| Speckle Interferometry at Soar in 2010 and 2011: Measures, Orbits, and Rectilinear Fits |
Feb 2012 |
20 pages |
| Authors:
William I Hartkopf; Andrei Tokovinin; Brian D Mason; NAVAL OBSERVATORY WASHINGTON DC
|
 | We report on the results of speckle observations at the 4.1 m SOAR telescope in 2010 and 2011. A total of 639 objects were observed. We give 562 measurements of 418 resolved binaries, including 21 pairs resolved for the first time, and upper detection limits for 221 unresolved stars. New orbital elements have been determined for 42 physical pairs, of which 22 are first-time calculations; the rest are corrections, sometimes ... |
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| Linear-Quadratic Control of a MEMS Micromirror using Kalman Filtering |
Dec 2011 |
91 pages |
| Authors:
Jamie P Schnapp; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The deflection limitations of electrostatic flexure-beam actuators are well known. Specifically, as the beam is actuated and the gap traversed, the restoring force necessary for equilibrium increases proportionally with the displacement to first order, while the electrostatic actuating force increases with the inverse square of the gap. Equilibrium, and thus stable open-loop voltage control, ceases at one-third the total gap distance, leading to actuator snap-in. A Kalman Filter is designed ... |
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| Byzantine Broadcast in Point-to-Point Networks using Local Linear Coding |
03 Nov 2011 |
24 pages |
| Authors:
Guanfeng Liang; Nitin Vaidya; ILLINOIS UNIV AT URBANA-CHAMPAIGN
|
| The goal of Byzantine Broadcast (BB) is to allow a set of fault-free nodes to agree on information that a source node wants to broadcast to them, in the presence of Byzantine faulty nodes. We consider design of efficient algorithms for BB in point-to-point networks where the rate of transmission over each communication link is limited by its link capacity. Given an algorithm A to solve BB in a network ... |
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| Using Impact Modulation to Identify Loose Bolts on a Satellite |
21 Oct 2011 |
140 pages |
| Authors:
Janette Jaques; Doug Adams; PURDUE UNIV LAFAYETTE IN
|
| This report investigates the use of Impact Modulation (IM) as a means for detecting loose bolts in a satellite structure. First, a two-beam, one-bolt assembly is studied to establish guidelines for implementing IM. Then, theoretical models are developed to provide a basis for applying IM to bolted joints. Two analysis methods for identifying loose bolts within a structure are then proposed. These methods are demonstrated on a three-beam, two-bolt structure; ... |
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| Control of Spatially Inhomogeneous Shear Flows |
Oct 2011 |
13 pages |
| Authors:
Dan S Henningson; Reza Dadfar; Onofrio Semeraro; Shervin Bagheri; Luca Brandt; ROYAL INST OF TECH STOCKHOLM (SWEDEN) DEPT OF MECHANICS
|
| It was demonstrated the possibility to delay the transition process using a feedback controller based on localized sensors/actuators. Three-dimensional TS wave packets and streaks with finite amplitudes are considered; reduced-order models based on balanced truncation are built and used for the control design. The controller mitigates the disturbances amplitude when the flow is still laminar but nonlinear, resulting in a significant reduction of the perturbation energy and, later, in a ... |
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| Ultrashort Laser Pulse Propagation in Water |
30 Sep 2011 |
13 pages |
| Authors:
George W Kattawar; Alexei V Sokolov; TEXAS A AND M UNIV COLLEGE STATION DEPT OF PHYSICS
|
| The major objectives of this proposal are twofold. The first objective is to perform both an experimental and theoretical study of the factors affecting the propagation distance behavior of ultrashort (femtosecond) laser pulses in water. This study will be conducted in the so-called linear regime which involves laser intensities that are below the threshold where nonlinear effects set in. A fundamental problem, which will be resolved by this research, is ... |
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| Evaluation of LIDAR for Automating Recognition of Roads and Trails Beneath Forest Canopy |
Sep 2011 |
114 pages |
| Authors:
Steven L Muha; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis discusses the utility of evaluating Light Detection and Ranging (LiDAR) to automate the recognition of roads and trails beneath forest canopy on Digital Elevation Models (DEMs) for use in military and forestry applications. Data were analyzed from three separate locations, including low elevation mixed conifer Indian Creek Watershed in Trinity County, CA; High elevation mixed conifer Cold Creek Trailhead area in South Lake Tahoe, CA; and lowland mesic ... |
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| Phase Field Modeling of Twinning in Indentation of Transparent Crystals |
Sep 2011 |
38 pages |
| Authors:
