Plating on the roof emits a psuedo-gravitational field that is attracted to the plates on the floor pushing everything on the ship 'down'. This creates the false sense of gravity that permeates the ship.
This technology is used on many of Geshrinari Shipyards. Qel'noran Shipyards, and Abwehran Imperial Yards designs. Though designed by two different corporations on opposite sides of known space, there is not much difference between the two designs. Abwehran Imperial Yards uses this type of plating sandwiched within their dual-layer hull in order to create an inertial dampening effect, basically creating a zone where a ship's inertia is warped to protect the crew inside. Abwehran Imperial Yards also uses the Unidirectional Gravity Plating in a military application by lining the outside of missile tubes with them to physically launch missiles out of their tubes using gravitational fields.