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2005

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Articles 121 - 150 of 159

Full-Text Articles in Aerospace Engineering

Computational Aerodynamics Goes To School: A Course In Cfd For Undergraduate Students, Russell M. Cummings, Scott A. Morton Jan 2005

Computational Aerodynamics Goes To School: A Course In Cfd For Undergraduate Students, Russell M. Cummings, Scott A. Morton

Aerospace Engineering

As aerodynamics education has evolved over the past decades, a slow transition from important analytic methods to increasingly powerful computational methods has taken place. While a basic understanding of theoretical aerodynamics should always be included in coursework, the realities of modern design practices make the usefulness of the traditional approach less and less practical. A new undergraduate course in computational aerodynamics has been developed that attempts to give students experience with the modern computational tools of aerodynamics, primarily from an applications perspective. While introducing students to the important computational topics of accuracy and stability, the course stresses the practical tools …

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Des Turbulence Modeling On The C-130 Comparison Between Computational And Experimental Results, Malcom P. Claus, Scott A. Morton, Russell M. Cummings, Yannick Bury Jan 2005

Des Turbulence Modeling On The C-130 Comparison Between Computational And Experimental Results, Malcom P. Claus, Scott A. Morton, Russell M. Cummings, Yannick Bury

Aerospace Engineering

This paper represents the results from the initial phase of a research program to determine the flow characteristics of the C-130 Hercules transport aircraft. The initial phase of the program consists of evaluation and comparison of the flow-field obtained from flow visualization methods. Specifically CFD (Computational Fluid Dynamics) results are compared with experimental Hot Wire results produced by wind tunnel tests on the C-130 in clean configuration. This paper outlines the results to date and provides a description of further work. The CFD element of this research features the use of Detached Eddy Simulation (DES) in order to extend its …

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Deformation Of Unstructured Viscous Grids, Denis B. Kholodar, Scott A. Morton, Russell M. Cummings Jan 2005

Deformation Of Unstructured Viscous Grids, Denis B. Kholodar, Scott A. Morton, Russell M. Cummings

Aerospace Engineering

A mesh deformation algorithm for unstructured grids is presented. It is designed for high Reynolds number flow problems. Such grids are employed in aerodynamic and aeroelastic studies of wings or complete aircraft configurations in flows where the viscous effects are important. Given a surface deformation, the method efficiently recalculates new locations of high aspect ratio cells that make up the viscous layers of the grid and then deforms the inviscid part of the grid using an established method based on a torsional spring analogy technique. Results are presented for monitoring the deterioration of the quality of the grid during subsequent …

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Robust Control Techniques For State Tracking In The Presence Of Variable Time Delays, Jarrett Goodell, Marc Compere, Miguel Simon, Wilford Smith, Ronnie Wright, Mark Brudnak Jan 2005

Robust Control Techniques For State Tracking In The Presence Of Variable Time Delays, Jarrett Goodell, Marc Compere, Miguel Simon, Wilford Smith, Ronnie Wright, Mark Brudnak

Publications

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory (GVSL). Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory (P&E SIL), which is developed and maintained by Science Applications International Corporation (SAIC). The goal is to close the loop between the GVSL and P&E SIL over the Internet to provide a realistic driving experience in addition to realistic …

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Engineering Tools For Variable Stiffness Vibration Suppression And Isolation, Michael F. Winthrop Jan 2005

Engineering Tools For Variable Stiffness Vibration Suppression And Isolation, Michael F. Winthrop

Theses and Dissertations

With the advent of smart materials, the concept of semi-active control or dynamic control of stiffness and/or damping for vibration control of structures has become practical and has seen limited use. Semi-active control has advantages over active and passive control methods, since it provides almost as much capability as active control while requiring much less power. Its main disadvantage is its inherent nonlinearity, greatly complicating engineering design. The purpose of this research is to extend semi-active control vibration isolation tools and methods considering space launch and on-orbit systems.

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Model Predictive Control Of A Parafoil And Payload System, Nathan Slegers, Mark Costello Jan 2005

Model Predictive Control Of A Parafoil And Payload System, Nathan Slegers, Mark Costello

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

No abstract provided.

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An Existing Global Heptane Mechanism Augmented With Diffusive Transport, Michael R. Foster, Howard Pearlman Jan 2005

An Existing Global Heptane Mechanism Augmented With Diffusive Transport, Michael R. Foster, Howard Pearlman

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

The couplings between diffusive transport and the temperature and species concentration distributions associated with low and intermediate temperature heptane oxidation are explored using an existing four-step heptane mechanism, tuned for elevated pressures. The energy and species concentration equations are augmented with diffusive fluxes for heat and species and solved numerically in a one-dimensional domain. The ignition delay times are also tabulated and compared with the zero-dimensional data reported in the literature.

