H+和Ar11+激发Si的K壳层X射线发射研究

测量了50–250 keV H⁺和1.0–3.0 MeV Ar¹¹⁺ 轰击Si表面过程中辐射的X射线. 结果表明, 在Ar¹¹⁺入射的情况下, 引起了Si的L壳层上3, 4个电子的多电离.计算了Si的K壳层X射线产生截面, 并将两体碰撞近似(BEA), 平面波恩近似, ECPSSR理论计算与实验值进行了对比. ECPSSR理论与质子产生的截面数据能够很好地符合; 而考虑多电离后, BEA理论与Ar¹¹⁺的实验结果符合较好. 关键词： X射线 高电荷态重离子 多电离     

基于积分直方图的快速粒子滤波跟踪算法

基于直方图的粒子滤波已成功地用于解决计算机视觉中的目标跟踪问题,但是,在观测似然计算上的低效限制了它们的实时应用。针对该问题,提出了一种快速的粒子跟踪方法。其建立在积分直方图技术的基础上,使得每个候选样本的观测似然能够由少量的查找表运算有效地计算出来。该方法使用了大量的粒子以确保鲁棒性,同时确保具备实时跟踪的能力。实验结果表明该方法在计算效率上优于通常的粒子滤波跟踪方法。     

Stabile,Thermoresponsive Colloidal Clusters: An Unusual Morphology of Polymer Dispersions

A new class of colloidal polymeric particles consisting of polystyrene spheres grown in a poly(N‐isopropyl acrylamide) precursor scaffold is synthesized via redox‐initiated heterophase polymerization. The morphology and thermoresponsiveness of these assemblies is proven by electron microscopy investigations and temperature‐dependent measurements of the change of both the speed of sound travelling through the dispersion and the hydrodynamic particle size. Electron microscopy (EM) micrographs (transmission and scanning EM as well cryo‐scanning EM) prove the existence of colloidal clusters when the freeze‐dried copolymer is redispersed in pure water. The clusters have a size of several micrometers, contain about 800 polystyrene particles with diameter below 100 nm, and show a highly reproducible thermoresponsive behavior with a lower critical solution temperature corresponding to that of pure poly(N‐isopropyl acrylamide).

     

Effect of Carbon Black Nature on Vulcanization and Mechanical Properties of Rubber

The influence of the basic properties of carbon black, such as structure, panicle size, and surface activity on the vulcanization and mechanical properties of filled natural rubber compounds was investigated in detail. This is important for a better understanding of the rubber performance and the mechanism of reinforcement. In particular, the effect of carbon black surface activity, which was changed by introducing one kind of hindered amine light stabilizer on rubber reinforcement is emphasized.     

Use of Crustacean Shells for Uptake and Removal of Metal Ions in Solution

Abstract

The use of crustacean shells, in particular crab shells, for the removal of metal ions in solution is described. Research studies found in the literature on the ability of the shells, effect of particle size, pH, competitive studies in mixtures of metals, application to real samples such as acid mine drainage, and use of the shells in a column are presented. The major component of the shells that allows uptake to occur is chitin. Several mechanisms are proposed for uptake. There are conflicting accounts in the literature on such areas as the effect of pH, flow rate, and particle size.     

Experimental Characterization of Sub-Millimetric Fluidic Actuators: Application to Boundary Layer Separation Control

Abstract

Sub-millimetric synthetic, continuous, and pulsed-jet actuators under identical conditions of generation are experimentally compared. Particle image velocimetry and hot-wire anemometry were used for measuring the velocity field. In the second part of the article, the interaction of these three types of actuators with a transverse external flow is characterized using the same experimental techniques. The studied plate is bended downstream from the actuator. Two angles are studied—0° and 28°. The efficiency of the fluidic action on the reattachment of the boundary layer is shown to be strongly dependant on the type of the jet.     

毫米波二阶分形频率选择表面寄生谐振的抑制

二阶分形频率选择表面具有良好的双频特性, 是实现准光学选频网络小型化的理想选择. 但是由于其自相似迭代结构的复杂性, 导致其长期受到寄生谐振的影响, 为了提高二阶分形结构在工程应用中的可靠性, 本文建立了二阶方环分形周期单元的等效电路并分析了寄生谐振产生时的场分布情况, 研究了寄生谐振的形成机理; 进而通过单元间去耦合操作, 并引入基于离散粒子群算法的多参数优化过程, 克服了这一问题. 仿真和实验结果表明: 在保证双频工作特性、对于入射角和极化稳定的前提下, 通过去耦合和粒子群算法实现的频率选择表面实测对寄生谐振的抑制可达13dB, 且避免了新的寄生谐振的产生. 关于寄生谐振抑制的研究, 为增强二阶分形阵列结构的可靠性提供了新的思路. 关键词： 二阶分形 频率选择表面 寄生谐振 离散粒子群算法     

Reviews

Abstract

Biological Effects of Radiations Daniel S. Grosch Blaisdell Publishing Co., New York, 1965, 293 pages. $3.50

Ion Bombardment of Solids G. Carter and J. S. Colligon American Elsevier Publishing Company, Inc., New York, 1968, 446 pages. $40.00     

The fundamental features and characteristics of discharge and plasma ion sources

An analysis of some of the fundamental and special physical processes occurring in discharge and plasma ion sources is presented.

The main purpose of the lecture is to present to the users of ion sources some key elements of information, of which not all may be generally recognised and which hopefully will be of value for a better understanding of the operational problems related to the complex behaviour of discharge and plasma ion sources.