1,720,994 research outputs found
Protection and Pole Voltage Rebalancing for Pole-to-ground Faults in Symmetrical Monopolar HVDC Grids
No full textPole rebalancing in symmetrical monopolar HVDC grids is
necessary to remove pole imbalances resulting from pole-toground
faults. For selective protection employing DC circuit
breakers, pole rebalancing considering backup protection operation
in case of breaker failure has until now not been studied.
This paper proposes fault clearing and post-fault restoration sequences
including pole rebalancing to deal with DC-side faults,
considering both primary and backup protection operations.
The performance of the proposed sequences and the impact of
the key breaker parameters on pole rebalancing are investigated
in a four-terminal test system using PSCAD/EMTDC.status: Publishe
The impact of fault blocking converters on HVDC protection
Full text linkMultiterminal High Voltage Direct Current (HVDC) systems are anticipated to enable flexible transmission of renewable energy across continents, however protection strategies for such systems are in their infancy. Fast circuit breakers have been proposed, however their implementation on a network is undecided. The protection requirements are likely to depend on both the AC/DC converter and network topologies.
This thesis examines several aspects of the protection of HVDC systems, considering factors influencing circuit breaker ratings, and examining primary and backup protection philosophies. A comparison is made throughout between fault feeding and fault blocking converters, aiming to investigate the impact of fault blocking converters on HVDC protection.
The ratings of HVDC circuit breakers on meshed networks are evaluated, considering factors such as the current breaking magnitude, operation time, additional inductance and energy dissipation requirements for various network and converter topologies. It is shown that the circuit breaker requirements in network areas with fault blocking converters are reduced compared to when a fault feeding converter is implemented.
HVDC protection is investigated, considering primary and backup methods for several protection philosophies. The influence of the converter, network and circuit breaker topologies are examined, and the impact of the HVDC protection strategy on the connected AC systems is evaluated. It is shown that slower protection strategies using fault blocking converters might be technically feasible from both the HVDC and AC system perspectives, which could result in an effective protection strategy with a reduced requirement for circuit breakers.Open Acces
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
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
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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