Multiple factor hierarchical clustering algorithm for?large scale web page and search engine clickstream data

The developments in World Wide Web and the advances in digital data collection and storage technologies during the last two decades allow companies and organizations to store and share huge amounts of electronic documents. It is hard and inefficient to manually organize, analyze and present these documents. Search engine helps users to find relevant information by present a list of web pages in response to queries. How to assist users to find the most relevant web pages from vast text collections efficiently is a big challenge. The purpose of this study is to propose a hierarchical clustering method that combines multiple factors to identify clusters of web pages that can satisfy users?? information needs. The clusters are primarily envisioned to be used for search and navigation and potentially for some form of visualization as well. An experiment on Clickstream data from a processional search engine was conducted to examine the results shown that the clustering method is effective and efficient, in terms of both objective and subjective measures.     

Nd: YAG激光烧蚀裂解加工技术模拟分析与实验研究

激光裂解技术能够极大改善发动机缸体主轴承座的加工质量并显著提高加工效率. 为探寻Nd:YAG激光烧蚀球墨铸铁材料裂解槽的裂解性能, 本文基于有限元法成功构建了发动机缸体主轴承座激光裂解加工过程仿真模型, 针对QT500-7球墨铸铁主轴承座的裂解参数进行了仿真分析. 研究结果表明: 在影响裂解质量的三个裂解槽几何参数中, 槽深较张角及曲率半径对裂解载荷的影响效应更为明显; 裂解载荷随槽深的增加而迅速降低, 随槽张角和曲率半径的增加而升高; QT500-7球墨铸铁发动机缸体主轴承座激光裂解加工优化参数应为裂解槽深选为0.5 mm, 裂解槽张角选为60^o, 裂解槽半径选为0.2 mm. 有限元模拟分析结果得到了单向拉伸实验结果的验证. 本工作通过ABAQUS仿真模拟及大量裂解载荷试验确立了裂解槽几何形状的优化参数, 为显著降低裂解载荷和优化裂解工艺提供了数值参考, 有利于实现发动机缸体加工的快速发展, 从而促进汽车工业实现绿色制造.     

Semilocal Convergence of a Class of Modified Super-Halley Methods in Banach Spaces

In this paper, we consider the semilocal convergence of a class of modified super-Halley methods for solving nonlinear equations in Banach spaces. The semilocal convergence of this class of methods is established by using recurrence relations. We construct a system of recurrence relations for the methods, and based on it, we prove an existence–uniqueness theorem that shows the R-order of the methods.     

Controllable transport of water through nanochannel by rachet-like mechanism

By using molecular dynamics simulation, we have investigated systematically the feasibility of continuous unidirectional water flux across a deformed single-walled carbon nanotube (SWNT) driven by an oscillating charge outside without osmotic pressure or hydrostatic drop. Simulation results indicate that the flux is dependent sensitively on the oscillating frequency of the charge, the distance of the charge from the SWNT, and the asymmetry of the water-SWNT system. A resonance-like phenomenon is found that the water flux is enhanced significantly when the period of the oscillation is close to twice the average hopping time of water molecules inside the SWNT. These findings are helpful in developing a novel design of efficient functional nanofluidic devices.     

Synthesis,Characterization, DNA‐binding Properties,and ­Antioxidant Activity of a Copper(II) Complex with 1, 3‐Bis­(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane

A new complex of copper(II) picrate (pic) with 1, 3‐bis(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane (aobb), with the composition [Cu(aobb)₂](pic)₂, was synthesized and characterized. The crystal structure of the copper(II) complex revealed that the coordination environment around the central copper(II) atom is a distorted octahedral arrangement. Electronic absorption spectroscopy, ethidium bromide displacement experiments and viscosity measurements indicate that the ligand and the Cu^II complex can strongly bind to calf thymus DNA, presumably by an intercalation mechanism. Furthermore, the antioxidant activity of the Cu^II complex was determined by superoxide and hydroxyl radical scavenging method in vitro, which indicate that the Cu^II complex has the activity to suppress OH ^· and O₂ ^{· –}.     

