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.

Residual stresses in silicon dioxide thin films prepared by reactive electron beam evaporation

Abstract: In this study, residual stresses and optical properties of SiO2 films prepared by reactive electron gun evaporation have been investigated as a function of process parameters. The purpose of this work was to find process conditions resulting in SiO2 stress free films or in a stress level balancing the high index material stress in a multilayer structure. We have found that stress in SiO2 films becomes more compressive with conditions resulting in denser coatings (such as high substrate temperatures or low gas pressures). Using an in situ measurement technique, stress stabilities of these films were also studied under vacuum or heated environments. These experiences have confirmed the porous structure of evaporated coatings and have underlined the great importance of water in their final state of stress.

Multi-port microwave coupler utilized in a beam forming network

Abstract: A multi-port microwave coupler has six input ports In 1, In 2, In 3, In 4, In 5 and In 6 and six output ports Out 1, Out 2, Out 3, Out 4, Out 5 and Out 6 and is synthesized from nine 2×2 90° hybrid couplers which are arranged as three sets, that is a first set A, B and C, a second set D, E and F and a third set G, H and I. A first group of transmission lines interconnect the first and second sets of hybrid couplers, and a second group of transmission lines interconnect the second and third sets of hybrid couplers The first and third sets of couplers each give a 3 dB power reduction, but the second set give a 1:2 power split between their outputs. Three 90° phase shift, devices X, Y and Z correct the phase of the signals in three of the transmission lines of the second group. When equal amplitude signals are applied to all of the input ports, the combined signal can be directed to any one of the output ports by appropriately selecting the respective phases of the input signals. The first and second groups of transmission lines can be arranged as respective transmission rings so that all cross-overs in the transmission lines are avoided thereby providing a planar realization of a 6×6 multi-port microwave coupler. The invention is of application to higher order n×n multi-port microwave couplers where n=2 p ×2 q with both p and q as whole numbers.

ADL: An Activity Description Language for Real-Time Networks

Abstract: This paper introduces and motivates ADL, a new formal notation for the specification of the temporal and functional behaviour of concurrent processes. ADL is tailored to be directly compatible with the DORIS design method. It combines a graphical Activity State-Machine (ASM) notation and a model-based Activity Functional Behaviour (AFB) notation. The abstract syntax, and static and dynamic semantics for the ASM notation are given, the dynamic semantics being given proof-theoretically in many-sorted logic extended with the RTL ‘occurrence’ relation, Θ, and the ERTL ‘holding’ relation, Φ. ADL is used to specify a small network, and proofs are given of its timeliness and safety properties.

Device for rapid connection between a totally implantable heart prosthesis and natural auricles

Abstract: Device for rapid connection between a totally implantable heart prosthesis and natural auricles. According to the invention, said prosthesis comprises: fastening means (16, 25) for fastening an end of one of the lunettes (2, 3) to the other lunette (3, 2), said fastening means being able to permit folding of said lunettes relative to each other; guide means (10, 11, 20, 21) for guiding said lunettes relative to each other before and during fastening and also during folding; and snap-fit means (19, 26) for engaging said lunettes on each other in the operating position corresponding to the end of said folding.

Enriques Surfaces: Generalities

Abstract: Let K be an algebraically closed field of arbitrary characteristic p. In this section we recall the main results of the classification of nonsingular projective surfaces over K. We refer to [Mu 2,B-M 1,B-M 2] for the proofs of all the assertions peculiar to the case of positive characteristic and to general textbooks [B-P-vdV,Bea 2,G-H 1] for the case of characteristic zero.