以3G为核心的通信新技术综述

随着第三代移动通信标准的发展,涌现出各种新兴的通信技术,它们所带来的变化是巨大的,影响是深远的。这些技术进步是革命性的,它大大提高并拓展了人与人、人与机器甚至机器与机器之间的通信能力,并进一步挖掘了通信潜力。该文主要系统分析了3G中采用的通信新技术,并对这些新技术的应用前景进行了展望。     

含磷蠕墨铸铁干摩擦过程中质的转移

采用销－盘式干摩擦磨损试验机，系统地研究了含磷蠕墨铸铁／４０Ｃｒ钢干摩擦副摩擦过程中质的转移规律。研究结果表明，含磷蠕墨铸铁／４０Ｃｒ钢干摩擦副摩擦过程中存在着双向质的转移现象。在含磷蠕墨铸铁方，质的转移可存在于距摩擦表面一定深度的次表层；摩擦速度的提高，接触压力的增大及蠕墨铸铁中磷含量的提高都促进了含磷蠕墨铸铁方质的转移向摩擦面更深层的发展。     

雷达电站的模块化设计

从模块化的基本概念出发，结合雷达电站分系统设计的情况，探讨了雷达电站模块化设计的可行性和设计方法。     

The preparation and microwave properties of Ba3ZnZCo2-ZFe24O41/SiO2 microcrystalline glass ceramics by citrate sol-gel process

A series of Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics with Z=0.0,0.4,0.8 and 1.2 were prepared by citrate sol-gel process. The result showed that Ba₃Zn_ZCo_2-ZFe₂₄O₄₁ hexferrite crystallites could be obtained by this process at 1200 °C in the system of BaO-Fe₂O₃-CoO-ZnO-SiO₂. The complex dielectric constant and complex permeability of Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics calcined at different temperature were measured in the range of 200MHz-6 GHz by transmission/reflection coaxial line method. The complex dielectric constant and dielectric loss exhibited insignificant variety in the whole range of measuring frequencies for all samples. The real part of the permeability decreased as the measuring frequency increasing, and calcining temperature had a clear influence on the value of μ′ for Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics, and so did the content of Zn²⁺ and Co²⁺. The natural resonance phenomenon was observed in μ′′ spectra for all the Ba₃Zn_ZCo_2-ZFe₂₄O₄₁/SiO₂ microcrystalline glass ceramics. The substitution of Zn²⁺ ion and annealing temperature closely affect the resonance frequency, the more the Zn²⁺ ion, the higher the annealing temperature and the lower the resonance frequency. Received: 23 July 2001 / Accepted: 24 July 2001     

Research Challenges for 3G and Paving the Way for Emerging New Generations

The first third-generation (3G) systems are going to be implemented within the year 2001. Academia and industry are, however, already looking for means to improve the system performance further. Spectral efficiency and higher data rate are the goal. In order to achieve this goal, several means have to be combined. The most important of these are interference cancellation and multiuser detection, optimum space-time processing and adaptive modulation and coding. In the future several wireless systems having different performance characteristics, system structure and parameters will exist. This heterogeneity will make the seamless handover from system to system difficult if not appropriately solved. 4G (fourth generation) is an acronym without any generally accepted concept. We describe some desirable goals and features of the 4G systems.     

浅论IEEE802.20标准

IEEE802.20标准是一种正在制订并完善中的无线宽带接入标准。文中介绍了IEEE802.20标准的体系结构,重点分析了标准的工作原理及机制,并与目前流行的无线宽带通信技术进行了比较,最后探讨了IEEE802.20标准的进一步发展。     

卫星通信新技术应用机遇及轨道/频谱管理策略

本文全面论述现代卫星通信新技术在中国的应用机遇和轨道／频谱管理相关策略考虑。     

Antiviral Warrior-APOBEC3G

This paper is to further understand how APOBEC3G can defend the retroviruses and to find new approaches to AIDs (acquired immure deficiency syndrome).The viral infectivity factor (Vif) induces rapid degradation of APOBEC3G by ubiquitination, which is a proteosome-dependent pathway. Precisely speaking, only in the virus-producing cell Vif expression is necessary; in its absence, infection of a subsequent target cell terminates at a postentry step through the action of the human APOBEC3G antiviral mechanism. Vif protein has two domains:one binds to APOBEC3G and the other regulates the degradation of APOBEC3G by a conserved sequence, SLQ (Y/F) LA motif. Recently, the research on Vif has also revealed APOBEC3G is a novel component of innate immune system. In fact, APOBEC3G not only acts in DNA editing to block the replication of retroviruses such as HIV-1, but also is able to defend a wide spectrum of distantly related retroviruses and interferes with HBV through a different mechanism from HIV.     

LCR（G）型重力仪格值因子的测定

本文提出了一种LCR（LACOSTE—ROMBERG）重力仪格值因子的测定方法——短基线全组合法。它比传统的长基线法，具有经济效益好，标定精度高的优点。最后，利用蒙特卡罗法进行了模拟计算，获得了良好的结果。     

我厂开发油井水泥的体会

山东铝业公司水泥厂利用覫3.6m×65m湿法短窑系统开发生产G级高抗硫油井水泥获得成功。采用石灰石、砂岩、铁粉三组分配料,率值控制指标为KH=1.14,SM=2.30,IM=0.64;进行更换燃烧器和窑内预热带增设扬料板的配套改造;水泥粉磨不加任何混合材并严控w(SO3)=1.8%～2.4%,实现了稳定生产油井水泥(达到新标准指标)的目标。