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Doppler Global Velocimeter-Development and Validation with Measurements in a Round Free Jet

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Journal of Thermal Science 2009年第1期18卷 74-84页

作者： X.Ottavy S.Goguey J.Berthiau I.Trébinjac laboratoire de Mécanique des Fluides et d’Acoustique(LMFA)

Doppler global velocimetry （DGV） has already been shown to be an interesting technique capable of measuring the three components of velocity in a plane. A 1-component DGV system is currently under development at the LMFA, using a stabilized continuous wave （CW） argon ion laser for ermssion, lne receiver Ieatures only one camera for both signal and reference images and incorporates a DEF1 system to adjust the incident laser light frequency and its transmission coefficient on the iodine cell absorption line. A description of the whole system is presented and a validation with measurements of axial velocities at several positions in a round free jet is proposed.

关键词： laser anemometry Doppler shift iodine vapor absorption line filter DEFI system image processing.

Properties of n-type SnO_2 semiconductor prepared by spray ultrasonic technique for photovoltaic applications

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Journal of Semiconductors 2015年第12期36卷 34-37页

作者： H.Bendjedidi A.Attaf H.Saidi M.S.Aida S.Semmari A.Bouhdjar Y.Benkhetta laboratoire de Physique des Couches Minces et Applications Université de Biskra laboratoire des Couches minces et Interfaces Université Mentouri

Transparent conducting n-type SnO2 semiconductor films were fabricated by employing an inexpensive, simplified spray ultrasonic technique using an ultrasonic generator at deferent substrate temperatures （300, 350, 400, 450 and 500 ℃）. The structural studies reveal that the SnO2 films are polycrystalline at 350,400, 450, 500 ℃ with preferential orientation along the （200） and （101） planes, and amorphous at 300 ℃. The crystallite size of the films was found to be in the range of 20.9-72.2 nm. The optical transmittance in the visible range and the optical band gap are 80% and 3.9 eV respectively. The films thicknesses were varied between 466 and 1840 nm. The resistivity was found between 1.6 and 4 × 10^-2 Ω.cm. This simplified ultrasonic spray technique may be considered as a promising alternative to a conventional spray for the massive production of economic SnO2 films for solar cells, sensors and opto-electronic applications.

关键词： tin oxide thin films spray ultrasonic structural properties optical properties

The Apollon 10 PW laser: experimental and theoretical investigation of the temporal characteristics

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High Power Laser Science and Engineering 2016年第3期4卷 127-133页

作者： D.N.Papadopoulos J.P.Zou C.Le Blanc G.Chriaux P.Georges F.Druon G.Mennerat P.Ramirez L.Martin A.Frneaux A.Beluze N.Lebas P.Monot F.Mathieu P.Audebert laboratoire pour l'Utilisation des Lasers Intenses CNRSEcole Polytechnique laboratoire Charles Fabry UMR 8501 Institut d'OptiqueCNRS Univ Paris Sud CEA Iramis SPAM

The objective of the Apollon 10 PW project is the generation of 10 PW peak power pulses of 15 fs at 1 shot min^(-1). In this paper a brief update on the current status of the Apollon project is presented, followed by a more detailed presentation of our experimental and theoretical investigations of the temporal characteristics of the laser. More specifically the design considerations as well as the technological and physical limitations to achieve the intended pulse duration and contrast are discussed.

关键词： high intensity lasers spatiotemporal effects ultrafast lasers

Numerical modeling of centrifuge cyclic lateral pile load experiments

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Earthquake Engineering and Engineering Vibration 2009年第1期8卷 61-76页

作者： Nikos Gerolymos Sandra Escoffier George Gazetas Jacques Garnier Civil Engineering National Technical UniversityAthens Greece laboratoire Central des Ponts et Chaussées Nantes France Lecturer laboratoire Central des Ponts et Chaussées Nantes France

To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including： soil plastification at an early stage of loading, ＂pinching＂ behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. （1974） for sand, is also presented.

