1,720,977 research outputs found
The Modular Engine Concept: a Cost Effective Way to Reduce Pollutant Emissions and Fuel Consumption
No full textA promising technique to enhance fuel efficiency of large capacity S.I. engines is the de-activation of some cylinders at partial load, through the cut-out of fuel metering and a specific control of the airflow. Thanks to the ensuing reduction of throttling losses (the active cylinders operate at a much higher load), fuel consumption can be reduced, without any negative perception from the driver. Such a technique has been already applied successfully on some production engines, at the cost of some additional complication on the valve-train system.The application analyzed in this study is a little bit different, being aimed to reduce both fuel consumption and emissions, with a minimum impact on engine design. Larger fuel savings may be obtained by coupling the cylinder de-activation with VVT.However, the most important advantage of the modular engine concept proposed in this paper is in terms of emissions: this study demonstrates that the light-off time of the catalysts may be strongly reduced, and a further improvement is obtained by doubling the effective surface of the catalytic bed.The study has been carried out on a conventional SI 4.2L V8 engine. The first step of the analysis has been the experimental validation of a 1D-CFD model of the engine, achieved with a very good accuracy at both full and partial load. Then, the engine has been simulated on a grid of 15 operating points, representing the usage in the New European Driving cycle. The following configurations have been analyzed and compared to the base engine: 4 active cylinders, 3 active cylinders; 4 active cylinders and optimization of valve timings; 3 active cylinders and optimization of valve timings
Choking hypoxia-inducible factor l alpha: A novel mechanism for connective tissue growth factor inhibition of angiogenesis
No full textThe Modular Engine Concept: a Cost Effective Way to Reduce Pollutant Emissions and Fuel Consuption
No full textA promising technique to enhance fuel efficiency of large capacity S.I. engines is the de-activation of some cylinders at partial load, through the cut-out of fuel metering and a specific control of the airflow. Thanks to the ensuing reduction of throttling losses (the active cylinders operate at a much higher load), fuel consumption can be reduced, without any negative perception from the driver. Such a technique has been already applied successfully on some production engines, at the cost of some additional complication on the valve-train system. The application analyzed in this study is a little bit different, being aimed to reduce both fuel consumption and emissions, with a minimum impact on engine design. Larger fuel savings may be obtained by coupling the cylinder de-activation with VVT. However, the most important advantage of the modular engine concept proposed in this paper is in terms of emissions: this study demonstrates that the light-off time of the catalysts may be strongly reduced, and a further improvement is obtained by doubling the effective surface of the catalytic bed. The study has been carried out on a conventional SI 4.2L V8 engine. The first step of the analysis has been the experimental validation of a 1D-CFD model of the engine, achieved with a very good accuracy at both full and partial load. Then, the engine has been simulated on a grid of 15 operating points, representing the usage in the New European Driving cycle. The following configurations have been analyzed and compared to the base engine: 4 active cylinders, 3 active cylinders; 4 active cylinders and optimization of valve timings; 3 active cylinders and optimization of valve timings
Metabolic regulation and redox activity as mechanisms for angioprevention by dietary phytochemicals
No full text
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
- …
