基于平均度与平均聚类系数的RWP模型的研究

RWP模型作为节点仿真移动模型被广泛应用在传统移动自组织网络研究中,而机会网络作为移动自组织网络的一个分支,具有不保证连通的网络拓扑特性,这种特殊性可能导致RWP模型不适合作为仿真机会网络的节点移动模型.结合复杂网络理论中平均度与平均聚类系数的概念,对RWP模型仿真数据与实验数据进行了对比分析.分析结论指出,在平均度相近的条件下RWP模型的平均聚类系数与实验数据有明显的差异,因此RWP模型不适合作为描述机会网络的移动模型.     

基于掌形积分的路由协议仿真与性能分析

现有基于RWM移动模型的自组织网络路由协议仿真经常会引起一些问题,如平均运动速率衰减、移动节点分布不均匀等,使得路由协议的仿真不准确.针对这些问题,本文应用掌形积分对RWM移动模型的初始化重新进行了设计,该设计方法简单、易于实现.在此基础上,作者仿真了自组织网络常用的路由协议并进行性能分析.仿真结果表明,在RWM移动模型和修改后RWM移动模型下的路由协议性能存在差别.RWM移动模型的平稳性会对路由协议性能产生显著的影响.     

无线网络中节点移动性对病毒传播行为的影响

结合无线网络上病毒传播的实际特点,以蓝牙网络为载体,通过在SIS传播模型上引入移动的网络节点,分析和研究节点的移动速率对病毒传播的影响.数值仿真采用类似于蜂窝网络的拓扑结构,使网络中的节点按照指定的角度和速度在指定的网络区域内朝任意方向移动以建模实际网络拓扑的动态变化.结果表明节点移动越活跃,网络病毒感染速率越快,网络中被感染的节点数就越多.因此,通过控制网络中节点的移动速度来抑制无线网络中病毒的传播,进而为网络管理部门部署病毒的预警和控制措施等提供一些有意义的理论指导.     

一种基于节点运动范围自感知的路由方法

针对传统的路由协议不能适应移动网络中由于节点稀疏分布、频繁断开或周期性移动造成的节点间歇性连接的情况,文中在网络状态未知的情况下,提出了基于节点运动范围自感知的路由协议MSAR.它不需要地理位置定位等硬件的支持,利用节点历史相遇信息来分析节点的运动范围,选择运动范围重叠较小的节点来转发消息.仿真实验结果表明,MSAR路由协议能够保证较高的消息交付比率和相对较低的平均延时,并能够大量减少消息在网络中的分发数量,减小网络开销.     

节点移动速率对Epidemic协议性能影响分析

当容迟网络DTN中的传感器部署于城市环境下, 携带传感器的移动对象存在多种选择的问题. 文章在城市场景下分别设置传感器部署于较低移动速率节点组与较高移动速率节点组, 并基于工作日模型仿真Epidemic传染路由协议. 实验结果表明, 传输覆盖半径为10米时, 传感器携带于较高平均速率的移动节点组可以提高数据投递成功率与降低DTN的网络负载.     

基于RPGM模型的Ad hoc路由协议的构建与仿真

为了改善无线Ad hoc网络中由于无线节点的移动所导致的网络性能下降,根据移动节点群体的特征,利用LANMAR作为簇间路由协议和AODV作为群组内的平面路由协议,提出一种基于参照点的群移动模型(RPGM)网络协议 MAG-Lanmar,并采用Ns2网络仿真工具进行了模拟测试.仿真结果表明,MAG-Lanmar无线网络协议在路由负载、响应时间、网络平均吞吐量方面,均有良好的性能.     

应用粒子群优化算法的航空自组网移动模型设计

为解决目前在航空自组网的研究过程中没有适用的移动模型问题,采用理论分析和实验仿真的方法,先对常用移动模型进行综述分析,在粒子群优化算法的基础上,结合AANET拓扑特点,提出一种基于PSO路径优化的移动模型,并在NS2平台上进行实验论证.研究结果表明:在节点高速运动情况下PSO模型比RWP模型更加稳定,网络吞吐量更大.该研究结果为航空自组网的研究提供模型参考与使用价值。     

战术Ad hoc网单元群组移动模型研究

提出以指挥员节点为参考点且更加接近真实战术的战术Ad hoc网单元群组移动模型.分析模型中战士节点运行特点和不同参数设置对节点路径有效性的影响.通过模型仿真与网络实际情况对照分析,证实了新的群组移动模型的可用性.     

基于真实场景下的DT-MSN性能分析

由于DT-MSN中节点的移动规律对网络性能起着关键的作用,本文采用真实场景中节点移动轨迹的样本,提取节点的移动规律,从而建立了容延迟移动传感器网络中移动节点间可通信概率的模型,并应用通用分析模型对网络进行了性能的分析,最后基于Randomized Routing下用仿真检验了该模型的可行性.它能在布置网络前提供技术参考,具有重要的实际应用价值.     

基于节点通信监听机制的高效感知消息传输机会网络路由研究

针对采用社区划分策略的机会网络路由算法在消息传输过程中存在冗余转发的问题,设计节点通信监听机制,构建了新的消息传输策略,以高效感知邻居节点社区属性信息;并充分考虑携带移动设备的人的移动轨迹特点,设计了社区移动模型;嵌入时间片轮回机制,对网络节点进行动态划分社区;最终提出了基于节点通信监听机制的高效感知消息分发机会网络路由算法。在社区内转发消息时,选取与目的节点通信范围重叠区域内的邻居节点作为下一跳,若不存在这样的节点则将消息转发给与目的节点相遇概率较大的邻居节点或目的节点;在社区间转发消息时,算法选取与目的社区通信概率较大的中继社区节点转发消息,通过充分利用通信重叠区域内的节点转发消息,优化转发节点判定机制,重设消息传输条件,降低消息转发次数,从而提高消息传输成功率,降低传输时延。理论分析和仿真结果显示:与当前机会路由算法相比,新算法的传输成功率以及转发效率更高、平均端到端时延与平均存储时间更低。     

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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