| The Exponential Expansion of Simulation: How Simulation has Grown as a Research Tool |
Sep 2012 |
105 pages |
| Authors:
Matthew J Powers; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
 | Simulation has overcome critical obstacles to become a valuable method for obtaining insights about the behavior of complex systems. George Box's famous assessment that all models are wrong, some are useful referred to statistical models, but should now be reimagined to reflect that many simulation models are right enough to aid in decision making for important practical problems. Over the past fifty years, simulation has transformed from its beginnings as ... |
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| Analysis of the Motion of a Ball in the Barrel of a Musket |
Jan 2012 |
18 pages |
| Authors:
Carl E Mungan; John S Denker; NAVAL ACADEMY ANNAPOLIS MD DEPT OF PHYSICS
|
| The one-dimensional motion of a particle is analyzed when the force on it is inversely proportional to its displacement and directly proportional to the elapsed time. Such a force law describes a projectile in a musket barrel that is propelled by a hot ideal gas where either the number of moles or the temperature increases linearly with time due to the burning gunpowder. A particular solution to Newton?s second law ... |
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| Analytical Solution in Curvilinear Coordinates for the Trajectory of a Projectile Subject to Aerodynamic Drag |
Dec 2011 |
38 pages |
| Authors:
Steven B Segletes; William P Walters; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| An analytical study was conducted to determine the general trajectory of a projectile subject to aerodynamic drag in a gravitational field. A solution was obtained to the governing equations using curvilinear coordinates. The general solution analytically provides the pathlength of the projectile in terms of the current trajectory angle. Noticeably absent from the solution, however, are several desirable quantities. For instance, there is no ability to analytically express the trajectory ... |
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| Advances in Statistical and Deterministic Modeling of Wind-Driven Seas |
30 Sep 2011 |
11 pages |
| Authors:
Vladimir E Zakharov; WAVES AND SOLITONS LLC PHOENIX AZ
|
| The long-term goal of this research is the development of accurate, fast, and advanced statistical and dynamical nonlinear models of ocean surface waves based on first physical principles. These wave models will improve both long-term ocean surface wave forecasts and the prediction of strongly coherent events, such as freak waves, tsunamis, and wave breaking. The objectives of this project are as follows: (1) finding a physically correct wind input term ... |
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| Demonstration of the DSST State Transition Matrix Time-Update Properties Using the Linux GTDS Program |
Sep 2011 |
23 pages |
| Authors:
Paul J Cefola; Chris Sabol; Keric Hill; Daron Nishimoto; AIR FORCE RESEARCH LAB KIHEI MAUI HI DETACHMENT 15
|
| The semi-analytical theory for the motion of a space object replaces the conventional equations of motion with two formulas: (1) equations of motion for the mean equinoctial elements, and (2) expressions for the short periodic motion in the equinoctial elements. Very complete force models have been developed for the mean element equations of motion and for the short periodic motion. There is also a semi-analytical theory for the partial derivatives ... |
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| Unifying Capability Integration Analysis - Initial Insights |
Sep 2011 |
88 pages |
| Authors:
Leonard F Kerzner; DEFENCE RESEARCH AND DEVELOPMENT CANADA OTTAWA (ONTARIO) CENTRE FOR OPERATIONAL RESEARCH AND ANALYSIS
|
| In 2005, the Chief of Defence Staff (CDS) of the Canadian Forces (CF) mandated that Capability-Based Planning (CBP) be institutionalized as a part of a centrally driven, top-down approach to Force Development (FD) within the Department of National Defence (DND). For the last four years, military and defence analyst staffs have developed and implemented the first iteration of an end-to-end capability-based FD process. This process ultimately produces a list of ... |
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| Design and Characterization of a Space Based Chromotomographic Hyperspectral Imaging Experiment |
JUN 2011 |
384 pages |
| Authors:
Jason D. Niederhauser; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| This research focuses upon the design, analysis and characterization of several systems related to a spacebased chromotomographic experiment (CTEx), a hyperspectral imager, currently in development at the Air Force Institute of Technology. Three interrelated subject-areas were developed. The initial focal point was a generic, system-level mechanical layout and integration analysis of the space-based instrument. The scope of this work was intended to baseline the space-based system design in order to ... |
