Assessing Safety Culture Within A Flight Training Organization,
2013
Embry Riddle Aeronautical University
Assessing Safety Culture Within A Flight Training Organization, David Freiwald, Carolina Lenz-Anderson, Erik Baker
Applied Aviation Sciences - Daytona Beach
This study was prompted by a string of aircraft hull losses experienced by a multinational, multi-campus flight training organization. A mixed methods study was conducted to study the attitudes and perceptions of the operations and management staff at this flight training organization through the use of a survey instrument previously existing and adapted, in order to ensure validity, and interviews with key staff members. Confirmatory factor analysis was performed to identify underlying constructs in the perceptions and attitudes of the staff in order to identify beliefs that may signify a flight training organization is at risk. An analysis was conducted …
Modelling And Configuration Control Of Wing-Shaped Bi-Stable Piezoelectric Composites Under Aerodynamic Loads,
2013
Old Dominion University
Modelling And Configuration Control Of Wing-Shaped Bi-Stable Piezoelectric Composites Under Aerodynamic Loads, Andres F. Arrieta, Onur Bilgen, Michael I. Friswell, Paolo Ermanni
Mechanical & Aerospace Engineering Faculty Publications
Bi-stable composites have been considered for morphing applications thanks to their ability to hold two statically stable shapes with no energy consumption. In this paper, the modelling of the dynamic response of cantilevered wing-shaped bi-stable composites is presented. To this end, an analytical model approximating the dynamic response about each statically stable shape of wing-shaped bi-stable composites is derived. Theoretical modal properties are obtained to attain or stabilise a desired configuration following a previously introduced resonant control strategy. The resonant control technique is evaluated for a wing-shaped bi-stable composite subject to aerodynamic loads. Wind tunnel experiments are conducted on a …
Gaseous Corrosion In Hard Disk Drive: A Computational Study,
2013
University of Texas at Arlington
Gaseous Corrosion In Hard Disk Drive: A Computational Study, Hardik Shah
Mechanical and Aerospace Engineering Theses - Archive
HDD is the largest digitally encoded data storage device. HDD is used to store digital data in data centers, computers and laptops. A typical HDD consists of a casing, an actuator arm, actuator axis, head, platters, power connectors, and jumper pins. The platter is made up of non-magnetic material and is covered by magnetic material, which stores the data. The magnetic heads are mounted on a moving actuator arm to read and write the data. One of the modes of failure of a HDD is corrosion. The parts of the HDD are corroded by coming in contact with the contaminants. …
Optimal Thickness Distributions Of Aeroelastic Flapping Shells,
2013
Wright–Patterson AFB
Optimal Thickness Distributions Of Aeroelastic Flapping Shells, Bret Stanford, Philip Beran
United States Air Force: Publications
The severe weight limitations of flapping wing micro air vehicles necessitates the use of thin flexible wings, which in turn requires an aeroelastic modeling tool for proper numerical characterization. Furthermore, due to the unconventional nature of these vehicles, wing design guidelines for thrust and/or power considerations are not generally available; numerical design optimization then becomes a valuable tool. This work couples a nonlinear shell model to an unsteady vortex lattice solver, and then computes analytical design gradients: the derivative of aerodynamic force/power quantities with respect to a large vector of thickness variables. Gradient-based optimization is then used to locate the …
Direct Ignition And S-Curve Transition By In Situ
Nano-Second Pulsed Discharge In Methane/Oxygen/Helium Counterflow Flame,
2013
Princeton University
Direct Ignition And S-Curve Transition By In Situ Nano-Second Pulsed Discharge In Methane/Oxygen/Helium Counterflow Flame, Wenting Sun, Sang Hee Won, Timothy Ombrello, Campbell Carter, Yiguang Ju
