Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Electrical and Computer Engineering (134)
- Aerospace Engineering (79)
- Electrical and Electronics (77)
- Mechanical Engineering (56)
- Civil and Environmental Engineering (50)
-
- Physical Sciences and Mathematics (44)
- Operations Research, Systems Engineering and Industrial Engineering (38)
- Materials Science and Engineering (28)
- Environmental Engineering (26)
- Aviation (25)
- Operational Research (22)
- Biomedical Engineering and Bioengineering (20)
- Aerodynamics and Fluid Mechanics (17)
- Computer Sciences (15)
- Controls and Control Theory (14)
- Business (13)
- Chemical Engineering (13)
- Engineering Science and Materials (13)
- Manufacturing (12)
- Physics (12)
- Signal Processing (12)
- Management and Operations (11)
- Structures and Materials (10)
- Civil Engineering (9)
- Industrial Engineering (9)
- Mechanics of Materials (9)
- Applied Mathematics (8)
- Computer Engineering (7)
- Operations and Supply Chain Management (7)
- Institution
-
- Air Force Institute of Technology (173)
- New Jersey Institute of Technology (119)
- Old Dominion University (22)
- Portland State University (18)
- Western Michigan University (15)
-
- Embry-Riddle Aeronautical University (13)
- American University in Cairo (10)
- Utah State University (8)
- University of Central Florida (6)
- William & Mary (5)
- University of Northern Iowa (4)
- University of Tennessee, Knoxville (4)
- Missouri University of Science and Technology (3)
- Eastern Illinois University (2)
- University of Alabama in Huntsville (2)
- University of New Mexico (2)
- Brigham Young University (1)
- Grand Valley State University (1)
- Keyword
-
- Flight control (8)
- Finite element method (6)
- Computer simulation (5)
- Control theory (5)
- Neural networks (Computer science) (5)
-
- Computer architecture. (4)
- Computer war games (4)
- Global Positioning System (4)
- H2 control (4)
- Target acquisition (4)
- Wavelets (Mathematics) (4)
- Adaptive filters. (3)
- Automatic speech recognition (3)
- Ceramic-matrix composites--Fatigue (3)
- Composite construction (3)
- Computer algorithms (3)
- F-16 (Jet fighter plane) (3)
- Fracture mechanics--Environmental aspects. (3)
- Inertial navigation systems (3)
- Infrared imaging (3)
- Intelligent control systems (3)
- Metallic composites--Fatigue (3)
- Motion--Analysis. (3)
- Navier-Stokes equations (3)
- Navigation (Aeronautics) (3)
- Nozzles (3)
- Pneumatics--Environmental aspects. (3)
- Shock tubes (3)
- Signal processing--Digital techniques (3)
- Structural optimization (3)
- Publication
-
- Theses and Dissertations (174)
- Theses (94)
- Dissertations (25)
- Masters Theses (20)
- Dissertations and Theses (18)
-
- Mechanical & Aerospace Engineering Theses & Dissertations (15)
- Master's Theses - Daytona Beach (13)
- Archived Theses and Dissertations (10)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (6)
- Retrospective Theses and Dissertations (6)
- Dissertations, Theses, and Masters Projects (5)
- Engineering Management & Systems Engineering Theses & Dissertations (5)
- Dissertations and Theses @ UNI (4)
- Honors Theses (3)
- Doctoral Dissertations (2)
- Honors Capstone Projects and Theses (2)
- Nuclear Engineering ETDs (2)
- Undergraduate Honors Capstone Projects (2)
- Civil & Environmental Engineering Theses & Dissertations (1)
- English Theses & Dissertations (1)
Articles 31 - 60 of 408
Full-Text Articles in Engineering
Distributed Interactive Simulation Virtual Cassette Recorder (Dis Vcr): A Datalogger With Variable Speed Replay, Jonathan L. Fortner
Distributed Interactive Simulation Virtual Cassette Recorder (Dis Vcr): A Datalogger With Variable Speed Replay, Jonathan L. Fortner
Theses and Dissertations
The overall objective of the Distributed Interactive Simulation Virtual Cassette Recorder (DIS VCR) is to add a flexible replay capability to any DIS environment and specifically to the Remote Debriefing Tool (RDT). The DIS VCR's abilities include selective filtering of incoming DIS Protocol Data Units (PDUs), variable-speed replays, ability to pause, fast-forward, rewind, efficient data storage and retrieval, and an interface that simplifies the execution of those functions. The thesis includes a DIS VCR-compatible design for concurrent replay of audio extracted from signal PDUs and an extension to the replay design that supports unmodifiable rendering or receiving applications. For variable-speed …
An Exploration Of Technology Transfer Control: A Case Study Of Wright Laboratory, William K. West
An Exploration Of Technology Transfer Control: A Case Study Of Wright Laboratory, William K. West
Theses and Dissertations