J D Clayton; J Knap; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Continuum phase field theory is applied to study elastic twinning in calcite and sapphire single crystals subjected to indentation loading by wedge-shaped indenters. An order parameter is associated with the magnitude of stress-free twinning shear. Geometrically linear and nonlinear theories are implemented and compared, the latter incorporating neo-Hookean elasticity. Equilibrium configurations of deformed and twinned crystals are attained numerically via direct energy minimization. Results are in qualitative agreement with experimental ... |
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| Holmium Doped Solid State Laser Resonantly Pumped and Q-Switched by Novel GaSb-Based Photonic Devices |
31 Aug 2011 |
|
| Authors:
STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF ELECTRICAL ENGINEERING
|
 | A highly efficient Ho3+-doped fluoride glass fiber laser operating at 2.08 micrometers is demonstrated using nearly resonant pumping at 1.94 micrometers by GaSb-based diode lasers. A maximum slope efficiency of 78% and output power above 500 mW were obtained. Asymmetric laser heterostructure was developed to improve beam properties of GaSb-based diode lasers. Multimode 100-micrometers-wide ridge waveguide lasers with 40 degrees fast axis beam divergence demonstrated output power of about 1.5 ... |
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| Analyzing C2 Structures and Self-Synchronization with Simple Computational Models |
JUN 2011 |
34 pages |
| Authors:
Anthony H. Dekker; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION (AUSTRALIA) JOINT OPERATIONS DIVISION
|
| Although Command and Control (C2) is a complex activity, useful lessons about C2 can be learned from simple computational models. In this paper, the author describes experiments with two such models. The Kuramoto Model, though it has some serious limitations, provides a representation of information flow and self-synchronization in an organization. A second (agent-based) model, based on factorization, provides a representation of planning that is slightly more realistic. These models ... |
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| Numerical Investigation of Serpentine Plasma Actuators for Separation Control at Low Reynolds Number |
Jun 2011 |
|
| Authors:
Mark Riherd; Subrata Roy; Miguel Visbal; FLORIDA UNIV GAINESVILLE DEPT OF MECHANICAL ENGINEERING
|
| Dielectric Barrier Discharge (DBD) plasma actuators with serpentine shaped electrodes cause a change in the operational behavior of the flow control mechanism relative to the standard linear actuator due to the introduction of fully three dimensional vortices. A parametric study is performed on a partially separated transitional flow over an SD7003 airfoil. This study examines the change in behavior as a function of geometric parameters, in particular the geometric amplitude ... |
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| Impact of Snow Removal Operations on Thermoplastic Pavement Markings |
MAR 2011 |
82 pages |
| Authors:
Monica L. Monfette; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This pilot study explored the effect snow removal operations have on thermoplastic pavement markings. Including snow removal as a separate independent variable is unique because much of the previous research performed on pavement marking degradation mentioned snow removal as a direct cause in a marking degrading more rapidly; however, it is mentioned as an afterthought and a suggestion to be considered in future research. This pilot study looked at 10 ... |
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| Digital Wideband Linear-FM Chirp Waveform Generator |
29 DEC 2010 |
44 pages |
| Authors:
David G. Kocher; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The design and performance of a digital linear-FM chirp waveform microwave generator having a maximum bandwidth capability of 16 GHz and minimum chirp duration of 102.4 ns are described along with techniques developed for the compensation of hardware errors. Emphasis is on optimization and characterization of chirp quality while operating with large bandwidths and chirp durations less than a microsecond. |
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| On the Number of Segments Needed in a Piecewise Linear Approximation |
MAY 2010 |
14 pages |
| Authors:
Christopher L. Frenzen; Tsutomu Sasao; Jon T. Butler; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF APPLIED MATHEMATICS
|
| The introduction of high-speed circuits to realize an arithmetic function f as a piecewise linear approximation has created a need to understand how the number of segments depends on the interval a less or equal to x less than b and the desired approximation error epsilon. |
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| Performance Analysis of Live-Virtual-Constructive and Distributed Virtual Simulations: Defining Requirements in Terms of Temporal Consistency |
Dec-2009 |
134 pages |
| Authors:
Douglas D Hodson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research extends the knowledge of live-virtual-constructive (LVC) and distributed virtual simulations (DVS) through a detailed analysis and characterization of their underlying computing architecture. LVCs are characterized as a set of asynchronous simulation applications each serving as both producers and consumers of shared state data. In terms of data aging characteristics, LVCs are found to be first-order linear systems. System performance is quantified via two opposing factors; the consistency of ... |
