Provided are a display apparatus and a method of operating the display apparatus that generate data signals that compensate for a deviation of a first power supply voltage output from a direct current -DC converter. Generally a proppant, delayed gel breaker and other modifiers are added to the gelled hydrocarbon to improve the oil recovery process. In another aspect, lateral edges of the upper and lower surfaces are also defined by convex arcs extending from a center point offset from the spacer midpoint.