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arXiv 2023年

作者： Islam, Tousif Department of Physics University of Massachusetts DartmouthMA02747 United States Department of Mathematics University of Massachusetts DartmouthMA02747 United States Center for Scientific Computing and Visualization Research University of Massachusetts DartmouthMA02747 United States

We investigate the interplay between numerical relativity (NR) and point-particle black hole perturbation theory (ppBHPT) for quasi-circular non-spinning binary black holes in the intermediate mass ratio regime: 7 ≤ q ≤ 128 (where q := m1/m2 is the mass ratio of the binary with m1 and m2 being the mass of the primary and secondary black hole respectively). Initially, we conduct a comprehensive comparison between the dominant (,m) = (2,2) mode of the gravitational radiation obtained from state-of-the-art NR simulations and ppBHPT waveforms along with waveforms generated from recently developed NR-informed ppBHPT surrogate model, BHPTNRSur1dq1e4. This surrogate model employs a simple but non-trivial rescaling technique known as the α-β scaling to effectively match ppBHPT waveforms to NR in the comparable mass ratio regime. Subsequently, we analyze the amplitude and frequency differences between NR and ppBHPT waveforms to investigate the non-linearities, beyond adiabatic evolution, that are present during the merger stage of the binary evolution and propose fitting functions to describe these differences in terms of both the mass ratio and the symmetric mass ratio. Finally, we assess the performance of the α-β scaling technique in the intermediate mass ratio regime. Copyright © 2023, The Authors. All rights reserved.

关键词： Black holes

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Lorsch Abbey and the London Charter - An Information System for a World Heritage Site

Lorsch Abbey and the London Charter - An Information System ...

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International Conference on Virtual Systems and MultiMedia

作者： Joyce Wittur Susanne Kromker Heidelberg Graduate School of Mathematical and Computational Methods for the Sciences (HGS MathComp) Institute of European Art History (IEK) Heidelberg University Germany Visualization and Numerical Geometry Group (NGG) Interdisciplinary Center of Scientific Computing (IWR) Heidelberg University Heidelberg Germany

ISBN: (纸本)9781424448340

The Lorsch Abbey World Heritage Site is a good example for a detailed London Charter implementation guideline. The information system attempted here strives for a combination of architectural 3D-models based on physical remains with historical and recent source materials. It needs to be suited for sites with heterogeneous and sparse sources, which heavily rely on the interpretation and the possible combination of information. It shall also help to compare and re-evaluate older or differing interpretations of the site. Argumentation networks have been proven to be a useful tool in preparing data for this case study.

关键词： Information systems History Electronic mail visualization Multimedia systems Multimedia computing Art Computational geometry Information geometry Scientific computing

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Learner-centered system design: HCI Perspective for the future 95

Learner-centered system design: HCI Perspective for the futu...

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1st Conference on Designing Interactive Systems: Processes, Practices, Methods, and Techniques, DIS 1995

作者： Guzdial, Mark Kafai, Yasmin B. Carroll, John B. Fischer, Gerhard Schank, Roger Soloway, Elliot Shneiderman, Ben Graphics Visualization Usability Center Georgia Institute of Technology College of Computing AtlantaGA30332-0280 United States Graduate School of Education and Information Studies University of California Los AngelesCA90095-152 United States Virginia Polytechnic Institute United States University of Colorado at Boulder United States Institute for the Learning Sciences Northwestern University United States University of Michigan United States University of Maryland at College Park United States

ISBN: (纸本)0897916735

User-centered system design (Norman & Draper, 1986) taught the HCI community to address users and their needs, but the community has learned that the needs of users are not a constant. Learner-centered design draws attention to the changing needs of users (both students and professionals) as they gain expertise and how these changes need to be reflected in the interface. The panelists will help in defining how interface design must be tailored to support users as learners with case studies of their experiences in designing adaptive and adaptable interfaces for learners. © 1995 ACM.

关键词： Systems analysis

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Energetics of Kinetic Reconnection in a Three-Dimensional Null-Point Cluster

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Physical Review Letters 2013年第4期111卷 045002-045002页

作者： V. Olshevsky G. Lapenta S. Markidis Center for mathematical Plasma Astrophysics (CmPA) Department of Mathematics KU Leuven Celestijnenlaan 200B bus 2400 B-3001 Leuven Belgium Main Astronomical Observatory of NAS Akademika Zabolotnoho 27 03680 Kyiv Ukraine High Performance Computing and Visualization (HPCViz) KTH Royal Institute of Technology SE-100 44 Stockholm Sweden

We perform three-dimensional particle-in-cell simulations of magnetic reconnection with multiple magnetic null points. Magnetic field energy conversion into kinetic energy is about five times higher than in traditional Harris sheet configuration. More than 85% of initial magnetic field energy is transferred to particle energy during 25 reversed ion cyclofrequencies. Magnetic reconnection in the cluster of null points evolves in three phases. During the first phase, ion beams are excited, then give part of their energy back to the magnetic field in the second phase. In the third phase, magnetic reconnection occurs in many small patches around the current channels formed along the stripes of a low magnetic field. Magnetic reconnection in null points essentially presents three-dimensional features, with no two-dimensional symmetries or current sheets.

