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单词 sector
释义
sector

Mathematics
  • A sector of a circle, with centre O, is the region bounded by an arc AB of the circle and the two radii OA and OB. The area of a sector is equal to 12r2θ, where r is the radius and θ‎ is the angle in radians.


Computer
  • A subdivision of a track on a magnetic disk that represents the smallest portion of data that can be modified by overwriting. Each sector has a unique address, which contains the location of the track and the sector number. In order to read an address or data the drive decoding electronics must be synchronized to the data stream. To achieve this a special pattern, the preamble, is written. Following the preamble comes the address mark or data mark as appropriate.

    A disk may be soft-sectored or hard-sectored. In soft-sectoring, the size and position of the sectors is determined by the control electronics and software: disk drives generate an index signal once per revolution of the disk, and when this is received from the drive unit all the sectors of a track are written in one continuous operation. On a hard-sectored disk, the start of each sector is related to a sector signal generated by the disk drive and is positively related to the position of the disk. Hard-sectoring can achieve higher packing of sectors since it is not necessary to have large intersector gaps to accommodate speed variations.


Electronics and Electrical Engineering
  • A division of a hard disk or other digital storage medium that holds a fixed number of bits, typically equivalent to 512 bytes. Data to be stored is broken into chunks that fit within a single sector, which also contains information about how the chunks should be linked, as well as error-correcting codes. The choice of sector size is a trade-off between data access speeds and wastage from left-over portions of sectors.


Economics
  • A part of the economy. Sectors can be delimited in a number of different ways. One way is by the bodies organizing expenditures: thus the economy is divided between the public sector, that is, the government at various levels and government-controlled bodies; the corporate sector, which is companies; and the personal sector, which is individuals, and unincorporated businesses. For national income accounting purposes the rest of the world is sometimes regarded as a sector. Sectors may also be distinguished by the type of product: a primary sector, that is, agriculture and mining; a secondary, or manufacturing, sector; and a tertiary, or services, sector. See also industrial sector; organized sector; sensitive sectors.


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