Raman scattering in the Bi2(Te0.9Se0.1)3 solid solution films

The Bi₂(Te_0.9Se_0.1)₃ solid solutions thin films are produced by ??hot wall?? thermal evaporation in vacuum. From the data of X-ray diffraction studies, atomic-force microscopy of the surface relief, and Raman spectroscopy, it is established that vacuum thermal annealing at a temperature of 200°C for 1 h substantially increases the degree of film crystallization. The laser radiation excitation power optimal for studies of the Raman spectra of the Bi₂(Te_0.9Se_0.1)₃ films is determined.     

三片式LCOS激光投影显示中复合散斑的抑制

研究了三片式硅基液晶(LCOS)激光投影显示中散斑的成因、类型及其光学统计特性,并分析了激光散斑大小的测量方法。在此基础上,选用旋转散射片来减少三片式LCOS激光投影系统中产生的复合散斑,并通过一系列的仿真和实验,使得该激光投影机对比度C降到了人眼可接受的范围4.2%。证明了旋转散射片的方法能有效减少复合散斑,具有光学结构简单、实施性强等优点。     

Cleaning Method of InSb [-1-1-1] B of n- InSb [111] A/B for growth of epitaxial layers by liquid phase epitaxy

The crystal structure of InSb [111] A/B surfaces shows that this structure is polarized. This means that the surfaces of InSb [111] A and InSb [1 1 1] B contain two different crystallized directions and they have different physical and chemical properties. Experiments were carried out on the InSb [111] A/B surfaces, showing that tartaric acid etchant could create a very smooth surface on the InSb [1 1 1] B without any traces of oxides and etch pit but simultaneously create etch pit on InSb [111] A surfaces. After lapping and polishing, some particles remained on the InSb [1 1 1] B surface, they could not be removed easily by standard cleaning process and if these particles remain on the surface of the substrate, the growth layer was not uniform and some island-like regions were observed. The purpose of this work is to remove these particles on the InSb [1 1 1] B surface. Some morphology images of both surfaces, InSb [111] A/B, will be presented.     

Characteristics of the nutrition of the male population of Ufa

The method of daily ration reproduction was used to study the actual nutrition of 25% of male subsampling comprising 674 subjects, during the epidemiological investigation of unorganized male population in a region of Ufa. The results of the study have shown that the caloric value of their nutrition does not exceed the established standards and is diminished with age. Protein consumption meets the physiological requirements, animal proteins prevail in their structure. Carbohydrate consumption is low, mainly at the expense of starch, while the share of sugar is high. Fat consumption exceeds the values recommended, mainly at the expense of saturated fatty acids. Cholesterol consumption is excessive. The established nutrition imbalance of the main food substances has evidenced the atherogenic character of the population nutrition, prevalence of animal food products in its structure, that should be taken into consideration when measures for the prevention of coronary heart disease are elaborated.     

A theoretical model of thulium-doped silica fiber's ASE in the 1900 nm waveband

A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range o...     

一种Ka频段超低交叉极化宽频带波纹喇叭天线

波纹喇叭天线是一种结构紧凑、具有良好辐射性能的馈源天线,特别是轴向槽波纹喇叭天线可以在宽频段内实现极低的交叉极化,对扩展工作频段、实现极化复用有重要的价值。文章对轴向槽波纹喇叭天线的设计方法进行了研究,利用模式匹配法和全波算法软件设计了一种Ka频段超低交叉极化宽频带轴向槽波纹喇叭天线。实测数据表明,该喇叭天线工作频段可覆盖整个Ka频段（26.5~40 GHz）,在频段内回波损耗小于-20 dB、交叉极化小于-45 dB,同时天线具备良好的方向图对称性和相位中心稳定性,在卫星通信领域具有广阔的应用前景。     

一种用于TOF激光雷达的多通道时数转换芯片设计

时间数字转换器(Time-to-Digital Converter,TDC)是一种将连续时间信号转换为数字信号输出的器件,是飞行时间(TOF)激光雷达中的关键部件.在利用计数器粗采样和多相位内插细采样的传统结构上,设计了一种基于相位内插的双级粗细结合型时间数字转换电路,并增加了双回波接收通路来接收多脉冲回波信号,在此基础上设计了一款17通道多路TDC系统芯片.芯片采用CMOS 0.11 μm工艺设计,版图面积为0.6 mm×3 mm.后仿真结果显示,在1.2 V电源下其功耗小于100 mW,单输入精度平均值为51.7 ps,动态范围为3.4 μm,且线性度良好.该TDC芯片适用于飞行时间脉冲激光雷达的信号计时.     

基于灰度-梯度共生矩阵的车轮踏面缺陷聚类分析北大核心CSCD

车轮作为列车走行部的关键部件之一,其踏面产生缺陷后会直接影响到列车的运行安全。为了能够在检测时准确识别车轮踏面缺陷不同类型,提出一种基于灰度-梯度共生矩阵的纹理特征提取方法,对踏面图像的灰度和梯度特征分析之后,根据灰度-梯度共生矩阵提取踏面图像纹理特征矢量,再结合K-均值(K-means)聚类优化算法对踏面缺陷特征量进行聚类,从而将踏面缺陷类型进行分类,并将分类结果用可视化数据显示。实验结果表明,采用上述所提方法,对车轮踏面缺陷不同类型的分类识别精度达96%以上。     

On the Growth of Thin-Film AlGaN/GaN Epitaxial Heterostructures on Hybrid Substrates Containing Layers of Silicon Carbide and Porous Silicon

Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...     

基于6H-SiC衬底外延石墨烯的被动锁模掺镱光纤激光器

报道了6H-SiC衬底外延生长的石墨烯作为可饱和吸收体,环形腔结构的全正色散被动锁模掺镱光纤激光器。在注入抽运功率为250mW时,得到稳定的重复频率为1.05MHz的自锁模脉冲,平均输出功率为6mW;当注入抽运功率增加到480mW时,最大平均输出功率为20mW,相应的最高单脉冲能量为19nJ,激光脉冲宽度约为520ps。