铁磁性过渡离子掺杂对纤锌矿相硫化锌电子结构的影响

通过第一性原理计算,优化了铁磁性过渡离子掺杂的纤锌矿相硫化锌Fm0.125Zn0.875S(Fm=Fe、Co、Ni)的几何结构,计算了其电子结构,分析了其半金属性及其微观机制。结果表明:对不同的铁磁性杂质离子,Fm0.125Zn0.875S在费米面处的自旋极化率均为-100%,具有半金属性,是潜在的优质自旋注入材料。Fm0.125Zn0.875S具有较宽的自旋带隙,从而具有较高的居里温度和广泛的应用前景。Fe0.125Zn0.875S、Co0.125Zn0.875S和Ni0.125Zn0.875S的2×2×1超胞的磁矩分别为3.96μB、2.90μB和2.00μB,主要来自于铁磁性过渡离子Fe、Co和Ni离子。这3种离子的电子结构分别为eg2↑eg1↓t2g3↑,eg2↑eg2↓t2g3↑和eg2↑eg2↓t2g3↑t2g1↓。     

由东南亚海啸引发的一堂物理课

印度洋海啸被认为是一次“全球性地球物理学事件”．通过对“海啸的物理学”的教学设计,利用从互联网收集的最新资料,结合学生的物理知识,对海啸中的物理现象作了计算和分析．     

Adsorption of ponceau 4R from aqueous solutions by polyamidoamine–cyclodextrin crosslinked copolymer

Batch adsorption experiments were carried out for the removal of ponceau 4R (P4R, C.I. 16255) from aqueous solutions using a novel polyamidoamine–cyclodextrin crosslinked copolymer (PAMAM-CD). The influence of several operating variables, such as contact time, initial concentration, pH, ionic strength, was investigated. Results showed that PAMAM-CD exhibited very high adsorption capacity toward P4R. The adsorption capacity of P4R was even up to 254.3?mg/g when the initial concentration of P4R solution was 340?mg/L at 288?K. The maximum adsorption capacity occured at below pH 5. The adsorption rate was fast and over 52% of the equilibrium adsorption value occurred in the first 15?min at 308?K. Adorption kinetics followed the Ho and McKay equation. Intraparticle diffusion was involved in the adsorption process but it is not the only rate-controlling step. Equilibrium isotherm data were precisely fitted by the Langmuir model. The negative values of Gibbs free energy change indicated the spontaneous nature of adsorption. The PAMAM-CD was easily recovered by 2?M HCl as washing solvent and it could be used as a promising alternative adsorbent.     

Lagrangian conditions for approximate solutions on nonconvex set-valued optimization problems

The purpose of this paper is to consider the set-valued optimization problem in Asplund spaces without convexity assumption. By a scalarization function introduced by Tammer and Weidner (J Optim Theory Appl 67:297–320, 1990), we obtain the Lagrangian condition for approximate solutions on set-valued optimization problems in terms of the Mordukhovich coderivative.     

截断调和Bergman空间上的Toeplitz算子

截断调和Bergman空间b_n~2=L_a~2{w,w~2,…,w~n}~v是Hilbert空间L~2的闭子空间.研究了单位圆盘上的截断调和Bergman空间上的Toeplitz算子的乘积问题,完整地刻画了具有有界调和符号的两个Toeplitz算子的有限秩与紧的半换位子或换位子.     

Generalized B-Well-Posedness for Set Optimization Problems

This paper aims at studying the generalized well-posedness in the sense of Bednarczuk for set optimization problems with set-valued maps. Three kinds of B-well-posedness for set optimization problems are introduced. Some relations among the three kinds of B-well-posedness are established. Necessary and sufficient conditions of well-posedness for set optimization problems are obtained.     

Gyrator变换全息图及其在图像加密中的应用

提出了gyrator变换全息图,利用gyrator变换快速算法模拟实现了gyrator变换全息图的产生和再现,并研究了基于相移数字全息的gyrator变换全息图.在此基础上提出了采用正弦相位光栅实现光学图像加密的新方法.该方法利用gyrator变换在相空间的旋转特性,将gyrator变换的角度、光栅的频率及光栅的旋转角度作为加密密钥,并利用两个或两个以上的gyrator变换系统的级联实现图像加密,增加了系统的安全性.依据相移数字全息进行的两个gyrator变换系统级联的仿真实验验证了该方法的可行性、有效性及其良好的安全性能.     

Variable selection in the partially linear errors-in-variables models for longitudinal data

This paper proposes a new approach for variable selection in partially linear errors-in-variables (EV) models for longitudinal data by penalizing appropriate estimating functions. We apply the SCAD penalty to simultaneously select significant variables and estimate unknown parameters. The rate of convergence and the asymptotic normality of the resulting estimators are established. Furthermore, with proper choice of regularization parameters, we show that the proposed estimators perform as well as the oracle procedure. A new algorithm is proposed for solving penalized estimating equation. The asymptotic results are augmented by a simulation study.     

关于酉对称矩阵的QR分解及其算法

为了简化大型行(列)酉对称矩阵的QR分解,研究了行(列)酉对称矩阵的性质,获得了一些新的结果,给出了行(列)酉对称矩阵的QR分解的公式和快速算法,它们可极大地减少行(列)酉对称矩阵的QR分解的计算量与存储量,并且不会丧失数值精度.同时推广和丰富了邹红星等(2002)的研究内容,拓宽了实际应用领域的范围.     

上海世博会的经济综合影响力指数模型

分析上海世博会在世博筹备建设和举办时期对上海市经济方面影响.筛选了世博会影响经济的四个方面(国民经济,财政收支,固定资产投资和对外经济贸易与旅游)的10个主要指标,构建了世博会影响经济的评价指标体系,针对每一项指标,利用1995年到2002的实际数据用指数回归拟合模型测算出2003-2010年在未筹办世博会情况下各项经济指标的估计(拟合)数据,并建立单指标的影响力指数模型,在分析2003年后的实际数据与拟合数据差异基础上,获得了上海世博会在每个指标方面对上海的影响力指数;建立了多指标综合影响力指数模型,得出总的经济影响力的指数为0.2403.考虑到2008年底金融危机势必会削弱世博会对经济的影响,通过参照另外两个同为中国直辖市的重庆和天津相同指标的变化,运用单独建立的模型,剔除金融危机对经济的影响,从而获得更客观地揭示世博对上海地区经济的真实影响程度.并就两个典型的指标给出了具体的演算过程,最后得到了消除了金融危机后的所有指标的影响力指数值,最终获得总的经济影响力的指数为0.2531,即世博会对上海市经济的实际贡献率为25.31%.