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Garnet Sm-Nd and U-Pb systems: A case study of a granulite from the European Variscan belt

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Chinese Science Bulletin 2002年第15期47卷 1284-1288页

作者： CHEN Fukuninstitut fur Mineralogie, Petrologie und Geochemie, universitat tubingen, 72074 tubingen, germany institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China institut für Mineralogie Petrologie und Geochemie Universität Tübingen Tübingen Germany institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

This study presents zircon and garnet ages of a mafic granulite from the high-grade Variscan basement of the Black Forest, germany and discuss isotope closure temperature of garnet Sm-Nd and U-Pb systems. Zircon grains yield 207Pb/206Pb ages between -340 and -414 Ma by the U-Pb and evaporation methods. In contract, garnet dating gives Sm-Nd and Pb-Pb isochron ages of (398±3) Ma and (411±14) Ma, respectively, which are older than most of zircon ages. These data imply that most of zircons lost radiogenic Pb, probably due to metamictization or recrystallisa-tion during the granulite-facies metamorphism (-800°C) at -340 Ma. Garnet Sm-Nd and U-Pb systems preserve chronological information of pro-grade metamorphism, probably profiting from a fluid-absence metamorphic environment. These results demonstrate that garnet mineral can be a better candidate than zircon mineral to date high-grade metamorphism by the U-Pb and Sm-Nd methods in some cases.

关键词： Variscan granulite garnet Sm-Nd U-Pb.

Magnetothermal Analysis of Nanocrystallization of Amorphous and Relaxations of Nanocrystalline Materials

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Journal of Materials Science & Technology 1997年第4期13卷 260-264页

作者： Reinhard L■ck(Max-Planck-institut fur Metallforschung, institut fur Werkstoffwissechaft,Seestraβe 75,D-70174 Stuttgart, germany) Max-Planck-institut für Metallforschung Institut für Werkstoffwissenschaft Seestraße 75 D-70174 Stuttgart Germany

For a few years it has been realized that nanocrystalline phases can be formed during crystallization of amorphous alloys annealed isothermally below the crystallization temperature of usual heating experiments. Data of this transformation monitored by the measurement of magnetic susceptibility are presented. A method using a magnetic balance with electronic stabilisation and combined computer facilities is applied. Constant heating and cooling rates as well as isothermal heat treatments are used. Magnetic measurements are able to detect the onset of the transformation of amorphous NI-P alloys much earlier than was possible with differential scanning calorimetry. The transformation kinetics can be analyzed by means of the Avrami plot based on the Johnson-Mehl-Avrami equation. The kinetics of solid state reactions in the nanostructured material can be investigated similarly. Formation of a Ni-phase in a nanostructured Hf-Ni alloy could be detected in a very early stage, where calorimetric methods are not sensitive. Segregation phenomena could be detected from the experiments even after long time. The sensitivity of the applied method is not dependent on the heating rate as the sensitivity of scanning calorimetry is.

关键词： Ni Figure Magnetothermal Analysis of Nanocrystallization of Amorphous and Relaxations of Nanocrystalline Materials

ROBUSTNESS OF AN UPWIND FINITE DIFFERENCE SCHEME FOR SEMILINEAR CONVECTION-DIFFUSION PROBLEMS WITH BOUNDARY TURNING POINTS

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Journal of Computational Mathematics 2003年第4期21卷 401-410页

作者： Torsten Linfi (institut fur Numerische Mathematik, Technische Universitdt Dresden, D-01062 Dresden, germany) institut fiir Nwnerisclie Mathematik Technische Universitdt Dresden 德国 D-01062 Dresden

We consider a singularly perturbed semilinear convection-diffusion problem with a boundary layer of attractive turning-point type. It is shown that its solution can be decomposed into a regular solution component and a layer component. This decomposition is used to analyse the convergence of an upwinded finite difference scheme on Shishkin meshes.

关键词： Convection-diffusion Singular perturbation Solution decomposition Shishkin mesh.

Reconstruction of Complex Materials by Integral Geometric Measures

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Journal of Materials Science & Technology 2002年第2期18卷 155-158页

作者： Klaus R.MeckeMax-Planck-institut fur Metallforschung, Heisenbergstr.1, D-70569 Stuttgart, institut fur Theoretische und Angewandte Physik, Fakultat fiir Physik universitat Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, germany [ Manuscript received Nov Fakultat fur Phys. Univ. Stuttgart Pfaffenwaldring 57 D-70569Stuttgart Germany

The goal of much research in computational materials science is to quantify necessary morphological information and then to develop stochastic models which both accurately reflect the material morphology and allow one to estimate macroscopic physical properties. A novel method of characterizing the morphology of disordered systems is presented based on the evolution of a family of integral geometric measures during erosion and dilation operations. The method is used to determine the accuracy of model reconstructions of random systems. It is shown that the use of erosion/dilation operations on the original image leads to a more accurate discrimination of morphology than previous methods.

