SDN的监控框架与自适应监控算法简

针对软件定义网络(SDN)的监控效果问题,提出了一种可对网络应用屏蔽底层细节的软件定义网络监控框架及一种自适应的的网络监控算法.该算法通过可变频率流量统计策略动态调整监控采样周期,从而在监控准确率和网络负载之间维持平衡.监控框架通过应用程序接口为上层应用提供监控算法接口,并与底层网络进行数据交互,从而实现了屏蔽底层网络复杂性的监控.实验结果表明,该框架与算法具有较小的监控误差和较低的流量负载,是一种理想的SDN监控方法.     

SDN的监控框架与自适应监控算法

针对软件定义网络(SDN)的监控效果问题,提出了一种可对网络应用屏蔽底层细节的软件定义网络监控框架及一种自适应的的网络监控算法.该算法通过可变频率流量统计策略动态调整监控采样周期,从而在监控准确率和网络负载之间维持平衡.监控框架通过应用程序接口为上层应用提供监控算法接口,并与底层网络进行数据交互,从而实现了屏蔽底层网络复杂性的监控.实验结果表明,该框架与算法具有较小的监控误差和较低的流量负载,是一种理想的SDN监控方法.     

基于离散粒子群的SDN动态流调度算法

针对数据中心网络中流量路径分配不合理、易导致大流冲突的问题,提出一种基于离散粒子群的软件定义网络(SDN)流量调度算法.该算法重定义粒子群内部的寻解过程,以最优化网络性能为目标,动态地为数据中心的流量分配最优路径,以减少大流量冲突;并引入Metropolis设计多元化最优调度方案,确保数据中心流量的合理调度.与其他流量调度算法进行对比验证的实验结果表明,该算法提升了网络质量,降低了大流时延,实现了更好的负载均衡.     

一种网络冗余流量消除算法

针对大量数据片段冗余传输造成网络带宽浪费严重的问题,提出了一种基于动态查找表的冗余流量消除(DYNATABLE)算法。该算法动态统计流量中以不同字节值开头的数据块的冗余率,在保证目标块抽样率的情况下,选取冗余率高的数据块的首字节值为标识,实时更新查找表,根据查找表中的标识从数据包中选出数据块,对已经传输过的冗余数据块进行简单编码,用编码数据替换原冗余数据片段,再对消除冗余流量的数据包进行传输。对比基于最大值选择和基于静态查找表选择等冗余流量消除算法,DYNATABLE算法能跟踪网络数据的动态变化,带来更高的字节节省,平均字节节省率提高到21.8%。     

针对SDN基础设施的拒绝服务攻击防护框架

为了进一步缓解针对SDN基础设施的典型拒绝服务攻击(数据-控制平面饱和攻击),提出了一种控制器和交换机协作式的安全防护框架,即FloodShield.在该攻击中,攻击者通过洪泛伪造数据包,使数据平面产生大量表项缺失和packet-in数据包,从而消耗SDN基础设施不同层次的资源:数据平面的TCAM资源、控制通道的带宽资源和控制器的CPU资源等.通过对这种攻击的详尽分析,提出并设计了易部署、全面性和轻量化的FloodShield防护框架.该框架主要使用了2个关键技术:1)源地址验证,用于在数据平面过滤源地址伪造的数据包;2)有状态数据包监控,用于监控源地址真实流量的状态,并基于流量评价打分和网络资源使用量采用动态的防护措施.实验结果表明,相比于之前的防护框架,FloodShield在消耗更少系统资源的同时,对SDN架构的数据平面、控制通道和控制平面都提供了有效的保护.     

数据中心网络多路径路由算法

数据中心网络流量分布的不均衡增加了网络拥塞产生的可能性,由于数据中心网络的流量特性,使得传统IP网络的流量工程方法不一定适合。该文在SDN/OF(software defined network/OpenFlow)的结构下,提出了一种基于多路径传输的动态路由算法(dynamic routing algorithm based on multipath propagation,Dramp)并作为SDN/OF结构中应用层的流量均衡策略。该算法在重新定义链路关键度并求解链路权值优化问题的基础上,能充分利用数据中心网络中存在的冗余路径,在完成细粒度流量均衡的同时,能很好地克服控制器的计算开销,完成路由优化的目标。通过在Mininet仿真平台中部署并进行仿真实验,与等开销多路径路由算法ECMP(equal-cost multi-path)以及GFF(global first fit)路由算法相比较,结果展示了Dramp的优越性能,同时证明了在数据中心网络中采用Dramp作为流量工程的解决方案更简单、更实用。     

链路洪泛攻击的SDN移动目标防御机制

针对Crossfire分布式拒绝服务(distributed denial of service,DDoS)攻击,该文提出一种基于软件定义网络(software defined network,SDN)的攻击防御机制。在对Crossfire攻击分析基础上,设计一个SDN流量层级的集中监测及分流控制模型并部署到防御机制中,利用SDN的重路由策略疏解被攻击链路的拥塞负载,通过对流量的灵活调度缓解拥塞并避免关键链路中断对网络业务造成严重干扰。利用SDN的移动目标防御(mobile target defense,MTD)机制动态调整网络配置和网络行为并诱使攻击者对攻击流量进行调整,提高诱饵服务器对攻击的检测效率。实验结果表明:该机制可以有效防御Crossfire攻击且SDN的防御机制和重路由策略不会造成显著开销。     

一种基于深度强化学习的SDN路由算法

为解决软件定义网络(SDN)中的流量工程(TE)问题,提出了一种深度强化学习路由(DRL-Routing)算法.该算法使用较全面的网络信息来表示状态,并使用一对多的网络配置来进行路由选择,奖励函数可以调整往返路径的网络吞吐量.仿真结果表明,DRL-Routing可以获得更高的奖励,并且经过适当的训练后,能使各交换机之间获得更优的路由策略,从而增大了网络吞吐量,降低了网络延迟和数据丢包率.     

基于代数连通度的软件定义网络节能算法

软件定义网络(software defined network, SDN)在快速发展中面临许多新挑战,其中能耗问题尤为突出.学者们提出了许多节能方案,但目前已有的方案存在依赖传统网络背景,需要实时流量数据,不易部署,连通稳定性兼顾不全等问题.因此,提出一种基于代数连通度的软件定义网络节能算法(energy saving for sdn based on algebraic connectivity, ESSDNAC).该算法通过代数连通度变化量计算网络拓扑中各链路的关键度Lc_i,并按Lc_i值越小越优先的顺序选择相应的链路进入可休眠队列.最后在保障网络连通稳定性的前提下实现节能,算法仅需网络拓扑参数,无需网络实时流量数据.通过实验结果表明,ESSDNAC算法无需复杂的计算代价,即可在Abilene网络源线卡环境中均值为33.1%的节能率,且节能后网络连通性得到保证,为SDN部署绿色节能网络提供一种新的方案.     

软件定义网络中基于贝叶斯ARTMAP的DDoS攻击检测模型

为解决SDN(software defined network,软件定义网络)架构下DDoS(distributed denial of service,分布式拒绝服务)攻击检测问题,提出基于贝叶斯ARTMAP的DDoS攻击检测模型. 流量统计模块主要收集捕获到的流表信息,特征提取模块提取流表中的关键信息并获取关键特征,分类检测模块通过贝叶斯ARTMAP提取分类规则,并通过粒子群算法对参数进行优化,对新的数据集进行分类检测.仿真实验证明了模型所提取的5元特征的有效性,并且该模型与3种传统的DDoS攻击检测模型相比检测成功率提高了0.96%~3.71%,误警率降低了0.67%~2.92%.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.