Engineering Commons^™

Maneuvering Control Of A Spacecraft With Propellant Sloshing, Philip A. Savella

Master's Theses - Daytona Beach

Propellant slosh has been a problem studied in spacecraft designs since the early days of large, liquid-fuel rockets. The conventional design solution involves physical structures inside the fuel tanks that limit propellant motion. Although effective, baffles and bladders add to spacecraft mass and structural complexity. In this research, the sloshing fuel mass is treated as an unactuated degree of freedom within a rigid body. Specifically, the propellant is modeled as a pendulum mass anchored at the center of a spherical tank. After obtaining the coupled equations of motion, several linear controllers are developed to achieve planar spacecraft pitch-maneuvers while suppressing …

Derivation Of A Numerical Method For Computing 3-D Magnetoplasmadynamic Flows In Thermodynamic Non-Equilibrium, Caroline CéCile Marcelle Liron

Master's Theses - Daytona Beach

Various models exist for the propulsion concept using magnetohydrodynamics (MHD). Various authors, such as Powell, Canupp, Candler, and MacCormack have dealt with issues of solving the magnetic field induction equations simultaneously with Navier-Stokes equations using Computational Fluid Dynamics (CFD). Although most authors deal with species non-equilibrium and thermal non-equilibrium, a new emphasis is set to study the impact of electrons with the electron energy and the electronic excitation energy, as well as a complex energy non-equilibrium.

This thesis presents the derivation of a numerical method for computing 3-D MHD flows for the purpose of modeling steady-state magnetoplasma …

Damage Assessment And Strength Predictions In S-Glass/Epoxy Laminates Subjected To Low Energy Impact, Tuan-Khoi Dang Nguyen

Master's Theses - Daytona Beach

Composite materials have become one of the leading materials for manufacturing in the aerospace industry today. Compared to "conventional" aerospace metals, composites generally have higher strength-to-weight and stiffness-to-weight ratios, good fatigue and corrosion resistance and reduced parts count. However, like any other material, they also have disadvantages. They are inherently brittle and are thus prone to impact damage. Low energy/velocity impact damage, in particular, can be dangerous because the damage oftentimes goes undetected and can subsequently grow under load. Also known as barely visible impact damage (BVID), this area of concentration focuses on the small-scale damage that may be very …

Investigation Of A Highly Loaded, High Pressure Ratio Axial Turbine Stage For Industrial Applications, Amit Garg

Master's Theses - Daytona Beach

The turbine component of a gas turbine engine is the most costly component due to its complexity, and life requirements, given the harsh environment in which it is required to operate. Minimizing the number of stages can lead to significant savings in terms of development efforts, materials, and serviceable parts. This philosophy has led to a significant increase in the work demanded from the typical stage. In this work, a highly loaded axial turbine stage was designed for high power-output industrial applications using a comprehensive set of investigations, which included parametric studies, throughflow solutions, and 2D airfoil shapes. The design …

Fabrication And Compressive Yield Strength Of Open Cell Corrugated Cellular Solids, Jeong Ho Choi

Master's Theses - Daytona Beach

This thesis studied the fabrication and compressive yield strength of open cell corrugated cellular solids made from type 304 stainless steel. Test samples were made by corrugating woven wire meshes, then laminating these in a high temperature argon environment. Mesh sizes ranging from 9.5 pore/cm (24 pore/in) to 31.5 pore/cm (80 pore/in) with wire diameters ranging from 0.178 mm (0.007 in) to 0.3556 mm (0.014 in) were bonded using lithobraze 925 (Ag-7.5Cu-0.2Li) to create cellular solids having relative densities ranging from 0.0384 to 0.0920. Test samples were then quasistatically compressed to measure the stress-strain response. The stress level at 25% …

