1.
Nuclear weapons testing
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Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that developed nuclear weapons tested them, the first nuclear device was detonated as a test by the United States at the Trinity site on July 16,1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of engineer device, codenamed Mike, was tested at the Enewetak atoll in the Marshall Islands on November 1,1952, also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at Novaya Zemlya on October 30,1961, with the largest yield ever seen, the treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, and China continued until 1980, underground tests in the United States continued until 1991, the Soviet Union until 1990, the United Kingdom until 1991, and both China and France until 1996. Non-signatories India and Pakistan last tested nuclear weapons in 1998, North Korea conducted nuclear tests in 2006,2009,2013, and 2016. The most recent confirmed nuclear test occurred in September 2016 in North Korea, Nuclear weapons tests have historically been divided into four categories reflecting the medium or location of the test. Atmospheric testing designates explosions that take place in the atmosphere, Nuclear explosions close enough to the ground to draw dirt and debris into their mushroom cloud can generate large amounts of nuclear fallout due to irradiation of the debris. This definition of atmospheric is used in the Limited Test Ban Treaty, underground testing refers to nuclear tests conducted under the surface of the earth, at varying depths. True underground tests are intended to be contained and emit a negligible amount of fallout. Unfortunately these nuclear tests do occasionally vent to the surface, producing from nearly none to considerable amounts of debris as a consequence. In 1976, the United States and the USSR agreed to limit the maximum yield of underground tests to 150 kt with the Threshold Test Ban Treaty. Underground testing also falls into two categories, tunnel tests in generally horizontal tunnel drifts, and shaft tests in vertically drilled holes. Exoatmospheric testing refers to tests conducted above the atmosphere. The test devices are lifted on rockets, underwater testing results from nuclear devices being detonated underwater, usually moored to a ship or a barge. Tests of this nature have usually been conducted to evaluate the effects of weapons against naval vessels. Another way to nuclear tests are by the number of explosions that constitute the test.1 second. The USSR has exploded up to eight devices in a single salvo test, Pakistans second, almost all lists in the literature are lists of tests, in the lists in Wikipedia, the lists are of explosions
2.
Nevada Test Site
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Nuclear testing at the Nevada Test Site began with a 1-kiloton-of-TNT bomb dropped on Frenchman Flat on 27 January 1951. Many of the images of the nuclear era come from the NTS. During the 1950s, the clouds from the 100 atmospheric tests could be seen for almost 100 mi. The city of Las Vegas experienced noticeable seismic effects, and the distant mushroom clouds, St. George, Utah, received the brunt of the fallout of above-ground nuclear testing in the Yucca Flats/Nevada Test Site. Winds routinely carried the fallout of these tests directly through St. George, the vast majority—828 of the 928 total nuclear tests—were underground. Those arrested included the astronomer Carl Sagan and the actors Kris Kristofferson, Martin Sheen, the Nevada Test Site contains 28 areas,1,100 buildings,400 miles of paved roads,300 miles of unpaved roads, ten heliports, and two airstrips. The Nevada Test Site was established as a 680-square-mile area by President Harry Truman on December 18,1950, within the Nellis Air Force Gunnery, the Nevada Test Site was the primary testing location of American nuclear devices from 1951 to 1992,928 announced nuclear tests occurred there. The site is covered with subsidence craters from the testing, the NTS was the United States primary location for tests in the 500-to-1,000 kt range. 126 tests were conducted elsewhere, including most larger tests, many of these occurred at the Pacific Proving Grounds in the Marshall Islands. During the 1950s, the clouds from atmospheric tests could be seen for almost 100 mi. The city of Las Vegas experienced noticeable seismic effects, and the distant mushroom clouds, the last atmospheric test detonation at the Nevada Test Site was Little Feller I of Operation Sunbeam, on 17 July 1962. Although the United States did not ratify the Comprehensive Test Ban Treaty, it honors the articles of the treaty, subcritical tests not involving a critical mass continue. It created a crater 1,280 feet wide and 320 feet deep that can still be seen today, the site was scheduled to be used to conduct the testing of a 1, 100-ton conventional explosive in an operation known as Divine Strake in June 2006. The bomb is an alternative to nuclear bunker busters. After objections from Nevada and Utahs members of Congress, the operation was postponed until 2007, on 22 February 2007, the Defense Threat Reduction Agency officially canceled the experiment. On December 7,2012 the most-recent explosion was conducted, an underground sub-critical test of the properties of plutonium, NTS also performed piggyback testing of effects of nuclear detonation during the above-ground tests. Vehicles, shelters, utility stations, and other structures were placed at distances from the Ground Zero detonation point of each weapon. Homes and commercial buildings were built to typical of American and European cities
3.
