different between switchhub vs concentrator

English

concentrate +? -or

concentrator (plural concentrators)

One who concentrates.
- 1960, Dissertation Abstracts (volume 20, page 4007)
  Experienced classroom teachers are well acquainted with the attention-seeker, the shy girl, the aggressive boy, the poor concentrator, the slow student […]
(telecommunications) A hub.
(mining) An apparatus for the separation of dry comminuted ore, by exposing it to intermittent puffs of air.
(Can we find and add a quotation of Knight to this entry?)
(firearms) A frame or ring of wire or hard paper fitting into the cartridge case used in some shotguns, and holding the shot together when discharged, to secure close shooting; also, a device for slightly narrowing the bore at the muzzle for the same purpose.

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