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International audience; The main reason for the early failure of radio-cephalic arteriovenous fistula (RCAVF) is non-maturity, which means that the blood flow rate in the fistula cannot increase to the expected value for dialysis. From a mechanical perspective, the vascular resistance at the artificially designed anastomosis causes an energy loss that affects blood flow rate growth and leads to early failure. This research studied how to maximize the RCA VF maturity and primary patency by controlling the energy loss rate. We theoretically analyzed and derived a model that evaluates the energy loss rate Eavf in RCAVF as a function of its blood vessel geometric parameters (GPs) for given flow rates. There was an aggregate of five controllable GPs in RCAVF: radial artery diameter (Dra), cephalic vein diameter (Dcv), blood vessel distance between artery and vein (h), anastomotic diameter (Da), and anastomotic angle (). Through this analysis, it was found that Eavf was inversely proportional to Dra, Dcv, Da, and , whereas proportional to h. Therefore, we recommended surgeons choose the vessels with large diameters , close distance, and increase the diameter and angle of the anastomosis to decrease the early failure of RCAVF. Simultaneously, we could explain the results of many clinical empiricisms with our formula. We found that increasing Dcv and  were more significant in reducing Eavf than increasing Dra and Da. Based on our model, we could define two critical energy loss rates (CELa, CELb) to help surgeons evaluate the blood vessels and choose the ideal range of . Help them design the preoperative RCAVF plan for each patient to increase the maturity and the primary patency of RCAVF.

This article focuses on the assessment of microclimatic conditions in the Ottoman residential buildings in the old city of Algiers. It aims to identify the nature of architectural transformations and to analyse their impact on hygrothermal comfort and the indoor microclimate so as to suggest ways to improve the current level of comfort within the traditional houses. The object of this article is to identify the nature of this transformation process, to find out, not only what triggers it but what fuels it, and to analyse its impact on the environment, or more specifically, on the hygrothermal comfort, within the building. It entails, primarily, an analysis of the colonial and post-colonial architectural transformations, followed by a verification of all the components of hygrothermal comfort through numerical simulation and modelling. The aim is to correct the interior comfort of the current houses in the Casbah. The results obtained will clarify the nature of these colonial and post-colonial changes, which were carried out to satisfy the needs of the inhabitants, and lead to an evaluation of environmental quality, assessed through the parameters that influence the indoor microclimate of houses in Algeria.

Crude oil is a major energy source that is exploited globally to achieve economic growth. To meet the growing demands for oil, in an environment of stringent environmental regulations and economic and technical pressure, industries have been required to develop novel oil salvaging techniques. The remaining ~70% of the world’s conventional oil (one-third of the available total petroleum) is trapped in depleted and marginal reservoirs, and could thus be potentially recovered and used. The only means of extracting this oil is via microbial enhanced oil recovery (MEOR). This tertiary oil recovery method employs indigenous microorganisms and their metabolic products to enhance oil mobilization. Although a significant amount of research has been undertaken on MEOR, the absence of convincing evidence has contributed to the petroleum industry’s low interest, as evidenced by the issuance of 400+ patents on MEOR that have not been accepted by this sector. The majority of the world’s MEOR field trials are briefly described in this review. However, the presented research fails to provide valid verification that the microbial system has the potential to address the identified constraints. Rather than promising certainty, MEOR will persist as an unverified concept unless further research and investigations are carried out.

National audience; * Développement d’une technique originale d'imprégnation directe de renforts continus de lin par des thermoplastiques totalement ou partiellement bio-sourcés, par injection dans un moule fermé* Étude multi-échelles des mécanismes d'imprégnation / gonflement sous contraintes thermo-hydromécaniques des fibres végétales. Déduction des évolutions de propriétés physiques et mécaniques* Étude des mécanismes d’imprégnation de composites moulés à haute cadence avec des thermoplastiques mono- ou bi-composants de haute fluidité* Assemblage de pièces composites renforcées de fibres végétales par soudage laser* Qualification de la résistance des joints de soudure des composites thermoplastiques bio-sourcés

National audience; POPCOM Composites Advanced Manufacturing Platform @ IMT LIlle Douai : Original facilities for development and industrialization of structural composites and reinforced polymers, embracing the whole chain of product life cycle … the ‘’Swiss Army Knife’’ of composites.

This thesis combines observations, simulations and development of high-performance numerical tools in the field of underwater acoustics, and in particular for the study of T-waves.The term T-waves is generally associated with acoustic waves generated by seismic events that subsequently travel horizontally in the ocean at the speed of sound. After a thematic review of the literature on T-waves we analyzed real data recorded in Sicily and Calabria following earthquakes occurring near the West coast of Greece. In order to model the phenomenon, we developed an axisymmetric spectral-element solver (2.5-D) in the time domain, which we present and validate. This tool allowed us to realistically reproduce numerically one of the Greek earthquakes studied as well as the propagation of the resulting T-waves up to Sicily.We also present a two-stage parametric study of the influence of seafloor slope in a typical T-wave generation/conversion scenario. The energy and duration of these waves is particularly sensitive to the environment. In particular, the slopes and characteristics of the seabed play a crucial role for both solid-fluid and fluid-solid conversion. These characteristics can mislead localization algorithms. Likewise, the depth and position of the earthquake relative to the slope is of great importance, with the presence of privileged areas for the generation of T-waves, which we have mapped. In addition, in the case of the conversion of an acoustic wave on a coast, our simulations predict that in some cases a strong Rayleigh wave can be generated, whose signal, recorded inland, is very sensitive to the slope and to the characteristics of the environment, but not very sensitive to the modal structure of the incident wave. This phenomenon may have interesting implications that we discuss.However, our studies confirm that at regional distances (< 1000 km) the sound speed profile in the ocean is only a second-order parameter. To evaluate its impact we have developed a procedure for the calculation of transmission-loss and time-dispersion maps from full-wave numerical simulations in the time domain. In the configurations studied, the presence of the SOFAR channel slightly limits the time dispersion but only introduces a gain in terms of energy transmission of a few thousandths of dB per kilometer.In a second step, we show that a medium-sized commercial vessel, as there are tens of thousands nowadays in the oceans of the globe, can generate by diffraction some T-waves of significant amplitude (of the order of those created by downslope conversion on a slope of 12^{\circ}) and of low dispersion. This mechanism of T-wave generation, to our knowledge undocumented, must be particularly frequent in areas in which maritime traffic is substantial and could explain some abyssal T-waves that are still not well understood. Taking the atmosphere into account in these simulations, we realized that the presence of these vessels could also produce guided infrasound in the lower layers of the atmosphere. This mechanism of infrasound production could be an alternative explanation to the evanescent coupling proposed by Evers et al. (2014) to explain the waves observed in Tasmania following an earthquake on the Macquarie Ridge.Finally, we presented and validated some numerical tools to calculate the acoustic field created by a moving source. The method was applied to a light aircraft flying over the ocean. This configuration, presented by Buckingham (2010), can be used to estimate the pressure wave speed in marine sediments.; Cette thèse mêle observations, simulations et développement d'outils numériques haute performance dans le domaine de l’acoustique sous-marine, et notamment pour l’étude des ondes T.Le terme ondes T est généralement associé à des signaux acoustiques générés par des événements sismiques et qui se déplacent ensuite horizontalement dans l'océan à la vitesse du son. Après une revue thématique de la littérature sur les ondes T nous avons analysé des données réelles enregistrées en Sicile et en Calabre à la suite de tremblements de terre survenus près de la côte ouest de la Grèce. Afin de modéliser le phénomène nous avons développé un solveur éléments spectraux axisymétriques (2.5-D) dans le domaine temporel, que nous présentons