Large Scale Parallel Hybrid GMRES Method for the Linear System on Grid System

Author(s):  
Ye Zhang ◽  
Guy Bergere ◽  
Serge Petiton

Author(s):  
Pingzhou Ming ◽  
Junjie Pan ◽  
Xiaolan Tu ◽  
Dong Liu ◽  
Hongxing Yu

Sub-channel thermal-hydraulics program named CORTH and assembly lattice calculation program named KYLIN2 have been developed in Nuclear Power Institute of China (NPIC). For the sake of promoting the computing efficiency of these programs and achieving the better description on fined parameters of reactor, the programs’ structure and details are interpreted. Then the characteristics of linear systems of these programs are analyzed. Based on the Generalized Minimal Residual (GMRES) method, different parallel schemes and implementations are considered. The experimental results show that calculation efficiencies of them are improved greatly compared with the serial situation.





Geophysics ◽  
2021 ◽  
pp. 1-40
Author(s):  
Wenhao Xu ◽  
Yang Zhong ◽  
Bangyu Wu ◽  
Jinghuai Gao ◽  
Qing Huo Liu

Solving the Helmholtz equation has important applications in various areas, such as acoustics and electromagnetics. Using an iterative solver together with a proper preconditioner is key for solving large 3D Helmholtz equations. The performance of existing Helmholtz preconditioners usually deteriorates when the minimum spatial sampling density is small (approximately four points per wavelength [PPW]). To improve the efficiency of the Helmholtz preconditioner at a small minimum spatial sampling density, we have adopted a new preconditioner. In our scheme, the preconditioning matrix is constructed based on an adaptive complex frequency that varies with the minimum spatial sampling density in terms of the number of PPWs. Furthermore, the multigrid V-cycle with a GMRES smoother is adopted to effectively solve the corresponding preconditioning linear system. The adaptive complex frequency together with a GMRES smoother can work stably and efficiently at different minimum spatial sampling densities. Numerical results of three typical 3D models show that our scheme is more efficient than the multilevel GMRES method and shifted Laplacian with multigrid full V-cycle and a symmetric Gauss-Seidel smoother for preconditioning the 3D Helmholtz linear system, especially when the minimum spatial sampling density is large (approximately 120 PPW) or small (approximately 4 PPW).



2012 ◽  
pp. 1349-1375
Author(s):  
Dang Minh Quan ◽  
Jörn Altmann ◽  
Laurence T. Yang

This chapter describes the error recovery mechanisms in the system handling the Grid-based workflow within the Service Level Agreement (SLA) context. It classifies the errors into two main categories. The first is the large-scale errors when one or several Grid sites are detached from the Grid system at a time. The second is the small-scale errors which may happen inside an RMS. For each type of error, the chapter introduces a recovery mechanism with the SLA context imposing the goal to the mechanisms. The authors believe that it is very useful to have an error recovery framework to avoid or eliminate the negative effects of the errors.



Author(s):  
Yaxing Wei ◽  
Liping Di ◽  
Guangxuan Liao ◽  
Baohua Zhao ◽  
Aijun Chen ◽  
...  

With the rapid accumulation of geospatial data and the advancement of geoscience, there is a critical requirement for an infrastructure that can integrate large-scale, heterogeneous, and distributed storage systems for the sharing of geospatial data within multiple user communities. This article probes into the feasibility to share distributed geospatial data through Grid computing technology by introducing several major issues (including system heterogeneity, uniform mechanism to publish and discover geospatial data, performance, and security) to be faced by geospatial data sharing and how Grid technology can help to solve these issues. Some recent research efforts, such as ESG and the Data Grid system in GMU CSISS, have proven that Grid technology provides a large-scale infrastructure which can seamlessly integrate dispersed geospatial data together and provide uniform and efficient ways to access the data.



1958 ◽  
Vol 105 (22) ◽  
pp. 363
Author(s):  
F.H. Last ◽  
E. Mills ◽  
N.D. Norris


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