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The Crank-Nicolson/Explicit Scheme for the Natural Convection Equations with Nonsmooth Initial Data

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Advances in Applied Mathematics and Mechanics 2020年第6期12卷 1481-1519页

作者： Jinting Yang Hongxia Liang tong zhang School of Mathematics&Information Science Henan Polytechnic UniversityJiaozuoHenan 454003China

In this article,a Crank-Nicolson/Explicit scheme is designed and analyzed for the time-dependent natural convection problem with nonsmooth initial *** Galerkin finite element method(FEM)with stable MINI element is used for the velocity and pressure and linear polynomial for the *** time discretization is based on the Crank-Nicolson *** order to simplify the computations,the nonlinear terms are treated by the explicit *** advantages of our numerical scheme can be list as follows:(1)The original problem is split into two linear subproblems,these subproblems can be solved in each time level in parallel and the computational sizes are smaller than the origin one.(2)A constant coefficient linear discrete algebraic system is obtained in each subproblem and the computation becomes *** main contributions of this work are the stability and convergence results of numerical solutions with nonsmooth initial ***,some numerical results are presented to verify the established theoretical results and show the performances of the developed numerical scheme.

关键词： Natural-Convection equations Crank-Nicolson/Explicit scheme nonsmooth initial data error estimates

Microstructures and mechanical properties of WE43 magnesium alloy prepared by friction stir processing

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Rare Metals 2020年第11期39卷 1267-1272页

作者： Jin Li Da-tong zhang Fang Chai Wen zhang National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou510640China

Mg-3.99Y-3.81Nd-0.53 Zr(WE43)casting alloy was subjected to single-pass friction stir processing(FSP)at a constant processing speed of 60 mm-min^(-1)and various rotation speeds of 400,800,1200,and 1500 r·min^(-1),and microstructures and mechanical properties of the experimental materials were *** results in the generation of fine-grained microstructure,and fundamental breakage and dissolution of the coarse second *** the rotation speeds increasing,the average grain size of the FSP specimen in the stir zone first decreases and then increases,and the finest microstructure(~2μm)was prepared at the rotation speed of 800 r·min^(-1).Owing to the finer and more uniform microstructure,the mechanical properties of WE43 alloy after FSP are significantly *** variation tendency of the tensile properties is consistent with the change of the grain *** maximum tensile strength,elongation,and average microhardness of the FSP WE43 alloy obtained at 800 r·min^(-1)are 290 MPa,17.2%,and HV92.9,*** fracture morphology shows that small dimples can be observed on the FSP specimens,while the as-cast alloy fails through cleavage fracture.

关键词： WE43 magnesium alloy Friction stir processing Microstructure mechanical property Rare earth elements

A Stabilized Finite Element Method for Non-Stationary Conduction-Convection Problems

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Advances in Applied Mathematics and Mechanics 2011年第2期3卷 239-258页

作者： Ke Zhao Yinnian He tong zhang Faculty of Science Xi’an Jiaotong UniversityXi’an 710049ShanxiChina. School of Mathematics&Information Science Henan Polytechnic UniversityJiaozuo 454003HenanChina.

This paper is concerned with a stabilized finite element method based on two local Gauss integrations for the two-dimensional non-stationary conductionconvection equations by using the lowest equal-order pairs of finite *** method only offsets the discrete pressure space by the residual of the simple and symmetry term at element level in order to circumvent the inf-sup *** stability of the discrete scheme is derived under some regularity ***timal error estimates are obtained by applying the standard Galerkin ***,the numerical illustrations agree completely with the theoretical expectations.

关键词： Non-stationary conduction-convection equations finite element method stabilized method stability analysis error estimate

Boosted cascade of scattered rectangle features for object detection

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Science in China(Series F) 2009年第2期52卷 236-243页

作者： zhang WeiZe tong RuoFeng DONG JinXiang Institute of Artificial Intelligence Zhejiang University Hangzhou 310027 China

This paper presents a variant of Haar-Iike feature used in Viola and Jones detection framework, called scattered rectangle feature, based on the common-component analysis of local region feature. Three common components, feature filter, feature structure and feature form, are extracted without concerning the details of the studied region features, which cast a new light on region feature design for specific applications and requirements： modifying some component（s） of a feature for an improved one or combining different components of existing features for a new favorable one. Scattered rectangle feature follows the former way, extending the feature structure component of Haar-like feature out of the restriction of the geometry adjacency rule, which results in a richer representation that explores much more orientations other than horizontal, vertical and diagonal, as well as misaligned, detached and non-rectangle shape information that is unreachable to Haar-Iike feature. The training result of the two face detectors in the experiments illustrates the benefits of scattered rectangle feature empirically; the comparison of the ROC curves under a rigid and objective detection criterion on MIT＋CMU upright face test set shows that the cascade based on scattered rectangle features outperforms that based on Haar-Iike features.

