Leonid Ilyich Brezhnev was a Soviet politician. The fifth leader of the Soviet Union, he was General Secretary of the Central Committee of the governing Communist Party of the Soviet Union from 1964 until his death in 1982. Ideologically, he was a Marxist-Leninist. Brezhnev was born to a Russian worker's family in Kamenskoye in the Russian Empire. After graduating from the Kamenskoye Metallurgical Technicum, he became a metallurgical engineer in the iron and steel industry. After the October Revolution led to the formation of a one-party state led by the Communist Party, Brezhnev joined the party's youth league, Komsomol, in 1923, became an active party member by 1929. With the onset of World War II, he was drafted into immediate military service and left the army in 1946 with the rank of major general. In 1952 Brezhnev was promoted in 1957 to full member of the Politburo. In 1964, he succeeded Nikita Khrushchev as First Secretary of the CPSU; as the leader of the Soviet Union, Brezhnev's conservatism and carefulness to reach decisions through consensus within the Politburo resulted in sustained political stability within the party and the country.
However, his hostility towards reform and tolerance of corruption ushered in a period of socioeconomic decline that came to be known as the Brezhnev Stagnation. On the world stage, Brezhnev pushed hard for the adoption of détente to relax tensions and foster economic cooperation between the two Cold War superpowers. Despite such diplomatic gestures, his regime presided over widespread military interventionism and a massive arms buildup that grew to comprise 12.5% of the nation's GNP. After years of declining health, Brezhnev died on 10 November 1982 and was succeeded as General Secretary by Yuri Andropov. Upon coming to power in 1985, Mikhail Gorbachev denounced his regime's pervasive inefficiency and inflexibility before overseeing steps to liberalize the Soviet Union. Brezhnev's eighteen-year term as General Secretary was second only to that of Joseph Stalin in duration. During Brezhnev's rule, the global influence of the Soviet Union grew in part because of the expansion of its military during this time.
His tenure as leader was marked by the beginning of an era of economic and social stagnation in the Soviet Union. Brezhnev was born on 19 December 1906 in Kamenskoye, Yekaterinoslav Governorate, Russian Empire, to metalworker Ilya Yakovlevich Brezhnev and his wife, Natalia Denisovna Mazalova, his parents used to live in Brezhnevo before moving to Kamenskoe. Brezhnev's ethnicity was specified as Ukrainian in main documents including his passport, Russian in some others. Like many youths in the years after the Russian Revolution of 1917, he received a technical education, at first in land management and in metallurgy, he graduated from the Kamenskoye Metallurgical Technicum in 1935 and became a metallurgical engineer in the iron and steel industries of eastern Ukraine. Brezhnev joined the Communist Party youth organisation, the Komsomol, in 1923, the Party itself in 1929. In 1935 and 1936, Brezhnev served his compulsory military service, after taking courses at a tank school, he served as a political commissar in a tank factory.
In 1936, he became director of the Dniprodzerzhynsk Metallurgical Technicum. In 1936, he was transferred to the regional center of Dnipropetrovsk, in 1939, he became Party Secretary in Dnipropetrovsk, in charge of the city's important defence industries; as a survivor of Stalin's Great Purge of 1937–39, he was able to advance as the purges created numerous openings in the senior and middle ranks of the Party and state governments. When Nazi Germany invaded the Soviet Union on 22 June 1941, Brezhnev was, like most middle-ranking Party officials drafted, he worked to evacuate Dnipropetrovsk's industries to the east of the Soviet Union before the city fell to the Germans on 26 August, was assigned as a political commissar. In October, Brezhnev was made deputy of political administration for the Southern Front, with the rank of Brigade-Commissar; when Ukraine was occupied by the Germans in 1942, Brezhnev was sent to the Caucasus as deputy head of political administration of the Transcaucasian Front.
