Sample records for cartesian coordinate grid

  1. Hybrid C-H grids for turbomachinery cascades. [parabolic and Cartesian coordinates

    NASA Technical Reports Server (NTRS)

    Ghia, U.; Ghia, K. N.; Ramamurti, R.

    1983-01-01

    The three basic types of grids available for two-dimensional cascade configurations are examined with respect to their relative advantages and disadvantages. Subsequently, a hybrid coordinate system is proposed such that it combines the major advantages of the C-type and the H-type meshes. The development of the hybrid grid system employs the patching of appropriate regions of these two basic mesh systems such that the transformed domain has a multi-block structure. Viewing the transformed domain as a three-dimensional surface enables the coordinates to be continuous across the boundaries of the patches in a natural manner.

  2. A fast nested multi-grid viscous flow solver for adaptive Cartesian\\/Quad grids

    Microsoft Academic Search

    Z. J. Wang

    2000-01-01

    SUMMARY A nested multi-grid solution algorithm has been developed for an adaptive Cartesian:Quad grid viscous flow solver. Body-fitted adaptive Quad (quadrilateral) grids are generated around solid bodies through 'surface extrusion'. The Quad grids are then overlapped with an adaptive Cartesian grid. Quadtree data structures are employed to record both the Quad and Cartesian grids. The Cartesian grid is generated through

  3. A sharp interface Cartesian grid hydrocode

    NASA Astrophysics Data System (ADS)

    Sambasivan, Shiv Kumar

    Dynamic response of materials to high-speed and high-intensity loading conditions is important in several applications including high-speed flows with droplets, bubbles and particles, and hyper-velocity impact and penetration processes. In such high-pressure physics problems, simulations encounter challenges associated with the treatment of material interfaces, particularly when strong nonlinear waves like shock and detonation waves impinge upon them. To simulate such complicated interfacial dynamics problems, a fixed Cartesian grid approach in conjunction with levelset interface tracking is attractive. In this regard, a sharp interface Cartesian grid-based, Ghost Fluid Method (GFM) is developed for resolving embedded fluid, elasto-plastic solid and rigid (solid) objects in hyper-velocity impact and high-intensity shock loaded environment. The embedded boundaries are tracked and represented by virtue of the level set interface tracking technique. The evolving multimaterial interface and the flow are coupled by meticulously enforcing the boundary conditions and jump relations at the interface. In addition, a tree-based Local Mesh Refinement scheme is employed to efficiently resolve the desired physics. The framework developed is generic and is applicable to interfaces separating a wide range of materials and for a broad spectrum of speeds of interaction (O(km/s)). The wide repertoire of problems solved in this work demonstrates the flexibility, stability and robustness of the method in accurately capturing the dynamics of the embedded interface. Shocks interacting with large ensembles of particles are also computed.

  4. A FV-TD electromagnetic solver using adaptive Cartesian grids

    Microsoft Academic Search

    Z. J. Wang; A. J. Przekwas; Yen Liu

    2002-01-01

    A second-order finite-volume (FV) method has been developed to solve the time-domain (TD) Maxwell equations, which govern the dynamics of electromagnetic waves. The computational electromagnetic (CEM) solver is capable of handling arbitrary grids, including structured, unstructured, and adaptive Cartesian grids, which are topologically arbitrary. It is argued in this paper that the adaptive Cartesian grid is better than a tetrahedral

  5. Investigation of grid embedment techniques as applied to subcritical flow 

    E-print Network

    Watts, Michael E.

    1980-01-01

    CHAPTER III: COORDINATE SYSTEMS. Stretched Cartesian Grid. . . Embedded Cartesian Grid. . . . Embedded Body Fitted Grid. . CHAPTER IV: PROBLEM FORMULATION. Cartesian Coordinate System. . . . Body Fitted Coordinate System. . 12 12 13 CHAPTER V...: BOUNDARY CONDITIONS Cartesian Grids Embedded Body Fitted Grid. . 14 14 15 CHAPTER VI: FINITE DIFFERENCE SCHEMES. . . Stretched Cartesian System. . Embedded Cartesian Grid. . . . . Embedded Body Fitted Grid. . . CHAPTER VII: DISCUSSION OF RESULTS...

  6. Unstructured Cartesian/prismatic grid generation for complex geometries

    NASA Technical Reports Server (NTRS)

    Karman, Steve L., Jr.

    1995-01-01

    The generation of a hybrid grid system for discretizing complex three dimensional (3D) geometries is described. The primary grid system is an unstructured Cartesian grid automatically generated using recursive cell subdivision. This grid system is sufficient for computing Euler solutions about extremely complex 3D geometries. A secondary grid system, using triangular-prismatic elements, may be added for resolving the boundary layer region of viscous flows near surfaces of solid bodies. This paper describes the grid generation processes used to generate each grid type. Several example grids are shown, demonstrating the ability of the method to discretize complex geometries, with very little pre-processing required by the user.

  7. On differential transformations between Cartesian and curvilinear (geodetic) coordinates

    NASA Technical Reports Server (NTRS)

    Soler, T.

    1976-01-01

    Differential transformations are developed between Cartesian and curvilinear orthogonal coordinates. Only matrix algebra is used for the presentation of the basic concepts. After defining the reference systems used the rotation (R), metric (H), and Jacobian (J) matrices of the transformations between cartesian and curvilinear coordinate systems are introduced. A value of R as a function of H and J is presented. Likewise an analytical expression for J(-1) as a function of H(-2) and R is obtained. Emphasis is placed on showing that differential equations are equivalent to conventional similarity transformations. Scaling methods are discussed along with ellipsoidal coordinates. Differential transformations between elipsoidal and geodetic coordinates are established.

  8. A Cartesian grid approach with hierarchical refinement for compressible flows

    NASA Technical Reports Server (NTRS)

    Quirk, James J.

    1994-01-01

    Many numerical studies of flows that involve complex geometries are limited by the difficulties in generating suitable grids. We present a Cartesian boundary scheme for two-dimensional, compressible flows that is unfettered by the need to generate a computational grid and so it may be used, routinely, even for the most awkward of geometries. In essence, an arbitrary-shaped body is allowed to blank out some region of a background Cartesian mesh and the resultant cut-cells are singled out for special treatment. This is done within a finite-volume framework and so, in principle, any explicit flux-based integration scheme can take advantage of this method for enforcing solid boundary conditions. For best effect, the present Cartesian boundary scheme has been combined with a sophisticated, local mesh refinement scheme, and a number of examples are shown in order to demonstrate the efficacy of the combined algorithm for simulations of shock interaction phenomena.

  9. Anisotropic Cartesian grid method for steady inviscid shocked flow computation

    Microsoft Academic Search

    Zi-Niu Wu; Ke Li

    2003-01-01

    The anisotropic Cartesian grid method, initially developed by Z.N. Wu (ICNMFD 15, 1996; CFD Review 1998, pp. 93-113) several years ago for efficiently capturing the anisotropic nature of a viscous boundary layer, is applied here to steady shocked flow computation. A finite-difference method is proposed for treating the slip wall conditions.

  10. Anisotropic Cartesian grid method for steady inviscid shocked flow computation

    NASA Astrophysics Data System (ADS)

    Wu, Zi-Niu; Li, Ke

    2003-04-01

    The anisotropic Cartesian grid method, initially developed by Z.N. Wu (ICNMFD 15, 1996; CFD Review 1998, pp. 93-113) several years ago for efficiently capturing the anisotropic nature of a viscous boundary layer, is applied here to steady shocked flow computation. A finite-difference method is proposed for treating the slip wall conditions.

  11. A Cartesian grid embedded boundary method for hyperbolic conservation laws

    E-print Network

    A Cartesian grid embedded boundary method for hyperbolic conservation laws Phillip Colella a,*,1-order Godunov algorithm to solve time-dependent hyperbolic systems of conservation laws on irregular domains. Our approach is based on a formally consistent discretization of the conservation laws on a finite

  12. Cartesian Grid Methods for Fluid Flow in Complex Geometries

    Microsoft Academic Search

    Randall J. Leveque; Donna Calhoun

    2001-01-01

    \\u000a Biological fluid dynamics typically involves geometrically complicated structures which are often deforming in time. We give\\u000a a brief overview of some approaches based on using fixed Cartesian grids instead of attempting to use a grid which conforms\\u000a to the boundary. Both finite-difference and finite-volume methods are discussed, as well as a combined approach which has\\u000a recently been used for computing

  13. Transforming geocentric cartesian coordinates to geodetic coordinates by using differential search algorithm

    NASA Astrophysics Data System (ADS)

    Civicioglu, Pinar

    2012-09-01

    In order to solve numerous practical navigational, geodetic and astro-geodetic problems, it is necessary to transform geocentric cartesian coordinates into geodetic coordinates or vice versa. It is very easy to solve the problem of transforming geodetic coordinates into geocentric cartesian coordinates. On the other hand, it is rather difficult to solve the problem of transforming geocentric cartesian coordinates into geodetic coordinates as it is very hard to define a mathematical relationship between the geodetic latitude (?) and the geocentric cartesian coordinates (X, Y, Z). In this paper, a new algorithm, the Differential Search Algorithm (DS), is presented to solve the problem of transforming the geocentric cartesian coordinates into geodetic coordinates and its performance is compared with the performances of the classical methods (i.e., Borkowski, 1989; Bowring, 1976; Fukushima, 2006; Heikkinen, 1982; Jones, 2002; Zhang, 2005; Borkowski, 1987; Shu, 2010 and Lin, 1995) and Computational-Intelligence algorithms (i.e., ABC, JDE, JADE, SADE, EPSDE, GSA, PSO2011, and CMA-ES). The statistical tests realized for the comparison of performances indicate that the problem-solving success of DS algorithm in transforming the geocentric cartesian coordinates into geodetic coordinates is higher than those of all classical methods and Computational-Intelligence algorithms used in this paper.

  14. A multilevel Cartesian non-uniform grid time domain algorithm

    Microsoft Academic Search

    Jun Meng; Amir Boag; Vitaliy Lomakin; Eric Michielssen

    2010-01-01

    A multilevel Cartesian non-uniform grid time domain algorithm (CNGTDA) is introduced to rapidly compute transient wave fields radiated by time dependent three-dimensional source constellations. CNGTDA leverages the observation that transient wave fields generated by temporally bandlimited and spatially confined source constellations can be recovered via interpolation from appropriately delay- and amplitude-compensated field samples. This property is used in conjunction with

  15. Topology preserving advection of implicit interfaces on Cartesian grids

    NASA Astrophysics Data System (ADS)

    Qin, Zhipeng; Delaney, Keegan; Riaz, Amir; Balaras, Elias

    2015-06-01

    Accurate representation of implicit interface topology is important for the numerical computation of two phase flow on Cartesian grids. A new method is proposed for the construction of signed distance function by geometrically projecting interface topology onto the Cartesian grid using a multi-level projection framework. The method involves a stepwise improvement in the approximation to the signed distance function based on pointwise, piecewise and locally smooth reconstructions of the interface. We show that this approach provides accurate representation of the projected interface and its topology on the Cartesian grid, including the distance from the interface and the interface normal and curvature. The projected interface can be in the form of either a connected set of marker particles that evolve with Lagrangian advection, or a discrete set of points associated with an implicit interface that evolves with the advection of a scalar function. The signed distance function obtained with geometric projection is independent of the details of the scaler field, in contrast to the conventional approach where advection and reinitialization cannot be decoupled. As a result, errors introduced by reinitialization do not amplify advection errors, which leads to substantial improvement in both volume conservation and topology representation.

  16. Cartesian based grid generation/adaptive mesh refinement

    NASA Astrophysics Data System (ADS)

    Coirier, William J.

    1992-04-01

    Grid adaptation has recently received attention in the computational fluid dynamics (CFD) community as a means to capture the salient features of a flowfield by either moving grid points of a structured or by adding cells in an unstructured manner. An approach based on a background cartesian mesh is investigated from which the geometry is 'cut' out of the mesh. Once the mesh is obtained, a solution on this coarse grid is found, that indicates which cells need to be refined. This process of refining/solving continues until the flow is grid refined in terms of a user specified global parameter (such as drag coefficient etc.). The advantages of this approach are twofold: the generation of the base grid is independent of the topology of the bodies or surfaces around/through which the flow is to be computed, and the resulting grid (in uncut regions) is highly isotropic, so that the truncation error is low. The flow solver (which, along with the grid generation is still under development) uses a completely unstructured data base, and is a finite volume, upwinding scheme. Current and future work will address generating Navier-Stokes suitable grids by using locally aligned and normal face/cell refining. The attached plot shows a simple grid about two turbine blades.

  17. Cartesian based grid generation/adaptive mesh refinement

    NASA Technical Reports Server (NTRS)

    Coirier, William J.

    1992-01-01

    Grid adaptation has recently received attention in the computational fluid dynamics (CFD) community as a means to capture the salient features of a flowfield by either moving grid points of a structured or by adding cells in an unstructured manner. An approach based on a background cartesian mesh is investigated from which the geometry is 'cut' out of the mesh. Once the mesh is obtained, a solution on this coarse grid is found, that indicates which cells need to be refined. This process of refining/solving continues until the flow is grid refined in terms of a user specified global parameter (such as drag coefficient etc.). The advantages of this approach are twofold: the generation of the base grid is independent of the topology of the bodies or surfaces around/through which the flow is to be computed, and the resulting grid (in uncut regions) is highly isotropic, so that the truncation error is low. The flow solver (which, along with the grid generation is still under development) uses a completely unstructured data base, and is a finite volume, upwinding scheme. Current and future work will address generating Navier-Stokes suitable grids by using locally aligned and normal face/cell refining. The attached plot shows a simple grid about two turbine blades.

  18. Transformation from Cartesian to Geodetic Coordinates Accelerated by Halley's Method

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    2006-03-01

    By using Halley’s third-order formula to find the root of a non-linear equation, we develop a new iterative procedure to solve an irrational form of the “latitude equation”, the equation to determine the geodetic latitude for given Cartesian coordinates. With a limit to one iteration, starting from zero height, and minimizing the number of divisions by means of the rational form representation of Halley’s formula, we obtain a new non-iterative method to transform Cartesian coordinates to geodetic ones. The new method is sufficiently precise in the sense that the maximum error of the latitude and the relative height is less than 6 micro-arcseconds for the range of height, -10 km ? h ? 30,000 km. The new method is around 50% faster than our previous method, roughly twice as fast as the well-known Bowring’s method, and much faster than the recently developed methods of Borkowski, Laskowski, Lin and Wang, Jones, Pollard, and Vermeille.

  19. Comparison of Cartesian grid configurations for application of the finite-difference time-domain

    E-print Network

    Liou, K. N.

    tech- nique in a Cartesian system. One configuration defines the electric and magnetic field componentsComparison of Cartesian grid configurations for application of the finite-difference time-domain, and Jun Q. Lu Two grid configurations can be employed to implement the finite-difference time-domain FDTD

  20. The Numerical Simulation of Ship Waves using Cartesian Grid Methods

    E-print Network

    Sussman, Mark

    2014-01-01

    Two different cartesian-grid methods are used to simulate the flow around the DDG 5415. The first technique uses a "coupled level-set and volume-of-fluid" (CLS) technique to model the free-surface interface. The no-flux boundary condition on the hull is imposed using a finite-volume technique. The second technique uses a level-set technique (LS) to model the free-surface interface. A body-force technique is used to impose the hull boundary condition. The predictions of both numerical techniques are compared to whisker-probe measurements of the DDG 5415. The level-set technique is also used to investigate the breakup of a two-dimensional spray sheet.

  1. A multilevel Cartesian non-uniform grid time domain algorithm

    SciTech Connect

    Meng Jun [Cadence Research Center Beijing, 15/F Metropolis Tower, No. 2, Haidian Dongsanjie Street, Haidian District, Beijing 100080 (China); University of Illinois at Urbana Champaign, Urbana, IL 61801 (United States); Boag, Amir [School of Electrical Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Lomakin, Vitaliy, E-mail: vitaliy@ece.ucsd.ed [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Michielssen, Eric [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 (United States)

    2010-11-01

    A multilevel Cartesian non-uniform grid time domain algorithm (CNGTDA) is introduced to rapidly compute transient wave fields radiated by time dependent three-dimensional source constellations. CNGTDA leverages the observation that transient wave fields generated by temporally bandlimited and spatially confined source constellations can be recovered via interpolation from appropriately delay- and amplitude-compensated field samples. This property is used in conjunction with a multilevel scheme, in which the computational domain is hierarchically decomposed into subdomains with sparse non-uniform grids used to obtain the fields. For both surface and volumetric source distributions, the computational cost of CNGTDA to compute the transient field at N{sub s} observation locations from N{sub s} collocated sources for N{sub t} discrete time instances scales as O(N{sub t}N{sub s}logN{sub s}) and O(N{sub t}N{sub s}log{sup 2}N{sub s}) in the low- and high-frequency regimes, respectively. Coupled with marching-on-in-time (MOT) time domain integral equations, CNGTDA can facilitate efficient analysis of large scale time domain electromagnetic and acoustic problems.

  2. An Adaptive Cartesian Grid Method For Unsteady Compressible Flow In Irregular Regions

    Microsoft Academic Search

    Richard B. Pember; John B. Bell; Phillip Colella

    1993-01-01

    In this paper we describe an adaptive Cartesian grid method for modeling timedependentinviscid compressible flow in irregular regions. In this approach a bodyis treated as an interface embedded in a regular Cartesian mesh. The single gridalgorithm uses an unsplit second-order Godunov algorithm followed by a correctorapplied to cells at the boundary. The discretization near the fluid-body interfaceis based on a

  3. CARTESIAN GRID SOLUTION OF THE EULER EQUATIONS USING A GRIDLESS BOUNDARY CONDITION TREATMENT

    E-print Network

    Liu, Feng

    CARTESIAN GRID SOLUTION OF THE EULER EQUATIONS USING A GRIDLESS BOUNDARY CONDITION TREATMENT D. J The convergence properties of a patched Cartesian field mesh using a gridless boundary condition treatment are presented in the solution of the Euler equations for transonic flow. The gridless treatment employs a least

  4. An Adaptive Cartesian Grid Method for Unsteady Compressible Flow in Irregular Regions

    Microsoft Academic Search

    Richard B. Pember; John B. Bell; Phillip Colella; William Y. Curtchfield; Michael L. Welcome

    1995-01-01

    In this paper we describe an adaptive Cartesian grid method for modeling time-dependent inviscid compressible flow in irregular regions. In this approach a body is treated as an interface embedded in a regular Cartesian mesh. The single grid algorithm uses an unsplit second-order Godunov algorithm followed by a corrector applied to cells at the boundary. The discretization near the fluid-body

  5. American Institute of Aeronautics and Astronautics Wall-Layer Modeling for Cartesian Grid Solver Using an

    E-print Network

    Yang, Jianming

    turbulence simulations such as large eddy simulation (LES) [1]. However, near-wall resolution for such high are difficult. Immersed boundary method (IBM) based Cartesian grid solvers involve extremely easy grid Using an Overset Boundary Layer Orthogonal Curvilinear Grid S. Bhushan, A. Hanaoka, J. Yang and F. Stern

  6. Euler solution using adaptive Cartesian grid with a gridless boundary treatment

    NASA Astrophysics Data System (ADS)

    Xiang, Liang; Yang, Guowei

    2009-04-01

    A quadtree-based adaptive Cartesian grid generator and flow solver were developed. The grid adaptation based on pressure or density gradient was performed and a gridless method based on the least-square fashion was used to treat the wall surface boundary condition, which is generally difficult to be handled for the common Cartesian grid. First, to validate the technique of grid adaptation, the benchmarks over a forward-facing step and double Mach reflection were computed. Second, the flows over the NACA 0012 airfoil and a two-element airfoil were calculated to validate the developed gridless method. The computational results indicate the developed method is reasonable for complex flows.

  7. The Numerical Simulation of Ship Waves Using Cartesian-Grid and Volume-of-Fluid Methods

    E-print Network

    Dommermuth, Douglas G; Wyatt, Donald C; Sussman, Mark; Weymouth, Gabriel D; Yue, Dick K P; Adams, Paul; Hand, Randall

    2014-01-01

    Cartesian-grid methods in combination with immersed-body and volume-of-fluid methods are ideally suited for simulating breaking waves around ships. A surface panelization of the ship hull is used as input to impose body-boundary conditions on a three-dimensional cartesian grid. The volume-of-fluid portion of the numerical algorithm is used to capture the free-surface interface, including the breaking of waves. The numerical scheme is implemented on a parallel computer. Various numerical issues are discussed, including implementing exit boundary conditions, conserving mass using a novel regridding algorithm, improving resolution through the use of stretched grids, minimizing initial transients, and enforcing hull boundary conditions on cartesian grids. Numerical predictions are compared to experimental measurements of ship models moving with forward speed, including model 5415 and model 5365 (Athena). The ability to model forced-motions is illustrated using a heaving sphere moving with forward speed.

  8. Adaptively refined, parallelised sharp interface Cartesian grid method for three-dimensional moving boundary problems

    Microsoft Academic Search

    H. S. Udaykumar; Sreedevi Krishnan; Saikrishna V. Marella

    2009-01-01

    Sharp interface Cartesian grid methods are capable of simulating complex moving boundary problems on fixed meshes while treating embedded interfaces accurately. This article further enhances the effectiveness of the sharp interface method by devising techniques for adaptive mesh resolution combined with parallel processing. These extensions enable dealing with problems involving disparate length scales encountered in many applications. A tree-based adaptive

  9. A Cartesian Grid Embedded Boundary Method for the Compressible Navier Stokes Equations

    E-print Network

    A Cartesian Grid Embedded Boundary Method for the Compressible Navier Stokes Equations Daniel T Abstract In this paper, we present an unsplit method for the time-dependent compressible Navier-Stokes method for the time-dependent compress- ible Navier-Stokes equations in two and three dimensions

  10. A Cartesian grid embedded boundary method for the heat equation and Poissons equation in three dimensions

    E-print Network

    A Cartesian grid embedded boundary method for the heat equation and PoissonÕs equation in three for solving PoissonÕs equation and the heat equation on irregular domains in three dimen- sions. Our work uses equation; Heat equation; Multigrid methods 0021-9991/$ - see front matter Ó 2005 Elsevier Inc. All rights

  11. Cartesian Coordinates The adjective Cartesian above refers to Rene Descartes (15961650), who was the first

    E-print Network

    Banaji,. Murad

    (three) mutually perpendicular axes through O, which we shall label as the x-, y- and z-axes. The x of the x-, y- and z-axes respectively. 14 #12;Let R be the point whose co¨ordinates are (a, b, c), and let

  12. Large-Eddy Simulation of Ship Flows with Wall-Layer Models on Cartesian Grids

    Microsoft Academic Search

    Jianming Yang; Shanti Bhushan; Jung Soo Suh; Zhaoyuan Wang; Bonguk Koo; Nobuaki Sakamoto; Tao Xing; Frederick Stern

    The recent development of CFDShip-Iowa Version 6, a high-performance, high-fidelity Cartesian grid solver for computational ship hydrodynamics, is presented. First, a wall function approach has been introduced for wall-layer modeling based on the immersed boundary method and the one-equation Spalart-Allmaras turbulence model. Second, in order to develop more advanced wall-layer modeling schemes, an orthogonal curvilinear grid solver based on the

  13. Alternative transformation from Cartesian to geodetic coordinates by least squares for GPS georeferencing applications

    Microsoft Academic Search

    T. Soler; J. Y. Han; N. D. Weston

    The inverse transformation of coordinates, from Cartesian to curvilinear geodetic, or symbolically (x,y,z)?(?,?,h) has been extensively researched in the geodetic literature. However, published formulations require that the application must be deterministically implemented point-by-point individually. Recently, and thanks to GPS technology, scientists have made available thousands of determinations of the coordinates (x,y,z) at a single point perhaps characterized by different observational

  14. Equivalence of the Path Integral for Fermions in Cartesian and Spherical Coordinates

    E-print Network

    Andrew Briggs; Horacio E. Camblong; Carlos R. Ordonez

    2013-07-05

    The path-integral calculation for the free energy of a spin-1/2 Dirac-fermion gas is performed in spherical polar coordinates for a flat spacetime geometry. Its equivalence with the Cartesian-coordinate representation is explicitly established. This evaluation involves a relevant limiting case of the fermionic path integral in a Schwarzschild background, whose near-horizon limit has been shown to be related to black hole thermodynamics.

  15. Active stiffness control of a manipulator in cartesian coordinates

    Microsoft Academic Search

    J. Kenneth Salisbury

    1980-01-01

    A method of actively controlling the apparent stiffness of a manipulator end effecter is presented. The approach allows the programmer to specify the three transnational and three rotational stiffness of a frame located arbitrarily in hand coordinates. Control of the nominal position of the hand then permits simultaneous position and force control. Stiffness may be changed under program control to

  16. Euler Technology Assessment program for preliminary aircraft design employing SPLITFLOW code with Cartesian unstructured grid method

    NASA Technical Reports Server (NTRS)

    Finley, Dennis B.

    1995-01-01

    This report documents results from the Euler Technology Assessment program. The objective was to evaluate the efficacy of Euler computational fluid dynamics (CFD) codes for use in preliminary aircraft design. Both the accuracy of the predictions and the rapidity of calculations were to be assessed. This portion of the study was conducted by Lockheed Fort Worth Company, using a recently developed in-house Cartesian-grid code called SPLITFLOW. The Cartesian grid technique offers several advantages for this study, including ease of volume grid generation and reduced number of cells compared to other grid schemes. SPLITFLOW also includes grid adaptation of the volume grid during the solution convergence to resolve high-gradient flow regions. This proved beneficial in resolving the large vortical structures in the flow for several configurations examined in the present study. The SPLITFLOW code predictions of the configuration forces and moments are shown to be adequate for preliminary design analysis, including predictions of sideslip effects and the effects of geometry variations at low and high angles of attack. The time required to generate the results from initial surface definition is on the order of several hours, including grid generation, which is compatible with the needs of the design environment.

  17. A Cartesian Grid Embedded Boundary Method for the Heat Equation on Irregular Domains

    Microsoft Academic Search

    Peter McCorquodale; Phillip Colella; Hans Johansen

    2001-01-01

    We present an algorithm for solving the heat equation on irregular time-dependent domains. It is based on the Cartesian grid embedded boundary algorithm of Johansen and Colella (1998, J. Comput. Phys.147, 60) for discretizing Poisson's equation, combined with a second-order accurate discretization of the time derivative. This leads to a method that is second-order accurate in space and time. For

  18. Two Phase Level-Set\\/Immersed-Boundary Cartesian Grid Method for Ship Hydrodynamics

    Microsoft Academic Search

    Jianming Yang; Nobuaki Sakamoto; Zhaoyuan Wang; Pablo Carrica; Frederick Stern

    Recent progress at IIHR on the development of CFDShip-Iowa version 6 is presented. Current focus is on a sharp interface Cartesian grid method for the large-eddy simulation (LES) of turbulent two-phase incompressible flows. In this method, the level set formulation for two-phase incompressible flows is adopted. The density and pressure jump conditions across the interface (the latter due to surface

  19. On the new analytical solution for a well in Cartesian coordinates with MODFLOW comparisons.

    PubMed

    Batu, Vedat

    2014-01-01

    In this paper, the comparison process of Batu (2012) generalized three-dimensional well hydraulics solution for confined aquifers in Cartesian coordinates with MODFLOW is presented. First, a brief description of Batu (2012) solution along with the governing equations and some of its key features are described. The final average drawdown expression in an observation well is given with the conversion expressions from Cartesian to radial coordinates. A generalized comparison using Batu (2012), Hantush (1964), and MODFLOW (Harbaugh et al. 2000), for vertical wells in horizontally isotropic aquifers, that is, ayx ?=?Ky /Kx ?=?1, is presented. Comparisons are also presented with Batu (2012) and MODFLOW for horizontally anisotropic aquifers, that is, ayx ???1. After that comparisons are presented for horizontal wells between Batu (2012) and MODFLOW. PMID:24236933

  20. A Cartesian Grid Method for Solving the Two-Dimensional Streamfunction-Vorticity Equations in Irregular Regions

    Microsoft Academic Search

    Donna Calhoun

    2002-01-01

    We describe a method for solving the two-dimensional Navier–Stokes equations in irregular physical domains. Our method is based on an underlying uniform Cartesian grid and second-order finite-difference\\/finite-volume discretizations of the streamfunction-vorticity equations. Geometry representing stationary solid obstacles in the flow domain is embedded in the Cartesian grid and special discretizations near the embedded boundary ensure the accuracy of the solution

  1. Pipelined Cartesian-to-Polar Coordinate Conversion Based on SRT Division

    Microsoft Academic Search

    Sung-Won Lee; Ki-Seok Kwon; In-Cheol Park

    2007-01-01

    This brief proposes a new Cartesian-to-polar coordinate conversion technique based on the radix-4 SRT division. The coarse quotient is used to derive the magnitude and the coarse phase by referring to tables, while the fine quotient is applied to linearly interpolate the fine phase to be added to the coarse phase. Compared to the CORDIC-based techniques, the proposed conversion requires

  2. Linear transformation of anharmonic molecular force constants between normal and Cartesian coordinates.

    PubMed

    Mackie, Cameron J; Candian, Alessandra; Huang, Xinchuan; Lee, Timothy J; Tielens, Alexander G G M

    2015-06-28

    A full derivation of the analytic transformation of the quadratic, cubic, and quartic force constants from normal coordinates to Cartesian coordinates is given. Previous attempts at this transformation have resulted in non-linear transformations; however, for the first time, a simple linear transformation is presented here. Two different approaches have been formulated and implemented, one of which does not require prior knowledge of the translation-rotation eigenvectors from diagonalization of the Hessian matrix. The validity of this method is tested using two molecules H2O and c-C3H2D(+). PMID:26133410

  3. Cartesian grid simulations of gas-solids flow systems with complex geometry

    SciTech Connect

    Dietiker, Jean-Francois; Li, Tingwen; Garg, Rahul; Mehrdad Shahnam

    2013-02-01

    Complex geometries encountered in many applications of gas–solids flow need special treatment in most legacy multiphase flow solvers with Cartesian numerical grid. This paper briefly outlines the implementation of a cut cell technique in the open-source multiphase flow solver—MFIX for accurate representation of complex geometries. Specifically, applications of the Cartesian cut cell method to different gas–solids fluidization systems including a small scale bubbling fluidized bed with submerged tube bundle and a complete pilot-scale circulating fluidized bed will be presented. In addition to qualitative predictions on the general flow behaviors inside each system, quantitative comparison with the available experimental data will be presented. Furthermore, some results on extending the current cut-cell technique to Lagrangian–Eulerian simulations will be presented.

  4. The Numerical Simulation of Ship Waves Using Cartesian Grid Methods with Adaptive Mesh Refinement

    E-print Network

    Dommermuth, Douglas G; Beck, Robert F; O'Shea, Thomas T; Wyatt, Donald C; Olson, Kevin; MacNeice, Peter

    2014-01-01

    Cartesian-grid methods with Adaptive Mesh Refinement (AMR) are ideally suited for simulating the breaking of waves, the formation of spray, and the entrainment of air around ships. As a result of the cartesian-grid formulation, minimal input is required to describe the ships geometry. A surface panelization of the ship hull is used as input to automatically generate a three-dimensional model. No three-dimensional gridding is required. The AMR portion of the numerical algorithm automatically clusters grid points near the ship in regions where wave breaking, spray formation, and air entrainment occur. Away from the ship, where the flow is less turbulent, the mesh is coarser. The numerical computations are implemented using parallel algorithms. Together, the ease of input and usage, the ability to resolve complex free-surface phenomena, and the speed of the numerical algorithms provide a robust capability for simulating the free-surface disturbances near a ship. Here, numerical predictions, with and without AMR,...

  5. A Cartesian grid embedded boundary method for Poisson`s equation on irregular domains

    SciTech Connect

    Johansen, H. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering; Colella, P. [Lawrence Berkeley National Lab., CA (United States). Center for Computational Sciences and Engineering

    1997-01-31

    The authors present a numerical method for solving Poisson`s equation, with variable coefficients and Dirichlet boundary conditions, on two-dimensional regions. The approach uses a finite-volume discretization, which embeds the domain in a regular Cartesian grid. They treat the solution as a cell-centered quantity, even when those centers are outside the domain. Cells that contain a portion of the domain boundary use conservation differencing of second-order accurate fluxes, on each cell volume. The calculation of the boundary flux ensures that the conditioning of the matrix is relatively unaffected by small cell volumes. This allows them to use multi-grid iterations with a simple point relaxation strategy. They have combined this with an adaptive mesh refinement (AMR) procedure. They provide evidence that the algorithm is second-order accurate on various exact solutions, and compare the adaptive and non-adaptive calculations.

  6. Coordinating Workflows in Shared Grid Environments

    Microsoft Academic Search

    Jim Blythe; Yolanda Gil; Ewa Deelman

    Computational grids are characterized by widely distributed computational resources shared by virtual organizations. Users submit workflows of tasks to be executed, some of which may duplicated because of their shared application domain. The problem of allocating tasks to resources in grids has unique characteristics, governed by three features. First, users are generally interested in workflows, coordinated sets of tasks that

  7. A Cartesian grid embedded boundary method for the heat equation on irregular domains

    SciTech Connect

    McCorquodale, Peter; Colella, Phillip; Johansen, Hans

    2001-03-14

    We present an algorithm for solving the heat equation on irregular time-dependent domains. It is based on the Cartesian grid embedded boundary algorithm of Johansen and Colella (J. Comput. Phys. 147(2):60--85) for discretizing Poisson's equation, combined with a second-order accurate discretization of the time derivative. This leads to a method that is second-order accurate in space and time. For the case where the boundary is moving, we convert the moving-boundary problem to a sequence of fixed-boundary problems, combined with an extrapolation procedure to initialize values that are uncovered as the boundary moves. We find that, in the moving boundary case, the use of Crank--Nicolson time discretization is unstable, requiring us to use the L{sub 0}-stable implicit Runge--Kutta method of Twizell, Gumel, and Arigu.

  8. A Multi-solver Scheme for Viscous Flows Using Adaptive Cartesian Grids and Meshless Grid

    E-print Network

    Jameson, Antony

    , Stanford, CA Andrew M. Wissink Ames Research Center, Moffett Field, CA This work concerns the development Communication Aaron Katz and Antony Jameson Department of Aeronautics and Astronautics, Stanford University of an adaptive multi-solver approach for CFD sim- ulation of viscous flows. Curvilinear grids are used near solid

  9. A fully conservative finite-volume method for incompressible Navier-Stokes equations on locally refined nested Cartesian grids

    NASA Astrophysics Data System (ADS)

    Sifounakis, Adamandios; You, Donghyun; Singh, Satbir

    2011-11-01

    A second-order-accurate finite-volume method is developed for the solution of incompressible Navier-Stokes equations on locally refined nested Cartesian grids. Numerical accuracy and stability on locally refined nested Cartesian grids are achieved using a finite-volume discretization of the incompressible Navier-Stokes equations based on higher- order conservation principles - i.e., in addition to mass and momentum conservation, kinetic energy conservation in the inviscid limit is used to guide the selection of the discrete operators and solution algorithm. Hanging nodes at the interface are implicitly slanted to improve the pressure-velocity projection, while the other parts of the grid maintain an orthogonal Cartesian grid topology. The present method is found to significantly improve the computational efficiency while it is straightforward to implement. The present method shows superior conservation of mass, momentum, and kinetic energy compared to the conventional methods employing interpolation at the interface between coarse and fine grids in simulations of Taylor vortex, lid-driven cavity flow, and flow over a square cylinder. Supported by the Army Research Office Grant W911NF1010348.

  10. A Sharp Interface Cartesian Grid Method for Simulating Flows with Complex Moving Boundaries

    NASA Astrophysics Data System (ADS)

    Udaykumar, H. S.; Mittal, R.; Rampunggoon, P.; Khanna, A.

    2001-11-01

    A Cartesian grid method for computing flows with complex immersed, moving boundaries is presented. The flow is computed on a fixed Cartesian mesh and the solid boundaries are allowed to move freely through the mesh. A mixed Eulerian-Lagrangian framework is employed, which allows us to treat the immersed moving boundary as a sharp interface. The incompressible Navier-Stokes equations are discretized using a second-order-accurate finite-volume technique, and a second-order- accurate fractional-step scheme is employed for time advancement. The fractional-step method and associated boundary conditions are formulated in a manner that properly accounts for the boundary motion. A unique problem with sharp interface methods is the temporal discretization of what are termed “freshly cleared” cells, i.e., cells that are inside the solid at one time step and emerge into the fluid at the next time step. A simple and consistent remedy for this problem is also presented. The solution of the pressure Poisson equation is usually the most time-consuming step in a fractional step scheme and this is even more so for moving boundary problems where the flow domain changes constantly. A multigrid method is presented and is shown to accelerate the convergence significantly even in the presence of complex immersed boundaries. The methodology is validated by comparing it with experimental data on two cases: (1) the flow in a channel with a moving indentation on one wall and (2) vortex shedding from a cylinder oscillating in a uniform free-stream. Finally, the application of the current method to a more complicated moving boundary situation is also demonstrated by computing the flow inside a diaphragm-driven micropump with moving valves.

  11. A Domain-Decomposed Multi-Level Method for Adaptively Refined Cartesian Grids with Embedded Boundaries

    NASA Technical Reports Server (NTRS)

    Aftosmis, M. J.; Berger, M. J.; Adomavicius, G.; Nixon, David (Technical Monitor)

    1998-01-01

    The work presents a new method for on-the-fly domain decomposition technique for mapping grids and solution algorithms to parallel machines, and is applicable to both shared-memory and message-passing architectures. It will be demonstrated on the Cray T3E, HP Exemplar, and SGI Origin 2000. Computing time has been secured on all these platforms. The decomposition technique is an outgrowth of techniques used in computational physics for simulations of N-body problems and the event horizons of black holes, and has not been previously used by the CFD community. Since the technique offers on-the-fly partitioning, it offers a substantial increase in flexibility for computing in heterogeneous environments, where the number of available processors may not be known at the time of job submission. In addition, since it is dynamic it permits the job to be repartitioned without global communication in cases where additional processors become available after the simulation has begun, or in cases where dynamic mesh adaptation changes the mesh size during the course of a simulation. The platform for this partitioning strategy is a completely new Cartesian Euler solver tarcreted at parallel machines which may be used in conjunction with Ames' "Cart3D" arbitrary geometry simulation package.

  12. A class of Cartesian grid embedded boundary algorithms for incompressible flow with time-varying complex geometries

    NASA Astrophysics Data System (ADS)

    Lee, Long; Vankova, Irena

    2011-10-01

    We present a class of numerical algorithms for simulating viscous fluid problems of incompressible flow interacting with moving rigid structures. The proposed Cartesian grid embedded boundary algorithms employ a slightly different idea from the traditional direct-forcing immersed boundary methods: the proposed algorithms calculate and apply the force density in the extended solid domain to uphold the solid velocity and hence the boundary condition at the rigid-body surface. The principle of the embedded boundary algorithm allows us to solve the fluid equations on a Cartesian grid with a set of external forces spread onto the grid points occupied by the rigid structure. The proposed algorithms use the MAC (marker and cell) algorithm to solve the incompressible Navier-Stokes equations. Unlike projection methods, the MAC scheme incorporates the gradient of the force density in solving the pressure Poisson equation, so that the dipole force, due to the jump of pressure across the solid-fluid interface, is directly balanced by the gradient of the force density. We validate the proposed algorithms via the classical benchmark problem of flow past a cylinder. Our numerical experiments show that numerical solutions of the velocity field obtained by using the proposed algorithms are smooth across the solid-fluid interface. Finally, we consider the problem of a cylinder moving between two parallel plane walls. Numerical solutions of this problem obtained by using the proposed algorithms are compared with the classical asymptotic solutions. We show that the two solutions are in good agreement.

  13. Characterization of genome-wide ordered sequence-tagged Mycobacterium mutant libraries by Cartesian Pooling-Coordinate Sequencing.

    PubMed

    Vandewalle, Kristof; Festjens, Nele; Plets, Evelyn; Vuylsteke, Marnik; Saeys, Yvan; Callewaert, Nico

    2015-01-01

    Reverse genetics research approaches require the availability of methods to rapidly generate specific mutants. Alternatively, where these methods are lacking, the construction of pre-characterized libraries of mutants can be extremely valuable. However, this can be complex, expensive and time consuming. Here, we describe a robust, easy to implement parallel sequencing-based method (Cartesian Pooling-Coordinate Sequencing or CP-CSeq) that reports both on the identity as well as on the location of sequence-tagged biological entities in well-plate archived clone collections. We demonstrate this approach using a transposon insertion mutant library of the Mycobacterium bovis BCG vaccine strain, providing the largest resource of mutants in any strain of the M. tuberculosis complex. The method is applicable to any entity for which sequence-tagged identification is possible. PMID:25960123

  14. Characterization of genome-wide ordered sequence-tagged Mycobacterium mutant libraries by Cartesian Pooling-Coordinate Sequencing

    PubMed Central

    Vandewalle, Kristof; Festjens, Nele; Plets, Evelyn; Vuylsteke, Marnik; Saeys, Yvan; Callewaert, Nico

    2015-01-01

    Reverse genetics research approaches require the availability of methods to rapidly generate specific mutants. Alternatively, where these methods are lacking, the construction of pre-characterized libraries of mutants can be extremely valuable. However, this can be complex, expensive and time consuming. Here, we describe a robust, easy to implement parallel sequencing-based method (Cartesian Pooling-Coordinate Sequencing or CP-CSeq) that reports both on the identity as well as on the location of sequence-tagged biological entities in well-plate archived clone collections. We demonstrate this approach using a transposon insertion mutant library of the Mycobacterium bovis BCG vaccine strain, providing the largest resource of mutants in any strain of the M. tuberculosis complex. The method is applicable to any entity for which sequence-tagged identification is possible. PMID:25960123

  15. 1. (a)Derive the three dimensional heat diffusion equation in Cartesian coordinates (14%), and @)describe the three kinds of boundary conditions generally

    E-print Network

    Huang, Haimei

    1. (a)Derive the three dimensional heat diffusion equation in Cartesian coordinates (14%), and @)describe the three kinds of boundary conditions generally encountered in heat transfer problems. (6 %) 2. Consider a long cylinder with radius Ri and uniform volumetric heat generation rate g. The cylinder

  16. Coordinates

    NSDL National Science Digital Library

    David Stern

    This introduction to the labeling of points on a plane by their Cartesian coordinates can optionally be extended to coordinates in 3-dimensional space, to plane polar coordinates and to 3-dimensional polar coordinates. Students should learn to use Cartesian coordinates (x,y) for defining the position of a point in two dimensions and to use Cartesian coordinates (x,y,z) in 3-dimensional space and learn to appreciate the two ways of defining the z axis. Students should also become familiar with some of the tools and terms used by surveyors such as theodolite, azimuth, elevation, and zenith. Optional items for students familiar with trigonometry and with the theorem of Pythagoras are polar coordinates (r,f ) on the plane, Converting (r,f) to (x,y) and vice versa, at least for r, and Spherical polar coordinates (r,q, f) in 3-dimensional space.

  17. Parallel large-eddy simulations of turbulent flows with complex moving boundaries on fixed Cartesian grids

    Microsoft Academic Search

    Jianming Yang; Elias Balaras

    A parallel embedded boundary approach for large-eddy simulations of turbulent flows with complex geometries and dynamically moving boundaries on fixed orthogonal grids is presented. The underlying solver is based on a second-order fractional step method on a staggered grid. The boundary conditions on an arbitrary immersed interface are satisfied via second-order local reconstructions. The parallelization is implemented via a slab

  18. Coordinated motion control of multiple robotic devices for welding and redundancy coordination through constrained optimization in Cartesian space

    Microsoft Academic Search

    S. Ahmad; S. Luo

    1989-01-01

    The problem of coordinating a positioning table and a seven-axis manipulator is examined. The method described is based on subdivision of tasks. The welding table is coordinated to align the weld point surface normal antiparallel to the direction of gravity. The seven-axis robot (a six-axis Cybotech WV 15 robot and a track) is constrained to move the weld torch along

  19. Three-dimensional adaptive Cartesian grid method with conservative interface restructuring and reconstruction

    Microsoft Academic Search

    Rajkeshar Singh; Wei Shyy

    2007-01-01

    Multiphase flows associated with interfacial dynamics, steep jumps in fluid properties and moving boundaries between different phases pose substantial computational challenges in terms of both modeling as well as computational efficiency. The present work extends a marker-based immersed boundary, or front tracking, technique to model the three-dimensional interfacial dynamics. It tracks the moving boundary using triangulated surface grids and solves

  20. Efficient generation of the cartesian coordinates of truncated icosahedron and related polyhedra.

    PubMed

    Hosoya, H; Maruyama, Y

    2001-01-01

    Efficient algorithms for deriving the analytical expressions of the rectangular coordinates of the vertices of regular polyhedra and truncated icosahedron inscribed in a cube is described and the results are exposed. Various characteristic quantities of the geometrical structure of truncated icosahedron are obtained. Kaleidoscopes for projecting the truncated icosahedron are discussed. PMID:11391870

  1. Analyzing electromagnetic structures with curved boundaries on Cartesian FDTD meshes

    Microsoft Academic Search

    Yang Hao; Chris J. Railton

    1998-01-01

    In this paper, a new finite-difference time-domain (FDTD) algorithm is investigated to analyze electromagnetic structures with curved boundaries using a Cartesian coordinate system. The new algorithm is based on a nonorthogonal FDTD method. However, only those cells near the curved boundaries are calculated by nonorthogonal FDTD formulas; most of the grid is orthogonal and can be determined by traditional FDTD

  2. Coordinated motion control of multiple robotic devices for welding and redundancy coordination through constrained optimization in Cartesian space

    Microsoft Academic Search

    Shaheen Ahmad; Shengwu Luo

    1988-01-01

    The authors consider the problem of coordinating multiple motion devices for welding purposes. They focus on the problem of controlling a positioning table and a seven-axis manipulator, given the parametric definition of a trajectory on a weld piece. The problem is complex as there are more than nine axes involved and a number of permutations are possible which achieve the

  3. Simulation of a prescribed fruitfly flapping motion by the ALE-GFD method on a hybrid Cartesian-meshfree grid

    NASA Astrophysics Data System (ADS)

    Trong, N. T.; Lim, T. T.; Yeo, K. S.

    2011-11-01

    The flapping-wing aerodynamics of insects has been a subject of immense interest for many years. The Arbitrary Lagrangian-Eulerian - Generalized Finite Difference (ALE-GFD) computational scheme on hybrid convecting Cartesian-meshfree grid systems represents a viable alternative to existing mesh-based and immersed boundary approaches for simulating the highly complex and unsteady flows generated by the flapping wings of insects. The three-dimensional flapping-wing flows of a fruitfly (Drosophila) are simulated in the present study. As the forces generated are very sensitive to the acceleration of the wings, a smoothing process was applied on the flapping kinematics to suppress non-physical fluctuations and spikes from the force outcome. The resulting lift and drag forces are then validated with the experimental results, obtained from a parallel experimental study conducted by the research group, measured on a fruitfly-like wing profile executing the identical motion. The excellent agreement between the results demonstrates the feasibility and efficacy of the ALE-GFD numerical approach.

