| Finite Set Control Transcription for Optimal Control Applications |
May-2009 |
260 pages |
| Authors:
Stuart A Stanton; TEXAS UNIV AT AUSTIN
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 | An enhanced method in optimization rooted in direct collocation is formulated to treat the finite set optimal control problem. This is motivated by applications in which a hybrid dynamical system is subject to ordinary differential continuity constraints, but control variables are contained within finite spaces. Resulting solutions display control discontinuities as variables switch between one feasible value to another. Solutions derived are characterized as optimal switching schedules between feasible control ... |
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| Evaluation of the Haltere as a Biologically-Inspired Inertial Rate Sensor |
Mar-2009 |
16 pages |
| Authors:
R A Thompson; M F Wehling; J E Evers; W E Dixon; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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| Since as early as the 1940's, specialized structures on dipteran insects have been recognized as necessary for inertial measurement associated with basic flight stability. These structures, called halteres, have been suggested to act as vibrating structure gyroscopes, measuring strains proportional to Coriolis accelerations. As a miniature, robust means for stabilizing flight, this biological inertial measurement system is not only of interest to biologists, but also to designers of biomimetic robotic ... |
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| Tuning of the Preferred Optic Flow Axes of Locust and Blowfly Visual Interneurons to Their Preferred Modes of Flight Behaviour |
17-Dec-2008 |
6 pages |
| Authors:
Holger G Krapp; R J Bomphrey; S B Laughlin; G K Taylor; D G Wuestenberg; IMPERIAL COLL LONDON (UNITED KINGDOM) DEPT OF BIOENGINEERING
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| This report results from a contract tasking Imperial College London as follows: The grantee will investigate the sensory mechanisms of gaze stabilization and flight control on insects (flies and locusts). The study aims at understanding the underlying biological design principles. The research includes techniques ranging from neurophysiology and neuroanatomy to quantitative behavioral observations complemented by analytical and numerical modeling. Focus is on multi-sensory integration (visual and mechanosensory information), biophysical mechanisms ... |
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| Coordinated Control of a Planar Dual-Crane Non-Fully Restrained System |
Dec-2008 |
415 pages |
| Authors:
Frank A Leban; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this dissertation a control scheme that would provide motion compensation for a ship-based two-crane system suspending a single payload was developed. Historical experience during the conflict in Vietnam, along with the introduction of standard containerized packaging have steered military sustainment logistics towards a reliance on commercially developed cranes for discharge of containers - even for instream lightering operations. With the inclusion of Seabasing as one of the Navy's pillars, ... |
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| Modal Synthesis of a Non-Proportionally Damped, Gyroscopically Influenced, Geared Rotor System via the State-Space |
01-Sep-2008 |
35 pages |
| Authors:
ARMY RESEARCH LAB CLEVELAND OH VEHICLE TECHNOLOGY DIRECTORATE
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| Modal synthesis provides for degree-of-freedom reduction and model simplification. This report presents a method for conducting modal synthesis on a geared rotor dynamic system under the influences of non-proportional damping and gyroscopic effects. Based on the familiar first-order, state-space methodology, a coordinate transformation is developed for diagonalizing the state-space equations of motion for each substructure of the system. A modal synthesis procedure then assembles the system equations of motion from ... |
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| Closed Loop Adaptive Refinement of Dynamical Models for Complex Chemical Reactions |
26-Jun-2008 |
16 pages |
| Authors:
Herschel Rabitz; PRINCETON UNIV NJ OFFICE OF RESEARCH AND PROJECT ADMINISTRATION
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| This research is concerned with the development of a systematic method for efficiently performing molecular dynamics (MD) simulations of complex chemical reactions and optimizing the underlying potential energy surfaces (PESs), ultimately using suitable laboratory data in a closed loop fashion. Two main objectives of the research are to (a) identify key parameters of each PES based on the global non-linear input-output Random Sampling High Dimensional Model Representation (RS-HDMR) mapping technique ... |
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| Response of an Acoustic Coating on a Rib-Stiffened Plate |
06-Jun-2008 |
45 pages |
| Authors:
Andrew J Hull; John R Welch; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
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| This report develops an analytical model of a fluid-loaded acoustic coating affixed to a rib-stiffened plate. The model is three-dimensional and has fully-elastic behavior. The system is loaded by a plane wave that is harmonic both spatially and temporally. The model begins with Naviers' equations of motion of an elastic solid, which produces unknown displacement fields that are inserted in to stress equations at the boundaries of the plate and ... |
