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A FAST COMPACT DIFFERENCE METHOD FOR TWO-DIMENSIONAL NONLINEAR SPACE-FRACTIONAL COMPLEX GINZBURG-LANDAU EQUATIONS

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Journal of Computational Mathematics 2021年第5期39卷 708-732页

作者： Lu zhang qifeng zhang Hai-wei Sun School of Mathematics and Statistics Xuzhou University of TechnologyXuzhou 221018China Department of Mathematics Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Mathematics University of MacaoMacaoChina

This paper focuses on a fast and high-order finite difference method for two-dimensional space-fractional complex Ginzburg-Landau *** firstly establish a three-level finite difference scheme for the time variable,followed by the linearized technique of the nonlinear *** the fourth-order compact finite difference method is employed to discretize the spatial *** the accuracy of the discretization is O(τ^(2)+h^(4)_(1)+h^(4)_(2))in L_(2)-norm,where τ is the temporal step-size,both h_(1) and h_(2) denote spatial mesh sizes in x-and y-directions,*** rigorous theoretical analysis,including the uniqueness,the almost unconditional stability,and the convergence,is studied via the energy ***,the discretized system holds the block Toeplitz ***,the coefficient Toeplitz-like matrix only requires O(M_(1)M_(2)) memory storage,and the matrix-vector multiplication can be carried out in O(M_(1)M_(2))(log M_(1)+log M_(2))computational complexity by the fast Fourier transformation,where M_(1) and M_(2) denote the numbers of the spatial grids in two different *** order to solve the resulting Toeplitz-like system quickly,an efficient preconditioner with the Krylov subspace method is proposed to speed up the iteration *** results are given to demonstrate the well performance of the proposed method.

关键词： Space-fractional Ginzburg-Landau equation Compact scheme Boundedness Convergence Preconditioner FFT

Highly Oriented ZnO Rod Arrays on Si Substrates from Aqueous Solution

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 189-193页

作者： LIU Changsong LI Zhiwen zhang qifeng School of Mechanical Engineering Qingdao Technological University Qingdao 266033 China Department of Electronics Peking University Beijing 100871 China

Ordered zinc oxide （ZnO） rod arrays with very high orientation were fabricated on Si substrates by using a solution method. The substrate surfaces were functionalized by Self-Assembly Monolayers （SAMs）. In the very early growth stage, the oriented ZnO crystals had already grown, which appeared to be the main reason why ZnO nanorods showed very high orientation. The un-dense and un-uniform SAMs provided a surface that was heterogeneous to ZnO nucleation. Consequently, highly oriented ZnO rods were selectively grown on the ＂coin-like＂ SAM-uncovered regions. The route developed here can provide some helpful information to control the nucleation and orientation of ZnO in aqueous solution. Also, the site-selective growth mechanisms can indicate a clue to grow patterned highly oriented ZnO nanorod arrays by the organic template.

关键词： zinc oxide (ZnO) self assembly monolayers (SAMs) crystal growth nanostructures site-selective growth solution method

Controllable tune of the cutoff frequencies in a photonic crystal waveguide with hexagonal lattice

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Science China(Physics,Mechanics & Astronomy) 2013年第6期56卷 1079-1084页

作者： ZHU KongTao DENG TianSong SUN Yan zhang qifeng WU JinLei Key Laboratory for the Physics and Chemistry of Nanodevices Department of ElectronicsPeking University

In this paper,configuration parameters of the waveguide are altered independently or simultaneously to control the cutoff frequencies of the guided *** independent control range of the upper and lower cutoff frequencies is 55.0% and 63.9% of the photonic band gap(PBG),*** regulating range of the simultaneous tuning can be as large as 28.6% in terms of the PBG,or 240% in terms of the *** tuning cutoff frequency method provides an efficient way to tailor the guided band and further tune the optical properties of PhCWs.