关键词： Porous media Integral geometry Morphology Erosion Dilation Minkowski functionals Reconstruction

A study on wildfire impacts on greenhouse gas emissions and regional air quality in South of Orléans,France

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Journal of Environmental Sciences 2024年第1期135卷 521-533页

作者： Chaoyang Xue Gisèle Krysztofiak Yangang Ren Min Cai Patrick Mercier Frédéric Le fur Corinne Robin Benoit Grosselin Véronique Daele Max RMcGillen Yujing Mu Valéry Catoire Abdelwahid Mellouki Laboratoire de Physique et Chimie de l’Environnement et de l’Espace(LPC2E) CNRS–UniversitéOrléans–CNES(UMR 7328)Orléans Cedex 245071France institut de Combustion AérothermiqueRéactivitéEnvironnement(ICARE)CNRSOrléans Cedex 245071France Research Centre for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Lig’Air-Association de surveillance de la qualitéde l’air en région Centre-Val de Loire Saint-Cyr-en-Val 45590France Mohammed V University RabatMorocco

Wildfire events are increasing globally which may be partly associated with climate change,resulting in significant adverse impacts on local,regional air quality and global *** September 2020,a small wildfire(burned area:36.3 ha)event occurred in Souesmes(Loiret-Cher,Sologne,France),and its plume spread out over 200 km on the following day as observed by the MODIS *** on measurements at a suburban site(~50 km northwest of the fire location)in Orléans and backward trajectory analysis,young wildfire plumes were *** increases in gaseous pollutants(CO,CH_(4),N_(2)O,VOCs,etc.)and particles(including black carbon)were found within the wildfire plumes,leading to a reduced air *** factors,defined as EF(X)=ΔX/ΔCO(where,X represents the target species),of various trace gases and black carbon within the young wildfire plumes were determined accordingly and compared with previous *** in the ambient ions(such as ammonium,sulfate,nitrate,chloride,and nitrite in the particle-and gasphase)and aerosol properties(e.g.,aerosol water content,aerosol p H)were also quantified and ***,we estimated the total carbon and climate-related species(e.g.,CO_(2),CH_(4),N_(2)O,and BC)emissions and compared them with fire emission *** biomass burning emission inventories have uncertainties in estimating small fire burned areas and *** instance,we found that the Global Fire Assimilation System(GFAS)may underestimate emissions(e.g.,CO)of this small wildfire while other inventories(GFED and FINN)showed significant *** that it is the first time to record wildfire plumes in this region,related atmospheric implications are presented and discussed.

关键词： Wildfire Air quality Emission factor Emission inventory VOLTAIRE supersite

CREEP DEFORMATION OF INTERMETALLIC ALLOYS

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Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 431-440页

作者： Gerhard Sauthoff(Max-Planck-institut fur Eisenforschung GmbH., D-40074 Dusseldorf,germany) Max-Planck-institut fur Eisenforschung GmbH Dusseldorf Germany

Intermetallics for structural applications at high temperatures must show a sufficient high temperature strength which is controlled by creep processes. In the first section the creep behaviour of single-phase intermetallic alloys is overviewed with respect to stress and temperature dependence and effects of composition and microstructure. It is shown in particular that creep deformation is controlled by diffusion. The second section refers to multiphase intermetallic alloys, and both particulate and non-particulate alloys are regarded. Data are presented for single-phase and multiphase alloys based on B2 phases and lesscommon phases and the consequences of diffusion control for alloy design are discussed.

