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A quark nova in the wake of a core-collapse supernova:a unifying model for long duration gamma-ray bursts and fast radio bursts

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Research in Astronomy and Astrophysics 2020年第2期20卷 119-186页

作者： rachid Ouyed Denis Leahy Nico Koning Department of Physics and Astronomy University of Calgary

By appealing to a quark nova(QN;the explosive transition of a neutron star to a quark star) in the wake of a core-collapse supernova(CCSN) explosion of a massive star,we develop a unified model for long duration gamma-ray bursts(LGRBs) and fast radio bursts(FRBs).The time delay(years to decades)between the SN and the QN,and the fragmented nature(i.e.,millions of chunks) of the relativistic QN ejecta are key to yielding a robust LGRB *** our model,an LGRB light curve exhibits the interaction of the fragmented QN ejecta with turbulent(i.e.,filamentary and magnetically saturated) SN ejecta which is shaped by its interaction with an underlying pulsar wind nebula(PWN).The afterglow is due to the interaction of the QN chunks,exiting the SN ejecta,with the surrounding *** model can fit BAT/XRT prompt and afterglow light curves simultaneously with their spectra,thus yielding the observed properties of LGRBs(e.g.,the Band function and the X-ray flares).We find that the peak luminositypeak photon energy relationship(i.e.,the Yonetoku law),and the isotropic energy-peak photon energy relationship(i.e.,the Amati law) are not fundamental but ***-like emission in our model results from coherent synchrotron emission(CSE) when the QN chunks interact with non-turbulent weakly magnetized PWN-SN ejecta,where conditions are prone to the Weibel *** field amplification induced by the Weibel instability in the shocked chunk frame sets the bunching length for electrons and pairs to radiate *** resulting emission frequency,luminosity and duration in our model are consistent with FRB *** find a natural unification of high-energy burst phenomena from FRBs(i.e.,those connected to CCSNe) to LGRBs including X-ray flashes(XRFs) and X-ray rich GRBs(XRR-GRBs) as well as superluminous SNe(SLSNe).We find a possible connection between ultra-high energy cosmic rays and FRBs and propose that a QN following a binary neutron star merger can yiel

关键词： stars:neutron stars:quark pulsars:general supernovae:general gamma-ray burst:general fast radio burst:general

The peculiar case of the “double-humped” super-luminous supernova SN 2006oz

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Research in Astronomy and Astrophysics 2013年第10期13卷 1202-1206页

作者： rachid Ouyed Denis Leahy Department of Physics and Astronomy University of Calgary 2500 University Drive NWCalgaryAlberta T2N 1N4 Canada

SN 2006oz is a super-luminous supernova with a mysterious bright precursor that has resisted explanation in standard ***,such a precursor has been predicted in the dual-shock quark nova model of super-luminous supernovae–the precursor is the supernova event while the main light curve of the super-luminous supernova is powered by the Quark-Nova（explosive transition of the neutron star to a quark star）.As the supernova is fading,the Quark-Nova re-energizes the supernova ejecta,producing a＂double-humped＂light *** show that the quark nova model successfully reproduces the observed light curve of SN 2006oz.

关键词： supernovae:general supernovae:individual(SN 2006oz

Heat transfer of copper/water nanofluid flow through converging-diverging channel

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Journal of Central South University 2016年第2期23卷 484-496页

作者： Mohamed Rafik SARI Mohamed KEZZAR rachid ADJABI Mechanical Engineering Department University of Skikda Industrial Mechanics Laboratory Badji-Mokhtar University of Annaba