关键词： centrifuge test Winkler model p-y curves cyclic loading pile-soil separation/gapping nonlinear response experimental validation

Pressure-broadened atomic Li(2s-2p) line perturbed by ground neon atoms in the spectral wings and core

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Chinese Physics B 2017年第7期26卷 67-74页

作者： Sabri Bouchoucha Kamel Alioua Moncef Bouledroua Physics Department Badji Mokhtar University laboratoire de Physique de la Matière et du Rayonnement Chérif Messaidia University laboratoire de Physique des Rayonnements Badji Mokhtar University

Full quantum calculations are performed to investigate the broadening profiles of the atomic lithium Li（2s-2p） resonance line induced by interactions with ground Ne（2s^22p^6） perturbers in the spectral wings and core. The X^2Σ~＋, A^2Π,and B^2Σ~＋ potential-energy curves of the two first low lying Li Ne molecular states, as well as the corresponding transition dipole moments, are determined with ab initio methods based on the SA-CASSCF-MRCI calculations. The emission and absorption coefficients in the wavelength range 550-800 nm and the line-core width and shift are investigated theoretically for temperatures ranging from 130 K to 3000 K. Their temperature dependence is analyzed, and the obtained results are compared with the previous experimental measurements and theoretical works.

关键词： pressure broadening emission and absorption coefficients linewidth lineshift

Electron Backscattered Diffraction of Transgranular Crack Propagation in Soft Steel

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Chinese Physics Letters 2007年第6期24卷 1759-1762页

作者： A. Boumaiza T. Baudin N. Rouag R. Penelle laboratoire Microstructures et Defauts Universit6 Mentouri Constantine Algdrie laboratoire de Physico-Chimie de l'Etat Solide UMR CNRS 8648 Paris-Sud Orsay France

We consider the crack propagation in a soft steel sheet during the formation. The drawability is considered in relation with the structural anisotropy, the mechanical behaviour is related to both the grain morphology and the texture. The structure heterogeneity could lead to the apparition of micro-cracks. The results show the texture effect on the crack propagation and on the crack arrest in soft steel during the formation. The EBSD technique allows to show that the adjustment of the grain orientation from the initial main component {111}（112） towards the deformation orientation {111}（110） incites a trans-granular crack through a grain with initial {111}（112） orientation in a globally ductile material. It is the presence of grains with {111}（110） orientation which permits the closing of micro-cracks.

关键词： INITIATION GROWTH

NH_3 Plasma Surface Treatments of Engineering Fluoropolymers: A Way to Enhance Adhesion of Ni or Cu Thin Films Deposited by Electroless Plating

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材料热处理学报 2004年第05B期25卷 1092-1097页

作者： Maurice Romand Marlene Charbonnier Yves Goepfert laboratoire de Sciences et Ingenierie des Surfaces and Laboratoire de Sciences et Ingenierie des Surfaces andUMR 5180 des Sciences Analytiques Universite Claude Bernard - Lyon 1 69622 Villeurbanne Cedex France

This paper describes the electroless Ni or Cu plating of some fiuoropolymer substrates through a tin-free activation process. Materials subjected to surface metallization are commercial Teflon() FEP, Nafion(), ACLAR() and LaRCTM-CP1 thin films which have recently gained a large scientific and technological interest due to their excellent thermal, chemical, mechanical and dielectric properties. The original approach implemented in the present work involves: (i)the grafting of nitrogen-containing functionalities on the polymer surfaces through plasma treatments in ammonia, (ii) the direct catalysis of the so-modified surfaces via their immersion in a simple acidic PdCl2 solution (i.e. without using a prior surface sensitization in an acidic SnCl2 solution), and finally (iii) the electroless metallization itself. However, prior to the immersion in the industrial plating baths, the chemical reduction of the Pd+2 species (species covalently tethered on the nitrogen-containing groups) to metallic palladium (PdO) is shown to be a key factor in catalyzing the electroless deposition initiation. This is made by immersion in an hypophosphite (H2PO2-) solution. Wettability measurements and X-ray photoelectron spectroscopy (XPS) experiments are used to characterize every surface modification step of the developed process. A cross-hatch tape test was used to asses the adhesion strength of the electroless films that is shown qualitatively good. In addition, a fragmentation test was developed in combination with electrical measurements. Its use allows to distinguish different adhesion levels at the metal/polymer interface and to evidence the influence of some processing parameters.

