title: Stephen Strasburg

text: Strasburg signed a 7-year, $175 million extension to remain with the Nationals. With the extension, Strasburg became the first National to receive an opt-out clause in his contract, which allows him to elect free agency after the 2019 or 2020 seasons if he desires. On June 26, 2016, he was placed on the 15-day disabled list due to an upper back strain. He returned on July3 against the Cincinnati Reds, where he took a no-hitter through 6.2 innings until being lifted from the game after throwing 109 pitches. The no-hitter was broken up in the 8th inning, but the Nationals still won 12–1. On July 8, Strasburg became the first pitcher since 1912 to start 12–0. His streak of consecutive wins ran to 16, including 13 decisions in the 2016 season, before it was snapped by the Los Angeles Dodgers on July 21. On August 22, Strasburg was again placed on the 15-day disabled list due to right elbow soreness.


title: Stephen Strasburg

text: In a May 27, 2017 game versus the San Diego Padres, Strasburg struck out a career-high 15 batters in a 3−0 win. It was tied for fourth-most in Nationals franchise history.


title: Stephen Strasburg

text: Strasburg set a franchise record on September 10 for consecutive innings pitched without allowing a run with 34 innings, including a nine-inning complete game shutout performance on August 30 in which he hit a home run to break the scoreless tie against Miami Marlins starter Adam Conley. For the 2017 season he was 15–4 with a 2.52 ERA, and led the majors in lowest home runs per nine innings (0.67).


title: Stephen Strasburg

text: On April 21, Strasburg pitched eight scoreless innings against the Miami Marlins to become the career leader in innings pitched by a Washington Nationals player. On July 3, he pitched an immaculate (top of the 4th) inning against Marlins Garrett Cooper, Neil Walker, and Starlin Castrothe fourth immaculate inning in Nationals history. On July 19, he went 3-for-3 with five RBIs, including a 420-foot three-run homerun against the Atlanta Braves.


title: Stephen Strasburg

text: In 2019, Strasburg was 18–6 with a 3.32 ERA. He finished the regular season leading the National League in wins (18), and he finished second in strikeouts (251) behind Jacob deGrom; both were career highs.


title: Stephen Strasburg

text: In the Wild Card Game against the Milwaukee Brewers, Strasburg pitched three scoreless innings in relief of Max Scherzer, earning the win as the Nationals came back to beat the Brewers 4–3. In Game 2 of the 2019 National League Division Series, Strasburg allowed one run and struck out ten batters, earning the win. Strasburg pitched in the deciding Game 5 of the NLDS going six innings and allowing three runs in a no-decision. The Nationals went on to win by a score of 7–3. In Game 6 of the 2019 World Series, Strasburg allowed two runs in the first inning, but pitched into the ninth inning, earning the win. He won the World Series Most Valuable Player Award for his two wins in two appearances (first former #1 draft pick to win the award), including pitching innings while striking out 14 batters and only giving up a total of 12 hits. Strasburg finished the playoffs 5–0 with a 1.98 ERA, 0.94 WHIP, and 47 strikeouts and he and teammate Juan Soto were named co-winners of the Babe Ruth Award as the overall postseason MVPs.


title: Stephen Strasburg

text: After winning the World Series, Strasburg opted out of the remaining four years on his contract and became a free agent for the first time in his career. On December 9, 2019, Strasburg agreed to a seven-year, $245 million contract to return to the Nationals. In the contract, Strasburg has a specific request that Nationals Park stays open every day in the off-season so that he could continue to work out. The $35 million annual average value of the contract was at the time the largest amount received by a pitcher in MLB history.


title: Stephen Strasburg

text: Strasburg began the 2020 shortened season on the injured list (IL); he made his 2020 debut on August 9, 2020. On August 14, Strasburg left the second game he started, after facing only three batters. The following day, Strasburg went back to the IL with a nerve issue in his pitching hand. Strasburg would miss the remainder of the year with the two games being his only appearances on the year.


title: Stephen Strasburg

text: Strasburg made two starts for the Nationals in 2021 before landing on the injured list on April 18 with right shoulder inflammation. Strasburg was activated and made three more starts before returning to the IL on June 2 with a neck strain. On July 27, it was announced that Strasburg would undergo surgery to alleviate neurogenic thoracic outlet syndrome, ending his 2021 season. In his 5 starts, Strasburg posted a 1–2 record and 4.57 ERA with 21 strikeouts in innings of work.


title: Stephen Strasburg

text: Strasburg was activated from the IL on June 9, 2022, and made one start (in which he gave up seven earned runs in innings of work) before returning to the IL five days later with a stress reaction in the ribs. On July 14, Strasburg was transferred to the 60-day IL, where he remained for the rest of the season. Much speculation remains as to whether or not Strasburg will call it a career soon due to the many quick trips back to the IL.


title: Stephen Strasburg

text: Strasburg's repertoire features five pitches: a four-seam fastball, his primary pitch at , which was recorded as high as 100 mph early in his career, and for which in the 2010 season was one of only three starting pitchers to have pitches of over 100 mph, and all did so at least 21 times (Justin Verlander and Ubaldo Jimenez); a two-seam fastball at ; a curveball that Strasburg himself refers to as a slurve at ; a changeup at . and a hybrid pitch he began using regularly in the 2016 season that his catcher Wilson Ramos described as a "slider-cutter," which moves laterally at . Strasburg throws a mix of all his pitches to left-handed hitters, but he mostly eliminates the changeup when facing right-handed hitters. He is liable to throw his four-seamer or slurve to right-handers with two strikes, and adds the changeup in those counts against lefties.


title: Stephen Strasburg

text: His velocity was not significantly affected by his Tommy John surgery in 2010. He had the fastest four-seam fastball among starting pitchers in the 2012 season, averaging . However, he had only one pitch in the seven seasons since Tommy John surgery to top over 100 mph.


title: Stephen Strasburg

text: Strasburg has a high strikeout rate of 11.2 per 9 innings through his first MLB innings. This corresponds with high swing-and-miss rates across all of his pitches, including 54% on his changeup—the highest whiff rate among all starting pitchers' changeups since PITCHf/x began tracking pitches. Through the 2012 season, Strasburg's career strikeout-to-walk ratio of 4.67 would rank second all-time if he had enough innings to qualify. Strasburg maintains that his high strikeout rate is not intentional, and in fact is a hindrance to maintaining low pitch counts.


title: Stephen Strasburg

text: Strasburg's pitching mechanics drew concern early in his career from scouts and coaches. The sequence of Strasburg's delivery was believed to place a great deal of stress on his arm, placing him at greater risk of elbow and shoulder injuries. Indeed, "several pitching coaches quietly predicted Strasburg was at risk" before the rupture of his elbow ligament. Independent scout Paul Reddick compared his mechanics unfavorably with those of pitching legend Greg Maddux, saying Strasburg's motion was inefficient and badly synchronized.


title: Stephen Strasburg

text: During the 2014 season, analysts noted a slight adjustment in Strasburg's pitching mechanics, as he moved his back foot to rest against rather than partially atop the pitching rubber when going into his throwing motion. Strasburg explained that he had been reluctant to make the change but had come to believe it would improve his development. "I didn’t feel comfortable at first. Working at in between starts, it’s just become second nature," he told "The Washington Post". Strasburg said he had noticed an improvement in his balance and timing as a result of the new foot placement.


title: Stephen Strasburg

text: Strasburg was born in San Diego, California, to Jim Strasburg, a real estate developer, and Kathleen Swett Strasburg, a dietician. He grew up a San Diego Padres fan.


title: Stephen Strasburg

text: Strasburg credits his maternal grandmother with helping him develop his baseball skills as a child. She would frequently play catch and even work on pitching with him. He labels her as one of his biggest inspirations.


title: Stephen Strasburg

text: On January 9, 2010, he married Rachel Lackey. They met as students at San Diego State. As of 2019, the couple has two daughters. The Strasburgs relocated full-time to Washington, D.C., in 2018 and live a short drive from Nationals Park, where Stephen regularly works out even during the offseason, according to "The Washington Post".


title: Stephen Strasburg

text: On June 24, 2014, Strasburg stated in an interview that he was going to stop chewing tobacco in the wake of his college coach Tony Gwynn's death, although he admitted to "The Washington Post" two years later that he had not yet completely kicked the habit.


title: Innervisions

text: Innervisions is the sixteenth studio album by American singer, songwriter, and musician Stevie Wonder, released on August 3, 1973, by Tamla, a subsidiary of Motown Records. A landmark recording of Wonder's "classic period", the album has been regarded as his transition from the "" known for romantic ballads into a more musically mature, conscious, and grown-up artist. On the album, Wonder continued to experiment with the ARP synthesizer and the revolutionary T.O.N.T.O. (The Original New Timbral Orchestra) synth developed by Malcolm Cecil and Robert Margouleff, and "Innervisions" became hugely influential on the future sound of commercial soul and black music.


title: Innervisions

text: The album peaked at number four on the "Billboard" Top LPs & Tapes chart and number one on the "Billboard" Soul LPs chart, eventually finishing at number four on the magazine's "Top Pop Albums" chart for 1974. At the 16th Grammy Awards, it won Album of the Year and Best Engineered Non-Classical Recording, while "Living for the City" won Best R&B Song. "Innervisions" is widely considered by fans, critics, and colleagues to be one of Wonder's finest works and one of the greatest albums ever made. It was ranked number 34 on "Rolling Stone"'s list of "The 500 Greatest Albums of All Time", and, in 1999, it was inducted into the Grammy Hall of Fame.


title: Innervisions

text: As with many of Wonder's albums, the lyrics, composition, and production of "Innervisions" are almost entirely his own work, and he also played all, or virtually all, of instruments on many of the album's tracks. He made prominent use of the ARP synthesizer throughout the album, which was popular among musicians of the time because of its ability to construct a complete sound environment.


title: Innervisions

text: The nine tracks of "Innervisions" encompass a wide range of themes and issues: from drug abuse in "Too High", through inequality and systemic racism in "Living for the City", to love in the ballads "All in Love Is Fair" and "Golden Lady". The album's closer, "He's Misstra Know-It-All", is a scathing attack on then-US President Richard Nixon, similar to Wonder's song "You Haven't Done Nothin'" from the following year. "Living for the City" was one of the first soul music songs to deal explicitly with systemic racism and to incorporate everyday sounds of the street, such as traffic, voices, and sirens, in with music recorded in the studio.