关键词： photonic crystal waveguide cutoff frequency coupled mode controllable tune

Understanding the role of tungsten on Pt/CeO_(2)for vinyl chloride catalytic combustion

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Journal of Rare Earths 2022年第9期40卷 1462-1470,I0005页

作者： qifeng zhang Zhengbo Zhou Tian Fang Han Gu Yanglong Guo Wangcheng Zhan Yun Guo Li Wang Key Laboratory for Advanced Materials and Research Institute of Industrial Catalysis School of Chemistry&Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

Spherical CeO_(2)synthesized by the hydrothermal process was used as support to prepare Pt/WO_(3)/CeO_(2),and the effects of tungsten(W)contents on activity,stability and polychlorinated by-products were investigated to understand the role of W for vinyl chloride(VC)catalytic *** introduction of12 wt%W to Pt/CeO_(2)(P12 WC)exhibits the highest catalytic activity with 90%conversion of VC at 250℃,meanwhile the stability improves and the polychlorinated by-products in the tail gas significantly decrease due to the removal of dissociated Cl species in the formation of *** beneficial effects of W on Pt/CeO_(2)are closely related to the chemical state of Pt,redox and surface acid sites *** doped W not only makes Pt disperse evenly on the support with the high valence,but also weakens the interaction between Pt and CeO_(2)by the formation of Pt-O-W and Pt-O-W-O-Ce species,which facilitates oxygen *** addition,the modification of W species also significantly increases the surface acidity amount and changes the distribution of acid sites.

关键词： Tungsten oxides Vinyl chloride Catalytic oxidation Pt/CeO_(2) By-products Rare earths

Prediction of Postbuckling Characteristics of Perforated Metamaterial Cylindrical Shells Under Axial Compression

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Acta Mechanica Solida Sinica 2023年第3期36卷 428-442页

作者： Xueqing Cao Jianyi Guo Yongqi Li qifeng zhang Zhenhuan Zhou Jiabin Sun Xinsheng Xu C.W.Lim State Key Laboratory of Structural Analysis for Industrial Equipment and School of Ocean Science and Technology Dalian University of TechnologyPanjin 124221China AVIC Jonhon Optronic Technology Co. Ltd.Luoyang 471003China State Key Laboratory of Structural Analysis for Industrial Equipment and Department of Engineering Mechanics Dalian University of TechnologyDalian 116024China Department of Architecture and Civil Engineering City University of Hong KongTat Chee AvenueKowloonHong KongChina

Large deflection postbuckling responses of metamaterial cylindrical shells perforated by arrayed circular holes are investigated through a newly proposed theoretical model incorporating with finite element method and *** triggering of an unusual pattern transformation under compressive load(that shows special hyperelastic metamaterial characteristics)contributes to the particularity of the postbucklingmodes,in which the axisymmetric waisted and non-axisymmetric postbuckling configurations of perforated cylindrical shells are *** transformations of postbucking modes are mainly affected by global outline sizes of the shell and local geometrical parameters of *** structural load-carrying capacity for the waisted postbuckling response suffers a sudden drop and recovers when the holes ***,the shell would undergo a sustained fall off under non-axisymmetric postbuckling *** negative Poisson’s ratio induced by pattern transformation plays a key role and a critical effective threshold value exists,inducing the waisted postbuckling *** revealed principles would be of benefit for achieving a controllable structural stability that is usually difficult to implement on those conventional structures.

关键词： Cylindrical shell Negative Poisson’s ratio Postbuckling Waisted deformation

Linearly Compact Difference Scheme for the Two-Dimensional Kuramoto-Tsuzuki Equation with the Neumann Boundary Condition

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Annals of Applied Mathematics 2023年第1期39卷 49-78页

作者： qifeng zhang Lu zhang Department of Mathematics Zhejiang Sci-Tech UniversityHangzhouZhejiang 310018China School of Mathematics and Statistics Xuzhou University of TechnologyXuzhouJiangsu 221018China

In this paper,we analyze and test a high-order compact difference scheme numerically for solving a two-dimensional nonlinear Kuramoto-Tsuzuki equation under the Neumann boundary condition.A three-level average technique is utilized,thereby leading to a linearized difference *** main work lies in the pointwise error estimate in H^(2)-*** optimal fourth-order convergence order is proved in combination of induction,the energy method and the embedded ***,we establish the stability of the difference scheme with respect to the initial value under very mild condition,however,does not require any step ratio *** numerical examples with/without exact solutions under diverse cases are implemented to validate the theoretical results.