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| Capacity Optimization of MIMO Links with Interference |
Jun 2011 |
7 pages |
| Authors:
Peng Wang; John Matyjas; Michael Medley; AIR FORCE RESEARCH LAB ROME NY INFORMATION DIRECTORATE
|
| In this paper, we derive the capacity for MIMO links suffered from cochannel interference where each MIMO link is decomposed via SVD. Then, each eigenchannel of MIMO link is represented by a set of logical links with a set of discrete data rates and discrete powers. An Integer Programming based algorithm (named as IP) is presented to solve the capacity optimization problem. The solution specifies the set of logical links ... |
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| Spectra of Multiplication Operators as a Numerical Tool |
03 Mar 2011 |
24 pages |
| Authors:
B Vioreanu; V Rokhlin; YALE UNIV NEW HAVEN CT DEPT OF MATHEMATICS
|
| We introduce a numerical procedure for the construction of interpolation and quadrature formulae on bounded convex regions in the plane. The construction is based on the behavior of spectra of certain multiplication operators and leads to nodes which are inside a prescribed convex region in R(2). The resulting interpolation schemes are numerically stable and the quadrature formulae have positive weights and almost (but not quite) optimal numbers of nodes. The ... |
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| The Nonhydrostatic Unified Model of the Atmosphere (NUMA): CG Dynamical Core |
MAR 2011 |
26 pages |
| Authors:
Frank Giraldo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF APPLIED MATHEMATICS
|
| Partial contents: Collaborators/Acknowledgements, Overview of Existing Global Models, Design Philosophy, Non-Conservative Form (2NC), Example of 3D Grids, Domain Decomposition via METIS, Rising Thermal Bubble: 3Ds, Orographic Flows: Linear Hydrostatic and Nonhydrostatic Mountain (3D), 3D Linear Hydrostatic Mountain (Verification), Results (Global): Pressure Wave), Results (Global): Inertia-Gravity Wave, Urban-Scale Modeling, CG: Scalability (Explicit + Semi-Implicit). |
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| Theoretical Methods in the Non-Equilibrium Quantum Mechanics of Many Bodies |
2011 |
191 pages |
| Authors:
Andrew B. Robertson; MARYLAND UNIV COLLEGE PARK
|
| A toolbox of theoretical methods pertinent to the study of non-equilibrium many-body quantum mechanics is presented with an eye to specific applications in cold atoms systems and solids. We discuss the generalization from unitary quantum mechanics to the non-unitary framework of open quantum systems. Theoretical techniques include the Keldysh close-time-path integral and its associated correlation functions, the quantum kinetic equation, and numerical integration of equations of motion both unitary and ... |
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| A Three-Dimensional Receiver Operator Characteristic Surface Diagnostic Metric |
Oct 2010 |
12 pages |
| Authors:
Donald L Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Receiver Operator Characteristic (ROC) curves are commonly applied as metrics for quantifying the performance of binary fault detection systems. An ROC curve provides a visual representation of a detection system's True Positive Rate versus False Positive Rate sensitivity as the detection threshold is varied. The area under the curve provides a measure of fault detection performance independent of the applied detection threshold. While the standard ROC curve is well suited ... |
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| NOGAPS Semi-Lagrangian |
30 SEP 2010 |
9 pages |
| Authors:
Timonthy F. Hogan; NAVAL RESEARCH LAB MONTEREY CA
|
| The long-term goal of this project is to develop new dynamical core that would enable the Navy Operational Global Atmospheric Prediction System (NOGAPS) to achieve higher horizontal and vertical resolution, higher vertical extent, increase meteorological skill, and additional predictive constituents, all without an appreciable increase in run time efficiency. The objective of this project is to develop and transition semi-Lagrangian/semi-implicit (SL/SI) integration algorithm into the NOGAPS. The SL/SI numerical algorithm ... |
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| Enhancing Seismic Calibration Research Through Software Automation and Scientific Information Management |
Sep 2010 |
12 pages |
| Authors:
Douglas A Dodge; Michael D Ganzberger; Teresa F Hauk; Stanley D Ruppert; LAWRENCE LIVERMORE NATIONAL LAB CA
|
| The National Nuclear Security Administration (NNSA) Ground-Based Nuclear Explosion Monitoring Research and Development (GNEMRD) Program at Lawrence Livermore National Laboratory (LLNL) continues to make significant progress enhancing the process of deriving seismic calibrations and performing scientific integration analysis, and information management with software automation tools. Our tool efforts address the problematic issues of very large datasets and varied formats encountered during seismic calibration research. New information management and analysis tools ... |
