Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Keyword
-
- Flight control (5)
- Cascades (Fluid dynamics) (4)
- Adaptive control systems (3)
- Flexible structures (3)
- Global Positioning System (3)
-
- Large space structures (Astronautics) (3)
- Navier-Stokes equations (3)
- Air traffic control (2)
- Artificial satellites (2)
- Axial flow compressors--Blades (2)
- Bifurcation theory (2)
- Compressors (2)
- Heat--Transmission (2)
- Kalman filtering (2)
- Passive damping (2)
- Quantitative feedback theory (2)
- Reynolds number (2)
- Scheduling (2)
- Space vehicles--Propulsion systems (2)
- Wakes (Fluid dynamics) (2)
- 3D (1)
- Aerodynamic optimization (1)
- Aerodynamics (1)
- Aerofoils (1)
- Air warfare (1)
- Aircrew (1)
- Airfoil (1)
- Airplanes--Control surfaces (1)
- Airplanes--Ramjet engines (1)
- Algorithms (1)
Articles 1 - 30 of 54
Full-Text Articles in Entire DC Network
Comparison Of Air Traffic Control Candidate Ability With Simulator-Based Training Measures, Lawrence A. Tomaskovic
Comparison Of Air Traffic Control Candidate Ability With Simulator-Based Training Measures, Lawrence A. Tomaskovic
Master's Theses - Daytona Beach
The purpose of this study was to determine if the utilization of an experimental computer-based selection test battery would aid in the prediction of a candidate's performance when using an air traffic control computer-based simulation program. Each candidate completed the selection test battery, and then received air traffic control instruction using the air traffic control simulation program incorporated in the TRACON/Pro™ simulator system. The selection test battery results were correlated with the subsequent simulator scoring results.
The Effect Of Active And Passive Control On Air Traffic Controller Dynamic Memory, Esa M. Rantanen
The Effect Of Active And Passive Control On Air Traffic Controller Dynamic Memory, Esa M. Rantanen
Master's Theses - Daytona Beach
The purpose of this study was to investigate the effect of automated and passive control on air traffic controller dynamic memory. The study consisted of two experiments, each involving a realistic ATC scenario for radar approach control with a mix of arriving and departing traffic. In Experiment I, the subjects performed manual control of the traffic while, in Experiment II, the scenario was highly automated and the subjects were tasked with only monitoring the situation. The dynamic memory performance was measured by interrupting the scenario and having the subjects recall the traffic situation at the moment of simulation interruption. The …
Primary Coolant Flow Characteristics As It Exits The Palisades Reactor, Gregory Alan Baustian
Primary Coolant Flow Characteristics As It Exits The Palisades Reactor, Gregory Alan Baustian
Masters Theses
During fuel cycles 9 and 10 at the Palisades Nuclear Power Plant, new phenomena have been observed using the resistance temperature devices installed in the reactor coolant piping. Oscillations in the temperature readings have been observed leading to the assumptions that there is temperature stratification of the coolant in the reactor hot-legs and that the coolant rotates as it leaves the reactor. In addition, oscillations in the bulk coolant flow within the two hot legs have been postulated. This report outlines work performed using computational fluid dynamics modelling which predict the observed and assumed flow characteristics of the Palisades reactor …
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller
Theses and Dissertations
The purpose of this thesis is to apply moving-bank multiple model adaptive estimation and control MMAEMMAC algorithms to an actual space structure SPICE being examined at Phillips Laboratory at Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Kalman filtering and LQG control techniques are utilized as the primary design tool. Implementing a bank of filters increases the robustness of the LQG controller when uncertainties exist in the system model, whereas the moving bank is utilized to reduce the computational load. Several reduced-order models are developed from …
Design And Construction Of The Aerobot Robotic Manipulator (Arm), William L. Cochran
Design And Construction Of The Aerobot Robotic Manipulator (Arm), William L. Cochran
Theses and Dissertations
This thesis designed, constructed, and tested a robotic arm for the Aerobot Aerial Robot. The main purpose of the ARM is to enable the Aerobot to retrieve objects for use in an annual robotics competition. Design of the ARM involved synthesizing the characteristics of simplicity, weight, strength, and size. The result was a three-degree-of-freedom manipulator that uses electric motors, cable linkages, and telescoping tubes to access a work space below the Aerobot. Forward and inverse kinematics were investigated to enable automation of the ARM. Data was collected from infrared sensors to validate the model. Manipulation of the ARM is presently …
Off-Design Performance Of Crenulated Blades In A Linear Compressor Cascade, Michael J. Costello
