System details.

The first generation peer-to-peer file sharing networks, such as Napster, relied on a central database to co-ordinate look ups on the network. Second generation peer-to-peer networks, such as Gnutella, used flooding to locate files, searching every node on the network. Third generation peer-to-peer networks use Distributed hash tables to look up files in the network. "Distributed hash tables" store resource locations throughout the network. A major criterion for these protocols is locating the desired nodes quickly.  Kademlia uses a "distance" calculation between two nodes. This distance is computed as the "exclusive or (XOR)" of the two node IDs, taking the result as an unsigned integer number. Keys and Node IDs have the same format and length, so distance can be calculated among them in exactly the same way. The node ID is typically a large random number that is chosen with the goal of being unique for a particular node (see UUID). It can and does happen that geographically widely separated nodes—from Germany and Australia, for instance—can be "neighbors" if they have chosen similar random node IDs.  "Exclusive or" was chosen because it acts as a distance function between all the node IDs. Specifically:  These three conditions are enough to ensure that "exclusive or" captures all of the essential, important features of a "real" distance function, while being cheap and simple to calculate.  Each Kademlia search iteration comes one bit closer to the target. A basic Kademlia network with 2 nodes will only take "n" steps (in the worst case) to find that node.

Fixed Size Routing tables.

"This section is simplified to use a single bit; see the section accelerated lookups for more information on real routing tables."  Fixed size routing tables were presented in the pre-proceedings version of the original paper and are used in the later version only for some mathematical proofs. An actual Kademlia implementation does not have a fixed size routing table, but a dynamic sized one.  Kademlia routing tables consist of a "list" for each bit of the node ID. (e.g. if a node ID consists of 128 bits, a node will keep 128 such "lists".) A list has many entries. Every entry in a "list" holds the necessary data to locate another node. The data in each "list" entry is typically the "IP address", "port", and "node ID" of another node. Every "list" corresponds to a specific distance from the node. Nodes that can go in the n "list" must have a differing n bit from the node's ID; the first n-1 bits of the candidate ID must match those of the node's ID. This means that it is very easy to populate the first "list" as 1/2 of the nodes in the network are far away candidates. The next "list" can use only 1/4 of the nodes in the network (one bit closer than the first), etc.  With an ID of 128 bits, every node in the network will classify other nodes in one of 128 different distances, one specific distance per bit.  As nodes are encountered on the network, they are added to the "lists". This includes store and retrieval operations and even helping other nodes to find a key. Every node encountered will be considered for inclusion in the "lists". Therefore, the knowledge that a node has of the network is very dynamic. This keeps the network constantly updated and adds resilience to failures or attacks.  In the Kademlia literature, the "lists" are referred to as "k-buckets". "k" is a system wide number, like 20. Every k-bucket is a "list" having up to "k" entries inside; i.e. for a network with k=20, each node will have "lists" containing up to 20 nodes for a particular bit (a particular distance from itself).  Since the possible nodes for each "k-bucket" decreases quickly (because there will be very few nodes that are that close), the lower bit "k-buckets" will fully map all nodes in that section of the network. Since the quantity of possible IDs is much larger than any node population can ever be, some of the k-buckets corresponding to very short distances will remain empty.  Consider the simple network to the right. The network size is 2^3 or eight maximum keys and nodes. There are seven nodes participating; the small circles at the bottom. The node under consideration is node six (binary 110) in black. There are three "k-buckets" for each node in this network. Nodes zero, one and two (binary 000, 001, and 010) are candidates for the farthest "k-bucket". Node three (binary 011, not shown) is not participating in the network. In the middle "k-bucket", nodes four and five (binary 100 and 101) are placed. Finally, the third "k-bucket" can only contain node seven (binary 111). Each of the three "k-buckets" are enclosed in a gray circle. If the size of the "k-bucket" was two, then the farthest "2-bucket" can only contain two of the three nodes. For example, if node six has node one and two in the farthest 2-bucket, it would have to request a node ID lookup to these nodes to find the location (ip address) of node zero. Each node "knows" its neighbourhood well and has contact with a few nodes far away which can help locate other nodes far away.  It is known that nodes that have been connected for a long time in a network will probably remain connected for a long time in the future. Because of this statistical distribution, Kademlia selects long connected nodes to remain stored in the k-buckets. This increases the number of known valid nodes at some time in the future and provides for a more stable network.  When a "k-bucket" is full and a new node is discovered for that "k-bucket", the least recently seen node in the "k-bucket" is PINGed. If the node is found to be still alive, the new node is placed in a secondary list, a replacement cache. The replacement cache is used only if a node in the "k-bucket" stops responding. In other words: new nodes are used only when older nodes disappear.

Protocol messages.

Kademlia has four messages.  Each RPC message includes a random value from the initiator. This ensures that when the response is received it corresponds to the request previously sent. (see Magic cookie)

Locating nodes.

Node lookups can proceed asynchronously. The quantity of simultaneous lookups is denoted by α and is typically three. A node initiates a FIND_NODE request by querying to the α nodes in its own "k-buckets" that are the closest ones to the desired key. When these recipient nodes receive the request, they will look in their "k-buckets" and return the "k" closest nodes to the desired key that they know. The requester will update a results list with the results (node ID's) he receives, keeping the "k" best ones (the k nodes that are closer to the searched key) that respond to queries. Then the requester will select these "k" best results and issue the request to them, and iterate this process again and again. Because every node has a better knowledge of his own surroundings than any other node has, the received results will be other nodes that are every time closer and closer to the searched key. The iterations continue until no nodes are returned that are closer than the best previous results. When the iterations stop, the best k nodes in the results list are the ones in the whole network that are the closest to the desired key.  The node information can be augmented with round trip times, or RTT. This information will be used to choose a time-out specific for every consulted node. When a query times out, another query can be initiated, never surpassing α queries at the same time.

Locating resources.

Information is located by mapping it to a key. A hash is typically used for the map. The storer nodes will have information due to a previous STORE message. Locating a value follows the same procedure as locating the closest nodes to a key, except the search terminates when a node has the requested value in his store and returns this value.  The values are stored at several nodes (k of them) to allow for nodes to come and go and still have the value available in some node. Periodically, a node that stores a value will explore the network to find the k nodes that are close to the key value and replicate the value onto them. This compensates for disappeared nodes.  Also, for popular values that might have many requests, the load in the storer nodes is diminished by having a retriever store this value in some node near, but outside of, the k closest ones. This new storing is called a cache. In this way the value is stored farther and farther away from the key, depending on the quantity of requests. This allows popular searches to find a storer more quickly. Because the value is returned from nodes farther away from the key, this alleviates possible "hot spots". Caching nodes will drop the value after a certain time depending on their distance from the key.  Some implementations (e.g. Kad) do not have replication nor caching. The purpose of this is to remove old information quickly from the system. The node that is providing the file will periodically refresh the information onto the network (perform FIND_NODE and STORE messages). When all of the nodes having the file go offline, nobody will be refreshing its values (sources and keywords) and the information will eventually disappear from the network.

Joining the network.

A node that would like to join the net must first go through a bootstrap process. In this phase, the joining node needs to know the IP address and port of another node—a bootstrap node (obtained from the user, or from a stored list)—that is already participating in the Kademlia network. If the joining node has not yet participated in the network, it computes a random ID number that is supposed not to be already assigned to any other node. It uses this ID until leaving the network.  The joining node inserts the bootstrap node into one of its "k-buckets". The joining node then performs a node lookup of its own ID against the bootstrap node (the only other node it knows). The "self-lookup" will populate other nodes' "k-buckets" with the new node ID, and will populate the joining node's k-buckets with the nodes in the path between it and the bootstrap node. After this, the joining node refreshes all "k-buckets" further away than the k-bucket the bootstrap node falls in. This refresh is just a lookup of a random key that is within that "k-bucket" range.  Initially, nodes have one "k-bucket". When the "k-bucket" becomes full, it can be split. The split occurs if the range of nodes in the "k-bucket" spans the node's own id (values to the left and right in a binary tree). Kademlia relaxes even this rule for the one "closest nodes" "k-bucket", because typically one single bucket will correspond to the distance where all the nodes that are the closest to this node are, they may be more than k, and we want it to know them all. It may turn out that a highly unbalanced binary sub-tree exists near the node. If "k" is 20, and there are 21+ nodes with a prefix "xxx0011..." and the new node is "xxx0000"11001"", the new node can contain multiple "k-buckets" for the other 21+ nodes. This is to guarantee that the network knows about all nodes in the closest region.

Accelerated lookups.

Kademlia uses an "XOR metric" to define distance. Two node ID's or a node ID and a key are XORed and the result is the distance between them. For each bit, the XOR function returns zero if the two bits are equal and one if the two bits are different. XOR metric distances hold the triangle inequality: given A, B and C are vertices (points) of a triangle, then the distance from A to B is shorter than (or equal to) the sum of the distance from A to C to B.  The "XOR metric" allows Kademlia to extend routing tables beyond single bits. Groups of bits can be placed in "k-buckets". The group of bits are termed a prefix. For an "m-bit" prefix, there will be 2-1 "k-buckets". The missing "k-bucket" is a further extension of the routing tree that contains the node ID. An "m-bit" prefix reduces the maximum number of lookups from "log n" to "log n". These are maximum values and the average value will be far less, increasing the chance of finding a node in a "k-bucket" that shares more bits than just the prefix with the target key.  Nodes can use mixtures of prefixes in their routing table, such as the Kad Network used by eMule. The Kademlia network could even be heterogeneous in routing table implementations, at the expense of complicating the analysis of lookups.

Academic significance.

While the XOR metric is not needed to understand Kademlia, it is critical in the analysis of the protocol. The XOR arithmetic forms an abelian group allowing closed analysis. Other DHT protocols and algorithms require simulation or complicated formal analysis in order to predict network behavior and correctness. Using groups of bits as routing information also simplifies the algorithms.

Mathematical analysis of the algorithm.

