检索结果-南通市图书馆

Journal of Computational Mathematics 2024年第2期42卷 355-371页

作者： yanping chen Zhenrong chen Yunqing Huang School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan UniversityXiangtan 411105China

For fractional Volterra integro-differential equations(FVIDEs)with weakly singular kernels,this paper proposes a generalized Jacobi spectral Galerkin method.The basis functions for the provided method are selected generalized Jacobi functions(GJFs),which can be utilized as natural basis functions of spectral methods for weakly singular FVIDEs when appropriately constructed.The developed method's spectral rate of convergence is determined using the L^(∞)-norm and the weighted L^(2)-norm.Numerical results indicate the usefulness of the proposed method.

关键词： Generalized Jacobi spectral Galerkin method Fractional-order Volterra integ-ro-differential equations Weakly singular kernels Convergence analysis

Nitsche-XFEM for a time fractional diffusion interface problem

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第3期67卷 665-682页

作者： Tao Wang yanping chen China Nuclear Power Technology Research Institute Co.Ltd. Shenzhen 518028China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

In this paper, we propose a space-time finite element method for a time fractional diffusion interface problem. This method uses the low-order discontinuous Galerkin(DG) method and the Nitsche extended finite element method(Nitsche-XFEM) for temporal and spatial discretization, respectively. Sharp pointwise-in-time error estimates in graded temporal grids are derived, without any smoothness assumptions on the solution.Finally, three numerical examples are provided to verify the theoretical results.

关键词： fractional diffusion interface discontinuous Galerkin Nitsche-XFEM error estimates

LaMnO_(3)/Co_(3)O_(4) nanocomposite for enhanced triethylamine sensing properties

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第4期42卷 733-742页

作者： Jian Zhang yanping chen Ling Li Xue chen Wenya An Xiujuan Qian Yuye Tao School of Science Shandong Jianzhu UniversityJinan250100China

LaMnO_(3) modified Co_(3)O_(4) nanocomposites were prepared by simple hydrothermal method co mbined with sol-gel method.The gas sensitivity properties of pure Co_(3)O_(4) and LaMnO_(3)/Co_(3)O_(4) with different composite proportions are compared.It is found that 0.6-LMO/Co_(3)O_(4) sensor has higher sensitivity to triethylamine(TEA)than pure Co_(3)O_(4) sensor,which is improved by 9.27 times.And the working temperature is reduced from 150 to 130℃.Besides,it has excellent gas selectivity and repeatability.The improvement of the gas sensitivity of LaMnO_(3)/Co_(3)O_(4) sensor may be due to the fact that LaMnO_(3) is an effective catalyst,and the catalytic performance perhaps is beneficial to improving the sensing performance.In addition,the formation of p-p heterojunctions may be the key factor to improve the gas sensing performance.This work provides a new Co_(3)O_(4)-based gas sensing material for the detection of TEA.

关键词： Gas sensing Co_(3)O_(4) LaMnO_(3) Triethylamine Rareearths

Selective extinction and habitat nestedness are the main drivers of lizard nestedness in the Zhoushan Archipelago

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2024年第2期70卷 244-252页

作者： Minchu Zhang Chaonan Tang Qing Zhang chengxiu Zhan Chuanwu chen yanping Wang Laboratory of Island Biogeography and Conservation Biology College of Life SciencesNanjing Normal UniversityNanjing 210023China

Nested subset pattern(nestedness)is an important part of the theoretical framework of island biogeography and community ecology.However,most previous studies often used nestedness metrics or randomization algorithms that are vulnerable to type I error.In this study,we inves-tigated the nestedness of lizard assemblages on 37 islands in the Zhoushan Archipelago,China.We used the line-transect method to survey species occurrence,abundance,and habitat types of lizards on 37 islands during 2 breeding seasons in 2021 and 2022.We applied the nested metric WNODF and the conservative rc null model to control for type I error and quantify the significance of nestedness.Spearman rank cor relations were used to evaluate the role of 4 habitat variables(island area,2 isolation indices,and habitat diversity)and 4 ecological traits(body size,geographic range size,clutch size,and minimum area requirement)in generating nestedness.The results of WNODF analyses showed that lizard assemblages were significantly nested.The habitat-by-site matrix estimated by the program NODF was also significantly nested,support-ing the habitat nestedness hypothesis.The nestedness of lizard assemblages were significantly correlated with island area,habitat diversity.clutch size,and minimum area requirement.Overall,our results suggest that selective extinction and habitat nestedness were the main drivers of lizard nestedness in our system.In contrast,the nestedness of lizard assemblages was not due to passive sampling or selective colonization.To maximize the number of species preserved,our results indicate that we should protect both large islands with diverse habitats and species with largearea requirement and clutch size.

