Wen ZHANG
材料科学技术（英文）
Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method, mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongatedβ-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.
关键词:
Ceramics
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null
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null
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null
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
Philosophical Magazine
The error of Equation (15b) in my article [Z.D. Zhang, Phil. Mag. 87 (2007) p.5309] in the application of the Jordan-Wigner transformation does not affect the validity of the putative exact solution, since the solution is not derived directly from that equation. Other objections of Perk's comment [J.H.H. Perk, Phil. Mag. 89 (2009) p.761] are the same as those in Wu et al.'s comments [F.Y. Wu et al., Phil. Mag. 88 (2008) p.3093; p.3103], which do not stand on solid ground and which I have sought to refute in my previous response [Z.D. Zhang, Phil. Mag. 88 (2008) p.3097]. The conjectured solution can be utilized to understand critical phenomena in various systems, whereas the conjectures are open to rigorous proof.
关键词:
3D Ising model;exact solution;conjecture;critical phenomena;ferromagnetism;magnetic phase transition;model;analyticity
中国腐蚀与防护学报
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关键词:
Physics Letters A
In a magnetic system, consistent with Griffiths analyticity requirements one can parameterize the equation of state near criticality by writing H = r(beta delta)h(theta), T = rt(theta) and the magnetization M = r(beta)m(theta), where T is measured from the critical temperature. For the insulating ferromagnet CrBr(3), the experimental data of Ho and Litster [J.T. Ho, J.D. Litster, Phys. Rev. Lett. 22 (1969) 6031 is well fitted by m(theta) as a linear function of theta [P. Schofield, J.D. Litster, J.T Ho, Phys. Rev. Lett. 23 (1969) 1098]. Also Ho and Litster give beta = 0.368, gamma = 1.215 and delta = 4.3. Those critical experiments are very close to the recent 31) king results of Zhang [Z.D. Zhang, Philos. Mag. 87 (2007) 5309], namely beta = 3/8, gamma = 5/4 and delta = 13/3. We therefore predict that m(theta) will be proportional to theta as a fingerprint of the 3D Ising Hamiltonian. (C) 2009 Elsevier B.V. All rights reserved.
关键词:
Critical-point effects;Critical exponents;Ising model;Criticality;Ferromagnet;Magnetic equation of state;critical exponents
周晓宏
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刘红军
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刘鹏
功能材料
优化技术是一种以数学为基础,可用来求解各种工程问题最优解的应用技术.本文利用磁流变阻尼器动态特性数据,采用遗传算法进行阻尼器模型参数识别优化过程,最终将得到的磁流变阻尼器模型参数用于土木工程结构振动控制研究.已建立的磁流变阻尼器的动力特性将在不同的电场强度和变化的位移幅度下进行测试,可以得到在不同位移和速度下恢复力的滞回曲线,建立Bouc-Wen模型.把根据试验得到的滞回曲线和使用遗传算法对模型参数进行优化的结果进行比较可知,这种模型的参数可以以十分小的误差得到优化.
关键词:
遗传算法
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阻尼器
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参数识别
