• 제목/요약/키워드: One Equation Method

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부등류조건에서 종확산방정식의 Eulerian-Lagrangian 모형 (Eulerian-Lagrangian Modeling of One-Dimensional Dispersion Equation in Nonuniform Flow)

  • 김대근;서일원
    • 한국환경과학회지
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    • 제11권9호
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    • pp.907-914
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    • 2002
  • Various Eulerian-Lagrangian models for the one-dimensional longitudinal dispersion equation in nonuniform flow were studied comparatively. In the models studied, the transport equation was decoupled into two component parts by the operator-splitting approach; one part is governing advection and the other is governing dispersion. The advection equation has been solved by using the method of characteristics following fluid particles along the characteristic line and the results were interpolated onto an Eulerian grid on which the dispersion equation was solved by Crank-Nicholson type finite difference method. In the solution of the advection equation, Lagrange fifth, cubic spline, Hermite third and fifth interpolating polynomials were tested by numerical experiment and theoretical error analysis. Among these, Hermite interpolating polynomials are generally superior to Lagrange and cubic spline interpolating polynomials in reducing both dissipation and dispersion errors.

Numerical Modeling of One-Dimensional Longitudinal Dispersion Equation using Eulerian Method

  • Seo, Il-Won;Kim, Dae-Geun
    • Korean Journal of Hydrosciences
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    • 제6권
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    • pp.51-66
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    • 1995
  • Various Eulerian-Lagerangian numerical models for the one-dimensional longtudinal dispersion equation are studied comparatively. In the models studied, the transport equation is decoupled into two component parts by the operator-splitting approach ; one part governing advection and the other dispersion. The advection equation has been solved using the method of characteristics following flud particles along the characteristic line and the result are interpolated onto an Eulerian grid on which the dispersion equation is solved by Crank-Nicholson type finite difference method. In solving the advection equation, various interpolation schemes are tested. Among those, Hermite interpo;ation po;ynomials are superor to Lagrange interpolation polynomials in reducing both dissipation and dispersion errors.

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선로조류 감도계수를 고려한 전압안정도 평가에 관한 연구 (A Study on Evaluating of Voltage Stability Considering Line Flow Sensitivity)

  • 김세영;최상규;송길영
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 하계학술대회 논문집 D
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    • pp.1118-1120
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    • 1997
  • This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations ($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these becomes one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack or generater bus, which is specified voltage magnitude, it becomes one equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, multiple load flow solutions may be obtained with simple computation, and the formulated equation used for approximately evaluating of voltage stability limit considering line flow sensitivity. The proposed method was validated to 2-bus and IEEE 6-bus system.

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자동차 충돌해석에 의한 단순화된 차체 강성 방정식의 유도 (The Derivation of Simplified Vehicle Body Stiffness Equation Using Collision Analysis)

  • 장인식;채덕병
    • 한국자동차공학회논문집
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    • 제8권4호
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    • pp.177-185
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    • 2000
  • The deformation characteristics is one of the major factors to resume the crash configuration in collision accident reconstruction. Crash analysis are carried out using finite element method and body stiffness equations representing force-deformation relationship are derived, Two different crash conditions : 1) frontal barrier impact 2) frontal impact between cars are given for the derivation of the equations. The stiffness coefficient of equation by method 2) is larger than that by method. 1). Crash analysis between two vehicles is accomplished with three crash angles and three velocities for each angle condition. The deformations are measured for six selected points and deformation energies are calculated using the derived equations. Equation by method 2) results in better estimation of deformation energy than that by method 1) for all crush configurations. The estimated energies can be utilized as one of indices to identify the type of the collision accident result.

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WKB 방법에 의한 일차원 완경사 파랑식의 해석해 (An Analytical Solution of One Dimensional Mild Slope Equation by the WKB method)

  • 서승남
    • 한국해안·해양공학회논문집
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    • 제20권5호
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    • pp.461-471
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    • 2008
  • WKB 방법에 의한 일차원 완경사 파랑식의 해석해를 유도하였고 이는 Porter(2003)의 해와 유사한 형태를 갖는다. 적용적 측면에서 본 해석해는 관련 수치해에 견줄 만큼 해석상의 일반성을 갖는다. 유도과정에서 해면함수로 표현된 굴절 방정식의 해도 얻었다. Bremmer 방법을 이용한 본 해석해에 대한 수치계산 결과를 제시하였고 이들은 기존 결과와 일치한다.