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| Experimental Validation of a Coupled Fluid-Multibody Dynamics Model for Tanker Trucks |
APR 2008 |
41 pages |
| Authors:
Tamer M. Wasfy; James O'Kins; Scott Smith; ADVANCED SCIENCE AND AUTOMATION CORP INDIANAPOLIS IN
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| Outline: *Motivation. *Objective. *Literature Review. *FE Formulation: -Solid: Frictional contact model, Simple tire model, Detailed tire model. -Fluid; -Free-surface model; -Fluid-structure coupling. *Validation Study. *Concluding Remarks. |
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| Mathematical Fluid Dynamics of Store and Stage Separation, Multi-Body Flows and Flow Control |
FEB 2008 |
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| Authors:
Norman D. Malmuth; Alexander V. Fedorov; TELEDYNE SCIENTIFIC AND IMAGING LLC THOUSAND OAKS CA
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 | New insights have been gained in atmospheric and space launch stage separation from our studies of the aerodynamic interference between multiple bodies in supersonic flow. Quick means of estimating and controlling repulsion or attraction lift is an important enabling technology to size launch separation rocket motors. Asymptotic methods, scattering, slender body theories and CFD modeling have provided valuable systematic approximations schemes that advantageously couple with modern computational methods. Our theoretical ... |
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| The Implementation and Testing of a Robotic Arm on an Autonomous Vehicle |
DEC 2007 |
51 pages |
| Authors:
Hyun Il Jun; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| An articulated arm with three degrees of freedom is implemented and tested on an autonomous robot. Kinematic equations of motion for the arm are modeled and tested. A communication architecture is successfully implemented for wireless manual control of the arm. Visual and thermal cues are realized with an onboard camera and a collocated thermal sensor. Future work suggests investigations for full autonomous arm control without manual operator intervention based on ... |
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| Experimental Validation of a Coupled Fluid-Multibody Dynamics Model for Tanker Trucks |
08 NOV 2007 |
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| Authors:
Tamer M. Wasfy; James O'Kins; Scott Smith; ADVANCED SCIENCE AND AUTOMATION CORP INDIANAPOLIS IN
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| A time-accurate finite element model for predicting the coupled dynamic response of tanker trucks and their liquid payloads is presented along with an experimental validation of the model. The tanker truck components are modeled using rigid bodies, flexible bodies, joints and actuators. The model is validated using a full-scale army heavy class tactical trailer carrying a water tank. The trailer is placed on an n-post motion base simulator which was ... |
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| Math-Based Simulation Tools and Methods |
10 OCT 2007 |
17 pages |
| Authors:
Sudhakar Arepally; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND WARREN MI
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| These briefing charts review numerous mathematical methods for simulating crashworthiness and occupant protection in motor vehicles. The following methods are reviewed: matrix operations, ordinary and partial differential system of equations, Lagrangian operations, Fourier transforms, Taylor Series, Finite Difference Methods, implicit and explicit finite element methods, and statistical methods (probabilistic and regression analysis). The slides are labeled as follows: HMMWV 30-mph Rollover Test, Soldier Gear Effects, Occupant Performance in Blast Effects, ... |
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| Improving the Coverage of Earth Targets by Maneuvering Satellite Constellations |
23 AUG 2007 |
9 pages |
| Authors:
Michel Santos; Benjamin Shapiro; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
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| Satellite constellations around Earth can be used for observing and/or communicating with targets on the surface. This research mainly addressed maneuvering existing satellite constellations in order to improve coverage of multiple targets over a timespan of 30 to 120 days. However, designing new satellite constellations can also be addressed by using a portion of this research regarding coverage estimation. This research identified a direct relationship between a satellite's orbital geometry ... |
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| On-Line Trajectory Optimization for Autonomous Air Vehicles |
31-Jul-2007 |
91 pages |
| Authors:
Anthony Calise; Eric Johnson; Shannon Twigg; Tobias Ries; Bong-Jun Yang; J E Corban; GUIDED SYSTEMS TECHNOLOGIES MCDONOUGH GA
