Phase Transformations of Graphite and Carbon Black by Laser with Low Power Density

The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both graphite structure and carbon black structure were changed obviously.The results of Raman analyses and Transmission Electron Microscopy(TEM)observations show that graphite transforms into nanodiamond about 5 nm and carbon black is graphitized.It is demonstrated that graphite is the intermediate phase in the transformation from carbon black to diamond,and graphite is easier to transform into diamond by laser irradiation than carbon black.     

Digital body preservation: Technique and applications

High-fidelity anatomical models can be produced with three-dimensional (3D) scanning techniques and as such be digitally preserved, archived, and subsequently rendered through various media. Here, a novel methodology—digital body preservation—is presented for combining and matching scan geometry with radiographic imaging. The technique encompasses joining layers of 3D surface scans in an anatomical correct spatial relationship. To do so, a computed tomography (CT) volume is used as template to join and merge different surface scan geometries by means of nonrigid registration into a single environment. In addition, the use and applicability of the generated 3D models in digital learning modalities is presented. Finally, as computational expense is usually the main bottleneck in extended 3D applications, the influence of mesh simplification in combination with texture mapping on the quality of 3D models was investigated. The physical fidelity of the simplified meshes was evaluated in relation to their resolution and with respect to key anatomical features. Large- and medium-scale features were well preserved despite extensive 3D mesh simplification. Subtle fine-scale features, particular in curved areas demonstrated the major limitation to extensive mesh size reduction. Depending on the local topography, workable mesh sizes ranging from 10% to 3% of the original size could be obtained, making them usable in various learning applications and environments.     

恒流管扫描电路的改进系数与时间误差

引入了恒流管扫描电路在同一时刻的改进系数和时间误差 ,归纳了两个近似公式 ,对几种恒流管扫描电路的性能作了深入一步的研究 ,并且简化了对该电路的计算     

大学英语四、六级考试长篇阅读解题策略

通过分析四、六级考试的试卷结构和测试题型作局部调整后长篇阅读的题型特点,提出了合理安排做题顺序和时间、浏览题干,找准关键词,通过寻读快速定位、跳读段落的前二句或后二句,确定主旨匹配信息的解题策略,旨在为大学英语长篇阅读的教与学和备考训练提供一些有益的参考.     

Er:LN晶体的生长和激光性能研究

在LiNbO5中掺进(0、0．5、1．0、1．5mol％)Er2O5，以Czochrals技术生长LiNbO5、Er(1mol％)：LiNbO3、Er(2mol％)：LiNbO3、Er(3mol％)：LiNbO3晶体。测试Er：LiNbO3晶体的吸收光谱，确定晶体的泵浦波长，Er：LiNbO3晶体的吸收变相对LiNbO3晶体发生红移，红移的程度随Er^3 浓度的增加而增大。测试Er：LiNbO3晶体的荧光光谱，Er：LiNbO3晶体易实现激光震荡的波长4115／2→4115／2(～1．5μm)，是制作波导激光器的最合适的波长。测试Er：LiNbO3晶体的光损伤阅值，其结果高于LiNbO3晶体。Er(3mol％)：LiNbO3晶体的光损伤阀值比LiNbO3晶体高一个数量级。     

国内外环境扫描研究综述

[目的/意义] 对环境扫描现有研究进行评述,指出未来研究内容,在丰富环境扫描领域研究成果的同时,为相关学者更好地把握环境扫描研究问题提供理论基础。[方法/过程] 针对国内外环境扫描的研究现状,对环境扫描领域的国内外核心文献进行系统的梳理和分析,重点从环境扫描的研究概况、概念、环境分类及研究维度方面进行综述。[结果/结论] 国外有关环境扫描的研究较多,研究内容全面,我国的环境扫描研究起步较晚,主要集中在图书情报学领域;3种环境分类方法和3种环境扫描维度被广泛地应用于环境扫描研究中;环境扫描的相关研究有待于得到进一步关注。     

研究生《激光等离子体相互作用原理》专业课程创新教学模式探索

介绍了国内激光等离子体相互作用课程的教学情况、教材使用情况,国防科学技术大学理学院在该课程的教学中所进行的创新性教学模式探索实践和所取得的成效。最后总结了教学改革和人才培养的经验,对其它研究生课程建设具有一定的参考价值。     

基于P-范分布下的三维激光点位误差分布检验

目前,在对三维激光点位误差模型进行推导的过程中,都是假设三维激光点位误差是服从正态分布的,而由于三维激光点位误差源与传统测量仪器中的误差源不同,同时外界环境对激光点位误差的影响也不相同,因此,不能直接断定点位误差服从正态分布,需要对其理论分析及数据统计分析验证。针对三维激光点位误差分布状况,本文对激光点位误差模型进行了推导,并通过大量数据统计分析验证了激光点位误差服从的分布状况。     

新课程视野下的语文基础知识探析

基于新课程视野的语文基础知识是指学习语言文字运用所需要的基础知识。根据现代认知心理学分类理论和中小学语文教学实际,认为语文基础知识由事实性知识、概念性知识和程序性知识构成,三个层面构成的语文基础知识体系就像一座"宝塔",据此来来审视当前的语文基础知识状况,从而提出教学方法的选择必须以知识的分类为基础,选择积累法、感悟法、案例法和训练法。     

Design and Realization of InP/AlGaInAs Multiple Quantum Well Ring Laser

Using beam propagation method(BPM), key optical design parameters of InP/AlGaInAs multiple quantum well(MQW) ring laser were numerically analyzed. The influences of waveguide dimensions, curvature radius and gap size on the coupling efficiency were discussed. An InP/AlGaInAs MQW ring laser with radius of 350 μm was designed and realized. The experimental results show that the designed device, lasing at 1 563.2 nm with side mode suppression ratio higher than 20 dB, exhibited unidirectional bistability between the clockwise and counterclockwise modes.