In April 1943, he became head of the Political Department of the 18th Army. That year, the 18th Army became part of the 1st Ukrainian Front, as the Red Army regained the initiative and advanced westward through Ukraine; the Front's senior political commissar was Nikita Khrushchev, who had supported Brezhnev's career since the pre-war years. Brezhnev had met Khrushchev in 1931, shortly after joining the Party, before long, as he continued his rise through the ranks, he became Khrushchev's protégé. At the end of the war in Europe, Brezhnev was chief political commissar of the 4th Ukrainian Front, which entered Prague in May 1945, after the German surrender. Brezhnev temporarily left the Soviet Army with the rank of Major General in August 1946, he had spent the entire war as a political commissar rather than a military commander. After working on reconstruction projects in Ukraine, he again became General Secretary in Dnipropetrovsk. In 1950, he became a deputy of the Supreme Soviet of the Soviet Union, the Soviet Union's highest legislative body.
That year he was appointed Party First Secretary in the Moldavian SSR. In 1952, he had a meeting with Stalin after which Stalin promoted Brezhnev to the Communist Party's Central Commit
Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, ductile unreactive, silverish-white transition metal, its name is derived from the Spanish term platino, meaning "little silver". Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements, it has six occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of 5 μg/kg, it occurs in some nickel and copper ores along with some native deposits in South Africa, which accounts for 80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, given its important uses, it is valuable and is a major precious metal commodity. Platinum is one of the least reactive metals, it has remarkable resistance to corrosion at high temperatures, is therefore considered a noble metal. Platinum is found chemically uncombined as native platinum; because it occurs in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.
It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, jewelry. Being a heavy metal, it leads to health problems upon exposure to its salts. Compounds containing platinum, such as cisplatin and carboplatin, are applied in chemotherapy against certain types of cancer; as of 2018, the value of platinum is $833.00 per ounce. Pure platinum is a lustrous and malleable, silver-white metal. Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold; the metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. Platinum does oxidize, forming PtO2, at 500 °C, it reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride.
It is attacked by chlorine, bromine and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia, to form chloroplatinic acid, H2PtCl6, its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewellery; the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, are stabilized by metal bonding in bimetallic species; as is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is unreactive, it dissolves in hot aqua regia to give aqueous chloroplatinic acid: Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2OAs a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide. In 2007, Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum.
Platinum has six occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, 198Pt. The most abundant of these is 195 Pt, it is the only stable isotope with a non-zero spin. 190Pt is the least abundant at only 0.01%. Of the occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 6.5×1011 years, causing an activity of 15 Bq/kg of natural platinum. 198 Pt can undergo alpha decay. Platinum has 31 synthetic isotopes ranging in atomic mass from 166 to 204, making the total number of known isotopes 39; the least stable of these is 166Pt, with a half-life of 300 µs, whereas the most stable is 193Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta alpha decay. 188Pt, 191Pt, 193Pt decay by electron capture. 190Pt and 198Pt are predicted to have energetically favorable double beta decay paths. Platinum is an rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust. It is sometimes mistaken for silver. Platinum is found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly.
Most the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, it is still mined. In nickel and copper deposits, platinum-group metals occur as sulfides, tellurides and arsenides, as end alloys with nickel or copper. Platinum arsenide, sperrylite, is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, about 17,000 kg was mined between 1927 and 1975; the mine ceased operations in 1990. The rare sulfide minera
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
Valery Pavlovich Chkalov was a Soviet and Russian aircraft test pilot and a Hero of the Soviet Union. Chkalov was born in 1904 in the upper Volga region, the town of Vasilyevo, which lies near Nizhny Novgorod, he was the son of a ship boiler-maker at the Vasselyevo Ship Yard on the River Volga. His mother died. Chkalov studied in the technical school in Cherepovets but returned to his home town to work as an apprentice in the shipyard alongside his father, he got a job as a stoker on a river dredger: the Bayan. He saw his first plane in 1919 and decided to join the Red Army's air force, joining first at age 16 as a mechanic, he trained as a pilot at the Yegoryevsk Training School and graduated in 1924 joining a fighter squadron. Chkalov married Olga Orekhova, a schoolteacher from Leningrad, in 1927. In the early 1930s he became a test pilot, his feats included doing 250 loop-the-loops in 45 minutes. From 1935 he led the stunt section of the Russian air force, used in public displays; this included the 1st of May celebrations over Red Square at which point he met Stalin for the first time.
