In Dynamic flux balance modeling to increase the production of high-value compounds in green microalgae (click here for free access), the authors present a flexible modeling formulation for accumulation of high-value storage molecules in microalgae that provides quantitative predictions under various light and nutrient conditions. The modeling approach is based on dynamic flux balance analysis…

Amir Akbari, a current postdoctoral associate in PSEL, has been awarded an NSF-funded Travel Grant to attend the World Congress of Chemical Engineering/ESCAPE 2017.

In Using semidefinite programming to calculate bounds on particle size distributions, Garrett R. Dowdy and Paul I. Barton have described a method for computing bounds on various industrially-relevant descriptions of a particle size distribution – CDF, D10, and so forth – using only finitely many moments of the distribution as input. The paper is now available…

In Convergence-order analysis of branch-and-bound algorithms for constrained problems (click here), Rohit Kannan and Paul I. Barton investigate the convergence order of bounding schemes for deterministic global optimization algorithms. Specifically, this article proposes a definition of convergence order for lower bounding schemes for constrained problems, defines the convergence order of full-space relaxation-based and Lagrangian dual-based…

Garrett Dowdy, a current Ph.D. student in PSEL, has won Outstanding Seminar Award for presentation of the best third-year talk in the MIT ChemE Department in Fall 2016. Entitled "Rigorous Bounds on Distributions through Semidefinie Programming," Garrett described how semidefinite programming can be applied to problems of practical chemical engineering interest.

Garrett Dowdy, a current Ph.D. student in PSEL, has been named a keynote speaker at the upcoming European Symposium on Computer-Aided Process Engineering (ESCAPE). Co-authored with Paul Barton, his selected paper is titled "Using Semidefinite Programming to Calculate Bounds on Steady-State Distributions in Stochastic Chemical Kinetic Systems." The conference takes place October 1-5, 2017, in…

Dependable algorithms for nonideal vapor-liquid equilibrium calculations are essential for effective process design, simulation and optimization. Inside-out algorithms [Boston & Britt, 1978] for flash calculations serve as the basis for many of the algorithms used by process simulation software due to their robustness with respect to initialization and inexpensive computational cost. However, if the specified…

The well-posedness of nonsmooth semi-explicit differential-algebraic equations (DAEs) is investigated (click here; free access is provided until February 08, 2017). The nonsmooth DAEs are classified as having differential index one in a generalized sense. Existence of solutions is derived under consistency and regularity of the initial data. Uniqueness of a solution is guaranteed under analogous…

New journal articles on global optimization problems authored by current and former members of PSEL have now appeared online with free access: Differentiable McCormick relaxations in  Journal of Global Optimization (click here).  This article presents a continuously differentiable variant of McCormick’s original relaxations in the multivariate McCormick framework of Tsoukalas and Mitsos. Gradients of the new…

A new journal article on differential–algebraic equations (DAEs) by members of PSEL has now appeared in Journal of Optimization Theory and Applications with free access (click here). Nonsmooth equation-solving and optimization algorithms which require local sensitivity information are extended to systems with nonsmooth parametric DAEs embedded.  Using lexicographic differentiation, an auxiliary nonsmooth DAE system is obtained whose unique solution furnishes…