Safety-Level Aware Bin-Packing Approach for Control Functions Assignment

International audienceThe assignment of functions to controllers is a crucial step when building an operational control system architecture. We identified this problem as a Multiple Choice Vector Bin-Packing with Conflicts that is a generalization of the one-dimensional Bin-Packing problem. Such problems are known to be strongly NP-Hard and exact techniques to solve them are too time and/or space consuming because of the combinatorial explosion. Therefore, in this paper, we propose a fast First-Fit Decreasing based heuristic that derives an optimized number of controllers in polynomial time. The objective is to minimize the global cost of controllers while satisfying safety constraints. We show through experiments that the adopted approach allows us to obtain values that are in average very close to the optimum

Model-based testing of PLC programs with appropriate conformance relations

International audienceNumerous theoretical results have been obtained in the field of conformance testing, a very promising formal technique to improve dependability of critical systems. Nevertheless, developing on this basis PLC test techniques that produce correct conformance verdicts requires to take into account the real technological features of PLC. This paper proposes conformance relations that meet this objective. Examples illustrate the benefits of the contribution

Coupling timed plant and controller models with urgent transitions without introducing deadlocks

International audienceThis paper focuses on timed models which represent closed-loop systems composed of a plant and a logic controller. Both the plant and controller models are described in a formalism where urgent transitions are possible, to avoid non-realistic evolutions, and without deadlock when they are separated. It is first shown that deadlocks may occur in the plant model as soon as both models are coupled. To solve this issue, shared variables which model the changes of the inputs of the controller are defined and introduced in some actions of the plant model as well as in some guards of the controller model; the aim of these variables is to authorize evolutions of the controller only when at least one input has changed. This solution removes the previously pinpointed deadlocks and guarantees the reactivity of the controller

Model of mechanism behavior for verification of PLC programs

More extensive work on formal methods is now available for checking PLC (Programmable Logic Controller) programs. To verify a PLC program, it is necessary to consider a set of properties to prove and one of the most interesting problems that the designers must deal is to deduce a set of properties that traduces all the safety requirements of the system behavior. In this paper, we explore the contribution of such a plant model within the context of deduction, in a systematized way, of a set of properties to prove, verifying the PLC program. Our study is primarily experimental in nature and based on a case study. A set of properties to be checked based on detailed plant model is proposed. We then analyze how a Symbolic Model-Checking tool (the NuSMV has been selected) ensures verification of these properties either with or without the considered plant model

Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach

Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate catabolism and proteasome are critical determinants of sensitivity to zinc, which also induces DNA damage. Conversely, glutathione levels and phagocytosis appear unaffected at moderately toxic zinc concentrations

Molecular responses of mouse macrophages to copper and copper oxide nanoparticles inferred from proteomic analyses

The molecular responses of macrophages to copper-based nanoparticles have been investigated via a combination of proteomic and biochemical approaches, using the RAW264.7 cell line as a model. Both metallic copper and copper oxide nanoparticles have been tested, with copper ion and zirconium oxide nanoparticles used as controls. Proteomic analysis highlighted changes in proteins implicated in oxidative stress responses (superoxide dismutases and peroxiredoxins), glutathione biosynthesis, the actomyosin cytoskeleton, and mitochondrial proteins (especially oxidative phosphorylation complex subunits). Validation studies employing functional analyses showed that the increases in glutathione biosynthesis and in mitochondrial complexes observed in the proteomic screen were critical to cell survival upon stress with copper-based nanoparticles; pharmacological inhibition of these two pathways enhanced cell vulnerability to copper-based nanoparticles, but not to copper ions. Furthermore, functional analyses using primary macrophages derived from bone marrow showed a decrease in reduced glutathione levels, a decrease in the mitochondrial transmembrane potential, and inhibition of phagocytosis and of lipopolysaccharide-induced nitric oxide production. However, only a fraction of these effects could be obtained with copper ions. In conclusion, this study showed that macrophage functions are significantly altered by copper-based nanoparticles. Also highlighted are the cellular pathways modulated by cells for survival and the exemplified cross-toxicities that can occur between copper-based nanoparticles and pharmacological agents

Introduction - Renouveler les regards sur l’innovation dans les systèmes agricoles et alimentaires

L’innovation est devenue un objet de questionnement incontournable dans nos sociétés. Elle est omniprésente dans les discours d’acteurs économiques ou politiques, s’inscrit dans des politiques dédiées et dans de nouvelles institutions telles que les pôles ou les plateformes, et vient s’incarner dans la figure du héros contemporain créateur de start-up. Le thème de l’innovation a aussi gagné une place importante dans le monde scientifique, comme en témoigne la forte croissance des travaux qui ..

Innovation et développement dans les systèmes agricoles et alimentaires

Innovation is often touted as one of the key levers for promoting a more sustainable development. The book looks at innovation in the agri-food sector in light of today's major challenges by examining the different dimensions of the change and focusing on the meaning ascribed to innovation by the stakeholders. An understanding of the methods and systems for supporting the stakeholders who innovate provides professionals, politics, and civil society with useful and novel courses of action