Nuclear weapons delivery
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Nuclear weapons delivery is the technology and systems used to place a nuclear weapon at the position of detonation, on or near its target. Several methods have developed to carry out this task. Strategic nuclear weapons are used primarily as part of a doctrine of deterrence by threatening large targets, weapons meant for use in limited military maneuvers, such as destroying specific military, communications, or infrastructure targets, are known as tactical nuclear weapons. In terms of yields, nowadays the former have much larger yield than the latter. The bombs that destroyed Hiroshima and Nagasaki in 1945 were weaker than many of todays tactical weapons, historically, the first method of delivery, and the method used in the only two nuclear weapons actually used in warfare, was a gravity bomb dropped by a plane. S. Nuclear warheads are represented in bombs, although some are in the form of missiles, gravity bombs are designed to be dropped from planes, which requires that the weapon be able to withstand vibrations and changes in air temperature and pressure during the course of a flight. Early weapons often had a core for safety, known as in flight insertion cores. They had to meet safety conditions, to prevent accidental detonation or dropping, a variety of types also had to have a fuse to initiate detonation. US nuclear weapons that met these criteria are designated by the letter B followed, without a hyphen, the B61, for example, was the primary bomb in the US arsenal for decades. Various air-dropping techniques exist, including bombing, parachute-retarded delivery. The early gravity nuclear bombs could only be carried by the B-29 Superfortress, most ballistic missiles exit the Earths atmosphere and re-enter it in their sub-orbital spaceflight. Placement of nuclear missiles on the low Earth orbit has been banned by the Outer Space Treaty as early as 1967. An ICBM is more than 20 times as fast as a bomber and more than 10 times as fast as a plane, and also flying at a much higher altitude. ICBMs can also be fired quickly in the event of a surprise attack, early ballistic missiles carried a single warhead, often of megaton-range yield. Because of the accuracy of the missiles, this kind of high yield was considered necessary in order to ensure a particular targets destruction. Since the 1970s modern ballistic weapons have seen the development of far more accurate targeting technologies and this set the stage for smaller warheads in the hundreds-of-kilotons-range yield, and consequently for ICBMs having multiple independently targetable reentry vehicles. Advances in technology have enabled a single missile to launch a payload containing several warheads, the number of independent warheads capable of deployment from ballistic missiles depends on the weapons platform the missile is launched from. For example, one D5 Trident missile carried by an Ohio-class submarine is capable of launching eight independent warheads, MIRV has a number of advantages over a missile with a single warhead
4.
Nuclear weapon design
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Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types, in many existing designs, the explosive energy of deployed devices is derived primarily from nuclear fission, not fusion. Pure fission weapons were the first nuclear weapons built and have so far been the type ever used in warfare. Implosion, a mass of either material is surrounded by high explosives that compress the mass. The implosion method can use either uranium or plutonium as fuel, the gun method only uses uranium. Boosted fission weapons improve on the implosion design, the high pressure and temperature environment at the center of an exploding fission weapon compresses and heats a mixture of tritium and deuterium gas. The hydrogen fuses to form helium and free neutrons, boosting can more than double the weapons fission energy release. Staged thermonuclear weapons are essentially a chain of fusion-boosted fission weapons, the secondary stage is imploded by x-ray energy from the first stage, called the primary. This radiation implosion is much more effective than the high-explosive implosion of the primary, consequently, the secondary can be many times more powerful than the primary, without being bigger. The secondary can be designed to maximize fusion energy release, but in most designs fusion is employed only to drive or enhance fission, as it is in the primary. More stages could be added and conceptual designs incorporating up to seven have been produced, pure fusion weapons have not been invented. Such weapons, though, would produce far less radioactive fallout than current designs, pure fission weapons historically have been the first type to be built by a nation state. Most known innovations in nuclear weapon design originated in the United States, although some were developed independently by other states. In early news accounts, pure fission weapons were called atomic bombs or A-bombs, Weapons involving fusion were called hydrogen bombs or H-bombs, also a misnomer since their energy comes mostly from fission. Practitioners favored the terms nuclear and thermonuclear, respectively, the term thermonuclear refers to the high temperatures required to initiate fusion. It omits the equally important factor of radiation pressure, which was considered secret at the time the term became widespread, many nuclear weapon terms similarly obfuscate because of their origin in a classified environment. Nuclear fission separates or splits heavier atoms to form lighter atoms, Nuclear fusion combines together lighter atoms to form heavier atoms. In some ways, fission and fusion are opposite and complementary reactions, to understand how nuclear weapons are designed, it is useful to know the important similarities and differences between fission and fusion
5.
