基于维度分解思想,设计并实现了一种联合元组空间和位图技术的二维分组分类算法(TB,joint tuple space and bitmap)。TB算法首先分别对源IP地址和目的IP地址进行单维匹配,然后在单维匹配的结果上运用交叉组合形成访问元组空间的路线,最...基于维度分解思想,设计并实现了一种联合元组空间和位图技术的二维分组分类算法(TB,joint tuple space and bitmap)。TB算法首先分别对源IP地址和目的IP地址进行单维匹配,然后在单维匹配的结果上运用交叉组合形成访问元组空间的路线,最后通过位图过滤技术进一步减少访问元组空间的个数,获得最终匹配的多维规则。相比传统的元组空间算法,TB结构清晰简洁易于更新和实现,TB算法拥有更好的时间和空间性能。实验证明,TB算法平均访问内存次数低于代表算法RSFR约26.6%,空间性能平均低于RSFR算法35.1%。展开更多
Traditional packet classification for IPv4 involves examining standard 5-tuple of a packet header, source address, destination address, source port, destination port and protocol. With introduction of IPv6 flow label ...Traditional packet classification for IPv4 involves examining standard 5-tuple of a packet header, source address, destination address, source port, destination port and protocol. With introduction of IPv6 flow label field which entails labeling the packets belonging to the same flow, packet classification can be resolved based on 3 dimensions： flow label, source address and desti- nation address. In this paper, we propose a novel approach for the 3-tuple packet classification based on flow label. Besides, by introducing a conversion engine to covert the source-destination pairs to the compound address prefixes, we put forward an algorithm called Reducing Dimension （RD） with dimension reduction capability, which combines heuristic tree search with usage of buck- ets. And we also provide an improved version of RD, called Improved RD （IRD）, which uses two mechanisms： path compression and priority tag, to optimize the perforrmnce. To evaluate our algo- rithm, extensive experiraents have been conducted using a number of synthetically generated databas- es. For the memory consumption, the two pro- posed new algorithms only consumes around 3% of the existing algorithms when the number of ill- ters increases to 10 k. And for the average search time, the search time of the two proposed algo- rithms is more than four times faster than others when the number of filters is 10 k. The results show that the proposed algorithm works well and outperforms rmny typical existing algorithms with the dimension reduction capability.展开更多
The present research reports a comparative study on the use of ＂really＂ by Chinese EFL learners. Taking the perspectives colligation and collocation, the study mainly yields the following findings： （1） Compared w...The present research reports a comparative study on the use of ＂really＂ by Chinese EFL learners. Taking the perspectives colligation and collocation, the study mainly yields the following findings： （1） Compared with American native speakers, Chinese EFL learners have different preferences for colligations and collocations of ＂really＂; （2） High achievers and low achievers demonstrate a similar pattern of the ranking order of the colligations, but high achievers are closer to the native speakers in the use of ＂really＂ in terms of collocation; low achievers rely more heavily on ＂very＂ to collocate with adjectives than high achievers.展开更多
As a key attribute of soil quality, soil organic matter(SOM) and its different fractions play an important role in regulating soil nutrient cycling and soil properties.This study evaluated the soil carbon(C) and nitro...As a key attribute of soil quality, soil organic matter(SOM) and its different fractions play an important role in regulating soil nutrient cycling and soil properties.This study evaluated the soil carbon(C) and nitrogen(N) concentrations in different SOM fractions(light– and heavy fractions,microbial biomass) under different vegetation types and analyzed their influencing factors in continuous permafrost regions along the Qinghai-Tibet Highway in the North of Kunlun Mountains, China.Soil samples were collected in pits under four vegetation types — Alpine swamp meadow(ASM), Alpine meadow(AM), Alpine steppe(AS) and Alpine desert(AD) — at the depth of 0-50 cm.The vegetation coverage was the highest at ASM and AM, followed byAS and AD.The results indicated that the concentrations of light fraction carbon(LFC) and nitrogen(LFN), and microbial biomass carbon(MBC)and nitrogen(MBN) decreased as follows: ASM > AM >AS > AD, with the relatively stronger decrease of LFC,whereas the heavy fraction carbon(HFC) and nitrogen(HFN) concentrations were lower in AS soils than in the AD soils.The relatively higher proportions of LFC/SOC and MBC/SOC in the 0-10 cm depth under the ASM soils are mainly resulted from its higher substrate input and soil moisture content.Correlation analysis demonstrated that aboveground biomass, soil moisture content, soil organic carbon(SOC) and total nitrogen(TN) positively correlated to LFC, LFN, HFC, HFN, MBC and MBN, while p H negatively correlated to LFC, LFN, HFC, HFN, MBC and MBN.There was no relationship between active layer thickness and SOM fractions, except for the LFC.Results suggested that vegetation cover, soil moisture content, and SOC and TN concentrations were significantly correlated with the amount and availability of SOM fractions, while permafrost had less impact on SOM fractions in permafrost regions of the central Qinghai–Tibet Plateau.展开更多
文摘基于维度分解思想,设计并实现了一种联合元组空间和位图技术的二维分组分类算法(TB,joint tuple space and bitmap)。TB算法首先分别对源IP地址和目的IP地址进行单维匹配,然后在单维匹配的结果上运用交叉组合形成访问元组空间的路线,最后通过位图过滤技术进一步减少访问元组空间的个数,获得最终匹配的多维规则。相比传统的元组空间算法,TB结构清晰简洁易于更新和实现,TB算法拥有更好的时间和空间性能。实验证明,TB算法平均访问内存次数低于代表算法RSFR约26.6%,空间性能平均低于RSFR算法35.1%。
基金This paper was supported by the National Natural Science Foundation of China under Crant No. 61003282 the Funda- mental Research Funds for the Central Universities under Crant No. 2011RCI）508+1 种基金 National Basic Research Program of China under Crant No. 2009CB320505 National High Technol-ogy Research and Development Program of China under Oant No. 2011AA010704.