Off-Design Performance Of Crenulated Blades In A Linear Compressor Cascade, Michael J. Costello
Theses and Dissertations
The effects of using compressor blades with a crenulated (notched) trailing edge in a low aspect ratio (AR= 1) linear compressor cascade at four incidence angles (-1.08°, +4.49°, +9.32° and +12.44°) were investigated. Blade performance and wake mixing characteristics for crenulated blades were compared with similar data for blades with a straight trailing edge. A seven-bladed cascade was operated with a flow Mach number of 0.4 and a blade chord Reynolds number of 4.1 (10)5. The diffusion factor ranged from 0.22 to 0. 42 and strong three-dimensional flow effects were present. Total pressure losses were measured with a …
Exploring Qdes As A Tool For Determining Limits Of Achievable Performance In Aircraft Design, Mark F. Reidinger
Exploring Qdes As A Tool For Determining Limits Of Achievable Performance In Aircraft Design, Mark F. Reidinger
Theses and Dissertations
This thesis explores the usefulness of a computer aided control design software package called QDES in determining the limits of achievable aircraft performance as it relates to controller capability. Modern aircraft, particularly fighters, are being designed to be statically unstable to enhance their maneuverability and performance. It is possible that the aircraft, although physically capable of a certain level of performance due to its engine/ airframe combination, may be uncontrollable up to this level. This study sought to develop a methodology to use QDES to make a preliminary analysis of an aircraft design to determine if there exists a controller …
Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris
Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris
Theses and Dissertations
The purpose of this thesis was to investigate the performance of two types of tracking loops used in Global Positioning System (GPS) receivers. The first loop, the Delay-Lock Loop (DLL), is responsible for maintaining synchronization with the received PN sequence. The second loop, the Modified Tanlock Loop (MTLL), is responsible for maintaining synchronization with the carrier signal. The performance of the two loops is investigated first separately then their performance is evaluated when operated together. This thesis is an investigation on the ability of these two loops to overcome corruption of the input signal due to noise. Expanding the dynamic …
A Methodology To Assess The Impact Of The Global Positioning System On Air Combat Outcomes, Stephen F. Sovaiko
A Methodology To Assess The Impact Of The Global Positioning System On Air Combat Outcomes, Stephen F. Sovaiko
Theses and Dissertations
The Air Force has a requirement to quantify the force enhancement effects of military space systems, but no methodology currently exists for the measurement of their contribution to air combat outcome. This research examines the Global Positioning System GPS and models its influence on air-to-ground combat. The decision analysis technique of influence diagrams is used to identify the effects of GPS launch decisions and constellation size on the navigation accuracy available to air combatants. The effect of accuracy variations on combat outcome is shown by using a value tree to identify the affected campaign Measures of Effectiveness. The study reveals …
Automating Satellite Range Scheduling, S. Michael Schalck
Automating Satellite Range Scheduling, S. Michael Schalck
Theses and Dissertations
The objective of this study was to develop a computer based satellite range scheduling SRS algorithm to create a 24 hour satellite support schedule. The algorithms goal was to schedule as many satellite support requests as possible. An iterative heuristic approach was used to schedule satellite support requests in three successive sub problems. The first sub problem involves scheduling low altitude satellite support requests using a mixed integer programming approach. The next two sub problems each involve scheduling 12 hour blocks of medium and high altitude satellite support requests, again using a mixed integer programming approach. Fourteen 24 hour schedules …
Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank
Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank
Theses and Dissertations
The stall characteristic of four single-stage transonic compressor rotors were investigated as they were throttled to stall. Forward-swept, backward-swept, and straight leading edge rotors were examined. Three methods of analysis (1) windowed power spectrum densities of pressure and spatial Fourier coefficients, (2) phase tracking analysis, and (3) system identification were used to identify the first appearance of modal waves and their accompanying frequencies in order to identify a stall warning time. A direct correlation between the amount of stall warning time and the shape of the compressor characteristic was found. Specifically, if the compressor characteristic had a significant period of …
Steady Motions Of Rigid Body Satellites In A Central Gravitational Field, Cynthia A. Provost
Steady Motions Of Rigid Body Satellites In A Central Gravitational Field, Cynthia A. Provost
Theses and Dissertations
Numerous studies have been conducted on equilibrium orientations of objects moving under the influence of a central gravitational field. The results of many of these studies conclude that equilibrium conditions exist only when one of the principal axes coincides with the radius vector. Furthermore, these results assume that the center of force is located within the orbit plane, thereby tracing a great circle orbit. While these previous works have approximated the gravitational potential, this study examines relative equilibrium obtained by retaining an exact expression for the potential of a spherical primary body, as shown in a recent paper by Wang, …
Analysis Of The Effects Of Wake Passage On Heat Transfer In A Linear Turbine Cascade, Kevin S. Allen
Analysis Of The Effects Of Wake Passage On Heat Transfer In A Linear Turbine Cascade, Kevin S. Allen
Theses and Dissertations
This study investigated the effect of wake passage on the heat transfer in a linear turbine cascade. The apparatus used was the Air-Force Institute of Technology linear Turbine Cascade Test Facility (TCTF). The TCTF was fitted with a be Pulley system to facilitate a series of translating bars. The bars, when passed d upstream of the cascade, created a series of wakes. The parameters varied were freestream model Reynolds number and bar conditions, i.e. , bars in, bars out, and bar passing frequency. One blade in the TCTF was instrumented to allow pressure and temperature measurements at discrete points on …
Dynamic Response Of A Compressor Research Facility, Janet W. Grondin
Dynamic Response Of A Compressor Research Facility, Janet W. Grondin
Theses and Dissertations
The response of the Wright Laboratory Compressor Research Facility to a small amplitude, acoustic, sinusoidal disturbance was investigated. The fluid transmission line equations for laminar, one-dimensional flow in a circular duct were solved and verified through a laboratory experiment using a scale model of the facility. The resonant frequencies of the facility were determined for a variety of flow conditions. Techniques for analytically modeling end impedance and flow straightening elements were also studied. The fundamental frequency of the facility was determined to be between 5.5 and 6.5 Hz depending on the flow conditions and geometry configurations specified.
Optimal Control Design Advantages Utilizing Two-Degree-Of-Freedom Controllers, Michael J. Stephens
Optimal Control Design Advantages Utilizing Two-Degree-Of-Freedom Controllers, Michael J. Stephens
Theses and Dissertations
The purpose of this study was to investigate and describe the differences between a one-degree-of-freedom (1-DOF) controller, in which a controller is placed in a single location in the control loop, and a two-degree- of-freedom (2-DOF) controller, in which two separate controllers are designed -- one in the feedback loop and the other as a prefilter in the forward loop. The approach involved summarizing the major rules governing loop shaping for performance and robustness in the 1-DOF case and then extending the concepts to the 2-DOF case. H2 optimization was utilized to perform several types of SISO examples and …
A Numerical Determination Of Bifurcation Points For Low Reynolds Number Conical Flows, Larry K. Waters
A Numerical Determination Of Bifurcation Points For Low Reynolds Number Conical Flows, Larry K. Waters
Theses and Dissertations
It has long been established that supersonic flow over axisymmetric conical bodies at high angles of attack tend to develop a side force due to vortical asymmetry. One of the proposed reasons for the asymmetry is a bifurcation point in the solution of the Navier-Stokes equations. This study investigated the possible existence of a bifurcation point in the Navier-Stokes equations for subsonic flow. Newton's method, with gauss elimination, was used- to solve the steady-state, viscous, compressible Navier-Stokes equations in spherical coordinates assuming conical similarity.
A Virtual Environment For Satellite Modeling And Orbital Analysis In A Distributed Interactive Simulation, Andrea A. Kunz
A Virtual Environment For Satellite Modeling And Orbital Analysis In A Distributed Interactive Simulation, Andrea A. Kunz
Theses and Dissertations
In response to the need for a more realistic, interactive, and immersive space simulation system, the Joint National Intelligence Defense Staff JNIDS has sponsored the development of the Satellite Modeler at the Air Force Institute of Technology AFIT. The Satellite Modeler SM is a virtual environment VE application that allows analyst-users to enter a virtual near- Earth space environment and visualize realistic satellite models performing accurate orbital motion. The Satellite Modeler provides manipulation functions that allow a user to interact with multiple satellite models and satellite constellations. The system affords the user multiple vantage points within the environment to view …
