Comparison between wood hygromechanical description and deformation modification factors of Eurocode 5

International audienceEngineers need confidence in normative standards to design timber structures. Structural design is performed to ensure safety issues and answer qualitative constructions regarding to an economic competitive objective. In order to improve and provide well matched normative rules and wood material behaviour we performed laboratory creep experiments to quantify and describe the kinetics of wood material facing hygro-mechanical history. Furthermore it allows a direct comparison with deformation modification factors of EN1995 regarding an increase of structural longevity of timber structures

Contribution à l'accroissement des performances du processus de µEDM par l'utilisation d'un robot à dynamique élevée et de haute précision

Electro Discharge Machining (EDM) is an attractive subtractive method for complex 3d structurization of hard and very hard conductive and semi-conductive materials. The machining capabilities of a material do not depend on its hardness but on its electric conductibility and its melting point. The absence of any mechanical interaction between tool (the electrode) and machined part makes the electroerosion a well-adapted process for micro-structurization. In the passage from the macro to the micro-electroerosion (µEDM), some of the elements of the machine have to be adapted in order to improve the performances and to obtain accurate movements. The goal is to manufacture millimeters-sized shapes with an accuracy of a hundred of nanometers. This thesis deals the problem of the µEDM with a three degrees of freedom (DOF) mechanism, based on a parallel kinematics and flexure joints (the Delta3 robot). In addition to its high accuracy (5 nm) and high bandwidth (500 Hz), the Delta3 robot has the particularity of being free of backlash, wear and stick-slip phenomena. These performances have allowed to verify the importance of the time constants in the servo loop of the process, by many experiences of micro-drilling. Simulations have demonstrated the advantages brought by the dynamic, in the improvement of the µEDM process. Bad flushing conditions and very small gaps (<10 µm), generate elevated gradients of contamination, to which the frequency response of the machine must be adapted. Simulations have shown that the balance between the material removal rate and the evacuation rate can be improved by adjusting the electrode-part distance at a frequency of a few hundreds of hertz. These back and forth movements have to be fast and accurate: first, to adjust quickly and precisely the breaking voltage distance and second, to guarantee a good machining accuracy. An industrial version of the prototype finalized during this thesis will be commercialized soon by AGIE (the company that supported this work)

To spike or not to spike: the whims of the Wonham filter in the strong noise regime

We study the celebrated Shiryaev-Wonham filter in its historical setup of Wonham (1964) where the hidden Markov jump process has two states. We are interested in the weak noise regime for the observation equation. Interestingly, this becomes a strong noise regime for the filtering equations. Earlier results of the authors show the appearance of spikes in the filtered process, akin to a metastability phenomenon. This paper is aimed at understanding the smoothed optimal filter, which is relevant for any system with feedback. In particular, we demonstrate that there is a sharp phase transition between a spiking regime and a regime with perfect smoothing.Comment: v1: Preliminary versio

The macrofilaricidal efficacy of repeated doses of ivermectin for the treatment of river blindness

Background: Mass drug administration (MDA) with ivermectin is the cornerstone of efforts to eliminate human onchocerciasis by 2020 or 2025. The feasibility of elimination crucially depends on the effects of multiple ivermectin doses on Onchocerca volvulus. A single ivermectin (standard) dose clears the skin-dwelling microfilarial progeny of adult worms (macrofilariae) and temporarily impedes the release of such progeny by female macrofilariae, but a macrofilaricidal effect has been deemed minimal. Multiple doses of ivermectin may cumulatively and permanently reduce the fertility and shorten the lifespan of adult females. However, rigorous quantification of these effects necessitates interrogating longitudinal data on macrofilariae with suitably powerful analytical techniques. Methods: Using a novel mathematical modeling approach, we analyzed, at an individual participant level, longitudinal data on viability and fertility of female worms from the single most comprehensive multiple-dose clinical trial of ivermectin, comparing 3-monthly with annual treatments administered for 3 years in Cameroon

