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International audience; The dynamics of plaster drying and the impact of subflorescence on the process are described through Magnetic Resonance Imaging and X-Ray Microtomography measurements. It is shown that crystals deposit around the air-liquid interface the closest to the sample free surface, which induces a recession of this interface within the sample at a rate only depending on the current saturation (water to pore volume ratio). Thus the distribution of crystals deposited during evaporation essentially depends on the history of saturation. The drying dynamics then results from vapor diffusion through the less porous layers of crystal accumulation below the sample free surface. This in particular makes it possible to predict the dramatic decrease of the drying rate after successive imbibition-drying cycles.

This paper presents a study of the influence of the radiation transfer on the thermal conductivity measurement in a parallel hot-wire method at high temperature. Simulations of the temperature evolution are first carried out with COMSOL Multiphysics ® using the coupled conduction-radiation module based on the P1 approximation for the radiation calculation. A wide range of conditions were investigated: a low and a high density insulator were considered with various radiation characteristics (purely scattering, absorbing and scattering, purely absorbing) and with temperature varying up to 1500 • C. This study enables the determination of the validity limit of the modeling of the temperature by a purely conductive model with an equivalent conductivity based on the Rosseland approximation. When this assumption is valid, a new estimation process was proposed to improve the estimation accuracy of the thermal properties. A calibration process of the distance between the hot-wire and the thermocouple has also been proposed and validated, enabling a more accurate estimation of the volume heat capacity. An experimental study carried out on three insulating materials with densities ranging from 581 kg • m −3 to 910 kg • m −3 and at temperatures ranging from 20 • C to 1200 • C confirms the results of the theoretical study. Finally, a method enabling the estimation of the extinction coefficient from thermal conductivity measurements at various temperatures is presented and successfully applied to the three tested materials.

International audience

Background In neonatology, parents play a central role as guarantors of the new-born’s autonomy. Notifying parents about their infant’s status in neonatal critical care is an integral part of the care. However, conveying this information can be very difficult for physicians and the neonatal medical team. The objective of this work is to assess the dimensions and dynamic processes of critical care communications in neonatal intensive care in order to enhance the development of theoretical and applied knowledge of these discussions. Methods This qualitative, descriptive study was conducted on critical care new-borns less than 28 days-old who were hospitalized in a neonatal intensive care unit. Verbatim communications with the parents were recorded using a dictaphone. Results The verbatim information had five themes: (a) critical care, (b) establishing the doctor-patient relationship, (c) assistance in decision making, (d) Socio-affective and (e) socio-symbolic dimensions. Our recordings underscored both the necessity of communication skills and the obligation to communicate effectively. Analysis of the dynamics of the communication process, according to the categories of delivering difficult information, showed few significant differences. Conclusion Physician training needs to include how to effectively communicate to parents to optimize their participation and cooperation in managing their care.

International audience; Obtaining large surfaces covered by submicron structures is a challenge in patterning coatings. Using laser induced dewetting, large surface self-assembled ordered metallic structures were used to modify optical properties of interference coatings.

Structural properties of aqueous Na-silicates at both room and high temperature (below 500°C) have been investigated to better understand the microscopic evolution of structure and the macroscopic phenomenon of foaming. NMR spectroscopy has provided a direct quantification of structural units defined as Qn. Solid-state NMR along with Raman spectroscopy has indicated the extent of local structural reorganization on heating the silicates. Heating an aqueous Na-silicate leads to structural changes due to the removal of water, where the quantity of leftover water in the system obeys an Arrhenian evolution with an activation energy of 30 kJ.mol−1. TGA, NMR and Raman measurements suggest that the structure becomes similar to the one of hydrated silicate glasses studied in geochemistry. Increasing the Na concentration results in a larger quantity of water retained after a pre-drying treatment, which correlates with a lower softening temperature of the material and is, macroscopically, related to foaming of the silicate.

International audience

International audience

Thermal bridges tend to increase overall buildings energy demand and might cause water condensation problems. They are thermally characterized by a linear transmission coefficient ψ or a point transmission coefficient χ . Today, most studies of thermal bridges are based on theoretical or numerical calculations. Standardized methods define default values and assumptions to make in simple or detailed simulations. The few existing in situ characterization methods of thermal bridges are based on steady-state assumptions. This makes them highly sensitive to weather conditions and often requires very long measurements. The present paper proposes a novel active method for the in situ characterization of a thermal bridge. It generalizes a measurement of a homogeneous wall thermal resistance. The indoor air is rapidly heated for a few hours (typically 6) and the wall thermal response is analyzed with an inverse technique based on a white-box model. Surface temperatures and heat fluxes are measured with contact sensors on a sound area and these quantities are then extrapolated to nearby thermal bridges using infrared thermography. The total heat transfer coefficient, required in the heat flux extrapolation process, is monitored with a specific device. The method is validated on a full-size load-bearing wall built inside a climate chamber. The mechanical supports, holding the internal insulation system implemented on the wall, generate several thermal bridges. The ψ -values estimated by the active method are less than 20% away from steady-state measurements taken as reference. Many configurations were tested with constant and varying external temperature and the method proved its robustness to these unsteady conditions.

We proposed a real time Total-Variation denosing method with an automatic choice of hyper-parameter $\lambda$, and the good performance of this method provides a large application field. In this article, we adapt the developed method to the non stationary signal in using the sliding window, and propose a noise variance monitoring method. The simulated results show that our proposition follows well the variation of noise variance.

