The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Cheng-de Zheng - One of the best experts on this subject based on the ideXlab platform.
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Generalized Homogeneous Multivariate Matrix PadÉ-Type Approximants and PadÉ Approximants
IEEE Transactions on Automatic Control, 2007Co-Authors: Cheng-de Zheng, Huaguang Zhang, Hong TianAbstract:Generalized homogeneous multivariate matrix Pade-type Approximants (GHMPTA) and Pade Approximants are studied in ways similar to those of Brezinski and Kida in the scalar cases. By choosing an arbitrary monic bivariate scalar polynomial from the triangular form as the generating one of the Approximant, we discuss their several typical important properties and study the connection between generalized homogeneous bivariate matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can be extended directly to the case of d variables (d ges 2).
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Generalized Multivariate Rectangular Matrix PadÉ-Type Approximants
IEEE Transactions on Circuits and Systems I: Regular Papers, 2007Co-Authors: Cheng-de Zheng, Huaguang ZhangAbstract:A new method for the construction of generalized multivariate rectangular matrix Pade-type Approximants on a rectangular grid is introduced in this paper, by choosing an arbitrary monic bivariate polynomial as the generating one of the Approximant. We discuss their several typical important properties and study the connection between bivariate rectangular matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can extend directly to the case of d variables (d ges 2).
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Generalized multivariate matrix Pade Approximants
2006 8th international Conference on Signal Processing, 2006Co-Authors: Cheng-de ZhengAbstract:In this paper, we present generalized multivariate rectangular matrix Pade-type Approximants and Pade Approximants by the similar ways to those of Brezinski and Kida in the scalar cases. By choosing an arbitrary monic bivariate scalar polynomial from the triangular form as the generating one of the Approximant, we discuss their several typical important properties and studies the connection between generalized bivariate rectangular matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can extend directly to the case of d variables (d
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On multivariate matrix Pade-type Approximants
2006 CIE International Conference on Radar, 2006Co-Authors: Cheng-de ZhengAbstract:Following naturally the same ways as Brezinski developed in the scalar case and Draux in the matrix scale, the author constructs a kind of generalized multivariate rectangular matrix Pade-type Approximants on a rectangular grid, choosing an arbitrary monic bivariate polynomial as the generating one of the Approximant, discusses their several typical important properties and studies the connec-tion between generalized bivariate rectangular matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can extend directly to the case of d variables (d>2).
T Kamiyama - One of the best experts on this subject based on the ideXlab platform.
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contribution of local atomic arrangements and electronic structure to high electrical resistivity in the al_ 82 6 x re_ 17 4 si_x 7 x 12 1 1 1 1 1 1 Approximant
Physical Review B, 2003Co-Authors: T Takeuchi, T Onogi, Toshio Otagiri, Uichiro Mizutani, H Sato, K Kato, T KamiyamaAbstract:Electrical resistivity of ${\mathrm{Al}}_{82.6\ensuremath{-}x}{\mathrm{Re}}_{17.4}{\mathrm{Si}}_{x}$ $(7l~xl~12)$ 1/1-1/1-1/1 Approximants was discussed in terms of their electronic structure near the Fermi level and the local atomic arrangements. Strong composition dependence of the electrical resistivity was observed for these 1/1-1/1/-1/1 Approximants; samples with $x=7,$ 9, and 12 show the Boltzmann-type electrical resistivity, while the others possess behaviors expected for system under the weak-localization. We found that the weak localization effect in the electrical resistivity, which is one of the characteristics of the corresponding Al-based quasicrystals, appears only when a condition of very low density of states with imperfections in the periodicity is satisfied. The Boltzmann-type behavior, on the other hand, takes place when one of the two factors, the very low density of states or the imperfection in the periodicity, is absent from the structure of the 1/1-1/1-1/1 Approximant.
Huaguang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Generalized Homogeneous Multivariate Matrix PadÉ-Type Approximants and PadÉ Approximants
IEEE Transactions on Automatic Control, 2007Co-Authors: Cheng-de Zheng, Huaguang Zhang, Hong TianAbstract:Generalized homogeneous multivariate matrix Pade-type Approximants (GHMPTA) and Pade Approximants are studied in ways similar to those of Brezinski and Kida in the scalar cases. By choosing an arbitrary monic bivariate scalar polynomial from the triangular form as the generating one of the Approximant, we discuss their several typical important properties and study the connection between generalized homogeneous bivariate matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can be extended directly to the case of d variables (d ges 2).
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Generalized Multivariate Rectangular Matrix PadÉ-Type Approximants
IEEE Transactions on Circuits and Systems I: Regular Papers, 2007Co-Authors: Cheng-de Zheng, Huaguang ZhangAbstract:A new method for the construction of generalized multivariate rectangular matrix Pade-type Approximants on a rectangular grid is introduced in this paper, by choosing an arbitrary monic bivariate polynomial as the generating one of the Approximant. We discuss their several typical important properties and study the connection between bivariate rectangular matrix Pade-type Approximants and Pade Approximants. The arguments given in detail in two variables can extend directly to the case of d variables (d ges 2).
