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International audience; Near-surface axial tensile residual stresses (from manufacturing) are reportedly detrimental to the yield strength of cold-drawn wires. Therefore, a reliable evaluation of their magnitude is necessary. The size and geometry of electrical wires can pose challenges for experimental measurement of those residual stresses. For that reason, the finite element analysis can prove useful. However, great care must be taken with the right choice of strain hardening law for a sound assessment of residual stresses. Given the complex loading condition during cold drawing, cyclic loading arises through the wire cross section even in single-pass drawing. As a result, it is of crucial importance to account for associated backstresses. The current study makes a comparison between two different hardening laws’ prediction of axial residual stress profiles in numerically cold-drawn Cu–Al composite wires of various Al volume fractions. The impact of die geometry on this prediction was also examined for a 25%Al-wire. To that end, a combined isotropic-kinematic law and a pure isotropic constitutive equation were considered. The results imply a possible overestimation of residual stresses by the pure isotropic model at relatively low Al volume fractions. The difference between the maximum magnitudes of tensile or compressive residual stresses (predicted by the two models) could be as large as about 100 MPa (larger than the yield strength of the starting materials). Furthermore, the tooling geometry minimally affects the prediction of the hardening models. In conclusion, backstresses are not to be overlooked for accurate estimations of drawing residual stresses at low Al volume fractions.

Near-surface axial tensile residual stresses (from manufacturing) are reportedly detrimental to the yield strength of cold-drawn wires. Therefore, a reliable evaluation of their magnitude is necessary. The size and geometry of electrical wires can pose challenges for experimental measurement of those residual stresses. For that reason, the finite element analysis can prove useful. However, great care must be taken with the right choice of strain hardening law for a sound assessment of residual stresses. Given the complex loading condition during cold drawing, cyclic loading arises through the wire cross section even in single-pass drawing. As a result, it is of crucial importance to account for associated backstresses. The current study makes a comparison between two different hardening laws’ prediction of axial residual stress profiles in numerically cold-drawn Cu-Al composite wires of various Al volume fractions. The impact of die geometry on this prediction was also examined for a 25%Al-wire. To that end, a combined isotropic-kinematic law and a pure isotropic constitutive equation were considered. The results imply a possible overestimation of residual stresses by the pure isotropic model at relatively low Al volume fractions. The difference between the maximum magnitudes of tensile or compressive residual stresses (predicted by the two models) could be as large as about 100 MPa (larger than the yield strength of the starting materials). Furthermore, the tooling geometry minimally affects the prediction of the hardening models. In conclusion, backstresses are not to be overlooked for accurate estimations of drawing residual stresses at low Al volume fractions.

This work is devoted to investigate the structural and electrical properties of the Ce, Gd-doped YBCO superconductors bulk ceramics. YBa2-xRExCu3O7−δ (x = 0, 0.01, 0.05, 0.1) (RE = Gd, Ce) samples were prepared by means of conventional solid-state reaction. X-ray diffraction analysis was carried out to identify the present phases in the as-prepared samples followed by the determination of their lattice parameters. Fourier Transform Infrared Spectroscopy (FTIR) was used to identify the functional groups. Furthermore, the morphology and the surface roughness of the studied samples were characterized using Scanning Electronic Microscopy (SEM) and Atomic Force Microscopy (AFM). Vickers Micro-hardness of the as-prepared samples was examined. Besides, the electrical resistivity measurements were achieved to determine the critical transition temperature TC and the critical current density JC. The effect of Ce and Gd additions is clearly noticed in the obtained results, where all the prepared samples are superconductors with the presence of Y123 as a major polycrystalline phase. From the XRD patterns, the intensities of the Y123 corresponding peaks decrease with further increasing the Ce and Gd contents. In addition, the variation of the cell parameters was significant after additions of both Ce and Gd, which affect the grain size and the oxygen content of the YBa2-xRExCu3O7−δ system. An improvement of the structure and surface roughness is observed on SEM and AFM images. Likewise, Vickers micro-hardness has increased after the Ce and Gd additions. Although, the critical transition temperature TC was not further increased upon Ce or Gd additions compared to the undoped YBCO samples. Nevertheless, an exception has been recorded with an increase of TC for YBa2-xRExCu3O7−δ with (RE = Gd, x=0.01) to reach 88 K. In contrary, an improvement of the deduced critical current density JC was achieved for all Ce-doped YBCO samples unlike those of Gd-doped samples.

