Search results for "Refinement"
showing 10 items of 114 documents
Effect of TiO2 on the mullite formation and mechanical properties of alumina porcelain
2010
Abstract The effect of adding TiO 2 to standard alumina porcelain on its microstructure and flexural strength was investigated. A series of alumina porcelain bodies containing increasing amounts of TiO 2 were prepared by extruding mixtures of raw materials and TiO 2 . Porcelain rods were fired under industrial scheduling in a manufacturing kiln. The overall degree of crystalline and amorphous phase content within the porcelain bodies was quantitatively determined using a Rietveld analysis. Results indicated a higher amount of mullite formation in porcelain bodies containing TiO 2 . Examination of the product materials using field emission scanning electron microscopy showed a high density o…
IM-17: a new zeolitic material, synthesis and structure elucidation from electron diffraction ADT data and Rietveld analysis
2014
International audience; The synthesis and the structure of IM-17, a new germanosilicate with a novel zeolitic topology, prepared hydrothermally with decamethonium as the organic structure directing agent, are reported. The structure of calcined and partially rehydrated IM-17 of chemical formula per unit cell |(H2O)14.4|[Si136.50Ge39.50O352] was solved ab initio using electron diffraction ADT data in the acentric Amm2 (setting Cm2m) space group and refined by the Rietveld method. This new zeolite framework type contains a 3D pore system made of intersecting 12, 10 and 8-ring channels.
Effects of redox treatments on the structural composition of a ceria–zirconia oxide for application in the three-way catalysis
2003
Abstract The influence of calcination and redox cycles on the structural modification and redox properties of a ceria–zirconia mixed oxide of nominal composition Ce 0.6 Zr 0.4 O 2 were investigated by XRD and Rietveld refinement, by BET measurement, TPR and OSC analyses. The material is characterized by high total OSC and retains this property after several redox and calcination cycles up to 1273 K, despite the loss of porosity and the decrease of surface area. The Rietveld analysis of the diffractograms allowed to establish that at least two solid solutions are present in the as-prepared sample: a cubic phase, space group Fm-3m, richer in cerium compared to the nominal composition, a tetra…
An alternative space-time meshless method for solving transient heat transfer problems with high discontinuous moving sources
2016
International audience; The aim of this work is the development of a space-time diffuse approximation meshless method (DAM) to solve heat equations containing discontinuous sources. This work is devoted to transient heat transfer problems with static and moving heat sources applied on a metallic plate and whose power presents temporal discontinuities. The space-time DAM using classical weight function is convenient for continuous transient heat transfer. Nevertheless, for problems including discontinuities, some spurious oscillations for the temperature field occur. A new weight function, respecting the principle of causality, is used to eradicate the physically unexpected oscillations.
PROFILE REFINEMENT IN ONTOLOGY-BASED RECOMMANDER SYSTEMS FOR ECONOMICAL E-NEWS
2014
International audience; This paper is interested in a recommender system of economic news articles. More precisely, it focuses on automatic profile refinement of customers which is an important task over time by taken into account logs of the user concerning especially his/her actions, reading time, and domain specific knowledge. In our approach, ontologies are used to describe and automatically refine these profiles. This work focuses on one particular type of recommender systems which is content-based recommenders. The aim of these recommender systems is to build a user profile and to improve its precision over time. Several improvements that have been made to these recommender systems ov…
Reliable numerical solution of a class of nonlinear elliptic problems generated by the Poisson-Boltzmann equation
2020
We consider a class of nonlinear elliptic problems associated with models in biophysics, which are described by the Poisson-Boltzmann equation (PBE). We prove mathematical correctness of the problem, study a suitable class of approximations, and deduce guaranteed and fully computable bounds of approximation errors. The latter goal is achieved by means of the approach suggested in [S. Repin, A posteriori error estimation for variational problems with uniformly convex functionals. Math. Comp., 69:481-500, 2000] for convex variational problems. Moreover, we establish the error identity, which defines the error measure natural for the considered class of problems and show that it yields computa…
Fe and Zn co-substituted beta-tricalcium phosphate (β-TCP): Synthesis, structural, magnetic, mechanical and biological properties
2020
This work was supported by the European Social Fund under the No. 09.3.3- LMT-K-712 “Development of Competences of Scientists, other Researchers and Students through Practical Research Activities” measure. AK would like to express sincere gratitude for Fellowship administrated by The Japan Society for the Promotion of Science (JSPS). Fellow’s ID No.: L12546. Authors are grateful to R. Vargalis (Vilnius University) for taking SEM images. © 2020. This work is licensed under a CC BY-NC-ND license.
The Truth is Out There : Focusing on Smaller to Guess Bigger in Image Classification
2023
In Artificial Intelligence (AI) in general and in Machine Learning (ML) in particular, which are important and integral components of modern Industry 4.0, we often deal with uncertainty, e.g., lack of complete information about the objects we are classifying, recognizing, diagnosing, etc. Traditionally, uncertainty is considered to be a problem especially in the responsible use of AI and ML tools in the smart manufacturing domain. However, in this study, we aim not to fight with but rather to benefit from the uncertainty to improve the classification performance in supervised ML. Our objective is a kind of uncertainty-driven technique to improve the performance of Convolutional Neural Netwo…
A coupled discontinuous Galerkin-Finite Volume framework for solving gas dynamics over embedded geometries
2021
Author(s): Gulizzi, Vincenzo; Almgren, Ann S; Bell, John B | Abstract: We present a computational framework for solving the equations of inviscid gas dynamics using structured grids with embedded geometries. The novelty of the proposed approach is the use of high-order discontinuous Galerkin (dG) schemes and a shock-capturing Finite Volume (FV) scheme coupled via an $hp$ adaptive mesh refinement ($hp$-AMR) strategy that offers high-order accurate resolution of the embedded geometries. The $hp$-AMR strategy is based on a multi-level block-structured domain partition in which each level is represented by block-structured Cartesian grids and the embedded geometry is represented implicitly by a…
Functional a posteriori error estimates for boundary element methods
2019
Functional error estimates are well-established tools for a posteriori error estimation and related adaptive mesh-refinement for the finite element method (FEM). The present work proposes a first functional error estimate for the boundary element method (BEM). One key feature is that the derived error estimates are independent of the BEM discretization and provide guaranteed lower and upper bounds for the unknown error. In particular, our analysis covers Galerkin BEM and the collocation method, what makes the approach of particular interest for scientific computations and engineering applications. Numerical experiments for the Laplace problem confirm the theoretical results.