Civil defense
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Civil defense, civil defence or civil protection is an effort to protect the citizens of a state from military attacks and natural disasters. It uses the principles of operations, prevention, mitigation, preparation, response, or emergency evacuation. Programs of this sort were initially discussed at least as early as the 1920s and were implemented in some countries during the 1930s as the threat of war and it became widespread after the threat of nuclear weapons was realized. Since the end of the Cold War, the focus of civil defense has largely shifted from military attack to emergencies, in some countries, civil defense is seen as a key part of total defense. For example, in Sweden, the Swedish word totalförsvar refers to the commitment of a range of resources of the nation to its defense - including to civil protection. Respectively, some countries may have or have had military-organized civil defense units as part of their armed forces or as a paramilitary service, the advent of civil defence was stimulated by the experience of the bombing of civilian areas during the First World War. The bombing of the United Kingdom began on 19 January 1915 when German zeppelins dropped bombs on the Great Yarmouth area, German bombing operations of the First World War were surprisingly effective, especially after the Gotha bombers surpassed the zeppelins. The most devastating raids inflicted 121 casualties for each ton of bombs dropped, the Committee produced figures estimating that in London there would be 9,000 casualties in the first two days and then a continuing rate of 17,500 casualties a week. It was believed there would be total chaos and panic. To control the population harsh measures were proposed, bringing London under almost military control, a different government department proposed setting up camps for refugees for a few days before sending them back to London. A special government department, the Civil Defence Service, was established by the Home Office in 1935 and its remit included the pre-existing ARP as well as wardens, firemen, fire watchers, rescue, first aid post, stretcher party and industry. Over 1.9 million people served within the CD, nearly 2,400 lost their lives to enemy action, the organisation of civil defence was the responsibility of the local authority. Volunteers were ascribed to different units depending on experience or training, each local civil defence service was divided into several sections. Wardens were responsible for reconnaissance and reporting, and leadership, organisation, guidance. Wardens would also advise survivors of the locations of rest and food centres, Rescue Parties were required to assess and then access bombed-out buildings and retrieve injured or dead people. In addition they would turn off gas, electricity and water supplies, medical services, including First Aid Parties, provided on the spot medical assistance. The expected stream of information that would be generated during an attack was handled by Report, a local headquarters would have an ARP controller who would direct rescue, first aid and decontamination teams to the scenes of reported bombing. If local services were deemed insufficient to deal with the incident then the controller could request assistance from surrounding boroughs
6.
