A Standardized Japanese Nomenclature for Crystal Forms
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Final Poster
Associating Finite Groups with Dessins d’Enfants Luis Baeza, Edwin Baeza, Conner Lawrence, and Chenkai Wang Abstract Platonic Solids Rotation Group Dn: Regular Convex Polygon Approach Each finite, connected planar graph has an automorphism group G;such Following Magot and Zvonkin, reduce to easier cases using “hypermaps” permutations can be extended to automorphisms of the Riemann sphere φ : P1(C) P1(C), then composing β = φ f where S 2(R) P1(C). In 1984, Alexander Grothendieck, inspired by a result of f : 1( ) ! 1( )isaBely˘ımapasafunctionofeither◦ zn or ' P C P C Gennadi˘ıBely˘ıfrom 1979, constructed a finite, connected planar graph 4 zn/(zn +1)! 2 such that Aut(f ) Z or Aut(f ) D ,respectively. ' n ' n ∆β via certain rational functions β(z)=p(z)/q(z)bylookingatthe inverse image of the interval from 0 to 1. The automorphisms of such a Hypermaps: Rotation Group Zn graph can be identified with the Galois group Aut(β)oftheassociated 1 1 rational function β : P (C) P (C). In this project, we investigate how Rigid Rotations of the Platonic Solids I Wheel/Pyramids (J1, J2) ! w 3 (w +8) restrictive Grothendieck’s concept of a Dessin d’Enfant is in generating all n 2 I φ(w)= 1 1 z +1 64 (w 1) automorphisms of planar graphs. We discuss the rigid rotations of the We have an action : PSL2(C) P (C) P (C). β(z)= : v = n + n, e =2 n, f =2 − n ◦ ⇥ 2 !n 2 4 zn · Platonic solids (the tetrahedron, cube, octahedron, icosahedron, and I Zn = r r =1 and Dn = r, s s = r =(sr) =1 are the rigid I Cupola (J3, J4, J5) dodecahedron), the Archimedean solids, the Catalan solids, and the rotations of the regular convex polygons,with 4w 4(w 2 20w +105)3 I φ(w)= − ⌦ ↵ ⌦ 1 ↵ Rotation Group A4: Tetrahedron 3 2 Johnson solids via explicit Bely˘ımaps. -
The Conway Space-Filling
Symmetry: Art and Science Buenos Aires Congress, 2007 THE CONWAY SPACE-FILLING MICHAEL LONGUET-HIGGINS Name: Michael S. Longuet-Higgins, Mathematician and Oceanographer, (b. Lenham, England, 1925). Address: Institute for Nonlinear Science, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92037-0402, U.S.A. Email: [email protected] Fields of interest: Fluid dynamics, ocean waves and currents, geophysics, underwater sound, projective geometry, polyhedra, mathematical toys. Awards: Rayleigh Prize for Mathematics, Cambridge University, 1950; Hon.D. Tech., Technical University of Denmark, 1979; Hon. LL.D., University of Glasgow, Scotland, 1979; Fellow of the American Geophysical Union, 1981; Sverdrup Gold Medal of the American Meteorological Society, 1983; International Coastal Engineering Award of the American Society of Civil Engineers, 1984; Oceanography Award of the Society for Underwater Technology, 1990; Honorary Fellow of the Acoustical Society of America, 2002. Publications: “Uniform polyhedra” (with H.S.M. Coxeter and J.C.P. Miller (1954). Phil. Trans. R. Soc. Lond. A 246, 401-450. “Some Mathematical Toys” (film), (1963). British Association Meeting, Aberdeen, Scotland; “Clifford’s chain and its analogues, in relation to the higher polytopes,” (1972). Proc. R. Soc. Lond. A 330, 443-466. “Inversive properties of the plane n-line, and a symmetric figure of 2x5 points on a quadric,” (1976). J. Lond. Math. Soc. 12, 206-212; Part II (with C.F. Parry) (1979) J. Lond. Math. Soc. 19, 541-560; “Nested triacontahedral shells, or How to grow a quasi-crystal,” (2003) Math. Intelligencer 25, 25-43. Abstract: A remarkable new space-filling, with an unusual symmetry, was recently discovered by John H. -
Computational Design Framework 3D Graphic Statics
Computational Design Framework for 3D Graphic Statics 3D Graphic for Computational Design Framework Computational Design Framework for 3D Graphic Statics Juney Lee Juney Lee Juney ETH Zurich • PhD Dissertation No. 25526 Diss. ETH No. 25526 DOI: 10.3929/ethz-b-000331210 Computational Design Framework for 3D Graphic Statics A thesis submitted to attain the degree of Doctor of Sciences of ETH Zurich (Dr. sc. ETH Zurich) presented by Juney Lee 2015 ITA Architecture & Technology Fellow Supervisor Prof. Dr. Philippe Block Technical supervisor Dr. Tom Van Mele Co-advisors Hon. D.Sc. William F. Baker Prof. Allan McRobie PhD defended on October 10th, 2018 Degree confirmed at the Department Conference on December 5th, 2018 Printed in June, 2019 For my parents who made me, for Dahmi who raised me, and for Seung-Jin who completed me. Acknowledgements I am forever indebted to the Block Research Group, which is truly greater than the sum of its diverse and talented individuals. The camaraderie, respect and support that every member of the group has for one another were paramount to the completion of this dissertation. I sincerely thank the current and former members of the group who accompanied me through this journey from close and afar. I will cherish the friendships I have made within the group for the rest of my life. I am tremendously thankful to the two leaders of the Block Research Group, Prof. Dr. Philippe Block and Dr. Tom Van Mele. This dissertation would not have been possible without my advisor Prof. Block and his relentless enthusiasm, creative vision and inspiring mentorship. -
On a Remarkable Cube of Pyrite, Carrying Crys- Tallized Gold and Galena of Unusual Habit
ON A REMARKABLE CUBE OF PYRITE, CARRYING CRYS- TALLIZED GOLD AND GALENA OF UNUSUAL HABIT By JOSEPH E. POGUE Assistant Curator, Division of Mineralogy, U. S. National Museum With One Plate The intergrowth or interpenetration of two or more minerals, especially if these be well crystallized, often shows a certain mutual crystallographic control in the arrangement of the individuals, sug- gestive of interacting molecular forces. Occasionally a crystal upon nearly completing its growth exerts what may be termed "surface affinit}'," in that it seems to attract molecules of composition differ- ent from its own and causes these to crystallize in positions bearing definite crystallographic relations to the host crystal, as evidenced, for example, by the regular arrangement of marcasite on calcite, chalcopyrite on galena, quartz on fluorite, and so on. Of special interest, not only because exhibiting the features mentioned above, but also on account of the unusual development of the individuals and the great beauty of the specimen, is a large cube of pyrite, studded with crystals of native gold and partly covered by plates of galena, acquired some years ago by the U. S. National Museum. This cube measures about 2 inches (51 mm.) along its edge, and is prominently striated, as is often the case with pyrite. It contains something more than 130 crystals of gold attached to its surface, has about one-fourth of its area covered with galena, and upon one face shows an imperfect crystal of chalcopyrite. The specimen came into the possession of the National Museum in 1906 and was ob- tained from the Snettisham District, near Juneau, Southeast Alaska. -
A Congruence Problem for Polyhedra
A congruence problem for polyhedra Alexander Borisov, Mark Dickinson, Stuart Hastings April 18, 2007 Abstract It is well known that to determine a triangle up to congruence requires 3 measurements: three sides, two sides and the included angle, or one side and two angles. We consider various generalizations of this fact to two and three dimensions. In particular we consider the following question: given a convex polyhedron P , how many measurements are required to determine P up to congruence? We show that in general the answer is that the number of measurements required is equal to the number of edges of the polyhedron. However, for many polyhedra fewer measurements suffice; in the case of the cube we show that nine carefully chosen measurements are enough. We also prove a number of analogous results for planar polygons. In particular we describe a variety of quadrilaterals, including all rhombi and all rectangles, that can be determined up to congruence with only four measurements, and we prove the existence of n-gons requiring only n measurements. Finally, we show that one cannot do better: for any ordered set of n distinct points in the plane one needs at least n measurements to determine this set up to congruence. An appendix by David Allwright shows that the set of twelve face-diagonals of the cube fails to determine the cube up to conjugacy. Allwright gives a classification of all hexahedra with all face- diagonals of equal length. 1 Introduction We discuss a class of problems about the congruence or similarity of three dimensional polyhedra. -
