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A compact streamfunction-velocity scheme for the 2-D unsteady incompressible Navier-Stokes equations in arbitrary curvilinear coordinates

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Journal of Hydrodynamics 2019年第4期31卷 827-839页

作者： jian-xin qiu Bo Peng Zhen-fu Tian Department of Mechanics and Engineering Science Fudan University Shanghai 200433 China

A streamfunction-velocity formulation-based compact difference method is suggested for solving the unsteady incompressible Navier-Stokes equations in the arbitrary curvilinear coordinates, in which the stream function and its first derivatives as the unknown variables are utilized. Numerical examples, involving the boundary layer problem, a constricted channel flow, driven polar cavity flow and trapezoidal cavity flow problem, are solved by the present method. Numerical results demonstrate the accuracy of the proposed scheme and exhibit the numerical capability to simulate the flow problems on geometries beyond rectangular. For driven polar cavity flow problem, the results show that the flow for Re = 5 000 is not steady but time-periodic, and the critical Reynold number (Rec) for the occurrence of a Hopf bifurcation is given.

关键词： Streamfunction-velocity formulation arbitrary curvilinear coordinates compact scheme unsteady incompressible flow

A review of multiple optical vortices generation: methods and applications

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Frontiers of Optoelectronics 2019年第1期12卷 52-68页

作者： Long zhu jian WANG Wuhan National Laboratory for Optoelectronics School of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan 430074China

Optical vortices carrying orbital angular momentum(OAM)have attracted increasing interest in recent *** vortices have seen a variety of emerging applications in optical manipulation,optical trapping,optical tweezers,optical vortex knots,imaging,microscopy,sensing,metrology,quantum information processing,and optical *** various optical vortices enabled applications,the generation of multiple optical vortices is of great *** this review article,we focus on the methods of multiple optical vortices generation and its *** review the methods for generating multiple optical vortices in three cases,i.e.,1-to-N collinear OAM modes,1-to-N OAM mode array and N-to-N collinear OAM *** applications of multiple OAM modes in optical communications and non-communication areas are *** trends,perspectives and opportunities are also discussed.

关键词： optical communications optical vortices orbital angular momentum (OAM) mode-division multiplexing (MDM) mode multicasting

Microstructure and piezoelectric properties of K_(5.70)Li_(4.07)Nb_(10.23)O_(3)0-added K_(0.5)Na_(0.5)NbO_(3) ceramics

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Journal of Advanced Ceramics 2014年第2期3卷 147-154页

作者： Xuming PANG Jinhao qiu Kongjun zhu State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical Engineering Nanjing Tech UniversityNanjing 210009China

Lead-free piezoelectric ceramics K_(0.5)Na_(0.5)NbO_(3)-xmol%K_(5.70)Li_(4.07)Nb_(10.23)O_(3)0(x=0-2.5,KNN-xmol%KLN)were prepared by conventional sintering *** phase structure and electrical properties of KNN ceramics were investigated as a function of KLN *** results showed that small amount of KLN introduced into the lattice formed a single phase perovskite *** KLN modification lowered the phase transition temperature of orthorhombic-tetragonal(T_(O-T))and increased the Curie temperature(T_(C)).Some abnormal coarse grains were formed in a matrix when the content of KLN was relatively low(1 mol%).However,normally grown grains were only observed when the sintering aid content was increased to 2 mol%.Proper content of KLN decreased the amount of defects,thus the remanent polarization increased and the coercive field decreased markedly,and the sinterability of the KNN ceramics was simultaneously improved with significant increase of piezoelectric properties.

关键词： ceramics sintering aid phase transformation electrical properties

HERMITE WENO SCHEMES WITH STRONG STABILITY PRESERVING MULTI-STEP TEMPORAL DISCRETIZATION METHODS FOR CONSERVATION LAWS

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Journal of Computational Mathematics 2017年第1期35卷 52-73页

作者： Xiaofeng Cai Jun zhu jianxian qiu School of Mathematical Sciences Xiamen University Xiamen Fujian 361005 China College of Science Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu 210016 China School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computation Xiamen University Xiamen Fujian 361005 China

Based on the work of Shu [SIAM J. Sci. Stat. Comput, 9 （1988）, pp.1073-1084], we construct a class of high order multi-step temporal discretization procedure for finite volume Hermite weighted essential non-oscillatory （HWENO） methods to solve hyperbolic conservation laws. The key feature of the multi-step temporal discretization procedure is to use variable time step with strong stability preserving （SSP）. The multi-step tem- poral discretization methods can make full use of computed information with HWENO spatial discretization by holding the former computational values. Extensive numerical experiments are presented to demonstrate that the finite volume HWENO schemes with multi-step diseretization can achieve high order accuracy and maintain non-oscillatory properties near discontinuous region of the solution.

关键词： Key words: Multi-step temporal discretization Hermite weighted essentially non-oscillatoryscheme Uniformly high order accuracy Strong stability preserving Finite volume scheme.

