The predictive functional control and the management of constraints in GUANAY II autonomous underwater vehicle actuators

Autonomous underwater vehicle control has been a topic of research in the last decades. The challenges addressed vary depending on each research group's interests. In this paper, we focus on the predictive functional control (PFC), which is a control strategy that is easy to understand, install, tune, and optimize. PFC is being developed and applied in industrial applications, such as distillation, reactors, and furnaces. This paper presents the rst application of the PFC in autonomous underwater vehicles, as well as the simulation results of PFC, fuzzy, and gain scheduling controllers. Through simulations and navigation tests at sea, which successfully validate the performance of PFC strategy in motion control of autonomous underwater vehicles, PFC performance is compared with other control techniques such as fuzzy and gain scheduling control. The experimental tests presented here offer effective results concerning control objectives in high and intermediate levels of control. In high-level point, stabilization and path following scenarios are proven. In the intermediate levels, the results show that position and speed behaviors are improved using the PFC controller, which offers the smoothest behavior. The simulation depicting predictive functional control was the most effective regarding constraints management and control rate change in the Guanay II underwater vehicle actuator. The industry has not embraced the development of control theories for industrial systems because of the high investment in experts required to implement each technique successfully. However, this paper on the functional predictive control strategy evidences its easy implementation in several applications, making it a viable option for the industry given the short time needed to learn, implement, and operate, decreasing impact on the business and increasing immediacy.Peer ReviewedPostprint (author's final draft

Non-local numerical treatment of non-linear behavior by means of Helmholtz equation, with variable coefficients. Application to reinforced concrete structures.

Numerous work has been done with the aim of modeling the cracking of reinforced concrete (RC) structures. Among the recent methods proposed in the literature, the combination of reinforcement-concrete equilibrium combined with the linear behavior of the interface leads to a Helmholtz equation which takes account of the slip between the homogenized reinforcements and the concrete in presence of localized cracks [1][2]. In the case of large cracks openings, it is necessary to consider the non-linear behaviors of material and interfaces, such as the plasticity of reinforcements or the damage of the matrix-reinforcement interface. These phenomena induce variations of the coefficients in the Helmholtz equation, which leads to two levels of iterative procedures: one at a global level considering equilibrium of homogenized RC, and another one at a non-local level taking account of equilibrium between reinforcement and concrete. The implementation of a convergence criterion is then needed at each level. The goal of this paper is to describe the developments implemented in the Finite Element code Cast3m to perform non-local Helmholtz type calculations with non-constant coefficients. This method, using an acceleration method [3] is illustrated by the cases of reinforced concrete tie and beam, with homogenized reinforcements. References : [1] A. Sellier and A. Millard, “A homogenized formulation to account for sliding of non-meshed reinforcements during the cracking of brittle matrix composites: Application to reinforced concrete,” Eng. Fract. Mech., vol. 213, pp. 182–196, May 2019, doi: 10.1016/j.engfracmech.2019.04.008. [2] A. Sellier and A. Millard, “Traitement numérique non local de phénomènes physiques par l’équation d’Helmholtz : les effets d’échelle et le glissement renfort-matrice,” in Club Cast3M 2018, Paris, 2018, vol. 1, no. 1, pp. 12–18. Available: http://www-cast3m.cea.fr/html/ClubCast3m/club2018/Presentation_Sellier.pdf. [3] A. C. Aitken, “On the iterative solution of a system of linear equations.,” Proc. Roy. Sot. Edinburgh, pp. 52–60, 1950

Chemical modelling of Alkali Silica reaction: Influence of the reactive aggregate size distribution

