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Recent progress in high temperature permanent magnetic materials

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Rare Metals 2013年第5期32卷 431-440页

作者： Cheng-Bao Jiang shi-zhong An School of Materials Science and Engineering Beihang University

Permanent magnetic materials capable of operating at high temperature up to 500℃ have wide potential applications in fields such as aeronautics, space, and electronic cars. SmCo alloys are candidates for high temperature applications, since they have large magnetocrystalline anisotropy field （6-30 T）, high Curie temperature （720-920℃）, and large energy product （〉200 kJ.m-3） at room temperature. However, the highest service temperature of commercial 2：17 type SmCo magnets is only 300℃, and many efforts have been devoted to develop novel high temperature permanent magnets. This review focuses on the development of three kinds of SmCo based magnets： 2：17 type SmCo magnets, nanocrystalline SmCo magnets, and nanocomposite SmCo magnets. The oxidation protection, including alloying and surface modification, of high temperature permanent magnets is discussed as well.

关键词： Magnetic materials Sm-Co alloys Permanent magnets High temperature

CONSTRAINED QUADRILATERAL NONCONFORMING ROTATED Q1 ELEMENT

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Journal of Computational Mathematics 2005年第6期23卷 561-586页

作者： Jun Hu zhong-ci shi LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

In this paper, we define a new nonconforming quadrilateral finite element based on the nonconforming rotated Q1 element by enforcing a constraint on each element, which has only three degrees of freedom. We investigate the consistency, approximation, superclose property, discrete Green＇s function and superconvergence of this element. Moreover, we propose a new postprocessing technique and apply it to this element. It is proved that the postprocessed discrete solution is superconvergent under a mild assumption on the mesh.

关键词： Constrained Nonconforming Rotated Q1 element Superconvergence Postprocess

A NOTE ON THE QUADRILATERAL MESH CONDITION RDP(N,ψ)

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Journal of Computational Mathematics 2007年第1期25卷 27-30页

作者： Dongyang shi zhong-Ci shi Jingzhu Wu Department of Mathematics Zhengzhou University Zhengzhou 450052 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

The main aim of this paper is to show that the quadrilateral mesh condition RDP（N, ψ） is only sufficient but not necessary for the optimal order error estimate of the Q isoparametric element in the Hi norm.

关键词： Isoparametric finite element Optimal order error estimate Quadrilateral meshcondition.

α-clustering effect on flows of direct photons in heavy-ion collisions

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Nuclear Science and Techniques 2021年第6期32卷 122-132页

作者： Chen-zhong shi Yu-Gang Ma Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China University of the Chinese Academy of Sciences Beijing 100080China

In this study,we reconstruct theγ-photon energy spectrum,which is in good agreement with the experimental data of ^(86)Kr+^(12)C at E/A=44 Me V within the framework of the modified EQMD *** directed and elliptic flows of free protons and direct photons were investigated by considering theα-clustering structure of ^(12)*** with free protons,direct photon flows provide clearer information about the early stage of a nuclear *** difference in the collective flows between different configurations of ^(12)C is observed in this *** indicates that the collective flows of direct photons are sensitive to the initial ***,theγbremsstrahlung process might be taken as an alternative probe to investigate theα-clustering structure in a light nucleus from heavy-ion collisions within the Fermienergy region.

关键词： Nuclear reaction Direct photon Collective flow α-clustering configuration

A relaxation scheme for a multi-class Lighthill-Whitham-Richards traffic flow model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第12期10卷 1835-1844页

作者： Jian-zhong CHEN zhong-ke shi Yan-mei HU College of Automation Northwestern Polytechnical University Xi 'an 710072 China College of Science Chang 'an University Xi 'an 710064 China

We present a high-resolution relaxation scheme for a multi-class Lighthill-Whitham-Richards (MCLWR) traffic flow model. This scheme is based on high-order reconstruction for spatial discretization and an implicit-explicit Runge-Kutta method for time integration. The resulting method retains the simplicity of the relaxation schemes. There is no need to involve Riemann solvers and characteristic decomposition. Even the computation of the eigenvalues is not required. This makes the scheme particularly well suited for the MCLWR model in which the analytical expressions of the eigenvalues are difficult to obtain for more than four classes of road users. The numerical results illustrate the effectiveness of the presented method.

关键词： Relaxation scheme Multi-class LWR model Traffic flow CWENO reconstruction Implicit-explicit Runge-Kutta

P1-NONCONFORMING QUADRILATERAL FINITE VOLUME ELEMENT METHOD AND ITS CASCADIC MULTIGRID ALGORITHM FOR ELLIPTIC PROBLEMS

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Journal of Computational Mathematics 2006年第1期24卷 59-80页

作者： Hong-ying Man zhong-ci shi LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China Department of Mathematics Beijing institute of Technology Beijing 100081 China

In this paper, we discuss the finite volume element method of P1-nonconforming quadrilateral element for elliptic problems and obtain optimal error estimates for general quadrilateral partition. An optimal cascadic multigrid algorithm is proposed to solve the non-symmetric large-scale system resulting from such discretization. Numerical experiments are reported to support our theoretical results.

关键词： finite volume element method cascadic multigrid Elliptic problems

Rejuvenation Heat Treatment of the Second-Generation Single-Crystal Superalloy DD6

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Acta Metallurgica Sinica(English Letters) 2015年第10期28卷 1278-1285页

作者： Zhen-Xue shi shi-zhong Liu Jia-Rong Li Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The second-generation single-crystal superalloy DD6 with [001] orientation was prepared by screw selecting method in the directionally solidified furnace. The long-term aging of the alloy after full heat treatment was performed at1100 °C for 400 h. Then the rejuvenation heat treatment 1300 °C/4 h/AC ？ 1120 °C/4 h/AC ？ 870 °C/24 h/AC was carried out. The stress rupture properties were investigated at 760 °C/800 MPa, 850 °C/550 MPa, 980 °C/250 MPa and1100 °C/140 MPa after different heat treatments. The microstructures of the alloy at different conditions were studied by SEM. The results show that c0 phase of the alloy became very irregular and larger after long-term aging at 1100 °C for 400 h. A very small amount of needle-shaped TCP phase precipitated in the dendrite core. The coarsened c0 phase and TCP phase dissolved entirely after rejuvenation heat treatment. The microstructure was restored and almost same with the original microstructure. The stress rupture life of the alloy decreased in different degrees at various test conditions after long-term aging. The stress rupture life of the alloy after rejuvenation heat treatment all restores to the original specimen more than 80%at different conditions. The microstructure degradation of the alloy during long-term aging includes coarsening of the c0 phase,P-type raft and precipitation of TCP phase, which results in the degeneration of stress rupture property. The rejuvenation heat treatment succeeds in restoring the original microstructure and stress rupture properties of the alloy.

关键词： Single-crystal superalioy DD6 Rejuvenation heat treatment Stress rupture properties

Effective properties of coated fibrous piezoelectric composites with spring-type interfaces under anti-plane mechanical and in-plane electrical loads

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Science China(Physics,Mechanics & Astronomy) 2016年第10期59卷 58-65页

作者： Yin shi YongPing Wan Zheng zhong School of Aerospace Engineering and Applied Mechanics Tongji University

In this paper,we investigate the effective properties of three-phase(matrix/coating/fiber)cylindrical piezoelectric composites with imperfect interfaces under anti-plane mechanical and in-plane electrical *** using the electromechanically coupling spring-type interface model and the generalized self-consistent method(GSM),we analytically derived the effective electroelastic *** present solutions include as special cases the three-phase cylindrical piezoelectric composites with perfect interfaces as well as the two-phase(matrix/fiber)case with imperfect or perfect *** calculations are graphically shown to demonstrate dependence of the effective moduli on the interfacial *** particular size-dependent characteristic due to the interfacial imperfection is also discussed.

关键词： effective moduli piezoelectric composites spring-type interface generalized self-consistent method size effect

MATHEMATICAL ANALYSIS FOR QUADRILATERAL ROTATED Q_1 ELEMENT Ⅱ: POINCARE INEQUALITY AND TRACE INEQUALITY

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Journal of Computational Mathematics 2003年第3期21卷 277-286页

作者： Ping-bing Ming zhong-ci shi Institute of Computational Mathematics Chinese Academy of Sciences Beijing 100080 China

This is the second part of the paper for the mathematical study of nonconforming rotated Q1 element (NRQ1 hereafter) on arbitrary quadrilateral meshes. Some Poincare Inequalities are proved without assuming the quasi-... 详细信息

关键词： Quadrilateral rotated Q1 element Poincare inequality Trace inequality.