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| Successful operation of next-generation unmanned air vehicles will demand a high level of autonomy. Autonomous low-level operation in a complex environment dictates a need for onboard, robust, reliable and efficient trajectory optimization. In this report, we develop and demonstrate an innovative combination of traditional analytical and numerical solution procedures to produce efficient, robust and reliable means for nonlinear flight path optimization in the presence of time-varying obstacles and threats. The ... |
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| An Overview of MAV Research at Brigham Young University |
MAY 2007 |
21 pages |
| Authors:
Timothy W. McLain; Randal W. Beard; D. B. Barber; Nathan B. Knoebel; BRIGHAM YOUNG UNIV PROVO UT
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| This paper summarizes research efforts at Brigham Young University related to the control of miniature aerial vehicles (MAVs). Recent results in the areas of vector field path following, precision landing and target prosecution, target localization, obstacle detection and avoidance, tailsitter aircraft control, and cooperative control are presented. |
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| Experimental Validation of a Time-Accurate Finite Element Model for Coupled Multibody Dynamics and Liquid Sloshing |
16 APR 2007 |
17 pages |
| Authors:
Tamer M. Wasfy; James O'Kins; Scott Smith; ADVANCED SCIENCE AND AUTOMATION CORP INDIANAPOLIS IN
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| A study for validating a time-accurate explicit finite element code for modeling fully-coupled flexible multibody systems carrying liquid-filled tanks is presented. The multibody system includes rigid bodies, flexible bodies, joints, and actuators. Rigid bodies rotational equations of motion are written in a body-fixed frame with the total rigid body rotation matrix updated each time step using incremental rotations. Flexible bodies are modeled using total-Lagrangian spring, truss, beam and hexahedral solid ... |
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| Functionally Graded Shape Memory Alloy Composites Optimized for Passive Vibration Control |
20 NOV 2006 |
23 pages |
| Authors:
Victor Birman; MISSOURI UNIV-ROLLA ENGINEERING EDUCATION CENTER
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| The author has developed a methodology for the dynamic analysis of composite and isotropic plates supported by functionally graded shape memory alloy wires embedded in sleeves. The solution of the equations of motion is obtained for shear deformable plates using the first order shear deformation theory and for thin plates by the classical plate theory. Two designs of functionally graded shape memory alloy reinforcements are considered, including wires in sleeves ... |
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| Prediction of Local Penetration/Damage and Global Dynamic System Response for Lethality/Survivability: A Multi-Time Scale Approach |
NOV 2006 |
9 pages |
| Authors:
Y. Miller; X. Zhou; D. Sha; K. K. Tamma; MILITARY ACADEMY WEST POINT NY DEPT OF MECHANICS
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| The Future Combat Systems (FCS) will transform the Army into a faster, more agile force with more lethal and more survivable capabilities. The FCS requires computational technologies that can simulate and assess lethality and survivability of the combat systems under real battlefield situations involving the global structural dynamics at system level, and highly localized contact-impact, damage, failure, penetration, and fragmentation. In order to integrate the aforementioned capabilities into a stand ... |
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| Efficient Calculation of Earth Penetrating Projectile Trajectories |
SEP 2006 |
119 pages |
| Authors:
Daniel F. Youch; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL AND ASTRONAUTICAL ENGINEERING
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| Currently, two methods exist to determine trajectory of a ballistic penetrator: Poncelet Analysis and Differential Area Force Law (DAFL) methods. An exact solution for the Poncelet Equation exists; making for easy computation. However, the one dimensional nature of the equation fails to capture the intricate three-dimensional nature of real world ballistic penetrator trajectories. The DAFL methods employ empirically derived stress algorithms to calculate the forces acting on a differential area ... |
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| Natural Frequencies and Mode Shapes of a Nonlinear, Uniform Cantilevered Beam |
SEP 2006 |
207 pages |
| Authors:
Daniel J. Marquez-Chisolm; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| A series of experiments in 1975, referred to as the Princeton Beam Experiments, were performed to measure natural frequencies and create a nonlinear elastic deformation model to improve helicopter main beam designs. These experiments used a homogeneous 7075 aluminum beam and have been referenced as a baseline for the past thirty years to validate computer models and theories in an effort to build beams capable of withstanding aero-elastic, static, and ... |
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| Nonlinear Wave Interaction with Submerged and Surface-Piercing Porous Structures |
SEP 2006 |
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| Authors:
Okey Nwogu; Zeki Demirbilek; MICHIGAN UNIV ANN ARBOR DEPT OF NAVAL ARCHITECTURE AND MARINE ENGINEERING
