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.

Applications for optical free space links in inter-satellite and intra-satellite communications

Abstract: Free space links between satellites provide a means of introducing increased connectivity into a satellite system. This can result in enhanced traffic capacity and extended coverage for the telecommunication systems and real-time relay of instrument data to the ground for Earth observation missions. Optical links offer the potential advantages over microwave links of lower mass, power and reduced size so that they can be accommodated more easily on the satellite. Matra Marconi Space has developed a range of optical terminals targetted at future inter-satellite requirements. This paper presents the current status of these optical terminals. Free space links also have potential for applications within the satellite itself. Intra-satellite links are required to connect subsystems within the payload. This is typically achieved using semi-rigid coaxial cables but the trend towards satellites with increased capacity and high gain multibeam antennas makes optical intra-satellite links attractive due to the increased connectivity and flexibility, signal routing, switching and distribution which can be achieved within the payload. An overview of potential intra-satellite applications is presented. (6 pages)

Proton SEU test of MC68020, MC68882, TMS320C25 on the ARIANE 5 launcher on board computer (OBC) and inertial reference system (SRI)

Abstract: The ARIANE5 On Board Computer (OBC) and Inertial Reference System (SRI) are based on Motorola MC68020 processor and MC68882 coprocessor. The SRI data acquisition board also uses the DSP TMS320C25 from Texas Instruments. These devices were characterized to proton induced SEUs. But representativeness of SEU test results on processors was questioned during ARIANE5 studies. Proton test of these devices was also performed on the actual equipments with flight (or representative) software. The results show that the On Board Computer and the Inertial Reference System can satisfy the requirements of the ARIANE5 missions.

Design methodology for supersonic air intakes

Abstract: A global design methodology for supersonic air intakes is proposed. It is strongly based on numerical computations. The emphasis is especially put on the optimization of the links between the various stages of the design so as to rationalize the process and insure a good communication between the designer, the numerical computation engineer and the configuration manager. WHY IS IT IMPORTANT TO MASTER THE AIR INTAKE DESIGN IN A HIGH SPEED AEROBIC MISSILE DEVELOPPEMENT ? The design of a high-speed air-breathing vehicle is a long and delicate operation requiring the optimization of numerous design compromises interacting with each other and conditioning very widely the definition of the various constituents. The realization of these compromises is all the more difficult as we are more and more confronted with the imperative need to reduce the costs and the duration of the global cycle of development. One of the key elements of the global optimization of the aeropropulsive balance of high speed aerobic vehicles is the air intake which: Determines both the quantity and the quality of the air taken from the atmosphere (which influences directly all the tuning of the combustion chamber) Constitutes an important part of the global drag (which directly influences the fuel tank sizing) COPYRIGHT © 2001 EADS AEROSPATIALE MATRA MISSILES. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. Contributes strongly to the global lift (that participates to the global aerodynamic formula) Can be a major contributor to the radar signature (RCS) Participates substantially to the mass estimate Represents a significant part of the production cost. It is thus advisable to master and to rationalize the iterative design process of the air intake aerodynamics to be capable of: Minimizing the cost by limiting as much as possible the expensive experimental iterations; Reducing the cycle times to favour the flexibility and the reactivity of the global optimization; Estimating quickly the feasibility of beneficial shape evolutions or minimizing development and production costs or reducing the RCS. WHAT KIND OF APPROACHES ARE CLASSICALLY USED TODAY ? To establish the definition of an air intake, two approaches are possible: The experimental approach, which consists in realizing, reduced scale models and testing them in a wind tunnel; The numerical approach which consists in realizing a computation of the flow upstream and in the air intake by means of a two-, then threedimensional model using, depending on the development, more and more accurate modeling of the fluid mechanics laws (Euler then NavierStokes). 1 American Institute of Aeronautics and Astronautics (c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. THE EXPERIMENTAL APPROACH Led with skill, the experimental approach gives the surest results in terms of accessible global performances (performance curve). Even if the computation times have been reduced formidably, it remains today the most effective means to characterize an air intake in a wide flight domain in order to establish a performance model serviceable for the propulsive system design, the global flight simulations, or the embarked regulation software. On the other hand, it requires heavy seed money, which consists in: Defining and realizing a "model kit" (modular model able to receive various elements which allow to study configuration variants, the manufacture of which should be of very good quality precision, repeatability of the configurations, surface roughness...); Endow the model of a detailed enough and precise instrumentation; Realize tests campaigns, the preparation of which being long and expensive. Besides, this experimental approach is too long if it is the only mean for the selection of the optimal air intake shape (model kit never perfectly adapted from the first tests campaign, time consuming configuration changes increasing the tests costs...). THE NUMERICAL APPROACH The numerical approach presents actually the inverse advantages and drawbacks of the experimental approach. In spite of the considerable progress realized these last ten years in the validation of the computation codes, and in spite of the precision presently obtained (of the same order as that of the tests), it will always be necessary to characterize in tests the shapes elaborated by computations, in order to definitively raise any doubt on the performances of the air intakes. Furthermore, the cost (in terms of duration) can turn out high if one wishes to perform a fine characterization requiring the computation of numerous running points. On the contrary, the numerical approach, although one endows it with effective meshing means, allows estimating in a reliable way and with a limited investment different configurations on a few flight points. Furthermore, it gives access to the detailed flow structure so yielding to understand better the physical phenomena that govern the functioning and favoring therefore the configuration desing. THE COUPLING OF THE EXPERIMENTAL AND NUMERICAL APPROACHES ALLOWS TO OPTIMIZE THE DESIGN To drive quoted rationalization process and answer more effectively the needs of the projects, we defines as objective: To establish an air intakes design methodology involving intimately both approaches to benefit of their advantages while minimizing (even eliminating) their drawbacks To obtain, thanks to this methodology, a sensitive reduction of the cost and the duration of the design cycle of an air intake To operate it according to its implementation on concrete industrial cases. GLOBAL DESIGN METHODOLOGY OF AIR INTAKES The development and the validation of internal aerodynamics computation codes being acquired, we focused on building a general design methodology for supersonic air intakes which strongly integrates the numerical approach into the traditional process based on wind-tunnel tests. Given the advantages and drawbacks described above for both experimental and numerical approaches, the best complementarity is obtained through the process described in the following scheme: American Institute of Aeronautics and Astronautics (c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. Figure 1: coupling of numerical and experimental approaches A few of key points was identified as determining the efficiency of the process: Configuration management Simplification of the CAD / meshing interface