title: Innervisions

text: On August 6, 1973, three days after the commercial release of "Innervisions", Wonder played a concert in Greenville, South Carolina. Afterward, he was asleep in the front seat of a car as his friend, John Harris, snaked along a road just outside Durham, North Carolina, behind a truck loaded high with logs. Suddenly, the trucker jammed on his brakes, and the two vehicles collided. Logs went flying, and one smashed through the windshield of Wonder's car and hit him in the forehead. He was bloody and unconscious when he was pulled from the wrecked car and lay in a coma caused by severe brain contusion for ten days.


title: Innervisions

text: When Wonder regained consciousness, he discovered that he had lost his sense of smell (which he later largely recovered), and he was deeply afraid that he might have lost his musical abilities, too. Tucker said:


title: Innervisions

text: Wonder's climb back to health was long and slow. He had to take medication for a year, tired easily, and suffered severe headaches. The crash also changed his way of thinking, as his deep faith and spiritual vision made him doubt that it was "an accident". He stated: "You can never change anything that has already happened. Everything is the way it's supposed to be...Everything that ever happened to me is the way it is supposed to have been." In an interview with "The New York Times", Wonder commented that "the accident opened my ears up to many things around me. Naturally, life is just more important to me now...and what I do with my life." He also said:


title: Innervisions

text: Before the crash, Wonder had been scheduled to do a five-week, 20-city tour in March and April 1974. It was postponed, with the exception of one date in Madison Square Garden in late March. That concert began with Wonder pointing to his scarred forehead, looking up, grinning, and giving "thanks to God that I'm alive." 21,000 people in the crowd roared with applause, and, as a "Post" critic noted, "it was hard not to be thrilled."


title: Innervisions

text: As with both "Music of My Mind" and "Talking Book" from the previous year, "Innervisions" was received warmly by music critics, many of whom praised Wonder's versatile musical skills. "Billboard" wrote that "the liner credits Stevie with playing all the instruments on seven of the nine tunes. So in essence this is a one-man band situation and it works. His skill on drums, piano, bass, and ARP synthesizers are outstanding, and all the tracks work within the thematic framework." "The New York Times" said: "At the center of his music is the sound of what is real. ... Stevie identifies himself as a gang and a genius, producing, composing, arranging, singing and, on several tracks, playing all the accompanying instruments. ... Vocally, he remains inventive and unafraid, he sings all the things he hears: rock, folk and all forms of Black music. The sum total of these varying components is an awesome knowledge, consumed and then shared by an artist who is free enough to do both."


title: Innervisions

text: Many critics praised the variety of musical styles and themes present in the album. A reviewer from "Playboy" wrote: "Stevie Wonder's "Innervisions" is a beautiful fusion of the lyric and the didactic, telling us about the blind world that Stevie inhabits with a depth of musical insight that is awesome. It's a view that's basically optimistic, a constant search for the 'Higher Ground', but the path is full of snares: dope ('Too High'), lies ('Jesus Children of America') and the starkly rendered poison of the city ('Living for the City'). Wonder seems to say that all people delude themselves but have to be well to pay their dues and existentially accept the present. 'Today's not yesterday,/And all things have an ending' is the way he puts it in 'Visions,' the key tune of the album—pretty yet serious, harmonically vivid. There's a lot of varied music here—Latin, reggae, even a nod to Johnny Mathis ('All in Love is Fair')—but it's all Stevie, unmistakably."


title: Innervisions

text: Some reviewers were less enthusiastic. Jon Tiven from "Circus" argued that there was a lack of memorable material on the album: "Just when Stevie had some momentum going, he went and put together a concept album of homogeneous music and rather typical lyrics. Unlike his last two albums, there are no real low spots on this album, which I suppose is an improvement, but there are no songs on "Innervisions" which are truly outstanding either. There's no 'Superstition,' no 'I Believe (When I Fall in Love It Will Be Forever).' By constructing a solid ground from which to work, Stevie has lowered the ceiling, and put a damper on his talents."


title: Innervisions

text: Musicians also showed consummate respect for the achievements of the album, with Roberta Flack saying to "Newsweek" that "It's the most sensitive of our decade ... it has tapped the pulse of the people."


title: Innervisions

text: "Innervisions" won Grammy Awards for Album of the Year and Best Engineered Non-Classical Recording in 1974, while "Living for the City" won the Grammy for Best R&B Song.


title: Innervisions

text: Following "Talking Book", which hit the top 5 of the "Billboard" albums chart in early 1973 and achieved steady sales throughout the rest of the year, "Innervisions" became another considerable hit on the charts for Wonder. It debuted on the "Billboard" albums chart on August 18, 1973, at number 85, then climbed to number 22, number 14, number nine, and number six, before reaching its peak position of number four on September 15. The album remained in the top 20 until the end of the year, and remained in the top 200 during the entire calendar year of 1975. "Innervisions" was Wonder's second consecutive album to reach the top of the "Billboard" Black Albums chart, where it remained for two weeks. On the "Cashbox" chart, it reached number one near the end of 1973. In the UK, the album also found success, and became Wonder's first to reach the UK top 10, peaking at number eight.


title: Innervisions

text: Three hit singles were issued from the album. "Higher Ground", which was released several weeks before "Innervisions", reached number four on the "Billboard" singles chart in late October 1973, and number one on the "Cashbox" singles chart. "Living for the City" reached number eight on the "Billboard" singles chart in early January 1974. These first two singles both reached number one on the "Billboard" Soul Singles chart. Finally, "Don't You Worry 'bout a Thing", released in March 1974, reached number 16 in early June, and also peaked at number two on the Soul Singles chart. In the UK, "Higher Ground" and "Living for the City" were released as singles, but only achieved modest success, reaching numbers 29 and 15, respectively. Only the third single issued there, "He's Misstra Know-It-All", managed to reach the top 10, peaking at number eight on the UK Singles Chart.


title: Innervisions

text: "All in Love Is Fair" was a hit for Barbra Streisand when she recorded it and released it as a single in 1974.


title: Innervisions

text: "Innervisions" is considered by many fans, critics, and colleagues to be one of Stevie Wonder's finest works, and one of the greatest albums ever made. "The Washington Post" critic Geoffrey Himes called it an exemplary release of the progressive soul development from 1968 to 1973. In his "Rock & Roll Review: A Guide to Good Rock" (1991), Bill Shapiro wrote: "This recording represents the pinnacle of a very important artist's career, and of his physically blind, but nonetheless extraordinary humane vision. For all intents and purposes, and for all of its richness and variety of texture, it is essentially "all" Stevie Wonder. He personally created and arranged every sound heard. His canvas stretches from the tough realities of ghetto streets to the transcendent joy of spiritual acceptance, each rendered with an original, unique musical palette. The feel is a little more jazz than funk, the result is simply glorious pop music – uplifting sound and message."


title: Innervisions

text: The album has been included in countless different lists of the greatest albums of all time. It was voted number 143 in the third edition of Colin Larkin's "All Time Top 1000 Albums" (2000). In 2001, VH1 named the album the 31st greatest album of all time, saying: "The whole message of this album seems to be caution – Wonder seems to be warning the black community to be aware of their own plight, strive for improvement, and take matters into their own hands. But this is all against the backdrop of the harsh social realities of America circa 1973, and nowhere does this conflict hit home more than in Wonder's magnum opus, 'Living for the City', a raw piece of modern blues on which Wonder played every instrument. The message of urban struggle resonates even more strongly now than it did thirty years ago, proving that the 'inner-visions' of this LP were visionary as well."


title: Innervisions

text: In 2003, the album was ranked number 23 on "Rolling Stone" magazine's list of the 500 greatest albums of all time; it was number 24 on the 2012 version of the list, and number 34 on the 2020 edition. The magazine wrote on the occasion of the initial list:


title: Innervisions

text: The album was re-released in the UK on September 15, 2008, to coincide with Wonder's critically-acclaimed autumn 2008 European tour.


title: Mentalism

text: Mentalism is a performing art in which its practitioners, known as mentalists, appear to demonstrate highly developed mental or intuitive abilities. Performances may appear to include hypnosis, telepathy, clairvoyance, divination, precognition, psychokinesis, mediumship, mind control, memory feats, deduction, and rapid mathematics. Mentalists perform a theatrical act that includes special effects that may appear to employ psychic or supernatural forces but that are actually achieved by "ordinary conjuring means", natural human abilities (i.e. reading body language, refined intuition, subliminal communication, emotional intelligence), and an in-depth understanding of key principles from human psychology or other behavioral sciences.


title: Mentalism

text: Mentalism is commonly classified as a subcategory of magic and, when performed by a stage magician, may also be referred to as "mental magic". However, many professional mentalists today may generally distinguish themselves from magicians, insisting that their art form leverages a distinct skillset. Instead of doing "magic tricks", mentalists argue that they produce psychological experiences for the mind and imagination, and expand reality with explorations of psychology, suggestion, and influence. Mentalists are also often considered psychic entertainers, although that category also contains non-mentalist performers such as psychic readers and bizarrists.


title: Mentalism

text: Some well-known magicians, such as Penn & Teller, and James Randi, argue that a key differentiation between a mentalist and someone who purports to be an actual psychic is that the former is open about being a skilled artist or entertainer who accomplishes their feats through practice, study, and natural means, while the latter may claim to actually possess genuine supernatural, psychic, or extrasensory powers and, thus, operates unethically.


title: Mentalism

text: Renowned mentalist Joseph Dunninger, who also worked to debunk fraudulent mediums, captured this key sentiment when he explained his impressive abilities in the following way: "Any child of ten could do this – with forty years of experience." Like any performing art, mentalism requires years of dedication, extensive study, practice, and skill to perform well and perfect.