The main objective of this work is to investigate analytically the steady nanofluid flow and heat transfer characteristics between nonparallel plane walls. Using appropriate transformations for the velocity and temperature, the basic nonlinear partial differential equations are reduced to the ordinary differential equations. Then, these equations have been solved analytically and numerically for some values of the governing parameters, Reynolds number, Re, channel half angle, α, Prandtl number, Pr, and Eckert number, Ec, using Adomian decomposition method and the Runge-Kutta method with mathematic package. Analytical and numerical results are searched for the skin friction coefficient, Nusselt number and the velocity and temperature profiles. It is found on one hand that the Nusselt number increases as Eckert number or channel half-angle increases, but it decreases as Reynolds number increases. On the other hand, it is also found that the presence of Cu nanoparticles in a water base fluid enhances heat transfer between nonparallel plane walls and in consequence the Nusselt number increases with the increase of nanoparticles volume fraction. Finally, an excellent agreement between analytical results and those obtained by numerical Runge-Kutta method is highly noticed.

关键词： nanofluid flow heat transfer copper nanoparticles inclined walls analytical solution

Impact of Data Quality on Question Answering System Performances

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Intelligent Automation & Soft Computing 2023年第1期35卷 335-349页

作者： rachid Karra Abdelali Lasfar LASTIMI Laboratory Mohammadia School of EngineersMohammed V University in RabatMorocco

In contrast with the research of new models,little attention has been paid to the impact of low or high-quality data feeding a dialogue *** present paper makes thefirst attempt tofill this gap by extending our previous work on question-answering(QA)systems by investigating the effect of misspelling on QA agents and how context changes can enhance the *** of using large language models trained on huge datasets,we propose a method that enhances the model's score by modifying only the quality and structure of the data feed to the *** is important to identify the features that modify the agent performance because a high rate of wrong answers can make the students lose their interest in using the QA agent as an additional tool for distant *** results demonstrate the accuracy of the proposed context simplification exceeds 85%.Thesefindings shed light on the importance of question data quality and context complexity construct as key dimensions of the QA *** conclusion,the experimental results on questions and contexts showed that controlling and improving the various aspects of data quality around the QA system can significantly enhance his robustness and performance.

关键词： DataOps data quality QA system nlp context simplification

Exploring Capillary Fringe Flow:Quasilinear Modeling with Kirchhoff Transforms and Gardner Model

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Fluid Dynamics & Materials Processing 2024年第7期20卷 1611-1631页

作者： rachid Karra Abdelatif Maslouhi LASTIMI Laboratory Mohammadia School of EngineersMohammed V University in RabatRabatMorocco LIRNE Laboratory Faculty of SciencesIbn Tofail UniversityKenitraMorocco

Recent studies have underscored the significance of the capillary fringe in hydrological and biochemical ***,its role in shallow waters is expected to be ***,the study of groundwater flow has centered on unsaturated-saturated zones,often overlooking the impact of the capillary *** this study,we introduce a steady-state two-dimensional model that integrates the capillary fringe into a 2-D numerical *** novel approach employs the potential form of the Richards equation,facilitating the determination of boundaries,pressures,and velocities across different ground surface *** utilized a two-dimensional Freefem++finite element model to compute the stationary *** validation of the model was conducted using experimental *** employed the OFAT(One_Factor-At-Time)method to identify the most sensitive soil parameters and understand how changes in these parameters may affect the behavior and water dynamics of the capillary *** results emphasize the role of hydraulic conductivity as a key parameter influencing capillary fringe shape and *** values within the capillary fringe suggest the prevalence of horizontal *** variation of the water table level and the incoming flow q0,we have shown the correlation between water table elevation and the upper limit of the capillary fringe.

关键词： Capillary fringe Freefem++ gardner model modeling porous media

SN 2009ip and SN 2010mc as dual-shock Quark-Novae

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Research in Astronomy and Astrophysics 2013年第12期13卷 1463-1470页

作者： rachid Ouyed Nico Koning Denis Leahy Department of Physics and Astronomy University of Calgary 2500 University Drive NW

In recent years a number of double-humped supernovae （SNe） have been discovered. This is a feature predicted by the dual-shock Quark-Nova （QN） model where an SN explosion is followed （a few days to a few weeks later） by a QN explo- sion. SN 2009ip and SN 2010mc are the best observed examples of double-humped SNe. Here, we show that the dual-shock QN model naturally explains their light curves including the late time emission, which we attribute to the interaction between the mixed SN and QN ejecta and the surrounding circumstellar matter. Our model applies to any star （O-stars, luminous blue variables, Wolf-Rayet stars, etc.） provided that the mass involved in the SN explosion is ~ 20 Mo which provides good conditions for forming a QN.

