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Articles 151 - 180 of 196
Full-Text Articles in Aerospace Engineering
Use Of Variable Incidence Angle For Glide Slope Control Of Autonomous Parafoils, Nathan Slegers, Eric Beyer, Mark Costello
Use Of Variable Incidence Angle For Glide Slope Control Of Autonomous Parafoils, Nathan Slegers, Eric Beyer, Mark Costello
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Strictly speaking, most autonomous parafoil and payload systems possess only lateral control, achieved by right and left parafoil brake deflection. An innovative technique to achieve direct longitudinal control through incidence angle changes is reported. Addition of this extra control channel requires simple rigging changes and an additional servoactuator. The ability of incidence angle to alter the glide slope of a parafoil and payload aircraft is demonstrated through a flight-test program with a microparafoil system. Results from the flight-test program are synthesized and integrated into a six degree-of-freedom simulation. The simulation model is subsequently used to assess the utility of glide …
Pid Parameter Optimization Of An Uav Longitudinal Flight Control System, Kamran Turkoglu, Ugur Ozdemir, Melike Nikbay, Elbrous Jafarov
Pid Parameter Optimization Of An Uav Longitudinal Flight Control System, Kamran Turkoglu, Ugur Ozdemir, Melike Nikbay, Elbrous Jafarov
Faculty Publications
In this paper, an automatic control system design based on Integral Squared Error (ISE) parameter optimization technique has been implemented on longitudinal flight dynamics of an UAV. It has been aimed to minimize the error function between the reference signal and the output of the plant. In the following parts, objective function has been defined with respect to error dynamics. An unconstrained optimization problem has been solved analytically by using necessary and sufficient conditions of optimality, optimum PID parameters have been obtained and implemented in control system dynamics.
The Role Of Diffusive Transport On Low And Intermediate Temperature Hydrocarbon Oxidation: Numerical Simulations Using The Wang-Mou Mechanism, Howard Pearlman, Michael R. Foster
The Role Of Diffusive Transport On Low And Intermediate Temperature Hydrocarbon Oxidation: Numerical Simulations Using The Wang-Mou Mechanism, Howard Pearlman, Michael R. Foster
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
The spatio-temporal temperature and species concentration distributions associated with low and intermediate temperature hydrocarbon oxidation are computed using a global thermo kinetic scheme augmented with diffusive transport. The scheme used for the computations was proposed by Wang and Mou and is extended to include diffusion of species and heat. The conservation equations for species and energy are then derived and solved for a one-dimensional and an axisymmetric, spherical domain for temperatures ranging from 540 to 660 Kat subatmospheric pressures. The predictions are then used to develop ignition diagrams for different Lewis ( Le) numbers. Increasing Le is found to promote …
The Role Of Diffusive Transport On Low And Intermediate Temperature Hydrocarbon Oxidation: Closed Reactor Experiments Using Equimolar N-Butane + Oxygen Premixtures At Reduced-Gravity, Howard Pearlman, Michael R. Foster
The Role Of Diffusive Transport On Low And Intermediate Temperature Hydrocarbon Oxidation: Closed Reactor Experiments Using Equimolar N-Butane + Oxygen Premixtures At Reduced-Gravity, Howard Pearlman, Michael R. Foster
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
Experiments were conducted in a closed, spherical reactor aboard NASA's KC-135 reduced-gravity aircraft using an equimolar n-C4H10 + 0 2 premixture ( Le = 1.3) at subatmospheric · pressures to compliment model predictions and further explore the reactive-diffusive structure of cool flames and ignitions. The pressure and radial temperature histories were recorded and analyzed for different initial conditions. In addition, the visible light emission from excited formaldehyde was recorded using an intensified video camera and was observed to be radially symmetric in all cases. Unexpectedly, however, the measured temperature distributions during (and after the passage of) the cool flames and …
Extensible Simulation Of Planets And Comets, Natalie Anne Wiser-Orozco
Extensible Simulation Of Planets And Comets, Natalie Anne Wiser-Orozco
Theses Digitization Project
The aim of this research was to create an extensible simulator that will not only calculate the trajectories of planets and comets using a numerical method, but be able to graphically simulate them. The significance of this project is its ability to be a useful tool to computer scientists, astronomers, and physicists by determining how an arbitrary set of celestial bodies interact with one another. It allows definition of bodies that belong to a system, and creates a graphical simulation of them based on their specific properties. Ideas are then easily conveyed not only to colleagues, but to the public …
Photoelectric Charging By Ultraviolet Light Of A Lunar Dust Simulant In A Microgravity Environment, Microgravity Research Team 2008
Photoelectric Charging By Ultraviolet Light Of A Lunar Dust Simulant In A Microgravity Environment, Microgravity Research Team 2008
Reports and Proposals
No abstract provided.
