Motion Planning for Kinematic systems

In this paper, we present a general theory of motion planning for kinematic systems. This theory has been developed for long by one of the authors in a previous series of papers. It is mostly based upon concepts from subriemannian geometry. Here, we summarize the results of the theory, and we improve on, by developping in details an intricated case: the ball with a trailer, which corresponds to a distribution with flag of type 2,3,5,6. This paper is dedicated to Bernard Bonnard for his 60th birthday

The Food Prices / Body Mass Index Relationship: Theory and Evidence from a Sample of French Adults

What would be the effect of a "fat tax" on obesity? This paper shows that the sign of the price-weight correlation is unclear, as variations of food price have a direct effect on weight through changes in energy intakes, and an indirect (income) effect that affects energy expenditure. Food expenditures data are used to examine the link between the prices of 16 food groups and the distribution of the Body Mass Index among French adults. We find positive correlations for ready-meals and snacks, and negative correlations for sea products and fruits. It is thus unlikely that the epidemic of obesity will react in the short-term to nutritional taxes.obesity, fat tax, price policies, quantitle regressions, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, D1, H3, I1,

Tunable luminescence from Ce-doped aluminoborosilicate glasses

International audienceA series of aluminoborosilicate glasses were prepared using the melt-quenching technique for mixture of stoichiometric amounts of SiO 2 , Al 2 O 3 , H 3 BO 3 , Na 2 CO 3 , and ZrO 2 with adding of different amounts of CeO 2. The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes. Ce 3+ ions were widely used as activators in various fluoride and oxide materials. The preparation of RE-doped phosphor materials for application in advanced illumination technologies has been the subject of intense research during recent decades. These researches are stimulated by the necessity of increasing the efficiency in white light emitting solid state devices which represent an alternate lightning source [1

Synthesis of powellite-rich glasses for high level waste immobilization

International audienceIncreasing amounts of MoO3 were added to SiO2-B2O3-Na2O-CaO-Al2O3 glasses in order to trap molybdenum as powellite (nominally CaMoO4). Different heat treatments were performed to study their influences on powellite crystallization by X-ray diffraction and EPR. The glass compositions studied in this work lead to glass-ceramics rich in CaMoO4, up to [MoO3] = 5 mol% no poorly durable Na2MoO4 phase was identified by XRD. Trivalent actinides surrogates (Gd3+) were observed to incorporate into CaMoO4 crystals

Divalent Europium in beta irradiated aluminoborosilicate glass

International audienceThe reduction processes of Eu3+ ions in aluminoborosilicate glasses were studied using both high-temperature melting in air and b-irradiation by time-resolved luminescence and electron paramagnetic resonance spectroscopies. The Eu2+ ions produced during the synthesis are characterized by the UV excited broadband luminescence in the blue region due to the 4f 65d1–4f7 transition. This band revealed the presence more than one Eu2+ site participating in the emission with different crystalline fields and with different covalency of surrounding ligands. In irradiated glasses, the observed redshift of the Eu2+ emission band is related to the different relative proportion between Eu2+ sites

Microstructure of Powellite-Rich Glass-Ceramics: A Model System for High Level Waste Immobilization

International audienceIn this study, we synthesized glass-ceramics from glasses in the system SiO 2-B 2 O 3-Na 2 O-CaO-Al 2 O 3-MoO 3-Gd 2 O 3 by various heat treatments. Glass-ceramics contain only one crystalline phase in the bulk: powellite (namely CaMoO 4). The influence of molybdenum and rare earth contents was studied by SEM and XRD. Heat treatments were optimized to lead to a wide range in size and concentration of powellite. Moreover, the molybdenum content left in residual glasses, calculated by XRD quantification, showed that the residual glasses have a similar composition for a given Gd 2 O 3 content after heat treatments. This work has permitted to synthesize two phase glass-ceramics with constant borosilicate glass matrices and powellite crystals with controlled sizes and concentrations

b-Irradiation Effect in Aluminoborosilicate Glasses: The Role of RE Codoping (RE= Sm, Gd)

International audienceThe effect of Sm and Gd codoping on the structural modifications of β-irradiated aluminoborosilicate glasses has been studied by electron paramagnetic resonance (EPR) and Raman spectroscopy. The EPR spectra showed that the relative amount of Gd3+ ions occupying network former positions ( ) follows a nonlinear behavior as a function of the Sm/Gd ratio. This suggests that codoping favors the occupation by Gd3+ ions of the network former positions rather than the modifier positions in aluminoborosilicate glasses. The appearance of a superhyperfine structure of EPR lines attributed to boron–oxygen hole centers (BOHC) with increasing Sm/Gd ratio was observed. This suggests that Gd3+ ions are diluted in the vicinity of the BOHC defects. The concentration of defects created by irradiation reveals a nonlinear dependence on Sm and Gd codoping for the lowest irradiation dose (105 Gy). Therefore, codoping also affects the defect creation processes at least at the lowest irradiation dose. Raman spectroscopy measurements suggest that the irradiation-induced structural changes vary nonlinearly with the Sm/Gd ratio. In fact, the shift of the Si–O–Si bending vibration modes reveals a clear minimum for samples containing equal amounts of Sm and Gd (1 : 1) in the investigated glasses

A bisector line field approach to interpolation of orientation fields

We propose an approach to the problem of global reconstruction of an orientation field. The method is based on a geometric model called "bisector line fields", which maps a pair of vector fields to an orientation field, effectively generalizing the notion of doubling phase vector fields. Endowed with a well chosen energy minimization problem, we provide a polynomial interpolation of a target orientation field while bypassing the doubling phase step. The procedure is then illustrated with examples from fingerprint analysis

Évaluation des élasticites-prix de la demande des produits d’origine animale en France entre 1999 et 2009

La consommation de viandes a connu de profonds changements durant les quatre dernières décennies en France (FranceAgriMer, 2010). Le volume total consommé par habitant est passé de 77,6 kg équivalent carcasse par habitant en 1970 à 85,9/kg.ec/hab en 2012. Cette augmentation s’est accompagnée d’une modification de la structure de la consommation en termes d’espèces. La part des viandes issues de ruminants (boeuf, veau et ovin/caprin) a baissé au profit des viandes de monogastriques (porc et volailles). Cette contribution vise à mesurer les parts budgétaires consacrées aux produits d’origine animale (hors produits laitiers) et à mesurer la sensibilité de la demande à leur variation de prix