To analyze the algorithm, consider a Kademlia network of formula_2 nodes with IDs formula_4, each of which is a string of length formula_5 that consists of only ones and zeros. It can be modeled as a trie, in which each leaf represents a node, and the labeled path from the root to a leaf represents its ID. For a node formula_6, let formula_7 be the set of nodes (IDs) that share a prefix with formula_8 of length formula_9. Then filling the formula_10-th bucket of formula_8 can be modeled as adding pointers from the leaf formula_8 to formula_13 leaves (IDs) chosen uniformly at random from formula_7. Thus routing can be seen as jumping among the leaves along these pointers such that each step goes towards the target ID as much as possible, i.e., in a greedy way.  Let formula_15 be number of jumps needed to go from the leaf formula_8 to a target ID formula_17. Assuming that formula_4 are chosen deterministically from formula_19, it has been proved that where formula_21 is the formula_13-th Harmonic Number. Since formula_23 as formula_24, when formula_13 is large formula_26 is bounded from above by about formula_27, however the IDs and the target are chosen. This justifies the intuition that in Kademlia only formula_28 nodes are contacted in searching for a target node.  To make the model closer to real Kademlia networks, formula_4 can also be assumed to be chosen uniformly at random without replacement from formula_19. Then it can be proved that for all formula_6 and formula_32, where formula_34 is a constant depending only on formula_13 with formula_36 as formula_24. Thus for formula_13 large, formula_39 converges to a constant close formula_40. This implies that the number of nodes need to be contact in searching for a target node is actually formula_41 on average.

Use in file sharing networks.

Kademlia is used in file sharing networks. By making Kademlia keyword searches, one can find information in the file-sharing network so it can be downloaded. Since there is no central instance to store an index of existing files, this task is divided evenly among all clients: If a node wants to share a file, it processes the contents of the file, calculating from it a number (hash) that will identify this file within the file-sharing network. The hashes and the node IDs must be of the same length. It then searches for several nodes whose ID is close to the hash, and has its own IP address stored at those nodes. i.e. it publishes itself as a source for this file. A searching client will use Kademlia to search the network for the node whose ID has the smallest distance to the file hash, then will retrieve the sources list that is stored in that node.  Since a key can correspond to many values, e.g. many sources of the same file, every storing node may have different information. Then, the sources are requested from all k nodes close to the key.  The file hash is usually obtained from a specially formed Internet magnet link found elsewhere, or included within an indexing file obtained from other sources.  Filename searches are implemented using keywords. The filename is divided into its constituent words. Each of these keywords is hashed and stored in the network, together with the corresponding filename and file hash. A search involves choosing one of the keywords, contacting the node with an ID closest to that keyword hash, and retrieving the list of filenames that contain the keyword. Since every filename in the list has its hash attached, the chosen file can then be obtained in the normal way.

Implementations.

Networks.

Public networks using the Kademlia algorithm (these networks are incompatible with one another):

Kademlia is a distributed hash table for decentralized peer-to-peer computer networks designed by Petar Maymounkov and David Mazières in 2002. It specifies the structure of the network and the exchange of information through node lookups. Kademlia nodes communicate among themselves using UDP. A virtual or overlay network is formed by the participant nodes. Each node is identified by a number or "node ID". The "node ID" serves not only as identification, but the Kademlia algorithm uses the "node ID" to locate values (usually file hashes or keywords). In fact, the "node ID" provides a direct map to file hashes and that node stores information on where to obtain the file or resource.

Kademlia是一种通过分布式杂凑表实现的协议算法,它是由Petar和David为非集中式P2P计算机网络而设计的。Kademlia规定了网络的结构,也规定了通过节点查询进行信息交换的方式。Kademlia网络节点之间使用UDP进行通讯。参与通讯的所有节点形成一张虚拟网(或者叫做覆盖网)。这些节点通过一组数字(或称为节点ID)来进行身份标识。节点ID不仅可以用来做身份标识,还可以用来进行值定位(值通常是文件的散列或者关键词)。其实,节点ID与文件散列直接对应,它所表示的那个节点存储着哪儿能够获取文件和资源的相关信息。当我们在网络中搜索某些值(即通常搜索存储文件散列或关键词的节点)的时候,Kademlia算法需要知道与这些值相关的键,然后分步在网络中开始搜索。每一步都会找到一些节点,这些节点的ID与键更为接近,如果有节点直接返回搜索的值或者再也无法找到与键更为接近的节点ID的时候搜索便会停止。这种搜索值的方法是非常高效的:与其他的分布式杂凑表的实现类似,在一个包含n个节点的系统的值的搜索中,Kademlia仅访问O(log(n))个节点。非集中式网络结构还有更大的优势,那就是它能够显著增强抵御拒绝服务攻击的能力。即使网络中的一整批节点遭受泛洪攻击,也不会对网络的可用性造成很大的影响,通过绕过这些漏洞(被攻击的节点)来重新编织一张网络,网络的可用性就可以得到恢复。


Biography.

Geoffrey was born between about 1090 and 1100, in Wales or the Welsh Marches. He had reached the age of majority by 1129 when he is recorded as witnessing a charter.  Geoffrey refers to himself in his "Historia" as "Galfridus Monemutensis" (Geoffrey of Monmouth), which indicates a significant connection to Monmouth, Wales, and may refer to his birthplace. His works attest to some acquaintance with the place-names of the region. Geoffrey was known to his contemporaries as "Galfridus Arturus" or variants thereof. The "Arthur" in these versions of his name may indicate the name of his father or a nickname based on his scholarly interests.  Earlier scholars assumed that Geoffrey was Welsh or at least spoke Welsh. His knowledge of this language appears to have been slight, however, and there is no evidence that he was of either Welsh or Cambro-Norman descent. He may have come from the same French-speaking elite of the Welsh border country as Gerald of Wales, Walter Map, and Robert, Earl of Gloucester, to whom Geoffrey dedicated versions of his "History". Frank Merry Stenton and others have suggested that Geoffrey's parents may have been among the many Bretons who took part in William I's conquest and settled in the southeast of Wales. Monmouth had been in the hands of Breton lords since 1075 or 1086, and the names Galfridus and Arthur were more common among the Bretons than the Welsh.  He may have served for a while in the Benedictine Monmouth Priory, but most of his adult life appears to have been spent outside Wales. Between 1129 and 1151, his name appears on six charters in the Oxford area, sometimes styled "magister" (teacher). He was probably a secular canon of St. George's college. All the charters signed by Geoffrey are also signed by Walter, Archdeacon of Oxford, a canon at that church. Another frequent co-signatory is Ralph of Monmouth, a canon of Lincoln.  Archbishop Theobald of Bec consecrated Geoffrey as Bishop of St Asaph at Lambeth on 24 February 1152, having ordained him a priest at Westminster 10 days before. According to Lewis Thorpe, "There is no evidence that he ever visited his see, and indeed the wars of Owain Gwynedd make this most unlikely." He appears to have died between 25 December 1154 and 24 December 1155 according to Welsh chronicles, when his successor took office.

Works.

Geoffrey's structuring and shaping of the Merlin and Arthur myths engendered their vast popularity which continues today, and he is generally viewed by scholars as the major establisher of the Arthurian canon. The "History"'s effect on the legend of King Arthur was so vast that Arthurian works have been categorised as "pre-Galfridian" and "post-Galfridian", depending on whether or not they were influenced by him.

"Historia Regum Britanniae".

Geoffrey wrote several works in Latin, the language of learning and literature in Europe during the medieval period. His major work was the "Historia Regum Britanniae" ("The History of the Kings of Britain"), the work best known to modern readers. It relates the purported history of Britain, from its first settlement by Brutus of Troy, a descendant of Trojan hero Aeneas, to the death of Cadwaladr in the 7th century, covering Julius Caesar's invasions of Britain, Kings Leir and Cymbeline, and one of the earliest developed narratives of King Arthur.  Geoffrey claims in his dedication that the book is a translation of an "ancient book in the British language that told in orderly fashion the deeds of all the kings of Britain", given to him by Walter, Archdeacon of Oxford, but modern historians have dismissed this claim. It is likely, however, that the Archdeacon did furnish Geoffrey with some materials in the Welsh language which helped inspire his work, as Geoffrey's position and acquaintance with him would not have permitted him to fabricate such a claim outright. Much of it is based on the "Historia Britonum", a 9th-century Welsh-Latin historical compilation, Bede's "Ecclesiastical History of the English People", and Gildas's 6th-century polemic "De Excidio et Conquestu Britanniae", expanded with material from bardic oral tradition and genealogical tracts, and embellished by Geoffrey's own imagination. In an exchange of manuscript material for their own histories, Robert of Torigny gave Henry of Huntingdon a copy of "History", which both Robert and Henry used uncritically as authentic history and subsequently used in their own works, by which means some of Geoffrey's fictions became embedded in popular history.  "The History of the Kings of Britain" is now usually considered a literary work of national myth containing little reliable history. This has since led many modern scholars to agree with William of Newburgh, who wrote around 1190 that "it is quite clear that everything this man wrote about Arthur and his successors, or indeed about his predecessors from Vortigern onwards, was made up, partly by himself and partly by others."  Other contemporaries were similarly unconvinced by Geoffrey's "History". For example, Giraldus Cambrensis recounts the experience of a man possessed by demons: "If the evil spirits oppressed him too much, the Gospel of St John was placed on his bosom, when, like birds, they immediately vanished; but when the book was removed, and the "History of the Britons" by 'Geoffrey Arthur' [as Geoffrey named himself] was substituted in its place, they instantly reappeared in greater numbers, and remained a longer time than usual on his body and on the book."  Geoffrey's major work was nevertheless widely disseminated throughout medieval Western Europe; Acton Griscom listed 186 extant manuscripts in 1929, and others have been identified since. It enjoyed a significant afterlife in a variety of forms, including translations and adaptations such as Wace's Anglo-Norman "Roman de Brut", Layamon's Middle English "Brut", and several anonymous Middle Welsh versions known as "" (""Brut of the Kings""). where it was generally accepted as a true account.  In 2017, Miles Russell published the initial results of the Lost Voices of Celtic Britain Project established at Bournemouth University. The main conclusion of the study was that the "Historia Regum Britanniae" appears to contain significant demonstrable archaeological fact, despite being compiled many centuries after the period that it describes. Geoffrey seems to have brought together a disparate mass of source material, including folklore, chronicles, king-lists, dynastic tables, oral tales, and bardic praise poems, some of which was irrevocably garbled or corrupted. In doing so, Geoffrey exercised considerable editorial control, massaging the information and smoothing out apparent inconsistencies in order to create a single grand narrative. Much of the information that he used can be shown to be derived from two discrete sources:  Stretching this source material out, chopping, changing and re-editing it in the process, Geoffrey added additional information culled from later Roman histories and also those of Dark Ages and early medieval writers such as Gildas and Bede.

