1,721,007 research outputs found
Angular electromagnetic response of double-ring metamaterials for TE polarization
No full textWe investigate transmission characteristics in symmetric planar double-ring metamaterials at oblique angles of incidence theoretically. The double-ring microwave metamaterials are used to study resonant response to incident TE electromagnetic wave. The trapped-mode resonant feature results from the excitation of antisymmetric current mode and the quality factor is associated to the angle of incidence
Isogeometric Shape Optimization for Quasi-static and Transient Problems
No full textThe recently developed isogeometric analysis (IGA) was aimed, from the start, at integrating computer aided design (CAD) and analysis. This synthesis of geometry and analysis has naturally led to renewed interest in developing structural shape optimization. The advantages of using isogeometric analysis in shape optimization are embodied in its ability to preserve exact CAD geometrical descriptions and its enhanced potential to perform shape sensitivity analysis. Recent contributions in shape optimization within IGA have been limited to static or steady-state loading conditions. The purpose of this work was to extend the isogeometric shape optimization and identification to quasi-static and transient problems. The normalization approaches for the search directions in isogeometric shape optimization scheme and the mean value property of B-spline basis were also studied. Shape sensitivity analysis plays a critical role in structural shape optimization. In this dissertation, an adjoint sensitivity analysis was performed for arbitrary objective functionals defined for quasi-static and transient problems at the continuous level. The sensitivity for quasi-static and transient problems are essentially different with each other since the transient case has a time-derivative term involved in the time interval. The transport relations considering discontinuities were studied and used to derive the continuous adjoint shape sensitivity. Consideration of the discontinuities enabled the shape sensitivity analysis to be applicable for the problems where discontinuities were involved in the objective functional and state equations. Then within the context of IGA, the continuous sensitivity was discretized to obtain the discrete design sensitivity with respect to the design discretization, which was used to find the search directions used to update the shape numerically. A interesting phenomenon in shape optimization is that the use of the search direction directly predicted from the discrete shape gradient makes the optimization history strongly dependent on the discretization. This discretization dependency can affect convergence and may lead the optimization process into a sub-optimal solution. The source of this discretization dependency was traced to the lack of consistency with the local steepest descent search direction in the continuous formulation. This inconsistency was analyzed using the shape variation equations and subsequently illustrated with a volume minimization problem. It was found that the inconsistency originates from the NURBS discretization which induces a discrete quadratic norm to represent the continuous Euclidean norm. To fix this inconsistency, a standard normalization approach, which is used to find the steepest descent direction for quadratic norm problems, was proposed to obtain a consistent discretization independent search direction. The standard approach requires solving a linear system of equations. Using the diagonally lumped mapping matrix (DLMM) and the partition of unity property of NURBS, two simpler normalization approaches, which do not require solving a linear system of equations, were proposed. The discretization-independence of the proposed approaches was verified with a benchmark problem. The superiority of the proposed search direction and its suitability for numerical implementation is illustrated with examples of shape optimization for mechanical and thermal problems. In the derivation of the simplified normalization approaches, the mean value property of B-spline basis function is proposed and proved using mathematical induction method. Using the normalization approaches, two frameworks to solve shape optimization and identification problems for quasi-static and transient process, respectively, were developed and implemented numerically within the context of isogeometric analysis. Generalized objective functionals were used to accommodate both structural shape optimization and identification problems in arbitrary forms. The methodology and its numerical implementation were tested using benchmark problems or passive control approaches with priori known solutions. For the quasi-static case, application problems were considered where an external load was allowed to move along the surface of a structure. The shape of the structure was modified to control the time-dependent displacement of the point where the load was applied according to a pre-specified target. For the transient case, the shape optimization and identification was performed for a plunger design under a transient heating process and a thermal protection layer design for a ballistic re-entry vehicle.Aerospace Structures and MaterialsAerospace Engineerin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Leucoma candida
No full textLeucoma candida (Staudinger, 1892) (Figs 5‒6, 20, 30) Stilpnotia salicis var. candida Staudinger, 1892: 308; Bryk, 1934: 115. Stilpnotia candida: Swinhoe, 1922: 462; Chao, 1978: 54. Liparis salicis: Bremer, 1864: 41. Leucoma candida: Kozhanchikov, 1950: 345; Inoue, 1956: 156; Chao, 2003: 286; Wang et al., 2015: 583. Diagnosis. The species is often confused with L. salicis due to the similarity of superficial characters, but can be easily separated from the latter by the following characters: main stem of antenna white, with a black-brown stripe; vesica of aedeagus with numerous minute denticles; female genitalia with a M-shaped signum within bursa. Material examined. 1♂ 1♀, Tiantai Mountain National Forest Park, Feng County, Baoji City, Shaanxi, 6– 13.VIII.2018, leg M. Wang, Z.P. Miao. 2♂, Huameiguang, Liuba County, Hanzhong City, Shaanxi, 10-12.VIII.2018, leg M. Wang, Z.P. Miao. 1♂, Heping Village, Caoke Towns, Shimian County, Ya’an City, Sichuan, China, 26– 27.VII.2017, leg M. Wang, Z.P. Miao. 3♂ 2♀, Tacheng Town, Weixi County, Diqing Tibetan Autonomous Prefecture, Yunnan, 15-18.VII.2018, leg M. Wang, Z.P. Miao. Distribution. China (Hebei, Shanxi, Liaoning, Jilin, Heilongjiang, Jiangsu, Zhejiang, Anhui, Fujian, Jiangxi, Shandong, Henan, Hubei, Sichuan, Yunnan, Shaanxi, Qinghai, Gansu), North Korea, Japan, Russia.Published as part of Xie, Linzhe, Wang, Ming, Chen, Yusi & Wang, Houshuai, 2022, Review of the genus Leucoma Hübner, 1822 (Lepidoptera: Erebidae: Lymantriinae) from China, with description of two new species, pp. 361-380 in Zootaxa 5115 (3) on pages 364-365, DOI: 10.11646/zootaxa.5115.3.3, http://zenodo.org/record/635837
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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