Hilbert�CSchmidt differences of composition operators on the Bergman space

In the setting of the weighted Bergman space over the unit disk, we characterize Hilbert?CSchmidt differences of two composition operators in terms of integrability condition involving pseudohyperbolic distance between the inducing functions. We also show that a linear combination of two composition operators can be Hilbert?CSchmidt, except for trivial cases, only when it is essentially a difference. We apply our results to study the topological structure of the space of all composition operators under the Hilbert?CSchmidt norm topology. We first characterize components and then provide some sufficient conditions for isolation or for non-isolation.     

Structural, magnetic and electronic structure studies of Mn doped TiO2 thin films

We report structural, magnetic and electronic structure study of Mn doped TiO₂ thin films grown using pulsed laser deposition method. The films were characterized using X-ray diffraction (XRD), dc magnetization, X-ray magnetic circular dichroism (XMCD) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements. XRD results indicate that films exhibit single phase nature with rutile structure and exclude the secondary phase related to Mn metal cluster or any oxide phase of Mn. Magnetization studies reveal that both the films (3% and 5% Mn doped TiO₂) exhibit room temperature ferromagnetism and saturation magnetization increases with increase in concentration of Mn doping. The spectral features of XMCD at Mn L_3,2 edge show that Mn²⁺ ions contribute to the ferromagnetism. NEXAFS spectra measured at O K edge show a strong hybridization between Mn, Ti 3d and O 2p orbitals. NEXAFS spectra measured at Mn and Ti L_3,2 edge show that Mn exist in +2 valence state, whereas, Ti is in +4 state in Mn doped TiO₂ films.     

采用任务剖面的复杂可修系统保障性仿真与评价技术研究

针对现有复杂可修系统建模仿真中存在的问题,以任务成功性为中心,建立了基于任务剖面的复杂可修系统保障性仿真模型,该模型的建模与仿真方法适用于舰船同类型系统的建模与仿真.通过对仿真结果的评价、反馈、改进修正,使各种方案最终直接为完成战斗任务服务,更符合实际的要求.仿真结果表明,该方法能够有效地评估复杂可修系统的保障性参数特征,所建模型具有可视化、流程化和层次化的优点.     

鲍体表黏液的几种免疫酶比活力的比较

为探索鲍体表黏液的免疫机制,利用生化测定的方法对杂色鲍(Haliotis diversicolor)、皱纹盘鲍(Haliotis dis-cus)、西氏鲍(Haliotis sieboldii Reeve)及杂色鲍不同杂交群体鲍体表黏液中的酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、总超氧化物歧化酶(T-SOD)的比活力进行了测定,并比较了它们之间的差异.结果表明在3种不同鲍中,西氏鲍体表黏液中AKP、T-SOD的比活力最强,显著高于杂色鲍台湾群体,这与生产实践中西氏鲍抗逆性强、存活量高相吻合,推测AKP、T-SOD是较好的免疫指标性酶;而在杂色鲍不同的杂交群体间,台湾♀×F1♂杂交群体与F1♀×台湾♂杂交群体体表黏液中3种酶比活力均最高,推测这种杂交方式能够产生较强的杂种优势.本研究有助于为鲍的选育和病害的防治提供参考.     

多尺度表面织构流体润滑问题的快速求解方法

为解决传统数值方法在求解多尺度织构流体润滑问题时计算速度慢、效率低、规模受限等问题,提出了有限细胞算法.针对简单的织构模型,通过对比有限元、流体力学和细胞算法的计算结果,验证了算法计算结果的准确性.通过对比不同计算规模下有限元和细胞算法的数值试验结果,发现新算法的计算速度和计算规模都有显著提升.对于大规模多尺度的织构模型,使用细胞算法进行求解,发现新算法的计算时间与网格数目成线性关系,表明细胞算法对于大规模织构问题具有良好的快速求解能力,并且为工程中类似的多尺度问题提供了具体的解决思路.     

BOT模式下的工程质量控制

近年来我国的基础设施建设突飞猛进,BOT模式在我国基础建设领域中被广泛采用。本文对BOT模式下工程质量的控制进行了论述,对BOT模式下工程质量存在的问题进行了分析,并提出了工程质量控制的措施。     

β-Ca2P2O7/CaSO4陶瓷的制备和体外降解研究

将β-焦磷酸钙和无水硫酸钙2种粉体进行复合,制备出β-焦磷酸钙/无水硫酸钙(β-Ca2 P2O7/CaSO4)复相生物陶瓷.研究了β-Ca2 P2 O7和CaSO4的比例和烧结温度对复相陶瓷气孔率、体积密度和相组成的影响,结果表明:随着CaSO4含量的增加,复相生物陶瓷的气孔率升高,体积密度降低;随着烧结温度的升高,复...     

一类椭圆型方程弱解的正则性

在一定条件假设下,讨论了一类椭圆型方程Lu=finU初值问题的弱解的正则性.通过一些技巧和方法,描述了弱解的内部正则性.这些技巧和方法包括截断函数、边界的展平、有限覆盖定理、sobolev不等式、内插不等式等.     

Extracting factors for students’ motivation in studying mathematics

The purpose of this article is to identify factors that statistically explain the variation and the measures on the level of motivation of a sample of mathematics students in a university. Specifically, this analysis will identify groups of similar items and reduce the number of variables used in a study. This article explains the use of exploratory factor analysis in extracting factors of personal belief and motivational factors among students in learning mathematics. The adaptation of these factors can be used for assessing academic performance in relation to motivation level. By identifying these factors, the mathematics educators or researchers will be able to find ways to improve the condition of the factors and also to further investigate the factors based on confirmatory approaches.