Satellite Attitude Determination Using Linear Combination Of Models, Martin S. Chin
Satellite Attitude Determination Using Linear Combination Of Models, Martin S. Chin
Theses and Dissertations
In satellite analysis, it is often necessary to determine the attitude of a satellite from a two dimensional image of the satellite. This thesis describes work performed to determine the attitude of a satellite relative to a reference position. The attitude is described in terms of the scaling, rotation and translation of the reference that will result in a pose that can be projected to form the image of interest. The techniques used are based on finding coefficients for the linear combination of basis images and decomposition of a composite transformation matrix. The methods were initially modeled in Mathematica and …
Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating
Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating
Theses and Dissertations
This thesis describes the application of the multiple-input multiple- output (MIMO) Quantitative Feedback Theory (QFT) design technique to the design of a digital flight control system for the Lambda Unmanned Research Vehicle (URV). The QFT technique allows the synthesis of a control system which is robust in the presence of structured plant uncertainties. Uncertainties considered in this design are the aircraft's plant variation within the flight envelope and the effects of damage to aircraft control surfaces. Mathematical models of control surface failure effects on aircraft dynamics are derived and used to modify an existing small perturbation model of the Lambda. …
Neural Networks For Dynamic Flight Control, Ronald E. Setzer
Neural Networks For Dynamic Flight Control, Ronald E. Setzer
Theses and Dissertations
This thesis examines the application of artificial neural networks (NNs) to the problem of dynamic flight control. The specific application is the control of a flying model helicopter. The control interface is provided through a hardware and software test bed called the Fast Adaptive Maneuvering Experiment (FAME). The NN design approach uses two NNs: one trained as an emulator of the plant and the other trained to control the emulator. The emulator neural network is designed to reproduce the flight dynamics of the experimental plant. The controller is then designed to produce the appropriate control inputs to drive the emulator …
Prototype Space Fabrication Platform, James A. Bessel, James M. Ceney, David M. Crean, Edward A. Ingham, David J. Pabst
Prototype Space Fabrication Platform, James A. Bessel, James M. Ceney, David M. Crean, Edward A. Ingham, David J. Pabst
Theses and Dissertations
Current plans for constructing large structures in space entail fabricating the primary components, such as truss segments, on the ground and assembling them in space. This process requires an exorbitant number of support missions, and methods to minimize the number must be considered. Whenever the space shuttle is launched, its external tank is jettisoned and destroyed prior to reaching orbit. This aerospace grade aluminum structure can be carried into orbit and utilized extrusively. The Prototype Space Fabrication Platform SFP fabricates aluminum materials, reduced from external tanks, into functional trusses. The trusses are strong and can be used as the primary …
Orbital Applications Of Electrodynamic Propulsion, Troy Irwin
Orbital Applications Of Electrodynamic Propulsion, Troy Irwin
Theses and Dissertations
Electrodynamic propulsion (EDP) uses forces resulting from electric currents in conductors as a spacecraft travels through a magnetic field. A vehicle-independent expression for the specific power required for any maneuver is derived and used to assess EDP feasibility. Analytical expressions for the accelerations and combined current-conductor vector required to change the orbital plane or the argument of perigee are developed based on Lagranges planetary equations. Solutions to the forced Clohessy-Wiltshire equations are developed to study iii-plane rendezvous. Results show EDP can change inclination or right ascension of the ascending mode at approximately 0.4 degrees/day with current spacecraft specific power technology. …
Evaluation Of A Concentration Probe For Application In A Supersonic Flow Field, John S. Alsup
Evaluation Of A Concentration Probe For Application In A Supersonic Flow Field, John S. Alsup
Theses and Dissertations
Aspirating, concentration probes are used to measure binary gas concentrations in a supersonic flow. In the past, a tank discharge method has been used to calibrate concentration probes. An alternate calibration method has been developed and tested on a probe in a steady, subsonic/sonic flow. This study evaluated the calibration and performance of a concentration probe in a steady, supersonic flow over a range of mixture ratios of air and helium. The results of this study and a comparison of the two calibration methods are presented.
