The chairman is the highest officer of an organized group such as a board, a committee, or a deliberative assembly. The person holding the office is elected or appointed by the members of the group, the chairman presides over meetings of the assembled group and conducts its business in an orderly fashion. In some organizations, the chairman position is called president, in others, where a board appoints a president, the two different terms are used for distinctly different positions. Other terms sometimes used for the office and its holder include chair, chairwoman, presiding officer, moderator and convenor; the chairman of a parliamentary chamber is called the speaker. The term chair is sometimes used in lieu of chairman, in response to criticisms that using chairman is sexist, it is used today, has been used as a substitute for chairman since the middle of the 17th century, with its earliest citation in the Oxford English Dictionary dated 1658–1659, only four years after the first citation for chairman.
Major dictionaries state that the word derives from a person. A 1994 Canadian study found the Toronto Star newspaper referring to most presiding men as "chairman", to most presiding women as "chairperson" or as "chairwoman"; the Chronicle of Higher Education uses "chairman" for men and "chairperson" for women. An analysis of the British National Corpus found chairman used 1,142 times, chairperson 130 times and chairwoman 68 times; the National Association of Parliamentarians adopted a resolution in 1975 discouraging the use of “chairperson” and rescinded it in 2017. The Wall Street Journal, The New York Times and United Press International all use "chairwoman" or "chairman" when referring to women, forbid use of "chair" or of "chairperson" except in direct quotations. In World Schools Style debating, male chairs are called "Mr. Chairman" and female chairs are called "Madame Chair"; the FranklinCovey Style Guide for Business and Technical Communication, as well as the American Psychological Association style guide, advocate using "chair" or "chairperson", rather than "chairman".
The Oxford Dictionary of American Usage and Style suggests that the gender-neutral forms are gaining ground. It advocates using "chair" to refer both to women; the Telegraph style guide bans the use of both "Chair" and "Chairperson" on the basis that "Chairman" is correct English. The word chair can refer to the place from which the holder of the office presides, whether on a chair, at a lectern, or elsewhere. During meetings, the person presiding is said to be "in the chair" and is referred to as "the chair". Parliamentary procedure requires that members address the "chair" as "Mr. Chairman" rather than using a name – one of many customs intended to maintain the presiding officer's impartiality and to ensure an objective and impersonal approach. In the United States, the presiding officer of the lower house of a legislative body, such as the House of Representatives, is titled the Speaker, while the upper house, such as the Senate, is chaired by a President. In his 1992 State of the Union address, then-U.
S. President George H. W. Bush used "chairman" for men and "chair" for women. In the British music hall tradition, the Chairman was the master of ceremonies who announced the performances and was responsible for controlling any rowdy elements in the audience; the role was popularised on British TV in the 1960s and 1970s by Leonard Sachs, the Chairman on the variety show The Good Old Days."Chairman" as a quasi-title gained particular resonance when socialist states from 1917 onward shunned more traditional leadership labels and stressed the collective control of soviets by beginning to refer to executive figureheads as "Chairman of the X Committee". Vladimir Lenin, for example functioned as the head of Soviet Russia not as tsar or as president but in roles such as "Chairman of the Council of People's Commissars of the Russian SFSR". Note in particular the popular standard method for referring to Mao Zedong: "Chairman Mao". In addition to the administrative or executive duties in organizations, the chairman has the duties of presiding over meetings.
Such duties at meetings include: Calling the meeting to order Determining if a quorum is present Announcing the items on the order of business or agenda as they come up Recognition of members to have the floor Enforcing the rules of the group Putting questions to a vote Adjourning the meetingWhile presiding, the chairman should remain impartial and not interrupt a speaker if the speaker has the floor and is following the rules of the group. In committees or small boards, the chairman votes along with the other members. However, in assemblies or larger boards, the chairman should vote only when it can affect the result. At a meeting, the chairman only has one vote; the powers of the chairman vary across organizations. In some organizations the chairman has the authority to hire staff and make financial decisions, while in others the chairman only makes recommendations to a board of directors, still others the chairman has no executive powers and is a spokesman for the organization; the amount of power given to the chairman depends on the type of organization, its structure, the rules it has created for itself.
