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A comparison of three kinds of local and parallel finite element algorithms based on two-grid discretizations for the stationary Navier-Stokes equations

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COMPUTERS & FLUIDS 2011年第1期40卷 249-257页

作者： Shang, Yueqiang He, Yinnian Luo, Zhendong Guizhou Normal Univ Sch Math & Comp Sci Guiyang 550001 Peoples R China Xi An Jiao Tong Univ Fac Sci Xian 710049 Peoples R China

Based on two-grid discretizations, three kinds of local and parallel finite element algorithms for the stationary Navier-Stokes equations are introduced and discussed. The main technique is first to use a standard finite element discretization on a coarse grid to approximate low frequencies of the solution, then to apply some linearized discretizations on a fine grid to correct the resulted residual (which contains mostly high frequencies) by some local and parallel procedures. Three approaches to linearization are discussed. Under the uniqueness condition, error estimates of the finite element solution are derived. Numerical results show that among the three kinds of parallel algorithms, the Oseen-linearized algorithm is preferable if we both consider the computational time and the accuracy of the approximate solution. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Navier-Stokes equations Finite element Two-grid discretizations parallel algorithm

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parallel addition in non-standard numeration systems

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THEORETICAL COMPUTER SCIENCE 2011年第41期412卷 5714-5727页

作者： Frougny, Christiane Pelantova, Edita Svobodova, Milena Czech Tech Univ Dept Math FNSPE Prague 12000 2 Czech Republic Czech Tech Univ Doppler Inst Math Phys & Appl Math Prague 12000 2 Czech Republic CNRS UMR 7089 LIAFA F-75205 Paris 13 France Univ Paris 07 F-75205 Paris 13 France Univ Paris 08 F-75205 Paris 13 France

We consider numeration systems where digits are integers and the base is an algebraic number beta such that vertical bar beta vertical bar > 1 and beta satisfies a polynomial where one coefficient is dominant in a certain sense. For this class of bases beta, we can find an alphabet of signed-digits on which addition is realizable by a parallel algorithm in constant time. This algorithm is a kind of generalization of the one of Avizienis. We also discuss the question of cardinality of the used alphabet, and we are able to modify our algorithm in order to work with a smaller alphabet. We then prove that beta satisfies this dominance condition if and only if it has no conjugate of modulus 1. When the base beta is the Golden Mean, we further refine the construction to obtain a parallel algorithm on the alphabet {-1, 0, 1}. This alphabet cannot be reduced any more. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Numeration Addition parallel algorithm Golden Mean

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The kinetic process of non-smooth substrate thin film growth via parallel Monte Carlo method

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APPLIED SURFACE SCIENCE 2011年第14期257卷 6102-6106页

作者： Chen, Zi-Yi Zhu, Yuan Chen, Shu-Han Qiu, Zhi-Ren Jiang, Shao-Ji Sun Yat Sen Univ State Key Lab Optoelect Mat & Technol Guangzhou 510275 Guangdong Peoples R China

A Monte Carlo simulation model of thin film growth based on parallel algorithm is presented. Non-smooth substrate with special defect mode is introduced in such a model. The method of regionalizing is used to divide the substrate into sub-regions. This method is supposed to be modulated according to the defect mode. The effects of surface defect mode and substrate temperature, such as the nucleation ratio and the average island size, are studied through parallel Monte Carlo method. The kinetic process of thin film growth in the defect mode is also discussed. Results show that surface defect mode contributes to crystal nucleation. Analyzing parallel simulation results we find that density defect points, substrate temperature and the number of processors contribute decisively to the parallel efficiency and speedup. According to defect mode we can obtain large grain size more feasibly and the parallel algorithm of this model can guide the non-smooth substrate simulation work. (C) 2011 Elsevier B. V. All rights reserved.

