Fig. 7. (a) Loading values of 20 companies in the 3rd principal component (PC3) and contribution ratios of different sources in the critical companies in PC3 in (b) 2012, (c) 2013, and (d) 2014. EC, L/UL, WWTP, OLS, and CT denote equipment component, loading/unloading, wastewater treatment plant, oil-water separator, and cooling tower, respectively. 