(September 2014). A general sales agent (GSA) is a sales representative for an airline in a specific country or region. Typically, the GSA is responsible for selling all products of the airline in its region which includes flight tickets and cargo space. A GSA will typically sell the product of more than one airline.
Definition of standing wave. : a single-frequency mode of vibration of a body or physical system in which the amplitude varies from place to place, is constantly zero at fixed points, and has maxima at other points.
The standing waves associated with resonance in air columns have been discussed mainly in terms of the displacement of air in the columns. They can also be visualized in terms of the pressure variations in the column. A node for displacement is always an antinode for pressure and vice versa, as illustrated below.