THE KAUST Repository is an initiative of the University Library to expand the impact of conference papers, technical reports, peer-reviewed articles, preprints, theses, images, data sets, and other research-related works of King Abdullah University of Science and Technology (KAUST).
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Expansion Planning for Renewable Integration in Power System of Regions with Very High Solar Irradiation(Journal of Modern Power Systems and Clean Energy, Journal of Modern Power Systems and Clean Energy, 2021-09-15) [Article]In this paper, we address the long-term generation and transmission expansion planning for power systems of regions with very high solar irradiation. We target the power systems that currently rely mainly on thermal generators and that aim to adopt high shares of renewable sources. We propose a stochastic programming model with expansion alternatives including transmission lines, solar power plants (photovoltaic and concentrated solar), wind farms, energy storage, and flexible combined cycle gas turbines. The model represents the longterm uncertainty to characterize the demand growth, and the short-term uncertainty to characterize daily solar, wind, and demand patterns. We use the Saudi Arabian power system to illustrate the functioning of the proposed model for several cases with different renewable integration targets. The results show that a strong dependence on solar power for high shares of renewable sources requires high generation capacity and storage to meet the night demand.
Influence of the anionic ligands on properties and reactivity of Hoveyda-Grubbs catalysts(Molecular Catalysis, Elsevier BV, 2021-06-26) [Article]Ruthenium based catalysts remain among the more successful complexes used in the catalysis of metathesis processes for the synthesis of new carbon-carbon bonds. The investigation of the influence of the different system moieties on its catalytic performance has led to important improvements in the field. To this extent, density functional theory (DFT) calculations have contributed significantly providing fundamental understandings to develop new catalysts. With this aim, we presented here a detailed computational study of how the nature of the anion ligand binding to the metal affects the global properties and reactivity of the catalyst. Geometric, energetic and electronic analysis have been performed to reach the key insights necessary to build structure-performance correlations.
Insights into the Enhancement of MOF/Polymer Adhesion in Mixed-Matrix Membranes via Polymer Functionalization(ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2021-06-09) [Article]MOF-based mixed-matrix membranes (MMMs) prepared using standard routes often exhibit poor adhesion between polymers and MOFs. Herein, we report an unprecedented systematic exploration on polymer functionalization as the key to achieving defect-free MMMs. As a case study, we explored computationally MMMs based on the combination of the prototypical UiO-66(Zr) MOF with polymer of intrinsic porosity-1 (PIM-1) functionalized with various groups including amidoxime, tetrazole, and N-((2-ethanolamino)ethyl)carboxamide. Distinctly, the amidoxime-derivative PIM-1/UiO-66(Zr) MMM was predicted to express the desired enhanced MOF/polymer interfacial interactions and thus subsequently prepared and evaluated experimentally. Prominently, high-resolution transmission electron microscopy confirmed optimal adhesion between the two components in contrast to the nanometer-sized voids/defects shown by the pristine PIM-1/UiO-66(Zr) MMM. Notably, single-gas permeation measurements further corroborated the need of optimal MOF/polymer adhesion in order to effectively enable the MOF to play a role in the gas transport of the resulting MMM.
Nonlinear Preconditioning Strategies for Two-Phase Flows in Porous Media Discretized by a Fully Implicit Discontinuous Galerkin Method(SIAM Journal on Scientific Computing, Society for Industrial & Applied Mathematics (SIAM), 2021-06-09) [Article]We consider numerical simulation of two-phase flows in porous media using implicit methods. Because of the complex features involving heterogeneous permeability and nonlinear capillary effects, the nonlinear algebraic systems arising from the discretization are very difficult to solve. The traditional Newton method suffers from slow convergence in the form of a long stagnation or sometimes does not converge at all. In this paper, we develop nonlinear preconditioning strategies for the system of two-phase flows discretized by a fully implicit discontinuous Galerkin method. The preconditioners identify and approximately eliminate the local high nonlinearities that cause the Newton method to take small updates. Specifically, we propose two elimination strategies: one is based on exploring the unbalanced nonlinearities of the pressure and the saturation fields, and the other is based on identifying certain elements of the finite element space that have much higher nonlinearities than the rest of the elements. We compare the performance and robustness of the proposed algorithms with an existing single-field elimination approach and the classical inexact Newton method with respect to some physical and numerical parameters. Experiments on three-dimensional porous media applications show that the proposed algorithms are superior to other methods in terms of robustness and parallel efficiency.