International audienceThis article presents a new model which aims at the prediction of the expansion induced by Alkali Silica Reaction (ASR) and the description of the chemical evolution of affected concretes. It is based on the description of the transport and reaction of alkalis and calcium ions within a Relative Elementary Volume (REV). It takes into account the influence of the reactive aggregate size grading on ASR, i.e. the effect of the simultaneous presence of different sized reactive aggregates within concrete. The constitutive equations are detailed and fitted using experimental results. Results from numerical simulations are presented and compared with experiments.Cet article présente un modèle qui a pour but la prédiction du gonflement induit par la réaction alcali-silice et la description de l'évolution chimique des bétons affectés. Il est basé sur la description du transport et de la réaction des alcalins et des ions calcium dans un Volume Elémentaire Représentatif. Il permet notamment de tenir compte de l'influence de la granulométrie réactive, c'est-à-dire de l'influence de la présence simultanée de granulats réactifs de différentes tailles dans le béton. Les équations constitutives du modèle sont détaillées puis calées à partir de résultats expérimentaux. Les résultats des simulations numériques sont présentés et comparés aux valeurs expérimentales

Risk due to creep of prestressed concrete at moderate temperature

This study is a part of a French national project dealing with the mechanical behaviour of the containment vessel of French Nuclear Power Plants in case of a severe accident. The accident conditions are characterized by the increases of internal pressure, +0.5 MPa, and of temperature, up to 180°C, during two weeks. Heating can induce a strong increase of creep deformations kinetics leading to prestressing losses of concrete. Associated to internal pressure, tensile stress could occur in some areas of the structure and the potential cracking could affect the containment capacity of the vessel. One of the objectives of the project was thus to provide original creep data to develop accurate models, taking into account the coupled effects of temperature, desiccation and damage, and able to predict the behaviour of prestressed concrete structures in such insitu conditions. A wide experimental program consisted of numerous creep tests under various thermo-hydro-mechanical conditions in the values range of the accident. The presented results concern uniaxial compressive and flexural creep tests respectively performed on concrete cylinders and prestressed concrete beams, at 20°C and 40°C without desiccation

Effets des couplages thermo-hydro-mécaniques sur le comportement différé du béton précontraint

Le projet ANR MACENA (MAitrise du Confinement d'une ENceinte en Accident) concerne l'étude du comportement de l'enceinte interne en béton précontraint d'une centrale nucléaire dans le cas d'un accident sévère. Ces conditions se caractérisent par une pression interne de 5 bars et une température pouvant atteindre 180°C durant deux semaines. L'augmentation des déformations, notamment différées, qui en résulte peut engendrer des pertes de précontrainte significatives et des redistributions de contraintes susceptibles d'induire une fissuration préjudiciable à la capacité de maintien du confinement vis-à-vis de la dispersion potentielle de radionucléides. Pour être capable de modéliser le comportement mécanique du béton précontraint de l'enceinte en phase accidentelle, et de disposer d'outils prédictifs fiables, des données expérimentales sont nécessaires. Peu d'investigations ont été menées sur le comportement mécanique du matériau béton dans de telles conditions thermo-hydro-mécaniques. Les rares résultats disponibles de la bibliographie mettent néanmoins en évidence des effets non négligeables de la température, des contraintes hydriques et mécaniques, sur les déformations du matériau, ainsi que de forts couplages. Cette étude a pour principal objectif de fournir des données originales afin d'alimenter et d'améliorer les modèles existants. Le programme expérimental réalisé est constitué de trois types d'essais de fluage : en compression uniaxiale à deux taux de chargement, modéré et intense, en flexion quatre points sur béton non armé, et en flexion quatre points sur poutres d'échelle réduite en béton précontraint par post-tension. Pour chaque type d'expérimentation, plusieurs configurations thermiques, hydriques et mécaniques sont étudiées dans le cadre du projet. Les résultats présentés concernent la plage de température 20°C-40°C et les conditions de conservation en endogène ou en séchage à 50%HR. Ils permettent d'estimer la perte de précontrainte due aux effets couplés des déformations différées du béton et de la relaxation des aciers de précontrainte, et d'évaluer le comportement structural d'éléments de petite dimension. La base de données issue des différents programmes d'essais de l'ensemble de ce projet de recherche contribue à améliorer la compréhension des effets couplés du séchage, de la température et de l'endommagement, et à affiner leurs prises en compte dans la modélisation en vue de la prédiction du comportement du béton précontraint en conditions accidentelles de l'enceinte

