Linear complexity of sequences produced by single cycle T-function

Four kinds of sequences generated by single cycle triangular function(T-function)are investigated to check the possibility for a single cycle T-function to be a cryptographic component in stream ciphers.Based on the special properties of single cycle T-function and an algorithm due to Wei,linear complexities of these four kinds of sequence are all acquired.The results show that single cycle T-function sequences have high linear complexity.Therefore,T-function satisfies the essential requirements being a basic component of stream cipher.     

矩形晶格微结构光纤偏振拍长稳定性的优化

针对纤芯两侧具有一对大圆孔的矩形晶格微结构光纤,分别在两个正交方向上进行压缩或伸展,利用多种非对称结构的双折射相互平衡与补偿,抑制双折射随波长的非线性变化。应用全矢量有限差分波束传播法数值模拟分析了横向伸缩形变对模式双折射和偏振拍长色散特性的影响。通过优化设计,找出了合适的伸缩因子,有效降低了偏振拍长的波长敏感性。在1.0~2.0μm波长范围内,偏振拍长值在90.7~95.3 mm之间变化,相对变化率约为5%。这种矩形晶格微结构光纤适于制作宽带1/4波片。     

Orbital Damping of the Oscillating Superfluid ^3He A–B Interface at Low Temperatures

We present a model for the friction and effective mass of an oscillating superfluid $^3$ He A–B interface due to orbital viscosity in the B-phase texture close to the interface. The model is applied to an experiment in which the A–B interface was stabilised in a magnetic field gradient at the transition field $B_c = 340$  mT at 0 bar pressure and at a very low temperature $T \approx 0.155$  mK. The interface was then oscillated by applying a small additional field at frequencies in the range 0.1–100 Hz. The response of the interface is governed by friction and by its effective mass. The measured dissipation does not fit theoretical predictions based either on the Andreev scattering of thermal quasiparticles or by pair-breaking from the moving interface. We describe a new mechanism based on the redistribution of thermal quasiparticle excitations in the B-phase texture engendered by the moving interface. This gives rise to friction via orbital viscosity and generates a significant effective mass of the interface. We have incorporated this mechanism into a simple preliminary model which provides reasonable agreement with the measured behaviour.     

各向异性左手材料光纤的传输特性

对纤芯为各向异性左手材料,包层为普通材料的光纤进行了相关研究。首先,从Maxwell方程组出发,得到了各向异性左手材料光纤振荡模的色散方程。根据这些色散方程及其当前左手材料实际结构,同时考虑实际左手材料的频率色散特性,画出了TE、TM、HE和EH振荡模的色散曲线。通过对这些色散曲线的比较、分析,得到了一些振荡模的色散特性。比如:随着频率的增加,有效折射率也单调增加;TM振荡模有一定的群速,而EH振荡模有2个不同的群速,其突变频率约为4.46 GHz。此外,随着模阶数的增加,色散曲线向左上方移动;随着纤芯半径的增加,色散曲线向右下方移动,HE11振荡模的工作频域随着纤芯半径的增加而变宽。总之,这些都是有趣的色散特性,为进一步设计高性能光纤指明了方向。     

Correlation power analysis of DECIM～v2

Power analysis has been a powerful and thoroughly studied threat for implementations of block ciphers and public key algorithms but not yet for stream ciphers.Based on the consumed power differences between two neighboring clock cycles,this paper presents a correlation power analysis(CPA)attack on the synchronous stream cipher DECIM～v2(the tweaked version of the original submission DECIM).This attack resynchronizes the cryptographic device ceaselessly with many different initialization values(IVs)to obtain enough power traces.Then by modeling the statistical properties of the differential power traces with the correlation coefficients,the proposed attack algorithm can completely reveal the secret key of DECIM～v2.Furthermore,a simulation attack is mounted to confirm the validity of the algorithm.The results show that the entire secret key of DECIM～v2 can be restored within several minutes by performing 12 CPA attacks.It seems that there are still some defects in the design of DECIM～v2 and thus some further improvements should be made to resist the proposed attack.     

杭州无线宽带城域网建设详解

无线城市的建设是国内近两年无线应用的一个热点。杭州的无线宽带城市建设一直走在全国的前列，本文在MP无线接入点，MX无线控制器和RingMaster无线管理系统这三方面详细介绍了卓纪思网络公司为杭州建设无线宽带城域网的整体解决方案。     

Spectral Properties of Fabry-Pérot Laser Diodes and Conventional Semiconductor Optical Amplifiers

1IntroductionSemiconductor Optical Amplifier(SOA)and LaserDiode(LD)are key elementsin optoelectronic integrat-ed systems andfiber transmissionsystems[1~6].Agreateffort has been madeinthe development of the theoreti-cal models for SOAand LD behavior si mul…     

小型化带制冷电吸收调制激光器的研究

随着光通信朝着高速、高带宽和大容量方向发展,开发高性能的光通信用器件并减小器件的体积以降低成本变得越来越重要.电吸收调制激光器(EML)具有体积小、啁啾效应小、驱动电压低和弛豫振荡频率高等优点,成为当前国内外长距离、高速光通信系统的理想光源.然而,EML对温度非常敏感,温度的微弱变化都会影响其工作的稳定性.因此,如何使...     

对一种基于椭圆曲线加密体制的安全性分析

本文对一种椭圆曲线环上的陷门离散对数加密体制的安全性进行分析,指出它存在的安全缺陷,攻击者通过选择适当的明文加密,在得到相应的解密明文后,能够分解模数,从而成功地攻击此加密体制,因此该体制不能抵抗选择密文攻击.     

一种基于有向均匀圆阵的宽带波束形成方法

本文提出一种基于有向均匀圆阵解决宽带波束形成问题的新方法,其基本思想是针对某一特定频率设计窄带波束形成空域滤波器,并把得到的滤波器权值直接应用于宽带信号以降低设计和处理的复杂度.在已知信号方向信息的前提下,使用线性约束的最小二乘法设计窄带空域滤波器,而有向均匀圆阵对频率变化不敏感的特性可以保证使用同一组空域滤波器权值在宽带信号所包含的不同频率上形成一致的波束与陷波点.所提出的宽带波束形成方法可以显著降低阵列信号处理时的运算复杂度,便于进行实时信号处理.