#ontheblog: "As a process #engineer in industry, I used first-principles models (also called mechanistic, phenomenological and engineers’ models) to support both process design and online analysis. They embody the functional relations between process variables and may have a few coefficients (like tray efficiency, reactivity, or friction factors) whose values could be adjusted to match process operating data. I found them very functional." This is something that Dr. R. Russell Rhinehart explains