Chkalov achieved several milestones in Aviation. In 1936 and 1937, he participated in several ultra long flights, including a 63-hour flight from Moscow, Soviet Union to Vancouver, United States via the North Pole in a Tupolev ANT-25 airplane, a non-stop distance of 8,811 kilometres; the flight pioneered the polar air route from Europe to the American Pacific Coast. He was planning the world's first non-stop flight around the planet. Chkalov died on 15 December 1938 while piloting a prototype of the Polikarpov I-180 fighter, which crashed during her maiden test flight; the series of events leading up to the crash is not clear. Neither the aircraft's two chief designers, Nikolai Nikolaevich Polikarpov and Dmitri Lyudvigovich Tomashevich, approved the flight, no one had signed a form releasing the prototype from the factory. In any case, Chkalov made a low altitude circuit around the airfield. For the second circuit, Chkalov flew farther away, climbing to over 2,000 m though the flight plan forbade exceeding 600 m.
Chkalov miscalculated his landing approach and came in short of the airfield, but when he attempted to correct his approach the engine cut out. Chkalov struck an overhead powerline, he was thrown from the cockpit, sustaining severe injuries, died two hours later. His ashes are interred in the Kremlin Wall; the official government investigation concluded that the engine cut out because it became too cold in the absence of the cowl flaps. Others thus flooded the engine; as a result of the crash and several other officials, including Arms Industry Department director S. Belyakin, who urged the first flight, were arrested. Years fellow test pilot Mikhail Gromov blamed the designers for flawed engine cooling and Chkalov himself for deviating from the flight plan. Chkalov's son claimed that a plan to assassinate his father had been in the works in the months preceding his death, but the circumstances of the crash make foul play unlikely. Despite the opinion of some, after Chkalov's death Polikarpov's reputation with Stalin was left intact, Polikarpov continued to design aircraft.
The village of Vasilyevo where Chkalov was born is now the town of Chkalovsk. The city of Orenburg bore the name Chkalov from 1938 to 1957. There was a Chkalov Street in Moscow, now renamed Zemlyanoy Val. Nizhny Novgorod has a staircase down to the Volga named after him with a statue of him at the top of it. In 1975, at Vancouver Washington, a monument to Chkalov's 1937 polar flight was dedicated at Pearson Field and a street was named Chkalov Drive. A Chapayev class cruiser was named Chkalov but was renamed Komsomolets in 1958; the metro rail systems of Moscow, Saint Petersburg, Nizhny Novgorod each have a Chkalovskaya station. Yekaterinburg Metro opened one in 2012 as well. Pearson Field site of 1937 landing Pearson Air Museum Chkalovsk, places named after Chkalov Chkalov Island Baĭdukov, G. Over the North Pole. Id. Russian Lindbergh: The Life of Valery Chkalov. Newspaper clippings about Valery Chkalov in the 20th Century Press Archives of the German National Library of Economics
Moscow is the capital and most populous city of Russia, with 13.2 million residents within the city limits, 17 million within the urban area and 20 million within the metropolitan area. Moscow is one of Russia's federal cities. Moscow is the major political, economic and scientific center of Russia and Eastern Europe, as well as the largest city on the European continent. By broader definitions, Moscow is among the world's largest cities, being the 14th largest metro area, the 18th largest agglomeration, the 14th largest urban area, the 11th largest by population within city limits worldwide. According to Forbes 2013, Moscow has been ranked as the ninth most expensive city in the world by Mercer and has one of the world's largest urban economies, being ranked as an alpha global city according to the Globalization and World Cities Research Network, is one of the fastest growing tourist destinations in the world according to the MasterCard Global Destination Cities Index. Moscow is the coldest megacity on Earth.
