Fig. 5. (a) Loading values of 20 companies in the 1st principal component (PC1) and contribution ratios of different sources in the critical companies in PC1 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. 