United States Air Force: Publications
A well-defined plasma assisted combustion system with novel in situ discharge in a counterflow diffusion flame was developed to study the direct coupling kinetic effect of non-equilibrium plasma on flame ignition and extinction. A uniform discharge was generated between the burner nozzles by placing porous metal electrodes at the nozzle exits. The ignition and extinction characteristics of CH4/O2/He diffusion flames were investigated by measuring excited OH* and OH PLIF, at constant strain rates and O2 mole fraction on the oxidizer side while changing the fuel mole fraction. It was found that ignition and extinction occurred with an abrupt change of …
Discussion Of Christine C. Shepard, Vera N. Agostini, Ben Gilmer, Tashya Allen, Jeff Stone, William Brooks And Michael W. Beck. Reply: Evaluating Alternative Future Sea-Level Rise Scenarios, Natural Hazards, 2012 Doi:10.1007/S11069-012-0160-2,
2013
Missouri University of Science and Technology
Discussion Of Christine C. Shepard, Vera N. Agostini, Ben Gilmer, Tashya Allen, Jeff Stone, William Brooks And Michael W. Beck. Reply: Evaluating Alternative Future Sea-Level Rise Scenarios, Natural Hazards, 2012 Doi:10.1007/S11069-012-0160-2, A. Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Robustness Of A Derivative-Free Adaptive Control Law In The Presence Of Unmodeled Dynamics,
2013
Missouri University of Science and Technology
Robustness Of A Derivative-Free Adaptive Control Law In The Presence Of Unmodeled Dynamics, Tansel Yucelen, Anthony J. Calise
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Although adaptive control theory offers mathematical tools to achieve required system performance without excessive dependence on modeling, its application to safety-critical systems can be limited by the presence of unmodeled dynamics. This paper examines the robustness to unmodeled dynamics of a recently developed derivative-free adaptive control law. In contrast to derivative-based adaptive laws it is shown, using a Lyapunov-Krasovskii functional, that robustness to unmodeled dynamics is improved by increasing the adaptation gain. This is accomplished by including a bias term in the set of basic functions employed by the adaptive control law. It is shown that derivative-based adaptive laws do …
Consensus Protocols In Networked Multiagent Systems For Cluttered And Hostile Environments,
2013
Missouri University of Science and Technology
Consensus Protocols In Networked Multiagent Systems For Cluttered And Hostile Environments, Gerardo De La Torre, Eric N. Johnson, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Consensus refers to the agreement of networked agents upon certain quantities of interest and has widespread applications in diverse areas in science and engineering. This paper focuses on a new consensus protocol for networked multiagent systems operating in cluttered and hostile environments. Specifically, a consensus optimization algorithm is introduced that renders the Laplacian potential to be a nonincreasing function while minimizing a cost function and satisfying state and cost constraints. In addition, we show how to choose this cost function and the aforementioned constraints in order to decay the Laplacian potential to zero strictly. The proposed framework depends on a …
Neuropredictive Control And Trajectory Generation For Slung Load Systems,
2013
Missouri University of Science and Technology
Neuropredictive Control And Trajectory Generation For Slung Load Systems, Gerardo De La Torre, Eric N. Johnson, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents a neuropredictive trajectory generation architecture for slung load systems. The presented architecture integrates the real-time trajectory generation method with a system uncertainty identifying neural network. It is shown that the effect of system uncertainty on a model predictive control approach can be mitigated by the use of neural networks. A numerical example of an uncertain slung load system is shown to demonstrate the effectiveness of the presented framework.