If the chairman exceeds the given authority, engages in misconduct, or fails to perform t
Taiwan the Republic of China, is a state in East Asia. Neighbouring states include the People's Republic of China to the west, Japan to the northeast, the Philippines to the south. Taiwan is the most populous state and largest economy, not a member of the United Nations; the island of Taiwan was inhabited by indigenous peoples for thousands of years before the 17th century, when Dutch colonialists opened the island to mass Han immigration. After a brief rule by the Kingdom of Tungning, the island was annexed in 1683 by the Qing dynasty of China, ceded to Japan in 1895. Following the surrender of Japan in 1945, the Republic of China, which had overthrown and succeeded the Qing in 1911, took control of Taiwan; the resumption of the Chinese Civil War led to the loss of the mainland to the Communists and the flight of the ROC government to Taiwan in 1949. Although the ROC government continued to claim to be the legitimate representative of China, since 1950 its effective jurisdiction has been limited to Taiwan and several small islands.
In the early 1960s, Taiwan entered a period of industrialisation. In the 1980s and early 1990s, it changed from a one-party military dictatorship to a multi-party democracy with a semi-presidential system; as a founding member, the ROC represented China in the UN until it was replaced by the PRC in 1971. The PRC has claimed sovereignty over Taiwan and refused diplomatic relations with any country that recognises the ROC; as of 2019, Taiwan maintains official ties with 16 out of 193 UN member states. Most international organisations in which the PRC participates either refuse to grant membership to Taiwan or allow it to participate only as a non-state actor. Most major powers maintain unofficial ties with Taiwan through representative offices and institutions that function as de facto embassies and consulates. In Taiwan, the major political division is between parties favouring eventual Chinese unification and promoting a Chinese identity contrasted with those aspiring to independence and promoting a Taiwanese identity, though both sides have moderated their positions to broaden their appeal.
Taiwan is a high-income advanced economy, with a skilled and educated workforce. It has the 22nd-largest economy in the world, its high-tech industry plays a key role in the global economy, it is urbanised, is one of the most densely populated countries in the world, with most of the population concentrated on the western coast. The state is ranked in terms of civil and political liberties, health care and human development. Various names for the island of Taiwan remain in use today, each derived from explorers or rulers during a particular historical period; the name Formosa dates from 1542, when Portuguese sailors sighted an uncharted island and noted it on their maps as Ilha Formosa. The name Formosa "replaced all others in European literature" and remained in common use among English speakers into the 20th century. In the early 17th century, the Dutch East India Company established a commercial post at Fort Zeelandia on a coastal sandbar called "Tayouan", after their ethnonym for a nearby Taiwanese aboriginal tribe Taivoan people, written by the Dutch and Portuguese variously as Taiouwang, Teijoan, etc.
This name was adopted into the Chinese vernacular as the name of the sandbar and nearby area. The modern word "Taiwan" is derived from this usage, seen in various forms in Chinese historical records; the area occupied by modern-day Tainan represented the first permanent settlement by both European colonists and Chinese immigrants. The settlement grew to be the island's most important trading centre and served as its capital until 1887. Use of the current Chinese name became official as early as 1684 with the establishment of Taiwan Prefecture. Through its rapid development the entire Formosan mainland became known as "Taiwan". In his Daoyi Zhilüe, Wang Dayuan used "Liuqiu" as a name for the island of Taiwan, or the part of it closest to Penghu. Elsewhere, the name was used for the Ryukyu Islands in general or Okinawa, the largest of them; the name appears in the Book of Sui and other early works, but scholars cannot agree on whether these references are to the Ryukyus, Taiwan or Luzon. The official name of the state is the "Republic of China".
Shortly after the ROC's establishment in 1912, while it was still located on the Chinese mainland, the government used the short form "China" to refer to itself, which derives from zhōng and guó, a term which developed under the Zhou dynasty in reference to its royal demesne, the name was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state during the Qing era. During the 1950s and 1960s, after the government had withdrawn to Taiwan upon losing the Chinese Civil War, it was referred to as "Nationalist China" to differentiate it from "Communist China", it was a member of the United Nations representing "China" until 1971, when it lost its seat to the People's Republic of China. Over subsequent decades, the Republic of China has become known as "Taiwan", after the island that comprises 99% of the territory under its control. In some contexts ROC government publications, the name is written as "
Philadelphia, sometimes known colloquially as Philly, is the largest city in the U. S. state and Commonwealth of Pennsylvania, the sixth-most populous U. S. city, with a 2017 census-estimated population of 1,580,863. Since 1854, the city has been coterminous with Philadelphia County, the most populous county in Pennsylvania and the urban core of the eighth-largest U. S. metropolitan statistical area, with over 6 million residents as of 2017. Philadelphia is the economic and cultural anchor of the greater Delaware Valley, located along the lower Delaware and Schuylkill Rivers, within the Northeast megalopolis; the Delaware Valley's population of 7.2 million ranks it as the eighth-largest combined statistical area in the United States. William Penn, an English Quaker, founded the city in 1682 to serve as capital of the Pennsylvania Colony. Philadelphia played an instrumental role in the American Revolution as a meeting place for the Founding Fathers of the United States, who signed the Declaration of Independence in 1776 at the Second Continental Congress, the Constitution at the Philadelphia Convention of 1787.
Several other key events occurred in Philadelphia during the Revolutionary War including the First Continental Congress, the preservation of the Liberty Bell, the Battle of Germantown, the Siege of Fort Mifflin. Philadelphia was one of the nation's capitals during the revolution, served as temporary U. S. capital while Washington, D. C. was under construction. In the 19th century, Philadelphia became a railroad hub; the city grew from an influx of European immigrants, most of whom came from Ireland and Germany—the three largest reported ancestry groups in the city as of 2015. In the early 20th century, Philadelphia became a prime destination for African Americans during the Great Migration after the Civil War, as well as Puerto Ricans; the city's population doubled from one million to two million people between 1890 and 1950. The Philadelphia area's many universities and colleges make it a top study destination, as the city has evolved into an educational and economic hub. According to the Bureau of Economic Analysis, the Philadelphia area had a gross domestic product of US$445 billion in 2017, the eighth-largest metropolitan economy in the United States.
Philadelphia is the center of economic activity in Pennsylvania and is home to five Fortune 1000 companies. The Philadelphia skyline is expanding, with a market of 81,900 commercial properties in 2016, including several nationally prominent skyscrapers. Philadelphia has more outdoor murals than any other American city. Fairmount Park, when combined with the adjacent Wissahickon Valley Park in the same watershed, is one of the largest contiguous urban park areas in the United States; the city is known for its arts, culture and colonial history, attracting 42 million domestic tourists in 2016 who spent US$6.8 billion, generating an estimated $11 billion in total economic impact in the city and surrounding four counties of Pennsylvania. Philadelphia has emerged as a biotechnology hub. Philadelphia is the birthplace of the United States Marine Corps, is the home of many U. S. firsts, including the first library, medical school, national capital, stock exchange and business school. Philadelphia contains 67 National Historic Landmarks and the World Heritage Site of Independence Hall.
The city became a member of the Organization of World Heritage Cities in 2015, as the first World Heritage City in the United States. Although Philadelphia is undergoing gentrification, the city maintains mitigation strategies to minimize displacement of homeowners in gentrifying neighborhoods. Before Europeans arrived, the Philadelphia area was home to the Lenape Indians in the village of Shackamaxon; the Lenape are a Native American tribe and First Nations band government. They are called Delaware Indians, their historical territory was along the Delaware River watershed, western Long Island, the Lower Hudson Valley. Most Lenape were pushed out of their Delaware homeland during the 18th century by expanding European colonies, exacerbated by losses from intertribal conflicts. Lenape communities were weakened by newly introduced diseases smallpox, violent conflict with Europeans. Iroquois people fought the Lenape. Surviving Lenape moved west into the upper Ohio River basin; the American Revolutionary War and United States' independence pushed them further west.