New protective battle-dress impregnated against mosquito vector bites

<p>Abstract</p> <p>Background</p> <p>Mixing repellent and organophosphate (OP) insecticides to better control pyrethroid resistant mosquito vectors is a promising strategy developed for bed net impregnation. Here, we investigated the opportunity to adapt this strategy to personal protection in the form of impregnated clothes.</p> <p>Methods</p> <p>We compared standard permethrin impregnated uniforms with uniforms manually impregnated with the repellent KBR3023 alone and in combination with an organophosphate, Pirimiphos-Methyl (PM). Tests were carried out with <it>Aedes aegypti</it>, the dengue fever vector, at dusk in experimental huts.</p> <p>Results</p> <p>Results showed that the personal protection provided by repellent KBR3023-impregnated uniforms is equal to permethrin treated uniforms and that KBR3023/PM-impregnated uniforms are more protective.</p> <p>Conclusion</p> <p>The use of repellents alone or combined with OP on clothes could be promising for personal protection of military troops and travellers if residual activity of the repellents is extended and safety is verified.</p

CADDA: Class-wise Automatic Differentiable Data Augmentation for EEG Signals

International audienceData augmentation is a key element of deep learning pipelines, as it informs the network during training about transformations of the input data that keep the label unchanged. Manually finding adequate augmentation methods and parameters for a given pipeline is however rapidly cumbersome. In particular, while intuition can guide this decision for images, the design and choice of augmentation policies remains unclear for more complex types of data, such as neuroscience signals. Besides, class-dependent augmentation strategies have been surprisingly unexplored in the literature, although it is quite intuitive: changing the color of a car image does not change the object class to be predicted, but doing the same to the picture of an orange does. This paper investigates gradient-based automatic data augmentation algorithms amenable to class-wise policies with exponentially larger search spaces. Motivated by supervised learning applications using EEG signals for which good augmentation policies are mostly unknown, we propose a new differentiable relaxation of the problem. In the class-agnostic setting, results show that our new relaxation leads to optimal performance with faster training than competing gradient-based methods, while also outperforming gradient-free methods in the class-wise setting. This work proposes also novel differentiable augmentation operations relevant for sleep stage classification

Managing insecticide resistance in malaria vectors by combining carbamate-treated plastic wall sheeting and pyrethroid-treated bed nets

<p>Abstract</p> <p>Background</p> <p>Pyrethroid resistance is now widespread in <it>Anopheles gambiae</it>, the major vector for malaria in sub-Saharan Africa. This resistance may compromise malaria vector control strategies that are currently in use in endemic areas. In this context, a new tool for management of resistant mosquitoes based on the combination of a pyrethroid-treated bed net and carbamate-treated plastic sheeting was developed.</p> <p>Methods</p> <p>In the laboratory, the insecticidal activity and wash resistance of four carbamate-treated materials: a cotton/polyester blend, a polyvinyl chloride tarpaulin, a cotton/polyester blend covered on one side with polyurethane, and a mesh of polypropylene fibres was tested. These materials were treated with bendiocarb at 100 mg/m²and 200 mg/m²with and without a binding resin to find the best combination for field studies. Secondly, experimental hut trials were performed in southern Benin to test the efficacy of the combined use of a pyrethroid-treated bed net and the carbamate-treated material that was the most wash-resistant against wild populations of pyrethroid-resistant <it>An. gambiae </it>and <it>Culex quinquefasciatus</it>.</p> <p>Results</p> <p>Material made of polypropylene mesh (PPW) provided the best wash resistance (up to 10 washes), regardless of the insecticide dose, the type of washing, or the presence or absence of the binding resin. The experimental hut trial showed that the combination of carbamate-treated PPW and a pyrethroid-treated bed net was extremely effective in terms of mortality and inhibition of blood feeding of pyrethroid-resistant <it>An. gambiae</it>. This efficacy was found to be proportional to the total surface of the walls. This combination showed a moderate effect against wild populations of <it>Cx. quinquefasciatus</it>, which were strongly resistant to pyrethroid.</p> <p>Conclusion</p> <p>These preliminary results should be confirmed, including evaluation of entomological, parasitological, and clinical parameters. Selective pressure on resistance mechanisms within the vector population, effects on other pest insects, and the acceptability of this management strategy in the community also need to be evaluated.</p