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PETSc/TS: A modern scalable ODE/DAE solver library

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arXiv 2018年

作者： Abhyankar, Shrirang Brown, Jed Constantinescu, Emil M. Ghosh, Debojyoti Smith, Barry F. Zhang, Hong Energy Systems Division Argonne National Laboratory 9700 South Cass Avenue LemontIL60439-5844 United States Department of Computer Science University of Colorado Boulder 430 UCB BoulderCO80309 United States Mathematics and Computer Science Division Argonne National Laboratory 9700 South Cass Avenue LemontIL60439-4844 United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory 7000 East Avenue LivermoreCA94550 United States

High-quality ordinary differential equation (ODE) solver libraries have a long history, going back to the 1970s. Over the past several years we have implemented, on top of the PETSc linear and nonlinear solver package, a new general-purpose, extensive, extensible library for solving ODEs and differential algebraic equations (DAEs). Package includes support for both forward and adjoint sensitivities that can be easily utilized by the TAO optimization package, which is also part of PETSc. The ODE/DAE integrator library strives to be highly scalable but also to deliver high efficiency for modest-sized problems. The library includes explicit solvers, implicit solvers, and a collection of implicit-explicit solvers, all with a common user interface and runtime selection of solver types, adaptive error control, and monitoring of solution progress. The library also offers enormous exibility in selection of nonlinear and linear solvers, including the entire suite of PETSc iterative solvers, as well as several parallel direct solvers. Copyright © 2018, The Authors. All rights reserved.

关键词： Ordinary differential equations

The computation of seismic normal modes with rotation as a quadratic eigenvalue problem

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arXiv 2019年

作者： Shi, Jia Li, Ruipeng Xi, Yuanzhe Saad, Yousef de Hoop, Maarten V. Department of Earth Environmental and Planetary Sciences Rice University United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory LivermoreCA United States Department of Mathematics Emory University AtlantaGA United States Department of Computer Science and Engineering University of Minnesota MN United States Simons Chair in Computational and Applied Mathematics and Earth Science Rice University HoustonTX United States

A new approach is presented to compute the seismic normal modes of a fully heterogeneous, rotating planet. Special care is taken to separate out the essential spectrum in the presence of a fluid outer core. The relevant elastic-gravitational system of equations, including the Coriolis force, is subjected to a mixed finite-element method, while self-gravitation is accounted for with the fast multipole method (FMM). To solve the resulting quadratic eigenvalue problem (QEP), the approach utilizes extended Lanczos vectors forming a subspace computed from a non-rotating planet – with the shape of boundaries of a rotating planet and accounting for the centrifugal potential – to reduce the dimension of the original problem significantly. The subspace is guaranteed to be contained in the space of functions to which the seismic normal modes belong. The reduced system can further be solved with a standard eigensolver. The computational accuracy is illustrated using all the modes with relative small meshes and also tested against standard perturbation calculations relative to a standard Earth model. The algorithm and code are used to compute the point spectra of eigenfrequencies in several Mars models studying the effects of heterogeneity on a large range of scales. Copyright © 2019, The Authors. All rights reserved.

关键词： Seismology

Statistical Analysis of Intrinsic High-Frequency Characteristic Fluctuation of Emerging Silicon Gate-All-Around Nanosheet (NS) MOSFETs at Sub-3-nm Nodes

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Statistical Analysis of Intrinsic High-Frequency Characteris...

IEEE Electron Devices Technology and Manufacturing Conference (EDTM)

作者： Sekhar Reddy Kola Yiming Li Min-Hui Chuang Kazuhiko Endo Seiji Samukawa Parallel and Scientific Computing Laboratory Electrical Engineering and Computer Science International Graduate Program Institute of Communications Engineering Department of Electronics and Electrical Engineering Institute of Biomedical Engineering Center for mm Wave Smart Radar System and Technologies National Yang Ming Chiao Tung University Hsinchu Taiwan Institute of Fluid Science Tohoku University 2-1-1 Katahira Aoba-ku Sendai Japan National Institute of Advanced Industrial Science and Technology Tsukuba Japan

In recent years, the GAA NS Si MOSFET has been explored as a leading technology. However, the intrinsic parameters of GAA NS Si MOSFETs are affected to varying degrees by various fluctuation sources, Statistically independent and identically distributed $(iid)$ assumptions on the aforementioned random variables overestimate the variability of high-frequency characteristics, compared with considering all fluctuation factors simultaneously. Notably, the random nanosized metal grains dominates the variations of voltage gain, cut-off frequency, and 3dB frequency because the random work functions strongly alter the channel surface potential.

