Application Des Réseaux de Neurones Avec la Régularisation Bayésienne pour la Modélisation de la Synthèse de l’hydroxyapatite Élaborée à Partir du Carbonate de Calcium et de L’acide Phosphorique

We have used a new, robust model mapping technique—a Bayesian-regularized neural network—to develop a quantitative relationships model for the synthesis of the phosphocalcic hydroxyapatite by precipitation from a calcium carbonate solution and a phosphoric acid solution. This model was preformed by using a set of factors consisting on the pH of reactional medium, the Ca/P molar ratio of the reagents, reaction time, and the initial concentration of calcium. The results show that the method is robust and gives satisfied results. The Levenberg–Marquardt's algorithm implemented in the neural network Matlab's toolbox allowed a drastic improvement of the performance of the model. Very satisfactory results are then obtained by testing the validity by cross-validation technique.

We have also turned our interests to the explanatory capacities of our methodology to explore the relative contribution and/or the contribution profile of the input factors by using Garson weight portioning method.     

Double-clad fiber laser design for particle image velocimetry and material science applications

We have developed models to design actively Q-switched Yb-doped Double-Clad fiber lasers in various configurations. Based on these simulations, we present the design of two specific cavities: the first one is able to emit a pair of sub-nanosecond pulses separated by more than 500 ns for Particle Imagery Velocimetry applications. The time delay between the pulses can be adjusted by proper choice of the length of an un-doped fiber inserted in the cavity. The second cavity designed allows to emit long 150 ns pulses exceeding a few millijoules per pulse. Applications concern in this case materials science and combustion. In all cases, the rise time of the EOM is an essential parameter.     

Preparation and Characterization of [Zn(H2O)6][Zn2V10O28(H2O)10]?·?6H2O Single Crystals with a Novel Metallic Heteropolyoxoanion

Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra. The Zn(1)O₆ octahedron and three water molecules associated with it are located between the different layers. The [Zn(H₂O)₆][Zn₂V₁₀O₂₈(H₂O)₁₀] · 6H₂O compound belongs to P-1 space group, with a = 8.967(2) ?, b = 10.390(4) ?, c = 12.338(13) ?, α = 108.31(7)°, β = 100.68(7)°, γ = 103.00(3)°, V = 1022(1) ?³ and Z = 1. Refinement gave R = 0.035 and wR(F²) = 0.098 for 3837 unique observed reflexions [I > 2σ(I)]. Index Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra.      

The novel arsenate Na4Co7−xAl2/3x(AsO4)6 (x = 1.37): crystal structure,charge‐distribution and bond‐valence‐sum investigations

The title compound, tetrasodium cobalt aluminium hexaarsenate, Na₄Co_7−xAl_2/3x(AsO₄)₆ (x = 1.37), is isostructural with K₄Ni₇(AsO₄)₆; however, in its crystal structure, some of the Co²⁺ ions are substituted by Al³⁺ in a fully occupied octahedral site (site symmetry 2/m) and a partially occupied tetrahedral site (site symmetry 2). A third octahedral site is fully occupied by Co²⁺ ions only. One of the two independent tetrahedral As atoms and two of its attached O atoms reside on a mirror plane, as do two of the three independent Na⁺ cations, all of which are present at half‐occupancy. The proposed structural model based on a careful investigation of the crystal data is supported by charge‐distribution (CHARDI) analysis and bond‐valence‐sum (BVS) calculations. The correlation between the X‐ray refinement and the validation results is discussed.     

New method to obtain the acute sill of an ecological model with complex polynomial perturbation

This research aims to highlight and examine an example of ecological complexity. By taking into account the interference between predator and prey, we introduce an ecological system with a general functional response. This model is perturbed by a novel class of fluctuations in the polynomial form. Analytically, we present an alternative method to obtain the acute threshold between stationarity and predator disappearance. Our analysis enriches and improves the work of Zhou et al. (2021) by unifying the criteria of said asymptotic characteristics. Numerically, we audit the accuracy of our threshold in three particular situations: linear, quadratic and cubic perturbations. We establish that the increasing order of disturbance has a passive influence on the extinction time of predators. This finding highlights that complex noise sources have a positive role in the transient dynamics of ecological systems.