稀薄气固两相流的数值分析

本文用拉格朗日方法对稀薄气固两相流进行了数值分析,着重讨论有颗粒存在时,颗粒对气流速度分布的影响。计算的实例与实验结果比较,有着很好的吻合。     

90°弯道内紊流的试验研究

一、试验设备及方法 本文应用LDV测量了弯曲度R_c/D=1.69矩形弯道内的紊流。来流属于正在发展的紊流区流动,弯道的简图示于图1。流动介质为空气,入口平均流速U_a=22.8(m/s),雷诺数为5.6×10~4,Dean数为2.9×10~4,各个截面均以Z~*=0为对称面。经过校核试验,数据的对称性甚好,因此只测量半个截面。对大部分截     

Geometric shapes of the interface surface of bicomponent flows between two concentric rotating cylinders

In this paper, the shape problem of interface of bicomponent flows between two concentric rotating cylinders is investigated. With tensor analysis, the problem is reduced to an energy functional isoperimetric problem when neglecting the effects of the dissipative energy caused by viscosity. We derive the associated Euler-Lagrangian equation, which is a nonlinear elliptic boundary value problem of the second order. Moreover, by considering the effects of the dissipative energy, we propose another total energy functional to characterize the geometric shape of the interface, and obtain the corresponding Euler-Lagrangian equation, which is also a nonlinear elliptic boundary value problem of the second order. Thus, the problem of the geometric shape is converted into a nonlinear boundary value problem of the second order in both cases.     

Growth and Characterization of Trumpet-Shaped ZnO Microtube Arrays on Si Substrates

Aligned trumpet-shaped zinc oxide microtube arrays have been successfully prepared on silicon （100） substrates via the chemical vapour deposition method with a mixture of ZnO and active carbon powders as reactants. The results show that two types of trumpet-shaped ZnO microtubes can be obtained. A plausible growth mechanism based on the studies of scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, x-ray diffraction （XRD）, and room-temperature photoluminescence spectroscopy is proposed and discussed. The initial metastable zinc-rich ZnOx embryos play a key role in the formation of trumpet-shaped ZnO microtubes. On the different surfaces of metastable zinc-rich ZnOx （x 〈 1）, embryos exhibit different stabilities and resistivities to oxidation; these tiny embryos are gradually extended with different growing rates along the directions of its long axis and circular boundary around its oxide shell. Just this special reason creates the formation of trumpet-shaped microtubes and results in the inerratic and imperfect hexagonshaped cross section that appears. Moreover, the analytical results also show that the as-synthesized ZnO microtube arrays can exhibit better room-temperature photoluminescence behaviour.     

二维流面上的流动问题的速度图方法

对于一些特殊的流动,尤其是平面上的位势流动,速度图方法有其显著的优点.对于理想流体来说,流面总是存在的,在流面上,流动的速度向量总是在其切空间里.通过引入流函数和势函数,采用张量分析作为工具,给出了二维曲流面上位势流动的速度图方法,得到了流函数满足的速度图方程,为一些特殊的流动问题提供了一类分析方法.并且,对于得到的二维速度图方程,得到了相应的特征方程和特征根,从而可以对方程的类型进行分类.最后,给出了一些特殊流动的实例.     

两个同心旋转圆柱之间的两种流体的交界面几何形状问题

研究两个同心旋转圆柱之间的两种流体的交界面几何形状问题.利用张量分析工具,给出了忽略耗散能量影响下交界面几何形状是一种能量泛函的临界点,其对应的Euler-Lagrange方程是1个非线性椭圆边值问题.对于粘性引起的耗散能量不能忽略的情况下,同样给出了1个带有耗散能量的能量泛函,其临界点是交界面几何形状,相应的Euler-Lagrange方程也是1个二阶的非线性椭圆边值问题.这样,交界面几何形状问题转化为求解非线性椭圆边值问题.     

苯炔对双键插入反应的研究进展

苯炔对双键的插入反应是近年来苯炔化学的一个热点领域.苯炔对双键插入将产生一个邻亚甲基醌型中间体,后者和苯炔一样是有机反应的重要活性中间体之一.综述了近年来苯炔对双键的插入反应及其在合成化学中的应用,并力图从反应机理的角度对这些插入反应及其生成的中间体进行结构上和反应活性上的阐释.     

参数最短路的原始-对偶算法

本文利用原始－对偶方法,对于含参数λ的网络（Ｖ,Ｅ,ｆ_１-λｆ_２）,给出了某一点至其它各点的参数最短路的求解算法,其时间复杂度为 Ｏ（ｎｍ＋ｎ~２ｌｏｇｎ）．     

Hodograph method of flow on two-dimensional manifold

For some special flows, especially the potential flow in a plane, using the hodograph method has obvious advantages. Realistic flows have a stream surface, namely, a two-dimensional manifold, on which the velocity vector of the flow lies on its tangent space. By introducing a stream function and a potential function, we establish the hodo- graph method for potential flows on a surface using the tensor analysis. For the derived hodograph equation, we obtain a characteristic equation and its characteristic roots, from which we can classify the type of the second-order hodograph equation. Moreover, we give some examples for special surfaces.     

一类人员招聘问题的算法研究

在人员招聘工作中,通常有招聘总人数和各部门最低录取人数要求等限制。针对给定的限制条件,本文给出了一类人员招聘问题的数学模型。考虑招聘过程中固定指标为0和机动指标为0的特殊情形,分别给出了相应模型的贪婪算法和匈牙利指派算法,在此基础上给出了求解该问题的一种基于指派问题的一般算法,并对相应的算法的最优性给出了证明,算法的复杂度仅为O(m3)。以公务员招聘的实际算例验证,模型能合理地满足招聘单位的实际需求。