关键词： clutch size habitat nestedness lizards minimum area requirement nestedness selective extinction WNODF Zhoushan Archipelago.

Photo-responsive functional materials based on light-driven molecular motors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第3期13卷 407-420页

作者： yanping Deng Guiying Long Yang Zhang Wei Zhao Guofu Zhou Ben L.Feringa Jiawen chen SCNU-UG International Joint Laboratory of Molecular Science and Displays National Center for International Research on Green OptoelectronicsSouth China Normal UniversityGuangzhou 510006China Stratingh Institute for Chemistry University of GroningenNijenborgh 49747AG GroningenThe Netherlands

In the past two decades,the research and development of light-triggered molecular machines have mainly focused on developing molecular devices at the nanoscale.A key scientific issue in the field is how to amplify the controlled motion of molecules at the nanoscale along multiple length scales,such as the mesoscopic or the macroscopic scale,or in a more practical perspective,how to convert molecular motion into changes of properties of a macroscopic material.Light-driven molecular motors are able to perform repetitive unidirectional rotation upon irradiation,which offers unique opportunities for responsive macroscopic systems.With several reviews that focus on the design,synthesis and operation of the motors at the nanoscale,photo-responsive macroscopic materials based on light-driven molecular motors have not been comprehensively summarized.In the present review,we first discuss the strategy of confining absolute molecular rotation into relative rotation by grafting motors on surfaces.Secondly,examples of self-assemble motors in supramolecular polymers with high internal order are illustrated.Moreover,we will focus on building of motors in a covalently linked system such as polymeric gels and polymeric liquid crystals to generate complex responsive functions.Finally,a perspective toward future developments and opportunities is given.This review helps us getting a more and more clear picture and understanding on how complex movement can be programmed in light-responsive systems and how man-made adaptive materials can be invented,which can serve as an important guideline for further design of complex and advanced responsive materials.

关键词： functions materials material

A CHARACTERISTIC MIXED FINITE ELEMENT TWO-GRID METHOD FOR COMPRESSIBLE MISCIBLE DISPLACEMENT PROBLEM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2022年第5期40卷 794-813页

作者： Hanzhang Hu yanping chen School of Mathematics Jiaying UniversityMeizhou 514015China School of Mathematical Science South China Normal UniversityGuangzhou 520631China

A nonlinear parabolic system is derived to describe compressible miscible displacement in a porous medium.The concentration equation is treated by a mixed finite element method with characteristics(CMFEM)and the pressure equation is treated by a parabolic mixed finite element method(PMFEM).Two-grid algorithm is considered to linearize nonlinear coupled system of two parabolic partial differential equations.Moreover,the L q error estimates are conducted for the pressure,Darcy velocity and concentration variables in the two-grid solutions.Both theoretical analysis and numerical experiments are presented to show that the two-grid algorithm is very effective.

关键词： Two-grid method Miscible displacement problem Mixed finite element Characteristic finite element method.

Copper-catalyzed C(sp)-H aryl amination enables modular synthesis of quinolines and 2-quinolinones

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第2期67卷 595-603页

作者： Yang Gao Haixia Li Simin Yang yanping Huo Qian chen Xianwei Li Zhe Wang Xiao-Qiang Hu School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou510006China Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory Jieyang515200China Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education&Hubei Key Laboratory of Catalysis and Materials Science School of Chemistry and Materials ScienceSouth-Central University for NationalitiesWuhan430074China

Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structurally diverse C2-substituted quinolines and 2-quinolinones.The in-situ formed carbonyl-ynamines are prone to tautomerize to carbonyl-ketenimines,which can efficiently react with a series of nucleophiles,including amines,alcohols,phenols,thiols,thiophenols,active-methylene compounds,and even water to produce various quinoline derivatives with the generation of H_(2)O as a sole and green byproduct.This method also unlocks a practical route to create various quinoline-fused heterocycles and can be successfully applied to the late-stage modification of complex molecules and the concise synthesis of bioactive targets.Mechanistic studies reveal a coppercatalyzed inner-sphere nitrene transfer process by using anthranils as novel aryl nitrene precursors.

