Design of LICVD equipment for preparation of nano powder and study on laser threshold

A laser-induced chemical vapor deposition (LICVD) nanometer equipment is designed and fabricated. The design conception of key parts is expatiated. The energy threshold of SiH4 decomposing is studied. In the condition of same reactive gas flux, the laser energy threshold decreases with the increase of SiH4 concentration. In the condition of same SiH4 concentration, with the increase of reactive gas flux, the laser energy threshold which induces SiH4 decomposition increases linearly at the beginning, and when the flux is more than 100 ml/min, it turns to increase slowly. The factors which influence the laser threshold are analyzed.     

烯烃及α,β-不饱和醛、酮在气相中的无催化环氧化反应

概述了碳碳双键在气相中无催化环氧化反应研究方法、反应机理、测定了2－甲基丙烯醛与过氧化乙酰基在393K和413K时环氧化反应的速率,实验结果表明，不同结构烯烃的环氧化反应速率主要取决于双键所连取代基的性质，取代基的给电子能力越强环氧化反应速率越快。     

基于气相色谱法危废品仓库中非甲烷总烃在线监测系统研制

研制了一套基于气相色谱法的危废品仓库中非甲烷总烃的在线监测系统。该系统采用气相色谱原理对样品进行分离,经火焰离子化检测器电离形成微电流,通过信号放大器检测并换算成烃类含量。经联动调试检测显示,系统的示值误差小于±2.5%,零点漂移小于±5%F.S.(传感器满量程误差的百分数),量程漂移小于±5%F.S.,响应时间小于300 s,系统各项技术性能指标均满足并优于《上海市固定污染源非甲烷总烃在线监测系统验收及运行技术要求》,具备推广和应用价值。     

(La0.57Ce0.1)Sr0.03MnO3纳米材料的低温合成及其磁热效应研究

采用聚合物前驱体方法,以H5DTPA为配位剂,低温下合成出(La0.57Ce0.1)Sr0.03MnO3纳米颗粒.用TGA-DTA对凝胶前驱体的热分解历程进行分析,采用XRD,高分辨透射显微镜(HRTEM)对凝胶前驱体不同温度下烧结所得粉体的相组成和微观结构进行研究.采用PPMS对(La0.57Ce0.1)Sr0.03MnO3纳米颗粒的磁性能进行了测量.结果表明:凝胶前驱体经600℃烧结2 h可以得到纯钙钛矿型(La0.57Ce0.1)Sr0.03MnO3纳米粉体,平均粒径为40～50 nm;(La0.57Ce0.1)Sr0.03MnO3纳米粉体的居里温度TC为368 K.     

基于电化学噪声研究模拟海洋大气环境下304不锈钢的点蚀行为

基于电化学噪声技术建立了不锈钢海洋大气点蚀监测系统,利用该系统对处于干湿循环环境下不锈钢的点蚀行为进行监测. 使用时域谱图、时域统计、频域谱图和散粒噪声理论等分析方法对采集到的电化学噪声数据进行处理分析,并结合动电位极化法,形貌分析法共同研究不锈钢的点蚀行为. 研究结果表明,304不锈钢在模拟海洋大气环境下的点蚀行为分为钝化、亚稳态点蚀和稳态点蚀三个阶段. 在钝化阶段,电位电流噪声信号出现少量的同步异向波动,腐蚀事件发生频率高,平均电量低;在亚稳态点蚀阶段,电位电流噪声信号出现大量的同步同向波动,腐蚀事件发生频率降低,平均电量上升,通过扫描电镜观察蚀点;在稳态点蚀阶段,电位电流噪声信号不仅存在大量的同步同向波动,还出现了同步异向波动,腐蚀事件发生频率较低,平均电量大幅度上升,通过扫描电镜观察到电极表面出现小而浅的蚀点. 而动电位极化法可以证实304不锈钢点蚀的发生. 两种分析方法所得结果具有较好的一致性,证明该监测系统很好地实现了对模拟海洋大气环境下304不锈钢点蚀行为的连续监测,并能判断点蚀的发生.     

基于遗传算法的一种Tikhonov正则化改进方法

就Tikhonov正则化方法求解第一类算子方程进行了新的探讨,针对展平泛函的极值处理,采用了遗传算法来解决.结合遗传算法的优点,扩大了解决问题的范围.介绍了其基本原理及运算流程,作为此方法的应用,首先对一变截面悬臂梁模型进行截面积反求,另外解决了一个热传导反问题实例,证明了其方法的有效性.     

A Possible Structure of the Al36 Cluster： Coexistence of Icosahedral and fcc-Like Structures

We study the atomic and electronic structures of the Al36 cluster using first principles total energy calculations with the local density approximation, and obtain a structure which has a HOMO-LUMO gap as large as 0.67eV, in agreement with experimental photoelectron spectroscopy. Its atomic structure is found to show the coexistence of icosahedral and fcc-based structures, which can be seen as a transition phase from icosahedral to fcc-bulk structures.     

Design of LICVD equipment for preparation of nano powder and study on laser threshold

A laser-induced chemical vapor deposition (LICVD) nanometer equipment is designed and fabricated. The design conception of key parts is expatiated. The energy threshold of SiH4 decomposing is studied. In the condition of same reactive gas flux, the laser energy threshold decreases with the increase of SiH4 concentration. In the condition of same SiH4 concentration, with the increase of reactive gas flux, the laser energy threshold which induces SiH4 decomposition increases linearly at the beginning, and when the flux is more than 100 ml/min, it turns to increase slowly. The factors which influence the laser threshold are analyzed.