磷酸盐激光玻璃非激活吸收系数测量研究

介绍了高功率激光放大器系统中磷酸盐激光玻璃的静态透过率测量。在正常运行条件下,4片长按布儒斯特角放置的国产N31钕玻璃片对1.054um的激光波长平均静态透过率为94.5%,介质的损耗系数为0.294%cm-1,平均非激活吸收系数为0.146%cm-1。在此基础上对片状放大器的增益系数的测量结果进行了修正,获得了5.25%cm-1的小信号增益系数。     

采用磁集成技术的低压大电流DC/DC变换器的仿真

运用回转器一电容模型可以很好的理解磁性器件，特别是复杂的集成磁件。文章运用磁导电容类比建模法建立了磁件的回转器一电容模型。在回转器一电容模型中，磁路由容性电路来模拟，绕组由双端口的回转器来代替。进行了采用磁集成技术的低压大电流DC／DC变换器的仿真。仿真电路拓扑是原边不对称半桥、副边倍流整流电路。磁集成变压器的结构是Wei Chen提出的原边绕于中柱的只在侧柱开气隙的倍流整流磁集成结构。建立了用SPICE语言描述的回转器仿真模型。仿真软件是MULTISIM2001。     

An observation of electron phase transition in SmB6 at low temperatures

In order to reveal the nature of the ground state of archetypal intermediate-valence compound SmB₆, a comprehensive study of its transport and magnetic properties was carried out on high-quality single crystals at temperatures of 1.8-300 K in magnetic fields up to 7 T. A drastic enhancement of negative magnetoresistance was observed below 14 K, with the maximum absolute value of Δρ/ρB²∼2.2×10⁻³ T⁻² at T≈5.2 K. This effect seems to be attributable to anomalous magnetic scattering of many-body (exciton-polaronic) complexes induced by fast valence fluctuations on Sm sites. The observed anomalies of magnetotransport, thermoelectric and magnetic characteristics are discussed in terms of electron phase transition to the coherent state of interacting many-body complexes occurring at T^*∼5 K.     

环境因子的定义及研究现状

从普遍接受的三个基本假设出发，讨论环境因子的定义和失效机理不变的约束条件，重点综述环境因子的研究现状和常用方法，并探讨引入反应论模型解决环境因子预测问题的可能途径。     

Control over the parameters of InAs-GaAs quantum dot arrays in the Stranski-Krastanow growth mode

The effect of the growth temperature on the density, lateral size, and height of InAs-GaAs quantum dots (QD) has been studied by transmission electron microscopy. With the growth temperature increasing from 450 to 520°C, the density and height of QDs decrease, whereas their lateral size increases; i.e., the QDs are flattened. The blue shift of the photoluminescence line indicates decreasing QD volume. The observed behavior is in agreement with the thermodynamic model of QD formation. The effect of lowering the substrate temperature immediately after the formation of QDs on the QD parameters has been studied. On lowering the temperature, the lateral size of QDs decreases and their density increases; i.e., the parameters of QD arrays tend to acquire the equilibrium parameters corresponding at the temperature to which the cooling is done. The QD height rapidly increases with cooling and may exceed the equilibrium value for a finite time of cooling, which enables fabrication of QD arrays with a prescribed ratio between height and lateral size by choosing the time of cooling.     

CSCL Script理论研究与系统设计

CSCL Script的研究成为当前CSCL领域中新的研究热点。为了更好的支持协同学习过程的设计,文章在综述和研究CSCL Script相关理论的基础上，重点设计了模型基本框架、主要功能和各模块之间关系,最后采用“面向行为流”方法基于树型结构设计实现该系统。     

Solving phase-noise Fokker-Planck equations using the motion-group Fourier transform

A quantity of importance in coherent optical communications is the probability density of a filtered signal in the presence of phase noise (PN). The Fokker-Planck(FP) approach has been recognized as a rigorous way to describe these statistical properties. However, computational difficulties in solving these FP equation shave prevented their widespread application. In this paper, we present a new and simple computational solution method based on techniques from noncommutative harmonic analysis on motion groups. This proposed method can easily solve all the PN FP equations with any kind of intermediate frequency filter. We also present a new derivation of PN FP equations from the viewpoint of stochastic processes.     

格基约减算法及其应用

格基约减在许多应用上是一个非常有力的数学工具。本文详细介绍了有关格基约减算 法的概念、定义和著名的LLL算法,并在此基础上通过一个对低阶RSA算法的攻击过程对约减算法 的应用进行了简要介绍。     

激光二极管侧面抽运Nd:YAG锁模激光器的研究

利用谐振腔的稳定条件对激光二极管侧面抽运的Nd：YAG锁模直腔的稳区特性和谐振腔内的光斑分布进行了分析。根据对腔参量的分析，选取合适的腔参量设计了一个简单的侧面抽运直腔，该谐振腔腔形简单，没有像散，振荡光模式好，有利于激光器的锁模运转。实验中采用国内自行研制的半导体可饱和吸收镜，实现了激光二极管侧面抽运半导体可饱和吸收镜锁模Nd：YAG激光器的连续锁模运转，平均输出功率为2W，锁模脉冲宽度为10ps，重复频率为100MHz。结合实验结果进一步讨论了半导体可饱和吸收镜的一些参量如饱和恢复时间、调制深度等对实现稳定连续锁模的影响。     

Effect of Gd-Mn exchange on phase transitions in GdMn<Subscript>2</Subscript>O<Subscript>5</Subscript> induced by a strong magnetic field

Complex studies of the magnetic, magnetoelectric, and magnetoelastic properties of GdMn₂O₅ single crystals in strong pulsed magnetic fields are carried out in order to obtain additional indirect information on the character of the rare-earth and manganese spin ordering. It is shown that magnetic ordering of Gd³⁺ spins affects the manganese sublattice spin orientation and initiates new magnetic phase transitions. The observed magnetoelectric properties of the GdMn₂O₅ system are interpreted in terms of the theory of phase transitions.