关键词： ION beams KINETIC energy MAGNETIC reconnection MAGNETIC field effects SYMMETRIES (Quantum mechanics)

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Multi-application inter-tile synchronization on ultra-high-resolution display walls 10

Multi-application inter-tile synchronization on ultra-high-r...

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2010 ACM SIGMM Conference on Multimedia Systems, MMSys'10

作者： Nam, Sungwon Deshpande, Sachin Vishwanath, Venkatram Jeong, Byungil Renambot, Luc Leigh, Jason Electronic Visualization Laboratory 842 W. Taylor St. Chicago IL 60607 United States Sharp Laboratories of America 5750 NW Pacific Rim Blvd. Camas WA 98607 United States Argonne National Laboratory 9700 S. Cass Ave. Argonne IL 60439 United States Texas Advanced Computing Center Bldg. 196 10100 Burnet Rd. Austin TX 78758 United States

ISBN: (纸本)9781605589145

Ultra-high-resolution tiled-display walls are typically driven by a cluster of computers. Each computer may drive one or more displays. Synchronization between the computers is necessary to ensure that animated imagery displayed on the wall appears seamless. Most tiled-display middleware systems are designed around the assumption that only a single application instance is running in the tiled display at a time. Therefore synchronization can be achieved with a simple solution such as a networked barrier. When a tiled display has to support multiple applications at the same time, however, the simple networked barrier approach does not scale. In this paper we propose and experimentally validate two synchronization algorithms to achieve low-latency, intertile synchronization for multiple applications with independently varying frame rates. The two-phase algorithm is more generally applicable to various highresolution tiled display systems. The one-phase algorithm provides superior results but requires support for the Network Time Protocol and is more CPU-intensive. Copyright 2010 ACM.

关键词： Cluster computing

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Multiple Grains in Nanocrystals: Effect of Initial Shape and Size on Transformed Structures Under Pressure

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Physical Review Letters 2004年第20期93卷 203401-203401页

作者： Sanjay Kodiyalam Rajiv K. Kalia Aiichiro Nakano Priya Vashishta Biological Computation and Visualization Center Department of Physics & Astronomy and Department of Computer Science Louisiana State University Baton Rouge LA 70803-4001 USA Collaboratory for Advanced Computing and Simulations Departments of Material Science & Engineering Physics & Astronomy Computer Science and Biomedical Engineering University of Southern California Los Angeles CA 90089-0242 USA

Pressure-induced structural transformations in spherical and faceted gallium arsenide nanocrystals of various shapes and sizes are investigated with a parallel molecular-dynamics approach. The results show that the pressure for zinc blende to rocksalt structural transformation depends on the nanocrystal size, and all nanocrystals undergo nonuniform deformation during the transformation. Spherical nanocrystals above a critical diameter ≥44 Å transform with grain boundaries. Faceted nanocrystals of comparable size have grain boundaries in 60% of the cases, whereas the other 40% are free of grain boundaries. The structure of transformed nanocrystals shows that domain orientation and strain relative to the initial zinc blende lattice are not equivalent. These observations may have implications in interpreting the experimental x-ray line shapes from transformed nanocrystals.

关键词： .ending undergo Grains grain boundaries rocksalt VOLUME NUMBER week structural transformation Transformed Structures nanocrystal size Spherical nanocrystals Faceted nanocrystals transformed nanocrystals strain relative zinc blende lattice

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Bayesian spatial binary regression for label fusion in structural neuroimaging

arXiv

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arXiv 2017年

作者： Brown, D. Andrew McMahan, Christopher S. Shinohara, Russell T. Linn, Kristin A. School Of Mathematical And Statistical Sciences Clemson University ClemsonSC29634 United States Penn Statistics In Imaging And Visualization Center Department Of Biostatistics Epidemiology And Informatics Center For Biomedical Image Computing And Analytics Department Of Radiology Perelman School Of Medicine University Of Pennsylvania PhiladelphiaPA19104 United States