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| A coupled Boussinesq-boundary integral method is developed to simulate nonlinear water wave interaction with structures consisting of multiple layers with different physical and hydraulic characteristics. The flow field in the water region is modeled with a modified set of Boussinesq-type equations, with additional terms to account for the flow of water into/out of the porous region. The equations of motion for the porous regions include an empirical Forchheimer-type term for ... |
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| LQG/LTR Optimal Attitude Control of Small Flexible Spacecraft Using Free-Free Boundary Conditions |
03 AUG 2006 |
220 pages |
| Authors:
Joseph M. Fulton; COLORADO UNIV AT BOULDER DEPT OF AEROSPACE ENGINEERING SCIENCES
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| Due to the volume and power limitations of a small satellite, careful consideration must be taken while designing an attitude control system for 3-axis stabilization. Placing redundancy in the system proves difficult and utilizing power hungry, high accuracy, active actuators is not a viable option. Thus, it is customary to find dependable, passive actuators used in conjunction with small scale active control components. This document describes the application of Elastic ... |
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| Including Nearshore Processes in Phase-Averaged Hydrodynamics Models |
AUG 2006 |
47 pages |
| Authors:
Bradley D. Johnson; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| The large spatial and time scales of the numerical modeling projects of the U.S. Army Corps of Engineers (USACE) requires the use of computationally efficient phase-averaged hydrodynamic models derived by averaging the equations of motion over a representative short wave period. Guidance in modeling nearshore regions with phase-averaged hydrodynamic models is provided herein. Physical processes unique to the surf zone are described along with methods of incorporating these effects to ... |
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| Moments on a Coning M864 by a Liquid Payload: The Candlestick Problem and Porous Media |
JUL 2006 |
26 pages |
| Authors:
Gene R. Cooper; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Moments that are caused by a payload assumed to be an inviscid liquid flowing in a coning projectile are predicted. This payload is contained in a uniform sequence of end-to-end cylinders stacked in columns along and off the symmetry axis of the projectile. A theoretical model is used to analyze inertial waves passing through the liquid, which are generated by the coning motion. This analysis continues by considering a single ... |
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| Maneuver Estimation Model for Geostationary Orbit Determination |
JUN 2006 |
123 pages |
| Authors:
Brian J. Hirsch; AIR FORCE INST OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| As an increasing number of geostationary satellites fill a limited number of orbital slots, collocation of satellites leads to a risk of close approach or misidentification. The ability to detect maneuvers made by these satellites using optical observations can help to prevent these problems. Such a model has already been created and tested using data from the Air Force Maui Optical and Supercomputing site. The goal of this research was ... |
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| Theoretical Modeling of the Transient Effects of a Towline Using the Method of Characteristics |
JUN 2006 |
136 pages |
| Authors:
Christopher A. Hill; AIR FORCE INST OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The use of decoys in combat has become more advanced in recent years. Some of the newest military aircraft, such as the US Navy's F/A-18E/F Superhornet, have the capability to deploy a towline with an attached decoy when entering hostile territory as a defense mechanism against enemy threats. In steady state, the towline extends behind and below the aircraft. A major concern is the position of the towline, as aircraft ... |
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| Development and Validation of Reentry Simulation Using MATLAB |
MAR 2006 |
146 pages |
| Authors:
Jr Jameson Robert E.; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This research effort develops a program using MATLAB to solve the equations of motion for atmospheric reentry and analyzes the validity of the program for use as a tool to expeditiously predict reentry profiles. The reentry vehicle is modeled as a point mass with constant aerodynamic properties as defined by the user. The equations of motion for reentry are based on the two-body problem. The atmosphere is modeled as a ... |
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| The Effects of Using Solar Radiation Pressure to Alleviate Fuel Requirements for Orbit Changing and Maintenance of the DSCS II F-13 Satellite |
MAR 2006 |
155 pages |
| Authors:
Jody A. Paris; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Orbit disposal and maintenance of aging satellites has become a significant concern over the past few years, as the increasing number of orbiting objects threatens to limit the launching of future satellites. Many of the satellites currently in orbit, however, were not built with disposal considerations. The DSCS II series was launched into orbit beginning in the 1970s, and many satellites are now without the fuel required to conventionally transition ... |