Consensus Protocols For Networked Multiagent Systems With Relative Position And Neighboring Velocity Information,
2013
Missouri University of Science and Technology
Consensus Protocols For Networked Multiagent Systems With Relative Position And Neighboring Velocity Information, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The consensus problem appears frequently in the coordination of multiagent systems in science and engineering and involves the agreement of networked agents upon certain quantities of interest. In this paper, we focus on a new consensus protocol for networked multiagent systems. The proposed control protocol consists of a standard term capturing relative position information and a new term capturing neighboring velocity information. In particular, the addition of the latter term results in an increase of the rate of system convergence while maintaining a fixed graph structure and without increasing the maximum eigenvalue of the graph Laplacian. Furthermore, in certain cases, …
Hybrid Protocols For Maintaining Connectivity Of Multiagent Systems,
2013
Missouri University of Science and Technology
Hybrid Protocols For Maintaining Connectivity Of Multiagent Systems, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper focuses on a new connectivity control architecture for networked multiagent systems based on hybrid protocols. Specifically, for a group of agents subject to Δ-disk proximity graphs, we consider the consensus problem while preserving connectedness with a priori given bounds on the control inputs. The bounds on the control inputs are shown not to depend on potential functions or system states. Instead, the bounds are user selected continuous functions. By using the proposed framework, we show that the maximum distance among neighboring agents decreases strictly, and hence the connectivity problem is solved while satisfying the consensus objective. © 2013 …
Separate-Channel Integrated Guidance And Autopilot For Automatic Path-Following,
2013
Missouri University of Science and Technology
Separate-Channel Integrated Guidance And Autopilot For Automatic Path-Following, Takeshi Yamasaki, S. N. Balakrishnan, Hiroyuki Takano
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An integrated guidance and autopilot scheme for a path-following uninhabited aerial vehicle is presented in this study. A fixed-wing aircraft usually performs a bank-to-turn maneuver to change its flight direction. The novel approach presented here, however, assumes that each of the three channels of the integrated guidance and autopilot can be independently designed. This concept makes the design process simple. A virtual target moving on the prespecified path for the uninhabited aerial vehicle is introduced to facilitate the algorithm development. A first-/ second order sliding structure with a second order sliding mode and a high-order sliding mode differentiator for the …
Constraint Enforcement Methods For Command Governor Based Adaptive Control Of Uncertain Dynamical Systems,
2013
Missouri University of Science and Technology
Constraint Enforcement Methods For Command Governor Based Adaptive Control Of Uncertain Dynamical Systems, Simon P. Schatz, Tansel Yucelen, Eric N. Johnsony, Florian Holzapfelz
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Recently, research has been conducted in order to improve the transient behavior of adaptively controlled uncertain nonlinear dynamical systems. In this paper, an adaptive control architecture is extended in order to achieve predictable transient performance in the presence of state constraints. The methodology at hand is based on a robust command governor framework, which is a dynamical system adjusting the trajectory of a given command in order to track a certain desired closed-loop reference model both in transient time and steady-state. Specifically, the command, which is applied on the reference model and the actual system, is changed by the command …
Effect Of Stitch Density On Tensile Properties And Damage Mechanisms Of Stitched Carbon/Epoxy Composites,
2013
Missouri University of Science and Technlogy
Effect Of Stitch Density On Tensile Properties And Damage Mechanisms Of Stitched Carbon/Epoxy Composites, Arief Yudhanto, Naoyuki Watanabe, Yutaka Iwahori, Hikaru Hoshi
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Experimental investigation is performed to study tensile properties, damage initiation and development in stitched carbon/epoxy composites subjected to tensile loading. T800SC-24kf dry preforms with tow orientation of [+45/90/-45/02/+45/902/-45/0]s are stitched using 200 denier Vectran® thread. Modified-lock stitch pattern is adopted, and stitch density is varied, viz. moderate density (stitched 6 x 6: stitch density = 2.8 cm-2) and high density (stitched 3 x 3: stitch density = 11.1 cm-2). The stitched preforms are then infiltrated by epoxy XNR/H6813 using resin transfer molding process. Tensile test is conducted to obtain in-plane mechanical properties (tensile strength, failure strain, tensile modulus and Poisson's …
Damage Characterization And Analytical Modeling Of Quasi-Statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru,
2013
Syracuse University
