Multicomponent film-penetration theory with linearized kinetics—II. Particular cases and tests

The matrix results required for the evaluation of all interfacial flows at the film theory limit are presented for the multiple reaction system A → C ? B with linear kinetics and the single reaction system A + 2B ? C with linearized kinetics. The yield of C is calculated in the former case and the enhancement factor for A is calculated in the latter case when B is nonvolatile and the reaction is irreversible.The single reaction, A + 2B ? C, as well as A + B ? C + D, is considered further for testing the linearized solution against the exact numerical calculations of the enhancement factor with the nonlinear kinetics. The results indicate that the linearization theory can be applied with a maximum error of 10 per cent and, in most cases, with a considerably smaller error over the complete range of gas—liquid contact times.     

固溶态染料激光材料基质的合成和性能的研究

以甲基丙烯酸甲酯/甲基丙烯酸(MMA/AA)共聚物为基本组分,加入尿素,以双甲基丙烯酸乙二醇酯(DMEG)为交联剂,本体聚合制得固溶态染料激光材料的基质。AA对激光染料Rh6G有增溶作用,MMA/AA=8/2(mol)时。Rh6G的浓度可达4×10~(-3)M。AA和尿素均有利于Rh6G二聚体转变为单分子,在MMA/AA=7.6/2.4(mol)溶液中,尿素为4％时,Rh6G的发射荧光光强I_F与在乙醇溶液中的I_F几乎相同。DMEG可有效地提高基质的T_g、硬度和热稳定性。基质有良好的透明性,其透光率基本上与纯PMMA相同。     

助力3G发展——“三不原则”实现原理透析

“三不原则”是运营商为推动3G发展出台的重要政策。本文对“三不原则”的实现原理进行了探讨,对终端和网络升级修改的内容进行了介绍,分析了利用SIM卡接入3G网络的用户鉴权过程,2G/3G互操作机制以及为优先接入3G所做的门限参数改进等,并针对“三不原则”的意义和作用做了总结。     

Policies for the reconfiguration of cognitive wireless infrastructures to 3G Radio Access Technologies

The ceaseless evolution of wireless communications is reflected nowadays on the introduction of Beyond-3G (B3G) systems, characterized by the coexistence and cooperation of various Radio Access Technologies (RATs), over a common infrastructure. Major facilitator of this convergence is the advent of cognitive networks, which deploy elements (base stations and mobile terminals) that are able to proactively adapt to environmental stimuli, so that to optimize their performance. Part of the adaptation action takes place in cognitive base stations that own several reconfigurable transceivers, which are controlled by appropriate management functionality and may dynamically change their operating parameters. Each reconfiguration set includes a specific RAT, carrier frequency, as well as demand volume to be allocated per transceiver. Accordingly, proper evaluation of the various candidate reconfiguration sets appears to be of high significance. To this effect, in this paper we consider a cognitive network segment with transceivers operating at 3G RAT/carrier and we solve the DAMC problem (Demand Allocation into Multiple Carriers problem), which aims at evaluating and selecting the optimum policy to allocate the demand into the available 3G carrier frequencies. Optimality is expressed in terms of minimizing the total transmitted/received power per base station, thus deciding for the reconfigurations with the least impact on network interference. Indicative simulation scenarios and results are also presented for the validation and verification of the proposed functionality.

数字电视抗脉冲噪声干扰测试原理浅析及SFU实现

数字电视接收机抗脉冲干扰（TII,Tolerance to Impulsive Interference）测试是数字电视系统测试的一个重要组成部分,传统的抗脉冲噪声测试采用简单的对AWGN噪声门取样（GAWGN,Gated AWGN）的方式实现,但是实际物理环境中的脉冲噪声十分复杂,单纯基于GAWGN,测试是不完善的,尤其对于基于OFDM调制的地面数字电视系统。本文介绍了欧洲DTG（Digital TV Group）组织关于脉冲噪声干扰（Ⅱ,ImpulsiveInterference）的研究成果——二次AWGN门取样（G^2AWGN Gated—squared AWGN）以及与GAWGN的区别,同时阐述了单载波和多载波调制系统在抗脉,中干扰测试中的不同,并且基于罗德与施瓦茨公司（R＆S）的广播电视测试系统SFU提出了完备的抗脉冲干扰测试方案。     

3G无线网络覆盖和容量的规划设计

随着我国3G系统建设的全面启动,3G网络规划设计已成为研究的热点之一。为了实现建设目标,在进行3G无线网络规划设计时,必须同时考虑覆盖、容量及不同服务质量的要求。文章对无线网络覆盖和容量的规划设计进行了论述,分析了覆盖和容量的关系,讨论了覆盖规划、容量规划等几个重要问题。特别对链路预算、传播模型、容量估算和极限容量等进行了阐述,给出了上行极限容量分析及上行链路容量规划的举例。     

2G／3G多模式控制器应用技术

技术的发展和继承性。决定了传统移动运营商必然要经历2G／3G共存的阶段。文章首先阐明了2G／3G共存期多模式控制器应用的意义和必然性,接着重点对多模式控制器实现的可行性以及实现中的传输融合技术进行了分析和探讨。     

本地传输网3G传输承载方案

文章通过对3G业务特性的分析,给出了3G业务对传输网络、传输设备的要求,针对已经部署的不同的本地传输网架构以及业务发展需求,给出了不同的承载方案,并且论述了不同承载方案的可行性、优缺点及性价比。     

CDMA网络电调天线及其网管系统应用分析

电调天线系统可满足CDMA网络3G业务发展的需求。文章首先介绍了电调天线的原理与应用场景,及其相比于常规天线的优点;接着给出了电调天线综合网管系统的结构和两种组网方式,详述了其应用价值;最后分析了电调天线及其网管系统的应用现状与前景。     

3G时代用户价值评价及应用

文章从用户当前价值和未来价值的角度,建立起3G用户价值评估可量化的评价指标体系,提出了各细分市场用户价值评价的算法,进而给出了基于价值评估的用户发展和管理建议.为运营商3G时代精确评价用户价值、开发3G业务提供了一定的参考.