“head”的概念、定义、翻译、参考文献-科学参考

head

Chemical Engineering

The pressure of a liquid expressed as the equivalent height that a column of the liquid would exert. The head is related to pressure, p, density, ρ, and gravitational acceleration, g, as:
$h = \frac{p}{ρ g}$

See hydrostatic head.

Computer

1. The part of a peripheral mechanism that is in contact with the medium or very close to it and that is directly responsible for writing data or patterns onto the medium or for reading or erasing them. The word is most frequently used of a magnetic head in a disk drive or tape transport (see magnetic tape), an optical head in an optical storage device, or a print head in a printer. See also read/write head.
2. (head-end) One end of a transmission medium. The head has some form of control over the contents of the medium and of access to it. See also broadband coaxial systems.
3. (header) The part of a cell or packet that contains routing and control information used to control the passage of the cell or packet across a packet switching network. See also cell relay, frame relay.
4. The first item in a list.

Electronics and Electrical Engineering

A device that records signals on a suitable medium or reads or erases signals already stored on the medium, examples of such media being magnetic tape and magnetic disk. See also magnetic recording.

Geology and Earth Sciences

1. In certain areas of Britain, the name given to a sheet of poorly sorted, angular rock debris, mantling a hillslope and deposited by gelifluction. Similar material is commonly found as a fossil deposit in the extraglacial areas of N. America and Europe. Coombe rock is similar, but is found on chalk.
2. See bernoulli equation; darcy’s law; elevation potential energy; hydraulic head; pressure head.

单词	head
释义	head Chemical Engineering The pressure of a liquid expressed as the equivalent height that a column of the liquid would exert. The head is related to pressure, p, density, ρ, and gravitational acceleration, g, as: $h = \frac{p}{ρ g}$ See hydrostatic head. Computer 1. The part of a peripheral mechanism that is in contact with the medium or very close to it and that is directly responsible for writing data or patterns onto the medium or for reading or erasing them. The word is most frequently used of a magnetic head in a disk drive or tape transport (see magnetic tape), an optical head in an optical storage device, or a print head in a printer. See also read/write head. 2. (head-end) One end of a transmission medium. The head has some form of control over the contents of the medium and of access to it. See also broadband coaxial systems. 3. (header) The part of a cell or packet that contains routing and control information used to control the passage of the cell or packet across a packet switching network. See also cell relay, frame relay. 4. The first item in a list. Electronics and Electrical Engineering A device that records signals on a suitable medium or reads or erases signals already stored on the medium, examples of such media being magnetic tape and magnetic disk. See also magnetic recording. Geology and Earth Sciences 1. In certain areas of Britain, the name given to a sheet of poorly sorted, angular rock debris, mantling a hillslope and deposited by gelifluction. Similar material is commonly found as a fossil deposit in the extraglacial areas of N. America and Europe. Coombe rock is similar, but is found on chalk. 2. See bernoulli equation; darcy’s law; elevation potential energy; hydraulic head; pressure head.
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