1,721,391 research outputs found
Self field AC losses in Ag-sheathed PbBi2223 tapes
No full textIn many engineering applications of high temperature superconductors the AC losses of the superconductor is an important design parameter. In general there are two cases of AC losses, those produced when the superconductor carries an AC transport current (self-field losses) and those produced when it is placed in an external AC field (external field losses). The work presented here is focused on the characterization of the self-field losses in Ag sheathed PbBi2223 tapes. The self-field losses of the tape can be devided into different regimes. At currents below the critical current of the tape the losses are dominated by the hysteresis losses of the tape. The cross-section of the superconducting core in a tape is best represented as either a "thin" rectangle or ellipse and the hysteresis losses can be calculated by solving the critical state for these two types of geometry. A standard method of measuring the self-field losses is to attach voltage contacts to the sample and measure the loss component of the surface electric field. However for the extreme geometry of the tape this loss electric field will vary according to the configuration of the voltage loop with a difference of up to 300% possible according to whether the loop is closed on top of or on the side of the tape. Detailed modelling and experiments have shown that an accurate measurement of the losses (within 5%) can be made provided that a suitable measurement protocol is followed. This protocol requires that the voltage loop used for measurement of the loss electric field is closed in the same plane as the tape at a distance for three times the tape half-width. In order to provide validation of the electric measurement a novel thermometric measurement system was constructed. With this method the losses within the tape are determined by the measurement of the temperature profile along an adiabatic tape with both ends at a fixed temperature. Comparative measurements between the electrical and thermometric systems showed a good correspondence for a large range of losses. Studies using the two systems also revealed that some of the tapes measured have a considerable inhomogeneity in the critical current along the length of the tape. Long lengths of the tape capable of carrying a high critical current are separated by shorter regions only capable of carrying a much reduced current. It is likely that the long regions of high current represent the intrinsic critical current of the tape with the reduced current in the shorter regions due to mechanical defects. Although the DC characteristics are dominated by the critical current in the short bad regions the AC losses are dominated by the critical current of the longer good regions making the AC measurements more indicative of the intrinsic critical current of the tape.</p
Refugee labour market transition and the role of third sector practitioners
No full textThis thesis investigates how host society actors influence the employability and labour market transitions of refugees. It was centred on qualitative investigation of how refugee-supporting third sector organisations in the UK engaged in collaborative work with employers. The study examined the roles and agency of the third sector organisations’ practitioners as they worked with employers to try and improve opportunities for refugees. The fieldwork consisted of scoping surveys, a case study, and semi-structured interviews, conducted with refugee employment support practitioners in third sector organisations across the UK.
There were three principal findings. Firstly, the third sector organisations faced major challenges from the limited capabilities and competencies of employers as recruiters and managers of people from forced migration backgrounds. Secondly, the most successful collaborations involved employers developing their capabilities through processes of dialogue with the third sector practitioners. Thirdly, the third sector practitioners conducting collaborative work with employers exercised highly developed competencies relating to the facilitation of learning across organisational and sociocultural boundaries.
These findings allow a reassessment of traditional views of how refugees’ social and labour market integration works. They show the opportunities and challenges that third sector organisations face to improve outcomes for refugees and employers. They also contribute to the growth of two-way perspectives on forced migrants’ labour market integration through highlighting the relational and socially situated aspects of refugees’ employability
Environmental controls on the state of HV cables under the seafloor
No full textSubmarine high voltage (HV) cables are becoming increasingly important to modern power transmission strategies. There has been a large amount of recent investment in projects such as offshore wind farms and international "megagrid" initiatives, of which submarine HV cables are essential components. A lot of research has been carried out into the thermal behaviour of HV cables buried on land. However, the performance of submarine HV cables has not been investigated extensively, despite several key differences between the two respective environments. The amount of power that can be transmitted along an HV cable is often limited thermally by the maximum operational temperature of the cable components. It is therefore crucial to understand how heat is dissipated from HV cables as comprehensively as possible to ensure reliable, economical, and efficient deployment of these assets.2D finite element method (FEM) simulations have been developed to examine the impact that certain environmental parameters have on the dissipation of heat generated within submarine HV cables into the surrounding burial sediment. Both conductive and convective heat transfer mechanisms are considered by solving coupled heat and fluid flow equations in a representative geometrical framework. The implications of some realistic inhomogeneous burial scenarios are considered, as is the impact of environmental conditions on cable temperature response times. The FEM model suggests that the most influential environmental factor in determining the nature of the heat flow around submarine HV cables is a quantity called the intrinsic permeability. For sediments with a high permeability, convection can make a significant contribution to the overall transfer of heat from submarine HV cables into the surrounding environment, despite being neglected by traditional techniques for assessing heat flow around cables buried on land. Under these circumstances, cable temperatures are typically lower than for low permeability sediments.Consideration of the additional cooling effect provided by convective heat transfer in these situations may result an increased cable current carrying capacity, or the potential to reduce the amount of conductor material required for manufacture
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
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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