Towards Formally Verified Optimizing Compilation in Flight Control Software

International audienceThis work presents a preliminary evaluation of the use of the CompCert formally specified and verified optimizing compiler for the development of level A critical flight control software. First, the motivation for choosing CompCert is presented, as well as the requirements and constraints for safety-critical avionics software. The main point is to allow optimized code generation by relying on the formal proof of correctness instead of the current un-optimized generation required to produce assembly code structurally similar to the algorithmic language (and even the initial models) source code. The evaluation of its performance (measured using WCET) is presented and the results are compared to those obtained with the currently used compiler. Finally, the paper discusses verification and certification issues that are raised when one seeks to use CompCert for the development of such critical software

Formally verified optimizing compilation in ACG-based flight control software

International audienceThis work presents an evaluation of the CompCert formally specified and verified optimizing compiler for the development of DO-178 level A flight control software. First, some fundamental characteristics of flight control software are presented and the case study program is described. Then, the use of CompCert is justified: its main point is to allow optimized code generation by relying on the formal proof of correctness and additional compilation information instead of the current un-optimized generation required to produce predictable assembly code patterns. The evaluation of its performance (measured using WCET and code size) is presented and the results are compared to those obtained with the currently used compiler

A typology for world electricity mix: Application for inventories in Consequential LCA (CLCA)

Over the past two decades, the integration of environmental concerns into decision making has been gaining prominence both at national and global levels. Sustainable development now factors into policy design as well as industrial technological choices. For this purpose, Life Cycle Assessment (LCA)–which evaluates environmental impacts of products, processes and services through their complete life cycle–is considered a crucial tool to support the integration of environmental sustainability into decision making. In particular, Consequential LCA (CLCA) has emerged as an approach to assess consequences of change, considering both direct and indirect impacts of changes. Currently, no long-term datasets of Consequential Life Cycle Inventories (CLCI) are available, particularly in the case of electricity production mixes. A first and fundamental step to begin filling this gap is to make available data on national level greenhouse gas emissions from electricity and create a typology of electricity production mixes to support policy making. The proposed typology is based on the analysis of the composition of electricity production mixes of 91 countries producing more than 10 TWh in 2012, on the one hand, and of their calculated greenhouse gas (GHG) emissions (in gCO2eq/kWh) from LCA using IPCC 2013 data, on the other hand. All types of primary energy resources are considered, and some are grouped according to similarities in their emissions intensities. Using graphical observations of these two characteristics and a boundary definition, we create a 4-group typology for GHG emissions per kWh, i.e., very low (0–37 gCO2eq/kWh), low (37–300 gCO2eq/kWh), mean (300–600 gCO2eq/kWh) and high (>600 gCO2eq/kWh). The typology is based on the general characteristics of the electric power generation fleet, corresponding respectively to power systems heavy on hydraulic and/or nuclear power with the remainder of the fleet dominated by renewables; hydraulic and/or nuclear power combined with a diversified mix; gas with a diversified mix; coal, oil and predominantly fossils. This typology describes the general tendencies of the electricity mix and, over time, it can help point to ways in which countries can transition between groups. Further steps should be devoted to the development of indicators taking into account grid interconnection, energy sector resilience in the quest for a mix optimum

Development of a detector of neutrons to characterize stratospheric radiatif environment and assess its pressure on microelectronics

Nous avons développé un détecteur intégré à base d'une diode pour être embarqué dans un ballon stratosphérique afin de caractériser l'environnement radiatif atmosphérique. Le détecteur a été calibré avec une source Californium, et il a été pleinement caractérisé lors de tests sous faisceaux de neutrons qui produisent diverses particules ionisantes secondaires. Les sections efficaces différentielles de détection pour différentes énergies de faisceaux de neutrons sont avérées être en bon accord avec les simulations effectuées avec le code MC-Oracle. Nous avons effectué un certain nombre de vols en ballon stratosphériques (avec l'ESA et le CNES) et confirmé la corrélation entre le taux de comptage et de l'altitude. En outre, nous avons observé que l'environnement radiatif n'est pas isotrope et démontré le potentiel de notre outil pour étudier l'environnement radiatif atmosphérique. Ces résultats sont utiles pour estimer le flux de particules qui affecte appareils et systèmes électroniques à bord des appareils.We developed an integrated silicon detector to be embedded in a stratospheric balloon in order to investigate the radiative atmospheric environment. The detector was calibrated with a Californium source, and it was fully characterized under neutron beams which produced various secondary ionizing particles. Differential detection cross sections for different neutron beam energies were shown to be in good agreement with simulations performed with the MC-Oracle code. We performed four stratospheric balloon flights (with ESA and CNES) and confirmed the correlation between the count rate and the altitude. Moreover, we observed that the radiative environment is not isotropic and demonstrated the potential of our tool for investigating the radiative atmospheric environment. These results are useful for estimating the particle flux that affects electronic devices and onboard aircraft systems

Contribution of Life Cycle Assessment for the objective of carbon neutrality: Bibliographic review

The Paris Agreement adopted in 2015 (UNFCCC, United Nations Framework Convention on Climate Change, 2015) set the objective of containing the rise in the average temperature of the planet well below 2°C, ideally at 1.5°C, compared to pre-industrial levels. According to the Intergovernmental Panel on Climate Change (IPCC, 2018), this requires achieving carbon neutrality by 2050. This objective has become a major issue and has led to the development of multiple scenarios, responding to specific questions from different sectors (ADEME, 2021; Ministère de la Transition Ecologique, 2020; négaWatt, 2021; RTE, 2021) and supporting various strategies at the international, national and even regional level. France, as a signatory of the Paris Agreement, has thus developed a trajectory, described in the National Low Carbon Strategy (SNBC) (Ministère de la Transition Ecologique, 2020) to achieve carbon neutrality by 2050. However, this issue raises many methodological questions on quantification metrics. Furthermore, Life Cycle Assessment (LCA) is a recognized method for the environmental assessment of products and services, taking into account the entire life cycle. Carbon neutrality strategies would benefit from being enriched by the LCA method, on two counts: in order to extend the carbon dimension to a broader, multi-criteria environmental dimension, and in order to take into account the entire life cycle rather than just emissions from the territory. Nevertheless, the question of the feasibility of translating carbon neutrality scenarios into LCA modeling arises. This article reviews the literature on this subject. Research has highlighted the growing interest in these two subjects for several years, while revealing an ill-defined semantic around carbon neutrality: the term is mainly used to contextualize decarbonization projects. Thus, no article dealing with the carbon neutrality of France assessed by an LCA study has been identified. A test case would make it possible to understand the feasibility of such an approach: the scenario of the SNBC (Ministère de la Transition Ecologique, 2020) seems to be a relevant support for such an exercise

Caractérisation électromagnétique d'une diode perturbée par des convertisseurs lors d'une campagne de mesures en ballon

International audienc

Caractérisation électromagnétique d'une diode perturbée par des convertisseurs lors d'une campagne de mesures en ballon

International audienc

Embedded silicon detector to investigate the natural radiative environment

International audienceA detector based on a silicon diode was developed to investigate the natural radiative environment. As the detector is embeddable, it has low power consumption and is lightweight and small. The instrument was tested under different neutron beams and used during stratospheric balloon flights. A comparison of the experimental results with Monte Carlo simulation results shows that the embeddable detector is a promising means of investigating the natural radiative environment