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Directional H^(2) Compression Algorithm: Optimisations and Application to a Discontinuous Galerkin BEM for the Helmholtz Equation

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Communications in Computational Physics 2022年第5期31卷 1585-1635页

作者： Nadir-Alexandre Messaï Sebastien Pernet Abdesselam Bouguerra ONERA/DTIS Universitéfédérale de Toulouse F-31000 Toulouse France Laboratoire de Physique de la Matière et du Rayonnement(lpmr) Département de Sciences de la MatièreUniversitéde Souk-AhrasBP 155341000 Souk-AhrasAlgeria

This study aimed to specialise a directional H^(2)(DH^(2))compression to matrices arising from the discontinuous Galerkin(DG)discretisation of the hypersingular equation in *** significantfinding is an algorithm that takes a DG stiffness matrix andfinds a near-optimal DH^(2) approximation for low and high-frequency *** introduced the necessary special optimisations to make this algorithm more efficient in the case of a DG stiffness ***,an automatic parameter tuning strategy makes it easy to use and *** comparisons with a classical Boundary Element Method(BEM)show that a DG scheme combined with a DH^(2) gives better computational efficiency than a classical BEM in the case of high-order finite elements and hp heterogeneous *** results indicate that DG is suitable for an auto-adaptive context in integral equations.

关键词： Integral equation boundary element method Helmholtz equation discontinuous Galerkin directional H^(2)-matrix low-rank approximation all frequency compression algorithm

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Preparation and Characterization of ZnO Nanocrystalline Layers

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Journal of Materials Science and Chemical Engineering 2014年第12期2卷 1-6页

作者： A. Haddad A. Hafidi A. Ain-Souya N. Chahmat R. Ganfoudi M. Ghers Laboratory for the Study of Surfaces and Interfaces of Solid Material (LESIMS) Badji Mokhtar-Annaba University Annaba Algeria Physics Laboratory of Matter and Radiation (lpmr) Med Cherif Mesaadia-Souk Ahras University Souk Ahras Algeria

This work consists on the study of the optical properties of zinc oxide layers. These Layers are elaborated under various conditions by cathode sputtering on glass substrates and by thermal oxidations of Zn layers deposited on different types of substrates by vacuum evaporation. The oxidation treatments of Zn are made in oxygen atmosphere at temperatures between 400°C and 450°C for different times. The analyses by diffraction of X-rays, Optical Microscopy and Scanning electron microscopy enabled us to understand that the zinc oxide films deposited by cathode sputtering on a glass substrate and having a thickness of at least 240 nm and those prepared by thermal oxidation at 450°C during 2 hours of layers of Zn on an alumina substrate are homogeneous and consist of grains of size 30 nm. The optical transmission measurements show that the gap is around 3.02 eV for layers obtained by oxidation and 3.3 eV for those deposited by sputtering. These samples have a good optical transparency in the visible.

关键词： Oxide Gas Adsorption Conductance Properties

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Theoretical investigation of the pressure broadening D1 and D2 lines of cesium atoms colliding with ground-state helium atoms

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Chinese Physics B 2019年第10期28卷 300-308页

作者： Moussaoui Abdelaziz Alioua Kamel Allouche Abdul-rahman Bouledroua Moncef Universite Cherif Messaidia B.P.1553Souk-Ahras 41000Algerie Laboratoire de Physique de la Matiere et du Rayonnement lpmr Universite Cherif MessaidiaB.P.1553Souk-Ahras 41000Algerie Universite Lyon 1 CNRSLASIM UMR5579bat.A.Kastler43 Bd du 11 novembre 1918F-69622 VilleurbanneFrance Laboratoire de Physique des Rayonnements LPR Universite Badji MokhtarB.P.12Annaba 23000Algerie