title: Mentalism

text: Much of what modern mentalists perform in their acts can be traced back directly to "tests" of supernatural power that were carried out by mediums, spiritualists, and psychics in the 19th century. However, the history of mentalism goes back even further. Accounts of seers and oracles can be found in the Old Testament of the Bible and in works about ancient Greece. The mentalist act generally cited as one of the earliest on record in the modern era was performed by diplomat and pioneering sleight-of-hand magician Girolamo Scotto in 1572. The performance of mentalism may utilize conjuring principles including sleights, feints, misdirection, and other skills of street or stage magic. Nonetheless, modern mentalists also now increasingly incorporate insights from human psychology and behavioral sciences to produce unexplainable experiences and effects for their audiences.


title: Mentalism

text: Styles of mentalist presentation can vary greatly. In this vein, Penn & Teller explain that "[m]entalism is a genre of magic that exists across a spectrum of morality." In the past, at times, some performers such Alexander and Uri Geller have promoted themselves as genuine psychics. Other famous mentalists, such as Joseph Dunninger and Michael Gutenplan, have claimed that their skills were human, but the result of extensive practice and study. The style of Theodore Annemann has been described as "that of an ordinary person, with extraordinary powers."


title: Mentalism

text: Some contemporary performers, such as Derren Brown, attribute their results and effects to natural skills, including the ability to master magic techniques and showmanship, read body language, and influence audiences with psychological principles, such as suggestion. In this vein, Brown explains that he presents and stages "psychological experiments" through his performances. Mentalist and psychic entertainer Banachek also rejects that he possesses any supernatural or actual psychic powers, having worked with the James Randi Educational Foundation for many years to investigate and debunk fake psychics. Thus, he is also clear with the public that the effects and experiences he creates through his stage performance are the result of his highly developed performance skills and magic techniques, combined with psychological principles and tactics.


title: Mentalism

text: Max Maven often presents his performances as creating interactive mysteries and explorations of the mysterious dimensions of the human mind. He is described as a "mentalist and master magician" as well as a "mystery theorist." In recent years, many other mentalists and allied performers also have begun to promote themselves as "mystery entertainers," as well.


title: Mentalism

text: Others, including Maurice Fogel, Kreskin, Chan Canasta, and David Berglas, may make no specific claims about how effects are achieved and may leave it up to the audience to decide, creating what has been described as "a wonderful sense of ambiguity about whether they possess true psychic ability or not."


title: Mentalism

text: Contemporary mentalists often take their shows onto the streets and perform tricks to a live, unsuspecting audience. They do this by approaching random members of the public and ask to demonstrate so-called supernatural powers. However, some performers such as Derren Brown who often adopt this method of performance tell their audience before the trick starts that everything they see is an illusion and that they are not really "having their mind read." This has been the cause of a lot of controversy in the sphere of magic as some mentalists want their audience to believe that this type of magic is "real" while others think that it is morally wrong to lie to a spectator.


title: Mentalism

text: Professional mentalists generally do not mix "standard" magic tricks with their mental feats. Doing so associates mentalism too closely with the theatrical trickery employed by stage magicians. Many mentalists claim not to be magicians at all, arguing that it is a different art form altogether. The argument is that mentalism invokes belief and imagination that, when presented properly, may allow the audience to interpret a given effect as "real" or may at least provide enough ambiguity that it is unclear whether it is actually possible to somehow achieve. This lack of certainty about the limits of what is real may lead individuals in an audience to reach different conclusions and beliefs about mentalist performers' claims – be they about their various so-called psychic abilities, photographic memory, being a "human calculator", power of suggestion, NLP, or other skills. In this way, mentalism may play on the senses and a spectator's perception or understanding of reality in a different way than conjuring techniques utilized in stage magic.


title: Mentalism

text: Magicians often ask the audience to suspend their disbelief, ignore natural laws, and allow their imagination to play with the various tricks they present. They admit that they are tricksters from the outset, and they know that the audience understands that everything is an illusion. Everyone knows that the magician cannot really achieve the impossible feats shown, such as sawing a person in half and putting them back together without injury, but that level of certainty does not generally exist among the mentalist's audience.


title: Mentalism

text: However, some magicians do still mix mentally-themed performance with magic illusions. For example, a mind-reading stunt might also involve the magical transposition of two different objects. Such hybrid feats of magic are often called "mental magic" by performers. Magicians who routinely mix magic with mental magic include David Copperfield, David Blaine, The Amazing Kreskin, and Dynamo. Notable mentalists who mix magic with mentalism include The Amazing Kreskin, Richard Osterlind, David Berglas, Derren Brown, and Joseph Dunninger.


title: Mentalism

text: Mentalism techniques have, on occasion, been allegedly used outside the entertainment industry to influence the actions of prominent people for personal and/or political gain. Famous examples of accused practitioners include:


title: Mentalism

text: In Albert Einstein's preface to Upton Sinclair's 1930 book on telepathy, "Mental Radio", he supported his friend's endeavor to test the abilities of purported psychics and skeptically suggested: "So if somehow the facts here set forth rest not upon telepathy, but upon some unconscious hypnotic influence from person to person, this also would be of high psychological interest." As such, Einstein here alluded to techniques of modern mentalism.


title: 6lack

text: Ricardo Valdez Valentine Jr. (born June 24, 1992), known professionally as 6lack (stylized as 6LACK, pronounced "black"), is an American singer and rapper.


title: 6lack

text: He initially gained notable recognition following the release of his single, "Prblms", taken from his debut album, "Free 6lack", which was released in November 2016. He released his second album, "East Atlanta Love Letter" in September 2018, which peaked at number three on the "Billboard" 200 chart. Later that year, he released the single "OTW" (with Khalid and Ty Dolla Sign). 6lack was featured on the Normani single "Waves", which earned him a MTV Video Music Award. In June 2020, he released the EP "6pc Hot", which included the single, "Know My Rights" (featuring Lil Baby). Later that year he was featured on the Gorillaz track "The Pink Phantom", with Elton John. In 2021, his single "Calling My Phone" (with Lil Tjay), topped the charts in Canada, and peaked at number three in the US, becoming both artists' highest charting song on both charts.


title: 6lack

text: 6lack is currently signed to Love Renaissance and Interscope Records. He is also a member of the Atlanta-Baltimore music collective Spillage Village, founded by EarthGang and JID. 6lack has received three Grammy Award nominations and has won an MTV Video Music Award.


title: 6lack

text: Ricardo Valdez Valentine Jr. was born on June 24, 1992, in Baltimore, Maryland, and moved to Atlanta, Georgia, with his parents in 1997. He attended Stone Mountain High School and Newton High School. He is the oldest of three siblings. Valentine's first recording experience was when he was 4 years of age, at his father's studio. He began rapping in middle school as a battle rapper and was involved in many battles in his youth including against rapper Young Thug.


title: 6lack

text: 6lack signed a record deal with Flo Rida's International Music Group and Strong Arm Records in July 2011. He left Valdosta State University once he signed, and spent the next few years learning about the industry. 6lack spent five years with the label, putting music out on his SoundCloud account. 6lack had little financial security and spent most of his time sleeping in the studio or outside on the street after moving to Miami, Florida to work on music with the record label. 6lack eventually left his label due to issues over artistic and creative license and management. In 2015, 6lack announced that he had joined the musical collective Spillage Village after living with the members of EarthGang, and appeared on four tracks of Spillage Village EP called "Bears Like This Too" in 2015.


title: 6lack

text: Once he left the label, he signed with Love Renaissance and Interscope Records. In November 2016, "Rolling Stone" included 6lack in their list of "10 New Artists You Need to Know". He then went on to release his debut studio album, "Free 6lack", which peaked at number 34 on the "Billboard" 200 chart. The album's single "Prblms" peaked at number 73 on the "Billboard" Hot 100 chart and became his first platinum record. In April 2017, he joined Canadian singer The Weeknd as opening act for his tour in North America.


title: 6lack

text: In April 2018, he released the single "OTW" with Khalid and Ty Dolla Sign, which has reached at number 57 on the "Billboard" Hot 100. "OTW" became 6lack's highest peaking song on the Hot 100. The first single for his sophomore album, "Switch", was released on June 22, 2018, with a music video released on July 16. "Nonchalant" was released as the album's second single on August 17, with its accompanying music video. On September 14, 2018, 6lack released his second studio album, "East Atlanta Love Letter", featuring guest appearances from Future, J. Cole, Offset, and Khalid. The album's release was preceded by the singles "Switch" and "Nonchalant." In October 2018, 6lack started a tour for the promotion of the album, with opening acts THEY., Tierra Whack, Boogie, Deante' Hitchcock, Summer Walker, and Ari Lennox. 6lack later featured on several other songs, such as "Waves" by Normani. and "Crowded Room" by Selena Gomez, in 2019 and early 2020, respectively.


title: 6lack

text: In May 2020, 6lack released the track "ATL Freestyle". A few weeks later, on June 24, 2020, 6lack celebrated his birthday with the release of the single "Float". He also announced his EP "6pc Hot", which was released on June 26 and included the Lil Baby-assisted single, "Know My Rights". He also launched his own hot sauce brand 600 Degrees Original.


title: 6lack

text: 6lack appeared on two tracks from Spillage Village's "Spilligion" album, released in September 2020. During 2020, he collaborated with British virtual band Gorillaz and singer-songwriter Elton John on the track "The Pink Phantom", for the band's seventh studio album, "".


title: 6lack

text: 6lack's music focuses or is based on personal and business relationships frequently, especially the topic of heartbreak. 6lack has said that his songwriting is influenced mainly by his personal experiences and failed relationships. "Billboard" magazine has described 6lack's music as "moody hip hop" that "spotlights vulnerability and honesty in a way the emoji generation can understand." 6lack has cited Sade, T-Pain, The-Dream, and Usher as his influences.


title: 6lack

text: In February 2017, 6lack announced the birth of his daughter, Syx Rose Valentine. He is currently dating soul singer Bianca Quiñones, known by her stage name Quiñ.


title: History of Liberia

text: Liberia is a country in West Africa founded by free people of color from the United States. The emigration of African Americans, both free and recently emancipated, was funded and organized by the American Colonization Society (ACS). The mortality rate of these settlers was the highest in accurately recorded human history. Of the 4,571 emigrants who arrived in Liberia between 1820 and 1843, only 1,819 survived.


