• Title/Summary/Keyword: non-affine

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An Adaptive M-estimators Robust Estimation Algorithm (적응적 M-estimators 강건 예측 알고리즘)

  • Jang Seok-Woo;Kim Jin-Uk
    • Journal of the Korea Society of Computer and Information
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    • v.10 no.2 s.34
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    • pp.21-30
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    • 2005
  • In general, the robust estimation method is well known for a good statistical estimator that is insensitive to small departures from the idealized assumptions for which the estimation is optimized. While there are many existing robust estimation techniques that have been proposed in the literature, two main techniques used in computer vision are M-estimators and least-median of squares (LMS). Among these. we utilized the M-estimators since they are known to provide an optimal estimation of affine motion parameters. The M-estimators have higher statistical efficiency but tolerate much lower percentages of outliers unless properly initialized. To resolve these problems, we proposed an adaptive M-estimators algorithm that effectively separates outliers from non-outliers and estimate affine model parameters, using a continuous sigmoid weight function. The experimental results show the superiority of our method.

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Discrete Representation Method of Nonlinear Time-Delay System in Control

  • Park, Ji-Hyang;Chong, Kil-To
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.327-332
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    • 2003
  • A new discretization method for nonlinear system with time-delay is proposed. It is based on the well-known Taylor series expansion and the zero-order hold (ZOH) assumption. We know that a discretization of linear system can be obtained with the ZOH assumption and within the sampling interval. A similar line of thinking is available in nonlinear case. The mathematical structure of the new discretization method is explored and under the structure, the sampled-data representation of nonlinear system including time-delay is computed. Provided that the discrete form of the single input nonlinear system with time-delay is derived, this result is easily extended to nonlinear system with multi-input time-delay. For simplicity two inputs are considered in this study. It is enough to generalize that of multiple inputs. Finally, the time-discretization of non-affine nonlinear system with time-delay is investigated for apply all nonlinear system

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Enhanced Pseudo Affine Projection Algorithm with Variable Step-size (가변 스텝 사이즈를 이용한 개선된 의사 인접 투사 알고리즘)

  • Chung, Ik-Joo
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.2
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    • pp.79-86
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    • 2012
  • In this paper, we propose an enhanced algorithm for affine projection algorithms which have been proposed to speed up the convergence of the conventional NLMS algorithm. Since affine projection (AP) or pseudo AP algorithms are based on the delayed input vector and error vector, they are complicated and not suitable for applying methods developed for the LMS-type algorithms which are based on the scalar error signal. We devised a variable step size algorithm for pseudo AP using the fact that pseudo AP algorithms are updated using the scalar error and that the error signal is getting orthogonal to the input signal. We carried out a performance comparison of the proposed algorithm with other pseudo AP algorithms using a system identification model. It is shown that the proposed algorithm presents good convergence characteristics under both stationary and non-stationary environments despites its low complexity.

Linearity Enhancement of RF Power Amplifier Using Digital Pre-Distortion Based on Affine Projection Algorithm (Affine Projection 알고리즘에 기초하여 구현한 디지털 전치왜곡을 이용한 RF 전력증폭기의 선형성 향상)

  • Seong, Yeon-Jung;Cho, Choon-Sik;Lee, Jae-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.4
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    • pp.484-490
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    • 2012
  • In this paper, we design a digitally pre-distorted RF power amplifier operating in 900 MHz band. The linearity of RF power amplifier is improved by employing the digital pre-distortion(DPD) based on affine projection(AP) algorithm, where the look-up table(LUT) method is used with non-linear indexing. The proposed DPD with AP algorithm is compared with that with normalized least mean square(NLMS) algorithm, applied to the RF power amplifier. A commercial power amplifier module is used for verification of the proposed algorithm which shows improvement of adjacent channel leakage ratio(ACLR) by about 21 dB.