Other writings.

Geoffrey's earliest writing was probably the "" ("Prophecies of Merlin") which he wrote before 1135, and which appears both independently and incorporated into "The History of the Kings of Britain". It consists of a series of obscure prophetic utterances attributed to Merlin which he claimed to have translated from an unspecified language.  The third work attributed to Geoffrey is the hexameter poem "Vita Merlini" ("Life of Merlin"), based more closely on traditional material about Merlin than the other works. Here he is known as Merlin of the Woods ("Merlinus Sylvestris") or Scottish Merlin ("Merlinus Caledonius") and is portrayed as an old man living as a crazed and grief-stricken outcast in the forest. The story is set long after the timeframe of the "History"'s Merlin, but the author tries to synchronise the works with references to the mad prophet's previous dealings with Vortigern and Arthur. The "Vita" did not circulate widely, and the attribution to Geoffrey appears in only one late 13th-century manuscript, but it contains recognisably Galfridian elements in its construction and content, and most critics recognise it as his.

Geoffrey of Monmouth (, ; c. 1095 – c. 1155) was a British cleric and one of the major figures in the development of British historiography and the popularity of tales of King Arthur. He is best known for his chronicle "The History of the Kings of Britain" ( or "") which was widely popular in its day, being translated into other languages from its original Latin. It was given historical credence well into the 16th century, but is now considered historically unreliable.

蒙茅斯的杰弗里(Galfridus Monemutensis, Galfridus Arturus, :Gruffudd ap Arthur, Sieffre o Fynwy ; 1095/1100年 - 1155年)是一名英国牧师,也是英国史学发展的主要人物之一,著名的亚瑟王故事的编撰者。他最为出名的作品是他的编年史《不列颠诸王史》(或"")。《不列颠诸王史》作为他广受欢迎的著作,已经从拉丁文被翻译成多个语言版本。它在16世纪被认为是可信的。但现代研究认为其记述的历史是不可靠的。


Treaty structure.

The NPT consists of a preamble and eleven articles. Although the concept of "pillars" is not expressed anywhere in the NPT, the treaty is nevertheless sometimes interpreted as a "three-pillar" system, with an implicit balance among them: These pillars are interrelated and mutually reinforcing. An effective nonproliferation regime whose members comply with their obligations provides an essential foundation for progress on disarmament and makes possible greater cooperation on the peaceful use of nuclear energy. With the right to access the benefits of peaceful nuclear technology comes the responsibility of nonproliferation. Progress on disarmament reinforces efforts to strengthen the nonproliferation regime and to enforce compliance with obligations, thereby also facilitating peaceful nuclear cooperation. The "pillars" concept has been questioned by some who believe that the NPT is, as its name suggests, principally about nonproliferation, and who worry that "three pillars" language misleadingly implies that the three elements have equivalent importance.

First pillar: Non-proliferation.

Under Article I of the NPT, nuclear-weapon states pledge not to transfer nuclear weapons or other nuclear explosive devices to any recipient or in any way assist, encourage or induce any non-nuclear-weapon state in the manufacture or acquisition of a nuclear weapon.  Under Article II of the NPT, non-nuclear-weapon states pledge not to acquire or exercise control over nuclear weapons or other nuclear explosive devices and not to seek or receive assistance in the manufacture of such devices.  Under Article III of the Treaty, non-nuclear-weapon states pledge to accept IAEA safeguards to verify that their nuclear activities serve only peaceful purposes.  Five states are recognized by NPT as nuclear weapon states (NWS): China (signed 1992), France (1992), the Soviet Union (1968; obligations and rights now assumed by the Russian Federation), the United Kingdom (1968), and the United States (1968), which also happen to be the five permanent members of the United Nations Security Council.

Second pillar: Disarmament.

Under Article VI of the NPT, all Parties undertake to pursue good-faith negotiations on effective measures relating to cessation of the nuclear arms race, to nuclear disarmament, and to general and complete disarmament.  Article VI of the NPT represents the only binding commitment in a multilateral treaty to the goal of disarmament by the nuclear-weapon states. The NPT's preamble contains language affirming the desire of treaty signatories to ease international tension and strengthen international trust so as to create someday the conditions for a halt to the production of nuclear weapons, and treaty on general

Third pillar: Peaceful use of nuclear energy.

NPT Article IV acknowledges the right of all Parties to develop nuclear energy for peaceful purposes and to benefit from international cooperation in this area, in conformity with their nonproliferation obligations. Article IV also encourages such cooperation. This so-called third pillar provides for the transfer of nuclear technology and materials to NPT Parties for peaceful purposes in the development of civilian nuclear energy programs in those countries, subject to IAEA safeguards to demonstrate that their nuclear programs are not being used for the development of nuclear weapons.  As the commercially popular light water reactor nuclear power station uses enriched uranium fuel,

Key articles.

"Article I": Each nuclear-weapons state (NWS) undertakes not to transfer, to any recipient, nuclear weapons, or other nuclear explosive devices, and not to assist any non-nuclear weapon state to manufacture or acquire such weapons or devices.  "Article II": Each non-NWS party undertakes not to receive, from any source, nuclear weapons, or other nuclear explosive devices; not to manufacture or acquire such weapons or devices; and not to receive any assistance in their manufacture.  "Article III": Each non-NWS party undertakes to conclude an agreement with the IAEA for the application of its safeguards to all nuclear material in all of the state's peaceful nuclear activities and to prevent diversion of such material to nuclear weapons or other nuclear explosive devices.  "Article IV": 1. Nothing in this Treaty shall be interpreted as affecting the inalienable right of all the Parties to the Treaty to develop research, production and use

History.

The impetus behind the NPT was concern for the safety of a world with many nuclear weapon states. It was recognized that the Cold War deterrent relationship between just the United States and the Soviet Union was fragile. Having more nuclear-weapon states would reduce security for all, multiplying the risks of miscalculation, accidents, unauthorized use of weapons, escalation in tensions, and nuclear conflict. Moreover, since the use of nuclear weapons in Hiroshima and Nagasaki in 1945, it has been apparent that the development of nuclear capabilities by States could enable them to divert technology and materials for weapons purposes. Thus, the problem of preventing such diversions became a central issue in discussions on peaceful uses of nuclear energy.  Initial efforts, which began in 1946, to create an international system enabling all States to have access to nuclear technology under appropriate safeguards, were terminated in 1949 without the achievement of this objective, due to serious political differences between the major Powers. By then, both the United States and the former Soviet Union had tested nuclear weapons, and were beginning to build their stockpiles.  In December 1953, US President Dwight D. Eisenhower in his "Atoms for Peace" proposal, presented to the eighth session of the United Nations General Assembly, urged that an international organization be established to disseminate peaceful nuclear technology, while guarding against development of weapons capabilities in additional countries. His proposal resulted in 1957 in the establishment of the International Atomic Energy Agency (IAEA), which was charged with the dual responsibility for promotion and control of nuclear technology. IAEA technical activities began in 1958. An interim safeguards system for small nuclear reactors, put in place in 1961, was replaced in 1964 by a system covering larger installations and, over the following years, was expanded to include additional nuclear facilities. In recent years, efforts to strengthen the effectiveness and improve the efficiency of the IAEA safeguards system culminated in the approval of the Model Additional Protocol by the IAEA Board of Governors in May 1997.  Within the framework of the United Nations, the principle of nuclear non-proliferation was addressed in negotiations as early as 1957. The NPT process was launched by Frank Aiken, Irish Minister for External Affairs, in 1958. The NPT gained significant momentum in the early 1960s. The structure of a treaty to uphold nuclear non-proliferation as a norm of international behaviour had become clear by the mid-1960s, and by 1968 final agreement had been reached on a Treaty that would prevent the proliferation of nuclear weapons, enable cooperation for the peaceful use of nuclear energy, and further the goal of achieving nuclear disarmament. It was opened for signature in 1968, with Finland the first State to sign. Accession became nearly universal after the end of the Cold War and of South African apartheid. In 1992, The People's Republic of China and France acceded to the NPT, the last of the five nuclear powers recognized by the treaty to do so.  The treaty provided, in article X, for a conference to be convened 25 years after its entry into force to decide whether the treaty should continue in force indefinitely, or be extended for an additional fixed period or periods. Accordingly, at the NPT Review and Extension Conference in May 1995, state parties to the treaty agreed-without a vote-on the treaty's indefinite extension, and decided that review conferences should continue to be held every five years. After Brazil acceded to the NPT in 1998, the only remaining non-nuclear-weapon state which had not signed was Cuba, which joined the NPT (and the Treaty of Tlatelolco NWFZ) in 2002.  Several NPT states parties have given up nuclear weapons or nuclear weapons programs. South Africa undertook a nuclear weapons program, but has since renounced it and acceded to the treaty in 1991 after destroying its small nuclear arsenal; after this, the remaining African countries signed the treaty. The former Soviet Republics where nuclear weapons had been based, namely Ukraine, Belarus and Kazakhstan, transferred those weapons to Russia and joined the NPT by 1994 following the signature of the Budapest Memorandum on Security Assurances.  Successor states from the breakups of Yugoslavia and Czechoslovakia also joined the treaty soon after their independence. Montenegro and East Timor were the last countries to accede to the treaty on their independence in 2006 and 2003; the only other country to accede in the 21st century was Cuba in 2002. The three Micronesian countries in Compact of Free Association with the USA joined the NPT in 1995, along with Vanuatu.  Major South American countries Argentina, Chile, and Brazil joined in 1995 and 1998. Arabian Peninsula countries included Saudi Arabia and Bahrain in 1988, Qatar and Kuwait in 1989, UAE in 1995, and Oman in 1997. The European states of Monaco and Andorra joined in 1995–6. Also acceding in the 1990s were Myanmar in 1992 and Guyana in 1993.

Leaving the treaty.

Article X allows a state to leave the treaty if "extraordinary events, related to the subject matter of this Treaty, have jeopardized the supreme interests of its country", giving three months' (ninety days') notice. The state is required to give reasons for leaving the NPT in this notice.  NATO states argue that when there is a state of "general war" the treaty no longer applies, effectively allowing the states involved to leave the treaty with no notice. This is a necessary argument to support the NATO nuclear weapons sharing policy, but a troubling one for the logic of the treaty. NATO's argument is based on the phrase "the consequent need to make every effort to avert the danger of such a war" in the treaty preamble, inserted at the behest of U.S. diplomats, arguing that the treaty would at that point have failed to fulfill its function of prohibiting a general war and thus no longer be binding. Many states do not accept

Recent and coming events.