关键词： circumstellar matter -- stars: evolution -- stars: winds outflows --supernovae: general -- supernovae: individual (SN 2009ip SN 2010mc)

Efficient fall activity recognition by combining shape and motion features

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Computational Visual Media 2020年第3期6卷 247-263页

作者： Abderrazak Iazzi Mohammed Rziza rachid Oulad Haj Thami LRIT RABAT IT CENTERFaculty of SciencesUniversity of Mohammed 5 in RabatMorocco ADMIR LAB IRDARABAT IT CENTERENSIASUniversity of Mohammed 5 in RabatMorocco

This paper presents a vision-based system for recognizing when elderly adults fall.A fall is characterized by shape deformation and high *** represent shape variation using three features,the aspect ratio of the bounding box,the orientation of an ellipse representing the body,and the aspect ratio of the projection *** motion variation,we extract several features from three blocks corresponding to the head,center of the body,and feet using optical *** each block,we compute the speed and the direction of *** activity is represented by a feature vector constructed from variations in shape and motion features for a set of frames.A support vector machine is used to classify fall and non-fall *** on three different datasets show the effectiveness of our proposed method.

关键词： shape motion features

Existence and numerical approximation of a solution to frictional contact problem for electro-elastic materials

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 201-219页

作者： Othman Baiz EL-Hassan Benkhira rachid Fakhar University Ibn Zohr Lab.ESERFP of OuarzazateMorocco University Moulay Ismail Faculty of SciencesLaboratory MACSESTMBP 3103Toulal-MeknesMorocco University Sultan Moulay Slimane Laboratory LS2MEPolydisciplary Faculty of Khouribga25000 KhouribgaMorocco

In this paper,a frictional contact problem between an electro-elastic body and an electrically conductive foundation is *** contact is modeled by normal compliance with finite penetration and a version of Coulomb’s law of dry friction in which the coefficient of friction depends on the *** addition,the effects of the electrical conductivity of the foundation are taken into *** model leads to a coupled system of the quasi-variational inequality of the elliptic type for the displacement and the nonlinear variational equation for the electric *** existence of a weak solution is proved by using an abstract result for elliptic variational inequalities and a fixed point ***,a finite element approximation of the problem is *** some regularity conditions,an optimal order error estimate of the approximate solution is ***,a successive iteration technique is used to solve the problem numerically and a convergence result is established.

关键词： piezoelectric material frictional contact variational Inequality fixed point process finite element method error estimation iteration method

TWO DISJOINT AND INFINITE SETS OF SOLUTIONS FOR AN ELLIPTIC EQUATION INVOLVING CRITICAL HARDY-SOBOLEV EXPONENTS

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Acta Mathematica Scientia 2023年第5期43卷 2061-2074页

作者： Khalid BOUABID rachid ECHARGHAOUI Mohssine EL MANSOUR Department of Mathematics Faculty of SciencesIbn Tofail UniversityKenitraB.P.133Morocco

In this paper,by an approximating argument,we obtain two disjoint and infinite sets of solutions for the following elliptic equation with critical Hardy-Sobolev exponents■whereΩis a smooth bounded domain in RN with 0∈?Ωand all the principle curvatures of?Ωat 0 are negative,a∈C1(Ω,R*+),μ>0,02(q+1)/(q-1).By2*:=2N/(N-2)and 2*(s):(2(N-s))/(N-2)we denote the critical Sobolev exponent and Hardy-Sobolev exponent,respectively.

关键词： Laplacien critical Sobolev-Hardy exponent critical Sobolev exponent infinitely many solutions Pohozaev identity