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Byzantine Generals
A Byzantine fault (also Byzantine generals problem, interactive consistency, source congruency, error avalanche, Byzantine agreement problem, and Byzantine failure) is a condition of a computer system, particularly distributed computing systems, where components may fail and there is imperfect information on whether a component has failed. The term takes its name from an allegory, the "Byzantine generals problem", developed to describe a situation in which, in order to avoid catastrophic failure of the system, the system's actors must agree on a concerted strategy, but some of these actors are unreliable. In a Byzantine fault, a component such as a server can inconsistently appear both failed and functioning to failure-detection systems, presenting different symptoms to different observers. It is difficult for the other components to declare it failed and shut it out of the network, because they need to first reach a consensus regarding which component has failed in the first pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Computing
A distributed system is a system whose components are located on different networked computers, which communicate and coordinate their actions by passing messages to one another from any system. Distributed computing is a field of computer science that studies distributed systems. The components of a distributed system interact with one another in order to achieve a common goal. Three significant challenges of distributed systems are: maintaining concurrency of components, overcoming the lack of a global clock, and managing the independent failure of components. When a component of one system fails, the entire system does not fail. Examples of distributed systems vary from SOA-based systems to massively multiplayer online games to peer-to-peer applications. A computer program that runs within a distributed system is called a distributed program, and ''distributed programming'' is the process of writing such programs. There are many different types of implementations for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SRI International
SRI International (SRI) is an American nonprofit scientific research institute and organization headquartered in Menlo Park, California. The trustees of Stanford University established SRI in 1946 as a center of innovation to support economic development in the region. The organization was founded as the Stanford Research Institute. SRI formally separated from Stanford University in 1970 and became known as SRI International in 1977. SRI performs client-sponsored research and development for government agencies, commercial businesses, and private foundations. It also licenses its technologies, forms strategic partnerships, sells products, and creates spin-off companies. SRI's headquarters are located near the Stanford University campus. SRI's annual revenue in 2014 was approximately $540 million, which tripled from 1998 under the leadership of Curtis Carlson. In 1998, the organization was on the verge of bankruptcy when Carlson took over as CEO. Over the next sixteen years w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARINC
Aeronautical Radio, Incorporated (ARINC), established in 1929, was a major provider of transport communications and systems engineering solutions for eight industries: aviation, airports, defense, government, healthcare, networks, security, and transportation. ARINC had installed computer data networks in police cars and railroad cars and also maintains the standards for line-replaceable units. ARINC was formerly headquartered in Annapolis, Maryland, and had two regional headquarters in London, established in 1999 to serve the Europe, Middle East, and Africa region, and Singapore, established in 2003 for the Asia Pacific region. ARINC had more than 3,200 employees at over 120 locations worldwide. The sale of the company by Carlyle Group to Rockwell Collins was completed on December 23, 2013, and from November 2018 onward operates as part of Collins Aerospace. History ARINC was incorporated in 1929 as Aeronautical Radio, Incorporated. It was chartered by the Federal Ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Information Management System
The Airplane Information Management System (AIMS) is the "brains" of Boeing 777 aircraft. It uses four ARINC 629 buses to transfer information. There are 2 cabinets on each plane (left and right). History The Intel 80x86 processor was the first to be used for the system, in conjunction with a compiler and runtime system for the Ada programming language. Beginning in 1988 and continuing for a number of years, Honeywell Air Transport Systems worked together with consultants from DDC-I in collaboration to retarget and optimize the DDC-I Ada compiler to the AMD 29050 architecture for use in full scale development. The Airplane Information Management System software would become arguably the best-known of any Ada project, civilian or military. Also at http://delivery.acm.org/10.1145/1040000/1035608/p28-wolfe.pdf Some 550 developers at Honeywell worked on the flight system. Functions Primary Functions * Cockpit displays system * Flight management system * Thrust management system ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proof Of Stake
Proof-of-stake (PoS) protocols are a class of consensus mechanisms for blockchains that work by selecting validators in proportion to their quantity of holdings in the associated cryptocurrency. This is done to avoid the computational cost of proof-of-work schemes. The first functioning use of PoS for cryptocurrency was Peercoin in 2012. Description For a blockchain transaction to be recognized, it must be appended to the blockchain. In the proof of stake blockchain the appending entities are named ''minters'' or (in the proof of work blockchains this task is carried out by the miners); in most protocols, the validators receive a reward for doing so. For the blockchain to remain secure, it must have a mechanism to prevent a malicious user or group from taking over a majority of validation. PoS accomplishes this by requiring that validators have some quantity of blockchain tokens, requiring potential attackers to acquire a large fraction of the tokens on the blockchain to m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proof-of-work
