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981.
Mahashweta Das Saravanan Thirumuruganathan Sihem Amer-Yahia Gautam Das Cong Yu 《The VLDB Journal The International Journal on Very Large Data Bases》2014,23(2):201-226
The rise of Web 2.0 is signaled by sites such as Flickr, del.icio.us, and YouTube, and social tagging is essential to their success. A typical tagging action involves three components, user, item (e.g., photos in Flickr), and tags (i.e., words or phrases). Analyzing how tags are assigned by certain users to certain items has important implications in helping users search for desired information. In this paper, we develop a dual mining framework to explore tagging behavior. This framework is centered around two opposing measures, similarity and diversity, applied to one or more tagging components, and therefore enables a wide range of analysis scenarios such as characterizing similar users tagging diverse items with similar tags or diverse users tagging similar items with diverse tags. By adopting different concrete measures for similarity and diversity in the framework, we show that a wide range of concrete analysis problems can be defined and they are NP-Complete in general. We design four sets of efficient algorithms for solving many of those problems and demonstrate, through comprehensive experiments over real data, that our algorithms significantly out-perform the exact brute-force approach without compromising analysis result quality. 相似文献
982.
V. G. Borisov Yu. S. Rodgol'ts O. P. Kononchuk K. V. Simonov O. V. Filonov A. L. Nesterova E. F. Vit' 《Refractories and Industrial Ceramics》1971,12(7-8):492-495
Conclusions Satkinsk dolomitic magnesite fired in a rotary kiln using a cycle employed for Styl'sk dolomite can be used to obtain sintered powder with an apparent density 3.15 g/cm3.Compared with the currently produced tarred dolomite-magnesite refractories, the tar-bonded converter refractories made on the basis of powder produced from dolomitic magnesite are characterized by higher densities, strength, and resistance to hydration.Thus, Satkinsk dolomitic magnesite which is hardly used at the present time is a promising raw material for producing converter refractories.Translated from Ogneupory, No. 8, pp. 15–20, August, 1971. 相似文献
983.
To study the effect of the molecular architecture of a copolymer on its miscibility with corresponding homopolymers a series of block copolymers of styrene and isoprene with diblock, triblock and four-arm star architectures have been prepared and the morphologies of the blends of the copolymers and polyisoprene with different molecular weights have been examined by electron microscopy. The results show that miscibility varies in the sequence diblock>triblock>four-arm star copolymers. This sequence is in the opposite direction to the variation of the architectural complexity of the block copolymers, i.e. the more complex is molecular architecture, the greater is conformation restriction in microdomain formation and the less is solubility of homopolymer in corresponding domains. 相似文献
984.
Microcellular foaming of biodegradable Bionolle in supercritical CO2 has been produced. The effects of a series of variable factors, such as saturation temperature, saturation pressure, and depressurization time and step on the foam structures and density, were studied through measurement of density and SEM observation. The experimental results show that higher saturation temperatures lead to an increase in bulk densities; and different depressurization time and step result in different product cell morphology. In addition, at some saturation temperature, the orientation of the cells can be found in the product morphology. XRD experimental results show that the foaming treatment with SC CO2 increased the crystallinity of Bionolle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2901–2906, 2006 相似文献
985.
Daniela M. Bonafede Lawrence J. Macala Martha Costantine-Paton Robert K. Yu 《Lipids》1989,24(8):680-684
Bovine buttermilk contains a unique ganglioside, 9-O-acetyl-GD3. In order to isolate large quantities of this ganglioside, a simplified isolation scheme which consists of several ion-exchange
and silica gel column chromatographic procedures was devised. The isolated 9-O-acetyl-GD3 was characterized on the basis of its thin-layer chromatographic behavior, its immunoreactivity with a specific monoclonal
antibody, JONES, and by conversion to authentic GD3 by mild base treatment. 相似文献
986.
987.
988.
超几何分布是一种重要的离散型概率分布,本文利用反证法以及比较法求出了三维超几何分布的最可能成功次数,并在此基础上,求出了多维超几何分布的最可能成功次数. 相似文献
989.
虚拟仪器的测量过程控制是保证测量数据有效的重要手段,利用灰色系统GM(1,1)模型对虚拟仪器的测量过程进行控制,由少量数据信息得到未来的预期测量结果,通过与核查标准的测量结果相比较来判别测量过程是否受控.论文给出了测量过程控制判别限、适用灰色系统GM(1,1)模型的条件以及模型精度检验判据. 相似文献
990.
陈彧 《湖北工业大学学报》2009,24(6):122-123,133
以中介作用理论为依据,以费厄斯坦所划分的教师中介作用的十二项特征为指导,探讨在现代信息技术辅助下大学英语教师如何从学习兴趣、学习动机、学习策略、自我控制等方面介入学生的英语学习,从而使学生成为真正的自主学习者. 相似文献