A Study on S.R.Topography of the Structural Defects in High-J_c Superconducting YBaCuO Crystal Prepared by the MTG Technique

It is well known that for technological application,a great effort has been done to enchance J_c value ofsuperconducting YBaCuO sintered bulk.Except oxygen content,the main problem for increasing critical cur-rent density J_c is to eliminate the weak link and to control crystallographic anisotropy.It is necessary tomake YBaCuO superconducting bulk have a strong texture with C-axis orientation.Since Jin et al.has suc-     

Wafer bonding technique used for the integration of cubic GaN/GaAs (001) with Si substrate

We successfully used the metal mediated-wafer bonding technique in transferring the as-grown cubic GaN LED structure of Si substrate. The absorbing GaAs substrate was removed by using the chemical solutions of NH4OH : H2O2=1 : 10. SEM and PL resuls show that wafer bonding technique could transfer the cubic GaN epilayers uniformly to Si without affecting the physical and optical properties of epilayers. XRD result shows that there appeared new peaks related to AgGa2 and Ni4N diffraction, indicating that the metals used as adhesive and protective layers interacted with the p-GaN layer during the long annealing process. It is just the reaction that ensures the reliability of the integration of GaN with metal and minor contact resistance on the interface.     

Mo／SiO2软X射线多层膜反射镜的界面分析

用Ｘ射线衍射的动力学理论对磁控溅射法制备的Ｍｏ／ＳｉＯ２多层膜低角Ｘ射线衍射谱进行拟合，定量分析了膜层的周期结构和界面粗糙度。同时，用Ａｕｇｅｒ电子能谱证实了多层膜成分的周期性以及比较明晰的层界面，随样品厚度的增加，界面粗糙度增加。     

H∞回路成形中的μ综合法

H∞控制理论中的回路成形设计和μ综合都已经是定型的设计方法. 最近有文献提出一种将这两种设计方法结合起来处理弱阻尼谐振模态参数摄动的新方法. 但是实际设计表明, 二者的结合并没有达到预期的效果. 本文分析指出, 回路成形本质上是一种鲁棒稳定性设计, 其H∞范数指标的逆就是系统的稳定裕度. 而μ综合只是一种鲁棒性能的设计工具. μ综合与回路成形结合只是反映在稳定裕度上, 而并不影响设计所允许的摄动大小. 所以在回路成形设计中没有必要再加进μ综合法. 文中附有算例.     

浅谈网页设计

网络世界五彩缤纷,涌现出大量优秀精美的网页。本文介绍了网页设计的重要性,并探讨了网页设计需要注意的几个问题。     

端活性聚氧化丙烯醚改性环氧树脂的研究

本文系统地研究了端羧基聚氧化丙烯醚、端异氰酸酯基聚氧化丙烯醚增韧环氧树脂的规律。分子量适宜的端活性聚氧化丙烯醚同端羧基液体丁腈橡胶一样,能增韧环氧树脂。聚醚改性环氧体系具有两相结构,断裂韧性提高近十倍,机械、电性能变化较小。由于聚醚价格要比端羧基液体丁腈橡胶便宜得多,这一体系有很大的实用价值。     

合成橡胶工业概况及发展建议

综述了国内外合成橡胶工业概况和发展趋势,并结合国情对我国“八五”期间合成橡胶工业的发展提出了建议。