Damage Characterization And Analytical Modeling Of Quasi-Statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru, Abhendra K. Singh
Mechanical and Aerospace Engineering - Dissertations
The research conducted for this dissertation focused on understanding the nature and extent of barely visible impact damage (BVID) in composite sandwich structures. This was part of a larger research effort that included studies on the influence of BVID on the compressive strengths and failure modes of composite sandwich structures. In this dissertation, the nature and extent of BVID is studied in aluminum honeycomb core sandwich panels with eight and sixteen ply, quasi-isotropic, graphite/epoxy face sheets. The damage in the sandwich structure is created quasi-statically using spherical indentors of two different sizes. Apart from the face sheet thickness and indentor …
Non-Equilibrium Pressure Control Of The Height Of A Large-Scale, Ground-Coupled, Rotating Fluid Column,
2013
Old Dominion University
Non-Equilibrium Pressure Control Of The Height Of A Large-Scale, Ground-Coupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan
Mechanical & Aerospace Engineering Faculty Publications
When a ground-coupled, rotating fluid column is modeled incorporating non-equilibrium pressure forces in the Navier-Stokes equations, a new exact solution results. The solution has been obtained in a similar manner to the classical equilibrium solution. Unlike the infinite-height, classical solution, the non-equilibrium pressure solution yields a ground-coupled rotating fluid column of finite height. A viscous, non-equilibrium Rankine vortex velocity distribution, developed previously, was used to demonstrate how the viscous and non-equilibrium pressure gradient forces, arising in the vicinity of the velocity gradient discontinuity that is present in the classical Rankine vortex model, effectively isolate the rotating central fluid column from …
Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model,
2013
University of Texas at El Paso
Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model, David Ricardo Romo
Open Access Theses & Dissertations
Foreign Object Debris/Damage (FOD) has been an issue for military and commercial aircraft manufacturers since the early ages of aviation and aerospace. Currently, aerospace is growing rapidly and the chances of FOD presence are growing as well. One of the principal causes in manufacturing is the human error. The cost associated with human error in commercial and military aircrafts is approximately accountable for 4 billion dollars per year. This problem is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access, restrictions of personal items entering designated areas, tool accountability, and the use of technology such …
Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application,
2013
University of Texas at Arlington
Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application, Chao Ji
Mechanical and Aerospace Engineering Theses - Archive
Lithium-ion batteries are currently widely used in electronics, electrical vehicles and other devices/machines. Along with the mounting demand for much improved performance in these developing technological fields, silicon was recognized to possess much higher energy capacity when used as an anode than graphite that is currently used. However, there occurs colossal volume expansion of silicon anode during the lithiation process. The material consequently suffers enormous stresses, especially, at the interface with a current collector, which deteriorate the device quickly during cycling. To prevent the active material (Si) from falling off from a current collector, nanoengineering strategies have been suggested, including …
Application Of Phase Change Material In Sustainable Cooling Of Data Centers,
2013
University of Texas at Arlington
Application Of Phase Change Material In Sustainable Cooling Of Data Centers, Nikhil Dhiman
Mechanical and Aerospace Engineering Theses - Archive
The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. In recent years, more effort is being made on the development of a new technique to use the phase change materials as pump-able heat transfer fluid and as heat storage system.Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a …
Thermal Management Method For Foil Bearings In Turbine Hot Section,
2013
University of Texas at Arlington
Thermal Management Method For Foil Bearings In Turbine Hot Section, Tejas Devidas Patil
Mechanical and Aerospace Engineering Theses - Archive
Recently, Air Foil Bearings (AFB) are gaining higher industrial acceptance in micro-turbo machinery. AFB show high speed operating capability and environmental friendly operation in comparison to rolling element bearings. Utilization of ambient air as a lubricant eliminates maintenance of a pressurized oil lubricating system. AFBs are therefore a feasible alternative to oil lubricated bearings in small machines. High speed operation results in thermal management issues which can be solved through a suitable cooling mechanism. Axial cooling by passing air through bearing support structure (called bump foils) is the most commonly used. In this method, cooling is achieved in the heat …