Unit 6 Visualising Solid Shapes(Final)
• 3D shapes/objects are those which do not lie completely in a plane. • 3D objects have different views from different positions. • A solid is a polyhedron if it is made up of only polygonal faces, the faces meet at edges which are line segments and the edges meet at a point called vertex. • Euler’s formula for any polyhedron is, F + V – E = 2 Where F stands for number of faces, V for number of vertices and E for number of edges. • Types of polyhedrons: (a) Convex polyhedron A convex polyhedron is one in which all faces make it convex. e.g. (1) (2) (3) (4) 12/04/18 (1) and (2) are convex polyhedrons whereas (3) and (4) are non convex polyhedron. (b) Regular polyhedra or platonic solids: A polyhedron is regular if its faces are congruent regular polygons and the same number of faces meet at each vertex. For example, a cube is a platonic solid because all six of its faces are congruent squares. There are five such solids– tetrahedron, cube, octahedron, dodecahedron and icosahedron. e.g. • A prism is a polyhedron whose bottom and top faces (known as bases) are congruent polygons and faces known as lateral faces are parallelograms (when the side faces are rectangles, the shape is known as right prism). • A pyramid is a polyhedron whose base is a polygon and lateral faces are triangles. • A map depicts the location of a particular object/place in relation to other objects/places. The front, top and side of a figure are shown. Use centimetre cubes to build the figure. -
Fundamental Principles Governing the Patterning of Polyhedra
FUNDAMENTAL PRINCIPLES GOVERNING THE PATTERNING OF POLYHEDRA B.G. Thomas and M.A. Hann School of Design, University of Leeds, Leeds LS2 9JT, UK. [email protected] ABSTRACT: This paper is concerned with the regular patterning (or tiling) of the five regular polyhedra (known as the Platonic solids). The symmetries of the seventeen classes of regularly repeating patterns are considered, and those pattern classes that are capable of tiling each solid are identified. Based largely on considering the symmetry characteristics of both the pattern and the solid, a first step is made towards generating a series of rules governing the regular tiling of three-dimensional objects. Key words: symmetry, tilings, polyhedra 1. INTRODUCTION A polyhedron has been defined by Coxeter as “a finite, connected set of plane polygons, such that every side of each polygon belongs also to just one other polygon, with the provision that the polygons surrounding each vertex form a single circuit” (Coxeter, 1948, p.4). The polygons that join to form polyhedra are called faces, 1 these faces meet at edges, and edges come together at vertices. The polyhedron forms a single closed surface, dissecting space into two regions, the interior, which is finite, and the exterior that is infinite (Coxeter, 1948, p.5). The regularity of polyhedra involves regular faces, equally surrounded vertices and equal solid angles (Coxeter, 1948, p.16). Under these conditions, there are nine regular polyhedra, five being the convex Platonic solids and four being the concave Kepler-Poinsot solids. The term regular polyhedron is often used to refer only to the Platonic solids (Cromwell, 1997, p.53). -
The Crystal Forms of Diamond and Their Significance
