UL简介与CCL认可

本文从六个方面对UL的基本知识作了一个简要的概述及CCL认可过程的介绍,希望能为业界同仁提供一个参考方向。     

非均相成核中间相炭微球的形成过程及其结构演变

以含有喹啉不溶物的煤焦油沥青为原料，在410℃、不同反应时间下获得一系列中间相炭微球(MCMB)和小于0．5μm的碳质颗粒(SCP)。通过对中间相沥青的软化点、族组成和MCMB、SCP的形貌及MCMB断面结构的分析，认为非均相成核MCMB的形成和生长过程不同于均相成核的融并生长过程，而是SCP碳质颗粒的构筑过程，我们称之为“球形基本单元构筑”过程。在MCMB生长过程中，体系的黏度对SCP的形成和MCMB的生长起着重要的作用。非均相成核MCMB的内部结构不是三种模型结构(“地球仪”型、“洋葱”型和“同心圆”型)中的任一种，而是炭层具有收缩点的复杂结构，并且球体的结构不具有“继承性”，即随着反应时间的延长而不断发生变化和调整。MCMB内部分子在球体生长过程中的主要变化趋势是分子的不断缩合长大，而不是分子片层的平行趋向。     

不用专门相移装置的三维面形测量

提出一种不需要专用相移装置实现相移，主要利用数字图像处理技术实现三维面形测量的方法，研究结果表明，用原干涉图像及1幅以上的移值条纹图主可能实现物体三维面形的测量。     

水布垭混凝土面板堆石坝填筑料开采爆破试验

清江水布垭混凝土面板堆石坝坝高237.0 m,是世界上最高的混凝土面板堆石坝.为了满足设计对填筑料提出的严格的级配要求,在大坝填筑前针对ⅢA、ⅢB、ⅢD填筑料进行了大规模的生产性爆破试验,以确定合适的各种料的爆破参数.简要介绍了试验的成果和初步分析结论,探讨了爆破参数的选择、爆破效果的预测等.     

基于有线电视网络平台视频点播技术的实现

通过对有线电视网络的频带划分、拓扑结构的介绍以及真视频点播 (T -VOD)技术对通信网络要求的分析 ,深入剖析T -VOD技术在有线电视网上的实现策略 ;另外通过对T -VOD系统以及N -VOD系统典型实现的体系结构和性能特点的分析 ,全面地总结了有线电视网上视频点播技术的实现方案 ,并最终提出有线电视网上实现双向数字业务的一种构想     

一种新的PCC-OFDM定时时偏盲估计

多项式相消编码PCC是一种编码技术，在PCC—OFDM调制中，它把将发送的信息调制到一组加权的子载波而不是单个子载波中去。PCC能够显著地降低OFDM对载波频偏的敏感性。本文对PCC—OFDM系统提出了一种新的定时盲估计，估计器是在接收机中的FFT之前进行的。基于PCC—OFDM的符号波形特征，构建定时时偏估计度量函数。最大化度量来估计定时时偏。本估计器不需要训练序列、导频信号或周期前缀。仿真表明，估计器在一个OFDM符号内收敛，且误差较小。     

Crystalline and viscoelastic properties of branched polyethylenes synthesized using bidentate nickel (II) catalyst

In this work, five branched polyethylenes with different branching units were synthesized using bidentate nickel (II) catalyst containing -diimine ligands. For comparison, one linear polyethylene was also prepared using tridentate iron (II) catalyst containing -diimine ligand. The crystalline structure of the polyethylenes was investigated using X-ray diffraction (XRD) and polarized optical microscope. The crystalline properties were also measured by differential scanning calorimeter (DSC). Viscoelastic properties of the polyethylenes were investigated using rheometric dynamic analyzer. The DSC and XRD results showed that highly branched polyethylenes exhibit no melting points and no predominating crystalline forms, while the linear polyethylene exhibits clear orthorhombic (110) and (200) reflections on XRD pattern and a clear melting point at 118 °C. The viscoelastic properties of the branched polyethylenes were very complicated due to the combined effect of the molecular weight difference and the degree of chain branching as well as the branching structure.     

Distributed Speech Recognition Systems and Some Key Factors Affecting It''''s Performance

1　IntroductionWiththerapiddevelopmentofInternetandmobilecommunications,theresearchonwirelessmobilenetworkshasbecomethenewhotspotinin formationtechnologyfield .Asweknow ,mobileterminals (mobilephone,forexample)arethetooltohelppeopletoaccessanyinformationtheyneedbyanymediaatanytimeandanywhere .However,itissometimesdifficultformobileterminalstoplaysucharolebecauseofthelimitationssuchaslimitedca pacity ,lowpower,andinconvenienceinoperating .So,peoplehopetofindanotherwaytoaccessnet workinformatio…     

A reactive molecular dynamics model of thermal decomposition in polymers: I. Poly(methyl methacrylate)

The theory and implementation of reactive molecular dynamics (RMD) are presented. The capabilities of RMD and its potential use as a tool for investigating the mechanisms of thermal transformations in materials are demonstrated by presenting results from simulations of the thermal degradation of poly(methyl methacrylate) (PMMA). While it is known that depolymerization must be the major decomposition channel for PMMA, there are unanswered questions about the nature of the initiation reaction and the relative reactivities of the tertiary and primary radicals formed in the degradation process. The results of our RMD simulations, performed directly in the condensed phase, are consistent with available experimental information. They also provide new insights into the mechanism of the thermally induced conversion of this polymer into its constituent monomers.     

Synthesis and characterization of novel diimide–dinaphthols and resulting poly(urethane–imide)s

Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry