由于网络传输环境的不稳定性,为了将可伸缩视频编码(Scalable video coding,SVC)的码流能够在异构网络上实现可靠高效的传输质量,采用了联合前向纠错技术的不均等差错保护(Unequal Error Protection).不均等差错保护根据数据重要度的不...由于网络传输环境的不稳定性,为了将可伸缩视频编码(Scalable video coding,SVC)的码流能够在异构网络上实现可靠高效的传输质量,采用了联合前向纠错技术的不均等差错保护(Unequal Error Protection).不均等差错保护根据数据重要度的不同对各层给予不同强度的保护量,然而如何合理分配各层所需的保护数据,使恢复的视频质量达到最优是研究中的难点。通过建立信道差错所引起的失真模型,利用遗传算法(Genetic Algorithms)得到了最优码率分配方案,通过实验与传统方法比较,该方法有效提高了解码端的重建视频质量,特别是在高丢包的网络环境下表现的更为出色。展开更多
Understanding present patterns of genetic diversity is critical in order to design effective conservation and manage- ment strategies for endangered species. Tangjiahe Nature Reserve （NR） is one of the most importan...Understanding present patterns of genetic diversity is critical in order to design effective conservation and manage- ment strategies for endangered species. Tangjiahe Nature Reserve （NR） is one of the most important national reserves for giant pandas Ailuropoda melanoleuca in China. Previous studies have shown that giant pandas in Tangjiahe NR may be threatened by population decline and fragmentation. Here we used 10 microsatellite DNA markers to assess the genetic variability in the Tang- jiahe population. The results indicate a low level of genetic differentiation between the Hongshihe and Motianling subpopulations in the reserve. Assignment tests using the Bayesian clustering method in STRUCTURE identified one genetic cluster from 42 in- dividuals of the two subpopulations. All individuals from the same subpopulation were assigned to one cluster. This indicates high gene flow between subpopulations. F statistic analyses revealed a low Fzs-value of 0.024 in the total population and implies a randomly mating population in Tangjiahe NR. Additionally, our data show a high level of genetic diversity for the Tangjiahe population. Mean allele number （A）, Allelic richness （AR） and mean expected heterozygosity （HE） for the Tangjiahe population was 5.9, 5.173 and 0.703, respectively. This wild giant panda population can be restored through concerted effort展开更多
文摘Understanding present patterns of genetic diversity is critical in order to design effective conservation and manage- ment strategies for endangered species. Tangjiahe Nature Reserve （NR） is one of the most important national reserves for giant pandas Ailuropoda melanoleuca in China. Previous studies have shown that giant pandas in Tangjiahe NR may be threatened by population decline and fragmentation. Here we used 10 microsatellite DNA markers to assess the genetic variability in the Tang- jiahe population. The results indicate a low level of genetic differentiation between the Hongshihe and Motianling subpopulations in the reserve. Assignment tests using the Bayesian clustering method in STRUCTURE identified one genetic cluster from 42 in- dividuals of the two subpopulations. All individuals from the same subpopulation were assigned to one cluster. This indicates high gene flow between subpopulations. F statistic analyses revealed a low Fzs-value of 0.024 in the total population and implies a randomly mating population in Tangjiahe NR. Additionally, our data show a high level of genetic diversity for the Tangjiahe population. Mean allele number （A）, Allelic richness （AR） and mean expected heterozygosity （HE） for the Tangjiahe population was 5.9, 5.173 and 0.703, respectively. This wild giant panda population can be restored through concerted effort