The main outcome of the 2000 Conference was the adoption by consensus of a comprehensive Final Document, which included among other things "practical steps for the systematic and progressive efforts" to implement the disarmament provisions of the NPT, commonly referred to as the Thirteen Steps.  On 18 July 2005, US President George W. Bush met Indian Prime Minister Manmohan Singh and declared that he would work to change US law and international rules to permit trade in US civilian nuclear technology with India. At the time, British columnist George Monbiot argued that the U.S.-India nuclear deal, in combination with US attempts to deny Iran (an NPT signatory) civilian nuclear fuel-making technology, might destroy the NPT regime.  In the first half of 2010, it was strongly believed that China had signed a civilian nuclear deal with Pakistan claiming that the deal was "peaceful".  Arms control advocates criticised the reported China-Pakistan deal as they did in case of U.S.-India deal claiming that both the deals violate the NPT by facilitating nuclear programmes in states which are not parties to the NPT. Some reports asserted that the deal was a strategic move by China to balance US influence in South-Asia.  According to a report published by U.S. Department of Defense in 2001, China had provided Pakistan with nuclear materials and has given critical technological assistance in the construction of Pakistan's nuclear weapons development facilities, in violation of the Nuclear Non-Proliferation Treaty, of which China even then was a signatory.  At the Seventh Review Conference in May 2005, there were stark differences between the United States, which wanted the conference to focus on non-proliferation, especially on its allegations against Iran, and most other countries, who emphasized the lack of serious nuclear disarmament by the nuclear powers. The non-aligned countries reiterated their position emphasizing the need for nuclear disarmament.  The 2010 Review Conference was held in May 2010 in New York City,

Criticism and responses.

Over the years the NPT has come to be seen by many Third World states as "a conspiracy of the nuclear 'haves' to keep the nuclear 'have-nots' in their place". This argument has roots in Article VI of the treaty which "obligates the nuclear weapons states to liquidate their nuclear stockpiles and pursue complete disarmament. The non-nuclear states see no signs of this happening". Some argue that the NWS have not fully complied with their disarmament obligations under Article VI of the NPT. Some countries such as India have criticized the NPT, because it "discriminated against states not possessing nuclear weapons on January 1, 1967," while Iran and numerous Arab states have criticized Israel for not signing the NPT. There has been disappointment with the limited progress on nuclear disarmament, where the five authorized nuclear weapons states still have 22,000 warheads among them and have shown a reluctance to disarm further.  As noted, the International Court of Justice, in its advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, stated that "there exists an obligation to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament in all its aspects under strict and effective international control. Some critics of the nuclear-weapons states contend that they have failed to comply with Article VI by failing to make disarmament the driving force in national planning and policy with respect to nuclear weapons, even while they ask other states to plan for their security without nuclear weapons.  The United States responds to criticism of its disarmament record by pointing out that, since the end of the Cold War, it has eliminated over 13,000 nuclear weapons, and eliminated over 80% of its deployed strategic warheads and 90% of non-strategic warheads deployed to NATO, in the process eliminating whole categories of warheads and delivery systems and reducing its reliance on nuclear weapons. U.S. officials have also pointed out the ongoing U.S. work to dismantle nuclear warheads. By the time accelerated dismantlement efforts ordered by President George W. Bush were completed, the U.S. arsenal was less than a quarter of its size at the end of the Cold War, and smaller than it had been at any point since the Eisenhower administration, well before the drafting of the NPT.  The United States has also purchased many thousands of weapons' worth of uranium formerly in Soviet nuclear weapons for conversion into reactor fuel. As a consequence of this latter effort, it has been estimated that the equivalent of one lightbulb in every ten in the United States is powered by nuclear fuel removed from warheads previously targeted at the United States and its allies during the Cold War.  The U.S. Special Representative for Nuclear Nonproliferation agreed that nonproliferation and disarmament are linked, noting that they can be mutually reinforcing but also that growing proliferation risks create an environment that makes disarmament more difficult. The United Kingdom, France and Russia likewise defend their nuclear disarmament records, and the five NPT NWS issued a joint statement in 2008 reaffirming their Article VI disarmament commitments.  According to Thomas Reed and Danny Stillman, the "NPT has one giant loophole": Article IV gives each non-nuclear weapon state the 'inalienable right' to pursue nuclear energy for the generation of power. A "number of high-ranking officials, even within the United Nations, have argued that they can do little to stop states using nuclear reactors to produce nuclear weapons". A 2009 United Nations report said that:  The revival of interest in nuclear power could result in the worldwide dissemination of uranium enrichment and spent fuel reprocessing technologies, which present obvious risks of proliferation as these technologies can produce fissile materials that are directly usable in nuclear weapons. According to critics, those states which possess nuclear weapons, but are not authorized to do so under the NPT, have not paid a significant price for their pursuit of weapons capabilities. Also, the NPT has been explicitly weakened by a number of bilateral deals made by NPT signatories, notably the United States.  Based on concerns over the slow pace of nuclear disarmament and the continued reliance on nuclear weapons in military and security concepts, doctrines and policies, the Treaty on the Prohibition of Nuclear Weapons was adopted in July 2017 and was subsequently opened for signature on 20 September 2017. Upon entry into force, it will prohibit each state party from the development, testing, production, stockpiling, stationing, transfer, use and threat of use of nuclear weapons, as well as assistance to those activities. It reaffirms in its preamble the vital role of the full and effective implementation of the NPT.

The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty whose objective is to prevent the spread of nuclear weapons and weapons technology, to promote cooperation in the peaceful uses of nuclear energy, and to further the goal of achieving nuclear disarmament and general and complete disarmament. Between 1965 and 1968, the treaty was negotiated by the Eighteen Nation Committee on Disarmament, a United Nations-sponsored organization based in Geneva, Switzerland.

《不扩散核武器条约》(英语:Treaty on the Non-Proliferation of Nuclear Weapons,缩写NPT),或称《核不扩散条约》(英语:Nuclear Non-Proliferation Treaty,缩写NNPT),1968年7月1日由英国、美国、苏联和其他59个国家缔结签署的一项国际条约,宗旨是防止核扩散、推动核裁军和促进和平利用核能的国际合作。截至2015年2月,共有190个国家与地区签署了该条约。而没有签署这项条约的国家包括印度、巴基斯坦、南苏丹、以色列和中华民国,朝鲜已于2003年宣布退出。


Development.

Background.

In 1963, the United States Air Force started a series of study projects on a very large strategic transport aircraft. Although the C-141 Starlifter was being introduced, officials believed that a much larger and more capable aircraft was needed, especially to carry cargo that would not fit in any existing aircraft. These studies led to initial requirements for the CX-Heavy Logistics System (CX-HLS) in March 1964 for an aircraft with a load capacity of and a speed of Mach 0.75 (), and an unrefueled range of with a payload of. The payload bay had to be wide by high and long with access through doors at the front and rear.  The desire to keep the number of engines to four required new engine designs with greatly increased power and better

Airliner proposal.

The 747 was conceived while air travel was increasing in the 1960s. The era of commercial jet transportation, led by the enormous popularity of the Boeing 707 and Douglas DC-8, had revolutionized long-distance travel. In the early 1960s, even before it lost the CX-HLS contract, Boeing was asked by Juan Trippe, president of Pan American World Airways (Pan Am), one of their most important airline customers, to build a passenger aircraft more than twice the size of the 707. During this time, airport congestion, worsened by increasing numbers of passengers carried on relatively small aircraft, became a problem that Trippe thought could be addressed by a larger new aircraft.  In 1965, Joe Sutter was transferred from Boeing's 737 development team to manage the design studies for the new airliner, already assigned the model number 747. Sutter began a design study

Design effort.

Ultimately, the high-winged CX-HLS Boeing design was not used for the 747, although technologies developed for their bid had an influence. The original design included a full-length double-deck fuselage with eight-across seating and two aisles on the lower deck and seven-across seating and two aisles on the upper deck. However, concern over evacuation routes and limited cargo-carrying capability caused this idea to be scrapped in early 1966 in favor of a wider single deck design. The cockpit was, therefore, placed on a shortened upper deck so that a freight-loading door could be included in the nose cone; this design feature produced the 747's distinctive "hump". In early models it was not clear what to do with the small space in the pod behind the cockpit, and this was initially specified as a "lounge" area with no permanent seating. (A different configuration that had been considered in order to keep the flight deck out of the way for freight loading had the pilots below the passengers, and was dubbed the "anteater".) One of the principal technologies that enabled an aircraft as large as the 747 to be drawn up was the high-bypass turbofan engine. The

Production plant.

As Boeing did not have a plant large enough to assemble the giant airliner, they chose to build a new plant. The company considered locations in about 50 cities, and eventually decided to build the new plant some north of Seattle on a site adjoining a military base at Paine Field near Everett, Washington. It bought the site in June 1966.  Developing the 747 had been a

Development and testing.

Before the first 747 was fully assembled, testing began on many components and systems. One important test involved the evacuation of 560 volunteers from a cabin mock-up via the aircraft's emergency chutes. The first full-scale evacuation took two and a half minutes instead of the maximum of 90 seconds mandated by the Federal Aviation Administration (FAA), and several volunteers were injured. Subsequent test evacuations achieved the 90-second goal but caused more injuries. Most problematic was evacuation from the aircraft's upper deck; instead of using a conventional slide, volunteer passengers escaped by using a harness attached to a reel. Tests also involved

Entry into service.

On January 15, 1970, First Lady of the United States Pat Nixon christened Pan Am's first 747, at Dulles International Airport (later Washington Dulles International Airport) in the presence of Pan Am chairman Najeeb Halaby. Instead of champagne, red, white, and blue water was sprayed on the aircraft. The 747 entered service on January 22, 1970, on Pan Am's New York–London route; the flight had been planned for the evening of January 21, but engine overheating made the original aircraft

Improved 747 versions.

