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High-voltage direct current

A high-voltage, direct current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may have lower electrical losses. For underwater power cables, HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may still be justified, due to other benefits of direct current links. Most HVDC links use voltages between 100 kV and 800 kV. A 1,100 kV link in China was completed in 2019 over a distance of 3,300 km with a power of 12 GW. With this dimension, intercontinental connections become possible which could help to deal with the fluctuations of wind power and photovoltaics. HVDC allows power transmission between unsynchronized AC transmission systems. Since the power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power.

HVDC allows transfer of power between grid systems running at different frequencies, such as 50 Hz and 60 Hz. This improves the stability and economy of each grid, by allowing exchange of power between incompatible networks; the modern form of HVDC transmission uses technology developed extensively in the 1930s in Sweden and in Germany. Early commercial installations included one in the Soviet Union in 1951 between Moscow and Kashira, a 100 kV, 20 MW system between Gotland and mainland Sweden in 1954; the longest HVDC link in the world is the Rio Madeira link in Brazil, which consists of two bipoles of ±600 kV, 3150 MW each, connecting Porto Velho in the state of Rondônia to the São Paulo area. The length of the DC line is 2,375 km. High voltage is used for electric power transmission to reduce the energy lost in the resistance of the wires. For a given quantity of power transmitted, doubling the voltage will deliver the same power at only half the current. Since the power lost as heat in the wires is directly proportional to the square of the current, doubling the voltage reduces the line losses by a factor of 4.

While power lost in transmission can be reduced by increasing the conductor size, larger conductors are heavier and more expensive. High voltage cannot be used for lighting or motors, so transmission-level voltages must be reduced for end-use equipment. Transformers are used to change the voltage levels in alternating current transmission circuits. Transformers made voltage changes practical, AC generators were more efficient than those using DC; because of this, AC became dominant after the conclusion of the war of the currents in 1892. Practical conversion of power between AC and DC became possible with the development of power electronics devices such as mercury-arc valves and, starting in the 1970s, semiconductor devices as thyristors, integrated gate-commutated thyristors, MOS-controlled thyristors and insulated-gate bipolar transistors; the first long-distance transmission of electric power was demonstrated using direct current in 1882 at Miesbach-Munich Power Transmission, but only 1.5 kW was transmitted.

An early method of HVDC transmission was developed by the Swiss engineer René Thury and his method was put into practice by 1889 in Italy by the Acquedotto De Ferrari-Galliera company. This system used series-connected motor-generator sets to increase the voltage; each set was driven by insulated shafts from a prime mover. The transmission line was operated in a'constant current' mode, with up to 5,000 volts across each machine, some machines having double commutators to reduce the voltage on each commutator; this system transmitted 630 kW at 14 kV DC over a distance of 120 km. The Moutiers–Lyon system transmitted 8,600 kW of hydroelectric power a distance of 200 km, including 10 km of underground cable; this system used eight series-connected generators with dual commutators for a total voltage of 150 kV between the positive and negative poles, operated from c.1906 until 1936. Fifteen Thury systems were in operation by 1913. Other Thury systems operating at up to 100 kV DC worked into the 1930s, but the rotating machinery required high maintenance and had high energy loss.

Various other electromechanical devices were tested during the first half of the 20th century with little commercial success. One technique attempted for conversion of direct current from a high transmission voltage to lower utilization voltage was to charge series-connected batteries reconnect the batteries in parallel to serve distribution loads. While at least two commercial installations were tried around the turn of the 20th century, the technique was not useful owing to the limited capacity of batteries, difficulties in switching between series and parallel connections, the inherent energy inefficiency of a battery charge/discharge cycle. First proposed in 1914, the grid controlled mercury-arc valve became available for power transmission during the period 1920 to 1940. Starting in 1932, General Electric tested mercury-vapor valves and a 12 kV DC transmission line, which served to convert 40 Hz generation to serve 60 Hz loads, at Mechanicville, New York. In 1941, a 60 MW, ±200 kV, 115 km buried cable link was designed for the city of Berlin u

David Davis (bluegrass)

David Davis is an American mandolinist and singer in the bluegrass tradition. He has been cited as a foremost practitioner of Bill Monroe's mandolin technique. Davis was raised In Alabama in a musical family, his grandfather J. H. Bailey played fiddle. In the 1930s, his father Leddell Davis and uncles sang the "brother duets" music style, Davis's uncle Cleo Davis was a member of the first incarnation of Bill Monroe's Blue Grass Boys. Garry Thurmond formed the original Warrior River Boys in 1960; when his health failed in 1984, he turned leadership of the band over to Davis. The band has included former Blue Grass Boy Tom Ewing; the band recorded 150 songs with Wango Records, launched by radio personality Ray Davis. These "Basement Recordings" have appeared on various albums through the years, many on the Time Life label. In 1990, Davis released the album New Beginnings followed in 1993 by Sounds Like Home, both on Rounder Records. Released in 2004, the album David Davis & The Warrior River Boys on Rebel Records features a wide range of rarely-covered songs.

2006 saw the release of Troubled Times. In 2009, Davis released A Nickel on Rebel. Besides Davis on mandolin, the current lineup of the Warrior River Boys includes Phillip James, Stan Wilemon, Marty Hays, Robert Montgomery. Davis was inducted into the Alabama Bluegrass Music Hall of Fame in 2010. In 2014, Davis was inducted into America's Old-Time Country Music Hall Of Fame. 1988: "Passin' Thru" 1990: New Beginnings 1993: Sounds Like Home 200?: America's Music 200?: My Dixie Home 2004: David Davis and the Warrior River Boys 2006: Troubled Times 2009: Two Dimes & A Nickel 2018: Didn't He Ramble: Songs Of Charlie Poole 2016: Retrospective: Live 1984-2014 2000: various artists - Freight Trains Rides Again Volume One 2000: various artists Plum Pitiful Volume Two 2001: various artists - It's Hymn-Time Volume Two's Official website David Davis at AllMusic David Davis discography at Discogs

Solomon Adeniyi Babalola

Rev. Dr. Solomon Adeniyi Babalola is a retired Nigerian Baptist pastor. Born in Oke-Ila, Nigeria, he graduated in December 1949 from the three-year theology course of the Nigerian Baptist Theological Seminary, Ogbomosho, he is reputed to be one of the youngest set of two Nigerian nationals recruited into the ministry by American missionaries, during a 1940s drive led by Seminary President Dr. J. C. Pool, assisted by indigenous pastors. Solomon Adeniyi Babalola was consecrated a trained pastor at the age of 20 years. Rev. Dr. S. Ade Babalola is the son of Emmanuel Babalola Adekeye and Marian Tinuoye Babalola-Adekeye; as the Obaala of Oke-Ila Orangun, Osun State, Nigeria until his death, his father Babalola Adekeye reigned as the Head of the Arefa and he was co-founder of the First Baptist Church of Oke-Ila. The young Adeniyi Babalola started school in Oke-Ila but to complete Primary education to Standard 6, he had to trek the 12 miles to resume each school term in Iresi across hills and bridgeless rivers.

On one of his trips, he had a close call to drowning while crossing through a flooded river, but was rescued by a farmer providentially passing nearby. He was recruited to the seminary from Iresi after his call to ministry. Rev. Dr. S. Ade Babalola was married Dec 16, 1952 to Victoria Titiloye Alao of royal lineage, a daughter of Prince Isaac Adewale Alao of Ara, the founder of her hometown's First Baptist Church. Pastor Babalola and his new wife departed Nigeria by sea one week after their wedding, to commence a missionary assignment in Ghana, for which the young Pastor Babalola had earlier volunteered. Rev. Dr. Babalola and Rev. Mrs. Babalola have five children, sixteen grandchildren and five great-grandchildren; the four oldest grandsons are graduate professionals with information technology/computer science degrees working across the United States. The next four grandchildren are healthcare professionals working across the United States; the other grandchildren are students at lower levels.

On graduation in 1949 with a Certificate in Theology from the Nigerian Baptist Theological Seminary, Pastor Babalola was appointed pastor of the First Baptist Churches of two adjoining Nigerian towns and Ishoko. During his pastorate in these two churches in the Zion Baptist Association, Pastor Babalola met his future wife during activities of the association. Miss Victoria Titiloye Alao was leader of various Women's organizations in her churches - growing up in Ara and teaching in Olla, she was Young Peoples' Leader for the Zion Baptist Association. Babalola pastored the Dunkwa Baptist Church, now the First Baptist Church, Dunkwa-on-Offin. Pastor Babalola was Travelling Pastor across the region. Mrs. Babalola leveraged the wide experience of her youthful activities within the Nigerian Women's Missionary Union to organize similar programs across the assigned missionary territory. On departure from Ghana in 1955, Pastor and Mrs. Babalola's family had increased by their first two sons. On return to Nigeria, Pastor S. Ade Babalola was assigned as Travelling Pastor of the Niger Division which included the Nupe-speaking and Bwari-speaking territories of Nigeria.

