未来无可预知,未来可以创造

美国知名杂志《新闻周刊》自2013年起,将只发行网络版。《新闻周刊》总编蒂娜·布朗在一篇名为"《新闻周刊》翻过一页"的文章中写道,"我们正在转型,不是结束。"杂志的本质正是一个在统一价值观与志趣下无所不包的载体。事实上,"Magazine"源自于法语,其本意是"大仓库"。早期的杂志,以容纳诗歌、论文等各式各样载体的文章,以包罗万象的取材方式,而成为一种独特的媒介形态。中文翻译也恰如其分     

智能手机:加速手机媒介化进程

随着移动通信技术的不断发展以及用户需求的提升,作为移动业务的载体:手机终端也在不断向前演进,智能化、功能日益强大、应用丰富且扩展性强,它已不是单纯的通信工具,它的媒体化特性进一步凸显,它是第五媒介,它是人的一种延伸,甚至会影响和改变我们本身.     

电视新闻评论的发展

在新闻传播中,新闻报道与新闻评论是两种基本的传播手段。其中,新闻报道的主要任务是传播信息,是新闻传播的主体和基础。新闻评论则是大众传播媒介立场、观点、态度的直接表现,在反映舆论和引导舆论等方面发挥着不可替代的作用,是新闻传播的旗帜和灵魂。随着社会主义市场经济的深入发展,整个中国社会发展进入了一个转型期电视新闻评论节目作为一种信息处理与传递方式,很大程度上承担了对意见性信息的传播,是意见性     

潜伏期和染病期均具有传染性的媒介传染病模型的全局稳定性分析

讨论潜伏期和染病期均具有传染性的媒介传染病模型.得到模型基本再生数的表达式,证明了当基本再生数小于1时,无病平衡点是全局渐近稳定的,此时疾病消亡;当基本再生数大于1时,无病平衡点是不稳定的,系统存在全局渐近稳定的地方病平衡点,此时,疾病将在人群中持续存在,数值模拟验证了理论结果.     

Lattice Boltzmann Simulation of Convection in a Porous Medium with Temperature Jump and Velocity Slip Boundary Conditions

To investigate the convection in a porous medium, a horizontal quiescent layer of one fluid saturating a porous medium heated from bottom is numerically studied using single lattice-Boltzmann method (LBM) and the generalized Navier-Stokes equation proposed by Nithiarasu et al. [P. Nithiarasu, K.M. Seetharamu, and T Sundararajan, Int. J. Heat Mass Trans. 40 (1997) 3955]. Due to the rarefaction, the boundary conditions are considered as both temperature jump and velocity slip. The computational results are validated against the analytical results, and excellent agreement has been obtained. The results have shown that the Rayleigh number is increased with increasing temperature jump, the stabilization effect of temperature is much more significant than that of velocity slip, and the computation stability of present model is better than that of Darcy and Brinkman models.     

探索光纤之谜

<正> 从本世纪70年代初至今,尤其是近20年来,光纤通信迅猛发展,现已在长途干线网中逐步取代同轴电缆、微波等而成为主要传输手段。可以预计,在不久的将来,光纤通信将进入用户网,逐步取代用户网中的音频电缆,从而走进千家万户。所谓光纤通信,是指将要传送的语音、图像和数据信号等调制在光载波上,以光纤作为传输媒介的通信方式。而光纤是迄今为止发现的最适合传导光的传输媒介,是光纤通信系统中不可缺少的组成部分。     

A velocity-difference-separation model for car-following theory

We introduce a velocity-difference-separation model that modifies the previous models in the literature. The improvement of this new model over the previous ones lies in that it not only theoretically retains many strong points of the previous ones, but also performs more realistically than others in the dynamical evolution of congestion. Furthermore, the proposed model is investigated with analytic and numerical methods, with the finding that it can demonstrate some complex physical features observed in real traffic such as the existence of three phases: free flow, synchronized flow, and wide moving jam; sudden flow drop in flow-density plane; and traffic hysteresis in transition between the free and the synchronized flow.     

Curvature relation of wave front and wave changing in external field

Introduction ThestudiesofexcitablemediaconcernwithBZreaction,slimemoldaggregationand cardiactissue[1].Thepropertiesofthesemediaare:forsmallperturbationsthemediaquickly recovertotheirreststates,whileforstimuliexceedingathresholdthemediawillbeactivated andr…     

网络电视系统的结构、接口、层次和组网分析

宽带网络电视系统又称为IPTV系统．是以IP网络作为传输媒介，以LiveTV、Time—Shifted TV和VOD为基本业务并以机顶盒＋电视为接收终端的电视系统。与传统的电视节目不同，IPTV系统通过宽带IP网络直接向顾客提供高质量的电视节目和视频内容。运营商可以在传统电视节目播出的基础上进行业务扩展，提供多种新型增值服务，比如时移电视，