基于多核的安全网关设计与实现

传统的安全网关大多基于单核系统开发,受限于硬件发展的瓶颈,单核难以满足日益增长的网络性能要求。该文提出了一种基于多核的安全网关的设计模型,并根据此模型实现了一款安全网关,经过测试表明,此款安全网关的实现与通用安全网关相比性能优异,满足高性能网络安全的需要。     

志愿计算系统时延分析

志愿计算(Volunteer Computing)系统是一种分布式计算系统,它利用全球空闲计算资源实现海量科学计算.随着志愿计算的广泛应用,系统时延性能分析变得日益重要.现有文献主要通过仿真和实验观察其时延特性,并不能深入分析系统参数的影响.为此,提出了一种新的数学模型对志愿计算系统时延特性进行分析.志愿计算系统可以建模为一个变速率服务的单服务台排队系统.理论分析表明,系统的平均队长与服务速率方差之间存在单调递增的关系.因此,系统在服务速率方差趋于0和无穷大两个极端情况下的平均队长分别为系统平均队长的下界和上界,而在这两种极端情况下,可以通过对系统模型的简化求得系统的平均队长.仿真结果验证了该方法所求平均队长上下界的正确性和准确性.     

WWW至相关数据库的比较研究

本文提出两种从ＷＷＷ服务器访问相关数据库的新的网关机制：常驻网关服务器和缓冲常驻网关服务器。这两种机制及以公用网关协议（ＣＧＩ）为基础的机制都已实施，并评价了服务器的性能。结果表明：（１）ＣＧＩ有性能不足的缺点，（２）使网关服务器常驻对改进性能十分有效，（３）当检索到的数据量较大时，缓冲检索到的数据对改进性能十分有效。     

轮询多址通信系统门限服务策略研究

从两方面对离散时间情况下轮询多址通信门限排队服务系统进行了研究。改进了系统服务策略，运用嵌入式马尔可夫链理论和多维概率母函数的方法，得到了改进后系统查询时间点处的平均排队队长和信息分组平均时延理论解析式，仿真结果表明分析方法有效且系统性能较之原系统得到提高；采用一种简化的近似算法，得到了轮询周期内平均队长的理论解析式，理论计算与仿真结果有较好的一致性。     

无线Mesh网络多网关选播QoS路由模型研究

无线Mesh网络中网关常常成为网络的瓶颈.为了解决网关的选取问题和提高QoS性能,根据多网关选取问题与选播路由的相似性,提出了一种基于选播机制的网关选取模型.该模型将所有网关节点抽象成一个选播组,带QoS约束的用户端通过有效的选播机制能够自适应地选择最优的网关节点为其服务,以保证无线Mesh网络良好的接入性能.仿真结果表明了该算法的正确性和有效性.     

一种新的实际网络流量性能刻画方法

针对网络节点发生失效而产生的性能问题,提出了一种新的流量预测算法(Prediction algorithm based -FARIMA model for Breakdown ,PFB).该算法首先利用排队理论推导了存在失效节点时流量平均队长的数学表达式,并结合 FARIMA 模型建立了预测方法.同时,通过数学仿真分析了平均队长与服务率等影响因素之间的关系.实验结果表明该算法具有较好的适应性,与原始流量的标准差为12.13.     

基于D^（x）i／D2／1模型的ATM VBR视频业务统计复用性能分析

本文提出了一种新的ＶＢＲ视频业务统计复用分析模型Ｄ＾（ｘ）ｉ／Ｄ２／１,给出了该模型的快速解法,获得了该模型下的信元丢失率,平均队长,时延等指标,并应用该模型分析了满足Ｇａｍｍａ分布信源统计复用的性能。     

基于D[X]1/D2/1模型的ATM VBR视频业务统计复用性能分析

本文提出了一种新的 Ｖ Ｂ Ｒ 视频业务统计复用分析模型 Ｄ［ Ｘ］１ ／ Ｄ２／１,给出了该模型的快速解法,获得了该模型下的信元丢失率,平均队长,时延等指标。并应用该模型分析了满足 Ｇａｍ ｍ ａ 分布信源统计复用的性能。     

一种透明邮件过滤模型研究与实现

垃圾邮件的猖獗对反垃圾邮件技术提出了更高的要求。目前反垃圾邮件网关模型单一，可扩展性和跨平台性都比较差。本文针对这种情况提出了一种透明的反垃圾邮件网关模型。这种模型与企业网络的邮件服务器相互独立。而且它能够有效的利用目前以及将来出现的反垃圾邮件技术，具有良好的可扩展性。文章首先介绍了邮件以及反垃圾邮件技术，然后介绍了这种透明模型的实现，并分析了其性能上的优势与弱点，最后提出了在将来工作中需要进一步加强研究的方面。     

多媒体通信中不同优先级的业务复用模型分析

本文建立了基于流体流方法的复用模型，分析了具有不同优先级的多业务复用情况，计算了平均时延、平均队长及分组丢失率等服务质量参数，比较了有无优先机制时上述服务质量参数的异同。     

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.     

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.     

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.     

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.     

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.     

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.     

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