一种降低直调电/光转换组件功耗的封装方法

为了降低直调电/光转换组件的功耗,以对组件的散热分析结论为基础,提出一种降低直调电/光转换组件功耗的封装方法,即对组件变形敏感的区域采用传统的柯伐合金材料,对半导体制冷器（TEC）底部要求快速散热的区域则采用热导率较高的金刚石铜材料。仿真与测试结果表明：所提出的方法可以降低TEC热端面与组件底面之间的温差、TEC的冷热两端面温差、TEC的电流和TEC自身产生的功耗;在工作温度为70℃时,电/光转换组件的单通道功耗从传统封装方式的2.875 W降低到1.25 W,功耗降低了56.5%。     

液相外延碲镉汞薄膜表面的结晶类缺陷分析

利用扫描电镜、能谱分析、光学轮廓仪以及金相显微镜等测试手段对液相外延碲镉汞薄膜表面缺陷的形貌、成分和断面进行了分析,并研究了不同种类表面缺陷的特征及来源。结果表明,液相外延碲镉汞薄膜表面上存在的结晶类缺陷往往尺寸较大或成片分布,对后续器件产生明显影响。通过分析其成因可以发现,母液均匀性的提升是减少该类缺陷和提高碲镉汞薄膜质量的关键。     

基于铷原子D1线塞曼能级间跃迁的光脉冲减速

基于铷原子D1线塞曼子能级间跃迁,可以观察到光脉冲减速现象。在实验中,当一束弱的右旋圆偏振探测光和一束强的左旋圆偏振耦合光同时耦合87Rb原子D1线F=2→F’=1塞曼子能级间跃迁时,就能在原子介质中获得高色散低吸收的电磁诱导透明现象,观察到光脉冲减速效应。耦合光越弱,光脉冲减速越大;光脉冲宽度越小,光脉冲延迟时间与脉冲宽度的比值越大。     

非接触法自动测量薄膜厚度

根据白光等厚干涉原理,基于单片机改造的迈氏干涉仪用于自动测量透明薄膜厚度,采用非接触性测量法。当迈克尔逊干涉仪静镜形成的虚像与动镜相交所成的夹角很小时,在光屏上看到彩色干涉条纹,插入薄膜后,光程差改变,彩纹消失。步进电机带动微调手轮转动,当彩纹再次出现,即可得出透明薄膜厚度。     

单轴附加应变对体硅及应变硅p-MOSFETs空穴迁移率的影响

Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained- Si（s-Si）p-MOSFETs（metal-oxide-semiconductor field-effect transistors）along 110 and 100 channel directions. In bulk Si,a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field.The combination of 100 direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the 110 direction,opposite to the situation in bulk Si.But the combinational strain experiences a gain loss at high field,which means that uniaxial compressive strain may still be a better choice.The mobility enhancement of SiGe-induced strained p-MOSFETs along the 110 direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.     

勇于面对高清电视时代的声音录制挑战——从《金沙水韵》获金帆奖一等奖谈《再说长江》的声音创作

《金沙水韵》是中央电视台制作的三十三集大型电视纪录片《再说长江》中的一集,该片在2007年度国家广电总局电视节目技术质量金帆奖的评比中获得电视声音制作纪录片类一等奖。本文着重介绍了在录制《金沙水韵》过程中,声音录制遇到的问题及解决办法,同时对《再说长江》的整体录音工作进行简要介绍。     

分数阶微分方程多点分数阶边值问题

研究分数阶微分方程多点分数阶边值问题解的存在性与唯一性,利用不动点定理,得到了边值问题存在唯一解和至少存在1个解的充分条件.     

Analysis of atmospheric effects on the continuous variable quantum key distribution

Atmospheric effects have significant influence on the performance of a free-space optical continuous variable quantum key distribution (CVQKD) system. In this paper, we investigate how the transmittance, excess noise and interruption probability caused by atmospheric effects affect the secret-key rate (SKR) of the CVQKD. Three signal wavelengths, two weather conditions, two detection schemes, and two types of attacks are considered in our investigation. An expression aims at calculating the interruption probability is proposed based on the Kolmogorov spectrum model. The results show that a signal using long working wavelength can propagate much further than that of using short wavelength. Moreover, as the wavelength increases, the influence of interruption probability on the SKR becomes more significant, especially within a certain transmission distance. Therefore, interruption probability must be considered for CVQKD by using long-signal wavelengths. Furthermore, different detection schemes used by the receiver will result in different transmission distances when subjected to individual attacks and collective attacks, respectively.     

一种轧辊磨损度的光电在线检测法

利用反射式光纤位移传感器的工作原理,通过对反射光强信号的检测提出了一种用于轧辊磨损度在线非接触检测的光电检测法.同时利用光电转换及信号处理技术,并采用一种新型等间距三光纤探头来自动补偿光源不稳定、反射体反射率不同、光纤传播损耗和弯曲损耗等因素产生的误差.研究表明,该传感器的分辨率可达到1 μm,精确度和稳定性均可满足实际要求,仪器可在工作现场进行多点在线非接触测量.     

混合型超导限流器与重合闸配合研究北大核心CSCD

基于超导限流器是最理想故障电流限流装置,当超导限流器串入电力系统后对电力系统继电保护和重合闸产生影响.本文在分析新型混合型超导限流器限流原理的基础上,为了解决失超型超导限流器的超导体失超恢复时间与重合闸时间无法配合的问题,引入失超检测系统,延长重合闸时间,当检测到超导线圈失超恢复后重合闸才动作,仿真结果表明该方法可行,并可解决失超型超导限流器与重合闸配合问题.