The new article by Amir Akbari and Paul I. Barton, Integrating Genome-Scale and Superstructure Optimization Models in Techno-Economic Studies of Biorefineries, has been selected as the cover story for the journal Processes 2019, 7(5). The article is open-access and can be viewed here. Abstract: Genome-scale models have become indispensable tools for the study of cellular growth. These…

Suzane Cavalcanti, a current Ph.D. student at PSEL, has been nominated an ExxonMobil-MIT Energy Fellow for the 2019-2020 academic year. In this time period, her research will be funded by ExxonMobil, a member company of the MIT Energy Initiative (MITEI).  The Society of Energy Fellows was established to help MIT address the world’s energy challenges…

In Simulation of Dual Mixed Refrigerant Natural Gas Liquefaction Processes Using a Nonsmooth Framework (click here for free access), a nonsmooth, multistream heat exchanger model is used to develop a simulation tool for two different dual mixed refrigerant processes. Natural gas liquefaction is an energy intensive process where the feed is cooled from ambient temperature down…

Applying the method of moments to the chemical master equation appearing in stochastic chemical kinetics often leads to the so-called closure problem. Recently, several authors showed that this problem can be partially overcome using moment-based semidefinite programs (SDPs). In particular, they showed that moment-based SDPs can be used to calculate rigorous bounds on various descriptions…

Stochastic programming with recourse usually assumes uncertainty to be exogenous. Decision-dependent probabilities in stochastic programs with recourse (click here for free access) presents modelling and application of decision-dependent uncertainty in mathematical programming including a taxonomy of stochastic programming recourse models with decision-dependent uncertainty. The work includes several ways of incorporating direct or indirect manipulation of underlying probability…

For the performance of global optimization algorithms, the rate of convergence of convex relaxations to the objective and constraint functions is critical. Convergence-order analysis for differential-inequalities-based bounds and relaxations of the solutions of ODEs (click here for free access) extends results from Bompadre and Mitsos (J Glob Optim 52(1):1–28, 2012) to characterize the convergence rate of parametric…

Nonsmooth Differential-Algebraic Equations in Chemical Engineering (click here for 50 days of free access) advocates a nonsmooth differential-algebraic equations (DAEs) modeling paradigm for dynamic simulation and optimization of process operations. A variety of systems encountered in chemical engineering are traditionally viewed as exhibiting hybrid continuous and discrete behavior. In many cases such discrete behavior is…

Prof. Matthew Stuber of the University of Connecticut, a PSEL alumnus, has won the 2018 W. David Smith, Jr. Graduate Publication Award from AIChE’s CAST Division for the paper Convex and Concave Relaxations of Implicit Functions, co-authored with Joseph Scott and Paul Barton. See here for details on the award. Congratulations! 

Garrett Dowdy, currently a PhD candidate at PSEL, has won a PSE 2018 Young Researcher Award. The award supports Garrett's participation in the PSE 2018 conference, to be held in San Diego, July 1-5 2018. Congratulations, Garrett!

Lexicographic linear programs are fixed-priority multiobjective linear programs that are a useful model of biological systems using flux balance analysis and for goal-programming problems. The objective function values of a lexicographic linear program as a function of its right-hand side are nonsmooth. Generalized Derivatives of Lexicographic Linear Programs (click here for free access) derives generalized derivative…