| Modeling Operational Robustness and Resiliency with High-Level Petri Nets |
May 2012 |
47 pages |
| Authors:
Madjid Tavana; Timothy E Busch; Eleanor L Davis; AIR FORCE RESEARCH LAB ROME NY INFORMATION DIRECTORATE
|
 | Military operations are highly complex workflow systems that require careful planning and execution. The interactive complexity and tight coupling between people and technological systems has been increased in military operations, which leads to both improved efficiency and a greater vulnerability to mission accomplishment due to attack or system failure. Although the ability to resist and recover from failure is important to many systems and processes, the robustness and resiliency of ... |
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| Development of a Highly Efficient and Accurate Wind-Wave Simulation Framework for Operational Data Assimilation |
30 Sep 2011 |
9 pages |
| Authors:
Lian Shen; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF CIVIL ENGINEERING
|
| This research aims at developing a highly efficient yet accurate computational framework for the simulation and prediction of wave and wind coupled motions with wave phases being resolved, which will lead to an advanced data assimilation tool to provide more comprehensive environmental input for naval applications. Our ultimate goal is to pave the way for developing an operational tool for the Navy to use for ocean-wave-atmosphere battlespace sensing and prediction ... |
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| A Spectral Element Eulerian-Lagrangian Atmospheric Model (SEELAM) |
01-Jan-2008 |
11 pages |
| Authors:
Francis X Giraldo; NAVAL RESEARCH LAB MONTEREY CA
|
| A new dynamical core for numerical weather prediction (NWP) based on the spectral element Eulerian-Lagrangian (SEEL) method is presented. This paper represents a departure from previously published work on solving the atmospheric equations in that the horizontal operators are all written, discretized, and solved in 3D Cartesian space. The advantages of this new methodology are: the pole singularity which plagues all gridpoint methods disappears, the horizontal operators can be approximated ... |
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| 3D Spatial Modeling Plan for Biospice |
JAN 2008 |
10 pages |
| Authors:
David Adalsteinsson; Phil Colella; NORTH CAROLINA UNIV AT CHAPEL HILL
|
| This effort developed the spatial modeling component of the Defense Advanced Research Projects Agency (DARPA) BioSpice project. The principal accomplishments include the development of a new class of methods for simulating reaction-diffusion processes in cells, and of an end-to-end methodology for obtaining discretization data from image data via level sets. These methods were tested on several model problems in systems biology. |
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| A High Order ENO Conservative Lagrangian Scheme for the Compressible Euler Equations |
2007 |
50 pages |
| Authors:
Juan Cheng; Chi-Wang Shu; ARMY RESEARCH OFFICE RESEARCH TRIANGLE PARK NC
|
| We develop a class of Lagrangian schemes for solving the Euler equations of compressible gas dynamics both in the Cartesian and in the cylindrical coordinates. The schemes are based on high order essentially non-oscillatory "ENO" reconstruction. They are conservative for the density, momentum and total energy, can maintain formal high order accuracy both in space and time and can achieve at least uniformly second order accuracy with moving and distorted ... |
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| Determining In-Flight Tracker Accuracy |
MAR 2006 |
8 pages |
| Authors:
Corbin G. Koepke; Vincent Parisi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE
|
| Evaluating a system in flight poses challenges that are not found in a laboratory environment. This paper discusses some of the issues involved in conducting an in-flight test to evaluate tracker accuracy, such as head movement, synchronization of time, changing coordinate systems, and interpolating data. The paper describes six types of accuracy: laboratory static, laboratory dynamic, installed static, installed dynamic, operational static, and operational dynamic. In general, as the realism ... |
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| Anholonomic Configuration Spaces and Metric Tensors in Finite Elastoplasticity |
FEB 2006 |
18 pages |
| Authors:
John D. Clayton; David L. McDowell; Douglas J. Bammann; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Deformation mappings are considered that correspond to the motions of lattice defects, elastic stretch and rotation of the lattice, and initial defect distributions. Intermediate (i.e., relaxed) configuration spaces associated with these deformation maps are identified and then classified from the differential-geometric point of view. A fundamental issue is the proper selection of coordinate systems and metric tensors in these configurations when such configurations are classified as anholonomic. The particular choice ... |
