1,724,933 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
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
Parametric study of detonation initiation using a hot jet in supersonic combustible mixtures
No full textThe effects of various flow or geometry parameters on detonation initiation in supersonic combustible mixtures using a hot jet were investigated, including the free stream Mach number Ma?, the hot jet Mach number Maj, the free stream pressure P?, the hot jet pressure Pj, the diameter of the hot jet Dj, and the height of the free stream channel Hc. The results show that there exists a free stream Mach number range (Ma?min, Ma?max) for the successful initiation. When Ma? is beyond that range, the hot jet is not able to initiate the detonation and the flow field maintains a stable shock wave or shock reflection induced by the hot jet. For the other parameters, including the hot jet Mach number, the free stream pressure, the hot jet pressure, the diameter of the hot jet, and the height of the free stream channel Hc, there exists a critical value for the detonation initiation. For the hot jet Mach number Maj, the hot jet pressure Pj, the diameter of the hot jet Dj, when they are larger than the critical values, the initiation can be realized eventually and the larger the parameters the faster the initiation. Otherwise, the flow field will maintain the final stable state as the shock wave or shock reflection. For the free stream pressure P? and the height of the free stream channel Hc, when they are larger than the critical values, the flow field will also maintain the final stable state. Otherwise, the detonation initiation can be realized eventually and the smaller the parameters the faster the initiation
RANKINGS IN DIRECTED CONFIGURATION MODELS WITH HEAVY TAILED IN-DEGREES
No full textWe consider the extremal values of the stationary distribution of sparse directed random graphs with given degree sequences and their relation to the extremal values of the in-degree sequence. The graphs are generated by the directed configuration model. Under the assumption of bounded (2 + eta)moments on the in-degrees and of bounded out-degrees, we obtain tight comparisons between the maximum value of the stationary distribution and the maximum in-degree. Under the further assumption that the order statistics of the in-degrees have a power-law behavior, we show that the extremal values of the stationary distribution also have a power-law behavior with the same index. In the same setting, we prove that these results extend to the PageRank scores of the random digraph, thus confirming a version of the socalled power-law hypothesis. Along the way we establish several facts about the model, including the mixing time cutoff and the characterization of the typical values of the stationary distribution, which were previously obtained under the assumption of bounded in-degrees
Segmentation of ultrasound image sequences by combing a novel deep siamese network with a deformable contour model
No full textDeformable contours are widely applied in medical image segmentation, which are usually derived from appearance cues in medical images. However, the performance of deformed contour is suppressed in ultrasonic image segmentation by the weak, misleading boundaries and the complex shapes of lesion regions. In this paper, a novel deformable contour model is proposed for segmenting ultrasound image sequences, which aims to utilize the powerful ability of deep learning network in learning of image features to help the deformable contour model resist weaknessses of ultrasound images. The deep learning network is designed as a densely connected siamese architecture. It trains a contrastive loss that serves as a boundary searching metric of a deformable contour to segment ultrasound image sequences. In this network, the densely residual blocks and the attention focused blocks are designed to make the network efficiently propagate features and focus on the lesion region, and the feature memory module stores and generates the prior features to aid the evolution of a deformable contour. Moreover, for resisting the impact of misleading or weak boundary, the shape similarity of lesion regions is used to as a shape prior and integrated into the framework of deformable contour to constrain the change of contours. The experimental results for the clinical ultrasound image sequences demonstrate that compared to the state-of-the-art methods, the proposed method can provide more accurate results in HIFU ultrasound images
Coordinated effect of microstructure and defect on fatigue accumulation in dual-phase Ti-6Al-4V: Quantitative characterization
No full textFatigue accumulation in dual-phase Ti-6Al-4V is strongly associated with the combined effects of microstructure and defects in itself, which is experimentally challenging to be characterized and quantified. Based on crystal plasticity finite element method (CPFEM), the present work aims to address the coordinated effect of microstructure and defect on fatigue behavior in Ti-6Al-4V, highlighting the influence of morphology and orientation of defects, in conjunction with the designated idealized microstructure. In light of these considerations, a modelling strategy is proposed to focus on defect morphology and orientation in polycrystalline RVE models. Firstly, the geometric roundness parameter is adopted to characterize the diverse defect morphology and is quantitatively correlated with the characteristic of fatigue accumulation in Ti-6Al-4V. Secondly, a liner relationship with respect to corner angle and plastic deformation is formulated to characterize the influence of defect orientation, reflecting the microstructural heterogeneity in dual-phase Ti-6Al-4V. The proposed modelling strategy overcomes the experimental limitation on characterizing the complex effect of microstructure and defect, holding the potential of revealing fatigue mechanism around defects in metal alloys
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