Numerical investigation on Rayleigh-Bénard-Marangoni flow of water near the maximum density in cylindrical pools with large aspect ratios

We report a set of direct numerical simulation results on Rayleigh-Bénard-Marangoni (R-B-M) flow of cold water in the cylindrical pools. The heat transfer between the free surface and the environment is considered. The aspect ratio Г of the cylindrical pool varies from 2 to 8. Rayleigh (Ra) and Biot (Bi) numbers are respectively confined in Ra ≤ 10⁴ and 0 < Bi ≤ 50. The flow onset critical Ra is determined and the influences of Bi and the density inversion parameter (Θ_m) on the critical Ra are analyzed. The primary bifurcation flow structures of R-B-M flow are shown and the evolution of the flow structures with Ra and Bi at different Θ_m is observed. Furthermore, the heat transfer ability is estimated by Nusselt number. The results indicate that the critical Ra of the flow onset increases with increasing Bi and Θ_m. But it decreases with the increase of Г. The primary bifurcation pattern is multicellular flow. With increasing Г, the number of flow cells in multicellular flow increases fast. With increasing Ra, the up-triangular and up-quadrilateral flow structures appear at Г = 4, and finally transits to the up one-torus. With increasing Ra and Г, and decreasing Θ_m, average Nusselt number increases monotonically. However, with increasing Bi, it first increases, and then decreases.

     

基于核的PP主成分分析及其在离群聚类中的应用

为了提高高维数据集合离群数据挖掘效率,在分析了传统的离群数据挖掘算法优点和缺点的基础上,提出了一种离群聚类算法,该算法将核方法与PP主成分变换结合于离群聚类算法中,采用基于核的PP主成分变换进行数据维数消减。通过该数据变换矩阵得到相应的非线性向量,并为每个向量分配一个动态权值,在优化经典的FCM模糊聚类的目标优化迭代函数基础上,最终得到各个数据的权值,根据权值的大小标识出数据集中的离群点,理论上证明了该算法的收敛性,仿真实验的结果表明了该方法能够有效地发现高维数据集中的离群点。     

一种有效的蛋白质序列聚类分析方法

提出了一种有效的基于仿射传播聚类算法和后处理方法的蛋白质序列聚类方法.在聚类分析蛋白质序列时,为了优化仿射传播聚类算法的聚类结果,采用后处理的方式来提高聚类结果的质量.为了度量蛋白质序列之间的相似度,给出了一种改进的无比对计算方法.在6个蛋白质序列数据集上进行对比实验,实验结果表明,所给出的方法能够有效地分析蛋白质序列.     

面向Agent的软件分析和设计方法

在复杂系统的分析、设计、开发过程中,面向Agent的方法在映射现实世界,模拟人认识问题、解决问题的过程等方面具有优势。从描述Agent的概念、分类和体系结构出发,对面向对象和面向Agent的分析设计方法进行了比较．讨论了面向Agent的分析模型及各模型的组成部分,以及面向Agent的分析模型到设计模型的转换,并指出面向Agent的分析设计方法提供了在建模、设计和实现不同级别上复用的基础。以政府公共行政服务系统为例对上述方法进行实例分析。最后得出面向Agent的软件分析和设计将为复杂系统提供新的解决思路的结论．同时指出本文提出的面向Agent的分析和设计方法的优点以及所面临的问题。     

PowerRTF: Power Diagram based Restricted Tangent Face for Surface Remeshing

Triangular meshes of superior quality are important for geometric processing in practical applications. Existing approximative CVT-based remeshing methodology uses planar polygonal facets to fit the original surface, simplifying the computational complexity. However, they usually do not consider surface curvature. Topological errors and outliers can also occur in the close sheet surface remeshing, resulting in wrong meshes. With this regard, we present a novel method named PowerRTF, an extension of the restricted tangent face (RTF) in conjunction with the power diagram, to better approximate the original surface with curvature adaption. The idea is to introduce a weight property to each sample point and compute the power diagram on the tangent face to produce area-controlled polygonal facets. Based on this, we impose the variable-capacity constraint and centroid constraint to the PowerRTF, providing the trade-off between mesh quality and computational efficiency. Moreover, we apply a normal verification-based inverse side point culling method to address the topological errors and outliers in close sheet surface remeshing. Our method independently computes and optimizes the PowerRTF per sample point, which is efficiently implemented in parallel on the GPU. Experimental results demonstrate the effectiveness, flexibility, and efficiency of our method.     

钻井液pH值的影响因素研究

讨论了各种因素引起钻井液pH值降低的原因并研究了滚动老化后放置时间、老化温度及含盐量的影响。参考胜利油田聚合物钻井液配方,由6%膨润土浆与多种处理剂配成实验淡水钻井液。pH值12.87的淡水钻井液在150℃老化16小时后,pH值随时间而降低,46小时降至10.01。在不同温度下（80-150℃）老化16小时后,该钻井液的pH值在前15小时内下降较快,此后下降缓慢,老化温度越高,pH值下降越快,降幅越大。在该钻井液中加入活性再生盐配成的盐水钻井液,150℃老化后pH值下降的幅度随含盐量增大（1%-35%）而增大。表面活性剂对150℃老化后饱和盐水（35%NaCl）钻井液pH值降低的影响程度因类型而不同,加量0.1%-0.5%时稳定该钻井液pH值的作用,阳离子型的CTMAB基本上无,阴离子型的AS和ABS很微弱,非离子型的Tween-80、OP-10、Span-80稍好,ABS/OP-10和OP-10/Span-80复配物更好,但稳定作用均不够强,老化后该钻井液的pH值一般均低于10.0。图4表4参6。     

Carrier Transport Regulation of Pixel Graphene Transparent Electrodes for Active-Matrix Organic Light-Emitting Diode Display

Integrating a graphene transparent electrode (TE) matrix with driving circuits is essential for the practical use of graphene in optoelectronics such as active-matrix organic light-emitting diode (OLED) display, however it is disabled by the transport of carriers between graphene pixels after deposition of a semiconductor functional layer caused by the atomic thickness of graphene. Here, the carrier transport regulation of a graphene TE matrix by using an insulating polyethyleneimine (PEIE) layer is reported. The PEIE forms an ultrathin uniform film (≤10 nm) to fill the gap of the graphene matrix, blocking horizontal electron transport between graphene pixels. Meanwhile, it can reduce the work function of graphene, improving the vertical electron injection through electron tunneling. This enables the fabrication of inverted OLED pixels with record high current and power efficiencies of 90.7 cd A⁻¹ and 89.1 lm W⁻¹, respectively. By integrating these inverted OLED pixels with a carbon nanotube-based thin-film transistor (CNT-TFT)-driven circuit, an inch-size flexible active-matrix OLED display is demonstrated, in which all OLED pixels are independently controlled by CNT-TFTs. This research paves a way for the application of graphene-like atomically thin TE pixels in flexible optoelectronics such as displays, smart wearables, and free-form surface lighting.