Alzheimer's disease is a neurodegenerative condition that accelerates cognitive decline relative to normal aging. It is of critical scientific importance to gain a better understanding of early disease mechanisms in the brain to facilitate effective, targeted therapies. The volume of the hippocampus is often used in diagnosis and monitoring of the disease. Measuring this volume via neuroimaging is difficult since each hippocampus must either be manually identified or automatically delineated, a task referred to as segmentation. Automatic hippocampal segmentation often involves mapping a previously manually segmented image to a new brain image and propagating the labels to obtain an estimate of where each hippocampus is located in the new image. A more recent approach to this problem is to propagate labels from multiple manually segmented atlases and combine the results using a process known as label fusion. To date, most label fusion algorithms employ voting procedures with voting weights assigned directly or estimated via optimization. We propose using a fully Bayesian spatial regression model for label fusion that facilitates direct incorporation of covariate information while making accessible the entire posterior distribution. Our results suggest that incorporating tissue classification (e.g, gray matter) into the label fusion procedure can greatly improve segmentation when relatively homogeneous, healthy brains are used as atlases for diseased brains. The fully Bayesian approach also produces meaningful uncertainty measures about hippocampal volumes, information which can be leveraged to detect significant, scientifically meaningful differences between healthy and diseased populations, improving the potential for early detection and tracking of the disease. © 2017, CC BY.

关键词： Neurodegenerative diseases

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Scalability of a low-cost multi-Teraflop Linux cluster for high-end classical atomistic and quantum mechanical simulations

Scalability of a low-cost multi-Teraflop Linux cluster for h...

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International Parallel and Distributed Processing Symposium, IPDPS 2003

作者： Kikuchi, Hideaki Kalia, Rajiv K. Nakano, Aiichiro Vashishta, Priya Shimojo, Fuyuki Saini, Subhash Collaboratory for Multiscale Simulations Department of Computer Science Department of Physics and Astronomy Department of Materials Science Department of Biomedical Engineering University of Southern California Los AngelesCA90089 United States Concurrent Computing Laboratory for Materials Simulations Biological Computation and Visualization Center Department of Computer Science Department of Physics and Astronomy Louisiana State University Baton RougeLA70803 United States Faculty of Integrated Arts and Sciences Hiroshima University Higashi-Hiroshima739-8521 Japan IT Modeling and Simulation NASA Ames Research Center Moffett FieldCA94035 United States

ISBN: (纸本)0769519261

Scalability of a low-cost, Intel Xeon-based, multi-Teraflop Linux cluster is tested for two high-end scientific applications: Classical atomistic simulation based on the molecular dynamics method and quantum mechanical calculation based on the density functional theory. These scalable parallel applications use spacetime multiresolution algorithms and feature computational-space decomposition, wavelet-based adaptive load balancing, and spacefilling-curve-based data compression for scalable I/O. Comparative performance tests are performed on a 1024-processor Linux cluster and a conventional higher-end parallel supercomputer, 1184-processor IBM SP4. The results show that the performance of the Linux cluster is comparable to that of the SP4. We also study various effects, such as the sharing of memory and L2 cache among processors, on the performance. © 2003 IEEE.

关键词： Scalability

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High Performance Solvers for Implicit Particle in Cell Simulation

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Procedia Computer Science 2013年 18卷 2251-2258页

作者： Pawan Kumar Stefano Markidis Giovanni Lapenta Karl Meerbergen Dirk Roose Department of Computer Science Celestijnenlaan 200A 3001 Heverlee Belgium Flanders Exascience Lab (Intel Labs Europe) Heverlee Belgium High Performance Computing and Visualization (HPCViz) Department KTH Royal Institute of Technology Stockholm Sweden Center for Plasma Astrophysics Department of Mathematics Celestijnenlaan 200B Heverlee Belgium

A three-dimensional implicit particle-in-cell (iPIC3D) method implemented by S. Markidis et. al. in [“Multiscale simulations of plasma with iPIC3D”, Mathematics and Computers in Simulation, 80(2010), 1509-1519] allows time steps at magnetohy- drodynamics time scale. The code requires the solution of two linear systems: a Poisson system related to divergence cleaning, and a system related to a second order formulation of Maxwell equation. In iPIC3D, the former is the most costly. To reduce the cost of solving the Poisson system, a parallel matrix assembly and partitioning method are implemented, and conjugate gradient and algebraic multigrid (AMG) solvers from the Hypre library are called. The scalability of AMG as a solver is studied for 1D and 3D partitionings and compared to that of CG.

关键词： Implicit PIC Algebraic multigrid Krylov solvers Distributed memory

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Future research directions in human-computer interaction

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ACM computing Surveys 1996年第4ES期28卷

作者： John Stasko Graphics Visualization and Usability Center College of Computing Georgia Institute of Technology Atlanta GA

No abstract available.

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