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Perimeter Security
Perimeter security refers to natural barriers or constructed fortifications designed either to prevent intruders from entering an area or to contain individuals within an enclosed area. Purpose Since at least the Roman Empire, fortifications, walls and barriers have been an important part of protecting sovereign territories and private property. Perimeter security is designed with the primary purpose to either keep intruders out or captives contained within the area the boundary surrounds. Both natural and manmade barriers can serve as perimeter security. Governments use perimeter security not only for the safety of their citizens, but to control the flow of commerce and immigration, as well as to protect vital infrastructure from attackers. Property owners and organizations of all sizes use various man-made technology to achieve varying degrees of perimeter security. History One of the earliest known instances of perimeter security on a large scale is Hadrian's Wall in the Roma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Natural Barrier
A natural barrier is a physical feature that protects or hinders travel through or over. Mountains, swamps, deserts and ice fields are among the clearest examples of natural barriers. Rivers are a more ambiguous example, as they may obstruct large-scale movement across them (especially by armies) but may facilitate smaller-scale movement along them in boats, once some of the people in the region have developed the relevant technologies. Seas have likewise been an obstacle at first, then a convenient medium for transport along coastlines, and finally a medium for intercontinental transport. Water can protect island states like the Venetian Republic or Great Britain from dangerous neighbors, and simultaneously connect them to the wider world. Natural barriers have been important factors in human history, by obstructing migration and invasion. For example, Jared Diamond argues that West European nations have been the dominant powers of the last 500 years because Europe's many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Concertina Wire
Concertina wire or Dannert wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina. In conjunction with plain barbed wire (and/or razor wire/tape) and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, or at international borders. During World War I, soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today, it is factory made. Origins In World War I, barbed wire obstacles were made by stretching lengths of barbed wire between stakes of wood or iron. At its simplest, such a barrier would resemble a fence as might be used for agricultural purposes. The double apron fence comprised a line of pickets with wires running diagonally down to points on the ground either side of the fence. Horizontal wires were attached to these diagonals. More elaborate an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Desert
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or Semi-arid climate, semi-arid. This includes much of the Polar regions of Earth, polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. Deserts are formed by weathering processes as large variations in temperature between day and night strain the Rock (geology), rocks, which consequently break in pieces. Although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter, and the resulting frag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Amazon Rainforest
The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin encompasses , of which are covered by the rainforest. This region includes territory belonging to nine nations and 3,344 Indigenous territory (Brazil), indigenous territories. The majority of the forest, 60%, is in Amazônia Legal, Brazil, followed by Peruvian Amazonia, Peru with 13%, Amazon natural region, Colombia with 10%, and with minor amounts in Bolivia, Ecuador, French Guiana, Guyana, Suriname, and Venezuela. Four nations have "Amazonas (other), Amazonas" as the name of one of their first-level administrative regions, and France uses the name "Guiana Amazonian Park" for French Guiana's protected rainforest area. The Amazon represents over half of the total area of remaining rainforests on Earth, and comprises the largest a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the northernmost, westernmost, and easternmost (the Aleutian Islands cross the 180th meridian into the eastern hemisphere) state in the United States. It borders the Canadian territory of Yukon and the province of British Columbia to the east. It shares a western maritime border, in the Bering Strait, with Russia's Chukotka Autonomous Okrug. The Chukchi and Beaufort Seas of the Arctic Ocean lie to the north, and the Pacific Ocean lies to the south. Technically, it is a semi-exclave of the U.S., and is the largest exclave in the world. Alaska is the largest U.S. state by area, comprising more total area than the following three largest states of Texas, California, and Montana combined, and is the seventh-largest subnational division i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Canada, to New Mexico in the Southwestern United States. Depending on differing definitions between Canada and the U.S., its northern terminus is located either in northern British Columbia's Terminal Range south of the Liard River and east of Rocky Mountain Trench, the Trench, or in the northeastern foothills of the Brooks Range/British Mountains that face the Beaufort Sea coasts between the Canning River (Alaska), Canning River and the Firth River across the Alaska-Yukon border. Its southernmost point is near the Albuquerque metropolitan area, Albuquerque area adjacent to the Rio Grande rift and north of the Sandia–Manzano Mountains, Sandia–Manzano Mountain Range. Being the easternmost portion of the North American Cordillera, the Rockie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Normandy Landings
The Normandy landings were the landing operations and associated airborne operations on 6 June 1944 of the Allies of World War II, Allied invasion of Normandy in Operation Overlord during the Second World War. Codenamed Operation Neptune and often referred to as D-Day (after D-Day (military term), the military term), it is the largest seaborne invasion in history. The operation began the liberation of France, and the rest of Western Europe, and laid the foundations of the Allied victory on the Western Front (World War II), Western Front. Planning for the operation began in 1943. In the months leading up to the invasion, the Allies conducted a substantial military deception, codenamed Operation Bodyguard, to mislead the Germans as to the date and location of the main Allied landings. The weather on the day selected for D-Day was not ideal, and the operation had to be delayed 24 hours; a further postponement would have meant a delay of at least two weeks, as the planners had re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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English Channel
The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest Sea lane, shipping area in the world. It is about long and varies in width from at its widest to at its narrowest in the Strait of Dover."English Channel". ''The Columbia Encyclopedia'', 2004. It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some . The Channel aided the United Kingdom in becoming a naval superpower, serving as a natural defence against invasions, such as in the Napoleonic Wars and in the World War II, Second World War. The northern, English coast of the Channel is more populous than the southern, French coast. The major languages spoken in this region are English language, English and French language, French. Names Roman historiography, Roman sources as (or , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Himalayas
The Himalayas, or Himalaya ( ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than list of highest mountains on Earth, 100 peaks exceeding elevations of above sea level lie in the Himalayas. The Himalayas abut on or cross territories of Himalayan states, six countries: Nepal, China, Pakistan, Bhutan, India and Afghanistan. The sovereignty of the range in the Kashmir region is disputed among India, Pakistan, and China. The Himalayan range is bordered on the northwest by the Karakoram and Hindu Kush ranges, on the north by the Tibetan Plateau, and on the south by the Indo-Gangetic Plain. Some of the world's major rivers, the Indus River, Indus, the Ganges river, Ganges, and the Yarlung Tsangpo River, Tsangpo–Brahmaputra River, Brahmaputra, rise in the vicinity of the Himalayas, and their combined drainage basin is home to some 6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Flare
A flare, also sometimes called a fusée, fusee, or bengala, bengalo in several European countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by flare guns or handheld percussive tubes. Origin The earliest recorded use of gunpowder for signaling purposes was the 'signal bomb' used by the Chinese Song dynasty, Song Dynasty (960–1279) as the Mongol-led Yuan dynasty, Yuan Dynasty (1271–1368) besieged Yangzhou in 1276. These soft-shelled bombs, timed to explode in midair, were used to send messages to a detachment of troops far in the distance. Another mention of the signal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Watchtower
A watchtower or guardtower (also spelt watch tower, guard tower) is a type of military/paramilitary or policiary tower used for guarding an area. Sometimes fortified, and armed with heavy weaponry, especially historically, the structures are built in areas of established control. These include military bases, cities occupied by military forces, prisons and more. A common equipment is searchlights. It differs from a regular tower in that its primary use is military/policiary and from a turret in that it is usually a freestanding structure. Its main purpose is to provide a high, safe place from which a sentinel or guard may observe the surrounding area. In some cases, non-military towers, such as religious towers, may also be used as watchtowers. Similar constructions include: observation towers, which are generally civilian structures, and control towers, used on airports or harbours. History Military watchtowers The Romans built numerous towers as part of a sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |