Energy Levels of Hydrogenic Impurities in InAs Quantum Ring

The distribution of energy levels of the ground state and the low-lying excited states of hydrogenic impurities in InAs quantum ring was investigated by applying the effective mass approximation and the perturbation method. In 2D polar coordinates, the exact solution to the Schrodinger equation was used to calculate the perturbation integral in a parabolic confinement potential. The numerical results show that the energy levels of electron are sensitively dependent on the radius of the quantum ring and a minimum exists on account of the parabolic confinement potential. With decreasing the radius, the energy spacing between energy levels increases. The degenerate energy levels of the first excited state for hydrogenic impurities are not relieved, and when the degenerate energy levels are split and the energy spacing will increase with the increase in the radius. The energy spacing between energy levels of electron is also sensitively dependent on the angular frequency and will increase with the increases in it. The degenerate energy levels of the first excited state are not relieved. The degenerate energy levels of the second excited state are relieved partially. The change in angular frequency will have a profound effect upon the calculation of the energy levels of the ground state and the low-lying excited states of hydrogenic impurities in InAs quantum ring. The conclusions of this paper will provide important guidance to investigating the optical transitions and spectral structures in quantum ring.

OPTICAL-PHONON MODES AND FROHLICH POTENTIAL IN ONE-DIMENSIONAL QUANTUM-WELL WIRES

By extending our microscopic model on optical-phonon modes in quantum wells to one-dimensional (1D) quantum-well wires (QWW), the optical displacements and associated electrostatic potentials of optical-phonon modes in 1D QWW are calculated. The modes can be clearly divided into confined LO bulklike, TO bulklike modes, and extended interfacelike modes provided the bulk phonon dispersion is ignored. The character of each type of mode is illustrated with special attention to the interfacelike modes, which are hybrids of longitudinal- and transverse-optical waves from the corresponding bulk materials. Based on the numerical results, approximate analytical formulas for bulklike modes are presented. As in 2D wells, both the optical displacements and Frohlich potentials for the bulklike modes vanish at the interfaces. The finite dispersion of bulk phonons has a more pronounced effect on the 1D phonon modes because interfacelike modes show mixed characteristics of 2D interface and bulklike modes.

Incremental pairwise discriminant analysis based visual tracking

The distinguishment between the object appearance and the background is the useful cues available for visual tracking in which the discriminant analysis is widely applied However due to the diversity of the background observation there are not adequate negative samples from the background which usually lead the discriminant method to tracking failure Thus a natural solution is to construct an object-background pair constrained by the spatial structure which could not only reduce the neg-sample number but also make full use of the background information surrounding the object However this Idea is threatened by the variant of both the object appearance and the spatial-constrained background observation especially when the background shifts as the moving of the object Thus an Incremental pairwise discriminant subspace is constructed in this paper to delineate the variant of the distinguishment In order to maintain the correct the ability of correctly describing the subspace we enforce two novel constraints for the optimal adaptation (1) pairwise data discriminant constraint and (2) subspace smoothness The experimental results demonstrate that the proposed approach can alleviate adaptation drift and achieve better visual tracking results for a large variety of nonstationary scenes (C) 2010 Elsevier B V All rights reserved

对达曼光栅进行二维扩展的矩形孔径光栅设计

介绍一种二元光学元件的设计方法.为了克服达曼光栅在二维设计上的局限性,采取均匀采样的矩形孔径编码方式进行优化设计.结果表明:与达曼光栅相比,不仅可将总衍射效率提高10%以上,还可得到更多样的二维设计图样,只是输出点阵均匀度略低于达曼光栅.因此,在均匀度要求不太高的高强光束变换中,这种二值型位相光栅的设计方法对于设计二维衍射图样十分简便有效,且其计算结果易于加工制作,具有很高的应用价值.

航天器贮箱气液自由界面追踪数值模拟

主要讨论了航天器贮箱在轨道航行时的微重力状态下其液体推进剂在贮箱内的形态分布及控制．文中采用VOF方法，加入了表面张力的效应，追踪气液两相流的自由界面，对液面在微重力条件下的位形变化进行了数值模拟．通过比较不同重力加速度及接触角下的两相流的相图，分析了影响贮箱中液体推进剂位形变化的主要因素及对其有效的控制方法．

星间激光通讯中的精跟踪研究

星间激光通讯中，精跟踪起着十分重要的作用，而精密偏转镜（FSM）是精跟踪系统中最为关键的部件．基于光学矢量反射定律，推导得到了FSM的精确光学特性，这一特性为精跟踪控制系统提供了精确的理论依据．设计了基于FSM精确光学特性的精跟踪控制系统，对系统整定所用的单纯形法进行了两点重要改进，并对所设计的精跟踪系统进行了数字模拟，由此实现了对FSM的精确控制，提高了精跟踪系统的精确性；将光学衍射超分辨原理应用到星间激光通讯中．利用三区位相光瞳滤波器的超分辨性能，改变光学系统的点扩散函数，从而改变接收端焦平面上的光强

