1,720,962 research outputs found
Orthonormal Gas-chromatography sets of Extra Virgin Olive Oil
No full textStarting from gas-chromatograms of extra virgin olive oil samples, choosing the most significant peaks, authors try to define a standard ortho-normal base to be deposited for quality valuation
Disseminazione del Panel Test, metrologia per la valutazione dell’olio extra vergine di oliva
No full textIl controllo delle caratteristiche organolettiche per la valutazione della qualità dell’Olio Extra Vergine di Oliva (EVOO) è regolata dalle autorità europee che indicano l'utilizzo del Panel Test (PT).
Il PT può essere considerato un vero "sistema metrologico" mentre le percezioni degli assaggiatori sono le sollecitazioni. Questo lavoro ha lo scopo di "disseminare" le proprietà della metrologia rappresentate dal PT per consentire un accesso più abbordabile ad un metodo di valutazione dell’olio altrimenti troppo costoso per le piccole imprese. I risultati del PT vengono impiegati per l’addestramento di una Rete Neurale Artificiale (ANN) non supervisionata. La sintesi è rappresentata
su una mappa di Kohonen che rende leggibile i risultati del PT. La disseminazione è ottenuta mediante l’uso dell’algoritmo Back-Propagation su una ANN supervisionata i cui input sono i risultati dell’analisi gascromatografica (GC) di ogni campione di olio e gli output i punteggi ottenuti dal PT.
Questa procedura è la "disseminazione della metrologia di uno standard" e anche l'obiettivo del lavoro cioè classificare gli EVOO senza dover sempre ricorrere al PT
Aromatic stability and degradation of Extra Virgin Olive Oil
No full textThe Panel Test (PT) is performed by certified assayers and recognized by European Union. From a statistic point of view, it is a methodology sufficiently objective and repetitive so realizing a Metrology. The aim of this work is the study of extra virgin oil olive degradation and stability.
The method uses a cascade of two neural networks which inputs are an essential set of quality parameters coming from the Panel Tests made on extra virgin olive oils samples and gas chromatographic analysis on them. Nine extra virgin olive oil samples have been examined. The results of the PT are classified by an unsupervised neural network and related on a Kohonen Map. Then, they are correlated to Gas Chromatographic analysis of olive oil by the Multi Layer Perceptron with Back-Propagation (MLP-BP), a supervised neural network. The MLP-BP is able to classify a sample different from those used for the learning.
The olive oil degradation is analyzed by comparing the results on the same sample performed in different periods. Instead, the aromatic stability is observed by comparing different sample from the same producer.
The degradation has been observed by the change of the intensity of the signals: the reduction of aromas "fruity" and "green grass" is detected, typical flavors of freshness of the product, in in some oils the flavors "spicy" and "mint" appear.
As regards the aromatic stability, many products have maintained the bearing characteristics while the few variations are related to the disappearance of aromas of flowers and/or apple
The Panel Test as the Metrology of Extra Virgin Olive Oil Quality Evaluation and Its Dissemination
No full textNowadays, the check of the organoleptic characteristics for the evaluation of extra virgin olive oil (EVOO) quality is
regulated by the European Union (EU) authorities, which indicate the use of the panel test (PT). It is composed by a team of
specialists that give a numerical value to many characteristics about flavours, synthesising a sensory analysis. Each expert answers questions about the aroma by assigning the adequate scores to each oil. The evaluation becomes objective by applying the statistical analysis of all the scores given by the participants: This is the definition of “measure” of Russell. The PT can be considered a true standard “metrological system” (considering the number of questions in the questionnaire), while the perceptions of the testers are the solicitations of it. To allow access to an expensive evaluation process by small companies, this work proposes to “disseminate” the properties of the metrology represented by PT. The results of the PT are arranged in an unsupervised artificial neural network (ANN), the Kohonen map, which represents the synthesis of self-organised output that has only the goal, in this paper, to make readable PT results. The dissemination process is obtained by the gas chromatographic (GC) analysis of each oil sample and through the identification of peaks corresponding to the perceptions. These signals are used for the training of the supervised Multi Layer Perceptron (MLP) ANN, with the back propagation algorithm, whose outputs are represented by the results of the PT. This procedure is exact a “metrological dissemination of a standard” and also the aim of the work: to classify EVOO without always resorting to PT
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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