Federal laboratories, system product centers, and military logistics centers are being challenged to leverage national investments in technology beyond their traditional customer base--technology transfer. Participation in domestic technology transfer is growing at an astounding rate. Additionally, the federal government has invested and continues to invest billions of dollars into active defense conversion, dual-use technology, and technology transfer. The objective of this research is to explore how one government laboratory controls its technology transfer process, in both the near and long terms. This research examines the motives for participating in technology transfer. The researcher presents several of the processes that are …
The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter
The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter
Theses and Dissertations
An experimental investigation was performed to determine the effects of transverse vibrations on the performance of an ammonia-aluminum axial groove wick heat pipe. Theoretical calculations predicted a performance degradation due to the working fluid being shaken out of the upper capillary grooves. A benchtop shaker was used to apply transverse, sinusoidal vibrations of 30, 35, and 40 Hertz, corresponding to peak acceleration amplitudes of 1.84g, 2.50g, and 3.27g, respectively. Maximum heat throughput, Q sub max, of the vibrating heat pipe was measured. A comparison of these values and static Q sub max values indicated a degradation in heat pipe performance. …
Experimental Investigation Of The Effects Of Relative Physical Orientation Between Evaporator And Condenser For A Loop Heat Pipe, Brad R. Thompson
Experimental Investigation Of The Effects Of Relative Physical Orientation Between Evaporator And Condenser For A Loop Heat Pipe, Brad R. Thompson
Theses and Dissertations
This research examined the effects on performance of varying angular orientation and height differences between evaporator and condenser for a loop heat pipe. Performance was defined as the difference in temperature between evaporator and condenser (DELTA T). The pipe was evaluated at varying input power (Qin) for: varying evaporator and condenser angles, different coolant temperatures, and varying relative height differences. All analysis included only steady state operation. The performance was influenced by condenser angles, with an optimal condenser angle for best performance being +45 degrees from horizontal. Additionally, the evaporator angles were found to influence performance only at low Qin …
Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter
Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter
Theses and Dissertations
Mean flow and compressible turbulence measurements have been obtained upstream and within a shock boundary interaction and a compression ramp in Mach 3 flow. Compressible turbulence models have met with little success in the accurate prediction of high-speed flows involving complicated shock boundary interactions and adverse pressure gradients because of a crucial lack of experimental data. Data were collected using conventional Pitot and cone static probes, single overheat cross-wire anemometry, multiple overheat cross-wire anemometry, and flow visualization techniques. Direct measurements of the total Reynolds shear stress were obtained using a turbulence transformation. Results indicate that compressibility effects, as evidenced by …
Performance Characterization Of A Highly-Offset Diffuser With And Without Blowing Vortex Generator Jets, Michael B. Senseney
Performance Characterization Of A Highly-Offset Diffuser With And Without Blowing Vortex Generator Jets, Michael B. Senseney
Theses and Dissertations
The effect of blowing vortex generator jets (VGJs) on the performance of a highly-offset (s-duct) diffuser was investigated experimentally. VGJs are pitched, skewed jets which generate streamwise vortices as well as injecting high-momentum fluid into the boundary layer. Diffuser performance with and without VGJs was measured for an inlet Mach number of 0.6 (Re/x = 1.27x107 per cm). Pitot static and hot-film instrumentation was used to measure flow properties at the diffuser inlet and exit planes. Without blowing, the flow on the lower surface of the diffuser was massively separated. Blowing at 0.48% mass flow ratio through three lower-surface …
Survey And Implementation Of Commercial Manual Controllers For A Generic Telerobotics Architecture, Thomas E. Deeter
Survey And Implementation Of Commercial Manual Controllers For A Generic Telerobotics Architecture, Thomas E. Deeter
Theses and Dissertations
The purpose of this study is to determine an input device for the Air Force's generic telerobotics architecture for large aircraft maintenance and repair. One area of concern is the human to machine interface, more specifically, which manual controller should be used for the specified tasks in this architecture. We mailed a survey to 68 companies in order to compile a list of possible input devices that the telerobotics architecture could use. 32 companies responded which gave me enough data to generate a list that described the physical traits of the input devices. We then divided the required tasks into …
A 3-D Finite Difference Time Domain Investigation Of Microwave Propagation Through Inhomogeneous Biological Materials, David B. Dunn Jr.
A 3-D Finite Difference Time Domain Investigation Of Microwave Propagation Through Inhomogeneous Biological Materials, David B. Dunn Jr.
Theses and Dissertations
This paper extends past analysis of an optimal source distribution around a homogeneous sphere of muscle tissue by using a 3-D finite difference time domain (FDTD) scenario in which an anatomically correct human head model is irradiated. It first duplicates the analytical solution within an FDTD space using an FDTD computer code developed at Penn State University. This duplication uses a 9.45 cm radius sphere represented in an FDTD space of 2.35 mm cubic cells. FDTD simulations are then performed on four, three, and two layer laminated spheres, designed to provide simple models of a head. Finally, four simulations were …
An Integrated Gps-Ins-Baro And Radar Altimeter System For Aircraft Precision Approach Landings, Robert A. Gray
An Integrated Gps-Ins-Baro And Radar Altimeter System For Aircraft Precision Approach Landings, Robert A. Gray
Theses and Dissertations
Currently, the Department of Defense (DoD) and the commercial airline industry are utilizing the Instrument Landing System (ILS) during aircraft landings for precision approaches. The replacement system for the aging ILS was thought to he the Microwave Landing System (MLS). Instead, use of the Global Positioning System (GPS) is now thought to be a viable replacement for ILS precision approaches. The majority of current precision landing research has exploited 'stand-alone' GPS receiver techniques. This thesis instead explores the possibilities of using an extended Kalman filter (EKF) that integrates an Inertial Navigation System (INS), GPS, Barometric Altimeter, Pseudolite and Radar Altimeter …
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Theses and Dissertations
A moving bank multiple model adaptive estimator-controller (MMAE-MMAC), based on linear system, quadratic cost, and Gaussian noise (LQG) assumptions, is used to quell unwanted vibrations in a large flexible space structure. The structure, known as the SPace Integrated Controls Experiment, or SPICE, exists at Phillips Laboratory, Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by a tripod of flexible legs. The purpose of the control system is to maintain a very precise line-of- sight vector through the center of the spacecraft. Kalman filtering, used to estimate the position and velocity of the bending …
Adaptive Beamforming In Frequency-Dispersive Multipath Environments, David A. Murray
Adaptive Beamforming In Frequency-Dispersive Multipath Environments, David A. Murray
Theses and Dissertations
It is well known that an antenna array with N degrees of freedom (DOF) can cancel N - 1 interferers if they approach the array from directions other than that of the desired signal. It has been shown that there are cases in which it is possible for an array with N DOF to effectively cancel more than N - 1 interferers. Specifically, we show how this can be done when there is incident upon an N-element array not only the desired signal and a jammer signal, but more than N - 1 Doppler-shifted multipath copies of the jammer signal …
Experimental Definition For Implantation Of The Afit Cortical Multielectrode Array, Adam G. Spenik
Experimental Definition For Implantation Of The Afit Cortical Multielectrode Array, Adam G. Spenik
Theses and Dissertations
A two-dimensional multiplexed array of 256 electrodes (16 x 16) has been fabricated using conventional CMOS fabrication techniques. The size and spacing of the electrodes (160 x 160 µm squares with center-to-center spacing of 250 µm) approximate that of the cortical columns. The device is mounted on a small biocompatible package and a protocol to implant this package on the visual cortex of a ferret and a Rhesus monkey was developed and approved. An instrumentation setup to record the data from the device is described as well as the methods used to demultiplex the data. Testing of the device in …
Reduction Of Off-Boresight Fields For A Tem Horn Antenna, Dennis J. Wolstenholme
Reduction Of Off-Boresight Fields For A Tem Horn Antenna, Dennis J. Wolstenholme
Theses and Dissertations
This research involves the design, modeling, and testing of both tapered periodic surfaces (TPS) and transverse electromagnetic (TEM) horns. The goal is to reduce the off-boresight fields for a TEM horn and increase the peak-to-peak field levels on boresight. This is accomplished by applying a TPS to the free space end. Two tapers are designed - one that approximates an exponential impedance function and one that approximates a triangular impedance function. Both reduce the off-boresight fields of the TEM horn. In most cases the exponential taper reduces the field levels further than the triangular taper. This research shows that a …
Satellite Surface Material Composition From Synthetic Spectra, Eugene L. Caudill
Satellite Surface Material Composition From Synthetic Spectra, Eugene L. Caudill