International audience; Edge-bridged halide tantalum clusters based on the {Ta6Br12}4+ core have been the topic of many physico-structural investigations both in solution and in the solid-state. Despite a large number of studies, the fundamental correlations between compositions, local symmetry, electronic structures of [{Ta6Bri12}La6]m+/n- cluster units (L = Br or H2O, in solution and at the solid-state), redox states, and vibrational and absorption properties are still not well established. Using K4[{Ta6Bri12}Bra6] as starting precursor (i: inner, a: apical), we have investigated the behavior of the [{Ta6Bri12}Bra6]4- cluster unit in terms of oxidation properties and chemical modifications both in solution (water and organic solvent) and after recrystallization. A wide range of experimental techniques in combination with quantum chemical simulations afford new data that allow to reveal the puzzling behavior the cluster units in response to changes in their environment. Apical ligands undergo changes like modifications of interatomic distances to complete substitutions in solution that modify noticeably the cluster physical properties. Changes of oxidation state of the cluster units also occur, which modifies significantly their physical properties, including optical properties, which can thus be used as fingerprint. A subtle balance exists between the number of substituted apical ligands and the cluster oxidation state. This study provides new information about the exact nature of the species formed during the transition from solid-state to solutions and vice-versa. This shines new perspectives on optimization protocols for the design of Ta6 cluster-based materials

In this thesis, we aim to propose a methodology for analyzing industrial processes based on a large quantity of process data with statistical and variational methods. The objective is to identify the key factors which ensure the good functioning of industrial processes. It is a preliminary step for the automatic generation of process control law from the collected data. In the first part of this thesis, we presented the statistical analysis of a process of Saint-Gobain. At first, we applied some classical statistical tools (Principal component analysis, clustering and so on) to the process data, and linked the obtained information with the functioning of the process. Then, we analyzed a product quality measure (called target) with the collected process parameters. The target is weakly correlated with the parameters, so the hypothesis of linear model is rejected. A restricted list of parameters which contribute to the explaination of the target was identified by the statistical methods and validated by our industrial interlocutors. Afterwards, we tested a non-linear model method: the generalized additive model (GAM). The introduction of the non-linear terms improved the performance of our model, but it remained insufficient for the future applications. Following the intuition of the process engineers and operators, we focused on a noisy signal, tracked regularly in the plants, characterizing the good functioning of the process, and restoring the missing information of this signal may improve the model. In the second part of this thesis, we developed a total variation restoration method with an automatic choice of hyper-parameter. Furthermore, our proposition of hyper-parameter has a similar performance as the existing methods, and our estimation method of both hyper-parameter and restoration is well fitted for the real time processing of a large quantity of data. Based on the proposed method, we have developed some applications of pattern restoration and discontinuities detection for several industrial processes., Dans cette thèse, nous cherchons à proposer une méthodologie pour analyser des procédés industriels à partir des données procédé collectées à l'aide de méthodes statistiques et variationnelles. L'objectif est d'identifier les facteurs clés garantissant le bon fonctionnement des procédés industriels en vue de la proposition de lois de contrôle de ceux-ci. La première partie présente les résultats d'analyses statistiques appliquées aux paramètres d'un procédé de Saint-Gobain. Nous avons d'abord analysé les données procédé à l'aide d'outils statistiques classiques (l'analyse en composantes principales, la classification non-supervisée, etc.) et cherché à relier les informations ainsi obtenues au fonctionnement du procédé. Puis, nous avons analysé une mesure de qualité du produit final (appelée cible) en fonction des paramètres opératoires. La cible étant faiblement corrélée avec les paramètres enregistrés, l'hypothèse du modèle linéaire est rejetée. Un ensemble restreint des paramètres contribuant à l'explication de la cible a été identifié par les méthodes statistiques utilisées, ce qui a été d'ailleurs validé auprès de l'expert procédé. Ensuite, nous avons testé les modèles additifs généralisés (GAM) en introduisant la non-linéarité dans la modélisation, ce qui a amélioré la performance de nos modèles. Mais les modèles proposés restent insuffisants pour les futures applications. D'après l'intuition des opérateurs et de l'ingénieur process impliqués, un des signaux clés du fonctionnement du procédé était fortement bruité, et une des pistes développées pour améliorer la performance de nos modèles a été de reconstituer les informations manquantes de celui-ci. Pour cela, dans la deuxième partie de la thèse, nous avons développé des méthodes (hors ligne et en ligne) de restauration par la régularisation de variation totale avec la détermination automatique de l'hyper-paramètre. Notre méthode d'estimation de l'hyper-paramètre a une performance similaire aux méthodes existantes dans les littératures scientifiques. Notre méthode pour estimer à la fois la restauration et l'hyper-paramètre est adaptée au traitement d'une grande quantité de données en temps réel. Des applications d'analyse de motifs et de détection de ruptures ont ensuite été développées pour plusieurs procédés industriels.

International audience

International audience; Acoustic comfort arouses interest in sociology, psychology and building industry since the sixties. It can be defined in first approach as the absence of unwanted sounds and the presence of adapted sounds while doing an activity. Comfort is influenced by the acoustic performances of building, by the various types of sound sources, and by individual attitudes (sociological background, musical preferences etc.). In this study, the impact of sound sources on the pleasantness of typical domestic ambiances is investigated using a ?sound design? approach when a composition of sounds is listened coming from three distinct spatialized channels (from outside, from inside the room and from the neighbor). Via a computer interface, 65 people had to adjust the level of the three channels while keeping the overall equivalent level constant at 40 dB(A) in order to design optimized sound scenes. The compositions of the most pleasant sound environments were obtained in reducing SPLs of the neighbor sounds in most situations (TV. documentary, children, work, and party). Two sound masking strategies were revealed. One group preferred to increase the ventilation noise level in the room by 1.5 dB(A), the other group increased sound levels from outside by 2 dB(A). Alternative strategies are found for the two types of musical sounds coming from the neighbor. For classical music, most participants increased in average its sound level by 2 dB(A) Regarding Pop. music, sound preferences lead to 3 sound strategies. People who like Pop. music increased the sound level of this sound source by 3dB(A) in average. One group mixed it with the ventilation in the room, the other with sounds from the outside of the building. People who dislike the Pop music stimulus reduced its sound level by 4.5 dB(A) in average and increased the sound level of the sources coming from the outside.

International audience; β-anhydrite, the stable form of CaSO4, is a common mineral and a key phase in gypsum's dehydration mechanism. An in-depth multi-scale investigation of its structure by powder X-ray diffraction revealed a very slight distortion of the crystal cell at room temperature (β = 90.092(9) °), that led to rule out the commonly admitted orthorhombic model (space group Cmcm) in favor of monoclinic C2/c subgroup. According to high-temperature XRD, the structure resumes however the orthorhombic symmetry around 400 °C.

