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Journal of Computational Mathematics 2024年第4期42卷 911-931页

作者： yuping zeng Mingchao Cai Liuqiang Zhong School of Mathematics Jiaying UniversityMeizhou 514015China Department of Mathematics Morgan State University1700 E Cold Spring LnBaltimoreMD 21251USA School of Mathematical Science South China Normal UniversityGuangzhou 520631China

A mixed finite element method is presented for the Biot consolidation problem in *** precisely,the displacement is approximated by using the Crouzeix-Raviart nonconforming finite elements,while the fuid pressure is approximated by using the node conforming finite *** well-posedness of the fully discrete scheme is established,and a corresponding priori error estimate with optimal order in the energy norm is also *** experiments are provided to validate the theoretical results.

关键词： Poroelasticity Nonconforming finite element Inf-sup condition A priori error estimate

A Priori and a Posteriori Error Estimates for H(div)-Elliptic Problemwith Interior Penalty Method

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Communications in Computational Physics 2013年第8期14卷 753-779页

作者： yuping zeng Jinru Chen Jiangsu Key Laboratory for NSLSCS School of Mathematical SciencesNanjing Normal UniversityNanjing 210023China

In this paper,we propose and analyze the interior penalty discontinuous Galerkin method for H(div)-elliptic *** optimal a priori error estimate in the energy norm is *** addition,a residual-based a posteriori error estimator is *** estimator is proved to be both reliable and efficient in the energy *** numerical testes are presented to demonstrate the effectiveness of our method.

关键词： Discontinuous Galerkin method H(div)-elliptic problem a priori error estimate a posteriori error estimate

A POSTERIORI ERROR ESTIMATES FOR A MODIFIED WEAK GALERKIN FINITE ELEMENT APPROXIMATION OF SECOND ORDER ELLIPTIC PROBLEMS WITH DG NORM

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Journal of Computational Mathematics 2021年第5期39卷 755-776页

作者： yuping zeng Feng Wang Zhifeng Weng Hanzhang Hu School of Mathematics Jiaying UniversityMeizhou 514015China Jiangsu Key Laboratory for NSLSCS School of Mathematical SciencesNanjing Normal UniversityNanjing 210023China Fujian Province University Key Laboratory of Computational Science School of Mathematical SciencesHuaqiao UniversityQuanzhou 362021China

In this paper,we derive a residual based a posteriori error estimator for a modified weak Galerkin formulation of second order elliptic *** prove that the error estimator used for interior penalty discontinuous Galerkin methods still gives both upper and lower bounds for the modified weak Galerkin method,though they have essentially different bilinear *** precisely,we prove its reliability and efficiency for the actual error measured in the standard DG *** further provide an improved a priori error estimate under minimal regularity assumptions on the exact *** results are presented to verify the theoretical analysis.

关键词： Modified weak Galerkin method A posteriori error estimate A medius error analysis

A PRIORI AND A POSTERIORI ERROR ESTIMATES OF A WEAKLY OVER-PENALIZED INTERIOR PENALTY METHOD FOR NON-SELF-ADJOINT AND INDEFINITE PROBLEMS

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Journal of Computational Mathematics 2014年第3期32卷 332-347页

作者： yuping zeng Jinru Chen Feng Wang Yanxia Meng School of Mathematics Jiaying University Meizhou 513015 China Jiangsu Key Laboratory for NSLSCS School of Mathematical Sciences Nanjing Normal University Nanjing 210023 China

In this paper, we study a weakly over-penalized interior penalty method for non-self- adjoint and indefinite problems. An optimal a priori error estimate in the energy norm is derived. In addition, we introduce a residual-based a posteriori error estimator, which is proved to be both reliable and efficient in the energy norm. Some numerical testes are presented to validate our theoretical analysis.

关键词： Interior penalty method Weakly over-penalization Non-self-adjoint and indefinite A priori error estimate A posteriori error estimate.

Microstructure and Mechanical Properties of Cu Matrix Composites Reinforced by TiB_(2)/TiN Ceramic Reinforcements

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Acta Metallurgica Sinica(English Letters) 2020年第12期33卷 1609-1617页

作者： Jinwei Yin Peilong Zhou Hanqin Liang Dongxu Yao Yongfeng Xia Kaihui Zuo yuping zeng State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Cu matrix composites reinforced by TiB_(2)/TiN ceramic reinforcements(Cu/TBN composites)were prepared by hot pressing *** to the hot pressing,Cu/TiB_(2)/TiN composite powders(CTBN powders),which were used as the starting materials of Cu/TBN composites,were fabricated by self-propagating high-temperature synthesis *** CTBN particles were found to be in a special core–shell structure with a Cu–Ti alloy core and a TiB_(2)/TiN ceramic *** test results presented obvious improvements in mechanical *** highest ultimate tensile strength reached up to 297 MPa,77 MPa higher than that of *** the highest hardness reached up to 70.7 HRF,15.7 HRF higher than that of Cu.A comparative study indicated that the core–shell structured particles could bring about more obvious strengthening eff ect than the traditional irregularly shaped particles,which was due to the improved Cu/ceramics interfacial bonding,the linkage strengthening effect of both TiB_(2) and TiN,and higher load bearing ability of the core–shell structured reinforcements.

