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Echelon Formation
An echelon formation () is a (usually military) formation in which its units are arranged diagonally. Each unit is stationed behind and to the right (a "right echelon"), or behind and to the left ("left echelon"), of the unit ahead. The name of the formation comes from the French word échelon, meaning a rung of a ladder, which describes the shape that this formation has when viewed from above or below. Military formation Use of the formation dates back to ancient infantry and cavalry warfare, as an alternative to column, line-abreast, or phalanx (box) formations. One of its earliest uses was at the Battle of Leuctra, when the Thebans attacked the Spartan right with a column 48 men deep while their weaker center and right were repelled. The echelon formation may have been used by Hannibal at the Battle of Cannae, Alexander the Great at the Battle of Gaugamela, Frederick II of Prussia, and the Confederate army at the Battle of Gettysburg. The tactic still persists and is reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tank
A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engine; usually their main armament is mounted in a turret. They are a mainstay of modern 20th and 21st century ground forces and a key part of combined arms combat. Modern tanks are versatile mobile land weapons platforms whose main armament is a large-caliber tank gun mounted in a rotating gun turret, supplemented by machine guns or other ranged weapons such as anti-tank guided missiles or rocket launchers. They have heavy vehicle armour which provides protection for the crew, the vehicle's munition storage, fuel tank and propulsion systems. The use of tracks rather than wheels provides improved operational mobility which allows the tank to overcome rugged terrain and adverse conditions such as mud and ice/snow better than wheeled vehicles, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echelon Faults
ECHELON, originally a secret government code name, is a surveillance program (signals intelligence/SIGINT collection and analysis network) operated by the five signatory states to the UKUSA Security Agreement:Given the 5 dialects that use the terms, UKUSA can be pronounced from "You-Q-SA" to "Oo-Coo-SA", AUSCANNZUKUS can be pronounced from "Oz-Can-Zuke-Us" to "Orse-Can-Zoo-Cuss". :From Talk:UKUSA Agreement: "Per documents officially released by both the Government Communications Headquarters and the National Security Agency, this agreement is referred to as the UKUSA Agreement. This name is subsequently used by media sources reporting on the story, as written in new references used for the article. The NSA press release provides a pronunciation guide, indicating that "UKUSA" should not be read as two separate entities.(National Security Agency)" Australia, Canada, New Zealand, the United Kingdom and the United States, also known as the Five Eyes. Created in the late 1960s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V Formation
A V formation is the symmetric V-shaped flight formation of flights of geese, swans, ducks, and other migratory birds, improving their energy efficiency. Usually, large birds fly in this formation since smaller birds create more complex wind currents that are hard for the birds in the back to take advantage of. V formations also improve the fuel efficiency of aircraft and are used on military flight missions. Aerodynamics The V formation possibly improves the efficiency of flying birds, particularly over long migratory routes. This allows the birds after to take the upwash lift force due to the wingtip vortices at the tip of the wings of the lead bird. The upwash assists each bird in supporting its own weight in flight, in the same way a glider can climb or maintain height indefinitely in rising air. The birds are able to find the place where the uplift is the most desirable either by sight or by sensing the airflow by their feathers, scientists suspect. Previous studies found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird Migration
Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by humans, and is driven primarily by the availability of food. It occurs mainly in the northern hemisphere, where birds are funneled onto specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea. Migration of species such as storks, turtle doves, and swallows was recorded as many as 3,000 years ago by Ancient Greek authors, including Homer and Aristotle, and in the Book of Job. More recently, Johannes Leche began recording dates of arrivals of spring migrants in Finland in 1749, and modern scientific studies have used techniques including bird ringing and satellite tracking to trace migrants. Threats to migratory birds have grown with habitat destruction, especially of stopover and wintering sites, as wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duck
Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form taxon; they do not represent a monophyletic group (the group of all descendants of a single common ancestral species), since swans and geese are not considered ducks. Ducks are mostly aquatic birds, and may be found in both fresh water and sea water. Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules and coots. Etymology The word ''duck'' comes from Old English 'diver', a derivative of the verb 'to duck, bend down low as if to get under something, or dive', because of the way many species in the dabbling duck group feed by upending; compare with Dutch and German 'to dive'. This word replaced Old English / 'duck', possibly to avoid confusion with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goose