International audience; When laminated glass shatters under impact, most of the energy dissipation occurs in the coupled delamination and stretching of the polymer interlayer between broken chunks of glass. The strong dependency of these mechanisms on interlayer nature, on loading rate and on temperature has been previously investigated: however, the effect of the interfacial adhesion is unexplored. In this work, a surface modification technique is proposed, along with a mechanical characterization of the debonding with the Through Crack Tensile Test. We show that while increasing adhesion has the effect of enhancing the energy required to propagate the delamination fronts as well as the stretch level of the delaminated interlayer, the dissipation associated to the stretching of the volume of the PVB interlayer seems unaffected. We attribute this effect to the competition between the changes in both stretch and stretch rate in the viscoelastic interlayer. Finally, we discuss the experimental observation of the limits of the steady-state debonding regime, related to the competition between adhesive crack propagation and cohesive failure in the interlayer.

International audience; This article presents a simple thermal characterization method, noted CFM, for the measurement of the apparent thermal conductivity of insulating materials at high temperature (i.e., up to 600°C). The CFM method is a steady-state relative measurement method which requires a calibration. The calibration of the experimental apparatus was done with a calcium silicate board of known thermal conductivity. Thermal conductivity measurements were carried out on a low-density compressible fibrous felt and a high-density calcium silicate board between 100 and 600°C. A good agreement was observed with the values obtained with the guarded hot-plate (GHP) method for the low-density fibrous felt and the parallel hot-wire (PHW) method for the high-density calcium silicate board. The measurement of the apparent thermal conductivities of low-density fibrous felts of different apparent densities, combined with a simple conducto-radiative model, allowed to estimate a mean specific extinction coefficient in good agreement with a value derived from transmittance/reflectance measurements. Keywords Insulating material. High temperature. Thermal conductivity 1 Introduction Knowledge of the thermal conductivity of insulating materials at high temperature is of great importance for the control of industrial processes. For example, the cooling rate of a liquid metal in a mold (which has a great influence on the mechanical properties of the molding) is highly dependent on the thermal resistance of the surrounding insulation. Thermal insulation materials are usually porous materials. Their thermal transport properties, at a macroscopic scale, are not intrinsic values since they depend on the local structure of the material (i.e., porosity, tortuosity) [1] and the contributions of several heat transfer modes (i.e., conduction, convection and/or radiation). The term apparent (or effective) thermal conductivity is thus used for porous materials. The characterization of the thermal transport properties (i.e., thermal conductivity and thermal diffusivity) of materials can be performed with a large variety of methods. The choice of the method depends on the following criteria: the nature of the material, the size and shape of the specimen, the temperature range, the thermal conductivity and thermal diffusivity range, the uncertainty of measurement [2].

International audience; We report an experimental study of the compaction behaviour of zirconia granules formed by a spray drying process. Using two different binders that were fully characterized, we have investigated the influence of the binder spatial distribution in the granules on compaction of a granule packing. Spatial distributions were modified by tuning binder adsorption on the ceramic nanoparticles in the spray dried suspensions. Granule powders with binder either located between nanoparticles only, or partly concentrated within a segregated layer at the surfaces of granules were thus obtained. We have found the role of the segregated layer is fully negligible during granule compression, and we justify that result by providing estimates of the theoretical compression energies of segregated layers and polymer bridges. We discuss the role of the binder bridges between nanoparticles, and we suggest a picture accounting for the experimental influence of binder mechanical properties and concentration on the compaction behaviour of spray-dried granules.

International audience; This article presents a temperature-temperature thermal characterization method for the measurement of the thermal diffusivity of insulating materials at high temperature. This novel method, noted 4L, is a transient absolute measurement method based on the estimation of the transfer function at the center of a symmetrical stack composed of two specimen of an insulating material sandwiched between two conductive metallic plates. Two different direct 1D semi-analytical models were developed. The first one considers purely conductive opaque materials and the second one takes into account the coupling between radiative and conductive heat transfer modes for purely scattering semi-transparent materials. The first model was used to estimate the thermal diffusivity of two different opaque insulating materials (calcium silicate boards) up to 800°C with accuracy better than 10%. The second model was used to estimate the thermal diffusivity of a semi-transparent insulating material (ceramic foam) up to 1000°C with an accuracy of approximately 10%. The second model was used to identify significant estimation errors occurring if a purely conductive model is used for semi-transparent materials. The conducto-radiative model was also used to estimate an average value of the mean extinction coefficient of the semi-transparent material. Nomenclature thermal diffusivity [m 2 s-1 ] specific heat of the sample [J kg-1 K-1 ] thickness of the samples [m] transfer function (real space) transfer function (Laplace space) directional monochromatic radiative intensity [W m-1 ] () black body monochromatic radiative intensity at [W m-1 ] refractive index Δ′ ⃗ → Δ ⃗ scattering phase function Laplace parameter [s-1 ] conduction heat flux [W m-2 ]

International audience; The performances of Pressure Sensitive Adhesives (PSA) are generally evaluated using different loading geometries such as tack, peel and shear tests. It is difficult to link the behaviors of PSAs in these different geometries, and to predict the result of one test from another, because the confinement of a soft and dissipative material prevents the use of standard fracture mechanics, which separates the interface debonding behavior from the dissipation associated with the bulk deformation. We present here an original experimental investigation based on the modeling strategy proposed by Creton and Ciccotti[1]. Using instrumented versions of both peel and tack measurements, we compared the adherence performances of a series of model PSAs based on styrene-isoprene block copolymers, while identifying the mesoscale mechanisms at play during debonding. This analysis method allows us to model the contribution of the large strain rheology of the PSAs in the total work of debonding. We clearly show that both the adherence performances and local mechanisms can be closely related between peel and tack when considering both similar confinement and a similar strain rate of the fibrils that are spontaneously formed during debonding. While the overall adherence properties change by a factor of 3 between the different samples, the peel tests only present a minor +20% bias in adherence, which can be attributed to the combination of a 10% increase in the average stress and a 10% increase in the maximum strain of the fibrils. This improvement in the understanding of the PSA performances opens the way to a more sound mechanical design of PSA based joints.

