LocalSolver 1.x: a black-box local-search solver for 0-1 programming

This paper introduces LocalSolver 1.x, a black-box local-search solver for general 0-1 programming. This software allows OR practitioners to focus on the modeling of the problem using a simple formalism, and then to defer its actual resolution to a solver based on efficient and reliable local-search techniques. Started in 2007, the goal of the LocalSolver project is to offer a model-and-run approach to combinatorial optimization problems which are out of reach of existing black-box tree-search solvers (integer or constraint programming). Having outlined the modeling formalism and the main technical features behind LocalSolver, its effectiveness is demonstrated through an extensive computational study. The version 1.1 of LocalSolver can be freely downloaded at and used for educational, research, or commercial purposes.     

Effect of laser beam incidence angle on the thermoelastic generation in semi-transparent materials

When a laser beam is absorbed in a semi-transparent material, a volume acoustic source is created owing to penetration of the laser beam inside the material and to thermoelastic transduction. Many experimental and theoretical studies have been conducted to better understand this ultrasound generation process with normal laser light incidence on the material surface. The purpose of this paper is to analyze the effects of the asymmetry caused by oblique incidence of a laser line source on the generation of acoustic waves in semi-transparent isotropic materials. Experiments on a glass plate demonstrate that such an obliquely incident laser light strongly affects bulk acoustic waves generation. Compressional and shear waves are enhanced and the loss of symmetry of the acoustic source causes asymmetrical behavior of the acoustic waves. Surprisingly, compressional-wave amplitude decreases whereas shear-wave amplitude increases in the region where the electromagnetic energy is refracted. This feature is explained by semi-analytical calculations.     

A holomorphic and background independent partition function for matrix models and topological strings

We study various properties of a nonperturbative partition function which can be associated with any spectral curve. When the spectral curve arises from a matrix model, this nonperturbative partition function is given by a sum of matrix integrals over all possible filling fractions, and includes all the multi-instanton corrections to the perturbative 1/N$1/N$ expansion. We show that the nonperturbative partition function, which is manifestly holomorphic, is also modular and background independent: it transforms as the partition function of a twisted fermion on the spectral curve. Therefore, modularity is restored by nonperturbative corrections. We also show that this nonperturbative partition function obeys the Hirota equation and provides a natural nonperturbative completion for topological string theory on local Calabi–Yau 3-folds.     

Stationary holomorphic discs and finite jet determination problems

We construct a family of small analytic discs attached to Levi non-degenerate hypersurfaces in $\mathbb{C }^{n+1}$ , which is globally biholomorphically invariant. We then apply this technique to study unique determination problems along Levi non-degenerate hypersurfaces that are merely of class $\mathcal{C }^4$ . This method gives 2-jet determination results for germs of biholomorphisms, CR diffeomorphisms, as well as in the almost complex setting.     

On heterogeneous latent class models with applications to the analysis of rating scores

Discovering the preferences and the behaviour of consumers is a key challenge in marketing. Information about such topics can be gathered through surveys in which the respondents must assign a score to a number of items. A strategy based on different latent class models can be used to analyze such data and achieve this objective: it consists in identifying groups of consumers whose response patterns are similar and characterizing them in terms of preferences and covariates. The basic latent class model can be extended by including covariates to model differences in (1) latent class probabilities and (2) conditional probabilities. A strategy for fitting and choosing a suitable model among them is proposed taking into account identifiability issues, the identification of potential covariates and the checking of goodness-of-fit. The tools to perform this analysis are implemented in the R package covLCA available from CRAN. We illustrate and explain the application of this strategy using data about the preferences of Belgian households for supermarkets.     

Thermal and optical behaviour of octa-alkoxy substituted phthalocyaninatovanadyl complexes

This paper deals with the synthesis of vanadyl phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions. The alkoxy chain length was varied, and octa-octyloxy (C₈H₁₇O), octa-dodecyloxy (C₁₂H₂₅O) and octa-hexadecyloxy (C₁₆H₃₃O) substituted vanadyl phthalocyanine complexes were prepared. Studies by polarizing optical microscopy and small angle X-ray diffraction (XRD) revealed that all the complexes are liquid crystalline and that these metallomesogens exhibit a columnar phase. The symmetry of the 2D lattice is rectangular, with a ^c2^mm space group, as determined by the indexation of the XRD reflections; hence a rectangular columnar phase (Colr) was assigned. A double periodicity, although weak, along the axis of the columns was found, which indicates some degree of pairing or dimerization. A tentative explanation based on an antiferroelectric stacking is given. Transition enthalpies were determined by differential scanning calorimetry. The compounds start to decompose above 250°C before reaching the clearing temperatures. A significant bathochromic shift of the Q-band in the UV/Vis spectra of the vanadyl complexes compared with the metal-free ligands and other metallophthalocyanines (M=Co^II, Ni^II, Cu^II, Zn^II) was also observed.