1,720,998 research outputs found
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
Non-exhaust traffic related emissions – Brake and tyre wear PM
Full text linkTraffic related sources are a significant contributor of particulate matter, particularly in urban environments and major cities. Traffic related particles can be distinguished into: exhaust traffic related particles, which are emitted as a result of incomplete fuel combustion and lubricant volatilization during the combustion procedure, and non-exhaust traffic related particles, which are either generated from non-exhaust traffic related sources such as brake, tyre, clutch and road surface wear or already exist in the environment as deposited material and become resuspended due to traffic induced turbulence. It is estimated that exhaust and non-exhaust sources contribute almost equally to total traffic-related PM10 emissions. However, as exhaust emissions control become stricter, relative contributions of non-exhaust sources to traffic related emissions will increasingly become more significant. The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding particulate emissions resulting from non-exhaust sources and particularly from brake and tyre wear. For this reason several different literature sources such as peer reviewed papers, research project reports, technical publications, as well as licentiate and doctoral theses were examined and the most significant findings in terms of importance, physicochemical characteristics, EFs and possible adverse health effects are discussed.JRC.F.8 - Sustainable Transpor
Chemical characterization of participate matter emitted from biodiesel combustion
No full textatty Acid Methyl Esters (FAMEs) are the most common renewable fuels used for diesel fuel blending. Rapeseed Methyl Ester (RME) is currently the most common FAME type throughout Europe and was chosen for this study. The objective of this study was to evaluate the impact of higher RME levels on unregulated particle emissions. Three Euro 4-compliant light-duty diesel vehicles were selected. All vehicles featured exhaust gas recirculation (EGR) and some type of diesel oxidation catalyst (DOC). Two vehicles were also equipped with Diesel Particulate Filters (DPF) using two different DPF regeneration strategies. Four FAME/diesel blends were blended and tested: A reference diesel fuel (<10mg/kg sulphur) (B0) and 3 blends of this fuel with RME at 10% v/v (B10), 30% v/v (B30), and 50% v/v (B50) over both the regulatory New European Driving Cycle (NEDC) and ‘real-world’ ARTEMIS driving cycle for particulate matter (PM), particularly: (a) determination of the Soluble Organic Fraction (SOF) of the emitted PM followed by a breakdown to fuel- and oil- derived hydrocarbons, (b) determination of the n-alkanes of the emitted SOF, (c) determination of the major anion and cation components of the emitted PM, (d) estimation of the EC content of the PM by subtracting the sum amount of SOF and ions from the gravimetrically measured PM mass and finally (e) determination of the oxidation potential of the SOF. The vehicle testing protocol was statistically designed in order to provide robust results for all emissions. Biodiesel in higher amounts reduced emissions of most of the chemical constituents of PM even if the reduction was not significant in DPF equipped vehicles. DPF equipped vehicles appeared a general tendency of increase of % total SOF and % F-D SOF with increasing blend, in both driving cycles. On the other hand, % O-D SOF was not affected by increasing blend. The major constituent of the DPM was F-D SOF. On the other hand, the non-DPF equipped vehicle appeared a general tendency of increase of % total SOF with increasing blend. In that case the major constituent of the DPM was EC. All vehicles emitted significantly higher % F-D SOF than % O-D SOF. In brief, F-D SOF emissions comprised from 70% to 90% of total SOF emissions. Although SOF emissions (mg/km) were generally higher in Artemis Urban than in NEDC, in DPF equipped vehicles % emissions were higher in NEDC due to the cold start of the engine during this cycle. N-alkanes were detected only in case of the non-DPF equipped vehicle and comprised about 20-40% of the emitted SOF. DPF equipped vehicles recorded slight differences in % nitrate emissions with increasing blend. Sulphates were not detected in DPF equipped vehicles as a result of getting trapped in the filter. The non-DPF equipped vehicle also recorded slight differences in % anion emissions with increasing blend. Sulphate emissions were slightly higher compared to nitrate emissions. All vehicles recorded ammonium emissions which not exceeded 4% of the total DPM emitted. EC percentage in the DPM determined by subtraction recorded a general tendency of decrease with increasing blend. Oxidation activity slightly increased with increasing blend, regardless the vehicle. DPF equipped vehicles recorded higher values of oxidation activity than the non-DPF equipped vehicle thus indicating more toxic organic emissions.