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| Use of Orthogonal Curvilinear Grids for the Representation of the Littoral Ocean Environment |
2006 |
9 pages |
| Authors:
Alan F. Blumberg; B. N. Kim; Sean O'Neil; James K. Lewis; Subramaniam D. Rajan; S. K. Numrich; William Smith; Richard L. Schaffer; Tom Curtin; Paul Maasel; HYDROQUAL INC MAHWAH NJ
|
| The effective representation of the littoral ocean environment has been a long-standing challenge for the Modeling and Simulation (M&S) community. The need for such a representation continues to grow, as the U.S. Navy refocuses from deep ocean to littoral missions. One of the greatest challenges of the littoral region is the wide range of spatial and temporal scales that must be represented. For example, the cross-shore gradients of important oceanographic ... |
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| Improving the Performance of Perfectly Matched Layers by Means of hp-Adaptivity |
2006 |
26 pages |
| Authors:
C. Michler; L. Demkowicz; J. Kurtz; D. Pardo; TEXAS UNIV AT AUSTIN DEPT OF MTHEMATICS AND INST OF COMPUTATIONAL ENGINEERING AND SCIENCES
|
| We improve the performance of the Perfectly Matched Layer by using an automatic hp-adaptive discretization. By means of hp-adaptivity, we obtain a sequence of discrete solutions that converges exponentially to the continuum solution. Asymptotically, we thus recover the property of the PML of having a zero reflection coefficient for all angles of incidence and all frequencies on the continuum level. This allows us to minimize the reflections from the discrete ... |
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| NRL Plasma Formulary |
2006 |
71 pages |
| Authors:
J. D. Huba; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
|
| The NRL Plasma Formulary originated over twenty five years ago and has been revised several times during this period. |
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| A Coupled Local Mode Investigation of Elastic Anisotropy in Shallow Water Environments: A Study of Antisotropy Beyond VTI |
28 NOV 2005 |
141 pages |
| Authors:
Darin J. Soukup; Robert I. Odom; Jeffrey Park; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
|
| This paper presents theoretical and numerical results for the coupled mode, shallow water seismo-acoustic wavefield in generally anisotropic, range-dependent media. General anisotropy affects the form of the elastic stiffness tensor, which directly affects the polarization of the local modes, the frequency and angular dispersion curves, and the coupling of the local modes in range-dependent media. The effects of anisotropy (1-D models) and the combination of anisotropy and lateral heterogeneity (2-D ... |
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| Non-Adiabatic Energy Surfaces of the B+H2 Systems |
MAR 2005 |
78 pages |
| Authors:
Lachlan T. Belcher; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| In order to solve the dynamics of a system, the kinetic energy operator of the Hamiltonian must be diagonalized. Diagonalization requires rotation of the system into a non-adiabatic representation. This rotation is a coupling angle determined by the derivative coupling terms. Derivative coupling terms are calculated using Columbus and Brooklyn, software packages. Separation of internal dynamics characterized by Jacobi coordinates, and external dynamics characterized by a set of Euler angles ... |
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| A Nodal Triangle-based Spectral Element Method for the Shallow Water Equations on the Sphere |
Jan-2005 |
27 pages |
| Authors:
F X Giraldo; T Warburton; NAVAL RESEARCH LAB MONTEREY CA
|
| A nodal triangle-based spectral element method for the shallow water equations on the sphere is presented. The original SE method uses quadrilateral elements and high-order nodal Lagrange polynomials, constructed from a tensor-product of the Legendre-Gauss-Lobatto points. In this work we construct the high-order Lagrange polynomials directly on the triangle using nodal sets obtained from the electrostatics principle and Fekete points. These points have good approximation properties and far better Lebesgue ... |
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| Distance Functions and Geodesics on Points Clouds |
2005 |
11 pages |
| Authors:
Facundo Memoli; Guillermo Sapiro; MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| An algorithm for computing intrinsic distance functions and geodesics on sub-manifolds vector r(sup d) given by point clouds is introduced in this paper. The basic idea is that, as shown in this paper intrinsic distance functions and geodesics on general co-dimension sub-manifolds vector r(sup d) can be accurately approximated by the extrinsic Euclidean ones computed in a thin offset band surrounding the manifold. This permits the use of computationally optimal ... |
