1,720,959 research outputs found
Dynamics of hybrid PM/EM electromagnetic valve in SI engines
Get PDFSome previous studies demonstrated the advantages of electromagnetic valve train (EMV) for controlling variable valve timing (VVT) in SI engines. EMV allows valve timings and duration events are optimized in wide operating ranges. However, conventional EMV with solenoid actuator consumes a larger amount of energy in catching the valve at engine start and in keeping valve at open or closed position. A new EMV with hybrid permanent magnet and electromagnetic coil (PM/EM) has been proposed in this paper. An engine model with new EMV has been built to simulate the valve dynamics. Additionally, the effects of the flow gas resistance and damp coefficient have also been examined and analyzed. The results show that the new EMV can satisfy the valve dynamics in transition time, valve velocity, acceleration, energy consumption, etc. in controlling valve timing for SI engines
PROPOSING A VALVE TRAIN SYSTEM FOR CYLINDER DEACTIVATION IN SI ENGINES
No full text Cylinder deactivation method can provide many advantages in improving emissions and fuel consumption at various load ranges in spark ignition (SI) engines. The study proposes a design valve train that can control the deactivation of cylinder in an inline SI engine with four cylinders. The proposed design, which is an improvement on the conventional valve train in the engine, can deactivate one- or two-cylinder mode depending on part or medium load in a vehicle. The results show that cylinder deactivation can reduce about 13–15% of fuel consumption compared with the conventional engine. The concentration of CO reduces by 15%, whereas HC decreases to about 8% when SI engine operates with different cylinder deactivation modes. </jats:p
A NEW ELECTROMAGNETIC VALVE TRAIN WITH PM/EM ACTUATOR IN SI ENGINES
No full text This paper proposes a new electromagnetic valve train (EMV), which uses hybrid permanent magnet and electromagnetic coil (PM/EM). The new EMV is characterized by a special structure, simple actuator as well as optimal parameter designs. This EMV brings many benefits, such as valve dynamic, actuator control, and low operation energy consumption, etc. The simulation results show that this EMV achieves a 15% volume reduction and a 20% enhancement in holding force by special armature design. Additionally, the estimated energy consumption of EMV operation for the proposed EMV indicates that this EMV has the lowest operating energy compared with other EMVs. </jats:p
Dynamics of hybrid PM/EM electromagnetic valve in SI engines
Get PDFSome previous studies demonstrated the advantages of electromagnetic valve train (EMV) for controlling variable valve timing (VVT) in SI engines. EMV allows valve timings and duration events are optimized in wide operating ranges. However, conventional EMV with solenoid actuator consumes a larger amount of energy in catching the valve at engine start and in keeping valve at open or closed position. A new EMV with hybrid permanent magnet and electromagnetic coil (PM/EM) has been proposed in this paper. An engine model with new EMV has been built to simulate the valve dynamics. Additionally, the effects of the flow gas resistance and damp coefficient have also been examined and analyzed. The results show that the new EMV can satisfy the valve dynamics in transition time, valve velocity, acceleration, energy consumption, etc. in controlling valve timing for SI engines
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
The Optimal Strategies for Improving Efficiency in Camless Engines
No full textIn this paper, an unthrottled camless engine model, which equipped electromagnetic valvetrain (EMV), has been built for performance simulation of engine dynamics. The combination of the techniques of cylinder deactivation (CDA) and variable valve timing (VVT) has been examined for different engine speeds and engine loads. The results concluded that the mode of two-cylinder deactivation considerably improves the fuel consumption at low engine load. Meanwhile, the one-cylinder deactivation mode is an optimal fuel economy mode for medium engine load. The normal engine mode fairly satisfies the driving torque and fuel economy in a vehicle, and thus it fits the optimal mode for the full loads. Additionally, the results also show that the optimal intake valve closing (IVC) timing for different engine speeds and loads. The IVC timing depends on engine speed linearly while the optimal IVC timing insignificantly changes at different engine loads when CDA is applied. By the determined CDA-VVT strategy, a camless unthrottled engine can maintain high efficiency operation for different speeds and loads.</jats:p
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
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