1,721,179 research outputs found
Multi-Agent Based Techniques for Coordinating the Distribution of Electricity in a MicroGrid Environment
No full textBy the year 2050, the UK must transition to a low carbon economy via an 80% reduction of all carbon emissions. In order to ensure that this challenging low carbon emissions plan is met, not only will energy need to be generated and used more efficiently, but technologies that use cleaner energy, such as the electrification of home heating and vehicles, will need to be introduced. This increase in demand for electricity will need to be balanced with additional supply, however the current national grid is not capable of sustaining this increase. Therefore a more dynamic and efficient two-way national grid will be required which incorporates intermittent renewable resources, micro-generators, micro-storage devices and agent managed microgrids. Fred Schweppe, a recognised world leader in the field of electric power, at Massachusetts Institute of Technology from 1960 onwards, researched ways in which a dynamic national grid could be implemented. However at the time the technologies available were limited. This paper compares the current state of the art techniques at solving some of problems Schweppe identified, describes the agent coordination algorithms that are used, and suggests some future research opportunities on applying agent coordination algorithms, that have not previously been used, to microgrids
Coordinating generators in the smart grid (Extended Abstract)
No full textDue to highly constrained ageing infrastructure, current electricity networks will not be able to handle an increased amount of generation; particularly that from intermittent renewable resources deployed within distribution networks. In order to efficiently control this increased generation, decentralised autonomous control is the only viable solution; due to the computational complexities that arise for large networks. Thus, an agent managed smart grid will be essential for future electricity networks. Part of this system will be agent managed distribution networks that incorporate an increased amount of decentralised micro-generation from renewable resources. My PhD focuses on the algorithms and techniques needed for distribution network operators to use in order to coordinate generators within their networks efficientl
Alien Registration- Miller, Sam (Lewiston, Androscoggin County)
Full text linkhttps://digitalmaine.com/alien_docs/27969/thumbnail.jp
Decentralised coordination of smart distribution networks using message passing
No full textOver the coming years, distribution network operators (DNOs) face the challenge of incorporating an increased number of electrical distributed generators (DGs) into their already capacity-constrained distribution networks. To overcome this challenge will require the DNOs to use active network management techniques, which are already prevalent in the transmission network, in order to constantly monitor and coordinate these generators, whilst ensuring that the bidirectional flows they engender on the network are safe. Therefore, this thesis presents novel decentralised message passing algorithms that coordinate generators in acyclic electricity distribution networks, such that the costs (in terms of carbon dioxide (CO2) emissions) of the entire network are minimised; a technique commonly referred to as optimal dispatch. In more detail, we cast the optimal dispatch problem as a decentralised agent-based coordination problem and formalise it as a distributed constraint optimisation problem (DCOP). We show how this DCOP can be decomposed as a factor graph and solved in a decentralised manner using algorithms based on the generalised distributive law; in particular the max-sum algorithm. We go on to show that max-sum applied naively in this setting performs a large number of redundant computations. To address this issue, we present both a discrete and a continuous novel decentralised message passing algorithm that outperforms max-sum by pruning much of the search space. Our discrete version is applicable to network settings that are entirely composed of discrete generators (such as wind turbines or solar panels), and when the constraints of the electricity network have been discretised. Our continuous version can be applied to a wider range of network settings containing multiple types of generators, without the need to discretise the electricity distribution network constraints. We empirically evaluate our algorithms, using two large real electricity distribution network topologies, and show that they outperform max-sum (in terms of computational time and total size of messages sent
Optimal Decentralised Dispatch of Embedded Generation in the Smart Grid
No full textDistribution network operators face a number of challenges; capacity constrained networks, and balancing electricity demand with generation from intermittent renewable resources. Thus, there is an increasing need for scalable approaches to facilitate optimal dispatch in the distribution network. To this end, we cast the optimal dispatch problem as a decentralised agent-based coordination problem and formalise it as a DCOP. We show how this can be decomposed as a factor graph and solved in a decentralised manner using algorithms based on the generalised distributive law; in particular, the max-sum algorithm. We go on to show that max-sum applied na?vely in this setting performs a large number of redundant computations. To address this issue, we present a novel decentralised message passing algorithm using dynamic programming that outperforms max-sum by pruning the search space. We empirically evaluate our algorithm using real distribution network data, showing that it outperforms (in terms of computational time and total size of messages sent) both a centralised approach, which uses IBM’s ILOG CPLEX 12.2, and max-sum, for large networks
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
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