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| Nearest Neighbor Classification Using a Density Sensitive Distance Measurement |
Sep-2009 |
120 pages |
| Authors:
Joshua J Burkholder; NAVAL POSTGRADUATE SCHOOL MONTEREY CA MODELING VIRTUAL ENVIRONMENTS AND SIMULATION (MOVES)
|
| This work proposes a density sensitive distance measurement that takes into account the density of an underlying dataset to better represent the shape of the data when measuring distance. Kernel density estimation, using kernel bandwidths determined by k -nearest neighbor distances, is used to approximate the density of the underlying dataset. A scale is applied to the resulting kernel density estimate and a line integral is performed along its surface ... |
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| F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators |
Sep-2009 |
122 pages |
| Authors:
Joseph S Browning; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| Buffet-induced vibrations can have a disastrous impact on aircraft structures. Early attempts at combating buffet vibrations included passive methods such as structural enhancements and leading edge fences. Active methods have shown greater promise, including active airflow control, control surface modulation, and active structural control using piezoelectric actuators. Surface mounted piezoelectric actuators impart directional strain reducing the negative effects associated with harmful vibration. The Block-15 F-16 ventral fin represents an aircraft ... |
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| Theory and Evaluation of Battlefield Visualization in Context |
Jun-2009 |
56 pages |
| Authors:
Celestine A Ntuen; NORTH CAROLINA AGRICULTURAL AND TECHNICAL STATE UNIV GREENSBORO ARMY CENTER FOR HUMAN-CENTRIC COMMAND AND CONTROL DECISION MAKING
|
| This paper describes an on-going effort to develop operational visualization concepts and their technical implementations to support sensemaking skills based on the Army's Field Manual (FM) 3-0 doctrinal information on Visualization, Detection, and Decide requirements. A theory of visualization is presented from the stance that visualization is embedded and situated in human endeavors, and its cognitive activities. A visualization tool from Sensemaking Support System (S3) is used to evaluate this ... |
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| Multi-Channel and Multi-Dimensional Sensors Parametric Statistics Estimation |
Jun 2009 |
|
| Authors:
Jr Marple S L; OREGON STATE UNIV CORVALLIS SCHOOL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
|
| Parametric estimation, when expressed in the form of AR models, linear prediction analysis, lattice filters or minimum variance adaptive filters, has been a major foundation for enhanced signal processing performance. Examples include high resolution spectral analysis, linear prediction coding for bit rate reduction, and enhanced detection statistic performance for space-time adaptive processing (STAP) using parametric forms of the inverse covariance matrix. The mathematical matrix structures of most parametric estimators are ... |
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| A Theoretical Model Analysis of Absorption of a Three level Diode Pumped Alkali Laser |
Mar-2009 |
116 pages |
| Authors:
Lewis; Charlton D II; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This paper models the absorption phenomena of light in a three level diode pumped alkali laser system. Specifically this model calculates for a user defined set of system parameters the attenuation of the input pump beam and characteristics of the bleached wave. Using Wolfram's Mathematical 6.0 software all necessary physics for an accurate description of absorption was modeled from first principles: energy levels, cross sections, spin-orbit kinetic processes, saturation frequencies, ... |
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| Impacts of Sigma Coordinates on the Euler and Navier-Stokes Equations using Continuous Galerkin Methods |
Mar-2009 |
93 pages |
| Authors:
Sean L Gibbons; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| In this thesis, the impacts of transforming the coordinate system of an existing x-z mesoscale model to x-sigma_z are analyzed and discussed as they were observed in three test cases. The three test cases analyzed are: A rising thermal bubble, a linear hydrostatic mountain, and a linear nonhydrostatic mountain. The methods are outlined for the transformation of two sets (set 1, the non-conservative form using Exner pressure, momentum, and potential ... |
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| Wireless Network Cocast: Location-Aware Cooperative Communications with Linear Network Coding |
Jan-2009 |
29 pages |
| Authors:
Hung-Quoc Lai; Ahmed S Ray Ibrahim; K J Liu; ARMY COMMUNICATIONS-ELECTRONICS RESEARCH DEVELOPMENT AND ENG CTR FT MONMOUTH NJ
|