关键词：镍化学镀层铜化学镀层等离子表面处理表面催化 XPS 剥离试验

Detection of CO2 and O2 by iron loaded LTL zeolite films

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Frontiers of Chemical Science and Engineering 2018年第1期12卷 94-102页

作者： Veselina Georgieva Richard Retoux Valerie Ruaux Valentin Valtchev Svetlana Mintova laboratoire Catalyse et Spectrochimie (LCS) ENSICAEN CNRS Normandy University 14000 Caen France laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT) ENSICAEN CNRS Normandy University 14000 Caen France

Detection of oxygen and carbon dioxide is important in the field of chemical and biosensors for atmosphere and biosystem monitoring and fermentation processes. The present study reports on the preparation of zeolite films doped with iron nanoparticles for detection of CO2 and O2 in gas phase. Pure nanosized LTL type zeolite with monomodal particle size distribution loaded with iron （Fe-LTL） was prepared under hydrothermal condition from colloidal precursor suspensions. The zeolite was loaded with iron to different levels by ion exchange. The Fe-LTL suspensions were used for preparation of thin films on silicon wafers via spin coating method. The reduction of the iron in the zeolite films was carried out under H2 flow （50% H2 in Ar） at 300 ℃. The presence of iron nanoparticles is proved by in situ ultra-violet-visible spectroscopy. The properties of the films including surface roughness, thickness, porosity, and mechanical stability were studied. In addition, the loading and distribution of iron in the zeolite films were investigated. The Fe-LTL zeolite films were used to detect O2 and CO2 in a concentration dependent mode, followed by IR spectroscopy. The changes in the IR bands at 855 and 642 cm^-1 （Fe O-H and Fe-O bending vibrations） and at 2363 and 2333 cm^-1 （CO2 asymmetric stretching） corresponding to the presence of O2 and CO2, respectively, were evaluated. The response to O2 and CO2 was instant, which was attributed to great accessibility of the iron in the nanosized zeolite crystals. The saturation of the Fe-LTL films with CO2 and O2 at each concentration was reached within less than a minute. The Fe-LTL films detected both oxygen and carbon dioxide in contrast, to the pure LTL zeolite film.

关键词： zeolite films detection of CO2 and O2 adsorption

First-principles study of the new potential photovoltaic absorber:Cu_2MgSnS_4 compound

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Chinese Physics B 2017年第7期26卷 294-304页

作者： Belmorsli Bekki Kadda Amara Mohammed El Keurti laboratoire d'étude physico-chimique Université Dr.Moulay Tahar de Saida

The structural, electronic, optical, and elastic properties of Cu_2MgSnS_4 in four crystalline phases（wurtzite-stannite（WS）, stannite（ST）, kesterite（KS）, and primitive-mixed Cu Au（PMCA）） are investigated using density functional theory（DFT） in the framework of the full potential linearized augmented plane wave plus local-orbitals（FP-LAPW＋lo） method within the generalized gradient approximation based on the Perdew 2008 functional（GGA-PBEsol）. For each phase, the structural parameters, bulk modulus, and its pressure derivative are calculated. The relative stability of these phases is also discussed. In addition, the elastic constants have been calculated in order to investigate the mechanical stability of all phases. Moreover, the anisotropy factor, shear modulus, Young＇s modulus, Lame＇s coefficient, and Poisson＇s ratio have been estimated from the calculated single crystalline elastic constants. For the band structure, the density of states and optical properties of the exchange and correlation effects are treated by the Tran-Blaha modified Becke-Johnson potential to give a better description of the band-gap energies and optical spectra. The obtained results are compared with available experimental data and to other theoretical calculations.

关键词： quaternary chalcogenide semiconductor elastic constants electronic properties optical properties