Modeling And Slew-Maneuver Control Of A Flexible Spacecraft, Jeremy E. Eckhart

Master's Theses - Daytona Beach

Slew-maneuver control problem is studied for a flexible spacecraft consisting of a rigid main body to which a long flexible appendage is attached. Nonlinear dynamical system models are developed using both distributed parameter modeling and discrete parameter modeling; these models are shown to be equivalent for appropriately chosen system parameters. Lyapunov-based nonlinear feedback controllers are designed for the control of rigid-body motion while suppressing the lowest frequency vibrational mode. In case of large-angle maneuvers, these nonlinear controllers are shown to outperform the linearization-based controllers including the filtered proportional-derivative (PD) controllers as well as the linear quadratic regulator (LQR) controllers. Finally, …

Effect Of Automation Management Strategies And Sensory Modalities As Applied To A Baggage Screening Task, Michelle Ann Leach

Master's Theses - Daytona Beach

Automation management strategies can assist the operator in coordinating activity in automated systems. Baggage screening is a domain in which automation and alarms can be studied in terms of signal detection theory. Baggage screening is vital to national security and should be completed in a time efficient manner without compromising accuracy. In the present study, the automation management strategies of management by consent (MBC) and management by exception (MBE) were crossed with alarm modalities of a visual (flashing) or an auditory alert which served as redundant cues in a baggage screening task. A control base line condition existed in which …

The Effect Of Level Of Automation And Operator-To-Vehicle Ratio On Operator Workload And Performance In Future Uav Systems, Ryan J. Wasson

Master's Theses - Daytona Beach

The military intends to increase the number of UAVs in service while at the same time reducing the number of operators (Dixon, Wickens & Chang; 2004). To meet this demand, many of the current UAV operator functions will need to be automated. How automation is applied to modern systems is not fixed. Levels of automation exist along a continuum from fully manual to fully automatic. Two proposed levels of automation for future UAV systems are Management by Consent (MBC), where the operator selects the task to be executed, and Management by Exception (MBE), where the computer selects the task to …

A Computational Study Of Thermo-Fluid Dynamics Of Pulse Detonation Engines, Alberto Davila Urresti

Master's Theses - Daytona Beach

The purpose of this thesis is to use a transient Computational Fluid Dynamics computer code written in FORTRAN 90 for full reaction kinetics, to perform an analysis of the physical processes and chemical phenomena occurring on a single cycle of an ideal Pulse Detonation Engine (PDE) using a stoichiometric mixture of H₂ and O₂. A small zone of high pressure and temperature is used to initiate the detonation wave in the PDE. A simple case with no chemical reactions and the same PDE geometry and “computational spark” is also tested. The speed of the wave relative to …

The Influence Of Visibility, Cloud Ceiling, Financial Incentive, And Personality Factors On General Aviation Pilots' Willingness To Take Off Into Marginal Weather, Part I: The Data And Preliminary Conclusions, William Knecht, Howard Harris, Scott Shappell

Publications

Adverse weather is the leading cause of fatalities in general aviation (GA). In this research, influences of ground visibility, cloud ceiling height, financial incentive, and personality were tested on 60 GA pilots' willingness to take off into simulated adverse weather. Results suggested that pilots do not see "weather" as a monolithic cognitive construct but, rather, as an interaction between its separate factors. This is supported by the finding that the multiplicative statistical effect of visibility and ceiling could better predict takeoff than could the linear effect of either variable considered separately. Also found was a statistical trend toward financial incentive …

Numerical Simulation Of Live Chaparral Fire Behavior Using Firetec, Lulu Sun, Xiangyang Zhou, Shankar Mahalingam, Jesse Canfield, Rodman Linn

Publications

Fire spread through chaparral fuels is a significant feature of wildland fire in southern California. In order to study the detailed physical processes involved during fire spread, FIRETEC, a coupled atmosphere/wildfire behavior model was refined to examine chaparral fire behavior. FIRETEC combines a sophisticated fine-scale model to simulate a three- dimensional wildfire, moving over a terrain-following finite volume grid, with the motions of the local atmosphere. It accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts and the resulting transport equations are solved by using a finite difference method. In …

Robust Control Techniques For State Tracking In The Presence Of Variable Time Delays, Jarrett Goodell, Marc Compere, Miguel Simon, Wilford Smith, Ronnie Wright, Mark Brudnak

Publications

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory (GVSL). Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory (P&E SIL), which is developed and maintained by Science Applications International Corporation (SAIC). The goal is to close the loop between the GVSL and P&E SIL over the Internet to provide a realistic driving experience in addition to realistic …

Control System Design And Simulation Of Spacecraft Formations, Daniel Dyer

Master's Theses - Daytona Beach

The objective of this thesis is to analyze an effective control scheme for a formation of spacecraft, implement that control, and provide a 3-D simulation. The thesis first summarizes the progress made in formation flight control schemes and then provides a theoretical framework for the control system design. Using established control design techniques, feedback laws are constructed to control both rotational and translational motion of a group of spacecraft. Computer simulations are carried out using Matlab to generate the ephemeris and attitude data, which are exported to Satellite Tool Kit (STK) to create animations. The process by which Matlab is …

Accuracy Of Heat-Pulse Sensors For Determining Moisture Of Capillary Mat Material Used To Support Plant Growth, Marisa Wyssling

Master's Theses - Daytona Beach

The accuracy and precision of Orbital Technologies (Orbitec, Madison, WI) Thermal and Moisture Acquisition System (TMAS) sensors were investigated for use in the WONDER space flight experiment. WONDER is studying the effect of multiple wetness level regimes and two different nutrient delivery systems (NDS) on plants grown in the microgravity of space. The following research concentrates on the porous tube NDS consisting solely of a capillary mat surrounding a bare porous tube used for water delivery. Sensors and plants will be attached to the capillary mat, which transports water by capillary action. The TMAS sensors, single probe heat-pulse moisture sensors, …

Transient Non-Linear Heat Conduction Solution By A Dual Reciprocity Boundary Element Method With An Effective Posteriori Error Estimator, Eduardo Divo, Alain J. Kassab

Publications

A Dual Reciprocity Boundary Element Method is formulated to solve non-linear heat conduction problems. The approach is based on using the Kirchhoff transform along with lagging of the effective non-linear thermal diffusivity. A posteriori error estimate is used to provide effective estimates of the temporal and spatial error. A numerical example is used to demonstrate the approach.

The Effect Of Crosswind And Turbulence In Mental Workload And Pilot Tracking Performance, Bruno E. Vivaldi

Master's Theses - Daytona Beach

The purpose of this study was to evaluate the effect of crosswind and turbulence on mental workload and pilot tracking performance. Based on previous research, it was believed that as the amount of crosswind and turbulence is increased, mental workload would increase and tracking performance would decrease. The objective was to estimate the impact that crosswind and turbulence, of varying degrees, had on performance and workload. Fifteen full time college student volunteers served as experimental participants in a simulated horizontal and vertical tracking task. Each participant flew twelve instrument approaches, experiencing a different crosswind and turbulence combination during each approach. …

The Effects Of Gender And Regional Dialect On Performance In Aviation Communication, Erin E. Mccollum

Master's Theses - Daytona Beach

The purpose of this study was to analyze the performance effects of gender and regional dialect on air traffic control statement recall. Sixty-one student volunteers participated in the experiment. Thirty-one participants held a pilot’s license and 30 participants had no flight experience. Each participant listened to one CD with 60 ATC statements each representing a male and female voice and New England, Southern, and General American dialect. Participants were asked to recall exactly what they heard. If the participant could not understand what they heard, they requested a repeat. The participant’s performance was recorded to CD and analyzed. Demographic questionnaires …

