Application of XAFS spectroscopy to studying the microstructure and electronic structure of quantum dots

Variations in the microscopic structural parameters of semiconductor nanoclusters (interatomic distances, coordination numbers, and types of neighboring atoms) under variation of the preparation conditions of Ge/Si, GaN/AlN, and InAs/AlAs heterostructures are determined by the EXAFS-and XANES spectroscopy methods. The effect of preparation conditions on interphase diffusion and structure parameters in semiconductor nanoclusters is revealed. The effect of the temperature of synthesis at different stages, the substrate orientation and pretreatment, the composition of the molecular beam (in particular, the presence of Ge⁺ cations) on the local composition of nanostructures is studied. Relations between the size and shape of nanoparticles and their local spatial characteristics (interatomic distances, stoichiometric composition, and phase boundary characteristics) are examined.     

移动通讯用超导接收系统滤波器集成结构设计及试验

详细介绍了移动通讯用超导接收系统滤波器的集成结构设计;提出了集成结构设计的考虑因素及总体集成结构方案。对集成结构中的重要零部件材料选取及结构设计进行了详细介绍、设计,并对设计的部分零件及系统整体进行了热力学、结构力学方面的计算,通过试验测试结果及后续实际使用,证明设计的集成结构完全满足使用要求。     

Cryostat RUPIK to SEM for depth profiling of object structure

The design features of the cryostat RUPIK to an SEM-100U microscope are described. This cryostat was tested on aqueous suspensions of ground coniferous wood and photographic films. A layer-by-layer SEM study at low temperatures made it possible to perform rapid structural analysis on different portions of these objects.     

Method of envelopes for studying a two-film system on a reflecting substrate

For determining the optical constants and the thickness of thin films (including strongly absorbing films) by the spectrophotometric method, we propose to deposit them on intermediate films formed on strongly reflecting substrates. Due to this, an interference pattern depending on the optical constants and the thickness of the film under study will be observed in the reflectance spectrum. The method of envelopes of the extrema in the reflectance spectrum that is based on the iterative approach is developed for studying two-film systems.     

New method for the electronic structure of heterojunctions — Application to the (100) Ge-GaAs interfaces

A method which for the first time can treat two truly semi-infinite semiconductors in contact is introduced and used to study the electronic structure of the two polar (100) Ge-GaAs interfaces. Both the Ge-Ga and the Ge-As interfaces exhibit essentially three interface bands. The nature and origins of these bands are discussed in detail in terms of local densities of states. The results are used to obtain a new interpretation of the experimental data in terms of a stoichiometrically mixed interface.     

100 GW直线变压器驱动源的物理设计与模拟

 基于已有四开关组直线变压器驱动源(LTD)模块设计了对1 Ω负载输出电流100 kA、脉冲上升时间小于60 ns的八开关组LTD模块,该模块采用轮辐式结构,由8个储能电容、气体开关、峰化电容器组并联向中心负载放电。在此基础上,给出了峰值功率100 GW、共10级的LTD装置的物理设计,该装置为同轴感应电压叠加型脉冲发生器。通过电路模拟和PIC模拟,对物理设计进行了检验,结果表明：10级八开关组100 kA LTD模块串联可使10 Ω负载获得超过100 GW的功率输出,脉冲上升时间小于60 ns,所选取的结构和参数能保证电子流的磁绝缘,高压脉冲能有效传输到负载。     

100 GW直线变压器驱动源的物理设计与模拟

基于已有四开关组直线变压器驱动源(LTD)模块设计了对1 Ω负载输出电流100 kA、脉冲上升时间小于60 ns的八开关组LTD模块,该模块采用轮辐式结构,由8个储能电容、气体开关、峰化电容器组并联向中心负载放电。在此基础上,给出了峰值功率100 GW、共10级的LTD装置的物理设计,该装置为同轴感应电压叠加型脉冲发生器。通过电路模拟和PIC模拟,对物理设计进行了检验,结果表明：10级八开关组100 kA LTD模块串联可使10 Ω负载获得超过100 GW的功率输出,脉冲上升时间小于60 ns,所选取的结构和参数能保证电子流的磁绝缘,高压脉冲能有效传输到负载。     

Nuclear orientation as a tool for studying the structure of very unstable nuclei

With the availability of modern isotope separator on-line systems it has become possible to make broad and systematic studies of low-energy low-spin nuclear structure. A vital ingredient in such a program is unique spin-parity assignments to all low-lying levels. A most desirable complement to spin-parity information is detailed spectroscopic information. Obtaining such information far from stability is difficult because of low activity production. Nuclear orientation provides a means for obtaining spin assignments usingsingles measurements. This is less demanding on source intensities than - angular correlation coincidence measurements. Further, nuclear orientation can provide information on magnetic moments and on multipole mixing ratios. A number of structural problems are discussed: the need for unique spin assignments in systematics schemes; the need to distinguish between E2+E0 and M1 transitions; the importance of measuring E2-M1 mixing ratios; and the value of magnetic moment information. Particular emphasis is placed on the desirability of obtaining such information in the neutron-deficient Pt, Au, Hg, Tl, Pb and Bi isotopes, based upon the experimental program at the UNISOR facility.Work supported in part by U.S.Dept. of Energy, Contract No. DE-AS05-80ER10599.     

Fusion of 3D laser scanner and depth images for obstacle recognition in mobile applications

The problem of obstacle detection and recognition or, generally, scene mapping is one of the most investigated problems in computer vision, especially in mobile applications. In this paper a fused optical system using depth information with color images gathered from the Microsoft Kinect sensor and 3D laser range scanner data is proposed for obstacle detection and ground estimation in real-time mobile systems. The algorithm consists of feature extraction in the laser range images, processing of the depth information from the Kinect sensor, fusion of the sensor information, and classification of the data into two separate categories: road and obstacle. Exemplary results are presented and it is shown that fusion of information gathered from different sources increases the effectiveness of the obstacle detection in different scenarios, and it can be used successfully for road surface mapping.     

用一种分数阶算法研究非马尔可夫过程中阻尼与涨落的竞争机制

基于分数阶朗之万方程和随机行走理论, 建立了一种用于研究非马尔可夫系统中随机变量随时间演化的数值模拟算法, 称之为分数阶随机行走模拟法. 进一步运用此算法分别数值研究了无阻尼有涨落、 有阻尼无涨落和阻尼与涨落兼备三种情况下, 受欠扩散分数阶朗之万方程约束的随机变量随时间的演化行为. 结果显示阻尼和涨落存在竞争关系: 高斯型涨落的影响会随着时间的增长被"抹平", 从而凸显阻尼使系统趋于平衡的作用; 而长尾型涨落则由于包含"小概率大贡献"事件, 使得长时间演化之后系统变量仍以一定概率出现突然变化. 关键词： 非马尔可夫 欠扩散 阻尼与涨落 分数阶朗之万方程     

变焦光学系统的景/焦深延拓及其分析

变焦光学系统在连续变焦过程中,由于变焦曲线的计算和加工精度,导致实际像面离焦,成像质量下降。变焦系统的特点是长焦距对应窄视场,短焦距对应宽视场。将波前编码技术应用于变焦系统,在系统的光瞳面设置相位掩模,则扩展了原系统的焦深和景深,使调制传递函数对离焦不敏感,同时提高短焦距宽视场的边缘成像质量。文章对原系统和应用波前编码技术的新系统的成像特性进行了分析和对比,随后讨论了掩模板的相位因子对系统的景深、焦深延拓以及对像质的稳定作用。仿真显示:变焦波前编码光学系统对离焦不敏感,可以很好地扩大系统的焦深和景深、稳定边缘视场的像质,具有很高的实用价值。     

Application of transmission electron microscopy for studying phase relations in the bismuth-rich region of the Ba-Bi-O system

The crystal structure and cation composition of oxides of the Ba-Bi-O system in the composition range 80–100 mol % BiO_1.5 have been investigated by the methods of transmission electron microscopy. Ordered phases of the compositions Ba: Bi = 2: 9, 1: 6, and 1: 15 with a rhombohedral structure have been revealed. In the range of the compositions Ba: Bi from 1: 36 to 1: 46, phases with triclinic, monoclinic, and cubic structures have been found. The monoclinic and cubic phases have structures similar to the structures of the α and γ modifications of bismuth oxide Bi₂O₃, respectively. Phase formation was found to be dependent on the following parameters: annealing temperature, partial oxygen pressure, oxygen content in the initial pairs of reacting components (BaO₂-Bi₂O₃, Ba(NO₃)₂-Bi₂O₃, BaCO₃-Bi₂O₃), and crucible material (alundum or platinum).     

