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Experimental Investigation of the Temperature-Dependent Dissolution Process of Aluminosilicate Glass and Low-Calcium Supplementary Cementitious Materials Under Alkaline Conditions

SSRN

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SSRN 2024年

作者： Zheng, Yuqian Jiao, Shizhe Hu, Wei Ishida, Tetsuya Wang, ZhiYong Ye, Jiayuan Qian, Hao Zhang, Wensheng Wang, Tiao Medepalli, Satya Concrete Laboratory Department of Civil Engineering School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan School of Future Technology Department of Chemical Physics Anhui Center for Applied Mathematics The University of Science and Technology of China Jinzhai Road No. 96 Hefei230026 China Key Laboratory of Sulfoaluminate and Ferroaluminate Cement Institute of Technical Information for Building Materials Industry of China No.1 Guanzhuang Dongli Chaoyang District Beijing100024 China State Key Laboratory of Green Building Materials China Building Materials Academy No. 1 Guanzhuang Dongli Chaoyang District Beijing100024 China School of Materials Science and Engineering Wuhan University of Technology No. 122 Luoshi Road Hongshan District Wuhan430070 China 4800 Cao’an Road Shanghai201804 China

High-temperature curing is commonly employed to promote the pozzolanic activity of supplementary cementitious materials (SCMs) in cementitious systems. Herein, the temperature-dependent dissolution processes of low-calcium SCMs and synthesised aluminosilicate glass were examined at pH 13 for cementitious systems. The dissolution rate and thermal activation energy (TAE) were estimated using nonlinear fitting and the Arrhenius equation. Experimental and analytical findings demonstrated that the TAEs of investigated SCMs and aluminosilicate glasses were temperature-dependent, decreasing with increasing temperature. Moreover, the TAE of aluminosilicate glasses increased with increasing Al/Si ratio, mainly due to the higher TAE of Al2O3 compared to SiO2. In addition, the TAE of fly ash was higher than that of investigated glass, largely because the Si and Al coordination numbers increased with decreasing cooling rates, according to molecular dynamics analysis. The topological TAE derived from molecular dynamics analysis is a promising parameter for estimating the TAE of aluminosilicate glass. © 2024, The Authors. All rights reserved.

关键词： Calcium

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Prediction of carbon nanostructure mechanical properties and role of defects using machine learning

arXiv

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arXiv 2021年

作者： Zhao, Qi Winetrout, Jordan J. Xu, Yanxun Wang, Yusu Heinz, Hendrik Halıcıoglu Data Science Institute University of California San Diego San diegoCA92093 United States Department of Chemical and Biological Engineering University of Colorado Boulder BoulderCO80309 United States Materials Science and Engineering Program University of Colorado Boulder BoulderCO80309 United States Department of Applied Mathematics and Statistics Johns Hopkins University BaltimoreMD21218 United States

Carbon fiber and graphene-based nanostructures such as carbon nanotubes (CNTs) and defective structures have extraordinary potential as strong and lightweight materials. A longstanding bottleneck has been lack of understanding and implementation of atomic-scale engineering to harness the theoretical limits of modulus and tensile strength, of which only a fraction is routinely reached today. Here we demonstrate accurate and fast predictions of mechanical properties for CNTs and arbitrary 3D graphitic assemblies based on a training set of over 1000 stress-strain curves from cutting-edge reactive MD simulation and machine learning (ML). Several ML methods are compared and show that our newly proposed hierarchically structured graph neural networks with spatial information (HS-GNNs) achieve predictions in modulus and strength for any 3D nanostructure with only 5-10% error across a wide range of possible values. The reliability is sufficient for practical applications and a great improvement over off-the shelf ML methods with up to 50% deviation, as well as over earlier models for specific chemistry with 20% deviation. The algorithms allow more than 100 times faster mechanical property predictions than traditional molecular dynamics simulations, the identification of the role of defects and random 3D morphology, and high-throughput screening of 3D structures for enhanced mechanical properties. The algorithms can be scaled to morphologies up to 100 nm in size, expanded for chemically similar compounds, and trained to predict a broader range of properties. © 2021, CC BY.

关键词： Defects

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Simulation of NMPC for a Laboratory Adiabatic CSTR with an Exothermic Reaction

Simulation of NMPC for a Laboratory Adiabatic CSTR with an E...

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European Control Conference (ECC)

作者： John Bagterp Jørgensen Tobias K. S. Ritschel Dimitri Boiroux Eskild Schroll-Fleischer Morten Ryberg Wahlgreen Marcus Krogh Nielsen Hao Wu Jakob Kjøbsted Huusom Department of Applied Mathematics and Computer Science Technical University of Denmark Lyngby Denmark Department of Chemical and Biochemical Engineering Technical University of Denmark Lyngby Denmark

ISBN: (数字)9783907144022

ISBN: (纸本)9781728188133

In this paper, we present nonlinear system identification and nonlinear model predictive control (NMPC) for a laboratory-scale adiabatic continuous stirred tank reactor (CSTR) with an exothermic reaction. We describe the equipment used in the process, and we present a process model based on first principles. We use a maximum likelihood estimation (MLE) approach based on the process model and the continuous-discrete extended Kalman filter (CD-EKF) to estimate four model parameters. The NMPC is based on the process model (with the estimated model parameters), the CD-EKF, and a nonlinear least-squares regulator with input (Tikhonov) and rate-of-movement regularization. We present simulations demonstrating that the NMPC (implemented in Python and C) can track any stable and unstable steady state for this system with multiple steady states in some operational regions.

关键词： chemical reactors Temperature measurement Adiabatic Mathematical model Maximum likelihood estimation Heuristic algorithms Parameter estimation

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Economic Nonlinear Model Predictive Control of a U-loop Bioreactor

Economic Nonlinear Model Predictive Control of a U-loop Bior...

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European Control Conference (ECC)

作者： Tobias K. S. Ritschel Dimitri Boiroux Marcus Krogh Nielsen Jakob Kjøbsted Huusom Sten Bay Jørgensen John Bagterp Jørgensen Department of Applied Mathematics and Computer Science Technical University of Denmark Lyngby Denmark Department of Chemical and Biochemical Engineering Technical University of Denmark Lyngby Denmark

ISBN: (数字)9783907144022

ISBN: (纸本)9781728188133

In this paper, we present an algorithm for economic nonlinear model predictive control (NMPC) of single-cell protein production in a U-loop bioreactor. The model of the U-loop bioreactor consists of both stochastic ordinary and partial differential equations. Using a typical finite-volume discretization, the model contains 87 state variables. The NMPC algorithm is based on the continuous-discrete extended Kalman filter and a simultaneous collocation method. We present a closed-loop simulation which demonstrates the computational feasibility of real-time implementation of the NMPC algorithm for startup and steady state operation of the U-loop reactor.

关键词： Mathematical model Inductors Computational modeling Substrates Biological system modeling Stochastic processes Prediction algorithms

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Ab-initio calculations of structural,electronic,and optical properties of Zn_3(VO_4)_2

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Chinese Physics B 2018年第3期27卷 220-224页

作者： Nisar Ahmed S Mukhtar Wei Gao Syed Zafar Ilyas Department of Physics and Applied Mathematics Pakistan Institute of Engineering and Applied Sciences Department of Physics Allama Iqbal Open University Department of Chemical and Materials Engineering the University of Auckland

The structural, electronic, and optical properties of Zn3（VO4）2 are investigated using full potential linearized aug- mented plane wave （FP-LAPW） method within the framework of density functional theory （DFT）. Various approaches are adopted to treat the exchange and correlation potential energy such as generalized gradient approximation （GGA）, GGA＋U, and the Tran-Blaha modified Becke-Johnson （TB-mBJ） potential. The calculated band gap of 3.424 eV by TB- mBJ is found to be close to the experimental result （3.3 eV）. The optical anisotropy is analyzed through optical constants, such as dielectric function and absorption coefficient along parallel and perpendicular crystal orientations. The absorption coefficient reveals high absorption （1.5 ×10^6cm^-1） of photons in the ultraviolet region.

关键词： density functional theory Zn3（V04）2 electronic structure optical properties

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A mems _-preconcentrator employing a carbon molecular sieve membrane for highly volatile organic compound sampling

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Chemosensors 2021年第5期9卷

作者： Kuo, Hung-Yang Cheng, Wei-Riu Wu, Tzu-Heng Sheen, Horn-Jiunn Wang, Chih-Chia Lu, Chia-Jung Department of Chemistry National Taiwan Normal University Taipei11677 Taiwan Institute of Applied Mechanics National Taiwan University Taipei10617 Taiwan Department of Chemical and Materials Engineering Chung Cheng Institute of Technology National Defense University Taoyuan33509 Taiwan Undergraduate Degree Program of System Engineering and Technology National Yang Ming Chiao Tung University Hsinchu30010 Taiwan

This paper presents the synthesis and evaluation of a carbon molecular sieve membrane (CMSM) grown inside a MEMS-fabricated μ-preconcentrator for sampling highly volatile organic compounds. An array of µ-pillars measuring 100 µm in diameter and 250 µm in height were fabricated inside a microfluidic channel to increase the attaching surface for the CMSM. The surface area of the CMSM was measured as high as 899 m2/g. A GC peak amplification factor >2 × 104 was demonstrated with gaseous ethyl acetate. Up to 1.4 L of gaseous ethanol at the 100 ppb level could be concentrated without exceeding the capacity of this microchip device. Sharp desorption chromatographic peaks ( © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

关键词： Molecular sieves

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Correction to: Identifying Efficient Transport Pathways in Early‑Wood Timber: Insights from 3D X‑ray CT Imaging of Softwood in the Presence of Flow

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Transport in Porous Media 2021年第3期137卷 799-800页