After the initial, Boeing developed the, a higher maximum takeoff weight (MTOW) variant, and the (Short Range), with higher passenger capacity. Increased maximum takeoff weight allows aircraft to carry more fuel and have longer range. The model followed in 1971, featuring more powerful engines and a higher MTOW. Passenger, freighter and combination passenger-freighter versions of the were produced. The shortened 747SP (special performance) with a longer range was also developed, and entered service in 1976.  The 747 line was further developed with the launch of the on June 11, 1980, followed by interest from Swissair a month later and the go-ahead for the project. The 300 series resulted from Boeing studies to increase the seating capacity of the 747, during which modifications such as fuselage plugs and extending the upper deck over the entire length of the fuselage were rejected. The first, completed in 1983, included a

Further developments.

Since the arrival of the, several stretching schemes for the 747 have been proposed. Boeing announced the larger 747-500X and preliminary designs in 1996. The new variants would have cost more than US$5 billion to develop, and interest was not sufficient to launch the program. In 2000, Boeing offered the more modest 747X and 747X stretch derivatives as alternatives to the Airbus A3XX. However, the 747X family was unable to attract enough interest to enter production. A year later, Boeing switched from the 747X studies to pursue

Design.

The Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. Its wings have a high sweep angle of 37.5 degrees for a fast, efficient cruise speed of Mach 0.84 to 0.88, depending on the variant. The sweep also reduces the wingspan, allowing the 747 to use existing hangars. Its seating capacity is over 366 with a 3–4–3 seat arrangement (a cross section of 3 seats, an aisle, 4 seats, another aisle, and 3 seats) in economy class and a 2–3–2 layout in first class on the main deck. The upper deck has a 3–3 seat arrangement in economy class and a 2–2 layout in first class. Raised above the main deck, the cockpit creates a hump. This raised cockpit allows front loading of cargo on freight variants. The upper deck behind the cockpit provides space for a lounge and/or extra seating. The "stretched upper deck" became available as an alternative on the variant and later as standard beginning on the

Variants.

The 747-100 was the original variant launched in 1966. The 747-200 soon followed, with its launch in 1968. The 747-300 was launched in 1980 and was followed by the in 1985. Ultimately, the 747-8 was announced in 2005. Several versions of each variant have been produced, and many of the early variants were in production simultaneously. The International Civil Aviation Organization (ICAO) classifies variants using a shortened code formed by combining the model number and the variant designator (e.g. "B741" for all -100 models).

747-100.

The first 747-100s were built with six upper deck windows (three per side) to accommodate upstairs lounge areas. Later, as airlines began to use the upper deck for premium passenger seating instead of lounge space, Boeing offered a ten-window upper deck as an option. Some early -100s were retrofitted with the new configuration. The -100 was equipped with Pratt & Whitney JT9D-3A engines. No freighter version of this model was developed, but many 747-100s were converted into freighters. A total of 168 747-100s were built; 167 were delivered to customers, while Boeing kept the prototype, "City of Everett".

747SR.

Responding to requests from Japanese airlines for a high-capacity aircraft to serve domestic routes between major cities, Boeing developed the 747SR as a short-range version of the with lower fuel capacity and greater payload capability. With increased economy class seating, up to 498 passengers could be carried in early versions and up to 550 in later models. The 747SR had an economic design life objective of 52,000 flights during 20 years of operation, compared to 24,600 flights in 20 years for the standard 747. The initial 747SR model, the -100SR, had a strengthened body structure and landing gear to accommodate the added stress accumulated from a greater number of takeoffs and landings. Extra structural support was built into the wings, fuselage, and the landing gear along with a 20% reduction in fuel capacity. The initial order for the -100SR – four aircraft for Japan Air Lines (JAL, later Japan Airlines) – was announced on October 30, 1972; rollout occurred on August 3, 1973, and the first flight took place on August 31, 1973. The type

747-100B.

The 747-100B model was developed from the -100SR, using its stronger airframe and landing gear design. The type had an increased fuel capacity of, allowing for a range with a typical 452-passenger payload, and an increased MTOW of was offered. The first -100B order, one aircraft for Iran Air, was announced on June 1, 1978. This aircraft first flew on June 20, 1979, received FAA certification on August 1, 1979, and was delivered the next day. Nine -100Bs were built, one for Iran Air and eight for Saudi Arabian Airlines. Unlike the original -100, the -100B was offered with Pratt & Whitney JT9D-7A, General Electric CF6-50, or Rolls-Royce RB211-524 engines. However, only RB211-524 (Saudia) and JT9D-7A (Iran Air) engines were ordered. The last 747-100B, EP-IAM was retired by Iran Air in 2014, the last commercial operator of the 747-100 and -100B.

747SP.

The development of the 747SP stemmed from a joint request between Pan American World Airways and Iran Air, who were looking for a high-capacity airliner with enough range to cover Pan Am's New York–Middle Eastern routes and Iran Air's planned Tehran–New York route. The Tehran–New York route, when launched, was the longest non-stop commercial flight in the world. The 747SP is shorter than the. Fuselage sections were eliminated fore and aft of the wing, and the center section of the fuselage was redesigned to fit mating fuselage sections. The SP's flaps used a simplified single-slotted configuration. The 747SP, compared to

747-200.

While the 747-100 powered by Pratt & Whitney JT9D-3A engines offered enough payload and range for medium-haul operations, it was marginal for long-haul route sectors. The demand for longer range aircraft with increased payload quickly led to the improved -200, which featured more powerful engines, increased MTOW, and greater range than the -100. A few early -200s retained the three-window configuration of the -100 on the upper deck, but most were built with a ten-window configuration on each side. The

747-300.

The 747-300 features a upper deck than the -200. The stretched upper deck (SUD) has two emergency exit doors and is the most visible difference between the -300 and previous models. After being made standard on the 747-300, the SUD was offered as a retrofit, and as an option to earlier variants still in-production. An example for a retrofit were two UTA -200 Combis being converted in 1986, and an example for the option were two brand-new JAL -100 aircraft (designated -100BSR SUD), the first of which was delivered on March 24, 1986.  The 747-300 introduced a new straight stairway to the upper deck, instead of a spiral staircase on earlier variants, which creates room above and below for more seats. Minor aerodynamic changes allowed the -300's cruise speed to reach Mach 0.85 compared with Mach 0.84 on the -200 and -100 models, while retaining the same takeoff weight. The -300 could be equipped with the same Pratt & Whitney and Rolls-Royce powerplants as on the -200, as well as updated General Electric CF6-80C2B1 engines.  Swissair

747-400.

The 747-400 is an improved model with increased range. It has wingtip extensions of and winglets of, which improve the type's fuel efficiency by four percent compared to previous 747 versions. The 747-400 introduced a new glass cockpit designed for a flight crew of two instead of three, with a reduction in the number of dials, gauges and knobs from 971 to 365 through the use of electronics. The type also features tail fuel tanks, revised engines, and a new interior. The longer range has been used by some airlines to bypass traditional fuel stops, such as Anchorage. Powerplants include the Pratt & Whitney PW4062, General Electric CF6-80C2, and Rolls-Royce RB211-524. As a result of the Boeing 767 development overlapping with the 747-400's development, both aircraft can use the same three powerplants and are even interchangeable between the two aircraft models.  The was offered in passenger (-400), freighter (-400F), combi (-400M), domestic (-400D), extended range passenger (-400ER), and extended range freighter (-400ERF) versions. Passenger versions retain the same upper deck

747-8.

Boeing announced a new 747 variant, the, on November 14, 2005. Referred to as the 747 Advanced prior to its launch, the 747-8 uses the same engine and cockpit technology as the 787, hence the use of the "8". The variant is designed to be quieter, more economical, and more environmentally friendly. The 747-8's fuselage is lengthened from 232 to 251 feet (70.8 to 76.4 m), marking the first stretch variant of the aircraft. Power is supplied by General Electric GEnx-2B67 engines.  The 747-8 Freighter, or 747-8F, is derived from the 747-400ERF. The variant has 16% more payload capacity than its predecessor, allowing it to carry seven more standard air cargo containers, with a maximum payload capacity

Undeveloped variants.

Boeing has studied a number of 747 variants that have not gone beyond the concept stage.

747 trijet.

During the late 1960s and early 1970s, Boeing studied the development of a shorter 747 with three engines, to compete with the smaller Lockheed L-1011 TriStar and McDonnell Douglas DC-10. The center engine would have been fitted in the tail with an

747-500.

In January 1986, Boeing outlined preliminary studies to build a larger, ultra-long haul version named the, which would enter service in the mid- to late-1990s. The derivative would use more efficient unducted fan (UDF) engines

747 ASB.

Boeing announced the 747 ASB ("Advanced Short Body") in 1986 as a response to the Airbus A340 and the McDonnell Douglas MD-11. This aircraft design would have combined

747-500X, -600X, and -700X.

Boeing announced the 747-500X and -600X at the 1996 Farnborough Airshow. The proposed models would have combined the 747's fuselage with a new 251 ft (77 m) span wing derived from the 777. Other changes included adding more powerful engines and increasing the number of tires from two to four on the nose landing gear and from 16 to 20 on the main landing gear.  The 747-500X concept featured an increased fuselage length of 18 ft (5.5 m) to 250 ft (76.2 m) long, and the aircraft was

747X and 747X Stretch.

As Airbus progressed with its A3XX study, Boeing offered a 747 derivative as an alternative in 2000; a more modest proposal than the previous -500X and -600X that retained the 747's overall wing design and add a segment at the root, increasing the span to. Power would have been supplied by either the Engine Alliance GP7172 or the Rolls-Royce Trent 600, which were also proposed for the 767-400ERX. A new flight deck based on the 777's would be used. The 747X aircraft was to carry 430 passengers over ranges

747-400XQLR.

After the end of the 747X program, Boeing continued to study improvements that could be made to the 747. The 747-400XQLR (Quiet Long Range) was meant to have an increased range of 7,980 nmi (9,200 mi, 14,800 km), with improvements to boost efficiency and reduce noise. Improvements studied included raked wingtips similar to those used on the 767-400ER and a sawtooth engine nacelle for noise reduction. Although the 747-400XQLR did not move to production, many of its features were used for the 747 Advanced, which has now been launched as the 747-8.

Operators.