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| Formation Flight Control for Aerial Refueling |
MAR 2006 |
280 pages |
| Authors:
Steven M. Ross; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| A controller is designed for an aircraft to autonomously fly formation during aerial refueling. Requirements for a refueling autopilot are stated. A six-degree-of-freedom model is developed for an F-16 lead aircraft and a Learjet LJ-25 wing aircraft. Bare airframe stability of both aircraft is investigated, and stability augmentation is performed. A Matlab Simulink (trademark) simulation is built to reproduce the sensor inputs that will be available to the wing aircraft ... |
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| Simulation of Weapons Release from Cargo Aircraft |
MAR 2006 |
212 pages |
| Authors:
Paul M. Wilson; AIR FORCE INST OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The purpose of this study is to develop a computer simulation capable of providing an accurate flight history of an air-dropped munitions dispenser system in order to conduct proof of concept testing. The simulation is intended to serve as an adaptable tool for the development and testing of any cargo aircraft based weapons dispenser system. The simulation allows the user to conduct low-cost, time efficient, and effective tests of various ... |
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| A Non-Linear Model for the Longitudinal Dynamics of a Hypersonic Air-breathing Vehicle |
2006 |
23 pages |
| Authors:
Michael A. Bolender; David B. Doman; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
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| A non-linear, physics-based model of the longitudinal dynamics for an air-breathing hypersonic vehicle is developed. The model is derived from first principles and captures the complex interactions between the propulsion system, aerodynamics, and structural dynamics. Unlike conventional aircraft, hypersonic vehicles require that the propulsion system be highly integrated into the airframe. Furthermore, hypersonic aircraft tend to have very lightweight, flexible structures that have low natural frequencies. Therefore, the first bending ... |
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| Parametric Study of the Towline Shape of an Aircraft Decoy |
19 OCT 2005 |
80 pages |
| Authors:
Tyler L. Richardson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Some of today's aircraft use decoys as a defense against enemy weapons. The decoy is towed behind the aircraft with the intention of attracting the weapon propagator by deception, trying to mislead the weapon into detecting it instead of the aircraft. An aircraft deploys a decoy via a towline extending out behind and below the aircraft. However, during some maneuvers, the towline moves up into the jet exhaust plume of ... |
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| Investigation of the Performance Characteristics of Re-Entry Vehicles |
SEP 2005 |
85 pages |
| Authors:
Charles A. Bilbey; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| When a non-US spacecraft reenters the Earth's atmosphere, having the ability to accurately determine its performance characteristics is a primary concern. This study investigated the atmospheric re-entry profiles of a maneuverable re-entry vehicle. The re-entry vehicle was modeled as a point mass with aerodynamic properties. Equations of motion were numerically integrated, giving the time histories of position, velocity and flight path angle. The algorithm is able to generate a complete ... |
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| The Effect of Aerodynamic Surfaces Versus Thrust Maneuvers on Reentry Vehicles |
SEP 2005 |
85 pages |
| Authors:
Meredith M. Albrecht; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This research effort analyzes the effect of aerodynamic surfaces versus thrust maneuvers on a reentry vehicle. At high altitudes the effect of aerodynamic surfaces on the reentry vehicle is small due to low atmospheric density; however as the vehicle reaches lower altitudes a lift maneuver is very successful in deflecting the vehicle and creating a large impact footprint. When a continuous thrust maneuver is input in the place of a ... |
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| Modeling Relative Position Relative Velocity and Range Rate for Formation Flying |
31 AUG 2005 |
23 pages |
| Authors:
Craig A. McLaughlin; Chris Sabol; Aaron Swank; Richard D. Burns; K. K. Luu; AIR FORCE RESEARCH LAB KIRTLAND AFB NMSPACE VEHICLES DIRECTORATE
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| The relative position, relative velocity, and range rate evolution is examined for various formations of satellites. A simple analytical model including Earth oblateness effects for the equations of relative motion is presented. This model provides physical insight into the Earth oblateness effects that are neglected by using Hill's equations. The accuracy of the relative position, relative velocity, and range rate predictions for the analytical model are compared to realistic force ... |
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| Modeling Ion Beam Neutralization and Near-Thruster Plume Interactions (POSTPRINT) |
31 AUG 2005 |
13 pages |
| Authors:
Lubos Brieda; Douglas VanGilder; Joseph Wang; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| Ion thruster plume interaction has been studied extensively in recent years. While most existing plume models have focused on charge-exchange ion interactions with the spacecraft and/or plume-induced contamination, few studies have examined the detailed physics near the thruster exit. In particular, the ion beam neutralization process and the characteristics of the neutralizing electrons are not well understood. This paper presents a full-PIC model for the near-thruster plume of a single ... |
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| An Assessment of the Biot-Stoll Model of a Poroelastic Seabed |
05 AUG 2005 |
83 pages |
| Authors:
James L. Buchanan; NAVAL RESEARCH LAB WASHINGTON DC ACOUSTIC SIGNAL PROCESSING BRANCH
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| This report evaluates the effectiveness of the Biot-Stoll model of a poroelastic seabed in predicting experimentally observed phenomena in underwater acoustics. Discussed in the report is the derivation of the model from physical principles, including more recent extensions such as the distributed pore size formulation of Turgut and Yamamoto and a more sophisticated approach to modeling intergranular effects advocated by Chotiros and Isakson. It is found that with the incorporation ... |
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| Investigations of Spacecraft Orbits Around the L(2) Sun-Earth Libration Point |
29 JUL 2005 |
178 pages |
| Authors:
Alan M. Segerman; Michael F. Zedd; NAVAL RESEARCH LAB WASHINGTON DC
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| Space agencies are planning missions to the vicinity of the Sun-Earth L sub 2 point, some involving a distributed system of telescope spacecraft, configured in a plane about a hub. An improved understanding is developed of their relative motion. First, the telescope equations of motion are written relative to L sub 2 in the context of the classical circular restricted three-body problem, and expanded in terms of the distance from ... |
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| Computation of Cavity Flow by Finite Element Method with Finite Spectral Shape Function |
14 APR 2005 |
7 pages |
| Authors:
Jian-Ping Wang; Yoshiaki Nakamura; Ting-Wen Li; PEKING UNIV BEIJING (CHINA)
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| The streamfunction-vorticity equations for two-dimensional cavity flow are solved by a new finite element method which uses finite spectral basis functions as shape functions for rectangular elements. Simulations for several cases with different Reynolds numbers are performed. Good agreement was obtained in the comparison between the present results with the bench mark solutions. |
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| Dynamic Response of a Fluid-Loaded Plate Containing Periodic Masses |
31 MAR 2005 |
47 pages |
| Authors:
Andrew J. Hull; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
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| This report derives the equations of motion of a fluid-loaded thin plate that contains periodically spaced embedded masses and is insonified by a harmonic plane wave. The thin plate equations of motion are coupled to the fluid and to the embedded masses and analyzed to determine the displacement field in the wave number-frequency domain. The masses of the periodic discontinuities are then varied to study their influence on the system ... |
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| Maneuver Estimation Model for Relative Orbit Determination |
21 MAR 2005 |
77 pages |
| Authors:
Tara R. Storch; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| While the use of relative orbit determination has reduced the difficulties inherent in tracking geosynchronous satellites that are in close proximity, the problem is often compounded by stationkeeping operations or unexpected maneuvers. If a maneuver occurs, observations will no longer fit predicted data, increasing the risk of misidentification and cross-tagging. The goal of this research was to develop a model that will estimate the magnitude, direction, and time of a ... |
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| Stability Analysis of a Towed Body for Shipboard Unmanned Surface Vehicle Recovery |
MAR 2005 |
81 pages |
| Authors:
Scott D. Roberts; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| As the U.S. Navy develops new technologies which enhance automation and reduce crew size onboard naval vessels, unmanned vehicles will become increasingly valuable in conducting maritime operations. Effective launch and recovery systems (LARS) are necessary for unmanned vehicles to efficiently conduct operations at sea. The Towed Body system is a LARS with a wide range of applications for unmanned vehicle operations. The Towed Body can be evaluated as a small ... |
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| Physically Nonlinear Behavior of Piezoelectric Actuators Subject to High Electric Fields |
08 FEB 2005 |
41 pages |
| Authors:
Victor Birman; MISSOURI UNIV-ROLLA
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| The paper is concerned with a physically nonlinear piezoelectric material behavior and its applications to practical problems. A survey of work dealing with the phenomenon is included in the introduction. Subsequently, the emphasis is on the analysis of vibrations of piezoelectric rods where a rather unique situation is observed, i.e. the response of a nonlinear system can be modeled by linear equations of motion. The solutions are obtained analytically by ... |
