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  2. Crystallographic restriction theorem - Wikipedia

    en.wikipedia.org/wiki/Crystallographic...

    Thus 5-fold rotational symmetry cannot be eliminated by an argument missing either of those assumptions. A Penrose tiling of the whole (infinite) plane can only have exact 5-fold rotational symmetry (of the whole tiling) about a single point, however, whereas the 4-fold and 6-fold lattices have infinitely many centres of rotational symmetry.

  3. Penrose tiling - Wikipedia

    en.wikipedia.org/wiki/Penrose_tiling

    The pattern represented by every finite patch of tiles in a Penrose tiling occurs infinitely many times throughout the tiling. They are quasicrystals: implemented as a physical structure a Penrose tiling will produce diffraction patterns with Bragg peaks and five-fold symmetry, revealing the repeated patterns and fixed orientations of its tiles ...

  4. Alan Lindsay Mackay - Wikipedia

    en.wikipedia.org/wiki/Alan_Lindsay_Mackay

    He is a pioneer in the introduction of five-fold symmetry in materials and in 1981 predicted quasicrystals in a paper (in Russian) entitled "De Nive Quinquangula" [3] in which he used a Penrose tiling in two and three dimensions to predict a new kind of ordered structures not allowed by traditional crystallography.

  5. Braarudosphaera bigelowii - Wikipedia

    en.wikipedia.org/wiki/Braarudosphaera_bigelowii

    The family Braarudosphaeraceae consist of single-celled coastal phytoplanktonic algae with calcareous scales with five-fold symmetry, called pentaliths. With 12 sides, it has a regular dodecahedral structure, approximately 10 micrometers across. [2] [3] (A) SEM image of a cell of B. bigelowii surrounded by 12 pentaliths.

  6. Compound of dodecahedron and icosahedron - Wikipedia

    en.wikipedia.org/wiki/Compound_of_dodecahedron...

    It has icosahedral symmetry (I h) and the same vertex arrangement as a rhombic triacontahedron. This can be seen as the three-dimensional equivalent of the compound of two pentagons ({10/2} "decagram"); this series continues into the fourth dimension as the compound of 120-cell and 600-cell and into higher dimensions as compounds of hyperbolic ...

  7. Rhombic icosahedron - Wikipedia

    en.wikipedia.org/wiki/Rhombic_icosahedron

    A rhombic icosahedron. The rhombic icosahedron is a polyhedron shaped like an oblate sphere.Its 20 faces are congruent golden rhombi; [1] 3, 4, or 5 faces meet at each vertex. It has 5 faces (green on top figure) meeting at each of its 2 poles; these 2 vertices lie on its axis of 5-fold symmetry, which is perpendicular to 5 axes of 2-fold symmetry through the midpoints of opposite equatorial ...

  8. Quasicrystal - Wikipedia

    en.wikipedia.org/wiki/Quasicrystal

    The more precise mathematical definition is that there is never translational symmetry in more than n – 1 linearly independent directions, where n is the dimension of the space filled, e.g., the three-dimensional tiling displayed in a quasicrystal may have translational symmetry in two directions.

  9. Medial rhombic triacontahedron - Wikipedia

    en.wikipedia.org/wiki/Medial_rhombic_triacontahedron

    Its 24 vertices are all on the 12 axes with 5-fold symmetry (i.e. each corresponds to one of the 12 vertices of the icosahedron). This means that on each axis there is an inner and an outer vertex. The ratio of outer to inner vertex radius is , the golden ratio.