A goose ( : geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera ''Anser'' (the grey geese and white geese) and '' Branta'' (the black geese). Some other birds, mostly related to the shelducks, have "goose" as part of their names. More distantly related members of the family Anatidae are swans, most of which are larger than true geese, and ducks, which are smaller. The term "goose" may refer to either a male or female bird, but when paired with "gander", refers specifically to a female one (the latter referring to a male). Young birds before fledging are called goslings. The collective noun for a group of geese on the ground is a gaggle; when in flight, they are called a skein, a team, or a wedge; when flying close together, they are called a plump. Etymology The word "goose" is a direct descendant of,''*ghans-''. In Germanic languages, the root gave Old English ''gōs'' with the plural ''gēs'' and ''gandres'' (b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birdwatching
Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device like binoculars or a telescope, by listening for bird sounds, or by watching public webcams. Most birdwatchers pursue this activity for recreational or social reasons, unlike ornithologists, who engage in the study of birds using formal scientific methods. Birding, birdwatching, and twitching The first recorded use of the term ''birdwatcher'' was in 1901 by Edmund Selous; ''bird'' was introduced as a verb in 1918. The term ''birding'' was also used for the practice of ''fowling'' or hunting with firearms as in Shakespeare's '' The Merry Wives of Windsor'' (1602): "She laments sir... her husband goes this morning a-birding." The terms ''birding'' and ''birdwatching'' are today used by some interchangeably, although some participants prefer ''birding'', partly because it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
En Echelon1
En or EN may refer to: Businesses * Bouygues (stock symbol EN) * Esquimalt and Nanaimo Railway (reporting mark EN, but now known as Southern Railway of Vancouver Island) * Euronews, a news television and internet channel Language and writing * En or N, the 14th letter of the Roman alphabet * EN (cuneiform), the mark in Sumerian cuneiform script for a High Priest or Priestess meaning "lord" or "priest" * En (Cyrillic) (Н, н), a letter of the Cyrillic alphabet, equivalent to the Roman letter "n" * En (digraph), ‹en› used as a phoneme * En (typography), a unit of width in typography ** en dash, a dash one en long * En language, a language spoken in northern Vietnam * English language (ISO 639-1 language code en) Organisations * Eastern National, a US organization providing educational products to National Park visitors * English Nature, a former UK government conservation agency * Envirolink Northwest, an environmental organization in England Religion * En (deity) in Albania ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riot Police
Riot police are police who are organized, deployed, trained or equipped to confront crowds, protests or riots. Riot police may be regular police who act in the role of riot police in particular situations or they may be separate units organized within or in parallel to regular police forces. Riot police are used in a variety of different situations and for a variety of different purposes. They may be employed to control riots as their name suggests, to disperse or control crowds, to maintain public order or discourage criminality, or to protect people or property. Riot gear Riot police often use special equipment termed riot gear to help protect themselves and attack others, oftentimes simultaneously. Riot gear typically includes personal armor, batons, and riot helmets. Many riot police teams also deploy specialized less-than-lethal weapons, such as pepper spray, tear gas, rifles that fire rubber bullets, stun grenades, water cannons and Long Range Acoustic Devices. L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leapfrogging (infantry)
Bounding overwatch (also known as leapfrogging, moving overwatch, or "The Buddy System") is a military Military tactics, tactic of alternating movement of coordinated units to allow, if necessary, suppressive fire in support of offensive forward "fire and movement" or defensive "center peel" disengagement. As members of a unit (element to platoon level) take an overwatch (military tactic), overwatch posture, other members advance to cover; these two groups continually switch roles as they close with the enemy. This process may be done by "leapfrogging" with fireteams, but is usually done within fireteams along a squad/platoon battle line to simulate an overwhelming movement towards the enemy and make it more difficult for the enemy to distinguish specific targets. This military tactic takes continuous training and focused coordination to be effectively practiced on the modern battlefield. It was first developed in World War II, when the prevalence of man-portable automatic weapo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platoon
A platoon is a military unit typically composed of two or more squads, sections, or patrols. Platoon organization varies depending on the country and the branch, but a platoon can be composed of 50 people, although specific platoons may range from 10 to 100 people. A platoon is typically the smallest military unit led by a commissioned officer. The platoon leader is usually a junior officer—a second or first lieutenant or an equivalent rank. The officer is usually assisted by a platoon sergeant. Rifle platoons normally consist of a small platoon headquarters and three or four sections (Commonwealth) or squads (United States). In some armies, platoon is used throughout the branches of the army. In a few armies, such as the French Army, a platoon is specifically a cavalry unit, and the infantry use "section" as the equivalent unit. A unit consisting of several platoons is called a company or a battery. Etymology According to Merriam-Webster, "The term was first used in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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