Dr. Mueller is a Distinguished Member of the Technical Staff in the Applied Combustion Research Department at Sandia National Laboratories’ Combustion Research Facility in Livermore, California, USA. He has been working at Sandia since receiving his Ph.D. degree in Aerospace Engineering from the University of Michigan in 1996. His research group uses optical and conventional diagnostics to better understand the processes occurring within modern mixing-controlled compression-ignition engines, and how they are affected by fuel changes. He is an SAE Fellow and serves as an associate editor of the SAE International Journal of Fuels and Lubricants.