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| High-Order Accuracy Methods for the Modeling and Design of Microoptics and Photonic Devices |
30 NOV 2004 |
7 pages |
| Authors:
Jan S. Hesthaven; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
|
| The goals of this effort have been the development of high-order accurate computational methods for wave problems in general and Maxwell's equations of electromagnetics in particular. The applications are general, but particular emphasis has been on optical applications. The authors have made substantial progress in the development and application of three different methods: time-domain, high-order finite difference embedding methods; boundary variation methods for multilayered optics; and discontinuous Galerkin methods for ... |
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| Enhanced System for Detection of Randomness in Sparse Time Series Distributions |
10 NOV 2004 |
42 pages |
| Authors:
Francis J. O'Brien; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A two-step method and apparatus are provided for automatically characterizing the spatial arrangement among the data points of a time series distribution in a data processing system wherein the classification of said time series distribution is required. In a first stage, the method and apparatus utilize a grid in Cartesian coordinates to determine (1) the number of cells in the grid containing at least one input data point of the ... |
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| Parallel Matlab Computation for STAP Clutter Scattering Function Estimation and Moving Target Estimation |
30 SEP 2004 |
28 pages |
| Authors:
Roger Chamberlain; Daniel R. Fuhrmann; John Maschmeyer; Lisandro Boggio; WASHINGTON UNIV ST LOUIS MO
|
| Conventional moving target estimation in STAP radar applications is based, in part, on adaptive clutter scattering function estimation techniques. These techniques classically rely on radar return data from adjacent range gates to estimate the clutter scattering function for the range gate of interest. Here, we are interested in using geographical information systems in conjunction with accurate platform positioning information as the basis for the clutter scattering function estimation. The goal ... |
|
| An Immersed FEM for Elasticity Equations With Interfaces |
12 AUG 2004 |
17 pages |
| Authors:
Zhilin Li; Xingzhou Yang; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
| The immersed finite element method based on a uniform Cartesian mesh has been developed for elasticity equations with discontinuous physical parameters across an interface in this paper. The interface does not have to be aligned with the mesh. The main idea is to modify the basis function over those triangles in which the interface cuts through so that the natural interface conditions are satisfied. The standard linear basis functions are ... |
|
| 3-Dimensional Retarding Walls and Flow in Their Vicinity |
22 JUN 2004 |
20 pages |
| Authors:
K. A. Toker; M. H. Aksel; H. T. Tinaztepe; MIDDLE EAST TECHNICAL UNIV ANKARA (TURKEY) DEPT OF MECHANICAL ENGINEERING
|
| In this project, the regression of combusting surface of solid propellant in rocket motors is investigated by using a fully 3-dimensional method which is called the "Fast Marching Method (FMM)." The FMM is capable of following the surface regression under local rate variations by itself. However, the aim is to use a varying burn rate under the effects of pressure and velocity. Different flow solvers are coupled with the FMM. ... |
|
| Handbook for Transformation of Datums, Projections, Grids, and Common Coordinate Systems |
MAY 2004 |
150 pages |
| Authors:
James Ackeret; Fred Esch; Chris Gard; Frederick Gloeckler; Daniel Oimen; Juan Perez; Justin Simpson; Daniel Specht; Harry Rossander; David Stoner; ENGINEER RESEARCH AND DEVELOPMENT CENTER ALEXANDRIA VA TOPOGRAPHIC ENGINEERING CENTER
|
| This document provides U.S. Army organizations and agencies with general guidance on selecting the appropriate methods for shifting between local geodetic datums and the World Geodetic System (WGS), and for converting Cartesian and map projection coordinates to and from geodetic coordinates. This guidance is provided to aid the Army community in selecting datum shift algorithms; developing, selecting, and maintaining software using these algorithms; and implementing this software to support operational ... |
|
| A Fourth Order Accurate Discretization for the Laplace and Heat Equations on Arbitrary Domains, with Applications to the Stefan Problem |
27 APR 2004 |
41 pages |
| Authors:
Frederic Gibou; Ronald Fedkiw; STANFORD UNIV CA DEPT OF COMPUTER SCIENCE
|
