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BEST APPROXIMATION FOR WEIERSTRASS TRANSFORM CONNECTED WITH SPHERICAL MEAN OPERATOR

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Acta Mathematica Scientia 2012年第2期32卷 455-470页

作者： L.T.Rachdi N.Msehli Département de Math'ematiques Facult'e des Sciences de Tunis2092 El-ManarTunisia Département de Mathématiques et d'informatique Institut National des Sciences Appliquées et de Technologie de Tunis1080 TunisTunisia

Using reproducing kernels for Hilbert spaces, we give best approximation for Weierstrass transform associated with spherical mean operator. Also, estimates of extremal functions are checked.

关键词： Weierstrass transform spherical mean operator best approximation repro-ducing kernel extremal function

Assessment of ship manoeuvrability by using a coupling between a nonlinear transient manoeuvring model and mathematical programming techniques

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Journal of Hydrodynamics 2013年第5期25卷 788-804页

作者： TRAN KHANH Toan OUAHSINE Abdellatif NACEUR Hakim EL WASSIFI Karima Laboratoire Roberval Université de Technologie de Compiègne Laboratoire LAMIH Université de Valenciennes Université Cadi Ayyad Faculté des Sciences et Techniques

In this paper, a numerical method based on a coupling between a mathematical model of nonlinear transient ship manoeuvring motion in the horizontal plane and Mathematical Programming （MP） techniques is proposed. The aim of the proposed procedure is an efficient estimation of optimal ship hydrodynamic parameters in a dynamic model at the early design stage. The proposed procedure has been validated through turning circle and zigzag manoeuvres based on experimental data of sea trials of the 190 000- dwt oil tanker. Comparisons between experimental and computed data show a good agreement of overall tendency in manoeuvring traiectories.

关键词： ship manoeuvrability hydrodynamics coefficients nonlinear transient dynamics sensitivity analysis mathematical pro- gramming

Analysis of a quasistatic contact problem with adhesion and nonlocal friction for viscoelastic materials

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Applied Mathematics and Mechanics(English Edition) 2010年第5期31卷 623-634页

作者： Arezki TOUZALINE Laboratoire de Systèmes Dynamiques Facult de Mathmatiques Universit des Sciences et de la Technologie Houari Boumediene

A mathematical model is established to describe a contact problem between a deformable body and a foundation. The contact is bilateral and modelled with a nonlocal friction law, in which adhesion is taken into account. Evolution of the bonding field is described by a first-order differential equation. The materials behavior is modelled with a nonlinear viscoelastic constitutive law. A variational formulation of the mechanical problem is derived, and the existence and uniqueness of the weak solution can be proven if the coefficient of friction is sufficiently small. The proof is based on arguments of time-dependent variational inequalities, differential equations, and the Banach fixed-point theorem.

关键词： viscoelastic materials adhesion nonlocal friction fixed point weak solution

Effect of some parameters on the performance of anchor impellers for stirring shear-thinning fluids in a cylindrical vessel

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Journal of Hydrodynamics 2016年第4期28卷 669-675页

作者： Houari AMEUR institut des sciences et technologies Centre Universitaire Salhi Ahmed

The 3-D hydrodynamics of shear thinning fluids in a stirred tank with an anchor impeller were numerically *** using a computational fluid dynamics code（CFX 13.0）,the obtained results give a good prediction of the hydrodynamics such as the velocity fields and cavern *** multiple reference frames（MRF） technique was employed to model the rotation of the *** rheology of the fluid was approximated using the Ostwald *** validate the CFD model,some predicted results were compared with the experimental data and a satisfactory agreement was *** effects of impeller speed,fluid rheology,and some design parameters on the flow pattern,cavern size and power consumption were explored.

关键词： anchor thinning satisfactory rotation frames rheology validate hydrodynamics stirring corner

Exact Solution of D-Dimensional Klein-Gordon Oscillator with Minimal Length

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Communications in Theoretical Physics 2010年第2期53卷 231-236页

作者： Y.Chargui L.Chetouani A.Trabelsi Unit de Recherche de Physique Nuclaire et des Hautes Energies Facult des Sciences de Tunis Dpartement de Physique Thorique Institut de Physique Universit de Constantine Route Ain El Bey Unite de Recherche de Physique Nucleaire et des Hautes Energies Faculte des Sciences de Tunis Centre National des sciences et technologies Nuclaires

Specific modifications of the usual canonical commutation relations between position and momentumoperators have been proposed in the literature in order to implement the idea of the existence of a minimal observablelength. Here, we study a consequence of this proposal in relativistic quantum mechanics by solving in the momentumspace representation the Klein-Gordon oscillator in arbitrary dimensions. The exact bound states spectrum and thecorresponding momentum space wave function are obtained. Following Chang et al. (Phys. Rev. D 65 (2002) 125027),we discuss constraint that can be placed on the minimal length by measuring the energy levels of an electron in a penningtrap.