, there were 462 Boeing 747s in airline service, with Atlas Airlines and British Airways being the largest operators with 33 747-400s each.  The last US passenger Boeing 747 was retired from Delta Air Lines in December 2017, after it flew for every American major carrier since its 1970 introduction. Delta flew three of its last four aircraft on a farewell tour, from Seattle to Atlanta on December 19 then to Los Angeles and Minneapolis/St Paul on December 20.  As the IATA forecast an increase in air freight from 4% to 5% in 2018 fuelled by booming trade for time-sensitive goods, from smartphones to fresh flowers, demand for freighters is strong while passenger 747s are phased out. Of the 1,544 produced, 890 are retired;, a small subset of those which were intended to be parted-out get $3 million D-checks before flying again. Young -400s are sold for 320 million yuan ($50 million) and Boeing stopped converting freighters, which used to cost nearly $30 million. This comeback helped the airframer financing arm Boeing Capital to shrink its exposure to the 747-8 from $1.07 billion in 2017 to $481 million in 2018.

Orders and deliveries.

Boeing 747 orders

Accidents and incidents.

As of February 2019, the 747 has been involved in 162 aviation accidents and incidents, including 63 accidents and hull losses which resulted in fatalities. The last crash was Turkish Airlines Flight 6491 in January 2017. There have been several hijackings of Boeing 747s, such as Pan Am Flight 73 where a Boeing 747-121 was hijacked by four terrorists and resulted in 20 deaths.  Few crashes have been attributed to design flaws of the 747. The Tenerife airport disaster resulted from pilot error and communications failure, while the Japan Airlines Flight 123 and China Airlines Flight 611 crashes stemmed from improper aircraft repair. United Airlines Flight 811, which suffered an explosive decompression mid-flight on February 24, 1989, led the National Transportation Safety Board (NTSB) to issue

Aircraft on display.

As increasing numbers of "classic" 747-100 and series aircraft have been retired, some have found their way into museums or other uses. In recent years, some older 747-300s and 747-400s have also found their way into museums as well.

Other uses.

Upon its retirement from service, the 747 number two in the production line was dismantled and shipped to Hopyeong, Namyangju, Gyeonggi-do, South Korea where it was re-assembled, repainted in a livery similar to that of Air Force One and converted into a restaurant. Originally flown commercially by Pan Am as N747PA, "Clipper Juan T. Trippe", and repaired for service following a tailstrike, it stayed with the airline until

Notable appearances in media.

Following its debut, the 747 rapidly achieved iconic status, appearing in numerous film productions such as "Airport 1975" and "Airport '77" disaster films, "Air Force One", "Die Hard 2", and "Executive Decision". Appearing in over 300 film productions the 747 is one of the most widely depicted civilian aircraft and is considered by many as one of the most iconic in film history. The aircraft entered the cultural lexicon as the original "Jumbo Jet", a term coined by the aviation media to describe its size, and was also nicknamed "Queen of the Skies".

The Boeing 747 is a large, long–range wide-body airliner and cargo aircraft manufactured by Boeing Commercial Airplanes in the United States.

波音747,又称为「珍宝客机」(Jumbo Jet)亦是全世界首款生产出的广体民航机,由美国波音民用飞机集团制造。波音747雏型的大小是1960年代被广泛使用的波音707的两倍,飞机翼展比莱特兄弟的首次飞行距离还要长。自1970年投入服务后,到2007年A380投入服务之前,波音747保持全世界载客量最高飞机的纪录长达37年。


Religions.

Eschatology is a part of theology concerned with the final events of history, or the ultimate destiny of humanity. This concept is commonly referred to as the "end of the world" or "end times". The word arises from the Greek "eschatos" meaning "last" and "-logy" meaning "the study of", and first appeared in English around 1844. The "Oxford English Dictionary" defines eschatology as "the part of theology concerned with death, judgment, and the final destiny of the soul and of humankind".  History can be divided into "ages" (aeons), which are time periods each with certain commonalities. One age comes to an end and a new age or world to come begins. When such transitions are the subject of eschatological discussion, the phrase, "end of the world", is replaced by "end of the age", "end of an era", or "end of life as we know it". Much apocalyptic fiction does not deal with the "end of time" but rather with the end of a certain period, the end of life as it is now, and the beginning of a new period. The transitioning crisis may take the form of the intervention of a deity in history, a war, a change in the environment, or the reaching of a new level of consciousness.  In modern eschatology and apocalypticism both religious and secular scenarios may involve the violent disruption or destruction of the world; whereas Christian and Jewish eschatologies view the end times as the consummation or perfection of God's creation of the world, albeit with violent overtures, such as the Great Tribulation.

Bahá'í.

In the Bahá'í system of belief, creation does not begin and does not end and is not cyclical. Instead, the eschatology of other religions is viewed as symbolic and human time is marked by a series of progressive revelations in which successive messengers or prophets come from God. The coming of each of these messengers is seen as the

Buddhism.

Buddha described his teachings as disappearing five thousand years from when he died, corresponding approximately to the year 4600 CE. He also said that at this time knowledge of dharma will also be lost. The last of his relics will be gathered in Bodh

Christianity.

Some scholars believe that Jesus' apocalyptic teachings were the central message Jesus intended to impart, more central even than his messianism. He even said to his disciples, "This generation shall not pass away before all of these things have been fulfilled.", and as James Tabor said, that is a very specific promise.  Various Christian eschatological systems have developed, providing different frameworks for understanding the timing and nature of apocalyptic predictions. Some like dispensational premillennialism tend more toward an apocalyptic vision, while others like postmillennialism and amillennialism, while teaching that the end of the world could come at any moment, tend to focus on the present life and contend that one should not attempt to predict when the end should come, though there have been exceptions such as postmillennialist Jonathan Edwards, who estimated that the end times would occur around the year 2000.

Christadelphians.

For Christadelphians, Armageddon marks the "great climax of history when the nations would be gathered together "into a place called in the Hebrew tongue Armageddon", and the judgment on them would herald the setting up of the Kingdom of God." After this Christadelphians believe

Jesus.

The gospels portray Jesus as an apocalyptic prophet, described by himself and by others as the Son of Man and hailing the restoration of Israel. Jesus himself, as the Son of God (a designation used both by himself and by others) was to rule this kingdom as lord of the Twelve Apostles, the judges of the twelve tribes.  Albert Schweitzer emphasized that Jesus was an apocalyptic prophet, preparing his fellow Jews for the imminent end of the world. Many historians concur that Jesus was an apocalyptic prophet, most notably Paula Fredriksen, Bart Ehrman, and John P. Meier. E. P. Sanders portrays Jesus as expecting to assume the "viceroy" position in God's kingdom, above the Apostles, who would judge the twelve tribes, but below God. He concludes, however, that Jesus seems to have rejected the title Messiah, and he contends that the evidence is uncertain as to whether Jesus meant himself when he referred to the Son of Man coming on the

Year 1000.

There are a few recorded instances of apocalypticism leading up to the year 1000. However they mostly rely on one source, Rodulfus Glaber.  Specifically in Western Europe, during the year 1000, Christian philosophers held many debates on when Jesus was actually born and the debates continue to today. This caused confusion between the common people on whether or not the apocalypse would occur at a certain time. Because both literate and illiterate people commonly accepted this idea of the apocalypse, they could only accept what they heard from religious leaders on when the disastrous event would occur. Religious leader, Abbo II of Metz believed that Jesus was born 21 years after year

Fifth Monarchy Men.

The Fifth Monarchists or Fifth Monarchy Men were an extreme Puritan sect active from 1649 to 1660 during the Interregnum, following the English Civil Wars of the 17th century. They took their name from a prophecy in the Book

Isaac Newton and the end of the world in 2060.

In late February and early March 2003, a large amount of media attention circulated around the globe regarding largely unknown and unpublished documents, evidently written by Isaac Newton, indicating that he believed the world would end no earlier than 2060. The story garnered vast amounts of public interest and found its way onto the front page of several widely distributed newspapers, including the UK's Daily Telegraph, Canada's National Post, Israel's Maariv and Yediot Aharonot, and was also featured in an article in the scientific journal "Canadian Journal of History".  The two documents detailing this prediction are currently housed within the Jewish National and University Library in Jerusalem. Both were believed to be written toward the end of Newton's life, circa 1705, a time frame most notably established by the use of the full title of "Sir" Isaac Newton within portions

Millerites and The Great Disappointment.

The Great Disappointment in the Millerite movement was the reaction that followed Baptist preacher William Miller's proclamations that Jesus Christ would return to the Earth by 1844, what he called the Advent. His study of the Daniel 8 prophecy during the Second Great Awakening led him to the conclusion that Daniel's "cleansing of the sanctuary" was cleansing of the world from sin when Christ would come, and he and many others prepared, but October 22, 1844, came and they were disappointed.  These events paved the way for the Adventists who formed the Seventh-day Adventist Church. They contended that what had happened on October 22 was not Jesus' return, as Miller had thought, but the start of Jesus' final work of atonement, the cleansing in the heavenly sanctuary, leading up to the Second Coming.

Mormonism.

Like many 19th-century American Protestant churches, the Mormon tradition teaches that adherents are living shortly before the Second Coming of Christ. The term "latter days" is used in the official names of several Mormon churches, including The Church of Jesus Christ of Latter-day Saints.

Jehovah's Witnesses.

The eschatology of Jehovah's Witnesses is central to their religious beliefs. They believe that Jesus Christ has been ruling in heaven as king since 1914 (a date they believe was prophesied in Scripture), and that after that time a period of cleansing occurred, resulting in God's selection of the Bible Students associated with Charles Taze Russell to be his people in 1919. They also believe the destruction of those who reject their message and thus willfully refuse to obey God will shortly take place at Armageddon, ensuring that the beginning of the new earthly society will be composed of willing subjects of that kingdom.  The group's doctrines surrounding 1914 are the legacy of a series of emphatic claims regarding the years 1799, 1874, 1878, 1914, 1918 and 1925 made in the Watch Tower Society's publications between 1879 and 1924. Claims about the significance of those years, including the presence of Jesus Christ, the beginning of

Realized eschatology.

Realized eschatology is a Christian eschatological theory popularized by J.A.T. Robinson, Joachim Jeremias, Ethelbert Stauffer (1902- 1979), and C. H. Dodd (1884–1973) that holds that the eschatological passages in the New Testament do not refer to the future, but instead refer to the ministry of Jesus and his lasting legacy. Eschatology is therefore not the end of the world but its rebirth instituted by Jesus and continued by his disciples, a historical (rather than transhistorical) phenomenon. Those holding this view generally dismiss end times theories, believing them to be irrelevant; they hold that what Jesus said and did, and told his disciples to do likewise, are of greater significance than any messianic expectations.

Hinduism.

