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DOCTOR OF PHILOSOPHY In the field of Chimie organique Application of the Radical Chemistry of Xanthates to the Synthesis of Cyclic or Acyclic Amines
No full textIn chapter 1, general aspects of radical chemistry are briefly introduced. Improvements and applications of the Barton radical decarboxylation, the Barton-McCombie radical deoxygenation and the radical chemistry of xanthates are also described in this chapter. In chapter 2, various methods for the construction of amines and especially radical hydroaminomethylation reaction developed in our group are described. In chapter 3, based on our previous experiences of radical hydroaminomethylation reactions, the synthesis of protected amines, 1,3-diamines, β-aminoacids involving in another radical process, the Wohl-Ziegler reaction, will be described. In chapter 4, a modular approach to access highly complex protected 1,2-diamines via the degenerative transfer of xanthates to protected 1,2-diamino alkenes will be described. Several extensions to prepare mono-protected diamines or indoline bearing diamino-unit will also be mentioned.In chapter 5, we will describe a newly developed modular approach to access highly substituted Boc-protected 4-aminomethyl-pyrroles via a radical addition of various α-xanthyl ketones to Boc-protected azetine following by the aminolysis of adducts. Therefore, plentiful functionalities can be incorporated into the final pyrrole products either through a xanthate partner or through ammonia or a primary amine.Le travail de thèse de mené par monsieur Songzhe HAN comporte trois parties. La première concerne l’ étude d’un nouvel acces aux amines primaires sous leurs formes protégées par un groupe phtalimide par voie radicalaire. Une voie a été mise au point pour la synthèse du xanthate via une étape de bromation radicalaire au NBS.La deuxième partie concerne l’étude d’un nouvel accès aux diamines sous leurs formes protégées par additions radicalairs. De plus, M. Songzhe Han a rapporté un nouvel accès aux N-Boc 4-aminométhyl-pyrroles via une addition radicalaire de divers xanthates sur l'N –Boc azétine Boc suivie d'une aminolyse des adduits radicalairs obtenus
Voxel-based path planning for 3D scanning of mechanical parts
No full textInternational audienceThe paper deals with an original approach to scan path planning that applies for any type of sensors. The approach relies on the representation of the part surface as a voxel map. The size of each voxel is defined according to the sensor FOV. To each voxel, a unique point of view is associated in function of visibility and quality criteria. Whatever the sensor, the method provides a set of admissible points of view to ensure the surface digitizing with a given quality
Prolonged eruptive history of a compound volcano on Mercury: Volcanic and tectonic implications
No full textInternational audienceA 27 × 13 km 'rimless depression' 100 km inside the southwest rim of the Caloris basin is revealed by high resolution orbital imaging under a variety of illuminations to consist of at least nine overlapping volcanic vents, each individually up to 8 km in diameter. It is thus a 'compound' volcano, indicative of localised migration of the site of the active vent. The vent floors are at a least 1 km below their brinks, but lack the flat shape characteristically produced by piston-like subsidence of a caldera floor or by flooding of a crater bottom by a lava lake. They bear a closer resemblance to volcanic craters sculpted by explosive eruptions and/or modified by collapse into void spaces created by magma withdrawal back down into a conduit. This complex of overlapping vents is at the summit of a subtle edifice at least 100 km across, with flank slopes of about only 0.2 degrees, after correction for the regional slope. This is consistent with previous interpretation as a locus of pyroclastic eruptions. Construction of the edifice could have been contributed to by effusion of very low viscosity lava, but high resolution images show that the vent-facing rim of a nearby impact crater is not heavily embayed as previously supposed on the basis of lower resolution flyby imaging. Contrasts in morphology (sharpness versus blurredness of the texture) and different densities of superposed sub-km impact craters inside each vent are consistent with (but do not prove) substantial differences in the age of the most recent activity at each vent. This suggests a long duration of episodic magmagenesis at a restricted locus. The age range cannot be quantified, but could be of the order of a billion years. If each vent was fed from the same point source, geometric considerations suggest a source depth of at least 50 km. However, the migration of the active vent may be partly controlled by a deep-seated fault that is radial to the Caloris basin. Other rimless depressions in this part of the Caloris basin fall on or close to radial lines, suggesting that elements of the Pantheon Fossae radial fracture system that dominates the surface of the central portion of the Caloris basin may continue at depth almost as far as the basin rim. © 2013 Elsevier B.V
Librational response of a deformed 3-layer Titan perturbed by non-Keplerian orbit and atmospheric couplings
