2007年"世界电信和信息社会日"解读

继本刊2007年第1期刊发了国际电联副秘书长赵厚麟先生为本刊读者的新年贺辞后，2007年4月17日本刊又收到赵厚麟先生从日内瓦发来的文章，其中全面解读和诠释了2007年5月17日“世界电信和信息社会日”的来由和将其主题确定为“让信息通信技术惠及下一代”的重要涵义，在此我们将全文刊出以飨读者，让我们共同为世界电信和信息技术的发展做出努力。[编者按]     

热载流子注入对MOS结构C─V和I─V特性的影响

讨论了热载流子注入对ＭＯＳ结构Ｃ─Ｖ和Ｉ─Ｖ特性的影响。指出热载流子效应引起载流子陷落和界面态的产生，导致Ｃ─Ｖ特性曲线畸变、平带电压漂移和恒定电压下ＳｉＯ２漏电流随时间漂移。本文论述了这些漂移的机理，提出了漂移的ｔｎ物理模型，从而很好地解释了实验所观察到的现象。     

石家庄市CATV系统网络技术指标分配初探

在ＣＡＴＶ系统网络工程设计中，技术指标的分配产关键问题。本文介绍了石家庄市在系统设计时采用的符合实际的设计程序，并对系统前端，传输及用户网各部分技术指标的确定，计算与分配方法，指标的核算等作了较详细地阐述，以供同行参考。     

Liquid crystalline hexa-amides and side chain polysiloxanes of azacrown [18]-N6

The hexa-4-dodecyloxybenzoyl derivative 1 of azacrown [18]-N₆ was originally reported to have a 'tubular' mesophase on the basis of its large central ring and 6-fold symmetry. Starting in the mesophase, annealing of 1 under a cover slip results in formation of a new crystalline phase that melts directly to an isotropic liquid at the temperature previously observed for the mesophase to isotropic transition. Thus the phase behaviour of 1 is kinetically controlled. The analogous hexa-3,4-bisdodecyloxybenzoyl derivative 2 of azacrown [18]-N₆ has no kinetic limitations to its phase changes and has an enantiotropic columnar liquid crystalline phase. We have synthesized side chain copolysiloxanes with a (CH₂)₁₁ spacer and 75-84 per cent by weight of the same 4-dodecyloxybenzoyl-[18]-N₆ mesogen. The polysiloxanes also display a liquid crystalline phase.     

DIGITAL PROCESSING OF THE POLARIZATION STATE OF GEOPHYSICAL ULF SIGNALS

In this paper, the evaluation by running window smoothing is used for the digital processing of the polarization of geophysical ULF signals. The observed signals are resolved into two orthogonal complex components so that it is no longer necessary to consider the phase and amplitude of the signals simultaneously.     

Comparisons of PWM and one-cycle control for power amplifier with multilevel converter

Based on the concepts of cascade multilevel converters and one-cycle technique, comparisons are conducted to characterize the distortion of the pulsewidth modulation (PWM) and one-cycle control methods that were applied to converters. Simulation results for the different control schemes are obtained in PSIM software initially to see the effect of one-cycle control different from that of PWM control. Through the comparisons, the advantages and disadvantages are identified for each method. The one-cycle scheme is better than PWM control in reducing undesirable harmonics and tracing dynamic waveforms. Simulation and experimental results are also provided to verify the conclusions.     

移动互联网和它的增值业务

概述 通信发展的几个必然趋势 理想通信的目的:任何时间;任何地方;任何空间能随机地找到任何人,传送任何信息,全球一个网.     

An implementation of the vectorial finite element analysis ofanisotropic waveguides through a general-purpose PDE software

This paper reports on the major progress in the development of an intelligent, interactive and automated system, based on the vector finite element method, and implemented within PDE/Protran problem solving environment. The system is known as WAVEGIDE and was originally developed by the authors for an efficient solution of inhomogeneous dielectric waveguides. In this paper, it has been further extended to the solution of anisotropic waveguiding structures. With our system, through an interactive “question-and-answer” session, which requires minimal knowledge of programming, the problem can be defined using high level PDE/Protran commands. It can then be simply and quickly solved by the main processor within this intelligent environment. To verify the convergence and accuracy of the present approach, numerical results (with respect to the grid density and element order) for a rectangular metallic waveguide half filled with dielectric are given and compared with other finite element methods. Numerical results for an anisotropic dielectric rectangular waveguide are also presented. These results clearly illustrate the accuracy and the ease of use of the modified WAVEGIDE program     

一种低压低功耗SRAM/SOI单元设计

提出一种改进4管自体偏压结构SRAM/SOI单元.基于TSUPREM4和MEDICI软件的模拟和结构性能的分析,设计单元结构并选取结构参数.该结构采用nMOS栅下的含p+埋沟的衬底体电阻代替传统6管CMOSSRAM单元中的pMOS元件,具有面积小、工艺简单的优点.该结构可以在0.5V的电源电压下正常工作,与6管单元相比,该单元瞬态响应正常,功耗只有6管单元的1/10,满足低压低功耗的要求.     

高功率双工旋转场移相器

旋转场移相器具有移相精度高(均方根误差可小于1°)和温度稳定性好等特点,通过改进射频传输结构,可大大提高他的功率容量。利用旋转场移相器的互易特性和铁氧体圆极化器的非互易特性,设计出高功率双工旋转场移相器。其双工特性可将收/发信号分开,实现移相器和环行器的双重功能,用于天线的收发通道等场合时,可省去一个高功率环行器,结构紧凑。分析了双工旋转场移相器的工作原理,阐述了高功率应用下的设计方法,推导出了管状铁氧体的相移量计算公式,按此方法设计了实用的器件,并给出了试验数据。