  Local density fluctuations near the QCD critical point can be probed by an
intermittency analysis of power-law behavior on scaled factorial moments in
relativistic heavy-ion collisions. We study the second-order scaled factorial
moment in Au + Au collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7-200 GeV from the
UrQMD model. Since the background subtraction and efficiency correction are two
important aspects in this measurement, we propose a cumulative variable method
to remove background contribution and a cell-by-cell method for efficiency
correction in the intermittency analysis.