The 2008 Strategy For United States Air Force Intelligence, Surveillance And Reconnaissance, United States Air Force
The 2008 Strategy For United States Air Force Intelligence, Surveillance And Reconnaissance, United States Air Force
United States Air Force: Publications
Since the inception of the Air Force, our Nation has asked us to create aerospace forces that no adversary could "out gun" under any circumstances. For over six decades we have answered that call. Now the Nation demands that we also create a set of capabilities that no adversary can "out smart" in the future. This strategy outlines our response in the realm of Intelligence, Surveillance and Reconnaissance (ISR).
This is a new document that specifies why and how our Air Force will provide the capacity and capability for full spectrum ISR. It provides the foundation for enabling our air …
An Integer Programming Approach To Support The Us Air Force’S Air Mobility Network, Corbin G. Koepke, Andrew P. Armacost, Cynthia Barnhart, Stephan E. Kolitz
An Integer Programming Approach To Support The Us Air Force’S Air Mobility Network, Corbin G. Koepke, Andrew P. Armacost, Cynthia Barnhart, Stephan E. Kolitz
United States Air Force: Publications
The United States Air Force’s air mobility command is responsible for creating a schedule and executing that schedule for a large-scale air mobility network that encompasses aircraft with prioritized missions. Aerial ports (airports) can process or park a maximum number of aircraft, called the maximum on ground (MOG). As the schedule changes due to disruptions, such as equipment failure or weather, the MOG constraint can cause the new schedule to be infeasible. Traditionally, re-planning the channel route schedule to adhere to MOG constraints has been a manual process that usually stops after the first feasible set of changes is found, …
Semi-Analytical Complex Variable Based Stochastic Finite Element Method, Weiya Jin
Semi-Analytical Complex Variable Based Stochastic Finite Element Method, Weiya Jin
Mechanical and Aerospace Engineering Dissertations - Archive
The stochastic finite element method (SFEM) is an approach that allows an analyst to define material, load, and geometry parameters as random variables to represent uncertainty in an engineering problem. The method is then used to estimate the probability of exceeding specified performance thresholds. A necessary ingredient for this analysis is consistent, accurate and efficient algorithms for computing finite element response sensitivities. In this work, the semi-analytical complex variable method (SACVM) is introduced as a method for computing accurate response sensitivities of stochastic models. The SACVM incorporates the complex variable method (CVM) with the semi-analytical method (SAM). It takes advantage …
Effects Of Edge Distance, Hole Size Ratio And Hole Spacing On Peak Stresses Of Composite Laminate With Multiple Holes, Manishkumar Kheradiya
Effects Of Edge Distance, Hole Size Ratio And Hole Spacing On Peak Stresses Of Composite Laminate With Multiple Holes, Manishkumar Kheradiya
Mechanical and Aerospace Engineering Theses - Archive
Unlike isotropic material, the stress distribution of laminate with a hole varies with its size, its material properties and fiber orientations of each layer. Moreover, presence of a hole in the neighborhood of another hole may also affect their stress distribution, too. The major objective of this study is to determine stress distribution of finite width laminated composite having multiple holes. The effect of stress concentration due to presence of holes in each angle ply of laminated composite is a focus of this study. Three dimensional finite element models are developed to determine the stress distribution in laminate using commercial …
Characterization And Cooling Capacity Enhancement Of A Porous Ceramic Wick Based Coldplate, Mauricio Adrian Salinas
Characterization And Cooling Capacity Enhancement Of A Porous Ceramic Wick Based Coldplate, Mauricio Adrian Salinas
Mechanical and Aerospace Engineering Dissertations - Archive
Current passive cooling methods of aerospace and military, high heat-flux electronics include the use of thermal planes made of exotic metal alloys, which have been designed, at a great expense, to have high thermal conductivity and low density (i.e. light weight). Also, phase change modules composed of a metal matrix saturated with a solid phase change material are being employed for systems requiring a transient cooling scheme such as expendable weapons. This method requires the heat to be transferred from the source location, through the metal matrix (typically a porous aluminum foam), to the available phase change material. Preliminary empirical …
Thermal Design Optimization Of Internally Cooled Turbine Blades, James Daniel Ruiz
Thermal Design Optimization Of Internally Cooled Turbine Blades, James Daniel Ruiz
Mechanical and Aerospace Engineering Theses - Archive
This paper outlines the use of Computational Fluid Dynamics (CFD) and Genetic Algorithm (GA) Optimization to enhance the design of a 3-dimensional internally cooled turbine blade. The optimization code utilizes principles of Genetic Algorithms to optimize (i.e. minimize) the integrated heat flux through the turbine blade. The optimization is accomplished by adjusting the size and position (within pre-determined constraints) of cooling passages internal to the turbine blade. Starting with an aerodynamically optimized airfoil shape, cooling passage designs are generated by the optimization process and coupled with boundary and airfoil domains. The analysis becomes a Conjugate Heat Transfer (CHT) problem analyzing …
Development Of Spectral And Wavelet Time-Of-Flight Methods For Propagating Shock And Detonation Waves, Alfredo Albert Ortiz
Development Of Spectral And Wavelet Time-Of-Flight Methods For Propagating Shock And Detonation Waves, Alfredo Albert Ortiz
Mechanical and Aerospace Engineering Theses - Archive
An accurate time delay estimate for a propagating disturbance, including an estimate of its uncertainty, is important in many areas of science. Several techniques were developed for determining the propagation time of a shock and detonation wave. The speed of the propagating wave was then determined by the time delay estimates provided for the best techniques. The techniques used ranged from the commonly used time-of-flight method to a nonstationary cross-spectral density phase method that provided a statistical estimation of the propagation time. The time delay results for a shock tube experiment showed that most of the methods had difficulties in …
Thermal Analysis Of Pulse Detonation Engines, Raghu Raman Ghandikota
Thermal Analysis Of Pulse Detonation Engines, Raghu Raman Ghandikota
Mechanical and Aerospace Engineering Theses - Archive
The pulse detonation engine (PDE) is a compact system that can be modeled thermodynamically by the Humphrey cycle and is capable of high efficiency. The rapid heat release for stochiometric fuel/oxidizer ratios results in developing high temperatures. The high temperatures produced during its operation can cause the engine to fail. Thus, operating this engine for a longer duration would become dubious if the temperatures are not dissipated from it. The current research aims to perform a preliminary thermal analysis. This analysis consists of two steps. The first step is to determine the heat dissipated from the engine using the unsteady …
Effect Of Pullout And Torsional Strength Of Composites With Co-Molded Thread Inserts, Dan L. Reller
