|
Clos Network
In the field of telecommunications, a Clos network is a kind of multistage circuit-switching network which represents a theoretical idealization of practical, multistage switching systems. It was invented by Edson Erwin in 1938 and first formalized by Charles Clos () in 1952. By adding stages, a Clos network reduces the number of crosspoints required to compose a large crossbar switch. A Clos network topology (diagrammed below) is parameterized by three integers ''n'', ''m'', and ''r'': ''n'' represents the number of sources which feed into each of ''r'' ingress stage crossbar switches; each ingress stage crossbar switch has ''m'' outlets; and there are ''m'' middle stage crossbar switches. Circuit switching arranges a dedicated communications path for a connection between endpoints for the duration of the connection. This sacrifices total bandwidth available if the dedicated connections are poorly utilized, but makes the connection and bandwidth more predictable, and only introd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hall's Marriage Theorem
In mathematics, Hall's marriage theorem, proved by , is a theorem with two equivalent formulations: * The combinatorial formulation deals with a collection of finite sets. It gives a necessary and sufficient condition for being able to select a distinct element from each set. * The graph theoretic formulation deals with a bipartite graph. It gives a necessary and sufficient condition for finding a matching that covers at least one side of the graph. Combinatorial formulation Statement Let \mathcal F be a family of finite sets. Here, \mathcal F is itself allowed to be infinite (although the sets in it are not) and to contain the same set multiple times. Let X be the union of all the sets in \mathcal F, the set of elements that belong to at least one of its sets. A transversal for F is a subset of X that can be obtained by choosing a distinct element from each set in \mathcal F. This concept can be formalized by defining a transversal to be the image of an injective function f: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Exchange Equipment
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from el, τῆλε (''tēle'', ''far'') and φωνή (''phōnē'', ''voice''), together meaning ''distant voice''. A common short form of the term is ''phone'', which came into use early in the telephone's history. In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device. This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households. The essential elements of a telephone are a micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omega Network
An Omega network is a network configuration often used in parallel computing architectures. It is an indirect topology that relies on the perfect shuffle interconnection algorithm. Connection architecture An 8x8 Omega network is a multistage interconnection network, meaning that processing elements (PEs) are connected using multiple stages of switches. Inputs and outputs are given addresses as shown in the figure. The outputs from each stage are connected to the inputs of the next stage using a perfect shuffle connection system. This means that the connections at each stage represent the movement of a deck of cards divided into 2 equal decks and then shuffled together, with each card from one deck alternating with the corresponding card from the other deck. In terms of binary representation of the PEs, each stage of the perfect shuffle can be thought of as a cyclic logical left shift; each bit in the address is shifted once to the left, with the most significant bit moving t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fat Tree
The fat tree network is a universal network for provably efficient communication. It was invented by Charles E. Leiserson of the Massachusetts Institute of Technology in 1985. k-ary n-trees, the type of fat-trees commonly used in most high-performance networks, were initially formalized in 1997. In a tree data structure, every branch has the same thickness, regardless of their place in the hierarchy—they are all "skinny" (''skinny'' in this context means low-bandwidth). In a fat tree, branches nearer the top of the hierarchy are "fatter" (thicker) than branches further down the hierarchy. In a telecommunications network, the branches are data links; the varied thickness (bandwidth) of the data links allows for more efficient and technology-specific use. Mesh and hypercube topologies have communication requirements that follow a rigid algorithm, and cannot be tailored to specific packaging technologies. Applications in supercomputers Supercomputers that use a fat tree network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banyan Switch
