• Title/Summary/Keyword: hyperbolic matrix

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Global Sliding Mode Control based on a Hyperbolic Tangent Function for Matrix Rectifier

  • Hu, Zhanhu;Hu, Wang;Wang, Zhiping;Mao, Yunshou;Hei, Chenyang
    • Journal of Power Electronics
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    • v.17 no.4
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    • pp.991-1003
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    • 2017
  • The conventional sliding mode control (CSMC) has a number of problems. It may cause dc output voltage ripple and it cannot guarantee the robustness of the whole system for a matrix rectifier (MR). Furthermore, the existence of a filter can decrease the input power factor (IPF). Therefore, a novel global sliding mode control (GSMC) based on a hyperbolic tangent function with IPF compensation for MRs is proposed in this paper. Firstly, due to the reachability and existence of the sliding mode, the condition of the matrix rectifier's robustness and chattering elimination is derived. Secondly, a global switching function is designed and the determination of the transient operation status is given. Then a SMC compensation strategy based on a DQ transformation model is applied to compensate the decreasing IPF. Finally, simulations and experiments are carried out to verify the correctness and effectiveness of the control algorithm. The obtained results show that compared with CSMC, applying the proposed GSMC based on a hyperbolic tangent function for matrix rectifiers can achieve a ripple-free output voltage with a unity IPF. In addition, the rectifier has an excellent robust performance at all times.

DISCRETE CONDITIONS FOR THE HOLONOMY GROUP OF A PAIR OF PANTS

  • Kim, Hong-Chan
    • Journal of the Korean Mathematical Society
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    • v.44 no.3
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    • pp.615-626
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    • 2007
  • A pair of pants $\sum(0,\;3)$ is a building block of oriented surfaces. The purpose of this paper is to determine the discrete conditions for the holonomy group $\pi$ of hyperbolic structure of a pair of pants. For this goal, we classify the relations between the locations of principal lines and entries of hyperbolic matrices in $\mathbf{PSL}(2,\;\mathbb{R})$. In the level of the matrix group $\mathbf{SL}(2,\;\mathbb{R})$, we will show that the signs of traces of hyperbolic elements playa very important role to determine the discreteness of holonomy group of a pair of pants.

A NOTE ON THE RANK 2 SYMMETRIC HYPERBOLIC KAC-MOODY ALGEBRAS

  • Kim, Yeon-Ok
    • The Pure and Applied Mathematics
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    • v.17 no.1
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    • pp.107-113
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    • 2010
  • In this paper, we study the root system of rank 2 symmetric hyperbolic Kac-Moody algebras. We give the sufficient conditions for existence of imaginary roots of square length -2k ($k\;{\in}\;\mathbb{Z}$>0). We also give several relations between the roots on g(A).

IDEAL RIGHT-ANGLED PENTAGONS IN HYPERBOLIC 4-SPACE

  • Kim, Youngju;Tan, Ser Peow
    • Journal of the Korean Mathematical Society
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    • v.56 no.4
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    • pp.1131-1158
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    • 2019
  • An ideal right-angled pentagon in hyperbolic 4-space ${\mathbb{H}}^4$ is a sequence of oriented geodesics ($L_1,{\ldots},L_5$) such that $L_i$ intersects $L_{i+1},i=1,{\ldots},4$, perpendicularly in ${\mathbb{H}}^4$ and the initial point of $L_1$ coincides with the endpoint of $L_5$ in the boundary at infinity ${\partial}{\mathbb{H}}^4$. We study the geometry of such pentagons and the various possible augmentations and prove identities for the associated quaternion half side lengths as well as other geometrically defined invariants of the configurations. As applications we look at two-generator groups ${\langle}A,B{\rangle}$ of isometries acting on hyperbolic 4-space such that A is parabolic, while B and AB are loxodromic.

IDEAL RIGHT-ANGLED PENTAGONS IN HYPERBOLIC 4-SPACE

  • Kim, Youngju;Tan, Ser Peow
    • Journal of the Korean Mathematical Society
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    • v.56 no.3
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    • pp.595-622
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    • 2019
  • An ideal right-angled pentagon in hyperbolic 4-space ${\mathbb{H}}^4$ is a sequence of oriented geodesics ($L_1,{\ldots},L_5$) such that Li intersects $L_{i+1},\;i=1,\;{\ldots},\;4$, perpendicularly in ${\mathbb{H}}^4$ and the initial point of $L_1$ coincides with the endpoint of $L_5$ in the boundary at infinity ${\partial}{\mathbb{H}}^4$. We study the geometry of such pentagons and the various possible augmentations and prove identities for the associated quaternion half side lengths as well as other geometrically defined invariants of the configurations. As applications we look at two-generator groups ${\langle}A,B{\rangle}$ of isometries acting on hyperbolic 4-space such that A is parabolic, while B and AB are loxodromic.

MATRIX PRESENTATIONS OF THE TEICHMULLER SPACE OF A PUNCTURED TORUS

  • Kim, Hong-Chan
    • The Pure and Applied Mathematics
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    • v.11 no.1
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    • pp.73-88
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    • 2004
  • A punctured torus $\Sigma(1,1)$ is a building block of oriented surfaces. The goal of this paper is to formulate the matrix presentations of elements of the Teichmuller space of a punctured torus. Let $\cal{C}$ be a matrix presentation of the boundary component of $\Sigma(1,1)$.In the level of the matrix group $\mathbb{SL}$($\mathbb2,R$) we shall show that the trace of $\cal{C}$ is always negative.

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MATRIX PRESENTATIONS OF THE TEICHMÜLLER SPACE OF A PAIR OF PANTS

  • KIM HONG CHAN
    • Journal of the Korean Mathematical Society
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    • v.42 no.3
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    • pp.555-571
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    • 2005
  • A pair of pants $\Sigma(0,3)$ is a building block of oriented surfaces. The purpose of this paper is to formulate the matrix presentations of elements of the Teichmuller space of a pair of pants. In the level of the matrix group $SL(2,\mathbb{R})$, we shall show that an odd number of traces of matrix presentations of the generators of the fundamental group of $\Sigma(0,3)$ should be negative.

Implementation of Blind Source Recovery Using the Gini Coefficient (Gini 계수를 이용한 Blind Source Recovery 방법의 구현)

  • Jeong, Jae-Woong;Song, Eun-Jung;Park, Young-Cheol;Youn, Dae-Hee
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.1
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    • pp.26-32
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    • 2008
  • UBSS (unde-determined blind source separation) is composed of the stages of BMMR (blind mixing matrix recovery) and BSR (blind source recovery). Generally, these two stages are executed using the sparseness of the observed data, and their performance is influenced by the accuracy of the measure of the sparseness. In this paper, as introducing the measure of the sparseness using the Gini coefficient to BSR stage, we obtained more accurate measure of the sparseness and better performance of BSR than methods using the $l_1$-norm, $l_q$-norm, and hyperbolic tangent, which was confirmed via computer simulations.