多聚类融合算法在频繁非法访问检测中的应用

针对频繁非法访问的检查问题，提供了一种机器学习方法来检测登录场景中的频繁非法访问活动。通过特征工程的方法分析登录日志数据，筛选提取有效特征，再使用聚类方法对登录特征数据进行检测，分类出正常用户和异常用户。为了提高无监督识别算法的精度，提出了多聚类融合的检测算法，从多个聚类算法的角度，精确识别出登录日志中的频繁非法访问用户。实验结果证明，该方法可以更准确地提取登录场景中各项指标异常的用户，并可以扩展适应其他频繁非法访问场景。     

浅谈防火墙在网络安全中应用

网络是一个复杂的环境系统,既要保证其访问的便捷性,又要考虑对其进行安全的控制,随着网络业务的迅速发展,必须扩展其内网应用服务资源和数据资源的访问领域,以满足越来越多的远程接入需求,比如分支机构接入、合作伙伴接入、客户接入、远程办公接入等。接入的网络环境也越来越复杂,接入的场景更是千变万化。如何在保证内网安全的前提下,确保处于各种复杂的网络环境以及接入场景的合法用户,能够安全接入内网,对现代网络提出了新的挑战。为了提供所需级别的保护,网络需要的是有安全策略的防火墙来防止非法用户访问内部网络上的资源和非法向外传递内部信息。     

分布式视频点播系统中动态负载平衡方法的研究

大多数多媒体的应用都是基于Client/Server通信模式的，用户通过高速网络访问媒体服务器上的媒体信息，这就需要一种通用的系统平台来负责管理用户对媒体服务器的访问，以达到系统资源充分利用，提出的系统平台正是基于这个目的，它采用动态负载平衡的方法，对用户访问多媒体服务器进行有效地管理，从而达到系统资源最有效地利用。系统访真结果表明，它在用户拒绝率、用户平均等待时间等方面的性能都优于传统意义上的视频点播系统。     

基于Shell命令和多阶Markov链模型的用户伪装攻击检测

伪装攻击是指非授权用户通过伪装成合法用户来获得访问关键数据或更高层访问权限的行为.提出一种新的用户伪装攻击检测方法.该方法针对伪装攻击用户行为的多变性和审计数据shell命令的相关性,利用特殊的多阶齐次narkov链模型对合法用户的正常行为进行建模,并通过双重阶梯式归并shell命令来确定状态,提高了用户行为轮廓描述的...     

数字交互式电视技术讲座:第3讲 视频服务器

(上接第 11期 )视频服务器是交互式电视与视频点播系统的核心设备 ,它的性能直接决定系统的总体性能。本讲介绍视频服务器的功能、结构、接口类型及磁盘与光盘存储技术。1　视频服务器的功能视频服务器是ＩＴＶ系统中的重要结构单元 ,它是一个存储信息和检索资料的服务系统。交互式电视的视频存储系统应具有以下几个功能。(1)具有一套用户访问控制功能结合系统资源的使用情况对用户的点播请求进行处理 ,采取一定的安全措施防止非法用户的访问 ;提供对交互式游戏和其他软件的随机即时访问 ,以及对数字化存储的电影磁带或磁盘提供顺序的、批量…     

基于移动云的虚拟化应用解决方案

随着企业规模和业务的不断扩展,移动云逐渐成为分支机构和外出办公人员通过移动终端访问企业内部系统资源的主要模式。针对用户移动终端无法准确识别、无法保证数据传输安全性等关键问题,文章提出基于移动云的虚拟化应用解决方案。方案采用虚拟化应用交付技术,实现移动终端与公司内部服务器间的优化连接,进行准确安全的设备、身份认证及数据传输,按需随时随地向移动终端用户提供完整的应用,最终保证企业系统资源的安全性。     

基于SAVI的IPv6接入认证系统设计

为了提高用户接入互联网的安全性,文中设计一款基于SAVI技术的IPv6接入认证系统。该系统基于充分的用户调研和技术分析,在Web认证方法的基础上,引入SAVI源地址验证技术。经实验测试表明,该系统可以抵抗分布式拒绝服务攻击,屏蔽无合法权限和伪造源地址的非法用户访问,进一步提高了新一代移动互联网的安全性防护水平。     

一个实用的off-line公平电子现金系统

本文提出的off-line公平电子现金系统具有以下特点:能保护合法用户的匿名性;可追踪非法用户;非法者不能敲诈用户;他人获得合法用户的电子现金不可盗用;银行与用户之间发生重复花费的争议时可仲裁;银行与信任机构都是脱线的.虽然信任机构要维护一个与银行相同数量级的数据库,但换来了申请、支付和存款的高效率.     

基于WPKI的3G实体认证的应用研究

3G系统的安全是3G系统正常运行和管理的基本保障,它关系到用户、制造商和运营商的切身利益及信息安全,如何在第三代移动通信系统中保证业务信息的安全性以及网络资源使用的安全性已成为3G系统中重要而迫切的问题。本文通过分析现有的3G认证过程,指出并分析了其存在的漏洞,并在此基础上提出了一种新的基于WPKI环境下的用于实现3G认证的具体方案,并对方案实现过程作了简要介绍,应用该方案增强了3G网中接入认证环节的安全性,而且杜绝了以往非法用户接入合法网络占用资源和合法用户登录非法网络从而泄露信息的现象。     

XML信息集及推理闭包的动态生成方法

XML动态推理控制的一个重要技术环节是如何简洁完整地记录用户获得的信息。文中采用模式树的形式将用户获得的信息保存在历史信息集中,当用户访问XML数据时,将访问结果包含的信息加入到历史信息集中,并利用模式树的信息包含关系消除冗余信息,同时使用XML关键字来合并XML元素。然后根据推理规则对XML历史信息集进行推理闭包扩展,使XML历史信息集能够完整地反映用户已了解的信息。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks