Laser-induced pattern formation from homogeneous polyisoprene solutions

This paper reports that the pattern formation in homogeneous solutions of polyisoprene in toluene saturated with C60 induced by a continuous-wave visible laser is observed experimentally. The transmitted beam patterns change with the increase of the laser irradiation time. In the initial phase, the patterns with concentric ring-shaped structure are formed. In the end, the patterns become speckle-shaped. The incubation time of the transmitted beam widening is inversely proportional to the laser power density and solution concentration. The pattern formation results from the optical-field-induced refractive index changes in the solutions, but the mechanism of optical-field-induced refractive index changes in the polymer solutions needs to be further studied.     

Characterizing localization properties of two spinless electrons in a one-dimensional Harper model with concurrence

By mapping the Fock space of many local fermionic modes isomorphically onto a many-qubit space and using the measure of concurrence, this paper studies numerically the mode entanglement of two spinless electrons with on-site interaction U moving in the one-dimensional Harper model. Generally speaking, for electrons in extended regimes （potential parameter λ 〈 2）, the spectrum-averaged concurrence N（C） first decreases slowly as A increases until its local minimum, then increases with λ until its peak at λ = 2, while for electrons in localized regimes （λ 〉 2）, N（C） decreases drastically as λ increases. The functions of N（C） versus λ are different for electrons in extended and localized regimes. The maximum of N（C） occurs at the point λ= 2, which is the critical value in the one-dimensional singleparticle Harper model. From these studies it can distinguish extended, localized and critical regimes for the two-particle system. It is also found for the same λ that the interaction U always induce the decreases of concurrence, i.e., the concurrence can reflect the localization effect due to the interaction. All these provide us a new quantity to understand the localization properties of eigenstates of two interacting particles.     

Quantum entanglement in the mode-mode competition system

Considering a two-level atom interacting with the competing two-mode field, this paper investigates the entanglement between the two-level atom and the two-mode field by using the quantum reduced entropy, and that between the two-mode field by using the quantum relative entropy of entanglement. It shows that the two kinds of entanglement are dependent on the relative coupling strength of atom-field and the atomic distribution, and exhibit the periodical evolution. The maximal atom-field entanglement state can be prepared via the appropriate selection of system parameters and interaction time.     

Steady state speed distribution analysis for a combined cellular automaton traffic model

Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.     

基于金属包覆磁性波导结构的磁光Bragg器件特性分析

使用金属包覆磁性波导中的磁光耦合理论分析了静磁表面波与导波光在金属／电介质／钇铁石榴石／钆镓石榴石结构中的磁光共线作用，讨论了金属覆层和斜向场对磁光模式转换效率的影响。计算表明，金属包覆波导可以提高磁光作用，通过调节金属覆层与磁性薄膜间距得到了比空气／4a铁石榴石／钆镓石榴石的传统三明治波导情形高8．7dB的模式转换效率；而同时优化偏置磁场方向和金属包覆波导参数，模式转换效率可以进一步提高5．25dB。因此，金属包覆波导可以用于提高磁光Bragg器件性能，在微波和光信息处理等方面具有广阔的应用前蒂。     

父代种群参与竞争遗传算法几乎必然收敛

熟知,标准遗传算法如不采用“杰出者记录策略”则必不收敛。本文发现：允许父代种群参与竞争是标准遗传算法几乎必然收敛的条件。特别地,我们运用鞅收敛定理证明：允许父代种群参与竞争型遗传算法能以概率1确保在限步内达到全局最优解,且收敛与种群规模无关。所获结果对该类遗传算法的应用奠定了可靠基础。     

为3G计费支招——业界知名计费厂家谈我国的3G计费系统建设

虽然3G在我国还没有正式启动，但业界对3G的摇旗呐喊以及为3G的准备工作从来没有停止过!时到今日，人们对3G的研究已经深入到如何建设、运维以及业务计费的细节上。 随着3G时代的临近，对3G业务的支撑已经成为2006年电信运营系统面临的紧迫问题。因为3G网络的建设及与之相伴的移动数据增值业务的发展将使国内电信运营格局变得更为错综复杂，各种移动数据增值业务获得发展的前提是：在实际的市场考验中吸引并留住客户，同时从客户使用中获取商业价值并实现盈利。3G业务与传统的话音业务在业务模式、市场模式、服务模式上有较大的不同，支撑系统必须对多媒体业务以及丰富的市场和服务模式提供一体化、标准化的支撑。在这种前提下，如何规划建设3G业务计费系统成为目前3G建设准备过程中的关键问题。 3G系统的建设主要是对用于承载业务的基础网络及用于开展业务的业务平台的建设，在业务上将以移动性、个性化、多媒体化和高速接入等为主要特点。3G业务的业务支撑系统，将具备相对复杂的价格体系、繁杂的优惠打折体系、与内容提供商等多方的复杂结算体系。为了给运营商3G计费系统建设提供一些有意义的参考，我们邀请了几大计费厂商的相关计费人员就未来3G计费面临的问题、采取什幺样的计费手段以及该公司提供怎样的支持等问题进行了深入探讨。[编按]     

宽带“按流量计费”需等待时机

宽带资费套餐市场．一直就存在着“按时长计费”和“按流量计费”两种计费模式之争。反对“按时长计费”的人士说。在上网的高峰时段，由于网络拥塞而导致的垃圾等待时长不应该算在用户的帐单上；抨击“按流量计费”的人士说，如果电脑误中病毒。向其它电脑发送数据包产生的垃圾流量不应该让用户埋单。笔分析目前国内宽带市场现状。并借鉴国外运营商相关经验，认为在用户的消费行为偏爱．消费感知和运营商的系统支撑等诸多方面。按流量计费模式都尚不成熟，按时长收费套餐仍是首选。[编按]     

“防静电技术和管理”学术讲座

课程背景 静电在电子制造业中造成严重的破坏已经是个众所周知的事实，然而；隹确的掌握和最适当的控制住静电，却不是如许多人想象中的容易。很多工厂的防静电措施都限于防静电腕带、接地导电桌垫、防静电工衣、防静电包装材料以及离子风机等的采购使用，而缺乏一套科学性的管理来支持。随着业界对防静电意识的增加以及普遍的使用各种防静电材料，以往的静电破坏模式已经大体上得到很好的处理。但随着自动化程度的增加和一些低成本的材料的大量使用，静电破坏模式也在改变中。不同的静电破坏模式需要不同的防御处理做法，对转变的不敏感以及认识不足常常使到业蒙受损失。