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String Art
__notoc__ String art or pin and thread art, is characterized by an arrangement of colored thread strung between points to form geometric patterns or representational designs such as a ship's sails, sometimes with other artist material comprising the remainder of the work. Thread, wire, or string is wound around a grid of nails hammered into a velvet-covered wooden board. Though straight lines are formed by the string, the slightly different angles and metric positions at which strings intersect gives the appearance of Bézier curves (as in the mathematical concept of envelope of a family of straight lines). Quadratic Bézier curve are obtained from strings based on two intersecting segments. Other forms of string art include Spirelli, which is used for cardmaking and scrapbooking, and curve stitching, in which string is stitched through holes. String art has its origins in the 'curve stitch' activities invented by Mary Everest Boole at the end of the 19th century to make mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardmaking
Card making is the craft of hand-making greeting cards. Many people with interests in allied crafts such as scrapbooking and stamping have begun to use their skills to start making handmade cards. This has contributed to cardmaking becoming a popular hobby. Traditional high street stores have begun to devote an increasing amount of their floorspace to handmade cards. Handmade products are now being seen by retailers as a way to increase margins, and handmade cards are no exception. This is particularly the case as mass-produced printed greeting cards have been faced with competition from electronic greeting cards. Over seven billion greeting cards were sent in the US alone last year; greeting cards are a multibillion-dollar business. In contrast, hundreds of small businesses have been set up by avid crafters keen to make a return on their cardmaking efforts. Many of these are taking advantage of the low setup costs of web-based selling and the wide customer-base of auction sites ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Arts Media
The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the ability to detect and process visible light) as well as enabling the formation of several non-image photo response functions. It detects and interprets information from the optical spectrum perceptible to that species to "build a representation" of the surrounding environment. The visual system carries out a number of complex tasks, including the reception of light and the formation of monocular neural representations, colour vision, the neural mechanisms underlying stereopsis and assessment of distances to and between objects, the identification of a particular object of interest, motion perception, the analysis and integration of visual information, pattern recognition, accurate motor coordination under visual guidance, and more. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chilton Book Co
Chilton Company (AKA Chilton Printing Co., Chilton Publishing Co., Chilton Book Co. and Chilton Research Services) is a former publishing company, most famous for its trade magazines, and automotive manuals. It also provided conference and market research services to a wide variety of industries. Chilton grew from a small publisher of a single magazine to a leading publisher of business-to-business magazines, consumer and professional automotive manuals, craft and hobby books, and a large, well-known marketing research company. In the early years, its flagship magazine was ''Iron Age''. In 1955, Chilton's profit reached $1 million for the first time, of which ''Iron Age'' accounted for $750,000. By 1980, ''Iron Ages revenue and status had declined due to the reduction in the size of the US metalworking manufacturing industry, and ''Jewelers Circular Keystone'' captured the position of Chilton's most profitable magazine. While Chilton had leading magazines in several different indu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-connectedness
In algebraic topology, homotopical connectivity is a property describing a topological space based on the dimension of its holes. In general, low homotopical connectivity indicates that the space has at least one low-dimensional hole. The concept of ''n''-connectedness generalizes the concepts of path-connectedness and simple connectedness. An equivalent definition of homotopical connectivity is based on the homotopy groups of the space. A space is ''n''-connected (or ''n''-simple connected) if its first ''n'' homotopy groups are trivial. Homotopical connectivity is defined for maps, too. A map is ''n''-connected if it is an isomorphism "up to dimension ''n,'' in homotopy". Definition using holes All definitions below consider a topological space ''X''. A hole in ''X'' is, informally, a thing that prevents some suitably-placed sphere from continuously shrinking to a point., Section 4.3 Equivalently, it is a sphere that cannot be continuously extended to a ball. Formally, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Envelope (mathematics)
In geometry, an envelope of a planar family of curves is a curve that is tangent to each member of the family at some point, and these points of tangency together form the whole envelope. Classically, a point on the envelope can be thought of as the intersection of two " infinitesimally adjacent" curves, meaning the limit of intersections of nearby curves. This idea can be generalized to an envelope of surfaces in space, and so on to higher dimensions. To have an envelope, it is necessary that the individual members of the family of curves are differentiable curves as the concept of tangency does not apply otherwise, and there has to be a smooth transition proceeding through the members. But these conditions are not sufficient – a given family may fail to have an envelope. A simple example of this is given by a family of concentric circles of expanding radius. Envelope of a family of curves Let each curve ''C''''t'' in the family be given as the solution of an equation ''f'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mary Everest Boole
Mary Everest Boole (11 March 1832 in Wickwar, Gloucestershire – 17 May 1916 in Middlesex, England) was a self-taught mathematician who is best known as an author of didactic works on mathematics, such as ''Philosophy and Fun of Algebra'', and as the wife of fellow mathematician George Boole. Her progressive ideas on education, as expounded in ''The Preparation of the Child for Science'', included encouraging children to explore mathematics through playful activities such as curve stitching. Her life is of interest to feminists as an example of how women made careers in an academic system that did not welcome them. Life She was born in England, the daughter of Reverend Thomas Roupell Everest, Rector of Wickwar, and Mary ''nee'' Ryall. Her uncle was George Everest, the surveyor and geographer after whom Mount Everest was named. She spent the first part of her life in France where she received an education in mathematics from a private tutor. On returning to England at the age ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scrapbooking
Scrapbooking is a method of preserving, presenting and arranging personal and family history in the form of a book, box or card. Typical memorabilia include photographs, printed media, and artwork. Scrapbook albums are often decorated and frequently contain extensive journal entries or written descriptions. Scrapbooking started in the United Kingdom in the nineteenth century. History In the 15th century, commonplace books, popular in England, emerged as a way to compile information that included recipes, quotations, letters, poems and more. Each commonplace book was unique to its creator's particular interests. Friendship albums became popular in the 16th century. These albums were used much like modern day yearbooks, where friends or patrons would enter their names, titles and short texts or illustrations at the request of the album's owner. These albums were often created as souvenirs of European tours and would contain local memorabilia including coats of arms or works of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Envelope (mathematics)
In geometry, an envelope of a planar family of curves is a curve that is tangent to each member of the family at some point, and these points of tangency together form the whole envelope. Classically, a point on the envelope can be thought of as the intersection of two " infinitesimally adjacent" curves, meaning the limit of intersections of nearby curves. This idea can be generalized to an envelope of surfaces in space, and so on to higher dimensions. To have an envelope, it is necessary that the individual members of the family of curves are differentiable curves as the concept of tangency does not apply otherwise, and there has to be a smooth transition proceeding through the members. But these conditions are not sufficient – a given family may fail to have an envelope. A simple example of this is given by a family of concentric circles of expanding radius. Envelope of a family of curves Let each curve ''C''''t'' in the family be given as the solution of an equation ''f'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bézier Curve
A Bézier curve ( ) is a parametric curve used in computer graphics and related fields. A set of discrete "control points" defines a smooth, continuous curve by means of a formula. Usually the curve is intended to approximate a real-world shape that otherwise has no mathematical representation or whose representation is unknown or too complicated. The Bézier curve is named after French engineer Pierre Bézier (1910–1999), who used it in the 1960s for designing curves for the bodywork of Renault cars. Other uses include the design of computer fonts and animation. Bézier curves can be combined to form a Bézier spline, or generalized to higher dimensions to form Bézier surfaces. The Bézier triangle is a special case of the latter. In vector graphics, Bézier curves are used to model smooth curves that can be scaled indefinitely. "Paths", as they are commonly referred to in image manipulation programs, are combinations of linked Bézier curves. Paths are not bound by the lim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
