非球体颗粒在强力混合机中混匀特性的数值模拟

为了研究非球体颗粒在强力混合机的随机运动及混合特性,采用离散元法对球体、六面体以及四面体颗粒在强力混合机内的混合情况进行数值模拟研究。从颗粒接触数量、桨叶轴扭矩、速度场分布等方面分析不同形状的颗粒流动形态,并基于统计学方法探讨颗粒形状对于颗粒混合性能的影响。结果表明:相对球体颗粒而言,异形非球体颗粒接触数量以及扭矩值明显增大;颗粒的混匀性能随着颗粒接触数量的减小而下降。

矩形片状材料在水中自由沉降规律研究

针对原位覆盖技术在覆盖过程中对底泥扰动的问题,提出一种利用片状土材料作为原位覆盖材料的新方法,并研究了材料在水中沉降的规律。采用堆场淤泥作为材料进行沉降实验,主要关注了材料的沉降速度与其入切角和自身性质之间的关系。结果表明:材料的入切角不会影响材料沉降稳定时的沉降速度;材料沉降稳定时的速度与材料的厚度、密度成正比。

Analysis of Culture and Drug Sensitivity Tests of Mycoplasmas for 387 Patients with Nongonococcal Urethritis (Cervicitis) in Chongqing

Objective: To investigate the prevalence of myco-plasma infections and the sensitivity to antibiotics among patients with nongonococcal urethritis or cer-vicitis (NGU) in Chongqing. Methods: 387 NGU cases with mycoplasma-positive results upon culture were analysed retrospectively. RESULTS: The majority of patients with mycoplasma infections were in the 20-40 year old age group. No significant difference was found between males and females. Ureaplasma urealyticum is the main pathogen of these NGU cases and no clear relationship between its concentration and pathogenic ability was noted. Drug sensitivity was tested against nine antibiotics; the sensitivity rates to josamycim, minocycline and doxycycline were 94.06%, 88.89% and 86.82% respectively, while the resistance rates to lincomycin, ofloxacin, azithromycin and roxthromycin were 74.94%, 42.12%, 41.60% and 40.31% in turn. Conclusions: Josamycin, minocycline and doxycycline could be used as the first choice to treat NGU with mycoplasma infections in Chongqing. It is important to select antibiotics for NGU treatment with mycoplasma infections based on the results of drug sensitivity tests.

300GHz不规则金属定标球散射特性研究

定标球是目前应用最广泛的一种定标体,而太赫兹频段定标球的散射特性、影响规律以及加工管理准则目前尚缺乏定量分析。对不规则金属定标球体后向RCS分布特性进行了研究,计算并分析了加工误差带入的椭球体和带状条纹金属球体后向RCS。揭示了太赫兹频段金属定标球体RCS的几个影响因素,以及定标体RCS在不同因素作用下的影响规律。此后对不同表面处理金属球样品并通过测试,揭示了保存和使用误差造成的涂覆金属球体RCS的影响规律,从而首次提出太赫兹频段定标球的加工和管理准则。以上仿真和测试结果作为300GHz频段目标电磁散射模拟测量的定标技术研究成果,为300GHz频段目标电磁散射模拟测量技术研究提供必要条件。

Numerical Simulation of Concentration Field on Liquid Side around Bubble during Rising and Coalescing Process in Non-Newtonian Fluid

On the basis of Navier-Stockes equation and convection-diffusion equation, combined with surface tension and penetration models, the equations of moment and mass transfer between bubble and the ambient non-Newtonian liquid were established. The formation of a single bubble from a submersed nozzle of 1.0 mm diameter and the mass transfer from an artificially fixed bubble into the ambient liquid were simulated by the volume-of-fluid （VOF） method. Good agreement between simulation results and experimental data confirmed the validity of the numerical method. Furthermore, the concentration distribution around rising bubbles in shear thinning non-Newtonian fluid was simulated. When the process of a single ellipsoidal bubble with the bubble deformation rate below 2.0 rises, the concentration distribution is a single-tail in the bubble＇s wake, but it is fractal when thebubble deformation rate is greater than 2.0. For the overtaking of two in-line rising bubbles, the concentration distribution area between two bubbles broadens gradually and then coalescence occurs. The bifurcation of concentration distribution appears in the rear of the resultant bubble.