| In this paper, the authors first describe a fourth order accurate finite difference discretization for both the Laplace equation and the heat equation with Dirichlet boundary conditions on irregular domains. In the case of the heat equation, they use an implicit time discretization to avoid the stringent time step restrictions associated with explicit schemes. They then turn their focus to the Stefan problem and construct a third order accurate method ... |
|
| Toward Immersed Boundary Simulation of High Reynolds Number Flows |
24 MAR 2004 |
10 pages |
| Authors:
Georgi Kalitzin; Gianluca Iaccarino; STANFORD UNIV CA
|
| In the immersed boundary (IB) method, the surface of an object is reconstructed with forcing terms in the underlying flow field equations. The surface may split a computational cell removing the constraint of the near wall gridlines to be aligned with the surface. This feature greatly simplifies the grid generation process which is cumbersome and expensive in particular for structured grids and complex geometries. |
|
| A Cartesian Adaptive Level Set Method for Two-Phase Flows |
24 MAR 2004 |
11 pages |
| Authors:
F. Ham; Y. N. Young; STANFORD UNIV CA
|
| Simulations of flows involving free surfaces have become ubiquitous in the literature. The evolution of both simulation methods and computer speed have allowed the investigation of many problems of increasing complexity and engineering relevance. For 2D simulations, it is reasonably common to use grid resolutions of 512 x 512 or larger. See for example the 2D planar breaking wave simulations of Chen et al. (1999), or the axisymmetric drop breakup ... |
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| Simulation of Moving Boundary Flow Using Overset Adaptive Cartesian/ Prism Grids and DES |
SEP 2003 |
22 pages |
| Authors:
Z. J. Wang; Laiping Zhang; MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING
|
| Development of improved weapon systems requires better understanding of the complex aerodynamics created by moving boundaries. Carriage and release of conventional weapons from aircraft and aerial refueling fall in this category. The flow problem involving moving boundaries are very challenging to compute because the resultant flow field is intrinsically unsteady. Modeling such flow problems is made even more difficult due to the complex geometries and the highly turbulent nature of ... |
|
| A Particle-Level-Set Based Sharp Interface Cartesian Grid Method for Impact, Penetration, and Void Collapse |
APR 2003 |
70 pages |
| Authors:
Linhbao Tran; H. S. Udaykumar; IOWA UNIV IOWA CITY DEPT OF MECHANICALAND INDUSTRIAL ENGINEERING
|
| An Eulerian, sharp interface, Cartesian grid method is developed for the numerical simulation of the response of materials to impact, shocks and detonations. The mass, momentum, and energy equations are solved along with evolution equations for deviatoric stresses and equivalent plastic strain. These equations are cast in Eulerian conservation law form. The Mie-Gruneisen equation of state is used to obtain pressure and the material is modeled as a Johnson- Cook ... |
|
| Les Investigation of Coherent Structures in Boundary Layers and Wakes. Volume I: Investigation of Coherent Structure in an Attached Shear Layer |
DEC 2002 |
|
| Authors:
R. Giammanco; C. Benocci; VON KARMAN INST FOR FLUID DYNAMICS RHODE-SAINT-GENESE (BELGIUM)
|
 | Purpose of the present investigation was to assess the feasibility of simulating and studying coherent structures in turbulent shear layers, making use of Large Eddy Simulations (LES). The current investigation has been performed across a rather wide range of simulated flows and LES implementations, starting from an established and validated structured LES code based on finite differences and cartesian grids ending to an unstructured LES code under development. The use ... |
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| MODFLOW-2000 for Cylindrical Geometry With Internal Flow Observations and Improved Water Table Simulation |
AUG 2002 |
34 pages |
| Authors:
Tom Clemo; BOISE STATE UNIV ID CENTER FOR THE GEOPHYSICAL INVESTIGATION OF THE SHALLOW SUBSURFACE
|
| A modified form of the MODFLOW-2000 code provides a tool to estimate a hydraulic conductivity distribution near a borehole. The modified code allows the effects of wellbore screen intervals, screen clogging, and disturbed zone skin to be taken into account. The primary application has been in an investigation of electromagnetic borehole flow meter measurement interpretation. MODFLOW-2000 was modified to simulate a two-dimensional cylindrical geometry. The two dimensions are vertical and ... |
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| Computation of Separating High Reynolds Number Incompressible Flows Using Uniform Cartesian Grids |
18 JUL 2002 |
82 pages |
| Authors:
John Steinhoff; TENNESSEE UNIV SPACE INST TULLAHOMA
|