Full quantum mechanical calculations are performed to determine the broadening in the far wings of the cesium D1 and D2 line shapes arising from elastic collisions of Cs atom with inert helium atoms. The potential energy curves of the low-lying CsHe molecular states, as well as the related transition dipole moments, are carefully computed from ab initio methods based on state-averaged complete active space self-consistent field-multireference configuration interaction(SACASSCF-MRCI) calculations, involving the spin-orbit effect, and taking into account the Davidson and BSSE *** absorption and emission reduced coefficients are determined in the temperature and wavelength ranges of 323-3000 K and 800-1000 nm, respectively. Both profiles of the absorption and the emission are dominated by the free-free transitions,and exhibit a satellite peak in the blue wing near the wavelength 825 nm, attributed to B^2Σ1/2^+→ X^2Σ1/2^+/transitions. The results are in good agreement with previous experimental and theoretical works.

关键词： absorption coefficient emission coefficient pressure broadening potential curves

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Li(2p←2s)+Na(3s)pressure broadening in the far-wing and line-core profiles

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Chinese Physics B 2022年第7期31卷 247-254页

作者： F Talbi N Lamoudi L Reggami M T Bouazza K Alioua M Bouledroua Physics Department Badji Mokhtar UniversityB.P.12Annaba 23000Algeria Laboratoire de Physique des Rayonnements Badji Mokhtar UniversityB.P.12Annaba 23000Algeria Laboratoire d’Etude des Surfaces et Interfaces de la Matiere Solide(LESIMS) Badji Mokhtar UniversityB.P.12 Annaba 23000Algeria Laboratoire LAMA Laboratoire des Materiaux Avances(LAMA)Badji Mokhtar UniversityB.P.12 Annaba 23000Algeria Laboratoire de Physique de la Matiere et du Rayonnement lpmr Universite Cherif MessaidiaB.P.1553Souk-Ahras 41000Algeria

This work reports pressure-broadening line-wing and line-core of the lithium Li(2p←2s)resonance line perturbed by ground sodium Na(3s)*** far-wing regions,the calculations are performed quantum-mechanically and are intended to examine the photoabsorption coefficients at diverse *** results show the existence of three satellites,in the blue wing near the wavelengths 470 nm and in the red wing around 862 nm and 1070 *** the line-core region,by adopting the simplified Baranger model,the line-width and line-shift rates are determined,and their variation law with temperature is *** published data were found to compare these results with.

关键词： pressure broadening line-core broadening far-wing spectra photoabsorption

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Bound in continuum states and induced transparency in mesoscopic demultiplexer with two outputs

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Chinese Physics B 2020年第12期29卷 429-437页

作者： Z Labdouti T Mrabti A Mouadili E H El Boudouti F Fethi B Djafari-Rouhani lpmr Dèpartement de PhysiqueFacultèdes SciencesUniversitèMohammed IOujdaMorocco LSTA Dèpartement de PhysiqueFacultèPolydisciplinaire de LaracheUniversitèAbdelmalek EssaadiTètouanMorocco LPMCER Dèpartement de PhysiqueFacultèdes Sciences et Techniques de MohammediaUniversitèHassan IICasablancaMorocco IEMN UMR CNRS 8520UFR de PhysiqueUniversitède Lille59655 Villeneuve d'AscqFrance

We investigate the electronic transport in a simple mesoscopic cross structure made of two wires(stubs)grafted at the same point along a quantum *** show that the structure may exhibit important phenomena such as bound in continuum(BIC)*** states are transformed into electromagnetically induced transparency(EIT)resonance by detuning slightly the lengths of the *** last phenomenon is used to propose and study a mesoscopic demultiplexer device with an input waveguide and two output *** give closed-form expressions of the geometrical parameters that allow a selective transfer of a given state in the first waveguide without perturbing the second *** effect of temperature on the transmission resonances is also examined by using Landauer-Büttiker *** analytical results of the dispersion relation and transmission and reflection coefficient are obtained using the Green's function method.

关键词： mesoscopic structure demultiplexer device bound states in continuum(BIC) EIT resonance

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