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Catalytic performance and kinetics of Au/γ-Al_2O_3 catalysts for low-temperature combustion of light alcohols

Transactions of Nonferrous Metals Society of China 2010年第3期20卷 437-442页

作者：邓谦李小梅彭振山龙云飞相龙明蔡铁军 School of Chemistry and Chemical Engineering Key Laboratory of Theoretical Chemistry and Molecular SimulationMinistry of EducationHunan University of Science and Technology Valiant Fine Chemicals Co.Ltd.

Au/γ-Al2O3 catalysts were prepared by deposition-precipitation method for the catalytic combustion of low concentration alcohol streams(methanol,ethanol,iso-propanol and n-propanol).The catalysts were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffractometry(XRD) and energy dispersive X-ray micro analysis(EDS) *** XPS results showed that there was only Au0 on the surface of *** XRD patterns showed that Au was presumably highly dispersed over γ-*** temperatures for complete conversion of methanol,ethanol,iso-propanol and n-propanol with concentration of 2.0 g/m3 were 60,155,170 and 137 ℃,respectively,but they were completely mineralized into CO2 and H2O at 60,220,260 and 217 ℃ respectively over the optimized *** activity of the catalyst was stable in 130 *** kinetics for the catalytic methanol elimination followed quasi-first order reaction expressed as r=0.652 8c0+0.084 *** value of apparent activation energy is 54.7 kJ/mol in the range of reaction temperature.

关键词： gold supported catalyst light alcohols low-temperature catalytic combustion kinetics

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Economical cascadic multigrid method (ECMG)

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science China Mathematics 2007年第12期50卷 1765-1780页

作者： Zhong-ci SHI~1 Xue-jun XU~(1+) Yun-qing HUANG~2 ~1 LSEC,Institute of computational Mathematics,Academy of Mathematics and Systems science,Chinese Academy of sciences,Beijing 100080,China ~2 hunan key laboratory for computation and simulation in science and engineering,Institute for computational and Applied Mathematics,Xiangtan University,Xiangtan 411105,China LSEC Institute of Computational Mathematics Academy of Mathematics Systems Science Chinese Academy of Sciences Beijing 100080 China Hunan Key Laboratory for Computation Simulation in Science Engineering Institute for Computational Applied Mathematics Xiangtan University Xiangtan 411105 China

In this paper, an economical cascadic multigrid method is proposed. Compared with the usual cascadic multigrid method developed by Bornemann and Deuflhard, the new one requires less iterations on each level, especially on the coarser grids. Many operations can be saved in the new cascadic multigrid algorithms. The main ingredient is the control of the iteration numbers on the each level to preserve the accuracy without over iterations. The theoretical justification is based on the observations that the error reduction rate of an iteration scheme in terms of the smoothing property is no longer accurate while the iteration number is big enough. A new formulae of the error reduction rate is employed in our new algorithm. Numerical experiments are reported to support our theory.

关键词： economical cascadic multigrid method (ECMG), cascadic multigrid method (CMG)

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A Posteriori Error Estimates of Triangular Mixed Finite Element Methods for Semilinear Optimal Control Problems

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Advances in Applied Mathematics and Mechanics 2009年第2期1卷 242-256页

作者： Zuliang Lu Yanping Chen Hunan Key Laboratory for Computation and Simulation in Science and Engineering Department of MathematicsXiangtan UniversityXiangtan 411105HunanP.R.China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631GuangdongP.R.China

In this paper,we present an a posteriori error estimates of semilinear quadratic constrained optimal control problems using triangular mixed finite element *** state and co-state are approximated by the order k≤1 RaviartThomas mixed finite element spaces and the control is approximated by piecewise constant *** derive a posteriori error estimates for the coupled state and control approximations.A numerical example is presented in confirmation of the theory.

关键词： Semilinear optimal control problems mixed finite element methods a posteriori error estimates

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Supercloseness of the Divergence-Free Finite Element Solutions on Rectangular Grids

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Communications in Mathematics and Statistics 2013年第2期1卷 143-162页

作者： Yunqing Huang Shangyou Zhang Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan UniversityXiangtan 411105China Department of Mathematical Sciences University of DelawareNewarkDE 19716USA

By the standard theory,the stable Qk+1,k−Qk,k+1/Qdck divergence-free element converges with the optimal order of approximation for the Stokes equations,but only order k for the velocity in H1-norm and the pressure in *** is due to one polynomial degree less in y direction for the first component of velocity,which is a Qk+1,k polynomial of x and *** this manuscript,we will show by supercloseness of the divergence free element that the order of convergence is truly k+1,for both velocity and *** special solutions(if the interpolation is also divergence-free),a two-order supercloseness is shown to *** tests are provided confirming the accuracy of the theory.

关键词： Mixed finite element Stokes equations Divergence-free element Quadrilateral element Rectangular grids Supercloseness Superconvergence

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An Algebraic Multigrid-Based Physical Factorization Preconditioner for the Multi-Group Radiation Diffusion Equations in Three Dimensions

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Numerical Mathematics(Theory,Methods and Applications) 2023年第2期16卷 410-432页

作者： Xiaoqiang Yue Zekai Zhang Xiaowen Xu Shuying Zhai Shi Shu National Center for Applied Mathematics in Hunan Key Laboratory of Intelligent Computing&Information Processing of Ministry of EducationHunan Key Laboratory for Computation and Simulation in Science and EngineeringXiangtan UniversityXiangtan 411105China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100094China School of Mathematical Sciences Huaqiao UniversityQuanzhou 362021China.

The paper investigates the robustness and parallel scaling properties of a novel physical factorization preconditioner with algebraic multigrid subsolves in the iterative solution of a cell-centered finite volume discretization of the threedimensional multi-group radiation diffusion *** key idea is to take advantage of a particular kind of block factorization of the resulting system matrix and approximate the left-hand block matrix selectively spurred by parallel processing *** spectral property of the preconditioned matrix is then *** practical strategy is considered sequentially and in ***,numerical results illustrate the numerical robustness,computational efficiency and parallel strong and weak scalabilities over the real-world structured and unstructured coupled problems,showing its competitiveness with many existing block preconditioners.

关键词： Radiation diffusion equations physical factorization preconditioning algebraic multigrid parallel and distributed computing

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A LEGENDRE GALERKIN SPECTRAL METHOD FOR OPTIMAL CONTROL PROBLEMS

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Journal of Systems science & Complexity 2011年第4期24卷 663-671页

作者： Yanping CHEN Nianshi XIA Nianyu YI School of Mathematical Sciences South China Normal University Guangzhou 510631 China. The Faculty of Mathematics Chengyi College Jimei University Xiamen 361021 China. Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematicsand Computational Science Xiangtan University Xiangtan 411105 China.

This paper considers the Legendre Galerkin spectral approximation for the unconstralnea optimal control problems. The authors derive a posteriori error estimate for the spectral approximation scheme of optimal control problem. By choosing the appropriate basis functions, the stiff matrix of the discretization equations is sparse. And the authors use the Fast Legendre Transform to improve the efficiency of this method. Two numerical experiments demonstrating our theoretical results are presented.

关键词： Legendre-Galerkin optimal control spectral method.

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Developing Finite Element Methods for Simulating Transformation Optics Devices with Metamaterials

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Communications in computational Physics 2019年第1期25卷 135-154页

作者： Wei Yang Jichun Li Yungqing Huang Bin He Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan UniversityXiangtan 411105P.R.China Department of Mathematical Sciences University of Nevada Las VegasLas VegasNevada 89154-4020USA

In this paper,we first develop the mathematical modeling equations for wave propagation in several transformation optics devices,including electromagnetic concentrator,rotator and *** we propose the corresponding finite element time-domain methods for simulating wave propagation in these transformation optics *** implement the proposed algorithms and our numerical results demonstrate the effectiveness of our modeling *** our best knowledge,this is the first work on time-domain finite element simulation carried out for the electromagnetic concentrator,rotator and splitter.

