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Selective catalytic reduction of nitrogen oxides over a modified silicoaluminophosphate commercial zeolite

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Journal of Environmental Sciences 2018年第3期30卷 246-252页

作者： Carolina Petitto gérard Delahay Institut Charles gerhardt Montpellier UMR 5253 CNRS/UM/ENSCM Matériaux Avancés pour la Catalyse et la Santé 8 rue de l'Ecole Normale

Nitrogen oxides（NOx：NO,NO2）are a concern due to their adverse health *** engine transport sector is the major emitter of *** regulations have been strengthened and to comply with them,one of the two methods commonly used is the selective catalytic reduction of NOxby NH3（NH3-SCR）,NH3being supplied by the in-situ hydrolysis of *** and durability of the catalyst for this process are highly *** is evaluated by hydrothermal treatment of the catalysts at temperature above 800℃.In this study,very active catalysts for the NH3-SCR of NOxwere prepared by using a silicoaluminophosphate commercial zeolite as copper host *** by X-ray diffraction（XRD）,scanning electron microscopy（SEM）and temperature programmed desorption of ammonia（NH3-TPD）showed that this commercial zeolite was hydrothermally stable up to 850℃ and,was able to retain some structural properties up to950℃.After hydrothermal treatment at 850℃,the NOxreduction efficiency into NH3-SCR depends on the copper *** catalyst with a copper content of 1.25 wt.%was the most *** difference in activity was much more important when using NO than the fast NO/NO2reaction mixture.

关键词： Diesel Nitrogen oxides SCR process Copper Zeolite Silicoaluminophosphate

growth of high-quality thick gaN using a tungsten interlayer

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Rare Metals 2006年第Z2期25卷 11-14页

作者： NOUET gérard RUTERANA Pierre Laboratoire Structures des Interfaces et Fonctionnalité des Couches Minces UMR CNRS 6176 ENSICAEN 6 Boulevard du Maréchal Juin 14050 Caen Cedex France

A high-quality gaN film was (W-gaN) grown by hydride vapor phase epitaxy (HVPE) on metalorganic chemical vapor deposition (MOCVD) gaN templates with a tungsten (W) interlayer. A sample without interlayer was also grown at the same time for comparison. Significant reductions of dislocation density in W-gaN film is confirmed by the result of high-resolution X-ray diffraction and transmission electron microscope (TEM) observation. The improvement of optical properties of the W-gaN is confirmed by photoluminescence (PL) result. A shift of PL peak suggests that the strain is lower in the W-gaN than the film without W interlayer. This technique offers a potential path to obtain high-quality gaN film as free-standing substrate.

关键词： gaN tungsten interlayer HVPE HRXRD

A survey of the Szeg? equation Dedicated to Professor Jean-Yves Chemin on the Occasion of His 60th Birthday

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Science China Mathematics 2019年第6期62卷 1087-1100页

作者： Patrick gérard Sandrine grellier Laboratoire de Mathématiques d'Orsay Université Paris-Sud CNRSUniversité Paris-Saclay Institut Denis Poisson-Université d'Orléans/Université de Tours CNRS UMR

We survey the main properties of the cubic Szeg? equation from the PDE viewpoint, emphasising global existence of smooth solutions, analytic regularity, growth of high Sobolev norms and the effects of weak damping.

关键词： cubic Szego equation integrable system Hankel operator spectral analysis analytic regularity wave turbulence

Precise time scales and navigation systems:mutual benefits of timekeeping and positioning

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Satellite Navigation 2020年第1期1卷 101-112页

作者： Patrizia Tavella gérard Petit Bureau International des Poids et Mesures Pavillon de Breteuil92312 Sèvres CedexFrance

The relationship and the mutual benefits of timekeeping and global Navigation Satellite Systems(gNSS)are reviewed,showing how each field has been enriched and will continue to progress,based on the progress of the other *** role of gNSSs in the calculation of Coordinated Universal Time(UTC),as well as the capacity of gNSSs to provide UTC time dissemination services are described,leading now to a time transfer accuracy of the order of 1-2 *** addition,the fundamental role of atomic clocks in the gNSS positioning is *** paper presents a review of the current use of gNSS in the international timekeeping system,as well as illustrating the role of gNSS in disseminating time,and use the time and frequency metrology as fundamentals in the navigation service.