THE CRYSTAL FORMS OF DIAMOND AND THEIR SIGNIFICANCE BY SIR C. V. RAMAN AND S. RAMASESHAN (From the Department of Physics, Indian Institute of Science, Bangalore) Received for publication, June 4, 1946 CONTENTS 1. Introductory Statement. 2. General Descriptive Characters. 3~ Some Theoretical Considerations. 4. Geometric Preliminaries. 5. The Configuration of the Edges. 6. The Crystal Symmetry of Diamond. 7. Classification of the Crystal Forros. 8. The Haidinger Diamond. 9. The Triangular Twins. 10. Some Descriptive Notes. 11. The Allo- tropic Modifications of Diamond. 12. Summary. References. Plates. 1. ~NTRODUCTORY STATEMENT THE" crystallography of diamond presents problems of peculiar interest and difficulty. The material as found is usually in the form of complete crystals bounded on all sides by their natural faces, but strangely enough, these faces generally exhibit a marked curvature. The diamonds found in the State of Panna in Central India, for example, are invariably of this kind. Other diamondsJas for example a group of specimens recently acquired for our studies ffom Hyderabad (Deccan)--show both plane and curved faces in combination. Even those diamonds which at first sight seem to resemble the standard forms of geometric crystallography, such as the rhombic dodeca- hedron or the octahedron, are found on scrutiny to exhibit features which preclude such an identification. This is the case, for example, witb. the South African diamonds presented to us for the purpose of these studŸ by the De Beers Mining Corporation of Kimberley. From these facts it is evident that the crystallography of diamond stands in a class by itself apart from that of other substances and needs to be approached from a distinctive stand- point. -
Uniform Panoploid Tetracombs
Uniform Panoploid Tetracombs George Olshevsky TETRACOMB is a four-dimensional tessellation. In any tessellation, the honeycells, which are the n-dimensional polytopes that tessellate the space, Amust by definition adjoin precisely along their facets, that is, their ( n!1)- dimensional elements, so that each facet belongs to exactly two honeycells. In the case of tetracombs, the honeycells are four-dimensional polytopes, or polychora, and their facets are polyhedra. For a tessellation to be uniform, the honeycells must all be uniform polytopes, and the vertices must be transitive on the symmetry group of the tessellation. Loosely speaking, therefore, the vertices must be “surrounded all alike” by the honeycells that meet there. If a tessellation is such that every point of its space not on a boundary between honeycells lies in the interior of exactly one honeycell, then it is panoploid. If one or more points of the space not on a boundary between honeycells lie inside more than one honeycell, the tessellation is polyploid. Tessellations may also be constructed that have “holes,” that is, regions that lie inside none of the honeycells; such tessellations are called holeycombs. It is possible for a polyploid tessellation to also be a holeycomb, but not for a panoploid tessellation, which must fill the entire space exactly once. Polyploid tessellations are also called starcombs or star-tessellations. Holeycombs usually arise when (n!1)-dimensional tessellations are themselves permitted to be honeycells; these take up the otherwise free facets that bound the “holes,” so that all the facets continue to belong to two honeycells. In this essay, as per its title, we are concerned with just the uniform panoploid tetracombs. -
Tetrahedral Decompositions of Hexahedral Meshes
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Europ. J. Combinatorics (1989) 10, 435-443 Tetrahedral Decompositions of Hexahedral Meshes DEREK HACON AND CARLOS TOMEI A hexahedral mesh is a partition of a region in 3-space 1R3 into (not necessarily regular) hexahedra which fit together face to face. We are concerned here with the question of how the hexahedra may be decomposed into tetrahedra without introducing any new vertices. We consider two possible decompositions, in which each hexahedron breaks into five or six tetrahedra in a prescribed fashion. In both cases, we obtain simple verifiable criteria for the existence of a decomposition, by making use of elementary facts of graph theory and algebraic. topology. 