| In wireless networks, reducing aggregate transmit power and in many cases, having even power distribution increase the network lifetime. Conventional direct transmission (DTX) scheme results in high aggregate transmit power and uneven power distribution. In this paper, we consider location-aware cooperation-based schemes namely immediate-neighbor cooperation (INC), maximal cooperation (MAX), and wireless network cocast (WNC) that achieve spatial diversity to reduce aggregate transmit power and even power distribution. INC utilizes two-user ... |
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| Cycling the Representer Method With Nonlinear Models |
Jan-2009 |
23 pages |
| Authors:
Scott R Smith; Hans E Ngodock; Gregg A Jacobs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Realistic dynamic systems are often strongly nonlinear, particularly those for the ocean and atmosphere. Applying variational data assimilation to these systems requires the linearization of the nonlinear dynamics about a background state for the cost function minimization, except when the gradient of the cost function can be analytically or explicitly computed. Although there is no unique choice of linearization, the tangent linearization is to be preferred if it can be ... |
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| Summary Diagrams for Coupled Hydrodynamic-Ecosystem Model Skill Assessment |
Jan-2009 |
22 pages |
| Authors:
Bradley Penta; Robert Helber; Jason K Jolliff; Igor G Shulman; John C Kindle; Robert A Arnone; Marjorie A M Friedrichs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| The increasing complexity of coupled hydrodynamic-ecosystem models may require skill assessment methods that both quantify various aspects of model performance and visually summarize these aspects within compact diagrams. Hence summary diagrams, such as the Taylor diagram (Taylor, 2001. Journal of Geophysical Research. 106. D7. 7183-7192). may meet this requirement by exploiting mathematical relationships between widely known statistical quantities in order to succinctly display a suite of model skill metrics in ... |
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| Economic Security and National Security -- Interaction and Synthesis |
Jan-2009 |
43 pages |
| Authors:
James G Rickards; OMNIS INC MCLEAN VA
|
| National security has never been more captive to economic security than it is today. Economic security is not restricted to the usual fluctuations in gross domestic product (GDP), employment, productivity, and other metrics that have been the focus of macroeconomists for decades. Instead, in the present context, economic security refers to global capital flows and the capital and commodities markets which accommodate those flows. Through these channels currencies can be ... |
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| Terminal Control of a Variable-Stability Slender Reentry Vehicle |
02 JUN 2008 |
137 pages |
| Authors:
Matthew T. Karmondy; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| Various terminal control schemes are applied to a proposed slender reentry vehicle, controlled by two separately-articulating flaps. The flap deflections are summarized as symmetric and asymmetric flap deflections; the former manipulates the drag, lift-curve slope, and static margin; the latter controls the vehicle trim characteristics. The control problem is interesting because the static margin can be actively controlled from statically stable in pitch to statically unstable in pitch. Deflection limits ... |
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| The Impact of Operations Tempo (OPTEMPO) on Intentions to Depart the Military. Does the Increase of OPTEMPO Cause Action |
01-Mar-2008 |
134 pages |
| Authors:
Nathan P Olsen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Recent information in the field of Operations Tempo (OPTEMPO) has resulted in conflicting information on its effect on turnover intentions. This study evaluated the August 2004 Status of Forces Survey to determine if the sample demonstrated OPTEMPO had a curvilinear effect on turnover intentions when accounting for the moderators job satisfaction and organizational commitment while controlling for rank and gender. Linear regressions were used to determine if the relationship between ... |
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| Improved Feature Extraction, Feature Selection, and Identification Techniques That Create a Fast Unsupervised Hyperspectral Target Detection Algorithm |
MAR 2008 |
245 pages |
| Authors:
Robert J. Johnson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| This research extends the emerging field of hyperspectral image (HSI) target detectors that assume a global linear mixture model (LMM) of HSI and employ independent component analysis (ICA) to unmix HSI images. Via new techniques to fully automate feature extraction, feature selection, and target pixel identification, an autonomous global anomaly detector, AutoGAD, has been developed for potential employment in an operational environment for real-time processing of HSI targets. For dimensionality ... |
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| Binary Chirped Grating Diffractive Element for Sinusoidal to Linear Scanning Conversion: The Beam Propagation Design (Preprint) |
