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矢量量化码书快速匹配算法是矢量量化技术实时应用的关键所在。从原理上看,提高矢量码书匹配速度的方法可以分为两类:一类是通过建立某种“剔除”条件来避免不必要的输入矢量和码书矢量之间欧氏距离计算“软”算法,另外一类是通过找表(LUT)技术来代替欧氏距离计算中乘法运算的“硬”方法,文章利用这两类方法的互补性,提出了一种“软”、“硬”方法相结合的矢量码书快速匹配算法。实验表明,该算法具有非常好的实时性能,能够方便地应用于加快数据压缩矢量量化的码书匹配过程以及模式识别中SOM型神经网络的识别过程。 相似文献
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Evolution behavior of catalytically activated replication-decline in a coagulation process
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We propose a catalytically activated replication-decline model of three species, in which two aggregates of the same species can coagulate themselves, an A aggregate of any size can replicate itself with the help of B aggregates, and the decline of A aggregate occurs under the catalysis of C aggregates. By means of mean-field rate equations, we derive the asymptotic solutions of the aggregate size distribution ak(t) of species A, which is found to depend strongly on the competition among three mechanisms: the self-coagulation of species A, the replication of species A catalyzed by species B, and the decline of species A catalyzed by species C. When the self-coagulation of species A dominates the system, the aggregate size distribution a~(t) satisfies the conventional scaling form. When the catalyzed replication process dominates the system, ak(t) takes the generalized scaling form. When the catalyzed decline process dominates the system, ak(t) approaches the modified scaling form. 相似文献
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用密度泛函理论对一种新式反铂抗癌药物trans-[PtCl2(3-pico)(isopropylamine)]的水解机理进行了研究.研究中选用两个模型,即模型一为反应物和产物均为孤立状态,模型二为反应物和产物处于络合状态.运用B3LYP/6-31G**泛函方法对反应物、产物和过渡态的几何结构进行了全面优化.发现水解过程中过渡态结构与文献中报道的三角双锥结构吻合.反应络合物与产物络合物中所包含的进入基团(水分子)和离去基团(氯离子)对反应的热力学和动力学都产生了很大影响:模型二的两步反应活化能垒分别比模型一提高了约26.3和23.8 kJ/mol,吸热量比模型一分别降低了约420.5和771.2 kJ/mol.采用IEF-PCM模型进行水溶液计算,模型一两步反应的活化能垒比气相值分别提高约27.6和6.7 kJ/mol,模型二则分别降低约7.9和29.3 kJ/mol.经过熵修正后整个体系第一步水解的反应活化能全部上升了而第二步则恰好相反,第二步水解的活化能垒始终高于第一步. 相似文献