In electronics, a banyan switch is a complex crossover switch used in electrical or optical switches. It is named for its resemblance to the roots of the banyan tree which cross over in complex patterns. Logical banyan switches are used in logic or signal pathways to crossover switching of signals onto new pathways. They can be mechanical microelectromechanical systems, electrical or nonlinear optics. Their complexity depends on the topology of the individual switches in a switch matrix (how wide it is by how many 'plies' or layers of switches it takes), to implement a desired crossover logic. Design Typical crossover matrices follow this formula: an N×N banyan switch uses (N/2) log2 N elements. Other formulas are used for differing number of crossover layers, and scaling is possible, but becomes very large and complex with large N×N arrays. CAD can be used to take the drudgery out of creating these designs. A banyan network is implemented by interconnecting 2×2 switching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Václav E
Václav () is a Czech male first name of Slavic origin, sometimes translated into English as Wenceslaus or Wenceslas. These forms are derived from the old Slavic/Czech form of this name: Venceslav. Nicknames are: Vašek, Vašík, Venca, Venda For etymology and cognates in other languages, see Wenceslaus. Václav or Vácslav * Saint Wenceslaus I, Duke of Bohemia (907–935 or 929) (svatý Václav) * Václav Noid Bárta, singer, songwriter, and actor *Václav Binovec, Czech film director and screenwriter * Václav Brožík, painter * Václav Hanka, philologist * Václav Havel, last President of Czechoslovakia (1989 – 1992) and first President of the Czech Republic (1993 – 2003) * Václav Holek, Designer of the ZB-26 light machinegun for Zbrojovka Brno and its descendants * Václav Hollar, graphic artist * Vaclav Jelinek, a Czechoslovak spy, who worked in London under the assumed identity of Erwin van Haarlem * Václav Jiráček, Czech actor * Václav Jírů, Czech photograp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binomial Distribution
In probability theory and statistics, the binomial distribution with parameters ''n'' and ''p'' is the discrete probability distribution of the number of successes in a sequence of ''n'' independent experiments, each asking a yes–no question, and each with its own Boolean-valued outcome: ''success'' (with probability ''p'') or ''failure'' (with probability q=1-p). A single success/failure experiment is also called a Bernoulli trial or Bernoulli experiment, and a sequence of outcomes is called a Bernoulli process; for a single trial, i.e., ''n'' = 1, the binomial distribution is a Bernoulli distribution. The binomial distribution is the basis for the popular binomial test of statistical significance. The binomial distribution is frequently used to model the number of successes in a sample of size ''n'' drawn with replacement from a population of size ''N''. If the sampling is carried out without replacement, the draws are not independent and so the resulting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian Jacobaeus
Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χριστός), a translation of the Biblical Hebrew term ''mashiach'' (מָשִׁיחַ) (usually rendered as ''messiah'' in English). While there are diverse interpretations of Christianity which sometimes conflict, they are united in believing that Jesus has a unique significance. The term ''Christian'' used as an adjective is descriptive of anything associated with Christianity or Christian churches, or in a proverbial sense "all that is noble, and good, and Christ-like." It does not have a meaning of 'of Christ' or 'related or pertaining to Christ'. According to a 2011 Pew Research Center survey, there were 2.2 billion Christians around the world in 2010, up from about 600 million in 1910. Today, about 37% of all Christians live in the Ameri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Academic Press
Academic Press (AP) is an academic book publisher founded in 1941. It was acquired by Harcourt, Brace & World in 1969. Reed Elsevier bought Harcourt in 2000, and Academic Press is now an imprint of Elsevier. Academic Press publishes reference books, serials and online products in the subject areas of: * Communications engineering * Economics * Environmental science * Finance * Food science and nutrition * Geophysics * Life sciences * Mathematics and statistics * Neuroscience * Physical sciences * Psychology Well-known products include the ''Methods in Enzymology'' series and encyclopedias such as ''The International Encyclopedia of Public Health'' and the ''Encyclopedia of Neuroscience''. See also * Akademische Verlagsgesellschaft (AVG) — the German predecessor, founded in 1906 by Leo Jolowicz (1868–1940), the father of Walter Jolowicz Walter may refer to: People * Walter (name), both a surname and a given name * Little Walter, American blues harmonica player Marion Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circuit Switching
Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel ( circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit. Circuit switching originated in analog telephone networks where the network created a dedicated circuit between two telephones for the duration of a telephone call. It contrasts with message switching and packet switching used in modern digital networks in which the trunklines between switching centers carry data between many different nodes in the form of data packets without dedicated circuits. Description The defining example of a circuit-switched network is the early analog telephone network. When a call is made from one telephone to another, swit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
