April 15, 2021
- Daniel A. Hickman (PhD ChE '92), Senior R&D Fellow in the Engineering and Process Science department of Dow’s Core Research & Development organization, was the featured guest speaker for the 8th annual Amundson Lecture on April 15, 2021.
He received his B.S. in chemical engineering from Iowa State University (1988) and his Ph.D. in chemical engineering from the University of Minnesota (1992) in the field of short contact time catalytic monolith reactors. In his 28 years with Dow, Hickman has served as a subject matter expert and technical leader in reaction engineering and process development for numerous reaction systems across a variety of Dow businesses and technologies. As a reaction engineering expert, his experience includes working with stirred tank reactors, fixed bed reactors, trickle bed reactors, and fluidized bed reactors. His contributions at Dow include the conceptual design of new reactor systems for three commercial processes and the development of training and resources that facilitate efficient and reliable reactor scale-up from the laboratory. Hickman began his career at Dow in 1992 on the Research Assignments Program. In 1993, he joined the Central Research & Development Engineering lab, the precursor to his current organization.
Hickman holds 23 U.S. patents and is an author of 26 journal articles and book chapters and more than 200 internal Dow reports. He was named the Mid-Michigan AIChE Chemical Engineer of the Year in 2014, received the CRE Practice Award from the Catalysis and Reaction Engineering Division of AIChE in 2015, and currently serves the global reaction engineering community as the president of the board of directors for ISCRE.
His lecture, "Nonlinear Mixed-Effects Models for Parameter Estimation" was presented in the context of Neal Amundson's legacy in the field of reaction engineering. Hickman indicated that, when asked about his standards for hiring during an interview in 1995, Amundson said that he sought candidates who did “not use the alibi ‘this is good enough for engineering.’ The general point was it had to be right.” Amundson transformed the field of chemical engineering, especially chemical reaction engineering, by the application of mathematics, initiating what some have called “the second revolution in chemical engineering.” Hickman's lecture argued that we have not completed this revolution, in at least one category of problems, we have failed to properly apply mathematics.
Furthermore, Hickman's lecture explained that reaction kinetic data are frequently obtained from batch experiments, where quantities such as species concentrations are measured at various times during the batch, resulting in time series data. Investigators then fit kinetic parameters to multiple sets of these time series data, often with the use of nonlinear least squares procedures. However, the application of standard least squares methods implicitly assumes that each individual measurement is statistically independent. Using experimental data obtained with a batch recycle reactor, this lecture will demonstrate that assumptions of independent, normally distributed errors for longitudinal measurements from multiple batch experiments yield estimates that provide statistically inferior explanations of the observed data relative to models that incorporate batch-to-batch variation. To circumvent analogous difficulties outside of the fields of chemical reaction engineering and chemical kinetics, numerous investigators have applied nonlinear mixed-effects models. Mixed-effects models for batch reactor longitudinal experiments offer a better explanation of the observed data by reducing or eliminating bias in the estimated parameters and providing confidence intervals that are more realistic. To echo Amundson, “This is the way you do the problem right.”
Hickman (pictured) is shown with the Amundson Lecture medal. The annual Amundson Lecture features a guest speaker that embodies the tenets of Professor Neal R. Amundson in scholarship and innovation in the fields of chemical engineering and materials science. Amundson, department head from 1949-1974, was a visionary leader who pioneered the application of mathematics in chemical engineering.