28-Jan-2008 |
15 pages |
| Authors:
Bahareh Haji-saeed; William Bailey; John Kierstead; Jed Khoury; Charles L Woods; AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE/ELECTROMAGNETICS TECHNOLOGY DIV
|
| We fabricated and tested our previously designed optical correction element with zoom capability to convert nonlinear sinusoidal scans into linear scans. The design methodology is based on derivating a graded index of refraction device as a reference design and converting the graded index of refraction into an amplitude or phase binarized diffractive element. Our graded index of refraction derivation is based on the propagation of an electromagnetic wave in an ... |
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| Location-Aware Cooperative Communications utilizing Linear Network Coding |
01-Jan-2008 |
6 pages |
| Authors:
Hung-Quoc Lai; Ahmed S Ibrahim; K J Liu; ARMY CECOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER FORT MONMOUTH NJ
|
| Cooperative communication can be used to reduce the transmit power of distant mobile units, compared to conventional direct transmission, given the same quality-of-service. However, imposing the constraint of having orthogonal transmission for the source and relays leads to large delay in TDMA systems. For a network of N mobile units, the transmission delay would be N(N +1)/2. In this work, we propose a location-aware cooperation-based scheme that aims to reduce ... |
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| Distributed Autonomous Control of Multiple Spacecraft During Close Proximity Operations |
DEC 2007 |
281 pages |
| Authors:
Shawn B. McCamish; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This research contributes to multiple spacecraft control by developing an autonomous distributed control algorithm for close proximity operations of multiple spacecraft systems, including rendezvous and docking scenarios. The proposed control algorithm combines the efficiency of the Linear Quadratic Regulator (LQR) and the robust collision avoidance capability of the Artificial Potential Function (APF) method. The LQR control effort serves as the attractive force toward goal positions, while the APF-based repulsive functions ... |
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| Comparing Organic vs. Assigned UAV Support to the Maneuver Company |
01 NOV 2007 |
29 pages |
| Authors:
MILITARY ACADEMY WEST POINT NY DEPT OF SYSTEM ENGINEERING
|
| The US Army has plans to deploy a dedicated UAV system at every echelon. However, there are disadvantages to fielding such a large number of different and separately controlled vehicles. This research addresses one key part of this issue of selecting the right mix of UAV systems: How shall a company be supported? We consider two alternatives for the company commander, loosely based on systems currently under development: (1) the ... |
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| Resource-Efficient Digital Communications: Research and Testbed Development in Support of Future Force Warrior and Joint Tactical Radio Systems |
NOV 2007 |
34 pages |
| Authors:
Thomas Fuja; Oliver Collins; Daniel Costello; Yih-Fang Huang; NOTRE DAME UNIV IN DEPT OF ELECTRICAL ENGINEERING
|
| This report describes the design and simulation of a bandwidth-efficient waveform suitable for the SLICE radio developed by ITT Aerospace/Communications; this waveform uses quadrature amplitude modulation (QAM) and low-complexity turbo codes developed at Notre Dame. The result is compared with another using continuous phase modulation (CPM). It is shown that the amplifier backoff required for QAM puts it at a disadvantage to CPM at spectral efficiencies where both are feasible ... |
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| PAR3D: Numerical Model for Incompressible Flow with Application to Aerosol Dispersion in Complex Enclosures |
SEP 2007 |
80 pages |
| Authors:
Robert S. Bernard; Phu V. Luong; Mario J. Sanchez; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| Abstract: This report documents the development of the PAR3D numerical flow model, with emphasis on modifications incorporated to facilitate simulations of contaminant dispersion in complex buildings and other enclosures. PAR3D is a general-purpose computational fluid dynamics (CFD) code for predicting three-dimensional flow and transport in air, water, and other incompressible fluids. It includes a two-equation turbulence model with adjustments for buoyancy, as well as transport equations for suspended materials (contaminants), ... |
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| Conversion and Verification Procedure for Goal-Based Control Programs |
15 AUG 2007 |
19 pages |
| Authors:
Julia M. Braman; Richard M. Murray; CALIFORNIA INST OF TECH PASADENA MATERIALS AND PROCESSES SIMULATION CENTER
|
| Fault tolerance and safety verification of control systems are essential for the success of autonomous robotic systems. A control architecture called Mission Data System, developed at the Jet Propulsion Laboratory, takes a goal-based control approach. In this paper, a method for converting goal network control programs into linear hybrid systems is developed. The linear hybrid system can then be verified for safety in the presence of failures using existing symbolic ... |
