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Fault-tolerant
Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the severity of the failure, as compared to a naively designed system, in which even a small failure can cause total breakdown. Fault tolerance is particularly sought after in high-availability, mission-critical, or even life-critical systems. The ability of maintaining functionality when portions of a system break down is referred to as graceful degradation. A fault-tolerant design enables a system to continue its intended operation, possibly at a reduced level, rather than failing completely, when some part of the system fails. The term is most commonly used to describe computer systems designed to continue more or less fully operational with, perhaps, a reduction in throughput or an increase in response time in the event of some partia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antonín Svoboda (computer Scientist)
Antonín Svoboda (14 October 1907 – 18 May 1980) was a Czech computer scientist, mathematician, electrical engineer, and researcher. He is credited with originating the design of fault-tolerant computer systems, and with the creation of SAPO, the first Czech computer design. Early life Svoboda was born in Prague in 1907. Attending a series of schools, he studied at the College of Mechanical and Electrical Engineering of Czech Technical University in Prague (CTU), from where he graduated in 1931. In that same year, he traveled to England briefly to study physics, but returned to Czechoslovakia to conduct research and study under Václav Dolejšek, who made very significant discoveries in X-ray spectrography. Professional career Svoboda and Dolejšek worked together on several projects, including X-rays and other astronomy-related aspects, but the rapidly rising specter of what was occurring in Germany, set against the backdrop of the economic collapse during his time, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SAPO (computer)
The SAPO (short for ''Samočinný počítač'', “automatic computer”) was the first Czechoslovak computer. It operated in the years 1957–1960 in '' Výzkumný ústav matematických strojů'', part of the Czechoslovak Academy of Sciences. The computer was the first fault-tolerant computer – it had three parallel arithmetic logic units, which decided on the correct result by voting, an example of triple modular redundancy (if all three results were different, the operation was repeated). SAPO was designed between 1950 and 1956 by a team led by Czechoslovak cybernetics pioneer Antonín Svoboda. Svoboda had experience from building in the United States, where he worked at MIT until 1946. It was an electromechanical design with 7,000 relays and 400 vacuum tubes, and a magnetic drum memory with capacity of 1024 32-bit words A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-stabilization
Self-stabilization is a concept of fault-tolerance in distributed systems. Given any initial state, a self-stabilizing distributed system will end up in a correct state in a finite number of execution steps. At first glance, the guarantee of self stabilization may seem less promising than that of the more traditional fault-tolerance of algorithms, that aim to guarantee that the system always remains in a correct state under certain kinds of state transitions. However, that traditional fault tolerance cannot always be achieved. For example, it cannot be achieved when the system is started in an incorrect state or is corrupted by an intruder. Moreover, because of their complexity, it is very hard to debug and to analyze distributed systems. Hence, it is very hard to prevent a distributed system from reaching an incorrect state. Indeed, some forms of self-stabilization are incorporated into many modern computer and telecommunications networks, since it gives them the ability to cope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatigue (material)
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure. Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal ''crystallising'' because of the brittle appearance of the fracture surface, but this has since been disproved. Most materials, such as composites, plastics and ceramics, seem to experience some sort of fatigue-related failure. To aid in predicting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System
A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed in its functioning. Systems are the subjects of study of systems theory and other systems sciences. Systems have several common properties and characteristics, including structure, function(s), behavior and interconnectivity. Etymology The term ''system'' comes from the Latin word ''systēma'', in turn from Greek ''systēma'': "whole concept made of several parts or members, system", literary "composition"."σύστημα" Henry George Liddell, Robert Scott, '' [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Power Plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. , the International Atomic Energy Agency reported there were 422 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction. Nuclear plants are very often used for base load since their operations, maintenance, and fuel costs are at the lower end of the spectrum of costs. However, building a nuclear power plant often spans five to ten years, which can accrue to significant financial costs, depending on how the initial investments are financed. Nuclear power plants have a carbon footprint comparable to that of renewable energy such as solar farms and wind farms, and much lower than fossil fuels such as natural gas and brown coal. Despite some spectacula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Probe
