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Graduate Theses, Dissertations, and Problem Reports (ETD)

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Articles 61 - 64 of 64

Full-Text Articles in Aerospace Engineering

Thermal-Fatigue And Thermo-Mechanical Equivalence For Transverse Cracking Evolution In Laminated Composites, Javier Cabrera Barbero Jan 2018

Thermal-Fatigue And Thermo-Mechanical Equivalence For Transverse Cracking Evolution In Laminated Composites, Javier Cabrera Barbero

Graduate Theses, Dissertations, and Problem Reports (ETD)

Carbon fiber reinforced plastics (CFRP) are potential materials for many aerospace and aeronautical applications due to their high specif strength/weight and a low coeffcient of thermal expansion (CTE) resulting in a high long-term stability. Among candidate structures, the re-entry reusable launch vehicles (RLV), the fuel oxidant storage and transportation at cryogenic temperature, space satellites, and aircraft structure (frame, wings, etc...) can be highlighted. However, CFRP are prone to internal damage as a result of high residual stresses and thermal fatigue loading. In this study, micro-cracking damage evolution in laminated composites subjected to monotonic cooling and thermal cyclic loads is developed …


Control Design And Performance Analysis For Autonomous Formation Flight Experiments, Caleb M. Rice Jan 2014

Control Design And Performance Analysis For Autonomous Formation Flight Experiments, Caleb M. Rice

Graduate Theses, Dissertations, and Problem Reports (ETD)

Autonomous Formation Flight is a key approach for reducing greenhouse gas emissions and managing traffic in future high density airspace. Unmanned Aerial Vehicles (UAV’s) have made it possible for the physical demonstration and validation of autonomous formation flight concepts inexpensively and eliminates the flight risk to human pilots. This thesis discusses the design, implementation, and flight testing of three different formation flight control methods, Proportional Integral and Derivative (PID); Fuzzy Logic (FL); and NonLinear Dynamic Inversion (NLDI), and their respective performance behavior. Experimental results show achievable autonomous formation flight and performance quality with a pair of low-cost unmanned research fixed …


Fault-Tolerant Trajectory Tracking Of Unmanned Aerial Vehicles Using Immunity-Based Model Reference Adaptive Control, Brenton K. Wilburn Jan 2014

Fault-Tolerant Trajectory Tracking Of Unmanned Aerial Vehicles Using Immunity-Based Model Reference Adaptive Control, Brenton K. Wilburn

Graduate Theses, Dissertations, and Problem Reports (ETD)

This dissertation presents the design, development, and simulation testing of an adaptive trajectory tracking algorithm capable of compensating for various aircraft subsystem failures and upset conditions. A comprehensive adaptive control framework, here within referred to as the immune model reference adaptive control (IMRAC) algorithm, is developed by synergistically merging core concepts from the biologically- inspired artificial immune system (AIS) paradigm with more traditional optimal and adaptive control techniques. In particular, a model reference adaptive control (MRAC) algorithm is enhanced with the detection and learning capabilities of a novel, artificial neural network augmented AIS scheme. With the given modifications, the MRAC …


Analytical Solution To The Wave Equation With Discrete Pressure Sources: A Model For The Rijke Tube, Eduardo G. Perez Jan 2008

Analytical Solution To The Wave Equation With Discrete Pressure Sources: A Model For The Rijke Tube, Eduardo G. Perez

Graduate Theses, Dissertations, and Problem Reports (ETD)

Despite of having been studied for several decades the phenomena of combustion instabilities are not well understood. Pressure waves due to the combustion instabilities can become violent being detrimental for both the performance and combustor life. A good prediction of the pressure distribution inside the combustor is important in order to prevent theoccurrence of this phenomenon. In this work a technique for solving the wave equation with discrete sources (or sinks) using the Green's functions was developed. One and two-dimensional approaches for cylindrical and Cartesian coordinates withconstant speed of sound were solved. Also the case of one-dimensional axially varying temperature …