Belief functions contextual discounting and canonical decompositions

In this article, the contextual discounting of a belief function, a classical discounting generalization, is extended and its particular link with the canonical disjunctive decomposition is highlighted. A general family of correction mechanisms allowing one to weaken the information provided by a source is then introduced, as well as the dual of this family allowing one to strengthen a belief function.     

Descent algorithm for nonsmooth stochastic multiobjective optimization

An algorithm for solving nearly-separable quadratic optimization problems (QPs) is presented. The approach is based on applying a semismooth Newton method to solve the implicit complementarity problem arising as the first-order stationarity conditions of such a QP. An important feature of the approach is that, as in dual decomposition methods, separability of the dual function of the QP can be exploited in the search direction computation. Global convergence of the method is promoted by enforcing decrease in component(s) of a Fischer–Burmeister formulation of the complementarity conditions, either via a merit function or through a filter mechanism. The results of numerical experiments when solving convex and nonconvex instances are provided to illustrate the efficacy of the method.     

Bisphenol-A polycarbonate–poly(butylene terephthalate) transesterification. II. Structure analysis of the reaction products by IR and 1H and 13C NMR

The structure of the four-component copolyester resulting from the exchange reaction between molten bisphenol-A polycarbonate and poly(butylene terephthalate) is analyzed as a function of the reaction time by infrared and nuclear magnetic resonance spectroscopy. By applying a statistical method developed earlier, the mean chain length of the various sequences as well as the degree of randomness is computed. The exchange reaction leads initially to the formation of a block copolyester with reduced solubility. As the reaction proceeds, a soluble random copolycondensate is progressively formed.     

Thermodynamical insertion of lithium in V5S8. Validity domain of the Thompson method

EMF versus Li-composition relation is determined by electrochemical insertion for Li-V₅S₈. The values of the thermodynamic functions ΔG, ΔH, ΔS corresponding to the lithium insertion reaction have been deduced. The Thompson method (electrochemical potential spectroscopy) has been applied to the V₅S₈ cathode, but it appears not valid in our case. The calculation of current versus time function is made to analyze the validity of this method. This technique requires: fast diffusion of Li in the host material, small grain size, small increments of applied voltage, low value of the cut-off current.     

Raman scattering from GaSxSe1-x

The non resonant Raman scattering spectra of GaSe, GaS and of eight different mixed crystals GaS_xSe_1-x are presented. The frequencies of some vibrational modes shift continuosly from GaSe to GaS indicating that the mixed crystals are homogeneous. The discontinuous shift of some other modes is explained either by the change of the stacking of the layers, or by a ‘two mode’ behaviour as previously observed in other types of mixed crystals. Moreover, local vibrational modes are observed.     

Chimie organométallique du niobium VIII. Etude détaillée de la réaction d'acétyléniques perfluorés avec (η5C5H5)2NbH3: Mise en evídence de la coupure de liaison C-F,de la formation de liaison Nb-F et de la reduction du niobium. Structure cristalline d'un dérivé niobiacyclopentadiène

Hexafluorobutyne (CF₃CCCF₃ = Hfb) reacts with Cp₂NbH₃ (Cp = η⁵-C₅H₅) affording five new complexes I–V, whose structures have been studied by mass,

Ir, ESR and NMR spectroscopy. The X-ray study of II shows the presence of a planar NbC₄ ring Nb—C(1): 2.25(5); C(1)—C(2): 1.31(7); C(2)—C(3): 1.53(8); C(3)—(4): 1.34(7); C(4)—Nb: 2.23(5) Å. With trifluoropropyne (CF₃CCH = tfp), only the analog of III, i.e. Cp₂NbFf(tfpH), has been isolated.     

High-resolution gamma-ray radiography produced by a laser-plasma driven electron source

An electron beam from a laser-plasma accelerator is converted into a gamma-ray source using bremsstrahlung radiation in a dense material. The gamma-ray beam has a pointlike source size because it is generated by a high quality electron beam with a small source size and a low divergence. Using this gamma-ray source, the radiography of complex and dense objects with submillimeter resolution is performed. It is the first evidence of a gamma-ray source size of a few hundreds micrometers produced with laser-driven accelerators. This size is consistent with results from Monte Carlo simulations.     

Planarized star-shaped oligothiophenes with enhanced pi-electron delocalization

[structure: see text] Planarized star-shaped oligothiophenes 1 have been synthesized by connecting short-chain oligothiophenes on a benzo[1,2-b:3,4-b':5,6-b' ']trithiophene central core. Their electrochemical and optical properties have been characterized by cyclic voltammetry and UV-visible spectroscopy, respectively. These results associated with theoretical calculations show the advantage of benzotrithiophene as a central core in terms of pi-electron delocalization.     

Synthesis and photochemical properties of novel pentamethylated norbornadiene containing polyimides

A novel pentamethylated norbornadiene (NBD) based dianhydride, α,α′‐bis‐(3,4,5,6,7‐pentamethylcyclopenta‐2,4‐dienyl)meta‐xylene‐1,2‐dianhydride (3), was prepared from α,α′‐bis‐(pentamethylcyclopentadienyl)meta‐xylene (1) and acetylene dicarboxylic acid. The bis‐adduct formed via Diels–Alder reaction afforded tetra‐acid (2), which was chemically cyclodehydrated to lead the targeted dianhydride (3). New polyimides containing NBD moieties in the main chain were prepared from the dianhydride monomer (3) and various aromatic diamines. The chemical structure of the polymers was confirmed by both ¹H and ¹³C NMR analysis. Their Molecular weights were also measured by SEC. All of these polyimides are soluble at room temperature in common organic solvents, such as chloroform, dichloromethane, THF, DMSO, DMF, and NMP, and show good thermal stabilities. The photochemical isomerization of the NBD into quadricyclane (QC) was investigated by UV/vis spectrophotometry from polymer films using visible sunlight as irradiation source. It was found that the kinetic rate of the conversion NBD‐QC which proceeded smoothly is a first kinetic order. The stored energies released by the transformation of QC groups into NBD ones of the irradiated polymer films were also evaluated by DSC measurement and were found to be around 90 kJ mol^?1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Time-harmonic acoustic propagation in the presence of a shear flow

This work deals with the numerical simulation, by means of a finite element method, of the time-harmonic propagation of acoustic waves in a moving fluid, using the Galbrun equation instead of the classical linearized Euler equations. This work extends a previous study in the case of a uniform flow to the case of a shear flow. The additional difficulty comes from the interaction between the propagation of acoustic waves and the convection of vortices by the fluid. We have developed a numerical method based on the regularization of the equation which takes these two phenomena into account. Since it leads to a partially full matrix, we use an iterative algorithm to solve the linear system.