Evidence of Oxygen Ferromagnetism in ZnO Based Materials

Discoveries of room‐temperature ferromagnetism (RTFM) in semiconductors hold great promise in future spintronics technologies. Unfortunately, this ferromagnetism remains poorly understood and the debate concerning the nature, carrier‐mediated versus defect‐mediated, of this ferromagnetism in semiconducting oxides is still open. Here, by using X‐ray absorption (XAS) and X‐ray magnetic circular dichroism (XMCD), it is demonstrated that the oxygen ions have a ferromagnetic response in different ZnO‐based compounds showing RTFM behavior: ZnO nanoparticles capped with organic molecules and ZnO/ZnS heterostructures. These results demonstrate the intrinsic occurrence of RTFM in these systems, and point out that it is not related to the metallic cation but it relays on the conduction band of the semiconductor.     

Diffusion and doping issues in germanium

This paper gives a review on self- and dopant diffusion in germanium (Ge) under thermal equilibrium and irradiation conditions and specifies the underlying mechanisms of diffusion and the point defects involved. Diffusion in Ge under thermal equilibrium conditions is mainly controlled by vacancies. However, Ge interstitials mediate the diffusion under concurrent annealing and irradiation. This is verified by the diffusion behavior of self-atoms, boron, phosphorus and arsenic under proton irradiation. The diffusion under irradiation is explained with the property of the Ge surface that is proposed to be an insufficient sink for Ge interstitials. As a consequence, a supersaturation of self-interstitials is established during irradiation, whereas the vacancy concentration is kept at thermal equilibrium. This explains that under irradiation the diffusion of self- and dopant atoms via self-interstitials becomes visible that is otherwise negligible under conventional annealing conditions. Our findings demonstrate ways to switch between vacancy and self-interstitial mediated diffusion and shows new strategies in the diffusion doping of Ge for technological applications.     

Computer Modeling and Simulation Evaluation of High Power LED Sources for Secondary Optical Design

Proposed and demonstrated is a novel computer modeling method for high power light emitting diodes（LEDs）. It contains geometrical structure and optical property of high power LED as well as LED dies definition with its spatial and angular distribution. Merits and non-merits of traditional modeling methods when applied to high power LEDs based on secondary optical design are discussed. Two commercial high power LEDs are simulated using the proposed computer modeling method. Correlation coefficient is proposed to compare and analyze the simulation results and manufacturing specifications. The source model is precisely demonstrated by obtaining above 99% in correlation coefficient with different surface incident angle intervals.     

Fe-B合金激光熔凝形成非晶态机理探讨

本文对激光表面熔区的显微组织进行了热力学和动力分析，提出一个简化的熔池中温度分布的物理模型，分析了非晶态形成过程。用ＣＷＣＯ２激光扫描Ｆｅ—Ｂ合金表面，得到１３０μｍ～２００μｍ厚度的非晶层，并对激光低速扫描时熔区再结晶点阵常数变化的有关数据进行了对比，对激光非晶态形成的条件及有关工艺参数进行了分析和讨论。     

NaOH催化微波法制备生物柴油的工艺研究

采用NaOH为催化剂,在微波加热下进行均相酯化反应制备生物柴油,得到最佳工艺条件为：醇油摩尔比14,催化剂含量1．2％,微波输出功率360W,反应时间2min,大豆油的平均转化率达到98．2％,优于水浴加热方式。     

螺旋埋弧焊管焊缝中链状气孔的判定

焊缝气孔是一种体积性缺欠,对焊缝强度的影响不可忽视,因而气孔缺欠的判定是焊缝缺陷评判的重要内容之一。链状气孔是螺旋埋弧焊管焊缝中最常见的缺欠之一,因其气孔数量多且间距不等,因而准确判定具有一定的难度,且评判过程比较繁琐。介绍了链状气孔常用的评定方法,即以点数评级和以气孔直径评级,说明了评定链状气孔应注意的事项。     

全玻真空管太阳能辐射量与其放置角度的关系

本文对全玻真空管在不同的纬度地区,放置在不同的方位、不同的倾角下可能得到的太阳辐射强度进行了探讨,并给出了计算结果。     

非平行分层等离子体鞘套电波传播的复射线方法

基于损耗媒质的复Snell定律提出采用复射线方法研究电磁波在非均匀且非平行分层的等离子体媒质中的传播特性.该方法考虑非均匀平面电磁波的复射线(包括等幅度面的传播射线和等相位面的传播射线), 追踪电磁波复射线在每层媒质中的传播路径以及它们透过媒质分界面时的折射射线, 同时根据复射线的传播方向计算电磁波在每层媒质中的传播衰减, 数值累计整个传播过程中的传播衰减即可获得电磁波穿过等离子体鞘套的总衰减.由钝锥体仿真流场数据简化出非平行分层几何模型并采用复射线方法进行计算分析.计算结果表明:飞行器头部至尾部的传播衰减相差巨大且呈现迅速减小趋势, 非平行分层非均匀等离子体媒质存在某特定入射角, 能使传播衰减达到最小值.     

用于3DTV的图像绘制技术

针对3DTV的应用,对深度图像绘制技术(DIBR)、光线空间表示法和光场绘制法这3类绘制方法分别提出了改进算法,实验结果表明新生成视图质量良好,可以用于3DTV系统的交互式场景渲染。     

基于AVR单片机的汽车尾气检测系统设计

针对当前汽车尾气污染加重和检测标准日益完善的现状,为了弥补传统汽车尾气检测系统在测量精度、稳定性、人机操作等方面存在的不足,提出了一种基于AVR单片机的汽车尾气检测系统设计方案。系统以ATMEGA8L为核心控制器,主要由传感器模块、信号采集调理电路、A/D转换器以及显示模块等组成。实验结果表明,系统具有测量精度高、稳定可靠、人机交互性好等优点。