Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane(GTMS) and zirconium(IV) n-propoxide(TPOZ). Used as inhibitors for corrosion, three types of cerium salts(Ce(NO_3)_3, CeCl_3, and Ce(CH_3COO)_3) were doped into the sol–gel coatings. Fourier transform infrared(FTIR) and scanning electron microscopy(SEM) were employed to investigate the structures and morphologies of various coatings, and the corrosion resistances of the coatings were evaluated by electrochemical methods and neutral salt spray tests. Experimental results indicate that the addition of cerium salts can hinder the process of corrosion due to their self-healing abilities. Furthermore, the sol–gel coating doped with Ce(CH_3COO)_3 has the best corrosion resistance because of the promotions of hydrolysis and condensation provided by CH_3COO.     

2010“太空家园畅想”中小学作文大赛圆满落幕

12月25日,2010年"太空家园畅想"全国中小学航天科幻主题作文大赛颁奖典礼在内蒙古呼和浩特市隆重举行。内蒙古自治区副主席刘福田,中国科学院院士、中国科普作家协会理事长刘嘉麒,长征二号F运载火箭原总指挥黄春平、中国宇航学会副秘书长龚金玉等领导、专家出席仪式并讲话,获奖学校代表、教师和学生共计400多人参加了颁奖仪式。     

大涵道比宽体客机发动机方案设计及系列化发展研究

基于宽体客机航空发动机系列化发展进行了总体性能方案设计,并分别基于保持整机不变和保持核心机不变的原则,对推力系列化发展方案进行了分析。结果表明,对于减推力使用发动机而言,可以直接采用降低高低压轴转速的方式;对于推力增长发动机而言,需重新匹配低压系统以得到更优化的方案。     

Real-time and reliability analysis of time-triggered CAN-bus

Real-time performance and reliability are two most important issues in applications of time-triggered controller area network (CAN) bus systems at present. A scheduling matrix of time-triggered CAN-bus system is established using average-loading algorithm. Periodic messages are guaranteed to transmit without delay by distributing independent transmission windows within the system matrix. Considering the traditional CAN-bus transmission mechanism and the time-triggered feature, an algorithm is improved to calculate the worst-case delay of event-triggered messages in time-triggered CAN-bus systems. The failure probability is calculated for event-triggered messages whose worst-case delay exceeds their deadlines. Different levels of redundant structures of CAN-bus circuits are analyzed and the maintenance management is proposed to improve the system reliability. Finally, the reliabilities of different structures are calculated and the influences of maintenance on the system reliability are analyzed.     

Feedback structure based entropy approach for multiple-model estimation

The variable-structure multiple-model（VSMM）approach,one of the multiple-model（MM）methods,is a popular and effective approach in handling problems with mode uncertainties.The model sequence set adaptation（MSA）is the key to design a better VSMM.However,MSA methods in the literature have big room to improve both theoretically and practically.To this end,we propose a feedback structure based entropy approach that could fnd the model sequence sets with the smallest size under certain conditions.The fltered data are fed back in real time and can be used by the minimum entropy（ME）based VSMM algorithms,i.e.,MEVSMM.Firstly,the full Markov chains are used to achieve optimal solutions.Secondly,the myopic method together with particle flter（PF）and the challenge match algorithm are also used to achieve sub-optimal solutions,a trade-off between practicability and optimality.The numerical results show that the proposed algorithm provides not only refned model sets but also a good robustness margin and very high accuracy.     

串级萃取最优萃取比精确方程

萃取比是优化串级萃取工艺设计中的重要参数。本文导出了计算最优萃取比的精确方程。相同条件下，最优萃取比精确议程的计算结果误差小于现有的最优萃取比方程。当分离系数小于3时，计算最优萃到比既可用最优萃取比方程，也可用最优萃取比精确方程。当分离系数大于3时，计算采用最优萃取比精确方程更为合适。     

玉米空间飞行处理细胞超微结构变异的研究

玉米干种子搭载于返回式卫星上，经离海平面１７６ｋｍ至３５４ｋｍ的空间条件处理，发现处理后的玉米叶片超微结构发生各种变异。主要变异包括：细胞质壁分离，液泡增大，细胞壁加厚、扭曲，胞间连丝增多，出现叶绿体基粒盘和基质类囊体的变异，细胞核和叶绿体变形，内质网的数量增多、体积增大，以及其它细胞内膜系统与其它超微结构的变化。     

一级燃料箱后底环缝错位的研究

为改善一级燃料箱后底环缝的错位变形，提高产品质量，分析探讨了环缝错位变形的形成机理，从装配和焊接两个方面，提出了相应的工艺措施，并在生产中得到了验证，后底环缝错位明显减小。     

流媒体技术及其应用

本文主要研究了流媒体的相关原理和技术支持，包括流媒体技术基础、流媒体播放方式、媒体服务器平台等主要内容，并简要介绍了视频直播解决方案、校园网视频解决方案和网上流式视音频解决方案等流媒体技术应用方案。     

虚拟维修仿真系统的设计与实现

为解决当前虚拟维修平台在处理维修任务时存在的不足，提出了虚拟维修仿真系统结构框架。将系统结构设计成主要由维修场景构建、维修任务和动作分解及维修性分析评价数据输出三个功能模块组成。基于Jack软件平台完成了系统开发。以某装备维修任务典型工况为例，对系统进行实例验证。结果表明：该系统能有效地加快维修过程的创建，改善了人机界面的交互功能，提高了虚拟维修仿真系统的智能化程度，基本满足了维修仿真的需求，具有可行性与实用性。