The microstructural evolution of Al-Zn-Mg-Zr alloy with trace amount of Sc during homogenization treatment was studied by means of metallographic analysis, scanning electron microscopy （SEM）, energy dispersive X-ray...The microstructural evolution of Al-Zn-Mg-Zr alloy with trace amount of Sc during homogenization treatment was studied by means of metallographic analysis, scanning electron microscopy （SEM）, energy dispersive X-ray （EDX） and differential scanning calorimetry （DSC）. The results show that serious dendritic segregation exists in studied alloy ingot. There are many eutectic phases with low melting-point at grain boundary and the distribution of main elements along interdendritic region varies periodically. Elements Zn, Mg and Cu distribute unevenly from grain boundary to the inside of alloy. With increasing the homogenization temperature or prolonging the holding time, the residual phases are dissolved into matrix α（Al） gradually during homogenization treatment, all elements become more homogenized. The overburnt temperature of studied alloy is 476.7 °C. When homogenization temperature increases to 480 °C, some spherical phases and redissolved triangular constituents at grain boundaries can be easily observed. Combined with microstructural evolution and differential scanning calorimeter, the optimum homogenization parameter is at 470 °C for 24 h.展开更多
A high-speed equalizer based on a new algorithm： stop-and-go-DD-LMS CMA （SGLMS-CMA） for quadrature amplitude modulation （QAM） signals ispresented. It integrates conventional constant modulus algorithm （CMA） and...A high-speed equalizer based on a new algorithm： stop-and-go-DD-LMS CMA （SGLMS-CMA） for quadrature amplitude modulation （QAM） signals ispresented. It integrates conventional constant modulus algorithm （CMA） and decision-direct least-mean-square （DD-LMS） under stop-and-go principle. Matlab simulations indicate that, compared with conventional CMA,the new algorithm performs five times faster in convergence speed, 3-5dB improved in rudimental mean square error （MSE）, 82% decreased in operation complexity and can correct a final phase ambiguity. As to the equalizer block in the system,synthesis results show that the SGLMS-CMA ＋ DD-LMS equalizer＇s hardware consumption is only 5% greater than the CMA＋ DD-LMS equalizer＇ s. Finally by using SMIC 0.18μm library to synthesis, the new equalizer is embedded into QAM demodulation chip,and test results show that the new equalizer acts better.展开更多
基金Project (2012CB619503) supported by the National Basic Research Program of China
文摘The microstructural evolution of Al-Zn-Mg-Zr alloy with trace amount of Sc during homogenization treatment was studied by means of metallographic analysis, scanning electron microscopy （SEM）, energy dispersive X-ray （EDX） and differential scanning calorimetry （DSC）. The results show that serious dendritic segregation exists in studied alloy ingot. There are many eutectic phases with low melting-point at grain boundary and the distribution of main elements along interdendritic region varies periodically. Elements Zn, Mg and Cu distribute unevenly from grain boundary to the inside of alloy. With increasing the homogenization temperature or prolonging the holding time, the residual phases are dissolved into matrix α（Al） gradually during homogenization treatment, all elements become more homogenized. The overburnt temperature of studied alloy is 476.7 °C. When homogenization temperature increases to 480 °C, some spherical phases and redissolved triangular constituents at grain boundaries can be easily observed. Combined with microstructural evolution and differential scanning calorimeter, the optimum homogenization parameter is at 470 °C for 24 h.
基金supported by the Special Funds for Jiangsu Science and Technology Project of Tackling Key Problems(No.BE2004004)~~
文摘A high-speed equalizer based on a new algorithm： stop-and-go-DD-LMS CMA （SGLMS-CMA） for quadrature amplitude modulation （QAM） signals ispresented. It integrates conventional constant modulus algorithm （CMA） and decision-direct least-mean-square （DD-LMS） under stop-and-go principle. Matlab simulations indicate that, compared with conventional CMA,the new algorithm performs five times faster in convergence speed, 3-5dB improved in rudimental mean square error （MSE）, 82% decreased in operation complexity and can correct a final phase ambiguity. As to the equalizer block in the system,synthesis results show that the SGLMS-CMA ＋ DD-LMS equalizer＇s hardware consumption is only 5% greater than the CMA＋ DD-LMS equalizer＇ s. Finally by using SMIC 0.18μm library to synthesis, the new equalizer is embedded into QAM demodulation chip,and test results show that the new equalizer acts better.
