镍基单晶高温合金短时时效过程中取向变化的原位研究

利用TEM和XRD原位研究了一种镍基单晶高温合金在时效过程中的取向变化.研究发现固溶-时效热处理后的初始样品内部不同γ′相之间存在~4°的小角度晶界.对材料在950℃下进行10 min短时时效处理,原位TEM和XRD结果表明γ′相的取向偏离初始取向~5°,且该取向变化在降温之后也不会完全恢复;该短时升、降温过程使γ′相的取向集中度增加.     

Impact of Ti Sputter Target Denitridation on the Crystallographic Orientation of Single Ti Layers and Ti/TiN/AlCu Layer Stacks on Different Oxides

The impact of Ti sputter target denitridation on the crystallographic orientation of single Ti layers and Ti/TiN/Al layer stacks was studied for three different underlayers: tetraethyl orthosilicate (TEOS)-based chemical vapor deposition (CVD) oxide, silane-based high-density plasma (HDP) CVD oxide, and thermal oxide. A clear correlation was found between Ti crystal orientation and Ti sputter target conditioning as well as oxide underlayer. The Ti crystal orientation determines the orientation of the Al in the Ti/TiN/Al layer stacks. The most perfect Al(111) orientation in Ti/TiN/Al layer stacks was found for a Ti layer sputtered on TEOS oxide after a Ti target denitridation of more than 5 s.     

CdTe and HgTe surface growth kinetics for molecular and metalorganic molecular beam epitaxy

The surface growth kinetics of CdTe and HgTe have been investigated during molecular and metalorganic molecular beam epitaxy. The surface growth kinetics was studied through in-situ measurements of the growth rate as a function of flux ratio and substrate temperature on the (001), (111)B, and (211)B CdTe surface orientations. For the (001) and (111)B CdTe growth kinetics, the existence of low binding energy surface precursor sites was proposed for both molecular and atomic growth species before lattice incorporation. Intensity oscillations were observed during HgTe growth on misoriented (111)B surfaces and during CdTe growth on the (211)B orientation. The (211)B surface reconstructions displayed both vicinal and singular surface characteristics, depending on the growth flux ratio.     

Moving cast shadow detection using online sub-scene shadow modeling and object inner-edges analysis

In this paper, we propose an adaptive and accurate moving cast shadow detection method employing online sub-scene shadow modeling and object inner-edges analysis for applications of static-camera video surveillance. To describe shadow appearance more accurately, the proposed method builds adaptive online shadow models for sub-scenes with different conditions of irradiance and reflectance. The online shadow models are learned by utilizing Gaussian functions to fit the significant peaks of accumulating histograms, which are calculated from Hue, Saturation and Intensity (HSI) difference of moving objects between background and foreground. Additionally, object inner-edges analysis is adopted to reject camouflages, which are misclassified foreground regions that are highly similar to shadows. Finally, the main shadow regions are expanded to recycle the misclassified shadow pixels based on local color constancy. The proposed algorithm can adaptively handle the shadow appearance changes and camouflages without prior information about illuminations and scenarios. Experimental results demonstrate that the proposed method outperforms state-of-the-art methods.     

基于粒子群优化的传感器预分配方法

针对实时传感器管理算法的局限,在深入分析传感器管理问题本质特征的基础上,提出一种传感器静态预分配方案。然后,以低轨星座目标连续跟踪为应用背景,提出一种基于修正粒子群优化的传感器预分配方法。仿真实验表明,所提方法虽然需要较长时间的静态分配过程,但是其实时运算效率明显高于实时传感器管理算法,因而给上层系统设计留下更多富余时间。      

联合人体模型与块生长的人群目标分割

人群目标的准确分割,是进行多相机联合目标跟踪与识别的关键。该文首先构造包含位置、尺寸、姿态信息的人体粗略姿态模型,并利用贝叶斯模型获得对应的目标模型。然后将前景区域利用分水岭算法划分为颜色分布一致的子块,通过位置和颜色约束解决遮挡目标的种子块选取问题。最后通过块生长获得每个目标区域。对于颜色相似子块,通过比较其产生的边缘能量确定其所属目标。实验结果表明,本文能够实现对人群目标较精确分割,且对背景噪声具有一定的抗干扰能力。     

北斗2机载双天线定向接收机研究与设计

针对使用北斗二代卫星导航系统实现飞机航向确定的接收机尚无实际应用,提出了一种机载双天线定向接收机;首先介绍了双天线定向原理,从射频前端处理、基带数字信号处理、定位测向解算模块等方面分析了适用于北斗二代信号体制的接收机设计方案,研究了基于LAMBDA算法的载波相位双差定向算法;最后进行实验验证,结果表明接收机平均定向精度可达0.121°/m,可以满足飞机定向应用要求.     

基于Webserver面向对象层次分解的故障诊断

基于Webserver面向对象层次分解的故障诊断,将复杂设备分解成设备、故障及维修三种对象类表示.先采集设备状态,获取设备征兆信息,并将系统故障分解成各子故障.由设备各级故障对象实例,获取设备各状态信息,验证设备故障,找出设备故障产生原因,排除方法,得出设备维修决策和设备状态性能意见.     

CuO纳米线中的取向畴

通过简单的热氧化法,可以得到不同取向畴的CuO纳米线结构.利用群论的知识,从理论上推导出CuO纳米线中存在11种畴壁结构,其中5种已经被实验证实.同时,在800℃下得到直径较大的CuO纳米线,利用透射电子显微学相关技术分析发现,这种纳米线中存在一种新的畴壁结构,而且也属于理论上得到的11种畴壁之一.本文利用群论分析,解释了CuO纳米线中取向畴结构的生成机制,对调控CuO纳米材料的生长具有指导作用.