Jean-marie Dubois - One of the best experts on this subject based on the ideXlab platform.
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New Approximant phases in Al–Cr–Fe
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2000Co-Authors: Valentin Demange, F. Machizaud, Jiefeng Wu, V Brien, Jean-marie DuboisAbstract:Recently, new Approximant phases were pointed out in the Al-Cr-Fe system, namely orthorhombic O-Al-Cr-Fe, hexagonal H-Al-Cr-Fe and monoclinic M-Al-Cr-Fe. In the corresponding analysed samples, the new Approximant phases were always coexisting with metallic aluminium. We have studied the Al-Cr-Fe system within a broad composition range. In one alloy with composition Al81Cr11Fe8, two new crystalline Approximants of the decagonal phase were discovered. These phases were analysed by differential thermal analysis (DTA), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and microprobe analysis. The phases were found to be isomorphic with a C-3.1-phase earlier discovered by Van Tendeloo et al. in Al-Mn-Ni and an O-1-phase earlier discovered by Dong et al. in Al-Cr-Cu-Fe. Moreover, we have found in the same sample the O-Al-Cr-Fe phase as well as metallic aluminium. (C) 2000 Elsevier Science B.V. All rights reserved.
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Structure and tribological property of B2-based Approximants
Bulletin of Materials Science, 1999Co-Authors: C. Dong, Jean-marie Dubois, Li-ming Zhang, Qing-gang Zhou, Hui-chen Zhang, Qiu-hua ZhangAbstract:The present paper is concerned with a special group of Approximants with B2 superstructures. In the first part, recent work on structural features of the B2 superstructure Approximants is summarized. Experimental results obtained in Al-Cu-Mn and Al-Cu systems are presented, where a series of B2-based Approximants are observed. These phases all have similar valence electron concentrations, in full support of thee/a-constant definition of Approximants. Special emphasis is laid on the chemical twinning modes of the B2 basic structure in relation to the Al-Cu Approximants. It is revealed that the B2 twinning mode responsible for the formation of local pentagonal atomic arrangements is of 180°/[111] type. This is also the origin of 5-fold twinning of the B2 phase on quasicrystal surfaces. Crystallographic features of phases B2, τ2, τ3,γ, and other newly discovered phases are also discussed. In all these phases, local pentagonal configurations are revealed. In the second part, dry tribological properties of some AlCuFe samples containing the B2-type phases are presented. The results indicated that the B2 phase having their valence ratio near that of the quasicrystal possesses low friction coefficient under various loads, comparable with the annealed quasicrystalline ingot. Such a result indicates that the B2-type phase withe/a near that of quasicrystal is indeed an Approximant, which is in full support of the valence electron criterion for Approximants.
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Lattice transformations in the Approximant and decagonal phases
Journal of Physics: Condensed Matter, 1992Co-Authors: Song Seng Kang, Jean-marie DuboisAbstract:A few two-dimensional Approximant-Approximant and Approximant-quasicrystal lattice transformations are studied. These lattice transformations are governed by three mechanisms: translational slip, rotational slip and irrational twinning. These operations can generate an infinite number of Approximants, most of them having commensurate structure. The irrational twinning generates either the one-dimensional or two-dimensional aperiodic lattices depending on the orientation of the irrational twin plane with respect to the periodic lattice. Experimental evidence in favour of such lattice transformations is supplied by high-resolution electron microscopy imaging in two Approximant structures.
T Takeuchi - One of the best experts on this subject based on the ideXlab platform.
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contribution of local atomic arrangements and electronic structure to high electrical resistivity in the al_ 82 6 x re_ 17 4 si_x 7 x 12 1 1 1 1 1 1 Approximant
Physical Review B, 2003Co-Authors: T Takeuchi, T Onogi, Toshio Otagiri, Uichiro Mizutani, H Sato, K Kato, T KamiyamaAbstract:Electrical resistivity of ${\mathrm{Al}}_{82.6\ensuremath{-}x}{\mathrm{Re}}_{17.4}{\mathrm{Si}}_{x}$ $(7l~xl~12)$ 1/1-1/1-1/1 Approximants was discussed in terms of their electronic structure near the Fermi level and the local atomic arrangements. Strong composition dependence of the electrical resistivity was observed for these 1/1-1/1/-1/1 Approximants; samples with $x=7,$ 9, and 12 show the Boltzmann-type electrical resistivity, while the others possess behaviors expected for system under the weak-localization. We found that the weak localization effect in the electrical resistivity, which is one of the characteristics of the corresponding Al-based quasicrystals, appears only when a condition of very low density of states with imperfections in the periodicity is satisfied. The Boltzmann-type behavior, on the other hand, takes place when one of the two factors, the very low density of states or the imperfection in the periodicity, is absent from the structure of the 1/1-1/1-1/1 Approximant.