According to Hindu cosmology, this universe lasts as long as the life of Brahma (311.04 trillion years, half of which has passed). At the end of Brahma's life, all material elements return to a state of "Prakriti" (unmixed, unmanifested). Within his 100-year lifespan are 360-day years where each "Day" (8.64 billion years) is divided into a day- and night-"Kalpa" (4.32 billion years). Planets (Earth included) and their life are cyclically created at the start of his day-"Kalpa"

Islam.

Islamic eschatology is the aspect of Islamic theology concerning ideas of life after death, matters of the soul, and the "Day of Judgement," known as "Yawm al-Qiyāmah" (,, "the Day of Resurrection") or "Yawm ad-Dīn" (,, "the Day of Judgment").> The Day of Judgement is characterized by the annihilation of all life, which will then be followed by the resurrection and judgment by God. It is not specified when al-Qiyamah will happen, but according to prophecy elaborated by hadith-literature, there are major and minor signs that will foretell its coming. Multiple verses in the Qur'an mention the Last Judgment.  The main subject of Surat al-Qiyama is the resurrection. The Great Tribulation is described in the hadith and commentaries of

Jainism.

According to Jainism, time is beginningless and eternal. The "Kālacakra", the cosmic wheel of time, rotates ceaselessly. The wheel of time is divided into two half-rotations, "Utsarpiṇī" or ascending time cycle and "Avasarpiṇī", the descending time cycle, occurring continuously after each other.  "Utsarpiṇī" is a period of progressive prosperity and happiness where the time spans and ages are at an increasing scale, while "Avsarpiṇī" is a period of increasing sorrow and immorality with decline in timespans of the epochs. Each of this half time cycle consisting of innumerable period of time (measured in "sagaropama" and "palyopama" years) is further sub-divided into six आरा "(aras)" or epochs of unequal periods.  The 6 "aras" are as follows:  The first four aras constitute millions and billions of years, whereas the last two are of 21000 years each. No divine or supernatural beings are credited or responsible with these spontaneous temporal changes, either

Judaism.

According to some ancient Hebrew worldviews, reality unfolds along a linear path (or rather, a spiral path, with cyclical components that nonetheless have a linear trajectory); the world began with God and is ultimately headed toward God's final goal for creation, the world to come. The main textual source for the belief in the end of days and accompanying events is the Tanakh or Hebrew Bible. The roots of Jewish eschatology are to be found in the pre-exile Prophets,

Norse.

Ragnarök is an important event in Norse mythology and has been the subject of scholarly discourse and theory in the history of Germanic studies and is attested primarily in the "Poetic Edda", compiled in the 13th century from earlier traditional sources and the "Prose Edda", written in the 13th century by Snorri Sturluson. In the "Prose Edda" and in a single poem in the "Poetic Edda", the event is referred to as "Ragnarök" or "Ragnarøkkr" (), a usage popularised by 19th-century composer Richard Wagner with the title of the last of his "Der Ring des Nibelungen" operas, "Götterdämmerung" (1876), which is "Twilight of the Gods" in German. There are various theories and interpretations of Ragnarök.

Cyclic time and "Hoddmímis holt".

Rudolf Simek theorizes that the survival of Líf and Lífþrasir at the end of Ragnarök is "a case of reduplication of the anthropogeny, understandable from the cyclic nature of the Eddic eschatology". Simek says that Hoddmímis holt "should not be understood literally as a wood or even a forest in which the two keep themselves hidden, but rather as an alternative name for the world-tree

"Muspille", "Heliand", and Christianity.

Theories have been proposed about the relation between Ragnarök and the 9th century Old High German epic poem "Muspilli" about the Christian Last Judgment, where the word "Muspille" appears, and the 9th century Old Saxon epic poem "Heliand" about the life of

Proto-Indo-European basis.

Parallels have been pointed out between the Ragnarök of Norse religion and the beliefs of other related Indo-European peoples. Subsequently, theories have been put forth that Ragnarök represents a later evolution of a Proto-Indo-European belief along with other cultures descending from the Proto-Indo-Europeans. These parallels include comparisons of a

Volcanic eruptions.

Hilda Ellis Davidson theorizes that the events in "Völuspá" occurring after the death of the gods (the sun turning black, steam rising, flames touching the heavens, etc.) may be inspired by the volcanic eruptions on Iceland. Records of eruptions on Iceland bear strong

"Bergbúa þáttr".

Parallels have been pointed out between a poem spoken by a jötunn found in the 13th century þáttr "Bergbúa þáttr" ("the tale of the mountain dweller"). In the tale, Thórd and his servant get lost while traveling to church in winter, and so take shelter for the night within a cave. Inside the cave they hear noises, witness a pair of immense burning eyes, and then the being

Modern influences.

In late 2013 and early 2014, English-language media outlets widely reported that Ragnarök was foretold to occur on 22 February 2014. Apparently patterned after the 2012 phenomenon, the claim was at times attributed to a "Viking Calendar". No such calendar is known to have existed, and the source was a "prediction" made to media outlets by the Jorvik Viking Centre in York, England, intended to draw attention to an event that the institution was to hold on that date. The Jorvik Viking Centre was criticized for misleading the public to promote the event. In a 2014 article on the claims, philologist Joseph S. Hopkins perceives the media response as an example of a broad revival of interest in the Viking Age and ancient Germanic topics.

Zoroastrian.

The eschatological ideas are only alluded to in the surviving texts of the Avesta, and are known of in detail only from the texts of Zoroastrian tradition, in particular in the ca. 9th century "Bundahishn". The accompanying story, as it appears in the "Bundahishn" ("GBd" 30.1ff), runs as follows: At the end of the "third time" (the first being the age of creation, the second of mixture, and the third of separation), there will be a great battle between the forces of good (the "yazata"s) and those of evil (the "daeva"s) in which the good will triumph. On earth, the Saoshyant will bring about a resurrection of the dead in the bodies they had before they died. This is followed by a last judgment through ordeal. The "yazata"s Airyaman and Atar will melt the metal in the hills and mountains, and the molten metal will then flow across the earth like a river. All mankind—both the living and the resurrected

Contemporary religious.

Branch Davidians.

The Branch Davidians (also known as The Branch) are a religious group that originated in 1955 from a schism among the Shepherd's Rod/Davidians. The Branch group was initially led by Benjamin Roden. Branch Davidians are most associated with the Waco siege of 1993, which involved David Koresh. There is documented evidence (FBI negotiation transcripts between Kathryn Shroeder and Steve Schneider with interjections from Koresh himself) that David Koresh and his followers did not call themselves Branch Davidians. In addition, David Koresh, through forgery, stole the identity of the Branch Davidian Seventh-day Adventists for the purpose of obtaining the Mount Carmel Center property. The doctrinal beliefs of the Branch Davidians differ on teachings such as the Holy Spirit and his nature, and the feast days and their requirements. Both groups have disputed the relevance of the other's spiritual authority based on the proceedings following Victor

Harold Camping.

American Christian radio host Harold Camping stated that the Rapture and Judgment Day would take place on May 21, 2011, and that the end of the world would take place five months later on October 21, 2011, based on adding the 153 fish of John 20 to May 21. The Rapture, as indicated in 1 Thessalonians 4:17 ("harpagēsometha" = we shall be raptured / taken up, "rapture" derivable from the Latin translation "rapiemur") is the taking up of believers to a meeting in the air with the Lord Jesus, but for Camping the rapture was also associated with the End of the World.  Camping, who was then president of the Family Radio Christian network, claimed the Bible as his source and said May 21 would be the date of the Rapture and the day of judgment "beyond the shadow of a doubt". Camping suggested that it would occur at 6 pm local time, with the Rapture sweeping the globe time zone

UFO religions.

UFO religions sometimes feature an anticipated end-time in which extraterrestrial beings will bring about a radical change on Earth or lift the religious believers to a higher plane of existence. One such religious group's failed expectations of such an event served as the basis for the

Mayan calendar 2012.

The 2012 phenomenon was a range of eschatological beliefs that cataclysmic or otherwise transformative events would occur on or around 21 December 2012. This date was regarded as the end-date of a 5,126-year-long cycle in the Mesoamerican Long Count calendar, and as such, festivities to commemorate the date took place on 21 December 2012 in the countries that were part of the Maya civilization (Mexico, Guatemala, Honduras, and El Salvador), with main events at Chichén Itzá in Mexico, and Tikal in Guatemala.  Various astronomical alignments and numerological formulae were proposed as pertaining to this date. A New Age interpretation held

David Meade.

David Meade is the pen name of an American end-times conspiracy theorist and book author who has yet to disclose his real name. Meade, who describes himself as a "Christian numerologist", claims to have attended the University of Louisville, where he "studied astronomy, among other subjects", but, because his real name is unknown, "The Washington Post" reported that the university could not confirm whether he had ever been a student there. He is also a writer, researcher and investigator who has written and self-published at least 13 books. He made appearances and interviews on "Coast to Coast AM", "The Washington Post", "Glenn Beck Program", YouTube with pastor Paul Begley, and the "Daily Express". He is best known for making numerous predictions, which have

Apocalypticism is the religious belief that there will be an apocalypse, a term which originally referred to a revelation, but now it usually refers to the belief that the end of the world is imminent, even within one's own lifetime. This belief is usually accompanied by the idea that civilization will soon come to a tumultuous end due to some sort of catastrophic global event. These views and movements often focus on cryptic revelations about a sudden, dramatic, and cataclysmic intervention of God in history; the judgment of all men; the salvation of the faithful elect; and the eventual rule of the elect with God in a renewed heaven and earth. Arising initially in Zoroastrianism, apocalypticism was developed more fully in Judaic, Christian, and Islamic eschatological speculation.

启示文学(英文:Apocalyptic),可指一个神学运动,或是该运动的代表性文体。这种特别的现象不是一种群体本身,而是在许多不同群体里出现的特别观点。它产生出大量引人入胜的文学作品,有的存留至今。他们相信世上的邪恶日亦增多、时代的终结趋近,并且神将会决定性的介入,以展开新的时代。犹太教与基督教皆有启示文学,它的独特性可见于《圣经》旧约里的但以理书、撒迦利亚书、以西结书、以赛亚书、约珥书,以及《圣经》新约里的马太福音和启示录。 《圣经》先知或其作者透过特殊的异象或异梦,偶然看到天上的事、超自然的景象,甚至被提到天庭,神借此向他们揭示将来,尤其是关于末世的隐藏之奥秘信息。 圣经启示文学通常是要安慰正在受苦或受欺压、逼迫的神之子民,使人类明白神将是历史的终结,其地上的国亦在神的掌管下,终有一天神的国会取代。使处于绝望中的人略见未来,得以相信神是永恒、今世与来世的盼望。


Early life and education.

