Hydrogen (disambiguation)

Hydrogen is a chemical element.

Hydrogen may also refer to:

See also

Hydrogen vehicle

A hydrogen vehicle is a vehicle that uses hydrogen as its onboard fuel for motive power. Hydrogen vehicles include hydrogen fueled space rockets, as well as automobiles and other transportation vehicles. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy either by burning hydrogen in an internal combustion engine, or by reacting hydrogen with oxygen in a fuel cell to run electric motors. Widespread use of hydrogen for fueling transportation is a key element of a proposed hydrogen economy.

Hydrogen fuel does not occur naturally on Earth and thus is not an energy source; rather it is an energy carrier. As of 2014, 95% of hydrogen is made from methane. It can be produced using renewable sources, but that is an expensive process. Integrated wind-to-hydrogen (power to gas) plants, using electrolysis of water, are exploring technologies to deliver costs low enough, and quantities great enough, to compete with traditional energy sources.

Isotopes of hydrogen

Hydrogen (H) (relative atomic mass: 1.00794) has three naturally occurring isotopes, sometimes denoted ¹H, ²H, and ³H. The first two of these are stable while ³H has a half-life of 12.32 years. All heavier isotopes are synthetic and have a half-life less than one zeptosecond (10⁻²¹ second). Of these, ⁵H is the most stable, and ⁷H is the least.

Hydrogen is the only element whose isotopes have different names that are in common use today. The ²H (or hydrogen-2) isotope is usually called deuterium, while the ³H (or hydrogen-3) isotope is usually called tritium. The symbols D and T (instead of ²H and ³H) are sometimes used for deuterium and tritium. The IUPAC states in the 2005 Red Book that while the use of D and T is common, it is not preferred because it can cause problems in the alphabetic sorting of chemical formulae. The ordinary isotope of hydrogen, with no neutrons, is sometimes called "protium". (During the early study of radioactivity, some other heavy radioactive isotopes were given names, but such names are rarely used today.)

Solar (room)

The solar was a room in many English and French medieval manor houses, great houses and castles, generally situated on an upper storey, designed as the family's private living and sleeping quarters. In such houses, the main ground-floor room was known as the Great Hall, in which all members of the household, including tenants, employees and servants, would eat. Those of highest status would be at the end, often on a raised dais, and those of lesser status further down the hall. But a need was felt for more privacy to be enjoyed by the head of the household, and, especially, by the senior women of the household. The solar was a room for their particular benefit, in which they could be alone and away from the hustle, bustle, noise and smells (including cooking smells) of the Great Hall.

The solar was generally smaller than the Great Hall, because it was not expected to accommodate so many people, but it was a room of comfort and status, and usually included a fireplace and often decorative woodwork or tapestries/wall hangings.

Solar (Taeyang album)

Solar is the first full-length solo album by Korean singer Taeyang, member of Big Bang. The album was released in two forms: the "Regular Edition" and the "Deluxe Edition" which is limited to 30,000 copies worldwide. The lead-single was "I Need a Girl" featuring his bandmate G-Dragon. On July 9, 2010, Taeyang's solo album Solar hit second place on iTunes' Top R&B-Soul albums chart in the United States and first place in Canada, the first time for an Asian musician. In Solar, Taeyang put much effort into enhancing his vocal skills as well as his composing, co-writing as many as four songs ("Solar", "Where U At", "Wedding Dress", and "Take It Slow") and writing lyrics for "Take It Slow".

Taeyang's first international album, Solar International, is the first ever K-Pop music release to be sold worldwide on iTunes as both an audio and video album. The audio version (complete with a digital booklet) hit iTunes stores on August 19, 2010, while the video version (bundled with bonus, behind the scenes documentaries) arrived by September 10, 2010. The audio album combines both English and Korean hits from his past and present albums including "I'll Be There", "Connection" (feat. BIG TONE), "Wedding Dress" and "I Need a Girl (feat. G-Dragon)". On August 26, 2010, Solar's International album made it to fifth place on iTunes' Top R&B-Soul albums chart in the United States and Japan, and third place in Canada.

Solar (composition)

"Solar" (/ˈsoʊlər/ or /soʊˈlɑːr/) is a musical composition attributed to Miles Davis on the studio album Walkin' (1954), considered a modern jazz standard. The tune has been played and recorded by many musicians including his former bandmates/collaborators Lee Konitz, Bill Evans, Dave Holland, Keith Jarrett or Jack DeJohnette. A controversy exists over authorship of this composition and one current consensus holds that Davis' "Solar" is essentially an earlier song, "Sonny", written by Chuck Wayne.

The first two measures of this song adorn Miles Davis' tombstone in Woodlawn Cemetery.

Chord structure

Solar is considered a blues by most listeners, and the commonly accepted chord structure for this piece is:

Recordings

General officer

A general officer is an officer of high rank in the army, and in some nations' air forces or marines.

The term "general" is used in two ways: as the generic title for all grades of general officer and as a specific rank. It originates in the 16th century, as a shortening of captain general, which rank was taken from Middle French capitaine général. The adjective general had been affixed to officer designations since the late medieval period to indicate relative superiority or an extended jurisdiction.

Today, the title of "General" is known in some countries as a four-star rank. However different countries use different systems of stars for senior ranks. It has a NATO code of OF-9 and is the highest rank currently in use in a number of armies.

General officer ranks

The various grades of general officer are at the top of the military rank structure. Lower-ranking officers in land-centric military forces are typically known as field officers or field-grade officers, and below them are company-grade officers.