星间激光通信光束微弧度跟瞄性能检测装置的设计原理

基于矢量折射定理，研究了透射光束通过双棱镜实现微弧度量级偏转的设计原理，解决了星间激光通信精跟瞄检测的难题。推导了正交双棱镜实现光束偏转的精确公式，提出以水平张角和垂直张角表达光束视场，并说明了单棱镜实现光束偏转的一般情况。根据设计指标和计算结果确定了棱镜的主要参量，进而对光束的偏转结果进行了数值模拟。最后的实验结果与模拟结果基本一致。结果表明：取棱镜棱角α为4°时，棱镜每旋转1’，透射光束变化约1μrad；分别控制双棱镜在其最小偏向角一侧小角度偏转，可以实现光束在水平方向和垂直方向500μ范围内的精确扫

空间激光跟瞄中指向驱动电机运动特性研究

设计了一种深空非合作目标的激光扫描、捕获、跟踪地面实验装置,通过模拟深空同轨道运动的两颗卫星跟瞄过程,在理论上计算了跟瞄装置中光束指向驱动电机的最小加速度和其在跟踪过程中的运动特性。理论分析与仿真结果表明,当卫星偏离光斑中心一定距离时,指向驱动电机先加速后减速,补偿这个偏心,重新捕获跟踪卫星;重新捕获到跟踪所需时间受电机加速度和望远镜探测精度以及探测器响应处理时间影响,其中探测器精度对重新捕获到跟踪所需时间影响较大,探测器响应处理时间要减小到最小;为了使从捕获到跟踪过程中卫星始终在扫描光斑范围内,经纬仪驱动电机的最小角加速度为25.5°/s2。

卫星跟踪技术在候鸟迁徙研究中的应用

：自20世纪80年代末期应用基于Argos系统的卫星跟踪技术开展候鸟迁徙研究以来，鸟类学家取得了 许多利用传统鸟类迁徙研究方法所无法取得的成果。但在中国，卫星跟踪技术在鸟类迁徙中的应用尚属空白。作 者利用参与中国首次应用卫星跟踪技术跟踪候鸟迁徙研究之机，对该技术用于候鸟迁徙研究的技术平台、主要内 容和未来研究进行了综述和展望。利用卫星跟踪技术开展的主要研究内容有：揭示迁徙路线和重要停歇地点；寻 找新繁殖地和越冬地；利用卫星数据对栖息地及其利用进行评价；探讨鸟类的迁徙策略。期望该技术能够成为中 国濒危鸟类保护的有效方法，并尽快得到应用。

Comparison of free spectral range and quality factor for two-dimensional square and circular microcavities

Free spectral range of whispering-gallery (WG)-like modes in a two-dimensional (2D) square microcavity is found to be twice that in a 2D circular microcavity. The quality factor of the WG-like mode with the low mode number in a 2D square microcavity, calculated by the finite-difference time-domain (FDTD) technique and the Pade approximation method, is found to exceed that of the WG mode in 2D circular microcavity with the same cavity dimension and close mode wavelength.

面向多目标追踪的无线传感器网络协同任务分配研究

在基于动态联盟机制的无线传感器网络协同任务分配研究中,为了解决多目标追踪带来的联盟间的资源竞争问题,本文采用分布式约束满足算法解决多动态联盟间的协同问题.根据无线传感器网络多目标追踪的应用需求,建立了基于动态联盟机制的协同任务分配的分布式约束满足模型,并采用分布式随机算法求解满足约束条件的动态联盟集合,实现多动态联盟间的协同.仿真结果表明,分布式约束满足算法有效地解决了多目标追踪中多个动态联盟间的资源竞争问题,能够有效降低系统的能量消耗。

移动机器人几何-拓扑混合地图的构建及自定位研究

基于墙角、房门和通路等高级环境特征的辨识与提取,依据几何和拓扑环境模型完成混合地图的构建,并根据混合地图的特点,提出在局部几何环境采用扩展卡尔曼滤波算法实现移动机器人的位姿跟踪,而在拓扑地图的节点位置则根据绑定的高级环境特征进行位姿再校正的混合定位方法.将该方法应用于实际移动机器人平台,所得结果证明了方法的有效性和实用性.

类Lyapunov理论在类人形机器人任务空间内跟踪的应用

考虑了类人形机器人的各种不确定因素,提出了其手臂控制的新方法.基于类Lyapunov方法,设计出具有鲁棒性功能的任务空间控制器.该方法得到的控制器不但在有限确定时间内达到稳定跟踪,而且不需要雅可比矩阵求逆,对一定类型的外部干扰具有鲁棒性功能.最后通过数值仿真显示了所得结果的有效性及其应用方法.

大射电望远镜精调Stewart平台工作空间分析

针对大射电望远镜精调Stewart平台的五自由度运动特性,采用快速极坐标搜索法确定了五自由度大射电望远镜精调Stewart平台的工作空间.通过实例分析验证了所提出的工作空间分析方法的有效性.为大射电望远镜馈源轨迹跟踪实现和精调Stewart平台的设计奠定了坚实的基础.

基于形状特征的二维旋转尺度不变相似度量

目标物体的旋转及尺度变化在目标识别过程中是普遍存在的 .这里给出了一种新的特征提取方法及其相似度标准 ,通过提取物体形状中具有二维旋转尺度不变性的信息 ,来实现对二维变化目标的识别