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| Calculation of Impedance Matrix Inner Integral to Prescribed Precision |
18-Dec-2008 |
91 pages |
| Authors:
John S Asvestas; Stephen Yankovich; Oliver E Allen; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| We present a new method for evaluating the inner integral of the impedance matrix element in the traditional Rao-Wilton-Glisson formulation of the method of moments for perfect conductors. In this method we replace the original integrand (modified by a constant phase factor) by its Taylor series and keep enough terms to guarantee a number of significant digits in the integration outcome. We develop criteria that relate the number of Taylor ... |
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| Comparison and Validation of Point Spread Models for Imaging in Natural Waters |
20-Jun-2008 |
9 pages |
| Authors:
Alan Weidemann; Robert Arnone; Weilin Hou; Deric Gray; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
|
| It is known that scattering by particulates within natural waters is the main cause of the blur in underwater images. Underwater images can be better restored or enhanced with knowledge of the point spread function (PSF) of the water. This will extend the performance range as well as the information retrieval from underwater electro-optical systems, which is critical in many civilian and military applications, including target and especially mine detection, ... |
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| Mountain Wave Analysis Using Fourier Methods |
01 OCT 2007 |
73 pages |
| Authors:
John R. Roadcap; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Eigenanalysis of temperature and wind profiles can reveal distinct resonances at mesoscale wavelengths. Fourier transform methods are well suited to analyze resonant modes such as mountain waves due, in part, to (1) their fast computation speed for large wave number domains compared to numerical forecast models and (2) their requirements for only a coarse horizontal background state. Common traits of Fourier mountain wave models include use of the Boussinesq approximation ... |
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| Semi-Lagrangian Global Models |
30 SEP 2007 |
5 pages |
| Authors:
Timothy F. Hogan; NAVAL RESEARCH LAB MONTEREY CA
|
| The long-term goal of this project is to develop numerical integration algorithms that will enable then the Navy Operational Global Atmospheric Prediction System (NOGAPS) to achieve higher horizontal and vertical resolution, higher vertical extent, increase meteorological skill, and additional predictive constituents, all with no appreciable increase in run time efficiency. |
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| Continuous Quantum Computation |
MAR 2007 |
31 pages |
| Authors:
Joseph F. Traub; COLUMBIA UNIV NEW YORK DEPT OF COMPUTER SCIENCE
|
| The focus of this research was on developing quantum algorithms for continuous problems, complexity analysis of these algorithms, and their simulation and implementation. Continuous problems are a focus because much of physics, chemistry, and engineering depends on continuous mathematical formulations such as partial differential equations, path integration, approximation, and high-dimensional integration. New algorithms and quantum speedups were obtained for a number of important problems such as path integration, eigenvalues of ... |
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| A State Event Detection Algorithm for Numerically Simulating Hybrid Systems with Model Singularities |
Jan 2007 |
27 pages |
| Authors:
Joel M Esposito; Vijay Kumar; NAVAL ACADEMY ANNAPOLIS MD
|
| This paper describes an algorithm for detecting the occurrence of events, which signify discontinuities in the first derivative of the state variables, while simulating a set of non-smooth differential equations. Such combined-discrete continuous systems arise in many contexts and are often referred to as hybrid systems, switched systems, or non-smooth systems. In all cases the state events are triggered at simulated times which generate states corresponding to the zeros of ... |
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| Derivation of a Theory to Estimate the Kinetic Parameters for Systems with Multiple Substrates Competing for the Same Active Site on an Enzyme |
Dec-2006 |
20 pages |
| Authors:
J R Smith; Richard E Sweeney; David T Yeung; Douglas M Cerasoli; Donald M Maxwell; David E Lenz; ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD
|
| In studies to characterize the kinetic parameters for catalytic hydrolysis of the organophosphorus nerve agent 1,2,2-trimethylpropyl methylphosphonofluoridate (GD) by human paraoxonase (HuPON1), it was found that standard analysis techniques could not be employed because the kinetic parameters for the GD isomers were not significantly different from each other. Separation of the racemic mixture into component stereoisomers for individual study is feasible but extremely expensive. It was recognized that a theory ... |
