1,721,569 research outputs found
Uncertainty-Based Comprehensive Optimization Design for the Thermal Protection System of Hypersonic Wing Structure
No full textDue to the inherent uncertainties in material properties, loads, geometric dimensions, et al., the uncertainty-based optimization design method has become increasingly important for the design of the thermal protection system (TPS) by carefully considering the influences of uncertainties. In this study, an uncertainty-based comprehensive optimization design method, which sequentially performs the robust design of aerodynamic shape and structure size for the TPS of a hypersonic wing is proposed, on the presence of uncertain-but-bounded parameters. The robust design of the TPS's aerodynamic shape is firstly carried out. The results show that the proposed method decreases the fluctuation of the lift-to-drag ratio by 5.7%, with a small increase of heat flux on the stagnation point by only 0.13% when compared with the conventional deterministic optimization method. After that, based on the optimized aerodynamic shape and heating loads, the robust design of the multilayer TPS tile is conducted. The results show that the mass of the TPS tile efficiently deceased from 2.713 kg to 2.445 kg by 9.89%, and the robustness of the optimized design is better than the initial design. Finally, the effectiveness of the proposed optimization method is validated by the heat insulting experiment of the typical multilayer TPS tiles
Analysis of thermal stress, fatigue life and allowable flux density for the molten salt receiver in solar power tower plants
No full textThe solar power tower (SPT) receiver design should be able to stand with fatigue damage caused by the passage of clouds, start-up and shut-down. In this paper, to investigate the impacts of incident heat flux distribution and SPT site weather data on the thermal stress, fatigue life and allowable flux density (AFD) of the molten salt receiver, the relationship between the fatigue life and AFD of the tube wall is developed based on the coupled thermal-structural analysis and Miner linear damage theory. The results show that the cosine effect of the circumferential heat flux distribution considered has a significant influence on the location and magnitude of the maximum thermal stress of the tube wall, which lead to the difference in the tube wall fatigue damage. The AFD are, respectively, 829 kW/m(2) and 1037 kW/m(2) under uniform and cosine circumferential heat flux distributions for the site of Barstow, USA, when the design lifetime of the tube is 30 years. Compared with the SPT site of Barstow, USA, the fatigue damage of the tube wall in Sevilla, Spain, and Delingha, China, are lower under the same conditions due to lower insolation hours of direct normal irradiation in the range of 750-1100 W/m(2). The AFD are, respectively, 829 kW/m(2), 973 kW/m(2) and 997 kW/m(2) for the site of Barstow, USA, Sevilla, Spain, and Delingha, China, with 30 years design life. These findings give guidelines for the operation reliability of the SPT molten salt receiver tube
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
Fig. 5 in Diterpenoid alkaloids from the whole herb of Delphinium grandiflorum L
No full textFig. 5. Plausible biosynthetic pathway of 1.Published as part of Xu, Jin-Bu, Li, Yu-Zhu, Huang, Shuai, Chen, Lin, Luo, Yan-Yan, Gao, Feng & Zhou, Xian-Li, 2021, Diterpenoid alkaloids from the whole herb of Delphinium grandiflorum L, pp. 1-11 in Phytochemistry (112866) 190 on page 5, DOI: 10.1016/j.phytochem.2021.112866, http://zenodo.org/record/825800
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
Fig. 3. Key 1H–1H in Diterpenoid alkaloids from the whole herb of Delphinium grandiflorum L
No full textFig. 3. Key 1H–1H COSY, HMBC and NOESY correlations of 1 and 2.Published as part of Xu, Jin-Bu, Li, Yu-Zhu, Huang, Shuai, Chen, Lin, Luo, Yan-Yan, Gao, Feng & Zhou, Xian-Li, 2021, Diterpenoid alkaloids from the whole herb of Delphinium grandiflorum L, pp. 1-11 in Phytochemistry (112866) 190 on page 4, DOI: 10.1016/j.phytochem.2021.112866, http://zenodo.org/record/825800
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