关键词： Maxwell’s equations finite element time-domain methods edge elements transfor-mation optics

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Error Estimates for the Iterative Discontinuous Galerkin Method to the Nonlinear Poisson-Boltzmann Equation

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Communications in computational Physics 2018年第1期23卷 168-197页

作者： Peimeng Yin Yunqing Huang Hailiang Liu Mathematics Department Iowa State UniversityAmesIA 50011USA Key Laboratory of Intelligent Computing&Information Processing of Ministry of Education Hunan Key Laboratory for Computation and Simulation in Science and EngineeringSchool of Mathematics and Computational ScienceXiangtan UniversityXiangtan411105P.R.China

This paper is devoted to the error estimate for the iterative discontinuous Galerkin(IDG)method introduced in[***,*** and ***.16:491-515,2014]to the nonlinear Poisson-Boltzmann *** total error includes both the iteration error and the discretization error of the direct DG method to linear elliptic *** the DDG method,the energy error is obtained by a constructive approach through an explicit global projection satisfying interface conditions dictated by the choice of numerical *** L^(2) error of order O(h^(m+1))for polynomials of degree m is further *** bounding constant is also shown to be independent of the iteration *** tests are given to validate the established convergence theory.

关键词： Poisson-Boltzmann equation DG methods global projection energy error estimates L^(2)error estimates

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Unveiling a large fraction of hidden organosulfates in ambient organic aerosol

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Nature Communications 2025年第1期16卷 1-11页

作者： Ma, Jialiang Reininger, Natalie Zhao, Cunliang Döbler, Damian Rüdiger, Julian Qiu, Yanting Ungeheuer, Florian Simon, Mario D’Angelo, Luca Breuninger, Anna David, Julia Bai, Yanxin Li, Yushan Xue, Ying Li, Lili Wang, Yuchen Hildmann, Stefanie Hoffmann, Thorsten Liu, Bangjun Niu, Hongya Wu, Zhijun Vogel, Alexander L. Institute for Atmospheric and Environmental Sciences Goethe University Frankfurt Frankfurt am Main Germany Institute of Ecology Evolution and Diversity Goethe University Frankfurt Frankfurt am Main Germany School of Earth Science and Engineering Hebei University of Engineering Handan China Air Monitoring Network German Environment Agency Langen Germany State Key Joint Laboratory of Environmental Simulation and Pollution Control Peking University Beijing China College of Environmental Science and Engineering Hunan University Changsha China Institute of Inorganic and Analytical Chemistry Johannes Gutenberg-University Mainz Germany

Organosulfates are key compounds driving the anthropogenic enhancement of ambient organic aerosol, however, total organosulfate quantification remains elusive due to their molecular diversity and the scarcity of authentic standards. Here, we present a solid-phase extraction method that isolates organosulfates from ambient aerosol samples and enables their identification and quantification using mass spectrometry and a charged aerosol detector, respectively. We investigate ambient aerosol samples from urban China and rural Germany and quantify ~130 and ~65 chromatographically resolved organosulfates, respectively, contributing less than ~2% to the total organic matter. We find a significantly larger organosulfate fraction appearing as a broad peak in the chromatograms from the charged aerosol detector. Confirming its origin from chromatographically non-resolved organosulfates, an all-ion fragmentation experiment reveals specific sulfate-related ions. Integrating this peak, we find the contribution of organosulfates to organic aerosol is 12-17% and ~21% in samples from urban China and rural Germany, respectively. These findings emphasise the potential of sulfur emission reduction for mitigating both sulfate-related and organic aerosol pollution. © The Author(s) 2025.

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Multicontinuum homogenization for coupled flow and transport equations

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Journal of computational and Applied Mathematics 2026年 471卷

作者： Dmitry Ammosov Jian Huang Wing Tat Leung Buzheng Shan Computational Technologies & Artificial Intelligence North-Eastern Federal University Yakutsk 677980 Russia School of Mathematics and Computational Science Xiangtan University National Center for Applied Mathematics in Hunan and Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan 411105 Hunan China Department of Mathematics City University of Hong Kong Hong Kong Department of Mathematics Texas A&M University College Station TX 77843 USA

In this paper, we present the derivation of a multicontinuum model for the coupled flow and transport equations by applying multicontinuum homogenization. We perform the multicontinuum expansion for both flow and transport solutions and formulate novel coupled constraint cell problems to capture the multiscale property, where oversampled regions are utilized to avoid boundary effects. Assuming the smoothness of macroscopic variables, we obtain a multicontinuum system composed of macroscopic elliptic equations and convection–diffusion–reaction equations with homogenized effective properties. Finally, we present numerical results for various coefficient fields and boundary conditions to validate our proposed algorithm.

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