Hybrid theoretical,experimental and numerical study of vibration and buckling of composite shells with scatter in elastic moduli

Hybrid theoretical, experimental and numerical method is proposed for free vibration and buckling of composite shell with unavoidable scatter in elastic moduli. Based on the Goggin’s measurement techniques, the elastic moduli for material T300-QY8911 are measured, and a set of experimental points are obtained. The measurements of elastic moduli are quantified by either (1) the smallest ellipsoid and (2) the smallest four-dimensional uncertainty hyper-rectangle. Then uncertainty propagation in vibration and buckling problems of composite shell by ellipsoidal analysis and interval analysis are, respectively, studied from the theoretical standpoint. Comparison between these analyses is performed numerically.     

PARISI-SOURLAS CONFINEMENT MECHANISM OF QUANTUM CHROMODYNAMICS

Using Parisi and Sourlas dimensional reduction, four-dimensional quantum chromodynamics is reduced to a two-dimensional principal chiral model by suitable superspace embedding. The frame T^a cannot be regarded as a fixed one and the frame connection field \varω_μ(x) becomes a dynamical gauge field in two dimensions, giving rise to a confining potential. As a result of the original SU(3) Yang-Mills field obtains another SU(3) local symmetry and turns into SU(3)×SU(3) local symmetry－one group element as exp (iδ\varphi^aT^a) with fixed frame T^a, the other gauging the frame T^a.     

镶嵌型乳胶粒子的合成

以苯乙烯、甲基丙烯酸甲酯、丙烯腈等单体或它们的混合物为硬单体,天然胶乳为弹性组分,经多步种子乳液聚合法制得了在天然胶乳的粒子上镶嵌硬聚合物相的互穿网络型乳胶粒子.考察了十二烷基硫酸钠、十二烷基苯磺酸钠、壬基酚聚氧乙烯醚、油酸等乳化体系,过硫酸钾、过氧化苯甲酰热引发体系及异丙苯过氧化氢-四乙烯五胺、叔丁基过氧化氢-四乙烯五胺等氧化还原引发体系对聚合反应的影响.研究了交联剂用量对互穿结合率、溶胶含量的影响及溶胀时间、硬单体组成、乳化剂种类对乳胶粒子形态的影响,确定了适宜的聚合配方和工艺条件.透射电镜观察乳粒形态结果表明,单一使用极性或非极性单体,仅得到核-壳结构乳液,而采用不同极性单体复合、溶胀、互穿,得到的是镶嵌硬聚合物型乳粒结构.     

对甲苯磺酸正丁铵毛细管色谱柱的制备及性能考察

用动态涂敷法制备了对甲苯磺酸正丁铵玻璃毛细管柱柱１（固定液浓度为７．５％,柱尺寸为３５ｍ×０．３５ｍｍｉ．ｄ．）和柱２（固定液浓度为９．２％,柱尺寸为３５ｍ×０．３０ｍｍｉ．ｄ．）,所用溶剂是丙酮和甲醇（２：１Ｖ／Ｖ）的混合溶剂,并对柱性能进行了考察。结果表明,这种色谱固定相具有较强的极性并对饱和烃、芳香烃、饱和酸、芳香酸、极性异构体等具有良好的分离效果。     

ZrO_2、TiO_2担载氧化铁催化剂上二氧化碳加氢制低碳烃(英文)

采用创新方法制备的ZrO2、TiO2担载氧化铁催化剂在二氧化碳加氢制低碳烃反应中显示出良好的催化活性和产物选择性,由15wt?/ZrO2给出的最佳结果为：CO2转化率为20%,除甲烷以外的低碳烃的选择性接近70%。还考察了金属Fe担载量及催化剂的预还原温度对催化活性的影响,发现催化活性随金属Fe担载量的增加而呈现“双峰”现象,这种现象可能与活性物种(零价铁及配位不饱和的三价或二价铁)在催化剂表面的几何排布有关,而两种催化剂的最佳还原温度分别为723 K(5wt?/ZrO2)和773 K(5wt?/TiO2)。