International audience; The present study investigates the tensile behavior of the two bimetallic composite wires Cu-Al and Fe-Al. The purpose is to understand the deviation their tensile strengths show from the Rule of Mixtures’ prediction. To that end, an experimental-numerical approach was adopted. Following tensile testing of the above cold-drawn composite wires, the manufacturing process (wire drawing) was simulated via finite element analysis. The prominent role of processing-induced residual stresses on the yield strength of cold-drawn products is known. Therefore, a discussion based on the axial tensile residual stress profile was developed. It was concluded that the higher-magnitude-near-surface tensile residual stresses in the Fe-Al wire causes its tensile curve to show a negative deviation from the Rule of Mixtures (RoM). The Cu-Al wire, on the contrary, exhibits a slight positive deviation.

International audience

Learning biology, and in particular systematics, requires learning a substantial amount of specific vocabulary, both for botanical and zoological studies. While crucial, the precise identification of structures serving as evolutionary traits and systematic criteria is not per se a highly motivating task for students. Teaching this in a traditional teaching setting is quite challenging especially with a large crowd of students to be kept engaged. This is even more difficult if, as during the COVID‐19 crisis, students are not allowed to access laboratories for hands‐on observation on fresh specimens and sometimes restricted to short‐range movements outside their home. Here, we present QuoVidi, a new open‐source web platform for the organization of large‐scale treasure hunts. The platform works as follows: students, organized in teams, receive a list of quests that contain morphologic, ecologic, or systematic terms. They have to first understand the meaning of the quests, then go and find them in the environment. Once they find the organism corresponding to a quest, they upload a geotagged picture of their finding and submit this on the platform. The correctness of each submission is evaluated by the staff. During the COVID‐19 lockdown, previously validated pictures were also submitted for evaluation to students that were locked in low‐biodiversity areas. From a research perspective, the system enables the creation of large image databases by the students, similar to citizen science projects. Beside the enhanced motivation of students to learn the vocabulary and perform observations on self‐found specimens, this system allows instructors to remotely follow and assess the work performed by large numbers of students. The interface is freely available, open‐source and customizable. Unlike existing naturalist platforms, allows the educators to fully customize the quests of interest. This enables the creation of multiple teaching scenarios, without being bound to a fixed scope. QuoVidi can be used in other disciplines with adapted quests and we expect it to be of interest in many classroom settings., QuoVidi is a decentralized web platform to organize large scale biological treasure hunts. It was created to teach students specific biological terms and observe them in their direct environments.

This prospective cohort study investigated the distribution pattern of carious lesions diagnosed by visual tactile and radiographic examinations, assessed the radiographic yield for clinical caries diagnosis, and estimated how accurately commonly used indicators for caries identified young adults who would benefit from radiographs at different thresholds. Overall, 576 patients aged 16–32 years seeking a first consultation were included. Patients were examined for caries and answered a validated questionnaire on sociodemographics and oral health behavior. Almost 10% of clinically sound approximal surfaces presented radiolucency in enamel/dentine. Of the clinically diagnosed noncavitated approximal and occlusal lesions, 22.5 and 17.7%, respectively, presented radiolucency reaching dentine at the radiographic examination. Noncavitated/enamel lesions detected radiographically were mainly at approximal surfaces (73.2%), while at occlusal surfaces these were negligible (0.7%). More than half of approximal dentine lesions were only detected radiographically (61.3%), while more than half of occlusal dentine lesions were only clinically diagnosed (57.1%). The hierarchical logistic regression analysis showed that patient’s caries activity, D1MFS scores ≥17, and frequent consumption of soft drinks were significantly associated with detection of approximal enamel/dentine lesions. Also, patient’s caries activity and frequent consumption of soft drinks were significantly associated with occlusal dentine caries (p ≤ 0.05). The indicator power of grouping these indicators as a predictor for the presence of radiographically detected lesions showed high sensitivity (0.84–0.91) and moderate specificity (0.64–0.73) for all surfaces and thresholds tested. In conclusion, radiographs increased significantly the number of approximal enamel/dentine and occlusal dentine lesions diagnosed. The ability to identify young adults with approximal lesions from the predictor was satisfactory. Bearing in mind that an essential contribution of bitewing radiographs to clinical examination is the detection of approximal noncavitated/enamel lesions that can be inactivated by nonoperative interventions, our results support the prescription of radiographs in young adults seeking a first consultation. Updating of current guidelines’ recommendation of radiographs is warranted.