关键词： MOSFET Fluctuations Statistical analysis Gallium arsenide Cutoff frequency Metals Logic gates

Achievable Rate Maximization Pattern Design for Reconfigurable MIMO Antenna Array

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arXiv 2022年

作者： Wang, Haonan Li, Ang Liu, Ya-Feng Qin, Qibo Song, Lingyang Li, Yonghui The School of Information and Communications Engineering Faculty of Electronic and Information Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China The State Key Laboratory of Integrated Services Networks Xidian University Shaanxi Xi'An China The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Wireless Network RAN Research Department Shanghai Huawei Technologies Co. Ltd. Shanghai201206 China The School of Electrical Engineering and Computer Science Peking University Beijing100871 China The School of Electrical and Information Engineering The University of Sydney SydneyNSW2006 Australia

Reconfigurable multiple-input multiple-output can provide performance gains over traditional MIMO by reshaping the channels, i.e., introducing more channel realizations. In this paper, we focus on the achievable rate maximization pattern design for reconfigurable MIMO systems. Firstly, we introduce the matrix representation of pattern reconfigurable MIMO (PR-MIMO), based on which a pattern design problem is formulated. To further reveal the effect of the radiation pattern on the wireless channel, we consider pattern design for both the single-pattern case where the optimized radiation pattern is the same for all the antenna elements, and the multi-pattern case where different antenna elements can adopt different radiation patterns. For the single-pattern case, we show that the pattern design is equivalent to a redistribution of gains among all scattering paths, and an eigenvalue optimization based solution is obtained. For the multi-pattern case, we propose a sequential optimization framework with manifold optimization and eigenvalue decomposition to obtain near-optimal solutions. Numerical results validate the superiority of PR-MIMO systems over traditional MIMO in terms of achievable rate, and also show the effectiveness of the proposed solutions. Copyright © 2022, The Authors. All rights reserved.

关键词： MIMO systems

Native and generic parallel programming environments on a transputer and a PowerPC platform

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Concurrency and Computation: Practice and Experience 1996年第1期8卷

作者： A.G. Hoekstra P.M.A. Sloot F. van der Linden M. van Muiswinkel J.J.J. Vesseur L.O. Hertzberger Parallel Scientific Computing & Simulation Group Computer Systems Department Faculty of Mathematics and Computer Science University of Amsterdam Kruislaan 409 1098 SJ Amsterdam The Netherlands

Genericity of parallel programming environments, enabling development of portable parallel programs, is expected to result in performance penalties. Furthermore, programmability and tool support of programming environments are important issues if a choice between programming environments has to be made. In this paper we propose a methodology to compare native and generic parallel programming environments, taking into account such competing issues as portability and performance. As a case study, this paper compares the Iserver-Occam, Parix, Express and PVM parallel programming environments on a 512-node Parasytec GCel. Furthermore, we apply our methodology to compare Parix and PVM on a new architecture, a 32-node Parsytec PowerXplorer, which is based on the PowerPC chip. In our approach we start with a representative application and isolate the basic (environment)-dependent building blocks. These basic building blocks, which depend on floating-point performance and communication capabilities of the environments, are analysed independently. We have measured point-to-point communication times, global communication times and floating-point performance. All information is combined into a time complexity analysis, allowing comparison of the environments on different degrees of functionality. Together with demands for portability of the code and development time (i.e. programmability), an overall judgement of the environments is given.

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International Joint Conference SOCO’14-CISIS’14-ICEUTE’14 1

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丛书名： Advances in Intelligent Systems and computing

1000年

作者： José Gaviria Puerta Iván García Ferreira Pablo Garcia Bringas Fanny Klett Ajith Abraham André C.P.L.F. Carvalho Álvaro Herrero Bruno Baruque Héctor Quintián Emilio Corchado

A pragmatic workflow for research software engineering in computational science

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arXiv 2023年

作者： Maric, Tomislav Gläser, Dennis Lehr, Jan-Patrick Papagiannidis, Ioannis Lambie, Benjamin Bischof, Christian Bothe, Dieter Mathematical modeling and analysis Mathematics department TU Darmstadt Darmstadt64287 Germany Institute for Modelling Hydraulic and Environmental Systems Department of Hydromechanics and Modelling of Hydrosystems University of Stuttgart Stuttgart70569 Germany Institute for Scientific Computing Department of Computer Science TU Darmstadt Darmstadt64289 Germany Research Field Energy & Environment TU Darmstadt Darmstadt64287 Germany