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Laboratory Evaluation Of Colored Light As An Attractant For Female Aedes Aegypti, Aedes Albopictus, Anopheles Quadrimaculatus, And Culex Nigripalpus, Douglas A. Burkett, Jerry F. Butler Jan 2005

Laboratory Evaluation Of Colored Light As An Attractant For Female Aedes Aegypti, Aedes Albopictus, Anopheles Quadrimaculatus, And Culex Nigripalpus, Douglas A. Burkett, Jerry F. Butler

United States Air Force: Publications

Mosquito feeding activity was monitored in an electronic apparatus (visualometer), having ten ports, illuminated from below with narrow bandwidths of light (700, 650, 600, 550, 500, 450, 400, or 350 nm). Responses of adult female Aedes albopictus Skuse, Ae. aegypti (L.), Anopheles quadrimaculatus, Say and Culex nigripalpus Theobald to feeding stations (blood containers) over each light port. No-light and broad spectrum white light were used as controls. Color preferences were based on electronic detection of feeding times. Aedes aegypti showed no significant feeding preferences over any of the colors. Conversely, Ae. albopictus, An. quadrimaculatus, and Cx. nigripalpus showed …

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Performance Of A New Cfd Flow Solver Using A Hybrid Programming Paradigm, M. J. Berger, M. J. Aftosmis, D. D. Mashall, S. M. Murman Jan 2005

Performance Of A New Cfd Flow Solver Using A Hybrid Programming Paradigm, M. J. Berger, M. J. Aftosmis, D. D. Mashall, S. M. Murman

Aerospace Engineering

This paper presents several algorithmic innovations and a hybrid programming style that lead to highly scalable performance using shared memory for a new computational fluid dynamics flow solver. This hybrid model is then converted to a strict message-passing implementation, and performance results for the two are compared. Results show that using this hybrid approach our OpenMP implementation is actually marginally faster than the MPI version, with parallel speedups of up to 599 out of 640 using OpenMP and 486 with MPI.

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United States Air Force Posture Statement 2005, U.S. Air Force Jan 2005

United States Air Force Posture Statement 2005, U.S. Air Force

United States Air Force: Publications

Today's security environment is characterized by change and ambiguity. The future will include a variety of challenges, including the risk of catastrophic attacks on the homeland and possibly of disruptive technological breakthroughs by our adversaries.

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Sample Preparation And Characterization Of Artificially Aged Aircraft Coatings For Microstructural Analysis, Lisa M. Farrier, Stephen A. Szaruga Jan 2005

Sample Preparation And Characterization Of Artificially Aged Aircraft Coatings For Microstructural Analysis, Lisa M. Farrier, Stephen A. Szaruga

United States Air Force: Publications

The paper describes a method for metallographic preparation of artificially aged aircraft coatings. In order to better understand the in-service performance and identify degradation mechanisms of an aircraft coating, complete characterization of the microstructure is essential. This paper discusses metallographic sample preparation and subsequent microscopy techniques (light optical microscopy, scanning electron microscopy) for characterization of a standard polyurethane aircraft coating system. The preparation method has proven to produce good, consistent results on a wide range of laboratory-produced simulated environmental exposures.

The military specification coating system under study (MIL-PRF-85285C and MIL-PRF-23377G) degrades severely after accelerated weathering. Typical degradation includes deterioration of …

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Improving Pilot Mental Workload Classification Through Feature Exploitation And Combination: A Feasibility Study, Jeremy B. Noel, Kenneth W. Bauer, Jr., Jeffrey W. Lanning Jan 2005

Improving Pilot Mental Workload Classification Through Feature Exploitation And Combination: A Feasibility Study, Jeremy B. Noel, Kenneth W. Bauer, Jr., Jeffrey W. Lanning

United States Air Force: Publications

Predicting high pilot mental workload is important to the United States Air Force because lives and aircraft have been lost due to errors made during periods of flight associated with mental overload and task saturation. Current research efforts use psychophysiological measures such as electroencephalography (EEG), cardiac, ocular, and respiration measures in an attempt to identify and predict mental workload levels. Existing classification methods successfully classify pilot mental workload using flight data for a single pilot on a given day, but are unsuccessful across different pilots and/or days. We demonstrate a small subset of combined and calibrated psychophysiological features collected from …