关键词： copper catalysis anthranils C(sp)-H aryl amination carbonyl-ketenimines quinolines

A zincophilic molecular brush for a dendrite-free,corrosionresistant,zinc metal anode with a long life cycle

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第1期17卷 390-396页

作者： Penggao Liu Jia Guo Xinyue chen Ting Wang yanping Huang Shasha Gao Tao Wang Dongling Wu Kaiyu Liu State Key Laboratory of Chemistry and Utilization of Carbon based Energy Resources College of ChemistryXinjiang UniversityUrumqi 830017China Hunan Provincial Key Laboratory of Chemical Power Sources College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China Key Laboratory of New Low-carbon Green Chemical Technology School of Chemistry and Chemical EngineeringEducation Department of Guangxi Zhuang Autonomous RegionGuangxi UniversityNanning 530004China Key Laboratory of Microelectronics and Energy of Henan Province Department of Physics and Electronic EngineeringXinyang Normal UniversityXinyang 464000China Interdisciplinary Research Center for Sustainable Energy Science and Engineering(IRC4SE2) School of Chemical EngineeringZhengzhou UniversityZhengzhou 450001China

Zinc-based aqueous rechargeable batteries have attracted extensive attention due to their low cost,safety,and environmental friendliness.However,dendrite growth and hydrogen evolution of Zn anodes limit their large-scale application.A new strategy to produce a polyacrylamide/reduced graphene oxide(PAM@rGO)molecular nanobrush coating and control Zn electrolyte interface engineering is proposed for use in highly reversible Zn plating/stripping.Hydrogen evolution is inhibited,and Zn deposition is consolidated using the rich zincophilic functional groups of the branched polyacrylamide chain and the high conductivity of rGO.Due to the synergistic effects of corrosion resistance and dendrite-free growth,PAM@rGO/Zn provides prolonged and reversible Zn plating/stripping.Density functional theory(DFT)calculations expand on homogenized nucleation.The PAM@rGO/Zn||activated carbon(AC)capacitor exhibits long cyclic stability,fast ion transfer,and minimal interfacial impedance.This study provides experimental and theoretical bases for the structural design of Zn anode.

关键词： zincophilic nanobrush polyacrylamide/reduced graphene oxide(PAM@rGO)/Zn surface modification Zn based energy storage

AN IMPROVED TWO-GRID TECHNIQUE FOR THE NONLINEAR TIME-FRACTIONAL PARABOLIC EQUATION BASED ON THE BLOCK-CENTERED FINITE DIFFERENCE METHOD

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2022年第3期40卷 453-471页

作者： Xiaoli Li yanping chen Chuanjun chen School of Mathematics Shandong UniversityJinanShandong 250100China School of Mathematical Science South China Normal UniversityGuangzhou 520631China School of Mathematics and Information Sciences Yantai UniversityYantai 264005China

A combined scheme of the improved two-grid technique with the block-centered finite difference method is constructed and analyzed to solve the nonlinear time-fractional parabolic equation.This method is considered where the nonlinear problem is solved only on a coarse grid of size H and two linear problems based on the coarse-grid solutions and one Newton iteration is considered on a fine grid of size h.We provide the rigorous error estimate,which demonstrates that our scheme converges with order O(∆t^(2−α)+h^(2)+H^(4))on non-uniform rectangular grid.This result indicates that the improved two-grid method can obtain asymptotically optimal approximation as long as the mesh sizes satisfy h=O(H^(2)).Finally,numerical tests confirm the theoretical results of the presented method.

关键词： Improved two-grid Time-fractional parabolic equation Nonlinear Error estimates Numerical experiments

NUMERICAL ANALYSIS OF A NONLINEAR SINGULARLY PERTURBED DELAY VOLTERRA INTEGRO-DIFFERENTIAL EQUATION ON AN ADAPTIVE GRID

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2022年第2期40卷 258-274页

作者： Libin Liu yanping chen Ying Liang School of Mathematics and Statistics Nanning Normal UniversityNanning 530023China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

In this paper,we study a nonlinear first-order singularly perturbed Volterra integro-differential equation with delay.This equation is discretized by the backward Euler for differential part and the composite numerical quadrature formula for integral part for which both an a priori and an a posteriori error analysis in the maximum norm are derived.Based on the a priori error bound and mesh equidistribution principle,we prove that there exists a mesh gives optimal first order convergence which is robust with respect to the perturbation parameter.The a posteriori error bound is used to choose a suitable monitor function and design a corresponding adaptive grid generation algorithm.Furthermore,we extend our presented adaptive grid algorithm to a class of second-order nonlinear singularly perturbed delay differential equations.Numerical results are provided to demonstrate the effectiveness of our presented monitor function.Meanwhile,it is shown that the standard arc-length monitor function is unsuitable for this type of singularly perturbed delay differential equations with a turning point.

关键词： Delay Volterra integro-differential equation Singularly perturbed Error analysis Monitor function