• Title/Summary/Keyword: Taylor expansion

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Efficient Technique of Motion Vector Re-estimation in Transcoding (트랜스 코딩에서의 효율적인 움직임 벡터 재추정 기법 연구)

  • 한두진;박강서;유희준;김봉곤;박상희
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.8
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    • pp.602-605
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    • 2004
  • A novel motion vector re-estimation technique for transcoding into lower spatial resolution is proposed. This technique is based on the fact that the block matching error is proportional to the complexity of the reference block with Taylor series expansion. It is shown that the motion vectors re-estimated by the proposed method are closer to optimal ones and offer better quality than those of previous techniques.

Dynamic Algorithm for Solid Problems using MLS Difference Method (MLS 차분법을 이용한 고체역학 문제의 동적해석)

  • Yoon, Young-Cheol;Kim, Kyeong-Hwan;Lee, Sang-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.2
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    • pp.139-148
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    • 2012
  • The MLS(Moving Least Squares) Difference Method is a numerical scheme that combines the MLS method of Meshfree method and Taylor expansion involving not numerical quadrature or mesh structure but only nodes. This paper presents an dynamic algorithm of MLS difference method for solving transient solid mechanics problems. The developed algorithm performs time integration by using Newmark method and directly discretizes strong forms. It is very convenient to increase the order of Taylor polynomial because derivative approximations are obtained by the Taylor series expanded by MLS method without real differentiation. The accuracy and efficiency of the dynamic algorithm are verified through numerical experiments. Numerical results converge very well to the closed-form solutions and show less oscillation and periodic error than FEM(Finite Element Method).

Non-statistical Stochastic Finite Element Method Employing Higher Order Stochastic Field Function (고차의 추계장 함수와 이를 이용한 비통계학적 추계론적 유한요소해석)

  • Noh, Hyuk-Chun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.2A
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    • pp.383-390
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    • 2006
  • In this paper, a stochastic field that is compatible with Monte Carlo simulation is suggested for an expansion-based stochastic analysis scheme of weighted integral method. Through investigation on the way of affection of stochastic field function on the displacement vector in the series expansion scheme, it is noticed that the stochastic field adopted in the weighted integral method is not compatible with that appears in the Monte Carlo simulation. As generally recognized in the field of stochastic mechanics, the response variability is not a linear function of the coefficient of variation of stochastic field but a nonlinear function with increasing variability as the intensity of uncertainty is increased. Employing the stochastic field suggested in this study, the response variability evaluated by means of the weighted integral scheme is reproduced with high precision even for uncertain fields with moderately large coefficient of variation. Besides, despite the fact that only the first-order expansion is employed, an outstanding agreement between the results of expansion-based weighted integral method and Monte Carlo simulation is achieved.

Taylor Series Discretization Method for Input-Delay Nonlinear Systems

  • Zhang, Zheng;Chong, Kil-To
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.152-154
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    • 2007
  • Anew discretization method for the input-driven nonlinear continuous-time system with time delay is proposed. It is based on the combination of Taylor series expansion and first-order hold assumption. The mathematical structure of the new discretization scheme is explored. The performance of the proposed discretization procedure is evaluated by case studies. The results demonstrate that the proposed discretization scheme can assure the system requirements even though under a large sampling period. A comparison between first order hold and zero-order hold is simulated also.

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A Gridless Finite Difference Method for Elastic Crack Analysis (탄성균열해석을 위한 그리드 없는 유한차분법)

  • Yoon, Young-Cheol;Kim, Dong-Jo;Lee, Sang-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.3
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    • pp.321-327
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    • 2007
  • This study presents a new gridless finite difference method for solving elastic crack problems. The method constructs the Taylor expansion based on the MLS(Moving Least Squares) method and effectively calculates the approximation and its derivatives without differentiation process. Since no connectivity between nodes is required, the modeling of discontinuity embedded in the domain is very convenient and discontinuity effect due to crack is naturally implemented in the construction of difference equations. Direct discretization of the governing partial differential equations makes solution process faster than other numerical schemes using numerical integration. Numerical results for mode I and II crack problems demonstrates that the proposed method accurately and efficiently evaluates the stress intensity factors.

Discretization of Nonlinear Systems with Delayed Multi-Input VIa Taylor Series and Scaling and Squaring Technique

  • Yuanliang Zhang;Chong Kil To
    • Journal of Mechanical Science and Technology
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    • v.19 no.11
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    • pp.1975-1987
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    • 2005
  • An input time delay always exists in practical systems. Analysis of the delay phenomenon in a continuous-time domain is sophisticated. It is appropriate to obtain its corresponding discrete-time model for implementation via digital computers. In this paper a new scheme for the discretization of nonlinear systems using Taylor series expansion and the zero-order hold assumption is proposed. The mathematical structure of the new discretization method is analyzed. On the basis of this structure the sampled-data representation of nonlinear systems with time-delayed multi-input is presented. The delayed multi-input general equation has been derived. In particular, the effect of the time-discretization method on key properties of nonlinear control systems, such as equilibrium properties and asymptotic stability, is examined. Additionally, hybrid discretization schemes that result from a combination of the scaling and squaring technique (SST) with the Taylor series expansion are also proposed, especially under conditions of very low sampling rates. Practical issues associated with the selection of the method's parameters to meet CPU time and accuracy requirements, are examined as well. A performance of the proposed method is evaluated using a nonlinear system with time delay maneuvering an automobile.

Analytical Solution for Long Waves on Axis-Symmetric Topographies (축 대칭 지형 위를 전파하는 장파의 해석해)

  • Jung, Tae-Hwa;Lee, Changhoon;Cho, Yong-Sik;Lee, Jin-Woo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4B
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    • pp.413-419
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    • 2008
  • In this study, we develop analytical solutions for long waves propagating over several types of axis-symmetric topographies where the water depth varies in an arbitrary power of radial distance. The first type is a cylindrical island mounted on a shoal. The second type is a circular island. To get the solution, the methods of separation of variables, Taylor series expansion and Frobenius series are used. Developed analytical solutions are validated by comparing with previously developed analytical solutions. We also investigate various cases with different incident wave periods, radii of the shoal, and the powers of radial distance.

Implementation of Efficient Exponential Function Approximation Algorithm Using Format Converter Based on Floating Point Operation in FPGA (부동소수점 기반의 포맷 컨버터를 이용한 효율적인 지수 함수 근사화 알고리즘의 FPGA 구현)

  • Kim, Jeong-Seob;Jung, Seul
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.11
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    • pp.1137-1143
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    • 2009
  • This paper presents the FPGA implementation of efficient algorithms for approximating exponential function based on floating point format data. The Taylor-Maclaurin expansion as a conventional approximation method becomes inefficient since high order expansion is required for the large number to satisfy the approximation error. A format converter is designed to convert fixed data format to floating data format, and then the real number is separated into two fields, an integer field and an exponent field to separately perform mathematic operations. A new assembly command is designed and added to previously developed command set to refer the math table. To test the proposed algorithm, assembly program has been developed. The program is downloaded into the Altera DSP KIT W/STRATIX II EP2S180N Board. Performances of the proposed method are compared with those of the Taylor-Maclaurin expansion.