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| Discrimination of Objects Within Polarimetric Using Principal Component and Cluster Analysis |
AUG 2007 |
30 pages |
| Authors:
Melvin Felton; Kristan P. Gurton; David Ligon; Adrienne Raglin; ARMY RESEARCH LAB ADELPHI MD COMPUTATIONAL AND INFORMATION SCIENCES DIRECTORATE
|
| We apply two multivariate image analysis techniques to several sets of spatially coincident, long-wave infrared (LWIR), polarimetric images to improve target contrast and/or aid in the identification of certain object features not present in the original image set. Principal component analysis (PCA) was used to obtain new representations of the scene that highlight target features based upon the variance of the variables used in the analysis. We show a representation ... |
|
| Signal Processing Fault Detection System |
13 JUL 2007 |
28 pages |
| Authors:
Derke R. Hughes; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A fault detection system designed to evaluate the structural integrity of a material employs an array of sensors disposed over the material being evaluated. The sensors detect vibrations in the material and the sensor signals are fed to a data processor. The processor employs a method to analyze the linear and nonlinear characteristics of the sensor signals and then determines whether to proceed with a linear signal processing analysis or ... |
|
| Rotorcraft Smoothing Via Linear Time Periodic Methods |
JUL 2007 |
312 pages |
| Authors:
Christopher S. Schulz; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research presents the development of an on line linear time periodic rotor vibration controller. The Cramer-Rao bound is developed for a linear time periodic system in order to identify the quality of identified system parameters, which are used in system models for controller development. The methods developed in this work allow model parameters can be verified for accuracy and likewise adjusted to improve controller accuracy. |
|
| Control of a System in the Presence of Flexible Modes |
JUN 2007 |
65 pages |
| Authors:
Eleftherios Manos; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The primary research objective is to investigate the control of flexible space structures -- mobile satellite communication systems in particular. Solar-powered satellites require a high level of accuracy in attitude stabilization and large-angle maneuvering. Furthermore, they have to be least sensitive to disturbances affecting the structure, possibly coming from several sources, such as mechanical vibrations due to flexible panels appended to the spacecraft. In this thesis, we address the problem ... |
|
| Variability and Model Adequacy in Simulations of Store-Induced Limit Cycle Oscillations |
03 MAY 2007 |
48 pages |
| Authors:
Ashley S. Myers; NAVAL ACADEMY ANNAPOLIS MD
|
| A prominent phenomenon of the transonic flight regime is the potential for limit cycle oscillation (LCO) development. LCO is a stable oscillation produced by aeroelastic interactions within a component of the aircraft. Such oscillation shortens the fatigue life of the aircraft and increases the amount of maintenance necessary. These aspects are of great concern to the aerospace industry, particularly with high performance military aircraft that are required to operate beyond ... |
|
| A Computer-Aided Diagnosis System for Breast Cancer Combining Mammography and Proteomics |
MAY 2007 |
85 pages |
| Authors:
Jonathan Jesneck; DUKE UNIV MEDICAL CENTER DURHAM NC
|
| This study investigated a computer-aided diagnosis system for breast cancer by combining the following three data sources: mammogram films, radiologist-interpreted BI-RADS descriptors, and proteomic profiles of blood sera. We implemented under 100-fold cross-validation various classification algorithms, including Bayesian probit regression, iterated Bayesian model averaging, linear discriminant analysis, artificial neural networks, as well as a novel method of decision fusion. The top-performing classifier, decision fusion achieved AUC = 0.85 0.01 on ... |
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| Nonlinear Response Optimization Using Equivalent Loads for a Joined-Wing |
APR 2007 |
38 pages |
| Authors:
Gyung-Jin Park; HANYANG UNIV GYEONGGI-DO (SOUTH KOREA) DEPT OF MECHANICAL ENGINEERING
|
| Final report of research in geometric nonlinear response optimization of a joined-wing, carried out by using equivalent loads. The utilized structure is a joined-wing that is currently being developed in the US Air Force Research Laboratories (AFRL). The joined-wing is modeled for finite element analysis (FEA). Equivalent loads are the load sets which generate the same response field in linear analysis as that from nonlinear analysis. |
|
| The Matrix Pencil and its Applications to Speech Processing |
MAR 2007 |
152 pages |
| Authors:
Darren H. Haddad; Andrew J. Noga; AIR FORCE RESEARCH LAB ROME NY INFORMATION DIRECTORATE
|
