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Reconstruction of a defect in an open waveguide

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Science China Mathematics 2013年第12期56卷 2539-2548页

作者： BAO Gang TRIKI Faouzi Department of Mathematics Zhejiang University Department of Mathematics Michigan State UniversityEast Lansing MI 48824 USA laboratoire Jean Kuntzmann Universit'e Joseph Fourier & CNRS38041 Grenoble Cedex 9 France

The paper is concerned with the reconstruction of a defect in the core of a two-dimensional open waveguide from the scattering data. Since only a finite numbers of modes can propagate without attenuation inside the core, the problem is similar to the one-dimensional inverse medium problem. In particular, the inverse problem suffers from a lack of uniqueness and is known to be severely ill-posed. To overcome these difficulties, we consider multi-frequency scattering data. The uniqueness of solution to the inverse problem is established from the far field scattering information over an interval of low frequencies.

关键词： inverse problem Helmholtz equation open waveguide Green function multi-frequency data

Design and current progress of the Apollon 10 PW project

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High Power Laser Science and engineering 2015年第1期3卷 32-35页

作者： J.P.Zou C.Le Blanc D.N.Papadopoulos G.Chériaux P.Georges G.Mennerat F.Druon L.Lecherbourg A.Pellegrina P.Ramirez F.Giambruno A.Fréneaux F.Leconte D.Badarau J.M.Boudenne *** T.Valloton J.L.Paillard J.L.Veray M.Pina P.Monot J.P.Chambaret P.Martin F.Mathieu P.Audebert F.Amiranoff laboratoire pour l’Utilisation des Lasers Intenses CNRSEcole Polytechnique laboratoire d’Optique Appliquée ENSTA Paris TechCNRS laboratoire Charles Fabry UMR 8501Institut d’OptiqueCNRSUniversité Paris Sud CeA IramisSPAM

The objective of the Apollon project is the generation of 10 PW peak power pulses of 15 fs at 1 shot/minute. In this paper the Apollon facility design, the technological challenges and the current progress of the proj... 详细信息

关键词： titanium lasers PW class facilities

High-Order Two-Scale Asymptotic Paradigm for the elastodynamic Homogenization of Periodic Composites

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Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo Mu He Liang Xia Qi-Chang He State Key Laboratory of Intelligent Manufacturing equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China laboratoire Modélisation et Simulation Multi-echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion ***,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order *** such a context,a compact,fast,and accurate asymptotic paradigm is *** work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be ***,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional *** numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

A PeRTURBATION MeTHOD FOR THe NUMeRICAL SOLUTION OF THe BeRNOULLI PROBLeM

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维普期刊数据库

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Journal of Computational Mathematics 2008年第1期26卷 23-36页

作者： Franois Bouchon Stéphane Clain Rachid Touzani laboratoire de Mathématiques Universite Blaise Pascal (Clermont-Ferrand) and CNRS (UMR 6620) Campus Universitaire des Cézeaux63177 Aubière cedexFrance laboratoire MIP UFR MIGUniversité Paul Sabatier Toulouse 3118 route de Narbonne31062 Toulouse cedex 4France laboratoire de Mathematiques Université Blaise Pascal (Clermont-Ferrand) and CNRS (UMR 6620) Campus Universitaire des Cézeaux63177 Aubière cedexFrance

We consider the numerical solution of the free boundary Bernoulli problem by employing level set formulations. Using a perturbation technique, we derive a second order method that leads to a fast iteration solver. The iteration procedure is adapted in order to work in the case of topology changes. Various numerical experiments confirm the efficiency of the derived numerical method.

关键词： Bernoulli problem Free boundary Level sets

Optical Constant and electrical Resistivity of Annealed Sn3Sb2S6 Thin Films

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Acta Metallurgica Sinica(english Letters) 2016年第3期29卷 287-294页

作者： Y.Fadhli A.Rabhi M.Kanzari laboratoire de Photovoltaique et Materiaux Semi-conducteurs-eNIT BP 37 Le belvedere 1002 Tunis Tunisia laboratoire de Photovoltaiques et Materiaux Semi-conducteurs-eNIT-IPeITunis Montfleury Universite de Tunis Tunis Tunisia

In this study,we report the annealing effects on the physical properties of Sn_3Sb_2S_6 thin ***_3Sb_2S_6 thin films were prepared onto non-heated glass substrates via thermal evaporation *** as-deposited films were annealed in air for 1 h in the temperature range from 100 to 300 °C.X-ray diffraction results show that the crystallinity of the thin films increased after *** microstructure parameters crystallite size,dislocation density,lattice strain and stacking fault probability were *** optical properties were obtained from the analysis of the experimental recorded transmittance and reflectance spectral data over the wavelength range 300–1800 *** absorption coefficient（10~5cm^（-1）） reached to the visible and near-IR spectral range.A decrease in optical band gap from 1.92 to 1.71 e V by increasing the air annealing temperature was *** energy e_o and dispersion energy e_d of the films after annealing were estimated according to the model of Wemple–Di Domenico single ***–Fan model was applied to determine the electron free carrier susceptibility and the ratio of carrier concentration to the effective *** layers annealed at temperatures 〉150 ℃ undergo abrupt changes in their electrical properties and exhibit a resistive hysteresis *** properties confer to the material interest perspectives for its application in diverse advanced technologies such as photovoltaic applications and optical storage.