  4. Large-eddy simulation of flow separation on an airfoil at a high angle of attack and Re  = 10 5 using Cartesian grids

    Microsoft Academic Search

    Sven Eisenbach; Rainer Friedrich

    2008-01-01

    Incompressible flow separating from the upper surface of an airfoil at an 18° angle of attack and a Reynolds number of Re = 105, based on the freestream velocity and chord length c, is studied by the means of large-eddy simulation (LES). The numerical method is based on second-order central spatial discretization\\u000a on a Cartesian grid using an immersed boundary

  5. Sharp Interface Immersed-Boundary\\/Level-Set Cartesian Grid Method for Large-Eddy Simulation of Two-Phase Flows with SurfacePiercing Moving Bodies

    Microsoft Academic Search

    Jianming Yang; Frederick Stern

    2007-01-01

    A sharp interface Cartesian grid method for the large-eddy simulation of two-phase flows interacting with surface-piercing moving bodies is presented. The method is based on a sharp interface immersed boundary formulation for fluid flows with moving boundaries and a level set based ghost fluid method for two-phase interface treatment. A four-step fractional step method is adopted and a Lagrangian dynamic

  6. Coordination of Cloud Computing and Smart Power Grids

    E-print Network

    Mohsenian-Rad, Hamed

    Coordination of Cloud Computing and Smart Power Grids Amir-Hamed Mohsenian-Rad and Alberto Leon.mohsenian.rad, alberto.leongarcia}@utoronto.ca Abstract--The emergence of cloud computing has established a trend towards increasing the load at locations where they are built. However, data centers and cloud computing also provide

  7. Computing UV/vis spectra from the adiabatic and vertical Franck-Condon schemes with the use of Cartesian and internal coordinates

    SciTech Connect

    Götze, Jan P.; Karasulu, Bora; Thiel, Walter [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany)] [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany)

    2013-12-21

    We address the effects of using Cartesian or internal coordinates in the adiabatic Franck-Condon (AFC) and vertical Franck-Condon (VFC) approaches to electronic spectra. The adopted VFC approach is a simplified variant of the original approach [A. Hazra, H. H. Chang, and M. Nooijen, J. Chem. Phys. 151, 2125 (2004)], as we omit any contribution from normal modes with imaginary frequency. For our test molecules ranging from ethylene to flavin compounds, VFC offers several advantages over AFC, especially by preserving the properties of the FC region and by avoiding complications arising from the crossing of excited-state potential surfaces or from the failure of the harmonic approximation. The spectral quality for our target molecules is insensitive to the chosen approach. We also explore the effects of Duschinsky rotation and relate the need for internal coordinates to the absence of symmetry elements. When using Duschinsky rotation and treating larger systems without planar symmetry, internal coordinates are found to outperform Cartesian coordinates in the AFC spectral calculations.

  8. G-GPE Squares on a coordinate grid

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: In the picture below a square is outlined whose vertices lie on the coordinate grid points: The area of this particular square is 16 square units. For ...

  9. Concurrent negotiation and coordination for grid resource coallocation.

    PubMed

    Sim, Kwang Mong; Shi, Benyun

    2010-06-01

    Bolstering resource coallocation is essential for realizing the Grid vision, because computationally intensive applications often require multiple computing resources from different administrative domains. Given that resource providers and consumers may have different requirements, successfully obtaining commitments through concurrent negotiations with multiple resource providers to simultaneously access several resources is a very challenging task for consumers. The impetus of this paper is that it is one of the earliest works that consider a concurrent negotiation mechanism for Grid resource coallocation. The concurrent negotiation mechanism is designed for 1) managing (de)commitment of contracts through one-to-many negotiations and 2) coordination of multiple concurrent one-to-many negotiations between a consumer and multiple resource providers. The novel contributions of this paper are devising 1) a utility-oriented coordination (UOC) strategy, 2) three classes of commitment management strategies (CMSs) for concurrent negotiation, and 3) the negotiation protocols of consumers and providers. Implementing these ideas in a testbed, three series of experiments were carried out in a variety of settings to compare the following: 1) the CMSs in this paper with the work of others in a single one-to-many negotiation environment for one resource where decommitment is allowed for both provider and consumer agents; 2) the performance of the three classes of CMSs in different resource market types; and 3) the UOC strategy with the work of others [e.g., the patient coordination strategy (PCS )] for coordinating multiple concurrent negotiations. Empirical results show the following: 1) the UOC strategy achieved higher utility, faster negotiation speed, and higher success rates than PCS for different resource market types; and 2) the CMS in this paper achieved higher final utility than the CMS in other works. Additionally, the properties of the three classes of CMSs in different kinds of resource markets are also verified. PMID:19884094

  10. George W. Arnold George Arnold was appointed National Coordinator for Smart Grid Interoperability at the

    E-print Network

    Magee, Joseph W.

    George W. Arnold George Arnold was appointed National Coordinator for Smart Grid Interoperability the development of standards underpinning the nation's Smart Grid. Dr. Arnold joined NIST in September 2006

  11. Cartesian Diver

    NSDL National Science Digital Library

    2012-06-26

    In this quick activity (page 1 of the PDF), learners will build a simple Cartesian Diver in an empty 2-liter bottle. Use this activity to demonstrate the principle of buoyancy, similar to the bladder system many fish rely on to move up and down in their watery environment. Relates to the linked video, DragonflyTV GPS: California Fish.

  12. A Cartesian grid embedded boundary method for solving the Poisson and heat equations with discontinuous coefficients in three dimensions

    SciTech Connect

    Crockett, R.K., E-mail: RKCrockett@txcorp.co [Applied Numerical Algorithms Group, Lawrence Berkeley National Laboratory, MS 50A-1148, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Colella, P.; Graves, D.T. [Applied Numerical Algorithms Group, Lawrence Berkeley National Laboratory, MS 50A-1148, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

    2011-04-01

    We present a method for solving Poisson and heat equations with discontinuous coefficients in two- and three-dimensions. It uses a Cartesian cut-cell/embedded boundary method to represent the interface between materials, as described in Johansen and Colella (1998). Matching conditions across the interface are enforced using an approximation to fluxes at the boundary. Overall second order accuracy is achieved, as indicated by an array of tests using non-trivial interface geometries. Both the elliptic and heat solvers are shown to remain stable and efficient for material coefficient contrasts up to 10{sup 6}, thanks in part to the use of geometric multigrid. A test of accuracy when adaptive mesh refinement capabilities are utilized is also performed. An example problem relevant to nuclear reactor core simulation is presented, demonstrating the ability of the method to solve problems with realistic physical parameters.

  13. A Cartesian grid embedded boundary method for solving the Poisson and heat equations with discontinuous coefficients in three dimensions

    SciTech Connect

    Crockett, Robert; Graves, Daniel; Colella, Phillip

    2009-10-23

    We present a method for solving Poisson and heat equations with discon- tinuous coefficients in two- and three-dimensions. It uses a Cartesian cut-cell/embedded boundary method to represent the interface between materi- als, as described in Johansen& Colella (1998). Matching conditions across the interface are enforced using an approximation to fluxes at the boundary. Overall second order accuracy is achieved, as indicated by an array of tests using non-trivial interface geometries. Both the elliptic and heat solvers are shown to remain stable and efficient for material coefficient contrasts up to 106, thanks in part to the use of geometric multigrid. A test of accuracy when adaptive mesh refinement capabilities are utilized is also performed. An example problem relevant to nuclear reactor core simulation is presented, demonstrating the ability of the method to solve problems with realistic physical parameters.

  14. Cartesian Diver

    NSDL National Science Digital Library

    2001-06-08

    This activity has students create a Cartesian diver, which will act in some ways like a submarine. Students will adjust the amount of air and water in an inverted test tube (the "diver") so that it at first barely floats in a water-filled bottle. Then, they will squeeze the closed bottle to create higher water pressure, causing the diver to sink. Releasing the bottle allows the diver to float again. Written instructions, a list of materials, and illustrations are included.

  15. A generalized finite-difference (GFD) ALE scheme for incompressible flows around moving solid bodies on hybrid meshfree Cartesian grids

    NASA Astrophysics Data System (ADS)

    Chew, C. S.; Yeo, K. S.; Shu, C.

    2006-11-01

    A scheme using the mesh-free generalized finite differencing (GFD) on flows past moving bodies is proposed. The aim is to devise a method to simulate flow past an immersed moving body that avoids the intensive remeshing of the computational domain and minimizes data interpolation associated with the established computational fluid methodologies; as such procedures are time consuming and are a significant source of error in flow simulation. In the present scheme, the moving body is embedded and enveloped by a cloud of mesh-free nodes, which convects with the motion of the body against a background of Cartesian nodes. The generalized finite-difference (GFD) method with weighted least squares (WLS) approximation is used to discretize the two-dimensional viscous incompressible Navier-Stokes equations at the mesh-free nodes, while standard finite-difference approximations are applied elsewhere. The convecting motion of the mesh-free nodes is treated by the Arbitrary Lagrangian-Eulerian (ALE) formulation of the flow equations, which are solved by a second-order Crank-Nicolson based projection method. The proposed numerical scheme was tested on a number of problems including the decaying-vortex flow, external flows past moving bodies and body-driven flows in enclosures.

  16. Opening Remarks by George W. Arnold, National Coordinator for Smart Grid Interoperability

    E-print Network

    Magee, Joseph W.

    Opening Remarks by George W. Arnold, National Coordinator for Smart Grid Interoperability Conference on Smart Grid Interoperability Standards January 31, 2011 Introduction Chairman Wellinghoff the opportunity to escribe NIST's and our partners efforts to develop standards for an interoperable d smart grid

  17. Coordination of the Smart Grid and Distributed Data Centers: A Nested Game-Based Optimization Framework

    E-print Network

    Pedram, Massoud

    Coordination of the Smart Grid and Distributed Data Centers: A Nested Game-Based Optimization pricing policies in the recently proposed smart grid technology can incentivize the cloud computing. On the other hand, distributed data centers also provide opportunities to help the smart grid to improve load

  18. A three-dimensional sharp interface Cartesian grid method for solving high speed multi-material impact, penetration and fragmentation problems

    NASA Astrophysics Data System (ADS)

    Kapahi, A.; Sambasivan, S.; Udaykumar, H. S.

    2013-05-01

    This work presents a three-dimensional, Eulerian, sharp interface, Cartesian grid technique for simulating the response of elasto-plastic solid materials to hypervelocity impact, shocks and detonations. The mass, momentum and energy equations are solved along with evolution equations for deviatoric stress and plastic strain using a third-order finite difference scheme. Material deformation occurs with accompanying nonlinear stress wave propagation; in the Eulerian framework the boundaries of the deforming material are tracked in a sharp fashion using level-sets and the conditions on the immersed boundaries are applied by suitable modifications of a ghost fluid approach. The dilatational response of the material is modeled using the Mie-Gruneisen equation of state and the Johnson-Cook model is employed to characterize the material response due to rate-dependent plastic deformation. Details are provided on the treatment of the deviatoric stress ghost state so that physically correct boundary conditions can be applied at the material interfaces. An efficient parallel algorithm is used to handle computationally intensive three-dimensional problems. The results demonstrate the ability of the method to simulate high-speed impact, penetration and fragmentation phenomena in three dimensions.

  19. 78 FR 7464 - Large Scale Networking (LSN)-Middleware And Grid Interagency Coordination (MAGIC) Team

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-01

    ...sharing among Federal agencies and non-Federal participants with interests and responsibility for middleware, Grid, and cloud projects. The MAGIC Team reports to the Large Scale Networking (LSN) Coordinating Group (CG). Public Comments: The...

  20. 77 FR 58416 - Large Scale Networking (LSN); Middleware and Grid Interagency Coordination (MAGIC) Team

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-20

    ...sharing among Federal agencies and non-Federal participants with interests and responsibility for middleware, Grid, and cloud projects. The MAGIC Team reports to the Large Scale Networking (LSN) Coordinating Group (CG). Public Comments: The...

  1. 78 FR 70076 - Large Scale Networking (LSN)-Middleware and Grid Interagency Coordination (MAGIC) Team

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ...sharing among Federal agencies and non-Federal participants with interests and responsibility for middleware, Grid, and cloud projects. The MAGIC Team reports to the Large Scale Networking (LSN) Coordinating Group (CG). Public Comments: The...

  2. Coordinated Variable Structure Switching Attacks for Smart Grid

    E-print Network

    Liu, Shan

    2013-02-11

    -physical aspects of a smart grid and determine the existence of the vulnerability and construct the destabilizing switching attack sequence. We illustrate the utility of the attack approach assess its impact on the different power system test cases including...

  3. Coordinating User and Device Behavior in Wireless Grids

    Microsoft Academic Search

    Lee W. Mcknight; William Lehr; James Howison

    Abstract The evolution of computing has lead to networks which are characterized by de- centralization and decreasing institutional control over resources. Wireless Grids, mobile ad-hoc resource sharing networks, are challenging environments in which users strategic behaviors are crucial to system performance. We review the mech- anisms employed to regulate strategic behavior online—technical, social, legal and economic—and discuss trends in their

  4. A new vertical coordinate system for a 3D unstructured-grid model

    NASA Astrophysics Data System (ADS)

    Zhang, Yinglong J.; Ateljevich, Eli; Yu, Hao-Cheng; Wu, Chin H.; Yu, Jason C. S.

    2015-01-01

    We present a new vertical coordinate system for cross-scale applications. Dubbed LSC2 (Localized Sigma Coordinates with Shaved Cell), the new system allows each node of the grid to have its own vertical grid, while still maintaining reasonable smoothness across horizontal and vertical dimensions. Furthermore, the staircase created by the mismatch of vertical levels at adjacent nodes is eliminated with a simple shaved-cell like approach using the concept of degenerate prisms. The new system is demonstrated to have the benefits of both terrain-following and Z-coordinate systems, while minimizing their adverse effects. We implement LSC2 in a 3D unstructured-grid model (SELFE) and demonstrate its superior performance with test cases on lake and ocean stratification.

  5. A hierarchically coordinated operation framework for optimally integrating PHEVs into power grids

    Microsoft Academic Search

    Yong Fu; Lei Wu; Zuyi Li

    2011-01-01

    This paper explores the impacts of high-level vehicle- to-grid (V2G) enabled plug-in hybrid vehicle (PHEV) penetration on power grids and proposes a novel hierarchically coordinated operation framework which will facilitate independent system operators (ISOs), distribution system operators, and individual households to effectively integrate V2G enabled PHEVs into existing transmission, distribution and home area networks, respectively. Accordingly, PHEVs can operate as

  6. Functions of a local controller to coordinate distributed resources in a smart grid

    Microsoft Academic Search

    Angela Chuang; Mark McGranaghan

    2008-01-01

    This paper describes requirements for an intelligent local controller for smart grids. The controller manages the operation of a portion of the power system to achieve customer-configured preferences for reliability and power quality through the combined use of local generation and storage sources, responsive load, power conditioning, and standby electric service from the supply system. The controller coordinates the set

  7. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the mirror is slightly tilted. Hence, one can determine the amount and direction of tilt from the coordinates of the target image on the viewing plane.

  8. GRID3C: Computer program for generation of C type multilevel, three dimensional and boundary conforming periodic grids

    NASA Technical Reports Server (NTRS)

    Dulikravich, D. S.

    1982-01-01

    A fast computer program, GRID3C, was developed for accurately generating periodic, boundary conforming, three dimensional, consecutively refined computational grids applicable to realistic axial turbomachinery geometries. The method is based on using two functions to generate two dimensional grids on a number of coaxial axisymmetric surfaces positioned between the centerbody and the outer radial boundary. These boundary fitted grids are of the C type and are characterized by quasi-orthogonality and geometric periodicity. The built in nonorthogonal coordinate stretchings and shearings cause the grid clustering in the regions of interest. The stretching parameters are part of the input to GRID3C. In its present version GRID3C can generate and store a maximum of four consecutively refined three dimensional grids. The output grid coordinates can be calculated either in the Cartesian or in the cylindrical coordinate system.

  9. An Adaptive Grid, Implicit Code for Spherically Symmetric, General Relativistic Hydrodynamics in Comoving Coordinates

    NASA Astrophysics Data System (ADS)

    Liebendörfer, Matthias; Rosswog, Stephan; Thielemann, Friedrich-Karl

    2002-07-01

    We describe an implicit general relativistic hydrodynamics code. The evolution equations are formulated in comoving coordinates. A conservative finite differencing of the Einstein equations is outlined, and artificial viscosity and numerical diffusion are discussed. The time integration is performed with AGILE, an implicit solver for stiff algebrodifferential equations on a dynamical adaptive grid. We extend the adaptive grid technique, known from nonrelativistic hydrodynamics, to the general relativistic application and identify it with the concept of shift vectors in a 3+1 decomposition. The adaptive grid minimizes the number of required computational zones without compromising the resolution in physically important regions. Thus, the computational effort is greatly reduced when the zones are subject to computationally expensive additional processes, such as Boltzmann radiation transport or a nuclear reaction network. We present accurate results in the standard tests for supernova simulations: Sedov's point-blast explosion, the nonrelativistic and relativistic shock tube, the Oppenheimer-Snyder dust collapse, and homologous collapse.

  10. Quality of the Computational Grids in the Orthogonal Curvilinear Terrain-Following Coordinate and its Computational Stability

    NASA Astrophysics Data System (ADS)

    Li, J.; Li, Y.; Wang, B.

    2014-12-01

    The orthogonal curvilinear terrain-following coordinate (OS-coordinate) proposed by Li et al. (2014) can create the orthogonal and terrain-following computational grids in the vertical, therefore reducing the advection errors compared with the corresponding non-orthogonal terrain-following grids according to the 2-D idealized Schär-type experiments. However, the orthogonal grid-lines have dramatic convergence and divergence above the steep terrain which restricts the time step and increases the numerical errors as pointed out by Li et al. (2014). In this study, we first investigate the quality of these orthogonal terrain-following grids in terms of the skewness, smoothness and aspect ratio, and their effects on reducing the advection errors. And then we design a hyperbolic rotation parameter b for the OS-coordinate instead of the power b used by Li et al. (2014) to create the new computational grids which have less convergence and divergence near the steep terrain. Finally, we use the OS-coordinate with the hyperbolic b to implement the Schär-type experiments as in Li et al. (2014) and then analyze the computational stability and the numerical accuracy relative to the OS-coordinate with the power b. The experimental results show that the hyperbolic b can control the distance of the neighbour grid-lines better than the power b, therefore alleviating the restriction of the time step in the OS-coordinate and also improving the performance of the OS-coordinate in reducing the advection errors.

  11. How do spatial learning and memory occur in the brain? Coordinated learning of entorhinal grid cells and hippocampal place cells

    E-print Network

    Spence, Harlan Ernest

    learning; spatial memory; grid cells; place cells; entorhinal cortex; hippocampus; learning; self of receptive fields are learned because each of the self-organizing maps amplifies and learns to categorize1 How do spatial learning and memory occur in the brain? Coordinated learning of entorhinal grid

  12. More IMPATIENT: A Gridding-Accelerated Toeplitz-based Strategy for Non-Cartesian High-Resolution 3D MRI on GPUs

    PubMed Central

    Gai, Jiading; Obeid, Nady; Holtrop, Joseph L.; Wu, Xiao-Long; Lam, Fan; Fu, Maojing; Haldar, Justin P.; Hwu, Wen-mei W.; Liang, Zhi-Pei; Sutton, Bradley P.

    2013-01-01

    Several recent methods have been proposed to obtain significant speed-ups in MRI image reconstruction by leveraging the computational power of GPUs. Previously, we implemented a GPU-based image reconstruction technique called the Illinois Massively Parallel Acquisition Toolkit for Image reconstruction with ENhanced Throughput in MRI (IMPATIENT MRI) for reconstructing data collected along arbitrary 3D trajectories. In this paper, we improve IMPATIENT by removing computational bottlenecks by using a gridding approach to accelerate the computation of various data structures needed by the previous routine. Further, we enhance the routine with capabilities for off-resonance correction and multi-sensor parallel imaging reconstruction. Through implementation of optimized gridding into our iterative reconstruction scheme, speed-ups of more than a factor of 200 are provided in the improved GPU implementation compared to the previous accelerated GPU code. PMID:23682203

  13. General strong conservation formulation of Navier-Stokes equations in nonorthogonal curvilinear coordinates

    Microsoft Academic Search

    H. Q. Yang; Sami D. Habchi; Andrzej J. Przekwas

    1994-01-01

    The selection of primary dependent variables for the solution of Navier-Stokes equations in the curvilinear body-fitted coordinates is still an unsettled issue. Reported formulations with primitive variables involve contravariant velocity components, Cartesian components, and velocity projections, also known as resolutes. Most of the formulations result in a weak conservation form of the momentum equations which contain grid line curvature- and

  14. The soft grid

    E-print Network

    Kardasis, Ari (Ari David)

    2011-01-01

    The grid in architecture is a systematic organization of space. The means that architects use to organize space are, almost by definition, rigid and totalizing. The Cartesian grid, which will serve as the antagonist of the ...

  15. Cartesian Genetic Programming

    Microsoft Academic Search

    Julian F. Miller; Peter Thomson

    2000-01-01

    This paper presents a new form of Genetic Programming called Cartesian Genetic Programming in which a program is represented as an in- dexed graph. The graph is encoded in the form of a linear string of integers. The inputs or terminal set and nod e outputs are numbered sequentially. The node functions are a lso separately nu mbered. The genotype

  16. A solution-adaptive mesh algorithm for dynamic/static refinement of two and three dimensional grids

    NASA Technical Reports Server (NTRS)

    Benson, Rusty A.; Mcrae, D. S.

    1991-01-01

    An adaptive grid algorithm has been developed in two and three dimensions that can be used dynamically with a solver or as part of a grid refinement process. The algorithm employs a transformation from the Cartesian coordinate system to a general coordinate space, which is defined as a parallelepiped in three dimensions. A weighting function, independent for each coordinate direction, is developed that will provide the desired refinement criteria in regions of high solution gradient. The adaptation is performed in the general coordinate space and the new grid locations are returned to the Cartesian space via a simple, one-step inverse mapping. The algorithm for relocation of the mesh points in the parametric space is based on the center of mass for distributed weights. Dynamic solution-adaptive results are presented for laminar flows in two and three dimensions.

  17. IEEE TRANSACTIONS ON SMART GRID, VOL. 5, NO. 3, MAY 2014 1183 A Coordinated Multi-Switch Attack for Cascading

    E-print Network

    Kundur, Deepa

    components using variable structure system theory. Here, an opponent is able to remotely control multiple-bus test system. Index Terms--Coordinated multi-switch attacks, cyber-physical system security, sliding mode theory, smart grid attacks, variable structure system modeling. I. INTRODUCTION I T IS WELL

  18. Determining the role of geospatial technologies for stigmergic coordination in situation management: Implications of the wireless grid

    Microsoft Academic Search

    Janet Marsden

    2011-01-01

    Abs tract—Geospatial technologies in conjunction with wireless grids will offer a context for locating and coordinating team activities in such a way that the nature of each team member's effort may be known and understood by other members. This constructed group knowledge enables teams to respond to unforeseen and emergent contingencies and act in concert through the active interpretation of

  19. Numerical grid generation; Proceedings of the Symposium on Numerical Generation of Curvilinear Coordinate Systems and Their Use in the Numerical Solution of Partial Differential Equations, Nashville, TN, April 13-16, 1982

    NASA Technical Reports Server (NTRS)

    Thompson, J. F. (editor)

    1982-01-01

    General curvilinear coordinate systems are considered along with the error induced by coordinate systems, basic differential models for coordinate generation, elliptic grid generation, conformal grid generation, algebraic grid generation, orthogonal grid generation, patched coordinate systems, and solid mechanics applications of boundary fitted coordinate systems. Attention is given to coordinate system control and adaptive meshes, the application of body conforming curvilinear grids for finite difference solution of external flow, the use of solution adaptive grids in solving partial differential equations, adaptive gridding for finite difference solutions to heat and mass transfer problems, and the application of curvilinear coordinate generation techniques to the computation of internal flows. Other topics explored are related to the solution of nonlinear water wave problems using boundary-fitted coordinate systems, the numerical modeling of estuarine hydrodynamics on a boundary-fitted coordinate system, and conformal grid generation for multielement airfoils.

  20. Rapid Structured Volume Grid Smoothing and Adaption Technique

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.

    2004-01-01

    A rapid, structured volume grid smoothing and adaption technique, based on signal processing methods, was developed and applied to the Shuttle Orbiter at hypervelocity flight conditions in support of the Columbia Accident Investigation. Because of the fast pace of the investigation, computational aerothermodynamicists, applying hypersonic viscous flow solving computational fluid dynamic (CFD) codes, refined and enhanced a grid for an undamaged baseline vehicle to assess a variety of damage scenarios. Of the many methods available to modify a structured grid, most are time-consuming and require significant user interaction. By casting the grid data into different coordinate systems, specifically two computational coordinates with arclength as the third coordinate, signal processing methods are used for filtering the data [Taubin, CG v/29 1995]. Using a reverse transformation, the processed data are used to smooth the Cartesian coordinates of the structured grids. By coupling the signal processing method with existing grid operations within the Volume Grid Manipulator tool, problems related to grid smoothing are solved efficiently and with minimal user interaction. Examples of these smoothing operations are illustrated for reduction in grid stretching and volume grid adaptation. In each of these examples, other techniques existed at the time of the Columbia accident, but the incorporation of signal processing techniques reduced the time to perform the corrections by nearly 60%. This reduction in time to perform the corrections therefore enabled the assessment of approximately twice the number of damage scenarios than previously possible during the allocated investigation time.

  1. A simple second order cartesian scheme for compressible Euler flows

    E-print Network

    Paris-Sud XI, Université de

    A simple second order cartesian scheme for compressible Euler flows Yannick Gorsse1 , Angelo Iollo1 Turin, Italy. Abstract We present a finite-volume scheme for compressible Euler flows where the grid to this class, and was mainly developed for compressible flows, see for example [31], [42], [25], [11], [18

  2. Game Coloring the Cartesian Product

    E-print Network

    Zhu, Xuding

    Game Coloring the Cartesian Product of Graphs Xuding Zhu1,2 1DEPARTMENT OF APPLIED MATHEMATICS to each vertex a set of n degree 1 neighbors. If G has game coloring number m and G has acyclic chromatic number k, then the Cartesian product G G has game chromatic number at most k(k+m - 1). As a consequence

  3. Coordination

    NSDL National Science Digital Library

    Olivia Worland (Purdue University; Biological Sciences)

    2008-06-06

    Coordination is an organized working together of muscles and groups of muscles aimed at bringing about a purposeful movement such as walking or standing. Coordination involves timing and concentration.

  4. Cartesian stiffness control of the JPL\\/Stanford\\/Salisbury hand

    Microsoft Academic Search

    G. P. Starr

    1988-01-01

    To be useful as a dexterous end effector in assembly operations, a multifingered hand must be position-controlled to allow preshaping, and force-controlled to apply and regulate grasp forces. The author describes an implementation of stiffness control on the Salisbury hand, from tendon tension control to coordinated Cartesian object stiffness control. Substantial joint friction effects were observed which were predicted well

  5. Software for Automated Generation of Cartesian Meshes

    NASA Technical Reports Server (NTRS)

    Aftosmis, Michael J.; Melton, John E.; Berger, Marshal J.

    2006-01-01

    Cart3D is a collection of computer programs for generating Cartesian meshes [for computational fluid dynamics (CFD) and other applications] in volumes bounded by solid objects. Aspects of Cart3D at earlier stages of development were reported in "Robust and Efficient Generation of Cartesian Meshes for CFD" (ARC-14275), NASA Tech Briefs, Vol. 23, No. 8 (August 1999), page 30. The geometric input to Cart3D comprises surface triangulations like those commonly generated by computer-aided-design programs. Complexly shaped objects can be represented as assemblies of simpler ones. Cart3D deletes all portions of such an assembled object that are not on the exterior surface. Intersections between components are preserved in the resulting triangulation. A tie-breaking routine unambiguously resolves geometric degeneracies. Then taking the intersected surface triangulation as input, the volume mesh is generated through division of cells of an initially coarse hexahedral grid. Cells are subdivided to refine the grid in regions of increased surface curvature and/or increased flow gradients. Cells that become split into multiple unconnected regions by thin pieces of surface are identified.

  6. An Adaptively-Refined, Cartesian, Cell-Based Scheme for the Euler and Navier-Stokes Equations

    Microsoft Academic Search

    William John Coirier

    1994-01-01

    An Adaptively-Refined, Cartesian, Cell-Based Schemefor the Euler and Navier-Stokes EquationsbyWilliam John CoirierChairperson: Kenneth G. PowellA Cartesian, cell-based scheme for solving the Euler and Navier-Stokes equations in twodimensions is developed and tested. Grids about geometrically complicated bodies are generatedautomatically, by recursive subdivision of a single Cartesian cell encompassing the entire flowdomain. Where the resulting cells intersect bodies, polygonal "cut"...

  7. A study of the effects of grid non-orthogonality on the solution of shallow water equations in boundary-fitted coordinate systems

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, S.; Spaulding, Malcolm L.

    2003-01-01

    In the present study, an existing two-dimensional boundary-fitted model [J. Hydraul. Eng.-ASCE 122 (9) (1996) 512] is used to study the effect of grid non-orthogonality on the solution of shallow water equations using boundary-fitted grids. The linearized two-dimensional shallow water equations are expressed in terms of the grid angle and aspect ratio. The truncation errors of the finite difference approximations used in the solution of the governing equations are shown to be dependent on the grid angle and the aspect ratio. The coefficient of the truncation error was shown to increase, with the decrease in the grid angle. The RMS errors in model predicted surface elevations and velocities for the case of seiching in a rectangular basin are found to increase gradually, as the grid resolution decreases from 174 to 80 gridpoints per wavelength or as the grid angle decreases from 90° to 50° and increases rather sharply for a grid angle of 30° at grid resolutions less than 80 gridpoints per wavelength. The model predicted surface elevations for the case of tidal forcing in a rectangular basin are found to be insensitive to the grid angle at grid resolutions higher than 600 gridpoints per wavelength. The RMS error in the model predicted velocities is found to increase gradually as the grid angle decreases from 90° to 30° or as the grid resolution decreases from 1400 gridpoints per wavelength to 400 gridpoints per wavelength and increases sharply as the grid resolution decreases from 400 to 150 gridpoints per wavelength. Two-dimensional depth averaged hydrodynamic modeling of tidal circulation in Narragansett Bay, using three different boundary-fitted grids showed that the model predicted surface elevations are insensitive to the grid angle at grid resolutions as low as 200 gridpoints per wavelength. However, the model predicted velocities were found to increase as the grid resolution decreases from 600 to 200 gridpoints per wavelength. We conclude from this study that grid angle and grid resolution affects the accuracy of the model predicted currents and the numerical dispersion increases with the decrease in grid angle or grid resolution and these are in agreement with that reached by Sankaranarayanan and Spaulding [Dispersion and Stability Analyses of Shallow Water Equations in Boundary-fitted Coordinates, Department of Ocean Engineering, University of Rhode Island, 2001, p. 33] through a Fourier analysis of the discretized equations in boundary-fitted coordinates.

  8. Coordinates

    NSDL National Science Digital Library

    In this activity, developed by the Lane Community College Geo-STAC programâ??, students "understand geographic location (absolute and relative) using an interactive Web-based GIS map." The lesson helps review basic concepts of coordinate geometry as they move about the world identifying coordinate relationships and important reference lines. On the site, visitors will find a link to the student activity and teaching guide, as well as link to the web-based GIS map. This is an excellent activity for high school or early undergraduate students for hands-on work with GIS and coordinate systems.

  9. A Cartesian embedded boundary method for hyperbolic conservation laws

    SciTech Connect

    Sjogreen, B; Petersson, N A

    2006-12-04

    The authors develop an embedded boundary finite difference technique for solving the compressible two- or three-dimensional Euler equations in complex geometries on a Cartesian grid. The method is second order accurate with an explicit time step determined by the grid size away from the boundary. Slope limiters are used on the embedded boundary to avoid non-physical oscillations near shock waves. They show computed examples of supersonic flow past a cylinder and compare with results computed on a body fitted grid. Furthermore, they discuss the implementation of the method for thin geometries, and show computed examples of transonic flow past an airfoil.

  10. NPSS on NASA's Information Power Grid: Using CORBA and Globus to Coordinate Multidisciplinary Aeroscience Applications

    NASA Technical Reports Server (NTRS)

    Lopez, Isaac; Follen, Gregory J.; Gutierrez, Richard; Foster, Ian; Ginsburg, Brian; Larsson, Olle; Martin, Stuart; Tuecke, Steven; Woodford, David

    2000-01-01

    This paper describes a project to evaluate the feasibility of combining Grid and Numerical Propulsion System Simulation (NPSS) technologies, with a view to leveraging the numerous advantages of commodity technologies in a high-performance Grid environment. A team from the NASA Glenn Research Center and Argonne National Laboratory has been studying three problems: a desktop-controlled parameter study using Excel (Microsoft Corporation); a multicomponent application using ADPAC, NPSS, and a controller program-, and an aviation safety application running about 100 jobs in near real time. The team has successfully demonstrated (1) a Common-Object- Request-Broker-Architecture- (CORBA-) to-Globus resource manager gateway that allows CORBA remote procedure calls to be used to control the submission and execution of programs on workstations and massively parallel computers, (2) a gateway from the CORBA Trader service to the Grid information service, and (3) a preliminary integration of CORBA and Grid security mechanisms. We have applied these technologies to two applications related to NPSS, namely a parameter study and a multicomponent simulation.

  11. Coordinating the Global Information Grid Initiative with the NG9-1-1 Initiative

    SciTech Connect

    Michael Schmitt

    2008-05-01

    As the Department of Defense develops the Global Information Grid, the Department of Transportation develops the Next Generation 9-1-1 system. Close examinations of these initiatives show that the two are similar in architectures, applications, and communications interoperability. These similarities are extracted from the lowest user level to the highest commander rank that will be involved in each network. Once the similarities are brought into perspective, efforts should be made to collaborate between the two departments.

  12. Coordinating Energy Based Business Models and Customer Empowerment in Future Smart Grids

    Microsoft Academic Search

    Shahid Hussain; Rune Gustavsson

    \\u000a Future sustainable energy systems are in focus of several national and international R&D programs. The transition from today’s\\u000a tariff-based energy systems towards future sustainable energy markets has to be supported by addressing and solving a range\\u000a of challenges. Among the identified barriers are doubts of user acceptance of future Smart Grids due to lack of experiences,\\u000a opportunities and possibilities: hence

  13. Two-Liquid Cartesian Diver

    ERIC Educational Resources Information Center

    Planinsic, G.; Kos, M.; Jerman, R.

    2004-01-01

    It is quite easy to make a version of the well known Cartesian diver experiment that uses two immiscible liquids. This allows students to test their knowledge of density and pressure in explaining the diver's behaviour. Construction details are presented here together with a mathematical model to explain the observations.

  14. A NEW THREE-DIMENSIONAL SOLAR WIND MODEL IN SPHERICAL COORDINATES WITH A SIX-COMPONENT GRID

    SciTech Connect

    Feng, Xueshang; Zhang, Man; Zhou, Yufen, E-mail: fengx@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-09-01

    In this paper, we introduce a new three-dimensional magnetohydrodynamics numerical model to simulate the steady state ambient solar wind from the solar surface to 215 R {sub s} or beyond, and the model adopts a splitting finite-volume scheme based on a six-component grid system in spherical coordinates. By splitting the magnetohydrodynamics equations into a fluid part and a magnetic part, a finite volume method can be used for the fluid part and a constrained-transport method able to maintain the divergence-free constraint on the magnetic field can be used for the magnetic induction part. This new second-order model in space and time is validated when modeling the large-scale structure of the solar wind. The numerical results for Carrington rotation 2064 show its ability to produce structured solar wind in agreement with observations.

  15. SAR imagery in non-Cartesian geometries

    NASA Astrophysics Data System (ADS)

    Dendal, Didier

    1995-11-01

    The subject of the reported work is the improvement of geometrical models for a SAR scanning in pushbroom, spotlight, scansar or bistatic imaging modes. This research has been motivated by the planetary cornerstone mission of ESA's long term program for European Space Science ('rendezvous' with a comet, and fly-bys of asteroids). In this specific context, the synthetic aperture radar is destined for an important role, but the rules and standard backgrounds of the Cartesian geometry are no longer justified. Several new techniques are proposed to handle with an optimal precision the data relative to celestial bodies with a complex geometry (coherent and non-coherent imagery). On the basis of a mathematical rigor (singleness of solutions, convergence of processes, biunivocity of transformations and generalizations), a lot of scenarios are discussed with key relations established (plane and spherical models, bodies with a symmetry of revolution and general bodies, specific sensor(s) trajectories as fly-bys or flight into orbit with the possibility of an approaching probe). The four methods developed are the tomographic analogy of radar principles (only known, previously, in the usual case of a straight line flight at constant altitude over a plane surface) and Hilbertian techniques for a direct adaptation to the scanned surface geometry, an automated autofocusing which enhances the contrast resulting from a Cartesian reconstruction and the coordinates transformation where the real space is converted into a fictitious space where Cartesian algorithms are fully rigorous. Beyond the fact that an interpolation step is often unavoidable, the major conclusion of the research is that all the prospected techniques are complementary and that the choice between the methods has to be made according to geometry, objectives and time requirements (reconstruction on board or not). In particular, coordinates transformation techniques are worthy of commendation in the case of plane (wavefront curvature balancing) or spherical models in a monostatic situation. Autofocusing methods (judicious ponderation between the usual reconstruction and a reconstruction of the derivative of the key expression of the mathematical formalism with regard to one of its parameters) has proven its validity in the hilly regions east of Belgium with low differences in contrast, while the Hilbertian principles are general methods without any restriction on the paths of the probes, the geometry of the celestial body, the modulation scheme and antennae radiation pattern. On the other hand, the tomographic analogy can be applied in all situations where a correct model of the body relief is available, but there are some approximations in the formalism (no antenna pattern modeling, no balancing of the range migration).

  16. Simple Coordinates Game

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students enter in coordinates then the applet places a house at that location, or the location is decided first then the student must enter in the coordinates of the house. This activity allows students to practice with coordinates and ordered pairs in the Cartesian coordinate system. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  17. Cartesian control of redundant robots

    NASA Technical Reports Server (NTRS)

    Colbaugh, R.; Glass, K.

    1989-01-01

    A Cartesian-space position/force controller is presented for redundant robots. The proposed control structure partitions the control problem into a nonredundant position/force trajectory tracking problem and a redundant mapping problem between Cartesian control input F is a set member of the set R(sup m) and robot actuator torque T is a set member of the set R(sup n) (for redundant robots, m is less than n). The underdetermined nature of the F yields T map is exploited so that the robot redundancy is utilized to improve the dynamic response of the robot. This dynamically optimal F yields T map is implemented locally (in time) so that it is computationally efficient for on-line control; however, it is shown that the map possesses globally optimal characteristics. Additionally, it is demonstrated that the dynamically optimal F yields T map can be modified so that the robot redundancy is used to simultaneously improve the dynamic response and realize any specified kinematic performance objective (e.g., manipulability maximization or obstacle avoidance). Computer simulation results are given for a four degree of freedom planar redundant robot under Cartesian control, and demonstrate that position/force trajectory tracking and effective redundancy utilization can be achieved simultaneously with the proposed controller.

  18. Non-Cartesian parallel imaging reconstruction.

    PubMed

    Wright, Katherine L; Hamilton, Jesse I; Griswold, Mark A; Gulani, Vikas; Seiberlich, Nicole

    2014-11-01

    Non-Cartesian parallel imaging has played an important role in reducing data acquisition time in MRI. The use of non-Cartesian trajectories can enable more efficient coverage of k-space, which can be leveraged to reduce scan times. These trajectories can be undersampled to achieve even faster scan times, but the resulting images may contain aliasing artifacts. Just as Cartesian parallel imaging can be used to reconstruct images from undersampled Cartesian data, non-Cartesian parallel imaging methods can mitigate aliasing artifacts by using additional spatial encoding information in the form of the nonhomogeneous sensitivities of multi-coil phased arrays. This review will begin with an overview of non-Cartesian k-space trajectories and their sampling properties, followed by an in-depth discussion of several selected non-Cartesian parallel imaging algorithms. Three representative non-Cartesian parallel imaging methods will be described, including Conjugate Gradient SENSE (CG SENSE), non-Cartesian generalized autocalibrating partially parallel acquisition (GRAPPA), and Iterative Self-Consistent Parallel Imaging Reconstruction (SPIRiT). After a discussion of these three techniques, several potential promising clinical applications of non-Cartesian parallel imaging will be covered. PMID:24408499

  19. Improved genetic algorithm for the protein folding problem by use of a Cartesian combination operator.

    PubMed Central

    Rabow, A. A.; Scheraga, H. A.

    1996-01-01

    We have devised a Cartesian combination operator and coding scheme for improving the performance of genetic algorithms applied to the protein folding problem. The genetic coding consists of the C alpha Cartesian coordinates of the protein chain. The recombination of the genes of the parents is accomplished by: (1) a rigid superposition of one parent chain on the other, to make the relation of Cartesian coordinates meaningful, then, (2) the chains of the children are formed through a linear combination of the coordinates of their parents. The children produced with this Cartesian combination operator scheme have similar topology and retain the long-range contacts of their parents. The new scheme is significantly more efficient than the standard genetic algorithm methods for locating low-energy conformations of proteins. The considerable superiority of genetic algorithms over Monte Carlo optimization methods is also demonstrated. We have also devised a new dynamic programming lattice fitting procedure for use with the Cartesian combination operator method. The procedure finds excellent fits of real-space chains to the lattice while satisfying bond-length, bond-angle, and overlap constraints. PMID:8880904

  20. A generalized coordinate ocean model and a comparison of the bottom boundary layer dynamics in terrain-following and in z-level grids

    Microsoft Academic Search

    Tal Ezer; George L. Mellor

    2004-01-01

    Sensitivity studies with a new generalized coordinate ocean model are performed in order to compare the behavior of bottom boundary layers (BBLs) when terrain-following (sigma or combined sigma and z-level) or z-level vertical grids are used, but most other numerical aspects remain unchanged. The model uses a second-order turbulence closure scheme that provides surface and BBL mixing and results in

  1. Discrepancy of Cartesian Products of Arithmetic Progressions

    E-print Network

    Srivastav, Anand

    Discrepancy of Cartesian Products of Arithmetic Progressions Benjamin Doerr # + Anand Srivastav discrepancy of the hypergraph H of cartesian products of d arithmetic progressions in the [N ] d --lattice ([N ] = {0, 1, . . . , N - 1}). The study of such higher dimensional arithmetic progressions is motivated

  2. Measuring the black hole spin direction in 3D Cartesian numerical relativity simulations

    NASA Astrophysics Data System (ADS)

    Mewes, Vassilios; Font, José A.; Montero, Pedro J.

    2015-06-01

    We show that the so-called flat-space rotational Killing vector method for measuring the Cartesian components of a black hole spin can be derived from the surface integral of Weinberg's pseudotensor over the apparent horizon surface when using Gaussian normal coordinates in the integration. Moreover, the integration of the pseudotensor in this gauge yields the Komar angular momentum integral in a foliation adapted to the axisymmetry of the spacetime. As a result, the method does not explicitly depend on the evolved lapse ? and shift ?i on the respective time slice, as they are fixed to Gaussian normal coordinates while leaving the coordinate labels of the spatial metric ?i j and the extrinsic curvature Ki j unchanged. Such gauge fixing endows the method with coordinate invariance, which is not present in integral expressions using Weinberg's pseudotensor, as they normally rely on the explicit use of Cartesian coordinates.

  3. Measuring the black hole spin direction in 3D Cartesian numerical relativity simulations

    E-print Network

    Mewes, Vassilios; Montero, Pedro J

    2015-01-01

    We show that the so-called flat-space rotational Killing vector method for measuring the Cartesian components of a black hole spin can be derived from the surface integral of Weinberg's pseudotensor over the apparent horizon surface when using Gaussian normal coordinates in the integration. Moreover, the integration of the pseudotensor in this gauge yields the Komar angular momentum integral in a foliation adapted to the axisymmetry of the spacetime. As a result, the method does not explicitly depend on the evolved lapse $\\alpha$ and shift $\\beta^i$ on the respective timeslice, as they are fixed to Gaussian normal coordinates, while leaving the coordinate labels of the spatial metric $\\gamma_{ij}$ and the extrinsic curvature $K_{ij}$ unchanged. Such gauge fixing endows the method with coordinate invariance, which is not present in integral expressions using Weinberg's pseudotensor, as they normally rely on the explicit use of Cartesian coordinates.

  4. Practical conversion from torsion space to Cartesian space for in silico protein synthesis

    Microsoft Academic Search

    Jerod Parsons; J. Bradley Holmes; J. Maurice Rojas; Jerry Tsai; Charlie E. M. Strauss

    2005-01-01

    Many applications require a method for translating a large list of bond angles and bond lengths to precise atomic Cartesian coordinates. This simple but computationally consuming task occurs ubiquitously in modeling proteins, DNA, and other polymers as well as in many other fields such as robotics. To find an optimal method, algorithms can be compared by a number of operations,

  5. An overlapping Yin-Yang grid method for global geomagnetic induction modeling

    NASA Astrophysics Data System (ADS)

    Weiss, C. J.

    2013-12-01

    Numerical modeling of whole-Earth electromagnetic response to space weather is an essential element for interpretation of ground-based and satellite-based magnetic field observations in terms of mantle conductivity, a physical property whose estimates offer powerful constraints on geodynamics and mantle evolution. Whereas staggered grid finite difference methods for computational electromagnetics are well-known for their efficiency in Cartesian geometries, mapping them to the sphere is problematic due to grid convergence near the poles. Alternate discretizations based on nested, triangulated spherical shells avoid the pole problem, but suffer from substantial computational overhead and a reduced-order polynomial accuracy. Presented here are results from a new approach to the global geomagnetic induction modeling problem, an approach first developed for massively parallel and global scale CFD calculations: the overlapping Yin-Yang grid. Based on the staggered grid scheme, the Yin-Yang grid takes a conformal mapping of the Cartesian grid onto a mid-latitude lat/lon grid spanning 270 degrees in longitude and +/- 45 degrees in latitude, thus preserving well-shaped and nearly uniform grid cells. Two such mappings are required to cover the sphere. The "Yin" grid is oriented in geographic coordinates, and its complement, the "Yang" grid is oriented with such that its North pole lies on the equator at 90 deg East. Hence, the sphere is covered with minimal overlap between the two grids and the polar regions are represented by the nearly-rectilinear cells of the Yang grid. The global induction problem is formulated here in the frequency domain as the solution to Maxwell's equations in terms of the Lorenz-gauged magnetic vector and electric scalar potentials over each of the overlapping grids, coupled through simple linear interpolation over their respective boundary elements. Computational efficiency of the method is maintained through recycling of finite difference and interpolation templates over each the grids, as well as the relatively simple coordinate transformation from one grid to the other. Ilustration of the overlapping Yin-Yang grid and color-coded Earth conductivity, with the reference crustal conductance map of Everett et al., (2003).

  6. Diverse assemblies of the (4,4) grid layers exemplified in Zn(II)/Co(II) coordination polymers with dual linear ligands

    SciTech Connect

    Liu, Guang-Zhen; Li, Xiao-Dong; Xin, Ling-Yun; Li, Xiao-Ling [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang, Henan 471022 (China); Wang, Li-Ya, E-mail: wlya@lynu.edu.cn [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang, Henan 471022 (China); College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang, Henan 473061 (China)

    2013-07-15

    Diverse (4,4) grid layers are exemplified in five two-dimensional coordination polymers with dual µ{sub 2}-bridged ligands, namely, ([Zn(cbaa)(bpp)]·H{sub 2}O){sub n} (1), [Zn{sub 2}(cbaa){sub 2}(bpy)]{sub n} (2), [Co{sub 2}(cbaa){sub 2}(bpp){sub 2}]{sub n} (3), [Co(cbaa)(bpp)]{sub n} (4), and [Co(bdaa)(bpp)(H{sub 2}O){sub 2}]{sub n} (5) (H{sub 2}cbaa=4-carboxybenzeneacetic acid, bpp=1,3-di(4-pyridyl)propane, bpy=4,4?-bipyridyl, and H{sub 2}bdaa=1,4-benzenediacrylic acid). For 1, two (4,4) grid layers with [ZnN{sub 2}O{sub 2}] tetrahedron as the node are held together by lattice water forming a H-bonding bilayer. Individual (4,4) grid layer in 2 is based on (Zn{sub 2}(OCO){sub 4}) paddlewheel unit as the node. Two (4,4) grid layers with (Co{sub 2}O(OCO){sub 2}) dimer as the node are covalently interconnected by organic ligands affording a thick bilayer of 3 with new framework topology. The different entanglements between two coincident (4,4) grid layers with [CoN{sub 2}O{sub 4}] octahedron as the node leads to two 2D?2D interpenetrated structures for 4 and 5. Furthermore, fluorescent properties of 1 and 2 as well as magnetic properties of 3 are investigated. - Graphical abstract: Diverse assemblies of the (4,4) grid layers with different network nodes forms five coordination polymers that are well characterized by IR, TGA, element analysis, fluorescent and magnetic measurement. - Highlights: • Diverse assemblies of the (4,4) grid layers with different structural units as the nodes. • A new topology type with the uninodal 6-connected net of (4{sup 12}.5{sup 2}.6) is found. • Intense fluorescence emissions with a rare blue-shift of 55 nm compared to free carboxylate ligand.

  7. Discrepancy of Cartesian Products of Arithmetic Progressions

    E-print Network

    Doerr, Benjamin

    Discrepancy of Cartesian Products of Arithmetic Progressions Benjamin Doerr #3; y Anand Srivastav: arithmetic progressions, discrepancy, harmonic analysis, locally compact abelian groups. Abstract We arithmetic progressions is motivated by a multi-dimensional version of van der Waerden's theorem, namely

  8. Structural Dynamics Model of a Cartesian Robot

    E-print Network

    Reynoso, Alfonso Garcia

    1985-10-01

    Methods are developed for predicting vibration response characteristics of systems which change configuration during operation. A cartesian robot, an example of such a position-dependent system, served as a test case ...

  9. Graphing and the Coordinate Plane

    NSDL National Science Digital Library

    2010-01-01

    This lesson is designed to introduce students to graphing coordinates and lines in the Cartesian coordinate plane. This lesson provides links to discussions and activities related to graphing as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

  10. Generalization of the hybrid monotone second-order finite difference scheme for gas dynamics equations to the case of unstructured 3D grid

    NASA Astrophysics Data System (ADS)

    Mingalev, V. S.; Mingalev, I. V.; Mingalev, O. V.; Oparin, A. M.; Orlov, K. G.

    2010-05-01

    A generalization of the explicit hybrid monotone second-order finite difference scheme for the use on unstructured 3D grids is proposed. In this scheme, the components of the momentum density in the Cartesian coordinates are used as the working variables; the scheme is conservative. Numerical results obtained using an implementation of the proposed solution procedure on an unstructured 3D grid in a spherical layer in the model of the global circulation of the Titan’s (a Saturn’s moon) atmosphere are presented.

  11. Enhanced Elliptic Grid Generation

    NASA Technical Reports Server (NTRS)

    Kaul, Upender K. (Editor)

    2007-01-01

    Method and system for generating an elliptic grid in generalized coordinates in two or three dimensions, where one or more decay parameters near a boundary segment of a grid are determined as part of the grid solution, rather than being prescribed initially by a user. The decay parameters may vary with one or more generalized coordinates and determine the rate(s) at which separation distances between adjacent grid lines change as one moves toward or away from a grid boundary segment.

  12. How Do Spatial Learning and Memory Occur in the Brain? Coordinated Learning of Entorhinal Grid Cells and Hippocampal Place Cells

    Microsoft Academic Search

    Praveen K. Pilly; Stephen Grossberg

    2012-01-01

    Spatial learning and memory are important for navigation and formation of episodic memories. The hippocampus and medial entorhinal cortex (MEC) are key brain areas for spatial learning and memory. Place cells in hippocampus fire whenever an animal is located in a specific region in the environment. Grid cells in the superficial layers of MEC provide inputs to place cells and

  13. How Do Spatial Learning and Memory Occur in the Brain? Coordinated Learning of Entorhinal Grid Cells and Hippocampal Place Cells

    Microsoft Academic Search

    Praveen K. Pilly; Stephen Grossberg

    Spatial learning and memory are important for navigation and formation of episodic memories. The hippocampus and medial entorhinal cortex (MEC) are key brain areas for spatial learning and memory. Place cells in hippocampus fire whenever an animal is located in a specific region in the environment. Grid cells in the superficial layers of MEC provide inputs to place cells and

  14. Maintain rigid structures in Verlet based Cartesian molecular dynamics simulations

    PubMed Central

    Tao, Peng; Wu, Xiongwu; Brooks, Bernard R.

    2012-01-01

    An algorithm is presented to maintain rigid structures in Verlet based Cartesian molecular dynamics (MD) simulations. After each unconstrained MD step, the coordinates of selected particles are corrected to maintain rigid structures through an iterative procedure of rotation matrix computation. This algorithm, named as SHAPE and implemented in CHARMM program suite, avoids the calculations of Lagrange multipliers, so that the complexity of computation does not increase with the number of particles in a rigid structure. The implementation of this algorithm does not require significant modification of propagation integrator, and can be plugged into any Cartesian based MD integration scheme. A unique feature of the SHAPE method is that it is interchangeable with SHAKE for any object that can be constrained as a rigid structure using multiple SHAKE constraints. Unlike SHAKE, the SHAPE method can be applied to large linear (with three or more centers) and planar (with four or more centers) rigid bodies. Numerical tests with four model systems including two proteins demonstrate that the accuracy and reliability of the SHAPE method are comparable to the SHAKE method, but with much more applicability and efficiency. PMID:23039588

  15. Solution-Adaptive Cartesian Cell Approach for Viscous and Inviscid Flows

    NASA Technical Reports Server (NTRS)

    Coirier, William J.; Powell, Kenneth G.

    1996-01-01

    A Cartesian cell-based approach for adaptively refined solutions of the Euler and Navier-Stokes equations in two dimensions is presented. Grids about geometrically complicated bodies are generated automatically, by the recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, polygonal cut cells are created using modified polygon-clipping algorithms. The grid is stored in a binary tree data structure that provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite volume formulation. The convective terms are upwinded: A linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The results of a study comparing the accuracy and positivity of two classes of cell-centered, viscous gradient reconstruction procedures is briefly summarized. Adaptively refined solutions of the Navier-Stokes equations are shown using the more robust of these gradient reconstruction procedures, where the results computed by the Cartesian approach are compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows.

  16. Iterative coordinate transformation procedure for one class of robots

    NASA Astrophysics Data System (ADS)

    Lumelsky, V. J.

    1984-06-01

    The processing of robot paths in Cartesian coordinates allows on-line path modification in light of data from conveyer, sensor, and other sources, which typically operate in Cartesian terms. Unfortunately, advanced robotic systems operate in terms of revolute and sliding joint geometries that are not easily translated into Cartesian equivalents. An iterative procedure has been developed for one class of articulated robots which produces an exact solution for the wrist tip position coordinates and an approximate solution for the wrist orientation coordinates. Attention is given to the procedure's convergence characteristics.

  17. MULTIPLE DRAFTS VERSUS THE CARTESIAN THEATER

    E-print Network

    Pylyshyn, Zenon

    VERSUS THE CARTESIAN THEATER 103 equations tell us to do is to examine the electromagnetic field There is no cell or group of cells in the brain of such anatomical or functional preeminence as to appear' of the particle, or else do we average the field (for the 'force') over all polnls at the surface? ... Perhaps we

  18. Affine connections for the Cartesian stiffness matrix

    Microsoft Academic Search

    Milos Zefran; Vijay Kumar

    1997-01-01

    We study the 6×6 Cartesian stiffness matrix. We show that the stiffness of a rigid body subjected to conservative forces and moments is described by a (0,2) tensor which is the Hessian of the potential function. The key observation of the paper is that since the Hessian depends on the choice of an affine connection in the task space, so

  19. Arbitrary order permanent Cartesian multipolar electrostatic interactions.

    PubMed

    Boateng, H A; Todorov, I T

    2015-01-21

    Recently, there has been a concerted effort to implement advanced classical potential energy surfaces by adding higher order multipoles to fixed point charge electrostatics in a bid to increase the accuracy of simulations of condensed phase systems. One major hurdle is the unwieldy nature of the expressions which in part has limited developers mostly to including only dipoles and quadrupoles. In this paper, we present a generalization of the Cartesian formulation of electrostatic multipolar interactions that enables the specification of an arbitrary order of multipoles. Specifically, we derive formulas for arbitrary order implementation of the particle mesh Ewald method and give a closed form formula for the stress tensor in the reciprocal space. In addition, we provide recurrence relations for common electrostatic potentials employed in molecular simulations, which allows for the generalization to arbitrary order and guarantees a computational cost that scales as O(p(3)) for Cartesian multipole interactions of order p. PMID:25612699

  20. Discrepancy of Cartesian Products of Arithmetic Progressions

    Microsoft Academic Search

    Benjamin Doerr; Anand Srivastav; Petra Wehr

    2004-01-01

    We determine the combinatorial discrepancy of the hypergraph H of cartesian products of d arithmetic progressions in the (N)d-lattice ((N )= {0, 1,...,N 1}). The study of such higher dimensional arithmetic progressions is motivated by a multi-dimensional version of van der Waerden's theorem, namely the Gallai-theorem (1933). We solve the discrepancy problem for d-dimensional arithmetic progressions by proving disc(H )=

  1. Synthesis of Cartesian Stiffness for Robotic Applications

    Microsoft Academic Search

    Namik Ciblak; Harvey Lipkin

    1999-01-01

    A new, systematic approach to the synthesis of Cartesian sti®ness by springs is presented using screw (spatial vector) algebra. The space of solutions is fully characterized for all sti®nesses realizable by springs. The main result shows that a rank r sti®ness can al- ways be synthesized by r springs. Further, it can also be synthesized by an arbitrarily large number

  2. On automating domain connectivity for overset grids

    NASA Technical Reports Server (NTRS)

    Chiu, Ing-Tsau; Meakin, Robert L.

    1995-01-01

    An alternative method for domain connectivity among systems of overset grids is presented. Reference uniform Cartesian systems of points are used to achieve highly efficient domain connectivity, and form the basis for a future fully automated system. The Cartesian systems are used to approximate body surfaces and to map the computational space of component grids. By exploiting the characteristics of Cartesian systems, Chimera type hole-cutting and identification of donor elements for intergrid boundary points can be carried out very efficiently. The method is tested for a range of geometrically complex multiple-body overset grid systems. A dynamic hole expansion/contraction algorithm is also implemented to obtain optimum domain connectivity; however, it is tested only for geometry of generic shapes.

  3. Fibonacci Grids

    NASA Technical Reports Server (NTRS)

    Swinbank, Richard; Purser, James

    2006-01-01

    Recent years have seen a resurgence of interest in a variety of non-standard computational grids for global numerical prediction. The motivation has been to reduce problems associated with the converging meridians and the polar singularities of conventional regular latitude-longitude grids. A further impetus has come from the adoption of massively parallel computers, for which it is necessary to distribute work equitably across the processors; this is more practicable for some non-standard grids. Desirable attributes of a grid for high-order spatial finite differencing are: (i) geometrical regularity; (ii) a homogeneous and approximately isotropic spatial resolution; (iii) a low proportion of the grid points where the numerical procedures require special customization (such as near coordinate singularities or grid edges). One family of grid arrangements which, to our knowledge, has never before been applied to numerical weather prediction, but which appears to offer several technical advantages, are what we shall refer to as "Fibonacci grids". They can be thought of as mathematically ideal generalizations of the patterns occurring naturally in the spiral arrangements of seeds and fruit found in sunflower heads and pineapples (to give two of the many botanical examples). These grids possess virtually uniform and highly isotropic resolution, with an equal area for each grid point. There are only two compact singular regions on a sphere that require customized numerics. We demonstrate the practicality of these grids in shallow water simulations, and discuss the prospects for efficiently using these frameworks in three-dimensional semi-implicit and semi-Lagrangian weather prediction or climate models.

  4. Evaluation of gridded scanning ARM cloud radar reflectivity observations and vertical doppler velocity retrievals

    NASA Astrophysics Data System (ADS)

    Lamer, K.; Tatarevic, A.; Jo, I.; Kollias, P.

    2014-04-01

    The scanning Atmospheric Radiation Measurement (ARM) cloud radars (SACRs) provide continuous atmospheric observations aspiring to capture the 3-D cloud-scale structure. Sampling clouds in 3-D is challenging due to their temporal-spatial scales, the need to sample the sky at high elevations and cloud radar limitations. Thus, a suggested scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range-Height Indicator - CW-RHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Southern Great Plains and Cape Cod sites are post-processed (detection mask, gaseous attenuation correction, insect filtering and velocity de-aliasing). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimensions. Next the Cartesian-gridded Doppler velocity fields are decomposed into the horizontal wind velocity contribution and the vertical Doppler velocity component. For validation purposes, all gridded and retrieved fields are compared to collocated zenith-pointing ARM cloud radar measurements. We consider that the SACR sensitivity loss with range, the cloud type observed and the research purpose should be considered in determining the gridded domain size. Our results also demonstrate that the gridded SACR observations resolve the main features of low and high stratiform clouds. It is established that the CW-RHI observations complemented with processing techniques could lead to robust 3-D cloud dynamical representations up to 25-30 degrees off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics and anisotropy and lead to more realistic 3-D radiative transfer calculations.

  5. EFFECTIVE SOLUTION OF A CLASS OF BOUNDARY VALUE PROBLEMS OF THERMOELASTICITY IN GENERALIZED CYLINDRICAL COORDINATES

    Microsoft Academic Search

    N. KHOMASURIDZE

    2004-01-01

    A class of static boundary value problems of thermoelasticity is eectively solved for bodies bounded by coordinate surfaces of generalized cylindrical coordinates ‰; fi; z (‰, fi are orthogonal curvilinear coordinates on the plane and z is a linear coordinate). Besides in the Cartesian system of coordinates some boundary value thermoelasticity problems are separately considered for a rectangular parallelepiped. An

  6. Adaptation of a k-epsilon Model to a C artesian Grid Based Methodology

    Microsoft Academic Search

    Stephen M. Ruffin; Jae-Doo Lee

    Despite the high cost of memory and CPU time required to resolve the boundary layer, a viscous unstructured grid solver has many advantages over a structured grid solver such as the convenience in automated grid generation and vortex capturing by solution adaption. In present study, an unstructured Cartesian grid solver is developed on the basis of the existing viscous solver,

  7. FIDDLE: A Computer Code for Finite Difference Development of Linear Elasticity in Generalized Curvilinear Coordinates

    NASA Technical Reports Server (NTRS)

    Kaul, Upender K.

    2005-01-01

    A three-dimensional numerical solver based on finite-difference solution of three-dimensional elastodynamic equations in generalized curvilinear coordinates has been developed and used to generate data such as radial and tangential stresses over various gear component geometries under rotation. The geometries considered are an annulus, a thin annular disk, and a thin solid disk. The solution is based on first principles and does not involve lumped parameter or distributed parameter systems approach. The elastodynamic equations in the velocity-stress formulation that are considered here have been used in the solution of problems of geophysics where non-rotating Cartesian grids are considered. For arbitrary geometries, these equations along with the appropriate boundary conditions have been cast in generalized curvilinear coordinates in the present study.

  8. Supramolecular assembly at interfaces: formation of an extended two-dimensional coordinate covalent square grid network at the air-water interface.

    PubMed

    Culp, Jeffrey T; Park, Ju-Hyun; Stratakis, Diktys; Meisel, Mark W; Talham, Daniel R

    2002-08-28

    Reaction of a Langmuir monolayer of an amphiphilic pentacyanoferrate(3+) complex with Ni(2+) ions from the subphase results in the formation of a two-dimensional iron-nickel cyanide-bridged network at the air-water interface. The network can be transferred to various supports to form monolayer or multilayer lamellar films by the Langmuir-Blodgett (LB) technique. The same network does not form from homogeneous reaction conditions. Therefore, the results demonstrate the potential utility of an interface as a structure director in the assembly of low dimensional coordinate covalent network solids. Characterization of the LB film extended networks by X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, SQUID magnetometry, X-ray absorption fine structure (XAFS), and grazing incidence synchrotron X-ray diffraction (GIXD) revealed a face-centered square grid structure with an average domain size of 3600 A(2). Magnetic measurements indicated that the network undergoes a transition to a ferromagnetic state below a T(c) of 8 K. PMID:12188672

  9. Internal coordinate density of state from molecular dynamics simulation.

    PubMed

    Lai, Pin-Kuang; Lin, Shiang-Tai

    2015-03-30

    The vibrational density of states (DoS), calculated from the Fourier transform of the velocity autocorrelation function, provides profound information regarding the structure and dynamic behavior of a system. However, it is often difficult to identify the exact vibrational mode associated with a specific frequency if the DoS is determined based on velocities in Cartesian coordinates. Here, the DoS is determined based on velocities in internal coordinates, calculated from Cartesian atomic velocities using a generalized Wilson's B-matrix. The DoS in internal coordinates allows for the correct detection of free dihedral rotations that may be mistaken as hindered rotation in Cartesian DoS. Furthermore, the pronounced enhancement of low frequency modes in Cartesian DoS for macromolecules should be attributed to the coupling of dihedral and angle motions. The internal DoS, thus deconvolutes the internal motions and provides fruitful insights to the dynamic behaviors of a system. PMID:25565300

  10. Configuration space representation in parallel coordinates

    NASA Technical Reports Server (NTRS)

    Fiorini, Paolo; Inselberg, Alfred

    1989-01-01

    By means of a system of parallel coordinates, a nonprojective mapping from R exp N to R squared is obtained for any positive integer N. In this way multivariate data and relations can be represented in the Euclidean plane (embedded in the projective plane). Basically, R squared with Cartesian coordinates is augmented by N parallel axes, one for each variable. The N joint variables of a robotic device can be represented graphically by using parallel coordinates. It is pointed out that some properties of the relation are better perceived visually from the parallel coordinate representation, and that new algorithms and data structures can be obtained from this representation. The main features of parallel coordinates are described, and an example is presented of their use for configuration space representation of a mechanical arm (where Cartesian coordinates cannot be used).

  11. 76 FR 46279 - Smart Grid Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-02

    ...Institute of Standards and Technology Smart Grid Advisory Committee AGENCY: Department...SUMMARY: The Smart Grid Advisory Committee (SGAC or Committee...Office of the National Coordinator for Smart Grid Interoperability, National...

  12. ABCXYZ: vector potential (A) and magnetic field (B) code (C) for Cartesian (XYZ) geometry using general current elements. [In LRL TRAN for CDC > 600 computer

    Microsoft Academic Search

    D. V. Anderson; J. Breazeal; C. H. Finan; B. M. Johnston

    1976-01-01

    ABCXYZ is a computer code for obtaining the Cartesian components of the vector potential and the magnetic field on an observed grid from an arrangement of current-carrying wires. Arbitrary combinations of straight line segments, arcs, and loops are allowed in the specification of the currents. Arbitrary positions and orientations of the current-carrying elements are also allowed. Specification of the wire

  13. Comparing cartesian closed categories of (core) compactly generated spaces

    E-print Network

    Simpson, Alex

    1 Comparing cartesian closed categories of (core) compactly generated spaces By MART´IN ESCARD 2004 Abstract It is well known that, although the category of topological spaces is not cartesian spaces; (ii) quotients of locally compact Hausdorff spaces, which form a larger category; (iii) quotients

  14. Comparing cartesian closed categories of (core) compactly generated spaces

    E-print Network

    Escardó, Martín

    1 Comparing cartesian closed categories of (core) compactly generated spaces By MART #19; IN ESCARD February 2004 Abstract It is well known that, although the category of topological spaces is not cartesian; spaces; (ii) quotients of locally compact Hausdor#11; spaces, which form a larger category; (iii

  15. EXTRACTING FUZZY SPARSE RULE BASE BY CARTESIAN REPRESENTATION AND

    E-print Network

    Ward, Karen

    EXTRACTING FUZZY SPARSE RULE BASE BY CARTESIAN REPRESENTATION AND CLUSTERING Yeung Yam 1 , Vladik Sparse rule base and interpolation have been proposed as possible solution to alleviate the geometric the effectiveness of the approach. Keywords: Fuzzy sparse rule base, Cartesian representation, fuzzy clustering

  16. Senior Year Project Design and Implementation of a Cartesian Router

    E-print Network

    Hughes, Larry

    ECED 4902 Senior Year Project Design and Implementation of a Cartesian Router Students: Edward A Submitted: 2001/12/03 #12;Abstract The goal of this project was to design and implement a Cartesian router. Unfortunately, the discrete logic router proved to be too large for two students with full course

  17. A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Coirier, William J.; Powell, Kenneth G.

    1995-01-01

    A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations in two dimensions is developed and tested. Grids about geometrically complicated bodies are generated automatically, by recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, N-sided 'cut' cells are created using polygon-clipping algorithms. The grid is stored in a binary-tree data structure which provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite-volume formulation. The convective terms are upwinded: A gradient-limited, linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The more robust of a series of viscous flux functions is used to provide the viscous fluxes at the cell interfaces. Adaptively-refined solutions of the Navier-Stokes equations using the Cartesian, cell-based approach are obtained and compared to theory, experiment and other accepted computational results for a series of low and moderate Reynolds number flows.

  18. A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Coirier, William J.; Powell, Kenneth G.

    1994-01-01

    A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations in two dimensions is developed and tested. Grids about geometrically complicated bodies are generated automatically, by recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, N-sided 'cut' cells are created using polygon-clipping algorithms. The grid is stored in a binary-tree structure which provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite-volume formulation. The convective terms are upwinded: a gradient-limited, linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The more robust of a series of viscous flux functions is used to provide the viscous fluxes at the cell interfaces. Adaptively-refined solutions of the Navier-Stokes equations using the Cartesian, cell-based approach are obtained and compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows.

  19. AIAA-01-0439 OVERLAPPING UNSTRUCTURED GRIDS

    E-print Network

    Löhner, Rainald

    based on adaptive Cartesian grids: these do not require remeshing or mesh movement, but extra e ort developed. A generalized `dominant mesh criterion' that includes element size and distance to walls is used bodies. The techniques developed have been implemented into FEFLO, a general-purpose CFD code

  20. Graphing Equations on the Cartesian Plane: Slope

    NSDL National Science Digital Library

    VU Bioengineering RET Program, School of Engineering,

    2007-01-01

    The lesson teaches students about an important characteristic of lines: their slope. Slope can be determined either in graphical or algebraic form. Slope can also be described as positive, negative, zero, or undefined. Students get an explanation of when and how these different types of slope occur. Finally, students learn how slope relates to parallel and perpendicular lines. When two lines are parallel, they have the same slope and when they are perpendicular their slopes are negative reciprocals of one another. Prerequisite knowledge: Students must know how to graph points on the Cartesian plane. They must be familiar with the x- and y- axes on the plane in both the positive and negative directions.

  1. OVERGRID: A Unified Overset Grid Generation Graphical Interface

    NASA Technical Reports Server (NTRS)

    Chan, William M.; Akien, Edwin W. (Technical Monitor)

    1999-01-01

    This paper presents a unified graphical interface and gridding strategy for performing overset grid generation. The interface called OVERGRID has been specifically designed to follow an efficient overset gridding strategy, and contains general grid manipulation capabilities as well as modules that are specifically suited for overset grids. General grid utilities include functions for grid redistribution, smoothing, concatenation, extraction, extrapolation, projection, and many others. Modules specially tailored for overset grids include a seam curve extractor, hyperbolic and algebraic surface grid generators, a hyperbolic volume grid generator, and a Cartesian box grid generator, Grid visualization is achieved using OpenGL while widgets are constructed with Tcl/Tk. The software is portable between various platforms from UNIX workstations to personal computers.

  2. A CUDA-based reverse gridding algorithm for MR reconstruction.

    PubMed

    Yang, Jingzhu; Feng, Chaolu; Zhao, Dazhe

    2013-02-01

    MR raw data collected using non-Cartesian method can be transformed on Cartesian grids by traditional gridding algorithm (GA) and reconstructed by Fourier transform. However, its runtime complexity is O(K×N(2)), where resolution of raw data is N×N and size of convolution window (CW) is K. And it involves a large number of matrix calculation including modulus, addition, multiplication and convolution. Therefore, a Compute Unified Device Architecture (CUDA)-based algorithm is proposed to improve the reconstruction efficiency of PROPELLER (a globally recognized non-Cartesian sampling method). Experiment shows a write-write conflict among multiple CUDA threads. This induces an inconsistent result when synchronously convoluting multiple k-space data onto the same grid. To overcome this problem, a reverse gridding algorithm (RGA) was developed. Different from the method of generating a grid window for each trajectory as in traditional GA, RGA calculates a trajectory window for each grid. This is what "reverse" means. For each k-space point in the CW, contribution is cumulated to this grid. Although this algorithm can be easily extended to reconstruct other non-Cartesian sampled raw data, we only implement it based on PROPELLER. Experiment illustrates that this CUDA-based RGA has successfully solved the write-write conflict and its reconstruction speed is 7.5 times higher than that of traditional GA. PMID:22898698

  3. Equipartition Principle for Internal Coordinate Molecular Dynamics

    PubMed Central

    Jain, Abhinandan; Park, In-Hee; Vaidehi, Nagarajan

    2012-01-01

    The principle of equipartition of (kinetic) energy for all-atom Cartesian molecular dynamics states that each momentum phase space coordinate on the average has ½kT of kinetic energy in a canonical ensemble. This principle is used in molecular dynamics simulations to initialize velocities, and to calculate statistical properties such as entropy. Internal coordinate molecular dynamics (ICMD) models differ from Cartesian models in that the overall kinetic energy depends on the generalized coordinates and includes cross-terms. Due to this coupled structure, no such equipartition principle holds for ICMD models. In this paper we introduce non-canonical modal coordinates to recover some of the structural simplicity of Cartesian models and develop a new equipartition principle for ICMD models. We derive low-order recursive computational algorithms for transforming between the modal and physical coordinates. The equipartition principle in modal coordinates provides a rigorous method for initializing velocities in ICMD simulations thus replacing the ad hoc methods used until now. It also sets the basis for calculating conformational entropy using internal coordinates. PMID:23341754

  4. Conservation equations of gasdynamics in curvilinear coordinate systems

    NASA Technical Reports Server (NTRS)

    Vinokur, M.

    1974-01-01

    Description of a new method of writing the conservation equations of gasdynamics in curvilinear coordinates which eliminates undifferentiated terms. It is thus possible to readily apply difference schemes derived for Cartesian coordinates which conserve mass, momentum, and energy in the total flow field. The method is derived for orthogonal coordinates, and then extended to cover the most general class of coordinate transformations, using general tensor analysis. Several special features of the equations are discussed.

  5. Adjoint Algorithm for CAD-Based Shape Optimization Using a Cartesian Method

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.

    2004-01-01

    Adjoint solutions of the governing flow equations are becoming increasingly important for the development of efficient analysis and optimization algorithms. A well-known use of the adjoint method is gradient-based shape optimization. Given an objective function that defines some measure of performance, such as the lift and drag functionals, its gradient is computed at a cost that is essentially independent of the number of design variables (geometric parameters that control the shape). More recently, emerging adjoint applications focus on the analysis problem, where the adjoint solution is used to drive mesh adaptation, as well as to provide estimates of functional error bounds and corrections. The attractive feature of this approach is that the mesh-adaptation procedure targets a specific functional, thereby localizing the mesh refinement and reducing computational cost. Our focus is on the development of adjoint-based optimization techniques for a Cartesian method with embedded boundaries.12 In contrast t o implementations on structured and unstructured grids, Cartesian methods decouple the surface discretization from the volume mesh. This feature makes Cartesian methods well suited for the automated analysis of complex geometry problems, and consequently a promising approach to aerodynamic optimization. Melvin et developed an adjoint formulation for the TRANAIR code, which is based on the full-potential equation with viscous corrections. More recently, Dadone and Grossman presented an adjoint formulation for the Euler equations. In both approaches, a boundary condition is introduced to approximate the effects of the evolving surface shape that results in accurate gradient computation. Central to automated shape optimization algorithms is the issue of geometry modeling and control. The need to optimize complex, "real-life" geometry provides a strong incentive for the use of parametric-CAD systems within the optimization procedure. In previous work, we presented an effective optimization framework that incorporates a direct-CAD interface. In this work, we enhance the capabilities of this framework with efficient gradient computations using the discrete adjoint method. We present details of the adjoint numerical implementation, which reuses the domain decomposition, multigrid, and time-marching schemes of the flow solver. Furthermore, we explain and demonstrate the use of CAD in conjunction with the Cartesian adjoint approach. The final paper will contain a number of complex geometry, industrially relevant examples with many design variables to demonstrate the effectiveness of the adjoint method on Cartesian meshes.

  6. Coordinate Dependence of Variability Analysis Dagmar Sternad1,2,3

    E-print Network

    Sternad, Dagmar

    Institutes of Health R01HD045639 (http://www.nichd.nih.gov/), the New York State Spinal Cord Injury Center of shoulder and elbow) but much less variation of hand kinematics (Cartesian coordinates of the hand

  7. Plasticity of Intermediate Mechanics Students' Coordinate System Choice

    ERIC Educational Resources Information Center

    Sayre, Eleanor C.; Wittman, Michael C.

    2008-01-01

    We investigate the interplay between mathematics and physics resources in intermediate mechanics students. In the mechanics course, the selection and application of coordinate systems is a consistent thread. At the University of Maine, students often start the course with a strong preference to use Cartesian coordinates, in accordance with their…

  8. Conformal coordinates associated with uniformly accelerated motion

    NASA Technical Reports Server (NTRS)

    Jones, R. T.

    1976-01-01

    Specific problems in the theory of relativity are often simplified by an appropriate choice of the coordinate system. Restricted conformal coordinates provide an especially simple analysis of motion with uniform acceleration, known as hyperbolic motion. Conformal coordinates x', t' may be obtained from Cartesian coordinates x, t by the transformation x'+ct'=F(x+ct) and x'-ct'=G(x-ct), where c is the velocity of light. A variable motion of the x' system is determined by the choice of the functions F and G.

  9. Consistent properties reconstruction on adaptive Cartesian meshes for complex fluids computations

    NASA Astrophysics Data System (ADS)

    Xia, Guoping; Li, Ding; Merkle, Charles L.

    2007-07-01

    An efficient reconstruction procedure for evaluating the constitutive properties of a complex fluid from general or specialized thermodynamic databases is presented. Properties and their pertinent derivatives are evaluated by means of an adaptive Cartesian mesh in the thermodynamic plane that provides user-specified accuracy over any selected domain. The Cartesian grid produces a binary tree data structure whose search efficiency is competitive with that for an equally spaced table or with simple equations of state such as a perfect gas. Reconstruction is accomplished on a triangular subdivision of the 2D Cartesian mesh that ensures function continuity across cell boundaries in equally and unequally spaced portions of the table to C0, C1 or C2 levels. The C0 and C1 reconstructions fit the equation of state and enthalpy relations separately, while the C2 reconstruction fits the Helmholtz or Gibbs function enabling EOS/enthalpy consistency also. All three reconstruction levels appear effective for CFD solutions obtained to date. The efficiency of the method is demonstrated through storage and data retrieval examples for air, water and carbon dioxide. The time required for property evaluations is approximately two orders of magnitude faster with the reconstruction procedure than with the complete thermodynamic equations resulting in estimated 3D CFD savings of from 30 to 60. Storage requirements are modest for today's computers, with the C1 method requiring slightly less storage than those for the C0 and C2 reconstructions when the same accuracy is specified. Sample fluid dynamic calculations based upon the procedure show that the C1 and C2 methods are approximately a factor of two slower than the C0 method but that the reconstruction procedure enables arbitrary fluid CFD calculations that are as efficient as those for a perfect gas or an incompressible fluid for all three accuracy levels.

  10. A three-dimensional turbulent compressible subsonic duct flow analysis for use with constructed coordinate systems

    NASA Technical Reports Server (NTRS)

    Levy, R.; Mcdonald, H.; Briley, W. R.; Kreskovsky, J. P.

    1981-01-01

    An approximate analysis is presented which is applicable to nonorthogonal coordinate systems having a curved centerline and planar transverse coordinate surfaces normal to the centerline. The primary flow direction is taken to coincide with the local direction of the duct centerline and is hence normal to transverse coordinate planes. The formulation utilizes vector components (velocity, vorticity, transport equations) defined in terms of local Cartesian directions aligned with the centerline tangent, although the governing equations themselves are expressed in general nonorthogonal coordinates. For curved centerlines, these vector quantities are redefined in new local Cartesian directions at each streamwise location. The use of local Cartesian variables and fluxes leads to governing equations which require only first derivatives of the coordinate transformation, and this provides for the aforementioned ease in using constructed coordinates.

  11. Crystal structure of a two-dimensional grid-type iron(II) coordination polymer: poly[[di-aqua-tetra-?-cyanido-diargentate(I)iron(II)] trans-1,2-bis(pyridin-2-yl)ethyl-ene disolvate].

    PubMed

    Othong, Jintana; Wannarit, Nanthawat; Pakawatchai, Chaveng; Youngme, Sujittra

    2014-08-01

    In the title compound, {[Ag2Fe(CN)4(H2O)2]·2C12H10N2} n , the asymmetric unit contains one Fe(II) cation, two water mol-ecules, two di-cyanido-argentate(I) anions and two uncoordinating 1,2-bis-(pyridin-2-yl)ethyl-ene (2,2'-bpe) mol-ecules. Each Fe(II) atom is six-coordinated in a nearly regular octa-hedral geometry by four N atoms from di-cyanido-argentate(I) bridges and two coordinating water mol-ecules. The Fe(II) atoms are bridged by di-cyanido-argentate(I) units to give a two-dimensional layer with square-grid spaces. The inter-grid spaces with inter-layer distance of 6.550?(2)?Å are occupied by 2,2'-bpe guest mol-ecules which form O-H?N hydrogen bonds to the host layers. This leads to an extended three-dimensional supra-molecular architecture. The structure of the title compound is compared with some related compounds containing di-cyanido-argentate(I) ligands and N-donor organic co-ligands. PMID:25249868

  12. Evidence against a single coordinate system representation in the motor cortex

    Microsoft Academic Search

    Wei Wu; Nicholas Hatsopoulos

    2006-01-01

    Understanding the coordinate systems in which the motor cortical cells encode movement parameters such as direction is a fundamental yet unresolved issue. Although many studies have assumed that motor cortex encodes direction in an extrinsic, Cartesian (CA) coordinate system, other studies have provided evidence for encoding in intermediate coordinate systems such as a shoulder-centered (SC) or in a purely intrinsic,

  13. Applications of Space-Filling-Curves to Cartesian Methods for CFD

    NASA Technical Reports Server (NTRS)

    Aftosmis, M. J.; Murman, S. M.; Berger, M. J.

    2003-01-01

    This paper presents a variety of novel uses of space-filling-curves (SFCs) for Cartesian mesh methods in CFD. While these techniques will be demonstrated using non-body-fitted Cartesian meshes, many are applicable on general body-fitted meshes-both structured and unstructured. We demonstrate the use of single theta(N log N) SFC-based reordering to produce single-pass (theta(N)) algorithms for mesh partitioning, multigrid coarsening, and inter-mesh interpolation. The intermesh interpolation operator has many practical applications including warm starts on modified geometry, or as an inter-grid transfer operator on remeshed regions in moving-body simulations Exploiting the compact construction of these operators, we further show that these algorithms are highly amenable to parallelization. Examples using the SFC-based mesh partitioner show nearly linear speedup to 640 CPUs even when using multigrid as a smoother. Partition statistics are presented showing that the SFC partitions are, on-average, within 15% of ideal even with only around 50,000 cells in each sub-domain. The inter-mesh interpolation operator also has linear asymptotic complexity and can be used to map a solution with N unknowns to another mesh with M unknowns with theta(M + N) operations. This capability is demonstrated both on moving-body simulations and in mapping solutions to perturbed meshes for control surface deflection or finite-difference-based gradient design methods.

  14. Frequency-Offset Cartesian Feedback Based on Polyphase Difference Amplifiers

    PubMed Central

    Zanchi, Marta G.; Pauly, John M.; Scott, Greig C.

    2010-01-01

    A modified Cartesian feedback method called “frequency-offset Cartesian feedback” and based on polyphase difference amplifiers is described that significantly reduces the problems associated with quadrature errors and DC-offsets in classic Cartesian feedback power amplifier control systems. In this method, the reference input and feedback signals are down-converted and compared at a low intermediate frequency (IF) instead of at DC. The polyphase difference amplifiers create a complex control bandwidth centered at this low IF, which is typically offset from DC by 200–1500 kHz. Consequently, the loop gain peak does not overlap DC where voltage offsets, drift, and local oscillator leakage create errors. Moreover, quadrature mismatch errors are significantly attenuated in the control bandwidth. Since the polyphase amplifiers selectively amplify the complex signals characterized by a +90° phase relationship representing positive frequency signals, the control system operates somewhat like single sideband (SSB) modulation. However, the approach still allows the same modulation bandwidth control as classic Cartesian feedback. In this paper, the behavior of the polyphase difference amplifier is described through both the results of simulations, based on a theoretical analysis of their architecture, and experiments. We then describe our first printed circuit board prototype of a frequency-offset Cartesian feedback transmitter and its performance in open and closed loop configuration. This approach should be especially useful in magnetic resonance imaging transmit array systems. PMID:20814450

  15. Cartesian base predictive control of robotic manipulators

    Microsoft Academic Search

    C. Ozsoy; R. Kazan

    1993-01-01

    A multi-input multi-output (MIMO) controlled auto regressive integrated moving average (CARIMA) model which has the input vector consisting of the joint torques and the output vector consisting of the velocities of the gripper expressed in the world coordinate system, is proposed for the motion of the end-effector of a robotic manipulator system. Since the manipulator is a time-varying system, because

  16. 77 FR 71169 - Smart Grid Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-29

    ...Institute of Standards and Technology Smart Grid Advisory Committee Meeting AGENCY...SUMMARY: The Smart Grid Advisory Committee (SGAC or Committee...cybersecurity coordination and the NIST Smart Grid Program Plan. The agenda may...

  17. Implicit Approaches for Moving Boundaries in a 3-D Cartesian Method

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Aftosmis, Michael J.; Berger, Marsha J.; Kwak, Dochan

    2003-01-01

    This work considers numerical simulation of three-dimensional flows with time-evolving boundaries. Such problems pose a variety of challenges for numerical schemes, and have received a substantial amount of attention in the recent literature. Since such simulations are unsteady, time-accurate solution of the governing equations is required. In special cases, the body motion can be treated by a uniform rigid motion of the computational domain. For the more general situation of relative-body motion, however, this simplification is unavailable and the simulations require a mechanism for ensuring that the mesh evolves with the moving boundaries. This involves a "remeshing" of the computational domain (either localized or global) at each physical timestep, and places a premium on both the speed and robustness of the remeshing algorithms. This work presents a method which includes unsteady flow simulation, rigid domain motion, and relative body motion using a time-evolving Cartesian grid system in three dimensions.

  18. MAPPRO: A program for processing the projection of latitude-longitude coordinates into rectangular map coordinate systems

    NASA Astrophysics Data System (ADS)

    Allison, David

    1995-08-01

    The advent of powerful, graphically oriented, desktop computer systems has increased dramatically the ability of the earth scientist to process and analyze geographic data electronically. Data that are digitized and stored electronically can be analyzed in ways that are not possible or practical with manual methods. Geographic data stored within databases can be manipulated and combined more effectively, and with greater precision, when it is stored in digital form. Unfortunately, the conversion of existing geographic data into digital form is both time consuming and prone to a variety of digitization errors. MAPPRO is presented here as a program that can convert the universal form of geographic data—latitude and longitude coordinates—into the digital cartesian coordinates that are required by computer systems. In this form geographic data can be imported into digital base maps that are calibrated to a standard projection coordinate system. In this way maps can be created without the need for repetitive manual plotting of geographically controlled data if the latitude-longitude database exists. MAPPRO has been applied to the task of plotting geological structure orientation data by this author however, virtually any data that is defined in terms of latitude and longitude may be plotted with MAPPRO. The current availability of global positioning systems (GPS) that can rapidly and accurately determine latitude-longitude coordinates has the potential to produce large amounts of position data that may need to be plotted on a variety of map projections. This type of data can be plotted directly onto digital base maps with the aid of MAPPRO. In addition, MAPPRO can be used to produce mathematically precise map boundaries and latitude-longitude grid lines. The output format used by MAPPRO allows for the importation of data into diverse selection of geographic information system (GIS) and computer-aided design (CAD) applications.

  19. ASAM v2.7: a compressible atmospheric model with a Cartesian cut cell approach

    NASA Astrophysics Data System (ADS)

    Jähn, M.; Knoth, O.; König, M.; Vogelsberg, U.

    2015-02-01

    In this work, the fully compressible, three-dimensional, nonhydrostatic atmospheric model called All Scale Atmospheric Model (ASAM) is presented. A cut cell approach is used to include obstacles and orography into the Cartesian grid. Discretization is realized by a mixture of finite differences and finite volumes and a state limiting is applied. Necessary shifting and interpolation techniques are outlined. The method can be generalized to any other orthogonal grids, e.g., a lat-long grid. A linear implicit Rosenbrock time integration scheme ensures numerical stability in the presence of fast sound waves and around small cells. Analyses of five two-dimensional benchmark test cases from the literature are carried out to show that the described method produces meaningful results with respect to conservation properties and model accuracy. The test cases are partly modified in a way that the flow field or scalars interact with cut cells. To make the model applicable for atmospheric problems, physical parameterizations like a Smagorinsky subgrid-scale model, a two-moment bulk microphysics scheme, and precipitation and surface fluxes using a sophisticated multi-layer soil model are implemented and described. Results of an idealized three-dimensional simulation are shown, where the flow field around an idealized mountain with subsequent gravity wave generation, latent heat release, orographic clouds and precipitation are modeled.

  20. A Fast Sinc Function Gridding Algorithm for Fourier Inversion in Computer Tomography

    Microsoft Academic Search

    J. D. O'Sullivan

    1985-01-01

    The Fourier inversion method for reconstruction of images in computerized tomography has not been widely used owing to the perceived difficulty of interpolating from polar or other measurement grids to the Cartesian grid required for fast numerical Fourier inversion. Although the Fourier inversion method is recognized as being computationally faster than the back-projection method for parallel ray projection data, the

  1. Nonlinear Accelerator with Transverse Motion Integrable in Normalized Polar Coordinates

    SciTech Connect

    Nagaitsev, S.; /Fermilab; Kharkov, Y.; Morozov, I.A.; /Novosibirsk, IYF; Zolkin, T.V.; /Chicago U.

    2012-05-01

    Several families of nonlinear accelerator lattices with integrable transverse motion were suggested recently. One of the requirements for the existence of two analytic invariants is a special longitudinal coordinate dependence of fields. This paper presents the particle motion analysis when a problem becomes integrable in the normalized polar coordinates. This case is distinguished from the others: it yields an exact analytical solution and has a uniform longitudinal coordinate dependence of the fields (since the corresponding nonlinear potential is invariant under the transformation from the Cartesian to the normalized coordinates). A number of interesting features are revealed: while the frequency of radial oscillations is independent of the amplitude, the spread of angular frequencies in a beam is absolute. A corresponding spread of frequencies of oscillations in the Cartesian coordinates is evaluated via the simulation of transverse Schottky noise.

  2. Internal coordinate molecular dynamics: a foundation for multiscale dynamics.

    PubMed

    Vaidehi, Nagarajan; Jain, Abhinandan

    2015-01-29

    Internal coordinates such as bond lengths, bond angles, and torsion angles (BAT) are natural coordinates for describing a bonded molecular system. However, the molecular dynamics (MD) simulation methods that are widely used for proteins, DNA, and polymers are based on Cartesian coordinates owing to the mathematical simplicity of the equations of motion. However, constraints are often needed with Cartesian MD simulations to enhance the conformational sampling. This makes the equations of motion in the Cartesian coordinates differential-algebraic, which adversely impacts the complexity and the robustness of the simulations. On the other hand, constraints can be easily placed in BAT coordinates by removing the degrees of freedom that need to be constrained. Thus, the internal coordinate MD (ICMD) offers an attractive alternative to Cartesian coordinate MD for developing multiscale MD method. The torsional MD method is a special adaptation of the ICMD method, where all the bond lengths and bond angles are kept rigid. The advantages of ICMD simulation methods are the longer time step size afforded by freezing high frequency degrees of freedom and performing a conformational search in the more important low frequency torsional degrees of freedom. However, the advancements in the ICMD simulations have been slow and stifled by long-standing mathematical bottlenecks. In this review, we summarize the recent mathematical advancements we have made based on spatial operator algebra, in developing a robust long time scale ICMD simulation toolkit useful for various applications. We also present the applications of ICMD simulations to study conformational changes in proteins and protein structure refinement. We review the advantages of the ICMD simulations over the Cartesian simulations when used with enhanced sampling methods and project the future use of ICMD simulations in protein dynamics. PMID:25517406

  3. A Simple Second Order Cartesian Scheme for Compressible Flows

    E-print Network

    Paris-Sud XI, Université de

    A Simple Second Order Cartesian Scheme for Compressible Flows Y. Gorsse, A. Iollo and L. Weynans Abstract A simple second order scheme for compressible inviscid flows on carte- sian meshes is presented to the simulation of a Ringleb flow is presented to demonstrate the accuracy of the method. Key words: compressible

  4. Developmental Plasticity in Cartesian Genetic Programming Artificial Neural Networks

    E-print Network

    Fernandez, Thomas

    Developmental Plasticity in Cartesian Genetic Programming Artificial Neural Networks Maryam Mahsal developmental plasticity in Artificial Neural Networks using Carte- sian Genetic Programming. This is inspired a trained artificial neural network loses its accuracy when the network is trained again on a different

  5. Cartesian Factoring of Polyhedra in Linear Relation Analysis

    E-print Network

    Paris-Sud XI, Université de

    to detect when a polyhedron is a Cartesian product of polyhedra of lower dimen- sions, i.e., when groups, Linear Relation Analysis was designed to discover lin- ear inequalities (or convex polyhedra) invariantly (convex hull), affine transformation, projection, check for inclusion and emptiness, and widening

  6. Coevolution of Intelligent Agents using Cartesian Genetic Programming

    E-print Network

    Fernandez, Thomas

    based on a com- partmentalised model of neurons. The genetic basis of neu- rons is an important [27]: Learning--Connectionism and neural nets General Terms Algorithms, Design, Performance Keywords GeneticCoevolution of Intelligent Agents using Cartesian Genetic Programming Gul Muhammad Khan Electronics

  7. The Structure of Integral Dimensions: Contrasting Topological and Cartesian Representations

    ERIC Educational Resources Information Center

    Jones, Matt; Goldstone, Robert L.

    2013-01-01

    Diverse evidence shows that perceptually integral dimensions, such as those composing color, are represented holistically. However, the nature of these holistic representations is poorly understood. Extant theories, such as those founded on multidimensional scaling or general recognition theory, model integral stimulus spaces using a Cartesian

  8. Feature-Driven Cartesian Adaptive Mesh Refinement in the Helios Code

    E-print Network

    Jameson, Antony

    Feature-Driven Cartesian Adaptive Mesh Refinement in the Helios Code Sean J. Kamkar Antony Jameson, Moffett Field, CA 94035 Feature-detection methods are applied to drive Cartesian-based adaptive mesh unstructured meshes in the near-body region and adaptive Cartesian meshes in the off-body region. The resultant

  9. Paper category: Genetic Programming What bloat? Cartesian Genetic Programming on Boolean problems

    E-print Network

    Fernandez, Thomas

    Paper category: Genetic Programming What bloat? Cartesian Genetic Programming on Boolean problems This paper presents an empirical study of the variation of program size over time, for a form of Genetic Programming called Cartesian Genetic Programming. Two main types of Cartesian genetic programming are examined

  10. Immersed Boundary Method for Boltzmann and Navier-Stokes Solvers with Adaptive Cartesian Mesh

    Microsoft Academic Search

    Robert R. Arslanbekov; Vladimir I. Kolobov; Anna A. Frolova

    2011-01-01

    Adaptive Cartesian mesh methods have demonstrated unique abilities for automated mesh generation and dynamic mesh adaptation to flow solution and moving boundaries. However Navier-Stokes (NS) solvers with Cartesian mesh often produce large fluctuations of surface quantities (pressure, skin friction, and heat flux) at solid boundaries. We show that the Immersed Boundary Method (IBM) with adaptive octree Cartesian mesh allows one

  11. Cartesian positioning system for localization of blast and ballistic fragments: a phantom-based pilot study.

    PubMed

    Folio, Les; Fischer, Tatjana; Shogan, Paul J; Frew, Michael; Bunger, Rolf; Provenzale, James M

    2011-11-01

    Our purpose was to demonstrate the consistency of radiologists' three-dimensional measurements of simulated blast fragment locations in vitro in an effort to objectively localize retained fragments and wound paths. We designed a phantom consisting of 10 nail heads (simulating blast fragments) glued to wooden pegs that were randomly situated at distances from a reference point within a plastic tub. The x, y, and z coordinates of simulated fragments were recorded in Cartesian 3-space relative to the reference point. Computed tomography images of the phantom were acquired. Differences in x, y, and z positions as determined by three observers were summed for each fragment. Agreement between recordings of coordinates across readers was assessed using the intraclass correlation coefficient. Summed differences in coordinate positions as determined by readers ranged between 0.00 and 1.204 cm (mean: 0.732 cm). Across readers, the intraclass correlation coefficient for each dimension was >0.99. We found excellent agreement among readers with minimal discrepancy of measured locations of simulated fragments. Our results provide a foundation for trajectory analysis necessary to lead to automated organ damage reporting for immediate assessment in the emergency department and for forensic investigation and long-term epidemiological analysis. PMID:22165660

  12. Smart Grid Impact on Intelligent Buildings

    E-print Network

    Zimmer, R. J.

    2013-01-01

    International Conference for Enhanced Building Operations ICEBO 2013 Ronald?J.?Zimmer?CAE President?&?CEO Continental?Automated?Buildings?Association http://www.CABA.org LinkedIn?Profile Smart Grid Impact on Intelligent Buildings CABA BOARD... OF DIRECTORS 3 Making?the?Grid?Smart Smart?grid?features?expand?energy? efficiency?beyond?the?grid?into? buildings?by?coordinating?low?priority? energy?consuming?devices?to?take? advantage?of?the?most?desirable? energy?sources Smart?grids...

  13. The Coordinate System for LDC Detector Studies

    E-print Network

    is then defined as follows: LC-XX-2005-XXX 1. The coordinate system is cartesian and right-handed. 2. Its origin to the LDC community in the LDC Phone/Video Meeting of 2005-09-29 [2] and has generally been agreed upon.ilcldc.org [2] LDC Phone/Video Meeting, 2005-09-29, www.ilcldc.org/meetings/ fourthLDCmeetingfolder/ [3] Guinea

  14. Equipartition Principle for Internal Coordinate Molecular Dynamics Abhinandan Jain,*,

    E-print Network

    of equipartition of (kinetic) energy for all-atom Cartesian molecular dynamics states that each momentum phase space coordinate on the average has kT/2 of kinetic energy in a canonical ensemble. This principle on the average (where k is the Boltzmann constant and T is the thermodynamic temperature). This equipartition

  15. Degree elevation for single-valued curves in polar coordinates

    E-print Network

    Casciola, Giulio

    Degree elevation for single-valued curves in polar coordinates G.Casciola, M.Lacchini and S natural value k. In this paper, two alternative formulae for degree elevation from degree n to kn is numerically proved. Keywords: Degree elevation; Polar curves; Cartesian rational curves; Reparametrization 1

  16. Constructing the ASCI Computational Grid

    Microsoft Academic Search

    Judy I. Beiriger; Wilbur R. Johnson; Hugh P. Bivens; Steven L. Humphreys; RONALD E. RHEA

    2000-01-01

    The Accelerated Strategic Computing Initiative (ASCI) computational grid is being constructed to interconnect the high performance computing resources of the nuclear weapons complex. The grid will simplify access to the diverse computing, storage, network, and visualization resources, and will enable the coordinated use of shared resources regardless of location. To match existing hardware platforms, required security services, and current simulation

  17. Parallel domain connectivity algorithm for unsteady flow computations using overlapping and adaptive grids

    NASA Astrophysics Data System (ADS)

    Sitaraman, Jayanarayanan; Floros, Matthew; Wissink, Andrew; Potsdam, Mark

    2010-06-01

    This paper describes the algorithms and functionality of a new module developed to support overset grid assembly associated with performing time-dependent and adaptive moving body calculations of external aerodynamic flows using a multi-solver paradigm (i.e. different CFD solvers in different parts of the computational domain). We use the term "domain connectivity" in this paper to denote all the procedures that are involved in an overset grid assembly, and the module developed is referred henceforth as the domain-connectivity module. The domain-connectivity module coordinates the data transfer between different solvers applied in different parts of the computational domain - body fitted structured or unstructured to capture viscous near-wall effects, and Cartesian adaptive mesh refinement to capture effects away from the wall. The execution of the CFD solvers and the domain-connectivity module are orchestrated by a Python-based computational infrastructure. The domain-connectivity module is fully parallel and performs all its operations (identification of grid overlaps and determination of data interpolation strategy) on the partitioned grid data. In addition, the domain connectivity procedures are completely automated such that no user intervention or manual input is necessary. The capabilities and performance of the package are presented for several test problems, including flow over a NACA 0015 wing and an AGARD A2 slotted airfoil, hover simulation of a scaled V-22 rotor, and dynamic simulation of a UH-60A rotor in forward flight. A modification to the algorithm for improved domain connectivity solutions in problems with tight tolerances as well as heterogeneous grid clustering is also presented.

  18. An unstructured/structured multi-layer hybrid grid method and its application

    NASA Astrophysics Data System (ADS)

    Sang, Weimin; Li, Fengwei

    2007-03-01

    A multi-layer hybrid grid method is constructed to simulate complex flow field around 2-D and 3-D configuration. The method combines Cartesian grids with structured grids and triangular meshes to provide great flexibility in discretizing a domain. We generate the body-fitted structured grids near the wall surface and the Cartesian grids for the far field. In addition, we regard the triangular meshes as an adhesive to link each grid part. Coupled with a tree data structure, the Cartesian grid is generated automatically through a cell-cutting algorithm. The grid merging methodology is discussed, which can smooth hybrid grids and improve the quality of the grids. A cell-centred finite volume flow solver has been developed in combination with a dual-time stepping scheme. The flow solver supports arbitrary control volume cells. Both inviscid and viscous flows are computed by solving the Euler and Navier-Stokes equations. The above methods and algorithms have been validated on some test cases. Computed results are presented and compared with experimental data.

  19. Grid management

    NASA Technical Reports Server (NTRS)

    Hwang, Danny

    1992-01-01

    A computational environment that allows many Computational Fluid Dynamics (CFD) engineers to work on the same project exists in the Special Project Office (SPO). This environment enables several users to carry out the task of grid generation. The grid management system, used by the engineers, is described in a brief overview. The topics will include the grid file naming system, the grid-generation procedure, grid storage, and the grid format standard.

  20. Relativistic theory of elastic deformable astronomical bodies: Perturbation equations in rotating spherical coordinates and junction conditions

    Microsoft Academic Search

    Chongming Xuand; Xuejun Wu; Michael Soffel; Sergei Klioner

    2003-01-01

    In this paper, the dynamical equations and junction conditions at the interface between adjacent layers of different elastic properties for an elastic deformable astronomical body in the first post-Newtonian approximation of Einstein theory of gravity are discussed in both rotating Cartesian coordinates and rotating spherical coordinates. The unperturbed rotating body (the ground state) is described as a uniformly rotating, stationary

  1. ONMCGP: Orthogonal Neighbourhood Mutation Cartesian Genetic Programming for Evolvable Hardware

    NASA Astrophysics Data System (ADS)

    I, Fuchuan N.; I, Yuanxiang L.; E, Peng K.

    2014-03-01

    Evolvable Hardware is facing the problems of scalability and stalling effect. This paper proposed a novel Orthogonal Neighbourhood Mutation (ONM) operator in Cartesian genetic programming (CGP), to reduce the stalling effect in CGP and improve the efficiency of the algorithms.The method incorporates with Differential Evolution strategy. Demonstrated by experiments on benchmark, the proposed Orthogonal Neighbourhood Search can jump out of Local optima, reduce the stalling effect in CGP and the algorithm convergence faster.

  2. Frequency-Offset Cartesian Feedback for MRI Power Amplifier Linearization

    PubMed Central

    Zanchi, Marta Gaia; Stang, Pascal; Kerr, Adam; Pauly, John Mark; Scott, Greig Cameron

    2011-01-01

    High-quality magnetic resonance imaging (MRI) requires precise control of the transmit radio-frequency field. In parallel excitation applications such as transmit SENSE, high RF power linearity is essential to cancel aliased excitations. In widely-employed class AB power amplifiers, gain compression, cross-over distortion, memory effects, and thermal drift all distort the RF field modulation and can degrade image quality. Cartesian feedback (CF) linearization can mitigate these effects in MRI, if the quadrature mismatch and DC offset imperfections inherent in the architecture can be minimized. In this paper, we present a modified Cartesian feedback technique called “frequency-offset Cartesian feedback” (FOCF) that significantly reduces these problems. In the FOCF architecture, the feedback control is performed at a low intermediate frequency rather than DC, so that quadrature ghosts and DC errors are shifted outside the control bandwidth. FOCF linearization is demonstrated with a variety of typical MRI pulses. Simulation of the magnetization obtained with the Bloch equation demonstrates that high-fidelity RF reproduction can be obtained even with inexpensive class AB amplifiers. Finally, the enhanced RF fidelity of FOCF over CF is demonstrated with actual images obtained in a 1.5 T MRI system. PMID:20959264

  3. Quality-based generation of weather radar Cartesian products

    NASA Astrophysics Data System (ADS)

    O?ródka, K.; Szturc, J.

    2014-11-01

    Weather radar data volumes are commonly processed to obtain various 2-D Cartesian products based on the transfer from polar to Cartesian representations through a certain interpolation method. In this research, an algorithm of the spatial interpolation of polar reflectivity data with respect to QI (quality index) data is applied to find the Cartesian reflectivity as PPI (plan position indicator) product and generate a corresponding QI field. On this basis, quality-based versions of standard algorithms for the generation of the following products have been developed: ETOP (echo top), MAX (maximum of reflectivity), and VIL (vertically integrated liquid water). Moreover, as an example of a higher-level product, a CONVECTION (detection of convection) has been defined as a specific combination of the above-listed standard products. A corresponding QI field is determined for each generated product, taking into account the quality of the pixels from which a given product was determined and how large a fraction of the investigated heights was scanned. Examples of such quality-based products are presented in the paper.

  4. Enhanced Elliptic Grid Generation

    NASA Technical Reports Server (NTRS)

    Kaul, Upender K.

    2007-01-01

    An enhanced method of elliptic grid generation has been invented. Whereas prior methods require user input of certain grid parameters, this method provides for these parameters to be determined automatically. "Elliptic grid generation" signifies generation of generalized curvilinear coordinate grids through solution of elliptic partial differential equations (PDEs). Usually, such grids are fitted to bounding bodies and used in numerical solution of other PDEs like those of fluid flow, heat flow, and electromagnetics. Such a grid is smooth and has continuous first and second derivatives (and possibly also continuous higher-order derivatives), grid lines are appropriately stretched or clustered, and grid lines are orthogonal or nearly so over most of the grid domain. The source terms in the grid-generating PDEs (hereafter called "defining" PDEs) make it possible for the grid to satisfy requirements for clustering and orthogonality properties in the vicinity of specific surfaces in three dimensions or in the vicinity of specific lines in two dimensions. The grid parameters in question are decay parameters that appear in the source terms of the inhomogeneous defining PDEs. The decay parameters are characteristic lengths in exponential- decay factors that express how the influences of the boundaries decrease with distance from the boundaries. These terms govern the rates at which distance between adjacent grid lines change with distance from nearby boundaries. Heretofore, users have arbitrarily specified decay parameters. However, the characteristic lengths are coupled with the strengths of the source terms, such that arbitrary specification could lead to conflicts among parameter values. Moreover, the manual insertion of decay parameters is cumbersome for static grids and infeasible for dynamically changing grids. In the present method, manual insertion and user specification of decay parameters are neither required nor allowed. Instead, the decay parameters are determined automatically as part of the solution of the defining PDEs. Depending on the shape of the boundary segments and the physical nature of the problem to be solved on the grid, the solution of the defining PDEs may provide for rates of decay to vary along and among the boundary segments and may lend itself to interpretation in terms of one or more physical quantities associated with the problem.

  5. Verification and validation of the Spalart-Allmaras turbulence model for strand grids

    NASA Astrophysics Data System (ADS)

    Tong, Oisin

    The strand-Cartesian grid approach provides many advantages for complex moving- body flow simulations, including fully-automatic volume grid generation, highly scalable domain connectivity, and high-order accuracy. In this work the Spalart-Allmaras model is implemented, verified, and validated for high Reynolds number turbulent flows in a strand- Cartesian solver. Second-order convergence is achieved using the Method of Manufactured Solutions implying correct implementation of the turbulence model. By using the NASA- Langley online resource, specific flow cases are validated with two independent compressible codes: FUN3D and CFL3D. The strand solver is validated with zero-pressure gradient flat plate and bump-in-channel cases, and shows excellent agreement with FUN3D and CFL3D for various aspects of turbulent flow, including: velocity profiles, turbulent viscosity profile, coefficient of surface pressure, and drag. Methods of handling sharp corners with strand grids through combinations of strand vector smoothing, multiple strands emanating from a single surface node, and telescoping Cartesian refinement into corner regions of the near- body grid are investigated for a NACA 0012 case. For standard viscous high-aspect ratio grids, smoothed strands with telescoping Cartesian refinement provide the most accurate results with the least complexity. Mesh discontinuities associated with use of multiple strands at sharp corners produce more error than with smoothed strands. With both strand approaches -- vector smoothing and multiple strands -- targeted Cartesian refinement is critical to capture features near sharp corners where strand grids alone are too coarse to capture. Other results show agreement with FUN3D and CFL3D. By using strand vector smoothing and telescoping Cartesian refinement, a NACA 4412 trailing edge separation case is validated with comparison against CFL3D and FUN3D. Velocity profiles show reasonable agreement with CFL3D; however implementing preconditioning to the solver in the future may increase the accuracy of the solution.

  6. Grid spacing control with variation diminishing splines

    NASA Technical Reports Server (NTRS)

    Smith, P. W.

    1983-01-01

    Methods used to specify and control two and three dimensional grids on which numerical solutions of partial differential equations may be obtained were studied. While initially focusing on grid generation, the research will evolve into a consideration of the interaction of grid generation with the solution of a partial differential equation. The multisurface method of grid generation was used to continuously patch a grid onto an existing grid. In the resulting grid the elements of the Jacobian matrix must be continuous across the boundary between the original grid and the patched grid. Programs were written which accept as input the coordinates of the original grid and the desired new boundary, and then use the three-surface or four-surface version of the multisurface method to extend the original grid out to a new boundary.

  7. Exact Integrations of Polynomials and Symmetric Quadrature Formulas over Arbitrary Polyhedral Grids

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1997-01-01

    This paper is concerned with two important elements in the high-order accurate spatial discretization of finite volume equations over arbitrary grids. One element is the integration of basis functions over arbitrary domains, which is used in expressing various spatial integrals in terms of discrete unknowns. The other consists of quadrature approximations to those integrals. Only polynomial basis functions applied to polyhedral and polygonal grids are treated here. Non-triangular polygonal faces are subdivided into a union of planar triangular facets, and the resulting triangulated polyhedron is subdivided into a union of tetrahedra. The straight line segment, triangle, and tetrahedron are thus the fundamental shapes that are the building blocks for all integrations and quadrature approximations. Integrals of products up to the fifth order are derived in a unified manner for the three fundamental shapes in terms of the position vectors of vertices. Results are given both in terms of tensor products and products of Cartesian coordinates. The exact polynomial integrals are used to obtain symmetric quadrature approximations of any degree of precision up to five for arbitrary integrals over the three fundamental domains. Using a coordinate-free formulation, simple and rational procedures are developed to derive virtually all quadrature formulas, including some previously unpublished. Four symmetry groups of quadrature points are introduced to derive Gauss formulas, while their limiting forms are used to derive Lobatto formulas. Representative Gauss and Lobatto formulas are tabulated. The relative efficiency of their application to polyhedral and polygonal grids is detailed. The extension to higher degrees of precision is discussed.

  8. TIGGERC: Turbomachinery Interactive Grid Generator for 2-D Grid Applications and Users Guide

    NASA Technical Reports Server (NTRS)

    Miller, David P.

    1994-01-01

    A two-dimensional multi-block grid generator has been developed for a new design and analysis system for studying multiple blade-row turbomachinery problems. TIGGERC is a mouse driven, interactive grid generation program which can be used to modify boundary coordinates and grid packing and generates surface grids using a hyperbolic tangent or algebraic distribution of grid points on the block boundaries. The interior points of each block grid are distributed using a transfinite interpolation approach. TIGGERC can generate a blocked axisymmetric H-grid, C-grid, I-grid or O-grid for studying turbomachinery flow problems. TIGGERC was developed for operation on Silicon Graphics workstations. Detailed discussion of the grid generation methodology, menu options, operational features and sample grid geometries are presented.

  9. An Adaptively-Refined, Cartesian, Cell-Based Scheme for the Euler and Navier-Stokes Equations. Ph.D. Thesis - Michigan Univ.

    NASA Technical Reports Server (NTRS)

    Coirier, William John

    1994-01-01

    A Cartesian, cell-based scheme for solving the Euler and Navier-Stokes equations in two dimensions is developed and tested. Grids about geometrically complicated bodies are generated automatically, by recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, polygonal 'cut' cells are created. The geometry of the cut cells is computed using polygon-clipping algorithms. The grid is stored in a binary-tree data structure which provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite-volume formulation. The convective terms are upwinded, with a limited linear reconstruction of the primitive variables used to provide input states to an approximate Riemann solver for computing the fluxes between neighboring cells. A multi-stage time-stepping scheme is used to reach a steady-state solution. Validation of the Euler solver with benchmark numerical and exact solutions is presented. An assessment of the accuracy of the approach is made by uniform and adaptive grid refinements for a steady, transonic, exact solution to the Euler equations. The error of the approach is directly compared to a structured solver formulation. A non smooth flow is also assessed for grid convergence, comparing uniform and adaptively refined results. Several formulations of the viscous terms are assessed analytically, both for accuracy and positivity. The two best formulations are used to compute adaptively refined solutions of the Navier-Stokes equations. These solutions are compared to each other, to experimental results and/or theory for a series of low and moderate Reynolds numbers flow fields. The most suitable viscous discretization is demonstrated for geometrically-complicated internal flows. For flows at high Reynolds numbers, both an altered grid-generation procedure and a different formulation of the viscous terms are shown to be necessary. A hybrid Cartesian/body-fitted grid generation approach is demonstrated. In addition, a grid-generation procedure based on body-aligned cell cutting coupled with a viscous stensil-construction procedure based on quadratic programming is presented.

  10. An Efficient Means of Adaptive Refinement Within Systems of Overset Grids

    NASA Technical Reports Server (NTRS)

    Meakin, Robert L.

    1996-01-01

    An efficient means of adaptive refinement within systems of overset grids is presented. Problem domains are segregated into near-body and off-body fields. Near-body fields are discretized via overlapping body-fitted grids that extend only a short distance from body surfaces. Off-body fields are discretized via systems of overlapping uniform Cartesian grids of varying levels of refinement. a novel off-body grid generation and management scheme provides the mechanism for carrying out adaptive refinement of off-body flow dynamics and solid body motion. The scheme allows for very efficient use of memory resources, and flow solvers and domain connectivity routines that can exploit the structure inherent to uniform Cartesian grids.

  11. A HYBRID SOLAR WIND MODEL OF THE CESE+HLL METHOD WITH A YIN-YANG OVERSET GRID AND AN AMR GRID

    SciTech Connect

    Feng Xueshang; Zhang Shaohua; Xiang Changqing; Yang Liping; Jiang Chaowei [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Wu, S. T., E-mail: fengx@spaceweather.ac.cn [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, AL 35899 (United States)

    2011-06-10

    A hybrid three-dimensional (3D) MHD model for solar wind study is proposed in the present paper with combined grid systems and solvers. The computational domain from the Sun to Earth space is decomposed into the near-Sun and off-Sun domains, which are respectively constructed with a Yin-Yang overset grid system and a Cartesian adaptive mesh refinement (AMR) grid system and coupled with a domain connection interface in the overlapping region between the near-Sun and off-Sun domains. The space-time conservation element and solution element method is used in the near-Sun domain, while the Harten-Lax-Leer method is employed in the off-Sun domain. The Yin-Yang overset grid can avoid well-known singularity and polar grid convergence problems and its body-fitting property helps achieve high-quality resolution near the solar surface. The block structured AMR Cartesian grid can automatically capture far-field plasma flow features, such as heliospheric current sheets and shock waves, and at the same time, it can save significant computational resources compared to the uniformly structured Cartesian grid. A numerical study of the solar wind structure for Carrington rotation 2069 shows that the newly developed hybrid MHD solar wind model successfully produces many realistic features of the background solar wind, in both the solar corona and interplanetary space, by comparisons with multiple solar and interplanetary observations.

  12. A Hybrid Solar Wind Model of the CESE+HLL Method with a Yin-Yang Overset Grid and an AMR Grid

    NASA Astrophysics Data System (ADS)

    Feng, Xueshang; Zhang, Shaohua; Xiang, Changqing; Yang, Liping; Jiang, Chaowei; Wu, S. T.

    2011-06-01

    A hybrid three-dimensional (3D) MHD model for solar wind study is proposed in the present paper with combined grid systems and solvers. The computational domain from the Sun to Earth space is decomposed into the near-Sun and off-Sun domains, which are respectively constructed with a Yin-Yang overset grid system and a Cartesian adaptive mesh refinement (AMR) grid system and coupled with a domain connection interface in the overlapping region between the near-Sun and off-Sun domains. The space-time conservation element and solution element method is used in the near-Sun domain, while the Harten-Lax-Leer method is employed in the off-Sun domain. The Yin-Yang overset grid can avoid well-known singularity and polar grid convergence problems and its body-fitting property helps achieve high-quality resolution near the solar surface. The block structured AMR Cartesian grid can automatically capture far-field plasma flow features, such as heliospheric current sheets and shock waves, and at the same time, it can save significant computational resources compared to the uniformly structured Cartesian grid. A numerical study of the solar wind structure for Carrington rotation 2069 shows that the newly developed hybrid MHD solar wind model successfully produces many realistic features of the background solar wind, in both the solar corona and interplanetary space, by comparisons with multiple solar and interplanetary observations.

  13. Eighteenth century optics: the Cartesian-Newtonian conflict.

    PubMed

    Pav, P A

    1975-12-01

    The eighteenth century is often regarded as a period when optics was stultified by Newton's dominant influence and the controversy of two rival hypotheses: the wave theory and the corpuscular theory of light. However, a study of the controversial development of achromatic lenses reveals a deeper underlying conflict between two different types of mechanistic philosophy-one Newtonian and the other Cartesian. This conflict, both methodological and cosmological, pitted inductivism against deductivism. Two pivotal issues were the role of mathematics and the nature of experimentation. Here we have a clear example of h e interaction of science and philosophy. PMID:20155161

  14. Analysis of Low-Momentum Correlations with Cartesian Harmonics

    E-print Network

    P. Danielewicz; S. Pratt

    2005-05-18

    Exploiting final-state interactions and/or identity interference, analysis of anisotropic correlations of particles at low-relative velocities yields information on the anisotropy of emission sources in heavy-ion reactions. We show that the use of cartesian surface-spherical harmonics in such analysis allows for a systematic expansion of the correlations in terms of real angular-moment coefficients dependent on relative momentum. The coefficients are directly related to the analogous coefficients for emission sources. We illustrate the analysis with an example of correlations generated by classical Coulomb interaction.

  15. Parallel implementation of the Dirac equation in three Cartesian dimensions

    SciTech Connect

    Wells, J.C.; Strayer, M.R. [Oak Ridge National Lab., TN (United States); Oberacker, V.E.; Umar, A.S. [Oak Ridge National Lab., TN (United States)]|[Vanderbilt Univ., Nashville, TN (United States). Dept. of Physics and Astronomy

    1994-09-01

    We describe the numerical methods used to solve the time-dependent Dirac equation on a three-dimensional Cartesian lattice. Efficient algorithms are required for computationally intensive studies of vacuum-pair production in relativistic heavy-ion collisions. Discretization is achieved through the lattice-collocation method. All numerical procedures reduce to a series of matrix-vector operations which we perform on the Intel iPSC/860 hypercube, making full use of parallelism. We discuss our solutions to the problems of limited node memory and node-to-node communication overhead inherent in using distributed-memory, multiple-instruction, multiple-data stream parallel computers.

  16. Highly Energy-Conservative Finite Difference Method for the Cylindrical Coordinate System

    Microsoft Academic Search

    Koji Fukagata; Nobuhide Kasagi

    2002-01-01

    A highly energy-conservative second-order-accurate finite difference method for the cylindrical coordinate system is developed. It is rigorously proved that energy conservation in discretized space is satisfied when appropriate interpolation schemes are used. This argument holds not only for an unequally spaced mesh but also for an equally spaced mesh on cylindrical coordinates but not on Cartesian coordinates. Numerical tests are

  17. Internal Coordinate Molecular Dynamics Based on the Spectroscopic B-Matrix

    Microsoft Academic Search

    Sang-Ho Lee; Kim Palmo; Samuel Krimm

    \\u000a Internal coordinate molecular dynamics (ICMD) has been used in the past in simulations for large molecules as an alternative\\u000a way of increasing step size with a reduced operational dimension that is not achievable by MD in Cartesian coordinates. A\\u000a new MD formalism in nonredundant generalized (internal and external) coordinates for flexible molecular systems is presented,\\u000a which is based on the

  18. Ontology-Based Resource Matching in the Grid - The Grid Meets the Semantic Web

    Microsoft Academic Search

    Hongsuda Tangmunarunkit; Stefan Decker; Carl Kesselman

    2003-01-01

    The Grid is an emerging technology for enabling resource sharing and coordinated problem solving in dynamic multi-institutional virtual organizations. In the Grid environment, shared resources and users typically span different orga- nizations. The resource matching problem in the Grid involves assigning resources to tasks in order to satisfy task requirements and resource policies. These require- ments and policies are often

  19. Multi-moment advection schemes for Cartesian grids and cut cells 

    E-print Network

    Ferrier, Richard James

    2014-11-27

    Computational fluid dynamics has progressed to the point where it is now possible to simulate flows with large eddy turbulence, free surfaces and other complex features. However, the success of these models often depends ...

  20. Cartesian grid simulations of bubbling fluidized beds with a horizontal tube bundle

    SciTech Connect

    Li, Tingwen; Dietiker, Jean-Francois; Zhang, Yongmin; Shahnam, Mehrdad

    2011-12-01

    In this paper, the flow hydrodynamics in a bubbling fluidized bed with submerged horizontal tube bundle was numerically investigated with an open-source code: Multiphase Flow with Interphase eXchange (MFIX). A newly implemented cut-cell technique was employed to deal with the curved surface of submerged tubes. A series of 2D simulations were conducted to study the effects of gas velocity and tube arrangement on the flow pattern. Hydrodynamic heterogeneities on voidage, particle velocity, bubble fraction, and frequency near the tube circumferential surface were successfully predicted by this numerical method, which agrees qualitatively with previous experimental findings and contributes to a sounder understanding of the non-uniform heat transfer and erosion around a horizontal tube. A 3D simulation was also conducted. Significant differences between 2D and 3D simulations were observed with respect to bed expansion, bubble distribution, voidage, and solids velocity profiles. Hence, the 3D simulation is needed for quantitative prediction of flow hydrodynamics. On the other hand, the flow characteristics and bubble behavior at the tube surface are similar under both 2D and 3D simulations as far as the bubble frequency and bubble phase fraction are concerned. Comparison with experimental data showed that qualitative agreement was obtained in both 2D and 3D simulations for the bubble characteristics at the tube surface.

  1. An adaptive discretization of incompressible flow using a multitude of moving Cartesian grids

    E-print Network

    Fedkiw, Ron

    intricate aspect of any such discretization is the method used in order to solve the elliptic equation that a robust second order accurate symmetric positive definite readily preconditioned discretization can to the Voronoi mesh in both the viscosity and pressure solves. We independently demonstrate each aspect of our

  2. An adaptive discretization of incompressible flow using a multitude of moving Cartesian grids

    E-print Network

    Bejerano, Gill

    for the parabolic terms, such as the heat equation and Navier-Stokes viscosity. The most intricate aspect of any order accurate symmetric positive definite readily preconditioned discretization can be obtained aspect of our approach on test problems in order to show efficacy and convergence before finally

  3. Lessons learned through driving science applications in the PRAGMA grid

    Microsoft Academic Search

    Cindy Zheng; Mason J. Katz; Philip M. Papadopoulos; David Abramson; Shahaan Ayyub; Colin Enticott; Slavisa Garic; Wojtek Goscinski; Peter W. Arzberger; Bu-sung Lee; Sugree Phatanapherom; Somsak Sriprayoonsakul; Putchong Uthayopas; Yoshio Tanaka; Yusuke Tanimura

    2007-01-01

    This paper describes the coordination, design and implementation of the PRAGMA Grid. Applications in genomics, quantum mechanics, climate simulation, organic chemistry and molecular simulation have driven the middleware requirements, and the PRAGMA Grid provides a mechanism for

  4. TeraGrid

    NSDL National Science Digital Library

    TeraGrid is an open scientific discovery infrastructure combining leadership class resources at nine partner sites to create an integrated, persistent computational resource. Using high-performance network connections, the TeraGrid integrates high-performance computers, data resources and tools, and high-end experimental facilities around the country. These integrated resources include more than 102 teraflops of computing capability and more than 15 petabytes (quadrillions of bytes) of online and archival data storage with rapid access and retrieval over high-performance networks. Through the TeraGrid, researchers can access over 100 discipline-specific databases. With this combination of resources, the TeraGrid is the world's largest, most comprehensive distributed cyberinfrastructure for open scientific research. TeraGrid is coordinated through the Grid Infrastructure Group (GIG) at the University of Chicago, working in partnership with the Resource Provider sites: Indiana University, Oak Ridge National Laboratory, National Center for Supercomputing Applications, Pittsburgh Supercomputing Center, Purdue University, San Diego Supercomputer Center, Texas Advanced Computing Center, University of Chicago/Argonne National Laboratory, and the National Center for Atmospheric Research.

  5. Polar Coordinates and Multiplication In the last chapter we wrote complex numbers in the form x + iy where x

    E-print Network

    Wortman, Kevin

    Polar Coordinates and Multiplication In the last chapter we wrote complex numbers in the form x + iy where x and y are real numbers. We can think of this as writing complex numbers using Cartesian coordinates. Every complex number is the sum of a number on the real axis and a number on the imaginary axis

  6. Evolution of Optimal ANNs for Non-Linear Control Problems using Cartesian Genetic Programming

    E-print Network

    Fernandez, Thomas

    networks using genetic algorithms. Numerous applications such as face recognition, manufacturing, aircraftEvolution of Optimal ANNs for Non-Linear Control Problems using Cartesian Genetic Programming networks using Cartesian Genetic Programming (CGPANN) is proposed. The CGPANN technique encodes the neural

  7. 1 Cartesian bicategories We now expand the scope of application of system Beta, by generalizing the

    E-print Network

    Brady, Geraldine

    1 Cartesian bicategories We now expand the scope of application of system Beta, by generalizing between a cartesian bicategory B and the subbicategory Map(B) whose arrows are the left adjoints in B, called maps. In the case of sets and relations, maps are precisely functions, whereas for categories

  8. Extending a CAD-Based Cartesian Mesh Generator for the Lattice Boltzmann Method

    SciTech Connect

    Cantrell, J Nathan [ORNL] [ORNL; Inclan, Eric J [ORNL] [ORNL; Joshi, Abhijit S [ORNL] [ORNL; Popov, Emilian L [ORNL] [ORNL; Jain, Prashant K [ORNL] [ORNL

    2012-01-01

    This paper describes the development of a custom preprocessor for the PaRAllel Thermal Hydraulics simulations using Advanced Mesoscopic methods (PRATHAM) code based on an open-source mesh generator, CartGen [1]. PRATHAM is a three-dimensional (3D) lattice Boltzmann method (LBM) based parallel flow simulation software currently under development at the Oak Ridge National Laboratory. The LBM algorithm in PRATHAM requires a uniform, coordinate system-aligned, non-body-fitted structured mesh for its computational domain. CartGen [1], which is a GNU-licensed open source code, already comes with some of the above needed functionalities. However, it needs to be further extended to fully support the LBM specific preprocessing requirements. Therefore, CartGen is being modified to (i) be compiler independent while converting a neutral-format STL (Stereolithography) CAD geometry to a uniform structured Cartesian mesh, (ii) provide a mechanism for PRATHAM to import the mesh and identify the fluid/solid domains, and (iii) provide a mechanism to visually identify and tag the domain boundaries on which to apply different boundary conditions.

  9. coordinate plane

    NSDL National Science Digital Library

    olsen

    2010-10-07

    Become familiar with the coordinate plane. Learn the quadrants and how to graph points and read points on a coordinate plane. You are required to do the assignment and take the quiz. The other resources are to help prepare you for the quiz and book assignment. This is a quick review of the lesson.The Coordinate Plane This is a game to practice plotting and reading points.coordinates game *Assignment: Watch Powerpoint 3.3 and fill in your ...

  10. Accurate direct georeferencing of aerial imagery in national coordinates

    NASA Astrophysics Data System (ADS)

    Shen, Xiang; Zhang, Yongjun; Li, Qingquan

    2015-07-01

    In aerial photogrammetry, data products are commonly needed in national coordinates, and, in practice, the georeferencing is often performed in the required national map projection frame directly. However, as a map projection frame is not Cartesian, some additional corrections are necessary in the georeferencing process to take account of various map projection distortions. This paper presents a new map projection correction method for the direct georeferencing of aerial images in national coordinates, which comprises of three consecutive steps: (1) a rough intersection to predict ground point coordinates in the Cartesian space; (2) calculating map projection corrections; and (3) a fine intersection. Benefiting from the explicit estimation of ground positions in the Cartesian space, our new method can directly adopt the accurate map projection distortion model that was previously developed for the direct georeferencing of airborne LiDAR data in national coordinates. Simulations show that the correction residuals of our new method are smaller by one order of magnitude than those of the previous best approach while their computational costs are at the same level, and even in an extreme scenario of 8000 m flight height above ground, the maximum error of our method is only several centimeters, which can be safely neglected in practical applications.

  11. Simulation of disk-disk encounters with co-moving polar grids

    NASA Technical Reports Server (NTRS)

    Salo, Heikki

    1990-01-01

    The two-grid simulation method combining advantages of both polar and Cartesian mesh-codes is described. In addition to the stellar component reacting solely to gravitational forces, the gas component is included with dissipatively colliding particles. This allows fairly realistic simulation of planar encounters where both systems contain star plus gas disks.

  12. Towards Hybrid Overset Grid Simulations of the Launch Environment

    NASA Astrophysics Data System (ADS)

    Moini-Yekta, Shayan

    A hybrid overset grid approach has been developed for the design and analysis of launch vehicles and facilities in the launch environment. The motivation for the hybrid grid methodology is to reduce the turn-around time of computational fluid dynamic simulations and improve the ability to handle complex geometry and flow physics. The LAVA (Launch Ascent and Vehicle Aerodynamics) hybrid overset grid scheme consists of two components: an off-body immersed-boundary Cartesian solver with block-structured adaptive mesh refinement and a near-body unstructured body-fitted solver. Two-way coupling is achieved through overset connectivity between the off-body and near-body grids. This work highlights verification using code-to-code comparisons and validation using experimental data for the individual and hybrid solver. The hybrid overset grid methodology is applied to representative unsteady 2D trench and 3D generic rocket test cases.

  13. Skew grids and irrotational flow

    NASA Astrophysics Data System (ADS)

    Bernard, Robert S.

    1988-03-01

    Finite-difference computation of incompressible flow through regions of arbitrary shape often requires the implementation of boundary-fitted coordinates for which the grid lines may be non-orthogonal (skew). When the governing equations are expressed in terms of pressure and velocity, conservation of mass is maintained by the gradient of the pressure. In principle, the gradient is irrotational and should have no effect on the existing circulation in the flow field; but if the grid lines are skew, the discrete representation of the gradient can generate spurious vorticity near the boundaries. In the present work this difficulty is eliminated for uniform skew grids, and markedly reduced for non-uniform skew grids, by adopting a discrete formulation of the pressure gradient that helps maintain irrotationality near boundaries. The procedure is applicable for staggered grids with either Poisson or Chorin equations for pressure.

  14. Grids = Structure.

    ERIC Educational Resources Information Center

    Barrington, Linda; Carter, Jacky

    2003-01-01

    Proposes that narrow columns provide a flexible system of organization for designers. Notes that grids serve the content on the pages, help to develop a layout that will clearly direct the reader to information; and prevent visual monotony. Concludes when grid layouts are used, school publications look as good as professional ones. (PM)

  15. Sustainable Coordination

    Microsoft Academic Search

    Martin Fredriksson; Rune Gustavsson; Alessandro Ricci

    2003-01-01

    Coordination, accounting for the global coherence of system behaviour, is a fundamental aspect of complex multi-agent systems.\\u000a As such, coordination in multi-agent systems provides a suitable level of abstraction to deal with system organisation and\\u000a control. However, current coordination approaches in multi-agent systems are not always fully equipped to model and support\\u000a the global coherence of open computational systems, i.e.,

  16. Ray Tracing in a Sectioned and Layered Atmosphere Using a Shifting Coordinate System

    Microsoft Academic Search

    MICHAEL E. AUSTIN; WILLIAMM. ROSS

    1969-01-01

    Acoustical ray tracing in a horizontally layered and vertically sectioned atmosphere is accomplished on a digital computer using a shifting Cartesian coordinate system. The atmosphere is divided into vertical layers. In each of these layers straight line approximations of the variation of the speed-of-sound curve with altitude are used, thereby generating a constant radius of curvature for the acoustic ray

  17. Structural analysis of a curved beam element defined in global coordinates

    Microsoft Academic Search

    L. Gimena; F. N. Gimena; P. Gonzaga

    2008-01-01

    In this article, a system of twelve differential equations expressed in the global Cartesian coordinate system to simulate the structural behavior of a general curved beam element, is presented. Different shape geometry of the curved centroid line, shearing deformations, varying cross section area, non-symmetric section and generalized loads are taken into account. The lower-triangular form of the system of equations

  18. An improved method for calculating self-motion coordinates for redundant manipulators

    SciTech Connect

    Reister, D.B.

    1997-04-01

    For a redundant manipulator, the objective of redundancy resolution is to follow a specified path in Cartesian space and simultaneously perform another task (for example, maximize an objective function or avoid obstacles) at every point along the path. The conventional methods have several drawbacks: a new function must be defined for each task, the extended Jacobian can be singular, closed cycles in Cartesian space may not yield closed cycles in joint space, and the objective is point-wise redundancy resolution (to determine a single point in joint space for each point in Cartesian space). The author divides the redundancy resolution problem into two parts: (1) calculate self-motion coordinates for all possible positions of a manipulator at each point along a Cartesian path and (2) determination of optimal self-motion coordinates that maximize an objective function along the path. This paper will discuss the first part of the problem. The path-wise approach overcomes all of the drawbacks of conventional redundancy resolution methods: no need to define a new function for each task, extended Jacobian cannot be singular, and closed cycles in extended Cartesian space will yield closed cycles in joint space.

  19. Grid Vertex-Unfolding Orthogonal Polyhedra

    Microsoft Academic Search

    Mirela Damian; Robin Y. Flatland; Joseph O’Rourke

    2005-01-01

    Abstract An edge-unfolding of a polyhedron is produced by cutting along edges and ?attening the faces to a net, a connected planar piece with no overlaps. A grid unfolding allows additional cuts along grid edges induced by coordinate planes passing through every vertex. A vertexunfolding permits faces in the net to be connected at single vertices, not necessarily along edges.

  20. Unstructured Grid Generation Techniques and Software

    NASA Technical Reports Server (NTRS)

    Posenau, Mary-Anne K. (editor)

    1993-01-01

    The Workshop on Unstructured Grid Generation Techniques and Software was conducted for NASA to assess its unstructured grid activities, improve the coordination among NASA centers, and promote technology transfer to industry. The proceedings represent contributions from Ames, Langley, and Lewis Research Centers, and the Johnson and Marshall Space Flight Centers. This report is a compilation of the presentations made at the workshop.

  1. The National Grid Project: A system overview

    NASA Technical Reports Server (NTRS)

    Gaither, Adam; Gaither, Kelly; Jean, Brian; Remotigue, Michael; Whitmire, John; Soni, Bharat; Thompson, Joe; Dannenhoffer,, John; Weatherill, Nigel

    1995-01-01

    The National Grid Project (NGP) is a comprehensive numerical grid generation software system that is being developed at the National Science Foundation (NSF) Engineering Research Center (ERC) for Computational Field Simulation (CFS) at Mississippi State University (MSU). NGP is supported by a coalition of U.S. industries and federal laboratories. The objective of the NGP is to significantly decrease the amount of time it takes to generate a numerical grid for complex geometries and to increase the quality of these grids to enable computational field simulations for applications in industry. A geometric configuration can be discretized into grids (or meshes) that have two fundamental forms: structured and unstructured. Structured grids are formed by intersecting curvilinear coordinate lines and are composed of quadrilateral (2D) and hexahedral (3D) logically rectangular cells. The connectivity of a structured grid provides for trivial identification of neighboring points by incrementing coordinate indices. Unstructured grids are composed of cells of any shape (commonly triangles, quadrilaterals, tetrahedra and hexahedra), but do not have trivial identification of neighbors by incrementing an index. For unstructured grids, a set of points and an associated connectivity table is generated to define unstructured cell shapes and neighboring points. Hybrid grids are a combination of structured grids and unstructured grids. Chimera (overset) grids are intersecting or overlapping structured grids. The NGP system currently provides a user interface that integrates both 2D and 3D structured and unstructured grid generation, a solid modeling topology data management system, an internal Computer Aided Design (CAD) system based on Non-Uniform Rational B-Splines (NURBS), a journaling language, and a grid/solution visualization system.

  2. Approximations to wire grid inductance.

    SciTech Connect

    Warne, Larry Kevin; Johnson, William Arthur; Merewether, Kimball O.

    2004-06-01

    By using a multipole-conformal mapping expansion for the wire currents we examine the accuracy of approximations for the transfer inductance of a one dimensional array of wires (wire grid). A simple uniform fit is constructed by introduction of the decay factor from bipolar coordinates into existing formulas for this inductance.

  3. Information services for smart grids

    Microsoft Academic Search

    Roger L. King

    2008-01-01

    Interconnected and integrated electrical power systems, by their very dynamic nature are complex. These multifaceted systems are subject to a host of challenges - aging infrastructure, generation availability near load centers, transmission expansion to meet growing demands, distributed resources, dynamic reactive compensation, congestion management, grid ownership vs. system operation, reliability coordination, supply and cost of natural resources for generation, etc.

  4. MESH2D GRID GENERATOR DESIGN AND USE

    SciTech Connect

    Flach, G.; Smith, F.

    2012-01-20

    Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j{sub 0}) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations. The overall mesh is constructed from grid zones that are typically then subdivided into a collection of smaller grid cells. The grid zones usually correspond to distinct materials or larger-scale geometric shapes. The structured grid zones are identified through uppercase indices (I,J). Subdivision of zonal regions into grid cells can be done uniformly, or nonuniformly using either a polynomial or geometric skewing algorithm. Grid cells may be concentrated backward, forward, or toward both ends. Figure 1 illustrates the above concepts in the context of a simple four zone grid.

  5. A second-order Cartesian method for the simulation of electropermeabilization cell models

    NASA Astrophysics Data System (ADS)

    Leguèbe, M.; Poignard, C.; Weynans, L.

    2015-07-01

    In this paper, we present a new finite differences method to simulate electropermeabilization models, like the model of Neu and Krassowska or the recent model of Kavian et al. These models are based on the evolution of the electric potential in a cell embedded in a conducting medium. The main feature lies in the transmission of the voltage potential across the cell membrane: the jump of the potential is proportional to the normal flux thanks to the well-known Kirchoff law. An adapted scheme is thus necessary to accurately simulate the voltage potential in the whole cell, notably at the membrane separating the cell from the outer medium. We present a second-order finite differences scheme in the spirit of the method introduced by Cisternino and Weynans for elliptic problems with immersed interfaces. This is a Cartesian grid method based on the accurate discretization of the fluxes at the interface, through the use of additional interface unknowns. The main novelty of our present work lies in the fact that the jump of the potential is proportional to the flux, and therefore is not explicitly known. The original use of interface unknowns makes it possible to discretize the transmission conditions with enough accuracy to obtain a second-order spatial convergence. We prove the second-order spatial convergence in the stationary linear one-dimensional case, and the first-order temporal convergence for the dynamical non-linear model in one dimension. We then perform numerical experiments in two dimensions that corroborate these results.

  6. Roman domination in Cartesian product graphs and strong product graphs

    E-print Network

    Yero, Ismael G

    2011-01-01

    A set $S$ of vertices of a graph $G$ is a dominating set for $G$ if every vertex outside of $S$ is adjacent to at least one vertex belonging to $S$. The minimum cardinality of a dominating set for $G$ is called the domination number of $G$. A map $f : V \\rightarrow \\{0, 1, 2\\}$ is a Roman dominating function on a graph $G$ if for every vertex $v$ with $f(v) = 0$, there exists a vertex $u$, adjacent to $v$, such that $f(u) = 2$. The weight of a Roman dominating function is given by $f(V) =\\sum_{u\\in V}f(u)$. The minimum weight of a Roman dominating function on $G$ is called the Roman domination number of $G$. In this article we study the Roman domination number of Cartesian product graphs and strong product graphs. More precisely, we study the relationships between the Roman domination number of product graphs and the (Roman) domination number of the factors.

  7. Advanced Fluid Dynamics 2013 Navier Stokes equation in curvilinear coordinate systems

    E-print Network

    Hogg, Andrew

    . Cylindrical polar coordinates (r, , z) The cylindrical polar system is related to Cartesian coordinates (x, y, z) by x = r cos and y = r sin , where r > 0 and 0 r, , z) and the velocity field u = ur^r + u + uz^z, we find that · (x, y, z) (r, , z) = r. · F = ^r F r + ^ 1 r F + ^z F z

  8. Ask Not What You Can Do for Yourself: Cartesian Chaos, Neural Dynamics, and Immunological Cognition

    Microsoft Academic Search

    Seán Ó Nualláin

    2010-01-01

    This paper focuses on the disparate phenomena we psychologize as “selfhood”. A central argument is that, far from being a\\u000a deus ex machina as required in the Cartesian schema, our felt experience of self is above all a consequence of data compression.\\u000a In coming to this conclusion, it considers in turn the Cartesian epiphany, other traditional and contemporary perspectives,\\u000a and

  9. Geometrical method for modeling of asymmetric 6×6 Cartesian stiffness matrix

    Microsoft Academic Search

    Shih-Feng Chen; Imin Kaot

    2000-01-01

    In this paper, we study the 6×6 Cartesian stiffness matrices of conservative systems using the method of changing basis in differential geometry of the motion of the rigid body. We show that the stiffness matrix is symmetric at the unloaded equilibrium configuration. When the system is subjected to external loads, the 6×6 Cartesian stiffness matrix becomes asymmetric. The skew-symmetric part

  10. Conservative Congruence Transformation for Joint and Cartesian Stiffness Matrices of Robotic Hands and Fingers

    Microsoft Academic Search

    Shih-feng Chen; Imin Kao

    2000-01-01

    In this paper, we develop the theoretical work on the properties and mapping of stiffness matrices between joint and Cartesian spaces of robotic hands and fingers, and propose the conservative congruence transformation (CCT). In this paper, we show that the conventional formulation between the joint and Cartesian spaces, K&thgr; = JT&thgr;KpJ&thgr;, first derived by Salisbury in 1980, is only valid

  11. Grid oscillators

    NASA Technical Reports Server (NTRS)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  12. Numerical solution of the full potential equation using a chimera grid approach

    NASA Technical Reports Server (NTRS)

    Holst, Terry L.

    1995-01-01

    A numerical scheme utilizing a chimera zonal grid approach for solving the full potential equation in two spatial dimensions is described. Within each grid zone a fully-implicit approximate factorization scheme is used to advance the solution one interaction. This is followed by the explicit advance of all common zonal grid boundaries using a bilinear interpolation of the velocity potential. The presentation is highlighted with numerical results simulating the flow about a two-dimensional, nonlifting, circular cylinder. For this problem, the flow domain is divided into two parts: an inner portion covered by a polar grid and an outer portion covered by a Cartesian grid. Both incompressible and compressible (transonic) flow solutions are included. Comparisons made with an analytic solution as well as single grid results indicate that the chimera zonal grid approach is a viable technique for solving the full potential equation.

  13. Uni Innsbruck InformatikUni Innsbruck Informatik --11 Grid InterNetworkingGrid InterNetworking

    E-print Network

    Welzl, Michael

    concept is coordinated resource sharing and problem solving in dynamic, multi institutional virtual organizations [Ian Foster, Carl Kesselman and Steven Tuecke, "The Anatomy of the Grid ­ Enabling Scalable Virtual Organizations", International Journal on Supercomputer Applications, 2001] #12;Uni Innsbruck

  14. Run-time Optimization for Grid Workflow Applications

    Microsoft Academic Search

    Rubing Duan; Radu Prodan; Thomas Fahringer

    The execution of workflow applications on the Grid is a complex issue because of its dynamic and heterogeneous nature. While the Grid provides good potential for achieving high performance, it also introduces a broad set of unpredictable overheads and possible failures. In this paper we present new methods for scalable and fault tolerant coordination of workflows in dynamic Grid environments,

  15. Astronomical Coordinates

    NSDL National Science Digital Library

    David Joiner

    The celestial coordinate system is a projection of earth's coordinate system into the celestial sphere. Being just like Earth's system it contains an "equator", lines of "latitude" and "longitude", and even poles. (Though we don't use the same words for it.) One suggestion one might have would be to just extend the Earth's latitude, longitude, and equator out into the night sky, but the Earth is constantly spinning. For the Celestial coordinates, we have to pick some fixed reference to go by.

  16. Simplified Cartesian basis model for intrapolyad emission intensities in the bent-to-linear electronic transition of acetylene.

    PubMed

    Park, G Barratt; Steeves, Adam H; Baraban, Joshua H; Field, Robert W

    2015-02-01

    The acetylene emission spectrum from the trans-bent electronically excited à state to the linear ground electronic X? state has attracted considerable attention because it grants Franck–Condon access to local bending vibrational levels of the X? state with large-amplitude motion along the acetylene ? vinylidene isomerization coordinate. For emission from the ground vibrational level of the à state, there is a simplifying set of Franck–Condon propensity rules that gives rise to only one zero-order bright state per conserved vibrational polyad of the X? state. Unfortunately, when the upper level involves excitation in the highly admixed ungerade bending modes, ?4? and ?6?, the simplifying Franck–Condon propensity rule breaks down--as long as the usual polar basis (with v and l quantum numbers) is used to describe the degenerate bending vibrations of the X? state--and the intrapolyad intensities result from complicated interference patterns between many zero-order bright states. In this article, we show that, when the degenerate bending levels are instead treated in the Cartesian two-dimensional harmonic oscillator basis (with vx and vy quantum numbers), the propensity for only one zero-order bright state (in the Cartesian basis) is restored, and the intrapolyad intensities are simple to model, as long as corrections are made for anharmonic interactions. As a result of trans ? cis isomerization in the à state, intrapolyad emission patterns from overtones of ?4? and ?6? evolve as quanta of trans bend (?3?) are added, so the emission intensities are not only relevant to the ground-state acetylene ? vinylidene isomerization, they are also a direct reporter of isomerization in the electronically excited state. PMID:25625552

  17. On deriving nonreflecting boundary conditions in generalized curvilinear coordinates

    E-print Network

    Adrian Sescu

    2015-01-20

    In this work, nonreflecting boundary conditions in generalized three-dimensional curvilinear coordinates are derived, relying on the original analysis that was done in Cartesian two-dimensional coordinates by Giles (AIAA Journal, 28.12, 2050-2058, 1990). A thorough Fourier analysis of the linearized Euler equation is performed to determine the eigenvalues and the eigenvectors that are then used to derive the appropriate inflow and outflow boundary conditions. The analysis lacks rigorous proof of the well-posedness in the general case, which is open to investigation (a weak assumption is introduced here to complete the boundary conditions). The boundary conditions derived here are not tested on specific applications.

  18. Solving Partial Differential Equations on Overlapping Grids

    SciTech Connect

    Henshaw, W D

    2008-09-22

    We discuss the solution of partial differential equations (PDEs) on overlapping grids. This is a powerful technique for efficiently solving problems in complex, possibly moving, geometry. An overlapping grid consists of a set of structured grids that overlap and cover the computational domain. By allowing the grids to overlap, grids for complex geometries can be more easily constructed. The overlapping grid approach can also be used to remove coordinate singularities by, for example, covering a sphere with two or more patches. We describe the application of the overlapping grid approach to a variety of different problems. These include the solution of incompressible fluid flows with moving and deforming geometry, the solution of high-speed compressible reactive flow with rigid bodies using adaptive mesh refinement (AMR), and the solution of the time-domain Maxwell's equations of electromagnetism.

  19. Geoboard - Coordinate

    NSDL National Science Digital Library

    1999-01-01

    This interactive Java applet lets users explore the coordinate plane through the use of a Geoboard. The user places bands on the board where each peg is at an integer coordinate. Once a band has been placed, the applet outputs the perimeter and area of the shape or, if bands are placed as line segments, the applet outputs the distance and slope of the segment.

  20. Smart Grid Impact on Intelligent Buildings 

    E-print Network

    Zimmer, R. J.

    2013-01-01

    OF DIRECTORS 3 Making?the?Grid?Smart Smart?grid?features?expand?energy? efficiency?beyond?the?grid?into? buildings?by?coordinating?low?priority? energy?consuming?devices?to?take? advantage?of?the?most?desirable? energy?sources Smart...?new?products,?services,?and?markets ? Provides?the?power?quality?for?the?range?of?needs ? Optimizes?asset?utilization?and?operating?efficiently;?and ? Operates?resiliently?to?disturbance,?attacks,?and?natural?disasters An?advanced?power?grid?for?the?21st?century ...? adding...

  1. MammoGrid: A Service Oriented Architecture Based Medical Grid Application

    Microsoft Academic Search

    Salvator Roberto Amendolia; Mohammad Waseem Hassan; Tamas Hauer; David Manset; Richard Mcclatchey; Dmitri Rogulin; Tony Solomonides

    2004-01-01

    The MammoGrid project has recently delivered its first proof-of-concept prototype using a Service-Oriented Architecture (SOA)-based Grid application to enable distributed com- puting spanning national borders. The underlying AliEn Grid infrastructure has been se- lected because of its practicality and because of its emergence as a potential open source standards-based solution for managing and coordinating distributed resources. The resul- tant prototype

  2. A computer program for converting rectangular coordinates to latitude-longitude coordinates

    USGS Publications Warehouse

    Rutledge, A.T.

    1989-01-01

    A computer program was developed for converting the coordinates of any rectangular grid on a map to coordinates on a grid that is parallel to lines of equal latitude and longitude. Using this program in conjunction with groundwater flow models, the user can extract data and results from models with varying grid orientations and place these data into grid structure that is oriented parallel to lines of equal latitude and longitude. All cells in the rectangular grid must have equal dimensions, and all cells in the latitude-longitude grid measure one minute by one minute. This program is applicable if the map used shows lines of equal latitude as arcs and lines of equal longitude as straight lines and assumes that the Earth 's surface can be approximated as a sphere. The program user enters the row number , column number, and latitude and longitude of the midpoint of the cell for three test cells on the rectangular grid. The latitude and longitude of boundaries of the rectangular grid also are entered. By solving sets of simultaneous linear equations, the program calculates coefficients that are used for making the conversion. As an option in the program, the user may build a groundwater model file based on a grid that is parallel to lines of equal latitude and longitude. The program reads a data file based on the rectangular coordinates and automatically forms the new data file. (USGS)

  3. Einstein Index Notation for Cartesian Vectors Grant W. Mason

    E-print Network

    Hart, Gus

    in straightforward ways. It was used by Albert Einstein as the original language of his General Theory of Relativity of Relativity. The mathematical formalism can be used to give the general expressions for the divergence, curl and Laplacian in generalized coordinates. Strictly speaking, a vector is a mathematical object that is useful

  4. Radiation heat transfer model using Monte Carlo ray tracing method on hierarchical ortho-Cartesian meshes and non-uniform rational basis spline surfaces for description of boundaries

    NASA Astrophysics Data System (ADS)

    Kuczy?ski, Pawe?; Bia?ecki, Ryszard

    2014-06-01

    The paper deals with a solution of radiation heat transfer problems in enclosures filled with nonparticipating medium using ray tracing on hierarchical ortho-Cartesian meshes. The idea behind the approach is that radiative heat transfer problems can be solved on much coarser grids than their counterparts from computational fluid dynamics (CFD). The resulting code is designed as an add-on to OpenFOAM, an open-source CFD program. Ortho-Cartesian mesh involving boundary elements is created based upon CFD mesh. Parametric non-uniform rational basis spline (NURBS) surfaces are used to define boundaries of the enclosure, allowing for dealing with domains of complex shapes. Algorithm for determining random, uniformly distributed locations of rays leaving NURBS surfaces is described. The paper presents results of test cases assuming gray diffusive walls. In the current version of the model the radiation is not absorbed within gases. However, the ultimate aim of the work is to upgrade the functionality of the model, to problems in absorbing, emitting and scattering medium projecting iteratively the results of radiative analysis on CFD mesh and CFD solution on radiative mesh.

  5. Coordinates Constellations

    E-print Network

    Walter, Frederick M.

    ;Ecliptic Coordinates #12;Earth's Orbit #12;Analemma The position of the Sun at civil noon (standard time). This demonstrates: ·The inclination of the ecliptic ·The equation of time ·The non-circularity of Earth's orbit #12;Constellations · There are about 6000 stars visible to the naked eye under good conditions · About 2000

  6. COORDINATED AV.

    ERIC Educational Resources Information Center

    CLEAVES, PAUL C.; AND OTHERS

    THE INSTRUCTIONAL MATERIALS CENTER IS LOCATED IN THE LOCAL HIGH SCHOOL AND SUPPLIES ALL SCHOOLS IN THE AREA. AUDIOVISUAL EQUIPMENT ORDERS, AFTER SELECTIONS ARE MADE BY THE CLASSROOM TEACHER, ARE PROCESSED BY THE CENTER, CONFIRMED AND DELIVERED BY TRUCK THREE TIMES EACH WEEK. EACH SCHOOL HAS A BUILDING COORDINATOR WHO CHECKS THE ORDERS INTO THE…

  7. COMPARISON OF THE ACCURACY OF VARIOUS SPATIAL DISCRETIZATION SCHEMES OF THE DISCRETE ORDINATES EQUATIONS IN 2D CARTESIAN GEOMETRY

    SciTech Connect

    Sebastian Schunert; Yousry Y. Azmy; Damien Fournier

    2011-05-01

    We present a comprehensive error estimation of four spatial discretization schemes of the two-dimensional Discrete Ordinates (SN) equations on Cartesian grids utilizing a Method of Manufactured Solution (MMS) benchmark suite based on variants of Larsen’s benchmark featuring different orders of smoothness of the underlying exact solution. The considered spatial discretization schemes include the arbitrarily high order transport methods of the nodal (AHOTN) and characteristic (AHOTC) types, the discontinuous Galerkin Finite Element method (DGFEM) and the recently proposed higher order diamond difference method (HODD) of spatial expansion orders 0 through 3. While AHOTN and AHOTC rely on approximate analytical solutions of the transport equation within a mesh cell, DGFEM and HODD utilize a polynomial expansion to mimick the angular flux profile across each mesh cell. Intuitively, due to the higher degree of analyticity, we expect AHOTN and AHOTC to feature superior accuracy compared with DGFEM and HODD, but at the price of potentially longer grind times and numerical instabilities. The latter disadvantages can result from the presence of exponential terms evaluated at the cell optical thickness that arise from the semianalytical solution process. This work quantifies the order of accuracy and the magnitude of the error of all four discretization methods for different optical thicknesses, scattering ratios and degrees of smoothness of the underlying exact solutions in order to verify or contradict the aforementioned intuitive expectation.

  8. Inspection of hexagonal and triangular C-grid discretizations of the shallow water equations

    Microsoft Academic Search

    Almut Gassmann

    2011-01-01

    C-grid discretizations based on a hexagonal or triangular mesh can be investigated with the help of a planar trivariate coordinate system, where the vector components are either defined tangentially (hexagonal C-grid) or perpendicularly (triangular C-grid) to the coordinate lines. Inspecting the Helmholtz decomposition of a vector in case of the linearly dependent trivariate coordinate description reveals insights into the structure

  9. Random subspaces for encryption based on a private shared Cartesian frame

    SciTech Connect

    Bartlett, Stephen D. [School of Physics, University of Sydney, New South Wales 2006 (Australia); Hayden, Patrick [School of Computer Science, McGill University, Montreal (Canada); Spekkens, Robert W. [Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada)

    2005-11-15

    A private shared Cartesian frame is a novel form of private shared correlation that allows for both private classical and quantum communication. Cryptography using a private shared Cartesian frame has the remarkable property that asymptotically, if perfect privacy is demanded, the private classical capacity is three times the private quantum capacity. We demonstrate that if the requirement for perfect privacy is relaxed, then it is possible to use the properties of random subspaces to nearly triple the private quantum capacity, almost closing the gap between the private classical and quantum capacities.

  10. An update on the classical and quantum harmonic oscillators on the sphere and the hyperbolic plane in polar coordinates

    E-print Network

    C. Quesne

    2015-05-08

    A simple derivation of the classical solutions of a nonlinear model describing a harmonic oscillator on the sphere and the hyperbolic plane is presented in polar coordinates. These solutions are then related to those in cartesian coordinates, whose form was previously guessed. In addition, the nature of the classical orthogonal polynomials entering the bound-state radial wavefunctions of the corresponding quantum model is identified.

  11. Coordinate Plane

    NSDL National Science Digital Library

    Miss Zilles

    2007-10-31

    5th Grade Math State core Standard 3, Objective 2a: Locate points defined by ordered pairs of integers. Congratulations for earning a game day in the computer lab! Remember that even though it is game day I expect you to stay on task and follow directions. We have been talking in math about graphing integers on the coordinate plane. The games for today require that ...

  12. Neural Force/Position Control in Cartesian Space for a 6DOF Industrial Robot: Concept and First Results

    E-print Network

    Behnke, Sven

    ,zahn@nero.uni-bonn.de Abstract A novel concept of neural force/position control in cartesian space (NFC) was developed and applied. The NFC concept for a 6DOF industrial robot with 6DOF sensor (3 forces, 3 torques) is based on a cycle time of only 2 msec. NFC features include: 1) Sensor and trajectory data processing in cartesian

  13. Theory manual to OctVCE - a cartesian cell CFD code with special application to blast wave problems

    Microsoft Academic Search

    Joseph Tang

    2007-01-01

    Abstract OctVCE is a cartesian cell CFD code produced especially for numerical simulations of shock and blast wave interactions with complex geometries, in particular, from explosions. Virtual Cell Embedding (VCE) was chosen as its cartesian cell kernel for its simplicity and suciency for practical engineering design problems. The code uses a finite-volume formulation of the unsteady Euler equations with a

  14. Design of a Mixed-Signal Cartesian Feedback Loop for a Low Power Zero-IF WCDMA Transmitter

    E-print Network

    Paris-Sud XI, Université de

    Design of a Mixed-Signal Cartesian Feedback Loop for a Low Power Zero-IF WCDMA Transmitter W. SANAA-stage design of a mixed-signal Cartesian Feedback loop for a zero-IF WCDMA transmitter is presented. The new transmitter architecture consists of an analog stage including filters, I/Q modulator, feedback I

  15. Grid Vertex-Unfolding Orthogonal Polyhedra

    Microsoft Academic Search

    Mirela Damian; Robin Y. Flatland; Joseph O’Rourke

    2008-01-01

    An edge-unfolding of a polyhedron is produced by cutting along edges and flattening the faces to a net, a connected planar piece with no overlaps. A grid unfolding allows additional cuts along grid edges induced by coordinate planes passing through every vertex. A vertex-unfolding allows faces in the net to be connected at single vertices, not necessarily along edges. We show that

  16. Extending Diffusion Monte Carlo to Internal Coordinates

    NASA Astrophysics Data System (ADS)

    Petit, Andrew S.; McCoy, Anne B.

    2013-06-01

    Diffusion Monte Carlo (DMC) is a powerful technique for studying the properties of molecules and clusters that undergo large-amplitude, zero-point vibrational motions. However, the overall applicability of the method is limited by the need to work in Cartesian coordinates and therefore have available a full-dimensional potential energy surface (PES). As a result, the development of a reduced-dimensional DMC methodology has the potential to significantly extend the range of problems that DMC can address by allowing the calculations to be performed in the subset of coordinates that is physically relevant to the questions being asked, thereby eliminating the need for a full-dimensional PES. As a first step towards this goal, we describe here an internal coordinate extension of DMC that places no constraints on the choice of internal coordinates other than requiring them all to be independent. Using H_3^+ and its isotopologues as model systems, we demonstrate that the methodology is capable of successfully describing the ground state properties of highly fluxional molecules as well as, in conjunction with the fixed-node approximation, the ?=1 vibrationally excited states. The calculations of the fundamentals of H_3^+ and its isotopologues provided general insights into the properties of the nodal surfaces of vibrationally excited states. Specifically, we will demonstrate that analysis of ground state probability distributions can point to the set of coordinates that are less strongly coupled and therefore more suitable for use as nodal coordinates in the fixed-node approximation. In particular, we show that nodal surfaces defined in terms of the curvilinear normal mode coordinates are reasonable for the fundamentals of H_2D^+ and D_2H^+ despite both molecules being highly fluxional.

  17. caGrid 1.0: An Enterprise Grid Infrastructure for Biomedical Research

    PubMed Central

    Oster, Scott; Langella, Stephen; Hastings, Shannon; Ervin, David; Madduri, Ravi; Phillips, Joshua; Kurc, Tahsin; Siebenlist, Frank; Covitz, Peter; Shanbhag, Krishnakant; Foster, Ian; Saltz, Joel

    2008-01-01

    Objective To develop software infrastructure that will provide support for discovery, characterization, integrated access, and management of diverse and disparate collections of information sources, analysis methods, and applications in biomedical research. Design An enterprise Grid software infrastructure, called caGrid version 1.0 (caGrid 1.0), has been developed as the core Grid architecture of the NCI-sponsored cancer Biomedical Informatics Grid (caBIG™) program. It is designed to support a wide range of use cases in basic, translational, and clinical research, including 1) discovery, 2) integrated and large-scale data analysis, and 3) coordinated study. Measurements The caGrid is built as a Grid software infrastructure and leverages Grid computing technologies and the Web Services Resource Framework standards. It provides a set of core services, toolkits for the development and deployment of new community provided services, and application programming interfaces for building client applications. Results The caGrid 1.0 was released to the caBIG community in December 2006. It is built on open source components and caGrid source code is publicly and freely available under a liberal open source license. The core software, associated tools, and documentation can be downloaded from the following URL: https://cabig.nci.nih.gov/workspaces/Architecture/caGrid. Conclusions While caGrid 1.0 is designed to address use cases in cancer research, the requirements associated with discovery, analysis and integration of large scale data, and coordinated studies are common in other biomedical fields. In this respect, caGrid 1.0 is the realization of a framework that can benefit the entire biomedical community. PMID:18096909

  18. Agora: Grid Community in Vega Grid

    Microsoft Academic Search

    Hao Wang; Zhiwei Xu; Yili Gong; Wei Li

    2003-01-01

    \\u000a In grid environment, how to organize, discover and use grid resources is one of the basic research problems. In this paper,\\u000a we introduce a new concept called agora, which refers grid community in our Vega grid project. We propose a principle on agora\\u000a as one of the basic design principles of Vega grid, which is the community principle. We give

  19. Embodying Learning: Post-Cartesian Pedagogy and the Academic Study of Religion

    ERIC Educational Resources Information Center

    Lelwica, Michelle Mary

    2009-01-01

    This paper explores the concept and practice of "embodied pedagogy" as an alternative to the Cartesian approach to knowledge that is tacitly embedded in traditional modes of teaching and learning about religion. My analysis highlights a class I co-teach that combines the study of Aikido (a Japanese martial art) with seminar-style discussions of…

  20. Investigating the Effects of Density and Volume of a Cartesian Diver

    NSDL National Science Digital Library

    Lee Anne Garhofer Ames Elementary School St. Paul, MN 55106

    This activity is an inquiry investigation where students gather data on why the Cartesian diver sinks or floats. They then develop a new question and then conduct a new investigation by changing one variable and repeat the altered experiment and record their conclusions.

  1. Real-time cartesian force feedback control of a teleoperated robot

    NASA Technical Reports Server (NTRS)

    Campbell, Perry

    1989-01-01

    Active cartesian force control of a teleoperated robot is investigated. An economical microcomputer based control method was tested. Limitations are discussed and methods of performance improvement suggested. To demonstrate the performance of this technique, a preliminary test was performed with success. A general purpose bilateral force reflecting hand controller is currently being constructed based on this control method.

  2. Two-dimensional anisotropic Cartesian mesh adaptation for the compressible Euler equations

    Microsoft Academic Search

    W. A. Keats; F.-S. Lien

    2004-01-01

    Simulating transient compressible flows involving shock waves presents challenges to the CFD practitioner in terms of the mesh quality required to resolve discontinuities and prevent smearing. This paper discusses a novel two-dimensional Cartesian anisotropic mesh adaptation technique implemented for transient compressible flow. This technique, originally developed for laminar incompressible flow, is efficient because it refines and coarsens cells using criteria

  3. ANALYSIS OF A CARTESIAN PML APPROXIMATION TO ACOUSTIC SCATTERING PROBLEMS IN R2

    E-print Network

    Pasciak, Joseph

    variables and equations in the "ficticious material" region. For more analysis on PML applied to time domainANALYSIS OF A CARTESIAN PML APPROXIMATION TO ACOUSTIC SCATTERING PROBLEMS IN R2 AND R3 JAMES H complex coefficient equation for the acoustic wave posed on an infinite domain, the complement

  4. Accelerated Non-Cartesian SENSE Reconstruction Using a Majorize-Minimize Algorithm Combining

    E-print Network

    Fessler, Jeffrey A.

    ) is a suitable regularizer: imposes prior information, reduces noise & artifacts, e.g., TV, `1-regularizers, etc-Cartesian k-space trajectories Efficient k-space coverage, robustness to motion & off-resonance effects majorize-minimize strategy with variable-splitting Has reduced need of NUFFTs Organization of the talk

  5. Cartesian Meshing Impacts for PWR Assemblies in Multigroup Monte Carlo and Sn Transport

    NASA Astrophysics Data System (ADS)

    Manalo, K.; Chin, M.; Sjoden, G.

    2014-06-01

    Hybrid methods of neutron transport have increased greatly in use, for example, in applications of using both Monte Carlo and deterministic transport to calculate quantities of interest, such as flux and eigenvalue in a nuclear reactor. Many 3D parallel Sn codes apply a Cartesian mesh, and thus for nuclear reactors the representation of curved fuels (cylinder, sphere, etc.) are impacted in the representation of proper fuel inventory (both in deviation of mass and exact geometry representation). For a PWR assembly eigenvalue problem, we explore the errors associated with this Cartesian discrete mesh representation, and perform an analysis to calculate a slope parameter that relates the pcm to the percent areal/volumetric deviation (areal corresponds to 2D and volumetric to 3D, respectively). Our initial analysis demonstrates a linear relationship between pcm change and areal/volumetric deviation using Multigroup MCNP on a PWR assembly compared to a reference exact combinatorial MCNP geometry calculation. For the same multigroup problems, we also intend to characterize this linear relationship in discrete ordinates (3D PENTRAN) and discuss issues related to transport cross-comparison. In addition, we discuss auto-conversion techniques with our 3D Cartesian mesh generation tools to allow for full generation of MCNP5 inputs (Cartesian mesh and Multigroup XS) from a basis PENTRAN Sn model.

  6. Simulation of Conservative Congruence Transformation: Conservative Properties in the Joint and Cartesian Spaces

    Microsoft Academic Search

    Shih-feng Chen; Imin Kao

    2000-01-01

    The stiffness characteristics of robot systems via the conservative congruence transformation (CCT) and the conventional congruence transformation (CT) between the joint and Cartesian spaces are investigated. A stiffness matrix is conservative if: 1) the force resulting from the stiffness matrix is conservative, and 2) the work done by such force along a closed path is zero. The criteria result in

  7. caGrid 1.0 : an enterprise Grid infrastructure for biomedical research.

    SciTech Connect

    Oster, S.; Langella, S.; Hastings, S.; Ervin, D.; Madduri, R.; Phillips, J.; Kurc, T.; Siebenlist, F.; Covitz, P.; Shanbhag, K.; Foster, I.; Saltz, J.; Mathematics and Computer Science; The Ohio State Univ.; National Cancer Inst. Centerfor Bioinformatics; SemanticBits

    2008-03-01

    To develop software infrastructure that will provide support for discovery, characterization, integrated access, and management of diverse and disparate collections of information sources, analysis methods, and applications in biomedical research. Design: An enterprise Grid software infrastructure, called caGrid version 1.0 (caGrid 1.0), has been developed as the core Grid architecture of the NCI-sponsored cancer Biomedical Informatics Grid (caBIG{trademark}) program. It is designed to support a wide range of use cases in basic, translational, and clinical research, including (1) discovery, (2) integrated and large-scale data analysis, and (3) coordinated study. Measurements: The caGrid is built as a Grid software infrastructure and leverages Grid computing technologies and the Web Services Resource Framework standards. It provides a set of core services, toolkits for the development and deployment of new community provided services, and application programming interfaces for building client applications. Results: The caGrid 1.0 was released to the caBIG community in December 2006. It is built on open source components and caGrid source code is publicly and freely available under a liberal open source license. The core software, associated tools, and documentation can be downloaded from the following URL: Grid>.

  8. Computer coordination of limb motion for a three-legged walking robot

    NASA Technical Reports Server (NTRS)

    Klein, C. A.; Patterson, M. R.

    1980-01-01

    Coordination of the limb motion of a vehicle which could perform assembly and maintenance operations on large structures in space is described. Manipulator kinematics and walking robots are described. The basic control scheme of the robot is described. The control of the individual arms are described. Arm velocities are generally described in Cartesian coordinates. Cartesian velocities are converted to joint velocities using the Jacobian matrix. The calculation of a trajectory for an arm given a sequence of points through which it is to pass is described. The free gait algorithm which controls the lifting and placing of legs for the robot is described. The generation of commanded velocities for the robot, and the implementation of those velocities by the algorithm are discussed. Suggestions for further work in the area of robot legged locomotion are presented.

  9. Uni InnsbruckUni Innsbruck InformatikInformatik --11 Grid InterNetworkingGrid InterNetworking

    E-print Network

    Welzl, Michael

    Foster, Carl Kesselman and Steven Tuecke, "The Anatomy of the Grid ­ Enabling Scalable Virtual is coordinated resource sharing and problem solving in dynamic, multi institutional virtual organizations [Ian Organizations", International Journal on Supercomputer Applications, 2001] · Common terms: Virtual Team

  10. GridMan: A grid manipulation system

    NASA Technical Reports Server (NTRS)

    Eiseman, Peter R.; Wang, Zhu

    1992-01-01

    GridMan is an interactive grid manipulation system. It operates on grids to produce new grids which conform to user demands. The input grids are not constrained to come from any particular source. They may be generated by algebraic methods, elliptic methods, hyperbolic methods, parabolic methods, or some combination of methods. The methods are included in the various available structured grid generation codes. These codes perform the basic assembly function for the various elements of the initial grid. For block structured grids, the assembly can be quite complex due to a large number of clock corners, edges, and faces for which various connections and orientations must be properly identified. The grid generation codes are distinguished among themselves by their balance between interactive and automatic actions and by their modest variations in control. The basic form of GridMan provides a much more substantial level of grid control and will take its input from any of the structured grid generation codes. The communication link to the outside codes is a data file which contains the grid or section of grid.

  11. Application of wall functions to generalized nonorthogonal curvilinear coordinate systems

    Microsoft Academic Search

    Douglas L. Sondak; Richard H. Pletcher

    1995-01-01

    A method has been developed for the application of wall functions to generalized curvilinear coordinate systems with nonorthogonal grids. Two test cases have been computed using this method with the k-epsilon turbulence model: flow over a flat plate at 0-deg angle of attack using a nonorthogonal grid at the wall and flow over a prolate hemispheroid with a hemispherical nose

  12. Cluster and Grid Computing

    NSDL National Science Digital Library

    Amy Apon

    * Overview of grid computing, * Basic Internet technologies: IP, HTTP, UDP, TCP, * Security, * Web Services and Enabling technologies, * Grid service concepts,* Resource Management, * Discovery and Information Services, * Parallel programming techniques suitable for a Grid, * Cluster computing and basic message passing techniques

  13. Grid Labeling Using A Marked Grid

    NASA Astrophysics Data System (ADS)

    Dunn, Stanley M.; Keizer, Richard L.

    1989-03-01

    Accurate grid labeling is a key step in recovering 3-D surfaces from structured light images. Knowledge of the real world (projector and camera geometry, surface continuity and smoothness, etc.) can be used to derive a set of local and global constraints which the grid labels must satisfy. Propagation of these constraints eliminates all but a small set of possible grid labels, but ambiguous solutions may still remain. This paper discusses a method of eliminating grid labeling ambiguity by adding constraints introduced by placing markers within the grid pattern. Grid labeling is based on geometric and topological constraints. Geometric constraints are global constraints on grid labels arising from knowledge of the camera and projector geometry, from assumed opaqueness of the object, and from knowledge of the work volume. Topological constraints are local constraints on grid labels arising from the sequential ordering of grid labels along a single grid stripe in the camera image, and from the assumption that a continuous (smooth) network of grid stripes in the camera image indicates a continuous (smooth) three-dimensional surface. This last assumption may be sometimes violated due to infrequent "viewing accidents" which may be caused by surface irregularities such as occluding contours or creases or by image processing errors. A problem with previous methods is the possible ambiguity of the recovered surface. This ambiguity occurs when more than one globally consistent set of grid labels is obtained, and consequently more than one object surface is possible. Our results show that the locations of the grid markers provide additional constraints to guide the grid labeling. We will present results of using several algorithms for labeling grids in structured light images. We will show that the additional constraints can be easily included into constraint propagation algorithms previously used for grid labeling.

  14. Hermite collocation solution of near-singular problems using numerical coordinate transformations based on adaptivity

    NASA Astrophysics Data System (ADS)

    Lang, A. W.; Sloan, D. M.

    2002-03-01

    A coordinate transformation approach is described that enables Hermite collocation methods to be applied efficiently in one space dimension to steady and unsteady differential problems with steep solutions. The work is an extension of earlier work by Mulholland et al. (J. Comput. Phys. 131 (1997) 280). A coarse grid is generated by an adaptive finite difference method and this grid is used to construct a steady or unsteady coordinate transformation that is based on monotonic cubic spline approximation. An uneven grid is generated by means of the coordinate transformation and the differential problem is solved on this grid using Hermite collocation. Numerical results are presented for steady and unsteady problems.

  15. Numerical grid generation in computational field simulations. Volume 1

    SciTech Connect

    Soni, B.K.; Thompson, J.F.; Haeuser, J.; Eiseman, P.R. [eds.

    1996-12-31

    To enhance the CFS technology to its next level of applicability (i.e., to create acceptance of CFS in an integrated product and process development involving multidisciplinary optimization) the basic requirements are: rapid turn-around time, reliable and accurate simulation, affordability and appropriate linkage to other engineering disciplines. In response to this demand, there has been a considerable growth in the grid generation related research activities involving automization, parallel processing, linkage with the CAD-CAM systems, CFS with dynamic motion and moving boundaries, strategies and algorithms associated with multi-block structured, unstructured, hybrid, hexahedral, and Cartesian grids, along with its applicability to various disciplines including biomedical, semiconductor, geophysical, ocean modeling, and multidisciplinary optimization.

  16. Technical Aspects of the Parkes Error Grid

    PubMed Central

    Pfützner, Andreas; Klonoff, David C.; Pardo, Scott; Parkes, Joan L.

    2013-01-01

    Background The Parkes error grid, which was developed in 1994, presented performance zones for blood glucose (BG) monitors with borders that were not mathematically specified at the time the grid was published. Methods In this article, we (1) review the history of the Parkes error grid, (2) present the never-before-published exact coordinates and specifications of the grid so that others may produce an exact replica of the original grid, and (3) discuss our suggestions how this metric should be applied. Results The new ISO15197:2013 guideline for system accuracy assessment of BG meters for patient self-measurement incorporates use of this metric for defining acceptable accuracy of BG monitors. It is expected that, for regulatory purposes, this document will stipulate that the error grid version for type 1 diabetes should be applied with the caveat that only the A zone represents acceptable accuracy. Conclusions It remains to be seen by how much the new error grid, which is currently being developed by the Food and Drug Administration/Diabetes Technology Society/American Diabetes Association/The Endocrine Society/ Association for Advancement of Medical Instrumentation, will deviate from the Parkers error grid. PMID:24124954

  17. Direct simulation of multi-phase MHD flows on an unstructured Cartesian adaptive system

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Ni, Ming-Jiu

    2014-08-01

    An approach for direct simulation of the multi-phase magnetohydrodynamics (MHD) flows has been developed in the present study on an unstructured Cartesian adaptive system. The approach is based on the volume-of-fluid (VOF) method for capturing the interface with the adaptive mesh refinement (AMR) technique used to well resolve the interface and the boundary layer. The Lorentz force is calculated using the consistent and conservative scheme, which is specially designed on a Cartesian adaptive mesh to conserve the physical conservation laws. The continuous-surface-tension (CSF) formulation is adopted for surface tension calculation. Moreover, the interfacial flows driven by thermal Marangoni effects at multifluid interfaces are also studied with a special numerical treatment presented. The method is able to simulate bubble motion in liquid metal under magnetic field irrespective of high density ratio and electric conductivity ratio. The proposed scheme for multi-phase MHD flows is validated by experimental results as well as analytical solutions.

  18. Aerodynamic Design of Complex Configurations Using Cartesian Methods and CAD Geometry

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.; Pulliam, Thomas H.

    2003-01-01

    The objective for this paper is to present the development of an optimization capability for the Cartesian inviscid-flow analysis package of Aftosmis et al. We evaluate and characterize the following modules within the new optimization framework: (1) A component-based geometry parameterization approach using a CAD solid representation and the CAPRI interface. (2) The use of Cartesian methods in the development Optimization techniques using a genetic algorithm. The discussion and investigations focus on several real world problems of the optimization process. We examine the architectural issues associated with the deployment of a CAD-based design approach in a heterogeneous parallel computing environment that contains both CAD workstations and dedicated compute nodes. In addition, we study the influence of noise on the performance of optimization techniques, and the overall efficiency of the optimization process for aerodynamic design of complex three-dimensional configurations. of automated optimization tools. rithm and a gradient-based algorithm.

  19. On the Use of Parmetric-CAD Systems and Cartesian Methods for Aerodynamic Design

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.; Pulliam, Thomas H.

    2004-01-01

    Automated, high-fidelity tools for aerodynamic design face critical issues in attempting to optimize real-life geometry arid in permitting radical design changes. Success in these areas promises not only significantly shorter design- cycle times, but also superior and unconventional designs. To address these issues, we investigate the use of a parmetric-CAD system in conjunction with an embedded-boundary Cartesian method. Our goal is to combine the modeling capabilities of feature-based CAD with the robustness and flexibility of component-based Cartesian volume-mesh generation for complex geometry problems. We present the development of an automated optimization frame-work with a focus on the deployment of such a CAD-based design approach in a heterogeneous parallel computing environment.

  20. Exploring predistortion training algorithms in a Cartesian feedback-trained digital predistortion system for RF power amplifier linearization

    E-print Network

    Huang, Jeffrey B

    2006-01-01

    A Cartesian feedback-trained digital predistortion system for RF power amplifier linearization offers many advantages with its combination of two different linearization techniques. This thesis describes such a system, ...

  1. Augmented Lagrangian with Variable Splitting for Faster Non-Cartesian L1-SPIRiT MR Image Reconstruction

    PubMed Central

    Weller, Daniel S.; Ramani, Sathish; Fessler, Jeffrey A.

    2013-01-01

    SPIRiT (iterative self-consistent parallel imaging reconstruction), and its sparsity-regularized variant L1-SPIRiT, are compatible with both Cartesian and non-Cartesian MRI sampling trajectories. However, the non-Cartesian framework is more expensive computationally, involving a nonuniform Fourier transform with a nontrivial Gram matrix. We propose a novel implementation of the regularized reconstruction problem using variable splitting, alternating minimization of the augmented La-grangian, and careful preconditioning. Our new method based on the alternating direction method of multipliers converges much faster than existing methods because of the preconditioners' heightened effectiveness. We demonstrate such rapid convergence substantially improves image quality for a fixed computation time. Our framework is a step forward towards rapid non-Cartesian L1-SPIRiT reconstructions. PMID:24122551

  2. A parallel performance study of the Cartesian method for partial differential equations on a sphere

    SciTech Connect

    Drake, J.B. [Oak Ridge National Lab., TN (United States); Coddington, M.P. [Swarthmore College, PA (United States)

    1997-04-01

    A 3-D Cartesian method for integration of partial differential equations on a spherical surface is developed for parallel computation. The target computer architectures are distributed memory, message passing computers such as the Intel Paragon. The parallel algorithms are described along with mesh partitioning strategies. Performance of the algorithms is considered for a standard test case of the shallow water equations on the sphere. The authors find the computation time scale well with increasing numbers of processors.

  3. (p, r)cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d

    E-print Network

    Klavzar, Sandi

    Fibonacci (p, r)­cubes as Cartesian products Sandi KlavŸzar a,b,c Yoomi Rho d a Faculty The Fibonacci (p, r)­cube # (p,r) n is the subgraph of Qn induced on binary words of length n in which there are at most r consecutive ones and at least p zeros between two substrings of ones. These cubes simultaneously

  4. (p, r)cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d

    E-print Network

    Klavzar, Sandi

    Fibonacci (p, r)­cubes as Cartesian products Sandi KlavŸzar a,b,c Yoomi Rho d a Faculty The Fibonacci (p, r)­cube # (p,r) n is the subgraph of Qn induced on binary words of length n in which there are at most r consecutive ones and there are at least p zeros between two substrings of ones. These cubes

  5. Cartesian path control of a two-degree-of-freedom robot manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Pooran, Farhad J.

    1988-01-01

    The problem of cartesian trajectory control of a closed-kinematic chain mechanism robot manipulator with possible space station applications is considered. The study was performed by both computer simulation and experimentation for tracking of three different paths: a straight line, a sinusoid and a circle. Linearization and pole placement methods are employed to design controller gains. Results show that the controllers are robust and there are good agreements between simulation and experimentation. Excellent tracking quality and small overshoots are also evident.

  6. On constructing three-dimensional overlapping grids with CMPGRD

    NASA Technical Reports Server (NTRS)

    Henshaw, William D.; Chesshire, Geoffrey; Henderson, Michael E.

    1992-01-01

    Techniques for the construction of three-dimensional composite overlapping grids, using the grid construction program CMPGRD, are described. The overlapping approach can be used to generate grids for regions of complicated geometry. The grids can be constructed to be smooth and free from coordinate singularities. The ability to create smooth grids for complicated regions is an important first step towards the accurate numerical solution of partial differential equations. The creation of grids for surfaces defined by cross-sections such as an airplane wing is described. A method for integrating the patched surfaces generated by a computer aided design (CAD) package with the CMPGRD program is described. Additionally, the creation of grids in regions where surfaces intersect is described.

  7. Comprehensive Smart Grid Planning in a Regulated Utility Environment

    NASA Astrophysics Data System (ADS)

    Turner, Matthew; Liao, Yuan; Du, Yan

    2015-06-01

    This paper presents the tools and exercises used during the Kentucky Smart Grid Roadmap Initiative in a collaborative electric grid planning process involving state regulators, public utilities, academic institutions, and private interest groups. The mandate of the initiative was to assess the existing condition of smart grid deployments in Kentucky, to enhance understanding of smart grid concepts by stakeholders, and to develop a roadmap for the deployment of smart grid technologies by the jurisdictional utilities of Kentucky. Through involvement of many important stakeholder groups, the resultant Smart Grid Deployment Roadmap proposes an aggressive yet achievable strategy and timetable designed to promote enhanced availability, security, efficiency, reliability, affordability, sustainability and safety of the electricity supply throughout the state while maintaining Kentucky's nationally competitive electricity rates. The models and methods developed for this exercise can be utilized as a systematic process for the planning of coordinated smart grid deployments.

  8. Anisotropy of the Reynolds stress tensor in the wakes of wind turbine arrays in Cartesian arrangements with counter-rotating rotors

    NASA Astrophysics Data System (ADS)

    Hamilton, Nicholas; Cal, Raúl Bayoán

    2015-01-01

    A 4 × 3 wind turbine array in a Cartesian arrangement was constructed in a wind tunnel setting with four configurations based on the rotational sense of the rotor blades. The fourth row of devices is considered to be in the fully developed turbine canopy for a Cartesian arrangement. Measurements of the flow field were made with stereo particle-image velocimetry immediately upstream and downstream of the selected model turbines. Rotational sense of the turbine blades is evident in the mean spanwise velocity W and the Reynolds shear stress - v w ¯ . The flux of kinetic energy is shown to be of greater magnitude following turbines in arrays where direction of rotation of the blades varies. Invariants of the normalized Reynolds stress anisotropy tensor (? and ?) are plotted in the Lumley triangle and indicate that distinct characters of turbulence exist in regions of the wake following the nacelle and the rotor blade tips. Eigendecomposition of the tensor yields principle components and corresponding coordinate system transformations. Characteristic spheroids representing the balance of components in the normalized anisotropy tensor are composed with the eigenvalues yielding shapes predicted by the Lumley triangle. Rotation of the coordinate system defined by the eigenvectors demonstrates trends in the streamwise coordinate following the rotors, especially trailing the top-tip of the rotor and below the hub. Direction of rotation of rotor blades is shown by the orientation of characteristic spheroids according to principle axes. In the inflows of exit row turbines, the normalized Reynolds stress anisotropy tensor shows cumulative effects of the upstream turbines, tending toward prolate shapes for uniform rotational sense, oblate spheroids for streamwise organization of rotational senses, and a mixture of characteristic shapes when the rotation varies by row. Comparison between the invariants of the Reynolds stress anisotropy tensor and terms from the mean mechanical energy equation indicate correlation between the degree of anisotropy and the regions of the wind turbine wakes where turbulence kinetic energy is produced. The flux of kinetic energy into the momentum-deficit area of the wake from above the canopy is associated with prolate characteristic spheroids. Flux upward into the wake from below the rotor area is associated with oblate characteristic spheroids. Turbulence in the region of the flow directly following the nacelle of the wind turbines demonstrates greater isotropy than regions following the rotor blades. The power and power coefficients for wind turbines indicate that flow structures on the order of magnitude of the spanwise turbine spacing that increase turbine efficiency depending on particular array configuration.

  9. Parallel Grid Manipulations in Earth Science Calculations

    NASA Technical Reports Server (NTRS)

    Sawyer, W.; Lucchesi, R.; daSilva, A.; Takacs, L. L.

