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International audience; In this work, the crosslinking reaction of partially carbonated epoxidized soybean oils with different diamines was investigated. To this end, a series of carbonated soybean oils (CSBO), with a carbonation ratio ranging from 45% (CSBO45) to 98% (CSBO98) were synthesized by CO2 carbonation of epoxidized soybean oil (ESBO). The relative aminolysis rate of the carbonate and epoxide functions of CSBO45, and also of the esters of the triglyceride skeleton, was monitored through an unprecedented combination of in situ infrared and Raman spectroscopy at various temperatures T (60 °C ≤ T ≤ 150 °C). Interestingly, two regimes are identified: (i) for T < 100 °C, a PHU regime, during which all the carbonate functions of CSBO45 react to provide an uncrosslinked PHU prepolymer (viscous liquid), (ii) for T ≥ 100 °C, a hybrid regime, during which the epoxide functions react to provide a hybrid thermosetting polymer (elastic solid). For the first time, we report the “conversion vs. time” plots for the aminolysis of epoxide in ESBO and partially carbonated ESBO. They indicate that the initiation of the reaction is thermally delayed as compared to the aminolysis of the corresponding carbonates. Surprisingly, the sol–gel transition of CSBO45 is correlated to the initiation of epoxide aminolysis, a counterintuitive conclusion given that ESBO cannot be crosslinked by a diamine under the same conditions. These results suggest that the combination of reactive carbonates with sluggish epoxides results in a decrease of undesirable side reactions such as ester aminolysis and intramolecular cyclization. Finally, general guidelines can be recommended for the stepwise synthesis of triglyceride-based hybrid poly(hydroxyurethane) thermosets.

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.

International audience; The high potential of [{Nb6Cli12}La6] cluster-based building blocks as near-infrared radiation blockers for energy saving applications is exposed in the present paper (i = inner edge-bridging ligand, a = apical ligand of the Nb6; L = H2O and/or Cl). To do so, a combined experimental and theoretical investigation of edge-bridged [{Nb6Cli12}Cla6–x(H2O)x]m+/0/n− cluster unit series (x = 0, 4, 6; m = 2, 3, 4; n = 2, 3, 4) has been carried out. By using the K4[{Nb6Cli12}Cla6] starting solid-state precursor, we explored the behavior of the [{Nb6Cli12}Cla6]4– cluster unit during the different steps of its integration as a building block into a polyvinylpyrrolidone (PVP) matrix to form a glass coating composite denoted {Nb6Cli12}m+@PVP (m = 2 or 3). The optical, vibrational and redox properties [{Nb6Cli12}Cla6–x(H2O)x]m+/0/n− building blocks have been interpreted with the support of electronic structure calculations and simulation of properties. The chemical modifications and oxidation properties have been identified and studied thanks to various techniques in solution. Combining Raman and ultraviolet–visible spectroscopies, electrochemistry, and quantum chemical simulations, we bring new knowledge to the understanding of the evolution of the properties of the [{Nb6Cli12}Cla6–x(H2O)x]m+/0/n− cluster units as a function of the number of valence electron per cluster (VEC) and the nature of terminal ligands (x = 0, n = 4; x = 4, charge = 0; x = 6, m = 4). The fine understanding of the physical properties and vibrational fingerprints depending on the VEC and chemical modifications in solution are mandatory to master the processing of cluster-based building blocks for the controlled design and shaping of glass coating nanocomposites. On the basis of this acquired knowledge, [{Nb6Cli12}Cla6–x(H2O)x]m+/0/n− building blocks were embedded in a PVP matrix. The resulting {Nb6Cli12}2+@PVP nanocomposite film shows excellent ultraviolet (UV, 280–380 nm) and near-infrared (NIR, 780–1080 nm) blocking ability (>90%) and a highly visible light transmittance thanks to the controlled integration of the {Nb6Cli12}2+ cluster core. The figures of merit (FOM) value of Tvis/Tsol (Tvis = visible transmittance and Tsol = solar transmittance) as well as the haze, clarity, and the NIR shielding values (SNIR) were measured. After optimization of the integration process, a {Nb6Cli12}2+@PVP nanocomposite on glass substrate has been obtained with a high FOM equal to 1.29. This high value places the transparent green olive {Nb6Cli12}2+@PVP nanocomposites at the top system in the benchmark in the field of glass coating composites for energy-saving applications.

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.

Advanced Materials Technologies 8(3), 2200922 (2022). doi:10.1002/admt.202200922, Published by Wiley, Weinheim

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.