University research groups in Computational science and Engineering (CSE) lack funding and personnel for Research Software Engineering (RSE), which leads to a focus on journal publications over sustainable software development and reproducible results. This negatively impacts CSE research output, with data and software related to publications being difficult to find, reproduce, or reuse. We propose an RSE workflow for CSE that addresses these challenges and improves research output quality by applying established software engineering practices such as version control and testing, as well as cross-linking software with data and publications. The workflow is minimal in terms of overhead and produces tested software cross-linked with publications and reproducible results. We define research software quality as the ability to quickly find and understand related publications, data, and software, and to extend existing code to realize new research ideas. © 2023, CC BY.

关键词： computer software reusability

A class of refined implicit-explicit Runge-Kutta methods with robust time adaptability and unconditional convergence for the Cahn-Hilliard model

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arXiv 2024年

作者： Liao, Hong-Lin Tang, Tao Wang, Xuping Zhou, Tao School of Mathematics Nanjing University of Aeronautics and Astronautics Nanjing211106 China MIIT Nanjing211106 China School of Electrical and Computer Engineering Guangzhou Nanfang College Institute for Advanced Study BNU-HKBU United International College China Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

One of main obstacles in verifying the energy dissipation laws of implicit-explicit Runge-Kutta (IERK) methods for phase field equations is to establish the uniform boundedness of stage solutions without the global Lipschitz continuity assumption of nonlinear bulk. With the help of discrete orthogonal convolution kernels, an updated time-space splitting technique is developed to establish the uniform boundedness of stage solutions for a refined class of IERK methods in which the associated differentiation matrices and the average dissipation rates are always independent of the time-space discretization meshes. This makes the refined IERK methods highly advantageous in self-adaptive time-stepping procedures as some larger adaptive step-sizes in actual simulations become possible. From the perspective of optimizing the average dissipation rate, we construct some parameterized refined IERK methods up to third-order accuracy, in which the involved diagonally implicit Runge-Kutta methods for the implicit part have an explicit first stage and allow a stage-order of two such that they are not necessarily algebraically stable. Then we are able to establish, for the first time, the original energy dissipation law and the unconditional L2 norm convergence. Extensive numerical tests are presented to support our *** Codes 35K58, 65L20, 65M06, 65M12 © 2024, CC BY-NC-ND.

关键词： Runge Kutta methods

Determining HEDP Foams’ Quality with Multi-View Deep Learning Classification

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arXiv 2022年

作者： Schneider, Nadav Rusanovsky, Matan Gvishi, Raz Oren, Gal Technology Division Soreq Nuclear Research Center Yavne Israel Israel Atomic Energy Commission Scientific Computing Center Nuclear Research Center Negev Israel Department of Physics Nuclear Research Center Negev Israel Applied Physics Division Soreq Nuclear Research Center Yavne Israel Department of Computer Science Technion – Israel Institute of Technology Israel

High energy density physics (HEDP) experiments commonly involve a dynamic wave-front propagating inside a low-density foam. This effect affects its density and hence, its transparency. A common problem in foam production is the creation of defective foams. Accurate information on their dimension and homogeneity is required to classify the foams’ quality. Therefore, those parameters are being characterized using a 3D-measuring laser confocal microscope. For each foam, five images are taken: two 2D images representing the top and bottom surface foam planes and three images of side cross-sections from 3D scannings. An expert has to do the complicated, harsh, and exhausting work of manually classifying the foam’s quality through the image set and only then determine whether the foam can be used in experiments or not. Currently, quality has two binary levels of normal vs. defective. At the same time, experts are commonly required to classify a sub-class of normal-defective, i.e., foams that are defective but might be sufficient for the needed experiment. This sub-class is problematic due to inconclusive judgment that is primarily intuitive. In this work, we present a novel state-of-the-art multi-view deep learning classification model that mimics the physicist’s perspective by automatically determining the foams’ quality classification and thus aids the expert. Our model achieved 86% accuracy on upper and lower surface foam planes and 82% on the entire set, suggesting interesting heuristics to the problem. A significant added value in this work is the ability to regress the foam quality instead of binary deduction and even explain the decision visually. The source code used in this work, as well as other relevant sources, are available at: https://***/scientific-computing-Lab-NRCN/***. © 2022, CC BY.

关键词： Classification (of information)