Effect Of Pullout And Torsional Strength Of Composites With Co-Molded Thread Inserts, Dan L. Reller
Mechanical and Aerospace Engineering Theses - Archive
Rotorcraft transmission housings and drive system components are typically made from cast metals due to their highly complex geometries. Utilizing composite materials offers potential to reduce weigh and manufacturing cost while increasing corrosive resistance and extending part life. Traditional compression molded composites have not been utilized in aerospace because they typically experience low fiber volume fraction. Currently there are numerous materials which offer opportunities for composites in drive system housing applications and also offer the ability to co-mold details to reduce post mold operations. One of the issues associated with composite structures is the ability to fasten them to one …
Electromagnetic Flow Control: A Review And Experimental Development And Testing Of A Compact Actuator, Eric Braun
Electromagnetic Flow Control: A Review And Experimental Development And Testing Of A Compact Actuator, Eric Braun
Mechanical and Aerospace Engineering Theses - Archive
This thesis is divided into two sections which both relate to the field of magnetohydrodynamics and particularly electromagnetic flow control (EMFC). The first section contains a review of recent research in EMFC. The second section presents the experimental results of a compact EMFC actuator designed for use at low speeds where the flow conductivity is raised by conductive seed particle injection.Fifty years ago, publications began to discuss the possibilities of using EMFC to improve aerodynamic performance. This led to an era of research that focused on coupling the fundamentals of magnetohydrodynamics (MHD) with propulsion, control, and power generation systems. Unfortunately, …
Finite Element Analysis Of Helicopter Main Rotor Hub Plates To Evaluate The Possibility Of Increasing The Time To Retirement, Douglas Wittig
Finite Element Analysis Of Helicopter Main Rotor Hub Plates To Evaluate The Possibility Of Increasing The Time To Retirement, Douglas Wittig
Mechanical and Aerospace Engineering Theses - Archive
Rotorcraft main rotor systems have multiple components that are subject to very high loads and moments. These loads and moments dictate the life expectancy of the parts based upon the components material of composition. This project will primarily focus on the upper and lower hub plates on the main rotor system of a typical four bladed commercial helicopter. The upper and lower plates are machined from 7075-T73 aluminum forgings. The upper and lower plates were laboratory fatigue tested during product development as supporting parts in the test of the main rotor assembly. With recent advances in finite element analysis, there …
Quantitative Characterization Of Resistive Defects In Thick Composites Using Step Heating Thermography, Adel A. Badghaish, David C. Fleming
Quantitative Characterization Of Resistive Defects In Thick Composites Using Step Heating Thermography, Adel A. Badghaish, David C. Fleming
Aerospace, Physics, and Space Science Faculty Publications
Inspection of thick composite structures, such as Reinforced Thermosetting Resin (RTR) pipes used in the petroleum industry, using infrared thermography is difficult. This paper investigates the use of step heating thermography to increase the maximum detectable defect depth and describes techniques to quantitatively characterize defect depth and severity in thick composites. A procedure to simultaneously determine defect depth and thermal resistance from the early time surface temperature is described. The procedure is based on fitting the early time surface temperature profile over a defect to a one-dimensional three-layer analytical model. Experimental testing demonstrates the accuracy of the procedure.
