• Title, Summary, Keyword: iterative method

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Takagi-Sugeno Fuzzy Model-Based Iterative Learning Control Systems: A Two-Dimensional System Theory Approach (Takagi-Sugeno 퍼지모델에 기반한 반복학습제어 시스템: 이차원 시스템이론을 이용한 접근방법)

  • Chu, Jun-Uk;Lee, Yun-Jung;Park, Bong-Yeol
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.5
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    • pp.385-392
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    • 2002
  • This paper introduces a new approach to analysis of error convergence for a class of iterative teaming control systems. Firstly, a nonlinear plant is represented using a Takagi-Sugeno(T-S) fuzzy model. Then each iterative learning controller is designed for each linear plant in the T-S fuzzy model. From the view point of two-dimensional(2-D) system theory, we transform the proposed learning systems to a 2-D error equation, which is also established if the form of T-S fuzzy model. We analyze the error convergence in the sense of induced L$_2$-norm, where the effects of disturbances and initial conditions on 2-D error are considered. The iterative teaming controller design problem to guarantee the error convergence can be reduced to the linear matrix inequality problem. This method provides a systematic design procedure for iterative teaming controller. A simulation example is given to illustrate the validity of the proposed method.

Explicit Matrix Expressions of Progressive Iterative Approximation

  • Chen, Jie;Wang, Guo-Jin
    • International Journal of CAD/CAM
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    • v.13 no.1
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    • pp.1-11
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    • 2013
  • Just by adjusting the control points iteratively, progressive iterative approximation (PIA) presents an intuitive and straightforward scheme such that the resulting limit curve (surface) can interpolate the original data points. In order to obtain more flexibility, adjusting only a subset of the control points, a new method called local progressive iterative approximation (LPIA) has also been proposed. But to this day, there are two problems about PIA and LPIA: (1) Only an approximation process is discussed, but the accurate convergence curves (surfaces) are not given. (2) In order to obtain an interpolating curve (surface) with high accuracy, recursion computations are needed time after time, which result in a large workload. To overcome these limitations, this paper gives an explicit matrix expression of the control points of the limit curve (surface) by the PIA or LPIA method, and proves that the column vector consisting of the control points of the PIA's limit curve (or surface) can be obtained by multiplying the column vector consisting of the original data points on the left by the inverse matrix of the collocation matrix (or the Kronecker product of the collocation matrices in two direction) of the blending basis at the parametric values chosen by the original data points. Analogously, the control points of the LPIA's limit curve (or surface) can also be calculated by one-step. Furthermore, the $G^1$ joining conditions between two adjacent limit curves obtained from two neighboring data points sets are derived. Finally, a simple LPIA method is given to make the given tangential conditions at the endpoints can be satisfied by the limit curve.

AN ITERATIVE METHOD FOR NONLINEAR MIXED IMPLICIT VARIATIONAL INEQUALITIES

  • JEONG, JAE UG
    • Honam Mathematical Journal
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    • v.26 no.4
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    • pp.391-399
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    • 2004
  • In this paper, we develop an iterative algorithm for solving a class of nonlinear mixed implicit variational inequalities in Hilbert spaces. The resolvent operator technique is used to establish the equivalence between variational inequalities and fixed point problems. This equivalence is used to study the existence of a solution of nonlinear mixed implicit variational inequalities and to suggest an iterative algorithm for solving variational inequalities. In our results, we do not assume that the mapping is strongly monotone.

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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.

Frictional Contact Analysis of the compression-Induced Crack Surfaces using the Finite element Method (유한요소법을 이용한 압축력으로 인한 균열 표면의 마찰접촉 해석)

  • 김방원;이기수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.517-522
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    • 2000
  • When a body including a crack inside is subjected to the compressive forces, the crack is closed and sliding occurs on the crack surfaces. In this work, a subsurface crack subjected to a static or moving compressive load is analyzed with the finite element method considering friction on the crack surface. The friction on the crack surface is assumed to follow the Coulomb friction law. A numerical method based on the finite element method and iterative method is applied in this work. And the result is compared with the frictional contact of crack by ANSYS using contact 12 element. The numerical results of two methods are compared with the wellknown analytical solutions, and the accuracy of iterative method is checked..

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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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Direct Earthquake Design Using Secant Stiffness (할선강성을 이용한 직접내진설계)

  • 박홍근;엄태성
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.239-246
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    • 2003
  • A new earthquake design method performing iterative calculations using secant stiffness was developed. The proposed design method has the advantages of convenience and stability in numerical analysis because it uses elastic analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it performs the analysis on the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and its advantages were presented by the comparisons with existing design methods using elastic or inelastic analysis. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member, the design concept of strong column - weak beam, and etc. Through iterative calculations on the structure preliminarily designed only with member sizing, the strength and ductility demands of each member can be directly calculated so as to satisfy the given design strategy As the result economical and safe design can be achieved.

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Three-Dimensional Grid Generation Method for an Orthogonal Grid at the Boundary by Using Boundary Element Method (경계요소법을 이용한 경계에 직교하는 삼차원 격자형성법)

  • Jeong H. K.;Kwon J. H.
    • 한국전산유체공학회:학술대회논문집
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    • pp.82-89
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    • 1995
  • In the present paper, a method of nearly orthogonal grid generation in an arbitrary simply-connected 3D domain will be presented. The method is a new direct and non-iterative scheme based on the concept of the decomposition of the global orthogonal transformation into consecutive mapping of a conformal mapping and an auxiliary orthogonal mapping, which was suggested by King and Leal [4]. In our numerical scheme. Kang and Leal's method is extended from 2D problems to 3D problems while the advantage of the non-iterative algorithm is maintained. The essence of the present mapping method is that an iterative scheme can be avoided by introducing a preliminary step. This preliminary step corresponds to a conformal map and is based on the boundary element method(BEM). This scheme is applied to generate several nearly-orthogonal grid systems which are orthogonal at boundaries.

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Direct Nonlinear Strut-Tie Model Using Secant Stiffness (할선강성을 이용한 직접 비선형 스트럿-타이 모델)

  • 김윤곤;엄태성;박홍근
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.384-387
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    • 2003
  • A new Direct Nonlinear Strut-Tie Model design method performing iterative calculations using secant stiffness was developed. Since basically the proposed design method uses elastic analysis, it has the advantages of convenience and stability in numerical analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it analyzes the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member. Through iterative calculations on the structure preliminary designed with member sizes, the strength and ductility demands of each member can be estimated so that they satisfy the given design strategy, and as the result economical and safe design is achieved.

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DIRECT INELASTIC EARTHQUAKE DESIGN OF R/C STRUCTURE

  • Park, Hong-Gun;Eom, Tae-Sung
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.472-477
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    • 2004
  • A new earthquake design method performing iterative calculations with secant stiffness was developed. Since basically the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of the structural members through iterative calculations. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed method, as an integrated analysis and design method, can directly address the earthquake design strategy intended by the engineer, such as limited ductility of member and the concept of strong column - weak beam. Through iterative calculations on a structural model with member sizes preliminarily assumed, the strength and ductility demands of each member can be determined so as to satisfy the given design strategy. As the result, structural safety and economical design can be achieved.

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