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Alphabet Letters
In a writing system, a letter is a grapheme that generally corresponds to a phoneme—the smallest functional unit of speech—though there is rarely total one-to-one correspondence between the two. An alphabet is a writing system that uses letters. Definition and usage A letter is a type of grapheme, the smallest functional unit within a writing system. Letters are graphemes that broadly correspond to phonemes, the smallest functional units of sound in speech. Similarly to how phonemes are combined to form spoken words, letters may be combined to form written words. A single phoneme may also be represented by multiple letters in sequence, collectively called a ''multigraph''. Multigraphs include ''digraphs'' of two letters (e.g. English ''ch'', ''sh'', ''th''), and ''trigraphs'' of three letters (e.g. English ''tch''). The same letterform may be used in different alphabets while representing different phonemic categories. The Latin H, Greek eta , and Cyrillic en are homog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Writing System
A writing system comprises a set of symbols, called a ''script'', as well as the rules by which the script represents a particular language. The earliest writing appeared during the late 4th millennium BC. Throughout history, each independently invented writing system gradually emerged from a system of proto-writing, where a small number of ideographs were used in a manner incapable of fully encoding language, and thus lacking the ability to express a broad range of ideas. Writing systems are generally classified according to how its symbols, called ''graphemes'', relate to units of language. Phonetic writing systemswhich include alphabets and syllabariesuse graphemes that correspond to sounds in the corresponding spoken language. Alphabets use graphemes called ''letter (alphabet), letters'' that generally correspond to spoken phonemes. They are typically divided into three sub-types: ''Pure alphabets'' use letters to represent both consonant and vowel sounds, ''abjads'' gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Ray
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay but may also be produced in different ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as He2+ or 2+ indicating a helium ion with a +2 charge (missing its two electrons). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom . Alpha particles have a net spin of zero. When produced in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV and a velocity in the vicinity of 4% of the speed of light. They are a highly ionizing form of particle radiation, with low penetration depth (stopped by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U Engine
A U engine is a piston engine made up of two separate straight engines (complete with separate crankshafts) placed side-by-side and coupled to a shared output shaft. When viewed from the front, the engine block resembles the letter "U". Although much less common than the similar V engine design, several U engines were produced from 1915 to 1987 for use in airplanes, racing cars, racing and road motorcycles, locomotives, and tanks. Design The main benefit of a U engine layout is the ability to share common parts with a straight engine upon which is it based. Additionally, if the two crankshafts rotate in opposite directions, the gyroscopic effect of the rotating components in each cylinder bank cancel each other out. A V engine is typically more compact and lighter than a U engine, in part due to the lack of a second crankshaft, making V engines far more common than U engines. However, the V engine does not cancel the gyroscopic effect. The H engine layout uses a similar con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yarn
Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. '' Thread'' is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for needlework. Yarn can be made of a number of natural or synthetic materials, and comes in a variety of colors and thicknesses (referred to as "weights"). Although yarn may be dyed different colours, most yarns are solid coloured with a uniform hue. Etymology The word " yarn" comes from Middle English, from the Old English , akin to Old High German ', "yarn", Dutch ', Ancient Greek (''chordē'', "string"), and Sanskrit , "band". It originally referred to entrails. History The human production of yarn is known to have existed since the Stone Age and earlier p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R-clip
__NOTOC__ An R-clip, also known as an R-pin, R-key, hairpin cotter pin, hairpin cotter,. bridge pin, hitch pin clip or spring cotter pin, is a fastener made of a durable but flexible material, commonly hardened metal wire, resembling the shape of the letter "R". R-clips are commonly used to secure the ends of round shafts such as axles and clevis pins. The straight leg of the R-clip is pushed into a hole near one end of the shaft until the semicircular "belly" in the middle of the other, bent leg of the R-clip grips one side of the shaft resisting any force removing the R-clip from its hole. To assist insertion, the end of the bent leg is angled away from the straight leg. This angled end rides the side of the shaft and opens the "belly" mouth enough to pass the widest part of the shaft as the R-clip is inserted. There is also a double loop variety when a wider range of suitable shafts is required, and to facilitate the attachment of a retaining tether to prevent the pin's loss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O-ring
An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross section (geometry), cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, forming a seal (mechanical), seal at the interface. The O-ring may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring. Dynamic examples include rotating pump shafts and hydraulic cylinder pistons. Static applications of O-rings may include fluid or gas sealing applications in which: (1) the O-ring is compressed resulting in zero clearance, (2) the O-ring material is vulcanized solid such that it is permeation, impermeable to the fluid or gas, and (3) the O-ring material is resistant to degradation by the fluid or gas. The wide range of potential liquids and gases that need to be sealed has necessitated the development of a wide range of O-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H Engine
