1,720,983 research outputs found
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
Variations 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
INVESTIGATION OF INDENTATION FRACTURE TOUGHNESS (K-IC) AND WEIBULL PARAMETERS OF 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) GLASS-CERAMIC
No full textIn the present study, mechanical properties of 0.25Li(2)O.2SiO(2)-0.75BaO.2SiO(2) glass-ceramic were investigated. The transformations temperatures were determined by DTA instrument. The optimum nucleation temperature was found to be 540 degrees C. This suggested the crystallization temperatures as 675, 720 and 800 degrees C. After carrying out crystallization heat treatments, Vickers indentation test was applied. In order to determine the indentation fracture toughness (KIC), crack half-length, 'c' of the samples was measured. To calculate KIC, Young's modulus, E and the measured hardness, Hv were used. Using KIC and probability of fracture, 'P', ln ln[1/(1-P)]-ln KIC graph was drawn based on the Weibull distribution equation. Consequently, Weibull modulus,, m` and scale parameter, 'K-0' were determined and compared with each other
Mechanochemical synthesis and characterisation of niobium silicide nanoparticles
No full textMechanochemical synthesis (MCS) investigations of niobium silicide powders in Nb2O5-SiO2-Mg powder mixtures were conducted via high-energy ball milling and leaching by means of process parameters such as the milling duration, initial Nb2O5 crystal structure, and excess Mg amount. The compositional, thermal, and microstructural properties of the products were characterised using X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), particle size analysis (PSA), stereomicroscopy (SM), scanning electron microscopy (SEM), and transmission electron microscopy/energy-dispersive spectrometry (TEM/EDS). After the 5 h milling of the stoichiometric mixtures, an instantaneous ignition occurred and NbSi2, Nb5Si3, Nb, and MgO phases formed with some residual Mg. In addition, the use of excess Mg inhibited the formation of Nb5Si3. Afterwards, leaching treatments (in a 4 M HCl solution) completely removed the Mg-based phases from the synthesised products. The XRD calculations revealed that the resultant product consisted of 97 wt% NbSi2 and 3 wt% Nb5Si3 phases. The TEM analyses indicated that each Nb silicide nanoparticle was coated with a SiO2 layer. According to random measurements, the average particle size of the Nb silicide cores and average thickness of the SiO2 layer were approximately 61 and 7.5 nm, respectively
Room-temperature synthesis of tungsten silicide powders using various initial systems
No full textThe present study investigated the synthesis of tungsten silicide powders using ternary (WO3-Si-Mg and W-SiO2 Mg) and binary (W-Si) initial systems at room temperature via mechanochemical synthesis (MCS) and mechanical alloying (MA) processes. Milling time was used as a process parameter. Subsequently, undesired Mg-based phases were leached out using aqueous HCl solution. Compositional analyses of powders were conducted by using an X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FTIR). Microstructural observations of powders were performed by utilizing particle size analyzer (PSA), scanning (SEM) and transmission electron microscopes (TEM). Also, differential scanning calorimetry (DSC) analyses were carried out for the synthesized powders. While the reaction for tungsten silicide formation took place by MCS in WO3-Si-Mg system after 1 min and by MA in W-Si system after 15 h, it did not occur in W-SiO2-Mg system even after 15 h milling. WSi2, W5Si3 and W phases were found in WO3-Si-Mg system whereas only WSi2 formed in W-Si system. The ternary WO3-Si-Mg system resulted in SiO2 coated nanoparticles owning a mean size of 203 nm. WSi2 submicron particles with an average size of 688 nm were obtained in binary W-Si system. The experimental results showed a good consistency with the reaction mechanisms predicted by FactSage thermodynamic calculations
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Fabrication of TiC and ZrC reinforced Al-4 wt% Cu composite droplets using impulse atomization
No full textIn this study, Al-4 wt% Cu alloy and its composites reinforced with different initial particle sizes of ZrC (8 mu m and 157 mu m) and TiC (13 mu m and 93 mu m) were fabricated by impulse atomization, and the microstructure of composite and unreinforced alloy droplets were examined by scanning electron microscopy, x-ray diffraction and cell size analyses. Scanning electron microscopic observations of composite droplets indicated that fine ZrC particles (8 mu m) were mostly clustered while the other composites of the present investigation were distributed rather uniformly within the fine microstructure of droplets. The relationship between the cell size and the amount of carbide particles reveals that the presence of carbide particles in the alloy powders yields a finer structure. This could be due to the role of the carbide particles as heterogeneous sites for nucleation and to some extent due to particle restricted growth of matrix cells during solidification
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