The Sardinia Radio Telescope (SRT), located near Cagliari (Italy), is the world’s second largest fully steerable radio telescope endowed with an active-surface system. Its primary mirror has a quasi-parabolic shape with a diameter of 64 m. The configuration of the primary mirror surface can be modified by means of electro-mechanical actuators. This capability ensures, within a fixed range, the balancing of the deformation caused, for example, by loads such as self-weight, thermal effects and wind pressure. In this way, the difference between the ideal shape of the mirror (which maximizes its performances) and the actual surface can be reduced. In this paper the authors describe the characteristics of the SRT, the close-range photogrammetry (CRP) survey developed in order to set up the actuator displacements, and a finite element model capable of accurately estimating the structural deformations. Numerical results are compared with CRP measurements in order to test the accuracy of the model.

We give some upper bounds on the dimension of the kernel of the cup product map H 1 (X, C) ⊗ H 1 (X, C) → H 2 (X, C), where X is a compact Kähler variety without Albanese fibrations.2. If q = 2n, then dim ker φ ≤ 2c + 3 where q = 2 c (2b + 1), and b, c integers.3. If q = 5 and n = 2, then dim ker φ ≤ 14. * Partially supported by 1) PRIN 2005 "Spazi di moduli e teorie di Lie"; 2) Indam (GNSAGA); 3) Far 2006 (PV):"Varietà algebriche, calcolo algebrico, grafi orientati e topologici".

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We calculate the maximal dimension of linear spaces of symmetric and hermitian matrices with given high rank generalizing a well-known result of Adams et al. AMS (MOS) Subject Classification: 15A30 (55N15).