Partial Nuclear Test Ban Treaty
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The impetus for the test ban was provided by rising public anxiety over the magnitude of nuclear tests, particularly tests of new thermonuclear weapons, and the resulting nuclear fallout. A test ban was also seen as a means of slowing nuclear proliferation, though the PTBT did not halt proliferation or the arms race, its enactment did coincide with a substantial decline in the concentration of radioactive particles in the atmosphere. The PTBT was signed by the governments of the Soviet Union, United Kingdom, the treaty formally went into effect on 10 October 1963. Since then,123 other states have become party to the treaty, ten states have signed but not ratified the treaty. In 1952–53, the US and Soviet Union detonated their first thermonuclear weapons, in 1954, the US Castle Bravo test at Bikini Atoll had a yield of 15 megatons of TNT, more than doubling the expected yield. In the same year, a Soviet test sent radioactive particles over Japan, around the same time, victims of the atomic bombing of Hiroshima visited the US for medical care, which attracted significant public attention. Between 1951 and 1958, the US conducted 166 atmospheric tests, the Soviet Union conducted 82, in 1945, Britain and Canada made an early call for an international discussion on controlling atomic power. At the time, the US had yet to formulate a policy or strategy on nuclear weapons. Taking advantage of this was Vannevar Bush, who had initiated and administered the Manhattan Project, as a first step in this direction, Bush proposed an international agency dedicated to nuclear control. Truman to help construct US nuclear weapons policy, a version of the Acheson-Lilienthal plan was presented to the United Nations Atomic Energy Commission as the Baruch Plan in June 1946. The Baruch Plan proposed that an International Atomic Development Authority would control all research on and material, the Soviet Union dismissed the Baruch Plan as a US attempt to secure its nuclear dominance, and called for the US to halt weapons production and release technical information on its program. The Acheson–Lilienthal paper and Baruch Plan would serve as the basis for US policy into the 1950s, between 1947 and 1954, the US and Soviet Union discussed their demands within the United Nations Commission for Conventional Disarmament. A series of events in 1954, including the Castle Bravo test and spread of fallout from a Soviet test over Japan, additionally, by 1954, both US and Soviet Union had assembled large nuclear stockpiles, reducing hopes of complete disarmament. Interest in nuclear control and efforts to stall proliferation of weapons to other states grew as the Soviet Unions nuclear capabilities increased, in the same year, the British Labour Party, then led by Clement Attlee, called on the UN to ban testing of thermonuclear weapons. 1955 marks the beginning of negotiations, as Soviet leader Nikita Khrushchev first proposed talks on the subject in February 1955. On 10 May 1955, the Soviet Union proposed a test ban before the UN Disarmament Commissions Committee of Five, the May 1955 proposal is now seen evidence of Khrushchevs new approach to foreign policy, as Khrushchev sought to mend relations with the West. The proposal would serve as the basis of the Soviet negotiating position through 1957, Eisenhower had supported nuclear testing after World War II. In 1947, he rejected arguments by Stafford L. Warrens arguments were lent credence in the scientific community, everybody seems to think that were skunks, saber-rattlers and warmongers
7.
Mushroom cloud
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A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of debris/smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with an explosion. They can be caused by conventional weapons, like vacuum bombs, including the ATBIP. Some volcanic eruptions and impact events can produce natural mushroom clouds, mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The stabilization altitude depends strongly on the profiles of the temperature, dew point, although the term appears to have been coined at the start of the 1950s, mushroom clouds generated by explosions were being described centuries before the atomic era. The Times published a report on 1 October 1937 of a Japanese attack on Shanghai in China which generated a great mushroom of smoke, the 1917 Halifax Explosion also produced one. During World War II, descriptions of mushroom clouds were relatively common, the atomic bomb cloud over Nagasaki, Japan was described in The Times of London of 13 August 1945 as a huge mushroom of smoke and dust. He wrote of the bomb producing a pillar of purple fire, later in 1946, the Operation Crossroads nuclear bomb tests were described as having a cauliflower cloud, but a reporter present also spoke of the mushroom, now the common symbol of the atomic age. Mushrooms have traditionally been associated both with life and death, food and poison, making them a powerful symbolic connection than, say. Mushroom clouds are formed by many sorts of large explosions under earths gravity, without gravity, the explosives by-product gases would remain spherical. Nuclear weapons are usually detonated above the ground, to maximize the effect of their spherically expanding fireball, immediately after the detonation, the fireball begins to rise into the air, acting on the same principle as a hot-air balloon. One way to analyze the motion, once the hot gas has cleared the ground sufficiently, is as a spherical cap bubble, as this gives agreement between the rate of rise and observed diameter. When the detonation altitude is low enough, these afterwinds will draw in dirt, Nuclear detonations produced high above the ground might not create mushroom clouds with a stem. Detonations underwater but near the surface produce a pillar of water, which, in collapsing, forms a cauliflower-like shape, underground detonations at low depth produce a mushroom cloud and a base surge, two different distinct clouds. The amount of radiation vented into the atmosphere decreases rapidly with increasing detonation depth, with surface and near-surface air bursts, the amount of debris lofted into the air decreases rapidly with increasing burst altitude. At burst altitudes of approximately 7 meters/kiloton^0.33, a crater is not formed, the fallout-reducing height, above which the primary radioactive particles consist mainly of the fine fireball condensation, is approximately 55 meters/kiloton^0.4. However, even at these burst altitudes, fallout may be formed by a number of mechanisms, the distribution of radiation in the mushroom cloud varies with yield of the explosion, type of weapon, fusion/fission ratio, burst altitude, terrain type, and weather. In general, lower-yield explosions have about 90% of their radioactivity in the mushroom head, in contrast, megaton-range explosions tend to have most of their radioactivity in the lower third of the mushroom cloud
8.
