一种新的基于DCRS的LEO信道分配策略

为提高LEO(low earth orbit)卫星通信系统中系统的信道利用率,在小区用户分布不均匀的前提下,基于动态分配预留保护信道DCRS(dynamic channel reservation scheme)的方法,提出了一种适合于LEO卫星通信系统的信道分配策略.该策略能根据系统中切换呼叫和新呼叫的比例,动态地分配预留的保护信道.仿真结果表明,与传统的固定分配预留保护信道FCRS(fixed channel reservation scheme)的策略相比,在保证一定切换呼叫阻塞概率的情况下,该策略能有效地降低新呼叫阻塞概率,提高信道利用率和系统的QoS(quality of service).     

利用asterisk构建小型IP呼叫中心

IP呼叫中心由于其价格低廉,维护简单,升级成本低等的优势,越来越受到中小型企业的关注,市场需求也日益增加。对开源PBx项目Asterisk．中的队列进行原理分析,并利用队列的排队和自动呼叫分配功能设计了一个小型IP呼叫中心的原型,以该原型为核心可以扩展成更加完整和多功能的企业级呼叫中心。     

蜂窝系统中一种基于抢占优先的保护信道策略

在分析蜂窝系统信道分配问题的基础上,提出一种适用于语音、数据呼叫的蜂窝移动通信系统的信道分配策略.该策略将信道分为3部分:数据信道、语音新呼叫保护信道和语音切换呼叫保护信道,为语音新呼叫和语音切换呼叫分配保护信道以降低呼叫阻塞率.为了进一步提高系统承载的语音业务量,赋予语音呼叫抢占优先权,语音呼叫可以抢占数据信道;语音...     

基于IP地址动态分配的IP电话实现方案

文章介绍了目前IP电话的各种实现方案,分析了纯软件IP电话的不足,提出了一种基于IP电话号码的实现方案。该方案通过服务器给每位用户分配一个惟一的IP电话号码,用户直接通过该号码相互呼叫,这样不仅可以实现IP地址的动态分配,而且使得呼叫过程更加简洁。最后简单介绍了该软件在Linux和Windows下用JAVA的实现。     

基于局部区域的移动性管理策略

基于用户呼叫和移动的局域性提出了一种基于局部区域的多层结构位置管理策略，并对其代价和呼叫建立时间进行了分析，结果表明只要局部区域选择恰当，呼叫移动比稍高时该策略优于基本策略．     

基于局部区域的移动性管理策略

基于用户呼叫和移动的局域性提出了一种基于局部区域的多层结构位置管理策略，并对其代价和呼叫建立时间进行了分析，结果表明只要局部区域选择恰当，呼叫移动比稍高时该策略优于基本策略。     

聚结CAP在求解频率分配问题中的应用

频率最少角网格图方案。信道分配问题（CAP）是无线蜂窝网中的一个重要方面,它根据呼叫请求对频率进行分配,同时使得整个网络所需的文中描述了一个有效的频率分配策略（聚结CAP）,它源于多重染色算法,所用模型基于移动通信网络中常用的三同时,该方案是分布式的,即网络中每个基站只需要和其邻接基站之间交换部分信息,即可得出自身的频率分配方案。     

CDMA系统的一种动态呼叫接入控制策略

CDMA系统在区间业务不平衡的情况下会出现高的阻塞率,为了改善系统性能,论文中提出了基于动态资源预留的呼叫接入控制策略,在各个小区中为邻区即将到来的呼叫预留部分资源,预留的大小随呼叫阻塞情况自适应地调整.仿真结果表明,这种策略能很好地解决区间业务不平衡的问题,而且与基于固定资源预留的呼叫接入控制策略相比,该策略能够跟随话务量的变化,保持良好性能.     

一种基于VP／VC的动态带宽分配机制

提出了一种基于ATMVP/VC技术的动态带宽分配和网络自愈机制,该方案在确保网络业务的可恢复性前提下,将呼叫接纳控制、VP带宽分配、网络逻辑空闲容量分配集成一起,使网络吞吐量最大化.     

保证服务的延迟划分方法--能者多劳法

实现Ｉｎｔｅｒｎｅｔ集成服务的一般手段为采用资源预留协议（ＲＳＶＰ）进行资源预留,其中的一个主要问题就是预留多少资源和如何提高呼叫的准入率,文中研究了可保证服务的呼叫准入控制和资源分配问题,提出用能者多劳法取代现有的“准等额分配法”,以提高网络的呼叫准入率,并给出了能者多劳法的推导过程和实施方法,计算机仿真证实,“能者多劳”法优于“准等额分配法”。     

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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