of 3 momentum wheels for large angle reorientation of rigid spacecraft with minimal induced spacecraft motion during maneuvers. In addition to development of general theory for 3 wheel vehicles, simulation results for a vehicle using momentum wheels for secondary attitude control (GPS Block IIR) are compared to results for a vehicle using them for primary attitude control (the Hubble Space Telescope), to demonstrate practical applications and limitations. While the control laws were developed assuming no external perturbing torques on the vehicle, reorientation scenarios were run both in a torque free environment as well as an …
Applications Of Nonlinear Control Using The State-Dependent Riccati Equation, David K. Parrish
Applications Of Nonlinear Control Using The State-Dependent Riccati Equation, David K. Parrish
Theses and Dissertations
This thesis examines the relatively new theory of nonlinear control using state dependent coefficient factorizations to mimic linear state space systems. The control theory is a nonlinear quadratic approach, analogous to linear quadratic regulation. All implementations examined in this thesis are done strictly numerically. This thesis is meant to provide a proof of concept for both satellite control and for an artificial pancreas to regulate blood glucose levels in diabetics by automatic insulin injection. These simulations represent only a first step towards practical use of the NQR method, and do not address noise rejection or robustness issues.
Electrical Characterization Of 4h-Silicon Carbide P-N Junction Diodes, Michael E. Dunn
Electrical Characterization Of 4h-Silicon Carbide P-N Junction Diodes, Michael E. Dunn
Theses and Dissertations
The current conduction mechanisms of 4H-SiC p+n mesa diodes were studied using current-voltage-temperature (I-V-T), capacitance-voltage-temperature (C-V-T), deep level transient spectroscopy (DLTS), optical observations, and reverse breakdown measurements. Temperature and voltage dependencies of diffusion, recombination, and tunneling current processes are shown to be consistent with Sah-Noyce-Shockley theory. Recombination currents having an ideality factor of A=1.85-2.1 yielded an activation energy of EA=1.56 eV, whereas for ideal recombination, A=2 and EA=1.6 eV. Forward I-V curves of poor diodes dominated by tunneling and recombination processes, showing low reverse breakdown voltages of approx. 100 V, can be correlated to DLTS results …
Electrical Characterization Of 4h-And 6h-Silicon Carbide Schottky Diodes, Jeffrey C. Wiemeri
Electrical Characterization Of 4h-And 6h-Silicon Carbide Schottky Diodes, Jeffrey C. Wiemeri
Theses and Dissertations
The electrical properties of silicon carbide (SiC) make it an excellent candidate for use in high temperature/high power devices due to its wide bandgap, high breakdown field, high electron mobility, etc. In this work two Schottky diodes of platinum (Pt) on n-type carbon faced 4H-SiC and three Schottky diodes of nickel (Ni) on n-type silicon faced 6H-SiC were electrically characterized. The diodes exhibited good performance up to 698 K for both the forward and reverse (up to -100v) bias voltages. The barrier heights measured by I-V-T tests were found to be 0.32 and 0.61 eV for the Pt/4H-SiC samples, but …
The Automated Wingman: An Airborne Companion For Users Of Dis Compatible Flight Simulators, Mark M. Edwards
The Automated Wingman: An Airborne Companion For Users Of Dis Compatible Flight Simulators, Mark M. Edwards
Theses and Dissertations
A major problem encountered by users of distributed virtual environments is the lack of simulators available to populate these environments. This problem is usually remedied by using computer generated entities. Unfortunately, these entities often lack adequate human behavior and are readily identified as non-human. This violates the realism premise of distributed virtual reality and is a major problem, especially in training situations. This thesis addresses the problem by presenting a computer generated entity called the Automated Wingman. The Automated Wingman is a semi-automated computer generated aircraft simulator that operates under the control of a designated lead simulator and integrates distributed …
An Architecture For Dynamic Meta-Level Process Control For Model-Based Troubleshooting, John E. Friskie
An Architecture For Dynamic Meta-Level Process Control For Model-Based Troubleshooting, John E. Friskie
Theses and Dissertations
There are numerous methods used for troubleshooting devices. Each method has certain domains, knowledge requirements, and assumptions required for it to perform well. However, oftentimes no one method by itself is sufficient to completely solve a troubleshooting problem. Therefore, an architecture is required to control the combined use of many problem solving methods. The combination of multiple problem solving methods makes the troubleshooting process more robust in terms of device domains that can be dealt with and quality of diagnoses produced. Troubleshooting has two tasks: diagnosis and problem resolution. This research provides an architecture that allows dynamic method selection during …
Design, Fabrication, Processing, And Testing Of Micro-Electro-Mechanical Chemical Sensors, Brian S. Freeman
Design, Fabrication, Processing, And Testing Of Micro-Electro-Mechanical Chemical Sensors, Brian S. Freeman
Theses and Dissertations
Chemical microsensors are a new field integrating chemical thin film technology with solid-state fabrication techniques to make devices capable of detecting chemicals in the environment. This thesis evaluated commercially available fabrication processes and numerous sensor designs for working chemical sensors. The commercial processes used were MUMPS for surface micromachined devices and MOSIS for bulk micromachined devices. Overall, eight fabrication runs and 29 different designs were made. Of these designs, two were shown to work effectively. Other designs failed due to fabrication problems and design errors that caused release problems. One design that worked was a surface micromachined chemoresistor with interdigitated …
Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo
Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo
Theses and Dissertations
Observations of the spatial variability of hydraulic conductivity of the heterogeneous alluvial aquifer at Columbus Air Force Base in Mississippi are analyzed using parametric geostatistical approaches. Field studies have revealed that the heterogeneity of the aquifer hydraulic conductivity field controls the movement and dispersion of groundwater solutes. Therefore, a means of quantifying spatial variability is essential for the application of flow and solute transport models to practical problems. Application of these models requires a large number of hydraulic conductivity measurements. Geostatistical analysis and kriging estimation procedures assist in providing these large numbers of values when sampling designs have provided sparse …
Validation Of Operational Multiscale Environment Model With Grid Adaptivity (Omega), Gordon R. Taylor
Validation Of Operational Multiscale Environment Model With Grid Adaptivity (Omega), Gordon R. Taylor
Theses and Dissertations
The Defense Nuclear Agency (DNA) is improving the military's capability to forecast dosage and hazard levels due to release of chemical, biological, and nuclear agents. During Operation DESERT STORM the military realized the need for models to predict risk levels for military personnel assigned proximate to missile attacks. One project associated with this is the continuing development of the Operational Multiscale Environmental Model with Grid Adaptivity (OMEGA). DNA has sponsored AFIT to validate OMEGA with focus on incorporating weather data obtained from Air Force Combat Climatology Center for the period of the Chernobyl Nuclear Accident. The physics of the model …
The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann
The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann
Theses and Dissertations
Explosive Ordnance Disposal (EOD) Open Burning (OB) operations are performed to treat and dispose of unserviceable munitions in the Department of Defense (DOD) inventory. Air pollution modeling of OB operations is an Environmental Protection Agency requirement for permit issuance at OB sites. Specific OB regulation is still in its infancy; therefore, establishment of OB modeling techniques is still in the early stages. This thesis effort sought to develop a computer model, based upon the Gaussian Puff Equation. The model varies from standard plume modeling practices by not making the assumption that the wind direction, wind speed and turbulence are uniform …
A Decision Tool To Optimally Select Pollution Prevention Projects Within A Constrained Budget, Charlotte Hudson
A Decision Tool To Optimally Select Pollution Prevention Projects Within A Constrained Budget, Charlotte Hudson
Theses and Dissertations
Pollution prevention managers need to select the best environmental projects for an installation within a constrained budget but have no standard way of selecting the optimal mix of projects. This thesis proposes a decision tool to aid decision makers in choosing this optimal mix. The model was built using decision analysis theory which provides a framework to aid the decision maker. Criteria sed in the model for selection was determined using a questionnaire sent to base-level pollution prevention managers. The model ses DPL, a software package designed to build, analyze, and conduct sensitivity analysis of decision problems to perform the …
In Situ Warming And Soil Venting To Enhance The Biodegradation Of Jp-4 In Cold Climates: A Critical Study And Analysis, Ricky D. Cox
In Situ Warming And Soil Venting To Enhance The Biodegradation Of Jp-4 In Cold Climates: A Critical Study And Analysis, Ricky D. Cox
Theses and Dissertations
Numerous bioremediation projects have proven effective in accelerating contaminant biodegradation by injecting oxygen into the vadose zone with a technique called bioventing. In cold climates, bioremediation is limited to the summer when soil temperatures are sufficient to support microbial growth. Laboratory studies directly correlate increased biodegradation rates with temperature. By raising soil temperatures, in situ jet fuel remediation can be accelerated which was shown by a bioventing project conducted in 1991 at Eielson AFB, Alaska, where three soil warming techniques were used. Two methods actively warmed the soil - warm water circulation and heat tape; the other passively warmed the …
Validation Testing A Contaminant Transport And Natural Attenuation Simulation Model Using Field Data, Steven J. Flier
Validation Testing A Contaminant Transport And Natural Attenuation Simulation Model Using Field Data, Steven J. Flier
Theses and Dissertations
This research extends the work begun by Enyeart (1994) which evaluated the process of intrinsic bioremediation, and which developed a model for predicting the velocity of an aerobic degradation front, as it traverses the length of a JP-4 contaminant plume. It is assumed this aerobic front will traverse the contaminant plume as dissolved oxygen is carried by the ground water through the sorption-retarded contaminant. The ultimate purpose of Enyeart's model is to use it to develop field guidance for assessing the feasibility of intrinsic bioremediation to restore petroleum-contaminated soils. After simulating intrinsic bioremediation many times with a spreadsheet model, results …
A Comparison Of Remediation Priorities Developed By The Defense Priority Model, The Relative Risk Evaluation Method, And A Quantitative Risk Assessment Approach, David M. Hunter
Theses and Dissertations
The Superfund, established by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, seriously underestimated both the number of severely contaminated sites and the associated cleanup cost. The magnitude of projected cleanup costs, coupled with shrinking federal budgets, necessitated the development and use of risk-based prioritization models among some federal agencies. Among these tools, the DOD prioritization models are meant to give priority to sites posing the greatest threat to human health. Their failure to properly rank sites could incorrectly shift the focus from those that pose substantial risk to sites of lesser risk. The DOD site ranking …
A Comparison Of Response Surface Methodology And A One-Factor-At-A-Time Approach As Calibration Techniques For The Bioplume-Ii Simulation Model Of Contaminant Biodegradation, Benjamin Shuman
Theses and Dissertations
This thesis compared Response Surface Methodology (RSM) to the one-factor-at-a-time approach for calibrating the Bioplume-II simulation model of contaminant biodegradation. The MADE-2 data set from Columbus Air Force Base, Mississippi was used. The one-factor-at-a-time approach reduced the root-mean-squared (RMS) error for the flow to 0.921225 feet in a total of 36 runs of Bioplume-II. The RSM approach reduced the error criterion to 0.918875 in a total of 47 runs. The one-factor-at-a-time approach was unable to reduce the error below 67.1831 parts per billion (ppb) after 21 runs. The RSM approach reduced the RMS error to 67.0327 ppb after 47 runs. …
Evaluation Of The Sensitivity Of Radar Cross Section Predictions To Uncertainties In Material Characteristics, Greg A. Barnhart
Evaluation Of The Sensitivity Of Radar Cross Section Predictions To Uncertainties In Material Characteristics, Greg A. Barnhart
Theses and Dissertations
The purpose of this study was to evaluate the effects of material characteristics uncertainties on Radar Cross Section (RCS) predictions. Many methods have been developed to predict the RCS of metal objects, but for material coated objects, these methods depend on the accuracy of measured material characteristics. Material characteristics of three dielectrics were measured by two separate X-band waveguide set-ups. RCS measurements were then made to evaluate the accuracy of RCS predictions using these measured material characteristics. A six inch square slab of each material was measured with and without a metal plate backing. A six inch square flat metal …
A Differential Gps Aided Ins For Aircraft Landings, Ryan L. Britton
A Differential Gps Aided Ins For Aircraft Landings, Ryan L. Britton
Theses and Dissertations
The Department of Defense (DOD) and the commercial airline industry are in the process of replacing the instrument landing system (ILS) for aircraft precision approach landings. The use of differential Global Positioning System (DGPS) is thought to be a viable replacement for ILS precision approaches. This thesis explores the integration of an INS, DGPS, Barometric Altimeter, Pseudolite, and Radar Altimeter for a tanker type and a single engine aircraft precision approach. These devices are integrated using an extended Kalman filter (EKF). For the tanker type aircraft federal Aviation Administration (FAA) requirements for a Category I and a Category II precision …
Velocity Determination For An Inverted Pseudolite Navigation Reference System, Jeffrey M. Hebert
Velocity Determination For An Inverted Pseudolite Navigation Reference System, Jeffrey M. Hebert
Theses and Dissertations
As navigation systems continue to improve in performance and features, the Air Force must develop better Navigation Reference Systems (NRS) to keep pace with technology. Specifically, with the advent of enhanced, integrated Global Positioning System (GPS) and Inertial Navigation System (INS) navigators, emphasis is placed on the measuring performance in the presence of GPS jamming. To meet these needs, a new NRS, dubbed the Sub-Meter Accuracy Reference System (SARS), is being developed by the 746th Test Squadron, Holloman AFB, New Mexico. SARS uses a unique, inverted GPS pseudolite positioning system to determine a reference trajectory. This research investigates two post …
Design And Fabrication Of A Micromechanical Gyroscope, Richard M. Kuhns
Design And Fabrication Of A Micromechanical Gyroscope, Richard M. Kuhns
Theses and Dissertations
Both size and cost of mechanical and optical inertial navigation systems (INS) have prevented their use in many applications. By developing a micromachined gyroscope and combining it with existing micromachined accelerometer designs to form a low sensitivity INS, the cost would be reduced by a factor of 10 or more. The lower per unit cost would open new areas for INS use. A second advantage of the micromachined INS would be its size. A micromachined INS would weigh only a few ounces and take significantly less space, allowing more room for electronics and the weight reduction would lead to longer …
Narrowband Interference Suppression In Spread Spectrum Communication Systems, James A. Lascody
Narrowband Interference Suppression In Spread Spectrum Communication Systems, James A. Lascody
Theses and Dissertations
Of significant interest to the United States military is the ability of an enemy to deny or disrupt the operation of the Global Positioning System. To combat this threat the GPS JPO initiated the Tactical GPS AntiJam Technology project, which yielded a prototype Digital Excision Filter (DEF) to remove narrowband jammers. This research describes the work performed to get the DEF hardware operational and extends the previous research performed in this area. Comdisco's Signal Processing Worksystem was used to examine the effect of the DEF on the probability of bit error. This research uses peak to average correlation value, probability …