一种基于链路优化的时延约束组播路由算法

研究具有时延约束的最小代价组播路由问题，提出一种基于链路优化的组播路由算法求解该问题。算法从最小时延树开始，不断地用低代价链路代替树中高代价链路，以求得满足条件的组播树。仿真实验结果表明，该算法能根据组播应用对时延的要求，快速、有效地构造最优组播树，具有较低的时延。     

一种时延受限共享组播树算法

针对目前基于共享树的组播路由算法中有些算法没有考虑时延约束、有些不能准确地选举出树的中心的情况,提出一种新的时延受限共享组播树算法,并对新算法进行算法分析和仿真实验。该算法首先准确地选择出共享组播树的中心,然后以所选举的中心为树根,构造一棵满足时延约束的最小代价组播树。仿真实验表明,该算法所构造的组播树的成功率要高于RAND DCSHARED,M INMAXD CSHARD,DC IN IT IALDCSHARED等算法,同时也能保证多个源结点到成员结点之间的时延约束。     

应用层组播分布式动态路由算法

在深入分析基于虚拟覆盖网上的应用层组播的特点,并建立组播网络路由模型的基础上,针对应用层组播带度约束与时延及时延抖动约束的路由问题,提出一种新的应用层组播分布式动态路由算法,该算法只要求维护网络链路和节点的局部状态信息,不需要维护全局状态信息,从而能够较好地减少构造组播树的开销。仿真实验结果表明,该算法具有较小的时延和较小的代价,能够较好地适用于网络状态变化比较频繁的环境及各种实时多媒体应用。     

基于遗传算法时延与时延差约束组播路由算法

现有组播路由协议提供尽力而为的服务而没有QoS(服务质量 )的支持 .一种启发式组播路由方案考虑了时延与时延差的约束条件 ,可以为应用提供实时性与同步性的支持 .提出了基于遗传算法的时延与时延差约束条件组播路由算法 ,在具有启发式组播算法性能的基础上兼顾组播的代价 ,同时力图减小算法运算复杂度     

BT与RS算法动态仿真测试

基于Mesh网络模型测试了移动IP基本路由算法RS和BT的动态组播特性,包括算法的生成树代价、平均时延、最大时延等性能。仿真测试表明：RS方式比BT方式更有利于网络资源的进一步优化,也更适合于“端到端”时延约束较严格的实时组播业务。     

基于混沌神经网络的QoS组播路由算法

为了改变Hopfield网络的能量函数梯度下降的趋势,对神经元的内部状态施加了一个混沌控制量以控制神经网络的能量函数增加,减少或保持不变。将该混沌神经网络应用于解决QoS组播路由问题,提出了基于该混沌神经网络的QoS组播路由算法。通过计算机仿真,该算法能根据组播应用对费用和时延的要求,快速有效地构造组播树,与当前其它启发式算法相比较,本文提出的算法是可行和有效的。     

基于SDN的工业物联网组播通信框架研究

工业物联网需要提供实时、可扩展的组播通信服务.这要求网络要在给定的时延上界内将数据传递给接收者,同时要能够最大化所承载的应用数.在现有的组播树算法中,单源树算法只关注实时性,共享树算法只关注可扩展性,同时兼顾两者的算法仍有待进一步研究.基于SDN技术,提出了一个面向工业物联网的实时、可扩展的组播通信框架,并为其设计了一个组播树算法——k-DCMO.k-DCMO算法为每个会话构建一棵时延有界开销最小的共享树,能够在保证会话实时性的同时,提升组播的可扩展性.结果表明,k-DCMO算法能够提供共享树算法所不能提供的实时性支持,并且能够获得比单源树算法更好的可扩展性.在实验拓扑中,其开销仅为后者的6.2%.     

一种时延约束的多共享组播树构造算法

该文提出了一种时延约束的多共享组播树构造算法,以解决多点到多点组播路由情况下单棵共享树无法满足时延约束的问题。该算法构造覆盖所有源节点和目的节点子集的多棵共享树以满足时延约束的要求,并通过减少共享树个数降低管理开销。该算法计算以每个节点为中心的共享树所能达到的目的节点的子集,将原问题转换为集合覆盖问题,并采用基于矩阵的启发式算法进行求解。仿真实验将该算法和同类算法进行比较,结果表明该算法在不增加管理开销和中心数的情况下,有效地减少了运行时间。     

PNNI层次网络模型下的动态组播路由算法

提出以通用层次网络模型(PNNI)为基础的,支持带宽-时延约束的动态层次组播路由算法(delay-band-width constrained PNNI hierarchical multicast routing,DB-PHMR).为实现组成员的动态跨域加入,设计了跨域分支计算、中间域内分支细化以及目地域内嫁接点优化等3大步骤.对所构建的跨域组播树不存在环路进行了理论证明.仿真结果表明,DB-PHMR不仅解决了PNNI模型下的时延-带宽约束的动态跨域组播路由问题,且能与各种信息聚集方法无缝结合,在实现信息压缩的同时保持了与平面路由近似的路由效率,实现组播路由在大规模网络下的扩展.     

基于自适应遗传算法的组播路由研究

本文提出一种基于自适应遗传算法,解决了组播路由中既考虑时延抖动,又满足时延约束的NP-complete问题。遗传算法的进化过程中,采用适于此类问题的动态交叉算子和动态变异算子,既克服了遗传算法的早熟收敛性,又提高算法的收敛速度。仿真结果表明本文算法能适应网络的动态环境,快速的,有效的的构建组播树。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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