The formation of self assembled CdSe quantum dots under Stranski Krastanow (S K) mode by low pressure metalorganic chemical vapor deposition (LP MOCVD) was reported for the first time. The samples were grown directly ...The formation of self assembled CdSe quantum dots under Stranski Krastanow (S K) mode by low pressure metalorganic chemical vapor deposition (LP MOCVD) was reported for the first time. The samples were grown directly on GaAs (100) surfaces by LP MOCVD. DimethylSelenide (DMSe) and DimethylCadmium (DMCd) were used as precursors. The growth pressure was kept at 2 93×10 4Pa and the growth temperature was 500℃. CdSe with the thickness of about 2 monolayers was grown directly on GaAs (100) surfaces. For the purpose of AFM observation, this uncapped sample was cooled down immediately to room temperature and was monitored under a Digital Instruments Nanoscope Ⅲa system at the same day of growth. The AFM images show that the average diameter, height and density of those self assembled CdSe quantum dots are 50±15nm, 13±4nm and 5μm -2 , respectively. And those dots’ diameter height ratio is about 4～5, just the same as those results observed in other Ⅱ Ⅵ and Ⅲ Ⅵ compounds which were grown under S K mode by MBE.展开更多
S-K模型(Shiono and Knight Method)是目前进行单一和复合断面顺直棱柱体明渠水力计算较为精细的模型之一。涉及3个待定参数:摩阻系数f、无量纲涡粘性系数λ和二次流影响因子Γ,这3个参数的待定性使该模型在实际工程应用中受到限制。本...S-K模型(Shiono and Knight Method)是目前进行单一和复合断面顺直棱柱体明渠水力计算较为精细的模型之一。涉及3个待定参数:摩阻系数f、无量纲涡粘性系数λ和二次流影响因子Γ,这3个参数的待定性使该模型在实际工程应用中受到限制。本文结合大量的水槽试验流量Q及壁面切应力τb结果,采用随机搜寻法,对S-K模型中的3个重要参数进行了同时满足Q和切应力bτ条件下的优化率定。结果表明,参数f变化规律与Colebrook-White公式基本一致,λ和Γ随渠道宽高比Pb/Pw的变化规律较为明显。展开更多
Necessary and sufficient conditions for a schur complement of a con-s-k-EP matrix to be con-s-k-EP are determined. Further it is shown that in a con-s-k-EPr matrix, every secondary sub matrix of rank “r” is con-s-k-...Necessary and sufficient conditions for a schur complement of a con-s-k-EP matrix to be con-s-k-EP are determined. Further it is shown that in a con-s-k-EPr matrix, every secondary sub matrix of rank “r” is con-s-k-EPr. We have also discussed the way of expressing a matrix of rank r as a product of con-s-k-EPr matrices. Necessary and sufficient conditions for products of con-s-k-EPr partitioned matrices to be con-s-k-EPr are given.展开更多
On the basis of preliminary studies,a novel duo-parameter model consisting of amplitude filter factor and frequency filter factor for low-pass S-K filter is presented in this paper.The model is established by applying...On the basis of preliminary studies,a novel duo-parameter model consisting of amplitude filter factor and frequency filter factor for low-pass S-K filter is presented in this paper.The model is established by applying numerical differentiation method.Some simulation experiments and real data tests are carried out to verify the feasibility and superiority of the new algorithm.The results show that this duo-parameter model of low-pass S-K filter can be used to achieve high performance in signal processing and nuclear spectrum smoothing.展开更多
文摘The formation of self assembled CdSe quantum dots under Stranski Krastanow (S K) mode by low pressure metalorganic chemical vapor deposition (LP MOCVD) was reported for the first time. The samples were grown directly on GaAs (100) surfaces by LP MOCVD. DimethylSelenide (DMSe) and DimethylCadmium (DMCd) were used as precursors. The growth pressure was kept at 2 93×10 4Pa and the growth temperature was 500℃. CdSe with the thickness of about 2 monolayers was grown directly on GaAs (100) surfaces. For the purpose of AFM observation, this uncapped sample was cooled down immediately to room temperature and was monitored under a Digital Instruments Nanoscope Ⅲa system at the same day of growth. The AFM images show that the average diameter, height and density of those self assembled CdSe quantum dots are 50±15nm, 13±4nm and 5μm -2 , respectively. And those dots’ diameter height ratio is about 4～5, just the same as those results observed in other Ⅱ Ⅵ and Ⅲ Ⅵ compounds which were grown under S K mode by MBE.
文摘S-K模型(Shiono and Knight Method)是目前进行单一和复合断面顺直棱柱体明渠水力计算较为精细的模型之一。涉及3个待定参数:摩阻系数f、无量纲涡粘性系数λ和二次流影响因子Γ,这3个参数的待定性使该模型在实际工程应用中受到限制。本文结合大量的水槽试验流量Q及壁面切应力τb结果,采用随机搜寻法,对S-K模型中的3个重要参数进行了同时满足Q和切应力bτ条件下的优化率定。结果表明,参数f变化规律与Colebrook-White公式基本一致,λ和Γ随渠道宽高比Pb/Pw的变化规律较为明显。
文摘Necessary and sufficient conditions for a schur complement of a con-s-k-EP matrix to be con-s-k-EP are determined. Further it is shown that in a con-s-k-EPr matrix, every secondary sub matrix of rank “r” is con-s-k-EPr. We have also discussed the way of expressing a matrix of rank r as a product of con-s-k-EPr matrices. Necessary and sufficient conditions for products of con-s-k-EPr partitioned matrices to be con-s-k-EPr are given.
基金Supported by branch project of national 863 project(2012AA061804)
文摘On the basis of preliminary studies,a novel duo-parameter model consisting of amplitude filter factor and frequency filter factor for low-pass S-K filter is presented in this paper.The model is established by applying numerical differentiation method.Some simulation experiments and real data tests are carried out to verify the feasibility and superiority of the new algorithm.The results show that this duo-parameter model of low-pass S-K filter can be used to achieve high performance in signal processing and nuclear spectrum smoothing.
