|
Trihexaflexagon Example
In geometry, flexagons are flat models, usually constructed by folding strips of paper, that can be ''flexed'' or folded in certain ways to reveal faces besides the two that were originally on the back and front. Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix can be added to the name to indicate the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon. In hexaflexagon theory (that is, concerning flexagons with six sides), flexagons are usually defined in terms of ''pats''. Two flexagons are equivalent if one can be transformed to the other by a series of pinches and rotations. Flexagon equivalence is an equivalence relation. History Discovery and introduction The discovery of the first flexagon, a trihexaflexagon, is credited to the British mathematician Arthur H. Stone, whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbick & Held Printing Company
Herbick & Held Printing Company was a high-end financial printer in Pittsburgh, Pennsylvania, that did business with many prominent companies such as US Steel, Mellon Bank and Gulf Oil, printing annual reports and other financial documents. It also printed many volumes for the University of Pittsburgh The University of Pittsburgh (Pitt) is a public state-related research university in Pittsburgh, Pennsylvania. The university is composed of 17 undergraduate and graduate schools and colleges at its urban Pittsburgh campus, home to the universit ... Press. The company printed the baseball programs for the Pittsburgh Pirates for many years, including the 1960 World Series Program. A copy of this program exists in the Heinz museum on the north side of Pittsburgh. Another memorable printing job was for RCA. Several million copies of the insert for the "Sound of Music" album was printed in the late 1960s. It was in business from 1903 to about 1984. It was founded by August He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trefoil Knot
In knot theory, a branch of mathematics, the trefoil knot is the simplest example of a nontrivial knot. The trefoil can be obtained by joining together the two loose ends of a common overhand knot, resulting in a knotted loop. As the simplest knot, the trefoil is fundamental to the study of mathematical knot theory. The trefoil knot is named after the three-leaf clover (or trefoil) plant. Descriptions The trefoil knot can be defined as the curve obtained from the following parametric equations: :\begin x &= \sin t + 2 \sin 2t \\ y &= \cos t - 2 \cos 2t \\ z &= -\sin 3t \end The (2,3)-torus knot is also a trefoil knot. The following parametric equations give a (2,3)-torus knot lying on torus (r-2)^2+z^2 = 1: :\begin x &= (2+\cos 3t) \cos 2t \\ y &= (2+\cos 3t )\sin 2t \\ z &= \sin 3t \end Any continuous deformation of the curve above is also considered a trefoil knot. Specifically, any curve isotopic to a trefoil knot is also considered to be a trefoil. In addition, the mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Möbius Strip
In mathematics, a Möbius strip, Möbius band, or Möbius loop is a surface that can be formed by attaching the ends of a strip of paper together with a half-twist. As a mathematical object, it was discovered by Johann Benedict Listing and August Ferdinand Möbius in 1858, but it had already appeared in Roman mosaics from the third century CE. The Möbius strip is a non-orientable surface, meaning that within it one cannot consistently distinguish clockwise from counterclockwise turns. Every non-orientable surface contains a Möbius strip. As an abstract topological space, the Möbius strip can be embedded into three-dimensional Euclidean space in many different ways: a clockwise half-twist is different from a counterclockwise half-twist, and it can also be embedded with odd numbers of twists greater than one, or with a knotted centerline. Any two embeddings with the same knot for the centerline and the same number and direction of twists are topologically equivalent. All of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recycling Symbol
The universal recycling symbol ( or in Unicode) is internationally recognized for symbol for recycling activity. The symbol's creation originates on the first Earth Day in 1970, where the logo depicted is a Möbius strip. The public domain status of the symbol has been challenged before, but attempts have been unsuccessful. Many variations on the logo had been created since its creation. History Worldwide attention to environmental issues led to the first Earth Day in 1970. Container Corporation of America, a large producer of recycled paperboard, sponsored a contest for art and design students at high schools and colleges across the country to raise awareness of environmental issues. It was won by Gary Anderson (designer), Gary Anderson, then a 23-year-old college student at the University of Southern California, whose entry was the image now known as the universal recycling symbol. The symbol is not trademarked and is in the public domain. The public-domain status of the symb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trihexaflexagon Example
In geometry, flexagons are flat models, usually constructed by folding strips of paper, that can be ''flexed'' or folded in certain ways to reveal faces besides the two that were originally on the back and front. Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix can be added to the name to indicate the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon. In hexaflexagon theory (that is, concerning flexagons with six sides), flexagons are usually defined in terms of ''pats''. Two flexagons are equivalent if one can be transformed to the other by a series of pinches and rotations. Flexagon equivalence is an equivalence relation. History Discovery and introduction The discovery of the first flexagon, a trihexaflexagon, is credited to the British mathematician Arthur H. Stone, whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Himber
Richard Himber (born Herbert Richard Imber; February 20, 1899 – December 11, 1966) was an American bandleader, composer, violinist, magician and practical joker. Early life He was born as Herbert Richard Imber in Newark, New Jersey to the owner of a chain of meat stores. His parents gave him violin lessons, but when they found him performing in a seedy Newark dive, they took the instrument away from him and sent him to military school. In 1915, he stole away into New York City, where Sophie Tucker heard him play and hired him as a novelty act to play with her and the ''Five Kings of Syncopation'' where Himber was the highlight of the cabaret act. He worked his way through Vaudeville and down Tin Pan Alley. He managed Rudy Vallee's orchestra service, which sent out bands for private parties and society functions. A suave salesman and irrepressible idea man, he soon had his own band booking agency. In 1932, he acquired the first known "vanity" telephone number, ''R-HIMBER'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubik's Magic
Rubik's Magic, like the Rubik's Cube, is a mechanical puzzle invented by Ernő Rubik and first manufactured by Matchbox in the mid-1980s. The puzzle consists of eight black square tiles (changed to red squares with goldish rings in 1997) arranged in a 2 × 4 rectangle; diagonal grooves on the tiles hold wires that connect them, allowing them to be folded onto each other and unfolded again in two perpendicular directions (assuming that no other connections restrict the movement) in a manner similar to a Jacob's ladder toy. The front side of the puzzle shows, in the initial state, three separate, rainbow-coloured rings; the back side consists of a scrambled picture of three interconnected rings. The goal of the game is to fold the puzzle into a heart-like shape and unscramble the picture on the back side, thus interconnecting the rings. Numerous ways to accomplish this exist, and experienced players can transform the puzzle from its initial into the solved state in less than 2 sec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacob's Ladder (toy)
A Jacob's ladder (also magic tablets, Chinese blocks, and klick-klack toyFrauenfelder, Mark (2011). ''Make: Technology On Your Time, Vol. 26: Roll Your Own'', p.148. O'Reilly Media. .) is a Folk culture, folk toy consisting of toy block, blocks of wood held together by strings or ribbons. When the ladder is held at one end, blocks appear to cascade down the strings. This effect is a optical illusion, visual illusion which is the result of one block after another flipping over. It may be considered a Kinetic depth effect, kinetic illusion, where the blocks appear to change position when they do not. Its name ''Jacob's Ladder'' comes from the biblical Jacob's Ladder (Bible), ladder to heaven, mentioned in Genesis 28:12. Of unknown origin, the earliest known review of the Jacob's Ladder is an 1889 ''Scientific American'' article which tells how it is built and works: Construction An arrangement of interlaced ribbons allows each block to act as if hinged to the next one at either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square (geometry)
In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length adjacent sides. It is the only regular polygon whose internal angle, central angle, and external angle are all equal (90°), and whose diagonals are all equal in length. A square with vertices ''ABCD'' would be denoted . Characterizations A convex quadrilateral is a square if and only if it is any one of the following: * A rectangle with two adjacent equal sides * A rhombus with a right vertex angle * A rhombus with all angles equal * A parallelogram with one right vertex angle and two adjacent equal sides * A quadrilateral with four equal sides and four right angles * A quadrilateral where the diagonals are equal, and are the perpendicular bisectors of each other (i.e., a rhombus with equal diagonals) * A convex quadrilateral with successiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