    1999-01-01

    The National Aeronautics and Space Administration (NASA) Data Assimilation Office (DAO) at the Goddard Space Flight Center is moving its data assimilation system to massively parallel computing platforms. This parallel implementation of GEOS DAS will be used in the DAO's normal activities, which include reanalysis of data, and operational support for flight missions. Key components of GEOS DAS, including the gridpoint-based general circulation model and a data analysis system, are currently being parallelized. The parallelization of GEOS DAS is also one of the HPCC Grand Challenge Projects. The GEOS-DAS software employs several distinct grids. Some examples are: an observation grid- an unstructured grid of points at which observed or measured physical quantities from instruments or satellites are associated- a highly-structured latitude-longitude grid of points spanning the earth at given latitude-longitude coordinates at which prognostic quantities are determined, and a computational lat-lon grid in which the pole has been moved to a different location to avoid computational instabilities. Each of these grids has a different structure and number of constituent points. In spite of that, there are numerous interactions between the grids, e.g., values on one grid must be interpolated to another, or, in other cases, grids need to be redistributed on the underlying parallel platform. The DAO has designed a parallel integrated library for grid manipulations (PILGRIM) to support the needed grid interactions with maximum efficiency. It offers a flexible interface to generate new grids, define transformations between grids and apply them. Basic communication is currently MPI, however the interfaces defined here could conceivably be implemented with other message-passing libraries, e.g., Cray SHMEM, or with shared-memory constructs. The library is written in Fortran 90. First performance results indicate that even difficult problems, such as above-mentioned pole rotation- a sparse interpolation with little data locality between the physical lat-lon grid and a pole rotated computational grid- can be solved efficiently and at the GFlop/s rates needed to solve tomorrow's high resolution earth science models. In the subsequent presentation we will discuss the design and implementation of PILGRIM as well as a number of the problems it is required to solve. Some conclusions will be drawn about the potential performance of the overall earth science models on the supercomputer platforms foreseen for these problems.

  10. Advancing Smart Grid Interoperability and Implementing NIST's Interoperability Roadmap

    SciTech Connect

    Basso,T.; DeBlasio, R.

    2010-04-01

    The IEEE American National Standards project P2030TM addressing smart grid interoperability and the IEEE 1547 series of standards addressing distributed resources interconnection with the grid have been identified in priority action plans in the Report to NIST on the Smart Grid Interoperability Standards Roadmap. This paper presents the status of the IEEE P2030 development, the IEEE 1547 series of standards publications and drafts, and provides insight on systems integration and grid infrastructure. The P2030 and 1547 series of standards are sponsored by IEEE Standards Coordinating Committee 21.

  11. Efficient procedure for the numerical calculation of harmonic vibrational frequencies based on internal coordinates

    SciTech Connect

    Miliordos, Evangelos; Xantheas, Sotiris S.

    2013-08-15

    We propose a general procedure for the numerical calculation of the harmonic vibrational frequencies that is based on internal coordinates and Wilson’s GF methodology via double differentiation of the energy. The internal coordinates are defined as the geometrical parameters of a Z-matrix structure, thus avoiding issues related to their redundancy. Linear arrangements of atoms are described with a dummy atom of infinite mass. The procedure has been automated in FORTRAN90 and its main advantage lies in the nontrivial reduction of the number of single point energy calculations needed for the construction of the Hessian matrix when compared to the corresponding number using double differentiation in Cartesian coordinates. For molecules of C1 symmetry the computational savings amount to 36! ? 30, where N is the number of atoms, with additional savings when symmetry is present. Typical applications for small and medium size molecules in their minimum and transition state geometries as well as hydrogen bonded clusters are presented. In all cases the frequencies based on internal coordinates differ on average by < 1 cm-1 from those obtained from Cartesian coordinates.

  12. Static Analysis of Large-Scale Multibody System Using Joint Coordinates and Spatial Algebra Operator

    PubMed Central

    Omar, Mohamed A.

    2014-01-01

    Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations. PMID:25045732

  13. caGrid: design and implementation of the core architecture of the cancer biomedical informatics grid

    Microsoft Academic Search

    Joel H. Saltz; Scott Oster; Shannon Hastings; Stephen Langella; Tahsin M. Kurç; William Sanchez; Manav Kher; Arumani Manisundaram; Krishnakant Shanbhag; Peter A. Covitz

    2006-01-01

    Motivation: The complexity of cancer is prompting researchers to find new ways to synthesize information from diverse data sources and to carry out coordinated research efforts that span multiple institutions. There is a need for standard applications, common data models, and softwareinfrastructuretoenablemoreefficientaccesstoandsharingof distributedcomputationalresourcesincancerresearch.Toaddressthis need the National Cancer Institute (NCI) has initiated a national-scale effort, called the cancer Biomedical Informatics Grid

  14. Visual SLAM Using Variance Grid Maps

    NASA Technical Reports Server (NTRS)

    Howard, Andrew B.; Marks, Tim K.

    2011-01-01

    An algorithm denoted Gamma-SLAM performs further processing, in real time, of preprocessed digitized images acquired by a stereoscopic pair of electronic cameras aboard an off-road robotic ground vehicle to build accurate maps of the terrain and determine the location of the vehicle with respect to the maps. Part of the name of the algorithm reflects the fact that the process of building the maps and determining the location with respect to them is denoted simultaneous localization and mapping (SLAM). Most prior real-time SLAM algorithms have been limited in applicability to (1) systems equipped with scanning laser range finders as the primary sensors in (2) indoor environments (or relatively simply structured outdoor environments). The few prior vision-based SLAM algorithms have been feature-based and not suitable for real-time applications and, hence, not suitable for autonomous navigation on irregularly structured terrain. The Gamma-SLAM algorithm incorporates two key innovations: Visual odometry (in contradistinction to wheel odometry) is used to estimate the motion of the vehicle. An elevation variance map (in contradistinction to an occupancy or an elevation map) is used to represent the terrain. The Gamma-SLAM algorithm makes use of a Rao-Blackwellized particle filter (RBPF) from Bayesian estimation theory for maintaining a distribution over poses and maps. The core idea of the RBPF approach is that the SLAM problem can be factored into two parts: (1) finding the distribution over robot trajectories, and (2) finding the map conditioned on any given trajectory. The factorization involves the use of a particle filter in which each particle encodes both a possible trajectory and a map conditioned on that trajectory. The base estimate of the trajectory is derived from visual odometry, and the map conditioned on that trajectory is a Cartesian grid of elevation variances. In comparison with traditional occupancy or elevation grid maps, the grid elevation variance maps are much better for representing the structure of vegetated or rocky terrain.

  15. Limitations of Radar Coordinates

    E-print Network

    Donato Bini; Luca Lusanna; Bahram Mashhoon

    2004-12-17

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  16. Density- and wavefunction-normalized Cartesian spherical harmonics for l ? 20.

    PubMed

    Michael, J Robert; Volkov, Anatoliy

    2015-03-01

    The widely used pseudoatom formalism [Stewart (1976). Acta Cryst. A32, 565-574; Hansen & Coppens (1978). Acta Cryst. A34, 909-921] in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ? 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens [Acta Cryst. (1988), A44, 6-7]. It was shown that the analytical form for normalization coefficients is available primarily for l ? 4 [Hansen & Coppens, 1978; Paturle & Coppens, 1988; Coppens (1992). International Tables for Crystallography, Vol. B, Reciprocal space, 1st ed., edited by U. Shmueli, ch. 1.2. Dordrecht: Kluwer Academic Publishers; Coppens (1997). X-ray Charge Densities and Chemical Bonding. New York: Oxford University Press]. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 < l ? 7 (Paturle & Coppens, 1988). In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle-Coppens (Paturle & Coppens, 1988) method in the Wolfram Mathematica software to derive the Cartesian spherical harmonics for l ? 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics. PMID:25727874

  17. Grid enabled Service Support Environment - SSE Grid

    Microsoft Academic Search

    Erwin Goor; Martine Paepen

    2010-01-01

    The SSEGrid project is an ESA\\/ESRIN project which started in 2009 and is executed by two Belgian companies, Spacebel and VITO, and one Dutch company, Dutch Space. The main project objectives are the introduction of a Grid-based processing on demand infrastructure at the Image Processing Centre for earth observation products at VITO and the inclusion of Grid processing services in

  18. Physical constraints on the coefficients of Fourier expansions in cylindrical coordinates

    NASA Astrophysics Data System (ADS)

    Lewis, H. Ralph; Bellan, Paul M.

    1990-11-01

    It is demonstrated that (i) the postulate of infinite differentiability in Cartesian coordinates and (ii) the physical assumption of regularity on the axis of a cylindrical coordinate system provide significant simplifying constraints on the coefficients of Fourier expansions in cylindrical coordinates. These constraints are independent of any governing equations. The simplification can provide considerable practical benefit for the analysis (especially numerical) of actual physical problems. Of equal importance, these constraints demonstrate that if A is any arbitrary physical vector, then the only finite Fourier terms of Ar and A? are those with m=1 symmetry. In the Appendix, it is further shown that postulate (i) may be inferred from a more primitive assumption, namely, the arbitrariness of the location of the cylindrical axis of the coordinate system.

  19. Cross-sectional optoacoustic tomographic reconstructions in a polar grid

    NASA Astrophysics Data System (ADS)

    Deán-Ben, X. Luís.; Lutzweiler, Christian; Razansky, Daniel

    2014-03-01

    Some commonly employed optoacoustic (photoacoustic) tomographic configurations make use of an array of cylindrically-focused transducers located around the imaging sample to selectively acquire the optoacoustic signals generated in the imaging plane. Thereby, the feasibility of simultaneous acquisition of signals leads to important advantages such as high-throughput performance or real-time imaging capacity. For this particular geometry, two-dimensional model-based reconstruction has showcased good performance in terms of imaging accuracy and flexibility to account for various transducer-related effects and acoustic propagation phenomena. The forward model is expressed as a linear operator (model-matrix) that maps the optical absorption in a grid containing the sample to the resulting wavefield at the sensor positions. The standard approach, however, may lead to excessive memory requirements for the storage of the model-matrix. Herein, an optoacoustic model based on a discretization of the time-domain equation in a polar grid is introduced. Due to the rotational symmetry of the acquisition geometry and the discretization grid, only the part of the model-matrix directly corresponding to one transducer position (projection) needs to be stored. As a result, inversion of the model-matrix can be done in a memory efficient manner. Performance of the method was tested in numerical simulations and experimental measurements, attaining results equivalent to Cartesian-based grids but using a much more computationally efficient implementation.

  20. Noniterative three-dimensional grid generation using parabolic partial differential equations

    NASA Technical Reports Server (NTRS)

    Edwards, T. A.

    1985-01-01

    A new algorithm for generating three-dimensional grids has been developed and implemented which numerically solves a parabolic partial differential equation (PDE). The solution procedure marches outward in two coordinate directions, and requires inversion of a scalar tridiagonal system in the third. Source terms have been introduced to control the spacing and angle of grid lines near the grid boundaries, and to control the outer boundary point distribution. The method has been found to generate grids about 100 times faster than comparable grids generated via solution of elliptic PDEs, and produces smooth grids for finite-difference flow calculations.

  1. Smart Grid Communications: Overview of Research Challenges, Solutions, and Standardization Activities

    E-print Network

    Fan, Zhong; Gormus, Sedat; Efthymiou, Costas; Kalogridis, Georgios; Sooriyabandara, Mahesh; Zhu, Ziming; Lambotharan, Sangarapillai; Chin, Woon Hau

    2011-01-01

    Optimization of energy consumption in future intelligent energy networks (or Smart Grids) will be based on grid-integrated near-real-time communications between various grid elements in generation, transmission, distribution and loads. This paper discusses some of the challenges and opportunities of communications research in the areas of smart grid and smart metering. In particular, we focus on some of the key communications challenges for realizing interoperable and future-proof smart grid/metering networks, smart grid security and privacy, and how some of the existing networking technologies can be applied to energy management. Finally, we also discuss the coordinated standardization efforts in Europe to harmonize communications standards and protocols.

  2. System Wide Joint Position Sensor Fault Tolerance in Robot Systems Using Cartesian Accelerometers

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    Joint position sensors are necessary for most robot control systems. A single position sensor failure in a normal robot system can greatly degrade performance. This paper presents a method to obtain position information from Cartesian accelerometers without integration. Depending on the number and location of the accelerometers. the proposed system can tolerate the loss of multiple position sensors. A solution technique suitable for real-time implementation is presented. Simulations were conducted using 5 triaxial accelerometers to recover from the loss of up to 4 joint position sensors on a 7 degree of freedom robot moving in general three dimensional space. The simulations show good estimation performance using non-ideal accelerometer measurements.

  3. CAD-Based Aerodynamic Design of Complex Configurations using a Cartesian Method

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.; Pulliam, Thomas H.

    2003-01-01

    A modular framework for aerodynamic optimization of complex geometries is developed. By working directly with a parametric CAD system, complex-geometry models are modified nnd tessellated in an automatic fashion. The use of a component-based Cartesian method significantly reduces the demands on the CAD system, and also provides for robust and efficient flowfield analysis. The optimization is controlled using either a genetic or quasi-Newton algorithm. Parallel efficiency of the framework is maintained even when subject to limited CAD resources by dynamically re-allocating the processors of the flow solver. Overall, the resulting framework can explore designs incorporating large shape modifications and changes in topology.

  4. A review of "Cartesian Metaphysics: The Late Scholastic Origins of Modern Philosophy." by Jorge Secada

    E-print Network

    Luciano Boschiero

    2002-01-01

    cognition. According to Secada, ?Incarnat- ing the ideals of the Jesuit Reformation and persuaded of the weak- ness of Scholastic learning, Descartes gradually came to adopt as his life project the construction of a new system of knowledge, in harmony... and thought. The issues dealt with here and in Part Two are at the core of the Cartesian metaphysical and natural philosophical views that came to replace the Scholastic traditions from which they were born, and which are explained in Part One of Secada...

  5. The Dirac-Hestenes Equation for Spherical Symmetric Potentials in the Spherical and Cartesian Gauges

    NASA Astrophysics Data System (ADS)

    da Rocha, Roldão; Rodrigues, Waldyr A.

    In this paper, using the apparatus of the Clifford bundle formalism, we show how straightforwardly solve in Minkowski space-time the Dirac-Hestenes equation — which is an appropriate representative in the Clifford bundle of differential forms of the usual Dirac equation — by separation of variables for the case of a potential having spherical symmetry in the Cartesian and spherical gauges. We show that, contrary to what is expected at a first sight, the solution of the Dirac-Hestenes equation in both gauges has exactly the same mathematical difficulty.

  6. Dynamic fisheye grids for binary black hole simulations

    NASA Astrophysics Data System (ADS)

    Zilhão, Miguel; Noble, Scott C.

    2014-03-01

    We present a new warped gridding scheme adapted to simulating gas dynamics in binary black hole spacetimes. The grid concentrates grid points in the vicinity of each black hole to resolve the smaller scale structures there, and rarefies grid points away from each black hole to keep the overall problem size at a practical level. In this respect, our system can be thought of as a ‘double’ version of the fisheye coordinate system, used before in numerical relativity codes for evolving binary black holes. The gridding scheme is constructed as a mapping between a uniform coordinate system—in which the equations of motion are solved—to the distorted system representing the spatial locations of our grid points. Since we are motivated to eventually use this system for circumbinary disc calculations, we demonstrate how the distorted system can be constructed to asymptote to the typical spherical polar coordinate system, amenable to efficiently simulating orbiting gas flows about central objects with little numerical diffusion. We discuss its implementation in the Harm3d code, tailored to evolve the magnetohydrodynamics equations in curved spacetimes. We evaluate the performance of the system’s implementation in Harm3d with a series of tests, such as the advected magnetic field loop test, magnetized Bondi accretion, and evolutions of hydrodynamic discs about a single black hole and about a binary black hole. Like we have done with Harm3d, this gridding scheme can be implemented in other unigrid codes as a (possibly) simpler alternative to adaptive mesh refinement.

  7. Cartesian contrivances

    NASA Astrophysics Data System (ADS)

    Kemp, Martin

    1998-08-01

    If matter fills the Universe, making everything happen by its interactions, what does it all look like? René Descartes may have been over-mechanistic in his view, but his efforts to visualize the invisible created striking images.

  8. Cartesian Diver

    NSDL National Science Digital Library

    Institute of Physics

    2012-06-26

    In this demonstration, learners observe the effects of density and pressure. A "diver" constructed out of a piece of straw and Blu-Tack will bob inside a bottle filled with water. This highly visual demonstration works best when learners can try moving the diver up and down themselves. This activity can also be related to how animals, like whales, dive in deep waters. This activity guide includes a helpful video that demonstrates each step of the demonstration.

  9. Off the Grid

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students learn and discuss the advantages and disadvantages of renewable and non-renewable energy sources. They also learn about our nation's electric power grid and what it means for a residential home to be "off the grid."

  10. Method of grid generation

    DOEpatents

    Barnette, Daniel W. (Veguita, NM)

    2002-01-01

    The present invention provides a method of grid generation that uses the geometry of the problem space and the governing relations to generate a grid. The method can generate a grid with minimized discretization errors, and with minimal user interaction. The method of the present invention comprises assigning grid cell locations so that, when the governing relations are discretized using the grid, at least some of the discretization errors are substantially zero. Conventional grid generation is driven by the problem space geometry; grid generation according to the present invention is driven by problem space geometry and by governing relations. The present invention accordingly can provide two significant benefits: more efficient and accurate modeling since discretization errors are minimized, and reduced cost grid generation since less human interaction is required.

  11. IPG Power Grid Overview

    NASA Technical Reports Server (NTRS)

    Hinke, Thomas

    2003-01-01

    This presentation will describe what is meant by grids and then cover the current state of the IPG. This will include an overview of the middleware that is key to the operation of the grid. The presentation will then describe some of the future directions that are planned for the IPG. Finally the presentation will conclude with a brief overview of the Global Grid Forum, which is a key activity that will contribute to the successful availability of grid components.

  12. Towards a Pervasive Grid

    Microsoft Academic Search

    Vipul Hingne; Anupam Joshi; Timothy W. Finin; Hillol Kargupta; Elias N. Houstis

    2003-01-01

    The increase in the use of mobile & embedded devices, coupled with ad-hoc, short range wireless networking is enabling pervasive computing. This pervasive computing environment and the wired Grid infrastructure can be combined to make the computation and information Grid truly pervasive. This paper identifies some of the interesting research issues and challenges in creating such a pervasive Grid, and

  13. Chimera Grid Tools

    NASA Technical Reports Server (NTRS)

    Chan, William M.; Rogers, Stuart E.; Nash, Steven M.; Buning, Pieter G.; Meakin, Robert

    2005-01-01

    Chimera Grid Tools (CGT) is a software package for performing computational fluid dynamics (CFD) analysis utilizing the Chimera-overset-grid method. For modeling flows with viscosity about geometrically complex bodies in relative motion, the Chimera-overset-grid method is among the most computationally cost-effective methods for obtaining accurate aerodynamic results. CGT contains a large collection of tools for generating overset grids, preparing inputs for computer programs that solve equations of flow on the grids, and post-processing of flow-solution data. The tools in CGT include grid editing tools, surface-grid-generation tools, volume-grid-generation tools, utility scripts, configuration scripts, and tools for post-processing (including generation of animated images of flows and calculating forces and moments exerted on affected bodies). One of the tools, denoted OVERGRID, is a graphical user interface (GUI) that serves to visualize the grids and flow solutions and provides central access to many other tools. The GUI facilitates the generation of grids for a new flow-field configuration. Scripts that follow the grid generation process can then be constructed to mostly automate grid generation for similar configurations. CGT is designed for use in conjunction with a computer-aided-design program that provides the geometry description of the bodies, and a flow-solver program.

  14. An immersed boundary method for compressible flows using local grid refinement

    NASA Astrophysics Data System (ADS)

    de Tullio, M. D.; De Palma, P.; Iaccarino, G.; Pascazio, G.; Napolitano, M.

    2007-08-01

    This paper combines a state-of-the-art method for solving the three-dimensional preconditioned Navier-Stokes equations for compressible flows with an immersed boundary approach, to provide a Cartesian-grid method for computing complex flows over a wide range of the Mach number. Moreover, a flexible local grid refinement technique is employed to achieve high resolution near the immersed body and in other high-flow-gradient regions at a fraction of the cost required by a uniformly fine grid. The method is validated versus well documented steady and unsteady test problems, for a wide range of both Reynolds and Mach numbers. Finally, and most importantly, for the case of the laminar compressible steady flow past an NACA-0012 airfoil, a thorough mesh-refinement study shows that the method is second-order accurate.

  15. Simulation of fluid flow in a body-fitted grid system using the lattice Boltzmann method.

    PubMed

    Mirzaei, Masoud; Poozesh, Amin

    2013-06-01

    The ability of the interpolation supplemented lattice Boltzmann method (ISLBM) diminishes in simulation of fluid flow around complex geometries and it is nearly impossible to use this method in body-filled grid systems. In this paper, a developed version of the interpolation supplemented lattice Boltzmann method is proposed to remove the limitations of the original ISLBM. Combination of the ISLBM and the Joukowski transformation is the basis of the method. In fact, using the Joukowski transformation, the physical domain with a body-fitted grid system is mapped to the computational domain with a uniform Cartesian grid system such that the conventional ISLBM can be easily applied. The results are compared with those of a Navier-Stokes solver and there is good agreement between these two results. PMID:23848811

  16. Simulation of fluid flow in a body-fitted grid system using the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Mirzaei, Masoud; Poozesh, Amin

    2013-06-01

    The ability of the interpolation supplemented lattice Boltzmann method (ISLBM) diminishes in simulation of fluid flow around complex geometries and it is nearly impossible to use this method in body-filled grid systems. In this paper, a developed version of the interpolation supplemented lattice Boltzmann method is proposed to remove the limitations of the original ISLBM. Combination of the ISLBM and the Joukowski transformation is the basis of the method. In fact, using the Joukowski transformation, the physical domain with a body-fitted grid system is mapped to the computational domain with a uniform Cartesian grid system such that the conventional ISLBM can be easily applied. The results are compared with those of a Navier-Stokes solver and there is good agreement between these two results.

  17. Grid Computing Lecture - Globus 4.0 grid services

    NSDL National Science Digital Library

    Dr. Clayton Ferner

    2011-07-05

    Grid Computing Lecture~~Globus 4.0 grid services: Using Web services for grid computing, stateful web services, Grid computing standards, Open Grid Services Architecture (OGSA), Web Services Resource Framework (WSRF), programming GT 4.0 grid services, GT 4.0 container.

  18. FermiGrid

    SciTech Connect

    Yocum, D.R.; Berman, E.; Canal, P.; Chadwick, K.; Hesselroth, T.; Garzoglio, G.; Levshina, T.; Sergeev, V.; Sfiligoi, I.; Sharma, N.; Timm, S.; /Fermilab

    2007-05-01

    As one of the founding members of the Open Science Grid Consortium (OSG), Fermilab enables coherent access to its production resources through the Grid infrastructure system called FermiGrid. This system successfully provides for centrally managed grid services, opportunistic resource access, development of OSG Interfaces for Fermilab, and an interface to the Fermilab dCache system. FermiGrid supports virtual organizations (VOs) including high energy physics experiments (USCMS, MINOS, D0, CDF, ILC), astrophysics experiments (SDSS, Auger, DES), biology experiments (GADU, Nanohub) and educational activities.

  19. Which grids are Hamiltonian

    SciTech Connect

    Hedetniemi, S. M.; Hedetniemi, S. T.; Slater, P. J.

    1980-01-01

    A complete grid G/sub m,n/ is a graph having m x n pertices that are connected to form a rectangular lattice in the plane, i.e., all edges of G/sub m,n/ connect vertices along horizontal or vertical lines. A grid is a subgraph of a complete grid. As an illustration, complete grids describe the basic pattern of streets in most cities. This paper examines the existence of Hamiltonian cycles in complete grids and complete grids with one or two vertices removed. It is determined for most values of m,n greater than or equal to 1, which grids G/sub m,n/ - (u) and G/sub m,n/ - (u,v) are Hamiltonian. 12 figures. (RWR)

  20. Coordinated Variable Structure Switching Attacks for Smart Grid 

    E-print Network

    Liu, Shan

    2013-02-11

    The effective modeling and analysis of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical...

  1. Enabling Autonomic Grid Applications: Dynamic Composition, Coordination and Interaction

    E-print Network

    Parashar, Manish

    of networks, systems and applications have made our computational and information infras- tructure brittle, unmanageable and insecure. This has necessitated the investiga- tion of an alternate paradigm for system of complex- ity, heterogeneity, and uncertainty, i.e. autonomic computing. Project AutoMate investigates

  2. Understanding The Smart Grid

    SciTech Connect

    NONE

    2007-11-15

    The report provides an overview of what the Smart Grid is and what is being done to define and implement it. The electric industry is preparing to undergo a transition from a centralized, producer-controlled network to a decentralized, user-interactive one. Not only will the technology involved in the electric grid change, but the entire business model of the industry will change too. A major objective of the report is to identify the changes that the Smart Grid will bring about so that industry participants can be prepared to face them. A concise overview of the development of the Smart Grid is provided. It presents an understanding of what the Smart Grid is, what new business opportunities or risks might come about due to its introduction, and what activities are already taking place regarding defining or implementing the Smart Grid. This report will be of interest to the utility industry, energy service providers, aggregators, and regulators. It will also be of interest to home/building automation vendors, information technology vendors, academics, consultants, and analysts. The scope of the report includes an overview of the Smart Grid which identifies the main components of the Smart Grid, describes its characteristics, and describes how the Smart Grid differs from the current electric grid. The overview also identifies the key concepts involved in the transition to the Smart Grid and explains why a Smart Grid is needed by identifying the deficiencies of the current grid and the need for new investment. The report also looks at the impact of the Smart Grid, identifying other industries which have gone through a similar transition, identifying the overall benefits of the Smart Grid, and discussing the impact of the Smart Grid on industry participants. Furthermore, the report looks at current activities to implement the Smart Grid including utility projects, industry collaborations, and government initiatives. Finally, the report takes a look at key technology providers involved in the Smart Grid and provides profiles on them including contact information, company overviews, technology reviews, and key Smart Grid activities.

  3. The Community Education Coordinator

    ERIC Educational Resources Information Center

    Nance, Everette E.

    1972-01-01

    Covers the selection process and hiring of the community education coordinator; describes the requisite personality, qualifications, role, and training of the coordinator; and outlines the organization and structure of the community education program. (Author/EA)

  4. Non-relativistic model of the laws of gravitation and electromagnetism, invariant under the change of inertial and non-inertial coordinate systems

    E-print Network

    Poliakovsky, Arkady

    2015-01-01

    Under the classical non-relativistic consideration of the space-time we propose the model of the laws of gravitation and Electrodynamics, invariant under the galilean transformations and moreover, under every change of non-inertial cartesian coordinate system. Being in the frames of non-relativistic model of the space-time, we adopt some general ideas of the General Theory of Relativity, like the assumption of covariance of the most general physical laws in every inertial and non-inertial coordinate system and equivalence of factious forces in non-inertial coordinate systems and the force of gravitation.

  5. PML-FDTD in cylindrical and spherical grids

    Microsoft Academic Search

    F. L. Teixeira; W. C. Chew

    1997-01-01

    Perfectly matched layers (PMLs) are derived for cylindrical and spherical finite-difference time-domain (FDTD) grids. The formulation relies on the complex coordinate stretching approach. Two-dimensional (2-D) cylindrical and three-dimensional (3-D) spherical staggered-grid FDTD codes are written based on the time-domain versions of the equations. Numerical simulations validate the formulation by showing very good agreement between the perfectly matched layer-finite-difference time-domain (FDTD)

  6. Regional Transportation Coordination Study 

    E-print Network

    Golden Crescent Regional Planning Commission

    2006-01-01

    Golden Crescent Regional Transit i Regional Transportation Coordination Study: 7-County Golden Crescent Region Regional Transportation Coordination Study Executive Summary Chapter 1... ......................................................................................... 4-4 Golden Crescent Regional Transit ii Regional Transportation Coordination Study: 7-County Golden Crescent Region Chapter 5 - Identified Pilot Project Opportunities Background...

  7. LCLS Undulator Coordinate System

    SciTech Connect

    Bong, E.

    2005-01-31

    This note defines the LCLS undulator coordinate system and relates that coordinate system to the linear accelerator coordinate system. The slight downward pitch of the SLAC linac and the finite radius of the Earth necessitate some choices and definitions for the undulator layout which is described here. The layout described is consistent with the LCLS optics MAD file ''LCLS13APR04''.

  8. Trends in life science grid: from computing grid to knowledge grid

    Microsoft Academic Search

    Akihiko Konagaya

    2006-01-01

    Background: Grid computing has great potential to become a standard cyberinfrastructure for life sciences which often require high-performance computing and large data handling which exceeds the computing capacity of a single institution. Results: This survey reviews the latest grid technologies from the viewpoints of computing grid, data grid and knowledge grid. Computing grid technologies have been matured enough to solve

  9. Mapping on the HEALPix grid

    NASA Astrophysics Data System (ADS)

    Calabretta, Mark R.; Roukema, Boudewijn F.

    2007-10-01

    The natural spherical projection associated with the Hierarchical Equal-Area and Isolatitude Pixelization (HEALPix) is described and shown to be one of a hybrid class that combines the cylindrical equal-area and Collignon projections, not previously documented in the cartographic literature. Projection equations are derived for the class in general and are used to investigate its properties. It is shown that the HEALPix projection suggests a simple method of (i) storing and (ii) visualizing data sampled on the grid of the HEALPix pixelization, and also suggests an extension of the pixelization that is better suited for these purposes. Potentially useful properties of other members of the class are described, and new triangular and hexagonal pixelizations are constructed from them. Finally, the standard formalism is defined for representing the celestial coordinate system for any member of the class in the FITS data format.

  10. Bipolar coordinates for computation of transition duct flows

    NASA Technical Reports Server (NTRS)

    Madabhushi, R. K.; Levy, R.

    1988-01-01

    Numerical simulation techniques for flows in jet-engine transition ducts with changing cross sections are developed and demonstrated. The boundary-conforming grids required are generated using bipolar coordinates, and the singularities arising at the no-slip boundaries are treated as described by de Vahl Davis (1979) and Tsai and Levy (1987). Grids for several typical configurations are employed in computations with the three-dimensional laminar/turbulent viscous-flow solver of Levy et al. (1983), and the results are presented graphically. The scheme used to deal with singularities is shown to be robust, suggesting that the bipolar grids may be applicable to Navier-Stokes computations.

  11. FUTURE POWER GRID INITIATIVE GridPACK: Grid Parallel Advanced

    E-print Network

    in Focus Area Two will use high-throughput data streams produced by projects in Focus Area One Pacific Northwest National Laboratory (509) 375-3899 bruce.palmer@pnnl.gov ABOUT FPGI The Future Power Operations Center (EIOC), the Pacific Northwest National Laboratory's (PNNL) national electric grid research

  12. Fibonacci (p,r)-cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d

    E-print Network

    Klavzar, Sandi

    Fibonacci (p,r)-cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d a Faculty The Fibonacci (p,r)-cube (p,r) n is the subgraph of Qn induced on binary words of length n in which generalize several interconnection networks, notably hypercubes, Fibonacci cubes, and postal networks

  13. Fibonacci (p,r)-cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d

    E-print Network

    Klavzar, Sandi

    Fibonacci (p,r)-cubes as Cartesian products Sandi Klavzar a,b,c Yoomi Rho d a Faculty The Fibonacci (p,r)-cube (p,r) n is the subgraph of Qn induced on binary words of length n in which simultaneously gen- eralize several interconnection networks, notably hypercubes, Fibonacci cubes, and postal

  14. Grasp of Consciousness and Performance in Mathematics Making Explicit the Ways of Thinking in Solving Cartesian Product Problems

    ERIC Educational Resources Information Center

    Soares, Maria Tereza Carneiro; Moro, Maria Lucia Faria; Spinillo, Alina Galvao

    2012-01-01

    This study examines the relationship between the grasp of consciousness of the reasoning process in Grades 5 and 8 pupils from a public and a private school, and their performance in mathematical problems of Cartesian product. Forty-two participants aged from 10 to 16 solved four problems in writing and explained their solution procedures by…

  15. A grid amplifier

    Microsoft Academic Search

    M. Kim; J. J. Rosenberg; R. P. Smith; J. B. Hacker; M. P. DeLisio; D. B. Rutledge

    1991-01-01

    A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from

  16. Cyber Security & Smart Grid

    E-print Network

    Shapiro, J.

    2011-01-01

    Cyber Security & Smart Grid Jonathan Shapiro Texas Institute The Clean Air Through Energy Efficiency (CATEE) Conference Cyber Security & Smart Grid ESL-KT-11-11-23 CATEE 2011, Dallas, Texas, Nov. 7 ? 9, 2011 Cyber Security and The Smart... and communication protocols. ESL-KT-11-11-23 CATEE 2011, Dallas, Texas, Nov. 7 ? 9, 2011 Smart Grid Systems ?Current Cyber Security Issues ? Advanced Metering Infrastructure (AMI) Security ? The wireless devices are used in the smart meters located...

  17. Local Rayleigh and Nusselt Numbers for Cartesian convection with temperature-dependent viscosity

    NASA Astrophysics Data System (ADS)

    Honda, S.

    We present a local treatment of the heat transport efficiency of the base-heated cartesian convection with a temperature-dependent viscosity, which allows us to give a clearer interpretation of Nusselt (Nu)-Rayleigh (Ra) numbers relation. The “local” Nusselt (Nul) and Rayleigh (Ral) numbers are defined by the local values at each boundary layer except the length scale which is the total depth. We find that Nul-Ral relation obtained for the convection with constant viscosity and free surfaces is nearly coincident with that of the bottom boundary layer. For top boundary layer, we can treat it as a constant viscosity convection with rigid surface for large enough viscosity contrast. This interpretation can be made by choosing an appropriate temperature drop and viscosity for the definitions of Nul and Ral.

  18. Numerical Simulation of Rolling-Airframes Using a Multi-Level Cartesian Method

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Aftosmis, Michael J.; Berger, Marsha J.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    A supersonic rolling missile with two synchronous canard control surfaces is analyzed using an automated, inviscid, Cartesian method. Sequential-static and time-dependent dynamic simulations of the complete motion are computed for canard dither schedules for level flight, pitch, and yaw maneuver. The dynamic simulations are compared directly against both high-resolution viscous simulations and relevant experimental data, and are also utilized to compute dynamic stability derivatives. The results show that both the body roll rate and canard dither motion influence the roll-averaged forces and moments on the body. At the relatively, low roll rates analyzed in the current work these dynamic effects are modest, however the dynamic computations are effective in predicting the dynamic stability derivatives which can be significant for highly-maneuverable missiles.

  19. Best Choice of Coordinate System for Tracking Coordinated Turns

    E-print Network

    Gustafsson, Fredrik

    is depicted in Figure 1. A radar located at the origin measures the range and bearing to an aircraft civil aircrafts. One where Cartesian velocities are used and one where absolute velocity and heading aircraft can be accurately mod­ eled as moving by constant speed in straight lines and circle segments

  20. A grid amplifier

    NASA Technical Reports Server (NTRS)

    Kim, Moonil; Weikle, Robert M., II; Hacker, Jonathan B.; Delisio, Michael P.; Rutledge, David B.; Rosenberg, James J.; Smith, R. P.

    1991-01-01

    A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from a relative power measurement. This grid is a hybrid circuit, but the structure is suitable for fabrication as a monolithic wafer-scale integrated circuit, particularly at millimeter wavelengths.

  1. The scintillating grid illusion.

    PubMed

    Schrauf, M; Lingelbach, B; Wist, E R

    1997-04-01

    Disk-shaped luminance increments were added to the intersections of a Hermann grid consisting of medium grey bars on a black background. Illusory spots, darker than the background, were perceived as flashing within the white disks with each flick of the eye. This striking phenomenon may be referred to as the scintillating grid illusion. We determined the conditions necessary for cancelling the Hermann grid illusion, as well as the luminance requirements and the size ratio between disks and bars that elicits the scintillation effect. The fact that scanning eye movements are necessary to produce the scintillation effect sets it apart from the Hermann grid illusion. PMID:9196721

  2. Grid Computing Security Lecture

    NSDL National Science Digital Library

    Dr. Clayton Ferner

    2011-07-05

    Grid Computing Lecture~~Security: secure connection, authentication and authorization, password authentication, symmetric (secret) and asymmetric (public/private) key cyptography, RSA algorithm.

  3. A Parallel Cartesian Approach for External Aerodynamics of Vehicles with Complex Geometry

    NASA Technical Reports Server (NTRS)

    Aftosmis, M. J.; Berger, M. J.; Adomavicius, G.

    2001-01-01

    This workshop paper presents the current status in the development of a new approach for the solution of the Euler equations on Cartesian meshes with embedded boundaries in three dimensions on distributed and shared memory architectures. The approach uses adaptively refined Cartesian hexahedra to fill the computational domain. Where these cells intersect the geometry, they are cut by the boundary into arbitrarily shaped polyhedra which receive special treatment by the solver. The presentation documents a newly developed multilevel upwind solver based on a flexible domain-decomposition strategy. One novel aspect of the work is its use of space-filling curves (SFC) for memory efficient on-the-fly parallelization, dynamic re-partitioning and automatic coarse mesh generation. Within each subdomain the approach employs a variety reordering techniques so that relevant data are on the same page in memory permitting high-performance on cache-based processors. Details of the on-the-fly SFC based partitioning are presented as are construction rules for the automatic coarse mesh generation. After describing the approach, the paper uses model problems and 3- D configurations to both verify and validate the solver. The model problems demonstrate that second-order accuracy is maintained despite the presence of the irregular cut-cells in the mesh. In addition, it examines both parallel efficiency and convergence behavior. These investigations demonstrate a parallel speed-up in excess of 28 on 32 processors of an SGI Origin 2000 system and confirm that mesh partitioning has no effect on convergence behavior.

  4. Variational solution of the Schrödinger equation using plane waves in adaptive coordinates: The radial case

    NASA Astrophysics Data System (ADS)

    Pérez-Jordá, José M.

    2010-01-01

    A new method for solving the Schrödinger equation is proposed, based on the following details. First, a map u =u(r) from Cartesian coordinates r to a new coordinate system u is chosen. Second, the solution (orbital) ?(r ) is written in terms of a function U depending on u so that ?(r )=|Ju|-1/2U(u), where |Ju| is the Jacobian determinant of the map. Third, U is expressed as a linear combination of plane waves in the u coordinate, U(u )=?kckeik ?u. Finally, the coefficients ck are variationally optimized to obtain the best energy, using a generalization of an algorithm originally developed for the Coulomb potential [J. M. Pérez-Jordá, Phys. Rev. B 58, 1230 (1998)]. The method is tested for the radial Schrödinger equation in the hydrogen atom, resulting in micro-Hartree accuracy or better for the energy of ns and np orbitals (with n up to 5) using expansions of moderate length.

  5. A conservative approach for flow field calculations on multiple grids

    NASA Technical Reports Server (NTRS)

    Kathong, Monchai; Tiwari, Surendra N.

    1988-01-01

    In the computation of flow fields about complex configurations, it is very difficult to construct body-fitted coordinate systems. An alternative approach is to use several grids at once, each of which is generated independently. This procedure is called the multiple grids or zonal grids approach and its applications are investigated in this study. The method follows the conservative approach and provides conservation of fluxes at grid interfaces. The Euler equations are solved numerically on such grids for various configurations. The numerical scheme used is the finite-volume technique with a three-state Runge-Kutta time integration. The code is vectorized and programmed to run on the CDC VPS-32 computer. Some steady state solutions of the Euler equations are presented and discussed.

  6. Research on the comparison of extension mechanism of cellular automaton based on hexagon grid and rectangular grid

    NASA Astrophysics Data System (ADS)

    Zhai, Xiaofang; Zhu, Xinyan; Xiao, Zhifeng; Weng, Jie

    2009-10-01

    Historically, cellular automata (CA) is a discrete dynamical mathematical structure defined on spatial grid. Research on cellular automata system (CAS) has focused on rule sets and initial condition and has not discussed its adjacency. Thus, the main focus of our study is the effect of adjacency on CA behavior. This paper is to compare rectangular grids with hexagonal grids on their characteristics, strengths and weaknesses. They have great influence on modeling effects and other applications including the role of nearest neighborhood in experimental design. Our researches present that rectangular and hexagonal grids have different characteristics. They are adapted to distinct aspects, and the regular rectangular or square grid is used more often than the hexagonal grid. But their relative merits have not been widely discussed. The rectangular grid is generally preferred because of its symmetry, especially in orthogonal co-ordinate system and the frequent use of raster from Geographic Information System (GIS). However, in terms of complex terrain, uncertain and multidirectional region, we have preferred hexagonal grids and methods to facilitate and simplify the problem. Hexagonal grids can overcome directional warp and have some unique characteristics. For example, hexagonal grids have a simpler and more symmetric nearest neighborhood, which avoids the ambiguities of the rectangular grids. Movement paths or connectivity, the most compact arrangement of pixels, make hexagonal appear great dominance in the process of modeling and analysis. The selection of an appropriate grid should be based on the requirements and objectives of the application. We use rectangular and hexagonal grids respectively for developing city model. At the same time we make use of remote sensing images and acquire 2002 and 2005 land state of Wuhan. On the base of city land state in 2002, we make use of CA to simulate reasonable form of city in 2005. Hereby, these results provide a proof of concept for hexagonal which has great dominance.

  7. Software models for Smart Grid

    Microsoft Academic Search

    Anjali Singhal; R. P. Saxena

    2012-01-01

    Smart grid technology is progressing worldwide. Various Countries are investing to transform their traditional power grid to Smart grid. They have started realigning their organization to support a Smart grid vision. At this initial stage some software models are required to quantifiably evaluate, monitor the progress and plan for the realization of a smart grid. At present some models like

  8. Gravity inversion in spherical coordinates using tesseroids

    NASA Astrophysics Data System (ADS)

    Uieda, Leonardo; Barbosa, Valeria C. F.

    2014-05-01

    Satellite observations of the gravity field have provided geophysicists with exceptionally dense and uniform coverage of data over vast areas. This enables regional or global scale high resolution geophysical investigations. Techniques like forward modeling and inversion of gravity anomalies are routinely used to investigate large geologic structures, such as large igneous provinces, suture zones, intracratonic basins, and the Moho. Accurately modeling such large structures requires taking the sphericity of the Earth into account. A reasonable approximation is to assume a spherical Earth and use spherical coordinates. In recent years, efforts have been made to advance forward modeling in spherical coordinates using tesseroids, particularly with respect to speed and accuracy. Conversely, traditional space domain inverse modeling methods have not yet been adapted to use spherical coordinates and tesseroids. In the literature there are a range of inversion methods that have been developed for Cartesian coordinates and right rectangular prisms. These include methods for estimating the relief of an interface, like the Moho or the basement of a sedimentary basin. Another category includes methods to estimate the density distribution in a medium. The latter apply many algorithms to solve the inverse problem, ranging from analytic solutions to random search methods as well as systematic search methods. We present an adaptation for tesseroids of the systematic search method of "planting anomalous densities". This method can be used to estimate the geometry of geologic structures. As prior information, it requires knowledge of the approximate densities and positions of the structures. The main advantage of this method is its computational efficiency, requiring little computer memory and processing time. We demonstrate the shortcomings and capabilities of this approach using applications to synthetic and field data. Performing the inversion of gravity and gravity gradient data, simultaneously or separately, is straight forward and requires no changes to the existing algorithm. Such feature makes it ideal for inverting the multicomponent gravity gradient data from the GOCE satellite. An implementation of our adaptation is freely available in the open-source modeling and inversion package Fatiando a Terra (http://www.fatiando.org).

  9. Grid Database Service Specification

    Microsoft Academic Search

    James Clerk Maxwell; Susan Malaika; Gavin McCance; James Magowan; Norman W. Paton; Greg Riccardi

    2002-01-01

    Data management systems are central to many applications across multiple domains, and play a significant role in many others. Web services provide implementation neutral facilities for describing, invoking and orchestrating collections of networked resources. The Open Grid Services Architecture (OGSA) extends Web Services with consistent interfaces for creating, managing and exchanging information among Grid Services, which are dynamic computational artefacts

  10. Security for grids

    SciTech Connect

    Humphrey, Marty; Thompson, Mary R.; Jackson, Keith R.

    2005-08-14

    Securing a Grid environment presents a distinctive set of challenges. This paper groups the activities that need to be secured into four categories: naming and authentication; secure communication; trust, policy, and authorization; and enforcement of access control. It examines the current state of the art in securing these processes and introduces new technologies that promise to meet the security requirements of Grids more completely.

  11. The Scintillating Grid Illusion

    Microsoft Academic Search

    MICHAEL SCHRAUF; BERND LINGELBACH; EUGENE R WIST

    1997-01-01

    Disk-shaped luminance increments were added to the intersections of a Hermann grid consisting of medium grey bars on a black background. Illusory spots, darker than the background, were perceived as flashing within the white disks with each flick of the eye. This striking phenomenon may be referred to as the scintillating grid illusion. We determined the conditions necessary for cancelling

  12. Geometric grid generation

    NASA Technical Reports Server (NTRS)

    Ives, David

    1995-01-01

    This paper presents a highly automated hexahedral grid generator based on extensive geometrical and solid modeling operations developed in response to a vision of a designer-driven one day turnaround CFD process which implies a designer-driven one hour grid generation process.

  13. Smart Grid security technology

    Microsoft Academic Search

    Anthony R. Metke; Randy L. Ekl

    2010-01-01

    The security of the United States and the way of life of its citizens is dependant on the availability of the North American power grid. Much of the technology currently in use by the grid is outdated and in many cases unreliable. There have been three major blackouts in the past nine years. Further, the reliance on old technology leads

  14. Decentral Smart Grid Control

    NASA Astrophysics Data System (ADS)

    Schäfer, Benjamin; Matthiae, Moritz; Timme, Marc; Witthaut, Dirk

    2015-01-01

    Stable operation of complex flow and transportation networks requires balanced supply and demand. For the operation of electric power grids—due to their increasing fraction of renewable energy sources—a pressing challenge is to fit the fluctuations in decentralized supply to the distributed and temporally varying demands. To achieve this goal, common smart grid concepts suggest to collect consumer demand data, centrally evaluate them given current supply and send price information back to customers for them to decide about usage. Besides restrictions regarding cyber security, privacy protection and large required investments, it remains unclear how such central smart grid options guarantee overall stability. Here we propose a Decentral Smart Grid Control, where the price is directly linked to the local grid frequency at each customer. The grid frequency provides all necessary information about the current power balance such that it is sufficient to match supply and demand without the need for a centralized IT infrastructure. We analyze the performance and the dynamical stability of the power grid with such a control system. Our results suggest that the proposed Decentral Smart Grid Control is feasible independent of effective measurement delays, if frequencies are averaged over sufficiently large time intervals.

