1,720,962 research outputs found
Performance predictions for electromagnetic launching with multi-fibre solid brush armatures and resistively layered rail accelerators
No full textIn the literature on EML research, a number of proposals have been made to suppress the negative influence of the velocity skin effect on the performance of solid armatures during electromagnetic launch. In this paper, the results of a study of two of these methods, i.e. the application of multi-fibre solid brush armatures and the use of accelerator rails with a resistive layer, are presented. This study is performed by means of two-dimensional finite element computer simulations of the electrothermal behaviour of the armature and the rails during the launch process. A description of the electrothermal model used in the simulations is given. Here, the fibre armatures are regarded as made of materials with an anisotropic electrical and thermal conductivity. The results for the current distribution in a rectangular multi-fibre solid brush armature obtained from the simulations agree with the results of an analytical method. It is shown that fibre armatures have a more homogeneous current distribution during the acceleration process than monobloc armatures. U-shaped molybdenum multi-fibre solid brush armatures are good candidates for arc erosion-free launching if the electrical insulation of the fibres can be maintained at increasing temperature. Simulations also show that the skin depth in monobloc and fibre armatures can be increased by using rails with a resistive layer with suitable material properties
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
Detection performance assessment of hand-held mine detection systems in a procurement process: test set-up for MDs and MD/GPRs
No full textThe Engineers Centre of Expertise of the Royal Netherlands Army (RNLA) has conducted a study on countermine in peace operations. This study, finished in 2002, concluded that the final solution to countermine will depend in the first place on better detection of buried low-metal mines, e.g. by direct detection of the explosive components in mines. Until such detection systems are available, intermediate solutions are necessary in order to assure freedom of movement in peace operations. Because countermine operations consist of a number of different activities (area preparation, detection, clearance, etc) and the suitability of the different types of available equipment depends on the scenario, the toolbox concept for countermine equipment was adopted. In 2003 a procurement process was started in order to fill this toolbox with commercial-off-the-shelf and military-off-the-shelf equipment. The paper gives a concise description of the study on countermine operations and the procurement process, and subsequently focuses on the set-up of the tests that were conducted in the framework of the procurement of hand-held mine detection systems, like metal detectors and dual-sensor mine detectors. Programs of requirements for these systems were drawn up, aiming at systems for general use and special purpose systems. Blind tests to check the compliancy to the detection performance requirements were designed and conducted in the short timeframe that was available in the procurement process. These tests are discussed in this paper, including the set-up of the test lanes, the targets used and their depths, and the role of the operator. The tests of the capability of the detectors to discriminate small targets adjacent to large targets were conducted according the guidelines of the CEN Workshop Agreement on metal detector tests. Although the results of the tests are commercially confidential, conclusions and lessons learned from the execution of these tests are presente
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
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
Small-wavenumber divergency in the mode-coupling amplitudes for the heat-current time correlation function of a dense one-component plasma in a magnetic field
Get PDFThe long-time behaviour of the heat-current time correlation function of a one-component plasma in a magnetic field is studied with the use of mode-coupling theory. The coupling of two gyro-plasmon modes gives rise to contributions with amplitudes that are divergent for small wavenumber. These imply a slowly decaying long-time tail of the Green-Kubo integrand. As such a behaviour would lead to a divergency in the static heat conductivity, it is concluded that mode-coupling theory with diverging coupling amplitudes is not a reliable starting point for the study of the long-time behaviour of Green-Kubo integrands
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