It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional super...It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.展开更多
为了进一步研究连续体结构拓扑优化模型的合理性和可行性,基于独立、连续、映射(independent continuous mapping,ICM)方法,在满足结构位移约束的条件下,通过引入复合指数形式过滤函数对位移约束下质量最小化(minimum weight with a dis...为了进一步研究连续体结构拓扑优化模型的合理性和可行性,基于独立、连续、映射(independent continuous mapping,ICM)方法,在满足结构位移约束的条件下,通过引入复合指数形式过滤函数对位移约束下质量最小化(minimum weight with a displacement constraint,MWDC)模型进行了改进,建立了基于独立连续变量和复合指数函数的位移约束平面连续体结构拓扑优化模型,并进行了优化求解.同时,利用M语言,基于Matlab软件平台,开发了相应的拓扑优化计算程序,并针对4种典型平面连续体结构进行了数值验证,分别比较分析了体积约束下的柔顺度最小化(minimum compliance with a volume constraint,MCVC)模型、MWDC模型以及改进的MWDC模型所得到的最优拓扑结构.数值结果表明:采用复合指数形式过滤函数改进的MWDC优化模型迭代次数更少,优化求解计算效率更高.展开更多
A bandwidth microwave second harmonic generator is successfully designed using composite right/left-handed non- linear transmission lines （CRLH NLTLs） in a GaAs monolithic microwave integrated circuit （MMIC） techn...A bandwidth microwave second harmonic generator is successfully designed using composite right/left-handed non- linear transmission lines （CRLH NLTLs） in a GaAs monolithic microwave integrated circuit （MMIC） technology. The structure parameters of CRLH NLTLs, e.g. host transmission line, rectangular spiral inductor, and nonlinear capacitor, have a great impact on the second harmonic performance enhancement in terms of second harmonic frequency, output power, and conversion efficiency. It has been experimentally demonstrated that the second harmonic frequency is deter- mined by the anomalous dispersion of CRLH NLTLs and can be significantly improved by effectively adjusting these structure parameters. A good agreement between the measured and simulated second harmonic performances of Ka-band CRLH NLTLs frequency multipliers is successfully achieved, which further validates the design approach of frequency multipliers on CRLH NLTLs and indicates the potentials of CRLH NLTLs in terms of the generation of microwave and millimeter-wave signal source.展开更多
文摘It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.
文摘为了进一步研究连续体结构拓扑优化模型的合理性和可行性,基于独立、连续、映射(independent continuous mapping,ICM)方法,在满足结构位移约束的条件下,通过引入复合指数形式过滤函数对位移约束下质量最小化(minimum weight with a displacement constraint,MWDC)模型进行了改进,建立了基于独立连续变量和复合指数函数的位移约束平面连续体结构拓扑优化模型,并进行了优化求解.同时,利用M语言,基于Matlab软件平台,开发了相应的拓扑优化计算程序,并针对4种典型平面连续体结构进行了数值验证,分别比较分析了体积约束下的柔顺度最小化(minimum compliance with a volume constraint,MCVC)模型、MWDC模型以及改进的MWDC模型所得到的最优拓扑结构.数值结果表明:采用复合指数形式过滤函数改进的MWDC优化模型迭代次数更少,优化求解计算效率更高.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61401373)the Research Fund for the Doctoral Program of Southwest University,China(Grant No.SWU111030)
文摘A bandwidth microwave second harmonic generator is successfully designed using composite right/left-handed non- linear transmission lines （CRLH NLTLs） in a GaAs monolithic microwave integrated circuit （MMIC） technology. The structure parameters of CRLH NLTLs, e.g. host transmission line, rectangular spiral inductor, and nonlinear capacitor, have a great impact on the second harmonic performance enhancement in terms of second harmonic frequency, output power, and conversion efficiency. It has been experimentally demonstrated that the second harmonic frequency is deter- mined by the anomalous dispersion of CRLH NLTLs and can be significantly improved by effectively adjusting these structure parameters. A good agreement between the measured and simulated second harmonic performances of Ka-band CRLH NLTLs frequency multipliers is successfully achieved, which further validates the design approach of frequency multipliers on CRLH NLTLs and indicates the potentials of CRLH NLTLs in terms of the generation of microwave and millimeter-wave signal source.
