Évaluation des logiciels critiques: application à la méthode B

From the point of view of safety the bottleneck in the operation of computerized systems currently appears to be the software. In order to improve the safety of software an independent assessment of its quality has been advocated for several years. The assessment of safety critical software consists of a technical examination on the basis of a set of criteria by a body which is independent from the designer. These assessment criteria are derived from the standards which are in force, the state of the art and experience. The objective of an assessments to verify that the product meets the specified safety and functionality requirements. In this paper the authors describe a combined approach to the assessment of safety critical software. On the one hand, the process used in order to develop the software is examined, and on the other the quality of the end product (software) is checked. The first part of the paper will present the position of safety critical software in the context of railway standardization as well as the main assessment techniques with particular reference to that used at Inrets. The second part of the paper will deal with the contribution of formal methods such as the B method to the development of safety critical software. The software assessment aspect will pay particular attention to assessment of the product — analysis of the traceability of requirements, integration and validation of safety properties. The paper ends with a brief account of the extraction and interpretation of metrics for a formal development. Finally the criteria used to assess the process are rapidly described. This approach has been used in the framework of an Esprit project known as Cascade (Certification and Assessment of Safety Critical Application Development).     

满足2025年CAFÉ标准的轻型卡车用节能柴油机解决方案（下）

针对全球气候条件的变化,减少温室气体（GHG）排放的相关举措取得了重大成果,比如减少交通部门产生的CO2排放。为此,针对美国的庞大市场,相关的法律部门为未来制定了富有挑战性的目标。     

Évaluation des potentiels de réduction des trafics automobiles dans le cas de la zone dense francilienne

The Pari 21 research project does not attempt to justify a move towards a radically different system—practically everything there is to say about the benefits and disadvantages of cars in cities has already been said. Instead, the project will perform simulations and assess, from the point of view of individuals, the feasibility of a transport system that is based mainly On the use of modes Other than the private car in the densely populated zone Of the Greater Paris Area (Paris city plus the inner suburbs). By constructing and evaluating transport policy scenarios, this research also aims to measure the potential for reducing car use in highly urbanized zones, particularly that which results from the reduction in journey speeds which are a likely consequence of the policies in question The method is based on repeated iterations of a simulation model which combines the assignment of round trips to modes other than the automobile with reformulations of transport supply. Demand is channelled towards personal modes (walking, cycling), public transport and a combination of personal and public modes. These iterations are based on the 1991-1992 Paris Region comprehensive travel survey which recorded all the round trips by car made in a typical day by the individuals living in the zone (i.e. the sequence of all trips made between each time the individual leaves home and returns home).     

Évaluation de mesures d’urgence potentielles en cas de pic de pollution atmosphérique en Alsace

Ten years after their implementation, the Alsatian prefectorial orders concerning emergency measures applied in case of exceedance of alert thresholds for ozone, nitrogen dioxide and, a pioneer feature of the French region, the PM, required an update. In 2007, the ASPA was mandated by the Bas-Rhin and the Haut-Rhin Prefectures to define and assess new emergency measures. The Alsatian emissions inventory first identified the activity sectors which would be potentially targeted by the measures, and then calculated the associated emission reductions. In association with the transportation agency, 3 scenarios were retained for concentration simulation: limitation of the speed limit at 70 km/h on freeways and major urban roads, alternated traffic in towns, and a combination of both measures. Then, an integrated modelling chain, including the CHIMERE and ADMS-Urban models, was allowed to simulate, for the three scenarios, the variation of ozone during the heat wave of 2003, and the variation of nitrogen dioxide and the PM during wintry episodes, for the cities of Strasbourg, Colmar and Mulhouse. Finally, the urban cartographies of the impact of the scenarios on the concentrations were crossed with the georeferenced residence data to estimate the population affected by threshold exceedances in each case. A weak impact was obtained for speed limit reduction, while it was significant for the alternated traffic; for the PM, the concentrations fell about 10 μg/m³ and the population exposed to threshold exceedance fell by a factor 4; for nitrogen dioxide, the concentrations were lowered by several dozen μg/m³ and the exposed population fell by a factor 2; whereas for ozone, we noted a slight increase in the concentration and the exposed population. At the same time as the implementation of the newly developed emergency measures, the evolution of knowledge and modelling shows that it would be technically justified to differentiate the measures, pollutant by pollutant.     

Mobilité et accès à la voiture chez les personnes âgées: Évolutions actuelles et enjeux

In France, and in most other industrialised countries, demographic ageing means that in the next decades there will be a rise among the elderly in vehicle ownership and driving for daily trips, long distance travel and leisure trips. This paper demonstrates the existence of these trends by drawing on a variety of statistical sources — National Transport and Communication Surveys, Urban Household Travel Surveys (Lyon) and surveys on French holiday practices. We nevertheless demonstrate that this structural change exhibits a high degree of differentiation with regard to gender, household income, place of residence and state of health. This change, which increases car use, is expected to continue during the next few years, especially among elderly women. Long term changes in lifestyles encourage the view that in the future people will cease to drive at a more advanced age. The increase in car use has important long-term implications in two areas. On the one hand it will affect road safety, on the other hand it raises the issues of the sustainability of mobility and the obligation to meet the needs of persons who are no longer able to drive.     

Évolution des émissions de CO2 liées aux mobilités quotidiennes: une stabilité en trompe l’œil

Alternatives to the use of automobiles have regained attention at the urban level. Against this background, we look at the spatial context of this attention in the agglomeration of Lyon. More specifically, we look at how CO₂ emissions that are associated with everyday mobility have developed until recently. First, we estimate the intensity of CO₂ emissions per day based on the last two household travel surveys done in the Lyon conurbation in 1995 and 2006. Even if the global emission level remains stable, we aim to analyze the dynamics of the socio-economic evolution of mobility between the two periods. To that end, we have abstracted the linkage of a specific form of mobility (mode of transport and distance) to a specific population group (status, residential location, car access, gender). This typology helps us highlight the groups where emission rates are significantly higher, and where the focus on emission reduction should be intensified.