Energy (journal)

Energy is a peer-reviewed academic journal covering research on energy engineering that was established in 1976. It is published by Elsevier and the editor-in-chief is Henrik Lund (Aalborg University). According to the Journal Citation Reports, the journal has a 2013 impact factor of 4.159, ranking it 13th out of 83 journals in the category "Energy & Fuels" and second out of 55 journals in "Thermodynamics".

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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.

South Africa

South Africa, officially the Republic of South Africa, is the southernmost sovereign state in Africa. It is bounded on the south by 2,798 kilometers of coastline of southern Africa stretching along the South Atlantic and Indian Oceans, on the north by the neighbouring countries of Namibia, Botswana and Zimbabwe, and on the east by Mozambique and Swaziland, and surrounding the kingdom of Lesotho. South Africa is the 25th-largest country in the world by land area, and with close to 53 million people, is the world's 24th-most populous nation. It is the southernmost country on the mainland of the Old World or the Eastern Hemisphere.

South Africa is a multiethnic society encompassing a wide variety of cultures, languages, and religions. Its pluralistic makeup is reflected in the constitution's recognition of 11 official languages, which is among the highest number of any country in the world. Two of these languages are of European origin: Afrikaans developed from Dutch and serves as the first language of most white and coloured South Africans; English reflects the legacy of British colonialism, and is commonly used in public and commercial life, though it is fourth-ranked as a spoken first language.