流量回放可有效提升网络仿真的逼真度并支持新兴网络与安全技术的评测。面向大规模、高并发、高速率网络流量仿真的需求,设计并实现了一种基于云平台的分布式流量回放系统DTRS(distributed traffic replay system based on cloud platfo...流量回放可有效提升网络仿真的逼真度并支持新兴网络与安全技术的评测。面向大规模、高并发、高速率网络流量仿真的需求,设计并实现了一种基于云平台的分布式流量回放系统DTRS(distributed traffic replay system based on cloud platform)。基于该系统,针对网络流量多样化的特点,提出了可扩展的多流回放方法,以实现多种协议流量按需组合、灵活复现;针对数据包流转的高开销问题,提出了基于DPDK(data plane development kit)的流量回放策略,以实现流量回放过程的精确控制,提升回放的时序逼真性;针对流量回放速率不足的问题,提出了基于VPP(vector packet processing)的矢量包处理策略,提升了回放的吞吐量。实验结果表明,DTRS能实现互联网流量的多样化、可扩展加载,支持灵活、逼真、可控地复现海量异构网络场景;在高速率的流量仿真中,DTRS能保证时序逼真性;相较于传统方法,DTRS的流量回放吞吐量提升了3.71倍。展开更多
Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results s...Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results showed that optimal growth of S alfredii in terms of the maximum dry matter yield was observed at Zn/Cd complex level of 500/100 mumol/L. Plant cadmium (Cd) or zinc (Zn) concentrations increased with increasing Cd or Zn supply. During the 20 d treatment, the highest Cd concentration in the leaves reached 12.1 g/kg at Zn/Cd level of 50/400 mumol/L and that of Zn in the stems was 23.2 g/kg at Zn/Cd level of 1000/50 mumol/L. The distribution of Cd in different plant parts decreased in the order: leaf > stem greater than or equal to root, whereas that of Zn was: stem > leaf greater than or equal to root. The accumulation of Cd and Zn in the shoots and roots of S. alfredii increased with the increasing of Zn/Cd supply levels, peaked at Zn/Cd levels of 250/400 and 500/100 mumol/L, respectively. The highest Cd and Zn uptake by the shoots was approximately 5 and 11 mg/plant, and was over 20 and 10 times higher than those in the roots, respectively. Zn supply at levels less than or equal to 500 mumol/L increased plant Cd concentrations, whereas high Zn supply decreased root Cd but did not affect leaf Cd concentrations in S alfredii Low Cd supply increased Zn concentration in the leaves, but Cd supply higher than 50 mumol/L considerably reduced root Zn concentrations, especially at low Zn level. These results indicate that S. alfredii can tolerate high Zn/Cd complex levels and has an extraordinary ability to hyperaccumulate not only Zn but also Cd. It could provide a new valuable plant material for understanding the mechanisms responsible for co-hyperaccumulation of Zn and Cd as well as for phytoremediation of the Cd/Zn complex polluted soils.展开更多
文摘流量回放可有效提升网络仿真的逼真度并支持新兴网络与安全技术的评测。面向大规模、高并发、高速率网络流量仿真的需求,设计并实现了一种基于云平台的分布式流量回放系统DTRS(distributed traffic replay system based on cloud platform)。基于该系统,针对网络流量多样化的特点,提出了可扩展的多流回放方法,以实现多种协议流量按需组合、灵活复现;针对数据包流转的高开销问题,提出了基于DPDK(data plane development kit)的流量回放策略,以实现流量回放过程的精确控制,提升回放的时序逼真性;针对流量回放速率不足的问题,提出了基于VPP(vector packet processing)的矢量包处理策略,提升了回放的吞吐量。实验结果表明,DTRS能实现互联网流量的多样化、可扩展加载,支持灵活、逼真、可控地复现海量异构网络场景;在高速率的流量仿真中,DTRS能保证时序逼真性;相较于传统方法,DTRS的流量回放吞吐量提升了3.71倍。
文摘Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results showed that optimal growth of S alfredii in terms of the maximum dry matter yield was observed at Zn/Cd complex level of 500/100 mumol/L. Plant cadmium (Cd) or zinc (Zn) concentrations increased with increasing Cd or Zn supply. During the 20 d treatment, the highest Cd concentration in the leaves reached 12.1 g/kg at Zn/Cd level of 50/400 mumol/L and that of Zn in the stems was 23.2 g/kg at Zn/Cd level of 1000/50 mumol/L. The distribution of Cd in different plant parts decreased in the order: leaf > stem greater than or equal to root, whereas that of Zn was: stem > leaf greater than or equal to root. The accumulation of Cd and Zn in the shoots and roots of S. alfredii increased with the increasing of Zn/Cd supply levels, peaked at Zn/Cd levels of 250/400 and 500/100 mumol/L, respectively. The highest Cd and Zn uptake by the shoots was approximately 5 and 11 mg/plant, and was over 20 and 10 times higher than those in the roots, respectively. Zn supply at levels less than or equal to 500 mumol/L increased plant Cd concentrations, whereas high Zn supply decreased root Cd but did not affect leaf Cd concentrations in S alfredii Low Cd supply increased Zn concentration in the leaves, but Cd supply higher than 50 mumol/L considerably reduced root Zn concentrations, especially at low Zn level. These results indicate that S. alfredii can tolerate high Zn/Cd complex levels and has an extraordinary ability to hyperaccumulate not only Zn but also Cd. It could provide a new valuable plant material for understanding the mechanisms responsible for co-hyperaccumulation of Zn and Cd as well as for phytoremediation of the Cd/Zn complex polluted soils.