  15. Tax Coordination and Unemployment

    Microsoft Academic Search

    Clemens Fuest; Bernd Huber

    1999-01-01

    This paper analyses the implications of unemployment for fiscal competition and tax coordination among small open economies.\\u000a Unemployment is modeled as resulting from wage bargaining. The analysis focuses on the effect of labour and capital tax coordination\\u000a on welfare. We show that, while coordinated capital and labour tax increases unambiguously raise welfare if labour markets\\u000a are competitive, different results emerge

  16. CaGrid Workflow Toolkit: A taverna based workflow tool for cancer grid

    PubMed Central

    2010-01-01

    Background In biological and medical domain, the use of web services made the data and computation functionality accessible in a unified manner, which helped automate the data pipeline that was previously performed manually. Workflow technology is widely used in the orchestration of multiple services to facilitate in-silico research. Cancer Biomedical Informatics Grid (caBIG) is an information network enabling the sharing of cancer research related resources and caGrid is its underlying service-based computation infrastructure. CaBIG requires that services are composed and orchestrated in a given sequence to realize data pipelines, which are often called scientific workflows. Results CaGrid selected Taverna as its workflow execution system of choice due to its integration with web service technology and support for a wide range of web services, plug-in architecture to cater for easy integration of third party extensions, etc. The caGrid Workflow Toolkit (or the toolkit for short), an extension to the Taverna workflow system, is designed and implemented to ease building and running caGrid workflows. It provides users with support for various phases in using workflows: service discovery, composition and orchestration, data access, and secure service invocation, which have been identified by the caGrid community as challenging in a multi-institutional and cross-discipline domain. Conclusions By extending the Taverna Workbench, caGrid Workflow Toolkit provided a comprehensive solution to compose and coordinate services in caGrid, which would otherwise remain isolated and disconnected from each other. Using it users can access more than 140 services and are offered with a rich set of features including discovery of data and analytical services, query and transfer of data, security protections for service invocations, state management in service interactions, and sharing of workflows, experiences and best practices. The proposed solution is general enough to be applicable and reusable within other service-computing infrastructures that leverage similar technology stack. PMID:21044328

  17. A boundary conforming structured grid for global ocean circulation studies

    Microsoft Academic Search

    William S. Russell; Peter R. Eiseman

    1998-01-01

    A boundary conforming two-dimensional structured grid for the irregular domain of the world's ocean is generated numerically using differential equation techniques. It is calculated using block structured methods which allow the inclusion of all major bodies of water including seas and basins, and which preserve slope continuity of the co-ordinate lines across the global domain. The block structure is coupled

  18. The Development of a Grid-based Engineering Design Problem

    E-print Network

    Sóbester, András

    trial or wind tunnel results in aerospace design problems) in order to decide where new problem analyses Grid Resource Allocation Management (GRAM) protocol and client API: Rapid advances in commodity; advanced infrastructures designed to enable the co-ordinated use of distributed high performance

  19. Basal ganglia outputs map instantaneous position coordinates during behavior.

    PubMed

    Barter, Joseph W; Li, Suellen; Sukharnikova, Tatyana; Rossi, Mark A; Bartholomew, Ryan A; Yin, Henry H

    2015-02-11

    The basal ganglia (BG) are implicated in many movement disorders, yet how they contribute to movement remains unclear. Using wireless in vivo recording, we measured BG output from the substantia nigra pars reticulata (SNr) in mice while monitoring their movements with video tracking. The firing rate of most nigral neurons reflected Cartesian coordinates (either x- or y-coordinates) of the animal's head position during movement. The firing rates of SNr neurons are either positively or negatively correlated with the coordinates. Using an egocentric reference frame, four types of neurons can be classified: each type increases firing during movement in a particular direction (left, right, up, down), and decreases firing during movement in the opposite direction. Given the high correlation between the firing rate and the x and y components of the position vector, the movement trajectory can be reconstructed from neural activity. Our results therefore demonstrate a quantitative and continuous relationship between BG output and behavior. Thus, a steady BG output signal from the SNr (i.e., constant firing rate) is associated with the lack of overt movement, when a stable posture is maintained by structures downstream of the BG. Any change in SNr firing rate is associated with a change in position (i.e., movement). We hypothesize that the SNr output quantitatively determines the direction, velocity, and amplitude of voluntary movements. By changing the reference signals to downstream position control systems, the BG can produce transitions in body configurations and initiate actions. PMID:25673860

  20. Modeling groundwater flow by lattice Boltzmann method in curvilinear coordinates

    NASA Astrophysics Data System (ADS)

    Budinski, Ljubomir; Fabian, Julius; Stipic, Matija

    2015-07-01

    In order to promote the use of the lattice Boltzmann method (LBM) for the simulation of isotropic groundwater flow in a confined aquifer with arbitrary geometry, Poisson's equation was transformed into a curvilinear coordinate system. With the metric function between the physical and the computational domain established, Poisson's equation written in Cartesian coordinates was transformed in curvilinear coordinates. Following, the appropriate equilibrium function for the D2Q9 square lattice has been defined. The resulting curvilinear formulation of the LBM for groundwater flow is capable of modeling flow in domains of complex geometry with the opportunity of local refining/coarsening of the computational mesh corresponding to the complexity of the flow pattern and the required accuracy. Since the proposed form of the LBM uses the transformed equation of flow implemented in the equilibrium function, finding a solution does not require supplementary procedures along the curvilinear boundaries, nor in the zones requiring mesh density adjustments. Thus, the basic concept of the LBM is completely maintained. The improvement of the proposed LBM over the previously published classical methods is completely verified by three examples with analytical solutions. The results demonstrate the advantages of the proposed curvilinear LBM in modeling groundwater flow in complex flow domains.

  1. Symmetrizing grids, radial basis functions, and Chebyshev and Zernike polynomials for the D4 symmetry group; Interpolation within a squircle, Part I

    NASA Astrophysics Data System (ADS)

    Li, Shan; Boyd, John P.

    2014-02-01

    A domain is invariant under the eight-element D4 symmetry group if it is unchanged by reflection with respect to the x and y axes and also the diagonal line x=y. Previous treatments of group theory for spectral methods have generally demanded a semester's worth of group theory. We show this is unnecessary by providing explicit recipes for creating grids, etc. We show how to decompose an arbitrary function into six symmetry-invariant components, and thereby split the interpolation problem into six independent subproblems. We also show how to make symmetry-invariant basis functions from products of Chebyshev polynomials, from Zernike polynomials and from radial basis functions (RBFs) of any species. These recipes are completely general, and apply to any domain that is invariant under the dihedral group D4. These concepts are illustrated by RBF pseudospectral solutions of the Poisson equation in a domain bounded by a squircle, the square-with-rounded corners defined by x2?+y2?-1=0 where here ?=2. We also apply Chebyshev polynomials to compute eigenmodes of the Helmholtz equation on the square and show each mode belongs to one and only one of the six D4 classes. [F. Albert Cotton, in: Chemical Applications of Group Theory, John Wiley, New York, 1963, p. vii]Cartesian coordinates. Znm(x,y), the Zernike polynomials. Radial basis functions (RBFs). We shall show how to rearrange each basis into six disjoint sets which are eigenfunctions of the operations of the group. We shall then explain how the interpolation problem with N points can be split into four problems of size N/8 and two problems of size N/4 with an enormous reduction of cost.First, though, we shall provide a brief overview of the D4 symmetry group.

  2. Wireless Grids Working Paper 2 Coordinating User and Device Behaviour in Wireless Grids

    E-print Network

    Howison, James

    Knight, William Lehr and James Howison October 2003 The evolution of computing has lead to networks which al. (2003), Gaynor et al. (2003), McKnight & Howison (2003). This article discusses the implications, as identified by our preliminary research on this issue Gaynor et al. (2003), McKnight & Howison (2003), Mc

  3. Reentry-Vehicle Shape Optimization Using a Cartesian Adjoint Method and CAD Geometry

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.

    2006-01-01

    A DJOINT solutions of the governing flow equations are becoming increasingly important for the development of efficient analysis and optimization algorithms. A well-known use of the adjoint method is gradient-based shape. Given an objective function that defines some measure of performance, such as the lift and drag functionals, its gradient is computed at a cost that is essentially independent of the number of design variables (e.g., geometric parameters that control the shape). Classic aerodynamic applications of gradient-based optimization include the design of cruise configurations for transonic and supersonic flow, as well as the design of high-lift systems. are perhaps the most promising approach for addressing the issues of flow solution automation for aerodynamic design problems. In these methods, the discretization of the wetted surface is decoupled from that of the volume mesh. This not only enables fast and robust mesh generation for geometry of arbitrary complexity, but also facilitates access to geometry modeling and manipulation using parametric computer-aided design (CAD). In previous work on Cartesian adjoint solvers, Melvin et al. developed an adjoint formulation for the TRANAIR code, which is based on the full-potential equation with viscous corrections. More recently, Dadone and Grossman presented an adjoint formulation for the two-dimensional Euler equations using a ghost-cell method to enforce the wall boundary conditions. In Refs. 18 and 19, we presented an accurate and efficient algorithm for the solution of the adjoint Euler equations discretized on Cartesian meshes with embedded, cut-cell boundaries. Novel aspects of the algorithm were the computation of surface shape sensitivities for triangulations based on parametric-CAD models and the linearization of the coupling between the surface triangulation and the cut-cells. The accuracy of the gradient computation was verified using several three-dimensional test cases, which included design variables such as the free stream parameters and the planform shape of an isolated wing. The objective of the present work is to extend our adjoint formulation to problems involving general shape changes. Factors under consideration include the computation of mesh sensitivities that provide a reliable approximation of the objective function gradient, as well as the computation of surface shape sensitivities based on a direct-CAD interface. We present detailed gradient verification studies and then focus on a shape optimization problem for an Apollo-like reentry vehicle. The goal of the optimization is to enhance the lift-to-drag ratio of the capsule by modifying the shape of its heat-shield in conjunction with a center-of-gravity (c.g.) offset. This multipoint and multi-objective optimization problem is used to demonstrate the overall effectiveness of the Cartesian adjoint method for addressing the issues of complex aerodynamic design.

  4. Continuous Parallel Coordinates Julian Heinrich and Daniel Weiskopf, Member, IEEE Computer Society

    E-print Network

    Gousie, Michael B.

    of patterns which otherwise are difficult to spot. For the visualization of large scientific data, we schemes, defined on a continuous domain. The visualization of such data in parallel coordinates may reveal parallel coordinates interpolate data values within grid cells, a scalable and dense visualization

  5. Grid-independent LES

    NASA Astrophysics Data System (ADS)

    Bose, Sanjeeb; Moin, Parviz

    2009-11-01

    Grid independent turbulent statistics are obtained in a planar channel flow at Re?= 640 by explicit filtering the governing equations for LES. Three dimensional filters (Vasilyev et al., JCP, 1998) are utilized such that commutation error is the same order as the truncation error of the fourth-order, conservative finite difference scheme (Morinishi et al., JCP, 1998). Several calculations are performed with a fixed filter width, but with varying grid resolutions. The grid-independent mean velocity profile is in good agreement with the experimental data of Hussain & Reynolds (1970). The rms velocity profiles and one-dimensional energy spectra are compared with previous LES results and the unfiltered DNS of Abe et al. (2001), and show convergence toward a grid-independent profile. Ensemble averaged contributions of the dynamic Smagorinsky subgrid model to the Reynolds shear stress have also converged to a grid-independent profile across all grid resolutions. The effect of effective filter shape on the convergence of turbulence statistics will be discussed. Progress in the development of grid-independent LES for complex geometries with unstructured meshes will be presented.

  6. The open science grid

    SciTech Connect

    Pordes, R.; /Fermilab

    2004-12-01

    The U.S. LHC Tier-1 and Tier-2 laboratories and universities are developing production Grids to support LHC applications running across a worldwide Grid computing system. Together with partners in computer science, physics grid projects and active experiments, we will build a common national production grid infrastructure which is open in its architecture, implementation and use. The Open Science Grid (OSG) model builds upon the successful approach of last year's joint Grid2003 project. The Grid3 shared infrastructure has for over eight months provided significant computational resources and throughput to a range of applications, including ATLAS and CMS data challenges, SDSS, LIGO, and biology analyses, and computer science demonstrators and experiments. To move towards LHC-scale data management, access and analysis capabilities, we must increase the scale, services, and sustainability of the current infrastructure by an order of magnitude or more. Thus, we must achieve a significant upgrade in its functionalities and technologies. The initial OSG partners will build upon a fully usable, sustainable and robust grid. Initial partners include the US LHC collaborations, DOE & NSF Laboratories and Universities & Trillium Grid projects. The approach is to federate with other application communities in the U.S. to build a shared infrastructure open to other sciences and capable of being modified and improved to respond to needs of other applications, including CDF, D0, BaBar, and RHIC experiments. We describe the application-driven, engineered services of the OSG, short term plans and status, and the roadmap for a consortium, its partnerships and national focus.

  7. Heliospheric coordinate systems

    Microsoft Academic Search

    M. Fränz; D. Harper

    2002-01-01

    This article gives an overview and reference to the most common coordinate systems currently used in space science. While coordinate systems used in near-Earth space physics have been described in previous work we extend that description to systems used for physical observations of the Sun and the planets and to systems based on spacecraft location. For all systems, we define

  8. Interstate Solar Coordination Council

    Microsoft Academic Search

    D. L. Block; R. D

    1981-01-01

    The Interstate Solar Coordination Council (ISCC) was established and held its first meeting January 31, 1980, for the purpose of developing a national forum for discussion and actions on common issues among solar energy-related state agencies. ISCC's general objectives are to establish a mechanism for voluntary exchange of information, coordination of solar standards and certification programs, and development of understanding

  9. Transition Coordinators: Define Yourselves.

    ERIC Educational Resources Information Center

    Asselin, Susan B.; Todd-Allen, Mary; deFur, Sharon

    1998-01-01

    Describes a technique that was used successfully to identify the changing roles and responsibilities of special educators as transition coordinators. The Developing a Curriculum (DACUM) model uses people who are currently working in the occupation to define job responsibilities. The duties of a transition coordinator are identified. (CR)

  10. Computational fluid dynamics for propulsion technology: Geometric grid visualization in CFD-based propulsion technology research

    NASA Technical Reports Server (NTRS)

    Ziebarth, John P.; Meyer, Doug

    1992-01-01

    The coordination is examined of necessary resources, facilities, and special personnel to provide technical integration activities in the area of computational fluid dynamics applied to propulsion technology. Involved is the coordination of CFD activities between government, industry, and universities. Current geometry modeling, grid generation, and graphical methods are established to use in the analysis of CFD design methodologies.

  11. The TeraGrid

    NSDL National Science Digital Library

    Catlett, Charlie.

    2002-01-01

    A project of the National Science Foundation, the TeraGrid is "a multi-year effort to build and deploy the world's largest, fastest, distributed infrastructure for open scientific research." This paper, published in September 2002, describes the activities and ongoing projects that will ultimately lead to the project's completion. TeraGrid, as the name implies, is based on principles of grid computing. It will eventually consist of a massive network of computers spread out over several sites that can work simultaneously and independently on scientific applications. Many specifications and design objectives are outlined in the paper, offering some insight into the ambitious project.

  12. A breakthrough in neuroscience needs a "Nebulous Cartesian System" Oscillations, quantum dynamics and chaos in the brain and vegetative system.

    PubMed

    Ba?ar, Erol; Güntekin, Bahar

    2007-04-01

    The Cartesian System is a fundamental conceptual and analytical framework related and interwoven with the concept and applications of Newtonian Dynamics. In order to analyze quantum processes physicist moved to a Probabilistic Cartesian System in which the causality principle became a probabilistic one. This means the trajectories of particles (obeying quantum rules) can be described only with the concept of cloudy wave packets. The approach to the brain-body-mind problem requires more than the prerequisite of modern physics and quantum dynamics. In the analysis of the brain-body-mind construct we have to include uncertain causalities and consequently multiple uncertain causalities. These multiple causalities originate from (1) nonlinear properties of the vegetative system (e.g. irregularities in biochemical transmitters, cardiac output, turbulences in the vascular system, respiratory apnea, nonlinear oscillatory interactions in peristalsis); (2) nonlinear behavior of the neuronal electricity (e.g. chaotic behavior measured by EEG), (3) genetic modulations, and (4) additional to these physiological entities nonlinear properties of physical processes in the body. The brain shows deterministic chaos with a correlation dimension of approx. D(2)=6, the smooth muscles approx. D(2)=3. According to these facts we propose a hyper-probabilistic approach or a hyper-probabilistic Cartesian System to describe and analyze the processes in the brain-body-mind system. If we add aspects as our sentiments, emotions and creativity to this construct, better said to this already hyper-probabilistic construct, this "New Cartesian System" is more than hyper-probabilistic, it is a nebulous system, we can predict the future only in a nebulous way; however, despite this chain of reasoning we can still provide predictions on brain-body-mind incorporations. We tentatively assume that the processes or mechanisms of the brain-body-mind system can be analyzed and predicted similar to the metaphor of "finding the walking path in a cloudy or foggy day". This is meant by stating "The Nebulous Cartesian System" (NCS). Descartes, at his time undertaking his genius step, did not possess the knowledge of today's physiology and modern physics; we think that the time has come to consider such a New Cartesian System. To deal with this, we propose the utilization of the Heisenberg S-Matrix and a modified version of the Feynman Diagrams which we call "Brain Feynman Diagrams". Another metaphor to consider within the oscillatory approach of the NCS is the "string theory". We also emphasize that fundamental steps should be undertaken in order to create the own dynamical framework of the brain-body-mind incorporation; suggestions or metaphors from physics and mathematics are useful; however, the grammar of the brains intrinsic language must be understood with the help of a new biologically founded, adaptive-probabilistic Cartesian system. This new Cartesian System will undergo mutations and transcend to the philosophy of Henri Bergson in parallel to the Evolution theory of Charles Darwin to open gateways for approaching the brain-body-mind problem. PMID:17049654

  13. myGrid: personalised bioinformatics on the information grid

    Microsoft Academic Search

    Robert D. Stevens; Alan J. Robinson; Carole A. Goble

    2003-01-01

    Motivation: The my Grid project aims to exploit Grid technology, with an emphasis on the Information Grid, and provide middleware layers that make it appropriate for the needs of bioinformatics. my Grid is building high level services for data and application integration such as resource discovery, workflow enactment and distributed query processing. Additional services are provided to support the scientific

  14. Exploiting the Computational Grid Lecture 1 Globus and the Grid

    E-print Network

    & procedures ­ security protocols must be widely applicable, standard and well tested and understood. · GSI Services ­ Grid Resource Information Protocol (GRIP) · Data Management ­ Grid FTP · Security is essential is the leading toolkit · Open source · Implements standard grid protocols and APIs · Grid-enabled tools

  15. The gridded electromagnet probe

    E-print Network

    Shadman, K. (Khashayar), 1972-

    2003-01-01

    We attempted to measure the anisotropy in the electron distribution function in magnetized plasma by exploiting the adiabatic invariance of the electron's magnetic moment with a probe comprising a grid, a collector, and ...

  16. Distributed Adaptive Grid Hierarchy

    NSDL National Science Digital Library

    DAGH (which stands for Distributed Adaptive Grid Hierarchy) was developed as a computational toolkit for the Binary Black Hole NSF Grand Challenge Project. It provides the framework to solve systems of partial differential equations using adaptive finite difference methods.

  17. IDL Grid Web Portal

    NASA Astrophysics Data System (ADS)

    Massimino, P.; Costa, A.

    2008-08-01

    Image Data Language is a software for data analysis, visualization and cross-platform application development. The potentiality of IDL is well-known in the academic scientific world, especially in the astronomical environment where thousands of procedures are developed by using IDL. The typical use of IDL is the interactive mode but it is also possible to run IDL programs that do not require any interaction with the user, submitting them in batch or background modality. Through the interactive mode the user immediately receives images or other data produced in the running phase of the program; in batch or background mode, the user will have to wait for the end of the program, sometime for many hours or days to obtain images or data that IDL produced as output: in fact in Grid environment it is possible to access to or retrieve data only after completion of the program. The work that we present gives flexibility to IDL procedures submitted to the Grid computer infrastructure. For this purpose we have developed an IDL Grid Web Portal to allow the user to access the Grid and to submit IDL programs granting a full job control and the access to images and data generated during the running phase, without waiting for their completion. We have used the PHP technology and we have given the same level of security that Grid normally offers to its users. In this way, when the user notices that the intermediate program results are not those expected, he can stop the job, change the parameters to better satisfy the computational algorithm and resubmit the program, without consuming the CPU time and other Grid resources. The IDL Grid Web Portal allows you to obtain IDL generated images, graphics and data tables by using a normal browser. All conversations from the user and the Grid resources occur via Web, as well as authentication phases. The IDL user has not to change the program source much because the Portal will automatically introduce the appropriate modification before submitting the IDL program to the Grid. When the user wishes, he will be able to check the status of his program and outputs, if any, because the Portal will assign the users a specific and univocal session identification number. This Web portal runs in the Trinacria Grid Virtual Laboratory and fully exploits the power of this grid in terms of CPU and data storage.

  18. Two-dimensional anisotropic Cartesian mesh adaptation for the compressible Euler equations

    NASA Astrophysics Data System (ADS)

    Keats, W. A.; Lien, F.-S.

    2004-12-01

    Simulating transient compressible flows involving shock waves presents challenges to the CFD practitioner in terms of the mesh quality required to resolve discontinuities and prevent smearing. This paper discusses a novel two-dimensional Cartesian anisotropic mesh adaptation technique implemented for transient compressible flow. This technique, originally developed for laminar incompressible flow, is efficient because it refines and coarsens cells using criteria that consider the solution in each of the cardinal directions separately. In this paper, the method will be applied to compressible flow. The procedure shows promise in its ability to deliver good quality solutions while achieving computational savings.Transient shock wave diffraction over a backward step and shock reflection over a forward step are considered as test cases because they demonstrate that the quality of the solution can be maintained as the mesh is refined and coarsened in time. The data structure is explained in relation to the computational mesh, and the object-oriented design and implementation of the code is presented. Refinement and coarsening algorithms are outlined. Computational savings over uniform and isotropic mesh approaches are shown to be significant.

  19. Development of a new two-dimensional Cartesian geometry nodal multigroup discrete-ordinates method

    SciTech Connect

    Pevey, R.E.

    1982-07-01

    The purpose of this work is the development and testing of a new family of methods for calculating the spatial dependence of the neutron density in nuclear systems described in two-dimensional Cartesian geometry. The energy and angular dependence of the neutron density is approximated using the multigroup and discrete ordinates techniques, respectively. The resulting FORTRAN computer code is designed to handle an arbitrary number of spatial, energy, and angle subdivisions. Any degree of scattering anisotropy can be handled by the code for either external source or fission systems. The basic approach is to (1) approximate the spatial variation of the neutron source across each spatial subdivision as an expansion in terms of a user-supplied set of exponential basis functions; (2) solve analytically for the resulting neutron density inside each region; and (3) approximate this density in the basis function space in order to calculate the next iteration flux-dependent source terms. In the general case the calculation is iterative due to neutron sources which depend on the neutron density itself, such as scattering interactions.

  20. Sadness as a passion of the soul: a psychopathological consideration of the Cartesian concept of melancholy.

    PubMed

    López-Muñoz, Francisco; Rubio, Gabriel; Molina, Juan D; Alamo, Cecilio

    2011-04-25

    The relationship between the "passions" (emotions or feelings) and psychopathology has been a constant throughout the history of medicine. In this context, melancholy was considered a perversion of the soul (corruption of the passions). One of the most influential authors on this subject was René Descartes, who discussed it in his work The Treatise on the Passions of the Soul (1649). Descartes believed that "passions" were sensitive movements that the soul experienced due to its union with the body (res extensa). According to this theory, the soul was located in the pineal gland, where it was actively involved in overseeing the functions of the "human machine" and kept its dysfunctions under control, by circulating animal spirits. Descartes described sadness as one of "the six primitive passions of the soul", which leads to melancholy if not remedied. Cartesian theories had a great deal of influence on the way that mental pathologies were considered throughout the entire 17th century (Spinoza, Willis, Pitcairn) and during much of the 18th century (Le Cat, Tissot). From the 19th century onwards, emotional symptomatology finally began to be used in diagnostic criteria for mood disorders. PMID:21315810

  1. On the Use of CAD and Cartesian Methods for Aerodynamic Optimization

    NASA Technical Reports Server (NTRS)

    Nemec, M.; Aftosmis, M. J.; Pulliam, T. H.

    2004-01-01

    The objective for this paper is to present the development of an optimization capability for Curt3D, a Cartesian inviscid-flow analysis package. We present the construction of a new optimization framework and we focus on the following issues: 1) Component-based geometry parameterization approach using parametric-CAD models and CAPRI. A novel geometry server is introduced that addresses the issue of parallel efficiency while only sparingly consuming CAD resources; 2) The use of genetic and gradient-based algorithms for three-dimensional aerodynamic design problems. The influence of noise on the optimization methods is studied. Our goal is to create a responsive and automated framework that efficiently identifies design modifications that result in substantial performance improvements. In addition, we examine the architectural issues associated with the deployment of a CAD-based approach in a heterogeneous parallel computing environment that contains both CAD workstations and dedicated compute engines. We demonstrate the effectiveness of the framework for a design problem that features topology changes and complex geometry.

  2. Spectra of Grid Turbulence

    Microsoft Academic Search

    Mahinder S. Uberoi; Stanley Wallis

    1969-01-01

    Energy spectra of the longitudinal and lateral turbulent velocities are measured behind grids of different geometries; the isotropic relation is not satisfied. Energy-dissipating eddies are more nearly isotropic than energy-containing eddies. Spectra of the energy-containing eddies and their deviation from isotropy depend on the grid geometry. Various microscales are measured to determine the anisotropy of the energy-dissipating eddies. The error

  3. Random array grid collimator

    DOEpatents

    Fenimore, E.E.

    1980-08-22

    A hexagonally shaped quasi-random no-two-holes touching grid collimator. The quasi-random array grid collimator eliminates contamination from small angle off-axis rays by using a no-two-holes-touching pattern which simultaneously provides for a self-supporting array increasng throughput by elimination of a substrate. The presentation invention also provides maximum throughput using hexagonally shaped holes in a hexagonal lattice pattern for diffraction limited applications. Mosaicking is also disclosed for reducing fabrication effort.

  4. Adaptive grid generation

    NASA Technical Reports Server (NTRS)

    Eiseman, Peter R.

    1987-01-01

    The fundamental principles of adaptive grid generation for the numerical analysis of physical phenomena described by systems of partial differential equations are examined in an analytical review. Topics addressed include weight functions, equidistribution in one dimension, the specification of coefficients in the linear weight, the attraction to a given grid on a curve, evolutionary forces, and metric notation. Consideration is given to curve-by-curve methods, finite-volume methods, variational methods, and temporal aspects.

  5. MicroGrids

    Microsoft Academic Search

    R. H. Lasseter

    2002-01-01

    The MicroGrid concept assumes a cluster of loads and microsources (<100 kW) operating as a single controllable system that provides both power and heat to its local area. This concept provides a new paradigm for defining the operation of distributed generation. To the utility the MicroGrid can be thought of as a controlled cell of the power system. For example

  6. Generation of orthogonal grids by boundary grid relaxation

    NASA Technical Reports Server (NTRS)

    Nakamura, S.

    1983-01-01

    Two elliptic grid generation schemes that yield orthogonal grids are presented (FGBR and UBGR). With the UBGR scheme, the grid points on the flow boundaries are automatically determined by the algorithm, while the FBGR scheme at most one half of the boundary grid points may be prespecified and the remainder of boundary grid points are determined automatically. Numerical examples show their capability of easy stretching, clustering and shock fitting while maintaining orthogonality of grid. The present method can be implemented into existing elliptic grid generation programs with relatively minor modifications.

  7. Grid-based molecular footprint comparison method for docking and de novo design: application to HIVgp41.

    PubMed

    Balius, Trent E; Allen, William J; Mukherjee, Sudipto; Rizzo, Robert C

    2013-05-30

    Scoring functions are a critically important component of computer-aided screening methods for the identification of lead compounds during early stages of drug discovery. Here, we present a new multigrid implementation of the footprint similarity (FPS) scoring function that was recently developed in our laboratory which has proven useful for identification of compounds which bind to a protein on a per-residue basis in a way that resembles a known reference. The grid-based FPS method is much faster than its Cartesian-space counterpart, which makes it computationally tractable for on-the-fly docking, virtual screening, or de novo design. In this work, we establish that: (i) relatively few grids can be used to accurately approximate Cartesian space footprint similarity, (ii) the method yields improved success over the standard DOCK energy function for pose identification across a large test set of experimental co-crystal structures, for crossdocking, and for database enrichment, and (iii) grid-based FPS scoring can be used to tailor construction of new molecules to have specific properties, as demonstrated in a series of test cases targeting the viral protein HIVgp41. The method is available in the program DOCK6. PMID:23436713

  8. Exploring Hypersonic, Unstructured-Grid Issues through Structured Grids

    NASA Technical Reports Server (NTRS)

    Mazaheri, Ali R.; Kleb, Bill

    2007-01-01

    Pure-tetrahedral unstructured grids have been shown to produce asymmetric heat transfer rates for symmetric problems. Meanwhile, two-dimensional structured grids produce symmetric solutions and as documented here, introducing a spanwise degree of freedom to these structured grids also yields symmetric solutions. The effects of grid skewness and other perturbations of structured-grids are investigated to uncover possible mechanisms behind the unstructured-grid solution asymmetries. By using controlled experiments around a known, good solution, the effects of particular grid pathologies are uncovered. These structured-grid experiments reveal that similar solution degradation occurs as for unstructured grids, especially for heat transfer rates. Non-smooth grids within the boundary layer is also shown to produce large local errors in heat flux but do not affect surface pressures.

  9. GridLab: Enabling Applications on the Grid

    Microsoft Academic Search

    Gabrielle Allen; Dave Angulo; Tom Goodale; Thilo Kielmann; André Merzky; Jarek Nabrzyski; Juliusz Pukacki; Michael Russell; Thomas Radke; Edward Seidel; John Shalf; Ian J. Taylor

    2002-01-01

    Grid technology is widely emerging. Still, there is an eminent shortage of real Grid users, due to the absence of two important\\u000a catalysts: First, a widely accepted vision on how applications can substantially benefit from Grids, and second a toolkit\\u000a of higher-level Grid services, tailored to application needs. The GridLab project aims to provide fundamentally new capabilities\\u000a for applications to

  10. Arc Length Based Grid Distribution For Surface and Volume Grids

    NASA Technical Reports Server (NTRS)

    Mastin, C. Wayne

    1996-01-01

    Techniques are presented for distributing grid points on parametric surfaces and in volumes according to a specified distribution of arc length. Interpolation techniques are introduced which permit a given distribution of grid points on the edges of a three-dimensional grid block to be propagated through the surface and volume grids. Examples demonstrate how these methods can be used to improve the quality of grids generated by transfinite interpolation.

  11. A Java commodity grid kit

    Microsoft Academic Search

    Gregor Von Laszewski; Ian T. Foster; Jarek Gawor

    2001-01-01

    In this paper we report on the features of the Java Commodity Grid Kit. The Java CoG Kit provides middleware for accessing Grid functionality from the Java framework. Java CoG Kit middleware is general enough to design a variety of advanced Grid applications with quite different user requirements. Access to the Grid is established via Globus protocols, allowing the Java

  12. Contiguous gridded gun development program

    Microsoft Academic Search

    G. Huffman

    1980-01-01

    A gridded gun, suitable for operating megawatt level linear beam tubes, has been designed and tested at lower levels in a beam analyzer. The new gun features a shadow grid in contact with the cathode surface. A major goal was to achieve low control grid interception. Guns with contiguous grid systems are in common use in low and medium power

  13. Smart Grid Integration Laboratory

    SciTech Connect

    Wade Troxell

    2011-09-30

    The initial federal funding for the Colorado State University Smart Grid Integration Laboratory is through a Congressionally Directed Project (CDP), DE-OE0000070 Smart Grid Integration Laboratory. The original program requested in three one-year increments for staff acquisition, curriculum development, and instrumentation â?? all which will benefit the Laboratory. This report focuses on the initial phase of staff acquisition which was directed and administered by DOE NETL/ West Virginia under Project Officer Tom George. Using this CDP funding, we have developed the leadership and intellectual capacity for the SGIC. This was accomplished by investing (hiring) a core team of Smart Grid Systems engineering faculty focused on education, research, and innovation of a secure and smart grid infrastructure. The Smart Grid Integration Laboratory will be housed with the separately funded Integrid Laboratory as part of CSUâ??s overall Smart Grid Integration Center (SGIC). The period of performance of this grant was 10/1/2009 to 9/30/2011 which included one no cost extension due to time delays in faculty hiring. The Smart Grid Integration Laboratoryâ??s focus is to build foundations to help graduate and undergraduates acquire systems engineering knowledge; conduct innovative research; and team externally with grid smart organizations. Using the results of the separately funded Smart Grid Workforce Education Workshop (May 2009) sponsored by the City of Fort Collins, Northern Colorado Clean Energy Cluster, Colorado State University Continuing Education, Spirae, and Siemens has been used to guide the hiring of faculty, program curriculum and education plan. This project develops faculty leaders with the intellectual capacity to inspire its students to become leaders that substantially contribute to the development and maintenance of Smart Grid infrastructure through topics such as: (1) Distributed energy systems modeling and control; (2) Energy and power conversion; (3) Simulation of electrical power distribution system that integrates significant quantities of renewable and distributed energy resources; (4) System dynamic modeling that considers end-user behavior, economics, security and regulatory frameworks; (5) Best practices for energy management IT control solutions for effective distributed energy integration (including security with the underlying physical power systems); (6) Experimental verification of effects of various arrangements of renewable generation, distributed generation and user load types along with conventional generation and transmission. Understanding the core technologies for enabling them to be used in an integrated fashion within a distribution network remains is a benefit to the future energy paradigm and future and present energy engineers.

  14. HR COMMUNICATIONS Program Coordinator

    E-print Network

    Ronquist, Fredrik

    HR COMMUNICATIONS Program Coordinator 51518 9254 04 VACANT University Business Administrator II TECHNOLOGY/ HR DATA MANAGEMENT/ COMMUNICATIONS RECORDS BENEFITS TIME & LABOR EMPLOYEE DATA MANAGEMENT EMPLOYMENT FACILITIES SATELLITE OFFICE EMPLOYEE & LABOR RELATIONS Director, Admin Svcs 55607 9250A 07 VACANT

  15. Communication Gestion et coordination

    E-print Network

    Spino, Claude

    Communication Gestion et coordination de patrouilles environnementales Développement de stratégies et d'outils de communication en développement durable Communication des politiques, programmes et professionnels et responsables, capables d'intégrer les aspects sociaux et économiques dans leur processus de

  16. Muscular Dystrophy Coordinating Committee

    MedlinePLUS

    Muscular Dystrophy Coordinating Committee (MDCC) WE ARE NO LONGER ACCEPTING COMMENTS AND EDITS THROUGH THIS SITE. THIS COPY ... on the Draft 2015 Action Plan for the Muscular Dystrophies Draft 2015 Action Plan (PDF, 1.06MB) Request ...

  17. Integrating Renewable Electricity on the Grid

    NASA Astrophysics Data System (ADS)

    Crabtree, George; Misewich, Jim; Ambrosio, Ron; Clay, Kathryn; DeMartini, Paul; James, Revis; Lauby, Mark; Mohta, Vivek; Moura, John; Sauer, Peter; Slakey, Francis; Lieberman, Jodi; Tai, Humayun

    2011-11-01

    The demand for carbon-free electricity is driving a growing movement of adding renewable energy to the grid. Renewable Portfolio Standards mandated by states and under consideration by the federal government envision a penetration of 20-30% renewable energy in the grid by 2020 or 2030. The renewable energy potential of wind and solar far exceeds these targets, suggesting that renewable energy ultimately could grow well beyond these initial goals. The grid faces two new and fundamental technological challenges in accommodating renewables: location and variability. Renewable resources are concentrated at mid-continent far from population centers, requiring additional long distance, high-capacity transmission to match supply with demand. The variability of renewables due to the characteristics of weather is high, up to 70% for daytime solar due to passing clouds and 100% for wind on calm days, much larger than the relatively predictable uncertainty in load that the grid now accommodates by dispatching conventional resources in response to demand. Solutions to the challenges of remote location and variability of generation are needed. The options for DC transmission lines, favored over AC lines for transmission of more than a few hundred miles, need to be examined. Conventional high voltage DC transmission lines are a mature technology that can solve regional transmission needs covering one- or two-state areas. Conventional high voltage DC has drawbacks, however, of high loss, technically challenging and expensive conversion between AC and DC, and the requirement of a single point of origin and termination. Superconducting DC transmission lines lose little or no energy, produce no heat, and carry higher power density than conventional lines. They operate at moderate voltage, allowing many "on-ramps" and "off-ramps" in a single network and reduce the technical and cost challenges of AC to DC conversion. A network of superconducting DC cables overlaying the existing patchwork of conventional transmission lines would create an interstate highway system for electricity that moves large amounts of renewable electric power efficiently over long distances from source to load. Research and development is needed to identify the technical challenges associated with DC superconducting transmission and how it can be most effectively deployed. The challenge of variability can be met (i) by switching conventional generation capacity in or out in response to sophisticated forecasts of weather and power generation, (ii) by large scale energy storage in heat, pumped hydroelectric, compressed air or stationary batteries designed for the grid, or (iii) by national balancing of regional generation deficits and excesses using long distance transmission. Each of these solutions to variability has merit and each requires significant research and development to understand its capacity, performance, cost and effectiveness. The challenge of variability is likely to be met by a combination of these three solutions; the interactions among them and the appropriate mix needs to be explored. The long distances from renewable sources to demand centers span many of the grid's physical, ownership and regulatory boundaries. This introduces a new feature to grid structure and operation: national and regional coordination. The grid is historically a patchwork of local generation resources and load centers that has been built, operated and regulated to meet local needs. Although it is capable of sharing power across moderate distances, the arrangements for doing so are cumbersome and inefficient. The advent of renewable electricity with its enormous potential and inherent regional and national character presents an opportunity to examine the local structure of the grid and establish coordinating principles that will not only enable effective renewable integration but also simplify and codify the grid's increasingly regional and national character.

  18. Dynamics of Interpersonal Coordination

    Microsoft Academic Search

    Richard C. Schmidt; Michael J. Richardson

    Everyday human actions often occur in a social context. Past psychological research has found that the motor behavior of socially\\u000a situated individuals tends to be coordinated. Our research performed over the last 20 years has sought to understand how the\\u000a mutuality, accommodation, and synchrony found in everyday interactional coordination can be understood using a dynamical theory\\u000a of behavioral order, namely

  19. Regional Transportation Coordination Study

    E-print Network

    Golden Crescent Regional Planning Commission

    ? Regional Assessment and Needs Chapter 3 ? Peer Review Chapter 4 ? Barriers and Constraints Chapter 5 ? Pilot Projects Chapter 6 ? RTA and Funding Options Golden Crescent Regional Transit 1-10 Regional Transportation Coordination Study... ? Regional Assessment and Needs Chapter 3 ? Peer Review Chapter 4 ? Barriers and Constraints Chapter 5 ? Pilot Projects Chapter 6 ? RTA and Funding Options Golden Crescent Regional Transit 1-10 Regional Transportation Coordination Study...

  20. Grid-Based Workflow Management

    Microsoft Academic Search

    Daniel Becker; Morris Riedel; Achim Streit; Felix Wolf

    Many Grid infrastructures have begun to offer services to end-users during the past several years with an increasing number of complex scientific applications and software tools that require seamless access to different Grid resources via Grid middleware during one workflow. End-users of the rather hpc-driven deisa Grid infrastructure take not only advantage of Grid workflow management capabilities for massively parallel

  1. A second-order curvilinear to Cartesian transformation of immersed interfaces and

    E-print Network

    Boyer, Edmond

    in CFD simulations. How- ever, this kind of mesh structure involves many limitations on the shape of the transformed domain. Nevertheless, the question of the motion and reconstruction of the mesh (especially the im found some examples of ctitious domains on curvilinear grids in the literature. An adaptation of the VOF

  2. Splatting and its Applications on the Body-Centered Cartesian (BCC) Lattice

    E-print Network

    Zhang, Richard "Hao"

    ;5 Splatting: Concept ! The reconstruction can also be done in image space ! For X-ray, splatting yields an accurate projection this way · this has great potential for X-ray computed tomography (see later a transformation of the grid values #12;7 Splatting: X-Ray ! Example: projecting a volume of two points 3. 2. 1. 4

  3. An Approach for Dynamic Grids

    NASA Technical Reports Server (NTRS)

    Slater, John W.; Liou, Meng-Sing; Hindman, Richard G.

    1994-01-01

    An approach is presented for the generation of two-dimensional, structured, dynamic grids. The grid motion may be due to the motion of the boundaries of the computational domain or to the adaptation of the grid to the transient, physical solution. A time-dependent grid is computed through the time integration of the grid speeds which are computed from a system of grid speed equations. The grid speed equations are derived from the time-differentiation of the grid equations so as to ensure that the dynamic grid maintains the desired qualities of the static grid. The grid equations are the Euler-Lagrange equations derived from a variational statement for the grid. The dynamic grid method is demonstrated for a model problem involving boundary motion, an inviscid flow in a converging-diverging nozzle during startup, and a viscous flow over a flat plate with an impinging shock wave. It is shown that the approach is more accurate for transient flows than an approach in which the grid speeds are computed using a finite difference with respect to time of the grid. However, the approach requires significantly more computational effort.

  4. Marshall Space Flight Center surface modeling and grid generation applications

    NASA Astrophysics Data System (ADS)

    Williams, Robert W.; Benjamin, Theodore G.; Cornelison, Joni W.

    1995-03-01

    The Solid Rocket Motors (SRM) used by NASA to propel the Space Shuttle employ gimballing nozzles as a means for vehicular guidance during launch and ascent. Gimballing a nozzle renders the pressure field of the exhaust gases nonaxisymmetric. This has two effects: (1) it exerts a torque and side load on the nozzle; and (2) the exhaust gases flow circumferentially in the aft-dome region, thermally loading the flexible boot, case-to-nozzle joint, and casing insulation. The use of CFD models to simulate such flows is imperative in order to assess SRM design. The grids for these problems were constructed by obtaining information from drawings and tabulated coordinates. The 2D axisymmetric grids were designed and generated using the EZ-Surf and GEN2D surface and grid generation codes. These 2D grids were solved using codes such as FDNS, GASP, and MINT. These axisymmetric grids were rotated around the center-line to form 3D nongimballed grids. These were then gimballed around the pivot point and the gaps or overlaps resurfaced to obtain the final domains, which contained approximately 366,000 grid points. The 2D solutions were then rotated and manipulated as appropriate for geometry and used as initial guesses in the final solution. The analyses were used in answering questions about flight criteria.

  5. The anatomy of the grid : enabling scalable virtual organizations.

    SciTech Connect

    Foster, I.; Kesselman, C.; Tuecke, S.; Mathematics and Computer Science; Univ. of Chicago; Univ. of Southern California

    2001-10-01

    'Grid' computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and, in some cases, high performance orientation. In this article, the authors define this new field. First, they review the 'Grid problem,' which is defined as flexible, secure, coordinated resource sharing among dynamic collections of individuals, institutions, and resources -- what is referred to as virtual organizations. In such settings, unique authentication, authorization, resource access, resource discovery, and other challenges are encountered. It is this class of problem that is addressed by Grid technologies. Next, the authors present an extensible and open Grid architecture, in which protocols, services, application programming interfaces, and software development kits are categorized according to their roles in enabling resource sharing. The authors describe requirements that they believe any such mechanisms must satisfy and discuss the importance of defining a compact set of intergrid protocols to enable interoperability among different Grid systems. Finally, the authors discuss how Grid technologies relate to other contemporary technologies, including enterprise integration, application service provider, storage service provider, and peer-to-peer computing. They maintain that Grid concepts and technologies complement and have much to contribute to these other approaches.

  6. Grid cell spatial tuning reduced following systemic muscarinic receptor blockade.

    PubMed

    Newman, Ehren L; Climer, Jason R; Hasselmo, Michael E

    2014-06-01

    Grid cells of the medial entorhinal cortex exhibit a periodic and stable pattern of spatial tuning that may reflect the output of a path integration system. This grid pattern has been hypothesized to serve as a spatial coordinate system for navigation and memory function. The mechanisms underlying the generation of this characteristic tuning pattern remain poorly understood. Systemic administration of the muscarinic antagonist scopolamine flattens the typically positive correlation between running speed and entorhinal theta frequency in rats. The loss of this neural correlate of velocity, an important signal for the calculation of path integration, raises the question of what influence scopolamine has on the grid cell tuning as a read out of the path integration system. To test this, the spatial tuning properties of grid cells were compared before and after systemic administration of scopolamine as rats completed laps on a circle track for food rewards. The results show that the spatial tuning of the grid cells was reduced following scopolamine administration. The tuning of head direction cells, in contrast, was not reduced by scopolamine. This is the first report to demonstrate a link between cholinergic function and grid cell tuning. This work suggests that the loss of tuning in the grid cell network may underlie the navigational disorientation observed in Alzheimer's patients and elderly individuals with reduced cholinergic tone. PMID:24493379

  7. Grid cell spatial tuning reduced following systemic muscarinic receptor blockade

    PubMed Central

    Newman, Ehren L.; Climer, Jason R.; Hasselmo, Michael E.

    2014-01-01

    Grid cells of the medial entorhinal cortex exhibit a periodic and stable pattern of spatial tuning that may reflect the output of a path integration system. This grid pattern has been hypothesized to serve as a spatial coordinate system for navigation and memory function. The mechanisms underlying the generation of this characteristic tuning pattern remain poorly understood. Systemic administration of the muscarinic antagonist scopolamine flattens the typically positive correlation between running speed and entorhinal theta frequency in rats. The loss of this neural correlate of velocity, an important signal for the calculation of path integration, raises the question of what influence scopolamine has on the grid cell tuning as a read out of the path integration system. To test this, the spatial tuning properties of grid cells were compared before and after systemic administration of scopolamine as rats completed laps on a circle track for food rewards. The results show that the spatial tuning of the grid cells was reduced following scopolamine administration. The tuning of head direction cells, in contrast, was not reduced by scopolamine. This is the first report to demonstrate a link between cholinergic function and grid cell tuning. This work suggests that the loss of tuning in the grid cell network may underlie the navigational disorientation observed in Alzheimer's patients and elderly individuals with reduced cholinergic tone. PMID:24493379

  8. Marshall Space Flight Center surface modeling and grid generation applications

    NASA Technical Reports Server (NTRS)

    Williams, Robert W.; Benjamin, Theodore G.; Cornelison, Joni W.

    1995-01-01

    The Solid Rocket Motors (SRM) used by NASA to propel the Space Shuttle employ gimballing nozzles as a means for vehicular guidance during launch and ascent. Gimballing a nozzle renders the pressure field of the exhaust gases nonaxisymmetric. This has two effects: (1) it exerts a torque and side load on the nozzle; and (2) the exhaust gases flow circumferentially in the aft-dome region, thermally loading the flexible boot, case-to-nozzle joint, and casing insulation. The use of CFD models to simulate such flows is imperative in order to assess SRM design. The grids for these problems were constructed by obtaining information from drawings and tabulated coordinates. The 2D axisymmetric grids were designed and generated using the EZ-Surf and GEN2D surface and grid generation codes. These 2D grids were solved using codes such as FDNS, GASP, and MINT. These axisymmetric grids were rotated around the center-line to form 3D nongimballed grids. These were then gimballed around the pivot point and the gaps or overlaps resurfaced to obtain the final domains, which contained approximately 366,000 grid points. The 2D solutions were then rotated and manipulated as appropriate for geometry and used as initial guesses in the final solution. The analyses were used in answering questions about flight criteria.

