“…1 In the paper 'Approximate dynamic programming solution for the optimal nitrogen oxides/particulate matter trade-off control of a WAPS engine', a data-driven approximate dynamic programming controller is developed to achieve optimal trade-off between nitrogen oxides and particulate matter emission for a unique 4JB1-Tweifu accumulator pump system (WAPS) engine. 2 In the paper 'Experimental investigation of emission characteristics based on new alcohol-based gasoline fuel', emission characteristics of a new type alcohol-based fuel are investigated in a CA4G5 engine. 3 The gear system is of great importance to transmission and powertrain systems, and two papers in this area are selected in this Special Collection.…”