He was pastor of the First Baptist Church, while Mrs. Babalola was appointed to serve as Headmistress to revive the long-dormant Baptist Day School. At the end of this assignment, Pastor Babalola was awarded a scholarship to attend Oyo Baptist Boys High School at Olivet Heights where he passed the West African School Certificate Examinations that would enable him to qualify for a bachelor's degree program. While at Olivet Heights, Rev. Dr. Babalola pastored the Baptist Church at Fashola Farm Settlement and Emmanuel Baptist Church, Oyo. on completion of his education at Olivet, he pastored Oke-Ado Baptist Church, Ibadan from January to August 1962 from where he was admitted for the seminary Bachelor's degree program. Babalola returned to the seminary for another three years and earned the Bachelor of Theology in 1965. While with her husband in Ogbomosho, Mrs. Babalola trained at the seminary for the three-year Certificate in Religious Education in 1965 and won the Top Student Award in her combined class of C.

Th. and CRE students.. Rev. Dr. Babalola pastored Laka Baptist Church from 1962 to 1965. Pastor Babalola had his longest pastorate of 17 years at the Oke-Ado Baptist Church, Ibadan - one of the leading churches of the Nigerian Baptist Convention. During this period, Rev. Mrs. V. T. Babalola worked as a Field Worker of the Nigerian Women's Missionary Union and served across the remote towns and villages of the Yoruba states of southwestern Nigeria, she worked in the northwestern Yorubaland and riverine southeastern Yorubaland. Rev. Mrs. Babalola rose to become a Director with the Nigerian Women's Missionary Union. Rev. Mrs. V. T. Babalola elected early retirement in 1987 to travel to the United States to assist her first son's family in the care of her first four grandsons. At the Baptist Association level, Rev. Dr. Babalola served at various times as Financial Secretary Moderator of Ibadan Baptist Association, served as Coordinator & Moderator of Dunkwa Baptist Association and served as Adviser to the Ibadan an

Emergency 4: Global Fighters for Life

Emergency 4: Global Fighters for Life is a simulation video game developed by German studio Sixteen Tons Entertainment allowing users to manage emergency services on a variety of accident and/or accident scenes. The player becomes head of operations in a fictional rescue management organization in command of a number of vehicles and staff from the fire department, medical rescue and technical services; the player has to react to a variety of events against a background of continuous day/night rotation and changing weather conditions. The game includes 20 missions, the ability to manage a team of emergency response professionals, ability to manage a variety of emergency response vehicles, with mandatory free play intermissions at every interim, the Endless and Challenge free play modes. Emergency 4 boasts several improvements in user-friendliness over previous games in the Emergency series. For instance, it is possible to dispatch several vehicles at the same time, order them to arrive at a specific location, there's a simple counter for the number of casualties in the area of operations, idle emergency physicians seek out nearby untended casualties.

A deluxe release includes three extra missions and support for voice commands. Emergency 911 First Responders on IMDb

Lester L. Short

Lester Leroy Short is an American ornithologist. His main research field is the order Piciformes. Short was born in New York. In 1955 he graduated to Bachelor of Science at the Cornell University. After a study of vertebrate zoology at Charles Sibley in the Cornell University he wrote his dissertation with the title Hybridization in the Flickers of North America in 1959. From 1960 to 1962 he was assistant professor at the Adelphi University. From 1963 to 1966 he worked for Wildlife Service. From 1966 until his retirement in 1997 he was Lamont curator of birds at the American Museum of Natural History. In that position he made expeditions to South America, Asia and the Pacific islands. In 1972 Short took part on a survey to study the Okinawa woodpecker. After the results of this expedition were published in the Wilson Bulletin in 1973 the American public became aware of the threats which brought the Okinawa woodpecker to the verge of extinction. A planned project to build United States Marine Corps facilities in the Yambaru forest in the northern Okinawa was stopped to protect the woodpecker.