Architectured copper clad aluminium composites processed by a restacking drawing method at room temperature are reported in this work. Wires were drawn to severe plastic strain without any intermediate annealing. Three different diameters were studied in order to examine the influence of a different plastic deformation level on the structure of the different wires. Thanks to image processing it has been shown that independently of the plastic deformation, inserted fibers remain continuous and are homogeneous in size and shape. Furthermore, XRD and TEM characterizations confirm that there is no significant intermetallic growth during the deformation. Thus, the improvement and/or degradation of the functional properties of the wires can be well controlled by performing an appropriate post-processing annealing treatment. Keywords: Cu/Al composite, architectured wire, drawing, microscopy, image processing

Learning biology, and in particular systematics, requires learning a substantial amount of specific vocabulary, both for botanical and zoological studies. While crucial, the precise identification of structures serving as evolutionary traits and systematic criteria is not per se a highly motivating task for students. Teaching this in a traditional teaching setting is quite challenging especially with a large crowd of students to be kept engaged. This is even more difficult if, as during the COVID-19 crisis, students are not allowed to access laboratories for hands-on observation on fresh specimens and sometimes restricted to short-range movements outside their home.Here we present QuoVidi, a new open-source web platform for the organisation of large scale treasure hunts. The platform works as follows: students, organised in teams, receive a list of quests that contain morphologic, ecologic or systematic terms. They have to first understand the meaning of the quests, then go and find them in the environment. Once they find the organism corresponding to a quest, they upload a geotagged picture of their finding and submit this on the platform. The correctness of each submission is evaluated by the staff. During the COVID-19 lockdown, previously validated pictures were also submitted for evaluation to students that were locked in low-biodiversity areas. From a research perspective, the system enables the creation of large image databases by the students, similar to citizen-science projects.Beside the enhanced motivation of students to learn the vocabulary and perform observations on self-found specimens, this system allows faculties to remotely follow and assess the work performed by large numbers of students. The interface is freely available, open-source and customizable. It can be used in other disciplines with adapted quests and we expect it to be of interest in many classroom settings.

The thermal behavior of Phase Change Materials (PCMs) is a major issue for cooling, heat storage and thermal management of various systems in general. Unfortunately many PCMs present supercooling which is a major drawback regarding the efficiency of cooling systems. Various solutions were proposed to model the thermal kinetics, in particular using the apparent specific heat Cp(T) technique. But among them only few consider the supercooling effect. The present work considers this issue by focusing on the representation of the different steps of the supercooling phenomenon. This leads to different formulations of the apparent capacity Cp (T,fsuper). The presented algorithm uses the lumped system analysis approach that is widely spread for first-order and multi-scale resolutions. The apparent capacity laws are explicitly presented for the different melting-crystallization steps. In particular, the punctually negative Cp formulation, a helpful mathematical artifact, permits to reproduce the thermal dynamics during the local crystallization. The formulations and the models are discussed. Eventually, the temperature evolutions of an experimental system are compared to calculated data and the crystallization rate is compared to the literature.

International audience; This work focusses on the link between microstructure and creep properties for heat-resistant austenitic alloys with high aluminum content (3-5 wt %). An emphasis was put on the coupling of thermodynamic simulations, microstructural characterizations by scanning electron microscopy and transmission electron microscopy, and creep testing. The phase predictions performed by the calculation of phase diagrams method are in good agreement with the observed microstructure after creep at 1000 � C and 1050 � C. Correlation between creep properties and microstructure characterizations at 1000 � C and 1050 � C revealed that NiAl and α' (chromium-rich base centered cubic phase) phases are deleterious for the creep properties at service temperature. Several high Al-content alloys are selected in order to replace the chromia-forming alloys standardly used in cracking furnaces.

Architectured wires containing 61 restacked Copper Clad Aluminum (CCA) wires were cold-drawn down to a diameter of 1 mm without intermediate annealing. Samples were taken at intermediate diameters of 3 mm and 1.7 mm to observe the wire structure at different steps. Independently of the wire diameter, the structure did not exhibit any porosity and initial CCA wires were uniformly distributed inside the structure with constant equivalent diameters. Post-elaboration annealing treatments performed on CCA and architectured wires led to the formation of Al2Cu, AlCu and Al4Cu9 intermetallic compounds (IMC). It was shown that IMC growth kinetics do not depend on the wire diameter, indicating no marked influence of the plastic deformation. The volume fraction of IMC strongly increased with the reduction of the diameter and impacted the electrical resistivity of the architectured wire. The equivalent resistivity has been easily computed by a linear rule of mixture model, with three electrical resistances in parallel (Al, Cu and IMC), weighted by their respective volume fraction. This model allowed extracting a mean resistivity of IMCs of 4.5 μΩ·cm. It also demonstrated that this restacking drawing process, without any intermediate annealing treatment is an interesting method for the elaboration of architectured wires with optimized functional properties. Keywords: Bimetallic composite, Architectured wire, Drawing, Intermetallic compound, Electrical resistivity