In the 1860s, the United States government sent most Lenape remaining in the eastern United States to the Indian Territory under the Indian removal policy. In the 21st century, most Lenape reside in Oklahoma, with some communities living in Wisconsin, in their traditional homelands. Europeans came to the Delaware Valley in the early 17th century, with the first settlements founded by the Dutch, who in 1623 built Fort Nassau on the Delaware River opposite the Schuylkill River in what is now Brooklawn, New Jersey; the Dutch considered the entire Delaware River valley to be part of their New Netherland colony. In 1638, Swedish settlers led by renegade Dutch established the colony of New Sweden at Fort Christina and spread out in the valley. In 1644, New Sweden supported the Susquehannocks in their military defeat of the English colony of Maryland. In 1648, the Dutch built Fort Beversreede on the west bank of the Delaware, south of the Schuylkill near the present-day Eastwick neighborhood, to reassert their dominion over the area.
The Swedes responded by building Fort Nya Korsholm, or New Korsholm, named after a town in Finland with a Swedish majority. In 1655, a
Ferrari is an Italian luxury sports car manufacturer based in Maranello. Founded by Enzo Ferrari in 1939 out of Alfa Romeo's race division as Auto Avio Costruzioni, the company built its first car in 1940. However, the company's inception as an auto manufacturer is recognized in 1947, when the first Ferrari-badged car was completed. In 2014, Ferrari was rated the world's most powerful brand by Brand Finance. In June 2018, the 1964 250 GTO became the most expensive car in history, setting an all-time record selling price of $70 million. Fiat S.p. A. acquired 50% of Ferrari in 1969 and expanded its stake to 90% in 1988. In October 2014 Fiat Chrysler Automobiles N. V. announced its intentions to separate Ferrari S.p. A. from FCA. The separation began in October 2015 with a restructuring that established Ferrari N. V. as the new holding company of the Ferrari group and the subsequent sale by FCA of 10% of the shares in an IPO and concurrent listing of common shares on the New York Stock Exchange. Through the remaining steps of the separation, FCA's interest in Ferrari's business was distributed to shareholders of FCA, with 10% continuing to be owned by Piero Ferrari.
The spin-off was completed on 3 January 2016. Throughout its history, the company has been noted for its continued participation in racing in Formula One, where it is the oldest and most successful racing team, holding the most constructors championships and having produced the highest number of drivers' championship wins. Ferrari road cars are seen as a symbol of speed and wealth. Enzo Ferrari was not interested in the idea of producing road cars when he formed Scuderia Ferrari in 1929, with headquarters in Modena. Scuderia Ferrari means "Ferrari Stable" and is used to mean "Team Ferrari." Ferrari bought and fielded Alfa Romeo racing cars for gentleman drivers, functioning as the racing division of Alfa Romeo. In 1933, Alfa Romeo withdrew its in-house racing team and Scuderia Ferrari took over as its works team: the Scuderia received Alfa's Grand Prix cars of the latest specifications and fielded many famous drivers such as Tazio Nuvolari and Achille Varzi. In 1938, Alfa Romeo brought its racing operation again in-house, forming Alfa Corse in Milan and hired Enzo Ferrari as manager of the new racing department.