Eulerian-Lagrangian 방법을 이용한 1차원 종확산방정식의 수치모형 (Numerical Modeling of One-Dimensional Longitudinal Dispersion Equation using Eulerian-Lagrangian Method)

  • 서일원;김대근
    • 물과 미래
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    • 제27권2호
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    • pp.155-166
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    • 1994
  • Eulerian-Lagrangian 방법을 이용하여 1차원 종확산방정식의 수치모형을 비교·분석하였다. 본 연구에서서 비교·분석한 모형은 지배방정식을 연산자 분리방법에 의해서 이송만을 지배하는 이송방정식과 확산만을 지배하는 확산방정식으로 분리한다. 이송방정식은 특성곡선을 따라서 유체입자를 추적하는 특성곡선법을 사용하여 해를 구하고, 그 결과를 고정된 Eulerian 격자상에 보간하였고, 확산방정식은 상기 고정격자상에서 Crank-Nicholson 유한차분법을 사용하여 해를 구하였다. 이송방정식의 풀이에서 다양한 보간방법이 적용되었는데, 일반적으로 Hermite 보간다항식을 사용한 경우가 Lagrange 보간다항식을 사용한 경우보다 수치확산 및 수치진동 등의 오차를 최소화할 수 있어서 더욱 우수한 것으로 밝혀졌다.

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Comparison of different iterative schemes for ISPH based on Rankine source solution

  • Zheng, Xing;Ma, Qing-wei;Duan, Wen-yang
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제9권4호
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    • pp.390-403
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    • 2017
  • Smoothed Particle Hydrodynamics (SPH) method has a good adaptability for the simulation of free surface flow problems. There are two forms of SPH. One is weak compressible SPH and the other one is incompressible SPH (ISPH). Compared with the former one, ISPH method performs better in many cases. ISPH based on Rankine source solution can perform better than traditional ISPH, as it can use larger stepping length by avoiding the second order derivative in pressure Poisson equation. However, ISPH_R method needs to solve the sparse linear matrix for pressure Poisson equation, which is one of the most expensive parts during one time stepping calculation. Iterative methods are normally used for solving Poisson equation with large particle numbers. However, there are many iterative methods available and the question for using which one is still open. In this paper, three iterative methods, CGS, Bi-CGstab and GMRES are compared, which are suitable and typical for large unsymmetrical sparse matrix solutions. According to the numerical tests on different cases, still water test, dam breaking, violent tank sloshing, solitary wave slamming, the GMRES method is more efficient than CGS and Bi-CGstab for ISPH method.

SOLVING FUZZY FRACTIONAL WAVE EQUATION BY THE VARIATIONAL ITERATION METHOD IN FLUID MECHANICS

  • KHAN, FIRDOUS;GHADLE, KIRTIWANT P.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제23권4호
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    • pp.381-394
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    • 2019
  • In this paper, we are extending fractional partial differential equations to fuzzy fractional partial differential equation under Riemann-Liouville and Caputo fractional derivatives, namely Variational iteration methods, and this method have applied to the fuzzy fractional wave equation with initial conditions as in fuzzy. It is explained by one and two-dimensional wave equations with suitable fuzzy initial conditions.

A STUDY ON THE EFFECTIVE ALGORITHMS BASED ON THE WEGMANN'S METHOD

  • Song, Eun-Jee
    • Journal of applied mathematics & informatics
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    • 제20권1_2호
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    • pp.595-602
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    • 2006
  • Determinations of conformal map from the unit disk onto a Jordan region are reduced to solve the Theodorsen equation which is an integral equation for the boundary correspondence function. Among numerical conformal maps the Wegmann's method is well known as a Newton efficient one for solving Theodorsen equation. However this method has not so wide class of convergence. We proposed as an improved method for convergence by applying a low frequency filter to the Wegmann's method. In this paper, we investigate error analysis and propose an automatic algorithm based on this analysis.

선로조류방정식 특성을 이용한 전압안정도 평가에 관한 연구 (A Study on Evaluating of Voltage Stability Using the Line Flow Equation.)

  • 송길영;김세영;김용하
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1996년도 하계학술대회 논문집 B
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    • pp.797-799
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    • 1996
  • This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these equations become one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack bus or generator bus, which is specified voltage magnitude, it becomes One equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, solutions are obtained with simple computation. Solutions obtained are used for evaluating of voltage stability through sensitivity analysis. Also, considering of reactive power source, method for evaluating the voltage stability is introduced. The proposed method was validated to 2-bus and IEEE 6-bus system.

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