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Numerical study of the performance of multistage Scaba 6SRGT impellers for the agitation of yield stress fluids in cylindrical tanks

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Journal of Hydrodynamics 2015年第3期27卷 436-442页

作者： AMeUR Houari BOUZIT Mohamed GHeNAIM Abdellah laboratoire de Mécanique Appliquée Faculté de Génie MécaniqueUSTO-MB Institut de Technologie Université Ibn Khaldoun INSA de Strasbourg-24 Bd de la Victoire-67084 Strasbourg-France

The 3-D flow fields and power consumption in a vessel stirred by multistage Scaba 6SRGT impeller have been investiga- ted. The Xanthan gum solutions in water were used, which have a shear thinning behavior with yield stress. This study was carried out with the help of a CFD package （CFX 13.0, Ansys Inc.） which is based on the finite volume method to solve the momentum equations. The effects of stirring rate, fluid rheology, impeller number, impeller location and vessel size on the performance of such stirred system are presented. To validate the CFD model, our predicted results have been compared with other literature data and a satisfactory agreement has been found.

关键词： Scaba 6SRGT impeller multistage agitator yield stress fluid stirred tank power consumption

Molecule-based kinetic modeling by Monte Carlo methods for heavy petroleum conversion

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Science China Chemistry 2013年第11期56卷 1608-1622页

作者： de OLIVeIRA Luís Pereira VeRSTRAeTe Jan J. KOLB Max IFP energies nouvelles Rond-point de l'échangeur de Solaize-BP 369360 SolaizeFrance laboratoire de Chimie cole Normale Supérieure69364 Lyon Cedex 07France

A methodology for kinetic modeling of conversion processes is *** proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by means of a two-step *** the first step,a synthetic mixture of molecules representing the feedstock is generated via a molecular reconstruction method,termed SR-ReM molecular *** the second step,a kinetic Monte Carlo method,termed stochastic simulation algorithm(SSA),is used to simulate the effect of the conversion reactions on the mixture of *** resulting methodology is applied to the Athabasca vacuum residue *** adequate molecular representation of the vacuum residue is obtained using the SR-ReM *** reaction simulations present a good agreement with the laboratory data for Athabasca vacuum residue *** addition,the proposed methodology provides the molecular detail of the vacuum residue conversion throughout the reactions simulations.

关键词： Monte-Carlo molecular reconstruction kinetic modeling stochastic simulation algorithm vacuum residue hydrocracking

Natural organic matter quantification in the waters of a semiarid freshwater wetland (Tablas de Daimiel, Spain)

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Journal of environmental Sciences 2013年第1期25卷 114-123页

作者： Montserrat Filella Juan Carlos Rodríguez-Murillo Franc ois Quentel Institute F.-A. Forel University of Geneva10 route de SuisseCH-1290 Versoix Switzerland Museo Nacional de Ciencias Naturales CSICSerrano 115 E-28006 MadridSpain laboratoire de Chimie Analytique UMR-CNRS 6521 Universit de Bretagne Occidentale6 avenue V.Le GorgeuCS 93837F-29238 Brest Cedex 3France

Dissolved organic matter （DOM） concentrations have been measured in the waters of a semiarid freshwater wetland, the Tablas de Daimiel, Spain, when the system-characterised by variable hydroperiodicity conditions, was completely flooded （February 2011）. Fluxes of DOM from the wetland soils to the overlying waters were measured by using a passive diffusion sampler （peeper）. Not only dissolved organic carbon （DOC） concentrations were measured but refractory organic matter （ROM, usually known as humic substances） was also quantified using a novel voltammetric method. Fluorescence spectra were recorded to help in selecting the appropriate standard for ROM quantification, test the homogeneity of DOM in the waters and get an indication of their source. The results obtained show a 7-fold increase in measured ROM concentrations from the Gigtiela River to the outlet, which points to a net exportation of ROM from the wetland and to the existence of an internal source of ROM in the system, probably diffusion from the wetland soils. This hypothesis is confirmed by the flux of ROM from the soils to the water column measured with the peeper and by the common fluorescence characteristics of colunm and interstitial waters. The smaller increase in DOC concentrations along the wetland, in spite of the higher DOC fluxes from soils, suggests that there is significant turnover of organic carbon （OC） in the water column. The system acts as a major carbon sink but, when flooded, exports .OC as DOM.