United States Marine Corps
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The U. S. Marine Corps is one of the four armed service branches in the U. S. Department of Defense and one of the seven uniformed services of the United States. The current Chairman of the Joint Chiefs of Staff, the military officer in the U. S. Armed Forces, is a Marine Corps general, the Marine Corps has been a component of the U. S. Department of the Navy since 30 June 1834, working closely with naval forces for training, transportation, and logistics. The USMC operates posts on land and aboard sea-going amphibious warfare ships around the world, two battalions of Continental Marines were formed on 10 November 1775 in Philadelphia as a service branch of infantry troops capable of fighting for independence both at sea and on shore. The role of the Corps has since grown and evolved, expanding to aerial warfare and earning popular titles such as, Americas third air force, and, second land army. By the mid-20th century, the U. S. Marine Corps had become a major theorist of and its ability to rapidly respond on short notice to expeditionary crises gives it a strong role in the implementation and execution of American foreign policy. As of 2016, the USMC has around 182,000 active duty members and it is the smallest of the U. S. The USMC serves as an expeditionary force-in-readiness and this last clause, while seemingly redundant given the Presidents position as Commander-in-chief, is a codification of the expeditionary responsibilities of the Marine Corps. It derives from similar language in the Congressional acts For the Better Organization of the Marine Corps of 1834, in 1951, the House of Representatives Armed Services Committee called the clause one of the most important statutory – and traditional – functions of the Marine Corps. In addition to its duties, the Marine Corps conducts Visit, Board, Search, and Seizure operations, as well as missions in direct support of the White House. The Marine Band, dubbed the Presidents Own by Thomas Jefferson, Marines from Ceremonial Companies A & B, quartered in Marine Barracks, Washington, D. C. The Executive Flight Detachment also provides transport to Cabinet members. The relationship between the Department of State and the U. S. Marine Corps is nearly as old as the corps itself, for over 200 years, Marines have served at the request of various Secretaries of State. After World War II, an alert, disciplined force was needed to protect American embassies, consulates, in 1947, a proposal was made that the Department of War furnish Marine Corps personnel for Foreign Service guard duty under the provisions of the Foreign Service Act of 1946. A formal Memorandum of Agreement was signed between the Department of State and the Secretary of the Navy on December 15,1948, during the first year of the MSG program,36 detachments were deployed worldwide. Continental Marines manned raiding parties, both at sea and ashore, the Advanced Base Doctrine of the early 20th century codified their combat duties ashore, outlining the use of Marines in the seizure of bases and other duties on land to support naval campaigns. Throughout the late 19th and 20th centuries, Marine detachments served aboard Navy cruisers, battleships, Marine detachments served in their traditional duties as a ships landing force, manning the ships weapons and providing shipboard security. Marines would develop tactics and techniques of amphibious assault on defended coastlines in time for use in World War II, during World War II, Marines continued to serve on capital ships
9.
