IPTV相关技术和标准 第2讲 IPTV业务相关标准（一）

在IPTV业务成为众入关注并被电信运营商看作为业务转型的关键业务之一的同时,有关标准化组织也开始研究和制定IPTV业务的相关标准.如在第1讲中所介绍的,IPTV业务涉及到多种技术,而这些技术都已经发展到了一定阶段,形成了相关的技术标准.下面将介绍与IPTV业务相关的标准化组织、主要标准以及相关标准的最新进展.     

油罐冒罐事故的原因分析及预防

通过事故实例分析，阐述油罐冒罐事故的原因，并针对原因提出要加强操作人员的责任心教育，完善各项规章制度，不断提高操作人员素质，严格遵守岗位操作规程，及时消除设备缺陷、完善罐区硬件设施和罐区实行现代科学管理等项措施。     

Creep and rupture properties of a squeeze-cast Mg-Al-Ca alloy

A squeeze-cast Mg-Al-Ca alloy (MRI153) was creep tested at 150, 175, and 200 °C under applied stresses in the range of 30 to 120 MPa. The creep curves were characterized by an extended tertiary stage in which the creep rate increases progressively with the creep strain. Microstructural examinations revealed the precipitation and coarsening of new particles during creep. The stress dependence of the minimum creep rate suggests a transition from power-law creep at low stresses to power-law breakdown at high stresses. Creep rupture of this alloy occurred as a result of cavitation damage at dendritic grain boundaries, with the creep rupture time and the minimum creep rate following the empirical Monkman-Grant equation. A comparison is made between the creep and rupture properties of MRI153 and those of a squeeze-cast Mg-Al alloy (AZ91).     

液晶分子附着能和盒间隙对响应时间的影响

通过理论分析和实验研究液晶分子附着能和液晶盒间隙对响应时间(τ0)的影响。用液晶盒有效间隙法和表面动力学方程法两种方法推出分析公式,由这两种方法推出的结果是一致的。实验数据与简化方程τ0-dx基本拟合(其中d是液晶盒的间隙,x是指数)。在两种极端的(极大或极小)附着能极限下,指数x分别接近2和1。这个结论有助于优化液晶显示器件的应用。     

膦化合物对加氢催化剂的影响

丁辛醇装置丁醛加氢催化剂在装置扩能投产以后热点上移 (失活 )的速率较快 ,针对催化剂老化的原因进行分析、判断 ,找出原因 ,采用相应的解决措施 ,可延长催化剂使用寿命 ,增加装置效益     

一个基于J2EE Web应用的框架设计与实现

J2EE(Java 2平台企业版)是当前建立和开发各种Web应用的主流平台,MVC(模型-视图-控制)体系结构是当今设计交互式应用的事实标准.文中结合MVC在J2EE Web中的应用,通过电子政务系统开发实践,提出了一个具体的实现方案,描述了应用系统设计,给出了表示层、控制层、代理层、业务逻辑层、数据访问层和数据存储层等层次的明确划分,阐述了各层的功能作用以及层与层之间的关系,并针对具体业务给出了实现的部分具体内容,为在J2EE环境下开发结构良好、易于维护、易于扩展的Web应用提供了可行方案.     

Fabrication of Ormocer Containing Eu3＋ Ion and Their Optical Spectra

Eu3 ions were incorporated in sol and gel by a sol-gel processing using 3-glycidoxypropyltrimethoxysilane(CH2OCHCH2O(CH2)3Si(OCH3)3, GPTMS) and ethyl silicate (TEOS) as precursors. The basic chemical-physical properties such as DTA curve, FF-IR spectra and specific surface area were recorded. The characteristics of their optical spectra were measured and investigated. The results indicate that the emission intensity of Eu3 ion in ormocer is much higher and the global line width is wider than those in SiO2 gel. The relationship between the composition and structure of gels and the fluorescence intensity and width were discussed. The obtained ormocer shows good mechanical strength, which can be cut and polished in machine without broken.     

碲镉汞外延晶膜的不稳定性

利用变温和变磁场霍尔测试对在空气室温环境长期存放的碲镉汞液相处延晶膜作了定期的检测，结果表明，晶膜的电学性质随时间有明显的改变，本文采用非均匀晶膜的层状模型对晶膜的不稳定性作了详细的分析。     

Novel polymeric aromatic lithium sulfonylimides as salts for polymer electrolytes

Three new polymeric aromatic lithium sulfonylimides were used as salts in high molecular weight poly(ethylene oxide) (PEO) electrolytes. Their conductivity and electrochemical stability behaviors were investigated. The electrolytes with lithium poly[4,4′‐(hexafluoroisopropylidene)diphenoxy]sulfonylimide (LiPHFIPSI) showed a better conductive performance compared with the other two lithium salts. The best conductivity was obtained for PEO/LiPHFIPSI EO/Li = 16 (1.90 × 10^?4 S/cm at 60°C). Thermal analysis indicated that the salts effectively decreased the crystallinity of PEO. Moreover, the electrolytes also had good electrochemical stability and their oxidative potential was to 5.5 V versus Li/Li⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1802–1805, 2002     

甜菜aa核不育研究之二──利用甜菜aa核不育系改良育种材料的方法与程序

论述了利用甜菜aa核不育系改良育种材料的先进性和优势，以及利用aa核不育改良雄性不育系自身及育种材料经济性状和抗病性能的方法与程序。