关键词： Cu matrix composite Microstructure Mechanical property Self-propagating high-temperature synthesis(SHS)

Porous SiC ceramics fabricated by quick freeze casting and solid state sintering

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Progress in Natural Science:Materials International 2017年第3期27卷 380-384页

作者： Feng Wang Jinwei Yin Dongxu Yao Yongfeng Xia Kaihui Zuo yuping zeng Shanghai Institute of Ceramics Chinese Academy of Sciences

Porous SiC ceramics with uniform microstructure were fabricated by quick freezing in liquid nitrogen and solid state ***(vinyl alcohol)(PVA) was added as binder and pore morphology controller in this *** microstructure and mechanical properties of porous SiC ceramics could be controlled by the composition of the aqueous *** solid content of the slurries and PVA content impacted on the pore structures and mechanical properties of the porous SiC *** solid content of slurries and PVA content varied from 60 to 67.5 wt%and 2-6 wt%,***,the grain morphology of ceramics was also tailored by changing the sintering temperature from 2050 to 2150 ℃.Porous SiC ceramics with an average porosity of 42.72%,flexural strength of 59.28 MPa were obtained at 2150 ℃ from 67.5 wt% slurries with 2 wt% PVA.

关键词： SiC Quick freezing Liquid nitrogen Uniform pore structure Solid state sintering

Tape Casting of Al_2O_3-TiB_2/Al_2O_3-Nano-TiC Multilayer Composites

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Journal of Materials Science & Technology 1997年第4期13卷 324-326页

作者： yuping zeng Dongliang JIANG Shouhong TAN and Jingkun GUO(Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China) Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China

Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃

关键词： Nano TiB Al Tape Casting of Al2O3-TiB2/Al2O3-Nano-TiC Multilayer Composites TiC

Influence of Yb_2O_3-MgO on Mechanical Properties and Thermal Conductivity of Silicon Nitride Ceramics via Gas Pressure Sintering

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China's Refractories 2015年第3期24卷 34-39页

作者： LIN Sen YAO Dongxu XIA Yongfeng ZUO Kaihui YIN Jinwei zeng yuping State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of Sciences Graduate School of Chinese Academy of Sciences

In this work,Yb2O3 and Mg O were used as sintering aids in preparing silicon nitride ceramics by gas pressure sintering（ 0. 6 MPa N2atmosphere） to investigate how the amounts of Yb2O3- Mg O influence the mechanical properties and thermal conductivity of silicon nitride ceramics. The total contents of Yb2O3- Mg O added were 1 mol%,2 mol%,4 mol%,6 mol%,8 mol%,10 mol%,12 mol%,14 mol%,keeping the Yb2O3-Mg O molar ratio of 1 ∶ 1 steadily. Curves of the relative density,thermal conductivity and bending strength plotted against the aids content present a ‘mountain＇shape with a maximum at nearly 10 mol% aids. The fracture toughness increased with the amounts of additives up to10 mol% and decreased slightly thereafter. The mechanical properties and thermal conductivity were almost proportional to the amount of the additives before10 mol%. When the content of aids exceeded 10 mol%,it would weaken the mechanical properties and thermal conductivity of the ceramics. The optimum content of Yb2O3- Mg O was 10 mol% by gas pressure sintering（ 0. 6MPa） at 1 850 ℃ for 4 h,which led to a relative density of 98. 9%,a flexural strength of（ 966 ± 38）MPa as well as a fracture toughness of（ 6. 29 ± 0. 29）MPa·m1 /2and thermal conductivity of 82 W /（ m·K）.

关键词： silicon nitride sintering mechanical properties thermal conductivity

A New Preconditioner with Two Variable Relaxation Parameters for Saddle Point Linear Systems with Highly Singular(1,1) Blocks

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American Journal of Computational Mathematics 2011年第4期1卷 252-255页

作者： yuping zeng Chenliang Li 不详

In this paper, we provide new preconditioner for saddle point linear systems with (1,1) blocks that have a high nullity. The preconditioner is block triangular diagonal with two variable relaxation paremeters and it is extension of results in [1] and [2]. Theoretical analysis shows that all eigenvalues of preconditioned matrix is strongly clustered. Finally, numerical tests confirm our analysis.

关键词： Saddle Point Linear Systems Block Triangular Preconditioner Krylov Subspace Methods

Effect of Pore Size on Properties of Highly Porous Silica Ceramic Foams for Heat Insulation

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China's Refractories 2020年第4期29卷 6-9页

作者： DU Zhongpei YAO Dongxu XIA Yongfeng ZUO Kaihui YIN Jinwei LIANG Hanqin zeng yuping State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Highly porous silica ceramics with different pore sizes were fabricated by adjusting the mixed surfactants *** effect of the pore size on the cold compressive strength and the thermal conductivity of the ceramics was *** results show that the smaller pore size can improve the compressive strength and the thermal *** the mixed surfactants addition increasing from 0.1 mass%to 0.4 mass%,the porosity is close,in the range of 88.10%-88.31%,and the average pore size decreases from 190μm to 97μm;the compressive strength is enhanced from 2.97 MPa to 3.55 MPa;and the thermal conductivity decreases from 0.104 W·m-1·K-1 to 0.089 W·m-1·K-1.

关键词： mixed surfactants pore size high porosity silica foams direct foaming thermal conductivity