关键词： Atomic clock Time scale Time measurement Navigation Timekeeping UTC

Stepping up after spinal cord injury:negotiating an obstacle during walking

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Neural Regeneration Research 2025年第7期20卷 1919-1929页

作者： Alain Frigon Charly g.Lecomte Department of Pharmacology-Physiology Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate *** spinal cord injury,stepping over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor *** information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiology obstacle negotiation spinal cord injury

An SPH Framework for Earthquake-Induced Liquefaction Hazard Assessment of geotechnical Structures

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.Ramana Department of Civil Engineering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures *** understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile ***,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando *** agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.

关键词： Earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPH)

Effect of AlN intermediate layer on growing gaN film by hydride vapor phase epitaxy

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Rare Metals 2006年第Z2期25卷 15-19页

作者： NOUET gérard2 RUTERANA Pierre Laboratoire Structures des Interfaces et Fonctionnalité des Couches Minces UMR CNRS 6176 ENSICAEN6 Boulevard du Maréchal Juin 14050 Caen Cedex France

Thick gaN layer deposited by hydride vapor phase epitaxy (HVPE) on a metalorganic chemical vapor deposition (MOCVD) gaN template with a thin low temperature (LT) AlN intermediate layer was investigated. High resolution X-ray resolution diffraction (HRXRD) shows that the crystalline quality of thick gaN layer was improved compared with the template. As confirmed by atomic force microscopy (AFM) observations, the surface morphology of AlN intermediate layer helps to improve the nucleation of gaN epilayer. Photoluminescence (PL) spectra measurement shows its high optical quality and low compressive stress, and micro Raman measurement confirms the latter result. Thus, the deposition of the LT-AlN interlayer has promoted the growth of an HVPE-gaN layer with an excellent crystalline quality.

关键词： gaN AlN intermediate layer HVPE HRXRD AFM photoluminescence

Sediment bed destabilization by an isolated vortex:an experimental approach

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Journal of Hydrodynamics 2021年第2期33卷 370-385页

作者： Yann Devaux Lionel Thomas Damien Calluaud gérard Pineau Institut Pprime CNRS-Universitéde Poitiers-ISAE-ENSMA-UPR 3346PoitiersFrance

The destabilization of an erodible sediment bed by a reproducible impulsive phenomenon is studied *** this,a specific setup is designed to produce a well-controlled isolated vortex,advected over a uniform sand *** image velocimetry(PIV)measurements are performed to get fluid flow information;suspended particles images are also recorded.A new measurement technique,based on a stereo-correlation method,provides a precise reconstruction of the bedform morphology over *** turbulent structures(namely sweep events)are evidenced in a near-wall region,where particles are mainly *** sediment plume follows the vortex:in particular,the upward velocity inside maintains the suspension ***,the dispersion process seems to be not dependent on the vortex ***,the bed morphology is investigated:a scour hole is dug as the vortex hits the granular *** dynamics is described by a typical scour law,even if the initial perturbation is *** area,where the particles settled,can be observed:it behaves like a ripple,with a logarithmic growth of its *** deposition region has a specific geometry,studied here by a Fourier contour ***,a pickup rate is also derived from the morphological data:it appears independent of the vortex and bedform features.

关键词： Sediment plume isolated vortex stereo-correlation particle image velocimetry(PIV) bedform dynamics

Effects of Polypropylene Fibers on the Physical and Mechanical Properties of Recycled Aggregate Concrete

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Journal of Wuhan University of Technology(Materials Science) 2019年第6期34卷 1327-1344页

作者： Pierre Matar gérard-Philippe Zéhil Lebanese University Faculty of EngineeringBranch 2RoumiehLebanon Notre Dame University-Louaize Faculty of EngineeringZouk MosbehLebanon

The viability of using polypropylene fibers(PPF) in concrete was largely studied. Yet, few of the existing research studies investigated the effects of PPF on the properties of concrete containing recycled concrete aggregate(RCA). Mixes with different RCA replacement ratios and different PPF content were designed and tested. The test results showed that the addition of PPF did not change significantly the compressive strength and the density of the concrete, but slightly decreased its modulus of elasticity and Poisson’s ratio. The drop in the splitting tensile strength and the flexural strength due to RCA inclusions was to a large extent compensated by the PPF addition. The water absorption decreased and the percent voids increased with increased PPF addition. Correlations between the RCA content, the PPF content and the properties of concrete were studied. Useful regression models were proposed to predict the properties of concrete in relevant ranges of RCA and PPF content.

关键词： concrete recycled aggregate fiber reinforcement physical properties mechanical properties