关键词： Thin film growth Simulation Monte Carlo method parallel algorithm

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A massively parallel hybrid scheme for direct numerical simulation of turbulent viscoelastic channel flow

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COMPUTERS & FLUIDS 2011年第1期43卷 134-142页

作者： Thais, Laurent Tejada-Martinez, Andres E. Gatski, Thomas B. Mompean, Gilmar Univ Lille Nord France USTL F-59000 Lille France CNRS LML UMR 8107 F-59655 Villeneuve Dascq France Univ S Florida Dept Civil & Environm Engn Tampa FL USA Univ Poitiers CNRS Inst Pprime Dept FluidesENSMA F-86962 Futuroscope France

This paper describes in detail a numerical scheme designed for direct numerical simulation (DNS) of turbulent drag reduction. The hybrid spatial scheme includes Fourier spectral accuracy in two directions and sixth-order compact finite differences for first and second-order wall-normal derivatives, while time marching can be up to fourth-order accurate. High-resolution and high-drag reduction viscoelastic DNS are made possible through domain decomposition with a two-dimensional MPI Cartesian grid alternatively splitting two directions of space ('pencil' decomposition). The resulting algorithm has been shown to scale properly up to 16384 cores on the Blue Gene/P at IDRIS-CNRS, France. Drag reduction is modeled for the three-dimensional wall-bounded channel flow of a FENE-P dilute polymer solution which mimics injection of heavy-weight flexible polymers in a Newtonian solvent. We present results for four high-drag reduction viscoelastic flows with friction Reynolds numbers Re-tau 0= 180, 395, 590 and 1000, all of them sharing the same friction Weissenberg number We(tau 0) = 115 and the same rheological parameters. A primary analysis of the DNS database indicates that turbulence modification by the presence of polymers is Reynolds-number dependent. This translates into a smaller percent drag reduction with increasing Reynolds number, from 64% at Re-tau 0= 180 down to 59% at Re-tau 0= 1000, and a steeper mean current at small Reynolds number. The Reynolds number dependence is also visible in second-order statistics and in the vortex structures visualized with iso-surfaces of the Q-criterion. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： parallel algorithm Drag reduction Polymer Turbulence DNS Channel flow

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parallel FPGA Placement algorithm on Multi-core Processor

Parallel FPGA Placement Algorithm on Multi-core Processor

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2011 4th IEEE International Conference on Computer Science and Information Technology(ICCSIT 2011)

作者： Bohu Huang Inst.of Computing Theory & Technology Xidian University Xi'an,China Zhihong Xie Inst.of Computing Theory & Technology Xidian University Xi'an,China Haibin Zhang Inst.of Computing Theory & Technology Xidian University Xi'an,China

As the sizes of FPGA device grow,the long run-time of the placement is becoming a great challenge for the FPGA design *** annealing is the best-known method applied to this problem due to the good quality of result（QoR）,but its computation time seems not *** this paper,we propose a parallel placement algorithm named MPP-SA（Multi-core parallel Placement algorithm based on Simulated Annealing）.Our goal is to provide a fast placement algorithm with high ***-SA has the same annealing schedule as the traditional simulated annealing,but it uses the parallel approach to move blocks concurrently by multiple threads that are run on different cores of the same *** ensure the correctness of the results,MPP-SA also uses synchronization technology and lock mechanism,which brings some ***,experiment results show that these overheads have not seriously affected the performance of our algorithm,especial for large *** with the placement algorithm of TPlace in VPR5.0,MPP-SA is able to decrease the run-time of 5 different size benchmark circuits by an average of 32%-42% without losing QoR.

关键词： FPGA multi-core parallel algorithm simulated annealing design AIDS

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parallel Improvement for a Classical Template Serial Thinning algorithm

Parallel Improvement for a Classical Template Serial Thinnin...

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The 2011 International Conference on Advanced Materials and Information Technology Processing(AMITP 2011)

作者： Mei Xiu Lu Furong Wang Feng Li Cisco School of Informatics Guangdong University of Foreign Studies School of Information Beijing Wuzi University College of Applied Mathematics Guangdong University of Technology

ISBN: (纸本)9783037851579

Image thinning is one of important steps of fingerprint preprocessing. Most of fingerprint recognition algorithms checked the characteristic points on thinning image. In this paper, we discover some shortages in OPTA and mathematical morphology thinning algorithm and find out the reasons for some shortages such as many glitches and snags, defective thinning, and so on. A new improved algorithm is proposed in the paper, which is an ideal algorithm because it is faster, produces less glitch, and thins completely.

关键词： Image processing OPTA algorithm thinning parallel algorithm

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algorithmS OF parallel COMPUTATIONS FOR LINEAR ALGEBRA PROBLEMS WITH IRREGULARLY STRUCTURED MATRICES

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CYBERNETICS AND SYSTEMS ANALYSIS 2011年第6期47卷 973-985页

作者： Khimich, A. N. Popov, A. V. Polyanko, V. V. Natl Acad Sci Ukraine VM Glushkov Cybernet Inst Kiev Ukraine

parallel algorithms for direct methods of analysis and solution of linear algebra problems with sparse symmetric irregularly structured matrices are considered. The performance of such algorithms is investigated. Upper estimates of the speedup and efficiency factors are obtained for a parallel algorithm for triangular decomposition of sparse matrices. Some results of numerical experiments carried out on a MIMD computer are given.

关键词： linear algebra sparse symmetric matrix parallel algorithm efficiency

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A Fast parallel SVM algorithm for Massive Classification Tasks

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2nd International Conference on Modelling, Computation and Optimization in Information Systems and Management Sciences

作者： Do, Thanh-Nghi Nguyen, Van-Hoa Poulet, Francois CanTho Univ CIT Can Tho Vietnam IRISA Rennes France

ISBN: (纸本)9783540874768

The new parallel incremental Support Vector Machine (SVM) algorithm aims at classifying very large datasets on graphics processing units (GPUs). SVM and kernel related methods have shown to build accurate models but the learning task usually needs a quadratic programming , so that the learning task for large datasets requires big memory capacity and a long time. We extend the recent finite Newton classifier for building a parallel incremental algorithm. The new algorithm uses graphics processors to gain high performance at low cost. Numerical test results on UCI. Delve dataset repositories showed that our parallel incremental algorithm using GPUs is about 45 times faster than a CPU implementation and often significantly over 100 times faster than state-of-the-art algorithms LibSVM, SVM-perf and CB-SVM.

关键词： Support vector machines incremental learning parallel algorithm graphics processing unit massive data classification

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parallel DEBLOCKING FILTER FOR H.264/AVC IMPLEMENTED ON TILE64 PLATFORM

PARALLEL DEBLOCKING FILTER FOR H.264/AVC IMPLEMENTED ON TILE...

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Yan, Chenggang Dai, Feng Zhang, Yongdong Ma, Yike Chen, Licheng Fan, Lingjun Zheng, Yasong Chinese Acad Sci Inst Comp Technol Beijing 100190 Peoples R China

ISBN: (纸本)9781612843490

For the purpose of accelerating deblocking filter, which accounts for a significant percentage of H.264/AVC decoding time, some researchers use multi-core platforms to achieve the required performance. We study the problem under the context of many-core systems. parallelization of deblocking filter on many-core platform is challenging not only because deblocking filter has complicated data dependencies which provides insufficient parallelism for so many cores but also because parallelization may have significant synchronization overhead. We present a new method to exploit the implicit parallelism and reduce the synchronization overhead. We apply our implementation to the deblocking filter of the H.264/AVC reference software JM15.1 on Tile64 platform. The proposed method achieves up to 817%, 604% and 532% speedup for CIF, SD and HD videos compared to the well-known wavefront method using 62 cores, respectively.

关键词： H.264/AVC Deblocking filter parallel algorithm Tile64

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parallel Deblocking Filter for H.264/AVC on the TILERA Many-Core Systems

Parallel Deblocking Filter for H.264/AVC on the TILERA Many-...

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17th International Multimedia Modeling Conference, MMM 2011

作者： Yan, Chenggang Dai, Feng Zhang, Yongdong Chinese Acad Sci Inst Comp Technol Multimedia Comp Grp Beijing Peoples R China

ISBN: (纸本)9783642178313

For the purpose of accelerating deblocking filter, which accounts for a significant percentage of H.264/AVC decoding time, some studies use wavefront method to achieve the required performance on multi-core platforms. We study the problem under the context of many-core systems and present a new method to exploit the implicit parallelism. We apply our implementation to the deblocking filter of the H.264/AVC reference software JM15.1 on a 64-core TILERA and achieve more than eleven times speedup for 1280*720(HD) videos. Meanwhile the proposed method achieves an overall decoding speedup of 140% for the HD videos. Compared to the wavefront method, we also have a significant speedup 200% for 720*576(SD) videos.

关键词： Video decoding H.264/AVC Deblocking filter parallel algorithm Many-core systems

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