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Next Generation Transmission Systems Enabling Technologies, Architectures, and Performances
Published in Iannone Eugenio, Telecommunication Networks, 2017
The performances of coherent detection M-PolSK are shown in Figure 9.43 using the configurations whose parameters are reported in Table 9.3, the 32 level system constellation is derived by randomly selected 32 points out of the 60 vertices of the snub-dodecahedron and the 64 points constellation by randomly selecting 64 out of the 120 vertices of the Icosidodecahedron. In the figure, the performances of a coherent detection M-PolSK system using the optimum constellations reported in [35,37] are also plotted in dashed lines. It is evident that the sensitivity gain related to the use of the optimum constellation with respect to a more regular suboptimum one is small and probably in practice it is cancelled by the difficulty to reproduce accurately the optimum configurations due to their more complex structure.
Cuboctahedron Model of Atomic Mass Based on a Dual Tetrahedral Coordinate System
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
James Garnett Sawyer, Marla Jeanne Wagner
FG and GR both exhibit properties of a dual-coordinate system based on kagome lattice, the cuboctahedron, icosidodecahedron, and icosahedron. The icosidodecahedron and icosahedron are the foundations of a triangular-based geodesic spherical space system (Zhuang, 2012).
Planar defect in approximant: the case of Cu-Al-Sc alloy
Published in Philosophical Magazine, 2021
Tsutomu Ishimasa, Yeong-Gi So, Marek Mihalkovič
The structure of the 1/1 approximant is interpreted as a combination of periodic framework and embedded Tsai-type clusters. The framework consists of the sites M3 and M5. The site M3 is occupied mostly by Cu, and site M5 by Al. This framework has holes at the origin and the body-centre position of the unit cell, in which the Tsai-type clusters are embedded. The Tsai-type cluster consists of triple shells plus disordered arrangement (M7) shown in Figure 3(a). The triple shells consist of an inner dodecahedron (M2 and M4), a Sc icosahedron, and an outermost icosidodecahedron (M1 and M6). The atoms consisting of the Tsai-type cluster exhibit interesting fluctuation, as presented in Figure 3(f). In particular, the fractional site M7 has very large displacement parameters. This is interpreted as a randomly oriented tetrahedron [23]. The characteristic fluctuation observed in Figure 3(f) may be related to the dynamical motion of atoms reported in the isostructural Zn6Sc [24,25] or the static chemical order theoretically predicted in the Cu-Al-Sc approximant [26].
Formation and crystallographic orientation study of quasicrystal, 2/1 and 1/1 approximants in Cd–Mg–Y system using electron backscatter diffraction (EBSD)
Published in Philosophical Magazine, 2019
Farid Labib, Satoshi Ohhashi, An-Pang Tsai
Atomic structure of the i-QC in the binary Cd-Yb, so-called a Tsai-type i-QC, and the ternary Cd–Mg–Yb systems have been also studied, as a result of which, a rhombic triacontahedral (RTH) building block, namely Tsai-type cluster, consisting four inner shells was revealed [11,12]. Mg atoms in the ternary Cd–Mg–Yb system were reported to locate on the two-fold axes of an icosidodecahedron and the vertex positions of the rhombic triacontahedron [15]. Almost the same atomic size and valence electron number of the Mg and Cd, which results in a solid solution of the α-Mg (Cd,Mg) over an entire compositional range in the Cd–Mg binary phase diagram [16], brings a unique characteristic to the Cd–Mg–RE type QCs and spread them over a wide compositional area in ternary phase diagrams [6,13]. However, despite deep investigations in the binary Cd–Yb and ternary Cd–Mg–Yb systems, a literature lacks thorough study in the Cd–Mg–RE (RE smaller than Yb) systems. One of the attempts in studying these systems dates back to 2000 [17], in which the existence of the stable i-QC phase in the Cd–Mg–RE (RE = Y, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) systems was reported to be around the composition of Cd65Mg20RE15.
Icosahedral quasicrystal, 1/1 and 2/1 approximants in Zn-based ternary alloys containing Au and Yb/Tb
Published in Philosophical Magazine Letters, 2019
This crystal structure is a typical example of the 1/1 approximant of Tsai-type except for the split of M6. Tsai-type clusters shown in Figure 4c are embedded in body-centred network formed by M3 and M5 sites (Figure 4d). The Tsai-type cluster consists of a triple shell with an irregular central region (Figure 4a) in which four atoms form a randomly orientated tetrahedron [19]. The triple shell consists of the innermost dodecahedron (M2 and M4), icosahedron (Tb), and icosidodecahedron (M1, M6). The Zn atom at the M8 site connects two Tsai-type clusters along the [111] direction. This result confirms that the Tsai-type 1/1 approximant is formed in Zn-Au-Tb system. It is noted that no corresponding approximant has been reported in binary Zn-Tb system.