A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or enter interstellar space. Many countries and private companies have launched probes to planets, asteroids, moons around the Solar System, including the Soviet Union, the United States, India, and many more. History On 4 October 1957, the first artificial satellite to orbit Earth was Sputnik 1, launched by the USSR. Four months later, on 1 February 1958, Explorer 1 was launched by the United States, being the first space probe. Explorer 1, collecting data on temperature, cosmic rays, and micrometeorite impacts. The first attempted lunar probe was the Luna E-1 No.1, launched on 23 September 1958. The goal of a lunar probe repeatedly failed until 4 January 1959 when Luna 1 orbited around the moon and then the sun. The success of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope thermoelectric generators (RTGs). Most satellites also have a method of communication to ground stations, called transponders. Many satellites use a standardized bus to save cost and work, the most popular of which is small CubeSats. Similar satellites can work together as a group, forming constellations. Because of the high launch cost to space, satellites are designed to be as lightweight and robust as possible. Most communication satellites are radio relay stations in orbit and carry dozens of transponders, each with a bandwidth of tens of megahertz. Satellites are placed from the surface to orbit by launch vehicles, high enough to avoid orbital decay by the atmosphere. Satellites can then change or maintain the orbit by pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collider
A collider is a type of particle accelerator which brings two opposing particle beams together such that the particles collide. Colliders may either be ring accelerators or linear accelerators. Colliders are used as a research tool in particle physics by accelerating particles to very high kinetic energy and letting them impact other particles. Analysis of the byproducts of these collisions gives scientists good evidence of the structure of the subatomic world and the laws of nature governing it. These may become apparent only at high energies and for tiny periods of time, and therefore may be hard or impossible to study in other ways. Explanation In particle physics one gains knowledge about elementary particles by accelerating particles to very high kinetic energy and letting them impact on other particles. For sufficiently high energy, a reaction occurs that transforms the particles into other particles. Detecting these products gives insight into the physics involved. To d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triple Modular Redundancy
Triple is used in several contexts to mean "threefold" or a "treble": Sports * Triple (baseball), a three-base hit * A basketball three-point field goal * A figure skating jump with three rotations * In bowling terms, three strikes in a row * In cycling, a crankset with three chainrings Places * Triple Islands, an uninhabited island group in Nunavut, Canada * Triple Island, British Columbia, Canada * Triple Falls (other), four waterfalls in the United States & Canada * Triple Glaciers, in Grand Teton National Park, Wyoming * Triple Crossing, Richmond, Virginia, believed to be the only place in North America where three Class I railroads cross * Triple Bridge, a stone arch bridge in Ljubljana, Slovenia Transportation * Kawasaki triple, a Japanese motorcycle produced between 1969 and 1980 * Triumph Triple, a motorcycle engine from Triumph Motorcycles Ltd * A straight-three engine * A semi-truck with three trailers Science and technology * Triple (mathematics) ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insurance Companies
Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to hedge against the risk of a contingent or uncertain loss. An entity which provides insurance is known as an insurer, insurance company, insurance carrier, or underwriter. A person or entity who buys insurance is known as a policyholder, while a person or entity covered under the policy is called an insured. The insurance transaction involves the policyholder assuming a guaranteed, known, and relatively small loss in the form of a payment to the insurer (a premium) in exchange for the insurer's promise to compensate the insured in the event of a covered loss. The loss may or may not be financial, but it must be reducible to financial terms. Furthermore, it usually involves something in which the insured has an insurable interest established by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Probability
Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, 0 indicates impossibility of the event and 1 indicates certainty."Kendall's Advanced Theory of Statistics, Volume 1: Distribution Theory", Alan Stuart and Keith Ord, 6th Ed, (2009), .William Feller, ''An Introduction to Probability Theory and Its Applications'', (Vol 1), 3rd Ed, (1968), Wiley, . The higher the probability of an event, the more likely it is that the event will occur. A simple example is the tossing of a fair (unbiased) coin. Since the coin is fair, the two outcomes ("heads" and "tails") are both equally probable; the probability of "heads" equals the probability of "tails"; and since no other outcomes are possible, the probability of either "heads" or "tails" is 1/2 (which could also be written ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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