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Vargas J.,Instituto National Of Tecnica Aeroespacial | Gonzalez-Fernandez L.,Instituto National Of Tecnica Aeroespacial | Antonio Quiroga J.,Complutense University of Madrid | Belenguer T.,Instituto National Of Tecnica Aeroespacial
Optics Letters | Year: 2010

We demonstrate a method to calibrate a Shack-Hartmann sensor as an orthographic camera. This calibration method permits us to obtain the distance, the rotation matrix between the microlens array and CCD imaging planes, and the projection matrix, which models the projection of the incoming rays to the CCD imaging plane. The proposed calibration method introduces a very compact matrix notation and allows wavefront reconstruction without an explicit centroid search between the reference and distorted spot diagrams. We show a set of simulations in code V that prove the effectiveness of the proposed method. © 2010 Optical Society of America.

Tamayo R.,Instituto National Of Tecnica Aeroespacial | Alonso J.,Complutense University of Madrid | Jimenez J.J.,Instituto National Of Tecnica Aeroespacial | Arruego I.,Instituto National Of Tecnica Aeroespacial | Guerrero H.,Instituto National Of Tecnica Aeroespacial
Journal of Aerospace Computing, Information and Communication | Year: 2010

The present work is a study on the propagation channel (physical layer) for wireless infrared communications in intra-satellite environments. Substituting cables and connectors with optical links inside a spaceborn platform offers many advantages and represents some technical challenges. We show analytical calculations, simulations, and experimental results for reflection models for aerospace materials, as well as wavelength division multiple access techniques for channel multiplexing. Improvements in the selection and optimization of emitter-detector pairs are also presented.

Ponsin J.,Instituto National Of Tecnica Aeroespacial | Fraysse F.,Technical University of Madrid | Gomez M.,Technical University of Madrid | Cordero-Gracia M.,Technical University of Madrid
Aerospace Science and Technology | Year: 2015

We present the development and validation of an output-based mesh adaptation approach which combines the adjoint methodology with the τ-estimation technique for truncation error estimation. The approach relies on the use of an auxiliary coarse mesh to estimate the functional error and drive the mesh adaptation. The functional is estimated with an error representation formula given by the inner product of the adjoint solution and the discrete residual of the exact solution, which is approximated by the τ-estimation method. This method avoids the use of an embedded fine grid which is the common approach in the adjoint-based adaptation methods. Furthermore, it also allows to reduce the computational time overhead per adaptation step because the adjoint solution is obtained on a coarser mesh level. The effectiveness of the method is demonstrated in the framework of unstructured-mesh finite volume discretization for two-and three-dimensional Euler flows and comparisons against several mesh adaptation approaches are shown. © 2015 Elsevier Masson SAS. All rights reserved.

Cordero-Gracia M.,Technical University of Madrid | Gomez M.,Technical University of Madrid | Ponsin J.,Instituto National Of Tecnica Aeroespacial | Valero E.,Technical University of Madrid
Aerospace Science and Technology | Year: 2012

The necessity to modify a pre-existing computational mesh is a common requirement in many areas of computational fluid dynamics like aeroelasticity, optimization, etc. Here, we propose an approach to develop an efficient numerical mesh movement tool. The strategy relies on a three steps procedure: (i) generation of an octree decomposition of the geometry, (ii) definition of small interpolation domains, and (iii) application of local interpolation algorithms. Deformation is propagated from the moving boundaries towards the far field in a way similar to an advancing front methodology, which ensures continuity and numerical viability. The method can be applied to any type of mesh: structured, multiblock structured, unstructured and hybrid because it only uses geometric position of the mesh points, regardless of the particular mesh connectivities. The interpolation tool is based on radial basis functions. It will be showed that the method is very robust and generates a mesh with similar quality parameters as the original, it is computationally very efficient and can be easily parallelized. © 2011 Elsevier Masson SAS. All rights reserved.

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