In September 1939, Ferrari left Alfa Romeo under the provision he would not use the Ferrari name in association with races or racing cars for at least four years. A few days he founded Auto Avio Costruzioni, headquartered in the facilities of the old Scuderia Ferrari; the new company ostensibly produced machine tools and aircraft accessories. In 1940, Ferrari produced a race car – the Tipo 815, based on a Fiat platform, it was the first Ferrari car and debuted at the 1940 Mille Miglia, but due to World War II it saw little competition. In 1943, the Ferrari factory moved to Maranello, where it has remained since; the factory was bombed by the Allies and subsequently rebuilt including a works for road car production. The first Ferrari-badged car was the 1947 125 S, powered by a 1.5 L V12 engine. The Scuderia Ferrari name was resurrected to denote the factory racing cars and distinguish them from those fielded by customer teams. In 1960 the company was restructured as a public corporation under the name SEFAC S.p.
A.. Early in 1969, Fiat took a 50% stake in Ferrari. An immediate result was an increase in available investment funds, work started at once on a factory extension intended to transfer production from Fiat's Turin plant of the Ferrari engined Fiat Dino. New model investment further up in the Ferrari range received a boost. In 1988, Enzo Ferrari oversaw the launch of the Ferrari F40, the last new Ferrari launched before his death that year. In 1989, the company was renamed Ferrari S.p. A. From 2002 to 2004, Ferrari produced the Enzo, their fastest model at the time, introduced and named in honor of the company's founder, Enzo Ferrari, it was to be called the F60, continuing on from the F40 and F50, but Ferrari was so pleased with it, they called it the Enzo instead. It was offered to loyal and recurring customers, each of the 399 made had a price tag of $650,000 apiece. On 15 September 2012, 964 Ferrari cars attended the Ferrari Driving Days event at Silverstone Circuit and paraded round the Silverstone Circuit setting a world record.
Ferrari's former CEO and Chairman, Luca di Montezemolo, resigned from the company after 23 years, succeeded by Amedeo Felisa and on 3 May 2016 Amedeo resigned and was succeeded by Sergio Marchionne, CEO and Chairman of Fiat Chrysler Automobiles, Ferrari's parent company. In July 2018, Marchionne was replaced by board member Louis Camilleri as CEO and by John Elkann as chairman. On 29 October 2014, the FCA group, resulting from the merger between manufacturers Fiat and Chrysler, announced the split of its luxury brand, Ferrari; the aim is to turn Ferrari into an independent brand which 10% of stake will be sold in an IPO in 2015. Ferrari priced its initial public offering at $52 a share after the market close on 20 October 2015. Since the company's beginnings, Ferrari has been involved in motorsport, competing in a range of categories including Formula One and sports car racing through its Scuderia Ferrari sporting division as well as supplying cars and engines to other t
A rolling-element bearing known as a rolling bearing, is a bearing which carries a load by placing rolling elements between two bearing rings called races. The relative motion of the races causes the rolling elements to roll with little rolling resistance and with little sliding. One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large stone block on top; as the stone is pulled, the logs roll along the ground with little sliding friction. As each log comes out the back, it is moved to the front where the block rolls on to it, it is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See "bearings" for more on the historical development of bearings. A rolling element rotary bearing uses a shaft in a much larger hole, cylinders called "rollers" fill the space between the shaft and hole; as the shaft turns, each roller acts as the logs in the above example. However, since the bearing is round, the rollers never fall out from under the load.
Rolling-element bearings have the advantage of a good tradeoff between cost, weight, carrying capacity, accuracy, so on. Other bearing designs are better on one specific attribute, but worse in most other attributes, although fluid bearings can sometimes outperform on carrying capacity, accuracy, rotation rate and sometimes cost. Only plain bearings are used as as rolling-element bearings. There are five types of rolling elements that are used in rolling-element bearings: balls, cylindrical rollers, spherical rollers, tapered rollers, needle rollers. Most rolling-element bearings feature cages; the cages reduce friction and bind by preventing the elements from rubbing against each other. Caged roller bearings were invented by John Harrison in the mid-18th century as part of his work on chronometers. Typical rolling-element bearings range in size from 10 mm diameter to a few metres diameter, have load-carrying capacity from a few tens of grams to many thousands of tonnes. A common kind of rolling-element bearing is the ball bearing.
