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.

Study on the Validity of Electronic Parts Stress Models

Abstract: By using data on the failure rates of electronic components collected by a European Bank, we try to form an idea on the validity of the various models (Bazovsky model, MIL HDBK-217A standard model, exponential model, RADC TR-67 models) that represent the variations of the failure rate with respect to the thermal and electrical stresses. Two different approaches have been programmed on a computer: 1) conventional, using the linear regression analysis 2) more modern using the Fletcher-Powell method or methods derived from it (Fletcher-Reeves or Davidon). The results are given for four types of components. The models studied reflect, more or less accurately, what happens in real life. We define and give a value to a criterion, allowing the model to be chosen closest to reality. This paper, apart from its practical interest on the validity of currently accepted models and its theoretical interest on the use of methods for seeking extremes, shows how the computer can assist the reliability engineer with the filing of data, the statistical processing of these data, etc., right up to the automatic tracing of networks of curves.

Composite structure state surveillance method and pressurized fluid container equiped with a device using this method

Abstract: Monitoring the state of a composite structure (14) formed from at least two different superposed materials and submitted to a uniform force over all its surface involves measuring the deformation at the interface between the materials. Comparison with a reference deformation amount for the structure normally generated by the force applied to it indicates the operating state. When the composite structure (14) forms the wall of a container (10), the monitoring is carried out in a instrumentation enclosure (30) that can be attached and detached to the container (10). When a critical threshold is exceeded, an alarm indicator (32) on the enclosure (30) operates.

X-38 V201 Avionics Architecture

Abstract: The X-38 is an experimental NASA project developing a core human capable spacecraft at a fraction of the cost of any previous human rated vehicle. The first operational derivative developed from the X-38 program will be the International Space Station (ISS) Crew Return Vehicle (CRV). Although the current X-38 vehicles are designed as re-entry vehicles only, the option exists to modify the vehicle for uses as an upward vehicle launched from an expendable launch vehicle or from the X-33 operational derivative. The Operational CRV, that will be derived from the X-38 spaceflight vehicle, will provide an emergency return capability from the International Space Station (ISS). The spacecraft can hold a crew of up to seven inside a pressurized cabin. The CRV is passively delivered to ISS, stays up to three year on-orbit attached to ISS in a passive mode with periodic functional checkout, before separation from ISS, de-orbit, entry and landing. The X-38 Vehicle 201 (V201) is being developed at NASA/JSC to demonstrate key technologies associated with the development of the CRV design. The X-38 flight test will validate the low cost development concept by demonstrating the entire station departure, re-entry, guidance and landing portions of the CRV mission. All new technologies and subsystems proposed for CRV will be validated during either the on orbit checkout or flight phases of the X-38 space flight test. The X-38 subsystems are required to be similar to those subsystems required for the CRV to the greatest extent possible. In many cases, the subsystems are identical to those that will be utilized on the Operational CRV.

Effects of roads and adjacent areas on diversity of terrestrial isopods of Hungarian highway verges

Abstract: Transportation infrastructure may be the most important driver of social and economic development, but it is a major cause of environmental change in landscapes. The main objective of this paper is to report road edge effects on isopods of Hungarian highway verges. We examined the isopod diversity along five highways (M0, M1, M3, M5, M7) while accounting for road edge proximity and the adjacent areas. Double-glass pitfall traps were set in a total of 15 sites and at three distances from the edge of the roads next to different types of adjacent areas. We found differences between ecological parameters of isopod communities in relation to adjacent areas as well as to road edge proximity. The highest diversity was observed near urban areas, while the lowest was near the arable fields. Isopod diversity increased with decreasing distance from a road. Species diversity of different types of verges based on adjacent areas varied strongly in relation to road edge proximity. A medium distance (40 m) from roads had a positive effect on species richness, while verges next to arable fields were the most species-rich habitats. The general conclusion of this study is that highway verges provided suitable environment conditions for generalist isopod species but may be a limiting factor for specialist isopods. Moreover, highway verges function as corridors for isopods. The proximity of roads and urban areas positively affected isopods, and verges close to roads and urban areas are considered as an attractive environment for isopods in heterogeneous roadside verges.

A traceability-based model for an integrated maintenance environment

Abstract: This paper presents an approach to support the exploitation of large sets of inter-related documents. This approach particularly focuses on the integration of hypertext concepts with object oriented ones in order to build a maintenance dedicated database. This database and hence, the underlying data model described here is particularly suited with the exploitation of traceability information. Though part of the paper explains the different modeling issues, some explanations are first given on the way the information is stored and extracted from the various documents.