1,721,055 research outputs found
An Experimental Comparison in the Uncertainty Estimation affecting wavelet-based Signal Analysis by means of the IEC-ISO Guide and the Random-Fuzzy Approaches
No full textThe aim of this paper is the comparative estimation of the measurement uncertainty associated to the results of complex measurements, such as the evaluation of the wavelet transform of signals affected by transient disturbances. The uncertainty estimation is performed by means of two different methods: the approach suggested by the IEC-ISO “Guide to the Expression of Uncertainty in Measurement" and the one, recently proposed in the literature, based on the use of Random-Fuzzy variables. The comparison is performed starting from actual signals generated and acquired by means of a suitable test system
Gestione dei sistemi elettrici in presenza di generazione da fonti rinnovabili: criteri decisionali basati su misure incerte
No full textLa presente memoria richiama l’attenzione su alcuni importanti aspetti legati alle metodologie di gestione delle reti elettriche, con riferimento, in particolare, ai problemi legati ad un utilizzo improprio delle informazioni disponibili dal campo e ai conseguenti rischi decisionali. Le problematiche discusse assumono particolare importanza in presenza di generazione da fonti rinnovabili, in virtù dei cambiamenti che essa impone nella gestione tecnica ed economica del sistema di distribuzione.
L’attenzione sarà concentrata in particolare sulla qualità della fornitura e del prelievo di energia elettrica, dal momento che la presenza sempre più diffusa di elementi capaci di degradare tale qualità, nonché la maggiore sensibilità degli utenti, hanno inevitabilmente richiamato su questo aspetto l’attenzione sia della comunità scientifica che degli organismi di governo nazionali (autorità, gestori di reti, ecc.).
Sono pertanto richieste informazioni di misura attendibili sulla base delle quali possano essere assunte decisioni connesse a politiche contrattuali, tariffarie, ecc. L’affidabilità e la correttezza di tali informazioni dipendono sia dall’individuazione di metodologie di misura teoricamente corrette sia dalla valutazione di come gli effetti delle sorgenti di incertezza si propagano sui risultati.
Nella memoria saranno approfonditi questi aspetti, evidenziando i punti critici su cui occorrerebbe dedicare future risorse per minimizzare i rischi di decisioni prese sulla base di dati che, provenendo da risultati di misure, non possono essere considerati come assolutamente certi e che quindi, se non considerati insieme alla loro incertezza, possono portare a decisioni errate
Analysis 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
The impact of Internet transmission on the uncertainty in the electric power quality estimation by means of a distributed measurement system
No full textInductive 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
A distributed system for the synchronized acquisition of fast voltage transients
No full textVoltage transients are the main causes of complaints for medium-voltage customers, and hence interest is focused on investigation techniques able to help in classifying and localizing such events in accordance with their origin. In this light of fact, a distributed measurement system for performing synchronized acquisition of fast voltage transients is presented in this paper. The system, designed to fulfill specific constraints about the reliability of the provided information, has been used in a one-year long measurement campaign performed in a medium voltage network. The main obtained results are presented
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
A pupil size measurement system for the analysis of the impact of flicker on human being
No full textA pupil size measurement system for the analysis of the impact of flicker on human bein
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