• Title, Summary, Keyword: Iterative refinement

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Blockwise analysis for solving linear systems of equations

  • Smoktunowicz, Alicja
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.3 no.1
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    • pp.31-41
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    • 1999
  • We investigate some techniques of iterative refinement of solutions of a nonsingular system Ax = b with A partitioned into blocks using only single precision arithmetic. We prove that iterative refinement improves a blockwise measure of backward stability. Some applications of the results for the least squares problem (LS) will be also considered.

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A modification of double projection method for adaptive analysis of Element-free Galerkin Method (적응적 Element-free Galerkin Method 해석을 위한 이중투영법의 개선)

  • 이계희;정흥진;이태열
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.615-622
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    • 2002
  • In this paper, the modification of double projection method for the adaptive analysis of Element-free Galerkin(EFG) method were proposed. As results of the double projection method, the smoothed error profile that is adequate for adaptive analysis was obtained by re-projection of error that means the differences of EFG stress and projected stress. However, it was found that the efficiency of double projection method is degraded as increase of the numerical integration order. Since, the iterative refinement to single step error estimation made the same effect as increasing of integration order, the application of the iterative refinement base on double projection method could be produced the inadequately refined analysis model. To overcome this defect, a modified scheme of double projection were proposed. In the numerical example, the results did not show degradation of double projection effect in iterative refinement and the efficiency of proposed scheme were proved.

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An Iterative Side Information Refinement Based on Block-Adaptive Search in Distributed Video Coding (분산 비디오 부호화에서 블록별 적응적 탐색에 기초한 반복적인 보조정보 보정기법)

  • Kim, Jin-Soo;Yun, Mong-Han;Kim, Jae-Gon;Seo, Kwang-Deok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.2
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    • pp.355-363
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    • 2011
  • Recently, as one of several methods to improve the performance of DVC(Distributed Video Coding) system, many research works are focusing on the iterative refinement of side information. Most of the conventional techniques are mainly based on the relationship between the reconstruction level and side information, or the vector median filtering of motion vectors, but, their performance improvements are restricted. In order to overcome the performance limit of the conventional schemes, in this paper, a side information generation scheme is designed by measuring the block-cost estimation. Then, by adaptively selecting the compensation mode using the received bit-plane information, we propose a block-adaptive iterative refinement which is efficient for non-symmetric moving objects. Computer simulations show that, by using the proposed refinement method, the performance can be improved up to 0.2 dB in rate-distortion.

Elasto-plastic nonconforming solid element with variable nodes

  • Choi, Chang-Koon;Chung, Gi-Taek
    • Structural Engineering and Mechanics
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    • v.3 no.4
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    • pp.325-340
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    • 1995
  • The iterative procedure to use the nonconforming elements in elasto-plastic problems is established and applied to the variable node transition solid element developed for the automated three-dimensional local mesh refinement. Through numerical tests, the validity and performance of the element are examined. As the nonlinear iterative procedure presented in this paper is accomplished for the general three-dimensional case, it can also be easily applied to the two-dimensional elements such as membranes, plates and shells.

Wave information retrieval algorithm based on iterative refinement (반복적 보정에 의한 파랑정보 추출 기법)

  • Kim, Jin-soo;Lee, Byung-Gil
    • Journal of the Korea Industrial Information Systems Research
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    • v.21 no.1
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    • pp.7-15
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    • 2016
  • Ocean wave parameters are important for safety and efficiency of operation and routing of marine traffic. In this paper, by using X-band marine radar, we try to develop an effective algorithm for collecting ocean surface information such as current velocity, wave parameters. Specifically, by exploiting iterative refinement flow instead of using fixed control schemes, an effective algorithm is designed in such a way that it can not only compute efficiently the optimized current velocity but also introduce new cost function in an optimized way. Experimental results show that the proposed algorithm is very effective in retrieving the wave information compared to the conventional algorithms.

Iterative Cell-wise Solution Method for the Adaptive Analysis of a Meshless Method (무요소법의 적응해석을 위한 반복격자해법)

  • 석병호;임장근
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.607-614
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    • 2002
  • For the accurate analysis of crack problems, considerable nodal refinement near the crack tip to capture singular stress field with sufficient accuracy to provide a useful computation of stress intensity factor is required. So, in this paper, adaptive nodal refinement scheme is proposed where nodes in restricted cell regions centered at crack tip are arranged in array for enhanced spatial resolution and adaptivity. With only cell-wise adaptive refinement scheme around crack tip fields, singularity of crack tip is sufficiently described to expect a successive crack propagate direction. Through numerical tests, accuracy of the proposed adaptive scheme is investigated and compared with the finite element and experimental results. By this implementation, it is shown that high accuracy is achieved by using iterative cell-wise solution method fur analyzing crack propagation problems.

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SOME MULTI-STEP ITERATIVE SCHEMES FOR SOLVING NONLINEAR EQUATIONS

  • Rafiq, Arif;Pasha, Ayesha Inam;Lee, Byung-Soo
    • The Pure and Applied Mathematics
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    • v.20 no.4
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    • pp.277-286
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    • 2013
  • In this paper, we suggest and analyze a family of multi-step iterative methods which do not involve the high-order differentials of the function for solving nonlinear equations using a different type of decomposition (mainly due to Noor and Noor [15]). We also discuss the convergence of the new proposed methods. Several numerical examples are given to illustrate the efficiency and the performance of the new iterative method. Our results can be considered as an improvement and refinement of the previous results.

THREE STEP ITERATIVE ALGORITHMS FOR GENERALIZED QUASIVARIATIONAL INCLUSIONS

  • Park, Jong-Yeoul;Jeong, Jae-Ug
    • Bulletin of the Korean Mathematical Society
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    • v.41 no.1
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    • pp.1-11
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    • 2004
  • In this paper, we suggest and analyze some new classes of three step iterative algorithms for solving generalized quasivariational inclusions by using the properties of proximal maps. Our results include the Ishikawa, Mann iterations for solving variational inclusions(inequalities) as special cases. The results obtained in this paper represent an improvement and significant refinement of previously known results [3, 5-8, 10, 14-18].

CONVERGENCE OF AN ITERATIVE ALGORITHM FOR SYSTEMS OF GENERALIZED VARIATIONAL INEQUALITIES

  • Jeong, Jae Ug
    • Korean Journal of Mathematics
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    • v.21 no.3
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    • pp.213-222
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    • 2013
  • In this paper, we introduce and consider a new system of generalized variational inequalities involving five different operators. Using the sunny nonexpansive retraction technique we suggest and analyze some new explicit iterative methods for this system of variational inequalities. We also study the convergence analysis of the new iterative method under certain mild conditions. Our results can be viewed as a refinement and improvement of the previously known results for variational inequalities.