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Cyclone‐Anticyclone Asymmetry of Eddy Detection on Gridded Altimetry Product in the Mediterranean Sea
No full textInternational audienceWe perform an Observing System Simulation Experiment (OSSE), that simulates the satellite sampling and the mapping procedure on the sea surface of the high-resolution model CROCO-MED60v40, to investigate the reliability and the accuracy of the detected eddies. The main result of this study is a strong cyclone-anticyclone asymmetry of the eddy detection on the altimetry products AVISO/CMEMS in the Mediterranean Sea. Large scale cyclones having a characteristic radius larger than the local deformation radius are much less reliable than large scale anticyclones. We estimate, that less than 60
Nested branch-and-bound algorithm for minmax problem and constraints with quantifiers
No full textInternational audienceWe consider global optimization problems of a minmax function subject to constraints with quantifiers. The goal is to minimize over x the maximum over y of f(x,y), and constraints with quantifiers must be satisfied for a set of value (for all y in S). We present an algorithm to address this non-smooth objective function and the constraints with quantifiers in the same way. Our approach is a set-valued method based on two nested branch-and-bound algorithm, using interval analysis. This problem arises in structured robust control, semi-infinite optimization or minmax optimization
Easily Implemented Methods of Radiometric Corrections for Hyperspectral-UAV-Application to Guianese Equatorial Mudbanks Colonized by Pioneer Mangroves
No full textInternational audienceHyper-DRELIO (Hyperspectral DRone for Environmental and LIttoral Observations) is a custom, mini-UAV (Unmanned Aerial Vehicle) platform (< 20 kg) equipped with a light push broom hyperspectral sensor combined with a navigation module measuring position and orientation. Because of the particularities of UAV surveys (low flight altitude, small spatial scale and high resolution), dedicated pre-processing methods have to be developed when reconstructing hy-perspectral imagery.This article presents light easy-implementation in-situ methods, using only two Spectralon® and a field spectrometer, allowing to perform an initial calibration of the sensor in order to correct “vignetting effects” and a field standardization to convert Digital Numbers (DN) collected by the hyperspectral camera to reflectance, taking into account the time-varying illumination con-ditions. Radiometric corrections are applied to a subset of a dataset collected above mudflats colonized by pioneer mangroves in French Guiana. The efficiency of the radiometric corrections is assessed by comparing spectra from Hyper-DRELIO imagery to in-situ spectrometer meas-urements above the intertidal benthic biofilm and mangroves. The shapes of the spectra are con-sistent and the Spectral Angle Mapper (SAM) distance is of 0.039 above the benthic biofilm and of 0.159 above the mangroves. These preliminary results provide new perspectives for quanti-fying and mapping the benthic biofilm and mangroves at the scale of the Guianese intertidal mudbanks system, given their importance in the coastal food webs, biogeochemical cycles and the sediment stabilization
Application-Based Analysis of Transformations of Uncertain Dynamical Systems Into a Cooperative Form
No full textInternational audienceUncertainty in dynamical system descriptions can have different sources. Whether it be mathematical model simplifications, manufacturing tolerances, and imperfect measurements resulting in parameter uncertainties or be it some kind of time-varying uncertain parameters as an interpretation of state dependencies in quasi-linear state-space representations. On the one hand, uncertainties can be represented as probability distributions in the stochastic case, which can be handled, for example by Monte-Carlo methods. However, those do not allow for the computation of worst-case bounds of the sets of reachable states. On the other hand, interval representations do allow this, which is why we will use those as a bounded error framework in the presented paper. When dealing with interval uncertainty, the rigorous computation of guaranteed state enclosures is a difficult task. Due to conservatism and/or the wrapping effect, overestimation is a common problem. The paper discusses not only a suitable control approach based on LMIs to stabilize an uncertain system but also a cooperativity-enforcing approach, which acts as a countermeasure to the wrapping effect. This simplifies the computation of guaranteed state enclosures in comparison with different methods to get the least conservative hull of the reachable state intervals. This is all done for a boom crane as a real-life application scenario
Solving Mixed Variational Inequalities Beyond Convexity
No full textInternational audienceAbstract We show that Malitsky’s recent Golden Ratio Algorithm for solving convex mixed variational inequalities can be employed in a certain nonconvex framework as well, making it probably the first iterative method in the literature for solving generalized convex mixed variational inequalities, and illustrate this result by numerical experiments
Copper and Nickel Nanoparticles Prepared by Thermal Treatment of Their Respective Cations Confined in Nanopores through High-Pressure Synthesis
No full textInternational audienceA new and simple method for preparing confined copper and nickel nanoparticles by thermal treatment of their respective cations inside Mobil Composition of Matter 41 (MCM–41) hydrophobic nanopores is presented here. Surface modified MCM–41 hydrophobic materials were impregnated by using high-pressure treatment with copper II (Cu II) or nickel II (Ni II) aqueous solutions. After pressure release and washing, the remaining metal cations, confined exclusively within the nanopores, were heated, forming metallic nanoparticles. Reduction of the cations by a redox reaction between the hydrophobic organic surface and the confined metal cations is proposed. Transmission electronic microscopy (TEM), selected area electron diffraction (SAED), nitrogen (N2) adsorption at −196 °C (77 K), Fourier transform infrared (FTIR) and thermogravimetric (TGA) analyses evidenced the identification of copper and nickel nanoparticles (NPs)
Concepts and Semantics of Programming Languages 2: Modular and Object‐oriented Constructs with OCaml, Python, C++, Ada and Java
No full textInternational audienceThis book – composed of two volumes – explores the syntactical constructs of the most common programming languages, and sheds a mathematical light on their semantics, providing also an accurate presentation of the material aspects that interfere with coding.Concepts and Semantics of Programming Languages 2 presents an original semantic model, collectively taking into account all of the constructs and operations of modules and classes: visibility, import, export, delayed definitions, parameterization by types and values, extensions, etc. The model serves for the study of Ada and OCaml modules, as well as C header files. It can be deployed to model object and class features, and is thus used to describe Java, C++, OCaml and Python classes.This book is intended not only for computer science students and teachers but also seasoned programmers, who will find a guide to reading reference manuals and the foundations of program verification
Short pre-irradiation of TiO2 nanoparticles increases cytotoxicity on human lung coculture system
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Relationship Between Maximum Principle and Dynamic Programming in presence of Intermediate and Final State Constraints
No full textInternational audienceIn this paper, we consider a class of optimal control problems governed by a differential system.We analyze the sensitivity relations satisfied by the co-state arc of the Pontryagin maximum principle and the value function that associates the optimal value of the control problem to the initial time and state. Such a relationship has been already investigated for state-constrained problems under some controllability assumptions to guarantee Lipschitz regularity property of the value function. Here, we consider the case with intermediate and final state constraints, without any controllability assumption on the system, and without Lipschitz regularity of the value function. Because of this lack of regularity, the sensitivity relations cannot be expressed with the sub-differentials of the value function. This work shows that the constrained problem can be reformulated with an auxiliary value function which is more regular and suitable to express the sensitivity of the adjoint arc of the original state-constrained control problem along an optimal trajectory. Furthermore, our analysis covers the case of normal optimal solutions, and abnormal solutions as well.Dans cet article, nous considérons une classe de problèmes de contrôle optimal régis par un système différentiel non-linéaire. Nous analysons le lien entre l'état adjoint du Principe du Maximum de Pontryagin et la fonction de valeur qui associe la valeur optimale du problème de contrôle aux conditions initiales du système. Une telle relation a déjà été étudiée pour les problèmes de contraintes d'état sous certaines hypothèses de contrôlabilité afin de garantir la régularité Lipschitz de la fonction valeur. Ici, nous considérons le cas avec des contraintes d'état intermédiaires et finale, sans aucune hypothèse de contrôlabilité sur le système ni sur la régularité Lipschitz de la fonction valeur. A cause de ce manque de régularité, les relations de sensibilité ne peuvent pas s'exprimer avec les sous-differentiels de la fonction valeur. Par contre, on prouve que le problème contraint peut se reformuler avec une fonction valeur auxiliaire qui est plus régulière et qui permet d'exprimer la sensibilité de l'état adjoint du problème original avec contraintes d'état autour d'une trajectoire optimale. De plus, notre analyse couvre le cas d’extrémales normales, ainsi que le cas d'extrémales anormales