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H. Küpfer T. Wolf R. Kresse R. Meier-Hirmer K. Salama D. Lee V. Selvamanickam 《Journal of Superconductivity》1994,7(2):287-290
Time-dependent decay of the magnetic moment and magnetization measurements were used to study pinning and flux creep in two samples with and without aj(B) maximum in nonzero field (fishtail effect). From both measurements theE(j) relation was reconstructed forBc and the characteristic current exponent was obtained. At highj and lowB values are between 1 and 4; with increasingB passes a maximum and approaches negative values. At lowj is below 0.5 and not dependent onB orj. This behavior, which is qualitatively the same in both samples, is compared with proposed phase diagrams of the vortex lattice. Large values are correlated with the plateau of the normalized creep rateS 0.025; both observations indicate low relaxation and are found in that lowB region for whichj(B) has its minimum. This observation rejects a dominating influence of relaxation on the fishtail effect. 相似文献
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针对环件轧制成形规律,以数值仿真和数学解析相结合的方法,以有限元分析软件ABAQUS为平台,建立弹塑性动态显式有限元模型,研究驱动辊转速对环件成形工艺的影响。研究表明,在环件轧制过程中,随着驱动辊转速的增加,每转进给量减小,外径部分金属轴向流动增加,环件自由端面形状系数FT增加,最大宽展系数增加,环件自由端面质量下降;在驱动辊转速增加过程中,轧制力和轧制力矩减小,对轧环机的力学性能要求降低。同时平均等效应变PEEQa增加,环件塑性变形程度增大,有利于提高环件力学性能,但同时变形不均匀程度也加大,内部质量缺陷的可能性增加。 相似文献
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为了研究鱼尾色素的抗氧化性,以提取率和DPPH自由基清除率为评价指标,采用溶剂浸提的方法对色素进行提取,利用DPPH法、ABTS法和铁氰化钾还原法对提取物进行抗氧化实验。结果表明,鱼尾色素抗氧化成分提取的较佳工艺为浸提溶剂无水乙醇、温度20℃、料液比(g/mL)1:5、时间24h、浸提1次;此时色素提取物的提取率达2.40%,DPPH自由基清除率为58.44%。抗氧化性实验表明,鱼尾色素提取物具有较强的清除DPPH自由基和ABTS+自由基能力,其IC50值为0.3891mg/mL和1.8654mg/mL。 相似文献
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鱼尾型片材机头内熔体流动的三维有限元模拟 总被引:1,自引:0,他引:1
利用ANSYS和MATLAB软件,对鱼尾型片材机头流道内熔体的速度、压力和剪切应力的分布进行三维有限元模拟和分析。通过对机头流道不同截面处熔体场量分布的模拟,探知了熔体在流道内的运动规律及特点,对口模设计具有一定的指导作用。 相似文献
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