Computing efficiently the lattice width in any dimension

We provide an algorithm for the exact computation of the lattice width of a set of points K in Z² in linear-time with respect to the size of K. This method consists in computing a particular surrounding polygon. From this polygon, we deduce a set of candidate vectors allowing the computation of the lattice width. Moreover, we describe how this new algorithm can be extended to an arbitrary dimension thanks to a greedy and practical approach to compute a surrounding polytope. Indeed, this last computation is very efficient in practice as it processes only a few linear time iterations whatever the size of the set of points. Hence, it avoids complex geometric processings.     

Machine learning to design full-reference image quality assessment algorithm

A crucial step in image compression is the evaluation of its performance, and more precisely, available ways to measure the quality of compressed images. In this paper, a machine learning expert, providing a quality score is proposed. This quality measure is based on a learned classification process in order to respect human observers. The proposed method namely Machine Learning-based Image Quality Measure (MLIQM) first classifies the quality using multi-Support Vector Machine (SVM) classification according to the quality scale recommended by the ITU. This quality scale contains 5 ranks ordered from 1 (the worst quality) to 5 (the best quality). To evaluate the quality of images, a feature vector containing visual attributes describing images content is constructed. Then, a classification process is performed to provide the final quality class of the considered image. Finally, once a quality class is associated to the considered image, a specific SVM regression is performed to score its quality. Obtained results are compared to the one obtained applying classical Full-Reference Image Quality Assessment (FR-IQA) algorithms to judge the efficiency of the proposed method.     

Optical Waveguides Fabricated from Oxidised Porous Silicon

Further results on the optical properties of oxidised porous silicon as a function of porosity and oxidation conditions are presented in this paper. The refractive index varies logarithmically with the oxidation time irrespective of the porosity of the sample and the oxidation temperature. Burried waveguides have been realised from as-prepared and oxidised porous silicon. Optical losses of 18 dB cm^–1 at = 1.3 m have been obtained after oxidation at 800°C for 35 min.     

Certain effects of melt-shearing and cooling on the stress-strain behavior of thermoplastic elastomers

The peculiar behavior of thermoplastic elastomers in molding suggested that the processing steps (mainly shearing) to which the material had been submitted had a great influence on the morphology. Experiments were carried out on two polysstyrene-polybutadiene-polystyrene elastomers. The effects of melt-shearing and cooling were examined both by mechanical testing and low angle X-ray scattering. Melt-shearing creates a marked morphological anisotropy but a form of annealing can occur at sufficiently high temperatures.     

An HLLC Scheme to Solve The <Emphasis Type="Italic">M</Emphasis><Subscript>1</Subscript> Model of Radiative Transfer in Two Space Dimensions

The M ₁ radiative transfer model is considered in the present work in order to simulate the radiative fields and their interactions with the matter. The model is governed by an hyperbolic system of conservation laws supplemented by relaxation source terms. Several difficulties arise when approximating the solutions of the model; namely the positiveness of the energy, the flux limitation and and the limit diffusion behavior have to be satisfied. An HLLC scheme is exhibited and it is shown to satisfy all the required properties. A particular attention is payed concerning the approximate extreme waves. These approximations are crucial to obtain an accurate scheme. The extension to the full 2D problem is proposed. It satisfies, once again, all the expected properties. Numerical experiments are proposed. They show that the considered scheme is actually less diffusive than the currently used numerical methods.      

Identification of constitutive model for rubber elasticity from micro-indentation tests on natural rubber and validation by macroscopic tests

Micro-hardness testing is widely used to measure the materials local response and is very valuable to describe gradients of physical properties. For polymers, the most common use is to measure a scalar value (hardness or modulus), which gives access to useful qualitative information but can clearly not be used to identify local constitutive models, strongly needed to achieve the numerical simulation of heterogeneous massive parts. In this study, load/displacement curves obtained at a micro-scale are used to identify the parameters of an Edwards-Vilgis hyperelastic model. The protocol proposed is coupling FE simulations achieved with Abaqus and optimization procedures using the dedicated software Boss Quattro. In order to limit the microstructure and viscous effects, the material studied is an unfilled natural rubber which exhibits a behavior very close to perfect hyperelasticity. Several numerical parameters (indent geometry, friction, thickness, …) as well as experimental protocols were tested in order to check the protocol reliability. The identified parameters are used to simulate macroscopic tests (tensile, compression and pure shear tests). The agreement with experimental data is very good, which is rarely found in the literature and which validates several numerical assumptions.     