Background: Paediatric complex chronic conditions (CCCs) are life-limiting conditions requiring paediatric palliative care, which, in Belgium, is provided through paediatric liaison teams (PLTs). Like the number of children and adolescents with these conditions in Belgium, their referral to PLTs is unknown. Objectives: The aim of the study was to identify, over a 5-year period (2010-2014), the number of children and adolescents (0-19 years) living with a CCC, and also their referral to PLTs. Methods: International Classification of Disease codes (ICD-9) corresponding to a CCC, as described by Feudtner et al, and national registration numbers were extracted from the databases of all hospitals (n=8) and PLTs (n=2) based in the Brussels region. Aggregated data and pseudonymised national registration number were transmitted to the research team by a Trusted Third Party (eHealth). Ages and diagnostic categories were calculated using descriptive statistics. Results: Over 5 years (2010-2014) in the Brussels region, a total of 22 721 children/adolescents aged 0-19 years were diagnosed with a CCC. Of this number, 22 533 were identified through hospital registries and 572 through PLT registries. By comparing the registries, we found that of the 22 533 children/adolescents admitted to hospital, only 384 (1.7%) were also referred to a PLT. Conclusion: In Belgium, there may be too few referrals of children and adolescents with CCC to PLTs that ensure continuity of care., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; The present study investigates the mechanical behavior of severely plastic-deformed Cu-Al composite wires with different diameters and heat-treatments. Each composite holds 61 restacked copper-clad aluminum wires. The bimetal composites were cold-worked up to diameters ranging from 1 mm to 3 mm, without any intermediate heat treatment. All the wires contain 61 hexagonal Cu-Al fibers with a continuous copper network extended from the outer surface into the center of the samples. Tensile tests were then performed on the as-drawn and heat treated wires. The latter were treated at 400 • C for 30 min and 6h. The heat treatments firstly induce recrystallization in both constituents, giving rise to a fine-grained microstructure and secondly prompt the formation of several intermetallics. Without heat treatment after processing, the architectured composites exhibit a ductility value similar to the conventional copper-clad aluminum wires and larger yield stresses compared to them, regardless of the diameter. The intermetallic compounds, forming as a result of heat treatment, affect the yield stress, ductility and strain hardening mechanisms. Finally, the results are discussed in terms of grain size, texture, intermetallics volume fraction and mechanical coupling between the phases.

This paper presents an original contribution for the establishment of the high-cycle fatigue curves ε–Nf (strain versus cycle number to failure) of low carbon steel under vibratory testing. These curves are obtained thanks to a vibrational fatigue bench composed of an electrodynamic shaker and a closed loop vibration control system. The main advantage of this is the high frequency excitation compared to conventional fatigue systems. Three criteria based on strain gauge measurements are implemented to provide cycle numbers to failure Nf and to plot the fatigue curves. Furthermore, cycle numbers to failure are also assessed from two modal parameters (resonant frequency and loss damping factor) and compared with the results obtained from these three criteria. Some micrographies of fractured samples observed by scanning electron microscope reveal fatigue striations but also intergranular fracture. Keywords: High cycle vibratory fatigue, Electrodynamic shaker ε–Nf curves, Real-time closed loop adaptive control, Failure criterion, Trans- and inter-granular fractures

International audience; In the particular case of finite orders, we investigate the notion of faithful extension among relations introduced in 1971 by R. Fraısse: an orderQ admits a faithful extension relative to an order P if P does not embed into Q and there exists a strict extension of Q into which P still does not embed. For most of the known order classes, we prove that if P and Q belong to a class then Q admits a faithful extension in this class. For theclass of distributive lattices, we give an infinite family of orders P and Q such that P does not embed into Q and embeds in every strict extension ofQ.

Very long aging times, up to 15,100 h (629 days) at 110°C, were achieved on flame-retardant printed circuit board laminates commonly used in automotive design. This composite was fabricated from glass fibers embedded in an epoxy resin. Aging was performed in an oven under an air atmosphere at a temperature lower than the glass-transition temperature. Temperature-modulated differential scanning calorimetric analysis was used to investigate the influence of such aging on the glass-transition phenomena. A new amorphous phase appeared during aging. By extending the analysis to samples collected at different thicknesses, we demonstrated the existence of a time-dependent gradient of the properties. A skin–core structure was evidenced, and this slowed down oxidation and allowed physical aging to occur in the bulk sample. An exponential law described the variations of the glass-transition of the new external compound. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 786-792, 2013