It is home to the Ostankino Tower, the tallest free standing structure in Europe. By its territorial expansion on July 1, 2012 southwest into the Moscow Oblast, the area of the capital more than doubled, going from 1,091 to 2,511 square kilometers, resulting in Moscow becoming the largest city on the European continent by area. Moscow is situated on the Moskva River in the Central Federal District of European Russia, making it Europe's most populated inland city; the city is well known for its architecture its historic buildings such as Saint Basil's Cathedral with its colorful architectural style. With over 40 percent of its territory covered by greenery, it is one of the greenest capitals and major cities in Europe and the world, having the largest forest in an urban area within its borders—more than any other major city—even before its expansion in 2012; the city has served as the capital of a progression of states, from the medieval Grand Duchy of Moscow and the subsequent Tsardom of Russia to the Russian Empire to the Soviet Union and the contemporary Russian Federation.
Moscow is a seat of power of the Government of Russia, being the site of the Moscow Kremlin, a medieval city-fortress, today the residence for work of the President of Russia. The Moscow Kremlin and Red Square are one of several World Heritage Sites in the city. Both chambers of the Russian parliament sit in the city. Moscow is considered the center of Russian culture, having served as the home of Russian artists and sports figures and because of the presence of museums and political institutions and theatres; the city is served by a transit network, which includes four international airports, nine railway terminals, numerous trams, a monorail system and one of the deepest underground rapid transit systems in the world, the Moscow Metro, the fourth-largest in the world and largest outside Asia in terms of passenger numbers, the busiest in Europe. It is recognized as one of the city's landmarks due to the rich architecture of its 200 stations. Moscow has acquired a number of epithets, most referring to its size and preeminent status within the nation: The Third Rome, the Whitestone One, the First Throne, the Forty Soroks.
Moscow is one of the twelve Hero Cities. The demonym for a Moscow resident is "москвич" for male or "москвичка" for female, rendered in English as Muscovite; the name "Moscow" is abbreviated "MSK". The name of the city is thought to be derived from the name of the Moskva River. There have been proposed several theories of the origin of the name of the river. Finno-Ugric Merya and Muroma people, who were among the several Early Eastern Slavic tribes which inhabited the area, called the river Mustajoki, it has been suggested. The most linguistically well grounded and accepted is from the Proto-Balto-Slavic root *mŭzg-/muzg- from the Proto-Indo-European *meu- "wet", so the name Moskva might signify a river at a wetland or a marsh, its cognates include Russian: музга, muzga "pool, puddle", Lithuanian: mazgoti and Latvian: mazgāt "to wash", Sanskrit: májjati "to drown", Latin: mergō "to dip, immerse". In many Slavic countries Moskov is a surname, most common in Bulgaria, Russia and North Macedonia. There exist as well similar place names in Poland like Mozgawa.
The original Old Russian form of the name is reconstructed as *Москы, *Mosky, hence it was one of a few Slavic ū-stem nouns. As with other nouns of that declension, it had been undergoing a morphological transformation at the early stage of the development of the language, as a result the first written mentions in the 12th century were Московь, Moskovĭ, Москви, Moskvi, Москвe/Москвѣ, Moskve/Moskvě. From the latter forms came the modern Russian name Москва, a result of morphological generalisation with the numerous Slavic ā-stem nouns. However, the form Moskovĭ has left some traces in many other languages, such as English: Moscow, German: Moskau, French: Moscou, Georgian: მოსკოვი, Latvian: Maskava, Ottoman Turkish: Moskov, Tatar: Мәскәү, Mäskäw, Kazakh: Мәскеу, Mäskew, Chuvash: Мускав, etc. In a similar manner the Latin name Moscovia has been formed it became a collo
A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end; the end opposite to the head is called the tail. On installation, the rivet is placed in a punched or drilled hole, the tail is upset, or bucked, so that it expands to about 1.5 times the original shaft diameter, holding the rivet in place. In other words, pounding creates a new "head" on the other end by smashing the "tail" material flatter, resulting in a rivet, a dumbbell shape. To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail; because there is a head on each end of an installed rivet, it can support tension loads. However, it is much more capable of supporting shear loads. Fastenings used in traditional wooden boat building, such as copper nails and clinch bolts, work on the same principle as the rivet but were in use long before the term rivet was introduced and, where they are remembered, are classified among nails and bolts respectively.