Uranium-233
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Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in weapons and as a reactor fuel. It has been used successfully in experimental nuclear reactors and has proposed for much wider use as a nuclear fuel. It has a half-life of 160,000 years, uranium-233 is produced by the neutron irradiation of thorium-232. When thorium-232 absorbs a neutron, it becomes thorium-233, which has a half-life of only 22 minutes, thorium-233 decays into protactinium-233 through beta decay. 233U usually fissions on neutron absorption but sometimes retains the neutron, the capture-to-fission ratio is smaller than the other two major fissile fuels uranium-235 and plutonium-239. In 1946 the public first became informed of U-233 bred from thorium as an available source of nuclear energy and atom bombs, following a United Nations report. The United States produced, over the course of the Cold War, approximately 2 metric tons of uranium-233, in varying levels of chemical and these were produced at the Hanford Site and Savannah River Site in reactors that were designed for the production of plutonium-239. Historical production costs, estimated from the costs of production, were 2–4 million USD/kg. There are few remaining in the world with significant capabilities to produce more uranium-233. Uranium-233 has been used as a fuel in several different reactor types, the long-term strategy of the nuclear power program of India, which has substantial thorium reserves, is to move to a nuclear program breeding uranium-233 from thorium feedstock. The fission of one atom of U-233 generates 197.9 MeV =3.171 × 10−11 J, i. e.19.09 TJ/mol =81.95 TJ/kg. The main difference is the co-presence of uranium-232 which can make uranium-233 very dangerous to work on, although not an outright fizzle, METs actual yield of 22 kilotons was sufficiently below the predicted 33 kt that the information gathered was of limited value. The Soviet Union detonated its first hydrogen bomb the year, the RDS-37. In 1998, as part of its Pokhran-II tests, India detonated an experimental U-233 device of low-yield called Shakti V, the B Reactor and others at the Hanford Site optimized for the production of weapons-grade material have been used to manufacture U-233. The hazards are significant even at 5 parts per million, implosion nuclear weapons require U-232 levels below 50 ppm. Gun-type fission weapons additionally need low levels of impurities, to keep the neutron generation low. The Molten-Salt Reactor Experiment used U-233, bred in light water reactors such as Indian Point Energy Center, thorium, from which U-233 is bred, is roughly three to four times more abundant in the earths crust than uranium
10.
Internet Archive
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The Internet Archive is a San Francisco–based nonprofit digital library with the stated mission of universal access to all knowledge. As of October 2016, its collection topped 15 petabytes, in addition to its archiving function, the Archive is an activist organization, advocating for a free and open Internet. Its web archive, the Wayback Machine, contains over 150 billion web captures, the Archive also oversees one of the worlds largest book digitization projects. Founded by Brewster Kahle in May 1996, the Archive is a 501 nonprofit operating in the United States. It has a budget of $10 million, derived from a variety of sources, revenue from its Web crawling services, various partnerships, grants, donations. Its headquarters are in San Francisco, California, where about 30 of its 200 employees work, Most of its staff work in its book-scanning centers. The Archive has data centers in three Californian cities, San Francisco, Redwood City, and Richmond, the Archive is a member of the International Internet Preservation Consortium and was officially designated as a library by the State of California in 2007. Brewster Kahle founded the Archive in 1996 at around the time that he began the for-profit web crawling company Alexa Internet. In October 1996, the Internet Archive had begun to archive and preserve the World Wide Web in large quantities, the archived content wasnt available to the general public until 2001, when it developed the Wayback Machine. In late 1999, the Archive expanded its collections beyond the Web archive, Now the Internet Archive includes texts, audio, moving images, and software. It hosts a number of projects, the NASA Images Archive, the contract crawling service Archive-It. According to its web site, Most societies place importance on preserving artifacts of their culture, without such artifacts, civilization has no memory and no mechanism to learn from its successes and failures. Our culture now produces more and more artifacts in digital form, the Archives mission is to help preserve those artifacts and create an Internet library for researchers, historians, and scholars. In August 2012, the Archive announced that it has added BitTorrent to its file download options for over 1.3 million existing files, on November 6,2013, the Internet Archives headquarters in San Franciscos Richmond District caught fire, destroying equipment and damaging some nearby apartments. The nonprofit Archive sought donations to cover the estimated $600,000 in damage, in November 2016, Kahle announced that the Internet Archive was building the Internet Archive of Canada, a copy of the archive to be based somewhere in the country of Canada. The announcement received widespread coverage due to the implication that the decision to build an archive in a foreign country was because of the upcoming presidency of Donald Trump. Kahle was quoted as saying that on November 9th in America and it was a firm reminder that institutions like ours, built for the long-term, need to design for change. For us, it means keeping our cultural materials safe, private and it means preparing for a Web that may face greater restrictions
11.
