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.     

ELID超精密镜面磨削钝化膜状态变化的研究

建立了ELID磨削系统的电解反应回路等效模型,提出用极间电流表征金属结合剂砂轮表面的钝化膜状态,分析了钝化膜在ELID超精密镜面磨削电解预修锐阶段、在线电解修整动态磨削阶段和光磨阶段的状态变化。     

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。     

运载火箭控制系统半实物仿真一体化智能化应用软件系统

为了进一步完善银河ＹＨ－Ｆ２仿真系统功能，开展一体化智能化仿真支撑软件的研制工作是很有意义的。本文从系统结构和功能等方面对已经研制完成，适用于运载火箭姿控系统半实物仿真的软件集成环境进行了简要介绍。