| Most of the research done during the contract period is reported in the "Interim Report" of March, 2002. This is included in section II. Other results, including a breakthrough that has lead to a new, simpler, fully conservative Vorticity Confinement formulation will be discussed in section III. Results of the original formulation for blunt body flow, including comparisons with experiment, are described in section IV. A new, more effective way ... |
|
| A User's Guide to LAMPAT and ANSYS |
MAR 2002 |
58 pages |
| Authors:
Robert P. Kaste; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| LAMPAT and ANSYS are analysis tools that can be used together to evaluate the mechanical integrity of structures of laminar construction. The two codes originate from two different areas of analysis. Their default coordinate systems have different orientations. To properly examine a structure, the directional properties used by LAMPAT must be transformed into the proper input coordinate directional properties for ANSYS. This has been done for some time already, but ... |
|
| Improvement and Restoration of Biomedical Images Blurred by Body Movement |
25 OCT 2001 |
|
| Authors:
J. Hori; Y. Saitoh; T. Kiryu; K. Okamoto; K. Sakai; NIIGATA UNIV (JAPAN) FACULTY OF ENGINEERING
|
| The restoration of biomedical images that have been blurred due to body movement are discussed. The observation system for these images is described using a mathematical operator and coordinate transformations. And a band-suppressed restoration filter composed of a series of such operators is proposed for improving the quality of images. In addition, redundancy is introduced into these restoration filters in order to suppress additive noise, The proposed method is applied ... |
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| Comparison of Batch and Kalman Filtering for Radar Tracking |
23 JUL 2001 |
|
| Authors:
Haywood Satz; Thomas H. Kerr; RAYTHEON CO BEDFORD MA
|
| Radar tracking performance was compared among two choices of statistical filtering algorithms for the noisy measurements of exo-atmospheric objects in ballistic motion. Such motion is characteristic of satellites and missiles. Object position and velocity were governed by the nonlinear dynamics of body motion in a central force field, and measurements were modeled as nonlinear observations of those object motions in Cartesian coordinates. The two choices of statistical filtering algorithms were ... |
|
| Shape-Measure Method for Introducing the Nearly Optimal Domain |
JUL 2001 |
8 pages |
| Authors:
A. Fakharzadeh; J. E. Rubio; LEEDS UNIV (UNITED KINGDOM) DEPT OF APPLIED MATHEMATICAL STUDIES
|
| We deal with introducing a new algorithm for solving the optimal shape problems in which they are defined with respect to a pair of geometrical elements. The problem is to find the optimal domain approximately for a given functional that is involved with the solution of a linear or nonlinear elliptic equation with a boundary condition over a domain. The Shape-Measure method, in Cartesian coordinates will be used to find ... |
|
| A Spectral Element Shallow Water Model on Spherical Geodesic Grids |
01-Jan-2001 |
34 pages |
| Authors:
Francis X Giraldo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OPERATIONS RESEARCH
|
| The spectral element method for the two-dimensional shallow water equations on the sphere is presented. The equations are written in conservation form and the domains are discretized using quadrilateral elements obtained from the generalized icosahedral grid introduced previously (Giraldo FX. Lagrange-Galerkin methods on spherical geodesic grids: the shallow water equations. Journal of Computational Physics 2000; 160: 336 368). The equations are written in Cartesian co-ordinates that introduce an additional momentum ... |
|
| Nodal High-Order Discontinuos Galerkin Methods for the Spherical Shallow Water Equations |
2001 |
26 pages |
| Authors:
F. X. Giraldo; J. S. Hesthaven; T. Warburton; NAVAL RESEARCH LAB MONTEREY CA PREDICTION SYSTEMS BRANCH
|
| We develop and evaluate a high-order discontinuous Galerkin method for the solution of the shallow water equations on the sphere. To overcome well known problems with polar singularities, we consider the shallow water equations in Cartesian coordinates, augmented with a Lagrange multiplier to ensure that fluid particles are constrained to the spherical surface. The global solutions are represented by a collection of curvilinear quadrilaterals from an icosahedral grid. On each ... |
|
| Three Dimensional Formation Flight Control |
MAR 2000 |
94 pages |
| Authors:
James K. Hall; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| Automating the control of an aircraft flying in formation necessitates the extension of the theory of formation flight control to allow for three dimensional maneuvers. The formation was modeled as a two-aircraft, leader and wingspan, formation. Both aircraft has its own three dimensional, rotating and translating, Cartesian axes system, with special attention being given to the motion of the leader in relation to the wingspan. ... |
