1,720,964 research outputs found
Reduction of fuel consumption and pollutant emissions from vehicles: implementation of low-temperature diesel combustion and development of an advanced central tire inflation system
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Potential impact of active tire pressure management on fuel consumption reduction in passenger vehicles
No full textActive tire pressure management, through an automatic, electro-pneumatic, central tire inflation system, is here proposed as a means of improving fuel consumption in passenger vehicles, as well as safety and drivability. A brief description of the active tire pressure control system, which has been set up at the Politecnico di Torino, is provided as a reference. Different strategies, aimed at reducing rolling resistance, through inflation pressure management, under specific vehicle working conditions, are then illustrated. The fuel benefits that can be achieved by adopting these strategies in passenger vehicles are studied by means of computer simulations using a proprietary software for vehicle performance and fuel consumption estimation. Coast-down coefficients, evaluated experimentally during deceleration tests on a closed track, are generally available at the reference tire pressure prescribed by the original equipment manufacturer of the vehicle. These fixed coefficients can then be used to describe the vehicle in simulation environments. LaClair’s relation, which illustrates the influence of tire inflation pressure on rolling resistance, has therefore been used to recalculate the coast-down coefficients as functions of the tire pressure. This has allowed fuel consumption simulations to be performed on the reference B-segment passenger car under different working conditions. In particular, the following pressure management strategies have been studied: adaptation of the inflation pressure to the vertical load, variation of the inflation pressure during tire warm-up, and adjustment of the inflation pressure, according to the average speed (urban/highway driving). The performed simulations have demonstrated that if the standard tire pressure is maintained, fuel consumption could be reduced by up to 2% in real-world driving; further advantages could be obtained by varying the target pressure as a function of the current working conditions of the vehicle
Analisi sperimentale di una combustione diesel non convenzionale - Ottimizzazione mediante l'applicazione di tecniche statistiche
No full textUna combustione ad elevato grado di premiscelazione è stata implementata in un motore diesel Euro VI, per diminuire contemporaneamente le emissioni di NOx e PM. Tecniche statistiche hanno permesso di ridurre il numero dei test mantenendo un elevato grado di predittvità dell'interazione dei parametri del motore su emissioni, consumi e rumore. Sono state ridotte le emissioni di NOx del 90% e di PM del 99%, a scapito di un aumento del consumo di combustibile e delle emissioni di HC e CO
Preliminary Optimization of the PCCI Combustion Mode in a Diesel Engine through a Design of Experiments
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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
Impact assessment of an intelligent central tire inflation system for passenger cars
Full text linkTire inflation pressure affects vehicle energetic balance, as well as road safety. These issues are particularly critical due to the low attention paid by the drivers to tire maintenance. Tire pressure monitoring systems are used to alert the drivers in case of low pressure, but higher benefits could be obtained through a completely autonomous on-board system capable of setting the optimal tire pressure according to current working conditions and of automatically inflate or deflate tires. Basing on computer simulations on fuel economy of a reference mid-size diesel passenger car, and referring to statistical data on vehicle use, the potentialities of such a device is evaluated on an annual mission. The results are then extended to the whole European fleet to provide an estimation of the potential benefits that could be obtained through massive adoption of this solution. The impact is evaluated through an economical evaluation of: fuel savings, reduction of social cost of carbon emissions, increase of tire life and reduction of costs related to crashes produced by improper tire pressure
Active Tire Pressure Control (ATPC) for Passenger Cars: Design, Performance, and Analysis of the Potential Fuel Economy Improvement
No full textActive tire pressure control (ATPC) is an automatic central tire inflation system (CTIS), designed,
prototyped, and tested at the Politecnico di Torino, which is aimed at improving the fuel consumption,
safety, and drivability of passenger vehicles. The pneumatic layout of the system and the
designed solution for on board integration are presented. The critical design choices are explained
in detail and supported by experimental evidence. In particular, the results of experimental tests,
including the characterizations of various pneumatic components in working conditions, have been
exploited to obtain a design, which allows reliable performance of the system in a lightweight
solution. The complete system has been tested to verify its dynamics, in terms of actuation time
needed to obtain a desired pressure variation, starting from the current tire pressure, and to validate
the design.
The effect of the dynamics of the system has also been studied by simulating some system
actuations under certain specific working conditions and by quantifying the effect of the actuation,
in terms of the reduction that can be obtained on fuel consumption.
Finally, on the basis of previous works on the effect of tire pressure on fuel consumption, and
on the benefits that could be obtained by means of smart tire pressure management strategies, the
potential fuel reduction provided by the studied technology has been estimated through computer
simulations. According to the performed calculations, it has been found that the ATPC system could
reduce fuel consumption by 1.7% on an annual basis with respect to a common underinflation case.
This corresponds to a reduction of 18 million barrels of fuel and 6,700,000 metric tons of CO2 emitted
per year in the United States alone
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
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