命名数据网络中基于信息熵的Interest洪泛攻击检测与防御

在命名数据网络中,兴趣包洪泛攻击通过向网络发送大量恶意interest包来消耗网络资源,从而对NDN造成较大危害.针对目前所提出的IFA攻击检测与防御方法存在攻击模式单一、在应对复杂攻击模式时效果不明显等局限,提出一种基于信息熵的改进方法(EIM),该方法通过与NDN路由器相连的用户的信誉值和信息熵相结合来限制攻击者发送的恶意interest包,很好地解决了现有方法在应对复杂的攻击模式时的局限性.仿真结果表明EIM较信息熵方法能够更有效地缓解IFA.     

命名数据网络中基于增强隔离林的Interest包洪泛攻击检测方法

IFA是NDN中的恶意攻击之一,危害较大.针对IFA,提出基于增强隔离林的IFA检测方法,通过在构造增强隔离林的过程中区分Interest包所携带的合法前缀与异常前缀,对异常前缀进行进一步判断,从而准确地检测出恶意前缀.所提出的方法将检测出的恶意前缀列入黑名单中,限制携带恶意前缀的Interest包转发.仿真结果表明：该方法能够有效地缓解IFA.     

NDN中基于神经网络的兴趣洪泛攻击综合防御方案

命名数据网络(named data networking, NDN)中的请求-应答通信模式及有状态的转发滋生了新的分布式拒绝服务(distributed denial of service, DDoS)攻击方式—兴趣洪泛攻击(interest flooding attack, IFA)。IFA是NDN中主要的拒绝服务威胁,虽然IFA防御方案被广泛研究,但目前缺乏系统的解决方案。针对这一问题,基于粒子群优化的后向传播神经网络算法提出一种新的IFA检测方法,并结合基于基尼不纯度的恶意前缀识别方法和兴趣包回溯方法来缓解攻击危害,形成一种综合的防御方案。通过ndnSIM仿真实验证明,提出的方案不仅可以准确检测和有效防御IFA攻击,而且解决了基于窗口检测方案无法检测连续攻击的问题。     

内容中心网络中基于熵率的攻击防御方法

兴趣包泛洪攻击通过耗尽路由器中待定兴趣表的资源从而对内容中心网络(content centric networking, CCN)产生严重的影响,目前的攻击防御方法主要是基于待定兴趣表的异常状态统计,但这些方法容易对合法用户产生误判,导致用户体验变差,因此针对内容中心网络中检测和防御兴趣包泛洪攻击的问题,提出基于信息熵和熵率的攻击防御方法。利用CCN中用户请求内容名称的随机性检测兴趣包泛洪攻击,再通过信息熵的差值识别恶意名称前缀,并向相邻节点发送包含恶意名称前缀信息的通知包,从而进行协同防御。仿真结果表明,与传统防御方法相比,在尽早检测出攻击的前提下,该方案能将突发流与攻击流进行区分,并快速抑制恶意兴趣包的转发,有效减少网络攻击造成的影响。     

命名数据网络中Sub/Pub 模式仿真实验研究

在 Linux 环境下，基于 Mini-ndn 仿真平台并利用 Python，设计并实现了命名数据网络(NDN) 分级命名路由仿真实验，研究了 Subscriber 和 Publisher 在一对一、一对多、多对一和多对多通信情况下， interest 包请求和 data 包响应问题，实验结果对 NDN 中的 Subscriber/Publisher 交互过程、结构化数据命名规则、interest 包在 NDN 路由器中的 CS 查找、PIT 处理和 FIB 转发等过程， 以及 data 包响应过程有了更直观的认识， 为 NDN 路由和转发理论研究提供实际参考依据．     

命名数据网络分级命名路由仿真实验研究

利用仿真工具Mini-CCNx,设计并实现了命名数据网络(NDN)中基于分级命名机制的路由仿真实验,通过设置不同的名字前缀来测试Interest包的响应情况,实验结果显示了NDN中基于分级命名机制的Interest包在路由和转发上的特点及优势.     

众包中基于博弈论的牛顿冷却定律应用

众包是一种可以高效解决复杂且困难问题的方法,但工人的恶意攻击行为会严重阻碍该方法的高效应用。为此,基于博弈理论,提出一种新的时衰收益策略模型来防止用户的恶意攻击行为。将参与者之间的交互建模为重复囚徒困境博弈,分析众包过程中的恶意攻击问题;使用基于牛顿冷却定律的时衰收益策略模型动态调节博弈双方的收益,改变博弈的纳什均衡;最后,使用股息贴现模型证明该策略模型的正确性。研究结果表明,该方案提高了合作用户的比例,降低了网络用户提供服务的成本,促进了网络用户之间的合作,解决了工人的恶意攻击问题。     

一种基于边缘同态重加密的NDN安全汇播机制

为提高安全汇播通信的传输效率,基于命名数据网络(named data networking,NDN),通过修改兴趣包命名与待定判决表结构,设计了具备缓存能力的新型汇播网络架构.在此基础上,结合同态加密技术,提出了一种基于边缘同态重加密的NDN安全汇播机制.该机制利用同态加密解决隐私数据汇聚问题,利用边缘重加密实现网内汇...     

基于轮询加密鉴权机制的5G网络抗攻击算法研究

为解决5G网络抗攻击领域内存在的网络抖动难以抑制、恶意攻击熔断效率不高等不足,提出了一种基于轮询加密鉴权机制的5G网络抗攻击算法.首先,利用基站和节点间存在的拓扑聚类关系,采用拓扑距离切割来实现对节点加入过程的主动应答,按能量水平实现快速排序,以增加恶意攻击节点的运行成本,优化网络传输质量;随后,基于拓扑距离、能耗等多参数,设计了一种基于多参数筛除机制的区域稳定方法,能够通过基准鉴权时钟优先清除不同步的恶意节点,以提升网络对恶意节点的熔断效果;最后,按照最小生成树来形成传输区域,有效降低流量激增对网络带来的恶意攻击,优化区域间传输,以提高网络抖动抑制能力.仿真实验表明,所提算法具有更强的网络抖动抑制能力及更优的恶意攻击熔断效果.     

基于遗传算法的蜜罐系统

入侵诱骗系统作为一种网络安全工具,其价值在于被扫描、攻击和入侵时,通过创建一个高度可控的攻击环境,从而捕获尽可能多的入侵信息.基于这些信息,分析入侵行为,预防更多的恶意破坏,从而更有效的保护网络.介绍一种基于遗传算法的蜜罐系统,其关键技术包括隐蔽的数据捕捉和基于遗传算法的行为分析技术.实验证明,该系统能有效捕捉恶意行为,防御多种新型攻击.     

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.     

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.     

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.     

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.     

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.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.