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| Qubit Complexity of Continuous Problems |
09 DEC 2005 |
7 pages |
| Authors:
A. Papageorgiou; J. F. Traub; COLUMBIA UNIV NEW YORK DEPT OF COMPUTER SCIENCE
|
| The number of qubits used by a quantum algorithm will be a crucial computational resource for the foreseeable future. The authors show how to obtain the classical query complexity for continuous problems. They then establish a simple formula for a lower bound on the qubit complexity in terms of the classical query complexity. Sections discuss classical information complexity, fundamental concepts and notation for quantum computation, and lower bound on qubit ... |
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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
|
| 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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| Capon and Bartlett Beamforming: Threshold Effect in Direction-of-Arrival Estimation Error and On the Probability of Resolution |
16 MAY 2005 |
|
| Authors:
C. D. Richmond; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
 | Below a specific threshold signal-to-noise ratio (SNR), the mean squared error (MSE) perfor- mance of signal direction-of arrival (DOA) estimates derived from the Capon algorithm degrades swiftly. Prediction of this threshold SNR point is of practical significance for robust system design and analysis. The exact pairwise error probabilities for the Capon (and Bartlett) algorithm are derived herein, given by simple finite sums involving no numerical integration, include finite sample effects, ... |
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| Numerical Techniques for Approximating the Solution of Matrix ODE on the General Linear Group |
03 JAN 2005 |
49 pages |
| Authors:
Nicoletta Del Buono; Luciano Lopez; BARI UNIV (ITALY)
|
| Briefing charts only. |
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| The Capon-MVDR Algorithm Threshold Region Performance Prediction and Its Probability of Resolution |
20 DEC 2004 |
|
| Authors:
Christ D. Richmond; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The Capon-MVDR algorithm exhibits a threshold effect in mean-squared error (MSE) performance 1. Below a specific threshold signal-to-noise ratio (SNR) the MSE of signal parameter estimates derived from the Capon algorithm rises rapidly. Prediction of this threshold SNR point is clearly of practical significance for system design and performance. Via an adaptation of an interval error-based method referred to herein as the method of interval errors (MIE) 2, 3 the ... |
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| Maximum Likelihood Estimation of Compound-Gaussian Clutter and Target Parameters |
20 DEC 2004 |
10 pages |
| Authors:
Aleksandar Dogandzic; Jian Wang; Arye Nehorai; IOWA STATE UNIV AMES
|
| The compound-Gaussian model is often used in radar signal processing to describe the heavy-tailed clutter distribution. The important problems in compound-Gaussian clutter modeling are choosing the texture distribution and estimating its parameters. Many texture distribution models have been proposed 1, 2 and their parameters were typically estimated using the (statistically suboptimal) method of moments, see 2. In this paper, we develop maximum likelihood (ML) methods for jointly estimating target and ... |
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| The Numerical Weather Prediction System at the Italian Air Force Weather Service: Impact of Non-Conventional Observations and Increased Resolution |
JUN 2004 |
115 pages |
| Authors:
Lucio Torrisi; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The impact of non-conventional observations and increased horizontal resolution on the numerical weather prediction (NWP) system of the National Center for Aeronautic Meteorology and Climatology of the Italian Air Force (CNMCA) has been investigated. The present study is part of ongoing research activities whose goal is the improvement of CNMCA s operational numerical weather prediction capabilities through the assimilation of non-conventional observations. Additional data derived from satellite observations, such as ... |
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| Source/Receiver Motion-Induced Doppler Influence on the Bandwidth of Sinusoidal Signals |
DEC 2003 |
155 pages |
| Authors:
David J. Pistacchio; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Most self-propelled vessels moving on, or under, the ocean surface, contain rotating machinery that radiate finite bandwidth signals into the water. Empirical evidence suggests that the signal bandwidth estimated with a far field receiver is often greater than expected. This thesis investigates the use of an acoustic propagation model to predict the received bandwidth of sinusoidal signals when both the source and the receiver are in motion. The bandwidth parameter ... |
