In flux balance analysis of metabolic networks, reaction rates and optimal pathways are ascertained by solving a linear program, in which the growth rate is maximized subject to mass-balance constraints, and for which extracellular conditions represent parameters. However, for most large, genome-scale metabolic networks of practical interest, the resulting parametric problem has multiple and highly degenerate optimal solutions,…

In Optimization of single mixed-refrigerant natural gas liquefaction processes described by nondifferentiable models (click here for 50 days of free access), a new strategy for the optimization of natural gas liquefaction processes is presented, in which flowsheets formulated using nondifferentiable process models are efficiently and robustly optimized using an interior-point algorithm. The constraints in the optimization formulation…

In this article series, Optimal Campaigns in End-to-End Continuous Pharmaceuticals Manufacturing, the authors investigate the optimal dynamic operation of a continuous process that includes several reaction and separation steps to produce an active pharmaceutical ingredient at final dosage from advanced intermediates, inspired by a pilot plant previously tested at MIT. Part 1: Nonsmooth Dynamic Modeling (click here…

Generalized Sensitivity Analysis of Nonlinear Programs (click here for full text) extends classical sensitivity results for nonlinear programs to cases in which parametric perturbations cause changes in the active set. This is accomplished using lexicographic directional derivatives, a recently developed tool in nonsmooth analysis based on Nesterov's lexicographic differentiation. A nonsmooth implicit function theorem is…

In Bounds on stochastic chemical kinetic systems at steady state (click here for 30 days of free access), the method of moments has been proposed as a potential means to reduce the dimensionality of the chemical master equation (CME) appearing in stochastic chemical kinetics. However, attempts to apply the method of moments to the CME usually result in…

In Optimal campaigns in end-to-end continuous pharmaceuticals manufacturing. Part 2: Dynamic optimization (click here for 50 days of free access), the authors investigate theoretical optimal campaigns in a continuous process of pharmaceuticals production. The simulated process, inspired by a pilot plant previously tested at MIT, includes several reaction and separation steps to produce final tablets. This paper…

In Optimal shale oil and gas investments in the United States (click here for free access), the authors present a comprehensive supply chain optimization model to determine optimal shale oil and gas infrastructure investments in the United States. The model encompasses multiple shale plays, commodities, plant locations, conversion technologies, transportation modes and both local and foreign markets. The…

How to solve a design centering problem (click here for free access) considers the problem of design centering. Geometrically, this can be thought of as inscribing one shape in another. Theoretical approaches and reformulations from the literature are reviewed; many of these are inspired by the literature on generalized semi-infinite programming, a generalization of design centering.…

Michael Patrascu, currently a postdoctoral associate in PSEL, has won the EFCE Excellence Award in Process Intensification 2017 for his PhD dissertation. The award will be presented on Monday, 2 October 2017, 8:30 – 10:00 h, at the Award Ceremony of the 10th World Congress of Chemical Engineering – WCCE10, Barcelona, Spain. Congratulations, Michael!  

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…