| 1. |
- Mazur, G. P., et al.
(författare)
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Towards modeling quasi-periodic oscillations of microquasars with oscillating slender tori
- 2013
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 554
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Tidskriftsartikel (refereegranskat)abstract
- Context. One of the often discussed models for high-frequency quasi-periodic oscillations of X-ray binaries is the oscillating torus model, which considers oscillation modes of slender accretion tori. Aims. Here, we aim at developing this model by considering the observable signature of an optically thick slender accretion torus subject to simple periodic deformations. Methods. We compute light curves and power spectra of a slender accretion torus subject to simple periodic deformations: vertical or radial translation, rotation, expansion, and shear. Results. We show that different types of deformations lead to very different Fourier power spectra and therefore could be observationally distinguished. Conclusions. This work is a first step in a longer term study of the observable characteristics of the oscillating torus model. It gives promising perspectives on the possibility of constraining this model by studying the observed power spectra of quasi-periodic oscillations.
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| 2. |
- Grahn, Markus, 1978, et al.
(författare)
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A Diesel Engine Management System Strategy for Transient Engine Operation
- 2013
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823434 ; 7:1, s. 1-6
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Konferensbidrag (refereegranskat)abstract
- A strategy for diesel engine management systems has been introduced and evaluated. The strategy calculates set points for engine management system controllable quantities with an aim to minimize fuel consumption for a given engine speed and requested torque profile, while keeping accumulated emissions below given limits. The strategy is based on existing methodology for steady-state engine operation, but extended to handle transient effects in the engine caused by dynamics in the air system. The strategy has been evaluated using a simulation model of a diesel engine system. The model estimates fuel consumption together with NOX and soot emissions for a transient simulation cycle depending on set points in the engine management system for boost pressure, oxygen fraction in the intake manifold, and injection timing. For the transient simulation scenario used in this paper and with given limits on accumulated emissions, the strategy has been shown to decrease fuel consumption with up to 0.7% compared to a strategy that is based only on steady-state engine operation.
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