Ellington was born on April 29, 1899, to James Edward Ellington and Daisy (Kennedy) Ellington in Washington, D.C. Both his parents were pianists. Daisy primarily played parlor songs, and James preferred operatic arias. They lived with Daisy's parents at 2129 Ida Place (now Ward Place), NW, in D.C.'s West End neighborhood. Duke's father was born in Lincolnton, North Carolina, on April 15, 1879, and moved to D.C. in 1886 with his parents. Daisy Kennedy was born in Washington, D.C., on January 4, 1879, the daughter of a former American slave. James Ellington made blueprints for the United States Navy.  When Edward Ellington was a child, his family showed racial pride and support in their home, as did many other families. African Americans in D.C. worked to protect their children from the era's Jim Crow laws.  At age seven, Ellington began taking piano lessons from Marietta Clinkscales. Daisy surrounded her son with dignified women to reinforce his manners and teach him elegance. His childhood friends noticed that his casual, offhand manner and dapper dress gave him the bearing of a young nobleman, so they began calling him "Duke". Ellington credited his friend Edgar McEntree for the nickname. "I think he felt that in order for me to be eligible for his constant companionship, I should have a title. So he called me Duke."  Though Ellington took piano lessons, he was more interested in baseball. "President Roosevelt (Teddy) would come by on his horse sometimes, and stop and watch us play", he recalled. Ellington went to Armstrong

Career.

Early career.

Working as a freelance sign-painter from 1917, Ellington began assembling groups to play for dances. In 1919 he met drummer Sonny Greer from New Jersey, who encouraged Ellington's ambition to become a professional musician. Ellington built his music business through his day job: when a customer asked him to make a sign for a dance or party, he would ask if they had musical entertainment; if not, Ellington would offer to play for the occasion. He also had a messenger job with the U.S. Navy and State departments, where he made a wide range of contacts.

Cotton Club engagement.

In October 1926, Ellington made an agreement with agent-publisher Irving Mills, giving Mills a 45% interest in Ellington's future. Mills had an eye for new talent and published compositions by Hoagy Carmichael, Dorothy Fields, and Harold Arlen early in their careers. After recording a handful of acoustic titles during 1924–26, Ellington's signing with Mills allowed him to record prolifically, although sometimes he recorded different versions of the same tune. Mills often took a co-composer credit. From the beginning of their relationship, Mills arranged recording sessions on nearly every label including Brunswick, Victor, Columbia, OKeh, Pathê (and its Perfect label), the ARC/Plaza group of labels (Oriole, Domino, Jewel, Banner)

The early 1930s.

Ellington led the orchestra by conducting from the keyboard using piano cues and visual gestures; very rarely did he conduct using a baton. By 1932 his orchestra consisted of six brass instruments, four reeds, and a four-man rhythm section. As a bandleader, Ellington was not a strict disciplinarian; he maintained control of his orchestra with a combination of charm, humor, flattery and astute psychology. A complex, private person, he revealed his feelings to only his closest intimates and effectively used his public persona to deflect

The later 1930s.

From 1936, Ellington began to make recordings with smaller groups (sextets, octets, and nonets) drawn from his then-15-man orchestra and he composed pieces intended to feature a specific instrumentalist, as with "Jeep's Blues" for Johnny Hodges, "Yearning for Love" for Lawrence Brown, "Trumpet in Spades" for Rex Stewart, "Echoes of Harlem" for Cootie Williams and "Clarinet Lament" for Barney Bigard. In 1937, Ellington returned to the Cotton Club, which had relocated to the mid-town Theater District. In the summer of that year, his father died, and due to many expenses, Ellington's finances were tight, although his situation improved the following year.  After leaving agent Irving Mills, he signed on with the William Morris Agency. Mills though continued to record Ellington. After only a year, his Master and Variety labels (the small groups

Ellington in the early to mid-1940s.

Some of the musicians who joined Ellington at this time created a sensation in their own right. The short-lived Jimmy Blanton transformed the use of double bass in jazz, allowing it to function as a solo/melodic instrument rather than a rhythm instrument alone. Terminal illness forced him to leave by late 1941 after only about two years. Ben Webster, the Orchestra's first regular tenor saxophonist, whose main tenure with Ellington spanned 1939 to 1943, started a rivalry with Johnny Hodges as the Orchestra's foremost voice in the sax section.  Trumpeter Ray Nance joined, replacing Cootie Williams who had defected to Benny Goodman. Additionally, Nance added violin to the instrumental colors Ellington had at

Early post-war years.

Musicians enlisting in the military and travel restrictions made touring difficult for the big bands and dancing became subject to a new tax, which continued for many years, affecting the choices of club owners. By the time World War II ended, the focus of popular music was shifting towards singing crooners such as Frank Sinatra and Jo Stafford. As the cost of hiring big bands had increased, club owners now found smaller jazz groups more cost-effective. Some of Ellington's new works, such as the wordless vocal feature "Transblucency" (1946) with Kay Davis, was not going to have a similar reach as the newly emerging stars. Ellington continued on his own course through these tectonic shifts. While Count Basie was forced to disband his whole ensemble and work as an octet for a time, Ellington was able to tour most of Western Europe between April 6 and June 30, 1950, with the orchestra playing 74 dates over 77 days. During the tour, according to Sonny Greer, the newer works were not performed, though Ellington's extended

Career revival.

Ellington's appearance at the Newport Jazz Festival on July 7, 1956 returned him to wider prominence and introduced him to a new generation of fans. The feature "Diminuendo and Crescendo in Blue" comprised two tunes that had been in the band's book since 1937 but largely forgotten until Ellington, who had abruptly ended the band's scheduled set because of the late arrival of four key players, called the two tunes as the time was approaching midnight. Announcing that the two pieces would be separated by an interlude played by tenor saxophonist Paul Gonsalves, Ellington proceeded to lead the band through the two pieces, with Gonsalves' 27-chorus marathon solo whipping the crowd into a frenzy, leading the Maestro to play way beyond the curfew time despite urgent pleas from festival organizer George Wein to bring the program to an end.  The concert made international headlines, led to one of only five "Time" magazine cover stories dedicated to a jazz musician, and

Last years.

Ellington was shortlisted for the Pulitzer Prize for Music in 1965 but no prize was ultimately awarded that year. Then 66 years old, he joked: "Fate is being kind to me. Fate doesn't want me to be famous too young." In 1999 he was posthumously awarded a special Pulitzer Prize "commemorating the centennial year of his birth, in recognition of his musical genius, which evoked aesthetically the principles of democracy through the medium of jazz and thus made an indelible contribution to art and culture."  In September 1965, he premiered the first of his Sacred Concerts. He created a jazz Christian liturgy. Although the work received mixed reviews, Ellington was proud of the composition and performed it dozens of times. This concert was followed by two others of the same type in 1968 and 1973, known as the Second and Third Sacred Concerts. These

Personal life.

Ellington married his high school sweetheart, Edna Thompson (d. 1967), on July 2, 1918, when he was 19. The next spring, on March 11, 1919, Edna gave birth to their only son, Mercer Kennedy Ellington.  Ellington was joined in New York City by his wife and son in the late twenties, but the couple soon permanently separated. According to her obituary in "Jet" magazine, she was "homesick for Washington" and returned. In 1929, Ellington became the companion of Mildred Dixon, who traveled with him, managed Tempo Music, inspired songs

Death.

Ellington died on May 24, 1974, of complications from lung cancer and pneumonia, a few weeks after his 75th birthday. At his funeral, attended by over

Legacy.

Memorials.

Numerous memorials have been dedicated to Duke Ellington, in cities from New York and Washington, D.C. to Los Angeles. Ellington is buried in Woodlawn Cemetery in the Bronx, New York City.  In Ellington's birthplace, Washington, D.C., the Duke Ellington School of the Arts educates talented students, who are considering careers in the arts, by providing intensive arts instruction and strong academic programs that prepare students for post-secondary education and professional careers. Originally built in 1935, the Calvert Street Bridge was renamed the Duke Ellington Bridge in 1974. Another school is P.S. 004 Duke Ellington in New York.  In 1989, a bronze plaque was attached to the newly named Duke Ellington Building at 2121 Ward Place, NW. In 2012, the new owner of the building commissioned a mural by Aniekan Udofia that appears above the lettering "Duke Ellington". In 2010 the triangular park, across the street from Duke Ellington's birth site, at the intersection of New Hampshire and M Streets, NW was named the Duke Ellington Park.  Ellington's residence at 2728 Sherman Avenue, NW, during the

Tributes.

After Duke died, his son Mercer took over leadership of the orchestra, continuing until his own death in 1996. Like the Count Basie Orchestra, this "ghost band" continued to release albums for many years. "Digital Duke", credited to The Duke Ellington Orchestra, won the 1988 Grammy Award for Best Large Jazz Ensemble Album. Mercer Ellington had been handling all administrative aspects of his father's business for several decades. Mercer's children continue a connection with their grandfather's work.  Gunther Schuller wrote in 1989:  Ellington composed incessantly to the very last days of his life. Music was indeed his mistress; it was his total life and his commitment to it was incomparable and unalterable. In jazz he was a giant among giants. And in twentieth century

Loss of material.

On June 25, 2019, "The New York Times Magazine" listed

Awards and honors.

Grammy Awards.

Ellington earned 14 Grammy awards from 1959 to

Grammy Hall of Fame.

Recordings of Duke Ellington were inducted into the Grammy Hall of Fame, which is a

Edward Kennedy "Duke" Ellington (April 29, 1899 – May 24, 1974) was an American composer, pianist, and leader of a jazz orchestra, which he led from 1923 until his death over a career spanning more than six decades.

爱德华·肯尼斯·爱灵顿(英语:Edward Kennedy Ellington,1899年-4月29日-1974年-5月24日),暱称艾灵顿公爵(英语:Duke Ellington),生于美国华盛顿特区,作曲家、钢琴家以及爵士乐队首席领班。公爵(英语:Duke)是童年朋友给他起的绰号,他成名后,人们还是这样称呼他。