title: History of Liberia

text: In 1846, the first black governor of Liberia, Joseph Jenkins Roberts, requested the Liberian legislature to declare independence, but in a manner that would allow them to maintain contacts with the ACS. The legislature called for a referendum, in which Liberians chose independence. On July 26, 1847, a group of eleven signatories declared Liberia an independent nation. The ACS as well as several northern state governments and local colonization chapters continued to provide money and emigrants as late as the 1870s. The United States government declined to act upon requests from the ACS to make Liberia an American colony or to establish a formal protectorate over Liberia, but it did exercise a "moral protectorate" over Liberia, intervening when threats manifested towards Liberian territorial expansion or sovereignty. Upon Liberian independence, Roberts was elected as the first president of Liberia.


title: History of Liberia

text: Liberia retained its independence throughout the Scramble for Africa by European colonial powers during the late 19th century, while remaining in the American sphere of influence. President William Howard Taft made American support to Liberia a priority of his foreign policy. From the 1920s, the economy focused on exploitation of natural resources. The rubber industry, specifically the Firestone Company, dominated the economy. Until 1980, Liberia was controlled politically by descendants of the original African-American settlers, known collectively as Americo-Liberians, who consisted of a small minority of the population. The violent overthrow of the Americo-Liberian regime that year led to two civil wars that devastated the country, the first from 1989–1997 and the second from 1999–2003.


title: History of Liberia

text: Historians believe that many of the indigenous peoples of Liberia migrated there from the north and east between the 12th and 16th centuries AD. Portuguese explorers established contacts with people of the land later known as "Liberia" as early as 1462. They named the area "Costa da Pimenta" (Pepper Coast), or Grain Coast, because of the abundance of melegueta pepper, which became desired in European cooking.


title: History of Liberia

text: In 1602 the Dutch established a trading post at Grand Cape Mount but destroyed it a year later. In 1663, the English established a few trading posts on the Pepper Coast. No further known settlements by Europeans occurred until the arrival in 1821 of free blacks from the United States.


title: History of Liberia

text: From around 1800, in the United States, people opposed to slavery were planning ways to liberate more slaves and, ultimately, to abolish the institution. At the same time, slaveholders in the South opposed having free Blacks in their states, as they believed the free people threatened the stability of their slave societies. Slaves were gradually freed in the North, although more slowly than generally realized; there were hundreds of slaves in Northern states in the 1840 census, and in New Jersey, in the 1860 census. The former slaves and other free blacks suffered considerable social and legal discrimination; they were not citizens and were seen by many as unwanted foreigners who were taking jobs away from whites by working for less. Like Southern states, some Northern states and territories (Illinois was one, and the Lecompton Constitution proposed this for Kansas) severely restricted or prohibited altogether entry by free Blacks.


title: History of Liberia

text: Some abolitionists, including distinguished blacks such as ship builder Paul Cuffe or Cuffee, believed that blacks should return to "the African homeland", as if it were one ethnicity and country, despite many having been in the United States for generations. Cuffe's dream was that free African Americans and freed slaves "could establish a prosperous colony in Africa," one based on emigration and trade. In 1811, Cuffe founded the Friendly Society of Sierra Leone, a cooperative black group intended to encourage “the Black Settlers of Sierra Leone, and the Natives of Africa generally, in the Cultivation of their Soil, by the Sale of their Produce.” As historian Donald R. Wright put it, "Cuffee hoped to send at least one vessel each year to Sierra Leone, transporting African-American settlers and goods to the colony and returning with marketable African products." However, Cuffe died in 1817, and with him his project.


title: History of Liberia

text: The first ship of the American Colonization Society, the "Elizabeth", departed New York on February 6, 1820, for West Africa carrying 86 settlers. Between 1821 and 1838, the American Colonization Society developed the first settlement, which would be known as Liberia. On July 26, 1847, Liberia declared itself a (free) sovereign nation.


title: History of Liberia

text: As early as the period of the American Revolution, many white members of American society thought that African Americans could not succeed in living in their society as free people. Many considered blacks physically and mentally inferior to whites, and others believed that the racism and societal polarization resulting from slavery were insurmountable obstacles for integration of the races. Thomas Jefferson was among those who proposed colonization in Africa: relocating free blacks outside the new nation.


title: History of Liberia

text: In 1787, Britain had started to resettle the "black poor" of London in the colony of Freetown in Sierra Leone. Many were Black Loyalists, former American slaves who had been freed in exchange for their services during the American Revolutionary War. The Crown also offered resettlement to former slaves whom they had first resettled in Nova Scotia. The Black Loyalists there found both the discrimination by white Nova Scotians and climate hard to bear. (See Black Nova Scotians.) Wealthy African-American shipowner Paul Cuffe thought that colonization was worth supporting. Aided by support from certain members of Congress and British officials, he transported 38 American blacks to Freetown in 1816 at his own expense. He died in 1817, but his private initiative helped arouse public interest in the idea of colonization.


title: History of Liberia

text: The American Colonization Society (ACS) was founded in 1816 by Virginia politician Charles F. Mercer and Presbyterian minister Robert Finley of New Jersey. The goal of the ACS was to settle free blacks outside of the United States; its method was to help them relocate to Africa.


title: History of Liberia

text: Starting in January 1820, the ACS sent ships from New York to West Africa. The first had 88 free black emigrants and three white ACS agents on board. The agents were to find an appropriate area for a settlement. Additional ACS representatives arrived in the . In December 1821, they acquired Cape Mesurado, a strip of land near present-day Monrovia, from the indigenous ruler King Peter (perhaps with some threat of force).


title: History of Liberia

text: From the beginning, the colonists were attacked by indigenous peoples whose territory this was, such as the Malinké tribes. In addition, they suffered from disease, the harsh climate, lack of food and medicine, and poor housing conditions.


title: History of Liberia

text: Until 1835, five more colonies were created by the colonization societies of five different states in the U.S. (Republic of Maryland, Kentucky-in-Africa, Mississippi in Africa, Louisiana, Liberia, and that set up by the Pennsylvania state colonization society and one planned by the New Jersey colonization society), and one by the U.S. government in the vicinity of the ACS settlement. The first colony on Cape Mesurado was extended along the coast as well as inland, sometimes by use of force against the native tribes. In 1838 these settlements came together to create the Commonwealth of Liberia. Monrovia was named the capital. By 1842, four of the other American settlements were incorporated into Liberia, and the fifth was destroyed by indigenous people. The colonists of African-American descent became known as Americo-Liberians. Many were of mixed race, including European ancestry. They remained African Americans in their education, religion, and culture, and they treated the natives as White Americans had treated them: as savages from the jungle, unwanted as citizens and not deserving the vote.


title: History of Liberia

text: Free people of color in the United States, with a few notable exceptions, overwhelmingly rejected the idea of moving to Liberia, or anywhere else in Africa, from the very beginning of the movement. Most of them had lived in the United States for generations, and while they wanted better treatment, they did not want to leave. In response to the proposal for blacks to move to Africa, Frederick Douglass said "Shame upon the guilty wretches that dare propose, and all that countenance such a proposition. We live here—have lived here—have a right to live here, and mean to live here."


title: History of Liberia

text: Starting in 1831 with William Lloyd Garrison's new newspaper, "The Liberator", and followed by his "Thoughts on African Colonization" in 1832, support for colonization dropped, particularly in Northern free states. Garrison and his followers supported the idea of "immediatism," calling for immediate emancipation of all slaves and the legal prohibition of slavery throughout the United States. The ACS, Garrison declared, was "a creature without heart, without brains, eyeless, unnatural, hypocritical, relentless and unjust." It was not, in his view, a plan to eliminate slavery; rather, it was a way to protect it.


title: History of Liberia

text: The ACS was made up of a combination of abolitionists who wanted to end slavery—it was easier to get slaves freed if they agreed to go to Liberia—and slaveholders who wanted to get rid of free people of color. Henry Clay, one of the founders of the group, had inherited slaves as a young child, but adopted antislavery views in the 1790s under the influence of his mentor, George Wythe. Garrison pointed out that the number of free people of color who actually resettled in Liberia was minute in comparison to the number of slaves in the United States. As put by one of his supporters: "As a remedy for slavery, it must be placed amongst the grossest of all delusions. In fifteen years it has transported less than three thousand persons to the African coast; while the "increase" on their numbers, in the same period, is about seven hundred thousand!"


title: History of Liberia

text: Emigrants to Liberia suffered the highest mortality rate of any country since modern record-keeping began. Of the 4,571 emigrants who arrived in Liberia from 1820 to 1842, only 1,819 survived until 1843. The ACS knew of the high death rate, but continued to send more people to the colony. Professor Shick writes:


title: History of Liberia

text: The ACS administrators gradually gave the maturing colony more self-governance. In 1839, it was reorganized into the Commonwealth of Liberia. In 1841, the Commonwealth's first non-white governor, Joseph Jenkins Roberts, was appointed by ACS's governing board. In early 1847, the ACS directed Liberian leadership to declare independence. On July 26, 1847, eleven signatories to the Liberian Declaration of Independence established the free and independent Republic of Liberia. It took several years for other nations to recognize Liberia's independence, most notably Britain in 1848 and France in 1852. In the United States, the Southern bloc in Congress refused to recognize Liberian sovereignty. In 1862, however, following the departure of most Southern congressmen due to the American Civil War and the secession of the Southern states, the United States finally established diplomatic relations and welcomed a Liberian delegation to Washington.


title: History of Liberia

text: Between 1847 and 1980, the state of Liberia was dominated by the small minority of African-American colonists and their descendants, known collectively as Americo-Liberians. The Americo-Liberian minority, many of whom were mixed-race African Americans, viewed the native majority as "racially" inferior to themselves and treated them much the same as white Americans had treated them. To avoid "racial" contamination, the Americo-Liberians practiced endogamous marriage. For over a century the indigenous population of the country was denied the right to vote or participate significantly in the running of the country. The Americo-Liberians consolidated power amongst themselves. They, but not the natives, received financial support from supporters in the United States. They established plantations and businesses, and were generally richer than the indigenous people of Liberia, exercising overwhelming political power.


title: History of Liberia

text: Politically, Liberia was dominated by two political parties. The Americo-Liberians had limited the franchise to prevent indigenous Liberians from voting in elections. The Liberian Party (later the Republican Party), was supported primarily by mixed-race African Americans from poorer backgrounds, while the True Whig Party received much of its following from richer blacks. From the first presidential election in 1847, the Liberian Party held political dominance. It used its position of power to attempt to cripple its opposition.