Theses and Dissertations
The objective of this research was to determine if measurements from a Sagnac interferometer could provide reliable estimates of satellite material composition. The Sagnac interferometer yields a spatial interferogram that can sampled by a linear detector array. The interferogram is related to the spectrum of the source through a Fourier transform. Here, spectral reflectivities of nine common satellite materials were used to simulate the spectrum on obtains from an ideal Sagnac interferometer in the beam-train of a ground-based telescope whose mission is to view satellites. The signal-to-noise ratio of the spectrum was varied to simulate the effect of range variation …
Design And Characterization Of Resonant Cavity Light-Emitting Diodes, Thomas M. Fitzgerald
Design And Characterization Of Resonant Cavity Light-Emitting Diodes, Thomas M. Fitzgerald
Theses and Dissertations
This thesis describes an investigation into the emission properties of Resonant Cavity Light Emitting Diodes (RCLED). RCLEDs are a new photonic device that promise laser-like properties of narrow output frequency spread and high output power, without the usual laser disadvantages of shorter lifetime and increased maintenance and lifetime costs. Specifically, this thesis examines the functional dependence between emitted wavelength and the RCLED microcavity, and attempts to correlate theory with experimental data. This thesis introduces a classical wave interference model that calculates the Spontaneous Emission Enhancement Factor (Z-) with angular dependence.
Image Perception Wavelet Simulation And Enhancement For The Visually Impaired, Lemuel Ray Myers Jr.
Image Perception Wavelet Simulation And Enhancement For The Visually Impaired, Lemuel Ray Myers Jr.
Theses and Dissertations
This research delves into the area of image enhancement for the visually impaired. Binocular macular degeneration a visual impairment, affects many Americans; since this condition could not be corrected with conventional glasses the literature suggested using an enhancement system which used a pre-emphasis algorithm to enhance the input image for output to the observer. The work of Dr. Eli Peli, a pioneer in the field of image enhancement, is examine and reproduced. Since his work concentrated mainly on frequency analysis of images, the bulk of this research involves using discrete wavelet analysis to augment that work. A biorthogonal wavelet set …
Optimization Of A Nutation Damper Attached To A Spin-Stabilized Satellite, Brady P. Hauboldt
Optimization Of A Nutation Damper Attached To A Spin-Stabilized Satellite, Brady P. Hauboldt
Theses and Dissertations
This study uses linearized equations of motion for a rigid body with an attached spring-mass-damper to maximize the decay rate of a satellite's coning motion. An analysis of the numerical eigenvalues is presented which leads to an optimal relationship between relevant parameters: damper placement, spring constant, damping coefficient, system moments of inertia, and damper mass fraction. The coupled system's eigenvalues do not provide truly critical damping, thus the real eigenvalue parts are minimized in order to achieve damping which requires the minimum amount of time. A comparison between this optimal design method and a classical method concludes a noticeable improvement …
Generic Satellite Monitoring Expert System, Loretta A. Kelemen
Generic Satellite Monitoring Expert System, Loretta A. Kelemen
Theses and Dissertations
Air Force Satellite Operations is undergoing major changes. Operators no longer receive detailed satellite training, instead they are taught basic fundamentals of satellite operations and expected to control multiple multimillion dollar satellites. The need is clear. An efficient and economical automated system is necessary to assist the satellite operator in his daily tasks of maintaining these DOD priority resources. Satellite intelligent controllers been under R&D since the early 1980s to this need. These systems, however, have focused on the control of one constellation of satellites. In a military striving for efficiency and lower costs, developing a unique intelligent controller for …
A Multi-Attribute-Utility-Theory Model That Minimizes Interview-Data Requirements: A Consolidation Of Space Launch Decisions, Raymond W. Staats
A Multi-Attribute-Utility-Theory Model That Minimizes Interview-Data Requirements: A Consolidation Of Space Launch Decisions, Raymond W. Staats
Theses and Dissertations
This research uses multi-attribute utility theory (MAUT) to define a mathematical representation of a decision maker's utility associated with a satellite system. While developing the survey instrument, we focused on making it simpler to administer, primarily by eliminating the use of lottery questions. These simplifications enabled us to shorten our interview with the decision maker to under two hours for a rather complex model.
Weighting Scheme For The Space Surveillance Network Automated Tasker, Beth L. Petrick
Weighting Scheme For The Space Surveillance Network Automated Tasker, Beth L. Petrick
Theses and Dissertations
The purpose of this research is to find the best weighting scheme in the SPADOC 4C Sensor Tasking Prototype. This software, known as the Prototype Tasker, assigns a tasking to each sensor of the Space Surveillance Network. A tasking is a list of objects in which the sensor needs to gather positional data, called observations. One of the inputs to the Prototype Tasker is a user-definable weighting scheme. The goal is to find the weighting scheme that produces the most efficient taskings. This problem was solved using a Simulated Annealing algorithm. The values in the weighting scheme were the variables …
Life Cycle Costs Of Alternatives For F-16 Printed Circuit Board Diagnosis Equipment, Kent R. Montgomery, Clifford B. Thorstenson
Life Cycle Costs Of Alternatives For F-16 Printed Circuit Board Diagnosis Equipment, Kent R. Montgomery, Clifford B. Thorstenson
Theses and Dissertations
This study analyzes two alternatives for printed circuit board (PCB) diagnosis for the F-16 depot PCB repair shop from a life cycle cost (LCC) perspective. Alternative 1 assumes the use of the current F-16 automatic test equipment (ATE) while Alternative 2 augments the current ATE with infrared imaging test equipment. Infrared imaging is a developed technology that is currently available to the Air Force in a commercial-off-the-shelf (COTS) form. Using the Cost Analysis and Strategy Assessment (CASA) Life Cycle Cost (LCC) Model and data from the DL41 database on F-16 PCBs this study determined that over the current expected life …
Analysis Of Hypersonic Boundary Layer Second Mode Instability Over A 7° Cone, Richard A. Dennery
Analysis Of Hypersonic Boundary Layer Second Mode Instability Over A 7° Cone, Richard A. Dennery
Theses and Dissertations
This paper presents the results of the analysis of Mach 8.0 flow over a seven degree half-angle cone. The purpose of this analysis was to develop techniques to examine boundary layer transition at hypersonic velocities. The specific objectives were to look for second mode instability waves characteristic of the transition process and to quantify the percentage of turbulent flow. Two sets of data were used in this analysis. The first set of data was taken at several axial positions at a freestream Reynolds number 4.265 million per meter. This data was used to develop the analysis techniques. The second set …
Improved Numerical Solution Of Mixed H2/H∞ Optimization With Applications, Linda D. Smith
Improved Numerical Solution Of Mixed H2/H∞ Optimization With Applications, Linda D. Smith
Theses and Dissertations
This study improved the numerical optimization technique used to compute mixed H2/H∞ controllers. The run time to generate the full curve of an H2/H∞ design was reduced by a factor of almost 200 for a specific example. This was accomplished by improving gradient calculations, upgrading the H∞ norm calculation to capture multiple peaks in the singular value plot and using routines that minimized processing time. The optimization routine used was the MATLAB CONSTR' Sequential Quadratic Programming (SQP) routine. This SQP routine was compared to a FORTRAN SQP numerical optimizer, IMSL-DNCONG. The method was …
Head Related Transfer Function Approximation Using Neural Networks, John K. Millhouse
Head Related Transfer Function Approximation Using Neural Networks, John K. Millhouse
Theses and Dissertations
This thesis determines whether an artificial neural network (ANN) can approximate the Armstrong Aerospace Medical Research Laboratories (AAMRL) head related transfer functions (HRTF) data obtained from research at AAMRL during the fall of 1988. The first test determines whether HRTF lends any support in sound localization when compared to no HRTF (Interaural Time Delay only). There is a statistically significant interaction between the location of the sound and whether the HRTF or no HRTF is used. When this interaction is removed using the alternate F.Value, the statistics give the result of equal means for the filters and azimuth. This means …
A Quantitative Feedback Theory Fcs Design For The Subsonic Envelope Of The Vista F-16 Including Configuration Variation, Scott N. Phillips
A Quantitative Feedback Theory Fcs Design For The Subsonic Envelope Of The Vista F-16 Including Configuration Variation, Scott N. Phillips
Theses and Dissertations
