Transitional phenomenon of particle dispersion in gas-solid two-phase flows

Without using any turbulent model, direct numerical simulation of a three-dimensional gas-solid two-phase turbulent jet was performed by finite volume method. The effects on dispersion of particles with different Stokes numbers by the transitional behavior of turbulent structures were investigated. To produce high-resolution results and reduce the computation and storage, the fractional-step projection algorithm was used to solve the governing equations of gas phase fluid. The low-storage, three-order Runge-Kutta scheme was used for time integration. The governing equations of particles were solved in the Lagrangian framework. These numerical schemes were validated by the good agreement be-tween the statistical results of flow field and the related experimental data. In the study of particle dis-persion, it was found that the effects on particle dispersion by the spanwise vortex structures were prominent. The new behaviors of particle dispersion were also observed during the evolution of the flow field, i.e. the transitional phenomenon of particle dispersion occurs for the particles with small and intermediate Stokes numbers.     

二元向量输出的Partially Bent函数

把关于布尔函数的Carlet不等式推广到向量输出的布尔函数并且引入了向量输出的Partially Bent函数的概念,即广义Carlet不等式中等式成立的向量输出布尔函数.给出了一些广义Carlet不等式中等式成立的充分必要条件.进一步讨论了二元向量输出的partially bent函数的密码学性质.     

Electronic properties and stabilities of methoxy-substituted Lindqvist polyoxometalates [Nb2W4019CH3]3- by DFT

The electronic properties and stabilities of five [Nb2W4O18OCH3]3-isomers have been investigated using a density functional theory method.The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms(two tungsten atoms in the plane that contains two niobium atoms) in the [Nb2W4O18OCH3]3-framework is the most stable isomer in acetonitrile.The stability of the one-electron-reduced isomers changes little.The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4-framework.The M-Ob(M = Nb,W;b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb2W4O19]4-.The highest occupied molecular orbitals(HOMO) in [Nb2W4O19]4-mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,and the bridging oxygen atoms on the axial surface.The lowest unoccupied molecular orbitals(LUMO) of [Nb2W4O19]4-are mainly concentrated on the tungsten atoms and antibonding oxygen atoms.Methoxy substitution modifies the electronic properties of the [Nb2W4O18OCH3]3-isomers.The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms,which are distant from the surface containing the methoxy group and four metal atoms.The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group,and the p-orbitals of oxygen.One-electron reduction occurred at the tungsten atoms,not the niobium atoms.     

Structures and Properties of Composite Yarns of Filaments and Wool Staple Fibers

More and more composite yarns of filament and wool staple fiber have been applied to develop the new type of fabrics. However, the great difference in yarn structures between the composite yarns and conventional staple yarns does affect the properties of yarns and fabrics. In this paper, it has been studied that the differences of the composite yarn properties of tensile, bending rigidity, torsional rigidity, the hairiness and irregularity etc.     

喹诺酮药物及其金属配合物研究进展

本文综述了喹诺酮类抗菌药物的发展历程和喹诺酮金属化合物的配位结构和活性等方面的研究现状,展望了此类研究的发展趋势。     

南方菟丝子水溶性成分的研究

采用Sephadex LH-20、RP-18反相柱、MCI和硅胶层析方法对南方菟丝子全草的化学成分进行分离纯化，运用现代波谱技术鉴定TZ个化合物：表儿茶素、刺五加-O-β—D-葡萄糖甙和Roseoside I。     

混合结构建筑温度收缩应力的近似计算

目前国内的混合结构建筑，由于温度变化以及材料伸缩等原因引起的墙体裂缝现象较为普遍。根据混合结构房屋构件之间的相互约束以及协同工作的关系，文章提出了温度收缩应力和变形的近似计算方法。计算结果表明，与现场实测的结果吻合较好，计算公式可供工程实践参考。     

沉降观测中被测建构筑物可视为基本稳定的判定

详细介绍了沉降观测中被测建构筑物可视为基本稳定的判定方法,提出了在沉降观测中应注意的事项。     

焊接结构及其维修的可靠性分析

本文以马尔科夫链理论研究了焊缝中裂纹的随机扩展过程,并在此基础上分析了焊缝的补焊问题,同时提出了“当量运行次数”的概念.对于工程中可能进行多次维修的结构,文中给出了损伤的稳态分布。最后用优化理论分析了最大经济效益意义上的维修方案。     

井巷多断面岩层热传递方式与深井热环境动态分析

确定井巷风流热量来源及关键地点温度变化、热增量与损失量,并以之为依据有针对性地开展深井气候调节是通风工程需要解决的关键问题之一.通过改进传统的傅里叶导热模型,建立了基于通风井巷实际断面形状的三维热传导模型,针对不同井巷断面形状确定了反映流速与流量状态的动量相关的计算边界条件,并结合时间参数揭示了岩层内部导热以及井巷岩壁与气流间的热交换规律,建立了湿壁面与气流间的热湿传导方程.在此基础上,构建起国内某大型深井金属矿山井下通风系统,获得了关键地点的温度、湿度、热量等参数的走势和变化特点,为矿山开展深井气候调节与控制奠定了基础.