| Matrix Pencils facilitate the study of differential equations resulting from oscillating systems. Certain problems in linear ordinary differential equations, such as speech processing, can be represented as the problem of finding a canonical pencil strictly equivalent to a given pencil. It was originally applied by the radar community to phased array radar for signal directional finding applications. The Matrix Pencil (MP) algorithm is a direct data approach, and is a ... |
|
| A Novel Method for Generating Non-Stationary Gaussian Processes for Use in Digital Radar Simulators |
MAR 2007 |
18 pages |
| Authors:
James A. Boehm; Patrick S. Debroux; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
|
| This report presents a novel and simple way to determine the transient response of the output of any linear system, described in the s-domain by an nth order polynomial, subjected to white Gaussian noise. The transient response of the output of the linear system is observed, in this report, in the variance of the output as a function of time. In addition, the mean and probability density function of the ... |
|
| Cycling the Representer Algorithm for Data Assimilation with the Lorenz Attractor |
FEB 2007 |
15 pages |
| Authors:
H. E. Ngodock; S. R. Smith; G. A. Jacobs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Realistic dynamic systems are often strongly nonlinear, particularly those for the ocean and atmosphere. Applying variational data assimilation to these systems requires a tangent linearization of the nonlinear dynamics about a background state for the cost function minimization. The tangent linearization may be accurate for limited time scales. Here it is proposed that linearized assimilation systems may be accurate if the assimilation time period is less than the tangent linear ... |
|
| Cost Cumulant-Based Control for a Class of Linear Quadratic Tracking Problems |
2007 |
7 pages |
| Authors:
Khanh D. Pham; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| The topic of cost-cumulant control is currently receiving substantial research from the theoretical community oriented toward stochastic control theory. For instance, the present paper extends the application of cost-cumulant controller design to control of a wide class of linear-quadratic tracking systems where output measurements of a tracker follow as closely as possible a desired trajectory via a complete statistical description of the associated integral-quadratic performance-measure. It is shown that the ... |
|
| On-Orbit Identification of Inertia Properties of Spacecraft using Robotics Technology |
DEC 2006 |
52 pages |
| Authors:
Ou Ma; NEW MEXICO STATE UNIV REGENTS LAS CRUCES
|
| This technical report describes the results of a 6-month research project conducted by Dr. Ou Ma and one of his graduate students at the New Mexico State University under the AFOSR grant number FA9550-06-1-0284 starting in May 2006. In the project, a methodology of on-orbit identification of spacecraft inertia properties (i.e., the mass, the location of the mass center, and the inertia tensor) using a robotic arm was investigated. The ... |
|
| An Exploration of Several Structural Measurement Techniques for Usage with Functionally Graded Materials |
DEC 2006 |
72 pages |
| Authors:
Robert Reuter; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Titanium / titanium boride functionally graded 6"x 1"x1" beams were subjected to a four-point beam test in order to critique the value of several measurement techniques. Also, finite element analysis results were compared with experimental values and general observations about the experiment were recorded. Uniform 85% TiB /15% Ti and uniform commercially pure titanium specimens were also subjected to the same loading conditions as a control. Techniques used include digital ... |
|
| Trajectory Control for Very Flexible Aircraft |
30 OCT 2006 |
47 pages |
| Authors:
Christopher M. Shearer; Cesnik E. Carlos; MICHIGAN UNIV ANN ARBOR
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| This paper focuses on trajectory control of the 6-DOF body fixed reference frame located on a very flexible aircraft. The 6-DOF equations of motion of a reference point on the aircraft are coupled with the aeroelastic equations that govern the geometrically nonlinear structural response of the vehicle. A low-order strain-based nonlinear structural analysis coupled with unsteady finitestate potential flow aerodynamics form the basis for the aeroelastic model. The nonlinear beam ... |
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| Hybrid Actuator for 3-Axis Control |
15 SEP 2006 |
66 pages |
| Authors:
peter C. Herdic; Robert D. Corsaro; Brian H. Houston; NAVAL RESEARCH LAB WASHINGTON DC
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| This report documents the development of a hybrid device for simultaneous 3-axis vibration reduction. This device was found to deliver ~30 to 45 dB downstream vibration reduction of both single and multiple tones. It is robust, reproducible, and sufficiently well-behaved that it can achieve this high performance level using just a base acceleration minimization. A key to its high performance is the ultra-low distortion provided by the highly linear single-crystal ... |
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Reports by Keyword(s)
LINEAR SYSTEMS
