用于太赫兹光源的准等时性储存环的设计

介绍了一种获得准等时性储存环的方案,即调节Lattice参数,在色散段引入负色散函数从而降低线性滑相因子,获得短束团。根据此方案设计了用于相干太赫兹光源的准等时性储存环,结果给出了线形光学函数曲线以及粒子的动力学孔径,表明了通过调节四极铁参数可以达到降低束团长度获得准等时性储存环的目的。还设计了用于准等时性储存环弯铁处的真空室的3维模型,并对其类腔体部分的本征模进行了计算,得到特性阻抗与品质因数的比值在10-3量级以下,表明类腔体部分对束流的影响很小。     

薄膜光学参数表征误差处理技术

针对光度测量数据中难以消除的系统误差对薄膜光学参数表征精度的负面影响,提出一种新型的误差处理技术。选取薄膜光谱系数对折射率和几何厚度的一阶偏导数,对大部分测量入射角满足符号相反或只有其中一个为零的条件的波段,剔除偏导数对全部测量入射角满足符号相同或同时为零条件的奇点波长附近波段,作为反演表征用的光度测量数据采集区域,以最小化光度测量系统误差引起的薄膜光学参数反演表征值相对真实值的偏差大小。通过数值模拟实验,对比研究了该技术对不同偏振光和不同测量入射角范围的适用性及实施技巧,以可复现的数值实验数据和合理的理论解释支持和验证了这种误差处理技术的可靠性。     

低温冷风与传统加工对磨削质量的对比分析

针对磨削加工传统方法的不足设计了一种新型低温冷风加工磨削装置,能够提供0～-80℃连续低温,压力在0.3～0.5MPa范围内变化,结构简单,操作控制方便,加工成本低。通过对比工件的表面粗糙度,发现使用低温冷风磨削效果优于传统磨削,并且低温冷风温度越低,压力越高则工件表面质量越好,机床参数与低温冷风参数相比对工件的表面粗糙度影响不很明显。     

大气湍流光学参数分析

利用两种不同大气湍流结构常数模型,讨论了不同高度的湍流对大气湍流光学参数的影响。通过理论计算得出:相干长度和对数振幅起伏方差主要由低层大气湍流决定,而等晕角、倾斜等晕角、格林伍德频率和泰勒频率由对流层顶附近的高层湍流决定。分析了垂直高度30 km以下的3部分大气湍流对等晕角的贡献比例,在给定的不同强度湍流下,对流层顶附近的高层大气湍流贡献比例都大于25％,而低层大气湍流的贡献比例都小于3%。     

基于斯托克斯参量的光弹性应力分布及成像方法研究

提出了一种基于斯托克斯参量测量的实时光弹性应力测量及其成像的新方法,对该方法的原理及参量测量方法进行了深入研究。根据分振幅斯托克斯参量测量原理设计一个实验系统,利用Equator-Poles(E-P)法定标系统,采用4个性能一致的光电探测器实现光束斯托克斯参量的快速实时测量。用实验系统测量单色平面偏振光通过光弹性样品后的斯托克斯参量,求得出射与入射偏振光的相位延迟量,再求得样品的应力值。运用该方法对有应力分布的平板玻璃和轴向受压有机玻璃进行测量并扫描成像,得到它们的应力分布图像。结果表明,该方法能够准确、快速和无损地测量光弹性样品任意位置的应力,实现对应力的实时测量。     

薄膜生长荧光显微图像实时采集与分析系统

设计了一套具有一定实用意义和科学价值的薄膜生长荧光显微图像实时采集与分析系统,可以实现透明衬底上有机荧光分子薄膜生长的实时原位监测。进一步阐明了系统的硬件构筑思路和软件设计架构,并依据薄膜的形貌特征,给出8个主要生长信息参数及其求取算法,并利用自行搭建的实验系统,针对联六苯(p-6P)分子在云母衬底上的纳米纤维生长过程,得出了其准一维的线性生长规律。该系统作为重要的薄膜生长成像监测技术,有望在薄膜与衬底表面相互作用和衬底微区结构特性研究等方面起到积极的作用。     

Studies on oxovanadium(IV), Cr(III), Co(II), Ni(II), and Cu(II) chelates of some bisketimino ligands

The oxovanadium(IV), Cr(III), Ni(II), Co(II), and Cu(II) chelates of some bisketimino Schiff-base ligands (H₂L) obtained by condensation of 4-butyryl-3-methyl-1-phenyl-(or-1,3-diphenyl)-2-pyrazolin-5-ones with thiourea were synthesized and characterized by elemental analyses and thermogravimetric analyses, molar conductivities, magnetic susceptibility measurements, mass, infrared, and electronic spectroscopies. Ligand field parameters, such as splitting energy, Racah parameter, spin–orbit coupling constant, and covalency parameter of the Cr(III), Ni(II), and Co(II) chelates were calculated by band-fitting methods. Based on these studies, tetragonally distorted octahedral environment around OV(IV) and Cu(II) and octahedral Cr(III), Ni(II), and Co(II) have been proposed.     

Viscosity and Thermodynamics of Viscous Flow of 1-propanol with Aniline,N-methylaniline and N,N-dimethylaniline

Abstract

Viscosities of the systems, 1-propanol + aniline, 1-propanol+N-methylaniline and 1-propanol+N,N-dimethylaniline have been measured in the temperature range 294.15 to 323.15K for the whole range of composition. The viscosities have been plotted against mole fraction of anilines. The viscosity-composition curves show minima, though not well-defined, in highly rich, moderately rich and moderately poor regions of 1-propanol respectively for 1-propanol + aniline, 1-propanol + N-methylaniline and 1-propanol +N,N-dimethylaniline systems. The excess viscosities have been found to be negative for all the systems throughout the whole composition and plotted against mole fraction of anilines. The thermodynamic activation parameters, such as, enthalpies, entropies and free energies and their excess values have been evaluated. The excess free energies have been found to be negative for all the systems and over the whole range of composition. The excess free energies have been plotted against the mole fraction of anilines. The viscosities, excess viscosities and excess free energies have been explained by assuming that the associated compounds, aniline, N-methylaniline and 1-propanol, are dissociated into smaller units in the solution systems by the rupture of H-bonds.     

Robust hierarchical a posteriori error estimators for stabilized convection–diffusion problems

We construct a hierarchical a posteriori error estimator for a stabilized finite element discretization of convection‐diffusion equations with height Péclet number. The error estimator is derived without the saturation assumption and without any comparison with the classical residual estimator. Besides, it is robust, such that the equivalence between the norm of the exact error and the error estimator is independent of the meshsize or the diffusivity parameter. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2012