关键词： Thin films Sn_3Sb_2S_6 Optical constants Resistivity Hysteresis

Stochastic seismic response of multi-layered soil with random layer heights

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earthquake engineering and engineering Vibration 2010年第2期9卷 213-221页

作者： M.Badaoui M.K.Berrah A.Mébarki Université Paris-est Laboratoire Modélisation et Simulation Multi Echelle ecole Nationale Polytechnique

This paper deals with the effect of layer height randomness on the seismic response of a layered soil. These parameters are assumed to be lognormal random variables. The analysis is carried out via Monte Carlo simulations coupled with the stiffness matrix method. A parametric study is conducted to derive the stochastic behavior of the peak ground acceleration and its response spectrum,the transfer function and the amplification factors. The input soil characteristics correspond to a site in Mexico City and the input seismic accelerations correspond to the Loma Prieta earthquake. It is found that the layer height heterogeneity causes a widening of the frequency content and a slight increase in the fundamental frequency of the soil profile,indicating that the resonance phenomenon is a concern for a large number of structures. Variation of the layer height randomness acts as a variation of the incident angle,i.e.,a decrease of the amplitude and a shift of the resonant frequencies.

关键词： random layer heights layered soil seismic acceleration lognormal distribution amplification factors Mexico City

Topological Studies of Three-dimensional Flows in a High Pressure Compressor Stator Blade Row without and with Boundary Layer Aspiration

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Chinese Journal of Aeronautics 2011年第5期24卷 541-549页

作者： Ankit SACHDeVA Francis LeBOeUF laboratoire de Mécanique des Fluides et d'Acoustique Ecole Centrale de Lyon

This paper presents a numerical study of the flow topologies of three-dimensional （3D） flows in a high pressure compressor stator blade row without and with boundary layer aspiration on the hub wall. The stator blade is representative of the first stage operating under transonic inlet conditions and the blade design encourages development of highly complex 3D flows. The blade has a small tip clearance. The computational fluid dynamics （CFD） studies show progressive increase of hub corner stall with the increase in incidence. Aspiration is implemented on the hub wall via a slot in the comer between the hub wall and the suction surface. The CFD studies show aspiration to be sensitive to the suction flow rate; lower rate leads to very complex flow struc- tures and increased level of losses whereas higher rate renders aspiration effective for control of hub comer separation. The flow topologies are studied by trace of skin friction lines on the walls. The nature of flow can be explained by the topological rules of closed separation. Furthermore, a deeper analysis is done for a particular case with advanced criterion to test the non-degeneracy of critical points in the flow field.

关键词： high pressure compressor flow topologies three-dimensional flows boundary layer aspiration tip clearance

Calculation and application of partition coefficients of light hydrocarbons in oil-based mud system

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Petroleum exploration and Development 2022年第4期49卷 906-918页

作者： BeN ABDALLAH Bacem Rabie AHMADI Riadh LYNeN Frederic ReKHISS Farhat laboratoire LR3e.ecole Nationale d’Ingénieurs de Sfax Rte Soukra km 3SfaxTunisia Separation Science Group Department of Organic and Macromolecular ChemistryGhent UniversityKrijgslaan 281-S4B-9000 GhentBelgium

To find out the relationship between the oil-based mud,the formation fluid and the extracted gas,we use a thermodynamic approach based on static headspace gas chromatography technique to calculate the partition coefficients of 47 kinds of light hydrocarbons compounds between nC5 and nC8 in two kinds of oil-based mud-air systems,and reconstruct the original formation fluid composition under thermodynamic *** oil-based drilling mud has little effect on the formation fluid compositions in the range of nC5-nC8(less than 1%for low-toxicity oil-based mud and less than 10%for oil-based mud).For most light hydrocarbon compositions,the partition coefficients obtained by vapor phase calibration and the direct quantitative methods have errors of less than 10%,and the partition coefficients obtained by direct quantitative method are more *** reconstructed compositions of the two kinds of crude oil have match degrees of 91%and 89%with their real compositions,proving the feasibility and accuracy of reconstructing the composition of original formation fluid by using partition coefficients of light hydrocarbon compositions between nC5 and nC8.

关键词： oil-based mud drilling mud gas light hydrocarbon compositions partition coefficients reservoir fluid

A general solution for Stokes flow and its application to the problem of a rigid plate translating in a fluid

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Acta Mechanica Sinica 2015年第1期31卷 32-44页

作者： Xiang-Yu Li Si-Cong Ren Qi-Chang He School of Mechanics and engineering Southwest Jiaotong University School of Mechanical engineering Southwest Jiaotong University Universit'e Paris-est Laboratoire Mod'elisation et Simulation Multi Echelle UMR 8208 CNRS 5 Boulevard Descartes77454 Marne-la-Vall'ee France

A general solution for 3D Stokes flow is given which is different from, and more compact than the exist ing ones and more compact than them in that it involves only two scalar harmonic functions. The general solution deduced is combined with the potential theory method to study the Stokes flow induced by a rigid plate of arbitrary shape trans lating along the direction normal to it in an unbounded fluid. The boundary integral equation governing this problem is derived. When the plate is elliptic, exact analytical results are obtained not only for the drag force but also for the ve locity distributions. These results include and complete the ones available for a circular plate. Numerical examples are provided to illustrate the main results for circular and ellip tic plates. In particular, the elliptic eccentricity of a plate is shown to exhibit significant influences.

关键词： Stokes flow 3D general solutions Potentialtheory method Circular plate elliptic plate