Theoretical Investigation of Uniform and Non-uniform Penetrable Sphere Fluid

A bridge function approximation is proposed for a single-component fluid consisting of penetrable sphere interacting via a potential that remains finite and constant for center-center distance smaller than the particle diameter and is zero otherwise. The radial distribution function from the Ornstein-Zernike integral equation combined with the present bridge function approximation is in satisfactory agreement with the corresponding simulation data for all of the investigated state points. The presently calculated excess Helmholtz free energy respectively based on virial route and compressibility route is highly self-consistent, and is in very good agreement with simulational results for the case of low temperatures. The present bridge function approximation, combined with the bridge density functional approximation, can reproduce very accurately density profiles of the penetrable sphere fluid confined in a hard spherical cavity for all the cases where simulational results are available.

Augmented Kierlik-Rosinberg Fundamental Measure Functional and Extension of Fundamental Measure Functional to Inhomogeneous Non-hard Sphere Fluids

From point of view of weighted density procedure, it is guessed that a Percus-Yevick （PY） compressibility excess free energy density, appearing in the Kierlik Rosinberg type fundamental measure functional （KR-FMF） and expressed in terms of scaled particle variables, can be substituted by a corresponding expression dictated by a more accurate Mansoori Carnahan-Starling Leland （MCSL） equation of state, while retaining the original weighting functions; it is numerically indicated that the resultant undesirable non-self-consistency between the PY type weighting function and MCSL type excess free energy density had no bad effect on the performance of the resultant augmented KR-ffMF which, on the one hand, preserves the exact low-density limit of the original KR-FMF and holds a high degree of pressure self-consistency, on the other hand, improves significantly, as expected, the predictions of density profile of hard sphere fluid at single hard wall contact location and its vicinity, and of the bulk hard sphere second order direct correlation function （DCF）, obtained from functional differentiation. The FMF is made applicable to inhomogeneous non-hard sphere fluids by supplementing a functional perturbation expansion approximation truncated at the lowest order with summation of higher order terms beyond the lowest term calculated by the FMF for an effective hard sphere fluid; the resultant extended FMF only needs second order DCF and pressure of the fluid considered at coexistence state as inputs, consequently is applicable whether the considered temperature is above critical point or below critical point. The extended MCSL-augmented KR-FMF is found to be endowed with an excellent performance for predictions of density profile and surface tension by comparing the present predictions of these two quantities with available computer simulation data for inhomogeneous hard core attractive Yukawa fluid and Lennard-3ones fluid.

基本三维几何体的最高填充率

数值模拟结果表明,基本三维几何体随机填充的填充率上限从高到底依次为:立方体(0.78)、椭球(0.74)、圆柱(0.72)、球柱体(spherocylinder,0.69)、四面体(0.68)、圆锥(0.67)、球体(0.64),而规则填充的填充率上限依次为:立方体(1.0)、圆柱和球柱体(0.9069)、圆锥(0.7854)、椭球(0.7707)、球体(0.7405)、正四面体(0.7175),这两种填充率排序的顺序并不相同.椭球、圆柱、球柱体、四面体和圆锥的随机填充率均与其形状有关,它们达到最高填充率时的形状参数分别为:椭球(三轴比为0.8:1:1.25)、圆柱(高度/直径=0.9)、球柱体(圆柱段高度/直径=0.35)、四面体(正四面体)和圆锥(高度/底面直径=0.8).

On the some issues of particle motion in the flow of viscoelastic fluids

Particle motion in confined shear flow of viscoelastic fluids is very common in nature and has a wide range of applications.Understanding and mastering the motion characteristics of particles in viscoelastic fluids has important academic value and practical significance.In this paper,we first introduce the related equations and characteristic parameter,and then emphasize the following issues:the lateral equilibrium position of particle;interaction and aggregation of multiple particles;the chain structure formed by multiple particles;and the motion of non-spherical particle.Finally,some unresolved issues,challenges,and future research directions are highlighted.