Matra

About: Matra is a based out in . It is known for research contribution in the topics: Signal & Detector. The organization has 1330 authors who have published 1216 publications receiving 17967 citations.

SILEX final ground testing and in-flight performance assessment

Abstract: SILEX (Semi-Conductor Inter-satellite Link EXperiment) consists of one optical terminal on-board the French LEO observation satellite SPOT 4, and another on-board the European GEO telecommunication satellite ARTEMIS. While the first part of the SILEX verification plan had been oriented towards verification at equipment and subsystem levels, the final stages have mainly been devoted to terminal and system (terminals coupling effects) verification. During this final stage, a thermal vacuum test was conducted in a class 100- cleanliness environment with optical ground support equipment of outstanding performances. The obtained tests results, used to determine software compensations and verify optical and static pointing performances, have been entered into overall system simulation models to finalize flight performances budgets. In addition, systems tests were performed on each terminal with respective partner simulator to validate system simulation models and assess link performances and robustness and to verify communication bit error rate.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Micropaleontological observations on a Sphagnum bog in East Carpathian region - Testate amoebae (Rhizopoda: Testacea) and their potential use for reconstruction of micro- and macroclimatic changes

Abstract: We investigated the possibilities of reconstructing the hydrological history of an East Carpathian Sphagnum bog (Fenyves-tető, near Erzsebetbanya) based on the Testacea fauna and the humification. A Russian-type sampler was used to supply undisturbed cores of 400 cm in depth. The exotic marker method (Lycopodium clavatum as a marker) was used for quantitative estimation of the abundances. Humic acid concentration was measured by photometry. The age of the peat layers was determined by radiocarbon method. Altogether we identified 33 testate amoebae taxa; there were 10 taxa which were frequent in the samples and have remarkable faunistic and ecological significance. Based on the relative abundance of Testacea taxa, eight zones were identified. The following species were characteristic of dry conditions: Assulinamuscorum, Difflugiapulex, and Nebelamilitaris, while wet conditions were indicated by Amphitrema flavum and Hyalospheniapapilio. We found strong qualitative correlation between the humification and the relative frequencies of the testate amoebae. Major changes of the moisture conditions can be appropriately reconstructed from the quantitative and qualitative analysis of testate amoebae, and offer a good characterization for the rapid changes of the moisture conditions and the stable periods. We have demonstrated that the analysis of Testacea and the study of humification are useful for reconstructing hydrological changes.

Rotary permanent magnet electric motor with varying air gap between interfacing stator and rotor elements

Abstract: A permanent magnet motor is configured with selective variation of the radial distance between an interfacing pair of rotor permanent magnet and stator pole along the circumferential length of the pair The effects of cogging torque on the overall torque signature can be controlled by setting an appropriate air gap variation profile The stator pole and rotor magnet surfaces may be sloped with respect to each other, the angle therebetween being selected to obtain desired cogging torque compensation Other air gap variation profiles may include provision of concave surfaces, the degree of concavity being selectable

SILEX overview after flight terminals campaign

Abstract: The ESA program dedicated to Optical Communications development has allowed to qualify two terminals in 1994 and 1995. In 1995/96, the respective proto flight models have been integrated and tested, leading to in depth knowledge of the behavior of optical terminals in optomechanical, pointing and telecommunications fields for various environmental conditions. The paper describes the program and the associated major tests results at terminal level or in coupled configuration on SPOTIV spacecraft. Considerations for future application are given in order to identify SILEX feedback on MMS optical terminal product line for commercial market.