« Piccioli (CE, 17 janvier 1923) »

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Deformation theory of Cohomological Field Theories

International audienceWe develop the deformation theory of cohomological field theories (CohFTs), which is done as a special case of a general deformation theory of morphisms of modular operads. This leads us to introduce two new natural extensions of the notion of a CohFT: homotopical (necessary to structure chain-level Gromov--Witten invariants) and quantum (with examples found in the works of Buryak--Rossi on integrable systems). We introduce a new version of Kontsevich's graph complex, enriched with tautological classes on the moduli spaces of stable curves. We use it to study a new universal deformation group which acts naturally on the moduli spaces of quantum homotopy CohFTs, by methods due to Merkulov--Willwacher. This group is shown to contain both the prounipotent Grothendieck--Teichmüller group and the Givental group

Residual stress and thickness effects on fracture behavior of trilayer films during uniaxial loading

International audienceThe effects of residual stress and film thickness on crack evolution in metallic trilayers deposited on polyimide substrate have been investigated during uniaxial tensile loading. Four different systems, consisting of Mo/Cu/Cr layers deposited on polyimide, with nominal thicknesses of 100/100/100 or 100/500/100 nm, were developed using two physical vapor deposition techniques, resulting in opposite as-deposited high residual stress for the top Cr layer (about +2.7 GPa versus -2.6 GPa). First, it was found that the higher the compressive residual stress of the top Cr layer and the thickness of the middle Cu layer, the higher the critical strain to initiate crack propagation in the trilayer film system. Second, it was found that the higher the compressive residual stress of the top Cr layer and the thickness of the middle Cu layer, the lower the maximum crack density in the trilayers. The maximum crack density in the thicker system with Cr in a tensile residual stress was similar to the maximum crack density in the thinner system with the Cr top layer in a compressive residual stress

Algebraic control strategy for solving the mutual exclusion constraint problem in a network of timed event graphs with disturbance inputs: Application to an assembly process.

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Friction Durability of Anodized Aluminum Alloy 2017A under Dry Conditions

International audienceIn this paper, the friction durability of an anodized aluminum alloy is investigated on relation to the effects of two elaboration parameters: the anodizing time (called the reaction time RT) and the applied current (J). For this purpose, the tribological behavior of the developed oxide layer is characterized using scratch and reciprocating cyclic friction tests under dry and severe conditions. Energy-dispersive x-ray spectroscopy, scanning electron microscopy and surface profilometry were used to correlate between the cyclic response and the worn surfaces and to highlight the impact of RT and J. The anodized layer exhibited an excellent wear resistance at 90 min RT, but its friction durability decreased at 30 min RT. The morphology of the anodized surface influenced the establishment and evolution of the friction-wear layer, which acted as a glass layer for 30 min RT/1A/dm2 (J) and an abrasive third body resource for 90 min RT/1A/dm2 (J) and for 30 min RT/2A/dm2 (J). The variation in the thickness, which affected by the change of the J and RT, has a strong influence on the adhesion strength of the oxide layer. The higher the oxide layer thickness is, the greater the adhesion strength

On the 1-parameter trigonometric and hyperbolic inequalities chains

In this paper, we introduce other classes of inequalities chains depending on a parameter, extending the classical ones. We show in particular how the Huygens and Wilker inequalities are related in chains. We thus improve recent results of Chen and Mortici [4]

Multi-Task Convolution Neural Network-Based Lifting Scheme for Image Compression

International audienceLifting schemes have attracted much interest in different image processing tasks, and more specifically in the image compression field. In this context, the optimization of the lifting operators (i.e. the prediction and update ones) plays a crucial role in the design of efficient lifting-based image coding systems. In this respect, we propose in this paper to further investigate the exploitation of neural networks in a standard non-separable lifting scheme structure. More precisely, unlike previous works, where different neural network models are employed for all the prediction and update steps involved in a lifting scheme-based decomposition, our design consists in building a new multi-task convolutional neural network model that takes into account the similarities between two prediction stages. Simulations carried out on three popular image datasets show the benefits of the proposed learning-based image coding approach

Telework, working conditions, health and wellbeing during the Covid crisis: A gendered analysis

International audienceObjectiveTelework was massively adopted during the COVID-19 crisis. Related changes in working conditions may have affected women's and men's health differently due to the gendered division of work. Our study aimed to assess the gendered association of telework with physical and mental health outcomes one year after the onset of the pandemic and to determine whether the pathways of working conditions underlying these associations are gender-related.MethodsWe compared pre-pandemic and Covid-crisis work contexts using a large representative sample of French employees surveyed in early 2021. We identified potential work-related mediators of the relationship between telework and well-being, i.e., change in autonomy, low support, work overload, digital issues, atypical working time, meaning at work, and work-life balance, and used multiple-matching and adjusting for confounders.ResultsAll things being equal, the health and well-being of teleworkers were, on average, less favourable than that of on-site workers, with little gender differences. The selected working conditions mediated a substantial part of the relationship, indicating that important pathways were captured, such as meaning at work. These pathways partly differed between women and men. In particular, in new teleworkers, the largest contributions came from digital issues for women, and from low support at work and work overload for men.ConclusionPeople who teleworked during the pandemic were at higher odds of deterioration of health and well-being than onsite workers. Health patterns were similar among male and female teleworkers; however, the pathways differed. These negative effects may yet have been absorbed once the government pandemic response became less stringent