International audience; The morphology, epitaxy, band-alignment and optical response of silver nanoparticles on ZnO(1010) has been analysed by microscopy, photoemission, electron diraction and dier-ential reectivity. At 700 K, clusters tend to nu-cleate and grow exclusively along [010]-oriented polar steps and corners, and not on at terraces or non-polar [001] steps. This preference leads to a specic epitaxy Ag(111)[110] ZnO[010](1010) with a large lattice mismatch along the dense row of the metal. The experiments have been rationalized through ab ini-tio simulations. A much lower adsorption energy is obtained for the O-terminated steps with a charge transfer from silver to oxygen, that corroborates the variation of ionization energy observed in photoemission and the presence of cationic silver. This anisotropy of growth reverberates in the plasmonic response of the metallic particles. The growth and epitaxy of metals on the polar (0001) and non-polar (1010) ori-entations of ZnO is discussed in terms of sur-face/step polarity compensation in the light of the present ndings.

International audience; Classical in situ measurement methods of building wall thermal resistance are based on steady-state assumptions. This limits their applicability given their high sensitivity to outdoor conditions and the duration required to obtain accurate results. To overcome these limitations, the present paper introduces an in situ method for the assessment of building wall thermal resistance. It is based on rapid active measurements: indoor air is heated for several hours. In addition, unlike common active methods based only on temperatures, the proposed method is based on measurements of a heat flux and one or several temperatures. Two approaches are implemented and compared to estimate wall thermal characteristics from measurements. In the first approach, inverse technique are used based on "white-box" models derived from the heat equation. The best direct model to choose depends on the type of wall tested and weather conditions. In the second approach, ARX "black-box" models are used. The proposed methods were thoroughly tested on a full-size load-bearing wall equipped with a classical internal insulation system commonly found in french buildings. The wall was built inside a climate chamber in order to assess the robustness of the methods to various outdoor conditions. The results demonstrated that, for type of wall, both approaches lead to accurate and repeatable results if the external temperature remains roughly constant. With varying external conditions, white-box models remained accurate while ARX "black-box" models did not.

International audience; The performance gap between the design and the as-built energy performance of buildings is considered a significant risk that may compromise the efforts on meeting the carbon reduction targets set by governments in Europe. The relative importance of irregularities or defects within building walls is more prominent when the thermal insulation level increases. It is thus necessary to quantify the global thermal insulation level of building walls (i.e., including thermal bridges). Classical contact measurement methods only allow local measurements and would thus require the use of a high number of sensors which would limit their applicability. Besides, the presence of thermal bridges prevents the use of contact heat flux measurements because of the 2D or 3D nature of the associated heat transfers through the building walls. To overcome these limitations, the present study proposes an alternative approach consisting in measuring the heat flux on one location and extrapolating its value on the whole building wall through the measurement of the total heat transfer coefficient. Therefore, we developed and/or further improved five different in situ measurement methods of the total heat transfer coefficient on building walls. The measurement methods were thoroughly tested indoor thanks to lab-scale experiments carried out both in steady-state and transient regimes. The results obtained demonstrated the accuracy and the robustness of the proposed methods, as well as their intrinsic limitations. These in situ methods can be used to assess the heat losses on a whole building wall, including the contribution of thermal bridges.

International audience; PTFE presents an original secondary crystallization that appears to be independent of the primary one. The conjunction of differential scanning calorimetry and dilatometry experiments has offered complementary data to study both crystallization melted compacted powder and of recrystallized samples. The primary crystallization is responsible for the crystallinity content variation with the cooling rate. It preserves the anisotropy induced by previous compaction that can be observed by dilatometry. Conversely, the secondary crystallization appears to be instantaneous, reversible, kinetic-free and isotropic. It occurs over a wide temperature range between 250°C and 310°C.

International audience; This article addresses a particular realization of a compact bistable nonlinear absorber based on the concept of Nonlinear Energy Sink. The article presents both a detailed description of the absorber mechanics and an illustration of the targeted energy transfer between the absorber and a linear system. The experimental results are accompanied with the numerical simulations. Beside practical improvements linked to the features of absorber design, the obtained results stay in line with those found for simpler realizations of a bistable Nonlinear Energy Sinks.

International audience

The charging properties of a particle during a single impact have been studied before in research. Despite these contributions, there remains incomprehension on the very mechanisms responsible for the charge transfer and predictions regarding the tribocharging of a dielectric particle against another dielectric material are still rather unreliable. Glass, found with various different chemical compositions, is a good example of a material that defies the expectations of triboelectric series. This article reports the development of a setup measuring the charge generated by a single impact between a glass bead and a dielectric. The setup is designed to control most relevant parameters to achieve the highest level of reproducibility possible, and to perform series of tests to maximize statistical relevance. Preliminary results on parameters such as the normal velocity at impact, the relative humidity and the impact angle are described.

International audience; Within the framework of a renovation project in Stockholm area (Sweden), in situ measurements were carried out with the QUB/e method to (i) assess the actual thermal performance of the building fabric and (ii) validate the thermal upgrade measures implemented. Two consecutive QUB/e tests were performed in an apartment of a fully renovated multi-storey residential building. The average U-values were 0.64 ± 0.04 W m −2 K −1 and 0.25 ± 0.02 W m −2 K −1 for the glazings and the external walls, respectively. The measured values were in good agreement with the calculated values communicated by the municipality. A comparison of in situ measurements undertaken before and after the implementation of the thermal upgrade measures indicates that a threefold decrease of the U-values (i.e.,-67%) was achieved. This was consistent with the target set by the municipality (i.e.,-60%). The thermal performance of the building fabric resulting from the thermal upgrade measures implemented (using off-the-shelf solutions) could thus be considered validated.

