In telecommunications and reliability theory, the term availability has the following meanings:

• The degree to which a system, subsystem, or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, i.e., a random, time. Simply put, availability is the proportion of time a system is in a functioning condition. This is often described as a mission capable rate. Mathematically, this is expressed as 1 minus unavailability.
• The ratio of (a) the total time a functional unit is capable of being used during a given interval to (b) the length of the interval.

For example, a unit that is capable of being used 100 hours per week (168 hours) would have an availability of 100/168. However, typical availability values are specified in decimal (such as 0.9998). In high availability applications, a metric known as nines, corresponding to the number of nines following the decimal point, is used. In this system, "five nines" equals 0.99999 (or 99.999%) availability.

Availability in Layman's Terms[link]

Availability of a system is typically measured as a factor of its reliability - as reliability increases, so does availability. However, no system can guarantee 100.000% reliability; and as such, no system can assure 100.000% availability. Further, reliability engineering and maintainability involve processes designed to optimize availability under a set of constraints, such as time and cost-effectiveness. Availability is the goal of most system users, and reliability engineering and maintainability provide the means to assure that availability performance requirements are achieved.

Representation[link]

The most simple representation for availability is as a ratio of the expected value of the uptime of a system to the aggregate of the expected values of up and down time, or

Failed to parse (Missing texvc executable; please see math/README to configure.): A = \frac{E[\mathrm{Uptime}]}{E[\mathrm{Uptime}]+E[\mathrm{Downtime}]}

If we define the status function Failed to parse (Missing texvc executable; please see math/README to configure.): X(t)

as

Failed to parse (Missing texvc executable; please see math/README to configure.): X(t)= \begin{cases} 1, & \mbox{sys functions at time } t\\ 0, & \mbox{otherwise} \end{cases}

therefore, the availability A(t) at time t>0 is represented by

Failed to parse (Missing texvc executable; please see math/README to configure.): A(t)=\Pr[X(t)=1]=E[X(t)].

Average availability must be defined on an interval of the real line. If we consider an arbitrary constant Failed to parse (Missing texvc executable; please see math/README to configure.): c>0 , then average availability is represented as

Failed to parse (Missing texvc executable; please see math/README to configure.): A_c = \frac{1}{c}\int_0^c A(t)\,dt.

Limiting (or steady-state) availability is represented by^{[citation needed]}

Failed to parse (Missing texvc executable; please see math/README to configure.): A = \lim_{t \rightarrow \infty} A(t).

Limiting average availability is also defined on an interval Failed to parse (Missing texvc executable; please see math/README to configure.): (0,c]

as,

Failed to parse (Missing texvc executable; please see math/README to configure.): A_{\infty}=\lim_{c \rightarrow \infty} A_c = \lim_{c \rightarrow \infty}\frac{1}{c}\int_0^c A(t)\,dt,\quad c > 0.

Example[link]

If we are using equipment which has mean time to failure (MTTF) of 81.5 years and mean time to repair (MTTR) of 1 hour:

MTTF in hours = 81.5*365*24=713940

Availability= MTTF/(MTTF+MTTR) = 713940/713941 =99.999859%

Unavailability = 0.000141%

Outage due to equipment in hours per year

U=0.01235 hours per year.

Literature[link]

Availability is well established in the literature of stochastic modeling and optimal maintenance. Barlow and Proschan [1975] define availability of a repairable system as "the probability that the system is operating at a specified time t." While Blanchard [1998] gives a qualitative definition of availability as "a measure of the degree of a system which is in the operable and committable state at the start of mission when the mission is called for at an unknown random point in time." This definition comes from the MIL-STD-721. Lie, Hwang, and Tillman [1977] developed a complete survey along with a systematic classification of availability.

Availability measures are classified by either the time interval of interest or the mechanisms for the system downtime. If the time interval of interest is the primary concern, we consider instantaneous, limiting, average, and limiting average availability. The aforementioned definitions are developed in Barlow and Proschan [1975], Lie, Hwang, and Tillman [1977], and Nachlas [1998]. The second primary classification for availilability is contingent on the various mechanisms for downtime such as the inherent availability, achieved availability, and operational availability. (Blanchard [1998], Lie, Hwang, and Tillman [1977]). Mi [1998] gives some comparison results of availability considering inherent availability.

Availability considered in maintenance modeling can be found in Barlow and Proschan [1975] for replacement models, Fawzi and Hawkes [1991] for an R-out-of-N system with spares and repairs, Fawzi and Hawkes [1990] for a series system with replacement and repair, Iyer [1992] for imperfect repair models, Murdock [1995] for age replacement preventive maintenance models, Nachlas [1998, 1989] for preventive maintenance models, and Wang and Pham [1996] for imperfect maintenance models.

See also[link]

• High availability
• List of system quality attributes
• Spurious trip level

References[link]

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).

External links[link]

• Reliability and Availability Basics
• System Reliability and Availability

Flo Rida
Flo Rida on the set of "Sugar" in 2009.
Background information
Birth name	Tramar Dillard
Born	(1979-12-16) December 16, 1979 (age 32) Carol City, Florida, U.S.
Genres	Hip hop
Occupations	Rapper, songwriter, actor
Years active	2006–present
Labels	Atlantic, Poe Boy, International Music Group, Strong Arm
Associated acts	Akon, Brisco, Lady Gaga, Timbaland, David Guetta, Kesha, T-Pain, Nicki Minaj , Taio Cruz, Sia Furler, Ne-Yo, Avicii
Website	officialflo.com

Tramar Dillard (born December 16, 1979) better known by his stage name Flo Rida (pronounced  /floʊ ˈraɪdə/), is an American rapper. He released his debut album, Mail on Sunday, in March 2008. His debut single "Low", featuring T-Pain, was a No. 1 hit for ten weeks in United States in early 2008. Two other singles resulted from Mail on Sunday: "Elevator" and "In the Ayer". In 2009, his second album R.O.O.T.S. was released; its most successful single "Right Round" was at the top of the Hot 100 for six weeks. Since then, he has released his third studio album titled Only One Flo (Part 1), which will see a sequel titled Wild Ones.

Biography[link]

Early life and career beginnings[link]

Tramar Dillard was born in the 187th Street projects of Carol City, Florida.^[1] His mother raised him and his seven sisters, some of whom sang in a local gospel group.^[2] Dillard's brother-in-law was a hypeman for local rap group 2 Live Crew, and while in ninth grade, Dillard formed his own amateur group with some friends called the GroundHoggz.^[3] Born and raised in Miami, the GroundHoggz formed in the 187 apartments in Carol City. Similar to Goodie Mob, they were making music for the love of the art and to feed their souls. With only three members, 1Bred, Key Lime, and Fist, they found their missing link when Flo Rida, who lived in the same apartments, spit a verse for them. They were instantly impressed. Together for eight years, they started recording at underground studios in Carver Ranches.^[4] His work with 2 Live Crew member Fresh Kid Ice attracted the attention of DeVante Swing, a member of the band Jodeci. However, he was rejected by several of the major labels, so he sought many other jobs outside of music.^[5] After graduating from high school in 1998, he studied international business management at the University of Nevada, Las Vegas for two years and attended Barry University for two months.^[5][6] He returned to Florida to continue pursuing his music career after receiving a phone call from a representative of the independent label Poe Boy Entertainment.^[5] Dillard signed with Poe Boy in 2006, and as Flo Rida he began affiliating with other artists, such as Rick Ross, Trina, T-Pain, and Trick Daddy. A promotional street single entitled "Birthday", featuring Rick Ross, was his first significant release. He made his debut guest appearance with the song "Bitch I'm from Dade County" on DJ Khaled's album We the Best, which featured Trick Daddy, Trina, Rick Ross, Brisco, C-Ride, and Dre.^[7]

[edit] 2007–08: Mail on Sunday

Rehearsing for the 2008 MuchMusic Video Awards in Toronto.

