1,721,111 research outputs found
A comparison of collocation-based similarity measures in query expansion
No full textIn this paper, we present a comparison of collocation-based similarity measures: Jaccard, Dice and Cosine similarity measures for the proper selection of additional search terms in query expansion. In addition, we consider two more similarity measures. average conditional probability (ACP) and normalized mutual information (NMI). ACP is the mean value of two conditional probabilities between a query term and an additional search term. NMI is a normalized value of the two terms' mutual information, All these similarity measures are the functions of any two terms' frequencies and the collocation frequency, but are different in the methods of measurement. The selected measure changes the order of additional search terms and their weights, hence has a strong influence on the retrieval performance. In our experiments of query expansion using these five similarity measures, the additional search terms of Jaccard, Dice and Cosine similarity measures include more frequent terms with lower similarity values than ACP or NMI. In overall assessments of query expansion, the Jaccard, Dice and Cosine similarity measures are better than ACP and NMI in terms of retrieval effectiveness, whereas, NMI and ACP are better in terms of execution efficiency. (C) 1999 Elsevier Science Ltd. All rights reserved
A computational method for probabilistic safety assessment of I&C systems and human operators in nuclear power plants
No full textTo make probabilistic safety assessment (PSA) more realistic, the improvements of human reliability analysis (HRA) are essential. But, current HRA methods have many limitations including the lack of considerations on the interdependency between instrumentation and control (I&C) systems and human operators, and lack of theoretical basis for situation assessment of human operators. To overcome these limitations, we propose a new method for the quantitative safety assessment of I&C systems and human operators. The proposed method is developed based on the computational models for the knowledge-driven monitoring and the situation assessment of human operators, with the consideration of the interdependency between I&C systems and human operators. The application of the proposed method to an example situation demonstrates that the quantitative description by the proposed method for a probable scenario well matches with the qualitative description of the scenario. It is also demonstrated that the proposed method can probabilistically consider all possible scenarios and the proposed method can be used to quantitatively evaluate the effects of various context factor on the safety of nuclear power plants. In our opinion, the proposed method can be used as the basis for the development of advanced HRA methods. (c) 2005 Published by Elsevier Ltd
Change of atomization performance with selection of nozzle materials in electrohydrodynamic spraying
No full textIn the present study, a series of experiments has been conducted for proper selection of nozzle materials to generate fine liquid (water) drops ranging between 30 and 450 mum through the electroydroynamic atomization process. The spindle mode was the primary drop-generation mode considered in this experimental work. Three nozzles made of different materials were prepared and tested: a stainless steel tube, and plain and metal (gold)-coated (except for the tip portion) silica tubes. The drop size distribution changed with the electrical conductivity and the surface wettability of the tubes, as well as with other parameters such as the liquid flow rate and the capillary tube voltage. Among these nozzles, the metal-coated silica tube showed the best performance in generating uniform, fine drops over a wide range of tube voltage because the pivoting motion and the sporadic corona could be suppressed
An analytic model for situation assessment of nuclear power plant operators based on Bayesian inference
No full textSimulation-based human reliability analysis (HRA) methods such as IDAC seem to provide a new direction for the development of advanced HRA methods. In such simulation-based HRA methods, the simulation model for the situation assessment of nuclear power plant (NPP) operators is essential, especially for addressing the issue of errors-of-commission (EOCs). Therefore, we propose an analytic model for the situation assessment of NPP operators based on Bayesian inference. The proposed model is found to be able to address several important features of the situation assessment of NPP operators, and is expected to provide good approximations to some parts of the situation assessment. A comparison with an existing model and identification of several other features of the situation assessment of NPP operators that should be further addressed are also provided. (c) 2005 Elsevier Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Chracterization of Electrohydrodynamic Atomization of Slaked-lime/Water Slurry Discharged from a Capillary Nozzle
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effect of the intercalation of the carbon layer on the kinetics of grain growth of FePt magnetic thin film during ordering reaction - A Monte Carlo simulation study
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