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Helmets
A helmet is a form of protective gear worn to protect the head. More specifically, a helmet complements the skull in protecting the human brain. Ceremonial or symbolic helmets (e.g., a policeman's helmet in the United Kingdom) without protective function are sometimes worn. Soldiers wear combat helmets, often made from Kevlar or other lightweight synthetic fibers. The word ''helmet'' is derived from ''helm'', an Old English word for a protective head covering. Helmets are used for recreational activities and sports (e.g., jockeys in horse racing, American football, ice hockey, cricket, baseball, camogie, hurling and rock climbing); dangerous work activities such as construction, mining, riot police, military aviation, and in transportation (e.g. motorcycle helmets and bicycle helmets). Since the 1990s, most helmets are made from resin or plastic, which may be reinforced with fibers such as aramids. Designs Some British gamekeepers during the 18th and 19th centuries wore hel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicycle Helmet
A bicycle helmet is a type of helmet designed to attenuate impacts to the head of a cyclist in falls while minimizing side effects such as interference with peripheral vision. There is ongoing scientific research into the degree of protection offered by bicycle helmets in the event of an accident, and the effects of helmet wearing on cyclist and motor vehicle driver behaviour. There is active debate over what can be concluded from available studies, and on whether the use of helmets by cyclists should be promoted or mandated, either just for children, or for cyclists of all ages. In particular the debate over bicycle helmet laws has been intense and occasionally bitter, often based not only on differing interpretations of the scientific and other academic literature, but also on differing assumptions and interests of various parties. History History of designs A cycle helmet should generally be light in weight and provide ample ventilation because cycling can be an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorcycle Helmet
A motorcycle helmet is a type of helmet used by motorcycle riders. Motorcycle helmets contribute to motorcycle safety by protecting the rider's head in the event of an impact. They reduce the risk of head injury by 69% and the risk of death by 42%. Their use is required by law in many countries. Motorcycle helmets consist of a Polystyrene, polystyrene foam inner shell that absorbs the shock of an impact, and a protective plastic outer layer. Several variations exist, notably helmets that cover the chin area and helmets that do not. Some helmets provide additional conveniences, such as ventilation, face shields, sun visors, ear protection or intercom. Origins The origins of the crash helmet date back to the Brooklands race track in early 1914, when a medical officer, Dr. Eric Gardner, noticed he was seeing a motor cyclist with head injuries about every two weeks. He got a Mr. Moss of Bethnal Green to make canvas and shellac helmets stiff enough to stand a heavy blow and smooth e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Football Helmet
The football helmet is a piece of protective equipment used mainly in gridiron football, although a structural variation has occasional use in Australian rules football. It consists of a hard plastic shell with thick padding on the inside, a face mask made of one or more plastic-coated metal bars, and a chinstrap. Each position has a different type of face mask to balance protection and visibility, and some players add polycarbonate visors to their helmets, which are used to protect their eyes from glare and impacts. Helmets are a requirement at all levels of organized football, except for non-tackle variations such as flag football. Although they are protective, players can and do still suffer head injuries such as concussions. Football helmets have changed dramatically with the modernization of the sport to facilitate technological changes and to improve the safety of the game. Despite lower rates of some injuries, serious traumas to the head are still common, and determini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Custodian Helmet
The custodian helmet is a type of helmet worn predominantly by male police officers in the United Kingdom, within England and Wales, and certain other places around the world. History The custodian helmet is the headgear traditionally worn by male police constables and sergeants while on foot patrol in England and Wales. Officers of all ranks in most forces are also issued a flat, peaked cap that is worn on mobile patrol in a vehicle. Ranks above sergeant wear the peaked cap only. However, some inspectors wear the custodian helmet, but with two silver bands around the base (to match the two pips worn as rank insignia) to denote their position. Claimed by some sources to have been based on the spiked pickelhaube worn by the Prussian Army, it was first adopted by the London Metropolitan Police in 1863 to replace the "stovepipe" top hat worn since 1829. In 1863, the Metropolitan Police replaced the previous uniform of white trousers, swallow-tailed coat and top hat in favour of ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combat Helmet
A combat helmet or battle helmet is a type of helmet. It is a piece of personal armor designed specifically to protect the head during combat. Modern combat helmets are mainly designed to protect from shrapnel and fragments, offer some protection against small arms, and offer a mounting point for devices such as night-vision goggles and communications equipment. History Helmets are among the oldest forms of personal protective equipment and are known to have been worn by the Akkadians/Sumerians in the 23rd century BC, Mycenaean Greeks since the 17th century BC, the Assyrians around 900 BC, ancient Greeks and Romans, throughout the Middle Ages, and up to the end of the 17th century by many combatants. Their materials and construction became more advanced as weapons became more and more powerful. Initially constructed from leather and brass, and then bronze and iron during the Bronze and Iron Ages, they soon came to be made entirely from forged steel in many societies afte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hockey Helmet
