Preparation of hybrid film with superhydrophobic surfaces based on irregularly structure by emulsion polymerization

A superhydrophobic surface originated from quincunx-shape composite particles was obtained by utilizing the encapsulation and graft of silica particles to control the surface chemistry and morphology of the hybrid film. The composite particles make the surface of film form a composite interface with irregular binary structure to trap air between the substrate surface and the liquid droplets which plays an essential role in obtaining high water contact angle and low water contact angle hysteresis. The water contact angle on the hybrid film is determined to be 154 ± 2° and the contact angle hysteresis is less than 5°. This is expected to be a simple and practical method for preparing self-cleaning hydrophobic surfaces on large area.     

Investigation of proton-proton short-range correlations via the 12C(e,e'pp) reaction

We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2=2 (GeV/c)2, xB=1.2, and in an (e, e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For (9.5+/-2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing-momentum vector, an experimental signature of correlations.     

Laser-diode excited intense upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses

We have investigated infrared-to-visible upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses. The UV cutoff wavelength is shortened while its lifetime is increased almost linearly, with PbF2 substituting for PbO in the bismuth-lead germanate glasses. Three emissions centred at around 529, 545 and 657 nm are clearly observed, which are identified as originating from the ^2H11/2→^4 I15/2,^4S3/2→^4 I15/2 and ^4 F9/2 →^4 I15/2 transitions, respectively. It is noted that all the upconversion emission intensities increase with PbF2 concentration increasing. The ratio between the intensities of red and green emissions increases with the increasing of PbF2 content. Energy transfer processes and nonradiative phonon-assisted decays account for the populations of the ^2 H11/2,^4 S3/2 and ^4F 9/2 levels. The quadratic dependence of fluorescence on excitation laser power confirms a two-photon process to contribute to the upconversion emissions.     

LD抽运被动调Q固体激光器的脉冲稳定性

报道了二极管激光抽运Cr,Nd∶YAG被动调Q Nd∶YVO₄ 1064nm激光输出.为了提高被动调Q激光的输出稳定性，谐振腔采用长腔，增益介质位于谐振腔中间位置.实验中获得了稳定的被动调Q激光输出.在最高入射抽运功率为17.5W时，脉冲重复频率达到71.3kHz，脉冲宽度为0.4μs.调Q脉冲幅度不稳定性低于±10%，脉冲时间波动性低于±3.5%.     

用于原子能级结构研究的激光共振电离光谱系统

激光共振电离光谱技术是一种利用一路或多路激光将待测原子选择性共振激发与电离,通过测量离子信号来研究原子能级结构的光谱技术。研建了一套激光共振电离光谱装置,用于原子高激发态能级结构参数的测量。分别从该装置的总体结构、关键技术和应用实例等方面进行了详细介绍。该套装置主要包括高调谐精度的染料激光器系统、高效的激光离子源系统和高分辨率的飞行时间质量分析器。染料激光器系统包括3台多纵模可调谐染料激光器和1台单纵模可调谐染料激光器,均为脉冲工作方式,重复频率为10 kHz,泵浦源均为532 nm的Nd∶YAG固体激光器。激光离子源系统包括原子化源、激光与原子相互作用区和离子光学透镜组三部分组成,样品在原子化源中被电加热实现原子化,喷射出的原子被激光选择性激发、电离,产生的离子被离子传输透镜整形成能量分散小、束窄的离子束。飞行时间质量分析器采用了反射式结构设计、脉冲垂直推斥技术和偏转板调节技术。利用此装置,实验测定了U原子的自电离态光谱,获得了U原子一条较佳的三色三光子共振电离路径,对应激光的波长分别为591.7,565.0和632.4 nm。此系统还可用于测量同位素位移和原子超精细结构等参数。另外,由于此系统中联用了质量分析器,因此可用于样品多元素分析、痕量元素分析、同位素丰度分析。     

基于邻域贡献权值细化的圆心亚像素定位算法

针对传统的圆心算法过程复杂、定位精度受初始边缘提取效果影响较大等问题,提出了一种基于邻域贡献权值细化的圆心亚像素定位算法。首先引入邻域贡献权值系数,改进传统非极大值抑制法,细化边缘;然后在边缘点的梯度方向对灰度值进行高斯拟合,确定亚像素边缘位置;最后针对边缘突变点提出了基于随机抽样一致的最小二乘法来拟合圆心。实验结果表明,该算法具有较好的精度和稳定性,圆心的提取精度可以达到0.1个像素。     

LUND面积定律产生子在R值测量中的应用

对Lund弦碎裂模型强子化面积定律严格求解,得到e⁺e^－湮没产生少体初始强子态的遍举分布.基于面积定律的新产生子LUARLW在2—5GeV能区的模拟结果与BES数据的多种谱分布符合很好,用于BES上强子产生总截面测量的强子探测效率的估计.     

GaAs异质结材料BOA光开关特性分析

本文较为详细地讨论了GaAs异质结材料BOA型光开关的特性;并应用转移矩阵理论和有效折射率法计算和分析了电极结构与器件半波电压和串音度的关系.结果表明:通过优化设计电极的宽度可以获得BOA型光开关最小的半波电压;电极位置的对称性对器件串音度起决定性的影响.采用自对准工艺技术可以比较准确的控制电极的位置.分析表明:要得到<-40dB的串音度,电极位置偏差必须小于0.3μm.     

USING RANDOM PROPORTIONAL PULSE FEEDBACK OF SYSTEM VARIABLES TO CONTROL CHAOS AND HYPERCHAOS

A method that allows one to control chaotic and hyperchaotic systems by a random proportional pulse feedback of system variables is proposed. This method is illustrated with the Rossler chaotic and the complex Lorenz-Harken hyperchaotic systems, and a better control result is obtained. The advantage of this method is that just one perturbed system variable is enough to obtain a stabilized periodic orbit.