一种高性能内容过滤网关的设计与实现

采用NetGraph内核组件,基于UNIX的V流思想,设计实现了一个高性能的内容过滤网关.网关的数据包捕获框架是由一系列NetGraph节点连接而成的有向图,数据包沿着边可以在不同的节点间进行流动,通过零拷贝技术完成在系统内核空间的报文捕获.内容检查模块采用了改进的AC多模式匹配算法,提高了数据包关键词的检查速度和系统的性能.     

基于零拷贝的网络数据捕获技术的研究与实现

以传统捕包平台为研究对象,着重分析了高速网络环境下数据拷贝、硬件中断对捕包性能的影响,根据"零拷贝"思想提出了改进的方法,实现了网络接口设备直接将数据报文存储到应用程序可以访问的地址空间,减少了数据报文在内核态里传输时的数据拷贝次数,降低了网络数据接收的延迟;通过减少网卡接收报文时的中断次数,增加每次中断处理的报文数,节省了CPU时间,提高了在高速网络环境中主机对网络数据包的捕获和实时处理能力。仿真实验验证了该方法的可行性。     

一种零拷贝报文捕获系统的性能分析

文章分析了零拷贝报文捕获系统ZPC（Zero-copy Packet Capture System）的性能瓶颈,为消除ZPC的性能瓶颈,提出用户空间报文捕获系统ULPC(uer-level packet capture system),实验表明ULPC能有效解决ZPC的瓶颈,提升了系统的捕包性能。     

IPv6高速网络环境下数据分组捕获技术的研究

针对传统的数据分组捕获技术在IPv6高速网络环境下表现出的严重分组丢失问题,采用"零拷贝"的思想设计并实现了一个适用于IPv6高速网络环境的数据分组捕获平台(HSPCP)。以Intel82541GI吉比特网卡驱动程序e1000为基础,对网络数据分组的接收流程进行改进,在内核中注册一个杂项设备,实现了其mmap和ioctl方法,并编写了与改进后零拷贝驱动相对应的用户空间报文捕获程序。通过实验将HSPCP与Libpcap进行了分组捕获效率对比测试,实验证明HSPCP相对于传统的Libpcap分组捕获方式在性能上有较明显的提高。     

高速入侵检测系统

本文提出了多个关键技术从各个方面解决传统入侵检测速度瓶颈的问题，包括：零拷贝报文捕获、基于状态的协议分析、以及规则树结合高速算法插件匹配等技术。其中规则树结合高速算法插件的匹配技术在国内外属首次提出。     

基于XDP的高速流量采集技术研究

为了更好地适应网络回溯分析系统对高速网络下数据包捕获的要求,研究了基于eXpress Data Path(XDP)的高性能流量采集技术。通过使用零拷贝套接字AF＿XDP旁路内核协议栈,直接将数据包从内核空间传输到用户空间,有效减少了用户空间和内核空间频繁上下文切换带来的系统开销,提高了数据包捕获性能。在Linux平台上,基于XDP技术实现了数据包的捕获功能,并与基于Intel Data Plane Development Kit (DPDK)的流量采集方式进行实验对比。实验结果表明,XDP满足DPDK的流量采集性能要求,并且具有独立于硬件设备的优势。     

Linux下自适应网络数据捕获系统设计

本文在对零拷贝技术改进的基础上提出了一种适应不同网络负载环境下的自适应的数据捕获方法,重点介绍了其实现的关键技术、数据捕获整体结构,自适应数据捕获方法使用范围更广、在同等条件下有效的减轻了CPU的负荷,提高了数据捕获的效率。     

基于网络处理器IXP2400的组播包高速转发技术

传统的IP报文的组播技术,由于在处理过程中需要把整个报文的内容报文复制多份,因此处理器需要对缓存报文的外部存储空间进行多次I/O操作,这严重制约了当前处理器,特别是网络处理器的高速报文处理能力,转发效率不高.为此,提出了一种新的技术--"零拷贝"转发技术.该技术只修改报文头,报文体不复制,减少了大量的I/O操作,提高了转发效率.     

一种支持SMP的高性能入侵检测通信机制研究

提出并实现了一种适用于宽带网的支持SMP的高性能入侵检测通信协议框架-ULNP(user level network protocol)。该框架通过采用旁路内核协议栈的零拷贝技术实现用户级虚拟网络接口，同时针对入侵检测的特点，优化了用户层的通信协议栈，从而有效地降低了入侵检测系统的通信开销。实验结果表明在本文的试验环境下，相对于传统入侵检测通信框架而言，ULNP的报文处理带宽提高了大约2-7倍，CPU空闲率提高大约1～2倍。     

基于报文捕获技术的系统入侵与信息安全研究

ILAS系统是目前应用广泛的管理信息系统,但其系统登录的数据报文在网络中却是明文传送,存在易被捕获和破解的漏洞。本文利用报文捕获技术成功捕获用户的账号／密码并成功入侵ILAS系统;发现了ILAS系统登录报文帧的数据结构;最后提出了强针对性的报文捕获的防范措施。     

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