title: History of Liberia

text: In 1869, however, the Whigs won the presidential election under Edward James Roye. Although Roye was deposed after two years and the Republicans returned to government, the Whigs regained power in 1878 and maintained power constantly thereafter for over a century.


title: History of Liberia

text: A series of rebellions among the indigenous Liberian population took place between the 1850s and 1920s. In 1854, a newly independent African-American state in the region, the Republic of Maryland, was forced by an insurgency of the Grebo and the Kru people to join Liberia. Liberia's expansion brought the colony into border disputes with the French and British in French Guinea and Sierra Leone, respectively. The presence and protection of the U.S. Navy in West Africa until 1916 ensured that Liberia's territorial acquisitions or independence were never under threat.


title: History of Liberia

text: The social order in Liberia was dominated by Americo-Liberians. Although descended primarily from peoples of African origin, often with some white DNA from an owner impregnating an enslaved female (see Children of the plantation), the ancestors of most Americo-Liberians had been born in the United States for generations before emigrating to Africa. As a result, they held American cultural, religious, and social values. Like many Americans of the period, the Americo-Liberians held a firm belief in the religious superiority of Christianity, and indigenous animism and culture became systematically oppressed.


title: History of Liberia

text: The Americo-Liberians created communities and a society that reflected closely the American society they had known. They spoke English, and built churches and houses in styles resembling those found in the Southern United States. The Americo-Liberians controlled the native peoples' access to the ocean, modern technology and skills, literacy, higher levels of education, and valuable relationships with many of the United States' institutions—including the American government.


title: History of Liberia

text: Reflecting the system of segregation in the United States, the Americo-Liberians created a cultural and racial caste system, with themselves at the top and indigenous Liberians at the bottom. They believed in a form of "racial equality," which meant that all residents of Liberia had the potential to become "civilized" through western-style education and conversion to Christianity.


title: History of Liberia

text: During World War II, thousands of indigenous Liberians migrated from the nation's rural interior to the coastal regions in search of jobs. The Liberian Government had long opposed this kind of migration, but was no longer able to restrain it. In the decades after 1945, the Liberian government received hundreds of millions of dollars of unrestricted foreign investment, which destabilized the Liberian economy. Government revenue rose enormously, but was being grossly embezzled by government officials. Growing economic disparities caused increased hostility between indigenous groups and Americo-Liberians.


title: History of Liberia

text: The social tensions led President Tubman to enfranchise the indigenous Liberians either in 1951 or 1963 (accounts differ). Tubman and his Whig Party continued to repress political opposition and rig elections.


title: History of Liberia

text: The suppression of the transatlantic slave trade in West Africa by the American and British navies after 1808 also produced new settlers, as these two navies would settle liberated slaves in Liberia or Sierra Leone. In the later 19th century, Liberia had to economically compete with European colonies in Africa. The economy of Liberia was always based on the production of agricultural produce for export. In particular, Liberia's important coffee industry was destroyed in the 1870s by the emergence of production in Brazil.


title: History of Liberia

text: New technology that became available in Europe increasingly drove Liberian shipping companies out of business. Although Roye's government attempted to procure funding for a railway in 1871, the plan never materialized. The first railway in Liberia was not constructed until 1945. From the late 19th century, European powers, such as the United Kingdom and Germany, invested in infrastructure in their African colonies, making them more competitive in terms of getting products to market, improving communications, etc.


title: History of Liberia

text: The national currency, the Liberian dollar, collapsed in 1907. The country was later forced to adopt the United States Dollar. The Liberian government was constantly dependent on foreign loans at high rates of exchange, which endangered the country's independence.


title: History of Liberia

text: In 1926, Firestone, an American rubber company, started the world's largest rubber plantation in Liberia. This industry created 25,000 jobs, and rubber quickly became the backbone of the Liberian economy; in the 1950s, rubber accounted for 40% of the national budget. During the 1930s, Liberia signed concession agreements with Dutch, Danish, German, and Polish investors in what has been described as an "open door" economic policy.


title: History of Liberia

text: Between 1946 and 1960, exports of natural resources such as iron, timber and rubber rose significantly. In 1971, Liberia had the world's largest rubber industry, and was the third largest exporter of iron ore. Since 1948, ship registration was another important source of state revenue.


title: History of Liberia

text: From 1962 until 1980, the U.S. donated $280 million in aid to Liberia, in exchange for which Liberia offered its land rent-free for American government facilities. Throughout the 1970s, the price of rubber in the world commodities market was depressed, which put pressure on Liberian state finances.


title: History of Liberia

text: After 1927, the League of Nations investigated accusations that the Liberian government had forcibly recruited and sold indigenous people as contract laborers or slaves. In its 1930 report, the league admonished the Liberian government for "systematically and for years fostering and encouraging a policy of gross intimidation and suppression" by "[suppressing] the native, prevent him from realizing his powers and limitations and prevent him from asserting himself in any way whatever, for the benefit of the dominant and colonizing race, although originally the same African stock as themselves." President Charles D. B. King hastily resigned.


title: History of Liberia

text: The United States had a long history of intervening in Liberia's internal affairs, and had repeatedly sent naval vessels to help suppress insurrections by indigenous tribes before and after independence (in 1821, 1843, 1876, 1910, and 1915). However, the United States had lost interest in Liberia after 1876 (the end of Reconstruction), and the country instead became closely tied to British capital. Starting in 1909, the U.S. once again became heavily involved in Liberia. By 1909, Liberia faced serious external threats to its sovereignty over unpaid foreign loans and border disputes.


title: History of Liberia

text: In 1912, the U.S. arranged a 40-year international loan of $1.7 million, against which Liberia had to agree to four Western powers (United States, Britain, France, and Germany) controlling Liberian Government revenues until 1926. The American administration of the border police stabilized the frontier with Sierra Leone (then part of the British Empire), and checked French ambitions to annex more Liberian territory. The United States Navy established a coaling station in Liberia.


title: History of Liberia

text: Ensuring American support for Liberian independence, prosperity, and reform was among the high priorities of United States President, William Howard Taft. The United States played a significant role in training the Liberian army, known as the Liberian Frontier Force, with the assistance of African-American officers from the United States Army. The American presence warded off European powers, defeated a series of local rebellions, and helped bring in American technology to develop the resource-rich interior. Democracy was not a high priority, as the 15,000 Americo-Liberians had full control over the approximately 750,000 locals. The Krus and Greboe tribes remained highly reluctant to accept control from Monrovia, but were not powerful enough to overcome a regime strongly supported by the U.S. Army and Navy. The American officers, including Charles Young and Benjamin Davis among others, were skilled at training recruits, helped the government minimize corruption, and advocated for loans from American corporations (while monitoring the resulting flow of fund).


title: History of Liberia

text: Liberia remained neutral for most of World War I. It joined the war on the Allied side on 4 August 1917. After its declaration of war, the resident German merchants were expelled from Liberia. As they constituted the country's largest investors and trading partners, Liberia suffered economically as a result.


title: History of Liberia

text: In 1926, the Liberian government granted a concession to Firestone, an American rubber company, that allowed the company to establish the world's largest rubber plantation at Harbel, Liberia. Concurrently, Firestone had arranged a $5 million private loan to Liberia. By the 1930s, Liberia became virtually bankrupt once again. After receiving pressure from the United States, the Liberian government agreed to an assistance plan from the League of Nations. As stipulated by the plan, two key officials of the league were placed in positions to "advise" the Liberian government.


title: History of Liberia

text: In 1942, Liberia signed a Defense Pact with the United States. Rubber was a strategically important commodity, and Liberia assured the U.S. and its allies that a sufficient supply of natural rubber would be provided. Furthermore, Liberia allowed the U.S. to use its territory as a bridgehead for transports of soldiers and war supplies, in addition to the construction of military bases, airports, the Freeport of Monrovia, roads to the interior, etc. Many of the American personnel who passed through Liberia were black soldiers (who, at the time, were in racially segregated army divisions), and were deployed into military service in Europe. The American military presence boosted the Liberian economy; thousands of laborers descended from the interior to the coastal region. The country's huge iron ore deposits were made accessible to commerce.


title: History of Liberia

text: The Defense Areas Agreement between the U.S. and Liberia entailed the US-financed construction of Roberts Field airport, the Freeport of Monrovia, and roads into the interior of Liberia. By the end of World War II, approximately 5,000 American troops had been stationed in Liberia. Arguments substantiating this notion are that World War II infrastructure developments did not positively affect social and political struggles in Liberia, and that decades after the development from World War II, Americo-Liberians disproportionately controlled and benefited from Liberia's growing economy and increase in foreign investment.


title: History of Liberia

text: After World War II, the U.S. pressured Liberia to resist the expansion of Soviet influence in Africa during the Cold War. Liberian president William Tubman was agreeable to this policy. Between 1946 and 1960 Liberia received some $500 million in unrestricted foreign investment, mainly from the U.S. From 1962 to 1980, the U.S. donated $280 million in aid to Liberia. In the 1970s under president Tolbert, Liberia strove for a more non-aligned and independent posture, and established diplomatic relations with the Soviet Union, China, Cuba and Eastern bloc countries. It also severed ties with Israel during the Yom Kippur War in 1973, but announced it supported American involvement in the Vietnam War.


title: History of Liberia

text: President William Tolbert pursued a policy of suppressing opposition. Dissatisfaction over governmental plans to raise the price of rice in 1979 led to protest demonstrations in the streets of Monrovia. Tolbert ordered his troops to fire on the demonstrators, and seventy people were killed. Rioting ensued throughout Liberia, finally leading to a military coup d'état in April 1980. Tolbert was killed during the coup, and several of his ministers were executed soon afterwards, marking the end of Americo-Liberian domination of the country.


title: History of Liberia

text: After a bloody overthrow of the Americo-Liberian régime by indigenous Liberians in 1980, a 'Redemption Council' took control of Liberia. Internal unrest, opposition to the new military regime, and governmental repression steadily grew, until in 1989 Liberia sank into outright tribal and civil war.