National audience; Cette étude vise à déterminer la fenêtre de paramètres optimum (pression, temps, température) pour réaliser le soudage entre deux surfaces de PTFE et comprendre les mécanismes d'adhésion entrant en jeu. Les principaux mécanismes responsables de l'adhésion à l'interface polymère/polymère sont présentés puis leur caractérisation expérimentale est exposée. Abstract This study aims to determine the optimum parameters (pressure, time, temperature) to achieve welding between two PTFE surfaces and to understand the adhesion mechanisms involved. The main mechanisms responsible for adhesion of polymer-to-polymer interface are presented and then their experimental characterization is exposed.

This paper proposes areas of improvement for Low Power Wide Area (LPWA) solutions. After recalling the rationale of these systems, it summarizes the main challenges of existing solutions and proposes various improvements at PHY and MAC layer that were investigated in context of the EPHYL project. NB-IoT and LoRa were mostly considered in the analysis of existing techniques, while proposals for improvement address both waveform design and resource allocation strategy. We propose as well introduction of new paradigm such as network coding to benefit of the sparse characteristic of some LPWA use cases. Some of the proposals are validated experimentally in the FIT/CorteXlab environment, offering to the research community a framework to experiment and compare their improvements of LPWA systems.

International audience; Cette étude porte sur la mesure des propriétés thermiques des ponts thermiques dans les bâtiments. La méthodologie est testée sur une maquette de mur en laboratoire. Les coefficients de transmission psi ou chi de chacun des 3 types de ponts thermiques présents dans la maquette sont mesurés par thermographie infrarouge en régime stationnaire. Pour cela, le facteur d'impact Itb des ponts est calculé. Dans la démarche proposée, la connaissance de l'émissivité de la surface n'est pas nécessaire car seules les températures apparentes sont exploitées. Les expériences ont montré une bonne reproductibilité ainsi qu'un bon accord avec des simulations numériques. Le calcul des incertitudes a permis d'identifier les principales sources d'erreur.

Experiments and simulation results are compared in order to make precise the conditions optimizing both the kinetics of plaster hydration and the structure of the resulting material. Calorimetry experiments performed for different amounts of added gypsum seeds are used to assign values to the simulation parameters controlling kinetics, e.g. time step, surface density of gypsum germs on plaster grains. Simulation provides a reliable quantity to follow the beginning of setting, the fraction of gypsum needles belonging to a percolating cluster, as proven by comparing its evolution with the one of the elastic modulus during shear experiments. The simulations reveal that the beginning of needle growth may be hindered by two many small plaster grains, whereas big plaster grains slow down the end of the reaction. We suggest to add gypsum germs with an m g / m p = 0.002 gypsum-to-plaster mass ratio in order to optimize homogeneity of the final material.

National audience

This article describes a statistical analysis applied on a centrifugation process of Saint-Gobain. The correlations within data were analysed by PCA, and some statistical models were built using information from the previous step. The final purpose is to build a control law for the centrifugation process through this statistical analysis. The work is still ongoing, but the first results already show which process steps play an important role in the final product's quality., Cet article présente une analyse statistique des données issues d'un procédé de centrifugation utiliséà Saint-Gobain. Les différentes corrélations entre les variables enregistrées ontété analysées via une ACP, et sur cette base plusieurs modèles statistiques ontété proposés. L'objectif final est de proposer un processus de contrôle de procédé de centrifugationà travers cette analyse statistique. Ce travail est actuellement en cours mais les résultats obtenus indiquent déjà quellesétapes du procédé industriel pourraient jouer de manière prépondérante sur la qualité du produit final.

Place: France; Thoracic ultrasound (TUS) is increasingly studied in neonatal respiratory distress but chest x-ray (CXR) remains the first-line exam. We aimed to evaluate its diagnostic performance for the investigation of unselected causes of neonatal respiratory distress in daily practice. We conducted a descriptive, prospective, and single-center diagnostic accuracy study in a tertiary hospital, including term and preterm newborns who needed a CXR because of respiratory conditions occurring at birth or during the first 24h of life. TUS was compared to the reference diagnosis, which was the association between the CXR results, the clinical initial context, and the patient's outcome. Fifty-two newborns were included and 104 hemi-thorax ultrasounds were analyzed. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), diagnosis accuracy, as well as the positive and negative likelihood ratio of TUSs were 100% for respiratory distress syndrome (RDS), transient tachypnea of newborn (TTN), pneumomediastinum, meconium aspiration syndrome, and absence of pulmonary disease. TUS also showed 100% sensitivity and NPV for pneumothorax, but specificity was 97% and PPV was 50%. Kappa concordance between TUS and either CXR alone or the radiological/clinical gold standard was 0.79 and 0.95, respectively. CONCLUSION: TUS at the newborn's bedside is efficient for investigating the main neonatal respiratory diseases, especially for the confirmation of RDS or TTN and for the exclusion of differential diagnosis or complications.

International audience; Cold uniaxial pressed PTFE compacts were subjected to thermal cycles of increasing maximum temperature below melting temperature, and thermal expansion was followed in both the compaction and transverse directions. The measurements reveal that thermal expansion consists of two distinct contributions: i) an irreversible part that is controlled only by the maximum temperature experienced by the sample, and ii) a reversible, or thermo-elastic, part that is observed while cycling below the maximum temperature. Moreover, both of these thermal strains exhibit marked anisotropy, resulting from the cold oedometric compaction of the sample. A quantitative analysis of these eigenstrains is proposed, following a formal analogy with elasto-plasticity. Finally, it is shown that such behavior is specific to cold-pressed compacts as sintered samples exhibit isotropic and purely reversible thermo-elastic behavior.

International audience; For decades, poly(vinylbutyral) (PVB) has been the polymer of choice to improve the impact resistance of laminated glass. PVB presents large rupture strain, large tensile strength and excellent dissipative properties. Here we investigate the relation between macromolecular structure and mechanical properties of plasticised PVB by combining large strain tensile experiments with calorimetry, X-ray and birefringence measurements. We find that the mechanical response is dominated by creep and that this plastic-like flow can effectively be described by a strain dependent viscosity. The commonalities with other toughened polymeric materials are outlined, and especially the role played by phase separated domains with weaker physical bonds. These results could help optimize polymer design for toughness and impact applications.

