1,720,974 research outputs found
Electricity markets, network and generation evolution towards the decarbonization process of the power systems
Get PDFOggigiorno la struttura dei mercati e dei sistemi elettrici di potenza sono sotto conti-nua evoluzione per via della crescita dei consumi energetici e del processo di decarbonizza-zione della produzione di energia elettrica. Questa evoluzione è necessaria per far fronte ai vincoli stringenti nel funzionamento delle reti elettriche e alle ulteriori incertezze introdotte dal carico e dalle fonti di energia rinnovabile (FER).
Dal punto di vista della rete il suo sviluppo deve considerare la crescita del carico e delle FER al fine di evitare limitazioni tecniche. Tuttavia, l’aumento di produzione da FER mette a dura prova la flessibilità del sistema, per l’indipendenza con l’andamento della do-manda di carico, e per via della sua installazione che è prevalentemente localizzata sul si-stema di distribuzione. Questo, a sua volta, causa un cambiamento delle direzioni dei flussi di potenza, risultando in condizioni operative inusuali del sistema di trasmissione con possi-bili problemi di saturazioni delle portate di corrente e di sovratensione.
Dal punto di vista del mercato, i programmi di produzione e consumo, definiti in esito alle sessioni dei vari mercati che vanno dal medio al breve termine assicurando la minimiz-zazione di costi complessivi, potrebbero essere soggetti ad ulteriori azioni di ridispacciamen-to per fronteggiare errori di previsione di carico e FER, vincoli di rete e contingenze.
Per queste ragioni, è necessaria una completa e dettagliata visione del funzionamento del sistema dalla programmazione a lungo termine fino alle strategie in tempo reale. Pertan-to, la presente tesi di ricerca di dottorato tratta lo sviluppo integrato dalla programmazione del mercato giorno prima alle operazioni in tempo reale del sistema, così come la program-mazione a lungo termine dello sviluppo del sistema elettrico. In particolare, viene mostrato come le simulazioni di mercato e quelle di regime permanente della rete possono essere im-piegate per sviluppare diversi contesti metodologici per svolgere specifiche analisi in fun-zione della problematica trattata. La tesi in esame è composta da sei capitoli, ognuno dei quali è strutturato sulla base della raccolta delle pubblicazioni scientifiche relativi agli argo-menti esaminati.
Il primo capitolo di questa dissertazione fornisce un’introduzione degli argomenti trat-tati, dove vengono introdotti i concetti fondamentali dei moderni mercati elettrici dell’energia e dei servizi di dispacciamento e dei piani di sviluppo dei sistemi di potenza. In particolare, vengono descritti i metodi ed i modelli implementati per trattare i suddetti studi, fornendo un’ampia esaminazione della ricerca bibliografica per evidenziare i rispettivi stati dell’arte. Il secondo capitolo si focalizza sugli studi condotti sulla rete test IEEE 39 nodi, che è stata opportunamente modificata per introdurre produzione da fonte solare ed eolica nel mix del parco di generazione. Nel terzo capitolo vengono proposte due metodologie per la valutazione tecnico-economica dei benefici introdotti dallo sviluppo della rete di trasmis-sione installando una nuova linea elettrica. Nel quarto capitolo viene proposta un’analisi di investimento della generazione in un sistema elettrico liberalizzato, al fine di individuare la taglia e il luogo più idonei che fornisca un guadagno economico all’investitore. Nel quinto capitolo viene descritta una metodologia pratica per determinare i fabbisogni di energia elet-trica sulla base delle incertezze del sistema. Inoltre, viene proposta una procedura per risol-vere un problema di ottimizzazione di security constrained unit commitment and economic redispatch. Nell’ultimo capitolo viene trattato un caso studio reale al fine valutare le strate-gie dell’operatore del sistema di trasmissione dal mercato dell’energia a quello in tempo rea-le per garantire il corretto funzionamento del sistema di trasmissione.
La ricerca condotta affronta le seguenti problematiche:
• Valutazione di metodologie tecnico-economiche per valutare la pianificazione dello sviluppo di rete in condizioni di crescita di carico e FER, per poter migliorare il so-cial welfare e per ridurre le azioni di ridispacciamento.
• Dimensionamento dei fabbisogni di riserva di energia per gestire efficacemente l’approvvigionamento nel mercato dei servizi di dispacciamento, soddisfano i vincoli di rete e dei meccanismi di mercato.
• La considerazione delle prospettive dell’operatore del sistema e dei partecipanti del mercato per valutare le rispettive strategie di pianificazione e operazione e le loro in-terazioni.
• Applicazioni a casi studio reali, per poter testare la validità del modello per problemi su sistemi di larga scala.The electricity market and power system frameworks are currently being adjusted to account for both the growing energy consumption and the decarbonization of electrical en-ergy production. This evolution is required to cope with the tightening constraints of the power system operation and the further uncertainties introduced by load and renewable en-ergy sources (RES).
From the network perspective, the development has to consider the load and RES growth in order to avoid technical limitations. However, increased RES production puts a strain on system flexibility, due to uncorrelation with load demand trend, and to installation mostly located on distribution system. This, in turn, causes a change in power flow direc-tions, resulting in unusual transmission network operating conditions with possible current capacity saturation and overvoltage issues.
From the market perspective, the production and consumption schedules, ensuring the minimization of the overall costs as yields of the various market sessions over medium- and short-time horizon, could be subject to further redispatching actions to tackle RES and load forecast errors, and to cope with network constraints and contingencies.
Useful methodologies to overcome the aforementioned issues are based on approach-es combining market and network analysis procedures. To these purposes, a complete and detailed concept of the system operation is required from long-term planning to real-time strategies. Therefore, the present doctoral research thesis is concerned with the integrated development, from day-ahead schedule to real-time operations, of electricity markets and transmission systems, as well as the long-term network evolution planning. It is specifically illustrated how market and steady-state simulations can be used to create various methodo-logical frameworks to carry out an appropriate analysis, in accordance with the issues under study. This thesis is divided into six chapters, related to the published or submitted scien-tific papers on the treated topic.
The first chapter is the dissertation’s comprehensive introduction. The fundamentals of modern energy and ancillary service markets as well as of network evolution planning are described. In particular, methods and models to develop the aforementioned studies are presented in this chapter, providing a further literature review to pinpoint the respective state-of-the-art. The second chapter is focused on the IEEE 39-bus system, that is suitably modified to include solar and wind generation in the traditional generation mix. The third chapter concerns two methodologies for technical and economic benefit evaluation of net-work development projects. The fourth chapter proposes a generation investment analysis in a deregulated market framework, evaluating the most suitable size and location to maximize the investor economic profit. In the fifth chapter a practical method for calculating operat-ing reserve requirements considering system uncertainties. Furthermore, a procedure for se-curity constrained redispatch optimization problem is proposed. In the last chapter a real case study to evaluate transmission system operator strategies from the energy to the bal-ancing markets is proposed in order to evaluate the secure operation of the transmission sys-tem.
The developed research addresses the following issues:
• Assessing network evolution planning under load and RES increase, in order to im-prove the social welfare and to reduce redispatching actions.
• Accurate reserve requirements sizing, to effectively manage ancillary service provi-sion, fulfilling the network constraints and market mechanisms.
• Considering system operator and market participant viewpoints, to evaluate respec-tive planning and operation strategies and their interactions.
• Real-case applications, to test the method validity for large-scale system issues
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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