  9. IEEE Smart Grid Series of Standards IEEE 2030 (Interoperability) and IEEE 1547 (Interconnection) Status: Preprint

    SciTech Connect

    Basso, T.; DeBlasio, R.

    2012-04-01

    The IEEE American National Standards smart grid publications and standards development projects IEEE 2030, which addresses smart grid interoperability, and IEEE 1547TM, which addresses distributed resources interconnection with the grid, have made substantial progress since 2009. The IEEE 2030TM and 1547 standards series focus on systems-level aspects and cover many of the technical integration issues involved in a mature smart grid. The status and highlights of these two IEEE series of standards, which are sponsored by IEEE Standards Coordinating Committee 21 (SCC21), are provided in this paper.

  10. NREL Smart Grid Projects

    SciTech Connect

    Hambrick, J.

    2012-01-01

    Although implementing Smart Grid projects at the distribution level provides many advantages and opportunities for advanced operation and control, a number of significant challenges must be overcome to maintain the high level of safety and reliability that the modern grid must provide. For example, while distributed generation (DG) promises to provide opportunities to increase reliability and efficiency and may provide grid support services such as volt/var control, the presence of DG can impact distribution operation and protection schemes. Additionally, the intermittent nature of many DG energy sources such as photovoltaics (PV) can present a number of challenges to voltage regulation, etc. This presentation provides an overview a number of Smart Grid projects being performed by the National Renewable Energy Laboratory (NREL) along with utility, industry, and academic partners. These projects include modeling and analysis of high penetration PV scenarios (with and without energy storage), development and testing of interconnection and microgrid equipment, as well as the development and implementation of advanced instrumentation and data acquisition used to analyze the impacts of intermittent renewable resources. Additionally, standards development associated with DG interconnection and analysis as well as Smart Grid interoperability will be discussed.

  11. Coordinate Representations for Interference Reduction in Motor Learning

    PubMed Central

    Yeo, Sang-Hoon; Wolpert, Daniel M.; Franklin, David W.

    2015-01-01

    When opposing force fields are presented alternately or randomly across trials for identical reaching movements, subjects learn neither force field, a behavior termed ‘interference’. Studies have shown that a small difference in the endpoint posture of the limb reduces this interference. However, any difference in the limb’s endpoint location typically changes the hand position, joint angles and the hand orientation making it ambiguous as to which of these changes underlies the ability to learn dynamics that normally interfere. Here we examine the extent to which each of these three possible coordinate systems—Cartesian hand position, shoulder and elbow joint angles, or hand orientation—underlies the reduction in interference. Subjects performed goal-directed reaching movements in five different limb configurations designed so that different pairs of these configurations involved a change in only one coordinate system. By specifically assigning clockwise and counter-clockwise force fields to the configurations we could create three different conditions in which the direction of the force field could only be uniquely distinguished in one of the three coordinate systems. We examined the ability to learn the two fields based on each of the coordinate systems. The largest reduction of interference was observed when the field direction was linked to the hand orientation with smaller reductions in the other two conditions. This result demonstrates that the strongest reduction in interference occurred with changes in the hand orientation, suggesting that hand orientation may have a privileged role in reducing motor interference for changes in the endpoint posture of the limb. PMID:26067480

  12. Advanced Techniques for Constrained Internal Coordinate Molecular Dynamics

    PubMed Central

    Wagner, Jeffrey R.; Balaraman, Gouthaman S.; Niesen, Michiel J. M.; Larsen, Adrien B.; Jain, Abhinandan; Vaidehi, Nagarajan

    2013-01-01

    Internal coordinate molecular dynamics (ICMD) methods provide a more natural description of a protein by using bond, angle and torsional coordinates instead of a Cartesian coordinate representation. Freezing high frequency bonds and angles in the ICMD model gives rise to constrained ICMD (CICMD) models. There are several theoretical aspects that need to be developed in order to make the CICMD method robust and widely usable. In this paper we have designed a new framework for 1) initializing velocities for non-independent CICMD coordinates, 2) efficient computation of center of mass velocity during CICMD simulations, 3) using advanced integrators such as Runge-Kutta, Lobatto and adaptive CVODE for CICMD simulations, and 4) cancelling out the “flying ice cube effect” that sometimes arises in Nosé-Hoover dynamics. The Generalized Newton-Euler Inverse Mass Operator (GNEIMO) method is an implementation of a CICMD method that we have developed to study protein dynamics. GNEIMO allows for a hierarchy of coarse-grained simulation models based on the ability to rigidly constrain any group of atoms. In this paper, we perform tests on the Lobatto and Runge-Kutta integrators to determine optimal simulation parameters. We also implement an adaptive coarse graining tool using the GNEIMO Python interface. This tool enables the secondary structure-guided “freezing and thawing” of degrees of freedom in the molecule on the fly during MD simulations, and is shown to fold four proteins to their native topologies. With these advancements we envision the use of the GNEIMO method in protein structure prediction, structure refinement, and in studying domain motion. PMID:23345138

  13. Evolution of cartesian genetic programs for development of learning neural architecture.

    PubMed

    Khan, Gul Muhammad; Miller, Julian F; Halliday, David M

    2011-01-01

    Although artificial neural networks have taken their inspiration from natural neurological systems, they have largely ignored the genetic basis of neural functions. Indeed, evolutionary approaches have mainly assumed that neural learning is associated with the adjustment of synaptic weights. The goal of this paper is to use evolutionary approaches to find suitable computational functions that are analogous to natural sub-components of biological neurons and demonstrate that intelligent behavior can be produced as a result of this additional biological plausibility. Our model allows neurons, dendrites, and axon branches to grow or die so that synaptic morphology can change and affect information processing while solving a computational problem. The compartmental model of a neuron consists of a collection of seven chromosomes encoding distinct computational functions inside the neuron. Since the equivalent computational functions of neural components are very complex and in some cases unknown, we have used a form of genetic programming known as Cartesian genetic programming (CGP) to obtain these functions. We start with a small random network of soma, dendrites, and neurites that develops during problem solving by repeatedly executing the seven chromosomal programs that have been found by evolution. We have evaluated the learning potential of this system in the context of a well-known single agent learning problem, known as Wumpus World. We also examined the harder problem of learning in a competitive environment for two antagonistic agents, in which both agents are controlled by independent CGP computational networks (CGPCN). Our results show that the agents exhibit interesting learning capabilities. PMID:21591889

  14. Information Power Grid Posters

    NASA Technical Reports Server (NTRS)

    Vaziri, Arsi

    2003-01-01

    This document is a summary of the accomplishments of the Information Power Grid (IPG). Grids are an emerging technology that provide seamless and uniform access to the geographically dispersed, computational, data storage, networking, instruments, and software resources needed for solving large-scale scientific and engineering problems. The goal of the NASA IPG is to use NASA's remotely located computing and data system resources to build distributed systems that can address problems that are too large or complex for a single site. The accomplishments outlined in this poster presentation are: access to distributed data, IPG heterogeneous computing, integration of large-scale computing node into distributed environment, remote access to high data rate instruments,and exploratory grid environment.

  15. Application of wall functions to generalized nonorthogonal curvilinear coordinate systems

    NASA Astrophysics Data System (ADS)

    Sondak, Douglas L.; Pletcher, Richard H.

    1995-01-01

    A method has been developed for the application of wall functions to generalized curvilinear coordinate systems with nonorthogonal grids. Two test cases have been computed using this method with the k-epsilon turbulence model: flow over a flat plate at 0-deg angle of attack using a nonorthogonal grid at the wall and flow over a prolate hemispheroid with a hemispherical nose cap at 0-deg angle of attack. All results are compared with experimental data. In addition, the hemispheroid results are compared with computations using the Baldwin-Lomax algebraic turbulence model and the Chien low-Reynolds-number k-epsilon turbulence model.

  16. Elliptic surface grid generation in three-dimensional space

    NASA Technical Reports Server (NTRS)

    Kania, Lee

    1992-01-01

    A methodology for surface grid generation in three dimensional space is described. The method solves a Poisson equation for each coordinate on arbitrary surfaces using successive line over-relaxation. The complete surface curvature terms were discretized and retained within the nonhomogeneous term in order to preserve surface definition; there is no need for conventional surface splines. Control functions were formulated to permit control of grid orthogonality and spacing. A method for interpolation of control functions into the domain was devised which permits their specification not only at the surface boundaries but within the interior as well. An interactive surface generation code which makes use of this methodology is currently under development.

  17. Developments of the Orthogonal Curvilinear Terrain-Following Coordinate: the New Basis Vectors

    NASA Astrophysics Data System (ADS)

    Li, J.; Li, Y.; Wang, B.

    2014-12-01

    We have developed the orthogonal curvilinear terrain-following coordinate (OS-coordinate) proposed by Li et al. (2014), especially focusing on the restriction of the time step in the OS-coordinate. We first propose two new methods to solve the basis vectors of the OS-coordinate, both of which avoid the spatial rotation proposed by Li et al. (2014), therefore simplifying the solving procedure of the OS-coordinate. Moreover, for the major drawback of the OS-coordinate, which is the convergence and the divergence of the grid-lines pointed out by Li et al. (2014), we revise their basis vectors and design a new general rotation parameter to create the new basis vectors of the OS-coordinate. The experimental results show that using these new basis vectors, we can improve the orthogonality of the 3-D coordinate surfaces of the OS-coordinate. More importantly, we can easily control the distance between the neighbour grid-lines, therefore alleviating the restriction of the time step in the OS-coordinate. These have been validated by the idealized Schär-type advection experiments.

  18. An overset grid method for global geomagnetic induction

    NASA Astrophysics Data System (ADS)

    Weiss, Chester J.

    2014-07-01

    A new finite difference solution to the global geomagnetic induction problem is developed and tested, based on a modified Lorenz gauge of the magnetic vector and electric scalar potentials and implementing a novel, overset `Yin-Yang' grid that avoids unnecessary mesh refinement at the geographic poles. Previously used in whole-earth mantle convection models, the overset grid is built from a pair of partially overlapping mid-latitude latitude-longitude (lat/lon) grids, one of which is rotated with respect to the other for complete coverage of the sphere. Because of this symmetry, only one set of finite difference templates is required for global discretization of the governing Maxwell equations, a redundancy that is exploited for computational efficiency and multithreaded parallelization. Comparisons between solutions obtained by the proposed method show excellent agreement with those obtained by independent integral equation methods for 1-D, 2-D and 3-D problem geometries. The computational footprint of the method is minimized through a (non-symmetric) matrix-free BiCG-STAB iterative solver which computes finite difference matrix coefficients `on the fly' as needed, rather than pulling stored values from memory. Scaling of the matrix-free BiCG-STAB algorithm with problem size shows behaviour similar to that seen with the (symmetric) QMR algorithm used in the Cartesian case from which the present algorithm is based. The proposed method may therefore provide a competitive addition to the existing body of global-scale geomagnetic induction modelling algorithms, allowing for resource-efficient forward modelling as the kernel for large-scale computing such as inversion of geomagnetic response functions, computational hypothesis testing and parametric studies of mantle geodynamics and physiochemical state.

  19. A Framework of Coordinated Defense

    Microsoft Academic Search

    Shuyuan Mary Ho

    Coordinated defense in cyber warfare has emerged to protect information as assets through the use of technologies, policy, and best management practices for defending against coordinated attacks. However, combining massive security technologies, policies, procedures and security staff does not guarantee the effectiveness of defense. Without a well-defined and structured element of coordination, an organization can not stand firm during coordinated

  20. Automated Evaluation of Coordination Approaches

    Microsoft Academic Search

    Tibor Bosse; Mark Hoogendoorn; Jan Treur

    2006-01-01

    How to coordinate the processes in a complex component-based software system is a nontrivial issue. Many different coordination approaches exist, each with its own specific advantages and drawbacks. To support their mutual comparison, this paper proposes a formal methodology to automatically evaluate the performance of coordination approaches. This methodology comprises (1) creation of simulation models of coordination approaches, (2) execution

  1. O`ahu Grid Study: Validation of Grid Models

    E-print Network

    O`ahu Grid Study: Validation of Grid Models Prepared for the U.S. Department of Energy Office............................................................................................................. 1 2 Model Validation .................................................................................................... 1 2.1 Production Cost Modeling (GE MAPSTM Analysis) ......................................... 2 2

  2. Social Informatics Data Grid

    Microsoft Academic Search

    Bennett Bertenthal; Robert Grossman; David Hanley; Mark Hereld; Sarah Kenny; Gina-Anne Levow; Michael E. Papka; Stephen W. Porges; Kavithaa Rajavenkateshwaran; Rick Stevens; Thomas D. Uram; Wenjun Wu

    The Social Informatics Data Grid is a new infrastructure designed to transform how social and behavioral scientists collect and annotate data, collaborate and share data, and analyze and mine large data repositories. An important goal of the project is to be compatible with existing databases and tools that support the sharing, storage and retrieval of archival data sets. It is

  3. APEC Smart Grid Initiative

    SciTech Connect

    Bloyd, Cary N.

    2012-03-01

    This brief paper describes the activities of the Asia Pacific Economic Cooperation (APEC) Smart Grid Initiative (ASGI) which is being led by the U.S. and developed by the APEC Energy Working Group. In the paper, I describe the origin of the initiative and briefly mention the four major elements of the initiative along with existing APEC projects which support it.

  4. Grid of the future

    Microsoft Academic Search

    Ali Ipakchi; Farrokh Albuyeh

    2009-01-01

    Many believe the electric power system is undergoing a profound change driven by a number of needs. There's the need for environmental compliance and energy conservation. We need better grid reliability while dealing with an aging infrastructure. And we need improved operational effi ciencies and customer service. The changes that are happening are particularly signifi cant for the electricity distribution

  5. Piloting the smart grid

    SciTech Connect

    Faruqui, Ahmad; Hledik, Ryan; Sergici, Sanem

    2009-08-15

    To address the likely impact of the smart grid on customers, utilities, and society as a whole, it may be necessary to conduct a pilot. When should a pilot be conducted and how should it be conducted? What validity criteria should the pilot satisfy? Here are issues to consider. (author)

  6. Unlocking the smart grid

    SciTech Connect

    Rokach, Joshua Z.

    2010-10-15

    The country has progressed in a relatively short time from rotary dial phones to computers, cell phones, and iPads. With proper planning and orderly policy implementation, the same will happen with the Smart Grid. Here are some suggestions on how to proceed. (author)

  7. Educating the Smart Grid

    Microsoft Academic Search

    J. S. Katz

    2008-01-01

    The smart grid is entering the era of practical pilot projects and readiness to scale. This has been the result of a movement in technology, regulation, and a learning process for all involved. This paper discusses several areas of experience with the \\

  8. Optical coordinate transformations.

    PubMed

    Davidson, N; Friesem, A A; Hasman, E

    1992-03-10

    A novel technique for designing holographic optical elements that can perform general types of coordinate transformation is presented. The design is based on analytic ray-tracing techniques for finding the grating vector of the element, from which the holographic grating function is obtained as a solution of a Poissonlike equation. The grating function can be formed either as a computer-generated or as a computer-originated hologram. The design and realization procedure are illustrated for a specific holographic element that performs a logarithmic coordinate transformation on two-dimensional patterns. PMID:20720723

  9. Coordinate Standard Measurement Development

    SciTech Connect

    Hanshaw, R.A.

    2000-02-18

    A Shelton Precision Interferometer Base, which is used for calibration of coordinate standards, was improved through hardware replacement, software geometry error correction, and reduction of vibration effects. Substantial increases in resolution and reliability, as well as reduction in sampling time, were achieved through hardware replacement; vibration effects were reduced substantially through modification of the machine component dampening and software routines; and the majority of the machine's geometry error was corrected through software geometry error correction. Because of these modifications, the uncertainty of coordinate standards calibrated on this device has been reduced dramatically.

  10. Journal of Grid Computing From Grids to Cloud Federations

    E-print Network

    Krintz, Chandra

    1 23 Journal of Grid Computing From Grids to Cloud Federations ISSN 1570-7873 Volume 11 Number 1 J Grid Computing (2013) 11:63-81 DOI 10.1007/s10723-012-9238-z Cloud Platform Datastore Support Navraj Computing (2013) 11:63­81 DOI 10.1007/s10723-012-9238-z Cloud Platform Datastore Support Navraj Chohan

  11. The GridSite Web\\/Grid security system

    Microsoft Academic Search

    Andrew Mcnab

    2005-01-01

    SUMMARY This paper describes the architecture of the GridSite system, which adds support for several Grid security protocols to the Apache Web server platform. These include the Globus GSI authentication system, Grid Access Control Language (GACL) access policy files, and Distinguished Name (DN) List and Virtual Organization Membership Service (VOMS) group memberships. Particular emphasis is placed on how the architecture

  12. Evaluating the Information Power Grid Using the NAS Grid Benchmarks

    Microsoft Academic Search

    Rob F. Van Der Wijngaart; Michael A. Frumkin

    2004-01-01

    The NAS Grid Benchmarks (NGB) are a collection of synthetic distributed applications designed to rate the per- formance and functionality of computational grids. We compare several implementations of the NGB to deter- mine programmability and efficiency of NASA's Informa- tion Power Grid (IPG), whose services are mostly based on the Globus Toolkit. We report on the overheads involved in porting

  13. FUTURE POWER GRID INITIATIVE GridOPTICSTM Power Networking,

    E-print Network

    FUTURE POWER GRID INITIATIVE GridOPTICSTM Power Networking, Equipment, and Technology (powerNET) Testbed OBJECTIVE A lot of interest in research, improvements, and testing surrounds the power grid to these activities. Specifically, » power system equipment is expensive and has a high knowledge barrier

  14. Stability of elastic grid shells

    E-print Network

    Mesnil, Romain, M. Eng. Massachusetts Institute of Technology

    2013-01-01

    The elastic grid shell is a solution that combines double curvature and ease of mounting. This structural system, based on the deformation of an initially at grid without shear stiffness was invented more than fifty years ...

  15. Standards for the Smart Grid

    Microsoft Academic Search

    R. DeBlasio; C. Tom

    2008-01-01

    To get from today's electricity grid to tomorrow's smart grid with interconnection and full two way communications connection to distributed energy sources such as wind, solar, and plug-in electric vehicles requires an interoperability framework of protocols and standards.

  16. Learning the Coordinate Gradients

    Microsoft Academic Search

    Yiming Ying; Qiang Wu; Colin Campbell

    In this paper we study the problem of learning the gradient function with application to variable selection and determining variable covariation. Firstly, we pro- pose a novel unifying framework for coordinate gradient learning from the perspective of multi-task learning. Various variable selection algorithms can be regarded as spe- cial instances of this framework. Secondly, we formulate the dual problems of

  17. Future Coordinated Universal Time

    Microsoft Academic Search

    Dennis D. McCarthy

    2000-01-01

    Coordinated Universal Time (UTC), created by adjusting International Atomic Time (TAI) by the appropriate number of leap seconds, is the uniform time scale that is the basis of most civil timekeeping in the world. The concept of a leap second was introduced to ensure that UTC would not differ by more than 0.9 seconds from UT1, the time determined by

  18. Coordination and Policy Traps

    Microsoft Academic Search

    George-Marios Angeletos; Christian Hellwig; Alessandro Pavan

    2003-01-01

    This paper examines the ability of a policy maker to control equilibrium outcomes in an environment where market participants play a coordination game with information heterogeneity. We consider defense policies against speculative currency attacks in a model where speculators observe the fundamentals with idiosyncratic noise. The policy maker is willing to take a costly policy action only for moderate fundamentals.

  19. Evolution of Dynamic Coordination

    E-print Network

    Jarvis, Erich D.

    of neurons, neural circuits, and neural computations across the animal kingdom; (b) brain organization­behavior relationships across animal taxa; and (c) the need for broadly comparative studies of the relationship of neural structures, neural functions, and behavioral coordination. Below we present an overview of neural machinery

  20. Coordination of Hand Shape

    PubMed Central

    Pesyna, Colin; Pundi, Krishna; Flanders, Martha

    2011-01-01

    The neural control of hand movement involves coordination of the sensory, motor and memory systems. Recent studies have documented the motor coordinates for hand shape, but less is known about the corresponding patterns of somatosensory activity. To initiate this line of investigation, the present study characterized the sense of hand shape by evaluating the influence of differences in the amount of grasping or twisting force, and differences in forearm orientation. Human subjects were asked to use the left hand to report the perceived shape of the right hand. In Experiment 1, six commonly grasped items were arranged on the table in front of the subject: bottle, doorknob, egg, notebook, carton, pan. With eyes closed, subjects used the right hand to lightly touch, forcefully support or imagine holding each object, while 15 joint angles were measured in each hand with a pair of wired gloves. The forces introduced by supporting or twisting did not influence the perceptual report of hand shape, but for most objects, the report was distorted in a consistent manner by differences in forearm orientation. Subjects appeared to adjust the intrinsic joint angles of the left hand, as well as the left wrist posture, so as to maintain the imagined object in its proper spatial orientation. In a second experiment, this result was largely replicated with unfamiliar objects. Thus somatosensory and motor information appear to be coordinated in an object-based, spatial coordinate system, sensitive to orientation relative to gravitational forces, but invariant to grasp forcefulness. PMID:21389230

  1. My Coordinates Nora Noffke

    E-print Network

    Noffke, Nora

    My Coordinates Nora Noffke MS, PhD Associate Professor Old Dominion University Ocean, Earth and microbial mats in sandy marine settings ­ today and through Earth history; Interactions of benthic realm; Earth's earliest environments; Ichnology Background I grew up in southern Germany, where I

  2. Dynamic Coordinated Email Visualization

    Microsoft Academic Search

    Simone Frau; Jonathan C. Roberts; Nadia Boukhelifa

    2005-01-01

    Many computer users receive hundreds (if not thousands) of emails per week; users often keep these emails and have many years of personal emails archived: users use their stored emails to manage appointments, to-do lists, and store useful information. In this paper we present an interactive email visualization tool (Mailview) that utilizes filter and coordination techniques to explore this archived

  3. Transonic Computation Using Euler Equations in Stream Function Coordinate System.

    NASA Astrophysics Data System (ADS)

    An, Chang-Fa.

    1992-01-01

    In this dissertation, a new approach has been developed to calculate the two dimensional steady transonic flow past airfoils using the Euler equations in a stream function coordinate system. Due to the importance of the transonic flow phenomenon in aeronautical practice, transonic flow computation has been an upsurging topic of the past two decades. Most existing transonic computation codes require the use of a grid generator to determine a suitable distribution of grid points. Although simple in concept, the grid generation takes a significant proportion of the CPU time and storage requirements. However, this time -consuming step can be completely avoided by introducing the von Mises transformation and the corresponding stream function coordinate system because this particular transformation combines the flow physics and flow geometry and produces a formulation in streamwise and body-fitting coordinates, without performing any conventional grid generation. In the present work, a set of the Euler equivalent equations in stream function coordinates is formulated. It consists of three equations with three unknowns. One unknown is a geometric variable, the streamline ordinate y, and the other two are physical quantities, density rho and vorticity omega. For irrotational fluid flow, the Euler formulation is simplified to the full potential formulation in which only two unknowns are solved--y and R, the generalized density. To solve these equations, several numerical techniques are applied: type-dependent differencing, shock point operator, marching from a non-characteristic boundary and successive line overrelaxation, etc. Particular attention has been paid to the supercritical case where a careful treatment of the shock is essential. It is shown that the shock point operator is crucial to accurately capture shock waves. The computed results for both analysis and design problems show good agreement with existing experimental data. The limitations of the approach and further investigations have been discussed.

  4. Spectral methods on arbitrary grids

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Gottlieb, David

    1995-01-01

    Stable and spectrally accurate numerical methods are constructed on arbitrary grids for partial differential equations. These new methods are equivalent to conventional spectral methods but do not rely on specific grid distributions. Specifically, we show how to implement Legendre Galerkin, Legendre collocation, and Laguerre Galerkin methodology on arbitrary grids.

  5. Smart Grid - a reliability perspective

    Microsoft Academic Search

    Khosrow Moslehi; Ranjit Kumar

    2010-01-01

    Increasing complexity of power grids, growing demand, and requirement for greater grid reliability, security and efficiency as well as environmental and energy sustainability concerns continue to highlight the need for a quantum leap in harnessing communication and information technologies. This leap toward a ¿smarter¿ grid is now widely referred to as \\

  6. Evolution of Data Grid Concepts

    Microsoft Academic Search

    Reagan W. Moore

    The goal of the Global Grid Forum is to develop a common set of services for access to distributed resources. The goal of the digital library and persistent archive communities is to organize, publish, and preserve digital entities. A Data Grid is the software infrastructure that maps from access mechanisms provided by grids to management functions provided by digital libraries.

  7. InterGrid: Peering Architecture and Policies for Internetworking Disparate Grids

    E-print Network

    Buyya, Rajkumar

    will impede realisation of full potential of the Grid computing paradigm. This InterGrid project aims. 1: InterGrid-based Integrated Human Physiome Environment. #12;InterGrid: Peering Architecture and Policies for Internetworking Disparate Grids Staff: Rajkumar

  8. Cloud Computing for the Grid: GridControl: A Software Platform to Support the Smart Grid

    SciTech Connect

    None

    2012-02-08

    GENI Project: Cornell University is creating a new software platform for grid operators called GridControl that will utilize cloud computing to more efficiently control the grid. In a cloud computing system, there are minimal hardware and software demands on users. The user can tap into a network of computers that is housed elsewhere (the cloud) and the network runs computer applications for the user. The user only needs interface software to access all of the cloud’s data resources, which can be as simple as a web browser. Cloud computing can reduce costs, facilitate innovation through sharing, empower users, and improve the overall reliability of a dispersed system. Cornell’s GridControl will focus on 4 elements: delivering the state of the grid to users quickly and reliably; building networked, scalable grid-control software; tailoring services to emerging smart grid uses; and simulating smart grid behavior under various conditions.

  9. A global Eta model on quasi-uniform grids

    Microsoft Academic Search

    Hai Zhang; Miodrag Rancic

    2007-01-01

    Summary Application of the quasi-uniform grids in global models of the atmosphere is an attempt to increase the computational efficiency by a more cost effective exploitation of the computing infrastructure. This paper describes the development of a global version of NCEP's regional, step-coordinate, Eta model on two quasi-uniform girds: cubic and octagonal. The governing equations are expressed in a general

  10. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  11. Cyber Security & Smart Grid 

    E-print Network

    Shapiro, J.

    2011-01-01

    -sponsored or terrorist infiltration and potential attack," said Jim Woolsey, former head of the Central Intelligence Agency (CIA). ?The real answer is new technology, active cyber defense, and distributed generation." ESL-KT-11-11-23 CATEE 2011, Dallas, Texas, Nov... of standards and interoperability ESL-KT-11-11-23 CATEE 2011, Dallas, Texas, Nov. 7 ? 9, 2011 Cyber Vulnerabilities In The Legacy Power Grid ? SCADA Security ? Supervisory Control and Data Acquisition (SCADA) systems are used extensively to control...

  12. Adaptive grid optical tomography

    Microsoft Academic Search

    Ivo Ihrke; Marcus A. Magnor

    2006-01-01

    Image-based modeling of semi-transparent, dynamic phenomena is a challenging task. We present an optical tomogra- phy method that uses an adaptive grid for the reconstruction of a three-dimensional density function from its projections. The proposed method is applied to reconstruct thin smoke and flames volumetrically from synchronized multi-video recordings. Our adaptive reconstruction algorithm computes a time-varying volumetric model, that enables

  13. Systematic Construction of Exact 2-D MHD Equilibria with Steady, Compressible Flow in Cartesian Geometry and Uniform Gravity

    E-print Network

    Gordon Petrie; Nektarios Vlahakis; Kanaris Tsinganos

    2001-11-28

    We present a systematic method for constructing two-dimensional magnetohydrodynamic equilibria with compressible flow in Cartesian geometry. This systematic method has already been developed in spherical geometry and applied in modelling solar and stellar winds and outflows (Vlahakis & Tsinganos,1998) but is derived here in Cartesian geometry in the context of the solar atmosphere for the first time. Using the method we find several new classes of solutions, some of which generalise known solutions, including the Kippenhahn & Schl\\"uter (1957) and Hood & Anzer (1990) solar prominence models and the Tsinganos, Surlantzis & Priest (1993) coronal loop model with flow, and some of which are completely new. Having developed the method in full and summarised the several classes of solutions, we explore in a some detail one of the classes to illustrate the general construction method. From one of the new classes of solutions we calculate two loop-like solutions, one of which is the first exact two-dimensional magnetohydrodynamic equilibrium with trans-Alfv\\'enic flow.

  14. Wireless Communications in Smart Grid

    NASA Astrophysics Data System (ADS)

    Bojkovic, Zoran; Bakmaz, Bojan

    Communication networks play a crucial role in smart grid, as the intelligence of this complex system is built based on information exchange across the power grid. Wireless communications and networking are among the most economical ways to build the essential part of the scalable communication infrastructure for smart grid. In particular, wireless networks will be deployed widely in the smart grid for automatic meter reading, remote system and customer site monitoring, as well as equipment fault diagnosing. With an increasing interest from both the academic and industrial communities, this chapter systematically investigates recent advances in wireless communication technology for the smart grid.

  15. RESEARCH COORDINATOR Job Title: Research Coordinator FLSA Status: Exempt

    E-print Network

    Massachusetts at Amherst, University of

    including the following: Coordinate clinical trial recruitment and enrollment of research participants range of clinical intervention, prevention, assessment, and data monitoring products. The Research Coordinator (RC) provides support to the Principal Investigator (and other clinical research team members

  16. A boundary conforming structured grid for global ocean circulation studies

    NASA Astrophysics Data System (ADS)

    Russell, William S.; Eiseman, Peter R.

    1998-10-01

    A boundary conforming two-dimensional structured grid for the irregular domain of the world's ocean is generated numerically using differential equation techniques. It is calculated using block structured methods which allow the inclusion of all major bodies of water including seas and basins, and which preserve slope continuity of the co-ordinate lines across the global domain. The block structure is coupled with an innovative blown-up cube model of the Earth which permits all areas of the global ocean to be modeled with the same resolution, eliminating problems associated with polar singularities. The grid is generated on the curved surface of the Earth (rather than the longitude-latitude plane) by employing the Beltrami operator instead of the standard Laplacian operator. Application of the grid to a steady state heat conduction problem shows the relative computational accuracy and the potential to resolve the complex, smaller scale oceanographic phenomena of great importance to global circulation studies.

  17. Solar System Data Access and Analysis with AstroGrid

    NASA Astrophysics Data System (ADS)

    Dalla, S.; Richards, A. M. S.; Gonzalez-Solares, E.; Walton, N. A.; Tedds, J. A.

    2007-10-01

    AstroGrid is the UK's contribution to a global Virtual Observatory (VO). This paper emphasizes the Solar System aspects of the 2006.3 AstroGrid release. The HelioScope service is presented, providing access to solar image data from the Virtual Solar Observatory, and to time series data from a variety of heliospheric and magnetospheric datasets part of the NASA Coordinated Data Analysis Workshops (CDAW) archive. Results from Helioscope can be streamed to visualization tools via PLASTIC. The AstroGrid Solar Movie Maker service allows the automatic generation of movies of solar images for visualization of flares, filament eruptions and coronal mass ejections. Data retrieval for specified events and cross matching based on time will be emphasized as essential for future Solar System VO developments.

  18. TRMM Gridded Text Products

    NASA Technical Reports Server (NTRS)

    Stocker, Erich Franz

    2007-01-01

    NASA's Tropical Rainfall Measuring Mission (TRMM) has many products that contain instantaneous or gridded rain rates often among many other parameters. However, these products because of their completeness can often seem intimidating to users just desiring surface rain rates. For example one of the gridded monthly products contains well over 200 parameters. It is clear that if only rain rates are desired, this many parameters might prove intimidating. In addition, for many good reasons these products are archived and currently distributed in HDF format. This also can be an inhibiting factor in using TRMM rain rates. To provide a simple format and isolate just the rain rates from the many other parameters, the TRMM product created a series of gridded products in ASCII text format. This paper describes the various text rain rate products produced. It provides detailed information about parameters and how they are calculated. It also gives detailed format information. These products are used in a number of applications with the TRMM processing system. The products are produced from the swath instantaneous rain rates and contain information from the three major TRMM instruments: radar, radiometer, and combined. They are simple to use, human readable, and small for downloading.

  19. Progress in Grid Generation: From Chimera to DRAGON Grids

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Kao, Kai-Hsiung

    1994-01-01

    Hybrid grids, composed of structured and unstructured grids, combines the best features of both. The chimera method is a major stepstone toward a hybrid grid from which the present approach is evolved. The chimera grid composes a set of overlapped structured grids which are independently generated and body-fitted, yielding a high quality grid readily accessible for efficient solution schemes. The chimera method has been shown to be efficient to generate a grid about complex geometries and has been demonstrated to deliver accurate aerodynamic prediction of complex flows. While its geometrical flexibility is attractive, interpolation of data in the overlapped regions - which in today's practice in 3D is done in a nonconservative fashion, is not. In the present paper we propose a hybrid grid scheme that maximizes the advantages of the chimera scheme and adapts the strengths of the unstructured grid while at the same time keeps its weaknesses minimal. Like the chimera method, we first divide up the physical domain by a set of structured body-fitted grids which are separately generated and overlaid throughout a complex configuration. To eliminate any pure data manipulation which does not necessarily follow governing equations, we use non-structured grids only to directly replace the region of the arbitrarily overlapped grids. This new adaptation to the chimera thinking is coined the DRAGON grid. The nonstructured grid region sandwiched between the structured grids is limited in size, resulting in only a small increase in memory and computational effort. The DRAGON method has three important advantages: (1) preserving strengths of the chimera grid; (2) eliminating difficulties sometimes encountered in the chimera scheme, such as the orphan points and bad quality of interpolation stencils; and (3) making grid communication in a fully conservative and consistent manner insofar as the governing equations are concerned. To demonstrate its use, the governing equations are discretized using the newly proposed flux scheme, AUSM+, which will be briefly described herein. Numerical tests on representative 2D inviscid flows are given for demonstration. Finally, extension to 3D is underway, only paced by the availability of the 3D unstructured grid generator.

  20. The Unit Coordinator Handbook About the Unit Coordinator Handbook

    E-print Network

    1 The Unit Coordinator Handbook About the Unit Coordinator Handbook This Handbook will assist you raised in this Handbook can be obtained from: · Curtin's Teaching and Learning Handbook · the Dean.curtin.edu.au/professional_development/seminars/foundations/about.cfm #12;2 Contents The Unit Coordinator Handbook

  1. iGridPortal and biological problems

    Microsoft Academic Search

    Hoang Le Minh; Vo Duc Cam Hai; Nguyen Thi Thanh Nhan; Tran Linh Thuoc; Do Anh Tuan; Vo Cam Quy

    2004-01-01

    Grid provides us a lot of computing services and resources. However, grid service interfaces are good for programmers, but not for users. Portal is a suitable framework to integrate grid resources and help users communicate easily with the grid infrastructure via Web browsers. Grid technologies have an impact on many areas of sciences, including biology. Grid computing has helped biologist

  2. Stability assessment of a multi-port power electronic interface for hybrid micro-grid applications

    NASA Astrophysics Data System (ADS)

    Shamsi, Pourya

    Migration to an industrial society increases the demand for electrical energy. Meanwhile, social causes for preserving the environment and reducing pollutions seek cleaner forms of energy sources. Therefore, there has been a growth in distributed generation from renewable sources in the past decade. Existing regulations and power system coordination does not allow for massive integration of distributed generation throughout the grid. Moreover, the current infrastructures are not designed for interfacing distributed and deregulated generation. In order to remedy this problem, a hybrid micro-grid based on nano-grids is introduced. This system consists of a reliable micro-grid structure that provides a smooth transition from the current distribution networks to smart micro-grid systems. Multi-port power electronic interfaces are introduced to manage the local generation, storage, and consumption. Afterwards, a model for this micro-grid is derived. Using this model, the stability of the system under a variety of source and load induced disturbances is studied. Moreover, pole-zero study of the micro-grid is performed under various loading conditions. An experimental setup of this micro-grid is developed, and the validity of the model in emulating the dynamic behavior of the system is verified. This study provides a theory for a novel hybrid micro-grid as well as models for stability assessment of the proposed micro-grid.

  3. Enhancing control of grid distribution in algebraic grid generation

    NASA Technical Reports Server (NTRS)

    Steinthorsson, E.; Shih, T. I.-P.; Roelke, R. J.

    1992-01-01

    Three techniques are presented to enhance the control of grid-point distribution for a class of algebraic grid generation methods known as the two-, four- and six-boundary methods. First, multidimensional stretching functions are presented, and a technique is devised to construct them based on the desired distribution of grid points along certain boundaries. Second, a normalization procedure is proposed which allows more effective control over orthogonality of grid lines at boundaries and curvature of grid lines near boundaries. And third, interpolating functions based on tension splines are introduced to control curvature of grid lines in the interior of the spatial domain. In addition to these three techniques, consistency conditions are derived which must be satisfied by all user-specified data employed in the grid generation process to control grid-point distribution. The usefulness of the techniques developed in this study was demonstrated by using them in conjunction with the two- and four-boundary methods to generate several grid systems, including a three-dimensional grid system in the coolant passage of a radial turbine blade with serpentine channels and pin fins.

  4. General Coordinates Game

    NSDL National Science Digital Library

    2005-01-01

    This interactive Java applet allows users to plot a "house" on a -10 by 10 coordinate plane. A "view" mode allows users to enter an ordered pair and move the house to that location. The "guess" mode randomly plots the house on the plane and the user must enter the ordered pair for its location. An optional scoring feature allows users to keep track of the number correct.

  5. A second order accurate projection method for the incompressible Navier Stokes equations on non-graded adaptive grids

    NASA Astrophysics Data System (ADS)

    Min, Chohong; Gibou, Frédéric

    2006-12-01

    We present an unconditionally stable second order accurate projection method for the incompressible Navier-Stokes equations on non-graded adaptive Cartesian grids. We employ quadtree and octree data structures as an efficient means to represent the grid. We use the supra-convergent Poisson solver of [C.-H. Min, F. Gibou, H. Ceniceros, A supra-convergent finite difference scheme for the variable coefficient Poisson equation on fully adaptive grids, CAM report 05-29, J. Comput. Phys. (in press)], a second order accurate semi-Lagrangian method to update the momentum equation, an unconditionally stable backward difference scheme to treat the diffusion term and a new method that guarantees the stability of the projection step on highly non-graded grids. We sample all the variables at the grid nodes, producing a scheme that is straightforward to implement. We propose two and three-dimensional examples to demonstrate second order accuracy for the velocity field and the divergence free condition in the L1 and L? norms.

  6. Hipparchus' coordinate system

    NASA Astrophysics Data System (ADS)

    Duke, Dennis W.

    2002-07-01

    In his "Histoire de l'Astronomie Ancienne" Delambre concludes unequivocally that Hipparchus knew and used a definite system of celestial spherical coordinates, namely the right ascension and declination system that we use today. The basis of Delambre's conclusion was disarmingly simple: he pointed out that in the "Commentary to Aratus" Hipparchus actually quotes the positions of numerous stars directly in right ascension and declination (or more often its complement, polar distance). Nearly two centuries later, in his "A History of Ancient Mathematical Astronomy", Neugebauer not only completely ignores Delambre's conclusion on this issue, but goes further to propose his own, as we shall see quite fanciful, theory that begins "From the Commentary to Aratus, it is quite obvious that at Hipparchus' time a definite system of spherical coordinates for stellar positions did not yet exist." and concludes "...nowhere in Greek astronomy before the catalogue of stars in the Almagest is it attested that orthogonal spherical coordinates are used to determine stellar positions." Today it is clear that Neugebauer's theory is conventionally accepted. It is the purpose of this paper to offer fresh arguments that Delambre was correct.

  7. NASA Surface-Modeling and Grid-Generation (SM/GG) activities

    NASA Technical Reports Server (NTRS)

    Choo, Yung K.

    1992-01-01

    A NASA Steering Committee was formed to carry out the recommendations from the NASA Workshop on Future Directions in Surface Modeling and Grid Generation. Its function is to communicate and coordinate within NASA the acquisition and distribution of geometry/grid generation software/data, establish geometry data exchange standards, and interface with other government, university, and industry efforts. Two speakers present the committee's activities in viewgraph format.

  8. International Space Exploration Coordination Group

    E-print Network

    International Space Exploration Coordination Group The Global Exploration Roadmap September 2011, and stimulating technical and commercial innovation. As more nations undertake space exploration activities agencies participating in the International Space Exploration Coordination Group (ISECG) are developing

  9. International Space Exploration Coordination Group

    E-print Network

    International Space Exploration Coordination Group The Global Exploration Roadmap September 2011 participating in the International Space Exploration Coordination Group (ISECG) are developing the Global. Agencies agree that human space exploration will be most successful as an international endeavor because

  10. GIS Lab 3 - Coordinate Systems

    NSDL National Science Digital Library

    Margaret McMillan

    Margaret E. (Beth) McMillan, University of Arkansas at Little Rock Summary I use this lab to reinforce the basic concepts of coordinate systems and to introduce the coordinate systems that are commonly used for ...

  11. LOCATION AWARENESS: EXPLORING SOCIAL COORDINATION

    E-print Network

    Toronto, University of

    LOCATION AWARENESS: EXPLORING SOCIAL COORDINATION by David Dearman Submitted in partial fulfillment 2006 © Copyright by David Dearman, 2006 #12;ii DALHOUSIE UNIVERSITY FACULTY OF COMPUTER SCIENCE a thesis entitled "LOCATION AWARENESS: EXPLORING SOCIAL COORDINATION" by David Dearman in partial

  12. Coordination in Software Agent Systems

    Microsoft Academic Search

    Hyacinth Nwana; Lyndon Lee; Nick Jennings

    1996-01-01

    this paper is to examine the crucial area of co-ordination in multi-agent systems. It does not attempt toprovide a comprehensive overview of the co-ordination literature; rather, it highlights the necessity for co-ordination inagent systems and overviews briefly various co-ordination techniques. It critiques these techniques and presents someconclusions and challenges drawn from this literature.1. IntroductionThe scope of this paper is limited

  13. Provably optimal parallel transport sweeps on regular grids

    SciTech Connect

    Adams, M. P.; Adams, M. L.; Hawkins, W. D. [Dept. of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843-3133 (United States); Smith, T.; Rauchwerger, L.; Amato, N. M. [Dept. of Computer Science and Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843-3133 (United States); Bailey, T. S.; Falgout, R. D. [Lawrence Livermore National Laboratory (United States)

    2013-07-01

    We have found provably optimal algorithms for full-domain discrete-ordinate transport sweeps on regular grids in 3D Cartesian geometry. We describe these algorithms and sketch a 'proof that they always execute the full eight-octant sweep in the minimum possible number of stages for a given P{sub x} x P{sub y} x P{sub z} partitioning. Computational results demonstrate that our optimal scheduling algorithms execute sweeps in the minimum possible stage count. Observed parallel efficiencies agree well with our performance model. An older version of our PDT transport code achieves almost 80% parallel efficiency on 131,072 cores, on a weak-scaling problem with only one energy group, 80 directions, and 4096 cells/core. A newer version is less efficient at present-we are still improving its implementation - but achieves almost 60% parallel efficiency on 393,216 cores. These results conclusively demonstrate that sweeps can perform with high efficiency on core counts approaching 10{sup 6}. (authors)

  14. Student Leadership Program Coordinator Application

    E-print Network

    Sheridan, Jennifer

    Student Leadership Program Coordinator Application Summer 2012 ­ Spring 2013 Please direct all (Preferable Start Date 7/1) ____ Leadership Events and Training Program Coordinator (Preferable Start Date 7 leadership skills do you hope to strengthen from a Student Leadership Program Coordinator position? 2

  15. Incremental coordination in collaborative networks

    Microsoft Academic Search

    Alexander Fridman; Olga Fridman

    2010-01-01

    We developed an incremental coordination technique for collaborative networks based on necessary and sufficient coordinability conditions that we proposed earlier for locally controlled hierarchies of dynamic systems. Efficiency of the technique is illustrated by mathematical modelling of a two-level control system for a network of linear objects. The modelling has proved that usage of local control and coordination widens the

  16. GridFMO - Quantum chemistry of proteins on the grid

    Microsoft Academic Search

    Tsutomu Ikegamial; Jun Maki; Toshiya Takami; Yoshio Tanaka; Mitsuo Yokokawa; Satoshi Sekiguchi; Mutsumi Aoyagi

    2007-01-01

    A GridFMO application was developed by recoining the fragment molecular orbital (FMO) method of GAMESS with grid technology. With the GridFMO, quantum calculations of macro molecules become possible by using large amount of computational resources collected from many moderate-sized cluster computers. A new middleware suite was developed based on Ninf-G, whose fault tolerance and flexible resource management were found to

  17. GridWise: Transforming the Power Grid with Information Technology

    Microsoft Academic Search

    Robert G. Pratt; Eric M. Lightner

    2004-01-01

    GridWise is a vision for the future electric system shared by a new DOE initiative and an industry alliance. GridWise is built upon the fundamental premise that information technology will profoundly transform the plan¬ning and operation of the power grid, just at is has changed business, education, and entertainment. The electric power system has served us remarkably well for over

  18. Evaluating the Information Power Grid using the NAS Grid Benchmarks

    NASA Technical Reports Server (NTRS)

    VanderWijngaartm Rob F.; Frumkin, Michael A.

    2004-01-01

    The NAS Grid Benchmarks (NGB) are a collection of synthetic distributed applications designed to rate the performance and functionality of computational grids. We compare several implementations of the NGB to determine programmability and efficiency of NASA's Information Power Grid (IPG), whose services are mostly based on the Globus Toolkit. We report on the overheads involved in porting existing NGB reference implementations to the IPG. No changes were made to the component tasks of the NGB can still be improved.

  19. Data Management in the GridRPC GridRPC Data Management API

    E-print Network

    Caniou, Yves

    Data Management in the GridRPC Issues Conclusion GridRPC Data Management API Implementations, Le Mahec, Nakada GridRPC DM API: Implem. and Interop. Issues (1/13) #12;Data Management in the GridRPC Issues Conclusion Goal GridRPC DM types: Reminder 1 Data Management in the GridRPC Goal GridRPC DM types

  20. Development of a Cartesian sinc DVR basis for single and double ionization

    NASA Astrophysics Data System (ADS)

    Jones, Jeremiah; Haxton, Dan

    2014-05-01

    In this investigation, we explore properties of a grid-based representation designed to calculate phenomena involving single and double (auto)ionization. The method employs a powerful representation of the two-electron operator within a basis of sinc functions. It consists of a tensor decomposition of the operator such that two-electron matrix elements may be computed in O(N2) operations, as opposed to the O(N4) calculations required for the usual Gaussian basis sets used in quantum chemistry. The basis and methods are tested with the hydrogen atom and H2+.Results indicate that, in addition to being more scalable, the technique is more accurate than variational method. Work supported by USDOE, OBES Chemical Sciences, Geosciences, and Biosciences Division.