title: History of Liberia

text: Samuel Kanyon Doe (1951–1990) was a member of the Krahn, a small ethnic group. He was a master sergeant in the Liberian army, and had trained with the U.S. Army Special Forces. On April 12, 1980, Doe led a bloody coup d'état against president Tolbert, in which Tolbert and twenty-six of his supporters were murdered. Ten days later, thirteen of Tolbert's Cabinet members were executed publicly. This ended the 133 years of Americo-Liberian political domination. Doe formed a military regime known as the People's Redemption Council (PRC). Many welcomed Doe's takeover, since the majority of the population had always been excluded from power. The PRC also for the time being tolerated a relatively free press.


title: History of Liberia

text: Doe quickly established good relations with the United States, especially after 1981, when U.S. President Ronald Reagan took office. Reagan more than tripled Liberia's financial aid, from $20 million in 1979 to $75 million per year. This soon rose to $95 million per annum. Liberia again became an important Cold War ally of the United States. Liberia protected important U.S. facilities and investments in Africa, and countered the threatened spread of Soviet influence in the continent. Doe closed the Libyan mission in Monrovia and severed diplomatic relations with the Soviet Union. He agreed to modify the mutual defense pact with the U.S., allowing the U.S. staging rights at 24 hours notice to use Liberia's harbors and airports for the U.S. Rapid Deployment Forces.


title: History of Liberia

text: Under Doe, Liberian ports were opened to American, Canadian, and European merchant ships, which brought in considerable foreign investment from shipping firms and earned Liberia a reputation as a tax haven.


title: History of Liberia

text: Doe put down seven coup attempts between 1981 and 1985. In August 1981, he had Thomas Weh Syen and four other PRC members arrested and executed for allegedly conspiring against him. Doe's government then declared amnesty for all political prisoners and exiles, and released sixty political prisoners.


title: History of Liberia

text: However, there soon were more internal rifts in the PRC. Doe became paranoid about the possibility of a counter-coup, and his government grew increasingly corrupt and repressive, banning all political opposition, shutting down newspapers, and jailing reporters. He began to systematically eliminate PRC members who challenged his authority, and to place people of his own ethnic Krahn background in key positions, which intensified popular anger. Meanwhile, the economy deteriorated precipitously. Popular support for Doe's government evaporated.


title: History of Liberia

text: A draft constitution providing for a multiparty republic had been issued in 1983 and was approved by referendum in 1984. After the referendum, Doe staged a presidential election on October 15, 1985. Nine political parties sought to challenge Doe's National Democratic Party of Liberia (NDPL), but only three were allowed to take part. Prior to the election, more than fifty of Doe's opponents were murdered. Doe was ‘elected’ with 51% of the vote, but the election was heavily rigged. Foreign observers declared the elections fraudulent, and most of the elected opposition candidates refused to take their seats.


title: History of Liberia

text: U.S. Assistant Secretary of State for Africa Chester Crocker testified before Congress that the election was imperfect but that at least it was a step toward democracy. He further justified his support for the election results with the claim that, in any case, all African elections were known to be rigged at that time.


title: History of Liberia

text: In November 1985, Doe's former second-in-command Thomas Quiwonkpa led an estimated 500 to 600 people in a failed attempt to seize power; all were killed. Doe was sworn in as president on January 6, 1986. Doe then initiated crackdowns against certain tribes, such as the Gio (or Dan) and Mano, in the north, where most of the coup plotters came from. This government's mistreatment of certain ethnic groups resulted in divisions and violence among indigenous peoples, who until then had coexisted relatively peacefully.


title: History of Liberia

text: In the late 1980s, as fiscal austerity took hold in the United States and the perceived threat of Communism declined with the waning of the Cold War, the U.S. became disenchanted with Doe's government and began cutting off critical foreign aid to Liberia. This, together with the popular opposition, made Doe's position precarious.


title: History of Liberia

text: In the late 1980s opposition from abroad to Doe’s regime led to economic collapse. Doe had already been repressing and crushing internal opposition for some time, when in November 1985 another coup attempt against him failed. Doe retaliated against tribes such as the Gio (or Dan) and Mano in the north, where most of the coup plotters had come from. Doe's Krahn tribe began attacking other tribes, particularly in Nimba County in the northeast of Liberia, bordering on Côte d’Ivoire (Ivory Coast) and on Guinea. Some Liberian northerners fled brutal treatment from the Liberian army into the Ivory Coast.


title: History of Liberia

text: Charles Taylor, born 1948 in Arthington, Liberia, is son of a Gola mother and either an Americo-Liberian or an Afro-Trinidadian father. Taylor was a student at Bentley University in Waltham, Massachusetts, U.S.A., from 1972 to 1977, earning a degree in economics. After the 1980 "coup d’état" he served some time in Doe's government until he was fired in 1983 on accusation of embezzling government funds. He fled Liberia, was arrested in 1984 in Massachusetts on a Liberian warrant for extradition, and jailed in Massachusetts. He escaped from jail the following year and probably fled to Libya. In 1989, while in the Ivory Coast, Taylor assembled a group of rebels into the National Patriotic Front of Liberia (NPFL), mostly from the Gio and Mano tribes.


title: History of Liberia

text: December 1989, the NPFL invaded Nimba County in Liberia. Thousands of Gio and Mano joined them, Liberians of other ethnic background as well. The Liberian army (AFL) counterattacked, and retaliated against the whole population of the region. Mid-1990, a war was raging between Krahn on one side, and Gio and Mano on the other. On both sides, thousands of civilians were massacred.


title: History of Liberia

text: By the middle of 1990, Taylor controlled much of the country, and by June laid siege to Monrovia. In July, Yormie Johnson split off from NPFL and formed the Independent National Patriotic Front of Liberia (INPFL), based around the Gio tribe. Both NPFL and INPFL continued their siege of Monrovia.


title: History of Liberia

text: In August 1990, the Economic Community of West African States (ECOWAS), an organisation of West African states, created a military intervention force called the Economic Community of West African States Monitoring Group (ECOMOG) composed of 4,000 troops, to restore order. President Doe and Yormie Johnson (INPFL) agreed to this intervention, Taylor didn't.


title: History of Liberia

text: On September 9, President Doe paid a visit to the barely established headquarters of ECOMOG in the Free Port of Monrovia. While he was at the ECOMOG headquarters, he was attacked by INPFL, taken to the INPFL's Caldwell base, tortured, and killed.


title: History of Liberia

text: In November 1990, ECOWAS agreed with some principal Liberian players, but without Charles Taylor, on an Interim Government of National Unity (IGNU) under President Dr. Amos Sawyer. Sawyer established his authority over most of Monrovia, with the help of a paramilitary police force, the 'Black Berets', under Brownie Samukai, while the rest of the country was in the hands of the various warring factions.


title: History of Liberia

text: In June 1991, former Liberian army fighters formed a rebel group, the United Liberation Movement of Liberia for Democracy (ULIMO). They entered western Liberia in September 1991 and gained territories from the NPFL.


title: History of Liberia

text: In 1993, ECOWAS brokered a peace agreement in Cotonou, Benin. On 22 September 1993, the United Nations established the United Nations Observer Mission in Liberia (UNOMIL) to support ECOMOG in implementing the Cotonou agreement. In March 1994, the Interim Government of Amos Sawyer was succeeded by a Council of State of six members headed by David D. Kpormakpor. Renewed armed hostilities broke out in 1994 and persisted. During the course of the year, ULIMO split into two militias: ULIMO-J, a Krahn faction led by Roosevelt Johnson, and ULIMO-K, a Mandigo-based faction under Alhaji G.V. Kromah. Faction leaders agreed to the Akosombo peace agreement in Ghana but with little consequence. In October 1994, the UN reduced its number of UNOMIL observers to about 90 because of the lack of will of combatants to honour peace agreements. In December 1994, the factions and parties signed the Accra agreement, but fighting continued. In August 1995, the factions signed an agreement largely brokered by Jerry Rawlings, Ghanaian President; Charles Taylor agreed. In September 1995, Kpormakpor’s "Council of State" was succeeded by one under the civilian Wilton G. S. Sankawulo and with the factional heads Charles Taylor, Alhaji Kromah, and George Boley in it. In April 1996, followers of Taylor and Kromah assaulted the headquarters of Roosevelt Johnson in Monrovia, and the peace accord collapsed. In August 1996, a new ceasefire was reached in Abuja, Nigeria. On September 3, 1996, Ruth Perry followed Sankawulo as chairwoman of the Council of State, with the same three militia leaders in it.


title: History of Liberia

text: Charles Taylor won the 1997 presidential elections with 75.33 percent of the vote, while the runner-up, Unity Party leader Ellen Johnson Sirleaf, received a mere 9.58 percent of the vote. Accordingly, Taylor's National Patriotic Party gained 21 of a possible 26 seats in the Senate, and 49 of a possible 64 seats in the House of Representatives. The election was judged free and fair by some observers although it was charged that Taylor had employed widespread intimidation to achieve victory at the polls.


title: History of Liberia

text: Bloodshed in Liberia did slow considerably, but it did not end. Violence kept flaring up. During his entire reign, Taylor had to fight insurgencies against his government. Suspicions were rife that Taylor continued to assist rebel forces in neighbouring countries like Sierra Leone, trading weapons for diamonds.


title: History of Liberia

text: President Charles Taylor had fortified his power over Liberia, mostly by purging the security forces of opponents, killing opposition figures, and raising new paramilitary units that were loyal only to him or his most trusted officers. Nevertheless, he still faced a few remaining opponents in the country, mostly former warlords of the First Liberian Civil War who had kept part of their forces to protect themselves from Taylor. His most important domestic rival by early 1998 was Roosevelt Johnson, a Krahn leader and former commander of the ULIMO. After some minor armed altercations, almost all of Johnson's followers were finally killed by Taylor's security forces during a major firefight in September 1998, though Johnson himself managed to flee into the United States embassy. After one last attempt by Taylor's paramilitaries to kill him there, causing a major diplomatic incident, Johnson was evacuated to Ghana.


title: History of Liberia

text: Some ULIMO forces reformed themselves as the Liberians United for Reconciliation and Democracy (LURD), backed by the government of neighbouring Guinea. In 1999, they emerged in northern Liberia, and in April 2000 they started fighting in Lofa County in northernmost Liberia. By the spring of 2001, they were posing a major threat to the Taylor government. Liberia was now engaged in a complex three-way conflict with Sierra Leone and the Republic of Guinea.


