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Contribution of different granulometric populations to powder reactivity

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Particuology 2009年第1期7卷 39-44页

作者： Jean-Charles Benezet Ali Benhassaine ecole des mines d’Alès 6 Avenue de Clavieres 30319 ALES CedexFrance ecole des mines d’Alès 6 Avenue de Clavieres 30319 ALES CedexFrance

In this article, different population contributions of quartz powders to chemical reactivity in pozzolanic reaction were studied. deconvolution software was used to show the different particle populations of each product. Reaction of quartz powder with lime in the pozzolanic reaction at 20 ℃ shows that reactivity of each powder population depends on its particle size. Adsorbed fine particles on coarse particle surfaces have a significant role in the first term of the reaction. In a second term, the micropowders react. The mesopowders react only in the last reaction terms. Until now, the reactivity of adsorbed powder has been attributed to amorphization of the particle surface.

关键词： Quartz population Reaction rate Curve deconvolution Powder granulometry Specific surface area

2-Dimensional FEM modeling of macrosegregation in the directional solidification with mesh adaptation

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Acta Metallurgica Sinica(English Letters) 2009年第3期22卷 233-240页

作者： Weitao LIU Changchuan XIE Michel Bellet Hervé Combeau Beijing Metallurgical Technology Research Institute CCTEC Engineering Corporation Limited Beijing 100081 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China ecole des mines de paris Sophia Antipolis 06904 France and Ecole des Mines de Nancy Nancy 54042France

In order to improve the prediction accuracy of macrosegregation channel, an algorithm for dynamic remeshing is proposed. The basic idea is to generate fine elements near the liquidus isotherm. The norm of the gradient of solid fraction is used for piloting the remeshing in the mushy zone; whereas, the objective mesh size in the liquid is considered as a function of the distance to the liquidus isotherm. The efficiency of mesh adaptation is demonstrated by prediction of macrosegregation channel in a case of unidirectional solidification.

关键词： Freckle Solidification Modeling Adaptive remeshing

Relation between silico-aluminous fly ash and its coal of origin

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Particuology 2008年第2期6卷 85-92页

作者： Jean-Charles Benezet Pierre Adamiec Ali Benhassaine ecole des mines d'Alès 6 Avenue de Clavieres30319 ALES CedexFrance

Fly ashes are typical complex solids which incorporate at the same time intrinsic properties derived from the layers （various mineralogical and dimensional spectra） and major transformations generated during prior processing. To use fly ashes in various applications, it is necessary to characterise them completely. The first research to date carried out on silico-aluminous fly ashes in order to characterise them physically, morphologically, chemically and mineralogically, resulted in the recognition that they are relatively simple materials. In the present study, a silico-aluminous fly ash coming from the power station of Albi （France） was selected. Heat treatment at 450 and 1200℃ together with coal simulated the treatment undergone by coal in the power station in order to mimic real coal residue. In conclusion, the diversity of the particles contained in fly ash could only be exolained by the relation existing between the fly ash and its coal of origin.

关键词： Fly ash Selection Thermal treatment

Pozzolanic reactivity of silico-aluminous fly ash

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Particuology 2008年第2期6卷 93-98页

作者： Pierre Adamiec Jean-Charles Benezet Ali Benhassaine ecole des mines d'Alès 6 Avenue de Clavières30319 ALES CedexFrance

For some years it has been possible to control the particle size of fly ashes, by-products of thermal power stations. Incorporating these very fine particles （obtained by grinding and/or pneumatic selection） improves the physical-mechanical characteristics of mortars and concretes. In this study, we measured the lime consumption of the various fractions （granulometric and densimetric） and identified by X-ray diffraction the neoformed phases by the pozzolanic reaction, to show that it is not sufficient to simply define the pozzolanicity of products based on lime consumption since it does not take into account the nature of the phases formed. The size of the particles used in the test samples also has a determining effect on the quantity of lime consumed. Before comparing results, it is necessary to ensure that the size of the particles （of the global ash and its constituents） be the same. Two distinct neoformed ohases appear： CSH in the largest granular fractions （d〉 40 μm） and C3AH6 in the smaller fractions.

关键词： Fly ash Pozzolanic reaction Particle size

Characterization and Photoluminescence Properties of Alumina Nanowires Elaborated by Arc-Plasma

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Journal of Materials Science & Technology 2006年第1期22卷 127-129页

作者： C.Arnoult X.devaux H.Rinnert M.Vergnat Laboratoire de Physique des Materiaux UMR CNRS 7556Ecole des MinesCS14234F54042 Nancy cedexPrance

Ultrafine powders containing alumina nanowires are synthesized by DC arc plasma from pure aluminium metal. Nanowires grow only when reactive gases are composed of nitrogen and less than ten percent of oxygen. Nanowires have the diameters ranging from 20 to 80 nm and lengths ranging from hundreds nanometers to tens of micrometers. A first assumption of the mechanism process is proposed, in which nanowires grow starting directly from the aluminium. Photoluminescence measurements show that the powders have three emission peaks around 435, 530 and 750 nm resulting from different kinds of defects such as oxygen vacancies, aluminium interstitial ions and surface defects.