关键词： Klein-Gordon oscillator minimal length energy spectrum

Stability of Three-Dimensional Interfacial Waves Under Subharmonic Disturbances

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China Ocean Engineering 2023年第4期37卷 558-567页

作者： Nabil ALLALOU Mohammed deBIANE Christian KHARIF Facultéde Physique Universitédes Sciences et de la Technologie Houari Boumediene(USTHB)Algiers 16123Algeria Technopole de Chateau-Gombert Institut de Recherche sur les Phénomènes Hors Equilibre(IRPHE)Marseille 13384France

This study examines the stability regimes of three-dimensional interfacial gravity *** numerical results of the linear stability analysis extend the three-dimensional surface waves results of Ioualalen and Kharif(1994)to three-dimensional interfacial *** approach of the collocation type has been developed for this *** equations of motion are reduced to an eigenvalue problem where the perturbations are spectrally decomposed into normal *** results obtained showed that the density ratio plays a stabilizing *** addition,the dominant instability is of three-dimensional structure,and it belongs to class I for all values of density ratio.

关键词： short-crested interfacial waves linear stability collocation method Padéapproximant

Numerical Simulation of Turbulent Diffusion Flames of a Biogas Enriched with Hydrogen

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Fluid Dynamics & Materials Processing 2024年第1期20卷 79-96页

作者： Naima Krarraz Amina Sabeur Khadidja Safer Ahmed Ouadha Laboratoire des Science et Ingénierie Maritimes Facultéde Génie MécaniqueUniversitédes Sciences et de la Technologie d’Oran Mohamed BoudiafOranAlgérie Laboratoire des Carburants Gazeux et de l’Environnement Facultéde Génie MécaniqueUniversitédes Sciences et de la Laboratoire des Carburants Gazeux et de l’Environneme

Any biogas produced by the anaerobic fermentation of organic materials has the advantage of being an environmentally friendly ***,the relatively low calorific value of such gases makes their effective utilization in practical applications relatively *** present study considers the addition of hydrogen as a potential solution to mitigate this *** particular,the properties of turbulent diffusion jet flames and the related pollutant emissions are investigated numerically for different operating *** related numerical simulations are conducted by solving the RANS equations in the frame of the Reynolds Stress Model in combination with the flamelet *** effects are also taken into account and the combustion kinetics are described via the GRI-Mech 3.0 reaction *** considered hydrogen fuel enrichment spans the range from 0%to 50%in terms of *** varies between 1 and 10 *** results show that both hydrogen addition and pressure increase lead to an improvement in terms of mixing quality and have a significant effect on flame temperature and *** also reduce CO_(2) emissions but increase NOx *** NO is shown to be the predominant NO formation mechanism.

关键词： Biogas hydrogen diffusion flame turbulence NO formation route pressure

3D hydrodynamics involving multiple eccentric impellers in unbaffled cylindrical tank

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Chinese Journal of Chemical Engineering 2016年第5期24卷 572-580页

作者： Houari Ameur institut des sciences et technologies Centre Universitaire Salhi Ahmed CUN-SA

In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely： the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found.

关键词： Computational fluid dynamics Mixing Non-Newtonian fluids Laminar flow Eccentric impeller

Turbulent Double-Diffusive Natural Convection and Entropy Generation within an Inclined Square Cavity

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Fluid Dynamics & Materials Processing 2022年第6期18卷 1619-1629页

作者： Khaled Said Ahmed Ouadha Amina Sabeur Laboratoire des sciences et Ingénierie Maritimes Facultéde Génie MécaniqueUniversitédes Sciences et de la Technologie Mohamed BOUDIAF d’OranOran El-MnouarAlgérie

The present study deals with double-diffusive convection within a two-dimensional inclined cavity filled with an air-CO_(2) binary gas *** left and the right vertical walls are differentially heated and subjected to different locations of(CO_(2))contaminants to allow for the variation of the buoyancy strength(N).However,the horizontal walls are assumed *** simulations are conducted using the finite volume method to solve the conservation equations of continuity,momentum,energy,and species *** agreement with other numerical results in the literature is *** effect of multiple parameters,namely,buoyancy ratio(N),thermal Rayleigh number(Ra),and inclination angle(α)on entropy generation rate is analyzed and discussed in the postprocessing stage,while considering both laminar and turbulent flow *** computations reveal that these parameters considerably affect both the heat and mass transfer performances of the system.

关键词： CFD entropy generation double diffusive convection inclination angle CO_(2) turbulent regime