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| Inverse Method for Estimating the Wave Propagation Parameters of Two Dissimilar Wave Types |
19 JAN 2005 |
39 pages |
| Authors:
Andrew J. Hull; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A method is provided to distinguish two blended but different waves in a structure, such as compression and shear waves, by measuring their corresponding wave numbers and wave speeds. Other characteristics of the two waves may also be measured, such as the propagation coefficients of both waves. All measurements can be calculated at every frequency for which a transfer function measurement is made. The measurements do not depend on the ... |
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| Inlet Free Torpedo Launch System |
19 JAN 2005 |
27 pages |
| Authors:
Thomas J. Gieseke; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A launcher for torpedoes and underwater vehicles includes an inlet recess in fluid communication with a shutterway recess. A primary shutterway is provided both for ejection of the vehicle and for supplying fluid intake to the launcher. A pump circulates fluid from the inlet recess to the shutterway recess, and a launch tube houses a vehicle such as a weapon, within the launcher prior to launch thereof. A slide valve ... |
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| In Search of Efficient Walking Robots |
10 JAN 2005 |
7 pages |
| Authors:
Brooke Haueisen; Paul Muench; Greg Hudas; James Overholt; Peter Adamczyk; Greg Hulbert; TACOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
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| With the recent conflicts in Afghanistan and Iraq, it is increasingly evident that the demands of warfare are changing and the need for innovative mobility systems is growing. In the rough, unstructured terrain that the soldiers encounter, they have reverted to using mules and donkeys to move stealthily and quickly. In light of the growing need for autonomous systems, the Army is looking at the possibility of legged mobility options ... |
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| On Lagrangian Meshless Methods in Free-Surface Flows |
JAN 2005 |
73 pages |
| Authors:
Jon P. Silverberg; CALIFORNIA UNIV BERKELEY COMPUTATIONAL MARINE MECHANICS LABORATORY
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| Classically, fluid dynamics have been dealt with analytically because of the lack of numerical resources (Yeung, 1982). With the development of computational ability, many formulations have been developed which typically use the traditional Navier-Stokes equations along with an Eulerian grid. Today, there exists the possibility of using a moving grid (Lagrangian) along with a meshless discretization. The first issue in meshless fluid dynamics is the equations of motion. There are ... |
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| Dynamics of O(3P) Reactions with Gaseous, Liquid, and Solid Hydrocarbons |
10 NOV 2004 |
36 pages |
| Authors:
William L. Hase; WAYNE STATE UNIV DETROIT MI DEPT OF COMPUTER SCIENCE
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| This final report describes the initial two phases of the overall project. In the first phase, accurate barriers and energetics were calculated for 7 reactions involved in O(3P) oxidation of hydrocarbons. This was done by MRCI/CASSCF ab initio calculations with cc-pVTZ and cc-pVQZ basis sets and extrapolation to the complete basis set limit. For collisions of high- energy O(3P) atoms with hydrocarbons, the radical products contain sufficient internal energy to ... |
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| Model Testing and Numerical Simulations of Seakeeping Performance for High-Speed Vessels |
OCT 2004 |
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| Authors:
Allen H. Engle; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD STRUCTURES AND COMPOSITES DIV
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| Given the need to support the long distance deployment of men and material, the US Navy has been exploring the engineering limits and capabilities of open ocean operation for high-speed ships. Of great concern are the risks associated with: Ship Motions - Human Factors " " " Ship Dynamic Stability and Manoeuvring Ship Dynamic Loads In order to address these risks, an initial assessment of design tools has been be ... |
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| A Numerical Method for Computing Barge Impact Forces Based on Ultimate Strength of the Lashings Between Barges |
AUG 2004 |
220 pages |
| Authors:
Jose R. Arroyo; Robert M. Ebeling; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
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| In 1993 Headquarters, U.S. Army Corps of Engineers, issued the first formal Corps-wide analysis procedure providing guidance for analyzing the effects of barge impact loading on navigation structures. According to the ETL 1110-2-338 engineering procedure, the magnitude of the impact forces generated by a particular collision event is dependent on the mass including hydrodynamic added mass of the barge train, the approach velocity, the approach angle, the barge train moment ... |
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EQUATIONS OF MOTION