Hybridization of polyoxometalates (POMs) via the formation of an organic-inorganic association constitutes a new route to develop a heterogeneous POM catalyst with tunable functionality imparted through supramolecular assembly. Herein, we report on strategies to obtain tunable well-defined supramolecular architectures of an organic-inorganic heterogeneous hybrid catalyst formed by the association of a hydrophobically substituted polyampholyte copolymer (poly N, N-diallyl-N-hexylamine-alt-maleic acid) and phosphotungstic acid (H3PW12O40) POMs. The self-assembling property of the initial polyampholyte copolymer matrix is modulated by controlling the pH of the hybridization solution. When deposited on a mica surface, isolated, long and extended polymer chains are formed under basic conditions (pH 7.9), while globular or coiled structures are formed under acidic conditions (pH 2). The supramolecular assembly of the POM-polymer hybrid is found to be directed by the type and quantities of charges present on the polyampholyte copolymer, which themselves depend on the pH conditions. The hypothesis is that the Keggin type [PW12O40](3-) anions, which have a size of ~1 nm, electrostatically bind to the positive charge sites of the polymer backbone. The hybrid material stabilized at pH 5.3 consists of POM-decorated polymer chains. Statistical analysis of distances between pairs of POM entities show narrow density distributions, suggesting that POM entities are attached to the polymer chains with a high level of order. Conversely, under acidic conditions (pH 2), the hybrid shows the formation of a core-shell type of structure. The strategies reported here, to tune the supramolecular assembly of organic-inorganic hybrid materials, are highly valuable for the design and a more rational utilization of POM heterogeneous catalysts in several chemical transformations.

The main characteristics of quasi-isothermal diffusive transformation from austenite to pearlite in a 100C6 steel have been determined from experimental tests. The parameters of constitutive laws and kinetics of phase transformation of different micromechanical models of phase transformation could then be identified. The models are classified according to the prevailing assumptions: mean- or full-field approach, regular or heterogeneous microstructural morphology, macro-homogeneous constitutive laws or crystal plasticity. A comparative analysis in terms of transformation-induced plasticity (TRIP) is performed in order to conclude on the relevance of the different models as regards experiments and to show how the principal assumptions of TRIP modelling can affect the predictions.

In this work, the process of co-drawing followed by bundling and restacking was used to fabricate composite wires with a metallic copper matrix and High Density Polyethylene (HDPE) polymer fibres. After processing, copper matrix composite wires with 3770 polymer domains of approximately 20 μm in diameter were obtained. Differential Scanning Calorimetry analysis, optical microscopy and microhardness measurements were performed on the polymer and the copper components of the composites. The volume fraction and the degree of crystallinity of the polymer remain constant during the drawing. This procedure leads to a lamellar reorganization and fragmentation of the crystalline HDPE phase.

Cold drawing of bimetallic wires is an efficient technology for fabrication of filamentary composite materials. In the present paper an analytical approach to the plastic flow of a two-component mono-filamentary wire through a converging conical die is proposed. Developed solution is based on a number of simplified assumptions concerning the radial flow pattern, the perfectly plastic materials’ behavior, and the perfect bonding conditions between the components. The stress and the strain-rate fields are determined. Obtained results for the drawing stress show a good agreement with available experimental data. Examination of the interfacial stresses localized at the boundary between the components allows to identify the range of the input parameters in which the pure radial flow can exist.

Psychiatric commitment laws have been reformed in many European countries. We assessed the relative importance of the different legal criteria in explaining involuntary commitment under the Belgian Mental Health Act of 1990. Psychiatric assessments were requested for 346 patients living in Brussels who were randomly selected from a larger group and were being considered for involuntary commitment. A retrospective study of these patients’ files was carried out. More than half of the requests for involuntary commitment were turned down. The lack of a less restrictive alternative form of care was the criterion most crucial in decisions in favour of commitment. Alternative forms of care were more likely to be unavailable for psychotic individuals, foreigners, and patients not living in a private household. Involuntary commitment is mainly due to the inability of the mental health care system to provide more demanding patients with alternative forms of care.

Copper–graphite composites are used and under investigations for various applications. The reported manufacturing methods are diverse, but no process is available to fabricate a multifilamentary copper–graphite wire with a large number of graphite filaments. A new processing route is described which allows the fabrication of such composite with more than 30 millions of graphite filaments in a 5.2 mm diameter copper wire. The resulting microstructures and electrical properties are presented and discussed.

Also published as FR3018383; A device for determining navigation parameters of an aircraft during a landing phase includes a video system including at least one digital video camera arranged on the aircraft, the digital video camera being configured to generate on the aircraft current video data relating to at least one characteristic point on the Earth, whose coordinates are known, and a data processing unit including an extended Kalman filter and configured to determine the navigation parameters on the basis of current navigation data of the aircraft, arising from a satellite navigation system, current inertial data of the aircraft, as well as said video data.; Le dispositif (1) comporte un système vidéo (10) comprenant au moins une caméra vidéo numérique (11) agencée sur l'aéronef, la caméra vidéo numérique (11) étant configurée pour générer sur l'aéronef des données vidéo courantes relatives à au moins un point caractéristique sur la Terre, dont les coordonnées sont connues, et une unité de traitement de données (6) comprenant un filtre de Kalman étendu (7) et configurée pour déterminer les paramètres de navigation à partir de données de navigation courantes de l'aéronef, issues d'un système de navigation par satellites, de données inertielles courantes de l'aéronef, ainsi que desdites données vidéo.

Copper-carbon composites (where carbon can be graphite, carbon-fibers, fullerenes and carbon nanotubes) are used and under investigations for various applications. The reported manufacturing methods are diverse, but, to our best knowledge, no process is available to fabricate a multifilamentary Copper-Graphite wire with a large number of graphite filaments. We describe a new processing route, which allows the fabrication of such composite by severe plastic deformation. The resulting microstructures and electrical properties are presented and discussed.

We propose an asymptotic approach for evaluating effective properties and determining the micro-mechanical response of filamentary composite wires fabricated by cold drawing under longitudinal shear (torsion). Our procedure is based on the homogenization method; a cell problem is solved using the underlying principles of the boundary shape perturbation technique. As the results we derive approximate analytical solutions for the effective shear modulus and for local distributions of the stress field. Developed approach is valid for all values of the components' volume fractions and properties, in particular, it works well in cases when rapid oscillations of stresses occur on micro level (e.g., in the case of perfectly rigid nearly touching inclusions). Analysis of the local stresses allows to predict the effective initial yield limit corresponding to the beginning of plastification of the composite medium. Obtained results are in good agreement with data of other authors.

Machined surfaces of two steels (0.38 and 0.8 wt.% C) were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Mossbauer spectrometry. Because of the shear and tool wear during the chip formation, a white etching layer appears on these surfaces. X-ray diffraction and Mossbauer spectrometry data show the presence of retained austenite and suggest the presence of martensite in the white etching layer. The formation of these phases is discussed and from crystallographic data, the temperature reached during turning is estimated.

International audience; The quick development of air traffic has led to the improvement of approach and landing operations by using flexible flight paths and decreasing the minima required to perform these operations. Most of the operations are currently supported by the Global Navigation Satellite System (GNSS) potentially augmented with Ground Based Augmentation System (GBAS), Satellite Based Augmentation Systems (SBAS) and Aircraft Based Augmentation System (ABAS). SBAS and GBAS allow supporting navigation operations down to Approaches with Vertical guidance (APV) and to Precision Approaches (PA) respectively. However, these augmentations do require an expensive network of reference receivers and real-time broadcasts to the airborne user [GEAS, 2008]. In order to overcome these limitations, the ABAS system integrates on-board information that can for example be provided by Inertial Navigation System (INS) so as to enhance the performance of the navigation system. In this scheme, the INS is coupled on board with GPS through a GPS/INS hybridization solution that is already performed on current commercial aircraft. This solution allows reaching better performance in terms of accuracy, integrity, availability and continuity than the two separated solutions. The basic principle of this hybridization technique is that the GPS solution can be used to estimate the inertial drift. Thus, the hybridization compensates GPS and INS drawbacks (unavailability for GPS and drifting errors for INS), allowing navigation in oceanic en-route operations down to non-precision approaches for long range aircraft. The hybridized solution also allows coasting when GPS is unavailable for a limited period of time and can improve integrity monitoring of GPS data. Moreover, on some commercial aircraft, the Air Data Inertial Reference Unit (ADIRU) provides air parameters such as Barometric Altitude and Vertical Speed, in addition to inertial parameters. In this case, the hybridization architecture can integrate the barometric altitude and estimate the vertical position and the vertical velocity. However the most stringent requirements for precision approaches or automatic landings cannot be reached with the current GPS/INS hybridization schemes. The main idea in the framework of my PhD study is then to extend the hybridization filter by including other sensors or other information sources available on commercial aircraft and to assess the performance reached by this global hybridization architecture. The objective of the work is to propose a system that will be able to fuse the multiple sources of information or measurement in a global architecture. Thus, it aims at providing most of the navigation parameters (3D position, 3D velocity, attitude and heading) in all conditions and operations with the required level of performance in terms of accuracy, integrity, availability and continuity. The integration of multiple sources of on-board measurements allows improving the performances of the navigation solution by gathering all the advantages of each source. The operations targeted by this hybridization are the ones requiring very stringent performances, as precision approaches, with a particular focus on CAT III precision approach and roll out on the runway. The study of the possible sensors/systems and associated information/measurements available on board a commercial aircraft has been investigated in previous works, and a set of sensors and data to consider has been identified: a GPS (potentially augmented with GBAS), an INS (different classes of inertial sensors will be considered), tachometers (during take-off and landing operations) and a video system. The aim of my work is to arrive to the definition of a global hybridization filter architecture based on the integration of multiple information/measurement sources or sensors (INS, GNSS receiver, tachometers and a video system), depending on the operational environment: the aircraft operation considered, the sensors available during the considered operation, the performance requirement for supporting the considered operation.

In this work we address the long standing problem of the non hookean elastic behavior of iron whiskers. It can be explained by taking into account the experimental errors not included in the original work. Furthermore, we demonstrate that the tensile curve is not linear if it is established from engineering stress and engineering strain.

The study aimed at identifying oral health determinants that are present in early childhood, are amenable to change and for which there is evidence of their modulation of the rate of caries progression in a sample of non-privileged children. The null hypothesis was that determinants associated with the child's institutional environment as evidenced by nursery policies significantly influenced the child's oral health. The sample was formed by 2,511 Brazilian 1-5-year-olds. Caries severity and activity were recorded. Parents were interviewed and nurseries answered a questionnaire. According to the case status d1efs, the final multilevel model (generalized linear mixed model) identified significant associations with determinants such as bottle-feeding the child during the night on demand, not assisting the child in toothbrushing, ensuring visit to the dentist in case of troubles with teeth only (p < 0.0001) and intake of sugary products 2-4 times daily at nursery (p = 0.026). The likelihood of caries outcomes was associated with determinants related to nursery policies, not promoting preventive oral health care for children of mothers with 4 years of education (OR = 2.14; p < 0.0015) and

International audience; Two kinds of Cu/Nb nanocomposite wires were investigated using field ion microscopy (FIM) and 3D atom probe. These two techniques revealed for the first time the nanoscale microstructure of nanocomposite wire cross sections. FIM investigations confirmed the Cu and Nb texture and the disorientation between (111) Cu and (110) Nb planes. Low angle Nb/Nb grain boundaries were also observed. Thanks to 3D atom probe, parts of niobium fibres and copper channels a few nanometer width were mapped out in 3D. Smooth Cu/Nb interfaces were attributed to stress-induced diffusion. Shear bands, observed perpendicular to the wire axis, were attributed to tracks of moving dislocations in a copper channel.

International audience; Global Navigation Satellite Systems (GNSS) and Inertial Navigation Systems (INS) are currently the main navigation systems for aircraft. INS navigation is based on dead-reckoning principle so small errors in the measurements of vehicle accelerations and rotation rates can cause non-negligible integration drift. As an alternative navigation mean, more and more considered in navigation applications, image-aided inertial navigation is a complete autonomous navigation opportunity because it is only based on sensors onboard that provide information from the dynamic of the vehicle and the observation of the scenery. This system of navigation might be used in the particular case of loss of other systems of navigation that need additional exterior equipment (Global Navigation Satellite System (GNSS) or Instrument Landing System (ILS) for example). Besides in the particular context of civil aviation, during precision approaches (currently done with ILS or GPS augmented with GBAS or SBAS), it could be interesting to use an additional autonomous mean of navigation like video measurement that could overtake the need of additional ground or space infrastructure. But the performance has to be analyzed so as to determine if such a system can satisfy the precision approaches requirements which are very stringent. Development of techniques of navigation with imaging sensors does not mean a complete replacement of the currently widely used hybridization technique that consists in coupling Global Positioning System (GPS) with Inertial Navigation System (INS). Imaging sensors would be more an additional navigation means, to be combined with existing navigation means. Lots of studies concerning the use of visual measurements for navigation have been achieved and cover a large range of applications, from precise guidance of a UAV during a landing [5], to the estimation of translation or velocity between two successive image of the landscape [7]. From the review of the applications, one of the most robust solutions to use visual measurements is to extract some geometrical measurements from the detection of targets in the image and to use them in a Kalman filter with GPS and INS measurements [1]. The optimal solution would be to couple these geometrical visual measurements, obtained through the detection of particular features, with other means currently used on board (mainly INS measurements and GPS pseudo-range measurements). The information extracted by visual measurements can characterize precisely the relative position of the camera with respect to the feature detected in the image. However, the knowledge of a distance (range between camera and feature, height of camera above ground or dimension of an object on the ground) is needed to determine a metric scale which is absolutely needed to interpret the image measurements. The current paper proposes a state of the art of image-aided navigation methods. A description of the key elements or characteristics used in these methods is done. Based on this, a proposition is done for a video-based navigation system for approach and landing operations. This is a first step of feasibility study for an aircraft landing system based on video.

As-cast low carbon steel strips produced by twin roll strip casting process were treated by cold rolling and batch annealing. The microstructure and mechanical properties were compared to those of drawing and commercial quality strips. The mechanical properties of the as-cast strip are inferior to those of an industrial hot band due to the presence of Widmannstatten ferrite microstructure. After simulated coiling, cold rolling and batch annealing the ductility of the strip cast steel is lower than that of the industrial products, due to the hardening effect of small Cu-S precipitates and coarser iron carbides. However, for the strip cast steel processed according to a drawing quality (DQ) route, the mechanical properties are within the range of a commercial quality (CQ) product. Therefore, mechanical properties falling within the range of commercial quality steel can be obtained with strip cast steel without a hot rolling step if appropriate cold rolling and annealing treatment is used.

