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Full-Text Articles in Engineering
The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco
The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco
Libraries' Newsletters
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Six Degree Of Freedom Dynamic Modeling Of A High Altitude Airship And Its Trajectory Optimization Using Direct Collocation Method, Pradens Pierre-Louis
Six Degree Of Freedom Dynamic Modeling Of A High Altitude Airship And Its Trajectory Optimization Using Direct Collocation Method, Pradens Pierre-Louis
Electronic Theses and Dissertations
The long duration airborne feature of airships makes them an attractive solution for many military and civil applications such as long-endurance surveillance, reconnaissance, environment monitoring, communication utilities, and energy harvesting. To achieve a minimum energy periodic motion in the air, an optimal trajectory problem is solved using basic direct collocation methods. In the direct approach, the optimal control problem is converted into a nonlinear programming (NLP). Pseudo-inverse and several discretization methods such as Trapezoidal and Hermite-Simpson are used to obtain a numerical approximated solution by discretizing the states and controls into a set of equal nodes. These nodes are approximated …
Modeling Of Flow Generated Sound In A Constricted Duct At Low Mach Number Flow, Peshala Thibbotuwawa Gamage
Modeling Of Flow Generated Sound In A Constricted Duct At Low Mach Number Flow, Peshala Thibbotuwawa Gamage
Electronic Theses and Dissertations
Modelling flow and acoustics in a constricted duct at low Mach numbers is important for investigating many physiological phenomena such as phonation, generation of arterial murmurs, and pulmonary conditions involving airway obstruction. The objective of this study is to validate computational fluid dynamics (CFD) and computational aero-acoustics (CAA) simulations in a constricted tube at low Mach numbers. Different turbulence models were employed to simulate the flow field. Models included Reynolds Average Navier-Stokes (RANS), Detached eddy simulation (DES) and Large eddy simulation (LES). The models were validated by comparing study results with laser doppler anemometry (LDA) velocity measurements. The comparison showed …
Simultaneous Imaging Of The Diatomic Carbon And Methylidyne Species Radicals For The Quantification Of The Fuel To Air Ratio From Low To High Pressure Combustion, Jonathan Reyes
Electronic Theses and Dissertations
The radical intensity ratio of the diatomic carbon to methylidyne was characterized at initial pressures up to 10 bar using certified gasoline of 93% octane. This gasoline was selected due to its availability as a common fuel. The characterization of the radical intensity ratio of gasoline at elevated pressures enabled the creation of a calibration map of the equivalence ratio at engine relevant conditions. The proposed calibration map acts as a feedback loop for a combustor. It allows for the location of local rich and lean zones. The local information acquired can be used as an optimization parameter for injection …
Combustion Of 1,3-Butadiene Behind Reflected Shocks, Joseph Lopez
Combustion Of 1,3-Butadiene Behind Reflected Shocks, Joseph Lopez
Electronic Theses and Dissertations
The chemical kinetics of 1,3-butadiene (1,3-C4H6) are important because 1,3-butadiene is a major intermediate during the combustion of real fuels. However, there is only limited information on the chemical kinetics of 1,3-butadiene combustion, which has applications in several combustion schemes that are currently being developed, including spark-assisted homogeneous charge compression ignition and fuel reformate exhaust gas recirculation. In the present work, the ignition delay times of 1,3-butadiene mixtures has been investigated using pressure data. Oxidation of 1,3-butadiene/oxygen mixtures diluted in argon or nitrogen at equivalence ratios (Φ) of 0.3 behind reflected shock waves has been studied at temperatures ranging from …
Characteristics Of Hydrogel-Wetted Thin Films, James Owens
Characteristics Of Hydrogel-Wetted Thin Films, James Owens
Electronic Theses and Dissertations
The meniscus region of a thin film is known to have high heat transfer properties due to high evaporation rates and activation of latent heat. The region known as the thin film meniscus (δfilm lt& 2 µm ) can account for more than half of the total heat transfer of a droplet or film. This study focuses on the potential elongation and curvature amplification of the thin film meniscus region by the implementation of a layer of high hydrogen bonding (hydrogel) film on which the liquid meniscus is built. Forced wetting via liquid propagation though this hydrogel layer in the …
Development And Implementation Of A Streamlined Process For The Creation And Mechanization Of Negative Poisson's Ratio Meso-Scale Patterns, Matthew Shuler
Development And Implementation Of A Streamlined Process For The Creation And Mechanization Of Negative Poisson's Ratio Meso-Scale Patterns, Matthew Shuler
Electronic Theses and Dissertations
This thesis focuses on the development a streamlined process used to create novel meso-scale pattern used to induce negative Poisson's ratio (NPR) behavior at the bulk scale. This process includes, the development, optimization, and implementation of a candidate pattern. Currently, the majority of NPR structures are too porous to be utilized in conventional applications. For others, manufacturing methods have yet to realize the meso-scale pattern. Consequently, new NPR meta-materials must be developed in order to confer transformative thermomechanical responses to structures where transverse expansion is more desirable than contraction. For example, materials at high temperature. Additionally, patterns that take into …
Timoshenko Beam Viscous Damping Model For Spacecraft Cabling Dynamics, Brandi Mcpherson
Timoshenko Beam Viscous Damping Model For Spacecraft Cabling Dynamics, Brandi Mcpherson
Electronic Theses and Dissertations
With the increasing data handling and power requirements of today's spacecraft, accurately modeling the effects of cabling on spacecraft structural dynamics has become an increasingly important part of the design process. During testing, spacecraft cabling produces a damping effect on the system dynamics; however, current models often overpredict this response in higher frequency modes and produce unrealistic damping values. Previous models incorporated structural and viscous damping terms into Euler-Bernoulli and shear beams; this thesis presents a viscous damping model for Timoshenko beams that can accurately capture the effects of both spacecraft wiring and harnesses during the design phase. Damping in …
Design And Modeling Of A Heat Exchanger For Porous Combustor Powered Steam Generators In Automotive Industry, Apratim Dasgupta
Design And Modeling Of A Heat Exchanger For Porous Combustor Powered Steam Generators In Automotive Industry, Apratim Dasgupta
Electronic Theses and Dissertations
A major challenge faced by automobile manufacturers is to achieve reduction of particulate emission to acceptable standards, as the emission standards become more and more stringent. One of the ecologically friendly options to reduce emissions is to develop external combustion in a steam engine as a replacement of the internal combustion engine. There are multiple factors, other than pollution that need to be considered for developing a substitute for Internal Combustion Engine, like specific power, throttle response, torque speed curve, fuel consumption and refueling infrastructure. External combustion in a steam engine seems to be a bright idea, for a cleaner …
Characterization Of Mechanical Properties In Nanoparticle Reinforced Hybrid Carbon Fiber Composites Using Photoluminescence Piezospectroscopy, Sanjida Jahan
Electronic Theses and Dissertations
Carbon fiber composites have become popular in aerospace structures and applications due to their light weight, high strength, and high performance. Hybrid carbon fiber reinforced polymer (HCFRP) composites with alumina nanoparticles reinforcement display improved material properties such as fracture toughness, resistance to crack propagation and improved fatigue life. However, homogeneous dispersion of nanoscale materials in the matrix is important for even distribution of the improved properties. Implementing silane coupling agents (SCAs) improves dispersion by acting as a bridge between organic and inorganic materials, which increases interfacial strength and decreases sedimentation by bonding the particulate filler to the fiber reinforcement. This …
Atmospheric Entry, Dillon A. Martin
Atmospheric Entry, Dillon A. Martin
Honors Undergraduate Theses
The development of atmospheric entry guidance methods is crucial to achieving the requirements for future missions to Mars; however, many missions implement a unique controller which are spacecraft specific. Here we look at the implementation of neural networks as a baseline controller that will work for a variety of different spacecraft. To accomplish this, a simulation is developed and validated with the Apollo controller. A feedforward neural network controller is then analyzed and compared to the Apollo case.
Mid-Infrared Absorption Spectrometer For Multi-Species Detection Using Leds For Space Applications: Development And Flight Testing, Michael Villar
Mid-Infrared Absorption Spectrometer For Multi-Species Detection Using Leds For Space Applications: Development And Flight Testing, Michael Villar
Electronic Theses and Dissertations
As commercial space travel expands, the need for specialized instrumentation to ensure the safety of crew and cargo becomes increasingly necessary. Both the Federal Aviation Administration (FAA) and pioneers in the space tourism industry have expressed an interest in a robust, low cost, and low power consumption sensor to measure atmospheric composition aboard spacecraft. To achieve this goal a time-resolved NDIR absorption sensor that measures transient levels of gaseous carbon dioxide (CO2) and carbon monoxide (CO) was developed. The developed sensor has a wide range of applications applicable to the growing needs of industry, from monitoring CO and CO2 levels …
A Flexible Physics-Based Lifing Method For Metals Under Creep And Thermomechanical Fatigue, Firat Irmak
A Flexible Physics-Based Lifing Method For Metals Under Creep And Thermomechanical Fatigue, Firat Irmak
Electronic Theses and Dissertations
This thesis focuses on the development of a flexible, physics-based life prediction approach for steels under complex conditions. Low alloy steels continue to be the materials of choice for large turbomachinery structures experiencing high temperatures for long durations. There has been significant advancement in the research of modern alloys; furthermore, these materials are continue to be utilized in boilers, heat exchanger tubes, and throttle valve bodies in both turbomachinery and pressure-vessel/piping applications. The material 2.25Cr-1Mo is studied in the present work. The resistance of this alloy to deformation and damage under creep and/or fatigue at elevated temperatures make it appropriate …
Implementation Of Optical Interferometry And Spectral Reflectometry For High Fidelity Thin Film Measurements, Armando Arends-Rodriguez
Implementation Of Optical Interferometry And Spectral Reflectometry For High Fidelity Thin Film Measurements, Armando Arends-Rodriguez
Electronic Theses and Dissertations
An in-house reflectometer/interferometer has been built to investigate the varying curvature and thickness profiles in the contact line region of air, acetone, iso-octane, ethanol, and water on various types of substrates. Light intensity measurements were obtained using our reflectometer/interferomter and then analyzed in MATLAB to produce thickness and curvature profiles. The apparatus is based on the principle of a reflectometer, consisting of different optical elements, probe, light source, and spectrometer. Our reflectometer/interferomter takes measurements in the UV-Vis-IR range (200nm-1000nm). This range is achieved by using a light source that has both a deuterium light (190nm-800nm), a tungsten halogen light (400nm-1100nm), …