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.

The SILEX optical interorbit link experiment

Abstract: The implementation of communication links between a low earth-orbiting satellite and a geostationary one, or between two geostationary satellites, will lead to significant improvements in the performance of space communication systems. Optical technology is attractive for these applications when high-data-rateCommunication is required. The European Space Agency (ESA) has therefore instigated and in-ordbit demonstration project known as SILEX (semiconductor laser intersatellite link experiment) using a pre-operational link between the French SPOT-4 low earth orbit satellite and the ESA Advanced Relay and Technology Mission Satellite(ARTEMIS). Such and optical communication system brings some new and challenging requirements. In particular, the communication beam, which has a divergence of around 6 μrad, must achieve and maintain a very demanding pointing accuracy in the presence of both host satellite vibration and relative satellite motion. This paper provides an overview of the SILEX project and describes a novel pointing mechanism.

Continuity properties of the normal cone to the level sets of a quasiconvex function

Abstract: Two main properties of the subgradient mapping of convex functions are transposed for quasiconvex ones. The continuity of the functionx→‖∇f(x)‖−1∇f(x) on the domain where it is defined is deduced from some continuity properties of the normal coneN to the level sets of the quasiconvex functionf. We also prove that, under a pseudoconvexity-type condition, the normal coneN(x) to the set {x:f(x)⩽f(x)} can be expressed as the convex hull of the limits of type {N(x n)}, where {x n} is a sequence converging tox and contained in a dense subsetD. In particular, whenf is pseudoconvex,D can be taken equal to the set of points wheref is differentiable.

MÉTÉOR: An Industrial Success in Formal Development

Abstract: A new line of metro in Paris is going to open in August 1998. This line, operated by RATP, is equipped with the METEOR system, which enables fully automatic driverless trains as well as conventional trains. The safety critical software of the METEOR system was formally developed in 1996-1997 using the B method by Matra Transport International. The development includes : - abstract models of the software components - refinement design to concrete models - automatic translation into Ada code.

Heavy ion induced single hard errors on submicronic memories (for space application)

Abstract: Recent heavy ion testing of high density SRAMs (static random access memories) has revealed radiation-induced hard errors: the errors show up as jammed bits in the memory. This phenomenon appears for high LET (linear transform energy) values. The single hard errors (SHEs) uniformly spread on the memory plane, disappear through UV escape, and anneal very slowly. It is believed that the errors are due to local ionizing dose deposition. This phenomenon could become an important limitation to space electronics design with the growing integration of the devices. The authors describe the test setup, the hard error characterization, and some first theoretical considerations for explaining this phenomenon. >

Three-Axes Missile Autopilot Design: From Linear to Nonlinear Control Strategies

Abstract: A three-axes skid-to-turn missile autopilot design is presented. The modeling is that of a missile developed by AerospatialeMatraMissiles.Variouscontrollawshavebeencomparedinordertoestimatetheirpotentialandtheir applicability: classical linear time-invariant control and static and dynamic approximate input-output linearizing feedbacks. The robustness is studied, and the best results, in terms of stability, performance, and robustness, are shown to be obtained by using a special type of nonlinear dynamic control. The simulation results are explained using a table of comparison.