关键词： creep B2 phases NiAl particulate alloys,multiphase alloys

Determination of Elastic and Creep Properties of Thin-film Systems from indentation Experiments

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Journal of Materials Science & Technology 2000年第6期16卷 559-567页

作者： Z.F.Yue and G.Eggeler (institut fur Werkstoffe, Ruhr-universitat Bochum, 44 801 Bochum, germany) [Manuscript received February 16, 2000, in revised form April 12, 2000] Ruhr Univ Bochum Inst Werkstoffe D-44801 Bochum Germany

Based on the detailed computer simulation of the indentation testing on the thin-film systems, the present paper explores the detailed procedure of determining elastic properties (elastic modulusE^(f) and Poisson ratio v(f)) and creep parameters (CCREEP^(f) and nCREEP^(f)) for a simple Norton law (ε=CCREEP^(f)σ^n CREE^(f), where e is creep strain rate, and a is the stress) material for a thin film coated on a creep substrate, whose elastic properties(E^(s) and v^(s)) and creep properties (CCREEP^(s) and nCREEP^(s)) of the substrate are known, from indentation elastic and creep testing,respectively. The influences of the thickness of the thin-film and the size of the indenter on the indentation behavior have been discussed. It is shown that the boundary between the thin film and the substrate has great influence on the indentation creep behavior. The relative sizes of indentation systems are chosen so that the behavior of the indentation on the film is influenced by the substrate. The two elastic parameters E^(f) and v^(f) of the film are coupled on the influence of the elastic behavior of indentation. With the two different size indenters, the two elastic parameters E^(f) and v^(f) of the film can be uniquely determined by the indentation experimental slopes of depth to applied net section stress results. The procedure of determining of the two Norton law parameters CCREEP^(f) and nCREEP^(f) includes the following steps by the steady indentation rate d. The first step to calculate the creep indentation rate on certain loads of the two different sizes of indenters on a set of assumed values of CCREEP^(f) and nCREEP^(f)Then to build relationship between the creep indentation rate and the assumed CCREEP^(f) and nCREEP^(f) With the experimental creep indentation rate to intersect two sets of which have the same values of d. The last step is to build the CCREEP^(f) and nCREEP^(f)curves from the intersection points for the two indenters. These two curves CCREEP^(f) a

关键词： Thin Determination of Elastic and Creep Properties of Thin-film Systems from indentation Experiments

EXISTENCE OF AREA MINIMIZING TANGENT CONES OF INTEGRAL CURRENTS WITH PRESCRIBED MEAN CURVATURE

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Acta Mathematica Scientia 1995年第1期15卷 95-102页

作者： Frank Duzaar(institut fur Augewandte Mathematik der universitat Bonn,Beringstr.4.D-53115 Bonn)Martin Fuchs(universitat des Saarlandes,Fachbereich Mathematik,D-66123 Saarbrucken) institut für Angewandte Mathematik der Universität Bonn Beringstr. 4 D–53115 Bonn Universität des Saarlandes Fachbereich Mathematik D–66123 Saarbrücken

Given an integral M-currrent To in Rm+k and a tensor H of type(m.l)on Rn+k with values orthogonal to each of its arguments we proved in a previous peper[3]the sxistence of anintegral m-current T =γ(M,θ.ζ)with boundary T0 and mean curvature vector H by minimizing an appropriate functional on suitable subclasses of the set of all integral *** thes paperwe discuss the existence and structure of oriented tangent cones C of T at points x∈spt(T) spt(T),especially we show that C is locally mass minimizing.

关键词： integral currents,generalized mean curvature tangent cones

Interfacial Electronic Structure of Thin Cu Films Grown on Ar^+-ion Sputter-cleaned α-Al_2O_3 Substrates

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Journal of Materials Science & Technology 2002年第2期18卷 117-120页

作者： Christina Scheu, Min Gao and Manfred RuhleMax-Planck-institut fur Metallforschung, Seestr. 92, 70174 Stuttgart, germany [ Manuscript received October 17, 2001] Max-Planck-Inst. für Metall. Seestr. 92 70174 Stuttgart Germany

The bonding and electronic structure of Cu/(0001)Al2O3 and Cu/(1120)Al2O3 interfaces has been studied experimentally using spatially-resolved transmission electron energy loss spectroscopy. The specimen were prepared by depositing Cu on single-crystal α-AI2O3 substrates, which have been Ar+-ion sputter-cleaned prior to the growth of Cu. For both orientations of the α-Al2O3 substrate, atomically abrupt interfaces formed as determined by high-resolution transmission electron microscopy. The investigations of the interfacial Cu-L2,3, Al-L2,3 and 0-K energy loss near-edge structures, which are proportional to the site- and angular-momentum-projected unoccupied density of states above the Fermi level, indicate the existence of metallic Cu-AI bonds at the Cu/AI2O3 interface independent of the substrate orientation.

关键词： Electronic structure Cu film Ion sputtering α-Al2O3