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Novel nanoporous palladium catalyst for electroreduction of hydrogen peroxide

Rare Metals 2011年第4期30卷 332-336页

作者： YI Qingfeng NIU Fengjuan School of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China Key Laboratory of Theoretical Chemistry and Molecular Simulation （Ministry of Education of China） Hunan University of Science and Technology Xiangtan 411201 China

Titanium-supported nanoporous palladium catalyst （Pd/Ti） was prepared by a hydrothermal method using PdC12 as a precursor, ethylenediamine tetraacetic acid （EDTA） as a ligand, and formaldehyde as a reduction agent. Complex Pd-EDTA^2- is favorable for the formation of Pd particles with nanoscale sizes. The electroactivity of the Pd/Ti catalyst towards the electroreduction of hydrogen peroxide in 1 mol/L NaOH solution was evaluated by voltammetric techniques. Both linear scan voltammetric and chronoamperometric data present significantly large steady-state reduction current density of the hydrogen peroxide electroreduction on the prepared Pd/Ti catalyst. The results show that the prepared Pd/Ti catalyst is an effective electrocatalyst for the electroreduction of hydrogen peroxide in alkaline media.

关键词： electrocatalysis nanoporous materials palladium hydrogen peroxide fuel cells

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An Iterative Discontinuous Galerkin Method for Solving the Nonlinear Poisson Boltzmann Equation

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Communications in computational Physics 2014年第7期16卷 491-515页

作者： Peimeng Yin Yunqing Huang Hailiang Liu Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational ScienceXiangtan UniversityXiangtan 411105P.R.China Iowa State University Mathematics DepartmentAmesIA 50011USA.

An iterative discontinuous Galerkin(DG)method is proposed to solve the nonlinear Poisson Boltzmann(PB)*** first identify a function space inwhich the solution of the nonlinear PB equation is iteratively approximated through a series of linear PB equations,while an appropriate initial guess and a suitable iterative parameter are selected so that the solutions of linear PB equations are monotone within the identified solution *** the spatial discretization we apply the direct discontinuous Galerkin method to those linear PB *** precisely,we use one initial guess when the Debye parameter l=O(1),and a special initial guess for l≪1 to ensure *** iterative parameter is carefully chosen to guarantee the existence,uniqueness,and convergence of the *** particular,iteration steps can be reduced for a variable iterative *** one and two-dimensional numerical results are carried out to demonstrate both accuracy and capacity of the iterative DG method for both cases of l=O(1)and l≪***(m+1)th order of accuracy for L2 and mth order of accuracy for H1 for Pm elements are numerically obtained.

关键词： Poisson-Boltzmann equation nonlinear existence uniqueness DDG methods numerical flux.

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Discovery of New Metastable Patterns in Diblock Copolymers

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Communications in computational Physics 2013年第7期14卷 443-460页

作者： Kai Jiang Chu Wang Yunqing Huang Pingwen Zhang LMAM and School of Mathematical Sciences Peking UniversityBeijing 100871P.R.China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan UniversityXiangtan 411105P.R.China

The ordered patterns formed bymicrophase-separated block copolymer systems demonstrate periodic symmetry,and all periodic structures belong to one of 230 space *** on this fact,a strategy of estimating the initial values of self-consistent field theory to discover ordered patterns of block copolymers is *** particular,the initial period of the computational box is estimated by the Landau-Brazovskii model as *** planting the strategy into the whole-space discrete method,several new metastable patterns are discovered in diblock copolymers.

关键词： Metastable patterns diblock copolymers self-consistent field theory(SCFT) space group theory initial values

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Analytical solutions for Earth discontinuous coverage of satellite constellation with repeating ground tracks

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Chinese Journal of Aeronautics 2022年第10期35卷 275-291页

作者： Xiangyue HE Haiyang LI College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China

This paper presents an analytical model for calculating the Earth discontinuous coverage of satellite constellation with repeating ground tracks by integrating and extending the application of coverage region and route ***,the visibility condition for a ground point is represented as a coverage region in the two-dimension map of visibility properties,and the trajectories of satellites with circular orbits and repeating ground tracks are converted to several inclined lines in the *** analyzing the intersections of the lines and the edge of the coverage region,the coverage durations for the ground point can be *** on the point coverage,the variations of coverage characteristics along the parallel are analyzed,and the regional or global coverage characteristics of constellations can be *** examples show that the proposed method can accurately and rapidly calculate the coverage characteristics,*** time and coverage *** calculated results are extremely close to those of the Satellite Tool Kit(STK)and are also superior to the existing research *** proposed analytical model can be a useful tool for constellation design and coverage performance analysis.

关键词： Analytical model Coverage region Earth discontinuous coverage Repeating ground track Satellite constellation Two-dimension map of visibility properties

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

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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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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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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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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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