关键词： Kuramoto-Tsuzuki equation compact difference scheme pointwise error estimate stability numerical simulation

Tribological and mechanical behaviours of resin-based friction materials based on microcrack filling

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Biosurface and Biotribology 2023年第1期9卷 1-8页

作者： Lekai Li Guixiong Gao Jin Tong Jian Zhuang Wei Song Yunhai Ma Guoqin Liu Feipeng Cao Shengwang Yuan qifeng zhang Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchunChina

To enhance the friction performance of resin-based friction materials,five types of specimens with different polymer ether ketone(PEEK)contents were fabricated and their physiomechanical behaviours were tested and,their tribological properties were investigated using a JF150F-II constant-speed *** was found that the addition of PEEK had a positive influence on the properties of the friction materials,and sample FM-3(the shorthand of‘Friction Materials-3’,containing 2 wt%PEEK)exhibited improved friction performance with a fade ratio and recovery ratio of 8.6%and 101.1%*** all samples,FM-4(the shorthand of‘Friction Materials-4’,con-taining 3 wt%PEEK)had the lowest specific wear rate with a value of 0.622×10^(−7)cm^(3)(N⋅m)^(−1)at 350℃.The PEEK can fill the microcracks in the composite at a high tem-perature and can also cover the hard abrasive particles to prevent them from directly damaging the *** findings from this study afford a foundation for studies to further improve the properties of resin-based friction materials.

关键词： fade ratios friction materials PEEK recovery ratios specific wear rate

Electrophoretic Deposition of Titanium Oxide Nanoparticle Films for Dye-Sensitized Solar Cell Applications

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Materials Sciences and Applications 2011年第10期2卷 1427-1431页

作者： Jason Bandy qifeng zhang Guozhong Cao Department of Materials Science and Engineering University of Washington Seattle USA.

Films of titanium oxide nanocrystalline particles (P25) were deposited using an electrophoretic deposition. The film’s characteristics were tuned for applications in dye-sensitized solar cells. Electrophoretic deposition allows control of film characteristics such as porosity and thickness by changing deposition parameters, such as the electric field and deposition time. To increase the efficiency of the dye-sensitized solar cells with films created using electrophoretic deposition, the problem of an electrolyte contamination in the film, which occurred during deposition, was addressed. With the proper chemical post treatment, efficiency of 2.93% with fill factor of 0.55 was obtained when the films were annealed at 450℃. A low annealing temperature of 150℃ resulted in efficiencys of 1.99% with fill factor of 0.68. When the P25 was replaced by hydrothermally fabricated titanium oxide nanocrystalline particles, efficiency of 4.91% with fill factor of 0.55 was obtained.

关键词： Dye-Sensitized Solar Cells Electrophoretic Deposition TiO2 Nanoparticles

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深海小型爬行机器人研究现状

机器人 2019年第2期41卷 250-264页

作者：张奇峰张运修张艾群中国科学院沈阳自动化研究所机器人学国家重点实验室辽宁沈阳110016 中国科学院大学北京100049

通过充分的文献调研和总结,根据海上作业形式对典型的深海小型爬行机器人分成3类进行了综述.对影响深海小型爬行机器人发展的海底运动适应性、导航定位、能源供给以及轻量级机械手4项关键技术进行了总结和分析,并对其未来的发展趋势进... 详细信息

通过充分的文献调研和总结,根据海上作业形式对典型的深海小型爬行机器人分成3类进行了综述.对影响深海小型爬行机器人发展的海底运动适应性、导航定位、能源供给以及轻量级机械手4项关键技术进行了总结和分析,并对其未来的发展趋势进行了展望.

关键词：深海小型爬行机器人海底自适应行走导航定位能源供给轻量级机械手