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| Joint Probability Density Function of Selected Order Statistics and the Sum of the Remainder as Applied to Arbitrary Independent Random Variables |
06 NOV 2003 |
22 pages |
| Authors:
Albert H. Nuttall; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| A set of N independent random variables (Xn! with arbitrary probability density functions ?pn(x)! are ordered into a new set of dependent random variables, each with a different probability density function. From this latter set, the M-1 largest random variables are selected. Then, the sum of the remaining N + 1 - M random variables is computed, giving a total of M dependent random variables. Several statistics are computed for ... |
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| Modelling of Heat and Mass Transfer Around Single Hot Particle Surrounded by a Vapor Layer and Liquid |
JUL 2002 |
|
| Authors:
A. A. Gubaidullin; I. N. Sannikov; E. A. Kosheleva; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSK INST OF THEORETICAL AND APPLIED MECHANICS
|
| The investigation of heat and mass transfer process around a single hot particle surrounded by vapor layer and liquid is actual due to a study of vapor explosion in the time of hard accidents on the nuclear reactors and metallurgy industry. The process of heat and mass transfer of vapor bubble at surrounding liquid was investigated well. However, insufficient attention was devoted a similarly process in the case of presence ... |
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| A 3D Parabolic Equation (PE) Based Technique for Predicting Propagation Path Loss in an Urban Area |
SEP 2001 |
108 pages |
| Authors:
Keem B. Thiem; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A mobile radio environment places fundamental limitations on the performance of wireless communication systems. Most models developed to predict propagation path loss have been historically performed in a statistical approach. These models are expensive to develop and do not offer the accuracy, computational advantages, and sufficiency as the parabolic equation (PE). The goal of this thesis is to develop a 3D model based on PE for predicting propagation path loss ... |
|
| Optimizing a Slingatron-Based Space Launcher Using MATLAB |
26 APR 2001 |
18 pages |
| Authors:
M. Bundy; G. Cooper; S. Wilkerson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A slingatron is the name given to a propellantless mechanical means of launching a projectile. To date, slingatrons are only conceptual in nature, but their potential use as a ground-to-space launch mechanism for unmanned payloads is under investigation. Slingatrons can be configured in a variety of geometries; one form consists of a spiral track (or launch tube) that gyrates at a constant frequency about a set radius. Under proper conditions ... |
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| Viscosity Parameterization and the Gulf Stream Separation |
19 JAN 2001 |
5 pages |
| Authors:
Eric P. Chassignet; Zulema D. Garraffo; MIAMI UNIV FL INST OF MARINE AND ATMOSPHERIC SCIENCES
|
| Recent advances in computer architecture allow for numerical integration of state-of-the-art ocean models at basin scale with a grid resolution of 1/10 degrees or higher. At that resolution, the Gulf Stream's separation at Cape Hatteras is well stimulated, but substantial differences from observations are still observed in its path, strength, and variability. Several high resolution (1/12 degrees) North Atlantic simulations performed with the Miami Isopycnic Coordinate Ocean Model (MICOM) are ... |
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| Order Reduction of Large Scale Systems via Nonlinear Normal Modes |
2001 |
|
| Authors:
Eric Butcher; Subhash Sinha; ALASKA UNIV FAIRBANKS
|
| By employing the piecewise modal method (PMM) and local equivalent linear stiffness method (LELSM) to estimate NNM frequencies and mode shapes, improved reduced order models were obtained for several types of nonsmooth nonlinearities. The resulting approximate frequencies and mode shapes were compared with the exact NNM frequencies and best-fit lines to the NNM manifolds obtained via least squares regression from the direct numerical integration of the full model. The technique ... |
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| The Surface Crack Problem for a Functionally Graded Coating Bonded to a Homogeneous Layer |
OCT 2000 |
267 pages |
| Authors:
Fazil Erdogan; Matheendra Kasmaklar; LEHIGH UNIV BETHLEHEM PA
|
| In the continuing search for materials which can withstand the grueling requirements of modem day applications, Functionally Graded Materials (FGMs) seem to be a promising alternative to conventional materials. These nonhomogeneous materials offer better interfacial properties by improving bond strength and reducing thermal mismatch. Before putting these materials into application, an important step in the design of FGMs is the stress analysis and fracture characterization. The fracture performance of FGM ... |