The bearing has outer races between which balls roll. Each race features a groove shaped so the ball fits loose. Thus, in principle, the ball contacts each race across a narrow area. However, a load on an infinitely small point would cause infinitely high contact pressure. In practice, the ball deforms where it contacts each race much as a tire flattens where it contacts the road; the race yields where each ball presses against it. Thus, the contact between ball and race has finite pressure. Note that the deformed ball and race do not roll smoothly because different parts of the ball are moving at different speeds as it rolls. Thus, there are sliding motions at each ball/race contact. Overall, these cause bearing drag. Roller bearings are the earliest known type of rolling-element-bearing, dating back to at least 40 BC. Common roller bearings use cylinders of greater length than diameter. Roller bearings have higher radial load capacity than ball bearings, but a lower capacity and higher friction under axial loads.
If the inner and outer races are misaligned, the bearing capacity drops compared to either a ball bearing or a spherical roller bearing. As in all radial bearings, the outer load is continuously re-distributed among the rollers. Only less than half of the total number of rollers carries a significant portion of the load at all time; the animation on the right shows how a static radial load is supported by the bearing rollers as the inner ring rotates. Spherical roller bearings have an outer ring with an internal spherical shape; the rollers are thinner at the ends. Spherical roller bearings can thus accommodate both dynamic misalignment. However, spherical rollers are difficult to produce and thus expensive, the bearings have higher friction than an ideal cylindrical or tapered roller bearing since there will be a certain amount of sliding between rolling elements and rings. Gear bearing is roller bearing combining to epicyclical gear; each element of it is represented by concentric alternation of rollers and gearwheels with equality of roller diameter to gearwheel pitch diameter.
The widths of conjugated rollers and gearwheels in pairs are the same. The engagement is herringbone or with the skew end; the downside to this bearing is manufacturing complexity. Gear bearings could be used, for example, as efficient rotary suspension, kinematically simplified planetary gear mechanism in measuring instruments and watches. Tapered roller bearings use conical rollers. Most roller bearings only take radial or axial loads, but tapered roller bearings support both radial and axial loads, can carry higher loads than ball bearings due to greater contact area. Tapered roller bearings are used, as the wheel bearings of most wheeled land vehicles; the downsides to this bearing is that due to manufacturing complexities, tapered roller bearings are more expensive than ball bearings. Needle roller bearings use long and thin cylinders; the ends of the rollers taper to points, these are used to keep the rollers captive, or they may be hemispherical and not captive but held
A linear actuator is an actuator that creates motion in a straight line, in contrast to the circular motion of a conventional electric motor. Linear actuators are used in machine tools and industrial machinery, in computer peripherals such as disk drives and printers, in valves and dampers, in many other places where linear motion is required. Hydraulic or pneumatic cylinders inherently produce linear motion. Many other mechanisms are used to generate linear motion from a rotating motor. Mechanical linear actuators operate by conversion of rotary motion into linear motion. Conversion is made via a few simple types of mechanism: Screw: leadscrew, screw jack, ball screw and roller screw actuators all operate on the principle of the simple machine known as the screw. By rotating the actuator's nut, the screw shaft moves in a line. Wheel and axle: Hoist, winch and pinion, chain drive, belt drive, rigid chain and rigid belt actuators operate on the principle of the wheel and axle. A rotating wheel moves a cable, chain or belt to produce linear motion.
Cam: Cam actuators function on a principle similar to that of the wedge, but provide limited travel. As a wheel-like cam rotates, its eccentric shape provides thrust at the base of a shaft; some mechanical linear actuators only pull, such as chain drive and belt drives. Others only push. Pneumatic and hydraulic cylinders, or lead screws can be designed to generate force in both directions. Mechanical actuators convert rotary motion of a control knob or handle into linear displacement via screws and/or gears to which the knob or handle is attached. A jackscrew or car jack is a familiar mechanical actuator. Another family of actuators are based on the segmented spindle. Rotation of the jack handle. Mechanical actuators are frequently used in the field of lasers and optics to manipulate the position of linear stages, rotary stages, mirror mounts and other positioning instruments. For accurate and repeatable positioning, index marks may be used on control knobs; some actuators include an encoder and digital position readout.