An H engine is a piston engine comprising two separate flat engine, flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the front. The most successful "H" engine in this form was the Napier Dagger and its derivatives. The name was also applied to engines of the same basic layout, but rotated through 90 degrees—most famously the Napier Sabre series. A variation on the "H" theme were the Fairey Prince (H-16) & Fairey Monarch, Fairey P.24 Monarch, where the two engines retained separate drives, driving Contra-rotating propellers through separate concentric shafts. Although successful, they only existed in prototype form. The H engine is a relatively rare layout, with its main use being in aircraft engines during the 1930s and 1940s. The 1966 Lotus 43 Formula One car used a BRM 16-cylinder H engine, and an 8-cylinder H engine was used for powerboat rac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maze (HM Prison)
HM Prison Maze (previously Long Kesh Detention Centre, and known colloquially as the Maze or H-Blocks) was a prison in Northern Ireland that was used to house paramilitary prisoners during the Troubles from August 1971 to September 2000. On 15 October 1974 Irish Republican internees burned 21 of the compounds used to house the internees thereby destroying much of Long Kesh. The prison was situated at the former Royal Air Force station of Long Kesh, on the outskirts of Lisburn. This was in the townland of Maze, about southwest of Belfast. The prison and its inmates were involved in such events as the 1981 hunger strike. The prison was closed in 2000 and demolition began on 30 October 2006, but on 18 April 2013 it was announced by the Northern Ireland Executive that the remaining buildings would be redeveloped into a peace centre, however these plans were later abandoned. Background Following the introduction of internment in 1971, Operation Demetrius was implemented by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-clamp
A C-clamp or G-clamp or G-cramp is a type of clamp device typically used to hold a wood or metal workpiece, and often used in, but are not limited to, carpentry and welding. Often believed that these clamps are called "C" clamps because of their C-shaped frame, or also often called C-clamps or G-clampshttp://www.technologystudent.com/equip1/cramp1.htm, Information on G-clamps. because including the screw part, they are shaped like an uppercase letter G. However, in fact, they were originally called a carriage maker's clamp, or Carriage Clamp. Description C-clamps or G-clamps are typically made of steel or cast iron, though smaller clamps may be made of pot metal. At the top of the "C," is usually a small flat edge. At the bottom is a threaded hole through which a large threaded screw protrudes. One end of this screw contains a flat edge of similar size to the one at the top of the frame, and the other end usually a small metal bar, perpendicular to the screw itself, which is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-clamp
An F-clamp, also known as a bar clamp or speed clamp, is a type of clamp. The name comes from its " F" shape. This tool is used in woodworking while more permanent attachment is being made with screws or glue, or in metalworking to hold pieces together for welding or bolting. F-clamps are similar to but distinct from C-clamps and pipe clamps. Description An F-clamp is a type of clamp. It is also known as a bar clamp or speed clamp. An F-clamp consists of two horizontal bars joined together by a vertical bar. This gives the clamp an appearance of the letter F. There is a large screw on the lower bar to allow for the clamp to be tightened. F-clamps are adjustable, which allows for them to be used on larger scale objects without the need for a large screw. Use This tool is used in woodworking while more permanent attachment is being made with screws or glue, or in metalworking to hold pieces together for welding or bolting. An F-clamp is also a simple mechanical device u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-ring
A D-ring is an item of hardware, usually a tie-down metal ring shaped like a capital letter 'D' used primarily as a lashing or attachment point. The term is found interchangeably spelled in different forms, such as: ''D ring'', ''D-ring'' or ''dee-ring''. A D-ring may be used at the end of a leather or fabric strap, or may be secured to a surface with a metal or fabric strap; though there are D-rings with a middle body designed to be welded to steel. Ideally, a D-ring swings freely after it has been secured. D-rings may vary in composition, geometry, weight, finish and load (rated) capacity. Though there are differences, a weld-on pivoting link is commonly called a D-ring. To minimize obstruction when the D-ring is not in use, recessed tie-down rings are designed that accommodate the D-ring so it is flush to the surface. There are some non-recessed designs that have an adhesive base. Work load limits are specified where appropriate. For D-rings used in the bed of a truck to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-frame
An A-frame is a basic structure designed to bear a Structural load, load in a lightweight economical manner. The simplest form of an A-frame is two similarly sized Beam (structure), beams, arranged in an angle of 45 degrees or less, attached at the top, like an uppercase letter 'A'. These materials are often wooden or steel beams attached at the top by rope, welding, Adhesive, gluing, or riveting. A-frames can be used as-is, as part of Shear legs, shears, or set up in a row along a longitudinal beam for added stability, as in a saw horse. More complex structures will often have crossmembers connecting the A-frames at different angles,"A-frame" (2009). ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0). Oxford University Press. forming a truss. Other structures that use A-frames * A-frame house * A-frame hydroponics system * A-frame contour measuring spirit level * A frame camping tent * A-frame complex, a motif in chemistry * Folding ladder * Double wishbone susp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
