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| 2. |
- Rieutord, M, et al.
(author)
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A simulation of solar convection at supergranulation scale
- 2002
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In: Nuovo Cimento C. Colloquia on Physics. - 1124-1896. ; 25:5-6, s. 523-528
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Journal article (peer-reviewed)abstract
- We present here numerical simulations of surface solar convection which cover a box of 30 x 30 x 3.2 Mm(3) with a resolution of 315 x 315 x 82, which is used to investigate the dynamics of scales larger than granulation. No structure resembling supergranulation is present; possibly higher Reynolds numbers (i.e. higher numerical resolution), or magnetic fields, or greater depth are necessary. The results also show interesting aspects of granular dynamics which are briefly presented, like extensive p-mode ridges in the k-w diagram and a ringlike distribution of horizontal vorticity around granules. At large scales, the horizontal velocity is much larger than the vertical velocity and the vertical motion is dominated by p-mode oscillations.
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| 3. |
- Rieutord, M, et al.
(author)
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Are granules good tracers of solar surface velocity fields?
- 2001
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In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 377, s. 14-17
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Journal article (peer-reviewed)abstract
- Using a numerical simulation of compressible convection with radiativetransfer mimicking the solar photosphere, we compare the velocity fieldderived from granule motions to the actual velocity field of the plasma.We thus test the idea that granules may be used to trace large-scalevelocity fields at the sun's surface. Our results show that this isindeed the case provided the scale separation is sufficient. We thusestimate that neither velocity fields at scales less than 2500 km nortime evolution at scales shorter than 0.5 hr can be faithfully describedby granules. At larger scales the granular motions correlate linearlywith the underlying fluid motions with a slope of ≲2 reachingcorrelation coefficients up to ~ 0.9.
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| 4. |
- Wedemeyer, S., et al.
(author)
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3-D hydrodynamic simulations of the solar chromosphere
- 2003
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In: Astronomical Notes - Astronomische Nachrichten. - : Wiley. - 0004-6337 .- 1521-3994. ; 324:4, s. 410-411
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Journal article (peer-reviewed)abstract
- We present first results of three-dimensional numerical simulations ofthe non-magnetic solar chromosphere, computed with the radiationhydrodynamics code CO5BOLD. Acoustic waves which are excitedat the top of the convection zone propagate upwards into thechromosphere where the waves steepen into shocks. The interaction of thewaves leads to the formation of complex structures which evolve on shorttime scales. Consequently, the model chromosphere is highly dynamical,inhomogeneous, and thermally bifurcated.
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| 5. |
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| 6. |
- Åström, Karl Johan, et al.
(author)
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Control in an Information Rich World: Report of the Panel on Future Directions in Control, Dynamics, and Systems
- 2003
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Book (other academic/artistic)abstract
- The field of control provides the principles and methods used to design physical and information systems that maintain desirable performance by sensing and automatically adapting to changes in the environment. This report spells out some of the prospects for control in the current and future technological environment, describes the role the field will play in military, commercial, and scientific applications over the next decade, and recommends actions required to enable new breakthroughs in engineering and technology through the application of control research. This brief yet thorough report provides renewed vision, a detailed list of new application areas, and specific recommendations for future research directions in control, dynamics, and systems, compiled by experts in the field.
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