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Affichage de 31 à 40 sur 1060

  • Article dans une revue

Estimation of the asymptotic variance matrix of the least squares estimator of weak FARIMA models

Yacouba Boubacar Mainassara, Youssef Esstafa

In this article, we propose a consistent estimator for the asymptotic variance matrix of the least squares estimator in Fractionally AutoRegressive Integrated Moving‐Average (FARIMA) models. Our approach allows for error terms that are uncorrelated, but not necessarily independent. Modified…

Statistica Neerlandica, 2025, 79 (3), ⟨10.1111/stan.70009⟩. ⟨hal-05531048⟩

  • Article dans une revue

Hydrothermal Synthesis and Structural Characterization of a New Lead Tri-magnesium Phosphate PbMg3(HPO4)(PO4)2

Ahmed Ould Saleck, Cyrille Albert-Mercier, Claudine Follet-Houttemane, Abderrazzak Assani, Lahcen El Ammari, Mohamed Saadi

A new lead tri-magnesium phosphate PbMg3(HPO4)(PO4)2 was synthesized by hydrothermal method and characterized by single crystal X-ray diffraction.

Journal of Chemical Crystallography, 2025, 55 (4), pp.259-266. ⟨10.1007/s10870-025-01056-3⟩. ⟨hal-05538269⟩

  • Poster de conférence

Experimental and DFT study of the structural, electronic and thermoelectrical properties of Li 3x La 2/3-x TiO 3 (x=0.125) Ceramic leads free for battery applications

Hicham Kacimi-Naciri, Ahmed Bachar, Assia Mabrouk

The solid-state sintering method, aiming for its application as a solid-state electrolyte in lithium-ion batteries. The resulting material was characterized experimentally through X-ray diffraction (XRD), dielectric measurements (permittivity and loss), complex impedance analysis, and electrical…

Faculté des Sciences Appliquées - Ait Melloul, Jul 2025, AGADIR (virtuel), France. ⟨hal-05583572⟩

  • Article dans une revue

DFT-based and experimental study on Sr-doped BaTiO3: Impacts on piezoelectric and ferroelectric performance

Hicham Kacimi-Naciri, Mohamed Rguiti, Assia Mabrouk, Christian Courtois, Mohamed Aymen Ben Achour, Yannick Lorgouilloux, Rachid Amrousse, Nadia Faska, Ahmed Bachar

This study combines first-principles Density Functional Theory (DFT) calculations and experimental analysis to investigate the impact of Sr-doping on the structural, electronic, and piezoelectric properties of Ba1-xSrxTiO3(BST) perovskites at different Sr concentrations (x = 0, 0.125, 0.25…

Ceramics International, 2025, 51 (17), pp.23801-23813. ⟨10.1016/j.ceramint.2025.03.069⟩. ⟨hal-05583186⟩

  • Article dans une revue

Determination of discontinuous diffusion coefficients for the heat equation on a tree-shaped network

Emmanuelle Crépeau, Lionel Rosier, Julie Valein

In this paper, we study the heat equation on a tree-shaped network with a piecewise regular diffusion coefficient. By developing new Carleman estimates, we establish stability results for the identification of the diffusion coefficient. These stability estimates are derived using either internal…

Inverse Problems, 2025, 41 (7), pp.075001. ⟨10.1088/1361-6420/ade3f9⟩. ⟨hal-05464931⟩

  • Poster de conférence

Étude par DFT de l'impact du dopage au Sr sur les propriétés structurales, électroniques, piézoélectriques et ferroélectriques du BaTiO3

Hicham Kacimi-Naciri, Mohamed Rguiti, Ahmed Bachar, Assia Mabrouk, Mohamed Aymen Ben Achour, Christian Courtois, Yannick Lorgouilloux

Les matériaux piézoélectriques sans plomb sont développés pour leurs applications variées et leur impact environnemental réduit. Les pérovskites Ba 1-x Sr x TiO 3 (BST) offrent un potentiel intéressant grâce à leur structure modulable. Cette étude examine l'effet du dopage au strontium (Sr)…

Journée Matériaux & Énergie Électrique, Jun 2025, Maubeuge, France. ⟨hal-05583575⟩

  • Article dans une revue

The Curious Spectra and Dynamics of Non-locally Finite Crystals

Joachim Kerner, Olaf Post, Mostafa Sabri, Matthias Täufer

Abstract This paper is devoted to the investigation of the spectral theory and dynamical properties of periodic graphs which are not locally finite but carry non-negative, symmetric and summable edge weights. These graphs are shown to exhibit rather intriguing behaviour: for example, we construct a…

Communications in Mathematical Physics, 2025, 406 (7), pp.169. ⟨10.1007/s00220-025-05346-x⟩. ⟨hal-05138415⟩

  • Pré-publication, Document de travail

Error Bounds for a Kernel-Based Constrained Optimal Smoothing Approximation

Laurence Grammont, François Bachoc, Andrés F. López-Lopera

This paper establishes error bounds for the convergence of a piecewise linear approximation of the constrained optimal smoothing problem posed in a reproducing kernel Hilbert space (RKHS). This problem can be reformulated as a Bayesian estimation problem involving a Gaussian process related to the…

2025. ⟨hal-04645086v2⟩

  • Article dans une revue

Thermoelastic properties of polycrystalline strontium titanium silicate Sr₂TiSi₂O₈ synthesized via the reactive sintering method

Oussama Zwein, Maurice Gonon, Sandra Abdelouhab, Isabella Mastroianni, Marc Duquennoy

The aim of the work presented in this paper is to investigate the thermoelastic properties of polycrystalline Sr-fresnoite Sr2TiSi2O8 (STS). On that purpose, Sr2TiSi2O8 samples were synthesized by solid state reactive sintering from SrCO3, TiO2 and SiO2 powders. The thermal expansion behaviour of…

Journal of the European Ceramic Society, 2025, 45 (6), pp.117224. ⟨10.1016/j.jeurceramsoc.2025.117224⟩. ⟨hal-04923467⟩

  • Thèse

Some Optimal Control Problems for Additive Manufacturing of Ceramics, Quelques problèmes de contrôle optimal pour la fabrication additive de la céramique

Hiba Hmede

Additive manufacturing using laser fusion on metal oxide powder beds, such as alumina (Al₂O₃) and aluminum titanate (Al₂TiO₅), has improved notably in recent years. This process now allows the fabrication of complex structures across various fields, particularly in physics and engineering. This…, La fabrication additive par fusion laser sur des lits de poudre d'oxyde métallique, comme l'alumine (Al₂O₃) et le titanate d'aluminium (Al₂TiO₅), s'est considérablement améliorée ces dernières années. Ce procédé permet aujourd'hui la fabrication de structures complexes dans…

Polymers. Université Polytechnique Hauts-de-France; Université Libanaise, 2025. English. ⟨NNT : 2025UPHF0011⟩. ⟨tel-05651363v2⟩