1,721,110 research outputs found
Synthesis and characterization of novel conductive star polymers containing PSS/PANI arms
No full textApplication of deep learning method to Reynolds stress models of channel flow based on reduced-order modeling of DNS data
No full textRecently, the methodology of deep learning is used to improve the calculation accuracy of the Reynolds-averaged Navier-Stokes (RANS) model. In this paper, a neural network is designed to predict the Reynolds stress of a channel flow of different Reynolds numbers. The rationality and the high efficiency of the neural network is validated by comparing with the results of the direct numerical simulation (DNS To further enhance the prediction accuracy, three methods are developed by using several algorithms and simplified models in the neural network. In the method 1, the regularization is introduced and it is found that the oscillation and the overfitting of the results are effectively prevented. In the method 2, y(+) is embedded in the input variable while the combination of the invariants is simplified in the method 3. From the predicted results, it can be seen that by using the first two methods, the errors are reduced. Moreover, the method 3 shows considerable advantages in the DNS trend and the smoothness of a curve. Consequently, it is concluded that the DNNs can predict effectively the anisotropic Reynolds stress and is a promising technique of the computational fluid dynamics.</p
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
Investigations into the ventilated cavities around a surface-piercing hydrofoil at high Froude numbers
No full textThis study investigates the ventilated cavities around a surface-piercing hydrofoil, aiming to extend previous studies by an in-depth understanding of the vaporous cavity behaviors and the flow-regime transition at high Froude numbers. An experiment is carried out in a constrained-launching water tank with a vertically cantilevered hydrofoil piercing a still water surface. The cavity is recorded using high-speed photography, and flow-regime maps are summarized over a broad range of Froude number and yaw angle at different immersed aspect ratios. In addition to the well-known steady flow regimes (i.e., fully wetted flow and fully ventilated flow), an unsteady vaporous cavitating flow is revealed at a very high Froude number with a small yaw angle, which exhibits cavitation shedding dynamics behaviors, including the cavity growth, destabilization, and collapse. The transition from the fully wetted flow to the fully ventilated flow is attributed to the vapor-cavitation-induced ventilation besides the tip-vortex-induced ventilation. Vaporous cavitation promotes ventilation formation, but it has to meet the criterion that air should enter the sub-atmospheric cavity through the tip-vortex path before the cavity length reaches the maximum. Moreover, an improved lifting-line model is developed with considering the effects of free surface and finite aspect ratio. Both analytical modeling and experimental measurements reveal that the vaporous cavity length follows a power relation against the cavitation parameter. Such knowledge lays a foundation for the design optimization and control strategy of high-speed hydrofoils
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
The mechanism of surface-seal splash during water entry
No full textWhen a solid body impacts quiescent water at a certain velocity, the resultant surface-seal splash deforms and closes above the free surface. This study investigates the dynamics of the surface-seal splash by using a high-speed camera and particle image velocimetry (PIV) measurements. Based on PIV, an analytical model is developed to understand the mechanics of the surface-seal splash. The results indicate that the theoretical splash shapes are consistent with the experimental results. In addition, the effects of gravity, drag, surface tension, and aerodynamic pressure on the dynamics of surface-seal splash are also assessed, and the results indicate that the aerodynamic pressure plays a dominant role in the formation of the surface-seal splash.</p
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