1. INTRODUcnON A hexahedral mesh is a partition of a region in 3-space ~3 into (not necessarily regular) hexahedra which fit together face to face. We are concerned here with the question of how the hexahedra may be decomposed into tetrahedra without introduc ing any new vertices. There is one well known [1] way of decomposing a hexahedral mesh into non-overlapping tetrahedra which always works. Start by labelling the vertices 1,2,3, .... Then divide each face into two triangles by the diagonal containing the first vertex of the face. Next consider a hexahedron H with first vertex V. The three faces of H not containing V have already been divided up into a total of six triangles, so take each of these to be the base of a tetrahedron with apex V. -
On Some Properties of Distance in TO-Space
Aksaray University Aksaray J. Sci. Eng. Journal of Science and Engineering Volume 4, Issue 2, pp. 113-126 e-ISSN: 2587-1277 doi: 10.29002/asujse.688279 http://dergipark.gov.tr/asujse http://asujse.aksaray.edu.tr Available online at Research Article On Some Properties of Distance in TO-Space Zeynep Can* Department of Mathematics, Faculty of Science and Letters, Aksaray University, Aksaray 68100, Turkey ▪Received Date: Feb 12, 2020 ▪Revised Date: Dec 21, 2020 ▪Accepted Date: Dec 24, 2020 ▪Published Online: Dec 25, 2020 Abstract The aim of this work is to investigate some properties of the truncated octahedron metric introduced in the space in further studies on metric geometry. With this metric, the 3- dimensional analytical space is a Minkowski geometry which is a non-Euclidean geometry in a finite number of dimensions. In a Minkowski geometry, the unit ball is a certain symmetric closed convex set instead of the usual sphere in Euclidean space. The unit ball of the truncated octahedron geometry is a truncated octahedron which is an Archimedean solid. In this study, 2 first, metric properties of truncated octahedron distance, 푑푇푂, in ℝ has been examined by 3 metric approach. Then, by using synthetic approach some distance formulae in ℝ푇푂, 3- dimensional analytical space furnished with the truncated octahedron metric has been found. Keywords Metric, Convex polyhedra, Truncated octahedron, Distance of a point to a line, Distance of a point to a plane, Distance between two lines *Corresponding Author: Zeynep Can, [email protected], 0000-0003-2656-5555 2017-2020©Published by Aksaray University 113 Zeynep Can (2020). -
Building Ideas
TM Geometiles Building Ideas Patent Pending GeometilesTM is a product of TM www.geometiles.com Welcome to GeometilesTM! Here are some ideas of what you can build with your set. You can use them as a springboard for your imagination! Hints and instructions for making selected objects are in the back of this booklet. Platonic Solids CUBE CUBE 6 squares 12 isosceles triangles OCTAHEDRON OCTAHEDRON 8 equilateral triangles 16 scalene triangles 2 Building Ideas © 2015 Imathgination LLC REGULAR TETRAHEDRA 4 equilateral triangles; 8 scalene triangles; 16 equilateral triangles ICOSAHEDRON DODECAHEDRON 20 equilateral triangles 12 pentagons 3 Building Ideas © 2015 Imathgination LLC Selected Archimedean Solids CUBOCTAHEDRON ICOSIDODECAHEDRON 6 squares, 8 equilateral triangles 20 equilateral triangles, 12 pentagons Miscellaneous Solids DOUBLE TETRAHEDRON RHOMBIC PRISM 12 scalene triangles 8 scalene triangles; 4 rectangles 4 Building Ideas © 2015 Imathgination LLC PENTAGONAL ANTIPRISM HEXAGONAL ANTIPRISM 10 equilateral triangles, 2 pentagons. 24 equilateral triangles STELLA OCTANGULA, OR STELLATED OCTAHEDRON 24 equilateral triangles 5 Building Ideas © 2015 Imathgination LLC TRIRECTANGULAR TETRAHEDRON 12 isosceles triangles, 8 scalene triangles SCALENOHEDRON TRAPEZOHEDRON 8 scalene triangles 16 scalene triangles 6 Building Ideas © 2015 Imathgination LLC Playful shapes FLOWER 12 pentagons, 10 squares, 9 rectagles, 6 scalene triangles 7 Building Ideas © 2015 Imathgination LLC GEMSTONE 8 equilateral triangles, 8 rectangles, 4 isosceles triangles, 8 scalene