title: History of Liberia

text: Meanwhile, the United Nations Security Council in March 2001 (Resolution 1343) concluded that Liberia and Charles Taylor played roles in the civil war in Sierra Leone, and therefore:


title: History of Liberia

text: By the beginning of 2002, Sierra Leone and Guinea were supporting the LURD, while Taylor was supporting opposition factions in both countries. By supporting Sierra Leonean rebels, Taylor also drew the hostility of the British and American governments.


title: History of Liberia

text: In 2003, other elements of the former ULIMO-factions formed another new small rebel group in the Republic of Ivory Coast, the Movement for Democracy in Liberia (MODEL), headed by Mr Yayah Nimley, and they emerged in the south of Liberia.


title: History of Liberia

text: In 2002, the women in Liberia were tired of seeing their country torn apart. Organized by social worker Leymah Gbowee, women started gathering and praying in a fish market to protest the violence. They organized the Women in Peacebuilding Network (WIPNET), and issued a statement of intent: "In the past we were silent, but after being killed, raped, dehumanized, and infected with diseases, and watching our children and families destroyed, war has taught us that the future lies in saying NO to violence and YES to peace! We will not relent until peace prevails."


title: History of Liberia

text: Joined by Liberian Muslim Women's Organization, Christian and Muslim women joined forces to create Women of Liberia Mass Action for Peace. They wore white, to symbolize peace. They staged silent nonviolence protests and forced a meeting with President Charles Taylor and extracted a promise from him to attend peace talks in Ghana.


title: History of Liberia

text: In 2003, a delegation of Liberian women went to Ghana to continue to apply pressure on the warring factions during the peace process. They staged a sit in outside of the Presidential Palace, blocking all the doors and windows and preventing anyone from leaving the peace talks without a resolution. Women of Liberia Mass Action for Peace became a political force against violence and against their government. Their actions brought about an agreement during the stalled peace talks. As a result, the women were able to achieve peace in Liberia after a 14-year civil war and later helped bring to power the country's first female head of state, Ellen Johnson Sirleaf.


title: History of Liberia

text: On March 7, 2003, the war tribunal Special Court for Sierra Leone (SCSL) decided to summon Charles Taylor and charge him with war crimes and crimes against humanity, but they kept this decision and this charge secret until June that year.


title: History of Liberia

text: Due to concerns over the lack of social, humanitarian and development use of industry revenue by the Liberian government, the UN Security Council enacted a 10-month embargo on timber imports from Liberia on July 7, 2003 (passed in Resolution 1478).


title: History of Liberia

text: By mid-2003, LURD controlled the northern third of the country and was threatening the capital, MODEL was active in the south, and Taylor's government controlled only a third of the country: Monrovia and central Liberia.


title: History of Liberia

text: On June 4, 2003, ECOWAS organized peace talks in Accra, Ghana, among the Government of Liberia, civil society, and the rebel groups LURD and MODEL. On the opening ceremony, in Taylor's presence, the SCSL revealed their charge against Taylor, which they had kept secret since March, and also issued an international arrest warrant for Taylor. The SCSL indicted Taylor for “bearing the greatest responsibility” for atrocities in Sierra Leone since November 1996. The Ghanaian authorities did not attempt to arrest Taylor, declaring they could not round up a president they themselves had invited as a guest for peace talks. The same day, Taylor returned to Liberia.


title: History of Liberia

text: June 2003, LURD began a siege of Monrovia. July 9, the Nigerian President offered Taylor safe exile in his country, if Taylor stayed out of Liberian politics. Also in July, American President Bush stated twice that Taylor “must leave Liberia”. Taylor insisted that he would resign only if American peacekeeping troops were deployed to Liberia.


title: History of Liberia

text: August 1, 2003, the Security Council, (Resolution 1497) decided on a multinational force in Liberia, to be followed-on by a United Nations stabilization force.


title: History of Liberia

text: ECOWAS sent troops under the banner of 'ECOMIL' to Liberia. These troops started to arrive in Liberia probably as of August 15. The U.S. provided logistical support. President Taylor resigned, and flew into exile in Nigeria. Vice-President Moses Blah replaced Taylor as interim-President.


title: History of Liberia

text: An ECOWAS-ECOMIL force of 1000 Nigerian troops was airlifted into Liberia on August 15, to halt the occupation of Monrovia by rebel forces. Meanwhile, U.S. stationed a Marine Expeditionary Unit with 2300 Marines offshore Liberia.


title: History of Liberia

text: On August 18, 2003, the Liberian Government, the rebels, political parties, and leaders from civil society signed the Accra Comprehensive Peace Agreement that laid the framework for a two-year National Transitional Government of Liberia. August 21, they selected businessman Charles Gyude Bryant as chair of the National Transitional Government of Liberia (NTGL), effective on October 14. These changes paved the way for the ECOWAS peacekeeping mission to expand into a 3,600-strong force, constituted by Benin, Gambia, Ghana, Guinea-Bissau, Mali, Nigeria, Senegal and Togo.


title: History of Liberia

text: On October 1, 2003, UNMIL took over the peacekeeping duties from ECOWAS. Some 3,500 West African troops were provisionally ‘re-hatted’ as United Nations peacekeepers. The UN Secretary-General commended the African Governments who have contributed to UNMIL, as well as the United States for its support to the regional force. October 14, 2003, Blah handed power to Gyude Bryant.


title: History of Liberia

text: Fighting initially continued in parts of the country, and tensions between the factions did not immediately vanish.


title: History of Liberia

text: But fighters were being disarmed; in June 2004, a program to reintegrate the fighters into society began; the economy recovered somewhat in 2004; by year's end, the funds for the re-integration program proved inadequate; also by the end of 2004, more than 100,000 Liberian fighters had been disarmed, and the disarmament program was ended.


title: History of Liberia

text: In light of the progress made, President Bryant requested an end to the UN embargo on Liberian diamonds (since March 2001) and timber (since May 2003), but the Security Council postponed such a move until the peace was more secure. Because of a supposed ‘fundamentally broken system of governance that contributed to 23 years of conflict in Liberia’, and failures of the Transitional Government in curbing corruption, the Liberian government and the International Contact Group on Liberia signed onto the anti-corruption program GEMAP, starting September 2005.


title: History of Liberia

text: The transitional government prepared for fair and peaceful democratic elections on October 11, 2005, with UNMIL troops safeguarding the peace. Twenty three candidates stood for the presidential election, with George Weah, international footballer, UNICEF Goodwill Ambassador and member of the Kru ethnic group, and Ellen Johnson Sirleaf, a former World Bank economist and finance minister, Harvard-trained economist and of mixed Americo-Liberian and indigenous descent.


title: History of Liberia

text: In the first round, no candidate took the required majority, Weah won this round with 28% of the vote. A run-off between the top two vote getters, Weah and Ellen Johnson Sirleaf, was necessary.


title: History of Liberia

text: The second round of elections took place on November 8, 2005. Ellen Johnson Sirleaf won this runoff decisively. Both the general election and runoff were marked by peace and order, with thousands of Liberians waiting patiently in the Liberian heat to cast their ballots.


title: History of Liberia

text: Sirleaf claimed victory of this round, winning 59 per cent of the vote. However, Weah alleged electoral fraud, despite international observers declaring the election to be free and fair. Although Weah was still threatening to take his claims to the Supreme Court if no evidence of fraud was found, Johnson-Sirleaf was declared winner on November 23, 2005, and took office on January 16, 2006; becoming the first African woman to do so.


title: History of Liberia

text: In November 2005, the International Labor Rights Fund filed an Alien Tort Claims Act (ATCA) case against Bridgestone, the parent company of Firestone, alleging “forced labor", the modern equivalent of slavery, on the Firestone Plantation in Harbel. In May 2006, the United Nations Mission in Liberia (UNMIL) released a report: “Human Rights in Liberia’s Rubber Plantations: Tapping into the Future”, which detailed the results of its investigation into the conditions on the Firestone plantation in Liberia.


title: History of Liberia

text: Under international pressure, President Sirleaf requested in March 2006 that Nigeria extradite Charles Taylor, who was then brought before an international tribunal in Sierra Leone to face charges of crimes against humanity, arising from events during the Sierra Leone civil war (his trial was later transferred to The Hague for security purposes). In June 2006, the United Nations ended its embargo on Liberian timber (effective since May 2003), but continued its diamond embargo (effective since March 2001) until an effective certificate of origin program was established, a decision that was reaffirmed in October 2006.


title: History of Liberia

text: In March 2007, former Interim President Bryant was arrested and charged with having embezzled government funds while in office. In August 2007, the Supreme Court of Liberia allowed the criminal prosecution for this to proceed in the lower courts. The court ruled that Bryant was not entitled to immunity as the head of state under the Constitution as he was not elected to the position and he was not acting in accordance with law when he allegedly stole US$1.3 million in property from the government.


title: History of Liberia

text: In 2014 an Ebola virus disease epidemic struck West Africa (see Ebola virus epidemic in West Africa), and spread to Liberia in early 2014. A few initial cases grew into an Ebola virus epidemic in Liberia.


title: History of Liberia

text: Following the 2017 Liberian general election, former professional football striker George Weah, one of the greatest African players of all time, was sworn in as president on January 22, 2018, becoming the fourth youngest serving president in Africa. The inauguration marked Liberia's first fully democratic transition in 74 years. Weah cited fighting corruption, reforming the economy, combating illiteracy, and improving life conditions as the main targets of his presidency.


title: Darcy's law

text: Darcy's law is an equation that describes the flow of a fluid through a porous medium. The law was formulated by Henry Darcy based on results of experiments on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of earth sciences. It is analogous to Ohm's law in electrostatics, linearly relating the volume flow rate of the fluid to the hydraulic head difference (which is often just proportional to the pressure difference) via the hydraulic conductivity.


title: Darcy's law

text: Darcy's law was first determined experimentally by Darcy, but has since been derived from the Navier–Stokes equations via homogenization methods. It is analogous to Fourier's law in the field of heat conduction, Ohm's law in the field of electrical networks, and Fick's law in diffusion theory.


