NOx emission control in a bio-diesel engine: Pre and post-combustion techniques using engine valve timing (EVT) and electrical discharge plasma (EDP) investigation and Analysis of NOx emission control of biodiesel engine using combined engine valve timing control and pulse discharge plasma (PDP) based exhaust control techniques. - A. D. Srinivasan; R. Rajagopala; N. Jagadisha; K. Chandrashekara (IAS, 2013)