Geographic distribution and genital morphology of the genera Lozekia Hudec, 1970 and Kovacsia Nordsieck, 1993 (Mollusca, Gastropoda, Hygromiidae)

Abstract: The Lozekia-Kovacsia species group comprises three species occurring in the Carpathian-Pannonian region, namely Lozekia transsilvanica (Westerlund, 1876), Lozekia deubeli (M. Kimakowicz, 1890) and Kovacsia kovacsi (Varga & L. Pinter, 1972). These species are known to be distinguishable by their genital morphology but, up to now, only a few populations have been examined anatomically. Due to their conchological similarity, distribution records that have been based on individuals of unknown anatomy are unreliable, and the ranges are far from being well defined. First we identified the type locality of L. transsilvanica and investigated the genital morphology of topotypical material in order to ensure the correct use of this name. Furthermore, we carried out a morphological analysis of Lozekia -Kovacsia material collected throughout the postulated range of this species group. Of the previously proposed species-specific features, the structure of the dart-sac complex and the number of digitiform glands were found to be the most reliable. Based on these genital characters, we re-defined the ranges of the three species; those of K. kovacsi and L. deubeli were found much larger than believed previously. Finally, we describe the morphology of the spermatophore of K. kovacsi, which was found in this species for the first time. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical Design Of The Hipparcos Telescope

Abstract: The design and the development of the HIPPAR-COS payload all reflective Schmidt telescope have been driven by the highly demanding challenge of reaching an accuracy of 2 milli-arcseconds (1.E-8 radians) in star position measurements. This achievement is made possible by an original optical arrangement of the telescope, based on the capability to develop the so-called "beam combiner", which consists in a reflective Schmidt corrector cut in two halves and reassembled by bonding with an angle of 29 degrees, with a final wavefront distortion of lambda / 60 RMS. The final optical performances of the tele-scope can be summarized by a loss of MTF better than 7 % with respect to the diffrac-tion limit and a chromaticity lower than 3 milliarc-seconds. After a short description of the principle of Hipparcos measurement and of the telescope optical configuration and a recall of the chromaticity concept, this paper gives a presentation of the development of the optics especially of the Beam Combiner, and technics used for the alignment and test of the telescope.