| 1. |
- Andersen, Torben, et al.
(författare)
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A parallel integrated model of the Euro50
- 2004
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5497:1, s. 251-265
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Konferensbidrag (refereegranskat)abstract
- The Euro50 is an astronomical extremely large telescope for optical and infrared wavelength with a 50 m primary mirror. The telescope will have an elaborate control system ("live optics") to correct for atmospheric and telescope aberrations. To study and predict performance of the complete telescope system, an integrated model combining the structural model of the telescope, optics models, the control systems, and the adaptive optics has been established. Wind is taken into account on the basis of wind tunnel measurements and computer fluid dynamics calculations. Atmospheric aberrations are included using a seven-layer atmosphere model. The integrated model is written in Matlab and is run on a cluster computer to achieve acceptable execution times. Dedicated ordinary differential equation solvers have been written and a special toolkit for communication between Matlab processes on different nodes of the cluster computer has been set up. Preliminary results from the complete integrated model, including adaptive optics, are shown
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| 2. |
- Andersen, Torben, et al.
(författare)
-
Integrated modeling of the Euro50
- 2003
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5382:1, s. 366-378
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Konferensbidrag (refereegranskat)abstract
- The Euro50 is a proposed 50 m optical and infrared telescope. It will have thousands of control loops to keep the optics aligned under influence of wind, gravity and thermal loads. Cross-disciplinary integrated modeling is used to study the overall performance of the Euro50. A sub-model of the mechanical structure originates from finite element modeling. The optical performance is determined using ray tracing, both non-linear and linearized. The primary mirror segment alignment control system is modeled with the 618 segments taken as rigid bodies. Adaptive optics is included using a layered model of the atmosphere and sub-models of the wavefront sensor, reconstructor and controller. The deformable mirror is, so far, described by a simple influence function and a second order dynamical transfer function but more detailed work is in progress. The model has been implemented using Matlab/Simulink on individual computers but it will shortly be implemented on a Beowulf cluster within a trusted network. Communication routines between Matlab on the cluster processors have been written and are being benchmarked. Representative results from the simulations are shown
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| 3. |
- Andersen, Torben, et al.
(författare)
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Status of the Euro50 project
- 2004
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5489:1, s. 407-416
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Konferensbidrag (refereegranskat)abstract
- The Euro50 is an extremely large telescope for optical and infrared wavelength with a 50 m primary mirror. It has a segmented, aspherical primary mirror and an aspherical, deformable secondary in a Gregorian layout. A tentative conceptual design exists and has been documented in a study report. Recent activities have concentrated on the science case for extremely large telescopes in the 50 m class and on identification of potential technical "show stoppers". The science case investigation has identified four fields of particular interest. The studies of critical technical issues have concentrated on atmospheric dispersion effects for high-resolution adaptive optics for extremely large telescopes, and on the influence of wind and other disturbances on wavefront control. Wind load on the telescope, the primary mirror and the enclosure has been studied using wind tunnel measurements and computational fluid dynamics. The impact of wind on the total system has been investigated using an integrated model that includes the telescope structure, the primary mirror segment alignment system, the secondary mirror alignment system, and single conjugate adaptive optics using the deformable secondary mirror. The first, tentative results show that wind disturbances may be significant and that the task of correcting for wind residuals may be at least as large for the adaptive optics system as that of correcting for atmospheric aberrations. The results suggest that use of extremely large telescopes for observations of earth-like planets around nearby stars may imply a considerable challenge
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| 4. |
- Browne, Michael, et al.
(författare)
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Parallelization of MATLAB for Euro50 integrated modeling
- 2004
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Ingår i: Modeling and Systems Engineering for Astronomy (Proceedings of the SPIE). - : SPIE. - 081945429X ; 5497, s. 604-610
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Konferensbidrag (refereegranskat)abstract
- MATLAB and its companion product Simulink are commonly used tools insystems modelling and other scientific disciplines. A cross-disciplinaryintegrated MATLAB model is used to study the overall performance of theproposed 50m optical and infrared telescope, Euro50. However thecomputational requirements of this kind of end-to-end simulation of thetelescope's behaviour, exceeds the capability of an individualcontemporary Personal Computer. By parallelizing the model, primarily ona functional basis, it can be implemented across a Beowulf cluster ofgeneric PCs. This requires MATLAB to distribute in some way data andcalculations to the cluster nodes and combine completed results. Therehave been a number of attempts to produce toolkits to allow MATLAB to beused in a parallel fashion. They have used a variety of techniques. Herewe present findings from using some of these toolkits and proposedadvances.
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| 5. |
- Moraru, Dan, et al.
(författare)
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Integrated modeling of submillimeter radio telescopes
- 2002
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 4757, s. 169-173
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Konferensbidrag (refereegranskat)abstract
- Integrated models are inherently complex and often obscure to any but those who write them. Their usefulness can be greatly enhanced through well-structured, object-oriented design. A robust and computationally efficient Simulink/C++ library of optics, control, finite-element, and visualization routines for modeling radio telescope performance under various operating conditions is being developed and is described. The library is being developed in conjunction with an end-to-end model of the Atacama Large Millimeter Array (ALMA) antennas. The model includes the mechanical structure, optics, servos, and potential laser gyros, and can be used to investigate such issues as tracking performance, compliance with error budgets, wind sensitivity, and effectiveness of an internal metrology system. It will also be a good tool for comparison of different antenna designs.
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