文摘Traditional packet classification for IPv4 involves examining standard 5-tuple of a packet header, source address, destination address, source port, destination port and protocol. With introduction of IPv6 flow label field which entails labeling the packets belonging to the same flow, packet classification can be resolved based on 3 dimensions： flow label, source address and desti- nation address. In this paper, we propose a novel approach for the 3-tuple packet classification based on flow label. Besides, by introducing a conversion engine to covert the source-destination pairs to the compound address prefixes, we put forward an algorithm called Reducing Dimension （RD） with dimension reduction capability, which combines heuristic tree search with usage of buck- ets. And we also provide an improved version of RD, called Improved RD （IRD）, which uses two mechanisms： path compression and priority tag, to optimize the perforrmnce. To evaluate our algo- rithm, extensive experiraents have been conducted using a number of synthetically generated databas- es. For the memory consumption, the two pro- posed new algorithms only consumes around 3% of the existing algorithms when the number of ill- ters increases to 10 k. And for the average search time, the search time of the two proposed algo- rithms is more than four times faster than others when the number of filters is 10 k. The results show that the proposed algorithm works well and outperforms rmny typical existing algorithms with the dimension reduction capability.
文摘The present research reports a comparative study on the use of ＂really＂ by Chinese EFL learners. Taking the perspectives colligation and collocation, the study mainly yields the following findings： （1） Compared with American native speakers, Chinese EFL learners have different preferences for colligations and collocations of ＂really＂; （2） High achievers and low achievers demonstrate a similar pattern of the ranking order of the colligations, but high achievers are closer to the native speakers in the use of ＂really＂ in terms of collocation; low achievers rely more heavily on ＂very＂ to collocate with adjectives than high achievers.
基金financially supported by the National Major Scientific Project of China"Cryospheric Change and Impacts Research"program"Research of permafrost hydrothermal process and its response to climate change"(Grant No.2013CBA01803)supported in part by Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.41121001)+2 种基金the National Natural Science Foundation of China(Grant No.41101055)the West Light Foundation of the Chinese Academy of Sciencesthe Foundation for Excellent Youth Scholars of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences
文摘As a key attribute of soil quality, soil organic matter(SOM) and its different fractions play an important role in regulating soil nutrient cycling and soil properties.This study evaluated the soil carbon(C) and nitrogen(N) concentrations in different SOM fractions(light– and heavy fractions,microbial biomass) under different vegetation types and analyzed their influencing factors in continuous permafrost regions along the Qinghai-Tibet Highway in the North of Kunlun Mountains, China.Soil samples were collected in pits under four vegetation types — Alpine swamp meadow(ASM), Alpine meadow(AM), Alpine steppe(AS) and Alpine desert(AD) — at the depth of 0-50 cm.The vegetation coverage was the highest at ASM and AM, followed byAS and AD.The results indicated that the concentrations of light fraction carbon(LFC) and nitrogen(LFN), and microbial biomass carbon(MBC)and nitrogen(MBN) decreased as follows: ASM > AM >AS > AD, with the relatively stronger decrease of LFC,whereas the heavy fraction carbon(HFC) and nitrogen(HFN) concentrations were lower in AS soils than in the AD soils.The relatively higher proportions of LFC/SOC and MBC/SOC in the 0-10 cm depth under the ASM soils are mainly resulted from its higher substrate input and soil moisture content.Correlation analysis demonstrated that aboveground biomass, soil moisture content, soil organic carbon(SOC) and total nitrogen(TN) positively correlated to LFC, LFN, HFC, HFN, MBC and MBN, while p H negatively correlated to LFC, LFN, HFC, HFN, MBC and MBN.There was no relationship between active layer thickness and SOM fractions, except for the LFC.Results suggested that vegetation cover, soil moisture content, and SOC and TN concentrations were significantly correlated with the amount and availability of SOM fractions, while permafrost had less impact on SOM fractions in permafrost regions of the central Qinghai–Tibet Plateau.
