用格子Boltzmann模型模拟激波现象

根据微观和宏观之间的质量、动量、能量守恒准则,建立了一个两维的D2Q13格子Boltzmann模型,可从该D2Q13模型出发推导出宏观的流体力学方程,所得动量方程和Navier-Stokes方程相比,在黏性输运项上有明显的改进,用该模型对冲击波在障碍物表面上的折射和反射现象的数值模拟都得到了比较满意的结果,而且数值稳定性也很好.证明了D2Q13模型的适宜性 关键词： Boltzmann模型 分布函数 冲击波 流体力学方程     

纳米TiO_2修饰电极对鲁米诺电化学发光的增敏及TiO_2晶型的影响

该文水解合成并通过煅烧改变晶型,获得了金红石和锐钛矿两种晶型混合的二氧化钛纳米粒子。利用紫外可见分光光度法(UV-Vis)、激光粒度分析(LPSA)、X射线多晶衍射分析(XRD)和冷场发射扫描电镜(SEM)等方法对样品进行了表征。制备了以氧化铟锡(ITO)玻璃为基底的纳米TiO2修饰电极,并研究了晶型对鲁米诺电化学发光(ECL)的增敏作用的影响。结果表明,当粒径较小,经650℃煅烧处理形成混晶时,纳米TiO/ITO修饰电极对鲁米诺电化学发光的增敏效果最明显,为裸电极的7.5倍。     

可调节活动导叶的形状解析

贯流式水轮机的活动导叶和转轮叶片都是可调节的,活动导叶开度角γG与转轮叶片角φR的协联关系相当重要,协联关系对水轮机设计及运行能够提供有效的帮助.至目前为止,γG和φR的协联关系即协联工况只能在水轮机设计完成后通过模型试验得到。本文在给定转轮叶片角φR的情况下,通过对活动导叶叶栅流道进行形状解析,进而在设计平台上预测对应协联工况开度角γG.     

Molecular Dynamic Simulation on Graphitization and Dehydrogenization of Hydrogenated Carbon Films in Vacuum

The thermal stability of hydrogenated carbon films with H fraction from zero to 51.5% is studied by carrying out a molecular dynamical simulation on the annealing process in vacuum. Our simulations show that both graphitization temperature and dehydrogenization temperature decrease with H fraction in the films, which is in good agreement with the available experimental data. The dehydrogenization temperature is found to be much higher than the graphitization temperature. It is indicated that graphitization is the dominant process causing the degeneration of hydrogenated carbon films.     

多天线信道空间衰落相关性近似算法及其复杂性研究

信道空间衰落相关性(SFC)主要取决于波达信号的功率方位谱(PAS)和多天线阵列收发模式.深入研究了移动通信系统中多天线阵列SFC近似计算法及其复杂性.首先导出在典型PAS为均匀分布、高斯分布以及拉普拉斯分布下的SFC函数的闭合表达式.再研究在波达信号PAS小角度扩展时的近似计算法,建立多输入多输出(MIMO)多天线接收信道模型,深入分析所选择的天线阵列和电波传播参数对MIMO系统信道容量的影响.通过理论计算和仿真实验得出近似计算法在特定条件下具有很好的拟合度,定量分析了近似计算法在对MIMO多天线系统分析时的适用性和计算效率.该算法能极大地减低理论计算复杂性,提高分析和仿真MIMO多天线系统的效率.     

a-C：H膜的高真空磨损失效机制研究——应力的影响

采用中频非平衡磁控溅射法沉积了含氢无定形碳(ａ-C:H)薄膜,利用球-盘摩擦试验机考察了不同载荷下薄膜在高真空中(5.0×10^-3 Pa)的摩擦磨损行为,通过对磨损表面的分析以及相关的验证实验,探讨了应力(接触应力、薄膜内应力)对薄膜在高真空中摩擦磨损行为的影响.结果表明:在高真空中,随着载荷的增加,薄膜的摩擦系数逐渐降低,而耐磨寿命却急剧缩短;在高真空高接触应力下,无论是摩擦还是静压,薄膜表面均出现了明显的应力释放花样.因此可以认为,薄膜在高真空中的磨损失效与其在高接触应力下的内应力释放有密切关系.     

Superior tribological properties of an amorphous carbon film with a graphite-like structure

Amorphous carbon films with high sp² concentrations are deposited by unbalanced magnetron sputtering with a narrow range of substrate bias voltage. Field emission scanning electron microscopes (FESEMs), high resolution transmission electron microscopes (HRTEMs), atomic force microscopes (AFMs), the Raman spectrometers, nano-indentation, and tribometers are subsequently used to characterize the microstructures and the properties of the resulting films. It is found that the present films are dominated by the sp² sites. However, the films demonstrate a moderate hardness together with a low internal stress. The high hardness of the deposited film originates from the crosslinking of the sp² clusters by the sp³ sites. The presence of the graphite-like clusters in the film structure may be responsible for the low internal stress. What is more important is that the resulting films show excellent tribological properties with high load capacity and excellent wear resistance in humid atmospheres. The relationship between the microstructure determined by the deposition condition and the film characteristic is discussed in detail.     

采用自动前处理LC/MS进行血浆中药物的快速分析

药物研究的发展对高通量的样品处理分析提出了越来越高的要求,减少样品制备时间和分析时间是解决问题的关键。我们新近发展了一种具有在线稀释旁路和新的样品预处理柱的Shim-Pack MAYI-ODS自动柱切换HPLC和LC／MS系统,该系统无需样品前处理,可直接进样进行血浆、血清中的药物分析。本文利用自动样品前处理LC／MS系统,用ODS整体柱实现了血浆中药物的快速分析。包括样品预处理,整个分析仅需1．2min完成。