Flo Rida's first single was "Low", featuring T-Pain. It was his first official single from his debut album Mail On Sunday and the soundtrack to the movie Step Up 2: The Streets. "Low" reached No. 1 on the Billboard Hot 100 chart.^[7] "Elevator", featuring Timbaland, "In the Ayer" featuring will.i.am, and "Roll" featuring Sean Kingston followed and all charted on the Hot 100 and other charts.^[8]

T-Pain, who laced the first single, is only one of the many featured guests throughout the album. Timbaland, who produced the second single "Elevator", is also featured on the track. Rick Ross, and Trey Songz made appearances as well.^[9] Lil Wayne has also been added to the list^[9] with assistance on the "American Superstar" track while Sean Kingston appears on the J. R. Rotem-produced "Roll" the concept was created, and co-written by Compton rapper Spitfiya, from The Bullets Production Team, Various other guests include Birdman, Brisco, and Yung Joc. The third single is "In the Ayer" featuring Will.i.am. The fourth single was scheduled to be "Money Right" featuring Brisco, and Rick Ross, but was canceled due to the release of his upcoming second studio album R.O.O.T.S. His second collaboration with T-Pain, "I Bet", as well as his collaboration with Trina, named "Bout It", both didn't make the final tracklist, but were recorded. As for production, J. R. Rotem, DJ Montay, and Timbaland all provided tracks for Mail on Sunday, among others.

After the success of Mail on Sunday, Flo Rida made guest performances on other R&B, rap, and pop singles, including "Move Shake Drop" by DJ Laz, "We Break the Dawn" by Michelle Williams, the remix of "4 Minutes" by Madonna, "Running Back" by Australian R&B singer Jessica Mauboy, "Feel It" by DJ Felli Fel, and the remix of "Speedin'" by Rick Ross. During the summer of 2008, he did live performances on the Fox dance competition program So You Think You Can Dance in the US^[10] and 2008 MuchMusic Video Awards in Canada.^[11] He appeared on the albums We Global by DJ Khaled, Gutta by Ace Hood, and The Fame by Lady Gaga, among others.

[edit] 2009–10: R.O.O.T.S.

Flo Rida performing "Right Round" at the Circus Club in Finland on July 9, 2009.

According to Billboard magazine, Flo Rida began recording his sophomore nine months after Mail On Sunday. The album is titled R.O.O.T.S. and was released on March 31, 2009.^[12] The first single "Right Round" featured Ke$ha and was released for airplay in January 2009. "Right Round" jumped from number 58 to the top spot in one week in late February. The song broke a record for the most digital one week sales in the U.S., with 636,000, beating the previous record he had set himself with "Low".^[13] "Right Round" sampled "You Spin Me Round (Like a Record)", a 1985 hit by Dead or Alive.^[14] The second official single was "Sugar", which featured R&B singer Wynter Gordon. The song reached No. 5 on the Billboard Hot 100. "Jump" is the third official single and was released on July 27, 2009 in the UK, and July 28, 2009 worldwide.^[15] The song features Canadian singer Nelly Furtado. As of August 13, 2009 it has peaked at number fifty-four in the US, number twenty-seven in Canada, number twenty-one in the UK, and number eighteen in Australia. "Be on You" has been confirmed as the album's fourth official single for a release on October 6, 2009. The song features American singer Ne-Yo. When the album was released the single debuted at number ninety in the US. The song has received airplay since the albums release, and has since peaked at number nineteen in the US, and number fifty-one in the UK. "Available" was going to be released on iTunes but was cancelled. It charted at number 120 in Ireland. The song features Akon. A music video was also shot in mid-2009.^[16] R.O.O.T.S. debuted at number eight on the Billboard 200 chart, selling 55,000 copies in its first week.^[17] As of August, 2009, the album has sold 223,000 copies in the United States, and 536,000 worldwide. By the end of 2009, the album sold 247,000 copies becoming the eighth best selling rap album of 2009.^[18]

Flo Rida made guest performances on "Feel It" by DJ Felli Fel, "Starstruck" by Lady Gaga, and "Feel It" by Three 6 Mafia. "Bad Boys", the first single by winner of British reality show The X Factor Alexandra Burke that featured Flo Rida, debuted at No. 1 on the UK Singles Chart in October.^[19]

