Snort入侵检测系统的改进

分析了Snort的工作原理．提出将网络流量中多媒体数据分离出来并对其进行专门处理的方法来提高Snort的检测效率．对多媒体数据包设计了放行和按媒体类型进行相应检测的2种处理方法，这2种方法均可以通过输入具体参数并针对双向或者单向数据流进行处理．实验证明，采用这2种方法能够降低Snort运行中的丢包率，而完备性较修改前没有降低．     

基于Snort的入侵检测系统研究

简要介绍了入侵检测系统的构成与系统特点,并对基于Snort的入侵检测方案进行了研究,给出了以Linux为平台的Snort入侵检测系统的设计、部署以及规则设计与模型改进等具体方案,为入侵检测系统的设计与开发提供了参考。     

一种快速Snort入侵检测系统研究

在高速网络中,提高入侵检测系统检测速率和效率是目前入侵检测系统需要解决的主要问题. 基于Linux平台,采用了零拷贝技术对Snort入侵检测系统的数据包捕获引擎进行了改进;采用改进的BM算法提高了规则匹配的效率,搭建了相应的实验平台并进行了性能测试. 测试表明,本方法可以显著提高Snort系统的性能.     

Snort规则链表结构的分析与改进

Snort主要是根据规则树对数据进行递归匹配。因此规则树的结构是否合理，在很大程度上影响着Snort规则匹配的速度。本文对Snort规则链表结构进行了分析，并针对Snort规则树过于简单这一不足之处，对其进行改进，在保持原有规则匹配方法的基础上，增加宽度优先搜索算法，从而减少规则匹配所需时间。     

基于Snort入侵检测系统的改进优化

在深入研究和分析Snort入侵检测系统的基础上,对原有系统提出了新的改进设计方案,解决了Snort系统不能及时检测未知入侵行为的问题．同时,根据Snort流出数据的特征,统计了其出现频率,将存在威胁的数据特征动态加入到Snort异常特征库中,实现了对未知入侵的拦截．改进后的系统可有效防止未知的入侵事件,降低了丢包率,提高了系统的全面检测能力．     

嵌入式Linux下网络设备驱动程序的开发

阐述了Linux网络系统的分层结构，分析了Linux内核中网络设备驱动程序的运行机理，介绍了实现Linux网络驱动程序开发的关键过程，结合设备驱动的调试方法通过应用实例给出了开发的全过程．最后，总结了嵌入式Linux下网络设备驱动程序开发的通用实现模式．     

基于Linux集群构建网络服务器的方案分析

Linux是当前最具发展潜力的计算机操作系统，它是一种新的开放自由软件，以高效性、灵活性著称，具有多任务、多用户的特点．随着Linux操作系统的不断完善和发展，用Linux构建网络服务器已成为网络服务器的发展方向．通过对实现虚拟网络服务相关方法的分析，提出了一种可行的构建Linux网络服务器方案．     

Linux体系结构及嵌入式Linux的移植方法

嵌入式系统是以应用为中心，以计算机技术为基础，软硬件均可裁剪，适应应用系统对功能、可靠性、成本、体积、功耗严格要求的专用计算机系统．而Linux作为一种优秀的免费操作系统，近几年在嵌入式领域异军突起，成为了最有潜力的嵌入式操作系统．本通过Linux体系结构的分析，以及一个移植Linux的具体范例，具体介绍了嵌入式Linux的移植方法．     

Snort系统的多播入侵检测功能的扩展

在对网络入侵检测系统Snort构架分析的基础之上，以Internet组管理（IGMP）协议为实例，提出了对Snort系统进行扩展的方法，实现了抓包、日志记录、检测出与IGMP协议有关的入侵等功能，最后给出了具体的扩展部分和实验。     

在嵌入式应用中增强Linux实时性的方法研究

在给出嵌入式系统实时性概念基础上，分析了在嵌入式系统中所运行任务的一般特点和Linux通用内核的实时机制，在肯定Linux的实时性性能的同时，指出了将其应用于嵌入式系统时所存在的不足，在分析目前提高Linux实时性的各种改进方法的基础上，提出了一种新的非常有效且可行的提高Linux实时性的思想及实现方法，并对改进的结果进行了分析．这为Linux在嵌入式系统中的应用提供了一种新的方法．     

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.     

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.     

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。     

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.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with