A hockey helmet is worn by players of ice hockey, inline hockey, and bandy Bandy is a winter sport and ball sport played by two teams wearing ice skates on a large ice surface (either indoors or outdoors) while using sticks to direct a ball into the opposing team's goal. The international governing body for bandy is ... to help protect the head from potential injury when hit by the hockey puck, puck, hockey stick, sticks, hockey skate, skates, boards, other players, or the ice. The shell of a hockey helmet is generally made of a substance called vinyl nitrile that disperses force from the point of contact, while the liner may be made of either vinyl nitrile foam, polypropylene, expanded polypropylene foam, or other material to absorb the energy, to reduce the chances of concussion. Hockey helmets grip the head from inside by cupping the back of head, or the External occipital protuberance, occipital protuberance. Helmet manufacturers will have a chart that relates their he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cricket Helmet
Helmets in cricket were developed in the 20th century. History There are recorded instances of cricketers using scarves and padded caps to protect themselves throughout cricket history. Patsy Hendren was one of the first to use a self-designed protective hat in the 1930s. Helmets were not in common use until the 1970s. The first helmets were seen in World Series Cricket, with Dennis Amiss being the first player to consistently wear a helmet which was a customised motorcycle helmet. Mike Brearley was another player who wore his own design. Tony Greig was of the opinion that they would make cricket more dangerous by encouraging bowlers to bounce the batsmen. Graham Yallop of Australia was the first to wear a protective helmet to a test match on 17 March 1978, when playing against West Indies at Bridgetown. Later Dennis Amiss of England popularised it in Test cricket. Helmets began to be widely worn thereafter. The last batsmen at the highest (Test match) level to never wear a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batting Helmet
A batting helmet is worn by batters in the game of baseball or softball. It is meant to protect the batter's head from errant pitches thrown by the pitcher. A batter who is " hit by pitch," due to an inadvertent wild pitch or by intent, may be seriously, even fatally, injured. Early concepts (1905–1920s) In 1905, Mogridge"Baseball Batting Helmets - A History" ''Sports Safety Blog'', September 2009 created the first crude protective headgear and was granted patent No. 780899 for a "head protector." This first attempt at a batting helmet was said to look like an "inflatable boxing glove that wrapped around the hitters head." [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hurling
Hurling ( ga, iománaíocht, ') is an outdoor team game of ancient Gaelic Irish origin, played by men. One of Ireland's native Gaelic games, it shares a number of features with Gaelic football, such as the field and goals, the number of players and much terminology. The same game played by women is called camogie ('), which shares a common Gaelic root. The objective of the game is for players to use an ash wood stick called a hurley (in Irish a ', pronounced or ) to hit a small ball called a ' between the opponent's goalposts either over the crossbar for one point or under the crossbar into a net guarded by a goalkeeper for three points. The ' can be caught in the hand and carried for not more than four steps, struck in the air or struck on the ground with the hurley. It can be kicked, or slapped with an open hand (the hand pass), for short-range passing. A player who wants to carry the ball for more than four steps has to bounce or balance the ' on the end of the stick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resin
In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on naturally occurring resins. Plants secrete resins for their protective benefits in response to injury. The resin protects the plant from insects and pathogens. Resins confound a wide range of herbivores, insects, and pathogens, while the volatile phenolic compounds may attract benefactors such as parasitoids or predators of the herbivores that attack the plant. Composition Most plant resins are composed of terpenes. Specific components are alpha-pinene, beta-pinene, delta-3 carene, and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene, and delta-cadinene. Some resins also contain a high proportion of resin acids. Rosins on the other hand are less ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives. 9.2 billion tonnes of plastic are estimated to have been made between 1950 and 2017. More than half this plastic has been produced since 2004. In 2020, 400 million tonnes of plastic were produced. If global trends on plastic demand continue, it is estimated that by 2050 annual global plastic production will reach over 1, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Aviation
Military aviation comprises military aircraft and other flying machines for the purposes of conducting or enabling aerial warfare, including national airlift ( air cargo) capacity to provide logistical supply to forces stationed in a war theater or along a front. Airpower includes the national means of conducting such warfare, including the intersection of transport and warcraft. Military aircraft include bombers, fighters, transports, trainer aircraft, and reconnaissance aircraft. History The first military uses of aviation involved lighter-than-air balloons. During the Battle of Fleurus in 1794, the French observation balloon ''l'Entreprenant'' was used to monitor Austrian troop movements. The use of lighter-than-air aircraft in warfare became prevalent in the 19th century, including regular use in the American Civil War. Lighter-than-air military aviation persisted until shortly after World War II, gradually being withdrawn from various roles as heavier-than-air airc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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