Optimized growth and dielectric properties of barium titanate thin films on polycrystalline Ni foils

Barium titanate(BTO) thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition(PAD) technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr～ 400 and tan δ < 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.     

内孤立波沿缓坡地形传播特性的实验研究

以南中国海东北部海域底部缓坡地形为背景, 在大型重力式分层流水槽中模拟了下凹型内孤立波沿缓坡地形传播过程中的浅化、破碎、分裂等现象, 利用分层染色标识方法和多点组合探头阵列技术对内孤立波沿缓坡地形演化特征进行了定性分析和定量测量. 实验表明: 浅化效应使内孤立波传播速度减小, 对大振幅内孤立波具有抑制作用, 对小振幅波具有放大效应; 浅化效应可导致内孤立波的剪切失稳及破碎, 还可导致大振幅内孤立波的分裂. 利用Miles稳定性理论可定性描述内孤立波沿缓坡地形传播时发生不稳定状态的位置, 实验结果与理论分析相符合. 关键词： 分层流 缓坡地形 内孤立波 不稳定性     

Investigation of the By-products Formed during the Catalytic Synthesis of 4,4＇-Methylenedimethyldiphenylcarbamate

The structures of the by-products formed during the catalytic synthesis of 4,4＇-methyldiphenylcarbamate （MDC） by the reaction of 4,4＇-methylenedianiline （MDA） with dimethyl carbonate （DMC） were identified and then the mechanisms of their formation were proposed.     

聚四氟乙烯/聚苯硫醚织物自润滑关节轴承的摩擦学性能

制备了两种聚四氟乙烯(PTFE)/聚苯硫醚(PPS)织物衬垫自润滑关节轴承.在径向载荷为35 kN,摆动频率为2.5 Hz工况下,利用关节轴承试验机对其摩擦学性能进行了研究.采用扫描电子显微镜(SEM)、能谱仪(EDS)和激光扫描共聚焦显微镜(LSCM)对其摩擦面的微观形貌和磨损机理进行了研究.结果表明:PTFE/PPS短纤维关节轴承表现出良好的摩擦学性能,其耐磨性和PTFE转移膜面积比PTFE/PPS长丝纤维关节轴承高22.9%和69.7%.PTFE/PPS短纤维关节轴承的磨损机理主要为轻微的黏着磨损和磨粒磨损,PTFE/PPS长丝纤维关节轴承的磨损机理主要为严重的黏着磨损和磨粒磨损.     

基于DSP的天文导航数据处理平台

根据天文导航系统数据量大、实时性要求高、数据接口多的特点,设计了由2片定点型DSP TMS320C6416和2片浮点型DSP TMS320C6711组成并行的MIMD系统用作天文导航数据处理平台,其中TMS320C6416完成通讯、随动控制解算、灰度图像处理和指令处理,TMS320C6711完成星历计算、天文解算和星点亚像素提取。该平台具有体积小、功耗低、重量轻等特点,能有效提高天文导航系统图像处理能力、系统实时性和数据输出率,具有功能强大、运算能力强、实时性好的特点。