Adaptive Synchronization Of Chaos For Secure Communication, Manish Pantha

Master's Theses - Daytona Beach

The purpose of this thesis is to study the use of adaptive synchronization of chaos for secure communication. Several non-linear models were studied, the one-dimensional logistic map, two-dimensional coupled logistic map, three dimensional Lorenz systems with and without time delay. Numerical simulation using MATLAB was conducted. The Lorenz system with time delay was studied numerically as well as by testing an analog circuit and comparisons was made between them. It has been pointed out in many research papers that for low-dimensional chaotic processes, once intercepted, the information can be readily extracted, so the interest has been directed to higher dimensional …

Lorentz-Violating Electrostatics And Magnetostatics, Quentin G. Bailey, V. Alan Kostelecký

Publications

Electromagnetostatics experiments show promise for improving existing sensitivities to parity-odd coefficients for Lorentz violation in the photon sector.

Final Report: Review Of The Fits Program: Program Tasks, Goals And Pilot Training Initiatives, Alex Chaparro, Bonnie Lida Rogers, Christopher J. Hamblin

Publications

In 2002 the FAA, academic and industry partners established the FAA/Industry Training Standards (FITS) program whose purpose is to modernize General Aviation (GA) pilot training. The FAA recognized the need to modernize training standards for pilots who would use new avionics technology that integrate the GPS (Global Positioning Systems) with the autopilot along with multifunction displays capable of depicting flight path, weather, terrain and traffic information. These avionics and displays are touted as improving safety by enhancing pilot Situational Awareness and reducing pilot workload. The new technology has highlighted the need for programs to train and certify pilots to use …

Aeroelastic Analysis Of A Flexible Membrane Wing, Isaac Nguri Wanjohi

Master's Theses - Daytona Beach

The focus of this research proposal is the investigation of the aeroelastic effects of a flexible lift augmentation system (LAS) wing. This research involves characterization of the forced vibration response of a wing appendage used to augment short field take off and landing (STOL) operations.

Although flutter theory is now well understood, the LAS presents the complications of a highly deformable airfoil shape as well as larger structural damping values compared to metal wings.

The proposed research will involve derivation of the equations of motion aided by experimental data from nodal excitation of the wing; stiffness and rigidity modeling from …

Modeling Launch Vehicle Success Using Artificial Neural Networks, Jennifer A. Schuck

Master's Theses - Daytona Beach

Expendable launch vehicles in the United States currently have a reliability of 92%. The failures that do occur cost millions of dollars in spacecraft replacement, lost revenue, and other expenses. These costs are passed on in higher insurance rates and launch vehicle price. If the launch outcome of the launch vehicles could be better predicted, the overall cost of launching payloads into space would decrease. This study used artificial neural networks to model the overall launch outcome of a launch vehicle so that the results of a launch could be predicted. Two neural network architectures--MLP and fuzzy ARTMAP--were trained on …

Laser-Assisted Fabrication Of Nmr Resonators, William W. Brey, Susan D. Allen

Mechanical Engineering - Daytona Beach

A detection coil for use in nuclear resonance magnetic (NMR) spectroscopy and a method of manufacture thereof. At least two film layers of material are deposited on an outer surface of a cylindrical tube of dielectric material. The layers are patterned to form a solenoid on the tube. At least one of the deposited materials is a conductor.

Neural Network Fatigue Life Prediction In 7075-T6 Aluminum From Acoustic Emission Data, Emeka Chigozie Ibekwe

Master's Theses - Daytona Beach

The objective of this research was to classify acoustic emission (AE) -data associated with fatigue cracks in aluminum fatigue specimens and to use early cycle life AE data to predict failure in such members. An AE data acquisition system coupled with a Kohonen self organizing map and a back propagation neural network were used to perform the analysis. AE waveforms were recorded during fatigue cycling of twenty-four notched 7075-T6 aluminum specimens using broad-band piezoelectric transducers. A Kohonen self organizing map was used to classify the AE flaw growth signals. The signals were classified into three categories based on their AE …