Development Of Optical Fiber Sensors For Distance, Refractive Index And Strain Measurement, Ayan Majumdar
Development Of Optical Fiber Sensors For Distance, Refractive Index And Strain Measurement, Ayan Majumdar
Mechanical and Aerospace Engineering Theses - Archive
This thesis is focused on the development of optical fiber based sensors for the measurement of distance, refractive index, and strain. The fabrication, implementation, analysis, and evaluation of the sensors are presented. The Extrinsic Fabry-Perot Interferometric (EFPI) distance sensor is one of the most popular distance sensors but it possesses an inherent drawback. When the free-space cavity distance is very small, the numbers of fringes generated are not sufficient for the distance demodulation algorithm; therefore the smallest distance it can measure is determined by the bandwidth of the light source. An optical fiber based distance sensor is developed in this …
A Process For Ice Detector Placement Using 3-D Eulerian Droplet Impingement Analysis, Glenn T. Lancaster
A Process For Ice Detector Placement Using 3-D Eulerian Droplet Impingement Analysis, Glenn T. Lancaster
Mechanical and Aerospace Engineering Theses - Archive
Ice detectors invoke an aircraft's ice protection systems, which reduce the risks of flight into known icing conditions. A process has been developed to place ice detectors on aircraft using high fidelity computational icing tools. Three-dimensional Eulerian droplet impingement analysis is used to determine the necessary ice detector height and location required to achieve full functionality. This method is applied to the V-22 Osprey tiltrotor aircraft for validation against both tunnel and flight test data. When compared to icing tunnel test data, computational results for the volume of ice accreted on an antenna were within ten percent, validating the computational …
Design Of An Adaptive Autopilot For An Expendable Launch Vehicle, Clinton Plaisted
Design Of An Adaptive Autopilot For An Expendable Launch Vehicle, Clinton Plaisted
Electronic Theses and Dissertations
This study investigates the use of a Model Reference Adaptive Control (MRAC) direct approach to solve the attitude control problem of an Expendable Launch Vehicle (ELV) during its boost phase of flight. The adaptive autopilot design is based on Lyapunov Stability Theory and provides a useful means for controlling the ELV in the presence of environmental and dynamical uncertainties. Several different basis functions are employed to approximate the nonlinear parametric uncertainties in the system dynamics. The control system is designed so that the desire dresponse to a reference model would be tracked by the closed-loop system. The reference model is …
Attitude Determination Using Imaging Lidar, Camille Decoust
Attitude Determination Using Imaging Lidar, Camille Decoust
Master's Theses - Daytona Beach
The purpose of this study is to determine the attitude of an out of control object using a new technology called lidar (Light Ranging and Detection). As the number of spacecraft continues to grow, it is paramount to introduce a new type of autonomous on-orbit satellite inspection and repair involving docking. Traditional space vision technology is based on video systems. This method is limited by the necessity of operating when the target is illuminated by the sunlight or using its own source of illumination. The use of laser imaging technology offers an elegant solution to these challenges. This approach allows …
Volcanic Activity: Processing Of Observation And Remote Sensing Data (Vapor), Mark Wylie
Volcanic Activity: Processing Of Observation And Remote Sensing Data (Vapor), Mark Wylie
Reports
The World Bank makes a very clear distinction between disasters and natural phenomena. Natural phenomena are events like volcanic eruptions. A disaster only occurs when the ability of the community to cope with natural phenomenon has been surpassed, causing widespread human, material, economic or environmental losses. By these definitions, volcanic eruptions do not have to lead to disasters. On November 13, 1985, the second most deadly eruption of the twentieth century occurred in Colombia. Within a few hours of the eruption of the Nevado del Ruiz volcano, 23,000 people were dead because no infrastructure existed to respond to such an …
United States Air Force Posture Statement 2008, U.S. Air Force
United States Air Force Posture Statement 2008, U.S. Air Force
United States Air Force: Publications
The United States Air Force provides the Nation with a powerful deterrent force in times of peace, and it sets the conditions for Joint and Coalition victory in times of war. For over seventeen years, since Operation DESERT SHIELD, the United States Air Force has been engaged in continuous combat operations. Our Airmen have maintained constant watch, deployed continuously, engaged America’s adversaries directly, responded to human crises around the world, and provided the Global Vigilance, Global Reach, and Global Power to secure our Nation.
