Industrial Heating, Jun. 2014. (Free registration required to view full-text.)
http://www.industrialheating.com/articles/91705-increasing-efficiency-with-advanced-controls?v=preview

"The ever-increasing need to produce higher-quality parts with lower costs requires newer tools to reduce waste and optimize processes. By using advanced gas-handling systems, heat treaters can reduce waste and get a handle on each furnaces gas consumption. Using process modeling for carburizing, nitriding, and carbonitriding can help users develop more efficient processes."