These are similar to the adjustment knobs used on micrometers except their purpose is position adjustment rather than position measurement. Hydraulic actuators or hydraulic cylinders involve a hollow cylinder having a piston inserted in it. An unbalanced pressure applied to the piston generates force. Since liquids are nearly incompressible, a hydraulic cylinder can provide controlled precise linear displacement of the piston; the displacement is only along the axis of the piston. A familiar example of a manually operated hydraulic actuator is a hydraulic car jack. Though, the term "hydraulic actuator" refers to a device controlled by a hydraulic pump. Pneumatic actuators, or pneumatic cylinders, are similar to hydraulic actuators except they use compressed gas to generate force instead of a liquid, they work to a piston in which air is pumped inside a chamber and pushed out of the other side of the chamber. Air actuators are not used for heavy duty machinery and instances where large amounts of weight are present.
One of the reasons pneumatic linear actuators are preferred to other types is the fact that the power source is an air compressor. Because air is the input source, pneumatic actuators are able to be used in many places of mechanical activity; the downside is, most air compressors are large and loud. They are hard to transport to other areas once installed. Pneumatic linear actuators are to leak and this makes them less efficient than mechanical linear actuators; the piezoelectric effect is a property of certain materials in which application of a voltage to the material causes it to expand. High voltages correspond to only tiny expansions; as a result, piezoelectric actuators can achieve fine positioning resolution, but have a short range of motion. In addition, piezoelectric materials exhibit hysteresis which makes it difficult to control their expansion in a repeatable manner. Twisted and coiled polymer actuator known as supercoiled polymer actuator is a coiled polymer that can be actuated by electric power.
A TCP actuator look like a helical spring. TCP actuators are made from silver coated Nylon. TCP actuators can be made from other electrical conductance coat such as gold. TCP actuator should be under a load to keep the muscle extended; the electrical energy transforms to thermal energy due to electrical resistance, which known as Joule heating, Ohmic heating, resistive heating. As the temperature of the TCP actuator increases by Joule heating, the polymer contracts and it causes the actuator contraction. Electro-mechanical actuators are similar to mechanical actuators except that the control knob or handle is replaced with an electric motor. Rotary motion of the motor is converted to linear displacement. There are many designs of modern linear actuators and every company that manufactures them tends to have a proprietary method; the following is a generalized description of a simple electro-mechanical linear actuator. An electric motor is mechanically connected to rotate a lead screw. A lead screw has a continuous helical thread machined on its circumference running along the length.
Threaded onto the lead screw is a lead nut or ball nut with corresponding helical threads. The nut is prevented from rotating with the lead screw. Therefore, when the lead screw is rotated, the nut will be driven along the threads; the direction of motion of the nut d
Schweinfurt is a city in the Lower Franconia region of Bavaria in Germany on the right bank of the navigable Main River, spanned by several bridges here, 44 km northeast of Würzburg. The city was first documented in the year 790, although as early as 740 a settlement called Villa Suinfurde was mentioned. In the 10th century Schweinfurt was the seat of a margraviate. After the defeat of count Henry of Schweinfurt in 1002/1003, in the feud against King Henry II of Germany, his family lost its leading position in the town. In the first half of the 13th century Schweinfurt expanded to become a proper city with city wall and city gates. At that time the Nikolaus hospital was founded, a mint was established and construction work on the Saint Johannis church began. Around 1250 Schweinfurt was destroyed during a feud between the Count of Henneberg and the Prince-Bishop of Würzburg. In the following years it was reconstructed. A document from 1282 signed by Rudolf I of Habsburg states that Schweinfurt was a free city within the Holy Roman Empire.