移动机器人自主返航控制系统设计与实验

针对遥控移动机器人在通信信号中断后,无法对其进行控制的问题,设计了移动机器人自主返航控制系统,实现信号中断后移动机器人按原路径自主返航直至恢复控制信号或返回初始位置。提出了基于控制意图融合里程计和光纤陀螺仪的定位算法,对移动机器人运动学模型的结构参数进行了校正,大幅度提高了移动机器人定位精度;基于嵌入式Linux平台设计了返航控制软件系统,在信号正常的情况下,启动遥控模式,遥控机器人移动并记录路径坐标点,信号中断则开启返航模式,采用线性控制率和PID控制率实现对移动机器人路径跟踪控制。基于实际应用环境开展自主返航实验验证,实验结果表明该控制系统能够在通信信号中断后以较高的精度控制移动机器人实现自主返航。该系统能够解决移动机器人在应用中的实际问题,且代码可移植性高、通用性强。     

1m口径主反射镜支撑系统的优化设计

应用有限元法并借助有限元分析软件建立了主镜的三维实体有限元模型,对1m主镜的支撑系统进行了优化设计。分析比较了两种常用主镜侧支撑结构,优化确定了轴向支撑半径、侧支撑方式和侧支撑点位置。分析计算显示主镜处于不同俯仰角位置时的最大面形精度RMS值为5.3nm,满足设计指标要求,该有限元优化设计方法和过程不受主镜直径及厚度的影响,适用于平面、球面、非球面甚至异形面主镜的设计。结果表明了所设计的支撑系统方案的合理性与可行性。     

Present status and future aspects of nuclear structure close to 100Sn

The present status of experimental approach to ¹⁰⁰Sn in the spectroscopy of excited states is landmarked by the T_z=3/2 nuclei between ⁹⁵Pd and ¹⁰¹In and the T_z=1 nuclei ⁹⁴Pd and ⁹⁸Cd. The detection limits with Pre-EUROBALL γ-arrays and ancillary detectors are below the 10^?5 level of the total fusion- evaporation residue cross section. A large scale shell model analysis of the existing data reveals the shell structure at ¹⁰⁰Sn, which shows a remarkable similarity to ⁵⁶Ni. Evidence for an increasing proton-neutron interaction in approaching the N=Z line is deduced from high spin isomers and spherical yrast lines. The effective E2 operator for protons and neutrons and implications for a low lying particle-hole (ph) E2 excitation in ¹⁰⁰Sn are discussed.     

Development of a mobile Raman-Mie lidar system for all time water vapor and aerosol detection

A turn-key Raman-Mie lidar system for water vapor and aerosol detection is described, which is placed in a boxcar and can be operated both at night and daytime. The operation of the lidar is very simple, especially, it does not need readjustment after road transit. The effective detection range of the system can reach tropopause for aerosol, and the improved system can obtain water vapor profile in boundary layers during daytime. Some experimental results and validations are presented.     

Artificial periodic inhomogeneities and a model for the lower part of theD region

The measured height profiles of the relaxation time and amplitudes of artificial periodic inhomogeneities (API) in the ionospheric D region are compared with the model. It is shown that the height dependences of the relaxation time of APIs and the amplitude of the scattered signal can be explained taking into account the hieght profile of the atmosphere density. Most probably, the upper boundary of APIs in the D region is due to the increase in the atomic oxygen density and can serve as an altitude indicator. Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 5, pp. 431–437, May 1999.     

Application of Huang-Yang pseudopotential to a few-body system

Huang and Yang replace a hard core of radius c by their pseudopotential (HYPP), which can be used in perturbation theory. I show that HYPP and boundary value perturbation theory give the same energy shift, to first order in c. I model a two-body potential as an oscillator potential (angular frequency ω) and a hard core. For an A-body system, the ratio of the first order energy correction to the unperturbed energy is 0.448 A^3/4 c a, where a = (M ω/2h)^1/2.