No full textInternational audienceThe analyses of Titan's gravity field obtained by Cassini space mission suggest the presence of an internal ocean beneath its icy surface. The characterization of the geophysical parameters of the icy shell and the ocean is important to constrain the evolution models of Titan. The knowledge of the librations, that are periodic oscillations around a uniform rotational motion, can bring a piece of information on the interior parameters. The objective of this paper is to study the librational response in longitude from an analytical approach for Titan composed of a deep atmosphere, an elastic icy shell, an internal ocean, and an elastic rocky core perturbed by the gravitational interactions with Saturn. We start from the librational equations developed for a rigid satellite in synchronous spin-orbit resonance. We introduce explicitly the atmospheric torque acting on the surface computed from the Titan IPSL GCM (Institut Pierre Simon Laplace General Circulation Model) and the periodic deformations of elastic solid layers due to the tides. We investigate the librational response for various interior models in order to compare and to identify the influence of the geophysical parameters and the impact of the elasticity. The main librations arise at two well-separated forcing frequency ranges: low forcing frequencies dominated by the Saturnian annual and semi-annual frequencies, and a high forcing frequency regime dominated by Titan's orbital frequency around Saturn. At low forcing frequency, the librational response is dominated by the Saturnian gravitational torque and the atmospheric torque has a small effect. In addition, the libration amplitude in that case is almost equal to the magnitude of the perturbation. The modulation of the gravitational torque amplitude at the orbital frequency with periodic deformation induces long-period terms in the librational response which contain information on the internal structure. At high forcing frequency the libration depends on the inertia of the layers and the elasticity can strongly reduce its amplitude at orbital frequency. For example, the amplitude of diurnal libration for oceanic models goes from about 320-390 m if the icy shell is purely rigid to 60-85 m when the elasticity is included, i.e. a reduction of about 80%. For models without ocean, diurnal libration goes from 52 m in a rigid case to 50 m for an elastic case, a very low reduction due to the weak deformation of an entirely solid satellite compared to the deformation of a thin icy shell. Oceanic models with elastic solid layers have the same order of libration amplitude than the oceanless models, which makes more challenging to differentiate them by the interpretation of librational motion. © 2014 Elsevier Ltd
Playing Mastermind with Constant-Size Memory
No full textInternational audienceWe analyze the classic board game of Mastermind with n holes and a constant number of colors. The classic result of Chvátal (Combinatorica 3:325–329, 1983) states that the codebreaker can find the secret code with Θ(n/logn) questions. We show that this bound remains valid if the codebreaker may only store a constant number of guesses and answers. In addition to an intrinsic interest in this question, our result also disproves a conjecture of Droste, Jansen, and Wegener (Theory Comput. Syst. 39:525–544, 2006) on the memory-restricted black-box complexity of the OneMax function class
Prévention solaire en milieu scolaire : UV, dose érythèmale, synthèse de vitamine D et prévention solaire font-ils bon ménage ?
No full textInternational audienceUne prévention solaire efficace en milieu scolaire se heurte à plusieurs obstacles : enfants exposés de façon prolongée (récréation, activités sportives, centre de loisir) et difficultés de mettre en œuvre des mesures adéquates (interdiction d’appliquer des crèmes de protection solaire par le personnel par exemple). Il s’agit de plus d’un axe non prioritaire de prévention pour l’enseignement national par rapport aux addictions et au risque sexuel.Nous avons évalué, à l’aide de techniques validées par des études antérieures, le rapport bénéfice (synthèse de vitamine D – dose cible : recommandations OMS)/risque (dose érythèmale minimale [DEM]) de l’exposition solaire en milieu scolaire associée à une étude des comportements de prévention
Integrable G-strands on semisimple Lie groups
No full textInternational audienceThe present paper derives systems of partial differential equations that admit a quadratic zero curvature representation for an arbitrary real semisimple Lie algebra. It also determines the general form of Hamilton's principles and Hamiltonians for these systems, and analyzes the linear stability of their equilibrium solutions in the examples of and
Théorie géométriquement exacte des tuyaux souples avec écoulement interne
No full textInternational audienceInstability of flexible tubes conducting fluid, or “garden hose instability”, is a phenomenon both familiar from everyday life and important for applications, which has been actively studied. However, previous works did not consider one of the most crucial physical effects — the dynamical change of the cross-section. We show how to consistently address this issue by coupling the geometrically exact rod dynamics with the fluid motion via the use of a constrained Hamilton's variational principle. We find strong effect of this dynamics on stability, and derive a variety of exact nonlinear solutions of traveling-wave type.L'instabilité des tuyaux souples avec écoulement interne, ou « instabilité du tuyau d'arrosage », est un phénomène commun, étudié de longue date, et qui a d'importantes applications. Cependant, les travaux antérieurs ne tiennent pas compte d'un effet crucial : la dynamique de la section transversale du tube. Nous montrons comment l'inclure dans la dynamique en utilisant un principe de Hamilton avec contrainte, couplant la dynamique d'une tige géométriquement exacte et celle de l'écoulement interne. Nous prouvons que cela affecte l'instabilité et calculons une classe de solutions exactes de type ondes progressives