In 1986 and 1987 Short was among the members of a Cuban-American-Expedition which were able to observe the thought to be extinct Cuban ivory-billed woodpecker for a short while. This was the last reliable sighting of this subspecies. Short is the author of Woodpeckers of the World, a comprehensive account on the order Piciformes, of more than 250 scientific articles including descriptions of the Kaempfer's woodpecker and the pale-eyed blackbird. In 1978 he married the Kenyan ornithologist and bioacoustican Jennifer F. M. Horne who died in 2008. Hybridization in the Flickers of North America, 1959 Aves nuevas o poco comunes Corrientes, Republica Argentina, 1971 Birds of the World, 1975 Woodpeckers of the World, 1982 The Birdwatcher's Book of Lists: Lists for Recreation and Recordkeeping, 1987 Annotated Check-list of the Birds of East Africa, 1990 The Birdwatcher's Book of Lists: Western Region, 1992 The Birdwatcher's Book of Lists: Eastern Region, 1992 The Lives of Birds: Birds of the World and Their Behavior, 1993 Toucans and Honeyguides: Ramphastidae and Indicatoridae, 2001 del Hoyo, J..

Handbook of the Birds of the World. Volume 7: Jacamars to Woodpeckers. Lynx Edicions. ISBN 84-87334-37-7 Biography

Junior Dragster

The Junior Dragster is a scaled-down version of the top fuel dragster. Known as the Jr dragster, it reaches speeds of up to 85 mph; the cars were developed in New Zealand in 1988, with classes developed by the New Zealand Hot Rod Association. The National Hot Rod Association in the USA began sanctioning the class in 1991, with the JDRL; the JDRL is a division of the NHRA, which consists of two different dragster classes, traditional Jr. Dragster having a wheelbase between 90-150 inches and a single-cylinder, five brake horsepower Briggs & Stratton engine, the larger Jr. Comp dragster being 150-190 inches in wheelbase and using a motorcycle or personal watercraft engine. Junior drag racers may choose to participate in programs run by the NHRA, IHRA, or at an unsanctioned facility. Drivers may be male or female and must be at least five years of age to test, six years to compete, be no older than 20 years on December 31 of the competition year; the track is 1/8 of a mile, depending on class, is contested as a bracket race or a heads-up start on a 5-tenths sportsman tree.

Racers E. T is determined by age. Drivers age 5 can only test in single-car passes, can go no faster than 20.00 seconds. Drivers age 6-7 can go no faster than 13.90, can compete in full competition. Drivers age 5-7 must use a crate engine from Stratton with a slide valve to reduce power. Drivers age 8-9 can go no faster than 11.90, 10- to 12-year-olds are limited to 8.90 and 13- to 17-year-olds can go up to 7.90 at 85 mph. Drivers 14-20 can race in Jr. Comp, where racers are limited to 6.900 at 109.99 MPH. Drivers who are 9 as of January 1 can participate in either the 8-9 or 10-12 category once they turn 10 during the year, drivers who are 12 as of January 1 can participate in the 10-12 or 13-17 category once they turn 13 during the year. Drivers who turn 14 may run in Jr. Comp. A driver who turns 18 during the year may stay in Jr. Dragster before jumping to either the adult classes or Jr. Comp. Jr. Dragsters compete in a different racing class called'Outlaw'; this class is run to the 330 ft cone of the racing surface.

The class runs heads-up on a 4-tenths pro tree. This class is a qualified field, so the teams have to give it all they can just to make the field. While different series rules vary, the main principle is the same; the different series restrict engine combinations and weight packages so that the cars do not exceed the 4.10 time NHRA says is the fastest junior dragsters can run to the 330 ft. legally. Racers compete every weekend, running in points series at their home tracks, or in various specialty events with big prizes. During the course of the year, racers could attend various division events, or Nationals. In the NHRA, racers choose between attending the Eastern, the Western Conference Finals. In the UK there are over still growing. Though Bracket racing is still the main factor of Jr. drag racing, varieties of heads up racing are a growing part of this sport. The next step up for Jr. Dragster is Jr. Comp, moving into the full size cars. NHRA Junior Dragster Racing League IHRA Junior Dragsters NHRA Official website IHRA Official website Official NHRA Drag Racing Podcasts Drag Race Central The Latest NHRA News and Analysis First and only young people's novel about junior drag racing