International audience

Poster Session 1 : Materials, Chemicals, Thin films & Nanomaterials, Thermal Processing and Applications - ISBN 978-3-940237-50-7; International audience; Gypsum is the mineralogical used term to describe materials that are mainly constituted of calcium sulfate dihydrate (CaSO4.2H20). The calcination of gypsum, i.e. the dehydration of gypsum under solid-gas conditions, is of great technological importance because it represents the main industrial process for the production of plaster, the inorganic material with the largest production in the world. Plaster, in turn, is mainly constituted of calcium sulfate hemihydrate (CaSO4.0.5H20). In spite of the significance of these materials for this and other scientific fields, some important aspects of the chemical system CaSO4- H20 are still unknown. In particular, the water content within the gypsum calcination products is only partially described in the literature.This absence of a complete understanding of this system despite its importance and the fact Chat these materials have been used since antiquity can be attributed to several phenomena Chat contribute to its complexity. First of ail, the literature acknowledges the existence of several calcium sulfate polymorphs. For instance, the dehydration of gypsum can lead to different calcium sulfate hydrates of the form CaSO4•&#949H2O, where &#949 can be 0.625, 0.5, or 0, depending on the temperature (T) and water vapor partial pressure (P) under which the reaction takes place. Moreover, these compounds can also present zones of divariance, i.e., domains where the overall water content of these hydrates can change continuously with T and P. The fine knowledge of the stability domain of each species throughout successive thermal transformations of the CaSO4.2H20 is still debatable. In this context, the objective of the present work is to determine the stability conditions and domains for the CaS04.2H20 dehydration products. Furthermore, the nature of the divariant behavior is also investigated. Thermogravimetric analysis under isotherm and isobaric conditions using different protocols with temperature ranges of 30°C to 250°C and water vapor partial pressure ranges of 5 hPa to 60 hPa was performed. The results allowed the determination of two zones of divariance and one univariant domain. The variations of the measured water contents in contrast with the stoichiometry of each polymorph were interpreted with models adapted for each zone. Finally, a phase diagram P-T is proposed based on the stability domain of each phase, and values of change in enthalpy and entropy of reaction were obtained for each transformation and compared with previously published values.

National audience; Le terme gypse est employé pour désigner les minéraux principalement constitués de sulfate de calcium dihydraté, CaSO4·2H2O. Ce matériau a une grande importance industrielle puisque sa calcination (ou déshydratation partielle) est le principal procédé de fabrication du plâtre, qui est le produit inorganique avec la plus grande production industrielle au monde. Ce produit est majoritairement constitué de sulfate de calcium hémi-hydraté, CaSO4·0,5H2O. Malgré cette importance et le fait que ces matériaux soient utilisés depuis l’antiquité, le système minéral CaSO4-2H2O reste mal connu. Surtout concernant les teneurs en eau des produits de calcination du gypse. Cette absence d’une compréhension complète des transformations de ce système est due à plusieurs phénomènes qui contribuent à sa complexité. D’abord, celui-ci possède plusieurs polymorphes : lors de la déshydratation du sulfate de calcium dihydraté, différents hydrates du type CaSO4·&#949H2O peuvent être obtenus, où &#949 peut valoir 0,625, 0,5, ou 0 selon les conditions de température T et pression partielle de vapeur d’eau P. De plus, ces composés peuvent aussi présenter des zones de divariance, i.e., des domaines où la teneur globale en eau &#949 peut changer continument selon T et P. La connaissance fine des domaines de stabilité de chaque espèce et des mécanismes réactionnels mis en jeu au cours des transformations thermiques successives du sulfate de calcium dihydraté reste à ce jour sujet à discussion. Les mécanismes de déshydratation et hydratation en voie solide-gaz ne sont que partiellement décrits dans la littérature scientifique. Dans ce contexte, l’un des objectifs de ce travail est donc la connaissance des phases et des transformations impliquées, lors de la déshydratation de poudres de sulfate de calcium dihydraté. De plus, la nature de la divariance pour ce système est également investiguée. Des expériences de thermogravimétrie en conditions isothermes et isobares, selon différents protocoles, ont été réalisées dans une gamme de température allant de 30ºC à 250ºC pour des pressions partielles de vapeur d’eau comprises entre 5 et 60 hPa. Les résultats obtenus permettent l’identification de deux domaines de divariance et d’un domaine de monovariance. Les variations des teneurs en eau par rapport à la stœchiométrie de chaque polymorphe sont interprétées à travers des modèles adaptés à chaque domaine de divariance. Des valeurs de variation d’enthalpie et d’entropie sont ainsi obtenues pour les différentes transformations. Enfin, un diagramme de phase « température-pression de vapeur d’eau » est proposé en se basant sur la stabilité des différentes phases obtenues dans les gammes de température et pression de vapeur d’eau investiguées.

International audience; Dans le cadre d’une thèse Cifre entre l’industriel Saint-Gobain Recherche (SGR) et l’Université de CergyPontoise (UCP), un laboratoire de restitution sonore écologiquement valide a été installé dans les locaux récents de la maison de la recherche à Neuville sur Oise (UCP) afin de reproduire les ambiances sonores spatialisées intérieures, typiques des logements résidentiels en ville. Ce laboratoire se situe naturellement dans un environnement très calme et dispose d’une forte isolation acoustique. L’environnement intérieur à reproduire est celui d’un salon et le système d’écoute consiste en un ensemble de 16 haut-parleurs et d’un caisson de basse contrôlés par un processeur numérique. A travers ce système d’écoute à géométrie modulable, des environnements sonores conçus pourront être restitués spatialement par la méthode VBAP ou par Ambisonied’ordre 1 ou 2 notamment. Des tests d’écoute se dérouleront dans ce laboratoire pendant toute l’année 2018 pour répondre à la problématique du confort acoustique dans le logement résidentiel. Ils visent à rendre compte de l’influence de deux facteurs distincts sur la perception du confort sonore au domicile. Le premier facteur est lié aux différents types de sources sonores qui pénètrent le logement, et le second facteur représente lesperformances acoustiques des systèmes constructifs du bâti. Pour le premier facteur, les provenances spatiales seront maîtrisées: le bruit des voisins (venant du plafond ou latéralement), des parties communes, et de l’extérieur via la fenêtre. Pour le second facteur, un filtrage multicanal sera appliqué pour simuler l’isolement des dispositions constructives choisies. Pour répondre à cette problématique, 60 participants suivront une série de trois tests perceptifs distincts. Les deux premiers tests respecteront une approche psycho-acoustique par une écoute active des participants tandis que le dernier test demandera aux participants de s’impliquer dans une tâche cognitive.

