Aerospace Engineering Commons^™

Optimal Neuro-Controller Synthesis For Impulse-Driven System, Xiaohua Wang, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a new controller design technique for systems driven with impulse inputs. Necessary conditions for optimal impulse control are derived. A neural network structure to solve the resulting equations is presented. The solution concepts are illustrated with a few example problems that exhibit increasing levels of difficulty. Two linear problems-one scalar and one vector-and a benchmark nonlinear problem-Van Der Pol oscillator-are used as case studies. Numerical results show the efficacy of the new solution process for impulse driven systems. Since the theoretical development and the design technique are free from restrictive assumptions, this technique is applicable to many …

Robust/Optimal Temperature Profile Control Of A High-Speed Aerospace Vehicle Using Neural Networks, Vivek Yadav, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approximate dynamic programming (ADP)-based suboptimal neurocontroller to obtain desired temperature for a high-speed aerospace vehicle is synthesized in this paper. a 1-D distributed parameter model of a fin is developed from basic thermal physics principles. ldquoSnapshotrdquo solutions of the dynamics are generated with a simple dynamic inversion-based feedback controller. Empirical basis functions are designed using the ldquoproper orthogonal decompositionrdquo (POD) technique and the snapshot solutions. a low-order nonlinear lumped parameter system to characterize the infinite dimensional system is obtained by carrying out a Galerkin projection. an ADP-based neurocontroller with a dual heuristic programming (DHP) formulation is obtained with a …

Near Optimal Output-Feedback Control Of Nonlinear Discrete-Time Systems In Nonstrict Feedback Form With Application To Engines, Peter Shih, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The controller includes an observer for estimating states and the outputs, critic, and two action NNs for generating virtual, and actual control inputs. The critic approximates certain strategic utility function and the action NNs are used to minimize both the strategic utility function and their outputs. All NN weights adapt online towards minimization of a performance index, utilizing gradient-descent based rule. …

Incorporating The Effects Of Magnetic Saturation In A Coupled-Circuit Model Of A Claw-Pole Alternator, Hua Bai, Steven Pekarek, Jerry L. Tichenor, Walter Eversman, Duane J. Buening, Gregory R. Holbrook, Ronald J. Krefta

Electrical and Computer Engineering Faculty Research & Creative Works

A method of representing the effects of magnetic saturation in a coupled-circuit model of a claw-pole alternator is presented. In the approach considered, the airgap flux density produced by each winding is expressed as a function of magnetic operating point. A challenge in the implementation is that the airgap flux densities consist of several significant harmonics, each of which changes at a distinct rate as iron saturates. Despite this complication, it is shown that relatively simple measurements can be used to determine model parameters. The model is implemented in the analysis of several alternator/rectifier systems using a commercial state-model-based circuit …

Neural Network Controller Development And Implementation For Spark Ignition Engines With High Egr Levels, Jonathan B. Vance, Atmika Singh, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

Past research has shown substantial reductions in the oxides of nitrogen (NOx) concentrations by using 10% -25% exhaust gas recirculation (EGR) in spark ignition (SI) engines (see Dudek and Sain, 1989). However, under high EGR levels, the engine exhibits strong cyclic dispersion in heat release which may lead to instability and unsatisfactory performance preventing commercial engines to operate with high EGR levels. A neural network (NN)-based output feedback controller is developed to reduce cyclic variation in the heat release under high levels of EGR even when the engine dynamics are unknown by using fuel as the control input. A separate …

Supersonic Crossflow Visualization Using The University Of Central Florida Supersonic Wind Tunnel, Peter Himmerich

Electronic Theses and Dissertations

The next generation air breathing engine that would enable an alternative to conventional air travel or suborbital flight is the supersonic ramjet engine (SCRAM) which requires a highly accelerated rate of fuel mixing and combustion. For this type of engine, one of the improvement opportunities lies in the injection of the fuel into the supersonic flow inside the combustor. In order to determine the flow field that develops when a sonic jet of secondary gas is injected into a supersonic free stream, a dedicated test section was developed which was attached to the existing supersonic wind tunnel at the University …

Manufacturing Of Glass Ribbon Reinforced Transparent Composites Using The Autoclave Process, Josef Patrick Seale

Masters Theses

"Clear transparent panels have many applications ranging from windows on an aircraft to protective safety guards on industrial equipment. Glass ribbon reinforced transparent composites are light weight, load bearing and have a high impact resistance.

A transparent composite is based on the concept of matching the refractive index of the glass ribbon with that of a resin system. It is not necessary that the resin refractive index match the glass refractive index before the cure cycle, only that the refractive indexes match after curing.

