Pico-second photoelectric characteristic in manganite oxide La0.67Ca0.33MnO3 films

Ultrafast photoelectric characteristic has been observed in La_0.67Ca_0.33MnO₃ films on tilted SrTiO₃ substrates. A pico-second (ps) open-circuit photovoltage of the perovskite manganese oxide films has been obtained when the films were irradiated by a 1.064μm laser pulse of 25 ps duration. The rise time and full width at half-maximum of the photovoltage pulse are ～300 ps and ～700 ps, respectively. The photovoltaic sensitivity was as large as ～500 mV/mJ.     

Structural characteristics of ultra-low k SiO<Subscript>2</Subscript> thin films prepared using a molecular template

Nanoporous SiO₂ thin films with ultra-low dielectric constants were synthesized using a molecular template method. Uniform films with pore size between 10 and 20 nm were obtained as observed by N₂ adsorption/desorption isotherms and transmission electron microscopy. Fourier transform infrared spectroscopy (FTIR) and differential thermal analysis were carried out to investigate the effect of n-hexane washing on structural properties before and after the surface modification process. The results showed that –OH bonds were substituted with –CH₃ bonds in the films as a result of modification of trimethylchlorosilane (TMCS)/n-hexane solution. Four kinds of model were used to analyze the relationship between porosity and dielectric constant of the films, where the dielectric constant was determined from capacitance-voltage measurements. The investigation indicated that the corresponding relationship was in accord with that estimated by the Rayleigh model.     

Electron acceleration in a tightly focused laser beam

Electron acceleration in a tightly focused ultra-intensity linear polarized laser beam is investigated numerically. It has been found that the acceleration is strong phase dependent and is periodic to the variety of the initial laser field phase. When optimal initial parameters are chosen, the electron can be accelerated effectively. The accelerated electrons are emitted in pulses of which the full width is less than the half period of the laser field.     

一类正则化参数自由的线性约束凸优化问题的预测-校正算法

我们对文章的结构做这样的安排:第二节给出本文需要的预备知识;第三节简述单个目标函数问题(1.1)的己有算法和求解可能遇到的困难,第四节给出解决问题的预测-校正方法;第五节和第六节对问题(1.2)分别陈述己有方法的固有困难和我们提出的解决方案.最后,在第七节中,我们为提出的方法给出统一的算法框架,证明这类算法的收敛性和遍历意义下的收敛速率,同时给出我们的一些结论.     

High-power continuous-wave operation of a diode-pumped laser at

The continuous-wave laser properties of an efficient diode-pumped Nd:GdVO₄ crystal operating at formed with a simple plane-concave cavity have been studied. With the incident pump power of 21 W, an output power of 6.9 W was obtained, giving an optical conversion efficiency of 32.8% and a slope efficiency of 35.3%. The laser characterization of two different Nd³⁺-doped concentration of Nd:GdVO₄ crystals were studied.     

关于GB型空间的若干结果

本文对GB型空间进行了若干讨论,得到了一些结果。 设X为Banach空间,X为X的共轭空间,B(X,X)为X到X的所有有界线性算子组成的空间。如果X中的弱收敛序列为弱收敛序列,则称X为GB型空间。Grothendieck.A于1953年证明了l~∞是GB型空间。显然自反空间是GB型空间。     

Surface profile measurement of moving objects by using an improved π phase-shifting Fourier transform profilometry

The π phase-shifting Fourier transform technique is introduced into the surface profile measurement of moving objects. A digital grating comprising two regions, which have a π phase shifting is projected onto the object. Two line-scan CCD cameras are used to capture two deformed fringe patterns with π phase shifting at the same time. As the object is moving, each point at the object surface can be captured twice. The digital correlation method is used to calibrate the experimental system. The zero-order component can be eliminated by subtracting intensities of the same surface point in two captured images. And then the phase can be extracted by Fourier transform without the disturbance of zero-order component. Experimental results demonstrate that this method is feasible for the moving surface profile detection and the measurable slope of height variation can be extended.     

横向补给系统高架索的稳定性与分岔研究

考虑集中质量对系统动力学行为的影响,建立了横向补给系统高架索振动的理论模型.利用Galerkin方法和多尺度方法对动力学方程进行渐近分析.通过对系统Jacobi矩阵特征值的讨论,分析了系统的稳定性.根据系统渐近解的消除永年项条件,得到了系统的振幅分岔方程.借助Mathematica软件,对系统的局部分岔行为进行研究,得到了系统的转迁集以及相应的局部分岔图,研究表明横向补给系统高架索的振动中存在的多种分岔现象.     

强磁场条件下金属凝固过程中第二相的迁移行为

理论分析表明,第二相的迁移行为可以通过迁移速度进行表征.影响迁移速度的因素包括第二相和熔体的物理性质、磁场强度和梯度大小、第二相的形状和体积等因素.强磁场下洛伦兹力的效果为促进第二相在基体中的均匀分布,其效率在磁场强度大于某一定值时逐渐降低.在梯度强磁场条件下,第二相迁移行为和分布状态的主要控制参数是梯度磁场下的磁化力.在磁场梯度较小时,因洛伦兹力的制约磁化力控制第二相迁移的效果不明显,随着磁场梯度的增加,磁化力的作用效果逐渐增强.通过研究强磁场下Al-Si合金、Al-Ni合金中原位自生第二相的迁移行为实 关键词： 强磁场 迁移 第二相 凝固     

嵌入到Fabry-Perot谐振腔的双晶约瑟夫森结阵列的阻抗匹配和相位锁定研究

在He等人所做的嵌入到Fabry-Perot谐振腔中约瑟夫森结阵列的微波辐照研究基础上,提出了同时实现约瑟夫森结阵列阻抗匹配和相位锁定的方法,进行了相关的电磁仿真和数值计算.双晶约瑟夫森结阵列被制作在YSZ双晶基片上,同时被嵌入到Fabry-Perot谐振腔内.通过在基片上制作与结阵列集成的串联馈电半波偶极天线阵,并对其结构进行优化实现了结与天线的匹配,数值计算表明结的辐射效率达到94%;利用天线阵辐射场的特征和对模型合理的设计,使Fabry-Perot谐振腔和基片同时谐振在合适的模式下,从而使结阵列与谐 关键词： 约瑟夫森结阵列 阻抗匹配 相位锁定 Fabry-Perot谐振腔