ramp up（v.）
"to increase or boost," 1968, originally in technical jargon; from ramp (n.) in the sense of "a slope or incline."
Thus for correlation and analysis, it is more accurate to approximate the reactivity increase by a linear rise (ramp) than by an instantaneous increase (step); then the power behavior depends on the rate of rise (ramp rate) and on the initial power. Data from kinetic experiments would be represented by a plot in three dimensions of peak power versus ramp rate and initial power. This can be represented on paper by a plot of lines of constant peak power on a graph having ramp rate and initial power as ab[s]cissa and ordinate. [V.K. Paré and S. Visner, "Experimental Program for HRE at High Power: Part II, " 1953]
The opposite ramp down is attested by 1984.
该词起源时间：1968年