Η απαίτηση της Ε.Ε. ώστε το 10% των ενεργειακών αναγκών για τις μετακινήσεις να καλύπτεται από ανανεώσιμα καύσιμα ως το 2020 οδήγησε τα τελευταία χρόνια στην εκτεταμένη χρήση του βιοντίζελ. Από τους μεθυλεστέρες των λιπαρών οξέων, αυτός του κραμβελαίου (Rapeseed Methyl Ester, RME) χρησιμοποιείται συχνότερα στην Ευρώπη για τη παραγωγή του βιοντίζελ και για το λόγο αυτό επιλέχθηκε στην παρούσα διατριβή. Στόχος της διατριβής είναι ο προσδιορισμός της επίδρασης της αύξησης του ποσοστού του βιοντίζελ στις εκπομπές των κυριότερων σωματιδιακών ρύπων και στην οξειδωτική δραστικότητα του διαλυτού οργανικού κλάσματος (Soluble Organic Fraction, SOF) της σωματιδιακής ύλης (Diesel Particulate Matter, DPM). Για το λόγο αυτό, επιλέχθηκαν τρία σύγχρονα επιβατηγά οχήματα ντίζελ (Euro 4+) εφοδιασμένα με οξειδωτικό καταλύτη, ενώ τα οχήματα 1 (V1) και 3 (V3) έφεραν επιπλέον διαφορετικού τύπου συστήματα ελέγχου των σωματιδιακών εκπομπών. Για τις δοκιμές επιλέχθηκε ένα συμβατικό καύσιμο ντίζελ χαμηλού θείου (B0) και τρία μίγματα του B0 με RME (B10, B30 και B50). Οι δοκιμές πραγματοποιήθηκαν στο νέο ευρωπαϊκό κύκλο οδήγησης (NEDC) και τον αστικό κύκλο Artemis Urban. Οι αναλύσεις της DPM των καυσαερίων περιελάμβαναν: (α) τον προσδιορισμό του SOF και το διαχωρισμό του σε προερχόμενο από το καύσιμο (Fuel Derived SOF, F-D SOF) και το λιπαντικό (Oil Derived SOF, O-D SOF), (β) τον προσδιορισμό των κ-αλκανίων και (γ) τον προσ-διορισμό των ιοντικών συστατικών. Επιπλέον, υπολογίστηκε ο στοιχειακός άνθρακας (Elemental Carbon, EC) με αφαίρεση του SOF και των ιοντικών συστατικών από τη συνολική DPM. Τέλος, προσδιορίστηκε η οξειδωτική δραστικότητα του SOF μέσω της δοκιμής της διθειοθρεϊτόλης (DTT test). Παρά το γεγονός ότι η χρήση του βιοντίζελ φαίνεται να έχει θετικό αντίκτυπο στις εκπομπές των περισσότερων ρύπων εντούτοις οι διαφορές δεν είναι σημαντικές, ειδικά στην περίπτωση των οχημάτων με παγίδα. Τα V2 και V3 εμφανίζουν μία τάση αύξησης των εκατοστιαίων περιεκτικοτήτων των SOF και F-D SOF στη DPM με την αύξηση του ποσοστού του βιοντίζελ. Στον αντίποδα, οι εκατοστιαίες περιεκτικότητες του O-D SOF δε φαίνεται να μεταβάλλονται με την αύξηση του βιοντίζελ. Το V2 σημειώνει χαμηλότερες εκατοστιαίες περιεκτικότητες του SOF στη DPM από τα οχήματα με παγίδα. Το F-D SOF συνιστά το 70-90% του ολικού SOF, ενώ στα V1 και V3 αποτελεί το κυρίαρχο συστατικό της DPM. Στο V2 τα προσδιοριζόμενα κ-αλκάνια αποτελούν το 21-39% του SOF και το 4-8% της συνολικής DPM. Σε αντίθεση με το SOF, οι εκατοστιαίες περιεκτικότητες των νιτρικών ιόντων στη DPM δε φαίνονται να επηρεάζονται από την αύξηση του βιοντίζελ. Στα V1 και V3 δεν ανιχνεύονται θειικά ιόντα, ενώ στο V2 προσδιορίζονται σε ποσοστά λίγο υψηλότερα από τα νιτρικά. Όλα τα οχήματα σημειώνουν χαμηλές εκπομπές αμμωνιακών. Τα V2 και V3 εμφανίζουν μία τάση ελάττωσης των εκατοστιαίων περιεκτικοτήτων του EC στη DPM με την αύξηση του βιοντίζελ. Στο συγκεκριμένο στήσιμο των κινητήρων οι χαμηλότερες εκπομπές των εξεταζόμενων ρύπων εμφανίζονται με το Β30. Ανεξαρτήτως οχήματος, παρατηρείται αύξηση της οξειδωτικής δραστικότητας ανά μο-νάδα μάζας του εκπεμπόμενου SOF με την αύξηση του βιοντίζελ. Αυτό αποτελεί ένδειξη ότι οι οργανικές ενώσεις που εκπέμπονται με τα βιοντίζελ είναι δυνητικά πιο επικίνδυνες από τις αντίστοιχες του συμβατικού ντίζελ. Οι τιμές της οξειδωτικής δραστικότητας ανά μονάδα μάζας είναι υψηλότερες στα οχήματα με φίλτρο σωματιδίων από ότι στο V2
Brake wear particle emissions: A review
Full text linkTraffic related sources have been recognized as a significant contributor of particulate matter particularly within major cities. Exhaust and non-exhaust traffic related sources are estimated to contribute almost equally to traffic related PM10 emissions. Non-exhaust particles can be generated either from non-exhaust sources such as brake, tyre, clutch and road surface wear or already exist in the form of deposited material at the roadside and become resuspended due to traffic induced turbulence. Among non-exhaust sources, brake wear can be a significant PM contributor, particularly within areas with high traffic density and braking frequency. Studies mention that in urban environments brake wear can contribute up to 55% by mass to total non-exhaust traffic related PM10 emissions and up to 21% by mass to total traffic related PM10 emissions, while in freeways this contribution is lower due to lower braking frequency. As exhaust emissions control become stricter, relative contributions of non-exhaust sources - and therefore brake wear - to traffic related emissions will become more significant and will raise discussions on possible regulatory needs. The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding PM resulting from brake wear and provide all the necessary information in terms of importance, physicochemical characteristics, emission factors and possible health effects.JRC.F.8 - Sustainable Transpor
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
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
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