A Robust Algorithm for Tracking Non-rigid Objects Using Deformed Template and Level-Set Theory (템플릿 변형과 Level-Set이론을 이용한 비강성 객체 추적 알고리즘)

  • 김종렬;나현태;문영식
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.40 no.3
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    • pp.127-136
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    • 2003
  • In this paper, we propose a robust object tracking algorithm based on model and edge, using deformed template and Level-Set theory. The proposed algorithm can track objects in case of background variation, object flexibility and occlusions. First we design a new potential difference energy function(PDEF) composed of two terms including inter-region distance and edge values. This function is utilized to estimate and refine the object shape. The first step is to approximately estimate the shape and location of template object based on the assumption that the object changes its shape according to the affine transform. The second step is a refinement of the object shape to fit into the real object accurately, by using the potential energy map and the modified Level-Set speed function. The experimental results show that the proposed algorithm can track non-rigid objects under various environments, such as largely flexible objects, objects with large variation in the backgrounds, and occluded objects.

ZEEMAN'S THEOREM IN NONDECOMPOSABLE SPACES

  • Duma, Adrian
    • Journal of the Korean Mathematical Society
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    • v.34 no.2
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    • pp.265-277
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    • 1997
  • Let E be a real, non-degenerate, indefinite inner product space with dim $E \geq 3$. It is shown that any bijection of E which preserves the light cones is an affine map.

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Microcontacting behaviour of material with fractal rough surface (프랙탈 표면을 가진 공구와 재료의 마이크로 접촉거동해석)

  • Kim, Young-Suk;Hyun, Sang-Il
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.33-37
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    • 2009
  • Finite-element methods are used to study non-adhesive, frictionless rough contact of elastic and plastic solids. Roughness on spherical surfaces is realized by self-affine fractal. True contact area between the rough surfaces and flat rigid surfaces increases with power law under external normal loads. The power exponent is sensitive to surface roughness as well as the curvature of spherical geometry. Surface contact pressures are analyzed and compared for the elastic and plastic solids. Distributions of local contact pressure are shown dependent on the surface roughness and the yield stress of plastic solids.

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A Study on Projection Properties of the 12-Run Plackett-Burman Design

  • Park, Dong-Kwon
    • Communications for Statistical Applications and Methods
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    • v.6 no.3
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    • pp.707-718
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    • 1999
  • Non-regular designs such as the Plackett-Burman(PB) design have traditionally been used for screening only main effects because of complex aliasing. But it was found that these designs could be used to estimate the 2-factor interactions as well as main effects through the hidden projection property. The goal of this paper is to propose the estimable model when projecting the 12-run PB design using the algebraic geometric method. The core of this method considers the design as a affine variety and the Grbner basis of the design ideal for this affine variety gives the estimable polynomial models. As the results of applying the 12-run PB design it is actually found that this design has the models not only with 2-factor interactions but with 3-factor. This design is the maximal fan in 4-factor projection.

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(Robust Non-fragile $H^\infty$ Controller Design for Parameter Uncertain Systems) (파라미터 불확실성 시스템에 대한 견실 비약성 $H^\infty$ 제어기 설계)

  • Jo, Sang-Hyeon;Kim, Gi-Tae;Park, Hong-Bae
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.39 no.3
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    • pp.183-190
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    • 2002
  • This paper describes the synthesis of robust and non-fragile H$\infty$ state feedback controllers for linear varying systems with affine parameter uncertainties, and static state feedback controller with structured uncertainty. The sufficient condition of controller existence, the design method of robust and non-fragile H$\infty$ static state feedback controller, and the set of controllers which satisfies non-fragility are presented. The obtained condition can be rewritten as parameterized Linear Matrix Inequalities(PLMls), that is, LMIs whose coefficients are functions of a parameter confined to a compact set. However, in contrast to LMIs, PLMIs feasibility problems involve infinitely many LMIs hence are inherently difficult to solve numerically. Therefore PLMls are transformed into standard LMI problems using relaxation techniques relying on separated convexity concepts. We show that the resulting controller guarantees the asymptotic stability and disturbance attenuation of the closed loop system in spite of controller gain variations within a degree.