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In signal processing, the energy Failed to parse (Missing texvc executable; please see math/README to configure.): E_s
of a continuous-time signal x(t) is defined as
- Failed to parse (Missing texvc executable; please see math/README to configure.): E_{s} \ \ = \ \ \langle x(t), x(t)\rangle \ \ = \int_{-\infty}^{\infty}{|x(t)|^2}dt
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:
- Failed to parse (Missing texvc executable; please see math/README to configure.): E = {E_s \over Z} = { 1 \over Z } \int_{-\infty}^{\infty}{|x(t)|^2}dt
- where Z represents the magnitude, in appropriate units of measure, of the load driven by the signal.
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 Failed to parse (Missing texvc executable; please see math/README to configure.): E_s
would appear as volt2-seconds, which is not dimensionally correct for energy in the sense of the physical sciences. After dividing Failed to parse (Missing texvc executable; please see math/README to configure.): E_s 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 [link]
Similarly, the spectral energy density of signal x(t) is
- Failed to parse (Missing texvc executable; please see math/README to configure.): \ E_s(f) = |X(f)|^2
where X(f) is the Fourier transform of x(t).
For example, if x(t) represents the magnitude of the electric field component (in volts per meter) of an optical signal propagating through free space, then the dimensions of X(f) would become volt-seconds per meter and Failed to parse (Missing texvc executable; please see math/README to configure.): E_s(f)
would represent the signal's spectral energy density (in volts2-second2 per meter2) as a function of frequency f (in hertz). Again, these units of measure are not dimensionally correct in the true sense of energy density as defined in physics. Dividing Failed to parse (Missing texvc executable; please see math/README to configure.): E_s(f) by Zo, the characteristic impedance of free space (in ohms), the dimensions become joule-seconds per meter2 or, equivalently, joules per meter2 per hertz, which is dimensionally correct in SI units for spectral energy density.
Parseval's Theorem [link]
As a consequence of Parseval's theorem, one can prove that the signal energy is always equal to the summation across all frequency components of the signal's spectral energy density.
See also [link]
https://wn.com/Energy_(signal_processing)
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
Energy (Melissa Manchester song)
"Energy" is a song performed by American singer Melissa Manchester, from her 1985 album Mathematics.
Details
The song was arranged by veteran songwriter Greg Mathieson and was released as the second single from the album, following the underperformance of the lead single "Mathematics", MCA hoped to reverse the album's fortune by releasing this Hi-NRG track with an aim for the club market.
Melissa Manchester filmed a videoclip to promote the song, which sees the singer and her band in a sort of industrial-setting stage performing the song.
The single was released on 7" and 12" formats featuring remixes, but it failed to chart either on the Billboard Hot 100 or the dance charts, and failed to chart elsewhere. The b-side to the single was a non-album song, called "So Full Of Yourself", which was co-written by Manchester and Tom Snow and used as the b-side to all 3 singles off the album.
Track listings
Thor (comics)
Thor, the god of Norse mythology, has appeared as a character in various comics over the years, appearing in series from a range of publishers.
Marvel Comics
Thor (often called The Mighty Thor) is a Marvel Comics superhero, based on the thunder god of Norse mythology. The superhero was created by editor Stan Lee and penciller Jack Kirby, who co-plotted, and scripter Larry Lieber, and first appeared in Journey into Mystery #83 (Aug. 1962).
On a mission from his father, Odin, Thor acts as a superhero while maintaining the secret identity of Dr. Donald Blake, an American physician with a partially disabled leg. Blake can transform by tapping his walking stick on the ground; the cane becomes the magical hammer Mjolnir and Blake transforms into Thor.
Thor, a founding member of the superhero group the Avengers, often battles his evil adoptive brother Loki, a Marvel character adapted from the Norse god of mischief. He is among Marvel's most powerful superheroes. Many recurring characters in his stories are based on Norse Mythology. Apart from this main superhero, Marvel features a number of characters based on him.
Jane Foster (comics)
Jane Foster is a fictional character appearing in American comic books published by Marvel Comics. The character is usually depicted as a supporting character of the superhero Thor. Created by writers Stan Lee and Larry Lieber, and artist Jack Kirby, the character first appeared in Journey into Mystery #84 (Sept. 1962). For many years, Foster was a nurse employed by Dr. Donald Blake, Thor's first mortal host, before becoming a doctor herself. In 2015, Foster was revealed to be deemed worthy to wield Thor's hammer Mjolnir when the former is no longer able, adopting the name of Thor, the "Goddess of Thunder", and joining the Avengers.
Jane Foster has also appeared in various media adaptations of Thor, including the 2011 feature film Thor, and its 2013 sequel Thor: The Dark World, in which she is portrayed by Natalie Portman.
Publication history
Jane Foster first appeared in Journey into Mystery #84 (Sept. 1962), and was created by plotter Stan Lee, scripter Larry Lieber and penciler Jack Kirby. Named "Jane Nelson" in her first two appearances, she went on to appear as the love interest of Dr. Donald Blake, the secret identity of the Norse god superhero Thor, in nearly every issue through #136 (Jan. 1967) of the title, by then renamed Thor.
Thor (motorcycles)
Thor was an American manufacturer of motorcycles, founded in 1901 in Aurora, Illinois.