|
| An Adaptation of Walker-Anderson Model Elements into the Frank-Zook Penetration Model for Use in MUVES |
SEP 2000 |
58 pages |
| Authors:
Steven B. Segletes; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The performance of the well-respected Frank-Zook (FZ) penetration algorithm is examined in light of an anticipated class of target technology involving laminated targets whose layers are thin relative to the projectile diameter (in the limiting case, this target class incorporates functionally graded materials). Because of the manner in which the FZ algorithm anticipates changes in material properties along the shotline of the penetrator, the algorithm is susceptible to inaccuracy precisely ... |
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| An Innovative Computational Method for Predicting Neutron Transport |
MAR 2000 |
60 pages |
| Authors:
Jay I. Frankel; TENNESSEE UNIV KNOXVILLE COLL OF ENGINEERING
|
| This final report indicates the work performed under DNA-OO1-96-0103 during the span covering June 1996 through June 1998. Several important findings are reported strongly suggesting that the proposed numerical methodology can perform as initially conceived upon resolving the remaining technical issue involving the numerical integration of integral containing Hadamard type kernels. Preliminary calculations are presented in bath cartesian and spherical geometries indicating that the symbolically ... |
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| Coherent Laser-Atom Interactions With Partially Coherent Laser Fields |
30 AUG 1999 |
7 pages |
| Authors:
Daniel S. Elliott; PURDUE UNIV LAFAYETTE IN SCHOOL OF ELECTRICAL ENGINEERING
|
| In this research program, the investigators have explored the role of fluctuations of a laser field on coherent interactions between the laser field and simple atomic systems. A key feature of these experiments is their ability to provide measurements of complex nonlinear optical interactions which are sufficient for direct, quantitative comparison with theory. The main thrust of the present work has been the study of non-Markovian ... |
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| Gaussian Filters for Nonlinear Filtering Problems |
25 MAY 1999 |
32 pages |
| Authors:
Kazufumi Ito; Kaiqi Xiong; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
| In this paper we develop and analyze real-time and accurate filters for nonlinear filtering problems based on the Gaussian distributions. We present the systematic formulation of Gaussian filters and develop efficient and accurate numerical integration of the optimal filter. We also discuss the mixed Gaussian filters in which the conditional probability density is approximated by the sum of Gaussian distributions. A new update rule of weights for Gaussian sum filters ... |
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| High Order Accuracy Computational Methods for Long Time Integration of Nonlinear PDEs in Complex Domains |
30 NOV 1998 |
20 pages |
| Authors:
David Gottlieb; C. W. Shu; P. F. Fischer; W. S. Don; J. Hesthaven; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
|
| The overarching goal of this research was to construct stable, robust and efficient high order accurate computational methods for long time integration of nonlinear partial differential equations. High order accuracy methods (Spectral, Finite Difference and Finite Elements) for the numerical simulations of flows with discontinuities, in complex geometries were developed. In particular applications in supersonic combustion were emphasized. Specific research subjects included: Robust high order ... |
|
| A Compact Analytical Fit to the Exponential Integral E1(x) |
SEP 1998 |
58 pages |
| Authors:
Steven B. Segletes; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A four-parameter fit is developed for the class of integrals known as the exponential integral (real branch). Unlike other fits that are piecewise in nature, the current fit to the exponential integral is valid over the complete domain of the function (compact) and is everywhere accurate to within +/-0.0052% when evaluating the first exponential integral, E1. To achieve this result, a methodology that makes use of analytically ... |
|
| Application of a Nystrom Method to Solving 3-D Electromagnetic Interior Scattering Problems |
JUL 1998 |
19 pages |
| Authors:
Sherwood Samn; AIR FORCE RESEARCH LAB BROOKS AFB TX HUMAN EFFECTIVENESS DIRECTORATE
|
| In studying interior scattering problems of electromagnetic waves in biological systems, it is natural to consider finite inhomogeneous models in 3- space. With the advent of ever-increasing computing power and noval computer architecture for parallel processing, integral equation formulations of the problem have become viable alternatives to more traditional finite difference or finite element approaches. This report describes a generalization of the classical Nystrom Method ... |