关键词： Nanowires Alumina Arc plasma Photoluminescence

Reevaluating health metrics:Unraveling the limitations of disabilityadjusted life years as an indicator in disease burden assessment

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World Journal of Methodology 2025年第1期15卷 14-19页

作者： Ariel Beresniak Dominique Bremond-Gignac Danielle Dupont Gerard Duru Data Mining International Geneva 1216Switzerland department of Ophtalmology Necker-Enfants Malades University HospitalAP-HPParis-CitéUniversityINSERMUMRS1138Team 17From Physiopathology of Ocular Diseases to Clinical DevelopmentSorbonne Paris CitéUniversityCentre de Recherche des CordeliersParis 75015France Data Mining America Montreal H2YCanada

In 1993,the World Bank released a global report on the efficacy of health promotion,introducing the disability-adjusted life years(DALY)as a novel *** DALY,a composite metric incorporating temporal and qualitative data,is grounded in preferences regarding disability *** review delineates the algorithm used to calculate the value of the proposed DALY synthetic indicator and elucidates key methodological challenges associated with its *** contrast to the quality-adjusted life years approach,derived from multi-attribute utility theory,the DALY stands as an independent synthetic indicator that adopts the assumptions of the Time Trade Off utility technique to define Disability *** to rely on no mathematical or economic theory,DALY users appear to have exempted themselves from verifying whether this indicator meets the classical properties required of all indicators,notably content validity,reliability,specificity,and *** DALY concept emerged primarily to facilitate comparisons of the health impacts of various diseases globally within the framework of the Global Burden of Disease initiative,leading to numerous publications in international *** widespread adoption,the DALY synthetic indicator has prompted significant methodological concerns since its inception,manifesting in inconsistent and non-reproducible *** the substantial diffusion of the DALY indicator and its critical role in health impact assessments,a reassessment is *** reconsideration is imperative for enhancing the robustness and reliability of public health decisionmaking processes.

关键词： Disability adjusted life years Cost-utility analyses Outcome research Public health Burden of disease

A Linear Quadratic Controller design Incorporating a Parametric Sensitivity Constraint

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International Journal of Automation and computing 2019年第4期16卷 553-562页

作者： Mohamed Yagoubi LUNAM University Ecole des Mines de Nantes IRCCyN UMR CNRS 6597(Institut de Recherche en Communications et Cyberntique de Nantes)

The purpose of this paper is to propose a synthesis method of parametric sensitivity constrained linear quadratic (SCLQ) controller for an uncertain linear time invariant (LTI) system. System sensitivity to parameter variation is handled through an additional quadratic trajectory parametric sensitivity term in the standard LQ criterion to be minimized. The main purpose here is to find a suboptimal linear quadratic control taking explicitly into account the parametric uncertainties. The paper main contribution is threefold: 1) A descriptor system approach is used to show that the underlying singular linear-quadratic optimal control problem leads to a non-standard Riccati equation. 2) A solution to the proposed control problem is then given based on a connection to the so-called Lur'e matrix equations. 3) A synthesis method of multiple parametric SCLQ controllers is proposed to cover the whole parametric uncertainty while degrading as less as possible the intrinsic robustness properties of each local linear quadratic controller. Some examples are presented in order to illustrate the effectiveness of the approach.

关键词： Linear quadratic control parametric uncertainties trajectory sensitivity non-standard Riccati equation Lur'e matrix equations linear time invariant (LMI) particle swarm optimization

Controlled acceleration of GeV electron beams in an all-optical plasma waveguide

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Light(Science & Applications) 2022年第7期11卷 1535-1541页

作者： Kosta Oubrerie Adrien Leblanc Olena Kononenko Ronan Lahaye Igor A.Andriyash Julien Gautier Jean-Philippe Goddet Lorenzo Martelli Amar TafziKim Ta Phuoc Slava Smartsev Cédric Thaury LOA CNRSEcole PolytechniqueENSTA ParisInstitut Polytechnique de Paris181 Chemin de la Hunière et des Joncherettes91120 PalaiseauFrance

Laser-plasma accelerators(LPAs)produce electric fields of the order of 100 GV m-1,more than 1000 times larger than those produced by radio-frequency *** uniquely strong fields make LPAs a promising path to generate electron beams beyond the TeV,an important goal in high-energy ***,large electric fields are of little benefit if they are not maintained over a long *** is therefore of the utmost importance to guide the ultra-intense laser pulse that drives the *** very high energies is equally useless if the properties of the electron beam change completely from shot to shot,due to the intrinsic lack of stability of the injection ***-of-the-art laser-plasma accelerators can already address guiding and control challenges separately by tweaking the plasma ***,the production of beams that are simultaneously high quality and high energy has yet to be *** paper presents a novel experiment,coupling laser-plasma waveguides and controlled injection techniques,facilitating the reliable and efficient acceleration of high-quality electron beams up to 1.1 GeV,from a 50 TW-class laser.

关键词： process. acceleration uniquely

GENERALIZATION OF THE INTERACTION BETWEEN HAAR APPROXIMATION AND POLYNOMIAL OPERATORS TO HIGHER ORdeR METHODS

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Analysis in Theory and Applications 2006年第4期22卷 301-318页

作者： Fran ois Chaplais école Nationale Supérieure des mines de paris France

In applications it is useful to compute the local average empirical statistics on u. A very simple relation exists when of a function f（u） of an input u from the local averages are given by a Haar approximation. The question is to know if it holds for higher order approximation methods. To do so, it is necessary to use approximate product operators defined over linear approximation spaces. These products are characterized by a Strang and Fix like condition. An explicit construction of these product operators is exhibited for piecewise polynomial functions, using Hermite interpolation. The averaging relation which holds for the Haar approximation is then recovered when the product is defined by a two point Hermite interpolation.

关键词： Strang and Fix conditions product approximation Hermite interpolation wavelets