Experimental investigation of the variability of concrete durability properties

One of the main objectives of the APPLET project was to quantify the variability of concrete properties to allow for a probabilistic performance-based approach regarding the service lifetime prediction of concrete structures. The characterization of concrete variability was the subject of an experimental program which included a significant number of tests allowing the characterization of durability indicators or performance tests. Two construction sites were selected from which concrete specimens were periodically taken and tested by the different project partners. The obtained results (mechanical behavior, chloride migration, accelerated carbonation, gas permeability, desorption isotherms, porosity) are discussed and a statistical analysis was performed to characterize these results through appropriate probability density functions

Over-expression of adenosine deaminase in mouse podocytes does not reverse puromycin aminonucleoside resistance

<p>Abstract</p> <p>Background</p> <p>Edema in nephrotic syndrome results from renal retention of sodium and alteration of the permeability properties of capillaries. Nephrotic syndrome induced by puromycin aminonucleoside (PAN) in rats reproduces the biological and clinical signs of the human disease, and has been widely used to identify the cellular mechanisms of sodium retention. Unfortunately, mice do not develop nephrotic syndrome in response to PAN, and we still lack a good mouse model of the disease in which the genetic tools necessary for further characterizing the pathophysiological pathway could be used. Mouse resistance to PAN has been attributed to a defect in glomerular adenosine deaminase (ADA), which metabolizes PAN. We therefore attempted to develop a mouse line sensitive to PAN through induction of normal adenosine metabolism in their podocytes.</p> <p>Methods</p> <p>A mouse line expressing functional ADA under the control of the podocyte-specific podocin promoter was generated by transgenesis. The effect of PAN on urinary excretion of sodium and proteins was compared in rats and in mice over-expressing ADA and in littermates.</p> <p>Results</p> <p>We confirmed that expression of ADA mRNAs was much lower in wild type mouse than in rat glomerulus. Transgenic mice expressed ADA specifically in the glomerulus, and their ADA activity was of the same order of magnitude as in rats. Nonetheless, ADA transgenic mice remained insensitive to PAN treatment in terms of both proteinuria and sodium retention.</p> <p>Conclusions</p> <p>Along with previous results, this study shows that adenosine deaminase is necessary but not sufficient to confer PAN sensitivity to podocytes. ADA transgenic mice could be used as a background strain for further transgenesis.</p

Rapid response to the M_w 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to large damages it produced in several villages. InSAR interferograms indicated a shallow rupture about 4 km long reaching the surface and the reactivation of the ancient NE-SW La Rouviere normal fault in reverse faulting in agreement with the present-day E-W compressional tectonics. The peculiarity of this earthquake together with a poor coverage of the epicentral region by permanent seismological and geodetic stations triggered the mobilisation of the French post-seismic unit and the broad French scientific community from various institutions, with the deployment of geophysical instruments (seismological and geodesic stations), geological field surveys, and field evaluation of the intensity of the earthquake. Within 7 days after the mainshock, 47 seismological stations were deployed in the epicentral area to improve the Le Teil aftershocks locations relative to the French permanent seismological network (RESIF), monitor the temporal and spatial evolution of microearthquakes close to the fault plane and temporal evolution of the seismic response of 3 damaged historical buildings, and to study suspected site effects and their influence in the distribution of seismic damage. This seismological dataset, completed by data owned by different institutions, was integrated in a homogeneous archive and distributed through FDSN web services by the RESIF data center. This dataset, together with observations of surface rupture evidences, geologic, geodetic and satellite data, will help to unravel the causes and rupture mechanism of this earthquake, and contribute to account in seismic hazard assessment for earthquakes along the major regional Cévenne fault system in a context of present-day compressional tectonics