1,720,967 research outputs found
Hybrid and Electric Vehicles Optimal Design and Real-time Control based on Artificial Intelligence
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Optimal mesh discretization of the dynamic programming for hybrid electric vehicles
No full textThe maximum fuel economy achievable by a hybrid electric vehicle (HEV) on a specific driving mission can be attained through the identification of the best admissible control policy. In the last years, the Dynamic Programming
(DP) algorithm has proved to be capable of identifying the optimal policy once the definition of a proper computational grid is performed. As far as the refinement of the latter is concerned, the results produced
by the selected control strategy can be negatively affected by a rough mesh due to approximation errors chains. Still, too fine a grid can lead to unreasonable CPU times. Hence, a method for automatically detecting the optimal
mesh discretization with respect to different HEV simulations should be found. In the present paper, a selfadaptive statistical approach based on a proper management of any admissible battery energy variation is
developed to significantly improve the calculation times required for HEV architectures while still attaining the best possible accuracy in terms of CO2 emissions as well as total cost of ownership (TCO). For the purpose, a lowthroughput battery model has been taken into account so that the number of cells, the curve power limit and the energy content could be accounted for. The proposed method was tested on two parallel HEVs belonging to
different categories, specifically a passenger car and a heavy-duty vehicle. The robustness of the method was also assessed for by testing the effects of a variation in the number of control variables within the simulation
Development and assessment of a random-forest model for real-time prediction of diesel engine-out particulate matter emissions
No full textThe containment of air pollution resulting from transportation sector is worldwide considered as one of the most important targets to be still achieved. The emissions of particulate matter (PM) assume a relevant role when Diesel engine-based vehicles are concerned. In the present paper, an innovative model for the prediction of engine-out emitted PM mass has been developed and assessed on two different Diesel engines. A semi-empirical approach is defined as reference model and initially validated through the ISO/IEC Guide 98-3:2008 procedure and its potentials of the being coupled to a predictive combustion model are demonstrated. Then, relying on the findings of the semi-empirical approach, a Random Forest (RF) algorithm has been thoroughly analysed and selected as a promising solution for real-time testing with on-line computed variables. Furthermore, an automatic feature selection and calibration procedure of the algorithm hyper-parameters has been developed. Very interesting performances were recorded as the reference model prediction accuracies were reproduced and comparable results were obtained when only ECU-measured variables were considered. The presented Random Forest model can be intended to be part of a pollution-oriented real-time powertrain control strategy that could on accurate and repeatable PM estimations
A New Control-Oriented Semi-Empirical Approach to Predict Engine-Out NOx Emissions in a Euro VI 3.0 L Diesel Engine
Full text linkThe present study is focused on the development of a new control-oriented semi-empirical model to predict nitrogen oxide (NOx) emissions in a light-duty diesel engine under both steady-state and transient conditions. The model is based on the estimation of the deviations of NOx emissions, with respect to the nominal engine-calibration map values, as a function of the deviations of the intake oxygen concentration and of the combustion phasing. The model also takes into account the effects of engine speed, total injected quantity, and ambient temperature and humidity. The approach has been developed and assessed on an Fiat Powertrain Technologies (FPT) Euro VI 3.0 L diesel engine for light-duty applications, in the frame of a research project in collaboration with FPT Industrial. The model has also been tested on a rapid prototyping device, and it was shown that it requires a very short computational time, thus being suitable for implementation on the Engine Control Unit (ECU) for real-time NOx control tasks
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
Influence of the reward function on the selection of reinforcement learning agents for hybrid electric vehicles real-time control
No full textAppropriate 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
- …