There are a number of types of rivets, designed to meet different cost and strength requirements: Solid rivets are one of the oldest and most reliable types of fasteners, having been found in archaeological findings dating back to the Bronze Age. Solid rivets consist of a shaft and head that are deformed with a hammer or rivet gun. A rivet compression or crimping tool can deform this type of rivet; this tool is used on rivets close to the edge of the fastened material, since the tool is limited by the depth of its frame. A rivet compression tool does not require two people, is the most foolproof way to install solid rivets. Solid rivets are used in applications where safety count. A typical application for solid rivets can be found within the structural parts of aircraft. Hundreds of thousands of solid rivets are used to assemble the frame of a modern aircraft; such rivets come with rounded or 100° countersunk heads. Typical materials for aircraft rivets are aluminium alloys and nickel-based alloys.
Some aluminum alloy rivets are too hard to buck and must be softened by solution treating prior to being bucked. "Ice box" aluminum alloy rivets harden with age, must be annealed and kept at sub-freezing temperatures to slow the age-hardening process. Steel rivets can be found in static structures such as bridges and building frames; the setting of these fasteners requires access to both sides of a structure. Solid rivets are driven using a hydraulically, pneumatically, or electromagnetically actuated squeezing tool or a handheld hammer. Applications where only one side is accessible require "blind" rivets. Solid rivets are used by some artisans in the construction of modern reproduction of medieval armour and metal couture; until recently, structural steel connections were either welded or riveted. High-strength bolts have replaced structural steel rivets. Indeed, the latest steel construction specifications published by AISC no longer covers their installation; the reason for the change is due to the expense of skilled workers required to install high strength structural steel rivets.
Whereas two unskilled workers can install and tighten high strength bolts, it takes a minimum of four skilled riveters to install rivets. At a central location near the areas being riveted, a furnace was set up. Rivets were placed in the furnace and heated to glowing hot so that they were more plastic and deformed; the rivet warmer or "cook" used tongs to remove individual rivets and throw them to a catcher stationed near the joints to be riveted. The catcher caught the rivet in wooden bucket with an ash-lined bottom, he placed the rivet into the hole to be riveted quickly turned to catch the next rivet. The "holder up or holder on" would hold a heavy rivet set or dolly or another pneumatic jack against the round head of the rivet, while the riveter applied a hammer or pneumatic rivet hammer to the unformed head, making it mushroom against the joint in its final domed shape. Alternatively the buck is hammered less flush with the structure in a counter sunk hole. Before the use of pneumatic hammers, e.g. in the construction of RMS Titanic, the man who hammered the rivet was known as the "basher".
Upon cooling, the rivet exerted further force, tightening the joint. The last used high strength structural steel rivets were designated ASTM A502 Grade 1 rivets; such riveted structures may be insufficient to resist seismic loading from earthquakes if the structure was not engineered for such forces, a common problem of older steel bridges. This is. In the seismic retrofit of such structures it is common practice to remove critical rivets with an oxygen torch, precision ream the hole insert a machined and heat treated bolt. Semi-tubular rivets are similar to solid rivets; the purpose of this hole is to reduce the amount of force needed for application by rolling the tubular portion outward. The force needed to apply a semitubular rivet is about 1/4 of the amount needed to apply a solid rivet. Tubular rivets are sometimes preferred for pivot points since the swelling of the rivet is only
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, furnace, incinerator or fireplace from human living areas. Chimneys are vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect; the space inside a chimney is called the flue. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships. In the United States, the term'Smokestack industry' refers to the environmental impacts of burning fossil fuels by industrial society including the electric industry during its earliest history; the term smokestack is used when referring to locomotive chimneys or ship chimneys, the term funnel can be used. The height of a chimney influences its ability to transfer flue gases to the external environment via stack effect. Additionally, the dispersion of pollutants at higher altitudes can reduce their impact on the immediate surroundings.