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The U.S. Air Force Remotely Piloted Aircraft And Unmanned Aerial Vehicle Strategic Vision, U.S. Air Force Jan 2005

The U.S. Air Force Remotely Piloted Aircraft And Unmanned Aerial Vehicle Strategic Vision, U.S. Air Force

United States Air Force: Publications

The U.S. Air Force Remotely Piloted Aircraft and Unmanned Aerial Vehicle Strategic Vision (hereafter referred to as The Strategic Vision) examines the future role of Air Force remotely piloted aircraft (RPAs) and unmanned aerial vehicles (UAVs) and their integration with other Air Force and joint systems. The Strategic Vision is presented in five sections.

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An Investigation Of The Autoignition Of Power Generation Gas Turbine Fuel Blends Using A Design Of Experiments Approach, Jaap De Vries Jan 2005

An Investigation Of The Autoignition Of Power Generation Gas Turbine Fuel Blends Using A Design Of Experiments Approach, Jaap De Vries

Electronic Theses and Dissertations

Natural gas has grown in popularity as a fuel for power generation gas turbines. However, changes in fuel composition are a topic of concern since fuel variability can have a great impact on the reliability and performance of the burner design. In particular, autoignition of the premixed fuel and air prior to entering the main burner is a potential concern when using exotic fuel blends. To obtain much-needed data in this area, autoignition experiments for a wide range of likely fuel blends containing CH4 mixed with combinations of C2H6, C3H8, C4H10, C5H12, and H2 were performed in a high-pressure shock …

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International Space Station Remote Sensing Pointing Analysis, Craig Jacobson Jan 2005

International Space Station Remote Sensing Pointing Analysis, Craig Jacobson

Electronic Theses and Dissertations

This paper analyzes the geometric and disturbance aspects of utilizing the International Space Station for remote sensing of earth targets. The proposed instrument is SHORE (Station High-Sensitivity Ocean Research Experiment), a multi-band optical spectrometer with 15 m pixel resolution. The analysis investigates the contribution of the error effects to the quality of data collected by the instrument. The analysis begins with the discussion of the coordinate systems involved and then conversion from the target coordinate system to the instrument coordinate system. Next the geometry of remote observations from the Space Station is investigated including the effects of the instrument location …

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Control System Design And Simulation Of Spacecraft Formations, Daniel Dyer Jan 2005

Control System Design And Simulation Of Spacecraft Formations, Daniel Dyer

Master's Theses - Daytona Beach

The objective of this thesis is to analyze an effective control scheme for a formation of spacecraft, implement that control, and provide a 3-D simulation. The thesis first summarizes the progress made in formation flight control schemes and then provides a theoretical framework for the control system design. Using established control design techniques, feedback laws are constructed to control both rotational and translational motion of a group of spacecraft. Computer simulations are carried out using Matlab to generate the ephemeris and attitude data, which are exported to Satellite Tool Kit (STK) to create animations. The process by which Matlab is …

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Accuracy Of Heat-Pulse Sensors For Determining Moisture Of Capillary Mat Material Used To Support Plant Growth, Marisa Wyssling Jan 2005

Accuracy Of Heat-Pulse Sensors For Determining Moisture Of Capillary Mat Material Used To Support Plant Growth, Marisa Wyssling

Master's Theses - Daytona Beach

The accuracy and precision of Orbital Technologies (Orbitec, Madison, WI) Thermal and Moisture Acquisition System (TMAS) sensors were investigated for use in the WONDER space flight experiment. WONDER is studying the effect of multiple wetness level regimes and two different nutrient delivery systems (NDS) on plants grown in the microgravity of space. The following research concentrates on the porous tube NDS consisting solely of a capillary mat surrounding a bare porous tube used for water delivery. Sensors and plants will be attached to the capillary mat, which transports water by capillary action. The TMAS sensors, single probe heat-pulse moisture sensors, …

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Incorporating The Impact Of Engineering Solutions On Society Into Technical Engineering Courses, Nicole Dejong-Okamoto, Jinny Rhee, Nikos J. Mourtos Jan 2005

Incorporating The Impact Of Engineering Solutions On Society Into Technical Engineering Courses, Nicole Dejong-Okamoto, Jinny Rhee, Nikos J. Mourtos