In this paper the findings from a long-term field study of the thermal performance of a circa 1950s dwelling are presented and discussed. The study aimed at evaluating the robustness of the QUB method in the field under UK climatic conditions. A series of 147 QUB tests were performed during the whole heating period (September 2016 – March 2017) in a detached house located in the University Park campus, University of Nottingham considering two distinct conditions: as-built and with increased airtightness. The QUB method was able to provide consistent and robust estimates of the Heat Transfer Coefficient (HTC) of the whole dwelling with approximately 80% of the results within ± 10% from the mean and more than 95% of the results within ± 15%. The need to treat heat losses occurring through the ground when assessing the thermal performance of buildings through experimental diagnostics methods was highlighted, especially in uninsulated concrete slab floors. The method devised to isolate the ground floor heat losses from the whole building losses resulted in reduced dispersion of the adjusted Heat Transfer Coefficient with a coefficient of variation of 5% and 98% of results within ± 10% from the mean.

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

1D Total Variation (TV) denoising, considering the data fidelity and the Total Variation (TV) regularization, proposes a good restored signal preserving shape edges. The main issue is how to choose the weight $\lambda$ balancing those two terms. In practice, this parameter is selected by assessing a list of candidates (e.g. cross validation), which is inappropriate for the real time application. In this work, we revisit 1D Total Variation restoration algorithm proposed by Tibshirani and Taylor. A heuristic method is integrated for estimating a good choice of $\lambda$ based on the extremums number of restored signal. We propose an offline version of restoration algorithm in O(n log n) as well as its online implementation in O(n). Combining the rapid algorithm and the automatic choice of $\lambda$, we propose a real-time automatic denoising algorithm, providing a large application fields. The simulations show that our proposition of $\lambda$ has a similar performance as the states of the art.

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; The impact of polypropylene and high-density polyethylene backbone binders on the structure of organic matrix, feedstock, and ceramic parts is investigated in terms of morphology in this paper. The miscibility of wax with polyethylene and polypropylene is investigated in the molten state via a rheological study, revealing wax full miscibility with high-density polyethylene and restricted miscibility with polypropylene. Mercury porosimetry measurements realized after wax extraction allow the characterization of wax dispersion in both neat organic blends and zirconia filled feedstocks. Miscibility differences in the molten state highly impact wax dispersion in backbone polymers after cooling: wax is preferentially located in polyethylene phase, while it is easily segregated from polypropylene phase, leading to the creation of large cracks during solvent debinding. The use of a polyethylene/polypropylene ratio higher than 70/30 hinders wax segregation and favors its homogeneous dispersion in organic binder. As zirconia is added to organic blends containing polyethylene, polypropylene, and wax, the pore size distribution created by wax extraction is shifted towards smaller pores. Above zirconia percolation at 40 vol%, the pore size distribution becomes sharp attesting of wax homogeneous dispersion. As the PP content in the organic binder decreases from 100% to 0%, the pore size distribution is reduced of 30%, leading to higher densification ability. In order to ensure a maximal densification of the final ceramic, polyethylene/polypropylene ratios with a minimum content of 70% of high-density polyethylene should be employed.

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; In this paper, the findings from a field study of the thermal performance of a low-energy dwelling are presented and discussed. The study aimed at evaluating the precision and accuracy of the QUB/e method in the field under UK climatic conditions. A series of in situ measurements were carried out in a low-energy detached house located in the University Park campus, University of Nottingham to determine both the whole building Heat Transfer Coefficient (HTC) and the thermal transmittances (U-values) of the external walls and the glazings. The values determined with wellestablished quasi-static measurement methods (coheating test, ISO 9869-1 average method) were used as reference (benchmark) values to assess the accuracy of the QUB/e method. In total 18 consecutive QUB/e tests were conducted. The QUB/e method was able to provide precise and accurate estimates of the whole building HTC: 94% of the results (i.e. 17 out of 18) were found to be within ± 15% from the mean and 78% of the HTC estimates (i.e., 14 out of 18) obtained with a QUB/e test could not be considered statistically different from the HTC determined with the coheating test (benchmark). It should be noted that the reported confidence intervals associated with the HTC estimates obtained with the QUB/e tests were slightly larger than the one reported for the coheating test (i.e., 11.6% in average and 6.1%, respectively). The Mean Bias Error (MBE) and the Root Mean Square Error (RMSE) associated with the HTC estimates obtained with the QUB/e tests were approximately 11%. The QUB/e method was also able to provide precise and accurate estimates of the thermal transmittances of the external walls and the glazings. We observed that all but seven (i.e., 119 out of 126 or 94%) U-values estimates of the external walls obtained with a QUB/e test could not be considered statistically different from the U-values determined with the ISO 9869-1 average method (benchmark). With regard to the glazings, this was observed for all U-values estimates (i.e., 162 out of 162 or 100%). It should be noted that the reported confidence intervals associated with the U-value estimates obtained with both test methods were close (i.e., approximately 10% in average) for all elements except for the ICF wall.

