宽带无线接入技术的应用及发展

宽带无线接入技术的发展 近年来，随着电信市场的开放和通信与信息技术的快速发展，各种高速率的宽带接入不断涌现，而宽带无线接入系统凭借其建设速度快、运营成本低、投资回收快等特点，受到电信运营商的青睐。     

基于IP的宽带主干网技术分析

综述了IP over ATM、IP over SDH和IP over WDM三种宽带主干网技术,并系统分析比较了各种技术的优缺点及相互区别与联系,探讨了未来宽带主干网技术的发展趋势,得出了明确结论,为进一步研究IP技术提供了技术基础并开辟了新的思路。     

IP宽带城域网安全与实施

随着网络技术的发展演变,IP宽带城域网已成为宽带网络的发展方向,各种信息化应用都将基于IP技术。本文在分析目前IP宽带城域网在安全应用与管理方面存在问题的基础上,从设备安全、结构安全、应用安全三个方面阐述了如何保障网络的安全性和运行质量,从而构件一个＂可控制、可管理、可经营＂的电信级IP宽带城域网,为各种信息化应用提供一个安全可信的基础点心网络平台。     

宽带接入的技术适用性与应用方式的探讨

接入网是宽带信息网中技术复杂、影响面广的关键部分,各种有线和无线宽带接入技术方兴未艾,至今尚无一种接入技术可以满足所有应用的需要。本文结合各种宽带接入技术的特点,给出不同种类宽带接入技术的适用性分析,探讨宽带接入网的发展方向和网络规划建设所要遵循的原则。     

基于以太网技术的宽带接入网技术的研究

首先提出了当今宽带接入网的各种接入技术、然后研究了在宽带公用网络的环境中应用以太网技术需要解决的问题,并分析了目前一些解决方案存在的问题,提出了适用于公用网络环境的基于以太网技术的宽带接入网。     

家庭宽带ADSL接入技术探讨

随着网络技术日新月异的发展,越来越多的家庭开始接受宽带服务,而网速的快慢成为网络用户普遍关注的问题,用户都希望网速变快,而各种宽带接人技术的发展正是为了迎合用户的这种需求,在这些接入技术中,基于电话线的ADSL技术是最有潜力的宽带网络技术。本文将就ADSL宽带网接入技术的原理、特点及其在家庭宽带中的发展前景作出相应的探讨。     

PON技术发展现状及应用前景分析

PON技术是一种较为先进的通信技术，随着最近几年光纤及光通信设备成本的下降和用户对于宽带质量要求的提高，PON技术在我国逐渐发展起来，并成为现在宽带等通信工程中的一个重要技术。以PON技术为基础的宽带具有使得高带宽、高可靠性、低成本的特点，代表了现在宽带最先进的发展方向。本文主要介绍PON技术的概念特点，以及在我国的发展情况和应用前景。     

HY6000-MMDS微波电视传输系统

HY6000-MMDS微波电视传输系统采用先进的线性大功率砷化镓场效应晶体管放大器、宽带高频模块、高效开关电源、微波锁相频率合成技术、高品质方向滤波器和宽带全向天线设计技术，以及智能化监控技术，具有各种功能和工作状态的指示、显示功能，告警和保护功能，计算机远程监控管理功能，并能与精密频率偏置设备、MMDS加解扰设备适配。产品性能优良，设计水平先进。     

基于宽带CDMA的多用户检测技术

在分析传统CDMA接收机缺陷的基础上介绍了多用户检测理论提出的背景和多用户检测技术的概念，分析了各种多用户检测方案的特点、性能及不足，指出了现有多用户检测技术存在的问题和局限性，对多用户检测技术在第三代宽带CDMA移动通信系统中的应用与实现作了分析，并指出了研究的方向。     

宽带数据通信提速可行性分析及要求

本文主要从宽带提速方面存在的问题对宽带提速线路进行了分析，提出了宽带接入网进行优化的思路，并提出宽带提速对设备技术的基本要求。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has