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International Conference on Computer Graphics Theory and Applications, GRAPP 2012 and International Conference on Information visualization Theory and Applications, IVAPP 2012

作者： Narayan, Akshay Sreevalsan-Nair, Jaya Gaither, Kelly Hamann, Bernd International Institute of Information Technology - Bangalore 26/C Electronics City Hosur Road Bangalore 560100 India Texas Advanced Computing Center University of Texas at Austin 10100 Burnet Road Austin TX 78758 United States Institute for Data Analysis and Visualization Department of Computer Science University of California Davis One Shields Avenue Davis CA 95616 United States

ISBN: (纸本)9789898565020

Grid-based computational simulations often use hybrid unstructured grids consisting of various types of elements. Most commonly used elements are tetrahedral, pentahedral (namely, square pyramids and right triangular prisms) and hexahedral elements. Extracting isosurfaces of scalar fields defined on such hybrid unstructured grids is often done using indirect methods, such as, (a) subdividing all non-tetrahedral cells into tetrahedra and computing the triangulated isosurfaces using the marching tetrahedra algorithm, or (b) triangulating intersection points of edges of cells and computing the isosurface using a standard triangulation algorithm. Using the basic ideas underlying the well-established marching cubes and marching tetrahedra algorithms, which are applied to hexahedral and tetrahedral elements, respectively, we generate look-up tables for extracting isosurfaces directly from pentahedral elements. By using appropriate look-up tables, it is possible to process nearly all types of hybrid unstructured grids used in practical applications without the need for indirect methods. We construct look-up tables for square pyramidal and triangular prismatic cells with accurate topological considerations.

关键词： Table lookup

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Debugging lenses: a new class of transparent tools for user interface debugging 97

Debugging lenses: a new class of transparent tools for user ...

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Proceedings of the 10th annual ACM symposium on User interface software and technology

作者： Scott E. Hudson Roy Rodenstein Ian Smith Human Computer Interaction Institute Carnegie Mellon University 5000 Forbes Ave. Pittsburgh PA Graphics Visualization and Usability Center College of Computing Georgia Institute of Technology Atlanta GA

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Empirically evaluating the use of animations to teach algorithms

Empirically evaluating the use of animations to teach algori...

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IEEE Symposium on Visual Languages

作者： A.W. Lawrence A.M. Badre J.T. Stasko Department of Computer and Information Sciences Spelman College Atlanta GA USA Graphics Visualization and Usability Center Georgia Institute of Technology College of Computing Georgia Institute of Technology Atlanta GA USA

As algorithm animation systems become more widely available and easy to use, instructors will have the opportunity to utilize these systems to assist their teaching. Although algorithm animation systems have generated excitement and interest in both teachers and students, little empirical evidence exists to promote their use. This article describes a study involving the use of algorithm animations in classroom and laboratory settings. Results indicated that allowing students to create their own examples in a laboratory session led to higher accuracy on a post-test examination of understanding as compared to students who viewed prepared examples or no laboratory examples.< >

关键词： Animation Laboratories Education Educational institutions Control systems Humans Educational technology Graphics Data visualization Usability

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visualization and geographic information system integration: what are the needs and the requirements, if any? 94

Visualization and geographic information system integration:...

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IEEE Conference on visualization

作者： T.M. Rhyne W. Ivey L. Knapp P. Kochevar T. Mace Martin Marietta U. S. EPA Visualization Center SAS Institute Inc. IBM and University of Colorado USA DEC San Diego Supercomputing Center Scientific Computing Branch U.S. EPA

ISBN: (纸本)9780780325210

Addresses the needs and requirements of integrating visualization and geographic information system technologies. There are three levels of integration methods: rudimentary, operational and functional. The rudimentary approach uses the minimum amount of data sharing and exchange between these two technologies. The operational level attempts to provide consistency of the data while removing redundancies between the two technologies. The functional form attempts to provide transparent communication between these respective software environments. At this level, the user only needs to request information and the integrated system retrieves or generates the information depending upon the request. This paper examines the role and impact of these three levels of integration. Stepping further into the future, the paper also questions the long-term survival of these separate disciplines.< >

关键词： Geographic Information Systems Data visualization Displays Decision making Synthetic aperture sonar Supercomputers Graphics Image generation Protection Hardware

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Fast estimation of the vascular cooling in RFA based on numerical simulation

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Open Biomedical Engineering Journal 2010年第SPEC. ISSUE 1期4卷 16-26页

作者： Kröger, T. Pätz, T. Altrogge, I. Schenk, A. Lehmann, K.S. Frericks, B.B. Ritz, J.-P. Peitgen, H.-O. Preusser, T. Fraunhofer MEVIS Institute for Medical Image Computing Bremen Germany CeVis Center of Complex Systems and Visualization University of Bremen Germany Chirurgische Klinik I Charité - Campus Benjamin Franklin Berlin Germany Jacobs University Bremen Germany

We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach. © Kröger et al.

