关于移动IP技术的研究

为了在移动通信网络中运用IP协议,因特网工程任务组(Internet Engineering Task Force,IETF)制定了Mobile IP协议.Mobile IP是一种简单、可扩展的全球Internet移动解决方案,使节点在切换链路时仍可保持正在进行的通信.文章讨论了Internet移动接入的重要技术--移动IP,对其中的关键技术以及存在的问题进行了探讨.     

基于移动IP组播机制的研究

无线宽带的接入需要目前计算环境提供对固定IP网络主机移动性的支持.一方面,互联网工程专门小组(IETF,Internet Engineering Task Force)在现有IP协议的基础上设计了一种支持主机漫游的网络层协议—Mobile IP;另一方面,作为一种高效的多点通信方式,IP组播在固定IP网络中提供了支持分布式多媒体应用和海量数据传送的机制.以移动IP作为路由协议面向移动主机提供组播机制是一个极具理论和实践意义的研究课题.在对相关文献进行深入研究的基础上,提出了一个新的解决方案,与现有移动IP组播机制仿真试验结果的比较表明,在相同环境下具有较小的资源开销和较高的效率,从而提供更好的网络服务质量(QoS Quality of Service)保证.     

移动IP的快速切换

移动IP协议使移动主机MH实现在任何时间和任何地点接入Internet,使Internet上主机透明地与MH通信。但是 ,移动IP协议的切换时延较长 ,严重影响了通信业务的质量。提出了一种结合层次外部代理管理和转发指针链的快速的移动IP切换算法 ,以改善MH频繁切换时业务的QOS。     

基于自适应策略的移动自组网与Internet互联

将Mobile IP与AODV路由协议进行集成以满足移动自组网MANET的Internet访问需求.Mobile IP的FA通过被动接收、解析源节点发送的RREQ-I以了解源节点数量及MANET规模.FA据此将代理通告的TTL作为参数进行自适应调整以实现最佳的代理通告覆盖.由于自适应协议无需额外开销且能根据MANET实际需要改变其提供全局连接信息的主动程度,而其中间节点也可向源节点及时提供自己侦听到的全局连接信息并抑制广播分组的进一步扩散,因此能为网络条件高度动态变化的MANET提供良好的互联性能并保持合理的开销,用NS2进行的仿真结果证明了其有效性.     

Mobile IP的几种切换策略

Mobile IP在IP层提供移动支持,移动主机可以从一个地方移动到另一个地方而不中断已有的连 接.在Mobile IP切换过程中,可能会丢失一些包,使得上层协议如TCP和UDP的性能下降.为此,提出了 多种切换策略.介绍了其中的几种,并提出了改进的方案6采用预先建立的隧道来降低切换时延,应用本地 广播和DE处的缓存来减少丢包,利用提前的资源预留来保证QoS     

FMC网络中SPIT检测与防范方法研究

随着固定移动融合（Fixed Mobile Convergence,FMC）网络的发展,基于会话初始协议（Session Initial Protocol,SIP）的VoIP（Voice over IP）无疑将成为全IP融合网络环境下最为重要的业务应用。然而SIP在设计之初便存在诸多安全隐患,VoIP又是采用开放、互通的应用模式,因此垃圾语音信息（Spam over Internet Telephony,SPIT）作为一种非预期的语音发送行为,成为全IP语音业务发展中的重要安全威胁。     

移动IP研究中的关键问题

移动IP技术目前已经成为移动通信和Internet结合的最佳技术方案,得到了广泛的关注和研究,在进行移动IP研究的基础上,详细分析了标准移动IP协议中无法解决或者不完善的几个问题,提出了研究思路,为以后的研究提供了参考.     

一种让上网计算机无缝漫游的方案——移动IP

讨论了一个由IETE（互连网工程任务组）所建议的、在目前的IPv4架构之下实现计算机移动通信的路由选择协议－移动IP（Mobile IP),分析了利用它实现计算机无缝漫游的原理,并探讨了移动IP和未来新一代互联网协议IPv6的结合问题。     

移动IP研究中的关键问题

移动IP技术目前已经成为移动通信和Internet结合的最佳技术方案，得到了广泛的关注和研究，在进行移动IP研究的基础上，详细分析了标准移动IP协议中无法解决或者不完善的几个问题，提出了研究思路，为以后的研究提供了参考。     

移动IP切换性能研究

文章介绍了Mobile IP及其移动检测策略,分析了Mobile IP切换过程,然后对重叠情况下移动IP切换进行建模并从理论上分析引发数据包丢失和数据包乱序的各种情况,根据所建立的模型计算出重叠情况下移动IP切换时延,得出重叠区域大小对切换性能的影响,这些理论研究将为移动IP实施QoS保证提供理论依据。     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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