et validons. Cet outil nous a permis de reproduire numériquement de façon réaliste un des séismes grecs étudiés ainsi que la propagation des ondes T résultantes jusqu'en Sicile.Nous présentons également une étude paramétrique en deux temps de l'influence de la pente du plancher océanique dans un scénario typique de génération/conversion d'une onde T. L'énergie et la durée de ces ondes s’avère être particulièrement sensible à l'environnement. En particulier nous avons vu que les pentes et les caractéristiques du fond marin jouaient un rôle capital autant sur la conversion solide - fluide que fluide - solide. Ces particularités peuvent d'ailleurs tromper les algorithmes de localisation. De même, la profondeur et la position du tremblement de terre vis-à-vis de la pente s'avèrent être de grande importance, avec la présence de zones privilégiées pour la génération des ondes T, que nous avons cartographiées. En outre, dans le cas de la conversion d'une onde acoustique sur une côte, nos simulations prédisent dans certains cas la création d'une forte onde de Rayleigh dont le signal, enregistré à l'intérieur des terres, est très sensible à la pente et aux caractéristiques de l'environnement, mais très peu sensible à la structure modale de l'onde incidente. Ce phénomène peut avoir des implications intéressantes que nous discutons.Cependant, nos études confirment qu’aux distances régionales (< 1000 km) le profil de vitesse dans l'océan s'avère n'être qu'un paramètre de deuxième ordre. Pour en évaluer l’impact nous avons développé une procédure pour le calcul de cartes de perte de transmission et de dispersion à partir de simulations numériques en forme d'onde complète dans le domaine temporel. Dans les configurations étudiées, la présence du canal SOFAR limite légèrement la dispersion temporelle mais n'introduit un gain en termes de transmission énergétique que de l'ordre de quelques millièmes de dB par kilomètre.Dans un second temps nous montrons qu'un bateau commercial de taille moyenne, comme il y en a aujourd'hui des dizaines de milliers sur les mers du globe, peut créer par diffraction des ondes T d'une d'amplitude conséquente (de l'ordre de celles créées par conversion « downslope » sur une pente de 12^{\circ}) et de faible dispersion. Ce mode de génération d'onde T, encore non documenté, doit être particulièrement fréquent dans les zones où le trafic maritime est important et pourrait expliquer certaines ondes T abyssales encore incomprises. En prenant l'atmosphère en compte dans ces simulations nous nous sommes aperçu que la présence de ces mêmes navires pouvait également générer des infrasons guidés dans les couches basses de l'atmosphère. Ce mode de production d'infrasons pourrait constituer une explication alternative au couplage évanescent proposé par Evers et al. (2014) pour expliquer les ondes observées en Tasmanie à la suite d'un tremblement de terre sur la dorsale Macquarie.Pour finir, nous avons présenté et validé des outils numériques pour calculer le champ acoustique créé par une source en mouvement. La méthode a été appliquée au cas d'un avion léger volant au-dessus de l'océan. Cette configuration, présentée par Buckingham (2010), peut permettre d'estimer la vitesse des ondes de compression dans les sédiments.

Intensification des transferts en agroalimentaire : approches numérique et expérimentale Synthèse des travaux de recherche En vue d'obtenir le diplôme d'Habilitation à diriger des Recherches

International audience; In the presented study, a numerical model which predicts the flow-induced collapse within the pharyngeal airway is validated using in vitro measurements. Theoretical simplifications were considered to limit the computation time. Systematic comparisons between simulations and measurements were performed on an in vitro replica, which reflects asymmetries of the geometry and of the tissue properties at the base of the tongue and in pathological conditions (strong initial obstruction). First, partial obstruction is observed and predicted. Moreover, the prediction accuracy of the numerical model is of 4.2% concerning the deformation (mean quadratic error on the constriction area). It shows the ability of the assumptions and method to predict accurately and quickly a fluid-structure interaction.