关键词： organic carbon natural organic matter refractory organic matter DOC ROM humic wetland Daimiel

Magnetic and electronic properties of double perovskite Sr2CrMoO6 for spintronic applications: insights from first-principles and Monte Carlo approaches

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Communications in Theoretical Physics 2024年第12期76卷 168-175页

作者： H Kerrai N Zaim M Kerouad A Zaim laboratoire de Physique des Matériaux et Modélisation des Systèmes (LP2MS) Unité Associée au CNRST-URAC: 08 Moulay Ismail University Faculty of Sciences

In this work,we studied the electronic and magnetic properties of the double perovskite Sr2CrMoO6using ab initio calculations with generalized gradient approximation（GGA） and Monte Carlo（MC） *** compound has two magnetic sublattices:one occupied by Mo5+with spin（S=1/2） and the other by Cr3+with spin（σ=3/2） The results showed halfmetallic behavior with a total magnetic moment of 2.0 μB. Using Monte Carlo simulations,we investigated the phase transitions and observed interesting phenomena such as a critical endpoint and both second-order and first-order phase ***,the results revealed compensation points for specific values of the crystal field.

关键词： DFT magnetic properties Monte Carlo simulation spintronic applications

experimental Prospects of the Bc Studies of the LHCb experiment

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Chinese Physics Letters 2010年第6期27卷 44-47页

作者： GAO Yuan-Ning He Ji-Bo Patrick Robbe Marie-Helene Schune YANG Zhen-Wei Key Laboratory of Particle and Radiation Imaging (Ministry of education) Tsinghua University Beijing 100084 Department of engineering Physics Tsinghua University Beijing 100084 Center for High energy Physics Tsinghua University Beijing 100084 Laboratoire de l'Accelerateur Lineaire Universite Paris-Sud 11 CNRS/IN2P3 (UMR 8607) 91400 Orsay France laboratoire de l'Accdl6rateur Lineaire Universite Paris-Sud 11 CNRS/IN2P3 (UMR 8607) 91400 Orsay France

The experimental prospects of the Bc studies of the LHCb experiment are discussed. Production rates of Bc mesons at different center-of-mass energies are estimated with the dedicated generator BCVeGPY. Theoretical estimates and experimental measurements of the Bc± inclusive production cross section at /s =1.96 TeV are compared. The possibilities of studying Bc production, Bc spectroscopy, Bc decays and CP violation in Bc decays in the LHCb experiment are evaluated.

关键词： experimentation Biodeterioration Measurement Productivity Products Production

effects of the trimodal random field on the magnetic properties of a spin-1 Ising nanotube

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Chinese Physics B 2013年第11期22卷 445-452页

作者： H. Magoussi A. Zaim M. Kerouad laboratoire Physique des Mate'riaux et Mode'lisation des Syste`mes (LP2MS) Unite' Associe'e au CNRST-URAC:08 University Moulay Ismail Faculty of Sciences B.P. 11201 Zitoune

In this work, the hysteresis behavior of a nanotube, consisting of a ferromagnetic core of spin-1 atoms surrounded by a ferromagnetic shell of spin-1 atoms with ferro-or anti-ferromagnetic interracial coupling is studied in the presence of a random magnetic field. Based on a probability distribution method, the effective-field theory has been used to investigate the effects of the random magnetic field, the interfacial coupling constant, and the temperature on the hysteresis loops of the nanotube. Some characteristic behaviors have been found, such as the existence of double or triple hysteresis loops for appropriate values of the system parameters. The remanent magnetization and the coercive field, as functions of the temperature, are examined.

