Additive manufacturing (AM) offers many advantages, including material savings, lightening, design freedom, function integration, etc. In the case of cellular materials, regular structures (lattice and honeycomb) are particularly important due to their ability to reduce weight. However, the design process and FEM analysis of this type of structure is very high time-consuming. In order to mitigate this problem, we propose a modelling method, called "Equivalent Continuum Material", based on the treatment of a cellular material as a continuous mass. This document describes the method and presents examples of applications, to facilitate and understand its use.
The High Optical Resolution Spectrograph (HORS) is a proposed high-resolution spectrograph for the
10-m Gran Telescopio Canarias (GTC) based on components from UES, a spectrograph which was in
use at the 4.2-m William Herschel Telescope (WHT) between 1992 and 2001.
HORS is designed as a cross-dispersed echelle spectrograph to observe in the range 380-800 nm with
a FWHM resolving power of about 50,000. HORS would operate on the GTC as a general-purpose
high-resolution spectrograph, and it would serve as a test-bed for some of the technologies proposed
for ESPRESSO – an ultra-high stability spectrograph planned for the Very Large Telescope (VLT) of
the European Southern Observatory.
The HORS spectrograph will be placed in the Coudé room, where it can enjoy excellent thermal and
mechanical stability, fiber fed from the Nasmyth focus, which is shared with OSIRIS. Inside the
spectrograph, incoming light will hit a small folder mirror before reaching the collimator. After a
second folder, the light will go through a set of three prisms and an Echelle grating before entering the
spectrograph camera and, finally, reaching the detector.
This manuscript contains a summary of the whole process that has transformed UES into HORS, with
all the mechanical and optical modifications that have been introduced to reach the final layout.
The GTC (Gran Telescopio Canarias) is an optical/IR telescope, with a 10,4 meter segmented primary, installed at the
Observatorio del Roque de Los Muchachos (ORM), at La Palma.
Past July 2007 it saw its First Light showing a very promising behaviour. The very good image quality achieved at that
an early stage of telescope commissioning is a direct consequence of the quality of its optics, the high performances of
its primary mirror control system, and the highly engineered telescope structure and servo system.
At present, we are advancing with the telescope commissioning whose first results are presented here. The two Day One
science instruments: OSIRIS and CanariCam are being prepared for installation and commissioning on the telescope.
Science verification are planned to be initiated by the end of 2008 and regular operation by March 2009.
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