Le prix Jean Besson a été décerné à João Preturlan.Le prix « Jean BESSON » vient récompenser l’exposé jugé scientifiquement et pédagogiquement le meilleur à l’issue de cette première journée.; National audience; Le terme gypse est employé pour désigner les minéraux principalement constitués de sulfate de calcium dihydraté, CaSO4·2H2O. Ce matériau a une grande importance industrielle puisque sa calcination (ou déshydratation partielle) est le principal procédé de fabrication du plâtre, qui est le produit inorganique avec la plus grande production industrielle au monde. Ce produit est majoritairement constitué de sulfate de calcium hémi-hydraté, CaSO4·0,5H2O. Malgré cette importance et le fait que ces matériaux soient utilisés depuis l’antiquité, le système minéral CaSO4-H2O reste mal connu. D’abord, celui-ci possède plusieurs polymorphes : lors de la déshydratation du sulfate de calcium dihydraté, différents hydrates du type CaSO4·&#949H2O peuvent être obtenus, où &#949 peut valoir 0,625, 0,5, ou 0 selon les conditions de température T et pression partielle de vapeur d’eau P. De plus, ces composés peuvent aussi présenter des domaines de divariance, i.e., la teneur globale en eau ε peut changer continument selon T et P. La connaissance fine des domaines de stabilité de chaque espèce et des mécanismes réactionnels mis en jeu au cours des transformations thermiques successives du sulfate de calcium dihydraté reste à ce jour sujet à discussion. Les mécanismes de déshydratation et hydratation en voie solide-gaz ne sont que partiellement décrits dans la littérature scientifique. Dans ce contexte, l’un des objectifs de ce travail est donc la connaissance des phases et des transformations impliquées, lors de la déshydratation de poudres de sulfate de calcium dihydraté, et la détermination des étapes élémentaires mises en jeu ainsi que les lois cinétiques associées. Des expériences en thermobalance en conditions isothermes et isobares ont été réalisées dans une gamme de température allant de 30 à 250°C pour des pressions partielles de vapeur d’eau comprises entre 5 et 60 hPa. Des caractérisations physico-chimiques des solides obtenus ont aussi été réalisées. Les résultats permettent de déterminer précisément les zones de divariance et de monovariance. Un modèle cinétique de germination-croissance a pu être proposé et appliqué aux données expérimentales.

Dispersing carbon nanotubes (CNTs) using surfactants into water requires ultrasonication that supplies mechanical energy to debundle and exfoliate CNTs. However, sonication is known to damage CNTs and to cut them into short fragments. Also, the CNT concentration in water dispersion is typically limited to up to 1.0 wt %. Here, we show that by using a sulfuric acid pretreatment, we can enhance the debundling of CNTs and reduce subsequent sonication to achieve homogeneous dispersions without damaging CNTs. Additionally, using a progressive and controlled dialysis, we are able to increase the CNT concentration up to 1.8 wt %. We demonstrate that such highly concentrated dispersions can be used as spin dopes to fabricate continuous fibers. Our fibers have an electrical conductivity up to 580 kS/m, a tensile strength of ∼1 GPa, and a Young’s modulus of 123 GPa, exceeding the mechanical properties of related fibers made from conventional surfactant-stabilized dispersions of sonicated CNTs.

International audience; Foams made with polymer hydrogels can be used in a variety of applications, such as scaffolds for biomedical applications or decontamination processes. However, from a practical point of view, it is difficult to introduce bubbles into viscous or viscoelastic fluids and to produce large volumes of hydrogel foams. In the present article, we investigate the foaming process of poly(vinyl alcohol) (PVA)/borax transient hydrogels, where PVA chains reversibly bind to borax molecules. In a previous article, we showed that foams obtained with PVA/borax mixtures are highly stable because of both high interfacial and bulk viscosities and can be used to quickly absorb liquids, which make them suitable for detergency or decontamination processes. To produce these foams, we use a two-step foaming process which consists in first shearing a PVA solution to obtain a PVA foam and second adding borax to the PVA foam under continuous shearing. The obtained PVA/borax foams are stable for weeks. In this study, we observe a shear-induced collapse of the foams for formulations containing a low borax/PVA ratio, whereas they remain stable under shear for high PVA/borax ratios. Using scaling arguments, we find that the shear-induced collapse of the foams and bubbles is obtained below a critical ratio, NE/NB = 15, of the number of entanglements per chain, NE, and the number of borax per chain, NB. Rheology measurements show that the samples present a shear-thickening behavior that increases with the borax concentration. We suggest that during the foaming process when the shearing rate is of the order of 100 s–1, the viscosity of these samples diverges, leading to a viscous to fragile transition. To mimic the fast stretching of the PVA/borax thin films during the foaming process, we study the stretching of individual PVA/borax catenoid-shaped thin films at high stretching rates. We observe that the films containing low PVA/borax ratios do not minimize their surface area unlike what is theoretically expected for standard surfactant films. Moreover, the films tend to be unstable and fracture because the PVA/borax network does not have time to rearrange and relax stresses for high stretching rates.