|
| Investigation of Interface Resolution Techniques in Moving Boundary Problems |
JAN 2000 |
46 pages |
| Authors:
W. Shyy; H. S. Udaykumar; D. Belk; K. Vanden; FLORIDA UNIV GAINESVILLE DEPT OF AEROSPACE ENGINEERING MECHANICS AND ENGINEERING SCIENCE
|
| In this report we describe the development of a numerical solution technique for the simulation of high-speed multi-material impact. Of particular interest is the interaction of solid impactors with targets. Such interactions present the following challenges to numerical solution techniques: (1) high velocities of impact leading to large deformations of the impactor as well as the targets. (2) nonlinear wave-propagation and the development of shocks ... |
|
| Bounded Derivative Initialization |
22 OCT 1999 |
2 pages |
| Authors:
Gerald L. Browning; Chungu Lu; COOPERATIVE INST FOR RESEARCH IN THE ATMOSPHERE FORT COLLINS CO
|
| A well-posed, multiscale, fourth-order accurate, limited area model in Cartesian coordinates. with a Kuo cumulus parameterization scheme was developed. The corresponding Bounded Derivative Initialization (BDI) package produced balanced initial fields from Offut AFB AVN vorticity data. The ensuing solution was essentially free of gravity waves. |
|
| Equilibrium Shape of Headland-Bay Beaches for Engineering Design |
01-Jun-1999 |
17 pages |
| Authors:
Nicholas C Kraus; Luis J Moreno; COASTAL DEFENSE PROGRAM MADRID (SPAIN)
|
| The equilibrium shoreline form of crenulate or headland-bay beaches was identified in the 1940s and is widely accepted by coastal geomorphologists and engineers. However, little quantitative verification of the standard functional shoreline forms, the logarithmic-spiral shape and parabolic shape, has been made. In addition, limited guidance is available for applying the functional shapes in engineering practice. In this paper, we investigate the two shapes by fitting to 46 beaches in ... |
|
| Two Kinds of Predictability in the Lorenz System |
15 MAY 1999 |
7 pages |
| Authors:
Peter C. Chu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The Lorenz system is used to discuss two kinds of predictability: the model sensitivity to inaccurate initial conditions (first kind) and to inaccurate boundary conditions (second kind). The first kind of predictability has been investigated for a long time, but not the second kind. It was found that the Lorenz system has a capability to detect both kinds of predictability since the boundary condition is represented by a model parameter, ... |
|
| Bounded Error Schemes for the Wave Equation on Complex Domains |
NOV 1998 |
13 pages |
| Authors:
Saul Abarbanel; Adi Ditkowski; Amir Yefet; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| This paper considers the application of the method of boundary penalty terms (SAT) to the numerical solution of the wave equation on complex shapes with Dirichlet boundary conditions. A theory is developed, in a semi- discrete setting, that allows the use of a Cartesian grid on complex geometries, yet maintains the order of accuracy with only a linear temporal error bound. A numerical example, involving the solution of Maxwell's equations ... |
|
| An Automated Viscous Unstructured Adaptive Cartesian Grid Generation Method for Complex Geometries |
AUG 1998 |
15 pages |
| Authors:
Z. J. Wang; CFD RESEARCH CORP HUNTSVILLE AL
|
| This Phase I Option final report contains two major work items carried out during the Option period: redefinition of the Phase II Statement of Work and the preliminary design for the Grid Generator and Grid Adaptor to be produced in Phase II. |
|
| Investigation of Acoustic Wavefield Dynamics in Quasi-Realistic Ocean Environments |
Jan 1998 |
4 pages |
| Authors:
Michael A Wolfson; WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
|
| Our long-term goal is to provide a more complete understanding of the forward propagation of acoustic pulses in range-dependent deep ocean environments at multi-megameter range scales. The objective of this project is to understand the limits of wavefield predictability in ocean environments where refractive scattering is the dominant physical process controlling the dynamics of the wavefield. The canonical scenario is long-range acoustic transmissions along the ocean waveguide, which has sound ... |
|
| Reduced Computational Cost, Totally Symmetric Angular Quadrature Sets for Discrete Ordinates Radiation Transport |
DEC 1997 |
148 pages |
| Authors:
Joseph M. Oder; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
|
| Several new quadrature sets for use in the discrete ordinates method of solving the Boltzmann neutral particle transport equation are derived. These symmetric quadratures extend the traditional symmetric quadratures by allowing ordinates perpendicular to one or two of the coordinate axes. Comparable accuracy with fewer required ordinates is obtained. Quadratures up to seventh order are presented. The validity and efficiency of the quadratures is then tested and compared with the ... |
