Channel Queuing system: single-server systems are called single channel systems.
Multichannel Queuing System: systems with more servers are called multi-channel systems.
Single-phase system: electrical engineering, single-phase electric power refers to distribution of AC power through the system in which all power supply varies in unison. Single phase distribution is used when loads are mostly lighting and heating, with few large electric motors. THE single phase supply connected to an AC electric motor does not produce the rotating magnetic field, single-phase motors require additional circuits for starting, and engines are uncommon above 10 or 20 kW in rating.