关键词： Haar-like feature feature filter feature structure feature form cascade

Driving lithium to deposit inside structured lithium metal anodes:A phase field model

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Journal of Energy Chemistry 2022年第10期31卷 285-291,I0007页

作者： Rui zhang Xin Shen Hao-Tian Ju Jun-Dong zhang Yu-tong zhang Jia-Qi Huang Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Lithium metal anode is one of the most important anode materials for next-generation high-specificenergy secondary *** lithium metal anodes have received extensive attention in the development of practical lithium metal *** of driving lithium metal to deposit inside the pores of structured lithium metal anodes have always been one of the most concerned issues,especially for highly conductive *** electrochemical phase field theory with galvanostatic lithium plating process is employed in this work,the mechanism that illustrates the preference of lithium metal to deposit at the top of the framework structure has been revealed,and through the simulation analysis of various regulating strategies,the strategies that can efficiently drive lithium to deposit inside structured pores are *** work presents the theoretical calculation and analysis methods that can be used for the rational design of lithium metal batteries.

关键词： Lithium metal batteries Lithium metal anodes Phase field theory Finite element method Deposition sites Gradient design Diffusion coefficient

Exact Geometric Relationships, Symmetry Breaking and Structural Stability for Single-Walled Carbon Nanotubes

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Nano-Micro Letters 2011年第4期3卷 228-235页

作者： tong zhang Ze Shuai Yuan Li Hao Tan Research Center for Solid Mechanics Beihang University

We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.

关键词： Geometry Structural Stability Symmetry Breaking Fractal Dimension

Fast registration of multisource three-dimensional city models in GeoGlobe

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International Journal of Digital Earth 2015年第4期8卷 293-311页

作者： Jing Chen tong zhang Shutao Dong Bingxiong Xie State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

We address the registration problem of multisource three-dimensional(3D)human-made buildings with remote sensing images and the earth’s surface in the context of virtual *** include fast transformation of 3D coordinates with different reference systems as well as the efficient use of original model information for rigorous and accurate model *** paper introduces a novel fast and scalable registration approach that can establish correspondences between heterogeneous external 3D city models and images/terrain surfaces of virtual globes in an efficient and accurate *** approach utilizes the projected 3D feature information of 3D city models to develop robust coordinate transformation and reliable model registration *** proposed approach builds a solid foundation for the fusion of multisource geospatial data in a united virtual globe reference *** report experimental results of online registration tasks for up to over 13K buildings in an integrated 3D virtual globe platform,namely,GeoGlobe.

关键词： registration virtual globes three-dimension city models coordinate transformation GeoGlobe

Fluorescent Recognition of Small Organic Molecules Based on Supramolecular Aggregation/Deaggregation of Planar Cu(Ⅱ)Coordination Complex

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Chinese Journal of Chemistry 2015年第4期33卷 425-430页

作者： Liang Hao tong zhang Ge Chang Hui Li Key Laboratory of Clusters Science of Ministry of Education Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of ChemistryBeijing Institute of TechnologyBeijing 100081China

A Cu(II)coordination complex(1)with Schiff ligand derived from diaminomaleonitrile was synthesized and characterized,in which the ligand is rigid,planar and *** complex 1 displays an interesting fluorescent property relative to solvents which can be turned-on by CH_(2)Cl_(2) and CHCl_(3) solvent *** mechanism of this selective fluorescence emission has been studied based on the crystal structure and the spectrum *** tuning on and off fluorescence of complex 1 can be controlled by the process of supramolecular aggregation/deag-gregation in different solvents.

关键词： fluorescence recognition crystal structure diaminomaleonitrile Cu(Ⅱ)coordination complex supramolecular aggregation/deaggregation

miR-222 targets ACOX1, promotes triglyceride accumulation in hepatocytes

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Hepatobiliary & Pancreatic Diseases International 2019年第4期18卷 360-365页

作者： Jing-Jie Wang Yi-tong zhang Yu Jen Tseng Jun zhang Department of Digestive Diseases Huashan Hospital Fudan University

Background:Non-alcoholic fatty liver disease(NAFLD)is one of the most prevalent chronic liver ***,the exact pathogenesis of NAFLD remains to be *** the association with tumors and cardiovascular diseases,the role of miR-222 in NAFLD remains *** present study was to investigate the role of miR-222 in ***:Wild-type C57BL/6 mice were fed a high-fat diet for 12 weeks to induce *** human liver cell line(L02)was cultured with free fatty acid(FFA)-containing medium to stimulate cell *** mRNA levels of miR-222 and acyl Coenzyme A xidase 1(ACOX1)were detected by quantitative-PCR(Q-PCR).The prediction of ACOX1 as the target gene for miR-222 was conducted via *** overexpression or inhibition of miR-222 was mediated by miR-222 mimics or antagomir,and intracellular triglyceride levels were measured using a triglyceride *** reporter assays verified ACOX1 as the target gene for ***:miR-222 was significantly elevated in both the in vivo and in vitro NAFLD *** of miR-222 significantly increased triglyceride content in the L02 cells,while inhibition of miR-222 expression restricted the accumulation of *** of miR-222 significantly inhibited ACOX1 *** transfection assays verified that ACOX1 3-UTR luciferase reporter activity could be inhibited by miR-222 ***:The present study suggested that miR-222 promotes the accumulation of triglycerides by inhibiting ACOX1.

关键词： ACOX1 Hepatocyte steatosis miR-222 NAFLD β-hydroxybutyrate