• Title/Summary/Keyword: fourier series expansion

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SERIES EXPANSIONS OF THE ANALYTIC FEYNMAN INTEGRAL FOR THE FOURIER-TYPE FUNCTIONAL

  • Lee, Il-Yong;Chung, Hyun-Soo;Chang, Seung-Jun
    • The Pure and Applied Mathematics
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    • v.19 no.2
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    • pp.87-102
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    • 2012
  • In this paper, we consider the Fourier-type functionals introduced in [16]. We then establish the analytic Feynman integral for the Fourier-type functionals. Further, we get a series expansion of the analytic Feynman integral for the Fourier-type functional $[{\Delta}^kF]^{\^}$. We conclude by applying our series expansion to several interesting functionals.

FOURIER SERIES OF A DEVIL'S STAIRCASE

  • Kwon, DoYong
    • Honam Mathematical Journal
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    • v.43 no.2
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    • pp.259-267
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    • 2021
  • Given 𝛽 > 1, we consider real numbers whose 𝛽-expansions are Sturmian words. When the slope of Sturmian words varies, their behaviors have been well studied from analytical point of view. The regularity enables us to find the Fourier series expansion, while the singularity at rational slopes yields a new kind of trigonometric series representing 𝜋.

Fourier series expansion method for plated-structures

  • Deng, Jiann-Gang;Cheng, Fu-Ping
    • Structural Engineering and Mechanics
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    • v.8 no.4
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    • pp.343-360
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    • 1999
  • This work applies a structural analysis method based on an analytical solution from the Fourier series which transforms a half-range cosine expansion into a static solution involving plated structures. Two sub-matrices of in-plane and plate-bending problems are also formulated and coupled with the prescribed boundary conditions for these variables, thereby providing a convenient basis for a numerical solution. In addition, the plate connection are introduced by describing the connection between common boundary continuity and equilibrium. Moreover, a simple computation scheme is proposed. Numerical results are then compared with finite element results, demonstrating the numerical scheme's versatility and accuracy.

REMARKS ON KERNEL FOR WAVELET EXPANSIONS IN MULTIDIMENSIONS

  • Shim, Hong-Tae;Kwon, Joong-Sung
    • Journal of applied mathematics & informatics
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    • v.27 no.1_2
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    • pp.419-426
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    • 2009
  • In expansion of function by special basis functions, properties of expansion kernel are very important. In the Fourier series, the series are expressed by the convolution with Dirichlet kernel. We investigate some of properties of kernel in wavelet expansions both in one and higher dimensions.

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A 2D hybrid stress element for improved prediction of the out-of-plane fields using Fourier expansion

  • Feng, M.L.;Dhanasekar, M.;Xiao, Q.Z.
    • Structural Engineering and Mechanics
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    • v.13 no.5
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    • pp.491-504
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    • 2002
  • Recently we formulated a 2D hybrid stress element from the 3D Hellinger-Reissner principle for the analysis of thick bodies that are symmetric to the thickness direction. Polynomials have typically been used for all the displacement and stress fields. Although the element predicted the dominant stress and all displacement fields accurately, its prediction of the out-of-plane shear stresses was affected by the very high order terms used in the polynomials. This paper describes an improved formulation of the 2D element using Fourier series expansion for the out-of-plane displacement and stress fields. Numerical results illustrate that its predictions have markedly improved.

Analysis of Symmetric and Periodic Open Boundary Problem by Coupling of FEM and Fourier Series

  • Kim, Young Sun
    • Journal of Magnetics
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    • v.18 no.2
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    • pp.130-134
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    • 2013
  • Most electrical machines like motor, generator and transformer are symmetric in terms of magnetic field distribution and mechanical structure. In order to analyze these problems effectively, many coupling techniques have been introduced. This paper deals with a coupling scheme for open boundary problem of symmetric and periodic structure. It couples an analytical solution of Fourier series expansion with the standard finite element method. The analytical solution is derived for the magnetic field in the outside of the boundary, and the finite element method is for the magnetic field in the inside with source current and magnetic materials. The main advantage of the proposed method is that it retains sparsity and symmetry of system matrix like the standard FEM and it can also be easily applied to symmetric and periodic problems. Also, unknowns of finite elements at the boundary are coupled with Fourier series coefficients. The boundary conditions are used to derive a coupled system equation expressed in matrix form. The proposed algorithm is validated using a test model of a bush bar for the power supply. And the each result is compared with analytical solution respectively.

Fourier Series Expansion Method for Free Vibration Analysis of a Fully Liquid-Filled Circular Cylindrical Shell (Fourier 급수전개를 이용한 유체로 가득 채워진 원통형 셸의 고유진동 해석)

  • 정경훈;이성철
    • Journal of KSNVE
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    • v.4 no.2
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    • pp.137-146
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    • 1994
  • An analytical method for linear free vibration of fully liquid-filled circular cylindrical shell with various boundary conditions is developed by the Fourier series expansion based on the Stokes' transformation. A set of modal displacement functions and their derivatives of a circular cylindrical shell is substituted into the Sanders' shell equations in order to explicitily represent the Fourier coefficients as functions of the end point displacements, forces, and moments. For the vibration relevant to the liquid motion, the velocity potential of liquid is assumed as a sum of linear combination of suitable harmonic functions in the axial directions. The unknown parameter of the velocity potential is selected to satisfy the boundary condition along the wetted shell surface. An explicit expression of the natural frequency equation can be obtained for any kind of classical boundary conditions. The natural frequencies of the liquid-filled cylindrical shells with the clamped-free, the clamped-clamped, and the simply supported-simply supported boundary conditions examined in the previous works, are obtained by the analytical method. The results are compared with the previous works, and excellent agreement is found for the natural frequencies of the shells.

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Free Vibration Analysis of a Circular Plate Submerged in a Fluid-filled Rigid Cylinder (유체로 채워진 강체 실린더에 잠긴 원판의 고유진동 해석)

  • Jeong, Kyeong-Hoon;Choi, Suhn;Jhung, Myung-Jo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.921-925
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    • 2003
  • An analytical method for the free vibration of single circular plate submerged in a fluid-filled rigid cylindrical vessel was developed by the Rayleigh-Ritz method based on the Fourier-Bessel series expansion. It was assumed that the plate is clamped at an offcentered location of the cylinder, and the non-viscous incompressible fluid contained in the cylinder is bisected by the plate. It was found that the theoretical results can predict well the fluid-coupled natural frequencies with excellent accuracy comparing with the finite element analysis results. The offcentered distance effect on the natural frequencies was also observed.

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A study on torque shaping method for slewing and vibration suppression of flexible structures (유연우주비행체의 선회 및 진동억제를 위한 Torque Shaping 기법에 관한 연구)

  • 문종윤;석진영;김유단
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1087-1090
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    • 1996
  • The objective of this paper is to present a new input torque shaping method for slewing and vibration suppression of flexible structure based on Fourier series expansion. Vibration energy of the structure with shaped control input is investigated with respect to the shaping parameter of the reference torque, maneuver time and the number of trigonometric functions to be included in the series. Analytic expressions of the performance indices and their derivatives are derived in the modal coordinates. Numerical results show the effectiveness of the proposed approach to design the open-loop control law that modifies the shape of input torque for simultaneous slewing and vibration suppression.

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Natural vibration analysis of coaxial shells coupled with fluid

  • Jhung, Myung Jo;Choi, Young Hwan;Jeong, Kyeong Hoon
    • Structural Engineering and Mechanics
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    • v.16 no.6
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    • pp.655-674
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    • 2003
  • Investigated in this study are the natural vibration characteristics of the coaxial cylindrical shells coupled with a fluid. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier series expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of the fluid-filled annulus and the boundary conditions on the modal characteristics of the coaxial shells is investigated using a finite element modeling.