1,720,960 research outputs found
Optimal control of aftertreatment electric heaters for mild hybrid vehicles during cold start
No full textHybrid electric on-road vehicles are gradually replacing their fossil fuel counterparts. Meanwhile, exhaust aftertreatment systems integrate new degrees of freedom, for example, heating capabilities. Therefore, this paper proposes an optimal control method to minimize the fuel consumption and the tailpipe emissions of a mild hybrid electric vehicle (mHEV) equipped with an electric aftertreatment system heater. The optimal control of the heating unit is formulated using the Pontryagin maximum principle, from which a sub-optimal bang-bang strategy can be derived. Results are presented in simulation for an mHEV with a selective catalytic reduction system equipped with an electric heating device
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
A multi-level cooperative strategy for reducing fuel consumption and transient pollutant emissions of hybrid electric vehicles
Get PDFDiese Doktorarbeit untersucht eine mehrstufige Energiemanagementstrategie zur Optimierung der Drehmomentaufteilung und Gangwahl für Hybridfahrzeuge mit Verbrennungsmotor (HEVs). Sie präsentiert drei wesentliche Beiträge, die jeweils in Fachpub- likationen detailliert beschrieben sind und darauf abzielen, den Kraftstoffverbrauch und die Schadstoffemissionen in HEVs weiter zu reduzieren. Während die Hybridisierung von Fahrzeugen bereits erfolgreich zur Senkung des Kraftstoffverbrauchs eingesetzt wird, sind neue Herausforderungen, vor allem bezüglich der Minimierung von Schadstoffemissionen, entstanden.Der erste Beitrag dieser Arbeit zielt auf die systematische Kooperation zwischen den Reglern und den Komponenten des Antriebsstranges ab. Die Kooperation wird dabei durch parametrische Regler erzielt, die die Einflüsse der anderen Regler bei der Aktualisierung der Reglerparameter berücksichtigen. Angewendet auf ein HEV zeigt die Methode eine erhebliche Kraftstoffreduktion durch verbesserte Zusammenarbeit zwischen den Reglern für Motor und Getriebe. Der zweite Beitrag konzentriert sich auf die Modellierung und Minimierung von Schadstoffemissionen während transienter Betriebszustände. Hier wird eine generische Optimierungsmethode vorgestellt, die die transienten Betriebszustände basierend auf einer funktionalen Darstellung der Stellgrößen berücksichtigt. Angewandt auf ein Diesel-Hybridfahrzeug zeigt die Methode eine signifikante Reduktion der transienten Emissionen dank gleichmäßigeren Betrieb. Der letzte Beitrag stellt ein generisches prädiktives Reglerdesign für die präzise Aktuatorregelung der Antriebskomponenten vor. Eine modulare Vorsteuerung, die basierend auf Messdaten identifiziert wurde und für nichtlineare Systeme geeignet ist, wird zur Regelung des Luftpfads eines Dieselmotors eingesetzt. Dieser Regler liefert vergleichbare Ergebnisse zur optimalen Lösung, jedoch mit deutlich geringerem Rechenaufwand.Die Beiträge dieser Arbeit wurden durch Simulationen mit detaillierten und experimentell validierten Plattformen überprüft. Die Ergebnisse unterstreichen die Bedeutung der Komponentenkooperation und der Berücksichtigung transienter Betriebszustände bei der effektiven Reduzierung von Kraftstoffverbrauch und Schadstoffemissionen. Dank ihrer Modularität können die entwickelten Lösunge auf verschiedene HEV-Architekturen und Komponentenkonfigurationen angewendet werden. Anhand spezifischer Fallstudien zeigt diese Arbeit signifikante eduktionen der Schadstoffemissionen bei Hybridfahrzeugen mit Verbrennungsmotoren.This PhD thesis investigates a multi-level energy management strategy to optimize torque distribution and gear selection of hybrid electric vehicles (HEVs) with an internal combustion engine. The thesis presents three significant contributions, each detailed in a dedicated journal publication, to further reduce fuel consumption and pollutant emissions of HEVs. While hybridization has long been recognized for its potentialto lower fuel consumption, new challenges have emerged, particularly in minimizingpollutant emissions to achieve cleaner transportation.The first contribution of this thesis is the systematic cooperation between control loops and powertrain components. This cooperation is achieved using parametric controllers, where the update of each controller’s parameters considers the reaction of the other con- trollers. Applied to an HEV, the proposed method demonstrates notable fuel reduction through enhanced collaboration between torque split and gear selection controllers.The second contribution focuses on modeling and minimizing pollutant emissions during transient operations. This thesis introduces a generic transient optimization method based on a functional representation of the control variables. The proposed optimization method is applied to control the engine torque, significantly reducing transient emissions of a diesel HEV thanks to smooth engine operations.The last contribution introduces a generic predictive controller design for precise control of powertrain component actuators, ensuring accurate tracking of reference trajectories. A modular feedforward controller structure, identified from measurement data and suit- able for nonlinear systems, is proposed and applied to control the air path of a diesel engine. This identified controller yields results comparable to an optimal solver but with substantially lower computational complexity.The contributions of this thesis have been validated through simulations on detailed and experimentally validated platforms. The findings highlight the critical role of com- ponent cooperation and transient operations in effectively reducing fuel consumption and pollutant emissions. Emphasizing modularity, the developed solutions are applicable to various HEV architectures and component configurations. Applied to specific case studies, this thesis demonstrates significant reductions in pollutant emissions for hybrid electric vehicles with combustion engines
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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