Proof of work (PoW) is a form of cryptographic proof in which one party (the ''prover'') proves to others (the ''verifiers'') that a certain amount of a specific computational effort has been expended. Verifiers can subsequently confirm this expenditure with minimal effort on their part. The concept was invented by Moni Naor and Cynthia Dwork in 1993 as a way to deter denial-of-service attacks and other service abuses such as spam on a network by requiring some work from a service requester, usually meaning processing time by a computer. The term "proof of work" was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels. Proof of work was later popularized by Bitcoin as a foundation for consensus in a permissionless decentralized network, in which miners compete to append blocks and mint new currency, each miner experiencing a success probability proportional to the computational effort expended. PoW and PoS (proof of stake) remain the two best known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blockchain
A blockchain is a type of distributed ledger technology (DLT) that consists of growing lists of records, called ''blocks'', that are securely linked together using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (generally represented as a Merkle tree, where data nodes are represented by leaves). The timestamp proves that the transaction data existed when the block was created. Since each block contains information about the previous block, they effectively form a ''chain'' (compare linked list data structure), with each additional block linking to the ones before it. Consequently, blockchain transactions are irreversible in that, once they are recorded, the data in any given block cannot be altered retroactively without altering all subsequent blocks. Blockchains are typically managed by a peer-to-peer (P2P) computer network for use as a public distributed ledger, where nodes collectively adhere to a conse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bitcoin Network
The bitcoin network is a peer-to-peer payment network that operates on a cryptographic protocol. Users send and receive bitcoins, the units of currency, by broadcasting digitally-signed messages to the network using bitcoin cryptocurrency wallet software. Transactions are recorded into a distributed, replicated, public database known as the blockchain, with consensus achieved by a proof-of-work system called ''mining''. Satoshi Nakamoto, the anonymous designer of the protocol, stated that design and coding of bitcoin began in 2007. The project was released in 2009 as open source software. The network requires minimal structure to share transactions. An ad hoc decentralized network of volunteers is sufficient. Messages are broadcast on a best-effort basis, and nodes can leave and rejoin the network at will. Upon reconnection, a node downloads and verifies new blocks from other nodes to complete its local copy of the blockchain. Transactions A bitcoin is defined by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bitcoin
Bitcoin (abbreviation: BTC; sign: ₿) is a decentralized digital currency that can be transferred on the peer-to-peer bitcoin network. Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. The cryptocurrency was invented in 2008 by an unknown person or group of people using the name Satoshi Nakamoto. The currency began use in 2009, when its implementation was released as open-source software. The word "''bitcoin''" was defined in a white paper published on October 31, 2008. It is a compound of the words ''bit'' and ''coin''. The legality of bitcoin varies by region. Nine countries have fully banned bitcoin use, while a further fifteen have implicitly banned it. A few governments have used bitcoin in some capacity. El Salvador has adopted Bitcoin as legal tender, although use by merchants remains low. Ukraine has accepted cryptocurrency donations to fund the resistance to the 2022 Rus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virginia-class Submarine
The ''Virginia'' class, also known as the SSN-774 class, is a class of nuclear-powered cruise missile fast-attack submarines, in service in the United States Navy. Designed by General Dynamics Electric Boat (EB) and Huntington Ingalls Industries, the ''Virginia'' class is the United States Navy's latest submarine model, which incorporates the latest in stealth, intelligence gathering, and weapons systems technology. ''Virginia''-class submarines are designed for a broad spectrum of open-ocean and littoral missions, including anti-submarine warfare and intelligence gathering operations. They are scheduled to replace older s, many of which have already been decommissioned. ''Virginia''-class submarines will be acquired through 2043, and are expected to remain in service until at least 2060, with later submarines expected to remain into the 2070s. History The class was developed under the codename Centurion, later renamed New SSN (NSSN). The "Centurion Study" was initiated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program, aeronautics research, and outer space, space research. NASA was National Aeronautics and Space Act, established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo program, Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion (spacecraft), Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew Program, Commercial Crew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byzantine Empire
The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinople. It survived the fragmentation and fall of the Western Roman Empire in the 5th century AD and continued to exist for an additional thousand years until the fall of Constantinople to the Ottoman Empire in 1453. During most of its existence, the empire remained the most powerful economic, cultural, and military force in Europe. The terms "Byzantine Empire" and "Eastern Roman Empire" were coined after the end of the realm; its citizens continued to refer to their empire as the Roman Empire, and to themselves as Romans—a term which Greeks continued to use for themselves into Ottoman times. Although the Roman state continued and its traditions were maintained, modern historians prefer to differentiate the Byzantine Empire from Ancient Rome a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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