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Free-space Optical Communication
Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. "Free space" means air, outer space, vacuum, or something similar. This contrasts with using solids such as optical fiber cable. The technology is useful where the physical connections are impractical due to high costs or other considerations. History Optical communications, in various forms, have been used for thousands of years. The ancient Greeks used a coded alphabetic system of signalling with torches developed by Cleoxenus, Democleitus and Polybius. In the modern era, semaphores and wireless solar telegraphs called heliographs were developed, using coded signals to communicate with their recipients. In 1880, Alexander Graham Bell and his assistant Charles Sumner Tainter created the photophone, at Bell's newly established Volta Laboratory in Washington, DC. Bell considered it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Washington, DC
) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, National Cathedral , image_flag = Flag of the District of Columbia.svg , image_seal = Seal of the District of Columbia.svg , nickname = D.C., The District , image_map = , map_caption = Interactive map of Washington, D.C. , coordinates = , subdivision_type = Country , subdivision_name = , established_title = Residence Act , established_date = 1790 , named_for = George Washington, Christopher Columbus , established_title1 = Organized , established_date1 = 1801 , established_title2 = Consolidated , established_date2 = 1871 , established_title3 = Home Rule Ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Wall
The Atlantic Wall (german: link=no, Atlantikwall) was an extensive system of coastal defences and fortifications built by Nazi Germany between 1942 and 1944 along the coast of continental Europe and Scandinavia as a defence against an anticipated Allied invasion of Nazi-occupied Europe from the United Kingdom, during World War II. The manning and operation of the Atlantic Wall was administratively overseen by the German Army, with some support from ''Luftwaffe'' ground forces. The ''Kriegsmarine'' (German Navy) maintained a separate coastal defence network, organised into a number of sea defence zones. Hitler ordered the construction of the fortifications in 1942 through his Führer Directive No. 40. More than half a million French workers were drafted to build it. The wall was frequently mentioned in Nazi propaganda, where its size and strength were usually exaggerated. The fortifications included colossal coastal guns, batteries, mortars, and artillery, and thousands o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Zeiss AG
Carl Zeiss AG (), branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid the foundation for today's multi-national company. The current company emerged from a reunification of Carl Zeiss companies in East and West Germany with a consolidation phase in the 1990s. ZEISS is active in four business segments with approximately equal revenue (Industrial Quality and Research, Medical Technology, Consumer Markets and Semiconductor Manufacturing Technology) in almost 50 countries, has 30 production sites and around 25 development sites worldwide. Carl Zeiss AG is the holding of all subsidiaries within Zeiss Group, of which Carl Zeiss Meditec AG is the only one that is traded at the stock market. Carl Zeiss AG is owned by the foundation Carl-Zeiss-Stiftung. The Zeiss Group has its headquarters in southern Germany, in the smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fighting occurring throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died in genocides within the Ottoman Empire and in the 1918 influenza pandemic, which was exacerbated by the movement of combatants during the war. Prior to 1914, the European great powers were divided between the Triple Entente (comprising France, Russia, and Britain) and the Triple Alliance (containing Germany, Austria-Hungary, and Italy). Tensions in the Balkans came to a head on 28 June 1914, following the assassination of Archduke Franz Ferdin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trench Warfare
Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became archetypically associated with World War I (1914–1918), when the Race to the Sea rapidly expanded trench use on the Western Front starting in September 1914.. Trench warfare proliferated when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire. The area between opposing trench lines (known as " no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties. The development of armoured ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germany Blinker Signal Lamp - National World War I Museum - Kansas City, MO - DSC07704
Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the south. Its 16 constituent states have a total population of over 84 million in an area of . It borders Denmark to the north, Poland and Czechia to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The nation's capital and most populous city is Berlin and its main financial centre is Frankfurt; the largest urban area is the Ruhr. Settlement in what is now Germany began in the Lower Paleolithic, with various tribes inhabiting it from the Neolithic onward, chiefly the Celts. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity. A region named Germania was documented before AD 100. In 962, the Kingdom of Germany formed the bulk of the H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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