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A.K. Erlang
Agner Krarup Erlang (1 January 1878 – 3 February 1929) was a Danish mathematician, statistician and engineer, who invented the fields of traffic engineering and queueing theory. By the time of his relatively early death at the age of 51, Erlang had created the field of telephone networks analysis. His early work in scrutinizing the use of local, exchange and trunk telephone line usage in a small community to understand the theoretical requirements of an efficient network led to the creation of the Erlang formula, which became a foundational element of modern telecommunication network studies. Life Erlang was born at Lønborg, near Tarm, in Jutland. He was the son of a schoolmaster, and a descendant of Thomas Fincke on his mother's side. At age 14, he passed the Preliminary Examination of the University of Copenhagen with distinction, after receiving dispensation to take it because he was younger than the usual minimum age. For the next two years he taught alongside his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denmark
) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark , established_title = History of Denmark#Middle ages, Consolidation , established_date = 8th century , established_title2 = Christianization , established_date2 = 965 , established_title3 = , established_date3 = 5 June 1849 , established_title4 = Faroese home rule , established_date4 = 24 March 1948 , established_title5 = European Economic Community, EEC 1973 enlargement of the European Communities, accession , established_date5 = 1 January 1973 , established_title6 = Greenlandic home rule , established_date6 = 1 May 1979 , official_languages = Danish language, Danish , languages_type = Regional languages , languages_sub = yes , languages = German language, GermanGerman is recognised as a protected minority language in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, with its main goal being to understand how the universe behaves. "Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logarithm
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 of is , or . The logarithm of to ''base'' is denoted as , or without parentheses, , or even without the explicit base, , when no confusion is possible, or when the base does not matter such as in big O notation. The logarithm base is called the decimal or common logarithm and is commonly used in science and engineering. The natural logarithm has the number as its base; its use is widespread in mathematics and physics, because of its very simple derivative. The binary logarithm uses base and is frequently used in computer science. Logarithms were introduced by John Napier in 1614 as a means of simplifying calculations. They were rapidly adopted by navigators, scientists, engineers, surveyors and others to perform high-a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manhole
A manhole (utility hole, maintenance hole, or sewer hole) is an opening to a confined space such as a shaft, utility vault, or large vessel. Manholes are often used as an access point for an underground public utility, allowing inspection, maintenance, and system upgrades. The majority of underground services have manholes, including water, sewers, telephone, electricity, storm drains, district heating, and gas. Manholes are generally found in urban areas, in streets and occasionally under sidewalks. In rural and undeveloped areas, services such as telephone and electricity are usually carried on utility poles or even pylons rather than underground. In Australia, ''manhole'' also commonly refers to an access hatch used to get access from a room or hallway into the ceiling cavity of a building. These manholes are typically around square. Construction Manhole closings are protected by a grating or manhole cover, a flat plug designed to prevent accidental or unauthorize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Call
A telephone call is a connection over a telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and internet. The idea was revolutionized in the 1920s, as more and more ... between the called party and the calling party. First telephone call The first telephone call was made on March 10, 1876, by Alexander Graham Bell. Bell demonstrated his ability to "talk with electricity" by transmitting a call to his assistant, Thomas Watson. The first words transmitted were "Mr Watson, come here. I want to see you." This event has been called Bell's "greatest success", as it demonstrated the first successful use of the telephone. Although it was his greatest success, he refused to have a telephone in his own home because it was something he invented by mistake and saw it as a distraction from his main studies. Information transmission A telephone cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Switchboard
A telephone switchboard was a device used to connect circuits of telephones to establish telephone calls between users or other switchboards, throughout the 20th century. The switchboard was an essential component of a manual telephone exchange, and was operated by switchboard operators who used electrical cords or switches to establish the connections. The electromechanical automatic telephone exchange, invented by Almon Strowger in 1888, gradually replaced manual switchboards in central telephone exchanges around the world. In 1919, the Bell System in Canada also adopted automatic switching as its future technology, after years of reliance on manual systems. Nevertheless, many manual branch exchanges remained operational into the second half of the 20th century in many enterprises. Later electronic devices and computer technology gave the operator access to an abundance of features. A private branch exchange (PBX) in a business usually has an attendant console, or an auto-atten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Exchange
