• Title, Summary, Keyword: iterative method

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An Iterative Local Search Algorithm for Rural Postman Problems (Rural Postman Problem 해법을 위한 Iterative Local Search 알고리즘)

  • 강명주
    • Journal of the Korea Society of Computer and Information
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    • v.7 no.1
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    • pp.48-53
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    • 2002
  • This paper Proposes an iterative Local Search (ILS) algorithm for Rural Postman Problems (RPPs). LS searches neighbors from an initial solution in solution space and obtains a nearoptimal solution which can be a local-minima. As an extension of LS, the ILS algorithm is a method that uses various initial solutions for LS. Hence. ILS can overcome the defect of LS. This paper proposes LS and ILS methods for 18 RPPs and analyzes the results of LS and ILS. In the simulation results, the ILS method obtained the better results than the LS method.

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Aggregation multigrid method for schur complement system in FE analysis of continuum elements

  • Ko, Jin-Hwan;Lee, Byung Chai
    • Structural Engineering and Mechanics
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    • v.30 no.4
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    • pp.467-480
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    • 2008
  • An aggregation multigrid method (AMM) is a leading iterative solver in solid mechanics. Recently, AMM is applied for solving Schur Complement system in the FE analysis of shell structures. In this work, an extended application of AMM for solving Schur Complement system in the FE analysis of continuum elements is presented. Further, the performance of the proposed AMM in multiple load cases, which is a challenging problem for an iterative solver, is studied. The proposed method is developed by combining the substructuring and the multigrid methods. The substructuring method avoids factorizing the full-size matrix of an original system and the multigrid method gives near-optimal convergence. This method is demonstrated for the FE analysis of several elastostatic problems. The numerical results show better performance by the proposed method as compared to the preconditioned conjugate gradient method. The smaller computational cost for the iterative procedure of the proposed method gives a good alternative to a direct solver in large systems with multiple load cases.

Finite element analysis of vehicle-bridge interaction by an iterative method

  • Jo, Ji-Seong;Jung, Hyung-Jo;Kim, Hongjin
    • Structural Engineering and Mechanics
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    • v.30 no.2
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    • pp.165-176
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    • 2008
  • In this paper, a new iterative method for solving vehicle-bridge interaction problems is proposed. Iterative methods have advantages over the non-iterative methods in that it is not necessary to update the system matrix for a given wheel location, and the method can be applied for a new type of car or bridge with few or no modifications. In the proposed method, the necessity of system matrices update is eliminated using the equivalent interaction force acting on the bridge, which is obtained iteratively. Ballast stiffness is included in the interaction forces and the geometric compatibility at the contact points are used as convergence criteria. The bridge is considered as an elastic Bernoulli-Euler beam with surface irregularity and ballast stiffness. The moving vehicle is modeled as a multi-axle mass-spring-damper system having many degrees of freedom depending on the number of axles. The pitching effect, which is the interaction effect between the rear and front wheels when a vehicle begins to enter or leave the bridge, is also considered in the formulation including extended ground boundaries having surface irregularity and ballast stiffness. The applicability of the proposed method is illustrated in the numerical studies.

ITERATIVE APPROXIMATION TO M-ACCRETIVE OPERATOR EQUATIONS IN BANACH SPACES

  • Park, Jong An;Park, Yang Seob
    • Korean Journal of Mathematics
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    • v.4 no.2
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    • pp.83-88
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    • 1996
  • In 1994 Z.Liang constructed an iterative method for the solution of nonlinear equations involving m-accretive operators in uniformly smooth Banach spaces. In this paper we apply the slight variants of Liang's iterative methods and generalize the results of Z.Liang. Moreover our proof is more simple than Liang's proof.

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FUZZY SLIDING MODE ITERATIVE LEARNING CONTROL Of A MANIPULATOR

  • Park, Jae-Sam
    • Proceedings of the IEEK Conference
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    • pp.1483-1486
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    • 2002
  • In this paper, a new scheme of iterative loaming control of a robot manipulator is presented. The proposed method uses a fuzzy sliding mode controller(FSMC), which is designed based on the similarity between the fuzzy logic control(FLC) and the sliding mode control(SMC), for the feedback. With this, the proposed method makes possible fDr fast iteration and has advantages that no linear approximation is used for the derivation of the learning law or in the stability proof Full proof of the convergence of the fuzzy sliding base learning scheme Is given.

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Evaluation of Non-iterative Shimming Using 2-D Field Map Compared with Simplex Shimming

  • Park, Min-Seok;Kim, Si-Seung;Park, Dae-Jun;Chung, Sung-Taek
    • Proceedings of the KSMRM Conference
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    • pp.152-152
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    • 2001
  • Purpose: The most common instrumental approach to automatic shimming has been based on iterativ. optimization routine(e.g., simplex) to adjust shim settings to maximize the envelope of the FID. Disadvantage of iterative method, however, is very long to compute shim values. Thi paper supposes a non-iterative method that uses 2-D field map to adjust shim settin rapidly.

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An Effective Detection of Bimean and its Application into Image Segmentation by an Interative Algorithm Method (반복적인 알고리즘 방법에 의한 효과적인 양평균 검출 및 영상분할에 응용)

  • Heo, Pil-U
    • 연구논문집
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    • pp.147-154
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    • 1995
  • In this paper, we discussed the convergence and the properties of an iterative algorithm method in order to improve a bimean clustering algorithm. This algorithm that we have discussed choose automatically an optimum threshold as a result of an iterative process, successive iterations providing increasingly cleaner extractions of the object region, The iterative approach of a proposed algorithm is seen to select an appropriate threshold for the low contrast images.

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A DUAL ITERATIVE SUBSTRUCTURING METHOD WITH A SMALL PENALTY PARAMETER

  • Lee, Chang-Ock;Park, Eun-Hee
    • Journal of the Korean Mathematical Society
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    • v.54 no.2
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    • pp.461-477
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    • 2017
  • A dual substructuring method with a penalty term was introduced in the previous works by the authors, which is a variant of the FETI-DP method. The proposed method imposes the continuity not only by using Lagrange multipliers but also by adding a penalty term which consists of a positive penalty parameter ${\eta}$ and a measure of the jump across the interface. Due to the penalty term, the proposed iterative method has a better convergence property than the standard FETI-DP method in the sense that the condition number of the resulting dual problem is bounded by a constant independent of the subdomain size and the mesh size. In this paper, a further study for a dual iterative substructuring method with a penalty term is discussed in terms of its convergence analysis. We provide an improved estimate of the condition number which shows the relationship between the condition number and ${\eta}$ as well as a close spectral connection of the proposed method with the FETI-DP method. As a result, a choice of a moderately small penalty parameter is guaranteed.

Elastodynamic analysis by a frequency-domain FEM-BEM iterative coupling procedure

  • Soares, Delfim Jr.;Goncalves, Kleber A.;de Faria Telles, Jose Claudio
    • Coupled systems mechanics
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    • v.4 no.3
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    • pp.263-277
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    • 2015
  • This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.