Photo of Tim DeFries

Tim DeFries

Principal Scientist

Every day is a beautiful day. And if I learn something new—whether it’s about machine learning, vehicle aerodynamics, signal processing, infrared spectroscopy, or how helpful my buddies are—that day is even more beautiful.

Tim DeFries uses chemistry, physics, and engineering principles to solve problems for commercial clients, government agencies, and trade organizations. When the data needed to answer research questions are not available, he designs and leads field efforts to get the required data for his analysis. His interests include atmospheric ozone formation; diesel fuel ignition quality; vehicle driving and engine operating behavior; and vehicle, refinery, and power plant emissions. Most recently, he has found a method for measuring on-road vehicle exhaust and evaporative emission rates using internal data routinely discarded by current remote-sensing instruments.

Coming from a long line of machinists, Tim is a hands-on guy. Starting in high school, he worked on a variety of vehicles and has rebuilt engines. For his doctoral thesis, he designed the pressure vessels he needed to investigate how extreme pressures up to 150,000 pounds per square inch and temperatures up to 800 degrees Celsius affect the molecular motions of liquid water. He holds a B.S. in chemistry from Purdue University and a Ph.D. in physical chemistry from the University of Illinois Urbana-Champaign. Tim plays euphonium in the Austin Symphonic Band. He has commissioned a suite for concert band based on the four Laws of Thermodynamics.