Faculty Publications

In the era of market and workforce globalisation, engineers need a solid understanding of the impact that their products have locally, as well as globally. This is why the US Accreditation Board for Engineering and Technology (ABET) recently put a new spin on this requirement in engineering education. Specifically, outcome 3h of Engineering Criteria 2000 states that engineering graduates must have the broad education to understand the impact of engineering solutions in a global/ societal context. This outcome may be one of the most difficult to achieve, since it requires not only a strong technical understanding, but also an informed …

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Decision Support For The Career Field Selection Process At The Us Air Force Academy, Andrew P. Armacost, James K. Lowe Jan 2005

Decision Support For The Career Field Selection Process At The Us Air Force Academy, Andrew P. Armacost, James K. Lowe

United States Air Force: Publications

Each year, the US Air Force Academy graduates nearly 1000 young men and women. To support the decision of which cadets will be classified into which career fields, we describe a linear programming formulation with appealing computational properties that enable it as the core of a decision support tool. We explore methods for measuring and balancing cadets' class standing, Air Force career field requirements, and cadets' career field preferences in the context of this model. Our computational experiments demonstrate the improvement of this method over previous classification approaches, yielding more than 10% increase in the number of cadets assigned to …

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Sounding Rocket Redesign And Optimization For Payload Expansion And In Flight Telemetry Transmittal, Matthew Huffman Jan 2005

Sounding Rocket Redesign And Optimization For Payload Expansion And In Flight Telemetry Transmittal, Matthew Huffman

Electronic Theses and Dissertations

Due to renewed interest in the sub orbital rocket program of the Florida Space Authority and a surplus of Super Loki Sounding Rockets, an effort to improve the usefulness of this surplus is herein undertaken. Currently, the capacity of the payload compartment in the upper stage of the Super Loki system is very limited. A redesign of the upper stage will allow larger and more versatile payloads to be carried, assuming the appropriate design parameters are met. It has therefore been undertaken to create a design procedure that is comprehensive in scope in order to affect this redesign. This procedure …

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The Katysat Project: Kids Aren’T Too Young (For Satellites), Benjamin Yuan Jan 2005

The Katysat Project: Kids Aren’T Too Young (For Satellites), Benjamin Yuan

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Benjamin Yuan titled "The KatySat Project: Kids Aren’t Too Young (for satellites)" from April 14, 2005.

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Results Of An Interlaboratory Study Of The Astm Standard Test Method For Tensile Properties Of Polymer Matrix Composites D 3039, Margaret Pinnell, Richard Fields, Ronald Zabora Jan 2005

Results Of An Interlaboratory Study Of The Astm Standard Test Method For Tensile Properties Of Polymer Matrix Composites D 3039, Margaret Pinnell, Richard Fields, Ronald Zabora

Mechanical and Aerospace Engineering Faculty Publications

An investigation was conducted on the ASTM Standard Test Method for Tensile Properties of Polymer Matrix Composites (D 3039). This investigation consisted of both preliminary testing and an interlaboratory test program. Information generated from preliminary testing was used to determine the effects of various parameters and to optimize the interlaboratory test plan and test protocol. The interlaboratory study portion of this investigation was conducted on six composite material systems in a variety of lay-up configurations. The number of participating labs ranged from five to nine depending on the material type. Precision statistics were determined for the ASTM D 3039 standard …

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Measurement And Control Of Torque Ripple-Induced Frame Torsional Vibration In A Surface Mount Permanent Magnet Machine, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue Jan 2005

Measurement And Control Of Torque Ripple-Induced Frame Torsional Vibration In A Surface Mount Permanent Magnet Machine, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A sensor to measure the stator torsional vibration due to torque ripple produced by a surface mount permanent magnet machine is first described. The sensor is relatively inexpensive and is straight forward to incorporate into a drive system. Experiments are performed to validate that the voltage produced by the sensor is linearly related to torque ripple amplitude. Closed-loop controllers are then described that adjust the stator current harmonics applied to the machine to achieve a commanded average torque while mitigating measured torsional vibration. Simulation and experimental results are used to demonstrate the effectiveness of the control techniques.

