目的 理清低密度校验(Low-Density Parity-Check, LDPC)码的交替方向乘子(Alternating Direction Method of Multipliers, ADMM)译码方法中向量到校验多胞体投影操作的复杂度。方法 比较基于割查找的欧几里德投影算法和快速近似欧几里...目的 理清低密度校验(Low-Density Parity-Check, LDPC)码的交替方向乘子(Alternating Direction Method of Multipliers, ADMM)译码方法中向量到校验多胞体投影操作的复杂度。方法 比较基于割查找的欧几里德投影算法和快速近似欧几里德投影算法2种典型投影算法的投影结果、算法特点、时间复杂度以及基本操作次数。结果与结论快速近似欧几里德投影算法各种操作的次数低于基于割查找的欧几里德投影算法,表明前者的时间复杂度低于后者。展开更多
Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (...Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (MAO).The two catalysts were well matched in a single reactor and i t was observed that the “comonomer effect" appeared in the in situ copolymeriz ation of ethylene.The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures.At 60℃ and n(Al )/n(Fe+Zr)=2000,the maximum activity of the catalytic system(8 5×10\+6g/mo l·h) was 4\^25 times higher than that of homopolymerization of ethylene(2\^0×1 0\+6g/mol·h),and the value of n(Fe)/n(Zr) was 0 5.At n(Al)/n(F e+Zr)=1000,the maximum activity diminished.When polymerization temperatures incr eased,the maximum activity of the in situ copolymerization decreased and the co rresponding ratio of Fe to Zr also decayed.The copolymers made from this catalyt ic system had the characteristics of low melting point(from 132 34℃ to 70 97 ℃),low density(from 0 9467?g/cm\+3 to 0\^9283?g/cm\+3) and narrow molecular weight distribution(from 2\^29 to 1\^86).However,it’s no obvious influence of th e comonomer effect on the physical properties of the copolymers.展开更多
文摘目的 理清低密度校验(Low-Density Parity-Check, LDPC)码的交替方向乘子(Alternating Direction Method of Multipliers, ADMM)译码方法中向量到校验多胞体投影操作的复杂度。方法 比较基于割查找的欧几里德投影算法和快速近似欧几里德投影算法2种典型投影算法的投影结果、算法特点、时间复杂度以及基本操作次数。结果与结论快速近似欧几里德投影算法各种操作的次数低于基于割查找的欧几里德投影算法,表明前者的时间复杂度低于后者。
文摘Linear low density polyethylene from ethylene as an o nly monomer was prepared by the combination catalyst system of Et(Ind) 2ZrCl 2 an d {2 [2 Me 4 Br C 6H 3NC(Me)] 2C 5H 3N}FeCl 2 activated with methy laluminoxane (MAO).The two catalysts were well matched in a single reactor and i t was observed that the “comonomer effect" appeared in the in situ copolymeriz ation of ethylene.The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures.At 60℃ and n(Al )/n(Fe+Zr)=2000,the maximum activity of the catalytic system(8 5×10\+6g/mo l·h) was 4\^25 times higher than that of homopolymerization of ethylene(2\^0×1 0\+6g/mol·h),and the value of n(Fe)/n(Zr) was 0 5.At n(Al)/n(F e+Zr)=1000,the maximum activity diminished.When polymerization temperatures incr eased,the maximum activity of the in situ copolymerization decreased and the co rresponding ratio of Fe to Zr also decayed.The copolymers made from this catalyt ic system had the characteristics of low melting point(from 132 34℃ to 70 97 ℃),low density(from 0 9467?g/cm\+3 to 0\^9283?g/cm\+3) and narrow molecular weight distribution(from 2\^29 to 1\^86).However,it’s no obvious influence of th e comonomer effect on the physical properties of the copolymers.