Transparent composites have a high impact resistance that would be mechanically ideal for aircraft windows and …

Low-Thrust Control Of A Lunar Orbiter, Nathan Harl

Masters Theses

"This thesis presents a method for maintaining a long-term lunar Sun-synchronous orbit using continuous low-thrust hardware. The control method is developed using optimal control theory, which involves controlling a system through the minimization of a desired cost function"--Abstract, page iii.

Refrigerant-Based Propulsion System For Small Spacecraft, Carl Reiner Seubert

Masters Theses

"The MR SAT spacecraft under development at UMR requires a propulsion system that can be utilized to perform orbital maneuvers and three-axis attitude control to complete its mission objective of conducting spacecraft formation flight. This thesis documents the research, analysis design and development of the cold gas propulsion system that was integrated on the MR SAT spacecraft"--Abstract, page iii.

Computational Study Of Flow Over Elliptic Airfoils For Rotor/Wing Unmanned Aerial Vehicle Applications, Timothy William Assel

Masters Theses

"The purpose of this study will be to conduct a parametric investigation on the performance of elliptic airfoils for Rotor/Wing Unmanned Aerial Vehicles. The objective of this study is to conduct a two-dimensional, aerodynamic analysis on a various elliptic airfoil parameters, compare the reults of the analysis with theoretical predictions and experimental results, and evaluate handling and performance characteristics of Rotor/Wing UAVs during hover, transition, and forward flight"--Abstract, page iii.

Magnetohydrodynamic Power Generation In A Scramjet Using A Post Combustor Generator, Nathan Lee Mundis

Masters Theses

"A scramjet with a post combustor MHD generator is examined. A quasi-one-dimensional model is developed to calculate the flow path from tip to tail. The model includes losses due to combustion irreversibility, incomplete combustion, chemically reacting flow, friction, MHD losses, and nozzle plume modeling. Flight Mach number, magnetic field strength, gas conductivity, MHD load factor, and MHD generator expansion angle are all varied in order to assess their effects on MHD power generated and thrust lost in the engine. The trends produced through the above variations are summarized in a set of model-fit equations. It is concluded that a post …

A Guide To The Establishment Of A University Satellite Program, Abbie Marie Stewart

Masters Theses

"The UMR SAT team was formed at the University of Missouri-Rolla to design and build microsatellites. The team competed against ten other universities in the Nanosat 4 competition hosted by the Air Force Office of Scientific Research, the Air Force Research Laboratory, and the American Institute of Aeronautics and Astronautics. This document, written by the Chief Engineer, is a description of the process used by the UMR SAT team to develop a successful satellite program. Included in the document are methods based on systems engineering for developing a mission, a discussion of team organization and recruitment, and lessons learned during …

Configuration, Manufacture, Assembly, And Integration Of A University Microsatellite, Lori Ann Ziegler

Masters Theses

"The Space Systems Engineering Team at the University of Missouri-Rolla (UMR), in conjunction with a number of Air Force, NASA, and industry mentors, is working toward the design, development, and launch of its first satellite, UMR SAT (University of Missouri-Rolla Satellite). This thesis documents the design of the UMR SAT satellites, specifically focusing attention on the layout of all components, component boxes designed for containment and protection from electromagnetic interference and the attachment of components inside the boxes and the boxes to the structure. This thesis also discusses the development of UMR SAT with challenges faced in manufacturing and prototyping …

Controls Algorithm For A Satellite Using Earth's Magnetic Field: Orbit Maneuvers And Attitude Positioning, Karthik Ganesh

Electronic Theses and Dissertations

This document describes the design, analysis of Orbit Maneuvers and Attitude Control for NanoSat class satellites, which uses an electro-magnetic force controller which was proposed by the Florida Space Institute (FSI). Orbit Maneuvering and the Attitude Control System (ACS) play a very important role for the success of this mission, as that can allow making the satellite go to the desired orbit as well do the sun pointing of the solar arrays with su¢ cient accuracy to achieve desired power levels. The primary mission would be to attain attitude stabilization using the torque from the coils. This is also used …

Addressing Student Retention In Engineering And Engineering Technology Through The Use Of A Multidisciplinary Freshman Course, Anthony Dean, Bonita Anthony, Linda Vahala

Engineering Technology Faculty Publications

The Engineering Fundamentals Division of the Batten College of Engineering and Technology (BCET) at Old Dominion University administers a freshman engineering course sequence, along with four engineering departments (Mechanical Engineering, Civil and Environmental Engineering, Aerospace Engineering, and Electrical and Computer Engineering) and the Department of Engineering Technology (which offers degrees in Mechanical Engineering Technology, Civil Engineering Technology and Electrical Engineering Technology). The two course sequence, Exploring Engineering and Technology I and II, involve the five departments in teaching at least one five week module in each of the two courses. Each department generally involves the students in a basic design …

Acoustic Emission Detection And Prediction Of Fatigue Crack Propagation In Composite Patch Repairs Using Neural Networks, Navdeep Singh, Navrag Singh, Anthony Chukwujekwu Okafor

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor …

Determination Of Laser Absorption Coefficients Of Gas Mixtures Using An Ab Initio Md Model, Zhi Liang, Hai-Lung Tsai, Lan Jiang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In an Effort to Study the Laser Induced Dissociation of Gas Mixtures for an Ongoing Research Project on Diamond Thin Film Coating using Multiple Lasers, It is Necessary to Determine the Absorption Coefficient of Laser Energy by CO2 Gas. an Ab Initio Molecular Dynamics (AIMD) Model is Used to Determine the Laser Absorption Coefficient of CO2 Gas as a Function of Laser Wavelength and Gas Temperature. the Translational, Rotational, and Vibration Motions of Molecules Are All Taken into Account in Our Model. the Intra-Molecular Potential Energy is Obtained by Solving the Kohn-Sham Equation. the Projector-Augmented Wave (PAW) Exchange-Correlation Potential Function …

Shock-Tube Investigation Of Ignition Delay Times Of Blends Of Methane And Ethane With Oxygen, Brian Christopher Walker

Electronic Theses and Dissertations

The combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the combustion of blends of methane and ethane is limited to ratios that recreate typical natural gas compositions (up to ~20% ethane molar concentration). The goal of this study was to …

Modeling Redox-Based Magnetohydrodynamics In Three-Dimensional Microfluidic Channels, Hussameddine S. Kabbani, Aihua Wang, Xiaobing Luo, Shizhi Qian

Mechanical Engineering Faculty Research

RedOx-based magnetohydrodynamic MHD[1] flows in three-dimensional microfluidic channels are investigated theoretically with a coupled mathematical model consisting of the Nernst-Planck equations for the concentrations of ionic species, the local electroneutrality condition for the electric potential, and the Navier-Stokes equations for the flow field. A potential difference is externally applied across two planar electrodes positioned along the opposing walls of a microchannel that is filled with a dilute RedOx electrolyte solution, and a Faradaic current transmitted through the solution results. The entire device is positioned under a magnetic field which can be provided by either a permanent magnet or an electromagnet. …

Development Of A Coupled Fluid/Structure Aeroelastic Solver With Applications To Vortex Breakdown-Induced Twin Tail Buffeting, Steven J. Massey

Mechanical & Aerospace Engineering Theses & Dissertations

Simulation of tail buffet is studied for several delta wing-vertical tail configurations. Flow conditions are chosen such that the wing primary-vortex cores experience vortex breakdown and the resulting turbulent wake flow impinges on the vertical tail. The dimensions and material properties of the vertical tails are chosen such that the deflections are large enough to insure interaction with the flow, and the natural frequencies are high enough to facilitate a practical computational solution. This multi-disciplinary problem is solved sequentially for the fluid flow, the elastic deformations and the grid displacements. The flow is simulated by time accurately solving the laminar, …

Propulsion Enhancement Contributions To The Performance Of Space Launch Vehicles, Russell H. Edwards

Mechanical & Aerospace Engineering Theses & Dissertations

A research effort has been undertaken to investigate critical aspects of launch vehicle performance as affected by variations in specific launch vehicle parameters. The major portion of the study involves liquid propellant systems. However, since solid propellant systems also play a role in today's launch systems, a representative solid-propellant launch vehicle has also been analyzed. The research undertaken determined that the payload capability of a space launch vehicle, or, conversely, the vehicle total liftoff mass, is highly sensitive to the manner in which the space launch vehicle is staged. The research has led to the development and programming of a …

Sonic Boom Focusing Prediction And Delta Wing Shape Optimization For Boom Mitigation Studies, Nitin Khasdeo

Mechanical & Aerospace Engineering Theses & Dissertations

Supersonic travel over land would be a reality if new aircraft are designed such that they produce quieter ground sonic booms, no louder than 0.3 psf according to the FAA requirement. An attempt is made to address the challenging goal of predicting the sonic boom focusing effects and mitigate the sonic boom ground over pressure for delta wing geometry.

Sonic boom focusing is fundamentally a nonlinear phenomenon and can be predicted by numerically solving the nonlinear Tricomi equation. The conservative time domain scheme is developed to carry out the sonic boom focusing or super boom studies. The computational scheme is …