|
| Adaptive Methods for Euler Flows in Complex Geometries |
MAY 97 |
7 pages |
| Authors:
Marsha Berger; NEW YORK UNIV NY
|
| We have developed algorithms for high resolution computations in complicated geometrics that are as automatic as possible. This includes the development of Cartesian grid methods, for easily representing complex geometry using non-body fitted grids, and the development of adaptive techniques, designed specifically for Cartesian grids, for increasing the resolution of a computation where necessary. Some 30 examples are include to illustrate the performance of the method. |
|
| Development of a User Friendly Wave Simulator for Military Applications |
07 OCT 96 |
30 pages |
| Authors:
Amarendra Sinha; Dilruba Sultana; CMS CONSULTING WORTHINGTON OH
|
| The objective of the Phase I SBIR project was to demonstrate the feasibility of using Boussinesq type models to simulate time dependent three dimensional near shore ocean waves intended to be used as a military planning tool. The main issues are the accuracy and the domain of applicability of the model, and the adequacy of current computers to simulate these models for a sufficiently large domain. We used Nwogu's form ... |
|
| The Dependence of Magnitude Uncertainty on Station Coverage |
31 AUG 96 |
43 pages |
| Authors:
Steven Bottone; Mark D. Fisk; Henry L. Gray; Gary D. McCartor; MISSION RESEARCH CORP SANTA BARBARA CA
|
| A useful event characterization parameter for relatively large (e.g., mb > 4) teleseismic events is mb-Ms, provided the events are not too deep. To use mb-Ms as a parameter with which to screen events of natural seismicity, at a given confidence level, the uncertainty (standard deviation) in mb-Ms must be quantified. This report presents a generalization to the current method of screening events using mb-Ms by including correlation between station ... |
|
| High Dimensional Clustering Using Parallel Coordinates and the Grand Tour |
APR 96 |
24 pages |
| Authors:
Edward J. Wegman; Qiang Luo; GEORGE MASON UNIV FAIRFAX VA CENTER FOR COMPUTATIONAL STATISTICS
|
| In this paper, we present some graphical techniques for cluster analysis of high-dimensional data. Parallel coordinate plots and parallel coordinate density plots are graphical techniques which map multivariate data into a two-dimensional display. The method has some elegant duality properties with ordinary Cartesian plots so that higher-dimensional mathematical structures can be analyzed. Our high interaction software allows for rapid editing of data to remove outliers and isolate clusters by brushing. ... |
|
| Handbook for Transformation of Datums, Projections, Grids and Common Coordinate Systems |
JAN 96 |
166 pages |
| Authors:
Frederick Gloeckler; Richard Joy; Justin Simpson; Daniel Specht; James Ackeret; ARMY TOPOGRAPHIC ENGINEERING CENTER ALEXANDRIA VA
|
| This document provides Army organizations and agencies with general guidance on selecting the appropriate methods for shifting between local geodetic datums and the World Geodetic System (WGS), and for converting Cartesian and map projection coordinates to and from geodetic coordinates. This guidance is provided to aid the Army community in selecting datum shift algorithms, in developing, selecting, and maintaining software using these algorithms, and in implementing this software to support ... |
|
| Handbook for Transformation of Datums, Projections, Grids and Common Coordinate Systems |
JAN 96 |
165 pages |
| Authors:
Frederick Gloeckler; Richard Joy; Justin Simpson; Daniel Specht; ARMY TOPOGRAPHIC ENGINEERING CENTER ALEXANDRIA VA
|
| This document provides Army organizations and agencies with general guidance on selecting the appropriate methods for shifting between local geodetic datums and the World Geodetic System (WGS), and for converting Cartesian and map projection coordinates to and from geodetic coordinates. This guidance is provided to aid the Army community in selecting datum shift algorithms, in developing, selecting, and maintaining software using these algorithms, and in implementing this software to support ... |
|
| Cartography and Typography with True Basic |
SEP 95 |
87 pages |
| Authors:
Allen V. Hershey; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A home computer can compute if it has BASIC. A showcase of data and programs has been prepared for True BASIC on a Macintosh computer. Cartographic data have been compressed to one fourth of their volume in a previous format, and typographic data have been compressed to one half of their previous volume. The use of the showcase is illustrated by samples of input to computer and output from a ... |
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CARTESIAN COORDINATES
