Energy (signal processing)

In signal processing, the energy of a continuous-time signal x(t) is defined as

the energy of a discrete-time signal x(t) is defined as

Relationship to energy in physics

Energy in this context is not, strictly speaking, the same as the conventional notion of energy in physics and the other sciences. The two concepts are, however, closely related, and it is possible to convert from one to the other:

For example, if x(t) represents the potential (in volts) of an electrical signal propagating across a transmission line, then Z would represent the characteristic impedance (in ohms) of the transmission line. The units of measure for the signal energy would appear as volt²·seconds, which is not dimensionally correct for energy in the sense of the physical sciences. After dividing by Z, however, the dimensions of E would become volt²·seconds per ohm, which is equivalent to joules, the SI unit for energy as defined in the physical sciences.

Spectral energy density

Seven Year Itch (Collective Soul album)

On September 18, 2001, Collective Soul released their greatest hits compilation Seven Year Itch: Greatest Hits, 1994-2001 (stylized as 7even Year Itch). The compilation includes songs recorded from 1994 to 2001 and included two new tracks; "Next Homecoming" and "Energy". Seven Year Itch received decent reviews and was relatively successful It sold 225,000 copies in the first year after its release and reached number fifty on the Billboard 200; in Canada, it reached number nine on its albums chart and went platinum. All the songs in Seven Year Itch had charted in the US on the Billboard Hot 100, Mainstream Rock Tracks, or the Modern Rock Tracks chart, except for "Energy", which debuted in this compilation.

The compilation has sold over 500,000 copies. It saw a resurgence in sales after Collective Soul began putting out albums on their own independent label, El Music Group, beginning in 2004.

Seven Year Itch was the last album Collective Soul released through Atlantic Records and their last album to feature guitarist Ross Childress, who had been with the band since its 1993/1994 debut.

Energy (Drake song)

"Energy" is the second single by Canadian rapper Drake from his fourth commercial release If You're Reading This It's Too Late.

Composition

"Energy" contains samples from Eazy-Duz-It performed by Eazy-E and Ridin Spiners performed by Three 6 Mafia. Energy was produced by Boi-1da and OB O'Brien. According to WhoSampled the song samples the score of an episode of The O.C..

Critical reception

"Energy" received acclaim from music critics with many calling it the best song of the album. Ryan Dombal of Pitchfork gave the song a positive review and named it "Best New Track", stating "The song isn't aimed to any rappers or pop stars, not Kendrick Lamar, Big Sean or Tyga, but the song lines are dangerous."

Music video

Release

The video of "Energy" was released on Apple Music and users with iTunes and registered Apple Music account can watch this video.

Synopsis

Compound (migrant labour)

A migrant worker compound is a key institution in a system such as that which regulated labour on mines in South Africa from the later nineteenth century. The tightly controlled closed compound which came to typify the phenomenon in that country originated on the diamond mines of Kimberley from about 1885 and was later replicated on the gold mines. This labour arrangement, regulating the flow of male workers from rural homes in Bantustans or Homelands to the mines and jobs in urban settings generally, became one of the major cogs in the apartheid state. The single-sex hostels that became flash points for unrest in the last years of apartheid were a later form of compound.

Compounds at Kimberley

An earlier form of compound developed in South Africa in response to copper mining in Namaqualand in the 1850s. However, the systems of control associated with labour compounds became more organized in the context of diamond mining at what became Kimberley from the early 1870s.

Compound chocolate

Compound chocolate is a product made from a combination of cocoa, vegetable fat, and sweeteners. It is used as a lower-cost alternative to true chocolate, as it uses less-expensive hard vegetable fats such as coconut oil or palm kernel oil in place of the more expensive cocoa butter. It may also be known as 'compound coating' or 'chocolatey coating' when used as a coating for candy.

Often used in lower-grade candy bars, compound chocolate is designed to simulate enrobed chocolate on a product.

Cocoa butter must be tempered to maintain gloss and coating. A baker tempers chocolate by cooling the chocolate mass below its setting point, then rewarming the chocolate to between 31 and 32 °C (88 and 90 °F) for milk chocolate, or between 32 and 33 °C (90 and 91 °F) for semi-sweet chocolate. Compound coatings, however, do not need to be tempered. Instead, they are simply warmed to between 3 and 5 °C (5.4 and 9.0 °F) above the coating's melting point.

See also

Compound (fortification)

In military science, a compound is a type of fortification made up of walls or fences surrounding several buildings in the center of a large piece of land. The walls can either serve the purpose of being tall, thick, and impenetrable, in which case they would be made of wood, stone, or some other like substance; or dangerous to attempt to scale, in which case they could be made of barbed wire or electrified. Compounds can be designed to double as living spaces and military structures in the middle of hostile territory or as a military area within a country's territory; they are also used by the extremely wealthy, powerful, paranoid or criminal to protect against threats to themselves or their property.

A number of survivalists own fortified compound-like structures as a means of protection in case civilization breaks down or their government becomes abusive.

The term compound is also used to refer to an unfortified enclosure, especially in Africa and Asia. See compound (enclosure).