title: Darcy's law

text: One application of Darcy's law is in the analysis of water flow through an aquifer; Darcy's law along with the equation of conservation of mass simplifies to the groundwater flow equation, one of the basic relationships of hydrogeology.


title: Darcy's law

text: Morris Muskat first refined Darcy's equation for a single-phase flow by including viscosity in the single (fluid) phase equation of Darcy. It can be understood that viscous fluids have more difficulty permeating through a porous medium than less viscous fluids. This change made it suitable for researchers in the petroleum industry. Based on experimental results by his colleagues Wyckoff and Botset, Muskat and Meres also generalized Darcy's law to cover a multiphase flow of water, oil and gas in the porous medium of a petroleum reservoir. The generalized multiphase flow equations by Muskat and others provide the analytical foundation for reservoir engineering that exists to this day.


title: Darcy's law

text: Darcy's law, as refined by Morris Muskat, in the absence of gravitational forces and in a homogeneously permeable medium, is given by a simple proportionality relationship between the instantaneous flux formula_1 (units of formula_2: m/s, units of formula_3: m, units of formula_4: m/s) through a porous medium, the permeability formula_5 of the medium, the dynamic viscosity of the fluid formula_6, and the pressure drop formula_7 over a given distance formula_8, in the form


title: Darcy's law

text: This equation, for single phase (fluid) flow, is the defining equation for absolute permeability (single phase permeability).


title: Darcy's law

text: With reference to the diagram to the right, the flux formula_4, or discharge per unit area, is defined in units formula_11, the permeability formula_5 in units formula_13, the cross-sectional area formula_3 in units formula_13, the total pressure drop formula_16 in units formula_17, the dynamic viscosity formula_6 in units formula_19, and formula_8 is the length of the sample in units formula_21. A number of these parameters are used in alternative definitions below. A negative sign is used in the definition of the flux following the standard physics convention that fluids flow from regions of high pressure to regions of low pressure. Note that the elevation head must be taken into account if the inlet and outlet are at different elevations. If the change in pressure is negative, then the flow will be in the positive direction. There have been several proposals for a constitutive equation for absolute permeability, and the most famous one is probably the Kozeny equation (also called Kozeny–Carman equation).


title: Darcy's law

text: where (units of volume per time, e.g., m/s) is the total discharge. By considering the relation for static fluid pressure (Stevin's law):


title: Darcy's law

text: Notice that the quantity formula_4 or formula_27, often referred to as the Darcy flux or Darcy velocity, is not the velocity at which the fluid is travelling through the pores. The flow velocity () is related to the flux () by the porosity () and takes the form


title: Darcy's law

text: Darcy's law is a simple mathematical statement which neatly summarizes several familiar properties that groundwater flowing in aquifers exhibits, including:


title: Darcy's law

text: A graphical illustration of the use of the steady-state groundwater flow equation (based on Darcy's law and the conservation of mass) is in the construction of flownets, to quantify the amount of groundwater flowing under a dam.


title: Darcy's law

text: Darcy's law is only valid for slow, viscous flow; however, most groundwater flow cases fall in this category. Typically any flow with a Reynolds number less than one is clearly laminar, and it would be valid to apply Darcy's law. Experimental tests have shown that flow regimes with Reynolds numbers up to 10 may still be Darcian, as in the case of groundwater flow. The Reynolds number (a dimensionless parameter) for porous media flow is typically expressed as


title: Darcy's law

text: where is the kinematic viscosity of water, is the specific discharge (not the pore velocity — with units of length per time), is a representative grain diameter for the porous media (the standard choice is d30, which is the 30% passing size from a grain size analysis using sieves — with units of length).


title: Darcy's law

text: For stationary, creeping, incompressible flow, i.e. , the Navier–Stokes equation simplifies to the Stokes equation, which by neglecting the bulk term is:


title: Darcy's law

text: where is the viscosity, is the velocity in the direction, is the gravity component in the direction and is the pressure. Assuming the viscous resisting force is linear with the velocity we may write:


title: Darcy's law

text: where is the porosity, and is the second order permeability tensor. This gives the velocity in the direction,


title: Darcy's law

text: In isotropic porous media the off-diagonal elements in the permeability tensor are zero, for and the diagonal elements are identical, , and the common form is obtained as below, which enables the determination of the liquid flow velocity by solving a set of equations in a given region.


title: Darcy's law

text: Another derivation of Darcy's law is used extensively in petroleum engineering to determine the flow through permeable media — the most simple of which is for a one-dimensional, homogeneous rock formation with a single fluid phase and constant fluid viscosity.


title: Darcy's law

text: Almost all oil reservoirs have a water zone below the oil leg, and some have also a gas cap above the oil leg. When the reservoir pressure drops due to oil production, water flows into the oil zone from below, and gas flows into the oil zone from above (if the gas cap exists), and we get a simultaneous flow and immiscible mixing of all fluid phases in the oil zone. The operator of the oil field may also inject water (and/or gas) in order to improve oil production. The petroleum industry is therefore using a generalized Darcy equation for multiphase flow that was developed by Muskat et alios. Because Darcy's name is so widespread and strongly associated with flow in porous media, the multiphase equation is denoted Darcy's law for multiphase flow or generalized Darcy equation (or law) or simply Darcy's equation (or law) or simply flow equation if the context says that the text is discussing the multiphase equation of Muskat et alios. Multiphase flow in oil and gas reservoirs is a comprehensive topic, and one of many articles about this topic is Darcy's law for multiphase flow.


title: Darcy's law

text: A number of papers have utilized Darcy's law to model the physics of brewing in a moka pot, specifically how the hot water percolates through the coffee grinds under pressure, starting with a 2001 paper by Varlamov and Balestrino, and continuing with a 2007 paper by Gianino, a 2008 paper by Navarini et al., and a 2008 paper by W. King. The papers will either take the coffee permeability to be constant as a simplification or will measure change through the brewing process.


title: Darcy's law

text: where q is the volume flux vector of the fluid at a particular point in the medium, "h" is the total hydraulic head, and "K" is the hydraulic conductivity tensor, at that point. The hydraulic conductivity can often be approximated as a scalar. (Note the analogy to Ohm's law in electrostatics. The flux vector is analogous to the current density, head is analogous to voltage, and hydraulic conductivity is analogous to electrical conductivity.)


title: Darcy's law

text: For flows in porous media with Reynolds numbers greater than about 1 to 10, inertial effects can also become significant. Sometimes an inertial term is added to the Darcy's equation, known as Forchheimer term. This term is able to account for the non-linear behavior of the pressure difference vs flow data.


title: Darcy's law

text: The flow in the middle of a sandstone reservoir is so slow that Forchheimer's equation is usually not needed, but the gas flow into a gas production well may be high enough to justify use of Forchheimer's equation. In this case, the inflow performance calculations for the well, not the grid cell of the 3D model, is based on the Forchheimer equation. The effect of this is that an additional rate-dependent skin appears in the inflow performance formula.


title: Darcy's law

text: Some carbonate reservoirs have many fractures, and Darcy's equation for multiphase flow is generalized in order to govern both flow in fractures and flow in the matrix (i.e. the traditional porous rock). The irregular surface of the fracture walls and high flow rate in the fractures may justify the use of Forchheimer's equation.


title: Darcy's law

text: For gas flow in small characteristic dimensions (e.g., very fine sand, nanoporous structures etc.), the particle-wall interactions become more frequent, giving rise to additional wall friction (Knudsen friction). For a flow in this region, where both viscous and Knudsen friction are present, a new formulation needs to be used. Knudsen presented a semi-empirical model for flow in transition regime based on his experiments on small capillaries. For a porous medium, the Knudsen equation can be given as


title: Darcy's law

text: where is the molar flux, is the gas constant, is the temperature, is the effective Knudsen diffusivity of the porous media. The model can also be derived from the first-principle-based binary friction model (BFM). The differential equation of transition flow in porous media based on BFM is given as


title: Darcy's law

text: This equation is valid for capillaries as well as porous media. The terminology of the Knudsen effect and Knudsen diffusivity is more common in mechanical and chemical engineering. In geological and petrochemical engineering, this effect is known as the Klinkenberg effect. Using the definition of molar flux, the above equation can be rewritten as


title: Darcy's law

text: where is known as the Klinkenberg parameter, which depends on the gas and the porous medium structure. This is quite evident if we compare the above formulations. The Klinkenberg parameter is dependent on permeability, Knudsen diffusivity and viscosity (i.e., both gas and porous medium properties).


title: Darcy's law

text: For very short time scales, a time derivative of flux may be added to Darcy's law, which results in valid solutions at very small times (in heat transfer, this is called the modified form of Fourier's law),


title: Darcy's law

text: where is a very small time constant which causes this equation to reduce to the normal form of Darcy's law at "normal" times (> nanoseconds). The main reason for doing this is that the regular groundwater flow equation (diffusion equation) leads to singularities at constant head boundaries at very small times. This form is more mathematically rigorous but leads to a hyperbolic groundwater flow equation, which is more difficult to solve and is only useful at very small times, typically out of the realm of practical use.


title: Darcy's law

text: Another extension to the traditional form of Darcy's law is the Brinkman term, which is used to account for transitional flow between boundaries (introduced by Brinkman in 1949),


title: Darcy's law

text: where is an effective viscosity term. This correction term accounts for flow through medium where the grains of the media are porous themselves, but is difficult to use, and is typically neglected.


title: Darcy's law

text: Darcy's law is valid for laminar flow through sediments. In fine-grained sediments, the dimensions of interstices are small and thus flow is laminar. Coarse-grained sediments also behave similarly but in very coarse-grained sediments the flow may be turbulent. Hence Darcy's law is not always valid in such sediments.


title: Darcy's law

text: For flow through commercial circular pipes, the flow is laminar when Reynolds number is less than 2000 and turbulent when it is more than 4000, but in some sediments, it has been found that flow is laminar when the value of Reynolds number is less than 1.


title: Textbook

text: A textbook is a book containing a comprehensive compilation of content in a branch of study with the intention of explaining it. Textbooks are produced to meet the needs of educators, usually at educational institutions. Schoolbooks are textbooks and other books used in schools. Today, many textbooks are published in both print and digital formats.