关键词： effective-field theory nanotube critical phenomena

Calculation of electric field–temperature (e, T) phase diagram of a ferroelectric liquid crystal near the SmA–SmC_α~* transition

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Chinese Physics B 2018年第3期27卷 444-450页

作者： F Trabelsi H Dhaouadi O Riahi T Othman Universite de Tunis el-Manar Faculte des Sciences de TunisLaboratoire de physique de la matiere molle et de modelisation electromagnetique(LP3ME)Campus Universitaire Farhat Hached 2092 Tunis Tunisie

In this work we perform a theoretical calculation in order to reconstitute the （e-T） phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA-SmCα＊ transition. This reconstruction is carried out on the basis of a thermo-dynamic calculation of the slope of the curve joining the SmC＊ domain and the unwound SmC＊. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations.

关键词： field-temperature phase diagram liquid orystal

A Comparison Theorem and Uniqueness Theorem of Backward Doubly Stochastic Differential equations

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Acta Mathematicae Applicatae Sinica 2011年第2期27卷 223-232页

作者： Qian Lin Zhen Wu School of Mathematics Shandong University Jinan 250100 China laboratoire de Mathematiques CNRS UMR 6205 Universite de Bretagne Occidentale 6 avenue Victor Le Gorgeu CS 93837 29238 Brest cedex 3 France

In this paper, we deal with one dimensional backward doubly stochastic differential equations （BDSDes）. We obtain a comparison theorem and a uniqueness theorem for BDSDes with continuous coefficients.

关键词： backward doubly stochastic differential equations comparison theorem backward stochastic integral uniqueness theorem

Transient Radiation-Conductive Heat transfer Problems:"The Quadrupole Method"

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Journal of Thermal Science 2002年第4期11卷 359-371页

作者： Alain Degiovanni Benjamin Remy Stephane Andre laboratoire d'energetique et de Mecanique Theorique et Appliquee L.E.M.T.A-U.M.R C.N.R.S 7563/E.E.I.G.M-E.N.S.E.MUniversite Henri Poincare-Nancy IInstitut National Polytechnique de Lorraine(I.N.P.L)02avenue de la Foret de Haye-B.P 16054516 Vandoeuvre-Les-Nancy CedexFrance

This paper presents a statement of the works performed in L.e.M.T.A by the members of the thermal and mechanical heterogeneous media research group during the last six years concerning the solving of coupled conductive and radiative heat transfers within a multilayer and semi-transparent“wall”.Out of the authors,this paper allows to take inspiration from the works of ***,*** and ***[19,20,21].The aim of these works is to represent in a macroscopic way,with the minimum number of thermophysical parameters,the heat transfers in a plane system composed of semi-transparent *** approach we propose is semi-analytic(Kernel substitution technique,Laplace transformation)and allow to obtain in the Laplace domain an analytical solution that can be easily *** method can be applied in two main scopes of applications:the estimation of thermophysical properties(phononic conductivity,optical thickness,Planck number for instance)of semi-transparent materials(glasses,crystals,glass wool,semi-conductors,synthetic diamonds,vitroceramics and so on)and the modelling of processes with semitransparent walls(for instance bottles forming,flat glass production,drying of paper).The method will be first presented and validated and two examples of applications will be then *** method can be applied to semitransparent walls that emit,absorb and scatter the radiant energy(participating medium).It appears from the principle of a Kernel substitution technique applied to the radiative flux expression and initially introduced by Lick[1]that allows to change the character of the governing heat equation from the integro-differential form to a purely differential *** the case of limiting cases of purely scattering and purely absorbing media,the solution of the radiative transfer equation is *** the general case,we make a two-flux *** all cases,we assume a linear transfer and use the Laplace *** method can be applied to grey or grey by bands

关键词： heat conduction thermal radiation coupled heat transfer quadrupole method