Electrical substation
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A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. Substations may be owned and operated by a utility, or may be owned by a large industrial or commercial customer. Generally substations are unattended, relying on SCADA for remote supervision, the word substation comes from the days before the distribution system became a grid. The first substations were connected to one power station, where the generators were housed. Substations may be described by their class, their applications within the power system, the method used to insulate most connections. These categories are not disjointed, for example, to solve a particular problem, a transmission substation connects two or more transmission lines. The simplest case is where all lines have the same voltage. In such cases, substation contains high-voltage switches that allow lines to be connected or isolated for fault clearance or maintenance, Transmission substations can range from simple to complex. A small switching station may be more than a bus plus some circuit breakers. The largest transmission substations can cover an area with multiple voltage levels, many circuit breakers. Modern substations may be implemented using international standards such as IEC Standard 61850, a distribution substation transfers power from the transmission system to the distribution system of an area. The input for a substation is typically at least two transmission or sub-transmission lines. Input voltage may be, for example,115 kV, or whatever is common in the area, the output is a number of feeders. Distribution voltages are typically medium voltage, between 2.4 kV and 33 kV, depending on the size of the area served, the feeders run along streets overhead and power the distribution transformers at or near the customer premises. In addition to transforming voltage, distribution substations also isolate faults in either the transmission or distribution systems, distribution substations are typically the points of voltage regulation, although on long distribution circuits, voltage regulation equipment may also be installed along the line. The downtown areas of large cities feature complicated distribution substations, with high-voltage switching, more typical distribution substations have a switch, one transformer, and minimal facilities on the low-voltage side
12.
Fat Man
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Fat Man was the codename for the atomic bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945. It was the second of the two nuclear weapons ever used in warfare, the first being Little Boy, and its detonation marked the third-ever man-made nuclear explosion in history. It was built by scientists and engineers at Los Alamos Laboratory using plutonium from the Hanford Site, for the Fat Man mission, Bockscar was piloted by Major Charles W. Sweeney. The name Fat Man refers generically to the design of the bomb, because it had a wide. It was also known as the Mark III, Fat Man was an implosion-type nuclear weapon with a solid plutonium core. The first of type to be detonated was the Gadget, in the Trinity nuclear test, less than a month earlier on 16 July at the Alamogordo Bombing. Two more Fat Man bombs were detonated during the Operation Crossroads nuclear tests at Bikini Atoll in 1946, some 120 Fat Man units were produced between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb. The Fat Man was retired in 1950, a gun-type design was chosen, in which two sub-critical masses would be brought together by firing a bullet into a target. Tolman suggested an implosion-type nuclear weapon, but the idea attracted scant consideration, the feasibility of a plutonium bomb was questioned in 1942. Conant consulted Ernest Lawrence and Arthur Compton, who acknowledged that their scientists at Berkeley and Chicago respectively knew about the problem, the committee concluded that any problems could be overcome simply by requiring higher purity. Nonetheless, it was decided that the gun would receive the bulk of the research effort. It was assumed that the uranium gun-type bomb could be adapted from it. The gun-type and implosion-type designs were codenamed Thin Man and Fat Man respectively and these code names were created by Robert Serber, a former student of Oppenheimers who worked on the Manhattan Project. Little Boy would come last, as a variation of Thin Man and he was assisted in this work by Hugh Bradner, Charles Critchfield, and John Streib. L. T. E. Thompson was brought in as a consultant, Thompson was skeptical that an implosion could be made sufficiently symmetric. But Neddermeyers efforts in July and August at imploding tubes to produce cylinders tended to produce objects that resembled rocks, Neddermeyer was the only person who believed that implosion was practical, and only his enthusiasm kept the project alive. Oppenheimer brought John von Neumann to Los Alamos in September 1943 to take a look at implosion. The prospect of more-efficient nuclear weapons impressed Oppenheimer, Teller, and Hans Bethe, kistiakowskys name was immediately suggested, and Kistiakowsky was brought into the project as a consultant in October 1943
