The flyby anomaly: A case for strong gravitomagnetism?

In the last two decades an anomalous variation in the asymptotic velocity of spacecraft performing a flyby manoeuvre around Earth has been discovered through careful Doppler tracking and orbital analysis. No viable hypothesis for a conventional explanation of this effect has been proposed and its origin remains unexplained. In this paper we discuss a strong transversal component of the gravitomagnetic field as a possible source of the flyby anomaly. We show that the perturbations induced by such a field could fit the anomalies both in sign and order of magnitude. But, although the secular contributions to the Gravity Probe B experimental results and the Lense Thirring effect in geodynamics satellites can be made null, the detailed orbital evolution is easily in conflict with such an enhanced gravitomagnetic effect.Acedo Rodríguez, L. (2014). The flyby anomaly: A case for strong gravitomagnetism?. Advances in Space Research. 54(4):788-796. doi:10.1016/j.asr.2014.04.014S78879654

Phenomenology of the Lense-Thirring effect in the Solar System

Recent years have seen increasing efforts to directly measure some aspects of the general relativistic gravitomagnetic interaction in several astronomical scenarios in the solar system. After briefly overviewing the concept of gravitomagnetism from a theoretical point of view, we review the performed or proposed attempts to detect the Lense-Thirring effect affecting the orbital motions of natural and artificial bodies in the gravitational fields of the Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of the impact of several sources of systematic uncertainties of dynamical origin to realistically elucidate the present and future perspectives in directly measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in Astrophysics and Space Science (ApSS). Some uncited references in the text now correctly quoted. One reference added. A footnote adde

Painting Scene Recognition Using Homogenous Shapes

Abstract. This paper addresses the problem of semantic analysis of paintings by automatic detection of the represented scene type. The so-lution comes as an incipient effort to fill the gap already stated in the literature between the low level computational analysis and the high level semantic dependent human analysis of paintings. Inspired by the way humans perceive art, we first decompose the image in homogenous regions, follow by a step of region merging, in order to obtain a painting description by the extraction of perceptual features of the dominant ob-jects within the scene. These features are used in a classification process that discriminates among 5 possible scene types on a database of 500 paintings