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Analysis And Modeling Of Information Flow And Distributed Expertise In Space-Related Operations, Barrett S. Caldwell Jan 2005

Analysis And Modeling Of Information Flow And Distributed Expertise In Space-Related Operations, Barrett S. Caldwell

School of Industrial Engineering Faculty Publications

Evolving space operations requirements and mission planning for long-duration expeditions require detailed examinationsand evaluations of information flow dynamics, knowledge-sharing processes, and information technology use in distributedexpert networks. This paper describes the work conducted with flight controllers in the Mission Control Center (MCC) ofNASA’s Johnson Space Center. This MCC work describes the behavior of experts in a distributed supervisory coordinationframework, which extends supervisory control/command and control models of human task performance. Findings from thiswork are helping to develop analysis techniques, information architectures, and system simulation capabilities for knowledgesharing in an expert community. These findings are being applied to improve knowledge-sharing processes …

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Modeling Satellite Formations In The Presence Of Perturbations, Robert Cannaday Jan 2005

Modeling Satellite Formations In The Presence Of Perturbations, Robert Cannaday

Electronic Theses and Dissertations

The potential benefits of autonomous satellite formation flying in such areas as high- resolution remote sensing, and sparse aperture radar, has stimulated interest in modeling the satellite environment for feasibility and simulation studies to help explore and define the technical challenges that must be solved in order to achieve successful autonomous satellite formations. The purpose of this paper is to develop and describe a numerical simulation of the orbital environment including central force field perturbations and atmospheric drag effects which will be a useful analytical tool for investigating issues relating to maintaining satellite formations in low-earth-orbit. Many of the studies …

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Modular Control Laboratory System With Integrated Simulation, Animation, Emulation, And Experimental Components, J. Liu, Robert G. Landers Jan 2005

Modular Control Laboratory System With Integrated Simulation, Animation, Emulation, And Experimental Components, J. Liu, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A typical sequence for the design of a controller, given the desired objectives, is the following: system modeling, design and mathematical analysis, simulation studies, emulation, and experimental implementation. Most control courses thoroughly cover design and mathematical analysis and utilize a simulation or experimental project at the end of the course. However, animation and emulation are seldom utilized and projects rarely cover the entire controller design sequence. This paper presents a control laboratory system developed at the University of Missouri at Rolla that integrates simulation, animation, emulation, and experimental components. The laboratory system may be applied to a wide variety of …

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A Methodology For Model Selection In Engineering Design, Rajesh Radhakrishnan, Daniel A. Mcadams Jan 2005

A Methodology For Model Selection In Engineering Design, Rajesh Radhakrishnan, Daniel A. Mcadams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Engineering design consists of a series of stages during which a number of decisions need to be made by the designer. Since the information available to the designer is limited during initial design stages, to make these decisions and be able to proceed further in the design process, the designer needs to depict the nature, visualize the form, and predict the behavior of the product through the use of aids called models. These models guide these decisions; therefore, the designer needs to ensure the downstream validity of these decisions by constructing models with sufficient accuracy and resolution. Because higher quality …

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Multiple Spacecraft Formation Control Using Θ - D Method, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka Jan 2005

Multiple Spacecraft Formation Control Using Θ - D Method, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multiple spacecraft formation control about the L2 libration point is investigated in this paper. the circular restricted three-body problem with Sun and Earth as the two primaries is utilized as a framework of study. the idea of virtual structure is considered as the architecture of multiple spacecraft formation. the center of the virtual rigid body follows a nominal orbit around the L2 libration point. the individual spacecraft is controlled so as to keep a constant relative distance from the center of the virtual structure. a nonlinear model is developed that describes the relative formation dynamics. This nonlinear control problem was …

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Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha Jan 2005

Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Online trained neural networks have become popular in recent years in designing robust and adaptive controllers for dynamic systems with uncertainties in their system equations because of their universal function approximation property. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled uncertainties. The controller design is carried out in two steps: (i) synthesis of a set of online neural networks that capture the uncertainties in the plant equations on-line (ii) re-optimization of the existing optimal controller to drive the states of the plant to a desired reference …

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A Model Of Function-Based Representations, Michael Van Wie, Cari R. Bryant, Matt R. Bohm, Robert B. Stone, Daniel A. Mcadams Jan 2005

A Model Of Function-Based Representations, Michael Van Wie, Cari R. Bryant, Matt R. Bohm, Robert B. Stone, Daniel A. Mcadams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The need to model and to reason about design alternatives throughout the design process demands robust representation schemes of function, behavior, and structure. Function describes the physical effect imposed on an energy or material flow by a design entity without regard for the working principles or physical solutions used to accomplish this effect. Behaviors are the physical events associated with a physical artifact (or hypothesized concept) over time (or simulated time) as perceived by an observer. Structure, the most tangible concept, partitions an artifact into meaningful constituents such as features, Wirk elements, and interfaces in addition to the widely used …

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