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
Reduction
Reduction, reduced, or reduce may refer to:
Science
Chemistry
- Organic redox reaction, a redox reaction that takes place with organic compounds
- Reduced gas, a gas with a low oxidation number
- Reducing agent, element or compound in a redox reaction that donates an electron to another species
- Reducing atmosphere, an oxygen-poor gaseous environment that inhibits oxidation
- Reductase, an enzyme that catalyzes a reduction reaction
- Reduction potential, a measure of the tendency of a chemical species to acquire electrons
- Ore reduction: see smelting
Reduction (complexity)
In computability theory and computational complexity theory, a reduction is an algorithm for transforming one problem into another problem. A reduction from one problem to another may be used to show that the second problem is at least as difficult as the first.
Intuitively, problem A is reducible to problem B if an algorithm for solving problem B efficiently (if it existed) could also be used as a subroutine to solve problem A efficiently. When this is true, solving A cannot be harder than solving B. "Harder" means having a higher estimate of the required computational resources in a given context (e.g., higher time complexity, etc.).
We write A ≤m B, usually with a subscript on the ≤ to indicate the type of reduction being used (m : mapping reduction, p : polynomial reduction).
The mathematical structure generated on a set of problems by the reductions of a particular type generally forms a preorder, whose equivalence classes may be used to define degrees of unsolvability and complexity classes.
Redox
Redox is a contraction of the name for chemical reduction-oxidation reaction. A reduction reaction always occurs with an oxidation reaction. Redox reactions include all chemical reactions in which atoms have their oxidation state changed; in general, redox reactions involve the transfer of electrons between chemical species. The chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. Oxygen is not necessarily included in such reactions as other chemical species can serve the same function.
The term "redox" comes from two concepts involved with electron transfer: reduction and oxidation. It can be explained in simple terms:
Although oxidation reactions are commonly associated with the formation of oxides from oxygen molecules, these are only specific examples of a more general concept of reactions involving electron transfer.
