1,720,964 research outputs found
Studio dell’efficienza di filtrazione nel numero e nella massa di un filtro per particolato close-coupled
No full textParticle number and mass collection efficiencies in a closecoupled DOC-DPF system: Experimental analysis supported by soot load modeling
No full textA comparison of particle number and mass collection efficiency of a close-coupled DOC-DPF system under different engine operating conditions
No full textPM effects on health are believed to be more related to particle total number rather than to particle total mass. This gave rise in Europe to the forthcoming introduction of an emission standard on total particle number, that will take place for passenger cars from EURO5 (stage b) on. The behavior of the DPF is therefore under investigation, to better understand its effectiveness toward particle number reduction. Moving from that background, a study on the effect of a close coupled DOC-CDPF (Diesel Oxidation Catalyst + Catalyzed Diesel Particulate Filter) on PM emissions is proposed in this paper, with special focus on the comparison between mass and number collection efficiency. Experimental data have been gathered at the engine laboratory of the University of Rome Tor Vergata, equipped with a FIAT 2.0l EURO 5 passenger car engine. Data have been acquired with a TSI 3090 EEPS to measure particle distribution and total number, and an AVL-415 S to measure PM mass emissions. A numerical code has been also developed to represent the DPF behavior, in terms of soot load (g/l) trend, under forced regenerating operating conditions and better understand regeneration potential as a function of time. Results, acquired for three non regenerating and one forced regenerating modes, prove that mass and number efficiencies are close to 100%, with a slight decrease during the forced regeneration mod
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
Trip-based control strategy for simple and efficient use of plugin hybrid electric vehicles
No full textThe optimal management of plugin hybrid electric vehicles (PHEVs)
energy efficiency and range autonomy is strictly dependent on the battery
discharge rate which may expressed by its state of charge (SOC) time variation.
In fact, vehicle efficiency is strongly influenced by the possibility of controlling
the SOC discharge rate as well as of the trip distance and the availability of
recharging facilities along the itinerary. In the given scenario, the accurate
control of SOC discharge rate to complying with trip-based target values of the
SOC (which allow for taking into account the availability of external recharge
station opportunities) appears as a key aspect to be investigated. In this paper,
we propose a robust and efficient optimised control strategy, implementable in
a state of the art ECU. The power-split strategy may be defined for any given
trip also taking into proper account the vehicle speed over the route. The main
target demonstrated in this paper is the request of reaching a target SOC
(SOCL) at the end of the trip although the application to other objectives (e.g.,
minimisation of emissions) is also theoretically feasible. The proposed strategy
is implemented and tested in a PHEV vehicle model designed and realised at
the University of Rome Tor Vergata, and validated by using experimental data
directly acquired over several standard cycles and real-world routes
EFFECTS OF BIODIESEL DISTILLATION PROCESS OF WASTE COOKING OIL BLENDS ON PARTICLE NUMBER AND MASS EMISSIONS
No full textThe use of biodiesel has been widely accepted as an
effective solution to reduce greenhouse emissions. The high
potential of biodiesel in terms of PM emission reduction may
represent an additional motivation for its wide diffusion. This
potential is related to the oxygenated nature of biodiesel,
leading to a different PM-NOx trade-off. Wide diffusion is also
under debate as it may represent a solution to the highly
disputed issue of the development of alternative biofuels
sources not competing with the food chain. In fact, besides
second generation biofuels (e.g. from algae), the
transesterification of Waste Cooking Oil (WCO) is another
option, that however needs additional insight. In fact, in this
case, the effects on particle emissions are still not well assessed,
as well as the impact of fuel distillation on engine performance
and emissions.
In this paper an experimental study on particle emissions
of a DEUTZ 4L off-road Diesel engine coupled to a DOC-DPF
system is proposed. Experimental data have been gathered at
the engine test bench of the University of Rome Tor Vergata, by
using baseline fossil fuel (B06) and blends (30 % vol) with both
distilled and non distilled WCO biodiesel. Data have been
acquired with respect to the three most probable engine points
referring to the NRTC (Non-Road-Transient-Cycle), upstream
and downstream of the AfterTreatment System.
Results show that B30 fuels have always lower emission
on a mass and number basis, and that distillation process may
have an impact especially at high power and torque operation.
A slightly better behavior in terms of mass emissions has been
observed for the blend with distilled fuel, while a slightly better
behavior in terms of particle number has been observed for the
blend with non-distilled fuel
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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