The dispersion of pollutants over a greater area can reduce their concentrations and facilitate compliance with regulatory limits. Romans used tubes inside the walls to draw smoke out of bakeries but chimneys only appeared in large dwellings in northern Europe in the 12th century; the earliest extant example of an English chimney is at the keep of Conisbrough Castle in Yorkshire, which dates from 1185 AD. However, they did not become common in houses until the 17th centuries. Smoke hoods were an early method of collecting the smoke into a chimney. Another step in the development of chimneys was the use of built in ovens which allowed the household to bake at home. Industrial chimneys became common in the late 18th century. Chimneys in ordinary dwellings were first built of plaster or mud. Since chimneys have traditionally been built of brick or stone, both in small and large buildings. Early chimneys were of a simple brick construction. Chimneys were constructed by placing the bricks around tile liners.
To control downdrafts, venting caps with a variety of designs are sometimes placed on the top of chimneys. In the 18th and 19th centuries, the methods used to extract lead from its ore produced large amounts of toxic fumes. In the north of England, long near-horizontal chimneys were built more than 3 km long, which terminated in a short vertical chimney in a remote location where the fumes would cause less harm. Lead and silver deposits formed on the inside of these long chimneys, periodically workers would be sent along the chimneys to scrape off these valuable deposits; as a result of the limited ability to handle transverse loads with brick, chimneys in houses were built in a "stack", with a fireplace on each floor of the house sharing a single chimney with such a stack at the front and back of the house. Today's central heating systems have made chimney placement less critical, the use of non-structural gas vent pipe allows a flue gas conduit to be installed around obstructions and through walls.
In fact, most modern high-efficiency heating appliances do not require a chimney. Such appliances are installed near an external wall, a noncombustible wall thimble allows a vent pipe to run directly through the external wall. On a pitched roof where a chimney penetrates a roof, flashing is used to seal up the joints; the down-slope piece is called an apron, the sides receive step flashing and a cricket is used to divert water around the upper side of the chimney underneath the flashing. Industrial chimneys are referred to as flue gas stacks and are external structures, as opposed to those built into the wall of a building, they are located adjacent to a steam-generating boiler or industrial furnace and the gases are carried to them with ductwork. Today the use of reinforced concrete has entirely replaced brick as a structural component in the construction of industrial chimneys. Refractory bricks are used as a lining if the type of fuel being burned generates flue gases containing acids. Modern industrial chimneys sometimes consist of a concrete windshield with a number of flues on the inside.
The 300 m chimney at Sasol Three consists of a 26 m diameter windshield with four 4.6 metre diameter concrete flues which are lined with refractory bricks built on rings of corbels spaced at 10 metre intervals. The reinforced concrete can be sliding formwork; the height is to ensure the pollutants are dispersed over a wider area to meet legal or other safety requirements. A flue liner is a secondary barrier in a chimney that protects the masonry from the acidic products of combustion, helps prevent flue gas from entering the house, reduces the size of an oversized flue. Since the 1950s, building codes in many locations require newly built chimneys to have a flue liner. Chimneys built without a liner can have a liner added, but the type of liner needs to match the type of appliance it services. Flue liners may be concrete tile, metal, or poured in place concrete. Clay tile flue liners are common in the United States, although it is the only liner that does not meet Underwriters Laboratories 1777 approval and they have problems such as cracked tiles and improper installation.
Clay tiles are about 2 feet long, available in various sizes and shapes, are installed in new construction as the chimney is built. A refractory cement is used between each tile. Metal liners may be stainless steel, aluminum, or galvanized iron and may be flexible or rigid pipes. Stainless stee