作者： H. C. Burridge R. Pini S. M. K. Shah T. P. S. Reynolds G. Wu D. U. Shah O. A. Scherman M. H. Ramage P. F. Linden Department of Civil and Environmental Engineering Imperial College London London UK Department of Chemical Engineering Imperial College London London UK Present Address UCL Mechanical Engineering Research Complex At Harwell RAL Didcot UK Institute for Infrastructure and Environment School of Engineering University of Edinburgh Edinburgh UK Melville Laboratory for Polymer Synthesis Department of Chemistry University of Cambridge Cambridge UK Department of Architecture University of Cambridge Cambridge UK Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences University of Cambridge Cambridge UK

A correction to this paper has been published: https://***/10.1007/s11242-021-01569-3

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Helmholtzian Eigenmap: Topological feature discovery & edge flow learning from point cloud data

arXiv

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arXiv 2021年

作者： Chen, Yu-Chia Wu, Weicheng Meila, Marina Kevrekidis, Ioannis G. Meta Platforms Inc. SeattleWA98109 United States Department of Statistics University of Washington SeattleWA98195 United States Chemical and Biomolecular Engineering Applied Mathematics and Statistics Johns Hopkins University BaltimoreMD21218 United States

The manifold Helmholtzian (1-Laplacian) operator ∆1 elegantly generalizes the Laplace-Beltrami operator to vector fields on a manifold M. In this work, we propose the estimation of the manifold Helmholtzian from point cloud data by a weighted 1-Laplacian L1. While higher order Laplacians have been introduced and studied, this work is the first to present a graph Helmholtzian constructed from a simplicial complex as a consistent estimator for the continuous operator in a non-parametric setting. Equipped with the geometric and topological information about M, the Helmholtzian is a useful tool for the analysis of flows and vector fields on M via the Helmholtz-Hodge theorem. In addition, the L1 allows the smoothing, prediction, and feature extraction of the flows. We demonstrate these possibilities on substantial sets of synthetic and real point cloud datasets with non-trivial topological structures;and provide theoretical results on the limit of L1 to ∆1 Copyright © 2021, The Authors. All rights reserved.

关键词： Topology

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Geometrical effect coupled with nanofluid on heat transfer enhancement in heat exchangers

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International Journal of Thermofluids 2021年 10卷

作者： Olabi, A.G. Wilberforce, Tabbi Sayed, Enas Taha Elsaid, Khaled Rahman, S.M.Atiqure Abdelkareem, Mohammad Ali Department of Sustainable and Renewable Energy Engineering University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates Mechanical Engineering and Design Aston University School of Engineering and Applied Science Aston Triangle BirminghamB4 7ET United Kingdom Center for Advanced Materials Research University of Sharjah PO Box 27272 Sharjah United Arab Emirates Chemical Engineering Department Minia University Elminia Egypt Chemical Engineering Program Texas A& M University College StationTX United States

This investigation summarized the application of nanofluids (NFs) in heat exchangers (HExs) with different geometries. The quest for heat devices with quick response for the industrial sector is still a major challenge that has been an active research direction over the years. Addressing this issue is likely to increase the capacity of several industries. There is a direct relationship between expanding the heat capacity and the pressure drop. The common approach in increasing the rate of heat transfer often leads to an increment in pressure drop. This study reviews and summarizes the investigations on various geometrical effects inside the channel combined with NF in HExs. This review explored the potential of NFs as possible heat transfer fluid in HExs. From a detailed literature review compiled and evaluated, it has been deduced that NFs application significantly improves the thermal efficiency of HExs. The investigation further evaluated plate, helical, as well as shell and tube HExs. The review explored NFs application in HExs and how they can significantly improve the HExs' thermal characteristics. It was deduced that the use of NFs improved the heat transfer both experimentally and numerically. This equally has a direct relation to energy savings as well as industrial waste heat. © 2021 The Author(s)

关键词： Heat exchangers

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Mechanism of skyrmion condensation and pairing for twisted bi-layer graphene

arXiv

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arXiv 2021年

作者： Jing, Dian Tyner, Alexander Conkey Goswami, Pallab Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States Department of Chemical and Biological Engineering Northwestern University EvanstonIL60208 United States Integrated Science Program Northwestern University EvanstonIL60208 United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States

When quantum flavor Hall insulator phases of itinerant fermions are disordered by strong quantum fluctuations, the condensation of skyrmion textures of order parameter fields can lead to superconductivity. In this work, we address the mechanism of skyrmion condensation by considering the scattering between (2+1)-dimensional, Weyl fermions and hedgehog type tunneling configurations of order parameters that violate the skyrmion-number conservation law. We show the quantized, flavor Hall conductivity (σxyf ) controls the degeneracy of topologically protected, fermion zero-modes, localized on hedgehogs, and the overlap between zero-mode eigenfunctions or't Hooft vertex determines the nature of pairing. We demonstrate the quantum-disordered, flavor Hall insulators with σxyf = 2N lead to different types of charge 2Ne− superconductivity. Some implications for the competition among flavor Hall insulators, the charge 2e− paired states in BCS and pair-density-wave channels, and the composite, charge 4e− superconductors for twisted bilayer graphene are outlined. © 2021, CC BY.

关键词： Condensation

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