TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 CONT

Conventional airborne gravimeters are essentially one-axis instruments which determine the magnitude of gravity by using a highly accurate accelerometer in flight to measure the magnitude of gravity along the local vertical. Although horizontal accelerometers are used on the platform, they are generally of poorer accuracy and are only suitable for supporting the alignment process. They cannot give the direction of the vertical with comparable accuracy. Thus, the term scalar gravimetry is used in this case. This is different with airborne gravity systems based on the principle of measuring the specific force vector by a three-axes inertial system and the aircraft acceleration vector by differential GPS. In this case, the three accelerometers of the inertial system are of the same accuracy and the three acceleration components of the aircraft show only small differences in accuracy due to the geometry of the GPS constellation. Thus, three components of each vector can be estimated with high accuracy and the full gravity disturbance vector can be obtained by differencing the specific force and the aircraft acceleration vector.  2, fiche 1, Anglais, - specific%20force%20vector

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 CONT

Imaginons un véhicule totalement coupé du monde extérieur en ce qui concerne : Les télécommunications; les émissions d'onde de toute sorte (électromagnétiques, acoustiques, etc. ...). Donc ne pouvant rien émettre ni rien recevoir. Mais : autonome en énergie. Pouvant emporter tout type de connaissances (disques, livres, CDROM, mémoire informatique ,..). Pouvant utiliser tous moyens de calculs imaginables. Disposant de moyens expérimentaux de tout type, mais autonomes. Que peut-on connaître du mouvement de ce vehicule ? Réponse : «Principe de relativité de Galilée-Einstein». Il est possible de mesurer à bord du véhicule deux vecteurs : Le vecteur rotation instantanée du véhicule par rapport au référentiel absolu. Le vecteur force spécifique f et rien d'autre.  1, fiche 1, Français, - vecteur%20force%20sp%C3%A9cifique

Fiche 1,  Justifications,  Espagnol