1,721,094 research outputs found
Power system islands, autonomous microgrids and relevant instrumentation
No full textUnplanned power system islanding is usually seen as a major risky operating condition and specific countermeasures are applied in order to avoid it. However the capability of voluntary disconnection from the external grid and autonomous operation is often a requirement for some industrial power systems and power plants. The panel session at the 2012 IEEE Innovative Smart Grid Technologies Conference on “Power system islands, autonomous microgrids and relevant instrumentation” aims at providing an occasion to exchange ideas and experiences in order to envisage situations in which voluntary power system islanding may be useful and to define the instrumentation required for a reliable operation in islanded conditions. This paper, provided by the organizers, reviews some activities recently carried out on this topic at their institution
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
Le parole della fidatezza
No full textDopo aver introdotto la parola Fidatezza nell’articolo “Chiariamoci sul concetto di Fidatezza”, gli Autori ritengono opportuno, attraverso questo secondo lavoro e sempre nell’ottica di un uso appropriato dei termini, focalizzare l’attenzione su alcune “parole della Fidatezza”. Essendo tuttavia l’argomento assai vasto e articolato, esso non può essere affrontato esaustivamente attraverso la redazione di un solo articolo. Corre quindi l’obbligo di ricordare al Lettore l’esistenza di importanti documenti normativi (qui si farà riferimento alle norme redatte dal Comitato Tecnico CEI 56), ormai consolidati, ai quali è necessario riferirsi per eventuali approfondimenti. In questo contesto ci limiteremo pertanto a richiamare la terminologia essenziale sui guasti, le avarie e gli stati di sistema, terminologia ricorrente nei lavori della Rubrica che seguiranno, e a proporre una loro classificazione.
In ottica di revisione progettuale, di miglioramento delle prestazioni di Fidatezza e di analisi delle condizioni di impiego - aspetto che, come noto, condiziona fortemente le prestazioni di Fidatezza - non è tuttavia sufficiente misurare l’istante di tempo in cui si è verificato il guasto del componente o l’avaria del sitema ma occorre accertarne le cause. In tal senso il lavoro riporta alcuni esempi di classificazione dei guasti proposti dalla normativa di settore. Infine, si ritiene opportuno soffermarsi sul termine tasso di guasto ed il suo andamento temporale.On the basis of the term Dependability given in a previous work [1], it is important to recall the definition of some terms currently used in this field; this is the assumption of the title “the words of dependability”. For sake of simplicity only a subset of terms are proposed in the paper, referring to the standard IEC 60050 for more details. In particular, our attention is focused on the terms failure, fault and system state and presents a brief their classification according to the above mentioned Standard. Such classifications are fundamental in order to understand the causes that lead to a failure and to increase dependability performances of the system. A brief description of the failure rate and the plot of its function is also proposed
Origine e Classificazione dei Disturbi ed Indici per la loro Caratterizzazione: Modelli, Metodi e Strumenti
No full textAnalysis of the effects of flicker on the blood-flow variation in the human eye
No full textFlicker annoyance measurement, regardless if it isperformed by processing the supplying voltage or by evaluatingthe light emitted by the lamp, relies on the assumption of a propermodel of the behavior of the complex eye–brain system in thepresence of fluctuating light. The only experimental data availableare the ones obtained, for a certain incandescent lamp, by askingseveral people to report their perception about the flicker to whichthey were subjected. In this paper, the possibility of achieving an“objective” evaluation of the flicker effects on a human subjectis investigated. In particular, the increment of the blood flow in avessel at the optic nerve is considered and taken as a possible indexof annoyance due to flicker
Inductive Current Transformer Core ParametersBehaviour vs. Temperature Under Different Working Conditions
No full textThis paper presents a study focused on the equivalent parameters of an inductive current transformer for medium voltage purposes. In particular, its equivalent parameters behaviour has been assessed by varying both the temperature and the working conditions (current and voltage). Preliminary results provide interesting “calibration” curves which may be used during the transformer modelling
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
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