An aircraft's response to control inputs varies widely throughout its flight envelope. The aircraft configuration also impacts control response through variations in center of gravity and moments of inertia. Designing a flight control system (FCS) to accommodate the full flight envelope and configuration set of an aircraft is clearly a complex undertaking. Quantitative feedback theory (QFT) is a design tool which enables the engineer to attack this task in an efficient way. Although QFT is a robust control design technique, it is an interactive algorithm allowing the engineer full control over compensator order and gain. In this research effort, a …
Advanced Formation Flight Control, Michael J. Veth
Advanced Formation Flight Control, Michael J. Veth
Theses and Dissertations
In this thesis, the formation flight control problem is continued from four previous theses. Automatic formation flight involves controlling multiple aircraft equipped with standard Mach-hold, altitude hold, and heading-hold autopilots to maintain a desired distance from a lead aircraft or "rabbit". Changes in the rabbit's states are treated as disturbances to the system and rejected. Previous research is advanced in the following areas: Higher-order aircraft-autopilot models are included into the design and a new feedback control law is employed, resulting in more accurate simulations. An energy tracking scheme is developed and is shown to reduce wing aircraft energy excursions. Finally, …
Polarization Sensitivity Of Monopulse Radar Boresight Error Induced By Large, Ogive Radomes, Kelce S. Wilson
Polarization Sensitivity Of Monopulse Radar Boresight Error Induced By Large, Ogive Radomes, Kelce S. Wilson
Theses and Dissertations
The dependence of Boresight Error (BSE) on incident Electric Field (E-Field) polarization tilt angle is investigated. BSE, defined as the angular difference between a target's actual and radar-indicated position, is influenced by the radome used to protect the antenna. A - reliable computer model for predicting the BSE of electrically large radar-radome systems has been demonstrated and used to investigate the dependence of radome-induced BSE for various combinations of scan angle, element polarization, and incident E-Field polarization. The analysis includes a development of a transmission-depolarization model to justify the results of the computer model. Results compare very well with empirical, …
Perceptual Based Image Fusion With Applications To Hyperspectral Image Data, Terry A. Wilson
Perceptual Based Image Fusion With Applications To Hyperspectral Image Data, Terry A. Wilson
Theses and Dissertations
Development of new imaging sensors has created a need for image processing techniques that can fuse images from different sensors or multiple images produced by the same sensor. The methods presented here focus on combining image data from the Airborne Visual and Infrared Imaging Spectrometer (AVIRIS) hyperspectral sensor into a single or smaller subset of images while maintaining the visual information necessary for human analysis. Three hierarchical multi-resolution image fusion techniques are implemented and tested using the AVIRIS image data and test images that contain various levels of correlated or uncorrelated noise. Two of the algorithms are published fusion methods …
Flow Visualization Of A Turbulent Shear Flow Using An Optical Wavefront Sensor, Daniel W. Jewell
Flow Visualization Of A Turbulent Shear Flow Using An Optical Wavefront Sensor, Daniel W. Jewell
Theses and Dissertations
The research reported here investigated the use of a shearing interferometer (SI) wavefront sensor to determine the effects of shear-layer turbulence on an optical wavefront. A collimated helium-neon laser beam was propagated through a plane shear-layer produced by mixing helium and nitrogen at different velocities. Since the gases have different indices of refraction, the optical wavefront was distorted by different amounts by each gas. The SI measured the wavefront slope across the sampled area of the wavefront. The shear-layer was viewed from two orthogonal directions. This document contains shadow graphs, interference patterns imaged by each of the SI's six cameras, …
Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen
Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen
Theses and Dissertations
NORAD maintains and disseminates mean orbital elements on Earth-orbiting satellites in the form of Two-Line Element Sets (TLE). Five mathematical propagator models were developed for NORAD's use to predict the position and velocity using TLEs. This study investigated two approaches, Newton's method and direct iteration, to inverting this process by iterating to obtain NORAD-compatible mean orbital elements from a position and velocity state vector and the drag term. The Newton's iteration method was developed but not tested. The less computationally intensive direct iteration method was developed, coded in FORTRAN, and tested. The initial guess and subsequent corrections in the iterative …