ABS／PMMA合金力学性能研究

采用熔融共混法,在合适工艺条件下制备出了不同PMMA牌号、不同配比的ABS／PMMA合金。并通过电子万能试验机、悬臂梁;中击实验机对合金的力学性能进行了研究,结果表明：不同牌号PMMA的ABS／PMMA合金材料拉伸强度随PMMA含量的增加而增大,断裂伸长率随PM-MA含量的增加而减小,缺口;中击强度随PMMA含量的增加而减小;比较两种不同牌号的PMMA,ABS／PMMA207合金具有更好的力学性能。     

纳米材料作为润滑油添加剂的研究进展

纳米材料由于本身物理、化学性质的特殊性在润滑油添加剂领域引起了广大研究人员的极大兴趣,本文介绍了单质纳米粉体、化合物纳米粉体和结构型纳米粉体的摩擦学性能及抗磨减摩机理。阐述了纳米材料用作润滑油添加剂进行表面改性的方法。指出了纳米润滑添加剂发展亟待解决的问题。     

闪锌矿型CdTe电子结构和光学性质的第一性原理

采用基于密度泛函理论(DFT)框架下广义梯度近似平面波超软赝势法,计算了闪锌矿型CdTe的能带结构、态密度和光学性质.计算表明,闪锌矿型CdTe为直接带隙半导体,禁带宽度为0.671eV.计算并分析了闪锌矿型CdTe的复折射率、复介电函数、吸收系数、光电导率、损失函数和反射率,其折射率为2.69,静态介电常数为7.23.计算结果与其他文献结果吻合较好,为闪锌矿型CdTe的应用提供了理论依据.     

国内外知名篮球鞋力学性能的实验研究

目的:了解国内外二款知名篮球鞋"耐克"全掌气垫篮球鞋和"安踏"非气垫篮球鞋的力学性能,评价力学功效。方法:以实验法测试二款知名篮球鞋的力学性能。结果:二款知名篮球鞋的压力测试表明,几乎所有的被试者"鞋-地"界面平均压力与峰值压力"安踏"鞋比"耐克"鞋稍高,但二款篮球鞋"鞋-地"界面的平均压力与峰值压力值都不存在显著性差异(P0.05);纵跳实验表明,"安踏"鞋纵跳高度稍高于"耐克"鞋,二者之间并无统计学上的差异;摩擦系数实验表明,"耐克"鞋的动静摩擦系数优于"安踏"鞋的动静摩擦系数,二者的的动静摩擦系数之间存在统计学上的差异(P0.05)。     

烧结温度对0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3陶瓷电学性能的影响

采用固相反应法制备了准同型相界处的0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3陶瓷,探索了其最佳预烧温度,并研究了不同烧结温度下制备的陶瓷样品的微观形貌、致密度、铁电、压电性能.结果表明,样品的致密度和剩余极化随着烧结温度的升高而略有升高,矫顽电场随着烧结温度的升高而降低.烧结温度对样品的压电性能具有非常大的影响.1 200℃烧结的样品具有非常良好的压电性能:压电常数d33～560 pC/N,厚度振动机电耦合系数kt～54.0%,径向振动机电耦合系数kp～30.4%.     

A factor analytic study of the Childhood Trauma Questionnaire-Short Form in an all-female South African sample with and without HIV infection

BackgroundThe Childhood Trauma Questionnaire-Short Form (CTQ-SF) is widely used around the world but no norms have been established for South African users of the CTQ. The CTQ has been employed in South Africa but not yet validated. The present study aims to address this gap. There is great need in both clinical and research settings for an assessment tool that adequately measures childhood trauma, a sensitive and challenging construct to measure.ObjectiveThis study explores the psychometric properties of the CTQ-SF in an all-female cohort living with and without HIV infection in South Africa, the first study of its kind in this population.Participants and settingThe CTQ-SF was administered to 314 women (170 HIV uninfected; 144 HIV infected) in Cape Town, South Africa.MethodInternal consistency of the CTQ-SF was determined by Cronbach alpha coefficients. Using Lisrel, a confirmatory factor analysis (CFA) was performed, followed by an exploratory factor analysis (EFA) to explore an alternative factor structure model in this cohort.ResultsFor the group as a whole, the model fit was acceptable but not good. However, for the sub-sample of women living with HIV, the CFA revealed poor model fit. The EFA revealed a three-factor model, with mostly stable factor loadings for four of the five subscales. However, the Physical Neglect (PN) subscale cross loaded on two of the three factors.ConclusionOur findings revealed an alternative factor structure from the original model in this study cohort. The PN subscale does not have stable factor loadings and is not homogenous. The original instrument may therefore benefit from revision for use in this population. Measures such as the CTQ can be informative for preventative strategies in HIV-infected or at-risk youth and for clinical interventions aimed at mitigating the negative psychological sequelae of childhood maltreatment.     

分子水平上研究地质流体的物理化学性质（英文）

研究地质流体的物理化学性质和地球化学行为是地球系统科学研究所面对的挑战性课题之一。与诸如实验和物理化学建模等传统研究方法相比,分子水平上的计算机模拟在解决极端条件下流体体系物理化学性质方面表现出明显的优势,成为定量研究地球内部不同层圈中地质流体特点及其作用规律的有效途径。本论文简要介绍了我们把计算机模拟技术应用到地质流体研究中的成果,主要可概括为：（1）利用蒙特卡罗计算机模拟方法,我们成功地模拟了地质流体体系相平衡和相变,取得了与实验一致的结果,从而在计算机上实现了相平衡研究,与花费昂贵的实验相比具有方法学上的先进性;（2）通过分子动力学模拟研究水的物理化学性质,我们把水的PVT数据从实验所允许的温压范围（温度小于1873.15 K、压力低于5万大气压）扩展到2000 K、20万大气压,并提出了一个适用于宽广温压条件下的状态方程;（3）通过分子动力学和蒙特卡罗模拟,我们建立了一个CO2分子模型,它能同时准确预测CO2的各种物理化学性质和行为（PVT性质、相平衡、潜热、结构性质和动力学性质）;（4）通过分子动力学模拟研究氯化锂在溶液中的离子水化和缔合性质,我们得到了与实验和量子力学模拟一致的结果,与此同时还揭示了离子水化和缔合过程的微观机制。     

当代排球比赛中的几个特性

正确、牢牢地把握住当代排球比赛中的特性,能使教练员、运动员乃至决策部门从宏观上认清排球运动的发展趋势,从而制定出行之有效的对策。本文认为,当代排球比赛中的特性主要表现在以下几方面:快这;高度;变化;创新;全面。     

Some algebraic properties of generalized inverse matrix-valued Padé approximation

The matrix Padé approximant based on generalized inverse is characterized by keeping approximation order and without multiplication of matrices in the construction process. The aim of this paper is to give and prove some algebraic properties of generalized inverse matrix-valued Pade approximation by means of its definition. Computational examples are given to illustrate the applications of the properties, which greatly simplify the computation process. Supported by the National Natural Science Foundation of China (19871054)     

The residual-based ESG algorithm and its performance analysis

The performance of the residual-based extended stochastic gradient (ESG) algorithms for identifying CARMA models with disturbances is analyzed under weaker conditions on statistical properties of the noise. The paper derives the conditions under which the parameter estimation errors converge to zero. Three examples are given to show the advantages of the proposed algorithm.