A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers. In historical perspective, telecommunication terms have been used with different semantics over time. The term ''telephone exchange'' is often used synonymously with ''central office'', a Bell System term. Often, a ''central office'' is defined as a building used to house the inside plant equipment of potentially several telephone exchanges, each serving a certain geographical area. Such an area has also been referred to as the exchange or exchange area. In North America, a central office location may also be identified as a ''wire center'', designating a facility to which a telephone is connected and obtains dial tone. For business and billing purposes, telecommunication carriers defi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switchboard Operator
In the early days of telephony, companies used manual telephone switchboards, and switchboard operators connected calls by inserting a pair of phone plugs into the appropriate jacks. They were gradually phased out and replaced by automated systems, first those allowing direct dialing within a local area, then for long-distance and international direct dialing. Description A typical telephone switchboard has a vertical panel containing an array of jacks with a desk in front. The desk has a row of switches and two rows of plugs attached to cables that retract into the desk when not in use. Each pair of plugs was part of a cord circuit with a switch associated that let the operator participate in the call or ring the circuit for an incoming call. Each jack had a light above it that lit when the customer's telephone receiver was lifted (the earliest systems required the customer to hand-crank a magneto to alert the central office and, later, to "ring off" the completed call). Lines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institution Of Electrical Engineers
The Institution of Electrical Engineers (IEE) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. It began in 1871 as the Society of Telegraph Engineers. In 2006, it changed its name to the Institution of Engineering and Technology (IET). Notable past presidents have included Lord Kelvin (1889), Sir Joseph Swan (1898) and Sebastian de Ferranti (1910–11). Notable chairmen include John M. M. Munro (1910–11). History The IEE was founded in 1871 as the Society of Telegraph Engineers, changed its name in 1880 to the Society of Telegraph Engineers and Electricians and changed to the Institution of Electrical Engineers in 1888. It was Incorporated by a Royal Charter in 1921. In 1988 the Institution of Electrical Engineers (IEE) merged with the Institution of Electronic and Radio Engineers (IERE), originally the British Institution of Radio Engineers (Brit IRE) founded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Bell Telephone Company
The International Bell Telephone Company (IBTC) of Brussels, Belgium, was created in 1879 by the Bell Telephone Company of Boston, Massachusetts, a precursor entity to the American Telephone and Telegraph Company (AT&T), initially to sell imported telephones and switchboards in Continental Europe.Bob's Old PhonesEuropean Bell and Western Electric Phones Bob's Old Phones website. Retrieved August 17, 2010. IBTC evolved into a notable European telephone service provider and manufacturer, with major operations in several countries. As a result of anti-trust actions in the U.S., AT&T, its parent, sold its entire European division and IBTC's subsidiaries to the International Telephone & Telegraph Company in 1925, ending a 46-year presence on the continent. Organization In 1879 Gardiner Hubbard, father-in-law of Alexander Graham Bell and the first president of the Bell Telephone Company, founded the International Bell Telephone Company for promoting sales of its telephone equipmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corporate Spin-off
A corporate spin-off, also known as a spin-out, or starburst or hive-off, is a type of corporate action where a company "splits off" a section as a separate business or creates a second incarnation, even if the first is still active. Characteristics Spin-offs are divisions of companies or organizations that then become independent businesses with assets, employees, intellectual property, technology, or existing products that are taken from the parent company. Shareholders of the parent company receive equivalent shares in the new company in order to compensate for the loss of equity in the original stocks. However, shareholders may then buy and sell stocks from either company independently; this potentially makes investment in the companies more attractive, as potential share purchasers can invest narrowly in the portion of the business they think will have the most growth. In contrast, divestment can also sever one business from another, but the assets are sold off rather t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TDC A/S
TDC Holding A/S or TDC Group (formerly Tele Danmark Communications) is a Danish telecommunications company dating back to 1879. TDC Group is the largest telecommunications company in Denmark. The company's headquarters are located in Copenhagen. TDC Holding is the holding company of two separate companies which were spun-off from TDC; Nuuday A/S and TDC NET A/S. All consumer related services and brands were placed under Nuuday, and the ownership and maintenance of physical infrastructure of mobile antennas as well as coax and fibre optical lines were placed under TDC NET. History In 1879, ''Kjøbenhavns By- og Hustelegraf'' was established by telegraph engineer Severin Lauritzen and telegraphist Th. Thaulow. The company set up private telephone lines over shorter distances, for example between offices and factories. In addition, it offered telegraph service in Copenhagen using small telegraph stations around the city that could communicate by telephone. On 21 August 1882, Car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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