关键词： Cooling

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Abstract: Exploring Performance Data with Boxfish

Abstract: Exploring Performance Data with Boxfish

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High Performance computing, Networking, Storage and Analysis (SCC), SC Companion:

作者： Katherine E. Isaacs Aaditya G. Landge Todd Gamblin Peer-Timo Bremer Valerio Pascucci Bernd Hamann Institute for Data Analysis and Visualization Department of Computer Science University of California Davis CA USA Scientific Computing and Imaging Institute University of Utah Salt Lake UT USA Center for Applied Scientific Computing Lawrence Livermore National Laboratories Livermore CA USA

The growth in size and complexity of scaling applications and the systems on which they run pose challenges in analyzing and improving their overall performance. With metrics coming from thousands or millions of processes, visualization techniques are necessary to make sense of the increasing amount of data. To aid the process of exploration and understanding, we announce the initial release of Boxfish, an extensible tool for manipulating and visualizing data pertaining to application behavior. Combining and visually presenting data and knowledge from multiple domains, such as the application's communication patterns and the hardware's network configuration and routing policies, can yield the insight necessary to discover the underlying causes of observed behavior. Boxfish allows users to query, filter and project data across these domains to create interactive, linked visualizations.

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CFD computation of fan interaction noise

CFD computation of fan interaction noise

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ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007

作者： Grace, Sheryl M. Sondak, Douglas L. Dorney, Daniel J. Logue, Michaela Department of Aerospace and Mechanical Engineering Boston University 110 Cummington St. BostonMA02215 United States Scientific Computing and Visualization Boston University BostonMA02215 United States Fluid Dynamics Branch NASA Marshall Space Flight Center AL35812 United States Aerospace and Mechanical Engineering Department University of Notre Dame Notre DameIN45665 United States

ISBN: (纸本)0791843025

In this study, a 3-D, unsteady, Reynolds-averaged Navier- Stokes (RANS) CFD code coupled to an acoustic calculation is used to predict the contribution of the exit guide vanes to tonal fan noise downstream. The configuration investigated is that corresponding to the NASA Source Diagnostic Test (SDT) 22-in fan rig. One configuration from the SDT matrix is considered here: The approach condition, and outlet guide vane count designed for cut-off of the blade passage frequency. In this chosen configuration, there are 22 rotor blades and 54 stator blades. The stators are located 2.5 tip chords downstream of the rotor trailing edge. The RANS computations are used to obtain the spectra of the unsteady surface pressure on the exit guide vanes. The surface pressure at the blade passage frequency and its second harmonic are then integrated together with the Green's function for an annular duct to obtain the pressure at locations in the duct. Comparison of the computed sound power level at the exhaust plane with experiment show good agreement at the cut-on circumferential mode. The results from this investigation validate the use of the CFD code along with the acoustic model for downstream fan noise predictions. This validation enables future investigations such as the effect of duct variation on the exhaust tonal power level and the validity of using this method for predicting broadband noise levels. Copyright © 2007 by ASME.

关键词： Stators

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Von-neumann stability and singularity resolution in loop quantized schwarzschild black hole

arXiv

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arXiv 2017年

作者： Yonika, Alec Khanna, Gaurav Singh, Parampreet Department of Physics Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth North DartmouthMA02747 United States Department of Physics and Astronomy Center for Computation and Technology Louisiana State University Baton RougeLA70803 United States

Though loop quantization of several spacetimes has exhibited existence of a bounce via an explicit evolution of states using numerical simulations, the question about the way central singularity is resolved in the black hole interior has remained open. The quantum Hamiltonian constraint in loop quantization turns out to be a finite difference equation whose stability is important to understand to gain insights on the viability of the underlying quantization and resulting physical implications. We take first steps towards addressing these issues for a loop quantization of the Schwarzschild interior recently given by Corichi and Singh. Von-Neumann stability analysis is performed using separability of solutions as well as a full two dimensional quantum difference equation. This results in a stability condition for black holes which have a very large mass compared to the Planck mass. For black holes of smaller masses evidence of numerical instability is found. In addition, stability analysis for macroscopic black holes leads to a constraint on the choice of the allowed states in numerical evolution. States which are not sharply peaked in accordance with this constraint result in instabilities. With the caveat of using kinematical norm, sharply peaked Gaussian states are evolved using the quantum difference equation and singularity resolution is obtained. A bounce is found for one of the triad variables, but for the other triad variable singularity resolution amounts to a non-singular passage through the zero volume. States are found to be peaked at the classical trajectory for a long time before and after the singularity resolution, and retain their semi-classical character across the zero volume. Our main result is that quantum bounce occurs in loop quantized Schwarzschild interior at least for macroscopic black holes. Instability of small black holes which can be a result of using kinematical norm nevertheless signifies the need of further understanding of the viabili

关键词： Gravitation

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Impact of subdominant modes on the interpretation of gravitational-wave signals from heavy binary black hole systems

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Physical Review D 2020年第12期101卷 124054-124054页

作者： Feroz H. Shaik Jacob Lange Scott E. Field Richard O’Shaughnessy Vijay Varma Lawrence E. Kidder Harald P. Pfeiffer Daniel Wysocki Department of Physics Department of Mathematics and the Center for Scientific Computing & Visualization Research University of Massachusetts Dartmouth Dartmouth Massachusetts 02747 USA Center for Computational Relativity and Gravitation Rochester Institute of Technology Rochester New York 14623 USA Department of Mathematics and the Center for Scientific Computing & Visualization Research University of Massachusetts Dartmouth Dartmouth Massachusetts 02747 USA Theoretical Astrophysics California Institute of Technology Pasadena California 91125 USA Cornell Center for Astrophysics and Planetary Science Cornell University Ithaca New York 14853 USA Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1 14476 Potsdam Germany

Over the past year, a handful of new gravitational wave models have been developed to include multiple harmonic modes thereby enabling for the first time fully Bayesian inference studies including higher modes to be performed. Using one recently developed numerical relativity surrogate model, NRHybSur3dq8, we investigate the importance of higher modes on parameter inference of coalescing massive binary black holes. We focus on examples relevant to the current three-detector network of observatories, with a detector-frame mass set to 120 M⊙ and with signal amplitude values that are consistent with plausible candidates for the next few observing runs. We show that for such systems the higher mode content will be important for interpreting coalescing binary black holes, reducing systematic bias, and computing properties of the remnant object. Even for comparable-mass binaries and at low signal amplitude, the omission of higher modes can influence posterior probability distributions. We discuss the impact of our results on source population inference and self-consistency tests of general relativity. Our work can be used to better understand asymmetric binary black hole merger events, such as GW190412. Higher modes are critical for such systems, and their omission usually produces substantial parameter biases.

关键词： Gravitational waves

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Constructing Multiple Scene Graphs in Distributed Environment

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Computer Aided Drafting,Design and Manufacturing 2015年第1期25卷 16-21页

作者： XIA Rui WANG Guo-ping LI Sheng WANG Heng Shenzhen Key Lab for Cloud Computing Technology and Applications Shenzhen Graduate School of Peking University Graphics & Interaction Lab. School of Electronics Engineering and Computer SciencesPeking University Beijing Engineering Technology Research Center of Virtual Simulation and Visualization Peking University

Scene graph is a infrastructure of the virtual reality system to organize the virtual scene with abstraction, it can provide facility for the rendering engine and should be integrated effectively on demand into a real-time system, where a large quantities of scene objects and resources can be manipulated and managed with high flexibility and reliability. We present a new scheme of multiple scene graphs to accommodate the features of rendering engine and distributed systems. Based upon that, some other functions, e.g. block query, interactive editing, permission management, instance response, ＂redo＂ and ＂undo＂, are implemented to satisfy various requirements. At the same time, our design has compatibility to popular C/S architecture with good concurrent performance. Above all, it is convenient to be used for further development. The results of experiments including responding time demonstrate its good performance.

关键词： multiple scene graphs authority scene editing distributed systems

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