• 제목/요약/키워드: Approximation Order

검색결과 1,075건 처리시간 0.028초

2차원 구조물의 최적형상설계에 관한 연구 (A Study on the Optimal Shape Design of 2-D Structures)

  • 김홍건;양성모;노홍길;나석찬;유기현;조남익
    • 한국공작기계학회논문집
    • /
    • 제12권2호
    • /
    • pp.9-16
    • /
    • 2003
  • A strategy of the optimal shape design with FEA(Finite Element Analysis) for 2-D structure is proposed by comparing subproblem approximation method with first order approximation method. A cantilever beam with two different loading conditions, a concentrated load and an evenly distribute load, and truss structure with a concentrated loading condition are implemented to optimize the shape. It gives a good design strategy on the optimal truss structure as well as the optimal cantilever beam shape. It is found that the convergence is quickly finished with the iteration number below ten. Optimized shapes of cantilever beam and truss structure are shown with stress contour plot by the results of the subproblem approximation method and the first order approximation methd.

APPROXIMATION ORDER TO A FUNCTION IN Lp SPACE BY GENERALIZED TRANSLATION NETWORKS

  • HAHM, NAHMWOO;HONG, BUM IL
    • 호남수학학술지
    • /
    • 제28권1호
    • /
    • pp.125-133
    • /
    • 2006
  • We investigate the approximation order to a function in $L_p$[-1, 1] for $0{\leq}p<{\infty}$ by generalized translation networks. In most papers related to neural network approximation, sigmoidal functions are adapted as an activation function. In our research, we choose an infinitely many times continuously differentiable function as an activation function. Using the integral modulus of continuity and the divided difference formula, we get the approximation order to a function in $L_p$[-1, 1].

  • PDF

HIGH ACCURACY POINTS OF WAVELET APPROXIMATION

  • Kwon, Soon-Geol
    • Journal of applied mathematics & informatics
    • /
    • 제27권1_2호
    • /
    • pp.69-78
    • /
    • 2009
  • The accuracy of wavelet approximation at resolution h = $2^{-k}$ to a smooth function f is limited by O($h^M$), where M is the number of vanishing moments of the mother wavelet ${\psi}$; that is, the approximation order of wavelet approximation is M - 1. High accuracy points of wavelet approximation are of interest in some applications such as signal processing and numerical approximation. In this paper, we prove the scaling and translating properties of high accuracy points of wavelet approximation. To illustrate the results in this paper, we also present two examples of high accuracy points of wavelet approximation.

  • PDF

가중치를 고려한 슬라이딩 모드 제어기 설계 (Sliding Mode Controller Design Considering Weight)

  • 임동균;서병설
    • 전력전자학회:학술대회논문집
    • /
    • 전력전자학회 1998년도 연구회 합동 학술발표회 논문집
    • /
    • pp.73-77
    • /
    • 1998
  • The conventional sliding mode controller (SMCr) approach is often impractical or difficult when applied to high order process because the number of tuning parameters in the SMCr increases with the order of the plant. Camacho(1996) proposed the design of a fixed structure sliding mode controller based on a first order plus dead time approximation to the higher-order process. But, there are such problems as overshoot, settling time and command following. They are mainly due to the approximation errors of the time delay term by Taylor series. In this paper, in order to improve Camcho's method, a new Taylor approximation technique considering a weight is proposed.

  • PDF

Routh Approximants with Arbitrary Order

  • Younseok Choo;Kim, Dongmin
    • Transactions on Control, Automation and Systems Engineering
    • /
    • 제1권1호
    • /
    • pp.50-53
    • /
    • 1999
  • It has been pointed out in the literature that the Routh approximation method for order reduction has limitations in treating transfer functions with the denominator-numerator order difference not equal to one. The purpose of this paper is to present a new algorithm based on the Routh approximation method that can be applied to general rational transfer functions, yield ing reduced models with arbitrary order.

  • PDF

NUMERICAL SIMULATION OF THE FRACTIONAL-ORDER CONTROL SYSTEM

  • Cai, X.;Liu, F.
    • Journal of applied mathematics & informatics
    • /
    • 제23권1_2호
    • /
    • pp.229-241
    • /
    • 2007
  • Multi-term fractional differential equations have been used to simulate fractional-order control system. It has been demonstrated the necessity of the such controllers for the more efficient control of fractional-order dynamical system. In this paper, the multi-term fractional ordinary differential equations are transferred into equivalent a system of equations. The existence and uniqueness of the new system are proved. A fractional order difference approximation is constructed by a decoupled technique and fractional-order numerical techniques. The consistence, convergence and stability of the numerical approximation are proved. Finally, some numerical results are presented to demonstrate that the numerical approximation is a computationally efficient method. The new method can be applied to solve the fractional-order control system.

PARAMETRIC APPROXIMATION OF MONOTONE DECREASING SEQUENCE

  • Rhee, Hyang J.
    • 충청수학회지
    • /
    • 제17권1호
    • /
    • pp.77-83
    • /
    • 2004
  • The aim of this work is to generalize parametric approximation in order to apply them to an one-sided $L_1$-approximation. A natural question now arises : when is the parameter map $$P:f{\rightarrow}P_{K(f)}(f)$$ continuous on $C_1(X)$ ? We find some results with a monotone decreasing sequence about above question.

  • PDF

A STUDY OF SIMULTANEOUS APPROXIMATION BY NEURAL NETWORKS

  • Hahm, N.;Hong, B.I.
    • Journal of applied mathematics & informatics
    • /
    • 제26권1_2호
    • /
    • pp.317-324
    • /
    • 2008
  • This paper shows the degree of simultaneous neural network approximation for a target function in $C^r$[-1, 1] and its first derivative. We use the Jackson's theorem for differentiable functions to get a degree of approximation to a target function by algebraic polynomials and trigonometric polynomials. We also make use of the de La Vall$\grave{e}$e Poussin sum to get an approximation order by algebraic polynomials to the derivative of a target function. By showing that the divided difference with a generalized translation network can be arbitrarily closed to algebraic polynomials on [-1, 1], we obtain the degree of simultaneous approximation.

  • PDF

Accuracy Analysis of Optimal Trajectory Planning Methods Based on Function Approximation for a Four-DOF Biped Walking Model

  • Peng Chunye;ONO Kyosuke
    • Journal of Mechanical Science and Technology
    • /
    • 제19권spc1호
    • /
    • pp.452-460
    • /
    • 2005
  • Based on an introduced optimal trajectory planning method, this paper mainly deals with the accuracy analysis during the function approximation process of the optimal trajectory planning method. The basis functions are composed of Hermit polynomials and Fourier series to improve the approximation accuracy. Since the approximation accuracy is affected by the given orders of each basis function, the accuracy of the optimal solution is examined by changing the combinations of the orders of Hermit polynomials and Fourier series as the approximation basis functions. As a result, it is found that the proper approximation basis functions are the $5^{th}$ order Hermit polynomials and the $7^{th}-10^{th}$ order of Fourier series.

Comparing Solution Methods for a Basic RBC Model

  • Joo, Semin
    • Management Science and Financial Engineering
    • /
    • 제21권2호
    • /
    • pp.25-30
    • /
    • 2015
  • This short article compares different solution methods for a basic RBC model (Hansen, 1985). We solve and simulate the model using two main algorithms: the methods of perturbation and projection, respectively. One novelty is that we offer a type of the hybrid method: we compute easily a second-order approximation to decision rules and use that approximation as an initial guess for finding Chebyshev polynomials. We also find that the second-order perturbation method is most competitive in terms of accuracy for standard RBC model.