This work is part of research on the emerging techniques to produce bulk nanostructured composites materials by severe plastic deformation and their characterization. Based on the Levi work, we present a new method to synthesize a composite wire-containing carbon-nanosized filaments (graphite and C60fullerenes) embedded in a copper matrix. The originality of this process is using powder media as fiber. Microstructures and electrical, mechanical, and thermal properties are presented.

The influence of C and heat treatment on the hot ductility of Nb-Ti microalloyed steels, in the temperature range 800 to 1300°C, was investigated by tensile testing at low strain rates. The C range was varied between 0.07 and 0.14 wt% (peritectic composition). The heat treatments involved direct heating to the test temperature, annealing at 1330°C and subsolidus reheating at 1480°C . The increase of the C content to 0.14 wt% slightly affects the hot ductility after the direct heating and annealing treatments. However, after subsolidus reheating, the width of the ductility trough is increased in the 0.14 wt% C steel. This effect is attributed to the coarser austenite structure inherited from this prior heat treatment.

The vegetative compatibility of the arbuscular mycorrhizal fungus (AMF) Glomus clarum MUCL 46238 was evaluated after continuous exposure to fenhexamid, a sterol biosynthesis inhibitor (SBI). Three lineages of this AMF were cultured in vitro for five generations in association with Ri T-DNA transformed carrot roots in the presence of 0, 5 or 10 mg l(-1) of fenhexamid. Whatever the AMF generation, fenhexamid at 5 and 10 mg l(-1) had no significant impact on the number of spores produced. However, vegetative compatibility tests (VCT) conducted with spores from the three lineages, in the presence of 10 mg l(-1) of fenhexamid, impacted the anastomosis process. At this concentration, the morphology of the germ tubes was modified. In addition, nitrotetrazolium-trypan blue staining revealed that 10 mg l(-l) of fenhexamid significantly reduced the probability of fusion between the germ tubes regardless of the culture conditions (i.e. absence or presence of fenhexamid) preceding the VCT. Our results demonstrated that spore production was not affected by fenhexamid, while anastomosis between germ tubes was decreased. This suggested that high concentrations, accumulation or repeated application of this SBI fungicide may impact the community structure of AMF in soil.

Background: In vitro studies suggest that the transcription factor nuclear factor-kappa B (NF-ĸB) is implicated in the transduction of proinflammatory signals in endometriosis. The aim of this study was to investigate the involvement of NF-ĸB and the processes regulated by NF-ĸB in the initial development of endometriotic lesionsin vivo.Methods: Endometriosis was induced in nude mice by intraperitoneal injection of fluorescent-labeled menstrual endometrium. Two NF-ĸB inhibitors (BAY 11-7085 and SN-50) were injected intraperitoneally on days 0, 2 and 4 after endometriosis induction, and endometriotic lesions were recovered on day 5. Number, mass, fluorimetry and surface (morphometry) of endometriotic lesions were quantified. NF-ĸB activation, intercellular adhesion molecule (ICAM)-1 expression, cell proliferation and apoptosis were evaluated by immunohistochemical analyses and the TUNEL method. Results: Both NF-ĸB inhibitors induced a significant reduction in lesion development compared to control mice. NF-ĸB activation and ICAM-1 expression of endometriotic lesions were significantly reduced in treated mice, and cell proliferation was significantly reduced in BAY 11-7085-treated mice. Both inhibitors produced a significant increase in apoptosis of endometriotic lesions, as assessed by active caspase-3 immunostaining and the TUNEL method. Conclusion: This study demonstrates, for the first time, that the NF-ĸB pathway is implicated in the development of endometriotic lesions in vivo and that NF-ĸB inhibition reduces ICAM-1 expression and cell proliferation, but increases apoptosis of endometriotic lesions, diminishing the initial development of endometriosis in an animal model.

International audience; Two kinds of high strength nanocomposite wires produced under heavy plastic deformation were investigated using 3D Atom Probe. First, cold drawn pearlitic steel wires were analyzed. Partly dissolved cementite lamellae were mapped out in 3D. The surface to volume ratio of cementite lamellae was correlated to their dissolution rate. Considering the increase of the interfacial energy during drawing, a model based on simple thermodynamical arguments was developed to estimate the global dissolution rate of cementite. Cu/Nb nanocomposite wires were also studied. Their nanoscale cross-section microstructure was revealed for the first time. 3D Atom Probe analysis pointed out a slight inter-diffusion of copper and niobium, and steps in copper channels attributed to tracks of moving dislocations in the (111) Cu plane, along the 〈110〉 direction.

Guillet Alain. Le lexique des verbes : description et organisation. In: L'Information Grammaticale, N. 59, 1993. pp. 23-35.