冷阴极离子镀TiN薄膜的空蚀磨损特性研究

采用自制磁致伸缩式空蚀磨损试验机考察了冷阴极离子镀TiN薄膜的空蚀磨损性能，分析了TiN镀层的空蚀磨损过程及机理，探讨了TiN镀层硬度和厚度对其空蚀磨损性能的影响．结果表明：TiN镀层具有优异的抗空蚀磨损性能；其空蚀磨损过程可以划分为孕育、镀层磨损、混合磨损及基体磨损等4个阶段；空蚀磨损从软质点开始，软质点剥落形成凹坑，凹坑边缘发生剥落或断裂；TiN镀层的抗空蚀磨损性能随其硬度和厚度增加而提高．     

Modeling walking behavior of pedestrian groups with floor field cellular automaton approach

Walking in groups is very common in a realistic walking environment. An extended floor field cellular automaton(CA)model is therefore proposed to describe the walking behavior of pedestrian groups. This model represents the motion of pedestrian groups in a realistic way. The simulation results reveal that the walking behavior of groups has an important but negative influence on pedestrian flow dynamics, especially when the density is at a high level. The presence of pedestrian groups retards the emergence of lane formation and increases the instability of operation of pedestrian flow. Moreover,the average velocity and volume of pedestrian flow are significantly reduced due to the group motion. Meanwhile, the parameter-sensitive analysis suggests that pedestrian groups should make a compromise between efficient movement and staying coherent with a certain spatial structure when walking in a dense crowd.     

MRPC宇宙线测试及温度效应

建造了一套MRPC单元的宇宙线测试系统.在数据处理过程中实现对入射宇宙线的方向选择.实验结果表明:MRPC的时间分辨可以达到约84ps,对应的触发系统参考时间分辨可以达到约75ps.对MRPC的温度特性进行了研究,得到了一些初步结论.     

Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.     

宽周期掩膜法HVPE侧向外延自支撑GaN的研究

GaN膜在传统生长过程中主要通过异质外延获得,这往往会产生晶格失配和热失配,给GaN带来严重的位错和应力。目前降低位错最广泛的方法是使用侧向外延技术。在这项工作中,首先在蓝宝石基GaN衬底上沉积了一层SiO₂,并用光刻的方法将其制备成高掩膜宽度(窗口宽度20 μm/掩膜宽度280 μm)的宽周期掩膜,再通过氢化物气相外延(HVPE)侧向外延了厚度为325 μm的GaN厚膜,通过胶带可以将其进行剥离形成自支撑衬底。同时通过二维的Wulff结构图研究了GaN生长过程中晶面的变化趋势。宽周期掩膜法对于生长可剥离的低位错密度自支撑GaN有着重大意义。     

铁Hugoniot曲线的Abinitio计算

以GGA -LAPW冷能计算为基础 ,应用经典统计理论计算了铁的Hugoniot性质 ,包括 :P -V曲线、P -T曲线、热容、Grueneisen参数。计算结果基本上与实验符合。     

铂Hugoniot曲线的Ab initio计算

对于一个原子平均体积为Ｖ,温度为Ｔ的热力学系统,体系的Ｈｅｌｍｂｏｌｔｚ自由能可以写为Ｆ（Ｖ,Ｔ）＝Ｅｃ（Ｖ）＋Ｆｉｏｎ（Ｖ,Ｔ）＋Ｆｅｌ（Ｖ,Ｔ）＋Ｆｍａｎ（Ｖ,Ｔ）其中Ｅｃ为０－Ｋ冷能。对于其中的电子热激发贡献Ｆｅｌ,目前流行的有三种计算方案,即：Ｍｏｒｕｚｚｉ的Ｄｅｂｙｅ－Ｇｒｕｅｎｅｉｓｅｎ方案、Ｍｏｒｉａｒｔｙ的ＭＧＰＴ方案和Ｗａｓｓｅｒｍａｎ的ＣＥＬＬ模型方案。Ｄｅｂｙｅ－Ｇｒｕｅｎｅ     

Ce(C_8H_8)_2和Ce(C_8H_8)_2~-的化学键性质

结合改进的重叠模型Xa-SW法和Ziegler过渡态法,通过将中心原子与配体的作用选成离子聚集、中心原子只有s和p轨道参与成键、中心原子只有d轨道参与成键、中心原子只有f轨道参与成键、中心原子的s、p、d和f轨道同时参与成键5种类型,从能量角度分析了Ce(C_8H_8)_2和Ce(C_8H_8)~-_2的化学键性质。     

STAR 飞行时间探测器和反物质氦核的发现

 相对论重离子碰撞物理是20 世纪70 年代以来形成的一个新的研究领域, 其内容是研究在极端条件下的核物质形态, 即研究由相对论核- 核碰撞所产生的极端高温、高能量密度下核物质的性质, 寻找和探测新的核物质相。这种研究对人们了解物质更深层次的性质, 对于粒子物理、核物理和有关宇宙形成及演化的研究都有非常重要的意义。     

Monitoring the energy variation of an electron linac using a Cerenkov detector

A new method to monitor the energy variation of a multi-energy electron linac by combining a Cerenkov detector and a CsI（Tl） detector is reported. The signals in the Cerenkov detector show an appreciable but different dependence on the energy of the electron linac from the traditional CsI（Tl） detector due to the particular response of the former to charged electrons with high velocity above threshold. The method is more convenient than the HVL （half-value layer） method which is commonly employed to calibrate the energy of an electron linac for real time monitoring. The preliminary validity of the method is verified in a dual-energy electron linac with 6 MeV and 3 MeV gears. Moreover, the method combining the Cerenkov detector and the CsI（Tl） detector is applicable to probe the X-ray spectrum hardened by the inspected material and may serve as a novel tool for material discrimination with effective atomic number in radiation imaging.