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
Mechanical & Aerospace Engineering Faculty Publications
A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7° C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N(2) adsorption ( BET) techniques. Wet-aging and lyophilization times are …
The Effect Of Stirring On The Morphology Of Birnessite Nanoparticles, Marcos A. Cheney, Pradip K. Bhowmik, Shingo Moriuchi, Mario Villabos, Shizhi Qian, Sang W. Joo
The Effect Of Stirring On The Morphology Of Birnessite Nanoparticles, Marcos A. Cheney, Pradip K. Bhowmik, Shingo Moriuchi, Mario Villabos, Shizhi Qian, Sang W. Joo
Mechanical & Aerospace Engineering Faculty Publications
The effect of mechanical stirring on the morphology of hexagonal layer- structure birnessite nanoparticles produced from decomposition of KMnO4 in dilute aqueous H2SO4 is investigated, with characterization by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high- resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET). Mechanical stirring during an initial stage of synthesis is shown to produce black birnessite containing nanofibers, whereas granular particulates of brown birnessite are produced without stirring. This is the first reduction synthesis of black birnessite nanoparticles with dendritic morphology without any use …
Multiplexed Predictive Control Of A Large Commercial Turbofan Engine, Hanz Richter, Anil V. Singaraju, Jonathan S. Litt
Multiplexed Predictive Control Of A Large Commercial Turbofan Engine, Hanz Richter, Anil V. Singaraju, Jonathan S. Litt
Mechanical Engineering Faculty Publications
Model predictive control is a strategy well-suited to handle the highly complex, nonlinear, uncertain, and constrained dynamics involved in aircraft engine control problems. However, it has thus far been infeasible to implement model predictive control in engine control applications, because of the combination of model complexity and the time allotted for the control update calculation. In this paper, a multiplexed implementation is proposed that dramatically reduces the computational burden of the quadratic programming optimization that must be solved online as part of the model-predictive-control algorithm. Actuator updates are calculated sequentially and cyclically in a multiplexed implementation, as opposed to the …
Visualizing The Flow Induced By An Air Curtain Over A Mannequin Using Stereo Particle Image Velocimetry, John Edward Fernandes
Visualizing The Flow Induced By An Air Curtain Over A Mannequin Using Stereo Particle Image Velocimetry, John Edward Fernandes
Mechanical and Aerospace Engineering Theses - Archive
Air curtains find widespread applications in today's world, such as in malls, supermarkets, airports, cold storage, etc., to allow easy pedestrian movement between two different environments. There is interest in understanding the flow induced by traffic through the air curtain in terms of energy efficiency and the ability to provide isolation from contaminants and airborne pathogens. To develop an understanding of the flow, an initial exploratory study was performed using a static mannequin. A stereo particle image velocimetry (SPIV) system was set up to map the flow of the air curtain, installed on top of the doorway, over a mannequin. …
Characterization Of Thermal Challenges In Electronics : Leakage Current, Co-Architectural Design And Rack Level Cooling, Uthaman Raju
Characterization Of Thermal Challenges In Electronics : Leakage Current, Co-Architectural Design And Rack Level Cooling, Uthaman Raju
Mechanical and Aerospace Engineering Theses - Archive
Since the advent of transistors and integrated circuits the complexity and functionality of the electronic products has gone up. In line with this, the scaling of the products is catching up at all levels of packaging. Current electronics era is driven by a mantra - "Miniaturization". Recently the number of transistors on high end microprocessor has exceeded a billon mark. The design at board level becomes sophisticated to meet the growing demands. All of these lead to thermal and reliability challenges. A good thermal design is one which makes sure that the chip is operating at its rated frequency or …
Experimental Analysis Of The Hydrogen Sulfide Absortion Phenomena In Brine/Oil Mixtures As A Function Of System Pressure And H2s, Luis Zea
Electronic Theses and Dissertations
In underground oil reservoirs, Hydrogen sulfide is usually found coexisting with the oil due to bacteria reduction over a long period of time. The amount of H2S in the oil varies from place to place around the globe. When the oil extraction process begins, the presence of Hydrogen sulfide becomes noticeable as drilling tools, piping and other equipment suffer from sulfide stress cracking, electrochemical corrosion and corrosion fatigue. For this reason, the oil industry invests millions of dollars per year trying to find better ways to reduce the amount of H2S in oil. An important part of the current investigations …