International audience; Lightweight plasterboard is a product composed of plaster foam core whose porosity can reach 75 vol%, lined with two sheets of paper. To optimize the trade-o between thermal resistance and mechanical strength, it is important to understand and characterize the mechanical behavior of plasterboard. Core compaction of plasterboard is one of the prevalent degradation mechanism. This mechanism is studied herein using in-situ indentation experiments performed at two dierent scales. The rst test was carried out in a lab tomograph. The second test was conducted on the high resolution synchrotron ID19 beamline at ESRF. Very early damage is revealed. The basic mechanism of pore collapse and its gradual development is detected in contrast with mesoscale observations where compaction appears very abrupt.

International audience; We use multiscale modelings to investigate the heat dissipation in 2D transistors based on phosphorene and silicene. First, molecular dynamics (MD) simulations were used to calculate the thermal interface resistance R int between the 2D materials (phosphorene and silicene) and dielectrics substrates (SiO 2 and TiO 2). The calculated R int of these systems are close to that between graphene and SiO 2 and are insensitive to the temperature. The MD values then served as inputs for finite-element simulations at the device scale. It is found that the heat-dissipation ability of the 2D transistors can be improved by increasing the thermal conductivities of the 2D materials as well as of the substrate. However, in contrast to the common belief, it is difficult to largely reduce the hot-spot temperature by tuning the interface thermal resistance. Finally, we show that the cooling performance of silicene/SiO 2 system can be significantly improved with a few-layer graphene heat spreader. These results provide important information for the novel design of 2D transistors in terms of thermal management.

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.

Drinking water pipes can be lined with a cement matrix based on CEM III, which can release aluminium into the water. However, the European Union limits the aluminium concentration in drinking water for public health reasons. In order to study the long-term leaching mechanism of aluminium, semi-dynamic leaching tests using an aggressive solution (demineralised water) or drinking water (mineralised water) were conducted on crushed CEM III pastes maintained at pH 7. They resulted in a very high leaching coefficient, approaching 50%. However, in spite of this strong leaching, the amount of Al leached remained very low, at less than 1.5% of the initial amount of Al in the material. Under these conditions, the leaching of Al from a CEM III paste is complex since it involves several steps, where slag (1st and last steps) or cement paste (2nd step) are the main contributors.

International audience; To design lightweight plasterboard and optimize the compromise between thermal resistance and mechanical strength, it is important to characterize its strength as characterized with the normative Nail pull test. Understanding the phenomenology of this test is the key to identifying the limiting factor in terms of load carrying capacity. In this work, the degradation mechanisms of lightweight plasterboard are analyzed via tests conducted in-situ in a laboratory tomograph. Through the analysis of the kinematics by digital volume correlation, the dierent mechanisms at play up to failure mechanism have been identied, i.e., quasi-elastic regime, failure of the roller coating layer, core compaction and core failure. The compaction of the core by the collapse of porosity in compression is recognized as the limiting factor in terms of compressive strength and tearing resistance.

Lignosulfonates (LS) are water-soluble polyphenolic macromolecules derived from lignins and common industrial additives in plasticizers and dispersants. A key feature for a more efficient utilization of modified LS is the monitoring of their free phenol (OHphen) content during various reactions as these phenols govern a large part of their chemical reactivity. Against this background, the UV difference spectroscopy (Δεi method) and ClO2 titration have been revisited. Synthetic LS model compounds with a SO3H group on their benzylic position and H, G, and S aromatic rings were synthesized and used to assess the suitability of both the ClO2 titration and the Δεi method on LS. The methodology combining the two analytical methods was then used to determine the molar extinction coefficient of a given LS allowing the calibration of the Δεi method for a convenient and rapid monitoring of OHphen in the course of LS reactions involving the OHphen groups.

Hydrogel coatings absorb water vapor - or other solvents - and, as such, are good candidates for antifog applications. In the present study, the transfer of vapor from the atmosphere to hydrogel thin films is measured in a situation where water vapor flows alongside the coating which is set to a temperature lower that the ambient temperature. The effect of the physico-chemistry of the hydrogel film on the swelling kinetics is particularly investigated. By using model thin films of surface-grafted polymer networks with controlled thickness, varied crosslinks density, and varied affinity for water, we were able to determine the effect of the film hygroscopy on the dynamics of swelling of the film. These experimental results are accounted for by a diffusion-advection model that is supplemented with a boundary condition at the hydrogel surface: we show that the latter can be determined from the equilibrium sorption isotherms of the polymer films. Altogether, this paper offers a predictive tool for the swelling kinetics of any hydrophilic hydrogel thin films.