A New Guidance System For Aircraft Based On Gps, Mukul Mishra

Doctoral Dissertations and Master's Theses

The navigation displays commonly used in aircraft (Course Deviation Indicators), provide only the offset from desired track, leaving the pilot to figure out steering correction necessary to get back on track. This correction, determined by trial and error, adds to the workload, especially in windy conditions. The feasibility of using a new algorithm for providing guidance to the pilots for improved interception and tracking is examined in this thesis. The proposed system employs GPS to calculate the offset from the track as well as the instantaneous ground speed vector, to provide steering information. Thus, precise tracking is possible in real …

Ultimate Strength Prediction In Fiberglass/Epoxy Beams Subjected To Three-Point Bending Using Acoustic Emission And Neural Networks, Michele D. Dorfinan

Master's Theses - Daytona Beach

The research presented herein demonstrates the feasibility of predicting ultimate strengths in composite beams subjected to 3-point bending using a neural network analysis of acoustic emission (AE) amplitude distribution data. Fifteen unidirectional fiberglass/epoxy beams were loaded to failure in a 3-point bend test fixture in an MTS load frame. Acoustic emission data were recorded from the onset of loading until failure. After acquisition, the acoustic emission data were filtered to include only data acquired up to 80 percent of the average ultimate load.

A backpropagation neural network was constructed to predict the ultimate failure load using these AE amplitude distribution …

An Analysis Of Intention Formation As A Function Of Prospective Memory In Air Traffic Controllers, Jennifer Nagle

Master's Theses - Daytona Beach

Prospective memory, or memory for future intents, is an important part of everyone's daily life. Air traffic controllers whose jobs are based in an environment that taxes their memory resources for extended periods of time rely on this type of memory. Controllers objectives often change based on incoming information and the amount of traffic they are controlling. It is important to investigate how controllers form intentions for future events, what processes facilitate retrieval of this information, and establish what influence experience may have. This study proposes to assess controllers in an air traffic scenario by employing a cognitive task analysis …

Instrument Pilot Skill Acquisition In The Early Phases Of Flight Training Using An Advanced Cockpit Display System, Erin E. Accettullo

Master's Theses - Daytona Beach

The purpose of this study was to evaluate the learning curve associated with complex flight behavior for both conventional and synthetic vision systems (SVS). The objective was to assess potential differences in learning curves and subjective workload. Workload data across trials indicated a negative linear trend, with a significantly lower level of workload on the synthetic vision display compared to conventional instruments. Levels of performance were significantly higher in the SVS condition, and revealed a quadratic trend, supporting the hypothesis that skill acquisition occurs faster while training with the SVS. These differences in learning and workload curves have implications for …

Improving The Capability Of Preliminary Aircraft Design Methodology By Incorporating Numerical Methods Into Segments Of A Proven Statistical Method, Igor Lebovic

Master's Theses - Daytona Beach

The purpose of this study was to identify any potential limitations of Roskam’s statistical aircraft flight performance estimation method, and to provide processes capable of improving those limitations. This project was conducted in collaboration with Diamond Aircraft Industries, and as any other general aviation manufacturer with limited time, manpower, and financial resources, Diamond wants the new process to be time and cost-effective. Presented in this study is a computational alternative that combines the speed and accuracy of low-order panel methods with the fully-coupled viscous/inviscid interaction method from the ISES code that was developed by Drela and Giles. Its benefit is …

Final Report: A Comparison Of Three Evaluative Techniques For Validating Maintenance Documentation, Alex Chaparro, Bonnie Rogers, Chris Hambllin, Barbara Chaparro

Publications

Surveys and interviews reveal that general aviation manufacturers rely on user[s] to identify problems in maintenance documentation with corrections typically initiated in response to users-reported problems found in the manual;. This investigation compares techniques that manufacturers can use to improve the quality of the maintenance documentation developed by technical writing groups. The techniques, User Performance and Cognitive Walkthrough, were used to identify problems in aircraft maintenance documentation.