|
| Numerical Modeling of Linear and Nonlinear Seismic Wave Attenuation |
APR 1998 |
81 pages |
| Authors:
Steven M. Day; J. B. Minster; Heming Xu; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
|
| CTBT verification requires an understanding of the propagation of seismic phases over complex regional paths which cut across major structural boundaries. The computation of synthetic seismograms by finite difference methods plays an important role in developing such understanding. In order for synthetic seismograms to be realistic, the models must account not only for regional elastic structure of the path, but also for an elastic losses. ... |
|
| Roots of Certain Transcendental Equations for Elastic Angular Regions |
30 JAN 1998 |
18 pages |
| Authors:
M. B. Subrahmanyam; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| Certain important transcendental equations occur in the case of elastic angular regions while analyzing these regions for flexure, vibration, and buckling. Previously these transcendental equations have been solved for roots and the data has been tabulated for different boundary conditions, as the angle of the region is varied. The purpose of this paper is to demonstrate that once we solve for the roots at a specific angular region, the roots ... |
|
| Spectral Deferred Correction Methods for Ordinary Differential Equations |
30 JAN 98 |
29 pages |
| Authors:
Alok Dutt; Leslie Greengard; Vladimir Rokhlin; YALE UNIV NEW HAVEN CT DEPT OF COMPUTER SCIENCE
|
| We introduce a new class of methods for the Cauchy problem for ordinary differential equations (ODEs). We begin by converting the original ODE into the corresponding Picard equation and apply a deferred correction procedure in the integral formulation, driven by either the explicit or the implicit Euler marching scheme. The approach results in algorithms of essentially arbitrary order accuracy for both non-stiff and stiff problems; their performance is illustrated with ... |
|
| Light Scattering from an Optically Active Sphere into a Circular Sensor Aperture |
DEC 1997 |
43 pages |
| Authors:
J. D. Pendleton; David L. Rosen; James B. Gillespie; ARMY RESEARCH LAB ADELPHI MD
|
| Two methods are developed to average Vand I Stokes parameters over a circular sensor aperture collecting light scattered from an optically active sphere. One method uses a two-dimensional numerical integration of Bohren's theory in scalar form, which explicitly shows the connection with Mueller matrix elements. The second method uses expansions of vector spherical harmonics in Bohren's theory to integrate over apertures of any size without convergence checks since numerical integration ... |
|
| Velocity Profiles and Skin Friction on a Ribletted Flat Plate in Adverse Pressure Gradient |
DEC 97 |
179 pages |
| Authors:
Richard D. Branam; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| This project investigated the flow field characteristics over a flat, ribletted plate and the effects of an adverse pressure gradient on this flow field. Testing examined the development of the flow over the ribletted plate from laminar through fully turbulent flow fields. The flow field states (laminar, transitional, and turbulent) were determined using local turbulence intensity values and boundary layer profiles. Several parameters were examined to help better describe the ... |
|
| Collection of Emission from an Oscillating Dipole Inside a Sphere: Analytic Integration Over a Circular Aperture |
DEC 97 |
35 pages |
| Authors:
J. D. Pendleton; Steven C. Hill; ARMY RESEARCH LAB ADELPHI MD
|
| We describe a method for analytically integrating, over a circular aperture, the emission from an oscillating dipole inside a dielectric sphere. The model is useful for investigating fluorescence, Raman, or other emission from molecules inside spherical particles or droplets. The analysis is performed for two cases: (1) the dipole emits from a fixed orientation, and (2) the dipole emits from all orientations. In both cases, all light entering the aperture ... |
|
| Orbit Estimation Using Track Compression and Least Squares Differential Correction |
DEC 97 |
152 pages |
| Authors:
Vincent J. Chioma; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
|
| This thesis develops two methods of compressing a track of radar observations of a satellite into a single state vector and associated covariance matrix, and a method of estimating orbits using results from multiple tracks. The track compression uses least squares differential correction to determine a state vector at the central observation time. The resulting state vectors and covariance matrices are then used to estimate the satellite's orbit, also using ... |
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Reports by Keyword(s)
NUMERICAL INTEGRATION