At least since the coat of arms of Schweinfurt has been an imperial white eagle. In 1309 the city was given to the Count of Henneberg, but in the 1360s the city regained its independence and joined the Swabian–Franconian Confederation. In 1397 King Wenzel entitled the town to utilize the River Main, in 1436–1437 Schweinfurt acquired the village of Oberndorf, as well as the Teutonic Order Fort on the Peterstirn and a small piece of land – including the villages of Zell and Weipoltshausen; some years there was the first uprising of Schweinfurt's citizens against the town council, followed by a second in 1513–1514. This time the issuing of a constitution was allowed; the city joined Martin Luther's Reformation in 1542. Schweinfurt was again destroyed in the course of the Second Margrave War, in 1554; the years up to 1615 were spent by the citizens for its reconstruction. Schweinfurt joined the Protestant Union in 1609. In the Thirty Years' War it was occupied by Gustavus Adolphus, who erected fortifications, the remains of which are still extant.
In 1652 the four doctors Johann Laurentius Bausch, Johann Michael Fehr, Georg Balthasar Wolfahrt and Balthasar Metzger founded the Academia Curiosorum in Schweinfurt, known today as the German Academy of Life Scientists, "Leopoldina". At some point Schweinfurt became a predominantly Roman Catholic city owing to migration from the surrounding Catholic territories, only again to receive a large section of Lutheran refugees/expellees after 1945 from Germany east of the Oder-Neisse line; the latest addition to the Lutheran churches in Schweinfurt arrived during the last years of the Soviet Union. In 1777, Johann Martin Schmidt began to produce white lead. Schweinfurt suffered from heavy casualties during the Napoleonic Wars of 1796–1801. Schweinfurt remained a free imperial city until 1802. Assigned to the grand duke of Würzburg in 1810, it was granted to the Kingdom of Bavaria four years later; the first railway junction was opened in 1852. In the following years Schweinfurt became a world leading centre for the production of ball bearings.
This was to lead to grievous consequences for the city during World War II. In 1939 Schweinfurt produced most of Nazi Germany's ball bearings, factories such as the Schweinfurter Kugellagerwerke became a target of Allied strategic bombing during World War II to cripple tank and aircraft production. Schweinfurt was bombed 22 times during Operation Pointblank by a total of 2,285 aircraft; the Schweinfurt-Regensburg mission caused an immediate 34% loss of production and all plants but the largest were devastated by fire. Efforts to disperse the surviving machinery began and the Luftwaffe deployed large numbers of interceptors along the corridor to Schweinfurt. Bombing included the Second Raid on Schweinfurt on 14 October 1943 and Big Week in February 1944. Although losses of production bearings and machinery were high and much of the industrial and residential areas of the city were destroyed, killing more than a thousand civilians, the factories were restored to production and the industry dispersed.
Although German planners thought it essential to purchase the entire output of the Swedish ball-bearing industry, losses in the production of bearings were made up from surpluses found within Germany in the aftermath of the first raid. The decentralized industry was able to restore output to 85% of its pre-bombing level. Hitler made restoration of ball bearing production a high priority and massive efforts were undertaken to repair and rebuild the factories in bomb-proof underground facilities; the 42nd Infantry Division entered Schweinfurt on 11 April 1945 and engaged in house-to-house fighting. On 12 April an internment camp at Goethe-Schule held male civilians aged 16–60. After the war Schweinfurt became a stronghold of their dependants, thus Schweinfurt recovered quickly from its third period of destruction. Schweinfurt hosted the U. S. Army Garrison Schweinfurt, which the U. S. Army closed on 19 September 2014 due to an ongoing effort to concentrate the U. S. military's footprint in Germany to fewer communities.
In post-war years, the new suburbs of Bergl and Steinberg were developed to settle a growing population. In 1954 the city laid the foundation stone for the new town hall and commemorated the 700th and 500th anniversaries of the two earlier periods of destruction as well as the ongoing reconstruction following World War II. In 1998 German and American veterans and s