Objectives There is no consensus about the performances of genotypic rules for predicting HIV-1 non-B subtype tropism. Three genotypic methods were compared for CRF01_AE HIV-1 tropism determination. Methods The V3 env region of 207 HIV-1 CRF01_AE and 178 B subtypes from 17 centers in France and 1 center in Switzerland was sequenced. Tropism was determined by Geno2Pheno algorithm with false positive rate (FPR) 5% or 10%, the 11/25 rule or the combined criteria of the 11/25, net charge rule and NXT/S mutations. Results Overall, 72.5%, 59.4%, 86.0%, 90.8% of the 207 HIV-1 CRF01_AE were R5-tropic viruses determined by Geno2pheno FPR5%, Geno2pheno FPR10%, the combined criteria and the 11/25 rule, respectively. A concordance of 82.6% was observed between Geno2pheno FPR5% and the combined criteria for CRF01_AE. The results were nearly similar for the comparison between Geno2pheno FPR5% and the 11/25 rule. More mismatches were observed when Geno2pheno was used with the FPR10%. Neither HIV viral load, nor current or nadir CD4 was associated with the discordance rate between the different algorithms. Conclusion Geno2pheno predicted more X4-tropic viruses for this set of CRF01_AE sequences than the combined criteria or the 11/25 rule alone. For a conservative approach, Geno2pheno FPR5% seems to be a good compromise to predict CRF01_AE tropism.

Oral Presentations 2 : Theory & Methods, Kinetics & Catalysis, Fuels & Biofuels, Energetics and Applied Thermal Engineering - ISBN 978-3-940237-50-7; International audience; Gypsum is the mineralogical term used to describe materials that are mainly constituted of calcium sulfate dihydrate (CaSO4.2H20). The calcination of gypsum to produce plaster is a large -scale industrial process with paramount importance for the modern construction materials industry. During this process, two main dehydration reactions usually occur during calcination depending on temperature and humidity conditions: CaSO4.2H2O dehydrates to hemihydrate (CaSO4.0.5H20) and the latter can also dehydrate forming soluble anhydrite (CaS04). Despite the fact Chat the literature in gypsum dehydration is considerably extensive, there is a substantial lack in accordance about several aspects of the aforementioned dehydration reactions. For instance, there is no accordance if the type of kinetic model to be used to describe the reaction needs to take accourt of both nucleation and growth or only one of these processes. Furthermore, when the nucleation and growth processes are considered, the JMAEK model is generally used, which lacks in physical meaning for solid-gas reactions. In addition, as there is no accordance concerning the employed kinetic models, published reaction mechanisms and apparent activation energy values also Biffer. Hence, the lack in accordance about several aspects of these reactions makes it necessary to investigate in detail the intrinsic chemical reactivity of this system. In this context, one of the objectives of the present work is to describe and analyze with precision the different solid-gas transformations within the chemical system CaSO4-H20 and clarify remaining questions on reaction kinetics still present in the literature. In order to perform this, the dehydration of a highly pure calcium sulfate dihydrate powder was monitored using thermogravimetric analysis under isotherm and isobaric conditions to obtain kinetic curves. Temperature ranging from 30°C to 250°C and water vapor partial pressure ranging from of 5 hPa to 60 hPa were investigated. Morphological and textural characterizations of the solids were also employed to understand the way of transformation. Based on this knowledge, a kinetic nucleation-growth model was then proposed and applied to the experimental data in order to obtain kinetic parameters for nucleation and growth. A growth mechanism was written and the change of kinetic parameters with temperature and water vapor partial pressure was explained.

International audience; Demand response (DR) at the building level (also named energy flexibility) will play an important role in facilitating energy systems based mostly or entirely on renewable energy sources. Flexibility is thus deemed necessary to control the energy consumption to match the actual energy generation from various renewable energy sources such as solar and wind power. However, there is lack of comprehensive knowledge about how much energy flexibility different building types and their usage may be able to offer to the present or future energy systems. In this study, the flexibility potential of space heating is characterised among the building stock in France. Five different typologies of buildings were chosen (post-1945, BR 1982, BR 2005, BR 2012 and BR 2020) with different levels of insulation, air-tightness and thermal mass. Building energy simulations were performed, with modulations (i.e. increase or decrease) of the space heating set-point during the heating season. From this study, the large influence of the envelope properties on the flexibility potential was highlighted: the storage efficiency for upward modulations and the rebound rates for downward modulations range from 40% up to 90% in poorly insulated and well-insulated buildings, respectively. This study describes a generic method and provides quantitative data to estimate the flexibility potential for demand response at the building level and to help designing future energy grids.

International audience; Reinforcing clamps made of low alloy steel from the Metz cathedral and corroded outdoors during 500 years were studied by OM, FESEM/EDS, and micro-Raman spectroscopy. The corrosion product layer is constituted of a dual structure. The outer layer is mainly constituted of goethite and lepidocrocite embedding exogenous elements such as Ca and P. The inner layer is mainly constituted of ferrihydrite. The behaviour of the inner layer under conditions simulating the wetting stage of the RH wet/dry atmospheric corrosion cycle was observed by in situ micro-Raman spectroscopy. The disappearance of ferrihydrite near the metal/oxide interface strongly suggests a mechanism of reductive dissolution caused by the oxidation of the metallic substrate and was observed for the first time in situ on an archaeological system.

National audience; Une méthode pulsée est utilisée pour estimer les propriétés thermiques et radiatives des matériaux semi-transparents à l’état liquide à haute température (i.e., pour des températures supérieures à 1000 °C). Le modèle direct développé prend en compte le caractère tridimensionnel destransferts thermiques et néglige les transferts thermiques convectifs dans le liquide car les nombres de Rayleigh sont suffisamment faibles. Le couplage conducto-radiatif est traité à l’aide de la méthode des harmoniques sphériques (PN). L’identifiabilité des propriétés thermiques et radiatives est investiguée à l’aide d’une étude de sensibilité aux paramètres suivants : la diffusivité thermique, le coefficient de pertes thermiques, l’épaisseur optique, le nombre de Planck, l’émissivité interne des parois et la valeur maximum du thermogramme. Une étude stochastique de l’estimation des paramètres est ensuite menée à partir de thermogrammes bruités générés avec le modèle direct conducto-radiatif.

International audience