A Numerical Study Of High-Speed Missile Configurations Using A Block- Structured Parallel Algorithm, Douglas C. Blake
A Numerical Study Of High-Speed Missile Configurations Using A Block- Structured Parallel Algorithm, Douglas C. Blake
Theses and Dissertations
A numerical analysis of the aerodynamic phenomena associated with the high-speed flight of a sharp-nosed, four-finned, high-fineness ratio missile using a block-structured, parallel computer algorithm is presented. The algorithm, PANS-3EM, utilizes a second-order-accurate, shock-capturing, Total Variation Diminishing scheme and incorporates a Baldwin-Lomax turbulence model. PANS-3EM allows for extreme flexibility in the choice of computational domain decomposition and computing machine of implementation. Developmental work consists of conceptualization and verification of the algorithm as well as parallel performance and scalability studies conducted on a variety of computing platforms. Using PANS-3EM, the aerodynamic characteristics of the missile are investigated. Drag and pitching moment …
Multiple Model Adaptive Control Of A Large Flexible Space Structure With Purposeful Dither For Enhanced Identifiability, James A. Fitch
Multiple Model Adaptive Control Of A Large Flexible Space Structure With Purposeful Dither For Enhanced Identifiability, James A. Fitch
Theses and Dissertations
Dithering techniques for enhancing uncertain parameter identification with moving-bank Multiple Model Adaptive Estimation MMAE and Control MMAC algorithms are analyzed in this thesis. The dithering techniques and multiple- model adaptive algorithms are applied to the SPICE 2 flexible space structure. The dithering techniques studied include purposefully constructed square wave, sine wave fixed and swept frequency and wide-band noise wave forms. Purposeful rigid-body slew commands are also used in order to excite the structures flexible bending modes. Dither inputs into the structure are performed in an effort to enhance the open-loop identifiability of the uncertain parameter, namely a scalar multiplier on …
Modal Control Of A Satellite In An Unstable Periodic Orbit About The Earth-Sun Interior Lagrange Point, Douglas J. Hopper
Modal Control Of A Satellite In An Unstable Periodic Orbit About The Earth-Sun Interior Lagrange Point, Douglas J. Hopper
Theses and Dissertations
A periodic halo orbit which exists about the interior Lagrange point for the Earth-sun system was decomposed using Floquet theory into modal variables, which are dynamically decoupled subspaces for the six degree of freedom system. Modal control consisted of evaluating the diverging mode and maneuvering to counteract its divergence. In the unperturbed system, this was successful. Control costs were low, and the significance is that the controller did nothing to suppress modes that were oscillatory or converging. The effect of the moons motion allowed the scheme to operate with reasonable control costs, but the effect of eccentricity caused divergence in …
An Approximate Solution For The Spinup Dynamics Of Near Axisymmetric Axial Gyrostats Using The Method Of Multiple Scales, Stewart J. Kowall
An Approximate Solution For The Spinup Dynamics Of Near Axisymmetric Axial Gyrostats Using The Method Of Multiple Scales, Stewart J. Kowall
Theses and Dissertations
Approximate solutions for the spinup of a near axisymmetric gyrostat are derived using the straightforward expansion method and the method of multiple scales. Two method of multiple scale solutions are presented. The first is derived using cartesian coordinates while the second is derived using cylindrical coordinates. The multiple scales solutions are compared to numerically integrated results for oblate and prolate configurations. A comparison for flat spin recovery is also accomplished. Excellent results are obtained for oblate configurations. Trajectory separatrix crossings hindered the results for prolate configurations and flat spin recoveries.
Modeling Of A Large Undamped Space Structure Using Time Domain Techniques, Anthony R. Nash
Modeling Of A Large Undamped Space Structure Using Time Domain Techniques, Anthony R. Nash
Theses and Dissertations
The first phase of this project was the selection of accurate time domain state space modeling techniques by comparing the models generated by various methods, against a known system. The techniques selected were the Eigensystem Realization Algorithm and the Backward Least Squares method. These modeling techniques were applied to the vibration data from the PACOSS dynamic test article. The resulting model transfer function was then compared to the frequency response function of the actual system, and was found to be an accurate match for the system poles, but not for the system zeros. Large Space structures, Dynamic Control, System Mode …
The Modal Solution To The Moon's Orbit Using Canonical Floquet Perturbation Theory, Kurt A. Vogel
The Modal Solution To The Moon's Orbit Using Canonical Floquet Perturbation Theory, Kurt A. Vogel
Theses and Dissertations
Using the restricted three body problem, the equations of motion EOM and Hamiltonian are computed for the moons orbit in physical variables. A periodic orbit is found in the vicinity of the moons orbit, and classical Floquet theory is applied to the periodic orbit to give stability information and the complete solution to the equations of variation. Floquet theory also supplies a transformation from physical variables to modal variables. This transformation to modal variables is made canonical by constraining the initial transformation matrix to be symplectic. Actual lunar data is used to calculate the modes for the real moons orbit. …
Wake Passage Effects On The Losses In A Linear Turbine Cascade, James A. Braunschneider
Wake Passage Effects On The Losses In A Linear Turbine Cascade, James A. Braunschneider
Theses and Dissertations
A linear turbine cascade was used to investigate the effects of wake passage due to stator-rotor interaction. The wakes were modeled by passing 1.98 mm (0.078 in) diameter bars upstream of a linear cascade blade row. Total pressure loss coefficients, mass averaged total pressure loss coefficients and velocities were used to characterize the effects of wake passage. Bar passing frequencies of 80, 160, 320 bars/sec were tested. These frequencies were tested, with the bars at 6.35 mm (0.25 in) intervals and at two Reynolds numbers, 341, 000 and 45,5000 Bar spacings of 12.7 mm (0.5 in), and 89 mm (3.5 …