Allelotype influence at glutathione S-transferase M1 locus on breast cancer susceptibility

PURPOSE: To compare development of visual acuity and binocular vision in preterm and full-term infants in a prospective study that used testers masked to subject's gestational age. METHODS: Seventy-nine healthy full-term infants, mean gestational age 40 weeks, and 18 low-risk preterm infants, mean gestational age 33 weeks, were examined biweekly between the 44th and 54th weeks of postmenstrual age. Ocular alignment, convergence, fusion, grating acuity, and onset of optokinetic nystagmus (OKN) were assessed at each examination. RESULTS: The mean postnatal ages of onset of ocular alignment, convergence, fusion, grating acuity to 1.6 cycles per degree, and OKN from temporal to nasal and nasal to temporal were, respectively, 5, 7, 7, 11, 6, and 9 weeks for the full-term and 12, 13, 14, 18, 13, and 16 weeks for the preterm infants. The mean postmenstrual ages of onset for the corresponding parameters were 46, 48, 48, 51, 46, and 50 weeks for full-term and 46, 47, 48, 52, 47, and 49 weeks for preterm infants. The onset of all parameters was earlier in full-term infants than in preterm infants of the same postnatal age (P < or = 0.0001). However, no differences were found when the parameters were compared at postmenstrual ages. CONCLUSIONS: Additional visual experience of preterm infants does not influence development of visual acuity or binocular vision during the first months of life as measured from the time of conception.     

Electroless oxidation of diamond surfaces in ceric and ferricyanide solutions: An easy way to produce “C-O” functional groups

Despite many works are devoted to oxidation of diamond surfaces, it is still a challenge, to successfully produce well defined “C-O” functions, particularly for functionalization purposes. In this paper we describe and compare, for the first time, the “electroless” oxidation of as-deposited polycrystalline boron-doped diamond (BDD) films in ceric and ferricyanide solutions at room temperature. Both reactions efficiently generate oxygen functionalities on BDD surface. While a higher amount of “C-O” moieties is produced with Ce⁴⁺ as oxidizing agent, the use of ferricyanide specie seems the most interesting to specifically generate hydroxyl groups. Additionally, this easy to perform oxidative method appears not damaging for diamond surfaces and adapted to conductive or non-conductive materials. The resulting surfaces were characterized using X-ray photoelectron spectroscopy, contact angle and capacitance-voltage analysis.     

Color stability of heat-treated wood during artificial weathering

The color change of wood after exposure to UV light may produce aesthetical damages. The stability of the color to light exposure is an important issue. This study describes experiments of testing the color stability of heat-treated wood samples. Heat treatment was done at 240°C during 2 hours, under nitrogen. Heat-treated samples of ash, beech, maritime pine and poplar heartwood were exposed to UV-light (QUV equipped with fluorescent lamps UVA-340) during 835 hours. Color measurements during accelerated weathering were made at intervals throughout the test period. The results are presented in ΔE and L* a* b* coordinates according to the CIELab system. The experiments show that the color stability for heat-treated wood is better during the 835 hours of exposure when compared to untreated wood. The properties of heat treated wood (lignin modifications, and monomers of phenolic compounds) are probably involved in the retified wood resistance against UV light under experimental conditions.     

Nitrogenation of boron doped diamond: Comparison of an electrochemical treatment in liquid ammonia and a NH3/N2 plasma

In the present work, two different nitrogenation of diamond surface were studied onto moderately doped BDD samples (10¹⁹ at cm^? 3). The effects of an electrochemical treatment in liquid ammonia have been compared to those produced by NH₃/N₂ plasma. The evolution of surface terminations from “CH” to “CN” has been studied by XPS analyses for both nitrogenation methods. Angle contact measurements complete this work, estimating the effect of such treatments on BDD wettability properties. Finally, cyclic voltammetry in presence of redox systems have been carried out to evidence the impact of “CN” bonds on BDD electrochemical behavior. In both cases the formation of “CN” terminations was evidenced by XPS analyses. Physico-chemical properties of BDD electrodes, deduced from contact angle and electrochemical measurements, were strongly modified according the process. The galvanostatic treatment in liquid ammonia led to a more hydrophobic diamond surface and an improvement of the charge transfer with Ce^4+/3+ redox couple, while a more hydrophilic surface and a notable decrease of the electrochemical response were generated by NH₃/N₂ plasma treatment.