[edit] 2010–11: Only One Flo (Part 1)

Flo Rida's third album Only One Flo (Part 1) was released on November 24, 2010. In March 2010, Flo Rida announced on Twitter that the album would be titled The Only One.^[20] Billboard reported that The Only One was to be a double album.^[21] A promo single, titled "Zoosk Girl", which features T-Pain, was released on the internet, though the song is not featured on the album, the single does have its own music video. On June 28, 2010, Flo Rida released the song "Club Can't Handle Me" featuring David Guetta, which was stated to be the official first single for the album. The song was also featured in the Step Up 3D soundtrack.^[22] On November 2, 2010, "Come with Me" was released as the first promo single for the album, along with "Puzzle", produced, and featuring by Electrixx, which isn't featured on the album. On November 16, 2010, "Turn Around (5, 4, 3, 2, 1)" was released as the second official promo single for the album via the iTunes Store.^[23] It debuted on the Australian Singles Chart at number thirty-four on November 29, 2010.^[24] After the release of the album in the UK, "Who Dat Girl" started to receive a strong amount of downloads, thus causing it to debut at number 136^[25] on the UK Singles Chart and chart at a current peak of number thirty-one on the UK R&B Chart.^[26] "Why You Up In Here" was released as the fourth single, and third promo single, on May 11, 2011. The song features Ludacris, Gucci Mane, and Git Fresh.

Flo Rida also made guest appearances on "iYiYi", a song by Australian teen singer Cody Simpson, and on the song "Out My Video" by Bulgarian singer LiLana. Flo Rida collaborated with UK girl group The Saturdays, recording a new version of the girl's single, "Higher".^[27] In December 2010, the Associated Press reported that Flo Rida had created his own label, International Music Group, inspired by Nicki Minaj's signing with Lil Wayne's. He has signed an 18 year-old rapper, Brianna^[28] and Git Fresh^[29] to International. Lately, Flo Rida has teamed up with the Malaysian singer, Mizz Nina, on a song called Take Over.

Driving issues[link]

On June 9, 2011, Flo Rida was arrested in Miami Beach, Florida for DUI and driving with a suspended license.^[30][31] Flo Rida was released from jail after he posted $2,000 bail and obtained a signed court order allowing him to travel to Asia for a series of previously scheduled concerts in Bangkok over the weekend.^[32]

[edit] 2011–present: Wild Ones

Flo Rida performing live in 2012.

The first single from Rida's upcoming album, Wild Ones, originally Only One Rida (Part 2), is "Good Feeling", released on August 29, 2011.^[33] The songs samples "Levels" by Avicii, which samples Etta James' 1962 song, "Something's Got a Hold on Me". Following the death of Etta James on January 20, 2012, Flo Rida dedicated the song in her memory.^[34] The song has peaked at No. 3 on the Hot 100,^[35] topped the charts in Austria,^[36] Germany,^[37] Scotland,^[38] and the UK. It has also reached the top five in nine different countries worldwide.

On April 1, Flo Rida made an appearance at WrestleMania XXVIII and have a segment with Heath Slater, Curt Hawkins and Tyler Reks where Heath calls Flo Rida "Florida" and Flo Rida shoves him into a wall; making Tyler and Curt come out laughing at Heath. Later that night Flo Rida performed "Wild Ones" and "Good Feeling" before Dwayne "The Rock" Johnson came out to battle John Cena. On April 6, 2012 and exclusive Australian EP entitled Good Feeling was released in Australia which contains six of his biggest hits and two remixes.^[39] It debuted at No. 21 on the Australian ARIA Albums Chart^[40] On May 22, 2012, Flo Rida performed and closed the show at the first Q102 Springle Ball Concert, the following day he performed "Goin' In" with Jennifer Lopez on the America Idol finale.

Discography[link]

• Mail on Sunday (2008)
• R.O.O.T.S. (2009)
• Only One Flo (Part 1) (2010)
• Wild Ones (2012)

Awards and nominations[link]

References[link]

External links[link]

• Official website