Phase Field Modelling Allotropic Transformation of Solid Solution

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Computers, Materials & Continua 2020年第3期62卷 1289-1302页

作者： Yaochan zhu Hua qiu Hakan Hallberg Xi’an Aeronautical Polytechnic Institute Xi’an710089China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Solid Mechanics Lund University22100LundSweden

Based on multiphase field conception and integrated with the idea of vector-valued phase field,a phase field model for typical allotropic transformation of solid solution is *** model takes the non-uniform distribution of grain boundaries of parent phase and crystal orientation into account in proper way,as being illustrated by the simulation of austenite to ferrite transformation in low carbon *** is found that the misorientation dependent grain boundary mobility shows strong influence on the formation of ferrite morphology comparing with the weak effect exerted by misorientation dependent grain boundary *** evolution of various types of grain boundaries are quantitatively characterized in terms of its respective grain boundary energy *** simulated ferrite fraction agrees well with the expectation from phase diagram,which verifies this model.

关键词： Phase field allotropic transformation grain boundary misorientation

Low complexity power control approach based on MMSE detection for V-BLAST

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Journal of Systems Engineering and Electronics 2006年第4期17卷 743-749页

作者： Zhao Kun qiu Ling zhu Jinkang PCN & SS Lab Univ. of Science and Technology of China Hefei 230027 P. R. China

A low complexity Per-Antenna Power Control （PAPC） approach based on Minimum Mean Squared Error （MMSE） detection for V-BLAST is proposed in this paper. The PAPC approach is developed for minimizing the Bit Error Rate （BER） averaged over all substreams when the data throughput and the total transmit power keep constant over time. Simulation results show that the Power-controlled V-BLAST （P-BLAST） outperforms the conventional V-BLAST in terms of BER performance with MMSE detector, especially in presence of high spatial correlation between antennas. However, the additional complexity for P-BLAST is not high. When MMSE detector is adopted, the P-BLAST can achieve a comparable BER performance to that of conventional V-BLAST with Maximum Likelihood （ML） detector but with low complexity.

关键词： Vertical Bell Lab Layered Space-Time power control MINMAX minimum mean squared error aximum likelihood.

The Extension of the H^k Mean Curvature Flow in Riemannian Manifolds

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Chinese Annals of Mathematics,Series B 2014年第2期35卷 191-208页

作者： Hongbing qiu Yunhua YE Anqiang zhu School of Mathematics and Statistics Wuhan University

In this paper,the authors consider a family of smooth immersions Ft : Mn→Nn+1of closed hypersurfaces in Riemannian manifold Nn+1with bounded geometry,moving by the Hkmean curvature *** authors show that if the second fundamental form stays bounded from below,then the Hkmean curvature flow solution with finite total mean curvature on a finite time interval [0,Tmax)can be extended over *** result generalizes the extension theorems in the paper of Li(see "On an extension of the Hkmean curvature flow,*** Math.,55,2012,99–118").

关键词： Hk mean curvature flow Riemannian manifold Sobolev type inequality Moser iteration

On Boolean elements and derivations in 2-dimension linguistic lattice implication algebras

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Applied Mathematics(A Journal of Chinese Universities) 2023年第2期38卷 274-292页

作者： zhu Hua ZHAO jian-bin School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China Henan Academy of Big Data Zhengzhou UniversityZhengzhou 450001China Henan Key Laboratory of Financial Engineering Zhengzhou 450001China Key Laboratory of Big Data Analysis and Application Zhengzhou 450001China

A 2-dimension linguistic lattice implication algebra(2DL-LIA)can build a bridge between logical algebra and 2-dimension fuzzy linguistic *** this paper,the notion of a Boolean element is proposed in a 2DL-LIA and some properties of Boolean elements are *** derivations on 2DL-LIAs are introduced and the related properties of derivations are ***,it proves that the derivations on 2DL-LIAs can be constructed by Boolean elements.

关键词： derivation Boolean element Lattice implication algebra(LIA) 2-dimension linguistic lattice implication algebra(2DL-LIA) 2-dimension fuzzy linguistic information

Direct Laser Writing Facility for Fabrication of Submicron Mask

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Chinese Physics Letters 2014年第4期31卷 185-188页

作者： zhu Feng MA jian-Yong Information Optics Laboratory Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800

Direct laser writing technique has become a well-established, multi-functional and flexible method for fabricating high quality diffractive optical elements. We propose and build a maskless direct laser writing system with the ability to produce a sub-micron feature size. The high precision lithography is realized by using the astigmatic autofocus method. The minimum feature size of the system, breaking through the diffraction limit with the chromium layer, can achieve 300hm with the 405nm blue laser. A 50 x 50ram2 chromium grating mask with a period of 1 #m and line width of 300 nm is fabricated. This facility will be useful for the fabrication of large-scale submicron diffraction optical elements in the future.

关键词： Mask Direct ability